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Yao
2024-12-20 17:49:45 +08:00
parent 86b0363ce1
commit 654d456c7d
7011 changed files with 1705926 additions and 7 deletions
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98
Pods/abseil/absl/debugging/internal/address_is_readable.cc generated Normal file
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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// base::AddressIsReadable() probes an address to see whether it is readable,
// without faulting.
#include "absl/debugging/internal/address_is_readable.h"
#if !defined(__linux__) || defined(__ANDROID__)
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// On platforms other than Linux, just return true.
bool AddressIsReadable(const void* /* addr */) { return true; }
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#else // __linux__ && !__ANDROID__
#include <stdint.h>
#include <syscall.h>
#include <unistd.h>
#include "absl/base/internal/errno_saver.h"
#include "absl/base/internal/raw_logging.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// NOTE: be extra careful about adding any interposable function calls here
// (such as open(), read(), etc.). These symbols may be interposed and will get
// invoked in contexts they don't expect.
//
// NOTE: any new system calls here may also require sandbox reconfiguration.
//
bool AddressIsReadable(const void *addr) {
// rt_sigprocmask below checks 8 contiguous bytes. If addr resides in the
// last 7 bytes of a page (unaligned), rt_sigprocmask would additionally
// check the readability of the next page, which is not desired. Align
// address on 8-byte boundary to check only the current page.
const uintptr_t u_addr = reinterpret_cast<uintptr_t>(addr) & ~uintptr_t{7};
addr = reinterpret_cast<const void *>(u_addr);
// rt_sigprocmask below will succeed for this input.
if (addr == nullptr) return false;
absl::base_internal::ErrnoSaver errno_saver;
// Here we probe with some syscall which
// - accepts an 8-byte region of user memory as input
// - tests for EFAULT before other validation
// - has no problematic side-effects
//
// rt_sigprocmask(2) works for this. It copies sizeof(kernel_sigset_t)==8
// bytes from the address into the kernel memory before any validation.
//
// The call can never succeed, since the `how` parameter is not one of
// SIG_BLOCK, SIG_UNBLOCK, SIG_SETMASK.
//
// This strategy depends on Linux implementation details,
// so we rely on the test to alert us if it stops working.
//
// Some discarded past approaches:
// - msync() doesn't reject PROT_NONE regions
// - write() on /dev/null doesn't return EFAULT
// - write() on a pipe requires creating it and draining the writes
// - connect() works but is problematic for sandboxes and needs a valid
// file descriptor
//
// This can never succeed (invalid first argument to sigprocmask).
ABSL_RAW_CHECK(syscall(SYS_rt_sigprocmask, ~0, addr, nullptr,
/*sizeof(kernel_sigset_t)*/ 8) == -1,
"unexpected success");
ABSL_RAW_CHECK(errno == EFAULT || errno == EINVAL, "unexpected errno");
return errno != EFAULT;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // __linux__ && !__ANDROID__

32
Pods/abseil/absl/debugging/internal/address_is_readable.h generated Normal file
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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
#define ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
#include "absl/base/config.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// Return whether the byte at *addr is readable, without faulting.
// Save and restores errno.
bool AddressIsReadable(const void *addr);
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_

