update_engine: Add ExtentReader
Currently Each operation in DeltaPerformer has the responsibility of
reading from the source device by itself. Adding an
ExtentReader (similar to ExtentWriter) aggregates all these
responsibilities on DeltaPerformer.source_fd_. This simplifies the
design as each operation does not need to invent is own open/read/close
etc. This specially will be used in conjunction with bspatch and puffin.
BUG=chromium:761138
TEST=FEATURES="test" emerge-amd64-generic update_engine;
Change-Id: I2c7a21a02bd1df06bbaa7ebf374a13f654768721
Reviewed-on: https://chromium-review.googlesource.com/651336
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>
diff --git a/payload_consumer/extent_reader.h b/payload_consumer/extent_reader.h
new file mode 100644
index 0000000..3f9e4c8
--- /dev/null
+++ b/payload_consumer/extent_reader.h
@@ -0,0 +1,82 @@
+//
+// Copyright (C) 2017 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_CONSUMER_EXTENT_READER_H_
+#define UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_READER_H_
+
+#include <vector>
+
+#include "update_engine/payload_consumer/file_descriptor.h"
+#include "update_engine/update_metadata.pb.h"
+
+namespace chromeos_update_engine {
+
+// ExtentReader is an abstract class with reads from a given file descriptor at
+// the extents given.
+class ExtentReader {
+ public:
+ virtual ~ExtentReader() = default;
+
+ // Initializes |ExtentReader|
+ virtual bool Init(FileDescriptorPtr fd,
+ const google::protobuf::RepeatedPtrField<Extent>& extents,
+ uint32_t block_size) = 0;
+
+ // Seeks to the given |offset| assuming all extents are concatenated together.
+ virtual bool Seek(uint64_t offset) = 0;
+
+ // Returns true on success.
+ virtual bool Read(void* buffer, size_t count) = 0;
+};
+
+// DirectExtentReader is probably the simplest ExtentReader implementation.
+// It reads the data directly from the extents.
+class DirectExtentReader : public ExtentReader {
+ public:
+ DirectExtentReader() = default;
+ ~DirectExtentReader() override = default;
+
+ bool Init(FileDescriptorPtr fd,
+ const google::protobuf::RepeatedPtrField<Extent>& extents,
+ uint32_t block_size) override;
+ bool Seek(uint64_t offset) override;
+ bool Read(void* bytes, size_t count) override;
+
+ private:
+ FileDescriptorPtr fd_{nullptr};
+ google::protobuf::RepeatedPtrField<Extent> extents_;
+ size_t block_size_{0};
+
+ // Current extent being read from |fd_|.
+ google::protobuf::RepeatedPtrField<Extent>::iterator cur_extent_;
+
+ // Bytes read from |cur_extent_| thus far.
+ uint64_t cur_extent_bytes_read_{0};
+
+ // Offset assuming all extents are concatenated.
+ uint64_t offset_{0};
+
+ // The accelaring upper bounds for |extents_| if we assume all extents are
+ // concatenated.
+ std::vector<uint64_t> extents_upper_bounds_;
+ uint64_t total_size_{0};
+
+ DISALLOW_COPY_AND_ASSIGN(DirectExtentReader);
+};
+
+} // namespace chromeos_update_engine
+
+#endif // UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_READER_H_