michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #include "base/shared_memory.h"
michael@0: 
michael@0: #include "base/logging.h"
michael@0: #include "base/win_util.h"
michael@0: #include "base/string_util.h"
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: SharedMemory::SharedMemory()
michael@0:     : mapped_file_(NULL),
michael@0:       memory_(NULL),
michael@0:       read_only_(false),
michael@0:       max_size_(0),
michael@0:       lock_(NULL) {
michael@0: }
michael@0: 
michael@0: SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
michael@0:     : mapped_file_(handle),
michael@0:       memory_(NULL),
michael@0:       read_only_(read_only),
michael@0:       max_size_(0),
michael@0:       lock_(NULL) {
michael@0: }
michael@0: 
michael@0: SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
michael@0:                            ProcessHandle process)
michael@0:     : mapped_file_(NULL),
michael@0:       memory_(NULL),
michael@0:       read_only_(read_only),
michael@0:       max_size_(0),
michael@0:       lock_(NULL) {
michael@0:   ::DuplicateHandle(process, handle,
michael@0:                     GetCurrentProcess(), &mapped_file_,
michael@0:                     STANDARD_RIGHTS_REQUIRED |
michael@0:                     (read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS),
michael@0:                     FALSE, 0);
michael@0: }
michael@0: 
michael@0: SharedMemory::~SharedMemory() {
michael@0:   Close();
michael@0:   if (lock_ != NULL)
michael@0:     CloseHandle(lock_);
michael@0: }
michael@0: 
michael@0: // static
michael@0: bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
michael@0:   return handle != NULL;
michael@0: }
michael@0: 
michael@0: // static
michael@0: SharedMemoryHandle SharedMemory::NULLHandle() {
michael@0:   return NULL;
michael@0: }
michael@0: 
michael@0: bool SharedMemory::Create(const std::string &cname, bool read_only,
michael@0:                           bool open_existing, size_t size) {
michael@0:   DCHECK(mapped_file_ == NULL);
michael@0:   std::wstring name = UTF8ToWide(cname);
michael@0:   name_ = name;
michael@0:   read_only_ = read_only;
michael@0:   mapped_file_ = CreateFileMapping(INVALID_HANDLE_VALUE, NULL,
michael@0:       read_only_ ? PAGE_READONLY : PAGE_READWRITE, 0, static_cast<DWORD>(size),
michael@0:       name.empty() ? NULL : name.c_str());
michael@0:   if (!mapped_file_)
michael@0:     return false;
michael@0: 
michael@0:   // Check if the shared memory pre-exists.
michael@0:   if (GetLastError() == ERROR_ALREADY_EXISTS && !open_existing) {
michael@0:     Close();
michael@0:     return false;
michael@0:   }
michael@0:   max_size_ = size;
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool SharedMemory::Delete(const std::wstring& name) {
michael@0:   // intentionally empty -- there is nothing for us to do on Windows.
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool SharedMemory::Open(const std::wstring &name, bool read_only) {
michael@0:   DCHECK(mapped_file_ == NULL);
michael@0: 
michael@0:   name_ = name;
michael@0:   read_only_ = read_only;
michael@0:   mapped_file_ = OpenFileMapping(
michael@0:       read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, false,
michael@0:       name.empty() ? NULL : name.c_str());
michael@0:   if (mapped_file_ != NULL) {
michael@0:     // Note: size_ is not set in this case.
michael@0:     return true;
michael@0:   }
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: bool SharedMemory::Map(size_t bytes) {
michael@0:   if (mapped_file_ == NULL)
michael@0:     return false;
michael@0: 
michael@0:   memory_ = MapViewOfFile(mapped_file_,
michael@0:       read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, 0, 0, bytes);
michael@0:   if (memory_ != NULL) {
michael@0:     return true;
michael@0:   }
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: bool SharedMemory::Unmap() {
michael@0:   if (memory_ == NULL)
michael@0:     return false;
michael@0: 
michael@0:   UnmapViewOfFile(memory_);
michael@0:   memory_ = NULL;
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
michael@0:                                         SharedMemoryHandle *new_handle,
michael@0:                                         bool close_self) {
michael@0:   *new_handle = 0;
michael@0:   DWORD access = STANDARD_RIGHTS_REQUIRED | FILE_MAP_READ;
michael@0:   DWORD options = 0;
michael@0:   HANDLE mapped_file = mapped_file_;
michael@0:   HANDLE result;
michael@0:   if (!read_only_)
michael@0:     access |= FILE_MAP_WRITE;
michael@0:   if (close_self) {
michael@0:     // DUPLICATE_CLOSE_SOURCE causes DuplicateHandle to close mapped_file.
michael@0:     options = DUPLICATE_CLOSE_SOURCE;
michael@0:     mapped_file_ = NULL;
michael@0:     Unmap();
michael@0:   }
michael@0: 
michael@0:   if (process == GetCurrentProcess() && close_self) {
michael@0:     *new_handle = mapped_file;
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   if (!DuplicateHandle(GetCurrentProcess(), mapped_file, process,
michael@0:       &result, access, FALSE, options))
michael@0:     return false;
michael@0:   *new_handle = result;
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: 
michael@0: void SharedMemory::Close() {
michael@0:   if (memory_ != NULL) {
michael@0:     UnmapViewOfFile(memory_);
michael@0:     memory_ = NULL;
michael@0:   }
michael@0: 
michael@0:   if (mapped_file_ != NULL) {
michael@0:     CloseHandle(mapped_file_);
michael@0:     mapped_file_ = NULL;
michael@0:   }
michael@0: }
michael@0: 
michael@0: void SharedMemory::Lock() {
michael@0:   if (lock_ == NULL) {
michael@0:     std::wstring name = name_;
michael@0:     name.append(L"lock");
michael@0:     lock_ = CreateMutex(NULL, FALSE, name.c_str());
michael@0:     DCHECK(lock_ != NULL);
michael@0:     if (lock_ == NULL) {
michael@0:       DLOG(ERROR) << "Could not create mutex" << GetLastError();
michael@0:       return;  // there is nothing good we can do here.
michael@0:     }
michael@0:   }
michael@0:   WaitForSingleObject(lock_, INFINITE);
michael@0: }
michael@0: 
michael@0: void SharedMemory::Unlock() {
michael@0:   DCHECK(lock_ != NULL);
michael@0:   ReleaseMutex(lock_);
michael@0: }
michael@0: 
michael@0: SharedMemoryHandle SharedMemory::handle() const {
michael@0:   return mapped_file_;
michael@0: }
michael@0: 
michael@0: }  // namespace base