| 1 | #ifndef SEEKABLE_H |
| 2 | #define SEEKABLE_H |
| 3 | |
| 4 | #if defined (__cplusplus) |
| 5 | extern "C" { |
| 6 | #endif |
| 7 | |
| 8 | #include <stdio.h> |
| 9 | #include "zstd.h" /* ZSTDLIB_API */ |
| 10 | |
| 11 | |
| 12 | #define ZSTD_seekTableFooterSize 9 |
| 13 | |
| 14 | #define ZSTD_SEEKABLE_MAGICNUMBER 0x8F92EAB1 |
| 15 | |
| 16 | #define ZSTD_SEEKABLE_MAXFRAMES 0x8000000U |
| 17 | |
| 18 | /* Limit maximum size to avoid potential issues storing the compressed size */ |
| 19 | #define ZSTD_SEEKABLE_MAX_FRAME_DECOMPRESSED_SIZE 0x40000000U |
| 20 | |
| 21 | /*-**************************************************************************** |
| 22 | * Seekable Format |
| 23 | * |
| 24 | * The seekable format splits the compressed data into a series of "frames", |
| 25 | * each compressed individually so that decompression of a section in the |
| 26 | * middle of an archive only requires zstd to decompress at most a frame's |
| 27 | * worth of extra data, instead of the entire archive. |
| 28 | ******************************************************************************/ |
| 29 | |
| 30 | typedef struct ZSTD_seekable_CStream_s ZSTD_seekable_CStream; |
| 31 | typedef struct ZSTD_seekable_s ZSTD_seekable; |
| 32 | typedef struct ZSTD_seekTable_s ZSTD_seekTable; |
| 33 | |
| 34 | /*-**************************************************************************** |
| 35 | * Seekable compression - HowTo |
| 36 | * A ZSTD_seekable_CStream object is required to tracking streaming operation. |
| 37 | * Use ZSTD_seekable_createCStream() and ZSTD_seekable_freeCStream() to create/ |
| 38 | * release resources. |
| 39 | * |
| 40 | * Streaming objects are reusable to avoid allocation and deallocation, |
| 41 | * to start a new compression operation call ZSTD_seekable_initCStream() on the |
| 42 | * compressor. |
| 43 | * |
| 44 | * Data streamed to the seekable compressor will automatically be split into |
| 45 | * frames of size `maxFrameSize` (provided in ZSTD_seekable_initCStream()), |
| 46 | * or if none is provided, will be cut off whenever ZSTD_seekable_endFrame() is |
| 47 | * called or when the default maximum frame size (2GB) is reached. |
| 48 | * |
| 49 | * Use ZSTD_seekable_initCStream() to initialize a ZSTD_seekable_CStream object |
| 50 | * for a new compression operation. |
| 51 | * - `maxFrameSize` indicates the size at which to automatically start a new |
| 52 | * seekable frame. |
| 53 | * `maxFrameSize == 0` implies the default maximum size. |
| 54 | * Smaller frame sizes allow faster decompression of small segments, |
| 55 | * since retrieving a single byte requires decompression of |
| 56 | * the full frame where the byte belongs. |
| 57 | * In general, size the frames to roughly correspond to |
| 58 | * the access granularity (when it's known). |
| 59 | * But small sizes also reduce compression ratio. |
| 60 | * Avoid really tiny frame sizes (< 1 KB), |
| 61 | * that would hurt compression ratio considerably. |
| 62 | * - `checksumFlag` indicates whether or not the seek table should include frame |
| 63 | * checksums on the uncompressed data for verification. |
| 64 | * @return : a size hint for input to provide for compression, or an error code |
| 65 | * checkable with ZSTD_isError() |
| 66 | * |
| 67 | * Use ZSTD_seekable_compressStream() repetitively to consume input stream. |
| 68 | * The function will automatically update both `pos` fields. |