2012
Pods/abseil/absl/debugging/internal/demangle.cc generated Normal file
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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// For reference check out:
// https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling
//
// Note that we only have partial C++11 support yet.
#include "absl/debugging/internal/demangle.h"
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <limits>
#include <string>
#include "absl/base/config.h"
#if ABSL_INTERNAL_HAS_CXA_DEMANGLE
#include <cxxabi.h>
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
typedef struct {
const char *abbrev;
const char *real_name;
// Number of arguments in <expression> context, or 0 if disallowed.
int arity;
} AbbrevPair;
// List of operators from Itanium C++ ABI.
static const AbbrevPair kOperatorList[] = {
// New has special syntax (not currently supported).
{"nw", "new", 0},
{"na", "new[]", 0},
// Works except that the 'gs' prefix is not supported.
{"dl", "delete", 1},
{"da", "delete[]", 1},
{"ps", "+", 1}, // "positive"
{"ng", "-", 1}, // "negative"
{"ad", "&", 1}, // "address-of"
{"de", "*", 1}, // "dereference"
{"co", "~", 1},
{"pl", "+", 2},
{"mi", "-", 2},
{"ml", "*", 2},
{"dv", "/", 2},
{"rm", "%", 2},
{"an", "&", 2},
{"or", "|", 2},
{"eo", "^", 2},
{"aS", "=", 2},
{"pL", "+=", 2},
{"mI", "-=", 2},
{"mL", "*=", 2},
{"dV", "/=", 2},
{"rM", "%=", 2},
{"aN", "&=", 2},
{"oR", "|=", 2},
{"eO", "^=", 2},
{"ls", "<<", 2},
{"rs", ">>", 2},
{"lS", "<<=", 2},
{"rS", ">>=", 2},
{"eq", "==", 2},
{"ne", "!=", 2},
{"lt", "<", 2},
{"gt", ">", 2},
{"le", "<=", 2},
{"ge", ">=", 2},
{"nt", "!", 1},
{"aa", "&&", 2},
{"oo", "||", 2},
{"pp", "++", 1},
{"mm", "--", 1},
{"cm", ",", 2},
{"pm", "->*", 2},
{"pt", "->", 0}, // Special syntax
{"cl", "()", 0}, // Special syntax
{"ix", "[]", 2},
{"qu", "?", 3},
{"st", "sizeof", 0}, // Special syntax
{"sz", "sizeof", 1}, // Not a real operator name, but used in expressions.
{nullptr, nullptr, 0},
};
// List of builtin types from Itanium C++ ABI.
//
// Invariant: only one- or two-character type abbreviations here.
static const AbbrevPair kBuiltinTypeList[] = {
{"v", "void", 0},
{"w", "wchar_t", 0},
{"b", "bool", 0},
{"c", "char", 0},
{"a", "signed char", 0},
{"h", "unsigned char", 0},
{"s", "short", 0},
{"t", "unsigned short", 0},
{"i", "int", 0},
{"j", "unsigned int", 0},
{"l", "long", 0},
{"m", "unsigned long", 0},
{"x", "long long", 0},
{"y", "unsigned long long", 0},
{"n", "__int128", 0},
{"o", "unsigned __int128", 0},
{"f", "float", 0},
{"d", "double", 0},
{"e", "long double", 0},
{"g", "__float128", 0},
{"z", "ellipsis", 0},
{"De", "decimal128", 0}, // IEEE 754r decimal floating point (128 bits)
{"Dd", "decimal64", 0}, // IEEE 754r decimal floating point (64 bits)
{"Dc", "decltype(auto)", 0},
{"Da", "auto", 0},
{"Dn", "std::nullptr_t", 0}, // i.e., decltype(nullptr)
{"Df", "decimal32", 0}, // IEEE 754r decimal floating point (32 bits)
{"Di", "char32_t", 0},
{"Du", "char8_t", 0},
{"Ds", "char16_t", 0},
{"Dh", "float16", 0}, // IEEE 754r half-precision float (16 bits)
{nullptr, nullptr, 0},
};
// List of substitutions Itanium C++ ABI.
static const AbbrevPair kSubstitutionList[] = {
{"St", "", 0},
{"Sa", "allocator", 0},
{"Sb", "basic_string", 0},
// std::basic_string<char, std::char_traits<char>,std::allocator<char> >
{"Ss", "string", 0},
// std::basic_istream<char, std::char_traits<char> >
{"Si", "istream", 0},
// std::basic_ostream<char, std::char_traits<char> >
{"So", "ostream", 0},
// std::basic_iostream<char, std::char_traits<char> >
{"Sd", "iostream", 0},
{nullptr, nullptr, 0},
};
// State needed for demangling. This struct is copied in almost every stack
// frame, so every byte counts.
typedef struct {
int mangled_idx; // Cursor of mangled name.
int out_cur_idx; // Cursor of output string.
int prev_name_idx; // For constructors/destructors.
unsigned int prev_name_length : 16; // For constructors/destructors.
signed int nest_level : 15; // For nested names.
unsigned int append : 1; // Append flag.
// Note: for some reason MSVC can't pack "bool append : 1" into the same int
// with the above two fields, so we use an int instead. Amusingly it can pack
// "signed bool" as expected, but relying on that to continue to be a legal
// type seems ill-advised (as it's illegal in at least clang).
} ParseState;
static_assert(sizeof(ParseState) == 4 * sizeof(int),
"unexpected size of ParseState");
// One-off state for demangling that's not subject to backtracking -- either
// constant data, data that's intentionally immune to backtracking (steps), or
// data that would never be changed by backtracking anyway (recursion_depth).
//
// Only one copy of this exists for each call to Demangle, so the size of this
// struct is nearly inconsequential.
typedef struct {
const char *mangled_begin; // Beginning of input string.
char *out; // Beginning of output string.
int out_end_idx; // One past last allowed output character.
int recursion_depth; // For stack exhaustion prevention.
int steps; // Cap how much work we'll do, regardless of depth.
ParseState parse_state; // Backtrackable state copied for most frames.
} State;
namespace {
// Prevent deep recursion / stack exhaustion.
// Also prevent unbounded handling of complex inputs.
class ComplexityGuard {
public:
explicit ComplexityGuard(State *state) : state_(state) {
++state->recursion_depth;
++state->steps;
}
~ComplexityGuard() { --state_->recursion_depth; }
// 256 levels of recursion seems like a reasonable upper limit on depth.
// 128 is not enough to demagle synthetic tests from demangle_unittest.txt:
// "_ZaaZZZZ..." and "_ZaaZcvZcvZ..."
static constexpr int kRecursionDepthLimit = 256;
// We're trying to pick a charitable upper-limit on how many parse steps are
// necessary to handle something that a human could actually make use of.
// This is mostly in place as a bound on how much work we'll do if we are
// asked to demangle an mangled name from an untrusted source, so it should be
// much larger than the largest expected symbol, but much smaller than the
// amount of work we can do in, e.g., a second.
//
// Some real-world symbols from an arbitrary binary started failing between
// 2^12 and 2^13, so we multiply the latter by an extra factor of 16 to set
// the limit.
//
// Spending one second on 2^17 parse steps would require each step to take
// 7.6us, or ~30000 clock cycles, so it's safe to say this can be done in
// under a second.
static constexpr int kParseStepsLimit = 1 << 17;
bool IsTooComplex() const {
return state_->recursion_depth > kRecursionDepthLimit ||
state_->steps > kParseStepsLimit;
}
private:
State *state_;
};
} // namespace
// We don't use strlen() in libc since it's not guaranteed to be async
// signal safe.
static size_t StrLen(const char *str) {
size_t len = 0;
while (*str != '\0') {
++str;
++len;
}
return len;
}
// Returns true if "str" has at least "n" characters remaining.
static bool AtLeastNumCharsRemaining(const char *str, size_t n) {
for (size_t i = 0; i < n; ++i) {
if (str[i] == '\0') {
return false;
}
}
return true;
}
// Returns true if "str" has "prefix" as a prefix.
static bool StrPrefix(const char *str, const char *prefix) {
size_t i = 0;
while (str[i] != '\0' && prefix[i] != '\0' && str[i] == prefix[i]) {
++i;
}
return prefix[i] == '\0'; // Consumed everything in "prefix".
}
static void InitState(State* state,
const char* mangled,
char* out,
size_t out_size) {
state->mangled_begin = mangled;
state->out = out;
state->out_end_idx = static_cast<int>(out_size);
state->recursion_depth = 0;
state->steps = 0;
state->parse_state.mangled_idx = 0;
state->parse_state.out_cur_idx = 0;
state->parse_state.prev_name_idx = 0;
state->parse_state.prev_name_length = 0;
state->parse_state.nest_level = -1;
state->parse_state.append = true;
}
static inline const char *RemainingInput(State *state) {
return &state->mangled_begin[state->parse_state.mangled_idx];
}
// Returns true and advances "mangled_idx" if we find "one_char_token"
// at "mangled_idx" position. It is assumed that "one_char_token" does
// not contain '\0'.
static bool ParseOneCharToken(State *state, const char one_char_token) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (RemainingInput(state)[0] == one_char_token) {
++state->parse_state.mangled_idx;
return true;
}
return false;
}
// Returns true and advances "mangled_cur" if we find "two_char_token"
// at "mangled_cur" position. It is assumed that "two_char_token" does
// not contain '\0'.
static bool ParseTwoCharToken(State *state, const char *two_char_token) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (RemainingInput(state)[0] == two_char_token[0] &&
RemainingInput(state)[1] == two_char_token[1]) {
state->parse_state.mangled_idx += 2;
return true;
}
return false;
}
// Returns true and advances "mangled_cur" if we find any character in
// "char_class" at "mangled_cur" position.
static bool ParseCharClass(State *state, const char *char_class) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (RemainingInput(state)[0] == '\0') {
return false;
}
const char *p = char_class;
for (; *p != '\0'; ++p) {
if (RemainingInput(state)[0] == *p) {
++state->parse_state.mangled_idx;
return true;
}
}
return false;
}
static bool ParseDigit(State *state, int *digit) {
char c = RemainingInput(state)[0];
if (ParseCharClass(state, "0123456789")) {
if (digit != nullptr) {
*digit = c - '0';
}
return true;
}
return false;
}
// This function is used for handling an optional non-terminal.
static bool Optional(bool /*status*/) { return true; }
// This function is used for handling <non-terminal>+ syntax.
typedef bool (*ParseFunc)(State *);
static bool OneOrMore(ParseFunc parse_func, State *state) {
if (parse_func(state)) {
while (parse_func(state)) {
}
return true;
}
return false;
}
// This function is used for handling <non-terminal>* syntax. The function
// always returns true and must be followed by a termination token or a
// terminating sequence not handled by parse_func (e.g.
// ParseOneCharToken(state, 'E')).
static bool ZeroOrMore(ParseFunc parse_func, State *state) {
while (parse_func(state)) {
}
return true;
}
// Append "str" at "out_cur_idx". If there is an overflow, out_cur_idx is
// set to out_end_idx+1. The output string is ensured to
// always terminate with '\0' as long as there is no overflow.
static void Append(State *state, const char *const str, const size_t length) {
for (size_t i = 0; i < length; ++i) {
if (state->parse_state.out_cur_idx + 1 <
state->out_end_idx) { // +1 for '\0'
state->out[state->parse_state.out_cur_idx++] = str[i];
} else {
// signal overflow
state->parse_state.out_cur_idx = state->out_end_idx + 1;
break;
}
}
if (state->parse_state.out_cur_idx < state->out_end_idx) {
state->out[state->parse_state.out_cur_idx] =
'\0'; // Terminate it with '\0'
}
}
// We don't use equivalents in libc to avoid locale issues.
static bool IsLower(char c) { return c >= 'a' && c <= 'z'; }
static bool IsAlpha(char c) {
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}
static bool IsDigit(char c) { return c >= '0' && c <= '9'; }
// Returns true if "str" is a function clone suffix. These suffixes are used
// by GCC 4.5.x and later versions (and our locally-modified version of GCC
// 4.4.x) to indicate functions which have been cloned during optimization.
// We treat any sequence (.<alpha>+.<digit>+)+ as a function clone suffix.
// Additionally, '_' is allowed along with the alphanumeric sequence.
static bool IsFunctionCloneSuffix(const char *str) {
size_t i = 0;
while (str[i] != '\0') {
bool parsed = false;
// Consume a single [.<alpha> | _]*[.<digit>]* sequence.
if (str[i] == '.' && (IsAlpha(str[i + 1]) || str[i + 1] == '_')) {
parsed = true;
i += 2;
while (IsAlpha(str[i]) || str[i] == '_') {
++i;
}
}
if (str[i] == '.' && IsDigit(str[i + 1])) {
parsed = true;
i += 2;
while (IsDigit(str[i])) {
++i;
}
}
if (!parsed)
return false;
}
return true; // Consumed everything in "str".
}
static bool EndsWith(State *state, const char chr) {
return state->parse_state.out_cur_idx > 0 &&
state->parse_state.out_cur_idx < state->out_end_idx &&
chr == state->out[state->parse_state.out_cur_idx - 1];
}
// Append "str" with some tweaks, iff "append" state is true.
static void MaybeAppendWithLength(State *state, const char *const str,
const size_t length) {
if (state->parse_state.append && length > 0) {
// Append a space if the output buffer ends with '<' and "str"
// starts with '<' to avoid <<<.
if (str[0] == '<' && EndsWith(state, '<')) {
Append(state, " ", 1);
}
// Remember the last identifier name for ctors/dtors,
// but only if we haven't yet overflown the buffer.
if (state->parse_state.out_cur_idx < state->out_end_idx &&
(IsAlpha(str[0]) || str[0] == '_')) {
state->parse_state.prev_name_idx = state->parse_state.out_cur_idx;
state->parse_state.prev_name_length = static_cast<unsigned int>(length);
}
Append(state, str, length);
}
}
// Appends a positive decimal number to the output if appending is enabled.
static bool MaybeAppendDecimal(State *state, int val) {
// Max {32-64}-bit unsigned int is 20 digits.
constexpr size_t kMaxLength = 20;
char buf[kMaxLength];
// We can't use itoa or sprintf as neither is specified to be
// async-signal-safe.
if (state->parse_state.append) {
// We can't have a one-before-the-beginning pointer, so instead start with
// one-past-the-end and manipulate one character before the pointer.
char *p = &buf[kMaxLength];
do { // val=0 is the only input that should write a leading zero digit.
*--p = static_cast<char>((val % 10) + '0');
val /= 10;
} while (p > buf && val != 0);
// 'p' landed on the last character we set. How convenient.
Append(state, p, kMaxLength - static_cast<size_t>(p - buf));
}
return true;
}
// A convenient wrapper around MaybeAppendWithLength().
// Returns true so that it can be placed in "if" conditions.
static bool MaybeAppend(State *state, const char *const str) {
if (state->parse_state.append) {
size_t length = StrLen(str);
MaybeAppendWithLength(state, str, length);
}
return true;
}
// This function is used for handling nested names.
static bool EnterNestedName(State *state) {
state->parse_state.nest_level = 0;
return true;
}
// This function is used for handling nested names.
static bool LeaveNestedName(State *state, int16_t prev_value) {
state->parse_state.nest_level = prev_value;
return true;
}
// Disable the append mode not to print function parameters, etc.
static bool DisableAppend(State *state) {
state->parse_state.append = false;
return true;
}
// Restore the append mode to the previous state.
static bool RestoreAppend(State *state, bool prev_value) {
state->parse_state.append = prev_value;
return true;
}
// Increase the nest level for nested names.
static void MaybeIncreaseNestLevel(State *state) {
if (state->parse_state.nest_level > -1) {
++state->parse_state.nest_level;
}
}
// Appends :: for nested names if necessary.
static void MaybeAppendSeparator(State *state) {
if (state->parse_state.nest_level >= 1) {
MaybeAppend(state, "::");
}
}
// Cancel the last separator if necessary.
static void MaybeCancelLastSeparator(State *state) {
if (state->parse_state.nest_level >= 1 && state->parse_state.append &&
state->parse_state.out_cur_idx >= 2) {
state->parse_state.out_cur_idx -= 2;
state->out[state->parse_state.out_cur_idx] = '\0';
}
}
// Returns true if the identifier of the given length pointed to by
// "mangled_cur" is anonymous namespace.
static bool IdentifierIsAnonymousNamespace(State *state, size_t length) {
// Returns true if "anon_prefix" is a proper prefix of "mangled_cur".
static const char anon_prefix[] = "_GLOBAL__N_";
return (length > (sizeof(anon_prefix) - 1) &&
StrPrefix(RemainingInput(state), anon_prefix));
}
// Forward declarations of our parsing functions.
static bool ParseMangledName(State *state);
static bool ParseEncoding(State *state);
static bool ParseName(State *state);
static bool ParseUnscopedName(State *state);
static bool ParseNestedName(State *state);
static bool ParsePrefix(State *state);
static bool ParseUnqualifiedName(State *state);
static bool ParseSourceName(State *state);
static bool ParseLocalSourceName(State *state);
static bool ParseUnnamedTypeName(State *state);
static bool ParseNumber(State *state, int *number_out);
static bool ParseFloatNumber(State *state);
static bool ParseSeqId(State *state);
static bool ParseIdentifier(State *state, size_t length);
static bool ParseOperatorName(State *state, int *arity);
static bool ParseSpecialName(State *state);
static bool ParseCallOffset(State *state);
static bool ParseNVOffset(State *state);
static bool ParseVOffset(State *state);
static bool ParseAbiTags(State *state);
static bool ParseCtorDtorName(State *state);
static bool ParseDecltype(State *state);
static bool ParseType(State *state);
static bool ParseCVQualifiers(State *state);
static bool ParseBuiltinType(State *state);
static bool ParseFunctionType(State *state);
static bool ParseBareFunctionType(State *state);
static bool ParseClassEnumType(State *state);
static bool ParseArrayType(State *state);
static bool ParsePointerToMemberType(State *state);
static bool ParseTemplateParam(State *state);
static bool ParseTemplateTemplateParam(State *state);
static bool ParseTemplateArgs(State *state);
static bool ParseTemplateArg(State *state);
static bool ParseBaseUnresolvedName(State *state);
static bool ParseUnresolvedName(State *state);
static bool ParseExpression(State *state);
static bool ParseExprPrimary(State *state);
static bool ParseExprCastValue(State *state);
static bool ParseLocalName(State *state);
static bool ParseLocalNameSuffix(State *state);
static bool ParseDiscriminator(State *state);
static bool ParseSubstitution(State *state, bool accept_std);
// Implementation note: the following code is a straightforward
// translation of the Itanium C++ ABI defined in BNF with a couple of
// exceptions.
//
// - Support GNU extensions not defined in the Itanium C++ ABI
// - <prefix> and <template-prefix> are combined to avoid infinite loop
// - Reorder patterns to shorten the code
// - Reorder patterns to give greedier functions precedence
// We'll mark "Less greedy than" for these cases in the code
//
// Each parsing function changes the parse state and returns true on
// success, or returns false and doesn't change the parse state (note:
// the parse-steps counter increases regardless of success or failure).
// To ensure that the parse state isn't changed in the latter case, we
// save the original state before we call multiple parsing functions
// consecutively with &&, and restore it if unsuccessful. See
// ParseEncoding() as an example of this convention. We follow the
// convention throughout the code.
//
// Originally we tried to do demangling without following the full ABI
// syntax but it turned out we needed to follow the full syntax to
// parse complicated cases like nested template arguments. Note that
// implementing a full-fledged demangler isn't trivial (libiberty's
// cp-demangle.c has +4300 lines).
//
// Note that (foo) in <(foo) ...> is a modifier to be ignored.
//
// Reference:
// - Itanium C++ ABI
// <https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling>
// <mangled-name> ::= _Z <encoding>
static bool ParseMangledName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return ParseTwoCharToken(state, "_Z") && ParseEncoding(state);
}
// <encoding> ::= <(function) name> <bare-function-type>
// ::= <(data) name>
// ::= <special-name>
static bool ParseEncoding(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
// Implementing the first two productions together as <name>
// [<bare-function-type>] avoids exponential blowup of backtracking.
//
// Since Optional(...) can't fail, there's no need to copy the state for
// backtracking.
if (ParseName(state) && Optional(ParseBareFunctionType(state))) {
return true;
}
if (ParseSpecialName(state)) {
return true;
}
return false;
}
// <name> ::= <nested-name>
// ::= <unscoped-template-name> <template-args>
// ::= <unscoped-name>
// ::= <local-name>
static bool ParseName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseNestedName(state) || ParseLocalName(state)) {
return true;
}
// We reorganize the productions to avoid re-parsing unscoped names.
// - Inline <unscoped-template-name> productions:
// <name> ::= <substitution> <template-args>
// ::= <unscoped-name> <template-args>
// ::= <unscoped-name>
// - Merge the two productions that start with unscoped-name:
// <name> ::= <unscoped-name> [<template-args>]
ParseState copy = state->parse_state;
// "std<...>" isn't a valid name.
if (ParseSubstitution(state, /*accept_std=*/false) &&
ParseTemplateArgs(state)) {
return true;
}
state->parse_state = copy;
// Note there's no need to restore state after this since only the first
// subparser can fail.
return ParseUnscopedName(state) && Optional(ParseTemplateArgs(state));
}
// <unscoped-name> ::= <unqualified-name>
// ::= St <unqualified-name>
static bool ParseUnscopedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseUnqualifiedName(state)) {
return true;
}
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "St") && MaybeAppend(state, "std::") &&
ParseUnqualifiedName(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <ref-qualifer> ::= R // lvalue method reference qualifier
// ::= O // rvalue method reference qualifier
static inline bool ParseRefQualifier(State *state) {
return ParseCharClass(state, "OR");
}
// <nested-name> ::= N [<CV-qualifiers>] [<ref-qualifier>] <prefix>
// <unqualified-name> E
// ::= N [<CV-qualifiers>] [<ref-qualifier>] <template-prefix>
// <template-args> E
static bool ParseNestedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'N') && EnterNestedName(state) &&
Optional(ParseCVQualifiers(state)) &&
Optional(ParseRefQualifier(state)) && ParsePrefix(state) &&
LeaveNestedName(state, copy.nest_level) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// This part is tricky. If we literally translate them to code, we'll
// end up infinite loop. Hence we merge them to avoid the case.
//
// <prefix> ::= <prefix> <unqualified-name>
// ::= <template-prefix> <template-args>
// ::= <template-param>
// ::= <substitution>
// ::= # empty
// <template-prefix> ::= <prefix> <(template) unqualified-name>
// ::= <template-param>
// ::= <substitution>
static bool ParsePrefix(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
bool has_something = false;
while (true) {
MaybeAppendSeparator(state);
if (ParseTemplateParam(state) ||
ParseSubstitution(state, /*accept_std=*/true) ||
ParseUnscopedName(state) ||
(ParseOneCharToken(state, 'M') && ParseUnnamedTypeName(state))) {
has_something = true;
MaybeIncreaseNestLevel(state);
continue;
}
MaybeCancelLastSeparator(state);
if (has_something && ParseTemplateArgs(state)) {
return ParsePrefix(state);
} else {
break;
}
}
return true;
}
// <unqualified-name> ::= <operator-name> [<abi-tags>]
// ::= <ctor-dtor-name> [<abi-tags>]
// ::= <source-name> [<abi-tags>]
// ::= <local-source-name> [<abi-tags>]
// ::= <unnamed-type-name> [<abi-tags>]
//
// <local-source-name> is a GCC extension; see below.
static bool ParseUnqualifiedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseOperatorName(state, nullptr) || ParseCtorDtorName(state) ||
ParseSourceName(state) || ParseLocalSourceName(state) ||
ParseUnnamedTypeName(state)) {
return ParseAbiTags(state);
}
return false;
}
// <abi-tags> ::= <abi-tag> [<abi-tags>]
// <abi-tag> ::= B <source-name>
static bool ParseAbiTags(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
while (ParseOneCharToken(state, 'B')) {
ParseState copy = state->parse_state;
MaybeAppend(state, "[abi:");
if (!ParseSourceName(state)) {
state->parse_state = copy;
return false;
}
MaybeAppend(state, "]");
}
return true;
}
// <source-name> ::= <positive length number> <identifier>
static bool ParseSourceName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
int length = -1;
if (ParseNumber(state, &length) &&
ParseIdentifier(state, static_cast<size_t>(length))) {
return true;
}
state->parse_state = copy;
return false;
}
// <local-source-name> ::= L <source-name> [<discriminator>]
//
// References:
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31775
// https://gcc.gnu.org/viewcvs?view=rev&revision=124467
static bool ParseLocalSourceName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'L') && ParseSourceName(state) &&
Optional(ParseDiscriminator(state))) {
return true;
}
state->parse_state = copy;
return false;
}
// <unnamed-type-name> ::= Ut [<(nonnegative) number>] _
// ::= <closure-type-name>
// <closure-type-name> ::= Ul <lambda-sig> E [<(nonnegative) number>] _
// <lambda-sig> ::= <(parameter) type>+
static bool ParseUnnamedTypeName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
// Type's 1-based index n is encoded as { "", n == 1; itoa(n-2), otherwise }.
// Optionally parse the encoded value into 'which' and add 2 to get the index.
int which = -1;
// Unnamed type local to function or class.
if (ParseTwoCharToken(state, "Ut") && Optional(ParseNumber(state, &which)) &&
which <= std::numeric_limits<int>::max() - 2 && // Don't overflow.
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "{unnamed type#");
MaybeAppendDecimal(state, 2 + which);
MaybeAppend(state, "}");
return true;
}
state->parse_state = copy;
// Closure type.
which = -1;
if (ParseTwoCharToken(state, "Ul") && DisableAppend(state) &&
OneOrMore(ParseType, state) && RestoreAppend(state, copy.append) &&
ParseOneCharToken(state, 'E') && Optional(ParseNumber(state, &which)) &&
which <= std::numeric_limits<int>::max() - 2 && // Don't overflow.
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "{lambda()#");
MaybeAppendDecimal(state, 2 + which);
MaybeAppend(state, "}");
return true;
}
state->parse_state = copy;
return false;
}
// <number> ::= [n] <non-negative decimal integer>
// If "number_out" is non-null, then *number_out is set to the value of the
// parsed number on success.
static bool ParseNumber(State *state, int *number_out) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
bool negative = false;
if (ParseOneCharToken(state, 'n')) {
negative = true;
}
const char *p = RemainingInput(state);
uint64_t number = 0;
for (; *p != '\0'; ++p) {
if (IsDigit(*p)) {
number = number * 10 + static_cast<uint64_t>(*p - '0');
} else {
break;
}
}
// Apply the sign with uint64_t arithmetic so overflows aren't UB. Gives
// "incorrect" results for out-of-range inputs, but negative values only
// appear for literals, which aren't printed.
if (negative) {
number = ~number + 1;
}
if (p != RemainingInput(state)) { // Conversion succeeded.
state->parse_state.mangled_idx += p - RemainingInput(state);
if (number_out != nullptr) {
// Note: possibly truncate "number".
*number_out = static_cast<int>(number);
}
return true;
}
return false;
}
// Floating-point literals are encoded using a fixed-length lowercase
// hexadecimal string.
static bool ParseFloatNumber(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
const char *p = RemainingInput(state);
for (; *p != '\0'; ++p) {
if (!IsDigit(*p) && !(*p >= 'a' && *p <= 'f')) {
break;
}
}
if (p != RemainingInput(state)) { // Conversion succeeded.
state->parse_state.mangled_idx += p - RemainingInput(state);
return true;
}
return false;
}
// The <seq-id> is a sequence number in base 36,
// using digits and upper case letters
static bool ParseSeqId(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
const char *p = RemainingInput(state);
for (; *p != '\0'; ++p) {
if (!IsDigit(*p) && !(*p >= 'A' && *p <= 'Z')) {
break;
}
}
if (p != RemainingInput(state)) { // Conversion succeeded.
state->parse_state.mangled_idx += p - RemainingInput(state);
return true;
}
return false;
}
// <identifier> ::= <unqualified source code identifier> (of given length)
static bool ParseIdentifier(State *state, size_t length) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (!AtLeastNumCharsRemaining(RemainingInput(state), length)) {
return false;
}
if (IdentifierIsAnonymousNamespace(state, length)) {
MaybeAppend(state, "(anonymous namespace)");
} else {
MaybeAppendWithLength(state, RemainingInput(state), length);
}
state->parse_state.mangled_idx += length;
return true;
}
// <operator-name> ::= nw, and other two letters cases
// ::= cv <type> # (cast)
// ::= v <digit> <source-name> # vendor extended operator
static bool ParseOperatorName(State *state, int *arity) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (!AtLeastNumCharsRemaining(RemainingInput(state), 2)) {
return false;
}
// First check with "cv" (cast) case.
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "cv") && MaybeAppend(state, "operator ") &&
EnterNestedName(state) && ParseType(state) &&
LeaveNestedName(state, copy.nest_level)) {
if (arity != nullptr) {
*arity = 1;
}
return true;
}
state->parse_state = copy;
// Then vendor extended operators.
if (ParseOneCharToken(state, 'v') && ParseDigit(state, arity) &&
ParseSourceName(state)) {
return true;
}
state->parse_state = copy;
// Other operator names should start with a lower alphabet followed
// by a lower/upper alphabet.
if (!(IsLower(RemainingInput(state)[0]) &&
IsAlpha(RemainingInput(state)[1]))) {
return false;
}
// We may want to perform a binary search if we really need speed.
const AbbrevPair *p;
for (p = kOperatorList; p->abbrev != nullptr; ++p) {
if (RemainingInput(state)[0] == p->abbrev[0] &&
RemainingInput(state)[1] == p->abbrev[1]) {
if (arity != nullptr) {
*arity = p->arity;
}
MaybeAppend(state, "operator");
if (IsLower(*p->real_name)) { // new, delete, etc.
MaybeAppend(state, " ");
}
MaybeAppend(state, p->real_name);
state->parse_state.mangled_idx += 2;
return true;
}
}
return false;
}
// <special-name> ::= TV <type>
// ::= TT <type>
// ::= TI <type>
// ::= TS <type>
// ::= TH <type> # thread-local
// ::= Tc <call-offset> <call-offset> <(base) encoding>
// ::= GV <(object) name>
// ::= T <call-offset> <(base) encoding>
// G++ extensions:
// ::= TC <type> <(offset) number> _ <(base) type>
// ::= TF <type>
// ::= TJ <type>
// ::= GR <name>
// ::= GA <encoding>
// ::= Th <call-offset> <(base) encoding>
// ::= Tv <call-offset> <(base) encoding>
//
// Note: we don't care much about them since they don't appear in
// stack traces. The are special data.
static bool ParseSpecialName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "VTISH") &&
ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "Tc") && ParseCallOffset(state) &&
ParseCallOffset(state) && ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "GV") && ParseName(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'T') && ParseCallOffset(state) &&
ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
// G++ extensions
if (ParseTwoCharToken(state, "TC") && ParseType(state) &&
ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
DisableAppend(state) && ParseType(state)) {
RestoreAppend(state, copy.append);
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "FJ") &&
ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "GR") && ParseName(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "GA") && ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "hv") &&
ParseCallOffset(state) && ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <call-offset> ::= h <nv-offset> _
// ::= v <v-offset> _
static bool ParseCallOffset(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'h') && ParseNVOffset(state) &&
ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'v') && ParseVOffset(state) &&
ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
return false;
}
// <nv-offset> ::= <(offset) number>
static bool ParseNVOffset(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return ParseNumber(state, nullptr);
}
// <v-offset> ::= <(offset) number> _ <(virtual offset) number>
static bool ParseVOffset(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
ParseNumber(state, nullptr)) {
return true;
}
state->parse_state = copy;
return false;
}
// <ctor-dtor-name> ::= C1 | C2 | C3 | CI1 <base-class-type> | CI2
// <base-class-type>
// ::= D0 | D1 | D2
// # GCC extensions: "unified" constructor/destructor. See
// #
// https://github.com/gcc-mirror/gcc/blob/7ad17b583c3643bd4557f29b8391ca7ef08391f5/gcc/cp/mangle.c#L1847
// ::= C4 | D4
static bool ParseCtorDtorName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'C')) {
if (ParseCharClass(state, "1234")) {
const char *const prev_name =
state->out + state->parse_state.prev_name_idx;
MaybeAppendWithLength(state, prev_name,
state->parse_state.prev_name_length);
return true;
} else if (ParseOneCharToken(state, 'I') && ParseCharClass(state, "12") &&
ParseClassEnumType(state)) {
return true;
}
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "0124")) {
const char *const prev_name = state->out + state->parse_state.prev_name_idx;
MaybeAppend(state, "~");
MaybeAppendWithLength(state, prev_name,
state->parse_state.prev_name_length);
return true;
}
state->parse_state = copy;
return false;
}
// <decltype> ::= Dt <expression> E # decltype of an id-expression or class
// # member access (C++0x)
// ::= DT <expression> E # decltype of an expression (C++0x)
static bool ParseDecltype(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "tT") &&
ParseExpression(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <type> ::= <CV-qualifiers> <type>
// ::= P <type> # pointer-to
// ::= R <type> # reference-to
// ::= O <type> # rvalue reference-to (C++0x)
// ::= C <type> # complex pair (C 2000)
// ::= G <type> # imaginary (C 2000)
// ::= U <source-name> <type> # vendor extended type qualifier
// ::= <builtin-type>
// ::= <function-type>
// ::= <class-enum-type> # note: just an alias for <name>
// ::= <array-type>
// ::= <pointer-to-member-type>
// ::= <template-template-param> <template-args>
// ::= <template-param>
// ::= <decltype>
// ::= <substitution>
// ::= Dp <type> # pack expansion of (C++0x)
// ::= Dv <num-elems> _ # GNU vector extension
//
static bool ParseType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
// We should check CV-qualifers, and PRGC things first.
//
// CV-qualifiers overlap with some operator names, but an operator name is not
// valid as a type. To avoid an ambiguity that can lead to exponential time
// complexity, refuse to backtrack the CV-qualifiers.
//
// _Z4aoeuIrMvvE
// => _Z 4aoeuI rM v v E
// aoeu<operator%=, void, void>
// => _Z 4aoeuI r Mv v E
// aoeu<void void::* restrict>
//
// By consuming the CV-qualifiers first, the former parse is disabled.
if (ParseCVQualifiers(state)) {
const bool result = ParseType(state);
if (!result) state->parse_state = copy;
return result;
}
state->parse_state = copy;
// Similarly, these tag characters can overlap with other <name>s resulting in
// two different parse prefixes that land on <template-args> in the same
// place, such as "C3r1xI...". So, disable the "ctor-name = C3" parse by
// refusing to backtrack the tag characters.
if (ParseCharClass(state, "OPRCG")) {
const bool result = ParseType(state);
if (!result) state->parse_state = copy;
return result;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "Dp") && ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'U') && ParseSourceName(state) &&
ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseBuiltinType(state) || ParseFunctionType(state) ||
ParseClassEnumType(state) || ParseArrayType(state) ||
ParsePointerToMemberType(state) || ParseDecltype(state) ||
// "std" on its own isn't a type.
ParseSubstitution(state, /*accept_std=*/false)) {
return true;
}
if (ParseTemplateTemplateParam(state) && ParseTemplateArgs(state)) {
return true;
}
state->parse_state = copy;
// Less greedy than <template-template-param> <template-args>.
if (ParseTemplateParam(state)) {
return true;
}
if (ParseTwoCharToken(state, "Dv") && ParseNumber(state, nullptr) &&
ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
return false;
}
// <CV-qualifiers> ::= [r] [V] [K]
// We don't allow empty <CV-qualifiers> to avoid infinite loop in
// ParseType().
static bool ParseCVQualifiers(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
int num_cv_qualifiers = 0;
num_cv_qualifiers += ParseOneCharToken(state, 'r');
num_cv_qualifiers += ParseOneCharToken(state, 'V');
num_cv_qualifiers += ParseOneCharToken(state, 'K');
return num_cv_qualifiers > 0;
}
// <builtin-type> ::= v, etc. # single-character builtin types
// ::= u <source-name>
// ::= Dd, etc. # two-character builtin types
//
// Not supported:
// ::= DF <number> _ # _FloatN (N bits)
//
static bool ParseBuiltinType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
const AbbrevPair *p;
for (p = kBuiltinTypeList; p->abbrev != nullptr; ++p) {
// Guaranteed only 1- or 2-character strings in kBuiltinTypeList.
if (p->abbrev[1] == '\0') {
if (ParseOneCharToken(state, p->abbrev[0])) {
MaybeAppend(state, p->real_name);
return true;
}
} else if (p->abbrev[2] == '\0' && ParseTwoCharToken(state, p->abbrev)) {
MaybeAppend(state, p->real_name);
return true;
}
}
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'u') && ParseSourceName(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <exception-spec> ::= Do # non-throwing
// exception-specification (e.g.,
// noexcept, throw())
// ::= DO <expression> E # computed (instantiation-dependent)
// noexcept
// ::= Dw <type>+ E # dynamic exception specification
// with instantiation-dependent types
static bool ParseExceptionSpec(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTwoCharToken(state, "Do")) return true;
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "DO") && ParseExpression(state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "Dw") && OneOrMore(ParseType, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <function-type> ::= [exception-spec] F [Y] <bare-function-type> [O] E
static bool ParseFunctionType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (Optional(ParseExceptionSpec(state)) && ParseOneCharToken(state, 'F') &&
Optional(ParseOneCharToken(state, 'Y')) && ParseBareFunctionType(state) &&
Optional(ParseOneCharToken(state, 'O')) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <bare-function-type> ::= <(signature) type>+
static bool ParseBareFunctionType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
DisableAppend(state);
if (OneOrMore(ParseType, state)) {
RestoreAppend(state, copy.append);
MaybeAppend(state, "()");
return true;
}
state->parse_state = copy;
return false;
}
// <class-enum-type> ::= <name>
static bool ParseClassEnumType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return ParseName(state);
}
// <array-type> ::= A <(positive dimension) number> _ <(element) type>
// ::= A [<(dimension) expression>] _ <(element) type>
static bool ParseArrayType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'A') && ParseNumber(state, nullptr) &&
ParseOneCharToken(state, '_') && ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'A') && Optional(ParseExpression(state)) &&
ParseOneCharToken(state, '_') && ParseType(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <pointer-to-member-type> ::= M <(class) type> <(member) type>
static bool ParsePointerToMemberType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'M') && ParseType(state) && ParseType(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <template-param> ::= T_
// ::= T <parameter-2 non-negative number> _
static bool ParseTemplateParam(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTwoCharToken(state, "T_")) {
MaybeAppend(state, "?"); // We don't support template substitutions.
return true;
}
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'T') && ParseNumber(state, nullptr) &&
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "?"); // We don't support template substitutions.
return true;
}
state->parse_state = copy;
return false;
}
// <template-template-param> ::= <template-param>
// ::= <substitution>
static bool ParseTemplateTemplateParam(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return (ParseTemplateParam(state) ||
// "std" on its own isn't a template.
ParseSubstitution(state, /*accept_std=*/false));
}
// <template-args> ::= I <template-arg>+ E
static bool ParseTemplateArgs(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
DisableAppend(state);
if (ParseOneCharToken(state, 'I') && OneOrMore(ParseTemplateArg, state) &&
ParseOneCharToken(state, 'E')) {
RestoreAppend(state, copy.append);
MaybeAppend(state, "<>");
return true;
}
state->parse_state = copy;
return false;
}
// <template-arg> ::= <type>
// ::= <expr-primary>
// ::= J <template-arg>* E # argument pack
// ::= X <expression> E
static bool ParseTemplateArg(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'J') && ZeroOrMore(ParseTemplateArg, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
// There can be significant overlap between the following leading to
// exponential backtracking:
//
// <expr-primary> ::= L <type> <expr-cast-value> E
// e.g. L 2xxIvE 1 E
// <type> ==> <local-source-name> <template-args>
// e.g. L 2xx IvE
//
// This means parsing an entire <type> twice, and <type> can contain
// <template-arg>, so this can generate exponential backtracking. There is
// only overlap when the remaining input starts with "L <source-name>", so
// parse all cases that can start this way jointly to share the common prefix.
//
// We have:
//
// <template-arg> ::= <type>
// ::= <expr-primary>
//
// First, drop all the productions of <type> that must start with something
// other than 'L'. All that's left is <class-enum-type>; inline it.
//
// <type> ::= <nested-name> # starts with 'N'
// ::= <unscoped-name>
// ::= <unscoped-template-name> <template-args>
// ::= <local-name> # starts with 'Z'
//
// Drop and inline again:
//
// <type> ::= <unscoped-name>
// ::= <unscoped-name> <template-args>
// ::= <substitution> <template-args> # starts with 'S'
//
// Merge the first two, inline <unscoped-name>, drop last:
//
// <type> ::= <unqualified-name> [<template-args>]
// ::= St <unqualified-name> [<template-args>] # starts with 'S'
//
// Drop and inline:
//
// <type> ::= <operator-name> [<template-args>] # starts with lowercase
// ::= <ctor-dtor-name> [<template-args>] # starts with 'C' or 'D'
// ::= <source-name> [<template-args>] # starts with digit
// ::= <local-source-name> [<template-args>]
// ::= <unnamed-type-name> [<template-args>] # starts with 'U'
//
// One more time:
//
// <type> ::= L <source-name> [<template-args>]
//
// Likewise with <expr-primary>:
//
// <expr-primary> ::= L <type> <expr-cast-value> E
// ::= LZ <encoding> E # cannot overlap; drop
// ::= L <mangled_name> E # cannot overlap; drop
//
// By similar reasoning as shown above, the only <type>s starting with
// <source-name> are "<source-name> [<template-args>]". Inline this.
//
// <expr-primary> ::= L <source-name> [<template-args>] <expr-cast-value> E
//
// Now inline both of these into <template-arg>:
//
// <template-arg> ::= L <source-name> [<template-args>]
// ::= L <source-name> [<template-args>] <expr-cast-value> E
//
// Merge them and we're done:
// <template-arg>
// ::= L <source-name> [<template-args>] [<expr-cast-value> E]
if (ParseLocalSourceName(state) && Optional(ParseTemplateArgs(state))) {
copy = state->parse_state;
if (ParseExprCastValue(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return true;
}
// Now that the overlapping cases can't reach this code, we can safely call
// both of these.
if (ParseType(state) || ParseExprPrimary(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'X') && ParseExpression(state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <unresolved-type> ::= <template-param> [<template-args>]
// ::= <decltype>
// ::= <substitution>
static inline bool ParseUnresolvedType(State *state) {
// No ComplexityGuard because we don't copy the state in this stack frame.
return (ParseTemplateParam(state) && Optional(ParseTemplateArgs(state))) ||
ParseDecltype(state) || ParseSubstitution(state, /*accept_std=*/false);
}
// <simple-id> ::= <source-name> [<template-args>]
static inline bool ParseSimpleId(State *state) {
// No ComplexityGuard because we don't copy the state in this stack frame.
// Note: <simple-id> cannot be followed by a parameter pack; see comment in
// ParseUnresolvedType.
return ParseSourceName(state) && Optional(ParseTemplateArgs(state));
}
// <base-unresolved-name> ::= <source-name> [<template-args>]
// ::= on <operator-name> [<template-args>]
// ::= dn <destructor-name>
static bool ParseBaseUnresolvedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseSimpleId(state)) {
return true;
}
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "on") && ParseOperatorName(state, nullptr) &&
Optional(ParseTemplateArgs(state))) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "dn") &&
(ParseUnresolvedType(state) || ParseSimpleId(state))) {
return true;
}
state->parse_state = copy;
return false;
}
// <unresolved-name> ::= [gs] <base-unresolved-name>
// ::= sr <unresolved-type> <base-unresolved-name>
// ::= srN <unresolved-type> <unresolved-qualifier-level>+ E
// <base-unresolved-name>
// ::= [gs] sr <unresolved-qualifier-level>+ E
// <base-unresolved-name>
static bool ParseUnresolvedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (Optional(ParseTwoCharToken(state, "gs")) &&
ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "sr") && ParseUnresolvedType(state) &&
ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "sr") && ParseOneCharToken(state, 'N') &&
ParseUnresolvedType(state) &&
OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
if (Optional(ParseTwoCharToken(state, "gs")) &&
ParseTwoCharToken(state, "sr") &&
OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <expression> ::= <1-ary operator-name> <expression>
// ::= <2-ary operator-name> <expression> <expression>
// ::= <3-ary operator-name> <expression> <expression> <expression>
// ::= cl <expression>+ E
// ::= cp <simple-id> <expression>* E # Clang-specific.
// ::= cv <type> <expression> # type (expression)
// ::= cv <type> _ <expression>* E # type (expr-list)
// ::= st <type>
// ::= <template-param>
// ::= <function-param>
// ::= <expr-primary>
// ::= dt <expression> <unresolved-name> # expr.name
// ::= pt <expression> <unresolved-name> # expr->name
// ::= sp <expression> # argument pack expansion
// ::= sr <type> <unqualified-name> <template-args>
// ::= sr <type> <unqualified-name>
// <function-param> ::= fp <(top-level) CV-qualifiers> _
// ::= fp <(top-level) CV-qualifiers> <number> _
// ::= fL <number> p <(top-level) CV-qualifiers> _
// ::= fL <number> p <(top-level) CV-qualifiers> <number> _
static bool ParseExpression(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTemplateParam(state) || ParseExprPrimary(state)) {
return true;
}
ParseState copy = state->parse_state;
// Object/function call expression.
if (ParseTwoCharToken(state, "cl") && OneOrMore(ParseExpression, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
// Clang-specific "cp <simple-id> <expression>* E"
// https://clang.llvm.org/doxygen/ItaniumMangle_8cpp_source.html#l04338
if (ParseTwoCharToken(state, "cp") && ParseSimpleId(state) &&
ZeroOrMore(ParseExpression, state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
// Function-param expression (level 0).
if (ParseTwoCharToken(state, "fp") && Optional(ParseCVQualifiers(state)) &&
Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
// Function-param expression (level 1+).
if (ParseTwoCharToken(state, "fL") && Optional(ParseNumber(state, nullptr)) &&
ParseOneCharToken(state, 'p') && Optional(ParseCVQualifiers(state)) &&
Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
// Parse the conversion expressions jointly to avoid re-parsing the <type> in
// their common prefix. Parsed as:
// <expression> ::= cv <type> <conversion-args>
// <conversion-args> ::= _ <expression>* E
// ::= <expression>
//
// Also don't try ParseOperatorName after seeing "cv", since ParseOperatorName
// also needs to accept "cv <type>" in other contexts.
if (ParseTwoCharToken(state, "cv")) {
if (ParseType(state)) {
ParseState copy2 = state->parse_state;
if (ParseOneCharToken(state, '_') && ZeroOrMore(ParseExpression, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy2;
if (ParseExpression(state)) {
return true;
}
}
} else {
// Parse unary, binary, and ternary operator expressions jointly, taking
// care not to re-parse subexpressions repeatedly. Parse like:
// <expression> ::= <operator-name> <expression>
// [<one-to-two-expressions>]
// <one-to-two-expressions> ::= <expression> [<expression>]
int arity = -1;
if (ParseOperatorName(state, &arity) &&
arity > 0 && // 0 arity => disabled.
(arity < 3 || ParseExpression(state)) &&
(arity < 2 || ParseExpression(state)) &&
(arity < 1 || ParseExpression(state))) {
return true;
}
}
state->parse_state = copy;
// sizeof type
if (ParseTwoCharToken(state, "st") && ParseType(state)) {
return true;
}
state->parse_state = copy;
// Object and pointer member access expressions.
if ((ParseTwoCharToken(state, "dt") || ParseTwoCharToken(state, "pt")) &&
ParseExpression(state) && ParseType(state)) {
return true;
}
state->parse_state = copy;
// Pointer-to-member access expressions. This parses the same as a binary
// operator, but it's implemented separately because "ds" shouldn't be
// accepted in other contexts that parse an operator name.
if (ParseTwoCharToken(state, "ds") && ParseExpression(state) &&
ParseExpression(state)) {
return true;
}
state->parse_state = copy;
// Parameter pack expansion
if (ParseTwoCharToken(state, "sp") && ParseExpression(state)) {
return true;
}
state->parse_state = copy;
return ParseUnresolvedName(state);
}
// <expr-primary> ::= L <type> <(value) number> E
// ::= L <type> <(value) float> E
// ::= L <mangled-name> E
// // A bug in g++'s C++ ABI version 2 (-fabi-version=2).
// ::= LZ <encoding> E
//
// Warning, subtle: the "bug" LZ production above is ambiguous with the first
// production where <type> starts with <local-name>, which can lead to
// exponential backtracking in two scenarios:
//
// - When whatever follows the E in the <local-name> in the first production is
// not a name, we backtrack the whole <encoding> and re-parse the whole thing.
//
// - When whatever follows the <local-name> in the first production is not a
// number and this <expr-primary> may be followed by a name, we backtrack the
// <name> and re-parse it.
//
// Moreover this ambiguity isn't always resolved -- for example, the following
// has two different parses:
//
// _ZaaILZ4aoeuE1x1EvE
// => operator&&<aoeu, x, E, void>
// => operator&&<(aoeu::x)(1), void>
//
// To resolve this, we just do what GCC's demangler does, and refuse to parse
// casts to <local-name> types.
static bool ParseExprPrimary(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
// The "LZ" special case: if we see LZ, we commit to accept "LZ <encoding> E"
// or fail, no backtracking.
if (ParseTwoCharToken(state, "LZ")) {
if (ParseEncoding(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// The merged cast production.
if (ParseOneCharToken(state, 'L') && ParseType(state) &&
ParseExprCastValue(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'L') && ParseMangledName(state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <number> or <float>, followed by 'E', as described above ParseExprPrimary.
static bool ParseExprCastValue(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
// We have to be able to backtrack after accepting a number because we could
// have e.g. "7fffE", which will accept "7" as a number but then fail to find
// the 'E'.
ParseState copy = state->parse_state;
if (ParseNumber(state, nullptr) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
if (ParseFloatNumber(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <local-name> ::= Z <(function) encoding> E <(entity) name> [<discriminator>]
// ::= Z <(function) encoding> E s [<discriminator>]
//
// Parsing a common prefix of these two productions together avoids an
// exponential blowup of backtracking. Parse like:
// <local-name> := Z <encoding> E <local-name-suffix>
// <local-name-suffix> ::= s [<discriminator>]
// ::= <name> [<discriminator>]
static bool ParseLocalNameSuffix(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (MaybeAppend(state, "::") && ParseName(state) &&
Optional(ParseDiscriminator(state))) {
return true;
}
// Since we're not going to overwrite the above "::" by re-parsing the
// <encoding> (whose trailing '\0' byte was in the byte now holding the
// first ':'), we have to rollback the "::" if the <name> parse failed.
if (state->parse_state.append) {
state->out[state->parse_state.out_cur_idx - 2] = '\0';
}
return ParseOneCharToken(state, 's') && Optional(ParseDiscriminator(state));
}
static bool ParseLocalName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'Z') && ParseEncoding(state) &&
ParseOneCharToken(state, 'E') && ParseLocalNameSuffix(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <discriminator> := _ <(non-negative) number>
static bool ParseDiscriminator(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, '_') && ParseNumber(state, nullptr)) {
return true;
}
state->parse_state = copy;
return false;
}
// <substitution> ::= S_
// ::= S <seq-id> _
// ::= St, etc.
//
// "St" is special in that it's not valid as a standalone name, and it *is*
// allowed to precede a name without being wrapped in "N...E". This means that
// if we accept it on its own, we can accept "St1a" and try to parse
// template-args, then fail and backtrack, accept "St" on its own, then "1a" as
// an unqualified name and re-parse the same template-args. To block this
// exponential backtracking, we disable it with 'accept_std=false' in
// problematic contexts.
static bool ParseSubstitution(State *state, bool accept_std) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTwoCharToken(state, "S_")) {
MaybeAppend(state, "?"); // We don't support substitutions.
return true;
}
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'S') && ParseSeqId(state) &&
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "?"); // We don't support substitutions.
return true;
}
state->parse_state = copy;
// Expand abbreviations like "St" => "std".
if (ParseOneCharToken(state, 'S')) {
const AbbrevPair *p;
for (p = kSubstitutionList; p->abbrev != nullptr; ++p) {
if (RemainingInput(state)[0] == p->abbrev[1] &&
(accept_std || p->abbrev[1] != 't')) {
MaybeAppend(state, "std");
if (p->real_name[0] != '\0') {
MaybeAppend(state, "::");
MaybeAppend(state, p->real_name);
}
++state->parse_state.mangled_idx;
return true;
}
}
}
state->parse_state = copy;
return false;
}
// Parse <mangled-name>, optionally followed by either a function-clone suffix
// or version suffix. Returns true only if all of "mangled_cur" was consumed.
static bool ParseTopLevelMangledName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseMangledName(state)) {
if (RemainingInput(state)[0] != '\0') {
// Drop trailing function clone suffix, if any.
if (IsFunctionCloneSuffix(RemainingInput(state))) {
return true;
}
// Append trailing version suffix if any.
// ex. _Z3foo@@GLIBCXX_3.4
if (RemainingInput(state)[0] == '@') {
MaybeAppend(state, RemainingInput(state));
return true;
}
return false; // Unconsumed suffix.
}
return true;
}
return false;
}
static bool Overflowed(const State *state) {
return state->parse_state.out_cur_idx >= state->out_end_idx;
}
// The demangler entry point.
bool Demangle(const char* mangled, char* out, size_t out_size) {
State state;
InitState(&state, mangled, out, out_size);
return ParseTopLevelMangledName(&state) && !Overflowed(&state) &&
state.parse_state.out_cur_idx > 0;
}
std::string DemangleString(const char* mangled) {
std::string out;
int status = 0;
char* demangled = nullptr;
#if ABSL_INTERNAL_HAS_CXA_DEMANGLE
demangled = abi::__cxa_demangle(mangled, nullptr, nullptr, &status);
#endif
if (status == 0 && demangled != nullptr) {
out.append(demangled);
free(demangled);
} else {
out.append(mangled);
}
return out;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl

