/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* API for getting a stack trace of the C/C++ stack on the current thread */

#include "mozilla/ArrayUtils.h"

#include "mozilla/Assertions.h"

#include "mozilla/IntegerPrintfMacros.h"

#include "mozilla/StackWalk.h"

#include <string.h>

using namespace mozilla;

// for _Unwind_Backtrace from libcxxrt or libunwind

// cxxabi.h from libcxxrt implicitly includes unwind.h first

#if defined(HAVE__UNWIND_BACKTRACE) && !defined(_GNU_SOURCE)

#define _GNU_SOURCE

#endif

#if defined(HAVE_DLOPEN) || defined(XP_DARWIN)

#include <dlfcn.h>

#endif

#if (defined(XP_DARWIN) && \

     (defined(__i386) || defined(__ppc__) || defined(HAVE__UNWIND_BACKTRACE)))

#define MOZ_STACKWALK_SUPPORTS_MACOSX 1

#else

#define MOZ_STACKWALK_SUPPORTS_MACOSX 0

#endif

#if (defined(linux) && \

     ((defined(__GNUC__) && (defined(__i386) || defined(PPC))) || \

      defined(HAVE__UNWIND_BACKTRACE)))

#define MOZ_STACKWALK_SUPPORTS_LINUX 1

#else

#define MOZ_STACKWALK_SUPPORTS_LINUX 0

#endif

#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 1)

#define HAVE___LIBC_STACK_END 1

#else

#define HAVE___LIBC_STACK_END 0

#endif

#if HAVE___LIBC_STACK_END

extern MOZ_EXPORT void* __libc_stack_end; // from ld-linux.so

#endif

#ifdef ANDROID

#include <algorithm>

#include <unistd.h>

#include <pthread.h>

#endif

#if MOZ_STACKWALK_SUPPORTS_WINDOWS

#include <windows.h>

#include <process.h>

#include <stdio.h>

#include <malloc.h>

#include "mozilla/ArrayUtils.h"

#include "mozilla/Atomics.h"

#include "mozilla/StackWalk_windows.h"

#include "mozilla/WindowsVersion.h"

#include <imagehlp.h>

// We need a way to know if we are building for WXP (or later), as if we are, we

// need to use the newer 64-bit APIs. API_VERSION_NUMBER seems to fit the bill.

// A value of 9 indicates we want to use the new APIs.

#if API_VERSION_NUMBER < 9

#error Too old imagehlp.h

#endif

struct WalkStackData

{

  // Are we walking the stack of the calling thread? Note that we need to avoid

  // calling fprintf and friends if this is false, in order to avoid deadlocks.

  bool walkCallingThread;

  uint32_t skipFrames;

  HANDLE thread;

  HANDLE process;

  HANDLE eventStart;

  HANDLE eventEnd;

  void** pcs;

  uint32_t pc_size;

  uint32_t pc_count;

  uint32_t pc_max;

  void** sps;

  uint32_t sp_size;

  uint32_t sp_count;

  CONTEXT* context;

};

CRITICAL_SECTION gDbgHelpCS;

#ifdef _M_AMD64

// Because various Win64 APIs acquire function-table locks, we need a way of

// preventing stack walking while those APIs are being called. Otherwise, the

// stack walker may suspend a thread holding such a lock, and deadlock when the

// stack unwind code attempts to wait for that lock.

//

// We're using an atomic counter rather than a critical section because we

// don't require mutual exclusion with the stack walker. If the stack walker

// determines that it's safe to start unwinding the suspended thread (i.e.

// there are no suppressions when the unwind begins), then it's safe to

// continue unwinding that thread even if other threads request suppressions

// in the meantime, because we can't deadlock with those other threads.

