1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "base/memory/shared_memory.h"
7 #include "base/logging.h"
8 #include "base/strings/utf_string_conversions.h"
12 // Returns the length of the memory section starting at the supplied address.
13 size_t GetMemorySectionSize(void* address) {
14 MEMORY_BASIC_INFORMATION memory_info;
15 if (!::VirtualQuery(address, &memory_info, sizeof(memory_info)))
17 return memory_info.RegionSize - (static_cast<char*>(address) -
18 static_cast<char*>(memory_info.AllocationBase));
25 SharedMemory::SharedMemory()
34 SharedMemory::SharedMemory(const std::wstring& name)
44 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
45 : mapped_file_(handle),
47 read_only_(read_only),
53 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
54 ProcessHandle process)
57 read_only_(read_only),
61 ::DuplicateHandle(process, handle,
62 GetCurrentProcess(), &mapped_file_,
63 read_only_ ? FILE_MAP_READ : FILE_MAP_READ |
68 SharedMemory::~SharedMemory() {
75 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
76 return handle != NULL;
80 SharedMemoryHandle SharedMemory::NULLHandle() {
85 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
86 DCHECK(handle != NULL);
87 ::CloseHandle(handle);
91 size_t SharedMemory::GetHandleLimit() {
92 // Rounded down from value reported here:
93 // http://blogs.technet.com/b/markrussinovich/archive/2009/09/29/3283844.aspx
94 return static_cast<size_t>(1 << 23);
97 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
98 return CreateAnonymous(size) && Map(size);
101 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
102 // TODO(bsy,sehr): crbug.com/210609 NaCl forces us to round up 64k here,
103 // wasting 32k per mapping on average.
104 static const size_t kSectionMask = 65536 - 1;
105 DCHECK(!options.executable);
106 DCHECK(!mapped_file_);
107 if (options.size == 0)
110 // Check maximum accounting for overflow.
112 static_cast<size_t>(std::numeric_limits<int>::max()) - kSectionMask)
115 size_t rounded_size = (options.size + kSectionMask) & ~kSectionMask;
116 name_ = ASCIIToWide(options.name == NULL ? "" : *options.name);
117 mapped_file_ = CreateFileMapping(INVALID_HANDLE_VALUE, NULL,
118 PAGE_READWRITE, 0, static_cast<DWORD>(rounded_size),
119 name_.empty() ? NULL : name_.c_str());
123 requested_size_ = options.size;
125 // Check if the shared memory pre-exists.
126 if (GetLastError() == ERROR_ALREADY_EXISTS) {
127 // If the file already existed, set requested_size_ to 0 to show that
128 // we don't know the size.
130 if (!options.open_existing) {
139 bool SharedMemory::Delete(const std::string& name) {
140 // intentionally empty -- there is nothing for us to do on Windows.
144 bool SharedMemory::Open(const std::string& name, bool read_only) {
145 DCHECK(!mapped_file_);
147 name_ = ASCIIToWide(name);
148 read_only_ = read_only;
149 mapped_file_ = OpenFileMapping(
150 read_only_ ? FILE_MAP_READ : FILE_MAP_READ | FILE_MAP_WRITE,
151 false, name_.empty() ? NULL : name_.c_str());
152 if (mapped_file_ != NULL) {
153 // Note: size_ is not set in this case.
159 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
160 if (mapped_file_ == NULL)
163 if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
166 memory_ = MapViewOfFile(mapped_file_,
167 read_only_ ? FILE_MAP_READ : FILE_MAP_READ |
169 static_cast<uint64>(offset) >> 32,
170 static_cast<DWORD>(offset),
172 if (memory_ != NULL) {
173 DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
174 (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
175 mapped_size_ = GetMemorySectionSize(memory_);
181 bool SharedMemory::Unmap() {
185 UnmapViewOfFile(memory_);
190 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
191 SharedMemoryHandle *new_handle,
194 DWORD access = FILE_MAP_READ;
196 HANDLE mapped_file = mapped_file_;
199 access |= FILE_MAP_WRITE;
201 // DUPLICATE_CLOSE_SOURCE causes DuplicateHandle to close mapped_file.
202 options = DUPLICATE_CLOSE_SOURCE;
207 if (process == GetCurrentProcess() && close_self) {
208 *new_handle = mapped_file;
212 if (!DuplicateHandle(GetCurrentProcess(), mapped_file, process,
213 &result, access, FALSE, options))
215 *new_handle = result;
220 void SharedMemory::Close() {
221 if (memory_ != NULL) {
222 UnmapViewOfFile(memory_);
226 if (mapped_file_ != NULL) {
227 CloseHandle(mapped_file_);
232 void SharedMemory::Lock() {
233 Lock(INFINITE, NULL);
236 bool SharedMemory::Lock(uint32 timeout_ms, SECURITY_ATTRIBUTES* sec_attr) {
238 std::wstring name = name_;
239 name.append(L"lock");
240 lock_ = CreateMutex(sec_attr, FALSE, name.c_str());
242 DPLOG(ERROR) << "Could not create mutex.";
243 return false; // there is nothing good we can do here.
246 DWORD result = WaitForSingleObject(lock_, timeout_ms);
248 // Return false for WAIT_ABANDONED, WAIT_TIMEOUT or WAIT_FAILED.
249 return (result == WAIT_OBJECT_0);
252 void SharedMemory::Unlock() {
253 DCHECK(lock_ != NULL);
257 SharedMemoryHandle SharedMemory::handle() const {