// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/debug/stack_trace.h"
#include <errno.h>
#include <execinfo.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <ostream>
#if defined(__GLIBCXX__)
#include <cxxabi.h>
#endif
#if defined(OS_MACOSX)
#include <AvailabilityMacros.h>
#endif
#include "base/basictypes.h"
#include "base/debug/debugger.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/posix/eintr_wrapper.h"
#include "base/strings/string_number_conversions.h"
#if defined(USE_SYMBOLIZE)
#include "base/third_party/symbolize/symbolize.h"
#endif
namespace base {
namespace debug {
namespace {
volatile sig_atomic_t in_signal_handler = 0;
#if !defined(USE_SYMBOLIZE) && defined(__GLIBCXX__)
// The prefix used for mangled symbols, per the Itanium C++ ABI:
// http://www.codesourcery.com/cxx-abi/abi.html#mangling
const char kMangledSymbolPrefix[] = "_Z";
// Characters that can be used for symbols, generated by Ruby:
// (('a'..'z').to_a+('A'..'Z').to_a+('0'..'9').to_a + ['_']).join
const char kSymbolCharacters[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_";
#endif // !defined(USE_SYMBOLIZE) && defined(__GLIBCXX__)
#if !defined(USE_SYMBOLIZE)
// Demangles C++ symbols in the given text. Example:
//
// "out/Debug/base_unittests(_ZN10StackTraceC1Ev+0x20) [0x817778c]"
// =>
// "out/Debug/base_unittests(StackTrace::StackTrace()+0x20) [0x817778c]"
void DemangleSymbols(std::string* text) {
// Note: code in this function is NOT async-signal safe (std::string uses
// malloc internally).
#if defined(__GLIBCXX__)
std::string::size_type search_from = 0;
while (search_from < text->size()) {
// Look for the start of a mangled symbol, from search_from.
std::string::size_type mangled_start =
text->find(kMangledSymbolPrefix, search_from);
if (mangled_start == std::string::npos) {
break; // Mangled symbol not found.
}
// Look for the end of the mangled symbol.
std::string::size_type mangled_end =
text->find_first_not_of(kSymbolCharacters, mangled_start);
if (mangled_end == std::string::npos) {
mangled_end = text->size();
}
std::string mangled_symbol =
text->substr(mangled_start, mangled_end - mangled_start);
// Try to demangle the mangled symbol candidate.
int status = 0;
scoped_ptr_malloc<char> demangled_symbol(
abi::__cxa_demangle(mangled_symbol.c_str(), NULL, 0, &status));
if (status == 0) { // Demangling is successful.
// Remove the mangled symbol.
text->erase(mangled_start, mangled_end - mangled_start);
// Insert the demangled symbol.
text->insert(mangled_start, demangled_symbol.get());
// Next time, we'll start right after the demangled symbol we inserted.
search_from = mangled_start + strlen(demangled_symbol.get());
} else {
// Failed to demangle. Retry after the "_Z" we just found.
search_from = mangled_start + 2;
}
}
#endif // defined(__GLIBCXX__)
}
#endif // !defined(USE_SYMBOLIZE)
class BacktraceOutputHandler {
public:
virtual void HandleOutput(const char* output) = 0;
protected:
virtual ~BacktraceOutputHandler() {}
};
void OutputPointer(void* pointer, BacktraceOutputHandler* handler) {
char buf[1024] = { '\0' };
handler->HandleOutput(" [0x");
internal::itoa_r(reinterpret_cast<intptr_t>(pointer),
buf, sizeof(buf), 16, 12);
handler->HandleOutput(buf);
handler->HandleOutput("]");
}
void ProcessBacktrace(void *const *trace,
int size,
BacktraceOutputHandler* handler) {
// NOTE: This code MUST be async-signal safe (it's used by in-process
// stack dumping signal handler). NO malloc or stdio is allowed here.
