1 /* zlib.h -- interface of the 'zlib' general purpose compression library 2 version 1.1.4, March 11th, 2002 3 4 Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler 5 6 This software is provided 'as-is', without any express or implied 7 warranty. In no event will the authors be held liable for any damages 8 arising from the use of this software. 9 10 Permission is granted to anyone to use this software for any purpose, 11 including commercial applications, and to alter it and redistribute it 12 freely, subject to the following restrictions: 13 14 1. The origin of this software must not be misrepresented; you must not 15 claim that you wrote the original software. If you use this software 16 in a product, an acknowledgment in the product documentation would be 17 appreciated but is not required. 18 2. Altered source versions must be plainly marked as such, and must not be 19 misrepresented as being the original software. 20 3. This notice may not be removed or altered from any source distribution. 21 22 Jean-loup Gailly Mark Adler 23 jloup@gzip.org madler@alumni.caltech.edu 24 25 26 The data format used by the zlib library is described by RFCs (Request for 27 Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt 28 (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format). 29 */ 30 31 #ifndef _ZLIB_H 32 #define _ZLIB_H 33 34 #include "zconf.h" 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 #define ZLIB_VERSION "1.1.4" 41 42 /* 43 The 'zlib' compression library provides in-memory compression and 44 decompression functions, including integrity checks of the uncompressed 45 data. This version of the library supports only one compression method 46 (deflation) but other algorithms will be added later and will have the same 47 stream interface. 48 49 Compression can be done in a single step if the buffers are large 50 enough (for example if an input file is mmap'ed), or can be done by 51 repeated calls of the compression function. In the latter case, the 52 application must provide more input and/or consume the output 53 (providing more output space) before each call. 54 55 The library also supports reading and writing files in gzip (.gz) format 56 with an interface similar to that of stdio. 57 58 The library does not install any signal handler. The decoder checks 59 the consistency of the compressed data, so the library should never 60 crash even in case of corrupted input. 61 */ 62 63 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size)); 64 typedef void (*free_func) OF((voidpf opaque, voidpf address)); 65 66 struct internal_state; 67 68 typedef struct z_stream_s { 69 Bytef *next_in; /* next input byte */ 70 uInt avail_in; /* number of bytes available at next_in */ 71 uLong total_in; /* total nb of input bytes read so far */ 72 73 Bytef *next_out; /* next output byte should be put there */ 74 uInt avail_out; /* remaining free space at next_out */ 75 uLong total_out; /* total nb of bytes output so far */ 76 77 char *msg; /* last error message, NULL if no error */ 78 struct internal_state FAR *state; /* not visible by applications */ 79 80 alloc_func zalloc; /* used to allocate the internal state */ 81 free_func zfree; /* used to free the internal state */ 82 voidpf opaque; /* private data object passed to zalloc and zfree */ 83 84 int data_type; /* best guess about the data type: ascii or binary */ 85 uLong adler; /* adler32 value of the uncompressed data */ 86 uLong reserved; /* reserved for future use */ 87 } z_stream; 88 89 typedef z_stream FAR *z_streamp; 90 91 /* 92 The application must update next_in and avail_in when avail_in has 93 dropped to zero. It must update next_out and avail_out when avail_out 94 has dropped to zero. The application must initialize zalloc, zfree and 95 opaque before calling the init function. All other fields are set by the 96 compression library and must not be updated by the application. 97 98 The opaque value provided by the application will be passed as the first 99 parameter for calls of zalloc and zfree. This can be useful for custom 100 memory management. The compression library attaches no meaning to the 101 opaque value. 102 103 zalloc must return Z_NULL if there is not enough memory for the object. 104 If zlib is used in a multi-threaded application, zalloc and zfree must be 105 thread safe. 106 107 On 16-bit systems, the functions zalloc and zfree must be able to allocate 108 exactly 65536 bytes, but will not be required to allocate more than this 109 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, 110 pointers returned by zalloc for objects of exactly 65536 bytes *must* 111 have their offset normalized to zero. The default allocation function 112 provided by this library ensures this (see zutil.c). To reduce memory 113 requirements and avoid any allocation of 64K objects, at the expense of 114 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h). 115 116 The fields total_in and total_out can be used for statistics or 117 progress reports. After compression, total_in holds the total size of 118 the uncompressed data and may be saved for use in the decompressor 119 (particularly if the decompressor wants to decompress everything in 120 a single step). 