| 69 | * Note that it may not consume the entire input, in which case `pos < size`, |
| 70 | * and it's up to the caller to present again remaining data. |
| 71 | * @return : a size hint, preferred nb of bytes to use as input for next |
| 72 | * function call or an error code, which can be tested using |
| 73 | * ZSTD_isError(). |
| 74 | * Note 1 : it's just a hint, to help latency a little, any other |
| 75 | * value will work fine. |
| 76 | * |
| 77 | * At any time, call ZSTD_seekable_endFrame() to end the current frame and |
| 78 | * start a new one. |
| 79 | * |
| 80 | * ZSTD_seekable_endStream() will end the current frame, and then write the seek |
| 81 | * table so that decompressors can efficiently find compressed frames. |
| 82 | * ZSTD_seekable_endStream() may return a number > 0 if it was unable to flush |
| 83 | * all the necessary data to `output`. In this case, it should be called again |
| 84 | * until all remaining data is flushed out and 0 is returned. |
| 85 | ******************************************************************************/ |
| 86 | |
| 87 | /*===== Seekable compressor management =====*/ |
| 88 | ZSTDLIB_API ZSTD_seekable_CStream* ZSTD_seekable_createCStream(void); |
| 89 | ZSTDLIB_API size_t ZSTD_seekable_freeCStream(ZSTD_seekable_CStream* zcs); |
| 90 | |
| 91 | /*===== Seekable compression functions =====*/ |
| 92 | ZSTDLIB_API size_t ZSTD_seekable_initCStream(ZSTD_seekable_CStream* zcs, int compressionLevel, int checksumFlag, unsigned maxFrameSize); |
| 93 | ZSTDLIB_API size_t ZSTD_seekable_compressStream(ZSTD_seekable_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); |
| 94 | ZSTDLIB_API size_t ZSTD_seekable_endFrame(ZSTD_seekable_CStream* zcs, ZSTD_outBuffer* output); |
| 95 | ZSTDLIB_API size_t ZSTD_seekable_endStream(ZSTD_seekable_CStream* zcs, ZSTD_outBuffer* output); |
| 96 | |
| 97 | /*= Raw seek table API |
| 98 | * These functions allow for the seek table to be constructed directly. |
| 99 | * This table can then be appended to a file of concatenated frames. |
| 100 | * This allows the frames to be compressed independently, even in parallel, |
| 101 | * and compiled together afterward into a seekable archive. |
| 102 | * |
| 103 | * Use ZSTD_seekable_createFrameLog() to allocate and initialize a tracking |
| 104 | * structure. |
| 105 | * |
| 106 | * Call ZSTD_seekable_logFrame() once for each frame in the archive. |
| 107 | * checksum is optional, and will not be used if checksumFlag was 0 when the |
| 108 | * frame log was created. If present, it should be the least significant 32 |
| 109 | * bits of the XXH64 hash of the uncompressed data. |
| 110 | * |
| 111 | * Call ZSTD_seekable_writeSeekTable to serialize the data into a seek table. |
| 112 | * If the entire table was written, the return value will be 0. Otherwise, |
| 113 | * it will be equal to the number of bytes left to write. */ |
| 114 | typedef struct ZSTD_frameLog_s ZSTD_frameLog; |
| 115 | ZSTDLIB_API ZSTD_frameLog* ZSTD_seekable_createFrameLog(int checksumFlag); |
| 116 | ZSTDLIB_API size_t ZSTD_seekable_freeFrameLog(ZSTD_frameLog* fl); |
| 117 | ZSTDLIB_API size_t ZSTD_seekable_logFrame(ZSTD_frameLog* fl, unsigned compressedSize, unsigned decompressedSize, unsigned checksum); |
| 118 | ZSTDLIB_API size_t ZSTD_seekable_writeSeekTable(ZSTD_frameLog* fl, ZSTD_outBuffer* output); |
| 119 | |
| 120 | |
| 121 | /*-**************************************************************************** |
