Add protobuf definition for lz4diff
We develope a new diffing format, called lz4diff. Since this diff format
need to store per-block compression information(which algorithm is used,
compressed size, etc), a new protobuf message is added to ease
development.
Test: th
Bug: 206729162
Change-Id: Ib05e865a6689f561cd00b28843c98d52d0714869
diff --git a/lz4diff/lz4diff_format.h b/lz4diff/lz4diff_format.h
new file mode 100644
index 0000000..5b5ce40
--- /dev/null
+++ b/lz4diff/lz4diff_format.h
@@ -0,0 +1,68 @@
+//
+// 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.
+//
+
+#ifndef UPDATE_ENGINE_LZ4DIFF_LZ4DIFF_FORMAT_H_
+#define UPDATE_ENGINE_LZ4DIFF_LZ4DIFF_FORMAT_H_
+
+#include <string_view>
+#include <vector>
+
+#include <lz4diff/lz4diff.pb.h>
+
+namespace chromeos_update_engine {
+
+using Blob = std::vector<unsigned char>;
+
+// Format of LZ4diff patch:
+// struct lz4diff_header {
+// char magic[8] = kLz4diffMagic;
+// uint32_t version;
+// uint32_t pb_header_size; // size of protobuf message
+// char pf_header[pb_header_size];
+// }
+
+constexpr std::string_view kLz4diffMagic = "LZ4DIFF";
+
+// 8 bytes magic + 4 bytes version + 4 bytes pb_header_size
+constexpr size_t kLz4diffHeaderSize = 8 + 4 + 4;
+
+constexpr uint32_t kLz4diffVersion = 1;
+
+struct CompressedBlock {
+ constexpr CompressedBlock() : CompressedBlock(0, 0, 0) {}
+ constexpr CompressedBlock(uint64_t offset,
+ uint64_t length,
+ uint64_t uncompressed_length)
+ : uncompressed_offset(offset),
+ compressed_length(length),
+ uncompressed_length(uncompressed_length) {}
+ constexpr bool IsCompressed() const noexcept {
+ return compressed_length < uncompressed_length;
+ }
+ uint64_t uncompressed_offset;
+ uint64_t compressed_length;
+ uint64_t uncompressed_length;
+};
+
+struct CompressedFile {
+ std::vector<CompressedBlock> blocks;
+ CompressionAlgorithm algo;
+ bool zero_padding_enabled{};
+};
+
+} // namespace chromeos_update_engine
+
+#endif