The Tor Browser: xpcom/base/nsStackWalk.cpp@6474c204b198 (annotated)

xpcom/base/nsStackWalk.cpp@6474c204b198 (annotated)

xpcom/base/nsStackWalk.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set shiftwidth=4 tabstop=8 autoindent cindent expandtab: */
 /* 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/Assertions.h"
 #include "mozilla/IntegerPrintfMacros.h"
 #include "mozilla/StackWalk.h"
 #include "nsStackWalkPrivate.h"
 #include "nsStackWalk.h"
 using namespace mozilla;
 // The presence of this address is the stack must stop the stack walk. If
 // there is no such address, the structure will be {nullptr, true}.
 struct CriticalAddress {
   void* mAddr;
   bool mInit;
 };
 static CriticalAddress gCriticalAddress;
 // 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_MACOSX)
 #include <dlfcn.h>
 #endif
 #define NSSTACKWALK_SUPPORTS_MACOSX \
     (defined(XP_MACOSX) && \
      (defined(__i386) || defined(__ppc__) || defined(HAVE__UNWIND_BACKTRACE)))
 #define NSSTACKWALK_SUPPORTS_LINUX \
     (defined(linux) && \
      ((defined(__GNUC__) && (defined(__i386) || defined(PPC))) || \
       defined(HAVE__UNWIND_BACKTRACE)))
 #define NSSTACKWALK_SUPPORTS_SOLARIS \
     (defined(__sun) && \
      (defined(__sparc) || defined(sparc) || defined(__i386) || defined(i386)))
 #if NSSTACKWALK_SUPPORTS_MACOSX
 #include <pthread.h>
 #include <CoreServices/CoreServices.h>
 typedef void
 malloc_logger_t(uint32_t type, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3,
                 uintptr_t result, uint32_t num_hot_frames_to_skip);
 extern malloc_logger_t *malloc_logger;
 static void
 stack_callback(void *pc, void *sp, void *closure)
 {
   const char *name = reinterpret_cast<char *>(closure);
   Dl_info info;
   // On Leopard dladdr returns the wrong value for "new_sem_from_pool". The
   // stack shows up as having two pthread_cond_wait$UNIX2003 frames. The
   // correct one is the first that we find on our way up, so the
   // following check for gCriticalAddress.mAddr is critical.
   if (gCriticalAddress.mAddr || dladdr(pc, &info) == 0  ||
       info.dli_sname == nullptr || strcmp(info.dli_sname, name) != 0)
     return;
   gCriticalAddress.mAddr = pc;
 }
 #ifdef DEBUG
 #define MAC_OS_X_VERSION_10_7_HEX 0x00001070
 static int32_t OSXVersion()
 {
   static int32_t gOSXVersion = 0x0;
   if (gOSXVersion == 0x0) {
     OSErr err = ::Gestalt(gestaltSystemVersion, (SInt32*)&gOSXVersion);
     MOZ_ASSERT(err == noErr);
   }
   return gOSXVersion;
 }
 static bool OnLionOrLater()
 {
   return (OSXVersion() >= MAC_OS_X_VERSION_10_7_HEX);
 }
 #endif
 static void
 my_malloc_logger(uint32_t type, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3,
                  uintptr_t result, uint32_t num_hot_frames_to_skip)
 {
   static bool once = false;
   if (once)
     return;
   once = true;
   // On Leopard dladdr returns the wrong value for "new_sem_from_pool". The
   // stack shows up as having two pthread_cond_wait$UNIX2003 frames.
   const char *name = "new_sem_from_pool";
   NS_StackWalk(stack_callback, /* skipFrames */ 0, /* maxFrames */ 0,
                const_cast<char*>(name), 0, nullptr);
 }
 // This is called from NS_LogInit() and from the stack walking functions, but
 // only the first call has any effect.  We need to call this function from both
 // places because it must run before any mutexes are created, and also before
 // any objects whose refcounts we're logging are created.  Running this
 // function during NS_LogInit() ensures that we meet the first criterion, and
 // running this function during the stack walking functions ensures we meet the
 // second criterion.
 void
 StackWalkInitCriticalAddress()
 {
   if(gCriticalAddress.mInit)
     return;
   gCriticalAddress.mInit = true;
   // We must not do work when 'new_sem_from_pool' calls realloc, since
   // it holds a non-reentrant spin-lock and we will quickly deadlock.
   // new_sem_from_pool is not directly accessible using dlsym, so
   // we force a situation where new_sem_from_pool is on the stack and
   // use dladdr to check the addresses.