//

// XXX: This global variable is a larger-than-necessary hammer. A more scoped

// solution would be to maintain a counter per thread, but then it would be

// more difficult for WalkStackMain64 to read the suspended thread's counter.

static Atomic<size_t> sStackWalkSuppressions;

MFBT_API

AutoSuppressStackWalking::AutoSuppressStackWalking()

{

  ++sStackWalkSuppressions;

}

MFBT_API

AutoSuppressStackWalking::~AutoSuppressStackWalking()

{

  --sStackWalkSuppressions;

}

static uint8_t* sJitCodeRegionStart;

static size_t sJitCodeRegionSize;

uint8_t* sMsMpegJitCodeRegionStart;

size_t sMsMpegJitCodeRegionSize;

MFBT_API void

RegisterJitCodeRegion(uint8_t* aStart, size_t aSize)

{

  // Currently we can only handle one JIT code region at a time

  MOZ_RELEASE_ASSERT(!sJitCodeRegionStart);

  sJitCodeRegionStart = aStart;

  sJitCodeRegionSize = aSize;

}

MFBT_API void

UnregisterJitCodeRegion(uint8_t* aStart, size_t aSize)

{

  // Currently we can only handle one JIT code region at a time

  MOZ_RELEASE_ASSERT(sJitCodeRegionStart &&

                     sJitCodeRegionStart == aStart &&

                     sJitCodeRegionSize == aSize);

  sJitCodeRegionStart = nullptr;

  sJitCodeRegionSize = 0;

}

#endif // _M_AMD64

// Routine to print an error message to standard error.

static void

PrintError(const char* aPrefix)

{

  LPSTR lpMsgBuf;

  DWORD lastErr = GetLastError();

  FormatMessageA(

    FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,

    nullptr,

    lastErr,

    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language

    (LPSTR)&lpMsgBuf,

    0,

    nullptr

  );

  fprintf(stderr, "### ERROR: %s: %s",

          aPrefix, lpMsgBuf ? lpMsgBuf : "(null)\n");

  fflush(stderr);

  LocalFree(lpMsgBuf);

}

static void

InitializeDbgHelpCriticalSection()

{

  static bool initialized = false;

  if (initialized) {

    return;

  }

  ::InitializeCriticalSection(&gDbgHelpCS);

  initialized = true;

}

static void

WalkStackMain64(struct WalkStackData* aData)

{

  // Get a context for the specified thread.

  CONTEXT context_buf;

  CONTEXT* context;

  if (!aData->context) {

    context = &context_buf;

    memset(context, 0, sizeof(CONTEXT));

    context->ContextFlags = CONTEXT_FULL;

    if (aData->walkCallingThread) {

      ::RtlCaptureContext(context);

    } else if (!GetThreadContext(aData->thread, context)) {

      return;

    }

  } else {

    context = aData->context;

  }

#if defined(_M_IX86) || defined(_M_IA64) || defined(_M_ARM64)

  // Setup initial stack frame to walk from.

  STACKFRAME64 frame64;

  memset(&frame64, 0, sizeof(frame64));

#ifdef _M_IX86

  frame64.AddrPC.Offset    = context->Eip;

  frame64.AddrStack.Offset = context->Esp;

  frame64.AddrFrame.Offset = context->Ebp;

#elif defined _M_IA64

  frame64.AddrPC.Offset    = context->StIIP;

  frame64.AddrStack.Offset = context->SP;

  frame64.AddrFrame.Offset = context->RsBSP;

#elif defined _M_ARM64

  frame64.AddrPC.Offset    = context->Pc;

  frame64.AddrStack.Offset = context->Sp;

  frame64.AddrFrame.Offset = context->Fp;

#endif

  frame64.AddrPC.Mode      = AddrModeFlat;

  frame64.AddrStack.Mode   = AddrModeFlat;

  frame64.AddrFrame.Mode   = AddrModeFlat;

  frame64.AddrReturn.Mode  = AddrModeFlat;

#endif

#ifdef _M_AMD64

  // If there are any active suppressions, then at least one thread (we don't

  // know which) is holding a lock that can deadlock RtlVirtualUnwind. Since

  // that thread may be the one that we're trying to unwind, we can't proceed.

  //

  // But if there are no suppressions, then our target thread can't be holding

  // a lock, and it's safe to proceed. By virtue of being suspended, the target

  // thread can't acquire any new locks during the unwind process, so we only

  // need to do this check once. After that, sStackWalkSuppressions can be

  // changed by other threads while we're unwinding, and that's fine because

  // we can't deadlock with those threads.

  if (sStackWalkSuppressions) {

    return;

  }

#endif

#ifdef _M_AMD64

  bool firstFrame = true;

#endif

  // Skip our own stack walking frames.

  int skip = (aData->walkCallingThread ? 3 : 0) + aData->skipFrames;

  // Now walk the stack.

  while (true) {

    DWORD64 addr;

    DWORD64 spaddr;

#if defined(_M_IX86) || defined(_M_IA64) || defined(_M_ARM64)

    // 32-bit frame unwinding.

