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1 // Copyright (c) 2009 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2010 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__ | 5 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__ |
6 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__ | 6 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__ |
7 | 7 |
| 8 #include <string> |
| 9 #include <vector> |
8 #include "base/basictypes.h" | 10 #include "base/basictypes.h" |
| 11 #include "update_engine/graph_types.h" |
| 12 #include "update_engine/update_metadata.pb.h" |
| 13 |
| 14 // There is one function in DeltaDiffGenerator of importance to users |
| 15 // of the class: GenerateDeltaUpdateFile(). Before calling it, |
| 16 // the old and new images must be mounted. Call GenerateDeltaUpdateFile() |
| 17 // with both the mount-points of the images in addition to the paths of |
| 18 // the images (both old and new). A delta from old to new will be |
| 19 // generated and stored in output_path. |
9 | 20 |
10 namespace chromeos_update_engine { | 21 namespace chromeos_update_engine { |
11 | 22 |
12 class DeltaDiffGenerator { | 23 class DeltaDiffGenerator { |
| 24 public: |
| 25 // Represents a disk block on the install partition. |
| 26 struct Block { |
| 27 // During install, each block on the install partition will be written |
| 28 // and some may be read (in all likelihood, many will be read). |
| 29 // The reading and writing will be performed by InstallOperations, |
| 30 // each of which has a corresponding vertex in a graph. |
| 31 // A Block object tells which vertex will read or write this block |
| 32 // at install time. |
| 33 // Generally, there will be a vector of Block objects whose length |
| 34 // is the number of blocks on the install partition. |
| 35 Block() : reader(Vertex::kInvalidIndex), writer(Vertex::kInvalidIndex) {} |
| 36 Vertex::Index reader; |
| 37 Vertex::Index writer; |
| 38 }; |
| 39 |
| 40 // This is the only function that external users of the class should call. |
| 41 // old_image and new_image are paths to two image files. They should be |
| 42 // mounted read-only at paths old_root and new_root respectively. |
| 43 // output_path is the filename where the delta update should be written. |
| 44 // Returns true on success. |
| 45 static bool GenerateDeltaUpdateFile(const std::string& old_root, |
| 46 const std::string& old_image, |
| 47 const std::string& new_root, |
| 48 const std::string& new_image, |
| 49 const std::string& output_path); |
| 50 |
| 51 // These functions are public so that the unit tests can access them: |
| 52 |
| 53 // Reads old_filename (if it exists) and a new_filename and determines |
| 54 // the smallest way to encode this file for the diff. It stores |
| 55 // necessary data in out_data and fills in out_op. |
| 56 // If there's no change in old and new files, it creates a MOVE |
| 57 // operation. If there is a change, or the old file doesn't exist, |
| 58 // the smallest of REPLACE, REPLACE_BZ, or BSDIFF wins. |
| 59 // new_filename must contain at least one byte. |
| 60 // Returns true on success. |
| 61 static bool ReadFileToDiff(const std::string& old_filename, |
| 62 const std::string& new_filename, |
| 63 std::vector<char>* out_data, |
| 64 DeltaArchiveManifest_InstallOperation* out_op); |
| 65 |
| 66 // Modifies blocks read by 'op' so that any blocks referred to by |
| 67 // 'remove_extents' are replaced with blocks from 'replace_extents'. |
| 68 // 'remove_extents' and 'replace_extents' must be the same number of blocks. |
| 69 // Blocks will be substituted in the order listed in the vectors. |
| 70 // E.g. if 'op' reads blocks 1, 2, 3, 4, 5, 6, 7, 8, remove_extents |
| 71 // contains blocks 6, 2, 3, 5, and replace blocks contains |
| 72 // 12, 13, 14, 15, then op will be changed to read from: |
| 73 // 1, 13, 14, 4, 15, 12, 7, 8 |
| 74 static void SubstituteBlocks(DeltaArchiveManifest_InstallOperation* op, |
| 75 const std::vector<Extent>& remove_extents, |
| 76 const std::vector<Extent>& replace_extents); |
| 77 |
| 78 // Cuts 'edges' from 'graph' according to the AU algorithm. This means |
| 79 // for each edge A->B, remove the dependency that B occur before A. |
| 80 // Do this by creating a new operation X that copies from the blocks |
| 81 // specified by the edge's properties to temp space T. Modify B to read |
| 82 // from T rather than the blocks in the edge. Modify A to depend on X, |
| 83 // but not on B. Free space is found by looking in 'blocks'. |
| 84 // Returns true on success. |
| 85 static bool CutEdges(Graph* graph, |
| 86 const std::vector<Block>& blocks, |
| 87 const std::set<Edge>& edges); |
| 88 |
| 89 // Stores all Extents in 'extents' into 'out'. |
| 90 static void StoreExtents(std::vector<Extent>& extents, |
| 91 google::protobuf::RepeatedPtrField<Extent>* out); |
| 92 |
| 93 // Creates all the edges for the graph. Writers of a block point to |
| 94 // readers of the same block. This is because for an edge A->B, B |
| 95 // must complete before A executes. |
| 96 static void CreateEdges(Graph* graph, const std::vector<Block>& blocks); |
| 97 |
| 98 // Install operations in the manifest may reference data blobs, which |
| 99 // are in data_blobs_path. This function creates a new data blobs file |
| 100 // with the data blobs in the same order as the referencing install |
| 101 // operations in the manifest. E.g. if manifest[0] has a data blob |
| 102 // "X" at offset 1, manifest[1] has a data blob "Y" at offset 0, |
| 103 // and data_blobs_path's file contains "YX", new_data_blobs_path |
| 104 // will set to be a file that contains "XY". |
| 105 static bool ReorderDataBlobs(DeltaArchiveManifest* manifest, |
| 106 const std::string& data_blobs_path, |
| 107 const std::string& new_data_blobs_path); |
| 108 |
13 private: | 109 private: |
14 // This should never be constructed | 110 // This should never be constructed |
15 DISALLOW_IMPLICIT_CONSTRUCTORS(DeltaDiffGenerator); | 111 DISALLOW_IMPLICIT_CONSTRUCTORS(DeltaDiffGenerator); |
16 }; | 112 }; |
17 | 113 |
18 }; // namespace chromeos_update_engine | 114 }; // namespace chromeos_update_engine |
19 | 115 |
20 #endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__ | 116 #endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__ |
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