   // malloc_logger can be set by external tools like 'Instruments' or 'leaks'
   malloc_logger_t *old_malloc_logger = malloc_logger;
   malloc_logger = my_malloc_logger;
   pthread_cond_t cond;
   int r = pthread_cond_init(&cond, 0);
   MOZ_ASSERT(r == 0);
   pthread_mutex_t mutex;
   r = pthread_mutex_init(&mutex,0);
   MOZ_ASSERT(r == 0);
   r = pthread_mutex_lock(&mutex);
   MOZ_ASSERT(r == 0);
   struct timespec abstime = {0, 1};
   r = pthread_cond_timedwait_relative_np(&cond, &mutex, &abstime);
   // restore the previous malloc logger
   malloc_logger = old_malloc_logger;
   // On Lion, malloc is no longer called from pthread_cond_*wait*. This prevents
   // us from finding the address, but that is fine, since with no call to malloc
   // there is no critical address.
   MOZ_ASSERT(OnLionOrLater() || gCriticalAddress.mAddr != nullptr);
   MOZ_ASSERT(r == ETIMEDOUT);
   r = pthread_mutex_unlock(&mutex);
   MOZ_ASSERT(r == 0);
   r = pthread_mutex_destroy(&mutex);
   MOZ_ASSERT(r == 0);
   r = pthread_cond_destroy(&cond);
   MOZ_ASSERT(r == 0);
 }
 static bool IsCriticalAddress(void* aPC)
 {
   return gCriticalAddress.mAddr == aPC;
 }
 #else
 static bool IsCriticalAddress(void* aPC)
 {
   return false;
 }
 // We still initialize gCriticalAddress.mInit so that this code behaves
 // the same on all platforms. Otherwise a failure to init would be visible
 // only on OS X.
 void
 StackWalkInitCriticalAddress()
 {
   gCriticalAddress.mInit = true;
 }
 #endif
 #if defined(_WIN32) && (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_IA64)) // WIN32 x86 stack walking code
 #include "nscore.h"
 #include <windows.h>
 #include <process.h>
 #include <stdio.h>
 #include <malloc.h>
 #include "plstr.h"
 #include "mozilla/ArrayUtils.h"
 #include "nspr.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
 // Define these as static pointers so that we can load the DLL on the
 // fly (and not introduce a link-time dependency on it). Tip o' the
 // hat to Matt Pietrick for this idea. See:
 //
 //   http://msdn.microsoft.com/library/periodic/period97/F1/D3/S245C6.htm
 //
 extern "C" {
 extern HANDLE hStackWalkMutex;
 bool EnsureSymInitialized();
 bool EnsureWalkThreadReady();
 struct WalkStackData {
   uint32_t skipFrames;
   HANDLE thread;
   bool walkCallingThread;
   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;
   void *platformData;
 };
 void PrintError(char *prefix, WalkStackData* data);
 unsigned int WINAPI WalkStackThread(void* data);
 void WalkStackMain64(struct WalkStackData* data);
 DWORD gStackWalkThread;
 CRITICAL_SECTION gDbgHelpCS;
 }
 // Routine to print an error message to standard error.
 void PrintError(const char *prefix)
 {
     LPVOID 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,
 ,
       nullptr
     );
     fprintf(stderr, "### ERROR: %s: %s",
                     prefix, lpMsgBuf ? lpMsgBuf : "(null)\n");
     fflush(stderr);
     LocalFree(lpMsgBuf);
 }
 bool
 EnsureWalkThreadReady()
 {
     static bool walkThreadReady = false;
     static HANDLE stackWalkThread = nullptr;
     static HANDLE readyEvent = nullptr;
     if (walkThreadReady)
         return walkThreadReady;
     if (stackWalkThread == nullptr) {
         readyEvent = ::CreateEvent(nullptr, FALSE /* auto-reset*/,
                                    FALSE /* initially non-signaled */,
                                    nullptr);
         if (readyEvent == nullptr) {
             PrintError("CreateEvent");
             return false;
         }
         unsigned int threadID;
         stackWalkThread = (HANDLE)
             _beginthreadex(nullptr, 0, WalkStackThread, (void*)readyEvent,
 , &threadID);
         if (stackWalkThread == nullptr) {
             PrintError("CreateThread");
             ::CloseHandle(readyEvent);
             readyEvent = nullptr;
             return false;
         }
         gStackWalkThread = threadID;
         ::CloseHandle(stackWalkThread);
     }
     MOZ_ASSERT((stackWalkThread != nullptr && readyEvent != nullptr) ||
                (stackWalkThread == nullptr && readyEvent == nullptr));
     // The thread was created. Try to wait an arbitrary amount of time (1 second
     // should be enough) for its event loop to start before posting events to it.