| 122 | * Seekable decompression - HowTo |
| 123 | * A ZSTD_seekable object is required to tracking the seekTable. |
| 124 | * |
| 125 | * Call ZSTD_seekable_init* to initialize a ZSTD_seekable object with the |
| 126 | * the seek table provided in the input. |
| 127 | * There are three modes for ZSTD_seekable_init: |
| 128 | * - ZSTD_seekable_initBuff() : An in-memory API. The data contained in |
| 129 | * `src` should be the entire seekable file, including the seek table. |
| 130 | * `src` should be kept alive and unmodified until the ZSTD_seekable object |
| 131 | * is freed or reset. |
| 132 | * - ZSTD_seekable_initFile() : A simplified file API using stdio. fread and |
| 133 | * fseek will be used to access the required data for building the seek |
| 134 | * table and doing decompression operations. `src` should not be closed |
| 135 | * or modified until the ZSTD_seekable object is freed or reset. |
| 136 | * - ZSTD_seekable_initAdvanced() : A general API allowing the client to |
| 137 | * provide its own read and seek callbacks. |
| 138 | * + ZSTD_seekable_read() : read exactly `n` bytes into `buffer`. |
| 139 | * Premature EOF should be treated as an error. |
| 140 | * + ZSTD_seekable_seek() : seek the read head to `offset` from `origin`, |
| 141 | * where origin is either SEEK_SET (beginning of |
| 142 | * file), or SEEK_END (end of file). |
| 143 | * Both functions should return a non-negative value in case of success, and a |
| 144 | * negative value in case of failure. If implementing using this API and |
| 145 | * stdio, be careful with files larger than 4GB and fseek. All of these |
| 146 | * functions return an error code checkable with ZSTD_isError(). |
| 147 | * |
| 148 | * Call ZSTD_seekable_decompress to decompress `dstSize` bytes at decompressed |
| 149 | * offset `offset`. ZSTD_seekable_decompress may have to decompress the entire |
| 150 | * prefix of the frame before the desired data if it has not already processed |
| 151 | * this section. If ZSTD_seekable_decompress is called multiple times for a |
| 152 | * consecutive range of data, it will efficiently retain the decompressor object |
| 153 | * and avoid redecompressing frame prefixes. The return value is the number of |
| 154 | * bytes decompressed, or an error code checkable with ZSTD_isError(). |
| 155 | * |
| 156 | * The seek table access functions can be used to obtain the data contained |
| 157 | * in the seek table. If frameIndex is larger than the value returned by |
| 158 | * ZSTD_seekable_getNumFrames(), they will return error codes checkable with |
| 159 | * ZSTD_isError(). Note that since the offset access functions return |
| 160 | * unsigned long long instead of size_t, in this case they will instead return |
| 161 | * the value ZSTD_SEEKABLE_FRAMEINDEX_TOOLARGE. |
| 162 | ******************************************************************************/ |
| 163 | |
| 164 | /*===== Seekable decompressor management =====*/ |
| 165 | ZSTDLIB_API ZSTD_seekable* ZSTD_seekable_create(void); |
| 166 | ZSTDLIB_API size_t ZSTD_seekable_free(ZSTD_seekable* zs); |
| 167 | |
| 168 | /*===== Seekable decompression functions =====*/ |
| 169 | ZSTDLIB_API size_t ZSTD_seekable_initBuff(ZSTD_seekable* zs, const void* src, size_t srcSize); |
| 170 | ZSTDLIB_API size_t ZSTD_seekable_initFile(ZSTD_seekable* zs, FILE* src); |
