The Tor Browser: xpcom/build/LateWriteChecks.cpp@b8a032363ba2 (annotated)

xpcom/build/LateWriteChecks.cpp@b8a032363ba2 (annotated)

xpcom/build/LateWriteChecks.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* vim:set ts=4 sw=4 sts=4 ci et: */
 /* 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/. */
 #include <algorithm>
 #include "mozilla/IOInterposer.h"
 #include "mozilla/PoisonIOInterposer.h"
 #include "mozilla/ProcessedStack.h"
 #include "mozilla/SHA1.h"
 #include "mozilla/Scoped.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/Telemetry.h"
 #include "nsAppDirectoryServiceDefs.h"
 #include "nsDirectoryServiceUtils.h"
 #include "nsPrintfCString.h"
 #include "nsStackWalk.h"
 #include "plstr.h"
 #ifdef XP_WIN
 #define NS_T(str) L ## str
 #define NS_SLASH "\\"
 #include <fcntl.h>
 #include <io.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <windows.h>
 #else
 #define NS_SLASH "/"
 #endif
 #include "LateWriteChecks.h"
 #if !defined(XP_WIN) || (!defined(MOZ_OPTIMIZE) || defined(MOZ_PROFILING) || defined(DEBUG))
 #define OBSERVE_LATE_WRITES
 #endif
 using namespace mozilla;
 /*************************** Auxiliary Declarations ***************************/
 // This a wrapper over a file descriptor that provides a Printf method and
 // computes the sha1 of the data that passes through it.
 class SHA1Stream
 {
 public:
     explicit SHA1Stream(FILE *stream)
       : mFile(stream)
     {
       MozillaRegisterDebugFILE(mFile);
     }
     void Printf(const char *aFormat, ...)
     {
         MOZ_ASSERT(mFile);
         va_list list;
         va_start(list, aFormat);
         nsAutoCString str;
         str.AppendPrintf(aFormat, list);
         va_end(list);
         mSHA1.update(str.get(), str.Length());
         fwrite(str.get(), 1, str.Length(), mFile);
     }
     void Finish(SHA1Sum::Hash &aHash)
     {
         int fd = fileno(mFile);
         fflush(mFile);
         MozillaUnRegisterDebugFD(fd);
         fclose(mFile);
         mSHA1.finish(aHash);
         mFile = nullptr;
     }
 private:
     FILE *mFile;
     SHA1Sum mSHA1;
 };
 static void RecordStackWalker(void *aPC, void *aSP, void *aClosure)
 {
     std::vector<uintptr_t> *stack =
         static_cast<std::vector<uintptr_t>*>(aClosure);
     stack->push_back(reinterpret_cast<uintptr_t>(aPC));
 }
 /**************************** Late-Write Observer  ****************************/
 /**
  * An implementation of IOInterposeObserver to be registered with IOInterposer.
  * This observer logs all writes as late writes.
  */
 class LateWriteObserver MOZ_FINAL : public IOInterposeObserver
 {
 public:
   LateWriteObserver(const char* aProfileDirectory)
     : mProfileDirectory(PL_strdup(aProfileDirectory))
   {
   }
   ~LateWriteObserver() {
     PL_strfree(mProfileDirectory);
     mProfileDirectory = nullptr;
   }
   void Observe(IOInterposeObserver::Observation& aObservation);
 private:
   char* mProfileDirectory;
 };
 void LateWriteObserver::Observe(IOInterposeObserver::Observation& aOb)
 {
 #ifdef OBSERVE_LATE_WRITES
   // Crash if that is the shutdown check mode
   if (gShutdownChecks == SCM_CRASH) {
     MOZ_CRASH();
   }
   // If we have shutdown mode SCM_NOTHING or we can't record then abort
   if (gShutdownChecks == SCM_NOTHING || !Telemetry::CanRecord()) {
     return;
   }
   // Write the stack and loaded libraries to a file. We can get here
   // concurrently from many writes, so we use multiple temporary files.
   std::vector<uintptr_t> rawStack;
   NS_StackWalk(RecordStackWalker, /* skipFrames */ 0, /* maxFrames */ 0,
                reinterpret_cast<void*>(&rawStack), 0, nullptr);
   Telemetry::ProcessedStack stack = Telemetry::GetStackAndModules(rawStack);
   nsPrintfCString nameAux("%s%s%s", mProfileDirectory,
                           NS_SLASH, "Telemetry.LateWriteTmpXXXXXX");
   char *name;
   nameAux.GetMutableData(&name);