     DWORD waitRet = ::WaitForSingleObject(readyEvent, 1000);
     if (waitRet == WAIT_TIMEOUT) {
         // We get a timeout if we're called during static initialization because
         // the thread will only start executing after we return so it couldn't
         // have signalled the event. If that is the case, give up for now and
         // try again next time we're called.
         return false;
     }
     ::CloseHandle(readyEvent);
     stackWalkThread = nullptr;
     readyEvent = nullptr;
     ::InitializeCriticalSection(&gDbgHelpCS);
     return walkThreadReady = true;
 }
 void
 WalkStackMain64(struct WalkStackData* data)
 {
     // Get the context information for the thread. That way we will
     // know where our sp, fp, pc, etc. are and can fill in the
     // STACKFRAME64 with the initial values.
     CONTEXT context;
     HANDLE myProcess = data->process;
     HANDLE myThread = data->thread;
     DWORD64 addr;
     DWORD64 spaddr;
     STACKFRAME64 frame64;
     // skip our own stack walking frames
     int skip = (data->walkCallingThread ? 3 : 0) + data->skipFrames;
     BOOL ok;
     // Get a context for the specified thread.
     if (!data->platformData) {
         memset(&context, 0, sizeof(CONTEXT));
         context.ContextFlags = CONTEXT_FULL;
         if (!GetThreadContext(myThread, &context)) {
             if (data->walkCallingThread) {
                 PrintError("GetThreadContext");
             }
             return;
         }
     } else {
         context = *static_cast<CONTEXT*>(data->platformData);
     }
     // Setup initial stack frame to walk from
     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_AMD64
     frame64.AddrPC.Offset    = context.Rip;
     frame64.AddrStack.Offset = context.Rsp;
     frame64.AddrFrame.Offset = context.Rbp;
 #elif defined _M_IA64
     frame64.AddrPC.Offset    = context.StIIP;
     frame64.AddrStack.Offset = context.SP;
     frame64.AddrFrame.Offset = context.RsBSP;
 #else
 #error "Should not have compiled this code"
 #endif
     frame64.AddrPC.Mode      = AddrModeFlat;
     frame64.AddrStack.Mode   = AddrModeFlat;
     frame64.AddrFrame.Mode   = AddrModeFlat;
     frame64.AddrReturn.Mode  = AddrModeFlat;
     // Now walk the stack
     while (1) {
         // debug routines are not threadsafe, so grab the lock.
         EnterCriticalSection(&gDbgHelpCS);
         ok = StackWalk64(
 #ifdef _M_AMD64
           IMAGE_FILE_MACHINE_AMD64,
 #elif defined _M_IA64
           IMAGE_FILE_MACHINE_IA64,
 #elif defined _M_IX86
           IMAGE_FILE_MACHINE_I386,
 #else
 #error "Should not have compiled this code"
 #endif
           myProcess,
           myThread,
           &frame64,
           &context,
           nullptr,
           SymFunctionTableAccess64, // function table access routine
           SymGetModuleBase64,       // module base routine
 
         );
         LeaveCriticalSection(&gDbgHelpCS);
         if (ok) {
             addr = frame64.AddrPC.Offset;
             spaddr = frame64.AddrStack.Offset;
          } else {
             addr = 0;
             spaddr = 0;
             if (data->walkCallingThread) {
                 PrintError("WalkStack64");
             }
         }
         if (!ok || (addr == 0)) {
             break;
         }
         if (skip-- > 0) {
             continue;
         }
         if (data->pc_count < data->pc_size)
             data->pcs[data->pc_count] = (void*)addr;
         ++data->pc_count;
         if (data->sp_count < data->sp_size)
             data->sps[data->sp_count] = (void*)spaddr;
         ++data->sp_count;
         if (data->pc_max != 0 && data->pc_count == data->pc_max)
             break;
         if (frame64.AddrReturn.Offset == 0)
             break;
     }
     return;
 }
 unsigned int WINAPI
 WalkStackThread(void* aData)
 {
     BOOL msgRet;
     MSG msg;
     // Call PeekMessage to force creation of a message queue so that
     // other threads can safely post events to us.
     ::PeekMessage(&msg, nullptr, WM_USER, WM_USER, PM_NOREMOVE);
     // and tell the thread that created us that we're ready.