#if defined(USE_SYMBOLIZE)
for (int i = 0; i < size; ++i) {
OutputPointer(trace[i], handler);
handler->HandleOutput(" ");
char buf[1024] = { '\0' };
// Subtract by one as return address of function may be in the next
// function when a function is annotated as noreturn.
void* address = static_cast<char*>(trace[i]) - 1;
if (google::Symbolize(address, buf, sizeof(buf)))
handler->HandleOutput(buf);
else
handler->HandleOutput("<unknown>");
handler->HandleOutput("\n");
}
#else
bool printed = false;
// Below part is async-signal unsafe (uses malloc), so execute it only
// when we are not executing the signal handler.
if (in_signal_handler == 0) {
scoped_ptr_malloc<char*> trace_symbols(backtrace_symbols(trace, size));
if (trace_symbols.get()) {
for (int i = 0; i < size; ++i) {
std::string trace_symbol = trace_symbols.get()[i];
DemangleSymbols(&trace_symbol);
handler->HandleOutput(trace_symbol.c_str());
handler->HandleOutput("\n");
}
printed = true;
}
}
if (!printed) {
for (int i = 0; i < size; ++i) {
OutputPointer(trace[i], handler);
handler->HandleOutput("\n");
}
}
#endif // defined(USE_SYMBOLIZE)
}
void PrintToStderr(const char* output) {
// NOTE: This code MUST be async-signal safe (it's used by in-process
// stack dumping signal handler). NO malloc or stdio is allowed here.
ignore_result(HANDLE_EINTR(write(STDERR_FILENO, output, strlen(output))));
}
#if !defined(OS_IOS)
void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
// NOTE: This code MUST be async-signal safe.
// NO malloc or stdio is allowed here.
// Record the fact that we are in the signal handler now, so that the rest
// of StackTrace can behave in an async-signal-safe manner.
in_signal_handler = 1;
if (BeingDebugged())
BreakDebugger();
PrintToStderr("Received signal ");
char buf[1024] = { 0 };
internal::itoa_r(signal, buf, sizeof(buf), 10, 0);
PrintToStderr(buf);
if (signal == SIGBUS) {
if (info->si_code == BUS_ADRALN)
PrintToStderr(" BUS_ADRALN ");
else if (info->si_code == BUS_ADRERR)
PrintToStderr(" BUS_ADRERR ");
else if (info->si_code == BUS_OBJERR)
PrintToStderr(" BUS_OBJERR ");
else
PrintToStderr(" <unknown> ");
} else if (signal == SIGFPE) {
if (info->si_code == FPE_FLTDIV)
PrintToStderr(" FPE_FLTDIV ");
else if (info->si_code == FPE_FLTINV)
PrintToStderr(" FPE_FLTINV ");
else if (info->si_code == FPE_FLTOVF)
PrintToStderr(" FPE_FLTOVF ");
else if (info->si_code == FPE_FLTRES)
PrintToStderr(" FPE_FLTRES ");
else if (info->si_code == FPE_FLTSUB)
PrintToStderr(" FPE_FLTSUB ");
else if (info->si_code == FPE_FLTUND)
PrintToStderr(" FPE_FLTUND ");
else if (info->si_code == FPE_INTDIV)
PrintToStderr(" FPE_INTDIV ");
else if (info->si_code == FPE_INTOVF)
PrintToStderr(" FPE_INTOVF ");
else
PrintToStderr(" <unknown> ");
} else if (signal == SIGILL) {
if (info->si_code == ILL_BADSTK)
PrintToStderr(" ILL_BADSTK ");
else if (info->si_code == ILL_COPROC)
PrintToStderr(" ILL_COPROC ");
else if (info->si_code == ILL_ILLOPN)
PrintToStderr(" ILL_ILLOPN ");
else if (info->si_code == ILL_ILLADR)
PrintToStderr(" ILL_ILLADR ");
else if (info->si_code == ILL_ILLTRP)
PrintToStderr(" ILL_ILLTRP ");
else if (info->si_code == ILL_PRVOPC)
PrintToStderr(" ILL_PRVOPC ");
else if (info->si_code == ILL_PRVREG)
PrintToStderr(" ILL_PRVREG ");
else
PrintToStderr(" <unknown> ");
