Add lz4 decompress/compress routines
During OTA generation, we decompress blobs on disk using lz4, and
perform diffing on the decompressed blobs. This is known to help OTA
size a lot. This CL adds decompression routines, following CLs will
start to actually call these routines.
Test: th
Bug: 206729162
Change-Id: Ifee87220e95740cb73a68ef84935c1cbb6a78666
diff --git a/lz4diff/lz4diff_compress_unittest.cc b/lz4diff/lz4diff_compress_unittest.cc
new file mode 100644
index 0000000..b4b56d2
--- /dev/null
+++ b/lz4diff/lz4diff_compress_unittest.cc
@@ -0,0 +1,117 @@
+//
+// 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 <unistd.h>
+
+#include <algorithm>
+#include <mutex>
+#include <string>
+#include <vector>
+
+#include <base/format_macros.h>
+#include <base/logging.h>
+#include <base/strings/string_number_conversions.h>
+#include <base/strings/string_util.h>
+#include <base/strings/stringprintf.h>
+#include <gtest/gtest.h>
+#include <erofs/internal.h>
+#include <erofs/io.h>
+
+#include "update_engine/common/test_utils.h"
+#include "update_engine/common/utils.h"
+#include "update_engine/lz4diff/lz4diff_compress.h"
+#include "update_engine/payload_generator/delta_diff_generator.h"
+#include "update_engine/payload_generator/erofs_filesystem.h"
+#include "update_engine/payload_generator/extent_utils.h"
+
+using std::string;
+using std::vector;
+
+namespace chromeos_update_engine {
+
+namespace {
+
+static void ExtractErofsImage(const char* erofs_image,
+ const char* inode_path,
+ Blob* output) {
+ // EROFS has plenty of global variable usage. Protect calls to EROFS APIs with
+ // global mutex.
+ // TODO(b/202784930) Replace erofs-utils with a cleaner and more C++ friendly
+ // library. (Or turn erofs-utils into one)
+ static std::mutex mutex;
+ std::lock_guard lock(mutex);
+ auto err = dev_open_ro(erofs_image);
+ ASSERT_EQ(err, 0);
+ DEFER { dev_close(); };
+
+ err = erofs_read_superblock();
+ ASSERT_EQ(err, 0);
+ struct erofs_inode inode;
+ err = erofs_ilookup(inode_path, &inode);
+ ASSERT_EQ(err, 0);
+ output->resize(inode.i_size);
+ err = erofs_pread(&inode,
+ reinterpret_cast<char*>(output->data()),
+ output->size(),
+ 0 /* offset */);
+ ASSERT_EQ(err, 0);
+}
+
+class Lz4diffCompressTest : public ::testing::Test {};
+
+using test_utils::GetBuildArtifactsPath;
+
+// This test parses the sample images generated during build time with the
+// "generate_image.sh" script. The expected conditions of each file in these
+// images is encoded in the file name, as defined in the mentioned script.
+TEST_F(Lz4diffCompressTest, ExtractElfBinary) {
+ const auto build_path = GetBuildArtifactsPath("gen/erofs.img");
+ auto fs = ErofsFilesystem::CreateFromFile(build_path);
+ ASSERT_NE(fs, nullptr);
+ ASSERT_EQ(kBlockSize, fs->GetBlockSize());
+
+ vector<ErofsFilesystem::File> files;
+ ASSERT_TRUE(fs->GetFiles(&files));
+
+ const auto it =
+ std::find_if(files.begin(), files.end(), [](const auto& file) {
+ return file.name == "/delta_generator";
+ });
+ ASSERT_NE(it, files.end())
+ << "There should be a delta_generator entry in gen/erofs.img. Is the "
+ "generate_test_erofs_imgages.sh script implemented wrong?";
+
+ const auto delta_generator = *it;
+ Blob expected_blob;
+ ASSERT_NO_FATAL_FAILURE(ExtractErofsImage(
+ build_path.c_str(), "/delta_generator", &expected_blob));
+ Blob compressed_blob;
+ ASSERT_TRUE(utils::ReadExtents(
+ build_path, delta_generator.extents, &compressed_blob, kBlockSize));
+ auto decompressed_blob = TryDecompressBlob(
+ compressed_blob,
+ delta_generator.compressed_file_info.blocks,
+ delta_generator.compressed_file_info.zero_padding_enabled);
+ ASSERT_GT(decompressed_blob.size(), 0UL);
+ ASSERT_GE(decompressed_blob.size(),
+ static_cast<size_t>(delta_generator.file_stat.st_size));
+ decompressed_blob.resize(delta_generator.file_stat.st_size);
+ ASSERT_EQ(decompressed_blob, expected_blob);
+}
+
+} // namespace
+
+} // namespace chromeos_update_engine