| 171 | ZSTDLIB_API size_t ZSTD_seekable_decompress(ZSTD_seekable* zs, void* dst, size_t dstSize, unsigned long long offset); |
| 172 | ZSTDLIB_API size_t ZSTD_seekable_decompressFrame(ZSTD_seekable* zs, void* dst, size_t dstSize, unsigned frameIndex); |
| 173 | |
| 174 | #define ZSTD_SEEKABLE_FRAMEINDEX_TOOLARGE (0ULL-2) |
| 175 | /*===== Seekable seek table access functions =====*/ |
| 176 | ZSTDLIB_API unsigned ZSTD_seekable_getNumFrames(const ZSTD_seekable* zs); |
| 177 | ZSTDLIB_API unsigned long long ZSTD_seekable_getFrameCompressedOffset(const ZSTD_seekable* zs, unsigned frameIndex); |
| 178 | ZSTDLIB_API unsigned long long ZSTD_seekable_getFrameDecompressedOffset(const ZSTD_seekable* zs, unsigned frameIndex); |
| 179 | ZSTDLIB_API size_t ZSTD_seekable_getFrameCompressedSize(const ZSTD_seekable* zs, unsigned frameIndex); |
| 180 | ZSTDLIB_API size_t ZSTD_seekable_getFrameDecompressedSize(const ZSTD_seekable* zs, unsigned frameIndex); |
| 181 | ZSTDLIB_API unsigned ZSTD_seekable_offsetToFrameIndex(const ZSTD_seekable* zs, unsigned long long offset); |
| 182 | |
| 183 | |
| 184 | /*-**************************************************************************** |
| 185 | * Direct exploitation of the seekTable |
| 186 | * |
| 187 | * Memory constrained use cases that manage multiple archives |
| 188 | * benefit from retaining multiple archive seek tables |
| 189 | * without retaining a ZSTD_seekable instance for each. |
| 190 | * |
| 191 | * Below API allow the above-mentioned use cases |
| 192 | * to initialize a ZSTD_seekable, extract its (smaller) ZSTD_seekTable, |
| 193 | * then throw the ZSTD_seekable away to save memory. |
| 194 | * |
| 195 | * Standard ZSTD operations can then be used |
| 196 | * to decompress frames based on seek table offsets. |
| 197 | ******************************************************************************/ |
| 198 | |
| 199 | /*===== Independent seek table management =====*/ |
| 200 | ZSTDLIB_API ZSTD_seekTable* ZSTD_seekTable_create_fromSeekable(const ZSTD_seekable* zs); |
| 201 | ZSTDLIB_API size_t ZSTD_seekTable_free(ZSTD_seekTable* st); |
| 202 | |
| 203 | /*===== Direct seek table access functions =====*/ |
| 204 | ZSTDLIB_API unsigned ZSTD_seekTable_getNumFrames(const ZSTD_seekTable* st); |
| 205 | ZSTDLIB_API unsigned long long ZSTD_seekTable_getFrameCompressedOffset(const ZSTD_seekTable* st, unsigned frameIndex); |
| 206 | ZSTDLIB_API unsigned long long ZSTD_seekTable_getFrameDecompressedOffset(const ZSTD_seekTable* st, unsigned frameIndex); |
| 207 | ZSTDLIB_API size_t ZSTD_seekTable_getFrameCompressedSize(const ZSTD_seekTable* st, unsigned frameIndex); |
| 208 | ZSTDLIB_API size_t ZSTD_seekTable_getFrameDecompressedSize(const ZSTD_seekTable* st, unsigned frameIndex); |
| 209 | ZSTDLIB_API unsigned ZSTD_seekTable_offsetToFrameIndex(const ZSTD_seekTable* st, unsigned long long offset); |
| 210 | |
| 211 | |
| 212 | /*===== Seekable advanced I/O API =====*/ |
| 213 | typedef int(ZSTD_seekable_read)(void* opaque, void* buffer, size_t n); |
| 214 | typedef int(ZSTD_seekable_seek)(void* opaque, long long offset, int origin); |
| 215 | typedef struct { |
| 216 | void* opaque; |
| 217 | ZSTD_seekable_read* read; |
| 218 | ZSTD_seekable_seek* seek; |
| 219 | } ZSTD_seekable_customFile; |
| 220 | ZSTDLIB_API size_t ZSTD_seekable_initAdvanced(ZSTD_seekable* zs, ZSTD_seekable_customFile src); |
| 221 | |
| 222 | #if defined (__cplusplus) |
| 223 | } |
| 224 | #endif |
| 225 | |
| 226 | #endif |