gecko-dev/ipc/glue/CrossProcessSemaphore_windows.cpp

81 lines
2.4 KiB
C++

/* -*- 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 "CrossProcessSemaphore.h"
#include "nsDebug.h"
#include "nsISupportsImpl.h"
#include "ProtocolUtils.h"
using base::GetCurrentProcessHandle;
using base::ProcessHandle;
namespace mozilla {
CrossProcessSemaphore::CrossProcessSemaphore(const char*, uint32_t aInitialValue)
{
// 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.
mSemaphore = ::CreateSemaphoreA(nullptr, aInitialValue, 0x7fffffff, nullptr);
if (!mSemaphore) {
MOZ_CRASH("This shouldn't happen - failed to create semaphore!");
}
MOZ_COUNT_CTOR(CrossProcessSemaphore);
}
CrossProcessSemaphore::CrossProcessSemaphore(CrossProcessSemaphoreHandle aHandle)
{
DWORD flags;
if (!::GetHandleInformation(aHandle, &flags)) {
MOZ_CRASH("Attempt to construct a semaphore from an invalid handle!");
}
mSemaphore = aHandle;
MOZ_COUNT_CTOR(CrossProcessSemaphore);
}
CrossProcessSemaphore::~CrossProcessSemaphore()
{
MOZ_ASSERT(mSemaphore, "Improper construction of semaphore or double free.");
::CloseHandle(mSemaphore);
MOZ_COUNT_DTOR(CrossProcessSemaphore);
}
bool
CrossProcessSemaphore::Wait(const Maybe<TimeDuration>& aWaitTime)
{
MOZ_ASSERT(mSemaphore, "Improper construction of semaphore.");
HRESULT hr = ::WaitForSingleObject(mSemaphore, aWaitTime.isSome() ?
aWaitTime->ToMilliseconds() :
INFINITE);
return hr == WAIT_OBJECT_0;
}
void
CrossProcessSemaphore::Signal()
{
MOZ_ASSERT(mSemaphore, "Improper construction of semaphore.");
::ReleaseSemaphore(mSemaphore, 1, nullptr);
}
CrossProcessSemaphoreHandle
CrossProcessSemaphore::ShareToProcess(base::ProcessId aTargetPid)
{
HANDLE newHandle;
bool succeeded = ipc::DuplicateHandle(mSemaphore, aTargetPid, &newHandle,
0, DUPLICATE_SAME_ACCESS);
if (!succeeded) {
return nullptr;
}
return newHandle;
}
}