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Pods/abseil/absl/debugging/internal/demangle.h generated Normal file
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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
#define ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
#include <string>
#include "absl/base/config.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// Demangle `mangled`. On success, return true and write the
// demangled symbol name to `out`. Otherwise, return false.
// `out` is modified even if demangling is unsuccessful.
//
// This function provides an alternative to libstdc++'s abi::__cxa_demangle,
// which is not async signal safe (it uses malloc internally). It's intended to
// be used in async signal handlers to symbolize stack traces.
//
// Note that this demangler doesn't support full demangling. More
// specifically, it doesn't print types of function parameters and
// types of template arguments. It just skips them. However, it's
// still very useful to extract basic information such as class,
// function, constructor, destructor, and operator names.
//
// See the implementation note in demangle.cc if you are interested.
//
// Example:
//
// | Mangled Name | Demangle | DemangleString
// |---------------|-------------|-----------------------
// | _Z1fv | f() | f()
// | _Z1fi | f() | f(int)
// | _Z3foo3bar | foo() | foo(bar)
// | _Z1fIiEvi | f<>() | void f<int>(int)
// | _ZN1N1fE | N::f | N::f
// | _ZN3Foo3BarEv | Foo::Bar() | Foo::Bar()
// | _Zrm1XS_" | operator%() | operator%(X, X)
// | _ZN3FooC1Ev | Foo::Foo() | Foo::Foo()
// | _Z1fSs | f() | f(std::basic_string<char,
// | | | std::char_traits<char>,
// | | | std::allocator<char> >)
//
// See the unit test for more examples.
//
// Note: we might want to write demanglers for ABIs other than Itanium
// C++ ABI in the future.
bool Demangle(const char* mangled, char* out, size_t out_size);
// A wrapper around `abi::__cxa_demangle()`. On success, returns the demangled
// name. On failure, returns the input mangled name.
//
// This function is not async-signal-safe.
std::string DemangleString(const char* mangled);
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Allow dynamic symbol lookup in an in-memory Elf image.
//
#include "absl/debugging/internal/elf_mem_image.h"
#ifdef ABSL_HAVE_ELF_MEM_IMAGE // defined in elf_mem_image.h
#include <string.h>
#include <cassert>
#include <cstddef>
#include "absl/base/config.h"
#include "absl/base/internal/raw_logging.h"
// From binutils/include/elf/common.h (this doesn't appear to be documented
// anywhere else).
//
// /* This flag appears in a Versym structure. It means that the symbol
// is hidden, and is only visible with an explicit version number.
// This is a GNU extension. */
// #define VERSYM_HIDDEN 0x8000
//
// /* This is the mask for the rest of the Versym information. */
// #define VERSYM_VERSION 0x7fff
#define VERSYM_VERSION 0x7fff
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
namespace {
#if __SIZEOF_POINTER__ == 4
const int kElfClass = ELFCLASS32;
int ElfBind(const ElfW(Sym) *symbol) { return ELF32_ST_BIND(symbol->st_info); }
int ElfType(const ElfW(Sym) *symbol) { return ELF32_ST_TYPE(symbol->st_info); }
#elif __SIZEOF_POINTER__ == 8
const int kElfClass = ELFCLASS64;
int ElfBind(const ElfW(Sym) *symbol) { return ELF64_ST_BIND(symbol->st_info); }
int ElfType(const ElfW(Sym) *symbol) { return ELF64_ST_TYPE(symbol->st_info); }
#else
const int kElfClass = -1;
int ElfBind(const ElfW(Sym) *) {
ABSL_RAW_LOG(FATAL, "Unexpected word size");
return 0;
}
int ElfType(const ElfW(Sym) *) {
ABSL_RAW_LOG(FATAL, "Unexpected word size");
return 0;
}
#endif
// Extract an element from one of the ELF tables, cast it to desired type.
// This is just a simple arithmetic and a glorified cast.
// Callers are responsible for bounds checking.
template <typename T>
const T *GetTableElement(const ElfW(Ehdr) * ehdr, ElfW(Off) table_offset,
ElfW(Word) element_size, size_t index) {
return reinterpret_cast<const T*>(reinterpret_cast<const char *>(ehdr)
+ table_offset
+ index * element_size);
}
} // namespace
// The value of this variable doesn't matter; it's used only for its
// unique address.
const int ElfMemImage::kInvalidBaseSentinel = 0;
ElfMemImage::ElfMemImage(const void *base) {
ABSL_RAW_CHECK(base != kInvalidBase, "bad pointer");
Init(base);
}
int ElfMemImage::GetNumSymbols() const {
if (!hash_) {
return 0;
}
// See http://www.caldera.com/developers/gabi/latest/ch5.dynamic.html#hash
return static_cast<int>(hash_[1]);
}
const ElfW(Sym) *ElfMemImage::GetDynsym(int index) const {
ABSL_RAW_CHECK(index < GetNumSymbols(), "index out of range");
return dynsym_ + index;
}
const ElfW(Versym) *ElfMemImage::GetVersym(int index) const {
ABSL_RAW_CHECK(index < GetNumSymbols(), "index out of range");
return versym_ + index;
}
const ElfW(Phdr) *ElfMemImage::GetPhdr(int index) const {
ABSL_RAW_CHECK(index >= 0 && index < ehdr_->e_phnum, "index out of range");
return GetTableElement<ElfW(Phdr)>(ehdr_, ehdr_->e_phoff, ehdr_->e_phentsize,
static_cast<size_t>(index));
}
const char *ElfMemImage::GetDynstr(ElfW(Word) offset) const {
ABSL_RAW_CHECK(offset < strsize_, "offset out of range");
return dynstr_ + offset;
}
const void *ElfMemImage::GetSymAddr(const ElfW(Sym) *sym) const {
if (sym->st_shndx == SHN_UNDEF || sym->st_shndx >= SHN_LORESERVE) {
// Symbol corresponds to "special" (e.g. SHN_ABS) section.
return reinterpret_cast<const void *>(sym->st_value);
}
ABSL_RAW_CHECK(link_base_ < sym->st_value, "symbol out of range");
return GetTableElement<char>(ehdr_, 0, 1, sym->st_value - link_base_);
}
const ElfW(Verdef) *ElfMemImage::GetVerdef(int index) const {
ABSL_RAW_CHECK(0 <= index && static_cast<size_t>(index) <= verdefnum_,
"index out of range");
const ElfW(Verdef) *version_definition = verdef_;
while (version_definition->vd_ndx < index && version_definition->vd_next) {
const char *const version_definition_as_char =
reinterpret_cast<const char *>(version_definition);
version_definition =
reinterpret_cast<const ElfW(Verdef) *>(version_definition_as_char +
version_definition->vd_next);
}
return version_definition->vd_ndx == index ? version_definition : nullptr;
}
const ElfW(Verdaux) *ElfMemImage::GetVerdefAux(
const ElfW(Verdef) *verdef) const {
return reinterpret_cast<const ElfW(Verdaux) *>(verdef+1);
}
const char *ElfMemImage::GetVerstr(ElfW(Word) offset) const {
ABSL_RAW_CHECK(offset < strsize_, "offset out of range");
return dynstr_ + offset;
}
void ElfMemImage::Init(const void *base) {
ehdr_ = nullptr;
dynsym_ = nullptr;
dynstr_ = nullptr;
versym_ = nullptr;
verdef_ = nullptr;
hash_ = nullptr;
strsize_ = 0;
verdefnum_ = 0;
// Sentinel: PT_LOAD .p_vaddr can't possibly be this.
link_base_ = ~ElfW(Addr){0}; // NOLINT(readability/braces)
if (!base) {
return;
}
const char *const base_as_char = reinterpret_cast<const char *>(base);
if (base_as_char[EI_MAG0] != ELFMAG0 || base_as_char[EI_MAG1] != ELFMAG1 ||
base_as_char[EI_MAG2] != ELFMAG2 || base_as_char[EI_MAG3] != ELFMAG3) {
assert(false);
return;
}
int elf_class = base_as_char[EI_CLASS];
if (elf_class != kElfClass) {
assert(false);
return;
}
switch (base_as_char[EI_DATA]) {
case ELFDATA2LSB: {
#ifndef ABSL_IS_LITTLE_ENDIAN
assert(false);
return;
#endif
break;
}
case ELFDATA2MSB: {
#ifndef ABSL_IS_BIG_ENDIAN
assert(false);
return;
#endif
break;
}
default: {
assert(false);
return;
}
}
ehdr_ = reinterpret_cast<const ElfW(Ehdr) *>(base);
const ElfW(Phdr) *dynamic_program_header = nullptr;
for (int i = 0; i < ehdr_->e_phnum; ++i) {
const ElfW(Phdr) *const program_header = GetPhdr(i);
switch (program_header->p_type) {
case PT_LOAD:
if (!~link_base_) {
link_base_ = program_header->p_vaddr;
}
break;
case PT_DYNAMIC:
dynamic_program_header = program_header;
break;
}
}
if (!~link_base_ || !dynamic_program_header) {
assert(false);
// Mark this image as not present. Can not recur infinitely.
Init(nullptr);
return;
}
ptrdiff_t relocation =
base_as_char - reinterpret_cast<const char *>(link_base_);
ElfW(Dyn)* dynamic_entry = reinterpret_cast<ElfW(Dyn)*>(
static_cast<intptr_t>(dynamic_program_header->p_vaddr) + relocation);
for (; dynamic_entry->d_tag != DT_NULL; ++dynamic_entry) {
const auto value =
static_cast<intptr_t>(dynamic_entry->d_un.d_val) + relocation;
switch (dynamic_entry->d_tag) {
case DT_HASH:
hash_ = reinterpret_cast<ElfW(Word) *>(value);
break;
case DT_SYMTAB:
dynsym_ = reinterpret_cast<ElfW(Sym) *>(value);
break;
case DT_STRTAB:
dynstr_ = reinterpret_cast<const char *>(value);
break;
case DT_VERSYM:
versym_ = reinterpret_cast<ElfW(Versym) *>(value);
break;
case DT_VERDEF:
verdef_ = reinterpret_cast<ElfW(Verdef) *>(value);
break;
case DT_VERDEFNUM:
verdefnum_ = static_cast<size_t>(dynamic_entry->d_un.d_val);
break;
case DT_STRSZ:
strsize_ = static_cast<size_t>(dynamic_entry->d_un.d_val);
break;
default:
// Unrecognized entries explicitly ignored.
break;
}
}
if (!hash_ || !dynsym_ || !dynstr_ || !versym_ ||
!verdef_ || !verdefnum_ || !strsize_) {
assert(false); // invalid VDSO
// Mark this image as not present. Can not recur infinitely.
Init(nullptr);
return;
}
}
bool ElfMemImage::LookupSymbol(const char *name,
const char *version,
int type,
SymbolInfo *info_out) const {
for (const SymbolInfo& info : *this) {
if (strcmp(info.name, name) == 0 && strcmp(info.version, version) == 0 &&
ElfType(info.symbol) == type) {
if (info_out) {
*info_out = info;
}
return true;
}
}
return false;
}
bool ElfMemImage::LookupSymbolByAddress(const void *address,
SymbolInfo *info_out) const {
for (const SymbolInfo& info : *this) {
const char *const symbol_start =
reinterpret_cast<const char *>(info.address);
const char *const symbol_end = symbol_start + info.symbol->st_size;
if (symbol_start <= address && address < symbol_end) {
if (info_out) {
// Client wants to know details for that symbol (the usual case).
if (ElfBind(info.symbol) == STB_GLOBAL) {
// Strong symbol; just return it.
*info_out = info;
return true;
} else {
// Weak or local. Record it, but keep looking for a strong one.
*info_out = info;
}
} else {
// Client only cares if there is an overlapping symbol.
return true;
}
}
}
return false;
}
ElfMemImage::SymbolIterator::SymbolIterator(const void *const image, int index)
: index_(index), image_(image) {
}
const ElfMemImage::SymbolInfo *ElfMemImage::SymbolIterator::operator->() const {
return &info_;
}
const ElfMemImage::SymbolInfo& ElfMemImage::SymbolIterator::operator*() const {
return info_;
}
bool ElfMemImage::SymbolIterator::operator==(const SymbolIterator &rhs) const {
return this->image_ == rhs.image_ && this->index_ == rhs.index_;
}
bool ElfMemImage::SymbolIterator::operator!=(const SymbolIterator &rhs) const {
return !(*this == rhs);
}
ElfMemImage::SymbolIterator &ElfMemImage::SymbolIterator::operator++() {
this->Update(1);
return *this;
}
ElfMemImage::SymbolIterator ElfMemImage::begin() const {
SymbolIterator it(this, 0);
it.Update(0);
return it;
}
ElfMemImage::SymbolIterator ElfMemImage::end() const {
return SymbolIterator(this, GetNumSymbols());
}
void ElfMemImage::SymbolIterator::Update(int increment) {
const ElfMemImage *image = reinterpret_cast<const ElfMemImage *>(image_);
ABSL_RAW_CHECK(image->IsPresent() || increment == 0, "");
if (!image->IsPresent()) {
return;
}
index_ += increment;
if (index_ >= image->GetNumSymbols()) {
index_ = image->GetNumSymbols();
return;
}
const ElfW(Sym) *symbol = image->GetDynsym(index_);
const ElfW(Versym) *version_symbol = image->GetVersym(index_);
ABSL_RAW_CHECK(symbol && version_symbol, "");
const char *const symbol_name = image->GetDynstr(symbol->st_name);
#if defined(__NetBSD__)
const int version_index = version_symbol->vs_vers & VERSYM_VERSION;
#else
const ElfW(Versym) version_index = version_symbol[0] & VERSYM_VERSION;
#endif
const ElfW(Verdef) *version_definition = nullptr;
const char *version_name = "";
if (symbol->st_shndx == SHN_UNDEF) {
// Undefined symbols reference DT_VERNEED, not DT_VERDEF, and
// version_index could well be greater than verdefnum_, so calling
// GetVerdef(version_index) may trigger assertion.
} else {
version_definition = image->GetVerdef(version_index);
}
if (version_definition) {
// I am expecting 1 or 2 auxiliary entries: 1 for the version itself,
// optional 2nd if the version has a parent.
ABSL_RAW_CHECK(
version_definition->vd_cnt == 1 || version_definition->vd_cnt == 2,
"wrong number of entries");
const ElfW(Verdaux) *version_aux = image->GetVerdefAux(version_definition);
version_name = image->GetVerstr(version_aux->vda_name);
}
info_.name = symbol_name;
info_.version = version_name;
info_.address = image->GetSymAddr(symbol);
info_.symbol = symbol;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_HAVE_ELF_MEM_IMAGE

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/*
* Copyright 2017 The Abseil Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Allow dynamic symbol lookup for in-memory Elf images.
#ifndef ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
#define ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
// Including this will define the __GLIBC__ macro if glibc is being
// used.
#include <climits>
#include "absl/base/config.h"
// Maybe one day we can rewrite this file not to require the elf
// symbol extensions in glibc, but for right now we need them.
#ifdef ABSL_HAVE_ELF_MEM_IMAGE
#error ABSL_HAVE_ELF_MEM_IMAGE cannot be directly set
#endif
#if defined(__ELF__) && !defined(__OpenBSD__) && !defined(__QNX__) && \
!defined(__native_client__) && !defined(__asmjs__) && \
!defined(__wasm__) && !defined(__HAIKU__) && !defined(__sun) && \
!defined(__VXWORKS__) && !defined(__hexagon__)
#define ABSL_HAVE_ELF_MEM_IMAGE 1
#endif
#ifdef ABSL_HAVE_ELF_MEM_IMAGE
#include <link.h> // for ElfW
#if defined(__FreeBSD__) && !defined(ElfW)
#define ElfW(x) __ElfN(x)
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// An in-memory ELF image (may not exist on disk).
class ElfMemImage {
private:
// Sentinel: there could never be an elf image at &kInvalidBaseSentinel.
static const int kInvalidBaseSentinel;
public:
// Sentinel: there could never be an elf image at this address.
static constexpr const void *const kInvalidBase =
static_cast<const void*>(&kInvalidBaseSentinel);
// Information about a single vdso symbol.
// All pointers are into .dynsym, .dynstr, or .text of the VDSO.
// Do not free() them or modify through them.
struct SymbolInfo {
const char *name; // E.g. "__vdso_getcpu"
const char *version; // E.g. "LINUX_2.6", could be ""
// for unversioned symbol.
const void *address; // Relocated symbol address.
const ElfW(Sym) *symbol; // Symbol in the dynamic symbol table.
};
// Supports iteration over all dynamic symbols.
class SymbolIterator {
public:
friend class ElfMemImage;
const SymbolInfo *operator->() const;
const SymbolInfo &operator*() const;
SymbolIterator& operator++();
bool operator!=(const SymbolIterator &rhs) const;
bool operator==(const SymbolIterator &rhs) const;
private:
SymbolIterator(const void *const image, int index);
void Update(int incr);
SymbolInfo info_;
int index_;
const void *const image_;
};
explicit ElfMemImage(const void *base);
void Init(const void *base);
bool IsPresent() const { return ehdr_ != nullptr; }
const ElfW(Phdr)* GetPhdr(int index) const;
const ElfW(Sym)* GetDynsym(int index) const;
const ElfW(Versym)* GetVersym(int index) const;
const ElfW(Verdef)* GetVerdef(int index) const;
const ElfW(Verdaux)* GetVerdefAux(const ElfW(Verdef) *verdef) const;
const char* GetDynstr(ElfW(Word) offset) const;
const void* GetSymAddr(const ElfW(Sym) *sym) const;
const char* GetVerstr(ElfW(Word) offset) const;
int GetNumSymbols() const;
SymbolIterator begin() const;
SymbolIterator end() const;
// Look up versioned dynamic symbol in the image.
// Returns false if image is not present, or doesn't contain given
// symbol/version/type combination.
// If info_out is non-null, additional details are filled in.
bool LookupSymbol(const char *name, const char *version,
int symbol_type, SymbolInfo *info_out) const;
// Find info about symbol (if any) which overlaps given address.
// Returns true if symbol was found; false if image isn't present
// or doesn't have a symbol overlapping given address.
// If info_out is non-null, additional details are filled in.
bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
private:
const ElfW(Ehdr) *ehdr_;
const ElfW(Sym) *dynsym_;
const ElfW(Versym) *versym_;
const ElfW(Verdef) *verdef_;
const ElfW(Word) *hash_;
const char *dynstr_;
size_t strsize_;
size_t verdefnum_;
ElfW(Addr) link_base_; // Link-time base (p_vaddr of first PT_LOAD).
};
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_HAVE_ELF_MEM_IMAGE
#endif // ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_

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#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
// Generate stack tracer for aarch64
#if defined(__linux__)
#include <signal.h>
#include <sys/mman.h>
#include <ucontext.h>
#include <unistd.h>
#endif
#include <atomic>
#include <cassert>
#include <cstdint>
#include <iostream>
#include <limits>
#include "absl/base/attributes.h"
#include "absl/debugging/internal/address_is_readable.h"
#include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems
#include "absl/debugging/stacktrace.h"
static const size_t kUnknownFrameSize = 0;
// Stack end to use when we don't know the actual stack end
// (effectively just the end of address space).
constexpr uintptr_t kUnknownStackEnd =
std::numeric_limits<size_t>::max() - sizeof(void *);
#if defined(__linux__)
// Returns the address of the VDSO __kernel_rt_sigreturn function, if present.
static const unsigned char* GetKernelRtSigreturnAddress() {
constexpr uintptr_t kImpossibleAddress = 1;
ABSL_CONST_INIT static std::atomic<uintptr_t> memoized{kImpossibleAddress};
uintptr_t address = memoized.load(std::memory_order_relaxed);
if (address != kImpossibleAddress) {
return reinterpret_cast<const unsigned char*>(address);
}
address = reinterpret_cast<uintptr_t>(nullptr);
#ifdef ABSL_HAVE_VDSO_SUPPORT
absl::debugging_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
absl::debugging_internal::VDSOSupport::SymbolInfo symbol_info;
auto lookup = [&](int type) {
return vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.6.39", type,
&symbol_info);
};
if ((!lookup(STT_FUNC) && !lookup(STT_NOTYPE)) ||
symbol_info.address == nullptr) {
// Unexpected: VDSO is present, yet the expected symbol is missing
// or null.
assert(false && "VDSO is present, but doesn't have expected symbol");
} else {
if (reinterpret_cast<uintptr_t>(symbol_info.address) !=
kImpossibleAddress) {
address = reinterpret_cast<uintptr_t>(symbol_info.address);
} else {
assert(false && "VDSO returned invalid address");
}
}
}
#endif
memoized.store(address, std::memory_order_relaxed);
return reinterpret_cast<const unsigned char*>(address);
}
#endif // __linux__
// Compute the size of a stack frame in [low..high). We assume that
// low < high. Return size of kUnknownFrameSize.
template<typename T>
static size_t ComputeStackFrameSize(const T* low,
const T* high) {
const char* low_char_ptr = reinterpret_cast<const char *>(low);
const char* high_char_ptr = reinterpret_cast<const char *>(high);
return low < high ? static_cast<size_t>(high_char_ptr - low_char_ptr)
: kUnknownFrameSize;
}
// Saves stack info that is expensive to calculate to avoid recalculating per frame.
struct StackInfo {
uintptr_t stack_low;
uintptr_t stack_high;
uintptr_t sig_stack_low;
uintptr_t sig_stack_high;
};
static bool InsideSignalStack(void** ptr, const StackInfo* stack_info) {
uintptr_t comparable_ptr = reinterpret_cast<uintptr_t>(ptr);
return (comparable_ptr >= stack_info->sig_stack_low &&
comparable_ptr < stack_info->sig_stack_high);
}
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return null if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING, bool WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void **NextStackFrame(void **old_frame_pointer, const void *uc,
const StackInfo *stack_info) {
void **new_frame_pointer = reinterpret_cast<void**>(*old_frame_pointer);
#if defined(__linux__)
if (WITH_CONTEXT && uc != nullptr) {
// Check to see if next frame's return address is __kernel_rt_sigreturn.
if (old_frame_pointer[1] == GetKernelRtSigreturnAddress()) {
const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
// old_frame_pointer[0] is not suitable for unwinding, look at
// ucontext to discover frame pointer before signal.
void **const pre_signal_frame_pointer =
reinterpret_cast<void **>(ucv->uc_mcontext.regs[29]);
// The most recent signal always needs special handling to find the frame
// pointer, but a nested signal does not. If pre_signal_frame_pointer is
// earlier in the stack than the old_frame_pointer, then use it. If it is
// later, then we have already unwound through it and it needs no special
// handling.
if (pre_signal_frame_pointer >= old_frame_pointer) {
new_frame_pointer = pre_signal_frame_pointer;
}
// Check that alleged frame pointer is actually readable. This is to
// prevent "double fault" in case we hit the first fault due to e.g.
// stack corruption.
if (!absl::debugging_internal::AddressIsReadable(
new_frame_pointer))
return nullptr;
}
}
#endif
// The frame pointer should be 8-byte aligned.
if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 7) != 0)
return nullptr;
// Only check the size if both frames are in the same stack.
if (InsideSignalStack(new_frame_pointer, stack_info) ==
InsideSignalStack(old_frame_pointer, stack_info)) {
// Check frame size. In strict mode, we assume frames to be under
// 100,000 bytes. In non-strict mode, we relax the limit to 1MB.
const size_t max_size = STRICT_UNWINDING ? 100000 : 1000000;
const size_t frame_size =
ComputeStackFrameSize(old_frame_pointer, new_frame_pointer);
if (frame_size == kUnknownFrameSize)
return nullptr;
// A very large frame may mean corrupt memory or an erroneous frame
// pointer. But also maybe just a plain-old large frame. Assume that if the
// frame is within a known stack, then it is valid.
if (frame_size > max_size) {
size_t stack_low = stack_info->stack_low;
size_t stack_high = stack_info->stack_high;
if (InsideSignalStack(new_frame_pointer, stack_info)) {
stack_low = stack_info->sig_stack_low;
stack_high = stack_info->sig_stack_high;
}
if (stack_high < kUnknownStackEnd &&
static_cast<size_t>(getpagesize()) < stack_low) {
const uintptr_t new_fp_u =
reinterpret_cast<uintptr_t>(new_frame_pointer);
// Stack bounds are known.
if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) {
// new_frame_pointer is not within a known stack.
return nullptr;
}
} else {
// Stack bounds are unknown, prefer truncated stack to possible crash.
return nullptr;
}
}
}
return new_frame_pointer;
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
// We count on the bottom frame being this one. See the comment
// at prev_return_address
ABSL_ATTRIBUTE_NOINLINE
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
#ifdef __GNUC__
void **frame_pointer = reinterpret_cast<void**>(__builtin_frame_address(0));
#else
# error reading stack point not yet supported on this platform.
#endif
skip_count++; // Skip the frame for this function.
int n = 0;
// Assume that the first page is not stack.
StackInfo stack_info;
stack_info.stack_low = static_cast<uintptr_t>(getpagesize());
stack_info.stack_high = kUnknownStackEnd;
stack_info.sig_stack_low = stack_info.stack_low;
stack_info.sig_stack_high = kUnknownStackEnd;
// The frame pointer points to low address of a frame. The first 64-bit
// word of a frame points to the next frame up the call chain, which normally
// is just after the high address of the current frame. The second word of
// a frame contains return address of to the caller. To find a pc value
// associated with the current frame, we need to go down a level in the call
// chain. So we remember return the address of the last frame seen. This
// does not work for the first stack frame, which belongs to UnwindImp() but
// we skip the frame for UnwindImp() anyway.
void* prev_return_address = nullptr;
// The nth frame size is the difference between the nth frame pointer and the
// the frame pointer below it in the call chain. There is no frame below the
// leaf frame, but this function is the leaf anyway, and we skip it.
void** prev_frame_pointer = nullptr;
while (frame_pointer && n < max_depth) {
if (skip_count > 0) {
skip_count--;
} else {
result[n] = prev_return_address;
if (IS_STACK_FRAMES) {
sizes[n] = static_cast<int>(
ComputeStackFrameSize(prev_frame_pointer, frame_pointer));
}
n++;
}
prev_return_address = frame_pointer[1];
prev_frame_pointer = frame_pointer;
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example).
// Use the non-strict unwinding rules to produce a stack trace
// that is as complete as possible (even if it contains a few bogus
// entries in some rare cases).
frame_pointer = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(
frame_pointer, ucp, &stack_info);
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int num_dropped_frames = 0;
for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) {
if (skip_count > 0) {
skip_count--;
} else {
num_dropped_frames++;
}
frame_pointer = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(
frame_pointer, ucp, &stack_info);
}
*min_dropped_frames = num_dropped_frames;
}
return n;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return true;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// This is inspired by Craig Silverstein's PowerPC stacktrace code.
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
#include <cstdint>
#include "absl/debugging/stacktrace.h"
// WARNING:
// This only works if all your code is in either ARM or THUMB mode. With
// interworking, the frame pointer of the caller can either be in r11 (ARM
// mode) or r7 (THUMB mode). A callee only saves the frame pointer of its
// mode in a fixed location on its stack frame. If the caller is a different
// mode, there is no easy way to find the frame pointer. It can either be
// still in the designated register or saved on stack along with other callee
// saved registers.
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return nullptr if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING>
static void **NextStackFrame(void **old_sp) {
void **new_sp = (void**) old_sp[-1];
// Check that the transition from frame pointer old_sp to frame
// pointer new_sp isn't clearly bogus
if (STRICT_UNWINDING) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_sp <= old_sp) return nullptr;
// Assume stack frames larger than 100,000 bytes are bogus.
if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return nullptr;
} else {
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_sp == old_sp) return nullptr;
// And allow frames upto about 1MB.
if ((new_sp > old_sp)
&& ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return nullptr;
}
if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return nullptr;
return new_sp;
}
// This ensures that absl::GetStackTrace sets up the Link Register properly.
#ifdef __GNUC__
void StacktraceArmDummyFunction() __attribute__((noinline));
void StacktraceArmDummyFunction() { __asm__ volatile(""); }
#else
# error StacktraceArmDummyFunction() needs to be ported to this platform.
#endif
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void * /* ucp */, int *min_dropped_frames) {
#ifdef __GNUC__
void **sp = reinterpret_cast<void**>(__builtin_frame_address(0));
#else
# error reading stack point not yet supported on this platform.
#endif
// On ARM, the return address is stored in the link register (r14).
// This is not saved on the stack frame of a leaf function. To
// simplify code that reads return addresses, we call a dummy
// function so that the return address of this function is also
// stored in the stack frame. This works at least for gcc.
StacktraceArmDummyFunction();
int n = 0;
while (sp && n < max_depth) {
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example).
// Use the non-strict unwinding rules to produce a stack trace
// that is as complete as possible (even if it contains a few bogus
// entries in some rare cases).
void **next_sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = *sp;
if (IS_STACK_FRAMES) {
if (next_sp > sp) {
sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
} else {
// A frame-size of 0 is used to indicate unknown frame size.
sizes[n] = 0;
}
}
n++;
}
sp = next_sp;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int num_dropped_frames = 0;
for (int j = 0; sp != nullptr && j < kMaxUnwind; j++) {
if (skip_count > 0) {
skip_count--;
} else {
num_dropped_frames++;
}
sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
}
*min_dropped_frames = num_dropped_frames;
}
return n;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return false;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_

