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

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

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

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

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

#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 "mozilla/Unused.h"

#include "nsAppDirectoryServiceDefs.h"

#include "nsDirectoryServiceUtils.h"

#include "nsLocalFile.h"

#include "nsPrintfCString.h"

#include "mozilla/StackWalk.h"

#include "plstr.h"

#include "prio.h"

#ifdef XP_WIN

#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"

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* aStream)

    : mFile(aStream)

  {

    MozillaRegisterDebugFILE(mFile);

  }

  void Printf(const char* aFormat, ...) MOZ_FORMAT_PRINTF(2, 3)

  {

    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());

    Unused << 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(uint32_t aFrameNumber, 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 final : public IOInterposeObserver

{

  using char_type = filesystem::Path::value_type;

public:

  explicit LateWriteObserver(const char_type* aProfileDirectory)

    : mProfileDirectory(NS_xstrdup(aProfileDirectory))

  {

  }

  ~LateWriteObserver()

  {

    free(mProfileDirectory);

    mProfileDirectory = nullptr;

  }

  void Observe(IOInterposeObserver::Observation& aObservation) override;

private:

  char_type* mProfileDirectory;

};

void

LateWriteObserver::Observe(IOInterposeObserver::Observation& aOb)

{

  // 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::CanRecordExtended()) {

    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;

  MozStackWalk(RecordStackWalker, /* skipFrames */ 0, /* maxFrames */ 0,

               &rawStack);

  Telemetry::ProcessedStack stack = Telemetry::GetStackAndModules(rawStack);

  nsTAutoString<char_type> nameAux(mProfileDirectory);

  nameAux.AppendLiteral(NS_SLASH "Telemetry.LateWriteTmpXXXXXX");

  char_type* name = nameAux.BeginWriting();

  // 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

    _wmktemp_s(char16ptr_t(name), NS_strlen(name) + 1);

    hFile = CreateFileW(char16ptr_t(name), GENERIC_WRITE, 0, nullptr,

                        CREATE_NEW, FILE_ATTRIBUTE_NORMAL, nullptr);

  } while (GetLastError() == ERROR_FILE_EXISTS);

  if (hFile == INVALID_HANDLE_VALUE) {

    MOZ_CRASH("Um, how did we get here?");

  }

  // http://support.microsoft.com/kb/139640

  int fd = _open_osfhandle((intptr_t)hFile, _O_APPEND);

  if (fd == -1) {

    MOZ_CRASH("Um, how did we get here?");

  }

  stream = _fdopen(fd, "w");

#else

  int fd = mkstemp(name);

  if (fd == -1) {

    MOZ_CRASH("mkstemp failed");

  }

  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.get(),

                      NS_ConvertUTF16toUTF8(module.mName).get());

  }

  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.

  nsAutoString finalName(NS_LITERAL_STRING("Telemetry.LateWriteFinal-"));

  for (int i = 0; i < 20; ++i) {

    finalName.AppendPrintf("%02x", sha1[i]);

  }

  RefPtr<nsLocalFile> file = new nsLocalFile(nameAux);

  file->RenameTo(nullptr, finalName);

}

/******************************* 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) {

    PathString nativePath = mozFile->NativePath();

    if (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