} else if (signal == SIGSEGV) {
if (info->si_code == SEGV_MAPERR)
PrintToStderr(" SEGV_MAPERR ");
else if (info->si_code == SEGV_ACCERR)
PrintToStderr(" SEGV_ACCERR ");
else
PrintToStderr(" <unknown> ");
}
if (signal == SIGBUS || signal == SIGFPE ||
signal == SIGILL || signal == SIGSEGV) {
internal::itoa_r(reinterpret_cast<intptr_t>(info->si_addr),
buf, sizeof(buf), 16, 12);
PrintToStderr(buf);
}
PrintToStderr("\n");
debug::StackTrace().Print();
#if defined(OS_LINUX)
#if ARCH_CPU_X86_FAMILY
ucontext_t* context = reinterpret_cast<ucontext_t*>(void_context);
const struct {
const char* label;
greg_t value;
} registers[] = {
#if ARCH_CPU_32_BITS
{ " gs: ", context->uc_mcontext.gregs[REG_GS] },
{ " fs: ", context->uc_mcontext.gregs[REG_FS] },
{ " es: ", context->uc_mcontext.gregs[REG_ES] },
{ " ds: ", context->uc_mcontext.gregs[REG_DS] },
{ " edi: ", context->uc_mcontext.gregs[REG_EDI] },
{ " esi: ", context->uc_mcontext.gregs[REG_ESI] },
{ " ebp: ", context->uc_mcontext.gregs[REG_EBP] },
{ " esp: ", context->uc_mcontext.gregs[REG_ESP] },
{ " ebx: ", context->uc_mcontext.gregs[REG_EBX] },
{ " edx: ", context->uc_mcontext.gregs[REG_EDX] },
{ " ecx: ", context->uc_mcontext.gregs[REG_ECX] },
{ " eax: ", context->uc_mcontext.gregs[REG_EAX] },
{ " trp: ", context->uc_mcontext.gregs[REG_TRAPNO] },
{ " err: ", context->uc_mcontext.gregs[REG_ERR] },
{ " ip: ", context->uc_mcontext.gregs[REG_EIP] },
{ " cs: ", context->uc_mcontext.gregs[REG_CS] },
{ " efl: ", context->uc_mcontext.gregs[REG_EFL] },
{ " usp: ", context->uc_mcontext.gregs[REG_UESP] },
{ " ss: ", context->uc_mcontext.gregs[REG_SS] },
#elif ARCH_CPU_64_BITS
{ " r8: ", context->uc_mcontext.gregs[REG_R8] },
{ " r9: ", context->uc_mcontext.gregs[REG_R9] },
{ " r10: ", context->uc_mcontext.gregs[REG_R10] },
{ " r11: ", context->uc_mcontext.gregs[REG_R11] },
{ " r12: ", context->uc_mcontext.gregs[REG_R12] },
{ " r13: ", context->uc_mcontext.gregs[REG_R13] },
{ " r14: ", context->uc_mcontext.gregs[REG_R14] },
{ " r15: ", context->uc_mcontext.gregs[REG_R15] },
{ " di: ", context->uc_mcontext.gregs[REG_RDI] },
{ " si: ", context->uc_mcontext.gregs[REG_RSI] },
{ " bp: ", context->uc_mcontext.gregs[REG_RBP] },
{ " bx: ", context->uc_mcontext.gregs[REG_RBX] },
{ " dx: ", context->uc_mcontext.gregs[REG_RDX] },
{ " ax: ", context->uc_mcontext.gregs[REG_RAX] },
{ " cx: ", context->uc_mcontext.gregs[REG_RCX] },
{ " sp: ", context->uc_mcontext.gregs[REG_RSP] },
{ " ip: ", context->uc_mcontext.gregs[REG_RIP] },
{ " efl: ", context->uc_mcontext.gregs[REG_EFL] },
{ " cgf: ", context->uc_mcontext.gregs[REG_CSGSFS] },
{ " erf: ", context->uc_mcontext.gregs[REG_ERR] },
{ " trp: ", context->uc_mcontext.gregs[REG_TRAPNO] },
{ " msk: ", context->uc_mcontext.gregs[REG_OLDMASK] },
{ " cr2: ", context->uc_mcontext.gregs[REG_CR2] },
#endif
};
#if ARCH_CPU_32_BITS
const int kRegisterPadding = 8;
#elif ARCH_CPU_64_BITS
const int kRegisterPadding = 16;
#endif
for (size_t i = 0; i < ARRAYSIZE_UNSAFE(registers); i++) {
PrintToStderr(registers[i].label);
internal::itoa_r(registers[i].value, buf, sizeof(buf),
16, kRegisterPadding);
PrintToStderr(buf);
if ((i + 1) % 4 == 0)
PrintToStderr("\n");
}
PrintToStderr("\n");
#endif
#elif defined(OS_MACOSX)
// TODO(shess): Port to 64-bit.
