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// Copyright 2017 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 <limits>
#include <zircon/process.h>
#include <zircon/rights.h>
#include <zircon/syscalls.h>
#include "base/bits.h"
#include "base/fuchsia/scoped_zx_handle.h"
#include "base/logging.h"
#include "base/memory/shared_memory_tracker.h"
#include "base/process/process_metrics.h"
namespace base {
SharedMemory::SharedMemory() {}
SharedMemory::SharedMemory(const SharedMemoryHandle& handle, bool read_only)
: shm_(handle), read_only_(read_only) {}
SharedMemory::~SharedMemory() {
Unmap();
Close();
}
// static
bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
return handle.IsValid();
}
// static
void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
DCHECK(handle.IsValid());
handle.Close();
}
// static
size_t SharedMemory::GetHandleLimit() {
// Duplicated from the internal Magenta kernel constant kMaxHandleCount
// (kernel/lib/zircon/zircon.cpp).
return 256 * 1024u;
}
bool SharedMemory::CreateAndMapAnonymous(size_t size) {
return CreateAnonymous(size) && Map(size);
}
bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
requested_size_ = options.size;
mapped_size_ = bits::Align(requested_size_, GetPageSize());
ScopedZxHandle vmo;
zx_status_t status = zx_vmo_create(mapped_size_, 0, vmo.receive());
if (status != ZX_OK) {
DLOG(ERROR) << "zx_vmo_create failed, status=" << status;
return false;
}
if (!options.executable) {
// If options.executable isn't set, drop that permission by replacement.
const int kNoExecFlags = ZX_DEFAULT_VMO_RIGHTS & ~ZX_RIGHT_EXECUTE;
ScopedZxHandle old_vmo(std::move(vmo));
status = zx_handle_replace(old_vmo.get(), kNoExecFlags, vmo.receive());
if (status != ZX_OK) {
DLOG(ERROR) << "zx_handle_replace() failed: "
<< zx_status_get_string(status);
return false;
}
ignore_result(old_vmo.release());
}
shm_ = SharedMemoryHandle(vmo.release(), mapped_size_,
UnguessableToken::Create());
return true;
}
bool SharedMemory::MapAt(off_t offset, size_t bytes) {
if (!shm_.IsValid())
return false;
if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
return false;
if (memory_)
return false;
int flags = ZX_VM_FLAG_PERM_READ;
if (!read_only_)
flags |= ZX_VM_FLAG_PERM_WRITE;
uintptr_t addr;
zx_status_t status = zx_vmar_map(zx_vmar_root_self(), 0, shm_.GetHandle(),
offset, bytes, flags, &addr);
if (status != ZX_OK) {
DLOG(ERROR) << "zx_vmar_map failed, status=" << status;
return false;
}
memory_ = reinterpret_cast<void*>(addr);
mapped_size_ = bytes;
mapped_id_ = shm_.GetGUID();
SharedMemoryTracker::GetInstance()->IncrementMemoryUsage(*this);
return true;
}
bool SharedMemory::Unmap() {
if (!memory_)
return false;
SharedMemoryTracker::GetInstance()->DecrementMemoryUsage(*this);
uintptr_t addr = reinterpret_cast<uintptr_t>(memory_);
zx_status_t status = zx_vmar_unmap(zx_vmar_root_self(), addr, mapped_size_);
if (status != ZX_OK) {
DLOG(ERROR) << "zx_vmar_unmap failed, status=" << status;
return false;
}
memory_ = nullptr;
mapped_id_ = UnguessableToken();
return true;
}
void SharedMemory::Close() {
if (shm_.IsValid()) {
shm_.Close();
shm_ = SharedMemoryHandle();
}
}
SharedMemoryHandle SharedMemory::handle() const {
return shm_;
}
SharedMemoryHandle SharedMemory::TakeHandle() {
SharedMemoryHandle handle(shm_);
handle.SetOwnershipPassesToIPC(true);
shm_ = SharedMemoryHandle();
memory_ = nullptr;
mapped_size_ = 0;
return handle;
}
SharedMemoryHandle SharedMemory::DuplicateHandle(
const SharedMemoryHandle& handle) {
return handle.Duplicate();
}
SharedMemoryHandle SharedMemory::GetReadOnlyHandle() const {
zx_handle_t duped_handle;
const int kNoWriteOrExec =
ZX_DEFAULT_VMO_RIGHTS &
~(ZX_RIGHT_WRITE | ZX_RIGHT_EXECUTE | ZX_RIGHT_SET_PROPERTY);
zx_status_t status =
zx_handle_duplicate(shm_.GetHandle(), kNoWriteOrExec, &duped_handle);
if (status != ZX_OK)
return SharedMemoryHandle();
SharedMemoryHandle handle(duped_handle, shm_.GetSize(), shm_.GetGUID());
handle.SetOwnershipPassesToIPC(true);
return handle;
}
} // namespace base
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