blob: 83754539f2ffc7e6d5f4313cf7e29e30efd2971a [file] [log] [blame]
// Copyright (c) 2011 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/memory/shared_memory.h"
#include <sys/mman.h>
#include "base/bits.h"
#include "base/logging.h"
#include "base/process/process_metrics.h"
#include "starboard/types.h"
#include "third_party/ashmem/ashmem.h"
namespace base {
// For Android, we use ashmem to implement SharedMemory. ashmem_create_region
// will automatically pin the region. We never explicitly call pin/unpin. When
// all the file descriptors from different processes associated with the region
// are closed, the memory buffer will go away.
bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
// Align size as required by ashmem_create_region() API documentation.
size_t rounded_size = bits::Align(options.size, GetPageSize());
if (rounded_size > static_cast<size_t>(std::numeric_limits<int>::max()))
return false;
// "name" is just a label in ashmem. It is visible in /proc/pid/maps.
int fd = ashmem_create_region(
options.name_deprecated ? options.name_deprecated->c_str() : "",
shm_ = SharedMemoryHandle::ImportHandle(fd, options.size);
if (!shm_.IsValid()) {
DLOG(ERROR) << "Shared memory creation failed";
return false;
int flags = PROT_READ | PROT_WRITE | (options.executable ? PROT_EXEC : 0);
int err = ashmem_set_prot_region(shm_.GetHandle(), flags);
if (err < 0) {
DLOG(ERROR) << "Error " << err << " when setting protection of ashmem";
return false;
requested_size_ = options.size;
return true;
bool SharedMemory::Delete(const std::string& name) {
// Like on Windows, this is intentionally returning true as ashmem will
// automatically releases the resource when all FDs on it are closed.
return true;
bool SharedMemory::Open(const std::string& name, bool read_only) {
// ashmem doesn't support name mapping
return false;
void SharedMemory::Close() {
if (shm_.IsValid()) {
shm_ = SharedMemoryHandle();
SharedMemoryHandle SharedMemory::GetReadOnlyHandle() const {
// There are no read-only Ashmem descriptors on Android.
// Instead, the protection mask is a property of the region itself.
SharedMemoryHandle handle = shm_.Duplicate();
return handle;
} // namespace base