    // Debug routines are not threadsafe, so grab the lock.

    EnterCriticalSection(&gDbgHelpCS);

    BOOL ok = StackWalk64(

#if defined _M_IA64

      IMAGE_FILE_MACHINE_IA64,

#elif defined _M_IX86

      IMAGE_FILE_MACHINE_I386,

#elif defined _M_ARM64

      IMAGE_FILE_MACHINE_ARM64,

#endif

      aData->process,

      aData->thread,

      &frame64,

      context,

      nullptr,

      SymFunctionTableAccess64, // function table access routine

      SymGetModuleBase64,       // module base routine

      0

    );

    LeaveCriticalSection(&gDbgHelpCS);

    if (ok) {

      addr = frame64.AddrPC.Offset;

      spaddr = frame64.AddrStack.Offset;

    } else {

      addr = 0;

      spaddr = 0;

      if (aData->walkCallingThread) {

        PrintError("WalkStack64");

      }

    }

    if (!ok) {

      break;

    }

#elif defined(_M_AMD64)

    // If we reach a frame in JIT code, we don't have enough information to

    // unwind, so we have to give up.

    if (sJitCodeRegionStart &&

        (uint8_t*)context->Rip >= sJitCodeRegionStart &&

        (uint8_t*)context->Rip < sJitCodeRegionStart + sJitCodeRegionSize) {

      break;

    }

    // We must also avoid msmpeg2vdec.dll's JIT region: they don't generate

    // unwind data, so their JIT unwind callback just throws up its hands and

    // terminates the process.

    if (sMsMpegJitCodeRegionStart &&

        (uint8_t*)context->Rip >= sMsMpegJitCodeRegionStart &&

        (uint8_t*)context->Rip < sMsMpegJitCodeRegionStart + sMsMpegJitCodeRegionSize) {

      break;

    }

    // 64-bit frame unwinding.

    // Try to look up unwind metadata for the current function.

    ULONG64 imageBase;

    PRUNTIME_FUNCTION runtimeFunction =

      RtlLookupFunctionEntry(context->Rip, &imageBase, NULL);

    if (runtimeFunction) {

      PVOID dummyHandlerData;

      ULONG64 dummyEstablisherFrame;

      RtlVirtualUnwind(UNW_FLAG_NHANDLER,

                       imageBase,

                       context->Rip,

                       runtimeFunction,

                       context,

                       &dummyHandlerData,

                       &dummyEstablisherFrame,

                       nullptr);

    } else if (firstFrame) {

      // Leaf functions can be unwound by hand.

      context->Rip = *reinterpret_cast<DWORD64*>(context->Rsp);

      context->Rsp += sizeof(void*);

    } else {

      // Something went wrong.

      break;

    }

    addr = context->Rip;

    spaddr = context->Rsp;

    firstFrame = false;

#else

#error "unknown platform"

#endif

    if (addr == 0) {

      break;

    }

    if (skip-- > 0) {

      continue;

    }

    if (aData->pc_count < aData->pc_size) {

      aData->pcs[aData->pc_count] = (void*)addr;

    }

    ++aData->pc_count;

    if (aData->sp_count < aData->sp_size) {

      aData->sps[aData->sp_count] = (void*)spaddr;

    }

    ++aData->sp_count;

    if (aData->pc_max != 0 && aData->pc_count == aData->pc_max) {

      break;

    }

#if defined(_M_IX86) || defined(_M_IA64)

    if (frame64.AddrReturn.Offset == 0) {

      break;

    }

#endif

  }

}

/**

 * Walk the stack, translating PC's found into strings and recording the

 * chain in aBuffer. For this to work properly, the DLLs must be rebased

 * so that the address in the file agrees with the address in memory.

 * Otherwise StackWalk will return FALSE when it hits a frame in a DLL

 * whose in memory address doesn't match its in-file address.

