| /* |
| * Copyright (C) 2021 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 "microdroid/metadata.h" |
| |
| #include <android-base/endian.h> |
| #include <android-base/file.h> |
| |
| using android::base::ErrnoError; |
| using android::base::Error; |
| using android::base::Result; |
| |
| namespace android { |
| namespace microdroid { |
| |
| Result<Metadata> ReadMetadata(const std::string& path) { |
| std::string content; |
| if (!base::ReadFileToString(path, &content)) { |
| return ErrnoError() << "Failed to read " << path; |
| } |
| |
| // read length prefix (4-byte, big-endian) |
| uint32_t size; |
| const size_t length_prefix_bytes = sizeof(size); |
| if (content.size() < length_prefix_bytes) { |
| return Error() << "Invalid metadata: size == " << content.size(); |
| } |
| size = be32toh(*reinterpret_cast<uint32_t*>(content.data())); |
| if (content.size() < length_prefix_bytes + size) { |
| return Error() << "Invalid metadata: size(" << size << ") mimatches to the content size(" |
| << content.size() - length_prefix_bytes << ")"; |
| } |
| content = content.substr(length_prefix_bytes, size); |
| |
| // parse content |
| Metadata metadata; |
| if (!metadata.ParseFromString(content)) { |
| return Error() << "Can't parse Metadata from " << path; |
| } |
| return metadata; |
| } |
| |
| Result<void> WriteMetadata(const Metadata& metadata, std::ostream& out) { |
| // prepare content |
| std::string content; |
| if (!metadata.SerializeToString(&content)) { |
| return Error() << "Failed to write protobuf."; |
| } |
| |
| // write length prefix (4-byte, big-endian) |
| uint32_t size = htobe32(static_cast<uint32_t>(content.size())); |
| out.write(reinterpret_cast<const char*>(&size), sizeof(size)); |
| |
| // write content |
| out << content; |
| |
| return {}; |
| } |
| |
| } // namespace microdroid |
| } // namespace android |