ipc/glue/CrossProcessMutex_windows.cpp
author Noemi Erli <nerli@mozilla.com>
Tue, 18 Jan 2022 17:41:19 +0200
changeset 604772 310661795ca22ab62de923ce9fc3b36850e6d72d
parent 600038 d95312302ea3b6037196c61b0d0d7e8f4ce285e2
permissions -rw-r--r--
Merge autoland to mozilla-central. a=merge

/* -*- 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 <windows.h>

#include "base/process_util.h"
#include "CrossProcessMutex.h"
#include "nsDebug.h"
#include "nsISupportsImpl.h"
#include "ProtocolUtils.h"

using base::GetCurrentProcessHandle;
using base::ProcessHandle;

namespace mozilla {

CrossProcessMutex::CrossProcessMutex(const char*) {
  // We explicitly share this using DuplicateHandle, we do -not- want this to
  // be inherited by child processes by default! So no security attributes are
  // given.
  mMutex = ::CreateMutexA(nullptr, FALSE, nullptr);
  if (!mMutex) {
    MOZ_CRASH("This shouldn't happen - failed to create mutex!");
  }
  MOZ_COUNT_CTOR(CrossProcessMutex);
}

CrossProcessMutex::CrossProcessMutex(CrossProcessMutexHandle aHandle) {
  DWORD flags;
  if (!::GetHandleInformation(aHandle.get(), &flags)) {
    MOZ_CRASH("Attempt to construct a mutex from an invalid handle!");
  }
  mMutex = aHandle.release();
  MOZ_COUNT_CTOR(CrossProcessMutex);
}

CrossProcessMutex::~CrossProcessMutex() {
  NS_ASSERTION(mMutex, "Improper construction of mutex or double free.");
  ::CloseHandle(mMutex);
  MOZ_COUNT_DTOR(CrossProcessMutex);
}

void CrossProcessMutex::Lock() {
  NS_ASSERTION(mMutex, "Improper construction of mutex.");
  ::WaitForSingleObject(mMutex, INFINITE);
}

void CrossProcessMutex::Unlock() {
  NS_ASSERTION(mMutex, "Improper construction of mutex.");
  ::ReleaseMutex(mMutex);
}

CrossProcessMutexHandle CrossProcessMutex::CloneHandle() {
  HANDLE newHandle;
  if (!::DuplicateHandle(GetCurrentProcess(), mMutex, GetCurrentProcess(),
                         &newHandle, 0, false, DUPLICATE_SAME_ACCESS)) {
    return nullptr;
  }
  return mozilla::UniqueFileHandle(newHandle);
}

}  // namespace mozilla