 */

MFBT_API void

MozStackWalkThread(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

                   uint32_t aMaxFrames, void* aClosure,

                   HANDLE aThread, CONTEXT* aContext)

{

  static HANDLE myProcess = nullptr;

  HANDLE myThread;

  struct WalkStackData data;

  InitializeDbgHelpCriticalSection();

  HANDLE targetThread = aThread;

  if (!aThread) {

    targetThread = ::GetCurrentThread();

    data.walkCallingThread = true;

  } else {

    DWORD threadId = ::GetThreadId(aThread);

    DWORD currentThreadId = ::GetCurrentThreadId();

    data.walkCallingThread = (threadId == currentThreadId);

  }

  // Have to duplicate handle to get a real handle.

  if (!myProcess) {

    if (!::DuplicateHandle(::GetCurrentProcess(),

                           ::GetCurrentProcess(),

                           ::GetCurrentProcess(),

                           &myProcess,

                           PROCESS_ALL_ACCESS, FALSE, 0)) {

      if (data.walkCallingThread) {

        PrintError("DuplicateHandle (process)");

      }

      return;

    }

  }

  if (!::DuplicateHandle(::GetCurrentProcess(),

                         targetThread,

                         ::GetCurrentProcess(),

                         &myThread,

                         THREAD_ALL_ACCESS, FALSE, 0)) {

    if (data.walkCallingThread) {

      PrintError("DuplicateHandle (thread)");

    }

    return;

  }

  data.skipFrames = aSkipFrames;

  data.thread = myThread;

  data.process = myProcess;

  void* local_pcs[1024];

  data.pcs = local_pcs;

  data.pc_count = 0;

  data.pc_size = ArrayLength(local_pcs);

  data.pc_max = aMaxFrames;

  void* local_sps[1024];

  data.sps = local_sps;

  data.sp_count = 0;

  data.sp_size = ArrayLength(local_sps);

  data.context = aContext;

  WalkStackMain64(&data);

  if (data.pc_count > data.pc_size) {

    data.pcs = (void**)_alloca(data.pc_count * sizeof(void*));

    data.pc_size = data.pc_count;

    data.pc_count = 0;

    data.sps = (void**)_alloca(data.sp_count * sizeof(void*));

    data.sp_size = data.sp_count;

    data.sp_count = 0;

    WalkStackMain64(&data);

  }

  ::CloseHandle(myThread);

  for (uint32_t i = 0; i < data.pc_count; ++i) {

    (*aCallback)(i + 1, data.pcs[i], data.sps[i], aClosure);

  }

}

MFBT_API void

MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

             uint32_t aMaxFrames, void* aClosure)

{

  MozStackWalkThread(aCallback, aSkipFrames, aMaxFrames, aClosure,

                     nullptr, nullptr);

}

static BOOL CALLBACK

callbackEspecial64(

  PCSTR aModuleName,

  DWORD64 aModuleBase,

  ULONG aModuleSize,

  PVOID aUserContext)

{

  BOOL retval = TRUE;

  DWORD64 addr = *(DWORD64*)aUserContext;

  /*

   * You'll want to control this if we are running on an

   *  architecture where the addresses go the other direction.

   * Not sure this is even a realistic consideration.

   */

  const BOOL addressIncreases = TRUE;

  /*

   * If it falls in side the known range, load the symbols.

   */

  if (addressIncreases

      ? (addr >= aModuleBase && addr <= (aModuleBase + aModuleSize))

      : (addr <= aModuleBase && addr >= (aModuleBase - aModuleSize))

     ) {

    retval = !!SymLoadModule64(GetCurrentProcess(), nullptr,

                               (PSTR)aModuleName, nullptr,

                               aModuleBase, aModuleSize);

    if (!retval) {

      PrintError("SymLoadModule64");

    }

  }

  return retval;

}

/*

 * SymGetModuleInfoEspecial

 *

 * Attempt to determine the module information.

 * Bug 112196 says this DLL may not have been loaded at the time

 *  SymInitialize was called, and thus the module information

 *  and symbol information is not available.

 * This code rectifies that problem.

 */

// New members were added to IMAGEHLP_MODULE64 (that show up in the

// Platform SDK that ships with VC8, but not the Platform SDK that ships

// with VC7.1, i.e., between DbgHelp 6.0 and 6.1), but we don't need to

// use them, and it's useful to be able to function correctly with the

// older library.  (Stock Windows XP SP2 seems to ship with dbghelp.dll

// version 5.1.)  Since Platform SDK version need not correspond to

// compiler version, and the version number in debughlp.h was NOT bumped

// when these changes were made, ifdef based on a constant that was

// added between these versions.