     HANDLE readyEvent = (HANDLE)aData;
     ::SetEvent(readyEvent);
     while ((msgRet = ::GetMessage(&msg, (HWND)-1, 0, 0)) != 0) {
         if (msgRet == -1) {
             PrintError("GetMessage");
         } else {
             DWORD ret;
             struct WalkStackData *data = (WalkStackData *)msg.lParam;
             if (!data)
               continue;
             // Don't suspend the calling thread until it's waiting for
             // us; otherwise the number of frames on the stack could vary.
             ret = ::WaitForSingleObject(data->eventStart, INFINITE);
             if (ret != WAIT_OBJECT_0)
                 PrintError("WaitForSingleObject");
             // Suspend the calling thread, dump his stack, and then resume him.
             // He's currently waiting for us to finish so now should be a good time.
             ret = ::SuspendThread( data->thread );
             if (ret == -1) {
                 PrintError("ThreadSuspend");
             }
             else {
                 WalkStackMain64(data);
                 ret = ::ResumeThread(data->thread);
                 if (ret == -1) {
                     PrintError("ThreadResume");
                 }
             }
             ::SetEvent(data->eventEnd);
         }
     }
     return 0;
 }
 /**
  * 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.
  */
 EXPORT_XPCOM_API(nsresult)
 NS_StackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
              uint32_t aMaxFrames, void *aClosure, uintptr_t aThread,
              void *aPlatformData)
 {
     StackWalkInitCriticalAddress();
     static HANDLE myProcess = nullptr;
     HANDLE myThread;
     DWORD walkerReturn;
     struct WalkStackData data;
     if (!EnsureWalkThreadReady())
         return NS_ERROR_FAILURE;
     HANDLE targetThread = ::GetCurrentThread();
     data.walkCallingThread = true;
     if (aThread) {
         HANDLE threadToWalk = reinterpret_cast<HANDLE> (aThread);
         // walkCallingThread indicates whether we are walking the caller's stack
         data.walkCallingThread = (threadToWalk == targetThread);
         targetThread = threadToWalk;
     }
     // We need to avoid calling fprintf and friends if we're walking the stack of
     // another thread, in order to avoid deadlocks.
     const bool shouldBeThreadSafe = !!aThread;
     // Have to duplicate handle to get a real handle.
     if (!myProcess) {
         if (!::DuplicateHandle(::GetCurrentProcess(),
                                ::GetCurrentProcess(),
                                ::GetCurrentProcess(),
                                &myProcess,
                                PROCESS_ALL_ACCESS, FALSE, 0)) {
             if (!shouldBeThreadSafe) {
                 PrintError("DuplicateHandle (process)");
             }
             return NS_ERROR_FAILURE;
         }
     }
     if (!::DuplicateHandle(::GetCurrentProcess(),
                            targetThread,
                            ::GetCurrentProcess(),
                            &myThread,
                            THREAD_ALL_ACCESS, FALSE, 0)) {
         if (!shouldBeThreadSafe) {
             PrintError("DuplicateHandle (thread)");
         }
         return NS_ERROR_FAILURE;
     }
     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.platformData = aPlatformData;
     if (aThread) {
         // If we're walking the stack of another thread, we don't need to
         // use a separate walker thread.
         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);
         }
     } else {
         data.eventStart = ::CreateEvent(nullptr, FALSE /* auto-reset*/,
                               FALSE /* initially non-signaled */, nullptr);
         data.eventEnd = ::CreateEvent(nullptr, FALSE /* auto-reset*/,
                             FALSE /* initially non-signaled */, nullptr);
         ::PostThreadMessage(gStackWalkThread, WM_USER, 0, (LPARAM)&data);
         walkerReturn = ::SignalObjectAndWait(data.eventStart,
                            data.eventEnd, INFINITE, FALSE);
         if (walkerReturn != WAIT_OBJECT_0 && !shouldBeThreadSafe)
             PrintError("SignalObjectAndWait (1)");
         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;
             ::PostThreadMessage(gStackWalkThread, WM_USER, 0, (LPARAM)&data);
             walkerReturn = ::SignalObjectAndWait(data.eventStart,
                                data.eventEnd, INFINITE, FALSE);
             if (walkerReturn != WAIT_OBJECT_0 && !shouldBeThreadSafe)
                 PrintError("SignalObjectAndWait (2)");
         }
         ::CloseHandle(data.eventStart);
         ::CloseHandle(data.eventEnd);
     }
     ::CloseHandle(myThread);
     for (uint32_t i = 0; i < data.pc_count; ++i)
         (*aCallback)(data.pcs[i], data.sps[i], aClosure);
     return data.pc_count == 0 ? NS_ERROR_FAILURE : NS_OK;
 }
 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 (nullptr != aLineInfo) {
         aLineInfo->SizeOfStruct = sizeof(IMAGEHLP_LINE64);
     }
     /*
      * Give it a go.
