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139 lines
3.3 KiB
C++
139 lines
3.3 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/memory/shared_memory.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <stddef.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <limits>
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#include "base/logging.h"
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#include "base/memory/shared_memory_tracker.h"
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namespace base {
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SharedMemory::SharedMemory()
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: mapped_size_(0), memory_(NULL), read_only_(false), requested_size_(0) {}
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SharedMemory::SharedMemory(const SharedMemoryHandle& handle, bool read_only)
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: shm_(handle),
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mapped_size_(0),
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memory_(NULL),
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read_only_(read_only),
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requested_size_(0) {}
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SharedMemory::~SharedMemory() {
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Unmap();
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Close();
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}
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// static
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bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
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return handle.IsValid();
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}
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// static
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void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
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DCHECK(handle.IsValid());
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handle.Close();
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}
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// static
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SharedMemoryHandle SharedMemory::DuplicateHandle(
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const SharedMemoryHandle& handle) {
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return handle.Duplicate();
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}
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bool SharedMemory::CreateAndMapAnonymous(size_t size) {
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// Untrusted code can't create descriptors or handles.
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return false;
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}
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bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
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// Untrusted code can't create descriptors or handles.
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return false;
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}
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bool SharedMemory::Delete(const std::string& name) {
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return false;
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}
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bool SharedMemory::Open(const std::string& name, bool read_only) {
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return false;
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}
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bool SharedMemory::MapAt(off_t offset, size_t bytes) {
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if (!shm_.IsValid())
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return false;
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if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
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return false;
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if (memory_)
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return false;
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memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
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MAP_SHARED, shm_.GetHandle(), offset);
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bool mmap_succeeded = memory_ != MAP_FAILED && memory_ != NULL;
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if (mmap_succeeded) {
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mapped_size_ = bytes;
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DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
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(SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
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mapped_id_ = shm_.GetGUID();
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SharedMemoryTracker::GetInstance()->IncrementMemoryUsage(*this);
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} else {
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memory_ = NULL;
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}
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return mmap_succeeded;
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}
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bool SharedMemory::Unmap() {
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if (memory_ == NULL)
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return false;
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SharedMemoryTracker::GetInstance()->DecrementMemoryUsage(*this);
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if (munmap(memory_, mapped_size_) < 0)
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DPLOG(ERROR) << "munmap";
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memory_ = NULL;
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mapped_size_ = 0;
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mapped_id_ = UnguessableToken();
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return true;
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}
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SharedMemoryHandle SharedMemory::handle() const {
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SharedMemoryHandle handle_copy = shm_;
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handle_copy.SetOwnershipPassesToIPC(false);
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return handle_copy;
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}
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SharedMemoryHandle SharedMemory::TakeHandle() {
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SharedMemoryHandle handle_copy = shm_;
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handle_copy.SetOwnershipPassesToIPC(true);
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Unmap();
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shm_ = SharedMemoryHandle();
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return handle_copy;
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}
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void SharedMemory::Close() {
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if (shm_.IsValid()) {
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shm_.Close();
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shm_ = SharedMemoryHandle();
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}
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}
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SharedMemoryHandle SharedMemory::GetReadOnlyHandle() const {
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// Untrusted code can't create descriptors or handles, which is needed to
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// drop permissions.
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return SharedMemoryHandle();
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}
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} // namespace base
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