121 */ 122 123 /* constants */ 124 125 #define Z_NO_FLUSH 0 126 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */ 127 #define Z_SYNC_FLUSH 2 128 #define Z_FULL_FLUSH 3 129 #define Z_FINISH 4 130 /* Allowed flush values; see deflate() below for details */ 131 132 #define Z_OK 0 133 #define Z_STREAM_END 1 134 #define Z_NEED_DICT 2 135 #define Z_ERRNO (-1) 136 #define Z_STREAM_ERROR (-2) 137 #define Z_DATA_ERROR (-3) 138 #define Z_MEM_ERROR (-4) 139 #define Z_BUF_ERROR (-5) 140 #define Z_VERSION_ERROR (-6) 141 /* Return codes for the compression/decompression functions. Negative 142 * values are errors, positive values are used for special but normal events. 143 */ 144 145 #define Z_NO_COMPRESSION 0 146 #define Z_BEST_SPEED 1 147 #define Z_BEST_COMPRESSION 9 148 #define Z_DEFAULT_COMPRESSION (-1) 149 /* compression levels */ 150 151 #define Z_FILTERED 1 152 #define Z_HUFFMAN_ONLY 2 153 #define Z_DEFAULT_STRATEGY 0 154 /* compression strategy; see deflateInit2() below for details */ 155 156 #define Z_BINARY 0 157 #define Z_ASCII 1 158 #define Z_UNKNOWN 2 159 /* Possible values of the data_type field */ 160 161 #define Z_DEFLATED 8 162 /* The deflate compression method (the only one supported in this version) */ 163 164 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */ 165 166 167 /* basic functions */ 168 169 /* The application can compare zlibVersion and ZLIB_VERSION for consistency. 170 If the first character differs, the library code actually used is 171 not compatible with the zlib.h header file used by the application. 172 This check is automatically made by deflateInit and inflateInit. 173 */ 174 175 /* 176 ZEXTERN(int) deflateInit OF((z_streamp strm, int level)); 177 178 Initializes the internal stream state for compression. The fields 179 zalloc, zfree and opaque must be initialized before by the caller. 180 If zalloc and zfree are set to Z_NULL, deflateInit updates them to 181 use default allocation functions. 182 183 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9: 184 1 gives best speed, 9 gives best compression, 0 gives no compression at 185 all (the input data is simply copied a block at a time). 186 Z_DEFAULT_COMPRESSION requests a default compromise between speed and 187 compression (currently equivalent to level 6). 188 189 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not 190 enough memory, Z_STREAM_ERROR if level is not a valid compression level, 191 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible 192 with the version assumed by the caller (ZLIB_VERSION). 193 msg is set to null if there is no error message. deflateInit does not 194 perform any compression: this will be done by deflate(). 195 */ 196 197 198 /* 199 deflate compresses as much data as possible, and stops when the input 200 buffer becomes empty or the output buffer becomes full. It may introduce some 201 output latency (reading input without producing any output) except when 202 forced to flush. 203 204 The detailed semantics are as follows. deflate performs one or both of the 205 following actions: 206 207 - Compress more input starting at next_in and update next_in and avail_in 208 accordingly. If not all input can be processed (because there is not 209 enough room in the output buffer), next_in and avail_in are updated and 210 processing will resume at this point for the next call of deflate(). 211 212 - Provide more output starting at next_out and update next_out and avail_out 213 accordingly. This action is forced if the parameter flush is non zero. 214 Forcing flush frequently degrades the compression ratio, so this parameter 215 should be set only when necessary (in interactive applications). 216 Some output may be provided even if flush is not set. 217 218 Before the call of deflate(), the application should ensure that at least 219 one of the actions is possible, by providing more input and/or consuming 220 more output, and updating avail_in or avail_out accordingly; avail_out 221 should never be zero before the call. The application can consume the 222 compressed output when it wants, for example when the output buffer is full 223 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK 224 and with zero avail_out, it must be called again after making room in the 225 output buffer because there might be more output pending. 226 227 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is 228 flushed to the output buffer and the output is aligned on a byte boundary, so 229 that the decompressor can get all input data available so far. (In particular 230 avail_in is zero after the call if enough output space has been provided 231 before the call.) Flushing may degrade compression for some compression 232 algorithms and so it should be used only when necessary. 233 234 If flush is set to Z_FULL_FLUSH, all output is flushed as with 235 Z_SYNC_FLUSH, and the compression state is reset so that decompression can 236 restart from this point if previous compressed data has been damaged or if 237 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade 238 the compression. 239 240 If deflate returns with avail_out == 0, this function must be called again 241 with the same value of the flush parameter and more output space (updated 242 avail_out), until the flush is complete (deflate returns with non-zero 243 avail_out). 