      * It may already be loaded.
      */
     retval = SymGetModuleInfo64(aProcess, aAddr, aModuleInfo);
     if (FALSE == retval) {
         BOOL enumRes = 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.
         enumRes = EnumerateLoadedModules64(aProcess, (PENUMLOADED_MODULES_CALLBACK64)callbackEspecial64, (PVOID)&aAddr);
         if (FALSE != enumRes)
         {
             /*
              * 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 (FALSE != retval && nullptr != 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;
 }
 bool
 EnsureSymInitialized()
 {
     static bool gInitialized = false;
     bool retStat;
     if (gInitialized)
         return gInitialized;
     if (!EnsureWalkThreadReady())
         return false;
     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;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_DescribeCodeAddress(void *aPC, nsCodeAddressDetails *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 NS_ERROR_FAILURE;
     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) {
         PL_strncpyz(aDetails->library, modInfo.ModuleName,
                     sizeof(aDetails->library));
         aDetails->loffset = (char*) aPC - (char*) modInfo.BaseOfImage;
         if (lineInfo.FileName) {
             PL_strncpyz(aDetails->filename, lineInfo.FileName,
                         sizeof(aDetails->filename));
             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) {
         PL_strncpyz(aDetails->function, pSymbol->Name,
                     sizeof(aDetails->function));
         aDetails->foffset = static_cast<ptrdiff_t>(displacement);
     }
     LeaveCriticalSection(&gDbgHelpCS); // release our lock
     return NS_OK;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_FormatCodeAddressDetails(void *aPC, const nsCodeAddressDetails *aDetails,
                             char *aBuffer, uint32_t aBufferSize)
 {
     if (aDetails->function[0]) {
         _snprintf(aBuffer, aBufferSize, "%s+0x%08lX [%s +0x%016lX]",
                   aDetails->function, aDetails->foffset,
                   aDetails->library, aDetails->loffset);
     } else if (aDetails->library[0]) {
         _snprintf(aBuffer, aBufferSize, "UNKNOWN [%s +0x%016lX]",
                   aDetails->library, aDetails->loffset);
     } else {
         _snprintf(aBuffer, aBufferSize, "UNKNOWN 0x%016lX", aPC);
     }
     aBuffer[aBufferSize - 1] = '\0';
     uint32_t len = strlen(aBuffer);
     if (aDetails->filename[0]) {
         _snprintf(aBuffer + len, aBufferSize - len, " (%s, line %d)\n",
                   aDetails->filename, aDetails->lineno);
     } else {
         aBuffer[len] = '\n';
         if (++len != aBufferSize)
             aBuffer[len] = '\0';
     }
     aBuffer[aBufferSize - 2] = '\n';
     aBuffer[aBufferSize - 1] = '\0';
     return NS_OK;
 }
 // WIN32 x86 stack walking code
 // i386 or PPC Linux stackwalking code or Solaris
 #elif HAVE_DLADDR && (HAVE__UNWIND_BACKTRACE || NSSTACKWALK_SUPPORTS_LINUX || NSSTACKWALK_SUPPORTS_SOLARIS || NSSTACKWALK_SUPPORTS_MACOSX)
 #include <stdlib.h>
 #include <string.h>
 #include "nscore.h"
 #include <stdio.h>
 #include "plstr.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)
     {
         PL_strncpyz(aBuffer,demangled,aBufLen);
         free(demangled);
     }
 #endif // MOZ_DEMANGLE_SYMBOLS
 }
 #if NSSTACKWALK_SUPPORTS_SOLARIS
 /*
  * Stack walking code for Solaris courtesy of Bart Smaalder's "memtrak".