#if ARCH_CPU_X86_FAMILY && ARCH_CPU_32_BITS
ucontext_t* context = reinterpret_cast<ucontext_t*>(void_context);
size_t len;
// NOTE: Even |snprintf()| is not on the approved list for signal
// handlers, but buffered I/O is definitely not on the list due to
// potential for |malloc()|.
len = static_cast<size_t>(
snprintf(buf, sizeof(buf),
"ax: %x, bx: %x, cx: %x, dx: %x\n",
context->uc_mcontext->__ss.__eax,
context->uc_mcontext->__ss.__ebx,
context->uc_mcontext->__ss.__ecx,
context->uc_mcontext->__ss.__edx));
write(STDERR_FILENO, buf, std::min(len, sizeof(buf) - 1));
len = static_cast<size_t>(
snprintf(buf, sizeof(buf),
"di: %x, si: %x, bp: %x, sp: %x, ss: %x, flags: %x\n",
context->uc_mcontext->__ss.__edi,
context->uc_mcontext->__ss.__esi,
context->uc_mcontext->__ss.__ebp,
context->uc_mcontext->__ss.__esp,
context->uc_mcontext->__ss.__ss,
context->uc_mcontext->__ss.__eflags));
write(STDERR_FILENO, buf, std::min(len, sizeof(buf) - 1));
len = static_cast<size_t>(
snprintf(buf, sizeof(buf),
"ip: %x, cs: %x, ds: %x, es: %x, fs: %x, gs: %x\n",
context->uc_mcontext->__ss.__eip,
context->uc_mcontext->__ss.__cs,
context->uc_mcontext->__ss.__ds,
context->uc_mcontext->__ss.__es,
context->uc_mcontext->__ss.__fs,
context->uc_mcontext->__ss.__gs));
write(STDERR_FILENO, buf, std::min(len, sizeof(buf) - 1));
#endif // ARCH_CPU_32_BITS
#endif // defined(OS_MACOSX)
_exit(1);
}
#endif // !defined(OS_IOS)
class PrintBacktraceOutputHandler : public BacktraceOutputHandler {
public:
PrintBacktraceOutputHandler() {}
virtual void HandleOutput(const char* output) OVERRIDE {
// NOTE: This code MUST be async-signal safe (it's used by in-process
// stack dumping signal handler). NO malloc or stdio is allowed here.
PrintToStderr(output);
}
private:
DISALLOW_COPY_AND_ASSIGN(PrintBacktraceOutputHandler);
};
class StreamBacktraceOutputHandler : public BacktraceOutputHandler {
public:
explicit StreamBacktraceOutputHandler(std::ostream* os) : os_(os) {
}
virtual void HandleOutput(const char* output) OVERRIDE {
(*os_) << output;
}
private:
std::ostream* os_;
DISALLOW_COPY_AND_ASSIGN(StreamBacktraceOutputHandler);
};
#if !defined(OS_IOS)
void WarmUpBacktrace() {
// Warm up stack trace infrastructure. It turns out that on the first
// call glibc initializes some internal data structures using pthread_once,
// and even backtrace() can call malloc(), leading to hangs.
//
// Example stack trace snippet (with tcmalloc):
//
// #8 0x0000000000a173b5 in tc_malloc
// at ./third_party/tcmalloc/chromium/src/debugallocation.cc:1161
// #9 0x00007ffff7de7900 in _dl_map_object_deps at dl-deps.c:517
// #10 0x00007ffff7ded8a9 in dl_open_worker at dl-open.c:262
// #11 0x00007ffff7de9176 in _dl_catch_error at dl-error.c:178
// #12 0x00007ffff7ded31a in _dl_open (file=0x7ffff625e298 "libgcc_s.so.1")
// at dl-open.c:639
// #13 0x00007ffff6215602 in do_dlopen at dl-libc.c:89
// #14 0x00007ffff7de9176 in _dl_catch_error at dl-error.c:178
// #15 0x00007ffff62156c4 in dlerror_run at dl-libc.c:48
// #16 __GI___libc_dlopen_mode at dl-libc.c:165
// #17 0x00007ffff61ef8f5 in init
// at ../sysdeps/x86_64/../ia64/backtrace.c:53
// #18 0x00007ffff6aad400 in pthread_once
// at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_once.S:104
// #19 0x00007ffff61efa14 in __GI___backtrace
// at ../sysdeps/x86_64/../ia64/backtrace.c:104
// #20 0x0000000000752a54 in base::debug::StackTrace::StackTrace
// at base/debug/stack_trace_posix.cc:175
// #21 0x00000000007a4ae5 in
// base::(anonymous namespace)::StackDumpSignalHandler
// at base/process_util_posix.cc:172
// #22 <signal handler called>
StackTrace stack_trace;
}
#endif // !defined(OS_IOS)
} // namespace
#if !defined(OS_IOS)
bool EnableInProcessStackDumping() {
// When running in an application, our code typically expects SIGPIPE
// to be ignored. Therefore, when testing that same code, it should run
// with SIGPIPE ignored as well.