244 245 If the parameter flush is set to Z_FINISH, pending input is processed, 246 pending output is flushed and deflate returns with Z_STREAM_END if there 247 was enough output space; if deflate returns with Z_OK, this function must be 248 called again with Z_FINISH and more output space (updated avail_out) but no 249 more input data, until it returns with Z_STREAM_END or an error. After 250 deflate has returned Z_STREAM_END, the only possible operations on the 251 stream are deflateReset or deflateEnd. 252 253 Z_FINISH can be used immediately after deflateInit if all the compression 254 is to be done in a single step. In this case, avail_out must be at least 255 0.1% larger than avail_in plus 12 bytes. If deflate does not return 256 Z_STREAM_END, then it must be called again as described above. 257 258 deflate() sets strm->adler to the adler32 checksum of all input read 259 so far (that is, total_in bytes). 260 261 deflate() may update data_type if it can make a good guess about 262 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered 263 binary. This field is only for information purposes and does not affect 264 the compression algorithm in any manner. 265 266 deflate() returns Z_OK if some progress has been made (more input 267 processed or more output produced), Z_STREAM_END if all input has been 268 consumed and all output has been produced (only when flush is set to 269 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example 270 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible 271 (for example avail_in or avail_out was zero). 272 */ 273 274 275 /* 276 All dynamically allocated data structures for this stream are freed. 277 This function discards any unprocessed input and does not flush any 278 pending output. 279 280 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the 281 stream state was inconsistent, Z_DATA_ERROR if the stream was freed 282 prematurely (some input or output was discarded). In the error case, 283 msg may be set but then points to a static string (which must not be 284 deallocated). 285 */ 286 287 288 /* 289 ZEXTERN(int) inflateInit OF((z_streamp strm)); 290 291 Initializes the internal stream state for decompression. The fields 292 next_in, avail_in, zalloc, zfree and opaque must be initialized before by 293 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact 294 value depends on the compression method), inflateInit determines the 295 compression method from the zlib header and allocates all data structures 296 accordingly; otherwise the allocation will be deferred to the first call of 297 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to 298 use default allocation functions. 299 300 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 301 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 302 version assumed by the caller. msg is set to null if there is no error 303 message. inflateInit does not perform any decompression apart from reading 304 the zlib header if present: this will be done by inflate(). (So next_in and 305 avail_in may be modified, but next_out and avail_out are unchanged.) 306 */ 307 308 309 ZEXTERN(int) inflate OF((z_streamp strm, int flush)); 310 /* 311 inflate decompresses as much data as possible, and stops when the input 312 buffer becomes empty or the output buffer becomes full. It may some 313 introduce some output latency (reading input without producing any output) 314 except when forced to flush. 315 316 The detailed semantics are as follows. inflate performs one or both of the 317 following actions: 318 319 - Decompress more input starting at next_in and update next_in and avail_in 320 accordingly. If not all input can be processed (because there is not 321 enough room in the output buffer), next_in is updated and processing 322 will resume at this point for the next call of inflate(). 323 324 - Provide more output starting at next_out and update next_out and avail_out 325 accordingly. inflate() provides as much output as possible, until there 326 is no more input data or no more space in the output buffer (see below 327 about the flush parameter). 328 329 Before the call of inflate(), the application should ensure that at least 330 one of the actions is possible, by providing more input and/or consuming 331 more output, and updating the next_* and avail_* values accordingly. 332 The application can consume the uncompressed output when it wants, for 333 example when the output buffer is full (avail_out == 0), or after each 334 call of inflate(). If inflate returns Z_OK and with zero avail_out, it 335 must be called again after making room in the output buffer because there 336 might be more output pending. 337 338 If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much 339 output as possible to the output buffer. The flushing behavior of inflate is 340 not specified for values of the flush parameter other than Z_SYNC_FLUSH 341 and Z_FINISH, but the current implementation actually flushes as much output 342 as possible anyway. 