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/*
* Copyright 2017 The Abseil Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* Defines ABSL_STACKTRACE_INL_HEADER to the *-inl.h containing
* actual unwinder implementation.
* This header is "private" to stacktrace.cc.
* DO NOT include it into any other files.
*/
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
#include "absl/base/config.h"
#if defined(ABSL_STACKTRACE_INL_HEADER)
#error ABSL_STACKTRACE_INL_HEADER cannot be directly set
#elif defined(_WIN32)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_win32-inl.inc"
#elif defined(__APPLE__)
#ifdef ABSL_HAVE_THREAD_LOCAL
// Thread local support required for UnwindImpl.
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_generic-inl.inc"
#endif // defined(ABSL_HAVE_THREAD_LOCAL)
// Emscripten stacktraces rely on JS. Do not use them in standalone mode.
#elif defined(__EMSCRIPTEN__) && !defined(STANDALONE_WASM)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_emscripten-inl.inc"
#elif defined(__linux__) && !defined(__ANDROID__)
#if defined(NO_FRAME_POINTER) && \
(defined(__i386__) || defined(__x86_64__) || defined(__aarch64__))
// Note: The libunwind-based implementation is not available to open-source
// users.
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_libunwind-inl.inc"
#define STACKTRACE_USES_LIBUNWIND 1
#elif defined(NO_FRAME_POINTER) && defined(__has_include)
#if __has_include(<execinfo.h>)
// Note: When using glibc this may require -funwind-tables to function properly.
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_generic-inl.inc"
#endif // __has_include(<execinfo.h>)
#elif defined(__i386__) || defined(__x86_64__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_x86-inl.inc"
#elif defined(__ppc__) || defined(__PPC__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_powerpc-inl.inc"
#elif defined(__aarch64__)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_aarch64-inl.inc"
#elif defined(__riscv)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_riscv-inl.inc"
#elif defined(__has_include)
#if __has_include(<execinfo.h>)
// Note: When using glibc this may require -funwind-tables to function properly.
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_generic-inl.inc"
#endif // __has_include(<execinfo.h>)
#endif // defined(__has_include)
#endif // defined(__linux__) && !defined(__ANDROID__)
// Fallback to the empty implementation.
#if !defined(ABSL_STACKTRACE_INL_HEADER)
#define ABSL_STACKTRACE_INL_HEADER \
"absl/debugging/internal/stacktrace_unimplemented-inl.inc"
#endif
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Portable implementation - just use glibc
//
// Note: The glibc implementation may cause a call to malloc.
// This can cause a deadlock in HeapProfiler.
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_EMSCRIPTEN_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_EMSCRIPTEN_INL_H_
#include <emscripten.h>
#include <atomic>
#include <cstring>
#include "absl/base/attributes.h"
#include "absl/debugging/stacktrace.h"
extern "C" {
uintptr_t emscripten_stack_snapshot();
uint32_t emscripten_stack_unwind_buffer(uintptr_t pc, void *buffer,
uint32_t depth);
}
// Sometimes, we can try to get a stack trace from within a stack
// trace, which can cause a self-deadlock.
// Protect against such reentrant call by failing to get a stack trace.
//
// We use __thread here because the code here is extremely low level -- it is
// called while collecting stack traces from within malloc and mmap, and thus
// can not call anything which might call malloc or mmap itself.
static __thread int recursive = 0;
// The stack trace function might be invoked very early in the program's
// execution (e.g. from the very first malloc).
// As such, we suppress usage of backtrace during this early stage of execution.
static std::atomic<bool> disable_stacktraces(true); // Disabled until healthy.
// Waiting until static initializers run seems to be late enough.
// This file is included into stacktrace.cc so this will only run once.
ABSL_ATTRIBUTE_UNUSED static int stacktraces_enabler = []() {
// Check if we can even create stacktraces. If not, bail early and leave
// disable_stacktraces set as-is.
// clang-format off
if (!EM_ASM_INT({ return (typeof wasmOffsetConverter !== 'undefined'); })) {
return 0;
}
// clang-format on
disable_stacktraces.store(false, std::memory_order_relaxed);
return 0;
}();
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
if (recursive || disable_stacktraces.load(std::memory_order_relaxed)) {
return 0;
}
++recursive;
static_cast<void>(ucp); // Unused.
constexpr int kStackLength = 64;
void *stack[kStackLength];
int size;
uintptr_t pc = emscripten_stack_snapshot();
size = emscripten_stack_unwind_buffer(pc, stack, kStackLength);
int result_count = size - skip_count;
if (result_count < 0) result_count = 0;
if (result_count > max_depth) result_count = max_depth;
for (int i = 0; i < result_count; i++) result[i] = stack[i + skip_count];
if (IS_STACK_FRAMES) {
// No implementation for finding out the stack frame sizes yet.
memset(sizes, 0, sizeof(*sizes) * result_count);
}
if (min_dropped_frames != nullptr) {
if (size - skip_count - max_depth > 0) {
*min_dropped_frames = size - skip_count - max_depth;
} else {
*min_dropped_frames = 0;
}
}
--recursive;
return result_count;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() { return true; }
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_EMSCRIPTEN_INL_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Portable implementation - just use glibc
//
// Note: The glibc implementation may cause a call to malloc.
// This can cause a deadlock in HeapProfiler.
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
#include <execinfo.h>
#include <atomic>
#include <cstring>
#include "absl/debugging/stacktrace.h"
#include "absl/base/attributes.h"
// Sometimes, we can try to get a stack trace from within a stack
// trace, because we don't block signals inside this code (which would be too
// expensive: the two extra system calls per stack trace do matter here).
// That can cause a self-deadlock.
// Protect against such reentrant call by failing to get a stack trace.
//
// We use __thread here because the code here is extremely low level -- it is
// called while collecting stack traces from within malloc and mmap, and thus
// can not call anything which might call malloc or mmap itself.
static __thread int recursive = 0;
// The stack trace function might be invoked very early in the program's
// execution (e.g. from the very first malloc if using tcmalloc). Also, the
// glibc implementation itself will trigger malloc the first time it is called.
// As such, we suppress usage of backtrace during this early stage of execution.
static std::atomic<bool> disable_stacktraces(true); // Disabled until healthy.
// Waiting until static initializers run seems to be late enough.
// This file is included into stacktrace.cc so this will only run once.
ABSL_ATTRIBUTE_UNUSED static int stacktraces_enabler = []() {
void* unused_stack[1];
// Force the first backtrace to happen early to get the one-time shared lib
// loading (allocation) out of the way. After the first call it is much safer
// to use backtrace from a signal handler if we crash somewhere later.
backtrace(unused_stack, 1);
disable_stacktraces.store(false, std::memory_order_relaxed);
return 0;
}();
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
if (recursive || disable_stacktraces.load(std::memory_order_relaxed)) {
return 0;
}
++recursive;
static_cast<void>(ucp); // Unused.
static const int kStackLength = 64;
void * stack[kStackLength];
int size;
size = backtrace(stack, kStackLength);
skip_count++; // we want to skip the current frame as well
int result_count = size - skip_count;
if (result_count < 0)
result_count = 0;
if (result_count > max_depth)
result_count = max_depth;
for (int i = 0; i < result_count; i++)
result[i] = stack[i + skip_count];
if (IS_STACK_FRAMES) {
// No implementation for finding out the stack frame sizes yet.
memset(sizes, 0, sizeof(*sizes) * static_cast<size_t>(result_count));
}
if (min_dropped_frames != nullptr) {
if (size - skip_count - max_depth > 0) {
*min_dropped_frames = size - skip_count - max_depth;
} else {
*min_dropped_frames = 0;
}
}
--recursive;
return result_count;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return true;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Produce stack trace. I'm guessing (hoping!) the code is much like
// for x86. For apple machines, at least, it seems to be; see
// https://developer.apple.com/documentation/mac/runtimehtml/RTArch-59.html
// https://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
// Linux has similar code: http://patchwork.ozlabs.org/linuxppc/patch?id=8882
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
#if defined(__linux__)
#include <asm/ptrace.h> // for PT_NIP.
#include <ucontext.h> // for ucontext_t
#endif
#include <unistd.h>
#include <cassert>
#include <cstdint>
#include <cstdio>
#include "absl/base/attributes.h"
#include "absl/base/optimization.h"
#include "absl/base/port.h"
#include "absl/debugging/stacktrace.h"
#include "absl/debugging/internal/address_is_readable.h"
#include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems
// Given a stack pointer, return the saved link register value.
// Note that this is the link register for a callee.
static inline void *StacktracePowerPCGetLR(void **sp) {
// PowerPC has 3 main ABIs, which say where in the stack the
// Link Register is. For DARWIN and AIX (used by apple and
// linux ppc64), it's in sp[2]. For SYSV (used by linux ppc),
// it's in sp[1].
#if defined(_CALL_AIX) || defined(_CALL_DARWIN)
return *(sp+2);
#elif defined(_CALL_SYSV)
return *(sp+1);
#elif defined(__APPLE__) || defined(__FreeBSD__) || \
(defined(__linux__) && defined(__PPC64__))
// This check is in case the compiler doesn't define _CALL_AIX/etc.
return *(sp+2);
#elif defined(__linux)
// This check is in case the compiler doesn't define _CALL_SYSV.
return *(sp+1);
#else
#error Need to specify the PPC ABI for your architecture.
#endif
}
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return null if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template<bool STRICT_UNWINDING, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void **NextStackFrame(void **old_sp, const void *uc) {
void **new_sp = (void **) *old_sp;
enum { kStackAlignment = 16 };
// Check that the transition from frame pointer old_sp to frame
// pointer new_sp isn't clearly bogus
if (STRICT_UNWINDING) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_sp <= old_sp) return nullptr;
// Assume stack frames larger than 100,000 bytes are bogus.
if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return nullptr;
} else {
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_sp == old_sp) return nullptr;
// And allow frames upto about 1MB.
if ((new_sp > old_sp)
&& ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return nullptr;
}
if ((uintptr_t)new_sp % kStackAlignment != 0) return nullptr;
#if defined(__linux__)
enum StackTraceKernelSymbolStatus {
kNotInitialized = 0, kAddressValid, kAddressInvalid };
if (IS_WITH_CONTEXT && uc != nullptr) {
static StackTraceKernelSymbolStatus kernel_symbol_status =
kNotInitialized; // Sentinel: not computed yet.
// Initialize with sentinel value: __kernel_rt_sigtramp_rt64 can not
// possibly be there.
static const unsigned char *kernel_sigtramp_rt64_address = nullptr;
if (kernel_symbol_status == kNotInitialized) {
absl::debugging_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
absl::debugging_internal::VDSOSupport::SymbolInfo
sigtramp_rt64_symbol_info;
if (!vdso.LookupSymbol(
"__kernel_sigtramp_rt64", "LINUX_2.6.15",
absl::debugging_internal::VDSOSupport::kVDSOSymbolType,
&sigtramp_rt64_symbol_info) ||
sigtramp_rt64_symbol_info.address == nullptr) {
// Unexpected: VDSO is present, yet the expected symbol is missing
// or null.
assert(false && "VDSO is present, but doesn't have expected symbol");
kernel_symbol_status = kAddressInvalid;
} else {
kernel_sigtramp_rt64_address =
reinterpret_cast<const unsigned char *>(
sigtramp_rt64_symbol_info.address);
kernel_symbol_status = kAddressValid;
}
} else {
kernel_symbol_status = kAddressInvalid;
}
}
if (new_sp != nullptr &&
kernel_symbol_status == kAddressValid &&
StacktracePowerPCGetLR(new_sp) == kernel_sigtramp_rt64_address) {
const ucontext_t* signal_context =
reinterpret_cast<const ucontext_t*>(uc);
void **const sp_before_signal =
#if defined(__PPC64__)
reinterpret_cast<void **>(signal_context->uc_mcontext.gp_regs[PT_R1]);
#else
reinterpret_cast<void **>(
signal_context->uc_mcontext.uc_regs->gregs[PT_R1]);
#endif
// Check that alleged sp before signal is nonnull and is reasonably
// aligned.
if (sp_before_signal != nullptr &&
((uintptr_t)sp_before_signal % kStackAlignment) == 0) {
// Check that alleged stack pointer is actually readable. This is to
// prevent a "double fault" in case we hit the first fault due to e.g.
// a stack corruption.
if (absl::debugging_internal::AddressIsReadable(sp_before_signal)) {
// Alleged stack pointer is readable, use it for further unwinding.
new_sp = sp_before_signal;
}
}
}
}
#endif
return new_sp;
}
// This ensures that absl::GetStackTrace sets up the Link Register properly.
ABSL_ATTRIBUTE_NOINLINE static void AbslStacktracePowerPCDummyFunction() {
ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
void **sp;
// Apple macOS uses an old version of gnu as -- both Darwin 7.9.0 (Panther)
// and Darwin 8.8.1 (Tiger) use as 1.38. This means we have to use a
// different asm syntax. I don't know quite the best way to discriminate
// systems using the old as from the new one; I've gone with __APPLE__.
#ifdef __APPLE__
__asm__ volatile ("mr %0,r1" : "=r" (sp));
#else
__asm__ volatile ("mr %0,1" : "=r" (sp));
#endif
// On PowerPC, the "Link Register" or "Link Record" (LR), is a stack
// entry that holds the return address of the subroutine call (what
// instruction we run after our function finishes). This is the
// same as the stack-pointer of our parent routine, which is what we
// want here. While the compiler will always(?) set up LR for
// subroutine calls, it may not for leaf functions (such as this one).
// This routine forces the compiler (at least gcc) to push it anyway.
AbslStacktracePowerPCDummyFunction();
// The LR save area is used by the callee, so the top entry is bogus.
skip_count++;
int n = 0;
// Unlike ABIs of X86 and ARM, PowerPC ABIs say that return address (in
// the link register) of a function call is stored in the caller's stack
// frame instead of the callee's. When we look for the return address
// associated with a stack frame, we need to make sure that there is a
// caller frame before it. So we call NextStackFrame before entering the
// loop below and check next_sp instead of sp for loop termination.
// The outermost frame is set up by runtimes and it does not have a
// caller frame, so it is skipped.
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example).
// Use the non-strict unwinding rules to produce a stack trace
// that is as complete as possible (even if it contains a few
// bogus entries in some rare cases).
void **next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
while (next_sp && n < max_depth) {
if (skip_count > 0) {
skip_count--;
} else {
result[n] = StacktracePowerPCGetLR(sp);
if (IS_STACK_FRAMES) {
if (next_sp > sp) {
sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
} else {
// A frame-size of 0 is used to indicate unknown frame size.
sizes[n] = 0;
}
}
n++;
}
sp = next_sp;
next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 1000;
int num_dropped_frames = 0;
for (int j = 0; next_sp != nullptr && j < kMaxUnwind; j++) {
if (skip_count > 0) {
skip_count--;
} else {
num_dropped_frames++;
}
next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(next_sp, ucp);
}
*min_dropped_frames = num_dropped_frames;
}
return n;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return true;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_

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// Copyright 2021 The Abseil Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_RISCV_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_RISCV_INL_H_
// Generate stack trace for riscv
#include <sys/ucontext.h>
#include "absl/base/config.h"
#if defined(__linux__)
#include <sys/mman.h>
#include <ucontext.h>
#include <unistd.h>
#endif
#include <atomic>
#include <cassert>
#include <cstdint>
#include <iostream>
#include <limits>
#include <utility>
#include "absl/base/attributes.h"
#include "absl/debugging/stacktrace.h"
static const uintptr_t kUnknownFrameSize = 0;
// Compute the size of a stack frame in [low..high). We assume that low < high.
// Return size of kUnknownFrameSize.
template <typename T>
static inline uintptr_t ComputeStackFrameSize(const T *low, const T *high) {
const char *low_char_ptr = reinterpret_cast<const char *>(low);
const char *high_char_ptr = reinterpret_cast<const char *>(high);
return low < high ? high_char_ptr - low_char_ptr : kUnknownFrameSize;
}
// Given a pointer to a stack frame, locate and return the calling stackframe,
// or return null if no stackframe can be found. Perform sanity checks (the
// strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template <bool STRICT_UNWINDING, bool WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void ** NextStackFrame(void **old_frame_pointer, const void *uc,
const std::pair<size_t, size_t> range) {
// .
// .
// .
// +-> +----------------+
// | | return address |
// | | previous fp |
// | | ... |
// | +----------------+ <-+
// | | return address | |
// +---|- previous fp | |
// | ... | |
// $fp ->|----------------+ |
// | return address | |
// | previous fp -|---+
// $sp ->| ... |
// +----------------+
void **new_frame_pointer = reinterpret_cast<void **>(old_frame_pointer[-2]);
uintptr_t frame_pointer = reinterpret_cast<uintptr_t>(new_frame_pointer);
// The RISCV ELF psABI mandates that the stack pointer is always 16-byte
// aligned.
// TODO(#1236) this doesn't hold for ILP32E which only mandates a 4-byte
// alignment.
if (frame_pointer & 15)
return nullptr;
// If the new frame pointer matches the signal context, avoid terminating
// early to deal with alternate signal stacks.
if (WITH_CONTEXT)
if (const ucontext_t *ucv = static_cast<const ucontext_t *>(uc))
// RISCV ELF psABI has the frame pointer at x8/fp/s0.
// -- RISCV psABI Table 18.2
if (ucv->uc_mcontext.__gregs[8] == frame_pointer)
return new_frame_pointer;
// Check frame size. In strict mode, we assume frames to be under 100,000
// bytes. In non-strict mode, we relax the limit to 1MB.
const uintptr_t max_size = STRICT_UNWINDING ? 100000 : 1000000;
const uintptr_t frame_size =
ComputeStackFrameSize(old_frame_pointer, new_frame_pointer);
if (frame_size == kUnknownFrameSize) {
if (STRICT_UNWINDING)
return nullptr;
// In non-strict mode permit non-contiguous stacks (e.g. alternate signal
// frame handling).
if (reinterpret_cast<uintptr_t>(new_frame_pointer) < range.first ||
reinterpret_cast<uintptr_t>(new_frame_pointer) > range.second)
return nullptr;
}
if (frame_size > max_size)
return nullptr;
return new_frame_pointer;
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
// The `frame_pointer` that is computed here points to the top of the frame.
// The two words preceding the address are the return address and the previous
// frame pointer.
#if defined(__GNUC__)
void **frame_pointer = reinterpret_cast<void **>(__builtin_frame_address(0));
#else
#error reading stack pointer not yet supported on this platform
#endif
std::pair<size_t, size_t> stack = {
// assume that the first page is not the stack.
static_cast<size_t>(sysconf(_SC_PAGESIZE)),
std::numeric_limits<size_t>::max() - sizeof(void *)
};
int n = 0;
void *return_address = nullptr;
while (frame_pointer && n < max_depth) {
return_address = frame_pointer[-1];
// The absl::GetStackFrames routine is called when we are in some
// informational context (the failure signal handler for example). Use the
// non-strict unwinding rules to produce a stack trace that is as complete
// as possible (even if it contains a few bogus entries in some rare cases).
void **next_frame_pointer =
NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp,
stack);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = return_address;
if (IS_STACK_FRAMES) {
sizes[n] = ComputeStackFrameSize(frame_pointer, next_frame_pointer);
}
n++;
}
frame_pointer = next_frame_pointer;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int num_dropped_frames = 0;
for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) {
if (skip_count > 0) {
skip_count--;
} else {
num_dropped_frames++;
}
frame_pointer =
NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp,
stack);
}
*min_dropped_frames = num_dropped_frames;
}
return n;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() { return true; }
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif

