diff -r 000000000000 -r 6474c204b198 xpcom/base/nsStackWalk.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/base/nsStackWalk.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,1396 @@
+/* -*- 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,
+      0,
+      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,
+                           0, &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
+          0
+        );
+        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