343 344 inflate() should normally be called until it returns Z_STREAM_END or an 345 error. However if all decompression is to be performed in a single step 346 (a single call of inflate), the parameter flush should be set to 347 Z_FINISH. In this case all pending input is processed and all pending 348 output is flushed; avail_out must be large enough to hold all the 349 uncompressed data. (The size of the uncompressed data may have been saved 350 by the compressor for this purpose.) The next operation on this stream must 351 be inflateEnd to deallocate the decompression state. The use of Z_FINISH 352 is never required, but can be used to inform inflate that a faster routine 353 may be used for the single inflate() call. 354 355 If a preset dictionary is needed at this point (see inflateSetDictionary 356 below), inflate sets strm-adler to the adler32 checksum of the 357 dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise 358 it sets strm->adler to the adler32 checksum of all output produced 359 so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or 360 an error code as described below. At the end of the stream, inflate() 361 checks that its computed adler32 checksum is equal to that saved by the 362 compressor and returns Z_STREAM_END only if the checksum is correct. 363 364 inflate() returns Z_OK if some progress has been made (more input processed 365 or more output produced), Z_STREAM_END if the end of the compressed data has 366 been reached and all uncompressed output has been produced, Z_NEED_DICT if a 367 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was 368 corrupted (input stream not conforming to the zlib format or incorrect 369 adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent 370 (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not 371 enough memory, Z_BUF_ERROR if no progress is possible or if there was not 372 enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR 373 case, the application may then call inflateSync to look for a good 374 compression block. 375 */ 376 377 378 ZEXTERN(int) inflateEnd OF((z_streamp strm)); 379 /* 380 All dynamically allocated data structures for this stream are freed. 381 This function discards any unprocessed input and does not flush any 382 pending output. 383 384 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state 385 was inconsistent. In the error case, msg may be set but then points to a 386 static string (which must not be deallocated). 387 */ 388 389 /* Advanced functions */ 390 391 /* 392 The following functions are needed only in some special applications. 393 */ 394 395 /* 396 ZEXTERN(int) deflateInit2 OF((z_streamp strm, 397 int level, 398 int method, 399 int windowBits, 400 int memLevel, 401 int strategy)); 402 403 This is another version of deflateInit with more compression options. The 404 fields next_in, zalloc, zfree and opaque must be initialized before by 405 the caller. 406 407 The method parameter is the compression method. It must be Z_DEFLATED in 408 this version of the library. 409 410 The windowBits parameter is the base two logarithm of the window size 411 (the size of the history buffer). It should be in the range 8..15 for this 412 version of the library. Larger values of this parameter result in better 413 compression at the expense of memory usage. The default value is 15 if 414 deflateInit is used instead. 415 416 The memLevel parameter specifies how much memory should be allocated 417 for the internal compression state. memLevel=1 uses minimum memory but 418 is slow and reduces compression ratio; memLevel=9 uses maximum memory 419 for optimal speed. The default value is 8. See zconf.h for total memory 420 usage as a function of windowBits and memLevel. 421 422 The strategy parameter is used to tune the compression algorithm. Use the 423 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a 424 filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no 425 string match). Filtered data consists mostly of small values with a 426 somewhat random distribution. In this case, the compression algorithm is 427 tuned to compress them better. The effect of Z_FILTERED is to force more 428 Huffman coding and less string matching; it is somewhat intermediate 429 between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects 430 the compression ratio but not the correctness of the compressed output even 431 if it is not set appropriately. 432 433 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 434 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid 435 method). msg is set to null if there is no error message. deflateInit2 does 436 not perform any compression: this will be done by deflate(). 437 */ 438 439 /* 440 Initializes the compression dictionary from the given byte sequence 441 without producing any compressed output. This function must be called 442 immediately after deflateInit, deflateInit2 or deflateReset, before any 443 call of deflate. The compressor and decompressor must use exactly the same 444 dictionary (see inflateSetDictionary). 445 446 The dictionary should consist of strings (byte sequences) that are likely 447 to be encountered later in the data to be compressed, with the most commonly 448 used strings preferably put towards the end of the dictionary. Using a 449 dictionary is most useful when the data to be compressed is short and can be 450 predicted with good accuracy; the data can then be compressed better than 451 with the default empty dictionary. 