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#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** /* result */, int* /* sizes */,
int /* max_depth */, int /* skip_count */,
const void* /* ucp */, int *min_dropped_frames) {
if (min_dropped_frames != nullptr) {
*min_dropped_frames = 0;
}
return 0;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return false;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Produces a stack trace for Windows. Normally, one could use
// stacktrace_x86-inl.h or stacktrace_x86_64-inl.h -- and indeed, that
// should work for binaries compiled using MSVC in "debug" mode.
// However, in "release" mode, Windows uses frame-pointer
// optimization, which makes getting a stack trace very difficult.
//
// There are several approaches one can take. One is to use Windows
// intrinsics like StackWalk64. These can work, but have restrictions
// on how successful they can be. Another attempt is to write a
// version of stacktrace_x86-inl.h that has heuristic support for
// dealing with FPO, similar to what WinDbg does (see
// http://www.nynaeve.net/?p=97). There are (non-working) examples of
// these approaches, complete with TODOs, in stacktrace_win32-inl.h#1
//
// The solution we've ended up doing is to call the undocumented
// windows function RtlCaptureStackBackTrace, which probably doesn't
// work with FPO but at least is fast, and doesn't require a symbol
// server.
//
// This code is inspired by a patch from David Vitek:
// https://code.google.com/p/google-perftools/issues/detail?id=83
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
#include <windows.h> // for GetProcAddress and GetModuleHandle
#include <cassert>
typedef USHORT NTAPI RtlCaptureStackBackTrace_Function(
IN ULONG frames_to_skip,
IN ULONG frames_to_capture,
OUT PVOID *backtrace,
OUT PULONG backtrace_hash);
// It is not possible to load RtlCaptureStackBackTrace at static init time in
// UWP. CaptureStackBackTrace is the public version of RtlCaptureStackBackTrace
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) && \
!WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn =
&::CaptureStackBackTrace;
#else
// Load the function we need at static init time, where we don't have
// to worry about someone else holding the loader's lock.
static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn =
(RtlCaptureStackBackTrace_Function*)GetProcAddress(
GetModuleHandleA("ntdll.dll"), "RtlCaptureStackBackTrace");
#endif // WINAPI_PARTITION_APP && !WINAPI_PARTITION_DESKTOP
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
const void*, int* min_dropped_frames) {
USHORT n = 0;
if (!RtlCaptureStackBackTrace_fn || skip_count < 0 || max_depth < 0) {
// can't get a stacktrace with no function/invalid args
} else {
n = RtlCaptureStackBackTrace_fn(static_cast<ULONG>(skip_count) + 2,
static_cast<ULONG>(max_depth), result, 0);
}
if (IS_STACK_FRAMES) {
// No implementation for finding out the stack frame sizes yet.
memset(sizes, 0, sizeof(*sizes) * n);
}
if (min_dropped_frames != nullptr) {
// Not implemented.
*min_dropped_frames = 0;
}
return n;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return false;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Produce stack trace
#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
#if defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
#include <ucontext.h> // for ucontext_t
#endif
#if !defined(_WIN32)
#include <unistd.h>
#endif
#include <cassert>
#include <cstdint>
#include <limits>
#include "absl/base/attributes.h"
#include "absl/base/macros.h"
#include "absl/base/port.h"
#include "absl/debugging/internal/address_is_readable.h"
#include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems
#include "absl/debugging/stacktrace.h"
using absl::debugging_internal::AddressIsReadable;
#if defined(__linux__) && defined(__i386__)
// Count "push %reg" instructions in VDSO __kernel_vsyscall(),
// preceding "syscall" or "sysenter".
// If __kernel_vsyscall uses frame pointer, answer 0.
//
// kMaxBytes tells how many instruction bytes of __kernel_vsyscall
// to analyze before giving up. Up to kMaxBytes+1 bytes of
// instructions could be accessed.
//
// Here are known __kernel_vsyscall instruction sequences:
//
// SYSENTER (linux-2.6.26/arch/x86/vdso/vdso32/sysenter.S).
// Used on Intel.
// 0xffffe400 <__kernel_vsyscall+0>: push %ecx
// 0xffffe401 <__kernel_vsyscall+1>: push %edx
// 0xffffe402 <__kernel_vsyscall+2>: push %ebp
// 0xffffe403 <__kernel_vsyscall+3>: mov %esp,%ebp
// 0xffffe405 <__kernel_vsyscall+5>: sysenter
//
// SYSCALL (see linux-2.6.26/arch/x86/vdso/vdso32/syscall.S).
// Used on AMD.
// 0xffffe400 <__kernel_vsyscall+0>: push %ebp
// 0xffffe401 <__kernel_vsyscall+1>: mov %ecx,%ebp
// 0xffffe403 <__kernel_vsyscall+3>: syscall
//
// The sequence below isn't actually expected in Google fleet,
// here only for completeness. Remove this comment from OSS release.
// i386 (see linux-2.6.26/arch/x86/vdso/vdso32/int80.S)
// 0xffffe400 <__kernel_vsyscall+0>: int $0x80
// 0xffffe401 <__kernel_vsyscall+1>: ret
//
static const int kMaxBytes = 10;
// We use assert()s instead of DCHECK()s -- this is too low level
// for DCHECK().
static int CountPushInstructions(const unsigned char *const addr) {
int result = 0;
for (int i = 0; i < kMaxBytes; ++i) {
if (addr[i] == 0x89) {
// "mov reg,reg"
if (addr[i + 1] == 0xE5) {
// Found "mov %esp,%ebp".
return 0;
}
++i; // Skip register encoding byte.
} else if (addr[i] == 0x0F &&
(addr[i + 1] == 0x34 || addr[i + 1] == 0x05)) {
// Found "sysenter" or "syscall".
return result;
} else if ((addr[i] & 0xF0) == 0x50) {
// Found "push %reg".
++result;
} else if (addr[i] == 0xCD && addr[i + 1] == 0x80) {
// Found "int $0x80"
assert(result == 0);
return 0;
} else {
// Unexpected instruction.
assert(false && "unexpected instruction in __kernel_vsyscall");
return 0;
}
}
// Unexpected: didn't find SYSENTER or SYSCALL in
// [__kernel_vsyscall, __kernel_vsyscall + kMaxBytes) interval.
assert(false && "did not find SYSENTER or SYSCALL in __kernel_vsyscall");
return 0;
}
#endif
// Assume stack frames larger than 100,000 bytes are bogus.
static const int kMaxFrameBytes = 100000;
// Stack end to use when we don't know the actual stack end
// (effectively just the end of address space).
constexpr uintptr_t kUnknownStackEnd =
std::numeric_limits<size_t>::max() - sizeof(void *);
// Returns the stack frame pointer from signal context, 0 if unknown.
// vuc is a ucontext_t *. We use void* to avoid the use
// of ucontext_t on non-POSIX systems.
static uintptr_t GetFP(const void *vuc) {
#if !defined(__linux__)
static_cast<void>(vuc); // Avoid an unused argument compiler warning.
#else
if (vuc != nullptr) {
auto *uc = reinterpret_cast<const ucontext_t *>(vuc);
#if defined(__i386__)
const auto bp = uc->uc_mcontext.gregs[REG_EBP];
const auto sp = uc->uc_mcontext.gregs[REG_ESP];
#elif defined(__x86_64__)
const auto bp = uc->uc_mcontext.gregs[REG_RBP];
const auto sp = uc->uc_mcontext.gregs[REG_RSP];
#else
const uintptr_t bp = 0;
const uintptr_t sp = 0;
#endif
// Sanity-check that the base pointer is valid. It's possible that some
// code in the process is compiled with --copt=-fomit-frame-pointer or
// --copt=-momit-leaf-frame-pointer.
//
// TODO(bcmills): -momit-leaf-frame-pointer is currently the default
// behavior when building with clang. Talk to the C++ toolchain team about
// fixing that.
if (bp >= sp && bp - sp <= kMaxFrameBytes)
return static_cast<uintptr_t>(bp);
// If bp isn't a plausible frame pointer, return the stack pointer instead.
// If we're lucky, it points to the start of a stack frame; otherwise, we'll
// get one frame of garbage in the stack trace and fail the sanity check on
// the next iteration.
return static_cast<uintptr_t>(sp);
}
#endif
return 0;
}
// Given a pointer to a stack frame, locate and return the calling
// stackframe, or return null if no stackframe can be found. Perform sanity
// checks (the strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template <bool STRICT_UNWINDING, bool WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void **NextStackFrame(void **old_fp, const void *uc,
size_t stack_low, size_t stack_high) {
void **new_fp = (void **)*old_fp;
#if defined(__linux__) && defined(__i386__)
if (WITH_CONTEXT && uc != nullptr) {
// How many "push %reg" instructions are there at __kernel_vsyscall?
// This is constant for a given kernel and processor, so compute
// it only once.
static int num_push_instructions = -1; // Sentinel: not computed yet.
// Initialize with sentinel value: __kernel_rt_sigreturn can not possibly
// be there.
static const unsigned char *kernel_rt_sigreturn_address = nullptr;
static const unsigned char *kernel_vsyscall_address = nullptr;
if (num_push_instructions == -1) {
#ifdef ABSL_HAVE_VDSO_SUPPORT
absl::debugging_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
absl::debugging_internal::VDSOSupport::SymbolInfo
rt_sigreturn_symbol_info;
absl::debugging_internal::VDSOSupport::SymbolInfo vsyscall_symbol_info;
if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.5", STT_FUNC,
&rt_sigreturn_symbol_info) ||
!vdso.LookupSymbol("__kernel_vsyscall", "LINUX_2.5", STT_FUNC,
&vsyscall_symbol_info) ||
rt_sigreturn_symbol_info.address == nullptr ||
vsyscall_symbol_info.address == nullptr) {
// Unexpected: 32-bit VDSO is present, yet one of the expected
// symbols is missing or null.
assert(false && "VDSO is present, but doesn't have expected symbols");
num_push_instructions = 0;
} else {
kernel_rt_sigreturn_address =
reinterpret_cast<const unsigned char *>(
rt_sigreturn_symbol_info.address);
kernel_vsyscall_address =
reinterpret_cast<const unsigned char *>(
vsyscall_symbol_info.address);
num_push_instructions =
CountPushInstructions(kernel_vsyscall_address);
}
} else {
num_push_instructions = 0;
}
#else // ABSL_HAVE_VDSO_SUPPORT
num_push_instructions = 0;
#endif // ABSL_HAVE_VDSO_SUPPORT
}
if (num_push_instructions != 0 && kernel_rt_sigreturn_address != nullptr &&
old_fp[1] == kernel_rt_sigreturn_address) {
const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
// This kernel does not use frame pointer in its VDSO code,
// and so %ebp is not suitable for unwinding.
void **const reg_ebp =
reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_EBP]);
const unsigned char *const reg_eip =
reinterpret_cast<unsigned char *>(ucv->uc_mcontext.gregs[REG_EIP]);
if (new_fp == reg_ebp && kernel_vsyscall_address <= reg_eip &&
reg_eip - kernel_vsyscall_address < kMaxBytes) {
// We "stepped up" to __kernel_vsyscall, but %ebp is not usable.
// Restore from 'ucv' instead.
void **const reg_esp =
reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_ESP]);
// Check that alleged %esp is not null and is reasonably aligned.
if (reg_esp &&
((uintptr_t)reg_esp & (sizeof(reg_esp) - 1)) == 0) {
// Check that alleged %esp is actually readable. This is to prevent
// "double fault" in case we hit the first fault due to e.g. stack
// corruption.
void *const reg_esp2 = reg_esp[num_push_instructions - 1];
if (AddressIsReadable(reg_esp2)) {
// Alleged %esp is readable, use it for further unwinding.
new_fp = reinterpret_cast<void **>(reg_esp2);
}
}
}
}
}
#endif
const uintptr_t old_fp_u = reinterpret_cast<uintptr_t>(old_fp);
const uintptr_t new_fp_u = reinterpret_cast<uintptr_t>(new_fp);
// Check that the transition from frame pointer old_fp to frame
// pointer new_fp isn't clearly bogus. Skip the checks if new_fp
// matches the signal context, so that we don't skip out early when
// using an alternate signal stack.
//
// TODO(bcmills): The GetFP call should be completely unnecessary when
// ENABLE_COMBINED_UNWINDER is set (because we should be back in the thread's
// stack by this point), but it is empirically still needed (e.g. when the
// stack includes a call to abort). unw_get_reg returns UNW_EBADREG for some
// frames. Figure out why GetValidFrameAddr and/or libunwind isn't doing what
// it's supposed to.
if (STRICT_UNWINDING &&
(!WITH_CONTEXT || uc == nullptr || new_fp_u != GetFP(uc))) {
// With the stack growing downwards, older stack frame must be
// at a greater address that the current one.
if (new_fp_u <= old_fp_u) return nullptr;
// If we get a very large frame size, it may be an indication that we
// guessed frame pointers incorrectly and now risk a paging fault
// dereferencing a wrong frame pointer. Or maybe not because large frames
// are possible as well. The main stack is assumed to be readable,
// so we assume the large frame is legit if we know the real stack bounds
// and are within the stack.
if (new_fp_u - old_fp_u > kMaxFrameBytes) {
if (stack_high < kUnknownStackEnd &&
static_cast<size_t>(getpagesize()) < stack_low) {
// Stack bounds are known.
if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) {
// new_fp_u is not within the known stack.
return nullptr;
}
} else {
// Stack bounds are unknown, prefer truncated stack to possible crash.
return nullptr;
}
}
if (stack_low < old_fp_u && old_fp_u <= stack_high) {
// Old BP was in the expected stack region...
if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) {
// ... but new BP is outside of expected stack region.
// It is most likely bogus.
return nullptr;
}
} else {
// We may be here if we are executing in a co-routine with a
// separate stack. We can't do safety checks in this case.
}
} else {
if (new_fp == nullptr) return nullptr; // skip AddressIsReadable() below
// In the non-strict mode, allow discontiguous stack frames.
// (alternate-signal-stacks for example).
if (new_fp == old_fp) return nullptr;
}
if (new_fp_u & (sizeof(void *) - 1)) return nullptr;
#ifdef __i386__
// On 32-bit machines, the stack pointer can be very close to
// 0xffffffff, so we explicitly check for a pointer into the
// last two pages in the address space
if (new_fp_u >= 0xffffe000) return nullptr;
#endif
#if !defined(_WIN32)
if (!STRICT_UNWINDING) {
// Lax sanity checks cause a crash in 32-bit tcmalloc/crash_reason_test
// on AMD-based machines with VDSO-enabled kernels.
// Make an extra sanity check to insure new_fp is readable.
// Note: NextStackFrame<false>() is only called while the program
// is already on its last leg, so it's ok to be slow here.
if (!AddressIsReadable(new_fp)) {
return nullptr;
}
}
#endif
return new_fp;
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
ABSL_ATTRIBUTE_NOINLINE
static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
int n = 0;
void **fp = reinterpret_cast<void **>(__builtin_frame_address(0));
// Assume that the first page is not stack.
size_t stack_low = static_cast<size_t>(getpagesize());
size_t stack_high = kUnknownStackEnd;
while (fp && n < max_depth) {
if (*(fp + 1) == reinterpret_cast<void *>(0)) {
// In 64-bit code, we often see a frame that
// points to itself and has a return address of 0.
break;
}
void **next_fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(
fp, ucp, stack_low, stack_high);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = *(fp + 1);
if (IS_STACK_FRAMES) {
if (next_fp > fp) {
sizes[n] = static_cast<int>(
reinterpret_cast<uintptr_t>(next_fp) -
reinterpret_cast<uintptr_t>(fp));
} else {
// A frame-size of 0 is used to indicate unknown frame size.
sizes[n] = 0;
}
}
n++;
}
fp = next_fp;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 1000;
int num_dropped_frames = 0;
for (int j = 0; fp != nullptr && j < kMaxUnwind; j++) {
if (skip_count > 0) {
skip_count--;
} else {
num_dropped_frames++;
}
fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp, stack_low,
stack_high);
}
*min_dropped_frames = num_dropped_frames;
}
return n;
}
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() {
return true;
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// This file contains internal parts of the Abseil symbolizer.
// Do not depend on the anything in this file, it may change at anytime.
#ifndef ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_
#define ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_
#ifdef __cplusplus
#include <cstddef>
#include <cstdint>
#include "absl/base/config.h"
#include "absl/strings/string_view.h"
#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
#error ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE cannot be directly set
#elif defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) \
&& !defined(__asmjs__) && !defined(__wasm__)
#define ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE 1
#include <elf.h>
#include <link.h> // For ElfW() macro.
#include <functional>
#include <string>
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// Iterates over all sections, invoking callback on each with the section name
// and the section header.
//
// Returns true on success; otherwise returns false in case of errors.
//
// This is not async-signal-safe.
bool ForEachSection(int fd,
const std::function<bool(absl::string_view name,
const ElfW(Shdr) &)>& callback);
// Gets the section header for the given name, if it exists. Returns true on
// success. Otherwise, returns false.
bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
ElfW(Shdr) *out);
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
#ifdef ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE
#error ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE cannot be directly set
#elif defined(__APPLE__)
#define ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE 1
#endif
#ifdef ABSL_INTERNAL_HAVE_EMSCRIPTEN_SYMBOLIZE
#error ABSL_INTERNAL_HAVE_EMSCRIPTEN_SYMBOLIZE cannot be directly set
#elif defined(__EMSCRIPTEN__)
#define ABSL_INTERNAL_HAVE_EMSCRIPTEN_SYMBOLIZE 1
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
struct SymbolDecoratorArgs {
// The program counter we are getting symbolic name for.
const void *pc;
// 0 for main executable, load address for shared libraries.
ptrdiff_t relocation;
// Read-only file descriptor for ELF image covering "pc",
// or -1 if no such ELF image exists in /proc/self/maps.
int fd;
// Output buffer, size.
// Note: the buffer may not be empty -- default symbolizer may have already
// produced some output, and earlier decorators may have adorned it in
// some way. You are free to replace or augment the contents (within the
// symbol_buf_size limit).
char *const symbol_buf;
size_t symbol_buf_size;
// Temporary scratch space, size.
// Use that space in preference to allocating your own stack buffer to
// conserve stack.
char *const tmp_buf;
size_t tmp_buf_size;
// User-provided argument
void* arg;
};
using SymbolDecorator = void (*)(const SymbolDecoratorArgs *);
// Installs a function-pointer as a decorator. Returns a value less than zero
// if the system cannot install the decorator. Otherwise, returns a unique
// identifier corresponding to the decorator. This identifier can be used to
// uninstall the decorator - See RemoveSymbolDecorator() below.
int InstallSymbolDecorator(SymbolDecorator decorator, void* arg);
// Removes a previously installed function-pointer decorator. Parameter "ticket"
// is the return-value from calling InstallSymbolDecorator().
bool RemoveSymbolDecorator(int ticket);
// Remove all installed decorators. Returns true if successful, false if
// symbolization is currently in progress.
bool RemoveAllSymbolDecorators();
// Registers an address range to a file mapping.
//
// Preconditions:
// start <= end
// filename != nullptr
//
// Returns true if the file was successfully registered.
bool RegisterFileMappingHint(const void* start, const void* end,
uint64_t offset, const char* filename);
// Looks up the file mapping registered by RegisterFileMappingHint for an
// address range. If there is one, the file name is stored in *filename and
// *start and *end are modified to reflect the registered mapping. Returns
// whether any hint was found.
bool GetFileMappingHint(const void** start, const void** end, uint64_t* offset,
const char** filename);
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // __cplusplus
#include <stdbool.h>
#ifdef __cplusplus
extern "C"
#endif // __cplusplus
bool
AbslInternalGetFileMappingHint(const void** start, const void** end,
uint64_t* offset, const char** filename);
#endif // ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Allow dynamic symbol lookup in the kernel VDSO page.
//
// VDSOSupport -- a class representing kernel VDSO (if present).
#include "absl/debugging/internal/vdso_support.h"
#ifdef ABSL_HAVE_VDSO_SUPPORT // defined in vdso_support.h
#if !defined(__has_include)
#define __has_include(header) 0
#endif
#include <errno.h>
#include <fcntl.h>
#if __has_include(<syscall.h>)
#include <syscall.h>
#elif __has_include(<sys/syscall.h>)
#include <sys/syscall.h>
#endif
#include <unistd.h>
#if !defined(__UCLIBC__) && defined(__GLIBC__) && \
(__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 16))
#define ABSL_HAVE_GETAUXVAL
#endif
#ifdef ABSL_HAVE_GETAUXVAL
#include <sys/auxv.h>
#endif
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/port.h"
#ifndef AT_SYSINFO_EHDR
#define AT_SYSINFO_EHDR 33 // for crosstoolv10
#endif
#if defined(__NetBSD__)
using Elf32_auxv_t = Aux32Info;
using Elf64_auxv_t = Aux64Info;
#endif
#if defined(__FreeBSD__)
#if defined(__ELF_WORD_SIZE) && __ELF_WORD_SIZE == 64
using Elf64_auxv_t = Elf64_Auxinfo;
#endif
using Elf32_auxv_t = Elf32_Auxinfo;
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
ABSL_CONST_INIT
std::atomic<const void *> VDSOSupport::vdso_base_(
debugging_internal::ElfMemImage::kInvalidBase);
ABSL_CONST_INIT std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(
&InitAndGetCPU);
VDSOSupport::VDSOSupport()
// If vdso_base_ is still set to kInvalidBase, we got here
// before VDSOSupport::Init has been called. Call it now.
: image_(vdso_base_.load(std::memory_order_relaxed) ==
debugging_internal::ElfMemImage::kInvalidBase
? Init()
: vdso_base_.load(std::memory_order_relaxed)) {}
// NOTE: we can't use GoogleOnceInit() below, because we can be
// called by tcmalloc, and none of the *once* stuff may be functional yet.
//
// In addition, we hope that the VDSOSupportHelper constructor
// causes this code to run before there are any threads, and before
// InitGoogle() has executed any chroot or setuid calls.
//
// Finally, even if there is a race here, it is harmless, because
// the operation should be idempotent.
const void *VDSOSupport::Init() {
const auto kInvalidBase = debugging_internal::ElfMemImage::kInvalidBase;
#ifdef ABSL_HAVE_GETAUXVAL
if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
errno = 0;
const void *const sysinfo_ehdr =
reinterpret_cast<const void *>(getauxval(AT_SYSINFO_EHDR));
if (errno == 0) {
vdso_base_.store(sysinfo_ehdr, std::memory_order_relaxed);
}
}
#endif // ABSL_HAVE_GETAUXVAL
if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
int fd = open("/proc/self/auxv", O_RDONLY);
if (fd == -1) {
// Kernel too old to have a VDSO.
vdso_base_.store(nullptr, std::memory_order_relaxed);
getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
return nullptr;
}
ElfW(auxv_t) aux;
while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
if (aux.a_type == AT_SYSINFO_EHDR) {
#if defined(__NetBSD__)
vdso_base_.store(reinterpret_cast<void *>(aux.a_v),
std::memory_order_relaxed);
#else
vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val),
std::memory_order_relaxed);
#endif
break;
}
}
close(fd);
if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
// Didn't find AT_SYSINFO_EHDR in auxv[].
vdso_base_.store(nullptr, std::memory_order_relaxed);
}
}
GetCpuFn fn = &GetCPUViaSyscall; // default if VDSO not present.
if (vdso_base_.load(std::memory_order_relaxed)) {
VDSOSupport vdso;
SymbolInfo info;
if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
fn = reinterpret_cast<GetCpuFn>(const_cast<void *>(info.address));
}
}
// Subtle: this code runs outside of any locks; prevent compiler
// from assigning to getcpu_fn_ more than once.
getcpu_fn_.store(fn, std::memory_order_relaxed);
return vdso_base_.load(std::memory_order_relaxed);
}
const void *VDSOSupport::SetBase(const void *base) {
ABSL_RAW_CHECK(base != debugging_internal::ElfMemImage::kInvalidBase,
"internal error");
const void *old_base = vdso_base_.load(std::memory_order_relaxed);
vdso_base_.store(base, std::memory_order_relaxed);
image_.Init(base);
// Also reset getcpu_fn_, so GetCPU could be tested with simulated VDSO.
getcpu_fn_.store(&InitAndGetCPU, std::memory_order_relaxed);
return old_base;
}
bool VDSOSupport::LookupSymbol(const char *name,
const char *version,
int type,
SymbolInfo *info) const {
return image_.LookupSymbol(name, version, type, info);
}
bool VDSOSupport::LookupSymbolByAddress(const void *address,
SymbolInfo *info_out) const {
return image_.LookupSymbolByAddress(address, info_out);
}
// NOLINT on 'long' because this routine mimics kernel api.
long VDSOSupport::GetCPUViaSyscall(unsigned *cpu, // NOLINT(runtime/int)
void *, void *) {
#ifdef SYS_getcpu
return syscall(SYS_getcpu, cpu, nullptr, nullptr);
#else
// x86_64 never implemented sys_getcpu(), except as a VDSO call.
static_cast<void>(cpu); // Avoid an unused argument compiler warning.
errno = ENOSYS;
return -1;
#endif
}
// Use fast __vdso_getcpu if available.
long VDSOSupport::InitAndGetCPU(unsigned *cpu, // NOLINT(runtime/int)
void *x, void *y) {
Init();
GetCpuFn fn = getcpu_fn_.load(std::memory_order_relaxed);
ABSL_RAW_CHECK(fn != &InitAndGetCPU, "Init() did not set getcpu_fn_");
return (*fn)(cpu, x, y);
}
// This function must be very fast, and may be called from very
// low level (e.g. tcmalloc). Hence I avoid things like
// GoogleOnceInit() and ::operator new.
ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY
int GetCPU() {
unsigned cpu;
long ret_code = // NOLINT(runtime/int)
(*VDSOSupport::getcpu_fn_)(&cpu, nullptr, nullptr);
return ret_code == 0 ? static_cast<int>(cpu) : static_cast<int>(ret_code);
}
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_HAVE_VDSO_SUPPORT

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//
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Allow dynamic symbol lookup in the kernel VDSO page.
//
// VDSO stands for "Virtual Dynamic Shared Object" -- a page of
// executable code, which looks like a shared library, but doesn't
// necessarily exist anywhere on disk, and which gets mmap()ed into
// every process by kernels which support VDSO, such as 2.6.x for 32-bit
// executables, and 2.6.24 and above for 64-bit executables.
//
// More details could be found here:
// http://www.trilithium.com/johan/2005/08/linux-gate/
//
// VDSOSupport -- a class representing kernel VDSO (if present).
//
// Example usage:
// VDSOSupport vdso;
// VDSOSupport::SymbolInfo info;
// typedef (*FN)(unsigned *, void *, void *);
// FN fn = nullptr;
// if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
// fn = reinterpret_cast<FN>(info.address);
// }
#ifndef ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_
#define ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_
#include <atomic>
#include "absl/base/attributes.h"
#include "absl/debugging/internal/elf_mem_image.h"
#ifdef ABSL_HAVE_ELF_MEM_IMAGE
#ifdef ABSL_HAVE_VDSO_SUPPORT
#error ABSL_HAVE_VDSO_SUPPORT cannot be directly set
#else
#define ABSL_HAVE_VDSO_SUPPORT 1
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
// NOTE: this class may be used from within tcmalloc, and can not
// use any memory allocation routines.
class VDSOSupport {
public:
VDSOSupport();
typedef ElfMemImage::SymbolInfo SymbolInfo;
typedef ElfMemImage::SymbolIterator SymbolIterator;
// On PowerPC64 VDSO symbols can either be of type STT_FUNC or STT_NOTYPE
// depending on how the kernel is built. The kernel is normally built with
// STT_NOTYPE type VDSO symbols. Let's make things simpler first by using a
// compile-time constant.
#ifdef __powerpc64__
enum { kVDSOSymbolType = STT_NOTYPE };
#else
enum { kVDSOSymbolType = STT_FUNC };
#endif
// Answers whether we have a vdso at all.
bool IsPresent() const { return image_.IsPresent(); }
// Allow to iterate over all VDSO symbols.
SymbolIterator begin() const { return image_.begin(); }
SymbolIterator end() const { return image_.end(); }
// Look up versioned dynamic symbol in the kernel VDSO.
// Returns false if VDSO is not present, or doesn't contain given
// symbol/version/type combination.
// If info_out != nullptr, additional details are filled in.
bool LookupSymbol(const char *name, const char *version,
int symbol_type, SymbolInfo *info_out) const;
// Find info about symbol (if any) which overlaps given address.
// Returns true if symbol was found; false if VDSO isn't present
// or doesn't have a symbol overlapping given address.
// If info_out != nullptr, additional details are filled in.
bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
// Used only for testing. Replace real VDSO base with a mock.
// Returns previous value of vdso_base_. After you are done testing,
// you are expected to call SetBase() with previous value, in order to
// reset state to the way it was.
const void *SetBase(const void *s);
// Computes vdso_base_ and returns it. Should be called as early as
// possible; before any thread creation, chroot or setuid.
static const void *Init();
private:
// image_ represents VDSO ELF image in memory.
// image_.ehdr_ == nullptr implies there is no VDSO.
ElfMemImage image_;
// Cached value of auxv AT_SYSINFO_EHDR, computed once.
// This is a tri-state:
// kInvalidBase => value hasn't been determined yet.
// 0 => there is no VDSO.
// else => vma of VDSO Elf{32,64}_Ehdr.
//
// When testing with mock VDSO, low bit is set.
// The low bit is always available because vdso_base_ is
// page-aligned.
static std::atomic<const void *> vdso_base_;
// NOLINT on 'long' because these routines mimic kernel api.
// The 'cache' parameter may be used by some versions of the kernel,
// and should be nullptr or point to a static buffer containing at
// least two 'long's.
static long InitAndGetCPU(unsigned *cpu, void *cache, // NOLINT 'long'.
void *unused);
static long GetCPUViaSyscall(unsigned *cpu, void *cache, // NOLINT 'long'.
void *unused);
typedef long (*GetCpuFn)(unsigned *cpu, void *cache, // NOLINT 'long'.
void *unused);
// This function pointer may point to InitAndGetCPU,
// GetCPUViaSyscall, or __vdso_getcpu at different stages of initialization.
ABSL_CONST_INIT static std::atomic<GetCpuFn> getcpu_fn_;
friend int GetCPU(void); // Needs access to getcpu_fn_.
VDSOSupport(const VDSOSupport&) = delete;
VDSOSupport& operator=(const VDSOSupport&) = delete;
};
// Same as sched_getcpu() on later glibc versions.
// Return current CPU, using (fast) __vdso_getcpu@LINUX_2.6 if present,
// otherwise use syscall(SYS_getcpu,...).
// May return -1 with errno == ENOSYS if the kernel doesn't
// support SYS_getcpu.
int GetCPU();
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_HAVE_ELF_MEM_IMAGE
#endif // ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Produce stack trace.
//
// There are three different ways we can try to get the stack trace:
//
// 1) Our hand-coded stack-unwinder. This depends on a certain stack
// layout, which is used by gcc (and those systems using a
// gcc-compatible ABI) on x86 systems, at least since gcc 2.95.
// It uses the frame pointer to do its work.
//
// 2) The libunwind library. This is still in development, and as a
// separate library adds a new dependency, but doesn't need a frame
// pointer. It also doesn't call malloc.
//
// 3) The gdb unwinder -- also the one used by the c++ exception code.
// It's obviously well-tested, but has a fatal flaw: it can call
// malloc() from the unwinder. This is a problem because we're
// trying to use the unwinder to instrument malloc().
//
// Note: if you add a new implementation here, make sure it works
// correctly when absl::GetStackTrace() is called with max_depth == 0.
// Some code may do that.
#include "absl/debugging/stacktrace.h"
#include <atomic>
#include "absl/base/attributes.h"
#include "absl/base/port.h"
#include "absl/debugging/internal/stacktrace_config.h"
#if defined(ABSL_STACKTRACE_INL_HEADER)
#include ABSL_STACKTRACE_INL_HEADER
#else
# error Cannot calculate stack trace: will need to write for your environment
# include "absl/debugging/internal/stacktrace_aarch64-inl.inc"
# include "absl/debugging/internal/stacktrace_arm-inl.inc"
# include "absl/debugging/internal/stacktrace_emscripten-inl.inc"
# include "absl/debugging/internal/stacktrace_generic-inl.inc"
# include "absl/debugging/internal/stacktrace_powerpc-inl.inc"
# include "absl/debugging/internal/stacktrace_riscv-inl.inc"
# include "absl/debugging/internal/stacktrace_unimplemented-inl.inc"
# include "absl/debugging/internal/stacktrace_win32-inl.inc"
# include "absl/debugging/internal/stacktrace_x86-inl.inc"
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace {
typedef int (*Unwinder)(void**, int*, int, int, const void*, int*);
std::atomic<Unwinder> custom;
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
ABSL_ATTRIBUTE_ALWAYS_INLINE inline int Unwind(void** result, int* sizes,
int max_depth, int skip_count,
const void* uc,
int* min_dropped_frames) {
Unwinder f = &UnwindImpl<IS_STACK_FRAMES, IS_WITH_CONTEXT>;
Unwinder g = custom.load(std::memory_order_acquire);
if (g != nullptr) f = g;
// Add 1 to skip count for the unwinder function itself
int size = (*f)(result, sizes, max_depth, skip_count + 1, uc,
min_dropped_frames);
// To disable tail call to (*f)(...)
ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
return size;
}
} // anonymous namespace
ABSL_ATTRIBUTE_NOINLINE ABSL_ATTRIBUTE_NO_TAIL_CALL int GetStackFrames(
void** result, int* sizes, int max_depth, int skip_count) {
return Unwind<true, false>(result, sizes, max_depth, skip_count, nullptr,
nullptr);
}
ABSL_ATTRIBUTE_NOINLINE ABSL_ATTRIBUTE_NO_TAIL_CALL int
GetStackFramesWithContext(void** result, int* sizes, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames) {
return Unwind<true, true>(result, sizes, max_depth, skip_count, uc,
min_dropped_frames);
}
ABSL_ATTRIBUTE_NOINLINE ABSL_ATTRIBUTE_NO_TAIL_CALL int GetStackTrace(
void** result, int max_depth, int skip_count) {
return Unwind<false, false>(result, nullptr, max_depth, skip_count, nullptr,
nullptr);
}
ABSL_ATTRIBUTE_NOINLINE ABSL_ATTRIBUTE_NO_TAIL_CALL int
GetStackTraceWithContext(void** result, int max_depth, int skip_count,
const void* uc, int* min_dropped_frames) {
return Unwind<false, true>(result, nullptr, max_depth, skip_count, uc,
min_dropped_frames);
}
void SetStackUnwinder(Unwinder w) {
custom.store(w, std::memory_order_release);
}
int DefaultStackUnwinder(void** pcs, int* sizes, int depth, int skip,
const void* uc, int* min_dropped_frames) {
skip++; // For this function
Unwinder f = nullptr;
if (sizes == nullptr) {
if (uc == nullptr) {
f = &UnwindImpl<false, false>;
} else {
f = &UnwindImpl<false, true>;
}
} else {
if (uc == nullptr) {
f = &UnwindImpl<true, false>;
} else {
f = &UnwindImpl<true, true>;
}
}
volatile int x = 0;
int n = (*f)(pcs, sizes, depth, skip, uc, min_dropped_frames);
x = 1; (void) x; // To disable tail call to (*f)(...)
return n;
}
ABSL_NAMESPACE_END
} // namespace absl

