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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 <fcntl.h>
#include <sys/mman.h>
#include "base/logging.h"
#include "base/string_util.h"
namespace base {
namespace {
// Paranoia. Semaphores and shared memory segments should live in different
// namespaces, but who knows what's out there.
const char kSemaphoreSuffix[] = "-sem";
}
SharedMemory::SharedMemory()
: mapped_file_(-1),
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_(handle),
memory_(NULL),
read_only_(read_only),
max_size_(0),
lock_(NULL) {
// We don't handle this case yet (note the ignored parameter); let's die if
// someone comes calling.
NOTREACHED();
}
SharedMemory::~SharedMemory() {
Close();
if (lock_ != NULL)
sem_close(lock_);
}
bool SharedMemory::Create(const std::wstring &name, bool read_only,
bool open_existing, size_t size) {
read_only_ = read_only;
int posix_flags = 0;
posix_flags |= read_only ? O_RDONLY : O_RDWR;
if (!open_existing || mapped_file_ <= 0)
posix_flags |= O_CREAT;
if (!CreateOrOpen(name, posix_flags))
return false;
if (ftruncate(mapped_file_, size) != 0) {
Close();
return false;
}
max_size_ = size;
return true;
}
bool SharedMemory::Open(const std::wstring &name, bool read_only) {
read_only_ = read_only;
int posix_flags = 0;
posix_flags |= read_only ? O_RDONLY : O_RDWR;
return CreateOrOpen(name, posix_flags);
}
bool SharedMemory::CreateOrOpen(const std::wstring &name, int posix_flags) {
DCHECK(mapped_file_ == -1);
name_ = L"/" + name;
mode_t posix_mode = S_IRUSR | S_IWUSR; // owner read/write
std::string posix_name(WideToUTF8(name_));
mapped_file_ = shm_open(posix_name.c_str(), posix_flags, posix_mode);
if (mapped_file_ < 0)
return false;
posix_name += kSemaphoreSuffix;
lock_ = sem_open(posix_name.c_str(), O_CREAT, posix_mode, 1);
if (lock_ == SEM_FAILED) {
close(mapped_file_);
mapped_file_ = -1;
shm_unlink(posix_name.c_str());
lock_ = NULL;
return false;
}
return true;
}
bool SharedMemory::Map(size_t bytes) {
if (mapped_file_ == -1)
return false;
memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
MAP_SHARED, mapped_file_, 0);
if (memory_)
max_size_ = bytes;
return (memory_ != NULL);
}
bool SharedMemory::Unmap() {
if (memory_ == NULL)
return false;
munmap(memory_, max_size_);
memory_ = NULL;
max_size_ = 0;
return true;
}
bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
SharedMemoryHandle *new_handle,
bool close_self) {
*new_handle = 0;
// TODO(awalker): figure out if we need this, and do the appropriate
// VM magic if so.
return false;
}
void SharedMemory::Close() {
if (memory_ != NULL) {
munmap(memory_, max_size_);
memory_ = NULL;
max_size_ = 0;
}
std::string posix_name(WideToUTF8(name_));
if (mapped_file_ > 0) {
close(mapped_file_);
shm_unlink(posix_name.c_str());
mapped_file_ = -1;
}
if (lock_) {
posix_name += kSemaphoreSuffix;
sem_unlink(posix_name.c_str());
lock_ = NULL;
}
}
void SharedMemory::Lock() {
DCHECK(lock_ != NULL);
sem_wait(lock_);
}
void SharedMemory::Unlock() {
DCHECK(lock_ != NULL);
sem_post(lock_);
}
} // namespace base
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