452 453 Depending on the size of the compression data structures selected by 454 deflateInit or deflateInit2, a part of the dictionary may in effect be 455 discarded, for example if the dictionary is larger than the window size in 456 deflate or deflate2. Thus the strings most likely to be useful should be 457 put at the end of the dictionary, not at the front. 458 459 Upon return of this function, strm->adler is set to the Adler32 value 460 of the dictionary; the decompressor may later use this value to determine 461 which dictionary has been used by the compressor. (The Adler32 value 462 applies to the whole dictionary even if only a subset of the dictionary is 463 actually used by the compressor.) 464 465 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a 466 parameter is invalid (such as NULL dictionary) or the stream state is 467 inconsistent (for example if deflate has already been called for this stream 468 or if the compression method is bsort). deflateSetDictionary does not 469 perform any compression: this will be done by deflate(). 470 */ 471 472 /* 473 Sets the destination stream as a complete copy of the source stream. 474 475 This function can be useful when several compression strategies will be 476 tried, for example when there are several ways of pre-processing the input 477 data with a filter. The streams that will be discarded should then be freed 478 by calling deflateEnd. Note that deflateCopy duplicates the internal 479 compression state which can be quite large, so this strategy is slow and 480 can consume lots of memory. 481 482 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 483 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 484 (such as zalloc being NULL). msg is left unchanged in both source and 485 destination. 486 */ 487 488 /* 489 This function is equivalent to deflateEnd followed by deflateInit, 490 but does not free and reallocate all the internal compression state. 491 The stream will keep the same compression level and any other attributes 492 that may have been set by deflateInit2. 493 494 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 495 stream state was inconsistent (such as zalloc or state being NULL). 496 */ 497 498 /* 499 Dynamically update the compression level and compression strategy. The 500 interpretation of level and strategy is as in deflateInit2. This can be 501 used to switch between compression and straight copy of the input data, or 502 to switch to a different kind of input data requiring a different 503 strategy. If the compression level is changed, the input available so far 504 is compressed with the old level (and may be flushed); the new level will 505 take effect only at the next call of deflate(). 506 507 Before the call of deflateParams, the stream state must be set as for 508 a call of deflate(), since the currently available input may have to 509 be compressed and flushed. In particular, strm->avail_out must be non-zero. 510 511 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source 512 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR 513 if strm->avail_out was zero. 514 */ 515 516 /* 517 ZEXTERN(int) inflateInit2 OF((z_streamp strm, 518 int windowBits)); 519 520 This is another version of inflateInit with an extra parameter. The 521 fields next_in, avail_in, zalloc, zfree and opaque must be initialized 522 before by the caller. 523 524 The windowBits parameter is the base two logarithm of the maximum window 525 size (the size of the history buffer). It should be in the range 8..15 for 526 this version of the library. The default value is 15 if inflateInit is used 527 instead. If a compressed stream with a larger window size is given as 528 input, inflate() will return with the error code Z_DATA_ERROR instead of 529 trying to allocate a larger window. 530 531 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 532 memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative 533 memLevel). msg is set to null if there is no error message. inflateInit2 534 does not perform any decompression apart from reading the zlib header if 535 present: this will be done by inflate(). (So next_in and avail_in may be 536 modified, but next_out and avail_out are unchanged.) 537 */ 538 539 /* 540 Initializes the decompression dictionary from the given uncompressed byte 541 sequence. This function must be called immediately after a call of inflate 542 if this call returned Z_NEED_DICT. The dictionary chosen by the compressor 543 can be determined from the Adler32 value returned by this call of 544 inflate. The compressor and decompressor must use exactly the same 545 dictionary (see deflateSetDictionary). 546 547 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a 548 parameter is invalid (such as NULL dictionary) or the stream state is 549 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the 550 expected one (incorrect Adler32 value). inflateSetDictionary does not 551 perform any decompression: this will be done by subsequent calls of 552 inflate(). 553 */ 554 555 /* 556 Skips invalid compressed data until a full flush point (see above the 557 description of deflate with Z_FULL_FLUSH) can be found, or until all 558 available input is skipped. No output is provided. 