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: stacktrace.h
// -----------------------------------------------------------------------------
//
// This file contains routines to extract the current stack trace and associated
// stack frames. These functions are thread-safe and async-signal-safe.
//
// Note that stack trace functionality is platform dependent and requires
// additional support from the compiler/build system in most cases. (That is,
// this functionality generally only works on platforms/builds that have been
// specifically configured to support it.)
//
// Note: stack traces in Abseil that do not utilize a symbolizer will result in
// frames consisting of function addresses rather than human-readable function
// names. (See symbolize.h for information on symbolizing these values.)
#ifndef ABSL_DEBUGGING_STACKTRACE_H_
#define ABSL_DEBUGGING_STACKTRACE_H_
#include "absl/base/config.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
// GetStackFrames()
//
// Records program counter values for up to `max_depth` frames, skipping the
// most recent `skip_count` stack frames, stores their corresponding values
// and sizes in `results` and `sizes` buffers, and returns the number of frames
// stored. (Note that the frame generated for the `absl::GetStackFrames()`
// routine itself is also skipped.)
//
// Example:
//
// main() { foo(); }
// foo() { bar(); }
// bar() {
// void* result[10];
// int sizes[10];
// int depth = absl::GetStackFrames(result, sizes, 10, 1);
// }
//
// The current stack frame would consist of three function calls: `bar()`,
// `foo()`, and then `main()`; however, since the `GetStackFrames()` call sets
// `skip_count` to `1`, it will skip the frame for `bar()`, the most recently
// invoked function call. It will therefore return 2 and fill `result` with
// program counters within the following functions:
//
// result[0] foo()
// result[1] main()
//
// (Note: in practice, a few more entries after `main()` may be added to account
// for startup processes.)
//
// Corresponding stack frame sizes will also be recorded:
//
// sizes[0] 16
// sizes[1] 16
//
// (Stack frame sizes of `16` above are just for illustration purposes.)
//
// Stack frame sizes of 0 or less indicate that those frame sizes couldn't
// be identified.
//
// This routine may return fewer stack frame entries than are
// available. Also note that `result` and `sizes` must both be non-null.
extern int GetStackFrames(void** result, int* sizes, int max_depth,
int skip_count);
// GetStackFramesWithContext()
//
// Records program counter values obtained from a signal handler. Records
// program counter values for up to `max_depth` frames, skipping the most recent
// `skip_count` stack frames, stores their corresponding values and sizes in
// `results` and `sizes` buffers, and returns the number of frames stored. (Note
// that the frame generated for the `absl::GetStackFramesWithContext()` routine
// itself is also skipped.)
//
// The `uc` parameter, if non-null, should be a pointer to a `ucontext_t` value
// passed to a signal handler registered via the `sa_sigaction` field of a
// `sigaction` struct. (See
// http://man7.org/linux/man-pages/man2/sigaction.2.html.) The `uc` value may
// help a stack unwinder to provide a better stack trace under certain
// conditions. `uc` may safely be null.
//
// The `min_dropped_frames` output parameter, if non-null, points to the
// location to note any dropped stack frames, if any, due to buffer limitations
// or other reasons. (This value will be set to `0` if no frames were dropped.)
// The number of total stack frames is guaranteed to be >= skip_count +
// max_depth + *min_dropped_frames.
extern int GetStackFramesWithContext(void** result, int* sizes, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames);
// GetStackTrace()
//
// Records program counter values for up to `max_depth` frames, skipping the
// most recent `skip_count` stack frames, stores their corresponding values
// in `results`, and returns the number of frames
// stored. Note that this function is similar to `absl::GetStackFrames()`
// except that it returns the stack trace only, and not stack frame sizes.
//
// Example:
//
// main() { foo(); }
// foo() { bar(); }
// bar() {
// void* result[10];
// int depth = absl::GetStackTrace(result, 10, 1);
// }
//
// This produces:
//
// result[0] foo
// result[1] main
// .... ...
//
// `result` must not be null.
extern int GetStackTrace(void** result, int max_depth, int skip_count);
// GetStackTraceWithContext()
//
// Records program counter values obtained from a signal handler. Records
// program counter values for up to `max_depth` frames, skipping the most recent
// `skip_count` stack frames, stores their corresponding values in `results`,
// and returns the number of frames stored. (Note that the frame generated for
// the `absl::GetStackFramesWithContext()` routine itself is also skipped.)
//
// The `uc` parameter, if non-null, should be a pointer to a `ucontext_t` value
// passed to a signal handler registered via the `sa_sigaction` field of a
// `sigaction` struct. (See
// http://man7.org/linux/man-pages/man2/sigaction.2.html.) The `uc` value may
// help a stack unwinder to provide a better stack trace under certain
// conditions. `uc` may safely be null.
//
// The `min_dropped_frames` output parameter, if non-null, points to the
// location to note any dropped stack frames, if any, due to buffer limitations
// or other reasons. (This value will be set to `0` if no frames were dropped.)
// The number of total stack frames is guaranteed to be >= skip_count +
// max_depth + *min_dropped_frames.
extern int GetStackTraceWithContext(void** result, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames);
// SetStackUnwinder()
//
// Provides a custom function for unwinding stack frames that will be used in
// place of the default stack unwinder when invoking the static
// GetStack{Frames,Trace}{,WithContext}() functions above.
//
// The arguments passed to the unwinder function will match the
// arguments passed to `absl::GetStackFramesWithContext()` except that sizes
// will be non-null iff the caller is interested in frame sizes.
//
// If unwinder is set to null, we revert to the default stack-tracing behavior.
//
// *****************************************************************************
// WARNING
// *****************************************************************************
//
// absl::SetStackUnwinder is not suitable for general purpose use. It is
// provided for custom runtimes.
// Some things to watch out for when calling `absl::SetStackUnwinder()`:
//
// (a) The unwinder may be called from within signal handlers and
// therefore must be async-signal-safe.
//
// (b) Even after a custom stack unwinder has been unregistered, other
// threads may still be in the process of using that unwinder.
// Therefore do not clean up any state that may be needed by an old
// unwinder.
// *****************************************************************************
extern void SetStackUnwinder(int (*unwinder)(void** pcs, int* sizes,
int max_depth, int skip_count,
const void* uc,
int* min_dropped_frames));
// DefaultStackUnwinder()
//
// Records program counter values of up to `max_depth` frames, skipping the most
// recent `skip_count` stack frames, and stores their corresponding values in
// `pcs`. (Note that the frame generated for this call itself is also skipped.)
// This function acts as a generic stack-unwinder; prefer usage of the more
// specific `GetStack{Trace,Frames}{,WithContext}()` functions above.
//
// If you have set your own stack unwinder (with the `SetStackUnwinder()`
// function above, you can still get the default stack unwinder by calling
// `DefaultStackUnwinder()`, which will ignore any previously set stack unwinder
// and use the default one instead.
//
// Because this function is generic, only `pcs` is guaranteed to be non-null
// upon return. It is legal for `sizes`, `uc`, and `min_dropped_frames` to all
// be null when called.
//
// The semantics are the same as the corresponding `GetStack*()` function in the
// case where `absl::SetStackUnwinder()` was never called. Equivalents are:
//
// null sizes | non-nullptr sizes
// |==========================================================|
// null uc | GetStackTrace() | GetStackFrames() |
// non-null uc | GetStackTraceWithContext() | GetStackFramesWithContext() |
// |==========================================================|
extern int DefaultStackUnwinder(void** pcs, int* sizes, int max_depth,
int skip_count, const void* uc,
int* min_dropped_frames);
namespace debugging_internal {
// Returns true for platforms which are expected to have functioning stack trace
// implementations. Intended to be used for tests which want to exclude
// verification of logic known to be broken because stack traces are not
// working.
extern bool StackTraceWorksForTest();
} // namespace debugging_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_STACKTRACE_H_

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/debugging/symbolize.h"
#ifdef _WIN32
#include <winapifamily.h>
#if !(WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP)) || \
WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
// UWP doesn't have access to win32 APIs.
#define ABSL_INTERNAL_HAVE_SYMBOLIZE_WIN32
#endif
#endif
// Emscripten symbolization relies on JS. Do not use them in standalone mode.
#if defined(__EMSCRIPTEN__) && !defined(STANDALONE_WASM)
#define ABSL_INTERNAL_HAVE_SYMBOLIZE_WASM
#endif
#if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE)
#include "absl/debugging/symbolize_elf.inc"
#elif defined(ABSL_INTERNAL_HAVE_SYMBOLIZE_WIN32)
// The Windows Symbolizer only works if PDB files containing the debug info
// are available to the program at runtime.
#include "absl/debugging/symbolize_win32.inc"
#elif defined(__APPLE__)
#include "absl/debugging/symbolize_darwin.inc"
#elif defined(ABSL_INTERNAL_HAVE_SYMBOLIZE_WASM)
#include "absl/debugging/symbolize_emscripten.inc"
#else
#include "absl/debugging/symbolize_unimplemented.inc"
#endif

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: symbolize.h
// -----------------------------------------------------------------------------
//
// This file configures the Abseil symbolizer for use in converting instruction
// pointer addresses (program counters) into human-readable names (function
// calls, etc.) within Abseil code.
//
// The symbolizer may be invoked from several sources:
//
// * Implicitly, through the installation of an Abseil failure signal handler.
// (See failure_signal_handler.h for more information.)
// * By calling `Symbolize()` directly on a program counter you obtain through
// `absl::GetStackTrace()` or `absl::GetStackFrames()`. (See stacktrace.h
// for more information.
// * By calling `Symbolize()` directly on a program counter you obtain through
// other means (which would be platform-dependent).
//
// In all of the above cases, the symbolizer must first be initialized before
// any program counter values can be symbolized. If you are installing a failure
// signal handler, initialize the symbolizer before you do so.
//
// Example:
//
// int main(int argc, char** argv) {
// // Initialize the Symbolizer before installing the failure signal handler
// absl::InitializeSymbolizer(argv[0]);
//
// // Now you may install the failure signal handler
// absl::FailureSignalHandlerOptions options;
// absl::InstallFailureSignalHandler(options);
//
// // Start running your main program
// ...
// return 0;
// }
//
#ifndef ABSL_DEBUGGING_SYMBOLIZE_H_
#define ABSL_DEBUGGING_SYMBOLIZE_H_
#include "absl/debugging/internal/symbolize.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
// InitializeSymbolizer()
//
// Initializes the program counter symbolizer, given the path of the program
// (typically obtained through `main()`s `argv[0]`). The Abseil symbolizer
// allows you to read program counters (instruction pointer values) using their
// human-readable names within output such as stack traces.
//
// Example:
//
// int main(int argc, char *argv[]) {
// absl::InitializeSymbolizer(argv[0]);
// // Now you can use the symbolizer
// }
void InitializeSymbolizer(const char* argv0);
//
// Symbolize()
//
// Symbolizes a program counter (instruction pointer value) `pc` and, on
// success, writes the name to `out`. The symbol name is demangled, if possible.
// Note that the symbolized name may be truncated and will be NUL-terminated.
// Demangling is supported for symbols generated by GCC 3.x or newer). Returns
// `false` on failure.
//
// Example:
//
// // Print a program counter and its symbol name.
// static void DumpPCAndSymbol(void *pc) {
// char tmp[1024];
// const char *symbol = "(unknown)";
// if (absl::Symbolize(pc, tmp, sizeof(tmp))) {
// symbol = tmp;
// }
// absl::PrintF("%p %s\n", pc, symbol);
// }
bool Symbolize(const void *pc, char *out, int out_size);
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_DEBUGGING_SYMBOLIZE_H_

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// Copyright 2020 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <cxxabi.h>
#include <execinfo.h>
#include <algorithm>
#include <cstring>
#include "absl/base/internal/raw_logging.h"
#include "absl/debugging/internal/demangle.h"
#include "absl/strings/numbers.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
void InitializeSymbolizer(const char*) {}
namespace debugging_internal {
namespace {
static std::string GetSymbolString(absl::string_view backtrace_line) {
// Example Backtrace lines:
// 0 libimaging_shared.dylib 0x018c152a
// _ZNSt11_Deque_baseIN3nik7mediadb4PageESaIS2_EE17_M_initialize_mapEm + 3478
//
// or
// 0 libimaging_shared.dylib 0x0000000001895c39
// _ZN3nik4util19register_shared_ptrINS_3gpu7TextureEEEvPKvS5_ + 39
//
// or
// 0 mysterious_app 0x0124000120120009 main + 17
auto address_pos = backtrace_line.find(" 0x");
if (address_pos == absl::string_view::npos) return std::string();
absl::string_view symbol_view = backtrace_line.substr(address_pos + 1);
auto space_pos = symbol_view.find(" ");
if (space_pos == absl::string_view::npos) return std::string();
symbol_view = symbol_view.substr(space_pos + 1); // to mangled symbol
auto plus_pos = symbol_view.find(" + ");
if (plus_pos == absl::string_view::npos) return std::string();
symbol_view = symbol_view.substr(0, plus_pos); // strip remainng
return std::string(symbol_view);
}
} // namespace
} // namespace debugging_internal
bool Symbolize(const void* pc, char* out, int out_size) {
if (out_size <= 0 || pc == nullptr) {
out = nullptr;
return false;
}
// This allocates a char* array.
char** frame_strings = backtrace_symbols(const_cast<void**>(&pc), 1);
if (frame_strings == nullptr) return false;
std::string symbol = debugging_internal::GetSymbolString(frame_strings[0]);
free(frame_strings);
char tmp_buf[1024];
if (debugging_internal::Demangle(symbol.c_str(), tmp_buf, sizeof(tmp_buf))) {
size_t len = strlen(tmp_buf);
if (len + 1 <= static_cast<size_t>(out_size)) { // +1 for '\0'
assert(len < sizeof(tmp_buf));
memmove(out, tmp_buf, len + 1);
}
} else {
strncpy(out, symbol.c_str(), static_cast<size_t>(out_size));
}
if (out[out_size - 1] != '\0') {
// strncpy() does not '\0' terminate when it truncates.
static constexpr char kEllipsis[] = "...";
size_t ellipsis_size =
std::min(sizeof(kEllipsis) - 1, static_cast<size_t>(out_size) - 1);
memcpy(out + out_size - ellipsis_size - 1, kEllipsis, ellipsis_size);
out[out_size - 1] = '\0';
}
return true;
}
ABSL_NAMESPACE_END
} // namespace absl