#ifdef SSRVOPT_SETCONTEXT

#define NS_IMAGEHLP_MODULE64_SIZE (((offsetof(IMAGEHLP_MODULE64, LoadedPdbName) + sizeof(DWORD64) - 1) / sizeof(DWORD64)) * sizeof(DWORD64))

#else

#define NS_IMAGEHLP_MODULE64_SIZE sizeof(IMAGEHLP_MODULE64)

#endif

BOOL SymGetModuleInfoEspecial64(HANDLE aProcess, DWORD64 aAddr,

                                PIMAGEHLP_MODULE64 aModuleInfo,

                                PIMAGEHLP_LINE64 aLineInfo)

{

  BOOL retval = FALSE;

  /*

   * Init the vars if we have em.

   */

  aModuleInfo->SizeOfStruct = NS_IMAGEHLP_MODULE64_SIZE;

  if (aLineInfo) {

    aLineInfo->SizeOfStruct = sizeof(IMAGEHLP_LINE64);

  }

  /*

   * Give it a go.

   * It may already be loaded.

   */

  retval = SymGetModuleInfo64(aProcess, aAddr, aModuleInfo);

  if (retval == FALSE) {

    /*

     * Not loaded, here's the magic.

     * Go through all the modules.

     */

    // Need to cast to PENUMLOADED_MODULES_CALLBACK64 because the

    // constness of the first parameter of

    // PENUMLOADED_MODULES_CALLBACK64 varies over SDK versions (from

    // non-const to const over time).  See bug 391848 and bug

    // 415426.

    BOOL enumRes = EnumerateLoadedModules64(

      aProcess,

      (PENUMLOADED_MODULES_CALLBACK64)callbackEspecial64,

      (PVOID)&aAddr);

    if (enumRes != FALSE) {

      /*

       * One final go.

       * If it fails, then well, we have other problems.

       */

      retval = SymGetModuleInfo64(aProcess, aAddr, aModuleInfo);

    }

  }

  /*

   * If we got module info, we may attempt line info as well.

   * We will not report failure if this does not work.

   */

  if (retval != FALSE && aLineInfo) {

    DWORD displacement = 0;

    BOOL lineRes = FALSE;

    lineRes = SymGetLineFromAddr64(aProcess, aAddr, &displacement, aLineInfo);

    if (!lineRes) {

      // Clear out aLineInfo to indicate that it's not valid

      memset(aLineInfo, 0, sizeof(*aLineInfo));

    }

  }

  return retval;

}

static bool

EnsureSymInitialized()

{

  static bool gInitialized = false;

  bool retStat;

  if (gInitialized) {

    return gInitialized;

  }

  InitializeDbgHelpCriticalSection();

  SymSetOptions(SYMOPT_LOAD_LINES | SYMOPT_UNDNAME);

  retStat = SymInitialize(GetCurrentProcess(), nullptr, TRUE);

  if (!retStat) {

    PrintError("SymInitialize");

  }

  gInitialized = retStat;

  /* XXX At some point we need to arrange to call SymCleanup */

  return retStat;

}

MFBT_API bool

MozDescribeCodeAddress(void* aPC, MozCodeAddressDetails* aDetails)

{

  aDetails->library[0] = '\0';

  aDetails->loffset = 0;

  aDetails->filename[0] = '\0';

  aDetails->lineno = 0;

  aDetails->function[0] = '\0';

  aDetails->foffset = 0;

  if (!EnsureSymInitialized()) {

    return false;

  }

  HANDLE myProcess = ::GetCurrentProcess();

  BOOL ok;

  // debug routines are not threadsafe, so grab the lock.

  EnterCriticalSection(&gDbgHelpCS);

  //

  // Attempt to load module info before we attempt to resolve the symbol.

  // This just makes sure we get good info if available.