559 560 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR 561 if no more input was provided, Z_DATA_ERROR if no flush point has been found, 562 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success 563 case, the application may save the current current value of total_in which 564 indicates where valid compressed data was found. In the error case, the 565 application may repeatedly call inflateSync, providing more input each time, 566 until success or end of the input data. 567 */ 568 569 ZEXTERN(int) inflateReset OF((z_streamp strm)); 570 /* 571 This function is equivalent to inflateEnd followed by inflateInit, 572 but does not free and reallocate all the internal decompression state. 573 The stream will keep attributes that may have been set by inflateInit2. 574 575 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 576 stream state was inconsistent (such as zalloc or state being NULL). 577 */ 578 579 580 /* utility functions */ 581 582 /* 583 The following utility functions are implemented on top of the 584 basic stream-oriented functions. To simplify the interface, some 585 default options are assumed (compression level and memory usage, 586 standard memory allocation functions). The source code of these 587 utility functions can easily be modified if you need special options. 588 */ 589 590 /* 591 Compresses the source buffer into the destination buffer. sourceLen is 592 the byte length of the source buffer. Upon entry, destLen is the total 593 size of the destination buffer, which must be at least 0.1% larger than 594 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the 595 compressed buffer. 596 This function can be used to compress a whole file at once if the 597 input file is mmap'ed. 598 compress returns Z_OK if success, Z_MEM_ERROR if there was not 599 enough memory, Z_BUF_ERROR if there was not enough room in the output 600 buffer. 601 */ 602 603 /* 604 Compresses the source buffer into the destination buffer. The level 605 parameter has the same meaning as in deflateInit. sourceLen is the byte 606 length of the source buffer. Upon entry, destLen is the total size of the 607 destination buffer, which must be at least 0.1% larger than sourceLen plus 608 12 bytes. Upon exit, destLen is the actual size of the compressed buffer. 609 610 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 611 memory, Z_BUF_ERROR if there was not enough room in the output buffer, 612 Z_STREAM_ERROR if the level parameter is invalid. 613 */ 614 615 /* 616 Decompresses the source buffer into the destination buffer. sourceLen is 617 the byte length of the source buffer. Upon entry, destLen is the total 618 size of the destination buffer, which must be large enough to hold the 619 entire uncompressed data. (The size of the uncompressed data must have 620 been saved previously by the compressor and transmitted to the decompressor 621 by some mechanism outside the scope of this compression library.) 622 Upon exit, destLen is the actual size of the compressed buffer. 623 This function can be used to decompress a whole file at once if the 624 input file is mmap'ed. 625 626 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not 627 enough memory, Z_BUF_ERROR if there was not enough room in the output 628 buffer, or Z_DATA_ERROR if the input data was corrupted. 629 */ 630 631 632 /* 633 Opens a gzip (.gz) file for reading or writing. The mode parameter 634 is as in fopen ("rb" or "wb") but can also include a compression level 635 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for 636 Huffman only compression as in "wb1h". (See the description 637 of deflateInit2 for more information about the strategy parameter.) 638 639 gzopen can be used to read a file which is not in gzip format; in this 640 case gzread will directly read from the file without decompression. 641 642 gzopen returns NULL if the file could not be opened or if there was 643 insufficient memory to allocate the (de)compression state; errno 644 can be checked to distinguish the two cases (if errno is zero, the 645 zlib error is Z_MEM_ERROR). */ 646 647 /* 648 gzdopen() associates a gzFile with the file descriptor fd. File 649 descriptors are obtained from calls like open, dup, creat, pipe or 650 fileno (in the file has been previously opened with fopen). 651 The mode parameter is as in gzopen. 652 The next call of gzclose on the returned gzFile will also close the 653 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file 654 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode). 655 gzdopen returns NULL if there was insufficient memory to allocate 656 the (de)compression state. 657 */ 658 659 /* 660 Dynamically update the compression level or strategy. See the description 661 of deflateInit2 for the meaning of these parameters. 662 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not 663 opened for writing. 664 */ 665 666 /* 667 Reads the given number of uncompressed bytes from the compressed file. 668 If the input file was not in gzip format, gzread copies the given number 669 of bytes into the buffer. 670 gzread returns the number of uncompressed bytes actually read (0 for 671 end of file, -1 for error). */ 672 673 /* 674 Writes the given number of uncompressed bytes into the compressed file. 675 gzwrite returns the number of uncompressed bytes actually written 676 (0 in case of error). 677 */ 678 679 /* 680 Converts, formats, and writes the args to the compressed file under 681 control of the format string, as in fprintf. gzprintf returns the number of 682 uncompressed bytes actually written (0 in case of error). 