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// Copyright 2017 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef SRC_EXTENT_STREAM_H_
#define SRC_EXTENT_STREAM_H_
#include <memory>
#include <vector>
#include "puffin/src/include/puffin/common.h"
#include "puffin/src/include/puffin/stream.h"
namespace puffin {
// A stream object that allows reading and writing into disk extents. This is
// only used in main.cc for puffin binary to allow puffpatch on a actual rootfs
// and kernel images.
class ExtentStream : public StreamInterface {
public:
// Creates a stream only for writing.
static UniqueStreamPtr CreateForWrite(UniqueStreamPtr stream,
const std::vector<ByteExtent>& extents);
// Creates a stream only for reading.
static UniqueStreamPtr CreateForRead(UniqueStreamPtr stream,
const std::vector<ByteExtent>& extents);
~ExtentStream() override = default;
bool GetSize(uint64_t* size) const override;
bool GetOffset(uint64_t* offset) const override;
bool Seek(uint64_t offset) override;
bool Read(void* buffer, size_t length) override;
bool Write(const void* buffer, size_t length) override;
bool Close() override;
private:
ExtentStream(UniqueStreamPtr stream,
const std::vector<ByteExtent>& extents,
bool is_for_write);
// Since both read and write operations are very similar in this class, this
// function acts as a common operation that does both write and read based on
// the nullability of |read_buffer| or |write_buffer|.
bool DoReadOrWrite(void* read_buffer,
const void* write_buffer,
size_t length);
// The underlying stream to read from and write into.
UniqueStreamPtr stream_;
std::vector<ByteExtent> extents_;
// The current |ByteExtent| that is being read from or write into.
std::vector<ByteExtent>::iterator cur_extent_;
// The current offset in the current |ByteExtent| |cur_extent_|.
uint64_t cur_extent_offset_;
// |True| if the stream is write only. |False| if the stream is read only.
bool is_for_write_;
// The size of the stream. It is actually the cumulative size of all the bytes
// in |extents_|.
uint64_t size_;
// The current offset.
uint64_t offset_;
// Used for proper and faster seeking.
std::vector<uint64_t> extents_upper_bounds_;
DISALLOW_COPY_AND_ASSIGN(ExtentStream);
};
} // namespace puffin
#endif // SRC_EXTENT_STREAM_H_
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