  //

  DWORD64 addr = (DWORD64)aPC;

  IMAGEHLP_MODULE64 modInfo;

  IMAGEHLP_LINE64 lineInfo;

  BOOL modInfoRes;

  modInfoRes = SymGetModuleInfoEspecial64(myProcess, addr, &modInfo, &lineInfo);

  if (modInfoRes) {

    strncpy(aDetails->library, modInfo.LoadedImageName,

                sizeof(aDetails->library));

    aDetails->library[mozilla::ArrayLength(aDetails->library) - 1] = '\0';

    aDetails->loffset = (char*)aPC - (char*)modInfo.BaseOfImage;

    if (lineInfo.FileName) {

      strncpy(aDetails->filename, lineInfo.FileName,

                  sizeof(aDetails->filename));

      aDetails->filename[mozilla::ArrayLength(aDetails->filename) - 1] = '\0';

      aDetails->lineno = lineInfo.LineNumber;

    }

  }

  ULONG64 buffer[(sizeof(SYMBOL_INFO) +

    MAX_SYM_NAME * sizeof(TCHAR) + sizeof(ULONG64) - 1) / sizeof(ULONG64)];

  PSYMBOL_INFO pSymbol = (PSYMBOL_INFO)buffer;

  pSymbol->SizeOfStruct = sizeof(SYMBOL_INFO);

  pSymbol->MaxNameLen = MAX_SYM_NAME;

  DWORD64 displacement;

  ok = SymFromAddr(myProcess, addr, &displacement, pSymbol);

  if (ok) {

    strncpy(aDetails->function, pSymbol->Name,

                sizeof(aDetails->function));

    aDetails->function[mozilla::ArrayLength(aDetails->function) - 1] = '\0';

    aDetails->foffset = static_cast<ptrdiff_t>(displacement);

  }

  LeaveCriticalSection(&gDbgHelpCS); // release our lock

  return true;

}

// i386 or PPC Linux stackwalking code

#elif HAVE_DLADDR && (HAVE__UNWIND_BACKTRACE || MOZ_STACKWALK_SUPPORTS_LINUX || MOZ_STACKWALK_SUPPORTS_MACOSX)

#include <stdlib.h>

#include <string.h>

#include <stdio.h>

// On glibc 2.1, the Dl_info api defined in <dlfcn.h> is only exposed

// if __USE_GNU is defined.  I suppose its some kind of standards

// adherence thing.

//

#if (__GLIBC_MINOR__ >= 1) && !defined(__USE_GNU)

#define __USE_GNU

#endif

// This thing is exported by libstdc++

// Yes, this is a gcc only hack

#if defined(MOZ_DEMANGLE_SYMBOLS)

#include <cxxabi.h>

#endif // MOZ_DEMANGLE_SYMBOLS

void DemangleSymbol(const char* aSymbol,

                    char* aBuffer,

                    int aBufLen)

{

  aBuffer[0] = '\0';

#if defined(MOZ_DEMANGLE_SYMBOLS)

  /* See demangle.h in the gcc source for the voodoo */

  char* demangled = abi::__cxa_demangle(aSymbol, 0, 0, 0);

  if (demangled) {

    strncpy(aBuffer, demangled, aBufLen);

    aBuffer[aBufLen - 1] = '\0';

    free(demangled);

  }

#endif // MOZ_DEMANGLE_SYMBOLS

}

// {x86, ppc} x {Linux, Mac} stackwalking code.

#if ((defined(__i386) || defined(PPC) || defined(__ppc__)) && \

     (MOZ_STACKWALK_SUPPORTS_MACOSX || MOZ_STACKWALK_SUPPORTS_LINUX))

MFBT_API void

MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

             uint32_t aMaxFrames, void* aClosure)

{

  // Get the frame pointer

  void** bp = (void**)__builtin_frame_address(0);

  void* stackEnd;

#if HAVE___LIBC_STACK_END

  stackEnd = __libc_stack_end;

#elif defined(XP_DARWIN)

  stackEnd = pthread_get_stackaddr_np(pthread_self());

#elif defined(ANDROID)

  pthread_attr_t sattr;

  pthread_attr_init(&sattr);

  pthread_getattr_np(pthread_self(), &sattr);

  void* stackBase = stackEnd = nullptr;

  size_t stackSize = 0;

  if (gettid() != getpid()) {

    // bionic's pthread_attr_getstack doesn't tell the truth for the main

    // thread (see bug 846670). So don't use it for the main thread.