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// This library provides Symbolize() function that symbolizes program
// counters to their corresponding symbol names on linux platforms.
// This library has a minimal implementation of an ELF symbol table
// reader (i.e. it doesn't depend on libelf, etc.).
//
// The algorithm used in Symbolize() is as follows.
//
// 1. Go through a list of maps in /proc/self/maps and find the map
// containing the program counter.
//
// 2. Open the mapped file and find a regular symbol table inside.
// Iterate over symbols in the symbol table and look for the symbol
// containing the program counter. If such a symbol is found,
// obtain the symbol name, and demangle the symbol if possible.
// If the symbol isn't found in the regular symbol table (binary is
// stripped), try the same thing with a dynamic symbol table.
//
// Note that Symbolize() is originally implemented to be used in
// signal handlers, hence it doesn't use malloc() and other unsafe
// operations. It should be both thread-safe and async-signal-safe.
//
// Implementation note:
//
// We don't use heaps but only use stacks. We want to reduce the
// stack consumption so that the symbolizer can run on small stacks.
//
// Here are some numbers collected with GCC 4.1.0 on x86:
// - sizeof(Elf32_Sym) = 16
// - sizeof(Elf32_Shdr) = 40
// - sizeof(Elf64_Sym) = 24
// - sizeof(Elf64_Shdr) = 64
//
// This implementation is intended to be async-signal-safe but uses some
// functions which are not guaranteed to be so, such as memchr() and
// memmove(). We assume they are async-signal-safe.
#include <dlfcn.h>
#include <elf.h>
#include <fcntl.h>
#include <link.h> // For ElfW() macro.
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <algorithm>
#include <array>
#include <atomic>
#include <cerrno>
#include <cinttypes>
#include <climits>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include "absl/base/casts.h"
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/low_level_alloc.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/internal/spinlock.h"
#include "absl/base/port.h"
#include "absl/debugging/internal/demangle.h"
#include "absl/debugging/internal/vdso_support.h"
#include "absl/strings/string_view.h"
#if defined(__FreeBSD__) && !defined(ElfW)
#define ElfW(x) __ElfN(x)
#endif
namespace absl {
ABSL_NAMESPACE_BEGIN
// Value of argv[0]. Used by MaybeInitializeObjFile().
static char *argv0_value = nullptr;
void InitializeSymbolizer(const char *argv0) {
#ifdef ABSL_HAVE_VDSO_SUPPORT
// We need to make sure VDSOSupport::Init() is called before any setuid or
// chroot calls, so InitializeSymbolizer() should be called very early in the
// life of a program.
absl::debugging_internal::VDSOSupport::Init();
#endif
if (argv0_value != nullptr) {
free(argv0_value);
argv0_value = nullptr;
}
if (argv0 != nullptr && argv0[0] != '\0') {
argv0_value = strdup(argv0);
}
}
namespace debugging_internal {
namespace {
// Re-runs fn until it doesn't cause EINTR.
#define NO_INTR(fn) \
do { \
} while ((fn) < 0 && errno == EINTR)
// On Linux, ELF_ST_* are defined in <linux/elf.h>. To make this portable
// we define our own ELF_ST_BIND and ELF_ST_TYPE if not available.
#ifndef ELF_ST_BIND
#define ELF_ST_BIND(info) (((unsigned char)(info)) >> 4)
#endif
#ifndef ELF_ST_TYPE
#define ELF_ST_TYPE(info) (((unsigned char)(info)) & 0xF)
#endif
// Some platforms use a special .opd section to store function pointers.
const char kOpdSectionName[] = ".opd";
#if (defined(__powerpc__) && !(_CALL_ELF > 1)) || defined(__ia64)
// Use opd section for function descriptors on these platforms, the function
// address is the first word of the descriptor.
enum { kPlatformUsesOPDSections = 1 };
#else // not PPC or IA64
enum { kPlatformUsesOPDSections = 0 };
#endif
// This works for PowerPC & IA64 only. A function descriptor consist of two
// pointers and the first one is the function's entry.
const size_t kFunctionDescriptorSize = sizeof(void *) * 2;
const int kMaxDecorators = 10; // Seems like a reasonable upper limit.
struct InstalledSymbolDecorator {
SymbolDecorator fn;
void *arg;
int ticket;
};
int g_num_decorators;
InstalledSymbolDecorator g_decorators[kMaxDecorators];
struct FileMappingHint {
const void *start;
const void *end;
uint64_t offset;
const char *filename;
};
// Protects g_decorators.
// We are using SpinLock and not a Mutex here, because we may be called
// from inside Mutex::Lock itself, and it prohibits recursive calls.
// This happens in e.g. base/stacktrace_syscall_unittest.
// Moreover, we are using only TryLock(), if the decorator list
// is being modified (is busy), we skip all decorators, and possibly
// loose some info. Sorry, that's the best we could do.
ABSL_CONST_INIT absl::base_internal::SpinLock g_decorators_mu(
absl::kConstInit, absl::base_internal::SCHEDULE_KERNEL_ONLY);
const int kMaxFileMappingHints = 8;
int g_num_file_mapping_hints;
FileMappingHint g_file_mapping_hints[kMaxFileMappingHints];
// Protects g_file_mapping_hints.
ABSL_CONST_INIT absl::base_internal::SpinLock g_file_mapping_mu(
absl::kConstInit, absl::base_internal::SCHEDULE_KERNEL_ONLY);
// Async-signal-safe function to zero a buffer.
// memset() is not guaranteed to be async-signal-safe.
static void SafeMemZero(void* p, size_t size) {
unsigned char *c = static_cast<unsigned char *>(p);
while (size--) {
*c++ = 0;
}
}
struct ObjFile {
ObjFile()
: filename(nullptr),
start_addr(nullptr),
end_addr(nullptr),
offset(0),
fd(-1),
elf_type(-1) {
SafeMemZero(&elf_header, sizeof(elf_header));
SafeMemZero(&phdr[0], sizeof(phdr));
}
char *filename;
const void *start_addr;
const void *end_addr;
uint64_t offset;
// The following fields are initialized on the first access to the
// object file.
int fd;
int elf_type;
ElfW(Ehdr) elf_header;
// PT_LOAD program header describing executable code.
// Normally we expect just one, but SWIFT binaries have two.
// CUDA binaries have 3 (see cr/473913254 description).
std::array<ElfW(Phdr), 4> phdr;
};
// Build 4-way associative cache for symbols. Within each cache line, symbols
// are replaced in LRU order.
enum {
ASSOCIATIVITY = 4,
};
struct SymbolCacheLine {
const void *pc[ASSOCIATIVITY];
char *name[ASSOCIATIVITY];
// age[i] is incremented when a line is accessed. it's reset to zero if the
// i'th entry is read.
uint32_t age[ASSOCIATIVITY];
};
// ---------------------------------------------------------------
// An async-signal-safe arena for LowLevelAlloc
static std::atomic<base_internal::LowLevelAlloc::Arena *> g_sig_safe_arena;
static base_internal::LowLevelAlloc::Arena *SigSafeArena() {
return g_sig_safe_arena.load(std::memory_order_acquire);
}
static void InitSigSafeArena() {
if (SigSafeArena() == nullptr) {
base_internal::LowLevelAlloc::Arena *new_arena =
base_internal::LowLevelAlloc::NewArena(
base_internal::LowLevelAlloc::kAsyncSignalSafe);
base_internal::LowLevelAlloc::Arena *old_value = nullptr;
if (!g_sig_safe_arena.compare_exchange_strong(old_value, new_arena,
std::memory_order_release,
std::memory_order_relaxed)) {
// We lost a race to allocate an arena; deallocate.
base_internal::LowLevelAlloc::DeleteArena(new_arena);
}
}
}
// ---------------------------------------------------------------
// An AddrMap is a vector of ObjFile, using SigSafeArena() for allocation.
class AddrMap {
public:
AddrMap() : size_(0), allocated_(0), obj_(nullptr) {}
~AddrMap() { base_internal::LowLevelAlloc::Free(obj_); }
size_t Size() const { return size_; }
ObjFile *At(size_t i) { return &obj_[i]; }
ObjFile *Add();
void Clear();
private:
size_t size_; // count of valid elements (<= allocated_)
size_t allocated_; // count of allocated elements
ObjFile *obj_; // array of allocated_ elements
AddrMap(const AddrMap &) = delete;
AddrMap &operator=(const AddrMap &) = delete;
};
void AddrMap::Clear() {
for (size_t i = 0; i != size_; i++) {
At(i)->~ObjFile();
}
size_ = 0;
}
ObjFile *AddrMap::Add() {
if (size_ == allocated_) {
size_t new_allocated = allocated_ * 2 + 50;
ObjFile *new_obj_ =
static_cast<ObjFile *>(base_internal::LowLevelAlloc::AllocWithArena(
new_allocated * sizeof(*new_obj_), SigSafeArena()));
if (obj_) {
memcpy(new_obj_, obj_, allocated_ * sizeof(*new_obj_));
base_internal::LowLevelAlloc::Free(obj_);
}
obj_ = new_obj_;
allocated_ = new_allocated;
}
return new (&obj_[size_++]) ObjFile;
}
class CachingFile {
public:
// Setup reader for fd that uses buf[0, buf_size-1] as a cache.
CachingFile(int fd, char *buf, size_t buf_size)
: fd_(fd),
cache_(buf),
cache_size_(buf_size),
cache_start_(0),
cache_limit_(0) {}
int fd() const { return fd_; }
ssize_t ReadFromOffset(void *buf, size_t count, off_t offset);
bool ReadFromOffsetExact(void *buf, size_t count, off_t offset);
private:
// Bytes [cache_start_, cache_limit_-1] from fd_ are stored in
// a prefix of cache_[0, cache_size_-1].
int fd_;
char *cache_;
size_t cache_size_;
off_t cache_start_;
off_t cache_limit_;
};
// ---------------------------------------------------------------
enum FindSymbolResult { SYMBOL_NOT_FOUND = 1, SYMBOL_TRUNCATED, SYMBOL_FOUND };
class Symbolizer {
public:
Symbolizer();
~Symbolizer();
const char *GetSymbol(const void *const pc);
private:
char *CopyString(const char *s) {
size_t len = strlen(s);
char *dst = static_cast<char *>(
base_internal::LowLevelAlloc::AllocWithArena(len + 1, SigSafeArena()));
ABSL_RAW_CHECK(dst != nullptr, "out of memory");
memcpy(dst, s, len + 1);
return dst;
}
ObjFile *FindObjFile(const void *const start,
size_t size) ABSL_ATTRIBUTE_NOINLINE;
static bool RegisterObjFile(const char *filename,
const void *const start_addr,
const void *const end_addr, uint64_t offset,
void *arg);
SymbolCacheLine *GetCacheLine(const void *const pc);
const char *FindSymbolInCache(const void *const pc);
const char *InsertSymbolInCache(const void *const pc, const char *name);
void AgeSymbols(SymbolCacheLine *line);
void ClearAddrMap();
FindSymbolResult GetSymbolFromObjectFile(const ObjFile &obj,
const void *const pc,
const ptrdiff_t relocation,
char *out, size_t out_size,
char *tmp_buf, size_t tmp_buf_size);
const char *GetUncachedSymbol(const void *pc);
enum {
SYMBOL_BUF_SIZE = 3072,
TMP_BUF_SIZE = 1024,
SYMBOL_CACHE_LINES = 128,
FILE_CACHE_SIZE = 8192,
};
AddrMap addr_map_;
bool ok_;
bool addr_map_read_;
char symbol_buf_[SYMBOL_BUF_SIZE];
char file_cache_[FILE_CACHE_SIZE];
// tmp_buf_ will be used to store arrays of ElfW(Shdr) and ElfW(Sym)
// so we ensure that tmp_buf_ is properly aligned to store either.
alignas(16) char tmp_buf_[TMP_BUF_SIZE];
static_assert(alignof(ElfW(Shdr)) <= 16,
"alignment of tmp buf too small for Shdr");
static_assert(alignof(ElfW(Sym)) <= 16,
"alignment of tmp buf too small for Sym");
SymbolCacheLine symbol_cache_[SYMBOL_CACHE_LINES];
};
static std::atomic<Symbolizer *> g_cached_symbolizer;
} // namespace
static size_t SymbolizerSize() {
#if defined(__wasm__) || defined(__asmjs__)
auto pagesize = static_cast<size_t>(getpagesize());
#else
auto pagesize = static_cast<size_t>(sysconf(_SC_PAGESIZE));
#endif
return ((sizeof(Symbolizer) - 1) / pagesize + 1) * pagesize;
}
// Return (and set null) g_cached_symbolized_state if it is not null.
// Otherwise return a new symbolizer.
static Symbolizer *AllocateSymbolizer() {
InitSigSafeArena();
Symbolizer *symbolizer =
g_cached_symbolizer.exchange(nullptr, std::memory_order_acquire);
if (symbolizer != nullptr) {
return symbolizer;
}
return new (base_internal::LowLevelAlloc::AllocWithArena(
SymbolizerSize(), SigSafeArena())) Symbolizer();
}
// Set g_cached_symbolize_state to s if it is null, otherwise
// delete s.
static void FreeSymbolizer(Symbolizer *s) {
Symbolizer *old_cached_symbolizer = nullptr;
if (!g_cached_symbolizer.compare_exchange_strong(old_cached_symbolizer, s,
std::memory_order_release,
std::memory_order_relaxed)) {
s->~Symbolizer();
base_internal::LowLevelAlloc::Free(s);
}
}
Symbolizer::Symbolizer() : ok_(true), addr_map_read_(false) {
for (SymbolCacheLine &symbol_cache_line : symbol_cache_) {
for (size_t j = 0; j < ABSL_ARRAYSIZE(symbol_cache_line.name); ++j) {
symbol_cache_line.pc[j] = nullptr;
symbol_cache_line.name[j] = nullptr;
symbol_cache_line.age[j] = 0;
}
}
}
Symbolizer::~Symbolizer() {
for (SymbolCacheLine &symbol_cache_line : symbol_cache_) {
for (char *s : symbol_cache_line.name) {
base_internal::LowLevelAlloc::Free(s);
}
}
ClearAddrMap();
}
// We don't use assert() since it's not guaranteed to be
// async-signal-safe. Instead we define a minimal assertion
// macro. So far, we don't need pretty printing for __FILE__, etc.
#define SAFE_ASSERT(expr) ((expr) ? static_cast<void>(0) : abort())
// Read up to "count" bytes from file descriptor "fd" into the buffer
// starting at "buf" while handling short reads and EINTR. On
// success, return the number of bytes read. Otherwise, return -1.
static ssize_t ReadPersistent(int fd, void *buf, size_t count) {
SAFE_ASSERT(fd >= 0);
SAFE_ASSERT(count <= SSIZE_MAX);
char *buf0 = reinterpret_cast<char *>(buf);
size_t num_bytes = 0;
while (num_bytes < count) {
ssize_t len;
NO_INTR(len = read(fd, buf0 + num_bytes, count - num_bytes));
if (len < 0) { // There was an error other than EINTR.
ABSL_RAW_LOG(WARNING, "read failed: errno=%d", errno);
return -1;
}
if (len == 0) { // Reached EOF.
break;
}
num_bytes += static_cast<size_t>(len);
}
SAFE_ASSERT(num_bytes <= count);
return static_cast<ssize_t>(num_bytes);
}
// Read up to "count" bytes from "offset" into the buffer starting at "buf",
// while handling short reads and EINTR. On success, return the number of bytes
// read. Otherwise, return -1.
ssize_t CachingFile::ReadFromOffset(void *buf, size_t count, off_t offset) {
char *dst = static_cast<char *>(buf);
size_t read = 0;
while (read < count) {
// Look in cache first.
if (offset >= cache_start_ && offset < cache_limit_) {
const char *hit_start = &cache_[offset - cache_start_];
const size_t n =
std::min(count - read, static_cast<size_t>(cache_limit_ - offset));
memcpy(dst, hit_start, n);
dst += n;
read += static_cast<size_t>(n);
offset += static_cast<off_t>(n);
continue;
}
cache_start_ = 0;
cache_limit_ = 0;
ssize_t n = pread(fd_, cache_, cache_size_, offset);
if (n < 0) {
if (errno == EINTR) {
continue;
}
ABSL_RAW_LOG(WARNING, "read failed: errno=%d", errno);
return -1;
}
if (n == 0) { // Reached EOF.
break;
}
cache_start_ = offset;
cache_limit_ = offset + static_cast<off_t>(n);
// Next iteration will copy from cache into dst.
}
return static_cast<ssize_t>(read);
}
// Try reading exactly "count" bytes from "offset" bytes into the buffer
// starting at "buf" while handling short reads and EINTR. On success, return
// true. Otherwise, return false.
bool CachingFile::ReadFromOffsetExact(void *buf, size_t count, off_t offset) {
ssize_t len = ReadFromOffset(buf, count, offset);
return len >= 0 && static_cast<size_t>(len) == count;
}
// Returns elf_header.e_type if the file pointed by fd is an ELF binary.
static int FileGetElfType(CachingFile *file) {
ElfW(Ehdr) elf_header;
if (!file->ReadFromOffsetExact(&elf_header, sizeof(elf_header), 0)) {
return -1;
}
if (memcmp(elf_header.e_ident, ELFMAG, SELFMAG) != 0) {
return -1;
}
return elf_header.e_type;
}
// Read the section headers in the given ELF binary, and if a section
// of the specified type is found, set the output to this section header
// and return true. Otherwise, return false.
// To keep stack consumption low, we would like this function to not get
// inlined.
static ABSL_ATTRIBUTE_NOINLINE bool GetSectionHeaderByType(
CachingFile *file, ElfW(Half) sh_num, const off_t sh_offset,
ElfW(Word) type, ElfW(Shdr) * out, char *tmp_buf, size_t tmp_buf_size) {
ElfW(Shdr) *buf = reinterpret_cast<ElfW(Shdr) *>(tmp_buf);
const size_t buf_entries = tmp_buf_size / sizeof(buf[0]);
const size_t buf_bytes = buf_entries * sizeof(buf[0]);
for (size_t i = 0; static_cast<int>(i) < sh_num;) {
const size_t num_bytes_left =
(static_cast<size_t>(sh_num) - i) * sizeof(buf[0]);
const size_t num_bytes_to_read =
(buf_bytes > num_bytes_left) ? num_bytes_left : buf_bytes;
const off_t offset = sh_offset + static_cast<off_t>(i * sizeof(buf[0]));
const ssize_t len = file->ReadFromOffset(buf, num_bytes_to_read, offset);
if (len < 0) {
ABSL_RAW_LOG(
WARNING,
"Reading %zu bytes from offset %ju returned %zd which is negative.",
num_bytes_to_read, static_cast<intmax_t>(offset), len);
return false;
}
if (static_cast<size_t>(len) % sizeof(buf[0]) != 0) {
ABSL_RAW_LOG(
WARNING,
"Reading %zu bytes from offset %jd returned %zd which is not a "
"multiple of %zu.",
num_bytes_to_read, static_cast<intmax_t>(offset), len,
sizeof(buf[0]));
return false;
}
const size_t num_headers_in_buf = static_cast<size_t>(len) / sizeof(buf[0]);
SAFE_ASSERT(num_headers_in_buf <= buf_entries);
for (size_t j = 0; j < num_headers_in_buf; ++j) {
if (buf[j].sh_type == type) {
*out = buf[j];
return true;
}
}
i += num_headers_in_buf;
}
return false;
}
// There is no particular reason to limit section name to 63 characters,
// but there has (as yet) been no need for anything longer either.
const int kMaxSectionNameLen = 64;
// Small cache to use for miscellaneous file reads.
const int kSmallFileCacheSize = 100;
bool ForEachSection(int fd,
const std::function<bool(absl::string_view name,
const ElfW(Shdr) &)> &callback) {
char buf[kSmallFileCacheSize];
CachingFile file(fd, buf, sizeof(buf));
ElfW(Ehdr) elf_header;
if (!file.ReadFromOffsetExact(&elf_header, sizeof(elf_header), 0)) {
return false;
}
// Technically it can be larger, but in practice this never happens.
if (elf_header.e_shentsize != sizeof(ElfW(Shdr))) {
return false;
}
ElfW(Shdr) shstrtab;
off_t shstrtab_offset = static_cast<off_t>(elf_header.e_shoff) +
elf_header.e_shentsize * elf_header.e_shstrndx;
if (!file.ReadFromOffsetExact(&shstrtab, sizeof(shstrtab), shstrtab_offset)) {
return false;
}
for (int i = 0; i < elf_header.e_shnum; ++i) {
ElfW(Shdr) out;
off_t section_header_offset =
static_cast<off_t>(elf_header.e_shoff) + elf_header.e_shentsize * i;
if (!file.ReadFromOffsetExact(&out, sizeof(out), section_header_offset)) {
return false;
}
off_t name_offset = static_cast<off_t>(shstrtab.sh_offset) + out.sh_name;
char header_name[kMaxSectionNameLen];
ssize_t n_read =
file.ReadFromOffset(&header_name, kMaxSectionNameLen, name_offset);
if (n_read < 0) {
return false;
} else if (n_read > kMaxSectionNameLen) {
// Long read?
return false;
}
absl::string_view name(header_name,
strnlen(header_name, static_cast<size_t>(n_read)));
if (!callback(name, out)) {
break;
}
}
return true;
}
// name_len should include terminating '\0'.
bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
ElfW(Shdr) * out) {
char header_name[kMaxSectionNameLen];
if (sizeof(header_name) < name_len) {
ABSL_RAW_LOG(WARNING,
"Section name '%s' is too long (%zu); "
"section will not be found (even if present).",
name, name_len);
// No point in even trying.
return false;
}
char buf[kSmallFileCacheSize];
CachingFile file(fd, buf, sizeof(buf));
ElfW(Ehdr) elf_header;
if (!file.ReadFromOffsetExact(&elf_header, sizeof(elf_header), 0)) {
return false;
}
// Technically it can be larger, but in practice this never happens.
if (elf_header.e_shentsize != sizeof(ElfW(Shdr))) {
return false;
}
ElfW(Shdr) shstrtab;
off_t shstrtab_offset = static_cast<off_t>(elf_header.e_shoff) +
elf_header.e_shentsize * elf_header.e_shstrndx;
if (!file.ReadFromOffsetExact(&shstrtab, sizeof(shstrtab), shstrtab_offset)) {
return false;
}
for (int i = 0; i < elf_header.e_shnum; ++i) {
off_t section_header_offset =
static_cast<off_t>(elf_header.e_shoff) + elf_header.e_shentsize * i;
if (!file.ReadFromOffsetExact(out, sizeof(*out), section_header_offset)) {
return false;
}
off_t name_offset = static_cast<off_t>(shstrtab.sh_offset) + out->sh_name;
ssize_t n_read = file.ReadFromOffset(&header_name, name_len, name_offset);
if (n_read < 0) {
return false;
} else if (static_cast<size_t>(n_read) != name_len) {
// Short read -- name could be at end of file.
continue;
}
if (memcmp(header_name, name, name_len) == 0) {
return true;
}
}
return false;
}
// Compare symbols at in the same address.
// Return true if we should pick symbol1.
static bool ShouldPickFirstSymbol(const ElfW(Sym) & symbol1,
const ElfW(Sym) & symbol2) {
// If one of the symbols is weak and the other is not, pick the one
// this is not a weak symbol.
char bind1 = ELF_ST_BIND(symbol1.st_info);
char bind2 = ELF_ST_BIND(symbol1.st_info);
if (bind1 == STB_WEAK && bind2 != STB_WEAK) return false;
if (bind2 == STB_WEAK && bind1 != STB_WEAK) return true;
// If one of the symbols has zero size and the other is not, pick the
// one that has non-zero size.
if (symbol1.st_size != 0 && symbol2.st_size == 0) {
return true;
}
if (symbol1.st_size == 0 && symbol2.st_size != 0) {
return false;
}
// If one of the symbols has no type and the other is not, pick the
// one that has a type.
char type1 = ELF_ST_TYPE(symbol1.st_info);
char type2 = ELF_ST_TYPE(symbol1.st_info);
if (type1 != STT_NOTYPE && type2 == STT_NOTYPE) {
return true;
}
if (type1 == STT_NOTYPE && type2 != STT_NOTYPE) {
return false;
}
// Pick the first one, if we still cannot decide.
return true;
}
// Return true if an address is inside a section.
static bool InSection(const void *address, ptrdiff_t relocation,
const ElfW(Shdr) * section) {
const char *start = reinterpret_cast<const char *>(
section->sh_addr + static_cast<ElfW(Addr)>(relocation));
size_t size = static_cast<size_t>(section->sh_size);
return start <= address && address < (start + size);
}
static const char *ComputeOffset(const char *base, ptrdiff_t offset) {
// Note: cast to intptr_t to avoid undefined behavior when base evaluates to
// zero and offset is non-zero.
return reinterpret_cast<const char *>(reinterpret_cast<intptr_t>(base) +
offset);
}
// Read a symbol table and look for the symbol containing the
// pc. Iterate over symbols in a symbol table and look for the symbol
// containing "pc". If the symbol is found, and its name fits in
// out_size, the name is written into out and SYMBOL_FOUND is returned.
// If the name does not fit, truncated name is written into out,
// and SYMBOL_TRUNCATED is returned. Out is NUL-terminated.
// If the symbol is not found, SYMBOL_NOT_FOUND is returned;
// To keep stack consumption low, we would like this function to not get
// inlined.
static ABSL_ATTRIBUTE_NOINLINE FindSymbolResult FindSymbol(
const void *const pc, CachingFile *file, char *out, size_t out_size,
ptrdiff_t relocation, const ElfW(Shdr) * strtab, const ElfW(Shdr) * symtab,
const ElfW(Shdr) * opd, char *tmp_buf, size_t tmp_buf_size) {
if (symtab == nullptr) {
return SYMBOL_NOT_FOUND;
}
// Read multiple symbols at once to save read() calls.
ElfW(Sym) *buf = reinterpret_cast<ElfW(Sym) *>(tmp_buf);
const size_t buf_entries = tmp_buf_size / sizeof(buf[0]);
const size_t num_symbols = symtab->sh_size / symtab->sh_entsize;
// On platforms using an .opd section (PowerPC & IA64), a function symbol
// has the address of a function descriptor, which contains the real
// starting address. However, we do not always want to use the real
// starting address because we sometimes want to symbolize a function
// pointer into the .opd section, e.g. FindSymbol(&foo,...).
const bool pc_in_opd = kPlatformUsesOPDSections && opd != nullptr &&
InSection(pc, relocation, opd);
const bool deref_function_descriptor_pointer =
kPlatformUsesOPDSections && opd != nullptr && !pc_in_opd;
ElfW(Sym) best_match;
SafeMemZero(&best_match, sizeof(best_match));
bool found_match = false;
for (size_t i = 0; i < num_symbols;) {
off_t offset =
static_cast<off_t>(symtab->sh_offset + i * symtab->sh_entsize);
const size_t num_remaining_symbols = num_symbols - i;
const size_t entries_in_chunk =
std::min(num_remaining_symbols, buf_entries);
const size_t bytes_in_chunk = entries_in_chunk * sizeof(buf[0]);
const ssize_t len = file->ReadFromOffset(buf, bytes_in_chunk, offset);
SAFE_ASSERT(len >= 0);
SAFE_ASSERT(static_cast<size_t>(len) % sizeof(buf[0]) == 0);
const size_t num_symbols_in_buf = static_cast<size_t>(len) / sizeof(buf[0]);
SAFE_ASSERT(num_symbols_in_buf <= entries_in_chunk);
for (size_t j = 0; j < num_symbols_in_buf; ++j) {
const ElfW(Sym) &symbol = buf[j];
// For a DSO, a symbol address is relocated by the loading address.
// We keep the original address for opd redirection below.
const char *const original_start_address =
reinterpret_cast<const char *>(symbol.st_value);
const char *start_address =
ComputeOffset(original_start_address, relocation);
#ifdef __arm__
// ARM functions are always aligned to multiples of two bytes; the
// lowest-order bit in start_address is ignored by the CPU and indicates
// whether the function contains ARM (0) or Thumb (1) code. We don't care
// about what encoding is being used; we just want the real start address
// of the function.
start_address = reinterpret_cast<const char *>(
reinterpret_cast<uintptr_t>(start_address) & ~1u);
#endif
if (deref_function_descriptor_pointer &&
InSection(original_start_address, /*relocation=*/0, opd)) {
// The opd section is mapped into memory. Just dereference
// start_address to get the first double word, which points to the
// function entry.
start_address = *reinterpret_cast<const char *const *>(start_address);
}
// If pc is inside the .opd section, it points to a function descriptor.
const size_t size = pc_in_opd ? kFunctionDescriptorSize : symbol.st_size;
const void *const end_address =
ComputeOffset(start_address, static_cast<ptrdiff_t>(size));
if (symbol.st_value != 0 && // Skip null value symbols.
symbol.st_shndx != 0 && // Skip undefined symbols.
#ifdef STT_TLS
ELF_ST_TYPE(symbol.st_info) != STT_TLS && // Skip thread-local data.
#endif // STT_TLS
((start_address <= pc && pc < end_address) ||
(start_address == pc && pc == end_address))) {
if (!found_match || ShouldPickFirstSymbol(symbol, best_match)) {
found_match = true;
best_match = symbol;
}
}
}
i += num_symbols_in_buf;
}
if (found_match) {
const off_t off =
static_cast<off_t>(strtab->sh_offset) + best_match.st_name;
const ssize_t n_read = file->ReadFromOffset(out, out_size, off);
if (n_read <= 0) {
// This should never happen.
ABSL_RAW_LOG(WARNING,
"Unable to read from fd %d at offset %lld: n_read = %zd",
file->fd(), static_cast<long long>(off), n_read);
return SYMBOL_NOT_FOUND;
}
ABSL_RAW_CHECK(static_cast<size_t>(n_read) <= out_size,
"ReadFromOffset read too much data.");
// strtab->sh_offset points into .strtab-like section that contains
// NUL-terminated strings: '\0foo\0barbaz\0...".
//
// sh_offset+st_name points to the start of symbol name, but we don't know
// how long the symbol is, so we try to read as much as we have space for,
// and usually over-read (i.e. there is a NUL somewhere before n_read).
if (memchr(out, '\0', static_cast<size_t>(n_read)) == nullptr) {
// Either out_size was too small (n_read == out_size and no NUL), or
// we tried to read past the EOF (n_read < out_size) and .strtab is
// corrupt (missing terminating NUL; should never happen for valid ELF).
out[n_read - 1] = '\0';
return SYMBOL_TRUNCATED;
}
return SYMBOL_FOUND;
}
return SYMBOL_NOT_FOUND;
}
// Get the symbol name of "pc" from the file pointed by "fd". Process
// both regular and dynamic symbol tables if necessary.
// See FindSymbol() comment for description of return value.
FindSymbolResult Symbolizer::GetSymbolFromObjectFile(
const ObjFile &obj, const void *const pc, const ptrdiff_t relocation,
char *out, size_t out_size, char *tmp_buf, size_t tmp_buf_size) {
ElfW(Shdr) symtab;
ElfW(Shdr) strtab;
ElfW(Shdr) opd;
ElfW(Shdr) *opd_ptr = nullptr;
// On platforms using an .opd sections for function descriptor, read
// the section header. The .opd section is in data segment and should be
// loaded but we check that it is mapped just to be extra careful.
if (kPlatformUsesOPDSections) {
if (GetSectionHeaderByName(obj.fd, kOpdSectionName,
sizeof(kOpdSectionName) - 1, &opd) &&
FindObjFile(reinterpret_cast<const char *>(opd.sh_addr) + relocation,
opd.sh_size) != nullptr) {
opd_ptr = &opd;
} else {
return SYMBOL_NOT_FOUND;
}
}
CachingFile file(obj.fd, file_cache_, sizeof(file_cache_));
// Consult a regular symbol table, then fall back to the dynamic symbol table.
for (const auto symbol_table_type : {SHT_SYMTAB, SHT_DYNSYM}) {
if (!GetSectionHeaderByType(&file, obj.elf_header.e_shnum,
static_cast<off_t>(obj.elf_header.e_shoff),
static_cast<ElfW(Word)>(symbol_table_type),
&symtab, tmp_buf, tmp_buf_size)) {
continue;
}
if (!file.ReadFromOffsetExact(
&strtab, sizeof(strtab),
static_cast<off_t>(obj.elf_header.e_shoff +
symtab.sh_link * sizeof(symtab)))) {
continue;
}
const FindSymbolResult rc =
FindSymbol(pc, &file, out, out_size, relocation, &strtab, &symtab,
opd_ptr, tmp_buf, tmp_buf_size);
if (rc != SYMBOL_NOT_FOUND) {
return rc;
}
}
return SYMBOL_NOT_FOUND;
}
namespace {
// Thin wrapper around a file descriptor so that the file descriptor
// gets closed for sure.
class FileDescriptor {
public:
explicit FileDescriptor(int fd) : fd_(fd) {}
FileDescriptor(const FileDescriptor &) = delete;
FileDescriptor &operator=(const FileDescriptor &) = delete;
~FileDescriptor() {
if (fd_ >= 0) {
close(fd_);
}
}
int get() const { return fd_; }
private:
const int fd_;
};
// Helper class for reading lines from file.
//
// Note: we don't use ProcMapsIterator since the object is big (it has
// a 5k array member) and uses async-unsafe functions such as sscanf()
// and snprintf().
class LineReader {
public:
explicit LineReader(int fd, char *buf, size_t buf_len)
: fd_(fd),
buf_len_(buf_len),
buf_(buf),
bol_(buf),
eol_(buf),
eod_(buf) {}
LineReader(const LineReader &) = delete;
LineReader &operator=(const LineReader &) = delete;
// Read '\n'-terminated line from file. On success, modify "bol"
// and "eol", then return true. Otherwise, return false.
//
// Note: if the last line doesn't end with '\n', the line will be
// dropped. It's an intentional behavior to make the code simple.
bool ReadLine(const char **bol, const char **eol) {
if (BufferIsEmpty()) { // First time.
const ssize_t num_bytes = ReadPersistent(fd_, buf_, buf_len_);
if (num_bytes <= 0) { // EOF or error.
return false;
}
eod_ = buf_ + num_bytes;
bol_ = buf_;
} else {
bol_ = eol_ + 1; // Advance to the next line in the buffer.
SAFE_ASSERT(bol_ <= eod_); // "bol_" can point to "eod_".
if (!HasCompleteLine()) {
const auto incomplete_line_length = static_cast<size_t>(eod_ - bol_);
// Move the trailing incomplete line to the beginning.
memmove(buf_, bol_, incomplete_line_length);
// Read text from file and append it.
char *const append_pos = buf_ + incomplete_line_length;
const size_t capacity_left = buf_len_ - incomplete_line_length;
const ssize_t num_bytes =
ReadPersistent(fd_, append_pos, capacity_left);
if (num_bytes <= 0) { // EOF or error.
return false;
}
eod_ = append_pos + num_bytes;
bol_ = buf_;
}
}
eol_ = FindLineFeed();
if (eol_ == nullptr) { // '\n' not found. Malformed line.
return false;
}
*eol_ = '\0'; // Replace '\n' with '\0'.
*bol = bol_;
*eol = eol_;
return true;
}
private:
char *FindLineFeed() const {
return reinterpret_cast<char *>(
memchr(bol_, '\n', static_cast<size_t>(eod_ - bol_)));
}
bool BufferIsEmpty() const { return buf_ == eod_; }
bool HasCompleteLine() const {
return !BufferIsEmpty() && FindLineFeed() != nullptr;
}
const int fd_;
const size_t buf_len_;
char *const buf_;
char *bol_;
char *eol_;
const char *eod_; // End of data in "buf_".
};
} // namespace
// Place the hex number read from "start" into "*hex". The pointer to
// the first non-hex character or "end" is returned.
static const char *GetHex(const char *start, const char *end,
uint64_t *const value) {
uint64_t hex = 0;
const char *p;
for (p = start; p < end; ++p) {
int ch = *p;
if ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'F') ||
(ch >= 'a' && ch <= 'f')) {
hex = (hex << 4) |
static_cast<uint64_t>(ch < 'A' ? ch - '0' : (ch & 0xF) + 9);
} else { // Encountered the first non-hex character.
break;
}
}
SAFE_ASSERT(p <= end);
*value = hex;
return p;
}
static const char *GetHex(const char *start, const char *end,
const void **const addr) {
uint64_t hex = 0;
const char *p = GetHex(start, end, &hex);
*addr = reinterpret_cast<void *>(hex);
return p;
}
// Normally we are only interested in "r?x" maps.
// On the PowerPC, function pointers point to descriptors in the .opd
// section. The descriptors themselves are not executable code, so
// we need to relax the check below to "r??".
static bool ShouldUseMapping(const char *const flags) {
return flags[0] == 'r' && (kPlatformUsesOPDSections || flags[2] == 'x');
}
// Read /proc/self/maps and run "callback" for each mmapped file found. If
// "callback" returns false, stop scanning and return true. Else continue
// scanning /proc/self/maps. Return true if no parse error is found.
static ABSL_ATTRIBUTE_NOINLINE bool ReadAddrMap(
bool (*callback)(const char *filename, const void *const start_addr,
const void *const end_addr, uint64_t offset, void *arg),
void *arg, void *tmp_buf, size_t tmp_buf_size) {
// Use /proc/self/task/<pid>/maps instead of /proc/self/maps. The latter
// requires kernel to stop all threads, and is significantly slower when there
// are 1000s of threads.
char maps_path[80];
snprintf(maps_path, sizeof(maps_path), "/proc/self/task/%d/maps", getpid());
int maps_fd;
NO_INTR(maps_fd = open(maps_path, O_RDONLY));
FileDescriptor wrapped_maps_fd(maps_fd);
if (wrapped_maps_fd.get() < 0) {
ABSL_RAW_LOG(WARNING, "%s: errno=%d", maps_path, errno);
return false;
}
// Iterate over maps and look for the map containing the pc. Then
// look into the symbol tables inside.
LineReader reader(wrapped_maps_fd.get(), static_cast<char *>(tmp_buf),
tmp_buf_size);
while (true) {
const char *cursor;
const char *eol;
if (!reader.ReadLine(&cursor, &eol)) { // EOF or malformed line.
break;
}
const char *line = cursor;
const void *start_address;
// Start parsing line in /proc/self/maps. Here is an example:
//
// 08048000-0804c000 r-xp 00000000 08:01 2142121 /bin/cat
//
// We want start address (08048000), end address (0804c000), flags
// (r-xp) and file name (/bin/cat).
// Read start address.
cursor = GetHex(cursor, eol, &start_address);
if (cursor == eol || *cursor != '-') {
ABSL_RAW_LOG(WARNING, "Corrupt /proc/self/maps line: %s", line);
return false;
}
++cursor; // Skip '-'.
// Read end address.
const void *end_address;
cursor = GetHex(cursor, eol, &end_address);
if (cursor == eol || *cursor != ' ') {
ABSL_RAW_LOG(WARNING, "Corrupt /proc/self/maps line: %s", line);
return false;
}
++cursor; // Skip ' '.
// Read flags. Skip flags until we encounter a space or eol.
const char *const flags_start = cursor;
while (cursor < eol && *cursor != ' ') {
++cursor;
}
// We expect at least four letters for flags (ex. "r-xp").
if (cursor == eol || cursor < flags_start + 4) {
ABSL_RAW_LOG(WARNING, "Corrupt /proc/self/maps: %s", line);
return false;
}
// Check flags.
if (!ShouldUseMapping(flags_start)) {
continue; // We skip this map.
}
++cursor; // Skip ' '.
// Read file offset.
uint64_t offset;
cursor = GetHex(cursor, eol, &offset);
++cursor; // Skip ' '.
// Skip to file name. "cursor" now points to dev. We need to skip at least
// two spaces for dev and inode.
int num_spaces = 0;
while (cursor < eol) {
if (*cursor == ' ') {
++num_spaces;
} else if (num_spaces >= 2) {
// The first non-space character after skipping two spaces
// is the beginning of the file name.
break;
}
++cursor;
}
// Check whether this entry corresponds to our hint table for the true
// filename.
bool hinted =
GetFileMappingHint(&start_address, &end_address, &offset, &cursor);
if (!hinted && (cursor == eol || cursor[0] == '[')) {
// not an object file, typically [vdso] or [vsyscall]
continue;
}
if (!callback(cursor, start_address, end_address, offset, arg)) break;
}
return true;
}
// Find the objfile mapped in address region containing [addr, addr + len).
ObjFile *Symbolizer::FindObjFile(const void *const addr, size_t len) {
for (int i = 0; i < 2; ++i) {
if (!ok_) return nullptr;
// Read /proc/self/maps if necessary
if (!addr_map_read_) {
addr_map_read_ = true;
if (!ReadAddrMap(RegisterObjFile, this, tmp_buf_, TMP_BUF_SIZE)) {
ok_ = false;
return nullptr;
}
}
size_t lo = 0;
size_t hi = addr_map_.Size();
while (lo < hi) {
size_t mid = (lo + hi) / 2;
if (addr < addr_map_.At(mid)->end_addr) {
hi = mid;
} else {
lo = mid + 1;
}
}
if (lo != addr_map_.Size()) {
ObjFile *obj = addr_map_.At(lo);
SAFE_ASSERT(obj->end_addr > addr);
if (addr >= obj->start_addr &&
reinterpret_cast<const char *>(addr) + len <= obj->end_addr)
return obj;
}
// The address mapping may have changed since it was last read. Retry.
ClearAddrMap();
}
return nullptr;
}
void Symbolizer::ClearAddrMap() {
for (size_t i = 0; i != addr_map_.Size(); i++) {
ObjFile *o = addr_map_.At(i);
base_internal::LowLevelAlloc::Free(o->filename);
if (o->fd >= 0) {
close(o->fd);
}
}
addr_map_.Clear();
addr_map_read_ = false;
}
// Callback for ReadAddrMap to register objfiles in an in-memory table.
bool Symbolizer::RegisterObjFile(const char *filename,
const void *const start_addr,
const void *const end_addr, uint64_t offset,
void *arg) {
Symbolizer *impl = static_cast<Symbolizer *>(arg);
// Files are supposed to be added in the increasing address order. Make
// sure that's the case.
size_t addr_map_size = impl->addr_map_.Size();
if (addr_map_size != 0) {
ObjFile *old = impl->addr_map_.At(addr_map_size - 1);
if (old->end_addr > end_addr) {
ABSL_RAW_LOG(ERROR,
"Unsorted addr map entry: 0x%" PRIxPTR ": %s <-> 0x%" PRIxPTR
": %s",
reinterpret_cast<uintptr_t>(end_addr), filename,
reinterpret_cast<uintptr_t>(old->end_addr), old->filename);
return true;
} else if (old->end_addr == end_addr) {
// The same entry appears twice. This sometimes happens for [vdso].
if (old->start_addr != start_addr ||
strcmp(old->filename, filename) != 0) {
ABSL_RAW_LOG(ERROR,
"Duplicate addr 0x%" PRIxPTR ": %s <-> 0x%" PRIxPTR ": %s",
reinterpret_cast<uintptr_t>(end_addr), filename,
reinterpret_cast<uintptr_t>(old->end_addr), old->filename);
}
return true;
} else if (old->end_addr == start_addr &&
reinterpret_cast<uintptr_t>(old->start_addr) - old->offset ==
reinterpret_cast<uintptr_t>(start_addr) - offset &&
strcmp(old->filename, filename) == 0) {
// Two contiguous map entries that span a contiguous region of the file,
// perhaps because some part of the file was mlock()ed. Combine them.
old->end_addr = end_addr;
return true;
}
}
ObjFile *obj = impl->addr_map_.Add();
obj->filename = impl->CopyString(filename);
obj->start_addr = start_addr;
obj->end_addr = end_addr;
obj->offset = offset;
obj->elf_type = -1; // filled on demand
obj->fd = -1; // opened on demand
return true;
}
// This function wraps the Demangle function to provide an interface
// where the input symbol is demangled in-place.
// To keep stack consumption low, we would like this function to not
// get inlined.
static ABSL_ATTRIBUTE_NOINLINE void DemangleInplace(char *out, size_t out_size,
char *tmp_buf,
size_t tmp_buf_size) {
if (Demangle(out, tmp_buf, tmp_buf_size)) {
// Demangling succeeded. Copy to out if the space allows.
size_t len = strlen(tmp_buf);
if (len + 1 <= out_size) { // +1 for '\0'.
SAFE_ASSERT(len < tmp_buf_size);
memmove(out, tmp_buf, len + 1);
}
}
}
SymbolCacheLine *Symbolizer::GetCacheLine(const void *const pc) {
uintptr_t pc0 = reinterpret_cast<uintptr_t>(pc);
pc0 >>= 3; // drop the low 3 bits
// Shuffle bits.
pc0 ^= (pc0 >> 6) ^ (pc0 >> 12) ^ (pc0 >> 18);
return &symbol_cache_[pc0 % SYMBOL_CACHE_LINES];
}
void Symbolizer::AgeSymbols(SymbolCacheLine *line) {
for (uint32_t &age : line->age) {
++age;
}
}
const char *Symbolizer::FindSymbolInCache(const void *const pc) {
if (pc == nullptr) return nullptr;
SymbolCacheLine *line = GetCacheLine(pc);
for (size_t i = 0; i < ABSL_ARRAYSIZE(line->pc); ++i) {
if (line->pc[i] == pc) {
AgeSymbols(line);
line->age[i] = 0;
return line->name[i];
}
}
return nullptr;
}
const char *Symbolizer::InsertSymbolInCache(const void *const pc,
const char *name) {
SAFE_ASSERT(pc != nullptr);
SymbolCacheLine *line = GetCacheLine(pc);
uint32_t max_age = 0;
size_t oldest_index = 0;
bool found_oldest_index = false;
for (size_t i = 0; i < ABSL_ARRAYSIZE(line->pc); ++i) {
if (line->pc[i] == nullptr) {
AgeSymbols(line);
line->pc[i] = pc;
line->name[i] = CopyString(name);
line->age[i] = 0;
return line->name[i];
}
if (line->age[i] >= max_age) {
max_age = line->age[i];
oldest_index = i;
found_oldest_index = true;
}
}
AgeSymbols(line);
ABSL_RAW_CHECK(found_oldest_index, "Corrupt cache");
base_internal::LowLevelAlloc::Free(line->name[oldest_index]);
line->pc[oldest_index] = pc;
line->name[oldest_index] = CopyString(name);
line->age[oldest_index] = 0;
return line->name[oldest_index];
}
static void MaybeOpenFdFromSelfExe(ObjFile *obj) {
if (memcmp(obj->start_addr, ELFMAG, SELFMAG) != 0) {
return;
}
int fd = open("/proc/self/exe", O_RDONLY);
if (fd == -1) {
return;
}
// Verify that contents of /proc/self/exe matches in-memory image of
// the binary. This can fail if the "deleted" binary is in fact not
// the main executable, or for binaries that have the first PT_LOAD
// segment smaller than 4K. We do it in four steps so that the
// buffer is smaller and we don't consume too much stack space.
const char *mem = reinterpret_cast<const char *>(obj->start_addr);
for (int i = 0; i < 4; ++i) {
char buf[1024];
ssize_t n = read(fd, buf, sizeof(buf));
if (n != sizeof(buf) || memcmp(buf, mem, sizeof(buf)) != 0) {
close(fd);
return;
}
mem += sizeof(buf);
}
obj->fd = fd;
}
static bool MaybeInitializeObjFile(ObjFile *obj) {
if (obj->fd < 0) {
obj->fd = open(obj->filename, O_RDONLY);
if (obj->fd < 0) {
// Getting /proc/self/exe here means that we were hinted.
if (strcmp(obj->filename, "/proc/self/exe") == 0) {
// /proc/self/exe may be inaccessible (due to setuid, etc.), so try
// accessing the binary via argv0.
if (argv0_value != nullptr) {
obj->fd = open(argv0_value, O_RDONLY);
}
} else {
MaybeOpenFdFromSelfExe(obj);
}
}
if (obj->fd < 0) {
ABSL_RAW_LOG(WARNING, "%s: open failed: errno=%d", obj->filename, errno);
return false;
}
char buf[kSmallFileCacheSize];
CachingFile file(obj->fd, buf, sizeof(buf));
obj->elf_type = FileGetElfType(&file);
if (obj->elf_type < 0) {
ABSL_RAW_LOG(WARNING, "%s: wrong elf type: %d", obj->filename,
obj->elf_type);
return false;
}
if (!file.ReadFromOffsetExact(&obj->elf_header, sizeof(obj->elf_header),
0)) {
ABSL_RAW_LOG(WARNING, "%s: failed to read elf header", obj->filename);
return false;
}
const int phnum = obj->elf_header.e_phnum;
const int phentsize = obj->elf_header.e_phentsize;
auto phoff = static_cast<off_t>(obj->elf_header.e_phoff);
size_t num_interesting_load_segments = 0;
for (int j = 0; j < phnum; j++) {
ElfW(Phdr) phdr;
if (!file.ReadFromOffsetExact(&phdr, sizeof(phdr), phoff)) {
ABSL_RAW_LOG(WARNING, "%s: failed to read program header %d",
obj->filename, j);
return false;
}
phoff += phentsize;
#if defined(__powerpc__) && !(_CALL_ELF > 1)
// On the PowerPC ELF v1 ABI, function pointers actually point to function
// descriptors. These descriptors are stored in an .opd section, which is
// mapped read-only. We thus need to look at all readable segments, not
// just the executable ones.
constexpr int interesting = PF_R;
#else
constexpr int interesting = PF_X | PF_R;
#endif
if (phdr.p_type != PT_LOAD
|| (phdr.p_flags & interesting) != interesting) {
// Not a LOAD segment, not executable code, and not a function
// descriptor.
continue;
}
if (num_interesting_load_segments < obj->phdr.size()) {
memcpy(&obj->phdr[num_interesting_load_segments++], &phdr, sizeof(phdr));
} else {
ABSL_RAW_LOG(
WARNING, "%s: too many interesting LOAD segments: %zu >= %zu",
obj->filename, num_interesting_load_segments, obj->phdr.size());
break;
}
}
if (num_interesting_load_segments == 0) {
// This object has no interesting LOAD segments. That's unexpected.
ABSL_RAW_LOG(WARNING, "%s: no interesting LOAD segments", obj->filename);
return false;
}
}
return true;
}
// The implementation of our symbolization routine. If it
// successfully finds the symbol containing "pc" and obtains the
// symbol name, returns pointer to that symbol. Otherwise, returns nullptr.
// If any symbol decorators have been installed via InstallSymbolDecorator(),
// they are called here as well.
// To keep stack consumption low, we would like this function to not
// get inlined.
const char *Symbolizer::GetUncachedSymbol(const void *pc) {
ObjFile *const obj = FindObjFile(pc, 1);
ptrdiff_t relocation = 0;
int fd = -1;
if (obj != nullptr) {
if (MaybeInitializeObjFile(obj)) {
const size_t start_addr = reinterpret_cast<size_t>(obj->start_addr);
if (obj->elf_type == ET_DYN && start_addr >= obj->offset) {
// This object was relocated.
//
// For obj->offset > 0, adjust the relocation since a mapping at offset
// X in the file will have a start address of [true relocation]+X.
relocation = static_cast<ptrdiff_t>(start_addr - obj->offset);
// Note: some binaries have multiple LOAD segments that can contain
// function pointers. We must find the right one.
ElfW(Phdr) *phdr = nullptr;
for (size_t j = 0; j < obj->phdr.size(); j++) {
ElfW(Phdr) &p = obj->phdr[j];
if (p.p_type != PT_LOAD) {
// We only expect PT_LOADs. This must be PT_NULL that we didn't
// write over (i.e. we exhausted all interesting PT_LOADs).
ABSL_RAW_CHECK(p.p_type == PT_NULL, "unexpected p_type");
break;
}
if (pc < reinterpret_cast<void *>(start_addr + p.p_vaddr + p.p_memsz)) {
phdr = &p;
break;
}
}
if (phdr == nullptr) {
// That's unexpected. Hope for the best.
ABSL_RAW_LOG(
WARNING,
"%s: unable to find LOAD segment for pc: %p, start_addr: %zx",
obj->filename, pc, start_addr);
} else {
// Adjust relocation in case phdr.p_vaddr != 0.
// This happens for binaries linked with `lld --rosegment`, and for
// binaries linked with BFD `ld -z separate-code`.
relocation -= phdr->p_vaddr - phdr->p_offset;
}
}
fd = obj->fd;
if (GetSymbolFromObjectFile(*obj, pc, relocation, symbol_buf_,
sizeof(symbol_buf_), tmp_buf_,
sizeof(tmp_buf_)) == SYMBOL_FOUND) {
// Only try to demangle the symbol name if it fit into symbol_buf_.
DemangleInplace(symbol_buf_, sizeof(symbol_buf_), tmp_buf_,
sizeof(tmp_buf_));
}
}
} else {
#if ABSL_HAVE_VDSO_SUPPORT
VDSOSupport vdso;
if (vdso.IsPresent()) {
VDSOSupport::SymbolInfo symbol_info;
if (vdso.LookupSymbolByAddress(pc, &symbol_info)) {
// All VDSO symbols are known to be short.
size_t len = strlen(symbol_info.name);
ABSL_RAW_CHECK(len + 1 < sizeof(symbol_buf_),
"VDSO symbol unexpectedly long");
memcpy(symbol_buf_, symbol_info.name, len + 1);
}
}
#endif
}
if (g_decorators_mu.TryLock()) {
if (g_num_decorators > 0) {
SymbolDecoratorArgs decorator_args = {
pc, relocation, fd, symbol_buf_, sizeof(symbol_buf_),
tmp_buf_, sizeof(tmp_buf_), nullptr};
for (int i = 0; i < g_num_decorators; ++i) {
decorator_args.arg = g_decorators[i].arg;
g_decorators[i].fn(&decorator_args);
}
}
g_decorators_mu.Unlock();
}
if (symbol_buf_[0] == '\0') {
return nullptr;
}
symbol_buf_[sizeof(symbol_buf_) - 1] = '\0'; // Paranoia.
return InsertSymbolInCache(pc, symbol_buf_);
}
const char *Symbolizer::GetSymbol(const void *pc) {
const char *entry = FindSymbolInCache(pc);
if (entry != nullptr) {
return entry;
}
symbol_buf_[0] = '\0';
#ifdef __hppa__
{
// In some contexts (e.g., return addresses), PA-RISC uses the lowest two
// bits of the address to indicate the privilege level. Clear those bits
// before trying to symbolize.
const auto pc_bits = reinterpret_cast<uintptr_t>(pc);
const auto address = pc_bits & ~0x3;
entry = GetUncachedSymbol(reinterpret_cast<const void *>(address));
if (entry != nullptr) {
return entry;
}
// In some contexts, PA-RISC also uses bit 1 of the address to indicate that
// this is a cross-DSO function pointer. Such function pointers actually
// point to a procedure label, a struct whose first 32-bit (pointer) element
// actually points to the function text. With no symbol found for this
// address so far, try interpreting it as a cross-DSO function pointer and
// see how that goes.
if (pc_bits & 0x2) {
return GetUncachedSymbol(*reinterpret_cast<const void *const *>(address));
}
return nullptr;
}
#else
return GetUncachedSymbol(pc);
#endif
}
bool RemoveAllSymbolDecorators(void) {
if (!g_decorators_mu.TryLock()) {
// Someone else is using decorators. Get out.
return false;
}
g_num_decorators = 0;
g_decorators_mu.Unlock();
return true;
}
bool RemoveSymbolDecorator(int ticket) {
if (!g_decorators_mu.TryLock()) {
// Someone else is using decorators. Get out.
return false;
}
for (int i = 0; i < g_num_decorators; ++i) {
if (g_decorators[i].ticket == ticket) {
while (i < g_num_decorators - 1) {
g_decorators[i] = g_decorators[i + 1];
++i;
}
g_num_decorators = i;
break;
}
}
g_decorators_mu.Unlock();
return true; // Decorator is known to be removed.
}
int InstallSymbolDecorator(SymbolDecorator decorator, void *arg) {
static int ticket = 0;
if (!g_decorators_mu.TryLock()) {
// Someone else is using decorators. Get out.
return -2;
}
int ret = ticket;
if (g_num_decorators >= kMaxDecorators) {
ret = -1;
} else {
g_decorators[g_num_decorators] = {decorator, arg, ticket++};
++g_num_decorators;
}
g_decorators_mu.Unlock();
return ret;
}
bool RegisterFileMappingHint(const void *start, const void *end, uint64_t offset,
const char *filename) {
SAFE_ASSERT(start <= end);
SAFE_ASSERT(filename != nullptr);
InitSigSafeArena();
if (!g_file_mapping_mu.TryLock()) {
return false;
}
bool ret = true;
if (g_num_file_mapping_hints >= kMaxFileMappingHints) {
ret = false;
} else {
// TODO(ckennelly): Move this into a string copy routine.
size_t len = strlen(filename);
char *dst = static_cast<char *>(
base_internal::LowLevelAlloc::AllocWithArena(len + 1, SigSafeArena()));
ABSL_RAW_CHECK(dst != nullptr, "out of memory");
memcpy(dst, filename, len + 1);
auto &hint = g_file_mapping_hints[g_num_file_mapping_hints++];
hint.start = start;
hint.end = end;
hint.offset = offset;
hint.filename = dst;
}
g_file_mapping_mu.Unlock();
return ret;
}
bool GetFileMappingHint(const void **start, const void **end, uint64_t *offset,
const char **filename) {
if (!g_file_mapping_mu.TryLock()) {
return false;
}
bool found = false;
for (int i = 0; i < g_num_file_mapping_hints; i++) {
if (g_file_mapping_hints[i].start <= *start &&
*end <= g_file_mapping_hints[i].end) {
// We assume that the start_address for the mapping is the base
// address of the ELF section, but when [start_address,end_address) is
// not strictly equal to [hint.start, hint.end), that assumption is
// invalid.
//
// This uses the hint's start address (even though hint.start is not
// necessarily equal to start_address) to ensure the correct
// relocation is computed later.
*start = g_file_mapping_hints[i].start;
*end = g_file_mapping_hints[i].end;
*offset = g_file_mapping_hints[i].offset;
*filename = g_file_mapping_hints[i].filename;
found = true;
break;
}
}
g_file_mapping_mu.Unlock();
return found;
}
} // namespace debugging_internal
bool Symbolize(const void *pc, char *out, int out_size) {
// Symbolization is very slow under tsan.
ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_BEGIN();
SAFE_ASSERT(out_size >= 0);
debugging_internal::Symbolizer *s = debugging_internal::AllocateSymbolizer();
const char *name = s->GetSymbol(pc);
bool ok = false;
if (name != nullptr && out_size > 0) {
strncpy(out, name, static_cast<size_t>(out_size));
ok = true;
if (out[static_cast<size_t>(out_size) - 1] != '\0') {
// strncpy() does not '\0' terminate when it truncates. Do so, with
// trailing ellipsis.
static constexpr char kEllipsis[] = "...";
size_t ellipsis_size =
std::min(strlen(kEllipsis), static_cast<size_t>(out_size) - 1);
memcpy(out + static_cast<size_t>(out_size) - ellipsis_size - 1, kEllipsis,
ellipsis_size);
out[static_cast<size_t>(out_size) - 1] = '\0';
}
}
debugging_internal::FreeSymbolizer(s);
ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_END();
return ok;
}
ABSL_NAMESPACE_END
} // namespace absl
extern "C" bool AbslInternalGetFileMappingHint(const void **start,
const void **end, uint64_t *offset,
const char **filename) {
return absl::debugging_internal::GetFileMappingHint(start, end, offset,
filename);
}