   // We want the sha1 of the entire file, so please don't write to fd
   // directly; use sha1Stream.
   FILE *stream;
 #ifdef XP_WIN
   HANDLE hFile;
   do {
     // mkstemp isn't supported so keep trying until we get a file
     int result = _mktemp_s(name, strlen(name) + 1);
     hFile = CreateFileA(name, GENERIC_WRITE, 0, nullptr, CREATE_NEW,
                         FILE_ATTRIBUTE_NORMAL, nullptr);
   } while (GetLastError() == ERROR_FILE_EXISTS);
   if (hFile == INVALID_HANDLE_VALUE) {
     NS_RUNTIMEABORT("Um, how did we get here?");
   }
   // http://support.microsoft.com/kb/139640
   int fd = _open_osfhandle((intptr_t)hFile, _O_APPEND);
   if (fd == -1) {
     NS_RUNTIMEABORT("Um, how did we get here?");
   }
   stream = _fdopen(fd, "w");
 #else
   int fd = mkstemp(name);
   stream = fdopen(fd, "w");
 #endif
   SHA1Stream sha1Stream(stream);
   size_t numModules = stack.GetNumModules();
   sha1Stream.Printf("%u\n", (unsigned)numModules);
   for (size_t i = 0; i < numModules; ++i) {
     Telemetry::ProcessedStack::Module module = stack.GetModule(i);
     sha1Stream.Printf("%s %s\n", module.mBreakpadId.c_str(),
                       module.mName.c_str());
   }
   size_t numFrames = stack.GetStackSize();
   sha1Stream.Printf("%u\n", (unsigned)numFrames);
   for (size_t i = 0; i < numFrames; ++i) {
     const Telemetry::ProcessedStack::Frame &frame =
         stack.GetFrame(i);
     // NOTE: We write the offsets, while the atos tool expects a value with
     // the virtual address added. For example, running otool -l on the the firefox
     // binary shows
     //      cmd LC_SEGMENT_64
     //      cmdsize 632
     //      segname __TEXT
     //      vmaddr 0x0000000100000000
     // so to print the line matching the offset 123 one has to run
     // atos -o firefox 0x100000123.
     sha1Stream.Printf("%d %x\n", frame.mModIndex, (unsigned)frame.mOffset);
   }
   SHA1Sum::Hash sha1;
   sha1Stream.Finish(sha1);
   // Note: These files should be deleted by telemetry once it reads them. If
   // there were no telemetry runs by the time we shut down, we just add files
   // to the existing ones instead of replacing them. Given that each of these
   // files is a bug to be fixed, that is probably the right thing to do.
   // We append the sha1 of the contents to the file name. This provides a simple
   // client side deduplication.
   nsPrintfCString finalName("%s%s", mProfileDirectory,
                             "/Telemetry.LateWriteFinal-");
   for (int i = 0; i < 20; ++i) {
     finalName.AppendPrintf("%02x", sha1[i]);
   }
   PR_Delete(finalName.get());
   PR_Rename(name, finalName.get());
 #endif
 }
 /******************************* Setup/Teardown *******************************/
 static StaticAutoPtr<LateWriteObserver> sLateWriteObserver;
 namespace mozilla{
 void InitLateWriteChecks()
 {
   nsCOMPtr<nsIFile> mozFile;
   NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR, getter_AddRefs(mozFile));
   if (mozFile) {
     nsAutoCString nativePath;
     nsresult rv = mozFile->GetNativePath(nativePath);
     if (NS_SUCCEEDED(rv) && nativePath.get()) {
       sLateWriteObserver = new LateWriteObserver(nativePath.get());
     }
   }
 }
 void BeginLateWriteChecks()
 {
   if (sLateWriteObserver) {
     IOInterposer::Register(
       IOInterposeObserver::OpWriteFSync,
       sLateWriteObserver
     );
   }
 }
 void StopLateWriteChecks()
 {
   if (sLateWriteObserver) {
     IOInterposer::Unregister(
       IOInterposeObserver::OpAll,
       sLateWriteObserver
     );
     // Deallocation would not be thread-safe, and StopLateWriteChecks() is
     // called at shutdown and only in special cases.
     // sLateWriteObserver = nullptr;
   }
 }
 } // namespace mozilla

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xpcom/build/LateWriteChecks.cpp@b8a032363ba2 (annotated)

xpcom/build/LateWriteChecks.cpp