Implement VABCPartitionWriter
Test: treehugger
Change-Id: I7ec47adba0bc095879989b43ec642ea6a7852ab6
diff --git a/payload_consumer/snapshot_extent_writer.h b/payload_consumer/snapshot_extent_writer.h
new file mode 100644
index 0000000..43a8317
--- /dev/null
+++ b/payload_consumer/snapshot_extent_writer.h
@@ -0,0 +1,47 @@
+//
+// Copyright (C) 2020 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 <cstdint>
+#include <vector>
+
+#include <libsnapshot/cow_writer.h>
+
+#include "update_engine/payload_consumer/extent_writer.h"
+
+namespace chromeos_update_engine {
+class SnapshotExtentWriter : public chromeos_update_engine::ExtentWriter {
+ public:
+ explicit SnapshotExtentWriter(android::snapshot::ICowWriter* cow_writer);
+ ~SnapshotExtentWriter();
+ // Returns true on success.
+ bool Init(FileDescriptorPtr fd,
+ const google::protobuf::RepeatedPtrField<Extent>& extents,
+ uint32_t block_size) override;
+ // Returns true on success.
+ // This will construct a COW_REPLACE operation and forward it to CowWriter. It
+ // is important that caller does not perform SOURCE_COPY operation on this
+ // class, otherwise raw data will be stored. Caller should find ways to use
+ // COW_COPY whenever possible.
+ bool Write(const void* bytes, size_t count) override;
+
+ private:
+ // It's a non-owning pointer, because PartitionWriter owns the CowWruter. This
+ // allows us to use a single instance of CowWriter for all operations applied
+ // to the same partition.
+ [[maybe_unused]] android::snapshot::ICowWriter* cow_writer_;
+ [[maybe_unused]] google::protobuf::RepeatedPtrField<Extent> extents_;
+ [[maybe_unused]] std::vector<uint8_t> buffer_;
+};
+} // namespace chromeos_update_engine