    if (!pthread_attr_getstack(&sattr, &stackBase, &stackSize)) {

      stackEnd = static_cast<char*>(stackBase) + stackSize;

    } else {

      stackEnd = nullptr;

    }

  }

  if (!stackEnd) {

    // So consider the current frame pointer + an arbitrary size of 8MB

    // (modulo overflow ; not really arbitrary as it's the default stack

    // size for the main thread) if pthread_attr_getstack failed for

    // some reason (or was skipped).

    static const uintptr_t kMaxStackSize = 8 * 1024 * 1024;

    uintptr_t maxStackStart = uintptr_t(-1) - kMaxStackSize;

    uintptr_t stackStart = std::max(maxStackStart, uintptr_t(bp));

    stackEnd = reinterpret_cast<void*>(stackStart + kMaxStackSize);

  }

#else

#  error Unsupported configuration

#endif

  FramePointerStackWalk(aCallback, aSkipFrames, aMaxFrames, aClosure, bp,

                        stackEnd);

}

#elif defined(HAVE__UNWIND_BACKTRACE)

// libgcc_s.so symbols _Unwind_Backtrace@@GCC_3.3 and _Unwind_GetIP@@GCC_3.0

#include <unwind.h>

struct unwind_info

{

  MozWalkStackCallback callback;

  int skip;

  int maxFrames;

  int numFrames;

  void* closure;

};

static _Unwind_Reason_Code

unwind_callback(struct _Unwind_Context* context, void* closure)

{

  unwind_info* info = static_cast<unwind_info*>(closure);

  void* pc = reinterpret_cast<void*>(_Unwind_GetIP(context));

  // TODO Use something like '_Unwind_GetGR()' to get the stack pointer.

  if (--info->skip < 0) {

    info->numFrames++;

    (*info->callback)(info->numFrames, pc, nullptr, info->closure);

    if (info->maxFrames != 0 && info->numFrames == info->maxFrames) {

      // Again, any error code that stops the walk will do.

      return _URC_FOREIGN_EXCEPTION_CAUGHT;

    }

  }

  return _URC_NO_REASON;

}

MFBT_API void

MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

             uint32_t aMaxFrames, void* aClosure)

{

  unwind_info info;

  info.callback = aCallback;

  info.skip = aSkipFrames + 1;

  info.maxFrames = aMaxFrames;

  info.numFrames = 0;

  info.closure = aClosure;

  // We ignore the return value from _Unwind_Backtrace. There are three main

  // reasons for this.

  // - On ARM/Android bionic's _Unwind_Backtrace usually (always?) returns

  //   _URC_FAILURE.  See

  //   https://bugzilla.mozilla.org/show_bug.cgi?id=717853#c110.

  // - If aMaxFrames != 0, we want to stop early, and the only way to do that

  //   is to make unwind_callback return something other than _URC_NO_REASON,

  //   which causes _Unwind_Backtrace to return a non-success code.

  // - MozStackWalk doesn't have a return value anyway.

  (void)_Unwind_Backtrace(unwind_callback, &info);

}

#endif

bool MFBT_API

MozDescribeCodeAddress(void* aPC, MozCodeAddressDetails* aDetails)

{

  aDetails->library[0] = '\0';

  aDetails->loffset = 0;

  aDetails->filename[0] = '\0';

  aDetails->lineno = 0;

  aDetails->function[0] = '\0';

  aDetails->foffset = 0;

  Dl_info info;

  int ok = dladdr(aPC, &info);

  if (!ok) {

    return true;

  }

  strncpy(aDetails->library, info.dli_fname, sizeof(aDetails->library));

  aDetails->library[mozilla::ArrayLength(aDetails->library) - 1] = '\0';

  aDetails->loffset = (char*)aPC - (char*)info.dli_fbase;

  const char* symbol = info.dli_sname;

  if (!symbol || symbol[0] == '\0') {

    return true;

  }

  DemangleSymbol(symbol, aDetails->function, sizeof(aDetails->function));

  if (aDetails->function[0] == '\0') {

    // Just use the mangled symbol if demangling failed.

    strncpy(aDetails->function, symbol, sizeof(aDetails->function));

    aDetails->function[mozilla::ArrayLength(aDetails->function) - 1] = '\0';

  }

  aDetails->foffset = (char*)aPC - (char*)info.dli_saddr;

  return true;

}

#else // unsupported platform.