  */
 #include <synch.h>
 #include <ucontext.h>
 #include <sys/frame.h>
 #include <sys/regset.h>
 #include <sys/stack.h>
 static int    load_address ( void * pc, void * arg );
 static struct bucket * newbucket ( void * pc );
 static struct frame * cs_getmyframeptr ( void );
 static void   cs_walk_stack ( void * (*read_func)(char * address),
                               struct frame * fp,
                               int (*operate_func)(void *, void *, void *),
                               void * usrarg );
 static void   cs_operate ( void (*operate_func)(void *, void *, void *),
                            void * usrarg );
 #ifndef STACK_BIAS
 #define STACK_BIAS 0
 #endif /*STACK_BIAS*/
 #define LOGSIZE 4096
 /* type of demangling function */
 typedef int demf_t(const char *, char *, size_t);
 static demf_t *demf;
 static int initialized = 0;
 #if defined(sparc) || defined(__sparc)
 #define FRAME_PTR_REGISTER REG_SP
 #endif
 #if defined(i386) || defined(__i386)
 #define FRAME_PTR_REGISTER EBP
 #endif
 struct bucket {
     void * pc;
     int index;
     struct bucket * next;
 };
 struct my_user_args {
     NS_WalkStackCallback callback;
     uint32_t skipFrames;
     uint32_t maxFrames;
     uint32_t numFrames;
     void *closure;
 };
 static void myinit();
 #pragma init (myinit)
 static void
 myinit()
 {
     if (! initialized) {
 #ifndef __GNUC__
         void *handle;
         const char *libdem = "libdemangle.so.1";
         /* load libdemangle if we can and need to (only try this once) */
         if ((handle = dlopen(libdem, RTLD_LAZY)) != nullptr) {
             demf = (demf_t *)dlsym(handle,
                            "cplus_demangle"); /*lint !e611 */
                 /*
                  * lint override above is to prevent lint from
                  * complaining about "suspicious cast".
                  */
         }
 #endif /*__GNUC__*/
     }
     initialized = 1;
 }
 static int
 load_address(void * pc, void * arg)
 {
     static struct bucket table[2048];
     static mutex_t lock;
     struct bucket * ptr;
     struct my_user_args * args = (struct my_user_args *) arg;
     unsigned int val = NS_PTR_TO_INT32(pc);
     ptr = table + ((val >> 2)&2047);
     mutex_lock(&lock);
     while (ptr->next) {
         if (ptr->next->pc == pc)
             break;
         ptr = ptr->next;
     }
     int stop = 0;
     if (ptr->next) {
         mutex_unlock(&lock);
     } else {
         (args->callback)(pc, args->closure);
         args->numFrames++;
         if (args->maxFrames != 0 && args->numFrames == args->maxFrames)
           stop = 1;   // causes us to stop getting frames
         ptr->next = newbucket(pc);
         mutex_unlock(&lock);
     }
     return stop;
 }
 static struct bucket *
 newbucket(void * pc)
 {
     struct bucket * ptr = (struct bucket *) malloc(sizeof (*ptr));
     static int index; /* protected by lock in caller */
     ptr->index = index++;
     ptr->next = nullptr;
     ptr->pc = pc;
     return (ptr);
 }
 static struct frame *
 csgetframeptr()
 {
     ucontext_t u;
     struct frame *fp;
     (void) getcontext(&u);
     fp = (struct frame *)
         ((char *)u.uc_mcontext.gregs[FRAME_PTR_REGISTER] +
         STACK_BIAS);
     /* make sure to return parents frame pointer.... */
     return ((struct frame *)((ulong_t)fp->fr_savfp + STACK_BIAS));
 }
 static void
 cswalkstack(struct frame *fp, int (*operate_func)(void *, void *, void *),
     void *usrarg)
 {
     while (fp != 0 && fp->fr_savpc != 0) {
         if (operate_func((void *)fp->fr_savpc, nullptr, usrarg) != 0)
             break;
         /*
          * watch out - libthread stacks look funny at the top
          * so they may not have their STACK_BIAS set
          */
         fp = (struct frame *)((ulong_t)fp->fr_savfp +
             (fp->fr_savfp?(ulong_t)STACK_BIAS:0));
     }
 }
 static void
 cs_operate(int (*operate_func)(void *, void *, void *), void * usrarg)
 {
     cswalkstack(csgetframeptr(), operate_func, usrarg);
 }
 EXPORT_XPCOM_API(nsresult)
 NS_StackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
              uint32_t aMaxFrames, void *aClosure, uintptr_t aThread,
              void *aPlatformData)
 {
     MOZ_ASSERT(!aThread);
     MOZ_ASSERT(!aPlatformData);
     struct my_user_args args;
     StackWalkInitCriticalAddress();
     if (!initialized)
         myinit();
     args.callback = aCallback;
     args.skipFrames = aSkipFrames; /* XXX Not handled! */
     args.maxFrames = aMaxFrames;
     args.numFrames = 0;
     args.closure = aClosure;
     cs_operate(load_address, &args);
