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comparison: mozglue/linker/SeekableZStream.h
mozglue/linker/SeekableZStream.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:3405d29eff6d |
|---|---|
| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 3 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 #ifndef SeekableZStream_h | |
| 6 #define SeekableZStream_h | |
| 7 | |
| 8 #include "Zip.h" | |
| 9 | |
| 10 /** | |
| 11 * Seekable compressed stream are created by splitting the original | |
| 12 * decompressed data in small chunks and compress these chunks | |
| 13 * individually. | |
| 14 * | |
| 15 * The seekable compressed file format consists in a header defined below, | |
| 16 * followed by a table of 32-bits words containing the offsets for each | |
| 17 * individual compressed chunk, then followed by the compressed chunks. | |
| 18 */ | |
| 19 | |
| 20 #pragma pack(1) | |
| 21 struct SeekableZStreamHeader: public Zip::SignedEntity<SeekableZStreamHeader> | |
| 22 { | |
| 23 SeekableZStreamHeader() | |
| 24 : Zip::SignedEntity<SeekableZStreamHeader>(magic) | |
| 25 , totalSize(0), chunkSize(0), dictSize(0), nChunks(0), lastChunkSize(0) | |
| 26 , windowBits(0), filter(0) { } | |
| 27 | |
| 28 /* Reuse Zip::SignedEntity to handle the magic number used in the Seekable | |
| 29 * ZStream file format. The magic number is "SeZz". */ | |
| 30 static const uint32_t magic = 0x7a5a6553; | |
| 31 | |
| 32 /* Total size of the stream, including the 4 magic bytes. */ | |
| 33 le_uint32 totalSize; | |
| 34 | |
| 35 /* Chunk size */ | |
| 36 le_uint16 chunkSize; | |
| 37 | |
| 38 /* Size of the dictionary */ | |
| 39 le_uint16 dictSize; | |
| 40 | |
| 41 /* Number of chunks */ | |
| 42 le_uint32 nChunks; | |
| 43 | |
| 44 /* Size of last chunk (> 0, <= Chunk size) */ | |
| 45 le_uint16 lastChunkSize; | |
| 46 | |
| 47 /* windowBits value used when deflating */ | |
| 48 signed char windowBits; | |
| 49 | |
| 50 /* Filter Id */ | |
| 51 unsigned char filter; | |
| 52 }; | |
| 53 #pragma pack() | |
| 54 | |
| 55 static_assert(sizeof(SeekableZStreamHeader) == 5 * 4, | |
| 56 "SeekableZStreamHeader should be 5 32-bits words"); | |
| 57 | |
| 58 /** | |
| 59 * Helper class used to decompress Seekable ZStreams. | |
| 60 */ | |
| 61 class SeekableZStream { | |
| 62 public: | |
| 63 /* Initialize from the given buffer. Returns whether initialization | |
| 64 * succeeded (true) or failed (false). */ | |
| 65 bool Init(const void *buf, size_t length); | |
| 66 | |
| 67 /* Decompresses starting from the given chunk. The decompressed data is | |
| 68 * stored at the given location. The given length, in bytes, indicates | |
| 69 * how much data to decompress. If length is 0, then exactly one chunk | |
| 70 * is decompressed. | |
| 71 * Returns whether decompression succeeded (true) or failed (false). */ | |
| 72 bool Decompress(void *where, size_t chunk, size_t length = 0); | |
| 73 | |
| 74 /* Decompresses the given chunk at the given address. If a length is given, | |
| 75 * only decompresses that amount of data instead of the entire chunk. | |
| 76 * Returns whether decompression succeeded (true) or failed (false). */ | |
| 77 bool DecompressChunk(void *where, size_t chunk, size_t length = 0); | |
| 78 | |
| 79 /* Returns the uncompressed size of the complete zstream */ | |
| 80 const size_t GetUncompressedSize() const | |
| 81 { | |
| 82 return (offsetTable.numElements() - 1) * chunkSize + lastChunkSize; | |
| 83 } | |
| 84 | |
| 85 /* Returns the chunk size of the given chunk */ | |
| 86 const size_t GetChunkSize(size_t chunk = 0) const { | |
| 87 return (chunk == offsetTable.numElements() - 1) ? lastChunkSize : chunkSize; | |
| 88 } | |
| 89 | |
| 90 /* Returns the number of chunks */ | |
| 91 const size_t GetChunksNum() const { | |
| 92 return offsetTable.numElements(); | |
| 93 } | |
| 94 | |
| 95 /** | |
| 96 * Filters used to improve compression rate. | |
| 97 */ | |
| 98 enum FilterDirection { | |
| 99 FILTER, | |
| 100 UNFILTER | |
| 101 }; | |
| 102 typedef void (*ZStreamFilter)(off_t, FilterDirection, | |
| 103 unsigned char *, size_t); | |
| 104 | |
| 105 enum FilterId { | |
| 106 NONE, | |
| 107 BCJ_THUMB, | |
| 108 BCJ_ARM, | |
| 109 BCJ_X86, | |
| 110 FILTER_MAX | |
| 111 }; | |
| 112 static ZStreamFilter GetFilter(FilterId id); | |
| 113 | |
| 114 static ZStreamFilter GetFilter(uint16_t id) { | |
| 115 return GetFilter(static_cast<FilterId>(id)); | |
| 116 } | |
| 117 | |
| 118 private: | |
| 119 /* RAW Seekable SZtream buffer */ | |
| 120 const unsigned char *buffer; | |
| 121 | |
| 122 /* Total size of the stream, including the 4 magic bytes. */ | |
| 123 uint32_t totalSize; | |
| 124 | |
| 125 /* Chunk size */ | |
| 126 uint32_t chunkSize; | |
| 127 | |
| 128 /* Size of last chunk (> 0, <= Chunk size) */ | |
| 129 uint32_t lastChunkSize; | |
| 130 | |
| 131 /* windowBits value used when deflating */ | |
| 132 int windowBits; | |
| 133 | |
| 134 /* Offsets table */ | |
| 135 Array<le_uint32> offsetTable; | |
| 136 | |
| 137 /* Filter */ | |
| 138 ZStreamFilter filter; | |
| 139 | |
| 140 /* Deflate dictionary */ | |
| 141 Array<unsigned char> dictionary; | |
| 142 }; | |
| 143 | |
| 144 inline void | |
| 145 operator++(SeekableZStream::FilterId &other) | |
| 146 { | |
| 147 const int orig = static_cast<int>(other); | |
| 148 other = static_cast<SeekableZStream::FilterId>(orig + 1); | |
| 149 } | |
| 150 | |
| 151 #endif /* SeekableZStream_h */ |
