blob: 05bc7ddfbe934987ae1c2832840f86ecf90feaa5 [file] [log] [blame]
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <errno.h>
#include <sys/mman.h>
#include <limits>
#include <cutils/ashmem.h>
#include <log/log.h>
#include <ui/BufferHubMetadata.h>
namespace android {
namespace {
static const int kAshmemProt = PROT_READ | PROT_WRITE;
} // namespace
using BufferHubDefs::kMetadataHeaderSize;
using BufferHubDefs::MetadataHeader;
/* static */
BufferHubMetadata BufferHubMetadata::create(size_t userMetadataSize) {
// The size the of metadata buffer is used as the "width" parameter during allocation. Thus it
// cannot overflow uint32_t.
if (userMetadataSize >= (std::numeric_limits<uint32_t>::max() - kMetadataHeaderSize)) {
ALOGE("BufferHubMetadata::Create: metadata size too big: %zu.", userMetadataSize);
return {};
}
const size_t metadataSize = userMetadataSize + kMetadataHeaderSize;
int fd = ashmem_create_region(/*name=*/"BufferHubMetadata", metadataSize);
if (fd < 0) {
ALOGE("BufferHubMetadata::Create: failed to create ashmem region.");
return {};
}
// Hand over the ownership of the fd to a unique_fd immediately after the successful
// return of ashmem_create_region. The ashmemFd is going to own the fd and to prevent fd
// leaks during error handling.
unique_fd ashmemFd{fd};
if (ashmem_set_prot_region(ashmemFd.get(), kAshmemProt) != 0) {
ALOGE("BufferHubMetadata::Create: failed to set protect region.");
return {};
}
return BufferHubMetadata::import(std::move(ashmemFd));
}
/* static */
BufferHubMetadata BufferHubMetadata::import(unique_fd ashmemFd) {
if (!ashmem_valid(ashmemFd.get())) {
ALOGE("BufferHubMetadata::Import: invalid ashmem fd.");
return {};
}
size_t metadataSize = static_cast<size_t>(ashmem_get_size_region(ashmemFd.get()));
size_t userMetadataSize = metadataSize - kMetadataHeaderSize;
// Note that here the buffer state is mapped from shared memory as an atomic object. The
// std::atomic's constructor will not be called so that the original value stored in the memory
// region can be preserved.
auto metadataHeader = static_cast<MetadataHeader*>(mmap(nullptr, metadataSize, kAshmemProt,
MAP_SHARED, ashmemFd.get(),
/*offset=*/0));
if (metadataHeader == nullptr) {
ALOGE("BufferHubMetadata::Import: failed to map region.");
return {};
}
return BufferHubMetadata(userMetadataSize, std::move(ashmemFd), metadataHeader);
}
BufferHubMetadata::BufferHubMetadata(size_t userMetadataSize, unique_fd ashmemFd,
MetadataHeader* metadataHeader)
: mUserMetadataSize(userMetadataSize),
mAshmemFd(std::move(ashmemFd)),
mMetadataHeader(metadataHeader) {}
BufferHubMetadata::~BufferHubMetadata() {
if (mMetadataHeader != nullptr) {
int ret = munmap(mMetadataHeader, metadataSize());
ALOGE_IF(ret != 0,
"BufferHubMetadata::~BufferHubMetadata: failed to unmap ashmem, error=%d.", errno);
mMetadataHeader = nullptr;
}
}
} // namespace android