MFBT_API void

MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

             uint32_t aMaxFrames, void* aClosure)

{

}

MFBT_API bool

MozDescribeCodeAddress(void* aPC, MozCodeAddressDetails* aDetails)

{

  aDetails->library[0] = '\0';

  aDetails->loffset = 0;

  aDetails->filename[0] = '\0';

  aDetails->lineno = 0;

  aDetails->function[0] = '\0';

  aDetails->foffset = 0;

  return false;

}

#endif

#if defined(XP_WIN) || defined (XP_MACOSX) || defined (XP_LINUX)

namespace mozilla {

void

FramePointerStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

                      uint32_t aMaxFrames, void* aClosure, void** aBp,

                      void* aStackEnd)

{

  // Stack walking code courtesy Kipp's "leaky".

  int32_t skip = aSkipFrames;

  uint32_t numFrames = 0;

  while (aBp) {

    void** next = (void**)*aBp;

    // aBp may not be a frame pointer on i386 if code was compiled with

    // -fomit-frame-pointer, so do some sanity checks.

    // (aBp should be a frame pointer on ppc(64) but checking anyway may help

    // a little if the stack has been corrupted.)

    // We don't need to check against the begining of the stack because

    // we can assume that aBp > sp

    if (next <= aBp ||

        next > aStackEnd ||

        (uintptr_t(next) & 3)) {

      break;

    }

#if (defined(__ppc__) && defined(XP_MACOSX)) || defined(__powerpc64__)

    // ppc mac or powerpc64 linux

    void* pc = *(aBp + 2);

    aBp += 3;

#else // i386 or powerpc32 linux

    void* pc = *(aBp + 1);

    aBp += 2;

#endif

    if (--skip < 0) {

      // Assume that the SP points to the BP of the function

      // it called. We can't know the exact location of the SP

      // but this should be sufficient for our use the SP

      // to order elements on the stack.

      numFrames++;

      (*aCallback)(numFrames, pc, aBp, aClosure);

      if (aMaxFrames != 0 && numFrames == aMaxFrames) {

        break;

      }

    }

    aBp = next;

  }

}

} // namespace mozilla

#else

namespace mozilla {

MFBT_API void

FramePointerStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,

                      uint32_t aMaxFrames, void* aClosure, void** aBp,

                      void* aStackEnd)

{

}

}

#endif

MFBT_API void

MozFormatCodeAddressDetails(char* aBuffer, uint32_t aBufferSize,

                            uint32_t aFrameNumber, void* aPC,

                            const MozCodeAddressDetails* aDetails)

{

  MozFormatCodeAddress(aBuffer, aBufferSize,

                       aFrameNumber, aPC, aDetails->function,

                       aDetails->library, aDetails->loffset,

                       aDetails->filename, aDetails->lineno);

}

MFBT_API void

MozFormatCodeAddress(char* aBuffer, uint32_t aBufferSize, uint32_t aFrameNumber,

                     const void* aPC, const char* aFunction,

                     const char* aLibrary, ptrdiff_t aLOffset,

                     const char* aFileName, uint32_t aLineNo)

{

  const char* function = aFunction && aFunction[0] ? aFunction : "???";

  if (aFileName && aFileName[0]) {

    // We have a filename and (presumably) a line number. Use them.

    snprintf(aBuffer, aBufferSize,

             "#%02u: %s (%s:%u)",

             aFrameNumber, function, aFileName, aLineNo);

  } else if (aLibrary && aLibrary[0]) {

    // We have no filename, but we do have a library name. Use it and the

    // library offset, and print them in a way that scripts like

    // fix_{linux,macosx}_stacks.py can easily post-process.

    snprintf(aBuffer, aBufferSize,

             "#%02u: %s[%s +0x%" PRIxPTR "]",

             aFrameNumber, function, aLibrary, static_cast<uintptr_t>(aLOffset));

  } else {

    // We have nothing useful to go on. (The format string is split because

    // '??)' is a trigraph and causes a warning, sigh.)

    snprintf(aBuffer, aBufferSize,

             "#%02u: ??? (???:???" ")",

             aFrameNumber);

  }

}