     return args.numFrames == 0 ? NS_ERROR_FAILURE : NS_OK;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_DescribeCodeAddress(void *aPC, nsCodeAddressDetails *aDetails)
 {
     aDetails->library[0] = '\0';
     aDetails->loffset = 0;
     aDetails->filename[0] = '\0';
     aDetails->lineno = 0;
     aDetails->function[0] = '\0';
     aDetails->foffset = 0;
     char dembuff[4096];
     Dl_info info;
     if (dladdr(aPC, & info)) {
         if (info.dli_fname) {
             PL_strncpyz(aDetails->library, info.dli_fname,
                         sizeof(aDetails->library));
             aDetails->loffset = (char*)aPC - (char*)info.dli_fbase;
         }
         if (info.dli_sname) {
             aDetails->foffset = (char*)aPC - (char*)info.dli_saddr;
 #ifdef __GNUC__
             DemangleSymbol(info.dli_sname, dembuff, sizeof(dembuff));
 #else
             if (!demf || demf(info.dli_sname, dembuff, sizeof (dembuff)))
                 dembuff[0] = 0;
 #endif /*__GNUC__*/
             PL_strncpyz(aDetails->function,
                         (dembuff[0] != '\0') ? dembuff : info.dli_sname,
                         sizeof(aDetails->function));
         }
     }
     return NS_OK;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_FormatCodeAddressDetails(void *aPC, const nsCodeAddressDetails *aDetails,
                             char *aBuffer, uint32_t aBufferSize)
 {
     snprintf(aBuffer, aBufferSize, "%p %s:%s+0x%lx\n",
              aPC,
              aDetails->library[0] ? aDetails->library : "??",
              aDetails->function[0] ? aDetails->function : "??",
              aDetails->foffset);
     return NS_OK;
 }
 #else // not __sun-specific
 #if __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 void *__libc_stack_end; // from ld-linux.so
 #endif
 namespace mozilla {
 nsresult
 FramePointerStackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
                       uint32_t aMaxFrames, void *aClosure, void **bp,
                       void *aStackEnd)
 {
   // Stack walking code courtesy Kipp's "leaky".
   int32_t skip = aSkipFrames;
   uint32_t numFrames = 0;
   while (1) {
     void **next = (void**)*bp;
     // bp may not be a frame pointer on i386 if code was compiled with
     // -fomit-frame-pointer, so do some sanity checks.
     // (bp 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 bp > sp
     if (next <= bp ||
         next > aStackEnd ||
         (long(next) & 3)) {
       break;
     }
 #if (defined(__ppc__) && defined(XP_MACOSX)) || defined(__powerpc64__)
     // ppc mac or powerpc64 linux
     void *pc = *(bp+2);
     bp += 3;
 #else // i386 or powerpc32 linux
     void *pc = *(bp+1);
     bp += 2;
 #endif
     if (IsCriticalAddress(pc)) {
       printf("Aborting stack trace, PC is critical\n");
       return NS_ERROR_UNEXPECTED;
     }
     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.
       (*aCallback)(pc, bp, aClosure);
       numFrames++;
       if (aMaxFrames != 0 && numFrames == aMaxFrames)
         break;
     }
     bp = next;
   }
   return numFrames == 0 ? NS_ERROR_FAILURE : NS_OK;
 }
 }
 #define X86_OR_PPC (defined(__i386) || defined(PPC) || defined(__ppc__))
 #if X86_OR_PPC && (NSSTACKWALK_SUPPORTS_MACOSX || NSSTACKWALK_SUPPORTS_LINUX) // i386 or PPC Linux or Mac stackwalking code
 EXPORT_XPCOM_API(nsresult)
 NS_StackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
              uint32_t aMaxFrames, void *aClosure, uintptr_t aThread,
              void *aPlatformData)
 {
   MOZ_ASSERT(!aThread);
   MOZ_ASSERT(!aPlatformData);
   StackWalkInitCriticalAddress();
   // Get the frame pointer
   void **bp;
 #if defined(__i386)
   __asm__( "movl %%ebp, %0" : "=g"(bp));
 #else
   // It would be nice if this worked uniformly, but at least on i386 and
   // x86_64, it stopped working with gcc 4.1, because it points to the
   // end of the saved registers instead of the start.
   bp = (void**) __builtin_frame_address(0);
 #endif
   void *stackEnd;
 #if HAVE___LIBC_STACK_END
   stackEnd = __libc_stack_end;
 #else
   stackEnd = reinterpret_cast<void*>(-1);
 #endif
   return 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 {
     NS_WalkStackCallback callback;
     int skip;
     int maxFrames;
     int numFrames;
     bool isCriticalAbort;
     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 (IsCriticalAddress(pc)) {
         printf("Aborting stack trace, PC is critical\n");
         info->isCriticalAbort = true;
         // We just want to stop the walk, so any error code will do.  Using
         // _URC_NORMAL_STOP would probably be the most accurate, but it is not
         // defined on Android for ARM.