683 */ 684 685 /* 686 Writes the given null-terminated string to the compressed file, excluding 687 the terminating null character. 688 gzputs returns the number of characters written, or -1 in case of error. 689 */ 690 691 /* 692 Reads bytes from the compressed file until len-1 characters are read, or 693 a newline character is read and transferred to buf, or an end-of-file 694 condition is encountered. The string is then terminated with a null 695 character. 696 gzgets returns buf, or Z_NULL in case of error. 697 */ 698 699 /* 700 Writes c, converted to an unsigned char, into the compressed file. 701 gzputc returns the value that was written, or -1 in case of error. 702 */ 703 704 /* 705 Reads one byte from the compressed file. gzgetc returns this byte 706 or -1 in case of end of file or error. 707 */ 708 709 /* 710 Flushes all pending output into the compressed file. The parameter 711 flush is as in the deflate() function. The return value is the zlib 712 error number (see function gzerror below). gzflush returns Z_OK if 713 the flush parameter is Z_FINISH and all output could be flushed. 714 gzflush should be called only when strictly necessary because it can 715 degrade compression. 716 */ 717 718 /* 719 Sets the starting position for the next gzread or gzwrite on the 720 given compressed file. The offset represents a number of bytes in the 721 uncompressed data stream. The whence parameter is defined as in lseek(2); 722 the value SEEK_END is not supported. 723 If the file is opened for reading, this function is emulated but can be 724 extremely slow. If the file is opened for writing, only forward seeks are 725 supported; gzseek then compresses a sequence of zeroes up to the new 726 starting position. 727 728 gzseek returns the resulting offset location as measured in bytes from 729 the beginning of the uncompressed stream, or -1 in case of error, in 730 particular if the file is opened for writing and the new starting position 731 would be before the current position. 732 */ 733 734 /* 735 Rewinds the given file. This function is supported only for reading. 736 737 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET) 738 */ 739 740 /* 741 Returns the starting position for the next gzread or gzwrite on the 742 given compressed file. This position represents a number of bytes in the 743 uncompressed data stream. 744 745 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR) 746 */ 747 748 /* 749 Returns 1 when EOF has previously been detected reading the given 750 input stream, otherwise zero. 751 */ 752 753 /* 754 Flushes all pending output if necessary, closes the compressed file 755 and deallocates all the (de)compression state. The return value is the zlib 756 error number (see function gzerror below). 757 */ 758 759 /* 760 Returns the error message for the last error which occurred on the 761 given compressed file. errnum is set to zlib error number. If an 762 error occurred in the file system and not in the compression library, 763 errnum is set to Z_ERRNO and the application may consult errno 764 to get the exact error code. 765 */ 766 767 /* checksum functions */ 768 769 /* 770 These functions are not related to compression but are exported 771 anyway because they might be useful in applications using the 772 compression library. 773 */ 774 775 ZEXTERN(uLong) adler32 OF((uLong adler, const Bytef *buf, uInt len)); 776 777 /* 778 Update a running Adler-32 checksum with the bytes buf[0..len-1] and 779 return the updated checksum. If buf is NULL, this function returns 780 the required initial value for the checksum. 781 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed 782 much faster. Usage example: 783 784 uLong adler = adler32(0L, Z_NULL, 0); 785 786 while (read_buffer(buffer, length) != EOF) { 787 adler = adler32(adler, buffer, length); 788 } 789 if (adler != original_adler) error(); 790 */ 791 792 /* 793 Update a running crc with the bytes buf[0..len-1] and return the updated 794 crc. If buf is NULL, this function returns the required initial value 795 for the crc. Pre- and post-conditioning (one's complement) is performed 796 within this function so it shouldn't be done by the application. 797 Usage example: 798 799 uLong crc = crc32(0L, Z_NULL, 0); 800 801 while (read_buffer(buffer, length) != EOF) { 802 crc = crc32(crc, buffer, length); 803 } 804 if (crc != original_crc) error(); 805 */ 806 807 808 /* various hacks, don't look :) */ 809 810 /* deflateInit and inflateInit are macros to allow checking the zlib version 811 * and the compiler's view of z_stream: 812 */ 813 ZEXTERN(int) inflateInit2_ OF((z_streamp strm, int windowBits, 814 const char *version, int stream_size)); 815 #define deflateInit(strm, level) \ 816 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream)) 817 #define inflateInit(strm) \ 818 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream)) 819 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \ 820 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\ 821 (strategy), ZLIB_VERSION, sizeof(z_stream)) 822 #define inflateInit2(strm, windowBits) \ 823 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream)) 824 825 826 #ifdef __cplusplus 827 } 828 #endif 829 830 #endif /* _ZLIB_H */ 831