ipc/glue/CrossProcessMutex_windows.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include <windows.h>
   8
   9 #include "base/process_util.h"
  10 #include "CrossProcessMutex.h"
  11 #include "nsDebug.h"
  12 #include "nsISupportsImpl.h"
  13 #include "ProtocolUtils.h"
  14
  15 using base::GetCurrentProcessHandle;
  16 using base::ProcessHandle;
  17
  18 namespace mozilla {
  19
  20 CrossProcessMutex::CrossProcessMutex(const char*) {
  21   // We explicitly share this using DuplicateHandle, we do -not- want this to
  22   // be inherited by child processes by default! So no security attributes are
  23   // given.
  24   mMutex = ::CreateMutexA(nullptr, FALSE, nullptr);
  25   if (!mMutex) {
  26     MOZ_CRASH("This shouldn't happen - failed to create mutex!");
  27   }
  28   MOZ_COUNT_CTOR(CrossProcessMutex);
  29 }
  30
  31 CrossProcessMutex::CrossProcessMutex(CrossProcessMutexHandle aHandle) {
  32   DWORD flags;
  33   if (!::GetHandleInformation(aHandle.get(), &flags)) {
  34     MOZ_CRASH("Attempt to construct a mutex from an invalid handle!");
  35   }
  36   mMutex = aHandle.release();
  37   MOZ_COUNT_CTOR(CrossProcessMutex);
  38 }
  39
  40 CrossProcessMutex::~CrossProcessMutex() {
  41   NS_ASSERTION(mMutex, "Improper construction of mutex or double free.");
  42   ::CloseHandle(mMutex);
  43   MOZ_COUNT_DTOR(CrossProcessMutex);
  44 }
  45
  46 void CrossProcessMutex::Lock() {
  47   NS_ASSERTION(mMutex, "Improper construction of mutex.");
  48   ::WaitForSingleObject(mMutex, INFINITE);
  49 }
  50
  51 void CrossProcessMutex::Unlock() {
  52   NS_ASSERTION(mMutex, "Improper construction of mutex.");
  53   ::ReleaseMutex(mMutex);
  54 }
  55
  56 CrossProcessMutexHandle CrossProcessMutex::CloneHandle() {
  57   HANDLE newHandle;
  58   if (!::DuplicateHandle(GetCurrentProcess(), mMutex, GetCurrentProcess(),
  59                          &newHandle, 0, false, DUPLICATE_SAME_ACCESS)) {
  60     return nullptr;
  61   }
  62   return mozilla::UniqueFileHandle(newHandle);
  63 }
  64
  65 }  // namespace mozilla