         return _URC_FOREIGN_EXCEPTION_CAUGHT;
     }
     if (--info->skip < 0) {
         (*info->callback)(pc, nullptr, info->closure);
         info->numFrames++;
         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;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_StackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
              uint32_t aMaxFrames, void *aClosure, uintptr_t aThread,
              void *aPlatformData)
 {
     MOZ_ASSERT(!aThread);
     MOZ_ASSERT(!aPlatformData);
     StackWalkInitCriticalAddress();
     unwind_info info;
     info.callback = aCallback;
     info.skip = aSkipFrames + 1;
     info.maxFrames = aMaxFrames;
     info.numFrames = 0;
     info.isCriticalAbort = false;
     info.closure = aClosure;
     (void)_Unwind_Backtrace(unwind_callback, &info);
     // We ignore the return value from _Unwind_Backtrace and instead determine
     // the outcome from |info|.  There are two 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.
     if (info.isCriticalAbort)
         return NS_ERROR_UNEXPECTED;
     return info.numFrames == 0 ? NS_ERROR_FAILURE : NS_OK;
 }
 #endif
 EXPORT_XPCOM_API(nsresult)
 NS_DescribeCodeAddress(void *aPC, nsCodeAddressDetails *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 NS_OK;
   }
   PL_strncpyz(aDetails->library, info.dli_fname, sizeof(aDetails->library));
   aDetails->loffset = (char*)aPC - (char*)info.dli_fbase;
   const char * symbol = info.dli_sname;
   if (!symbol || symbol[0] == '\0') {
     return NS_OK;
   }
   DemangleSymbol(symbol, aDetails->function, sizeof(aDetails->function));
   if (aDetails->function[0] == '\0') {
     // Just use the mangled symbol if demangling failed.
     PL_strncpyz(aDetails->function, symbol, sizeof(aDetails->function));
   }
   aDetails->foffset = (char*)aPC - (char*)info.dli_saddr;
   return NS_OK;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_FormatCodeAddressDetails(void *aPC, const nsCodeAddressDetails *aDetails,
                             char *aBuffer, uint32_t aBufferSize)
 {
   if (!aDetails->library[0]) {
     snprintf(aBuffer, aBufferSize, "UNKNOWN %p\n", aPC);
   } else if (!aDetails->function[0]) {
     snprintf(aBuffer, aBufferSize, "UNKNOWN [%s +0x%08" PRIXPTR "]\n",
                                    aDetails->library, aDetails->loffset);
   } else {
     snprintf(aBuffer, aBufferSize, "%s+0x%08" PRIXPTR
                                    " [%s +0x%08" PRIXPTR "]\n",
                                    aDetails->function, aDetails->foffset,
                                    aDetails->library, aDetails->loffset);
   }
   return NS_OK;
 }
 #endif
 #else // unsupported platform.
 EXPORT_XPCOM_API(nsresult)
 NS_StackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
              uint32_t aMaxFrames, void *aClosure, uintptr_t aThread,
              void *aPlatformData)
 {
     MOZ_ASSERT(!aThread);
     MOZ_ASSERT(!aPlatformData);
     return NS_ERROR_NOT_IMPLEMENTED;
 }
 namespace mozilla {
 nsresult
 FramePointerStackWalk(NS_WalkStackCallback aCallback, uint32_t aSkipFrames,
                       void *aClosure, void **bp)
 {
     return NS_ERROR_NOT_IMPLEMENTED;
 }
 }
 EXPORT_XPCOM_API(nsresult)
 NS_DescribeCodeAddress(void *aPC, nsCodeAddressDetails *aDetails)
 {
     aDetails->library[0] = '\0';
     aDetails->loffset = 0;
     aDetails->filename[0] = '\0';
     aDetails->lineno = 0;
     aDetails->function[0] = '\0';
     aDetails->foffset = 0;
     return NS_ERROR_NOT_IMPLEMENTED;
 }
 EXPORT_XPCOM_API(nsresult)
 NS_FormatCodeAddressDetails(void *aPC, const nsCodeAddressDetails *aDetails,
                             char *aBuffer, uint32_t aBufferSize)
 {
     aBuffer[0] = '\0';
     return NS_ERROR_NOT_IMPLEMENTED;
 }
 #endif

The Tor Browser / annotate

xpcom/base/nsStackWalk.cpp@6474c204b198 (annotated)

xpcom/base/nsStackWalk.cpp