1// Copyright 2017 The Chromium OS Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef _BSDIFF_DIFF_ENCODER_H_
6#define _BSDIFF_DIFF_ENCODER_H_
7
8#include <stdint.h>
9
10#include "bsdiff/bz2_compressor.h"
11#include "bsdiff/patch_writer_interface.h"
12
13namespace bsdiff {
14
15// Helper class to encapsulate the diff and extra stream generation logic
16// derived from the old and new file buffers. Using this class is impossible to
17// produce an invalid or incomplete bsdiff patch, since it has checks in place
18// verifying its correct usage.
19
20class DiffEncoder {
21 public:
22  // Initialize the DiffEncoder with the old and new file buffers, as well as
23  // the path writer used. The |patch| will be initialized when calling Init().
24  DiffEncoder(PatchWriterInterface* patch,
25              const uint8_t* old_buf,
26              uint64_t old_size,
27              const uint8_t* new_buf,
28              uint64_t new_size)
29      : patch_(patch),
30        old_buf_(old_buf),
31        old_size_(old_size),
32        new_buf_(new_buf),
33        new_size_(new_size) {}
34
35  // Initialize the diff encoder and the underlying patch.
36  bool Init();
37
38  // Add a new control triplet entry to the patch. The |entry.diff_size| bytes
39  // for the diff stream and the |entry.extra_size| bytes for the extra stream
40  // will be computed and added to the corresponding streams in the patch.
41  // Returns whether the operation succeeded. The operation can fail if either
42  // the old or new files are referenced out of bounds.
43  bool AddControlEntry(const ControlEntry& entry);
44
45  // Finalize the patch writing process and close the underlying patch writer.
46  bool Close();
47
48 private:
49  // Pointer to the patch we are writing to.
50  PatchWriterInterface* patch_;
51
52  // Old and new file buffers.
53  const uint8_t* old_buf_;
54  uint64_t old_size_;
55  const uint8_t* new_buf_;
56  uint64_t new_size_;
57
58  // Bytes of the new_buf_ already written.
59  uint64_t written_output_{0};
60
61  // The current position in the old buf.
62  int64_t old_pos_{0};
63};
64
65}  // namespace bsdiff
66
67#endif  // _BSDIFF_DIFF_ENCODER_H_
68