4 #if defined (__cplusplus)
9 #include "zstd.h" /* ZSTDLIB_API */
12 #define ZSTD_seekTableFooterSize 9
14 #define ZSTD_SEEKABLE_MAGICNUMBER 0x8F92EAB1
16 #define ZSTD_SEEKABLE_MAXFRAMES 0x8000000U
18 /* Limit maximum size to avoid potential issues storing the compressed size */
19 #define ZSTD_SEEKABLE_MAX_FRAME_DECOMPRESSED_SIZE 0x40000000U
21 /*-****************************************************************************
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 ******************************************************************************/
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;
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/
40 * Streaming objects are reusable to avoid allocation and deallocation,
41 * to start a new compression operation call ZSTD_seekable_initCStream() on the
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.
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
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()
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
74 * Note 1 : it's just a hint, to help latency a little, any other
75 * value will work fine.
77 * At any time, call ZSTD_seekable_endFrame() to end the current frame and
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 ******************************************************************************/
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);
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);
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.
103 * Use ZSTD_seekable_createFrameLog() to allocate and initialize a tracking
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.
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);
121 /*-****************************************************************************
122 * Seekable decompression - HowTo
123 * A ZSTD_seekable object is required to tracking the seekTable.
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
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().
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().
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 ******************************************************************************/
164 /*===== Seekable decompressor management =====*/
165 ZSTDLIB_API ZSTD_seekable* ZSTD_seekable_create(void);
166 ZSTDLIB_API size_t ZSTD_seekable_free(ZSTD_seekable* zs);
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);
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);
184 /*-****************************************************************************
185 * Direct exploitation of the seekTable
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.
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.
195 * Standard ZSTD operations can then be used
196 * to decompress frames based on seek table offsets.
197 ******************************************************************************/
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);
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);
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);
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);
222 #if defined (__cplusplus)