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// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/shared_memory.h"
#include "base/logging.h"
#include "base/win_util.h"
SharedMemory::SharedMemory()
: mapped_file_(NULL),
memory_(NULL),
read_only_(false),
max_size_(0),
lock_(NULL) {
}
SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
: mapped_file_(handle),
memory_(NULL),
read_only_(read_only),
max_size_(0),
lock_(NULL) {
}
SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
ProcessHandle process)
: mapped_file_(NULL),
memory_(NULL),
read_only_(read_only),
max_size_(0),
lock_(NULL) {
::DuplicateHandle(process, handle,
GetCurrentProcess(), &mapped_file_,
STANDARD_RIGHTS_REQUIRED |
(read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS),
FALSE, 0);
}
SharedMemory::~SharedMemory() {
Close();
if (lock_ != NULL)
CloseHandle(lock_);
}
bool SharedMemory::Create(const std::wstring &name, bool read_only,
bool open_existing, size_t size) {
DCHECK(mapped_file_ == NULL);
name_ = name;
read_only_ = read_only;
mapped_file_ = CreateFileMapping(INVALID_HANDLE_VALUE, NULL,
read_only_ ? PAGE_READONLY : PAGE_READWRITE, 0, static_cast<DWORD>(size),
name.empty() ? NULL : name.c_str());
if (!mapped_file_)
return false;
// Check if the shared memory pre-exists.
if (GetLastError() == ERROR_ALREADY_EXISTS && !open_existing) {
Close();
return false;
}
max_size_ = size;
return true;
}
bool SharedMemory::Open(const std::wstring &name, bool read_only) {
DCHECK(mapped_file_ == NULL);
name_ = name;
read_only_ = read_only;
mapped_file_ = OpenFileMapping(
read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, false,
name.empty() ? NULL : name.c_str());
if (mapped_file_ != NULL) {
// Note: size_ is not set in this case.
return true;
}
return false;
}
bool SharedMemory::Map(size_t bytes) {
if (mapped_file_ == NULL)
return false;
memory_ = MapViewOfFile(mapped_file_,
read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, 0, 0, bytes);
if (memory_ != NULL) {
return true;
}
return false;
}
bool SharedMemory::Unmap() {
if (memory_ == NULL)
return false;
UnmapViewOfFile(memory_);
memory_ = NULL;
return true;
}
bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
SharedMemoryHandle *new_handle,
bool close_self) {
*new_handle = 0;
DWORD access = STANDARD_RIGHTS_REQUIRED | FILE_MAP_READ;
DWORD options = 0;
HANDLE mapped_file = mapped_file_;
HANDLE result;
if (!read_only_)
access |= FILE_MAP_WRITE;
if (close_self) {
// DUPLICATE_CLOSE_SOURCE causes DuplicateHandle to close mapped_file.
options = DUPLICATE_CLOSE_SOURCE;
mapped_file_ = NULL;
Unmap();
}
if (process == GetCurrentProcess() && close_self) {
*new_handle = mapped_file;
return true;
}
if (!DuplicateHandle(GetCurrentProcess(), mapped_file, process,
&result, access, FALSE, options))
return false;
*new_handle = result;
return true;
}
void SharedMemory::Close() {
if (memory_ != NULL) {
UnmapViewOfFile(memory_);
memory_ = NULL;
}
if (mapped_file_ != NULL) {
CloseHandle(mapped_file_);
mapped_file_ = NULL;
}
}
void SharedMemory::Lock() {
if (lock_ == NULL) {
std::wstring name = name_;
name.append(L"lock");
lock_ = CreateMutex(NULL, FALSE, name.c_str());
DCHECK(lock_ != NULL);
if (lock_ == NULL) {
DLOG(ERROR) << "Could not create mutex" << GetLastError();
return; // there is nothing good we can do here.
}
}
WaitForSingleObject(lock_, INFINITE);
}
void SharedMemory::Unlock() {
DCHECK(lock_ != NULL);
ReleaseMutex(lock_);
}
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