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// Copyright 2020 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <cxxabi.h>
#include <emscripten.h>
#include <algorithm>
#include <cstring>
#include "absl/base/internal/raw_logging.h"
#include "absl/debugging/internal/demangle.h"
#include "absl/strings/numbers.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
extern "C" {
const char* emscripten_pc_get_function(const void* pc);
}
// clang-format off
EM_JS(bool, HaveOffsetConverter, (),
{ return typeof wasmOffsetConverter !== 'undefined'; });
// clang-format on
namespace absl {
ABSL_NAMESPACE_BEGIN
void InitializeSymbolizer(const char*) {
if (!HaveOffsetConverter()) {
ABSL_RAW_LOG(INFO,
"Symbolization unavailable. Rebuild with -sWASM=1 "
"and -sUSE_OFFSET_CONVERTER=1.");
}
}
bool Symbolize(const void* pc, char* out, int out_size) {
// Check if we have the offset converter necessary for pc_get_function.
// Without it, the program will abort().
if (!HaveOffsetConverter()) {
return false;
}
if (pc == nullptr || out_size <= 0) {
return false;
}
const char* func_name = emscripten_pc_get_function(pc);
if (func_name == nullptr) {
return false;
}
strncpy(out, func_name, out_size);
if (out[out_size - 1] != '\0') {
// strncpy() does not '\0' terminate when it truncates.
static constexpr char kEllipsis[] = "...";
int ellipsis_size = std::min<int>(sizeof(kEllipsis) - 1, out_size - 1);
memcpy(out + out_size - ellipsis_size - 1, kEllipsis, ellipsis_size);
out[out_size - 1] = '\0';
}
return true;
}
ABSL_NAMESPACE_END
} // namespace absl

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <cstdint>
#include "absl/base/internal/raw_logging.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
int InstallSymbolDecorator(SymbolDecorator, void*) { return -1; }
bool RemoveSymbolDecorator(int) { return false; }
bool RemoveAllSymbolDecorators(void) { return false; }
bool RegisterFileMappingHint(const void *, const void *, uint64_t, const char *) {
return false;
}
bool GetFileMappingHint(const void **, const void **, uint64_t *, const char **) {
return false;
}
} // namespace debugging_internal
void InitializeSymbolizer(const char*) {}
bool Symbolize(const void *, char *, int) { return false; }
ABSL_NAMESPACE_END
} // namespace absl

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// See "Retrieving Symbol Information by Address":
// https://msdn.microsoft.com/en-us/library/windows/desktop/ms680578(v=vs.85).aspx
#include <windows.h>
// MSVC header dbghelp.h has a warning for an ignored typedef.
#pragma warning(push)
#pragma warning(disable:4091)
#include <dbghelp.h>
#pragma warning(pop)
#pragma comment(lib, "dbghelp.lib")
#include <algorithm>
#include <cstring>
#include "absl/base/internal/raw_logging.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
static HANDLE process = NULL;
void InitializeSymbolizer(const char*) {
if (process != nullptr) {
return;
}
process = GetCurrentProcess();
// Symbols are not loaded until a reference is made requiring the
// symbols be loaded. This is the fastest, most efficient way to use
// the symbol handler.
SymSetOptions(SYMOPT_DEFERRED_LOADS | SYMOPT_UNDNAME);
if (!SymInitialize(process, nullptr, true)) {
// GetLastError() returns a Win32 DWORD, but we assign to
// unsigned long long to simplify the ABSL_RAW_LOG case below. The uniform
// initialization guarantees this is not a narrowing conversion.
const unsigned long long error{GetLastError()}; // NOLINT(runtime/int)
ABSL_RAW_LOG(FATAL, "SymInitialize() failed: %llu", error);
}
}
bool Symbolize(const void* pc, char* out, int out_size) {
if (out_size <= 0) {
return false;
}
alignas(SYMBOL_INFO) char buf[sizeof(SYMBOL_INFO) + MAX_SYM_NAME];
SYMBOL_INFO* symbol = reinterpret_cast<SYMBOL_INFO*>(buf);
symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
symbol->MaxNameLen = MAX_SYM_NAME;
if (!SymFromAddr(process, reinterpret_cast<DWORD64>(pc), nullptr, symbol)) {
return false;
}
const size_t out_size_t = static_cast<size_t>(out_size);
strncpy(out, symbol->Name, out_size_t);
if (out[out_size_t - 1] != '\0') {
// strncpy() does not '\0' terminate when it truncates.
static constexpr char kEllipsis[] = "...";
size_t ellipsis_size =
std::min(sizeof(kEllipsis) - 1, out_size_t - 1);
memcpy(out + out_size_t - ellipsis_size - 1, kEllipsis, ellipsis_size);
out[out_size_t - 1] = '\0';
}
return true;
}
ABSL_NAMESPACE_END
} // namespace absl