struct sigaction sigpipe_action;
memset(&sigpipe_action, 0, sizeof(sigpipe_action));
sigpipe_action.sa_handler = SIG_IGN;
sigemptyset(&sigpipe_action.sa_mask);
bool success = (sigaction(SIGPIPE, &sigpipe_action, NULL) == 0);
// Avoid hangs during backtrace initialization, see above.
WarmUpBacktrace();
struct sigaction action;
memset(&action, 0, sizeof(action));
action.sa_flags = SA_RESETHAND | SA_SIGINFO;
action.sa_sigaction = &StackDumpSignalHandler;
sigemptyset(&action.sa_mask);
success &= (sigaction(SIGILL, &action, NULL) == 0);
success &= (sigaction(SIGABRT, &action, NULL) == 0);
success &= (sigaction(SIGFPE, &action, NULL) == 0);
success &= (sigaction(SIGBUS, &action, NULL) == 0);
success &= (sigaction(SIGSEGV, &action, NULL) == 0);
success &= (sigaction(SIGSYS, &action, NULL) == 0);
return success;
}
#endif // !defined(OS_IOS)
StackTrace::StackTrace() {
// NOTE: This code MUST be async-signal safe (it's used by in-process
// stack dumping signal handler). NO malloc or stdio is allowed here.
// Though the backtrace API man page does not list any possible negative
// return values, we take no chance.
count_ = std::max(backtrace(trace_, arraysize(trace_)), 0);
}
void StackTrace::Print() const {
// NOTE: This code MUST be async-signal safe (it's used by in-process
// stack dumping signal handler). NO malloc or stdio is allowed here.
PrintBacktraceOutputHandler handler;
ProcessBacktrace(trace_, count_, &handler);
}
void StackTrace::OutputToStream(std::ostream* os) const {
StreamBacktraceOutputHandler handler(os);
ProcessBacktrace(trace_, count_, &handler);
}
namespace internal {
// NOTE: code from sandbox/linux/seccomp-bpf/demo.cc.
char *itoa_r(intptr_t i, char *buf, size_t sz, int base, size_t padding) {
// Make sure we can write at least one NUL byte.
size_t n = 1;
if (n > sz)
return NULL;
if (base < 2 || base > 16) {
buf[0] = '\000';
return NULL;
}
char *start = buf;
uintptr_t j = i;
// Handle negative numbers (only for base 10).
if (i < 0 && base == 10) {
j = -i;
// Make sure we can write the '-' character.
if (++n > sz) {
buf[0] = '\000';
return NULL;
}
*start++ = '-';
}
// Loop until we have converted the entire number. Output at least one
// character (i.e. '0').
char *ptr = start;
do {
// Make sure there is still enough space left in our output buffer.
if (++n > sz) {
buf[0] = '\000';
return NULL;
}
// Output the next digit.
*ptr++ = "0123456789abcdef"[j % base];
j /= base;
if (padding > 0)
padding--;
} while (j > 0 || padding > 0);
// Terminate the output with a NUL character.
*ptr = '\000';
// Conversion to ASCII actually resulted in the digits being in reverse
// order. We can't easily generate them in forward order, as we can't tell
// the number of characters needed until we are done converting.
// So, now, we reverse the string (except for the possible "-" sign).
while (--ptr > start) {
char ch = *ptr;
*ptr = *start;
*start++ = ch;
}
return buf;
}
} // namespace internal
} // namespace debug
} // namespace base