Implement Xz compressor functions.
The new XzCompress() function is similar to BzipCompress() function but
uses the Xz compression algorithm.
This patch simplifies the unittests of the compressors and reuses the
client-side decompresor implementation instead of repeating the
implementation in the delta generator. This patch removes the unused
compression/decompression functions.
Bug: 24578399
TEST=Added unittests.
Change-Id: Id858112b50f4aa2597f184dc23a86af772f4f190
diff --git a/payload_generator/xz.h b/payload_generator/xz.h
new file mode 100644
index 0000000..6e0a26c
--- /dev/null
+++ b/payload_generator/xz.h
@@ -0,0 +1,34 @@
+//
+// Copyright (C) 2016 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_PAYLOAD_GENERATOR_XZ_H_
+#define UPDATE_ENGINE_PAYLOAD_GENERATOR_XZ_H_
+
+#include <brillo/secure_blob.h>
+
+namespace chromeos_update_engine {
+
+// Initialize the xz compression unit. Call once before any call to
+// XzCompress().
+void XzCompressInit();
+
+// Compresses the input buffer |in| into |out| with xz. The compressed stream
+// will be the equivalent of running xz -9 --check=none
+bool XzCompress(const brillo::Blob& in, brillo::Blob* out);
+
+} // namespace chromeos_update_engine
+
+#endif // UPDATE_ENGINE_PAYLOAD_GENERATOR_XZ_H_