74 lines
2.3 KiB
C++
74 lines
2.3 KiB
C++
/*
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* Copyright (C) 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "microdroid/metadata.h"
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#include <android-base/endian.h>
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#include <android-base/file.h>
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using android::base::ErrnoError;
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using android::base::Error;
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using android::base::Result;
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namespace android {
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namespace microdroid {
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Result<Metadata> ReadMetadata(const std::string& path) {
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std::string content;
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if (!base::ReadFileToString(path, &content)) {
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return ErrnoError() << "Failed to read " << path;
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}
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// read length prefix (4-byte, big-endian)
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uint32_t size;
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const size_t length_prefix_bytes = sizeof(size);
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if (content.size() < length_prefix_bytes) {
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return Error() << "Invalid metadata: size == " << content.size();
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}
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size = be32toh(*reinterpret_cast<uint32_t*>(content.data()));
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if (content.size() < length_prefix_bytes + size) {
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return Error() << "Invalid metadata: size(" << size << ") mimatches to the content size("
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<< content.size() - length_prefix_bytes << ")";
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}
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content = content.substr(length_prefix_bytes, size);
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// parse content
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Metadata metadata;
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if (!metadata.ParseFromString(content)) {
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return Error() << "Can't parse Metadata from " << path;
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}
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return metadata;
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}
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Result<void> WriteMetadata(const Metadata& metadata, std::ostream& out) {
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// prepare content
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std::string content;
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if (!metadata.SerializeToString(&content)) {
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return Error() << "Failed to write protobuf.";
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}
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// write length prefix (4-byte, big-endian)
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uint32_t size = htobe32(static_cast<uint32_t>(content.size()));
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out.write(reinterpret_cast<const char*>(&size), sizeof(size));
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// write content
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out << content;
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return {};
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}
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} // namespace microdroid
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} // namespace android
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