1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.1.3, July 9th, 1998
4 Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
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.
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:
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.
22 Jean-loup Gailly Mark Adler
23 jloup@gzip.org madler@alumni.caltech.edu
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).
40 #define ZLIB_VERSION "1.1.3"
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
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.
55 The library also supports reading and writing files in gzip (.gz) format
56 with an interface similar to that of stdio.
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.
63 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size))
65 typedef void (*free_func) OF((voidpf opaque, voidpf address))
68 struct internal_state;
70 typedef struct z_stream_s {
71 Bytef *next_in; /* next input byte */
72 uInt avail_in; /* number of bytes available at next_in */
73 uLong total_in; /* total nb of input bytes read so far */
75 Bytef *next_out; /* next output byte should be put there */
76 uInt avail_out; /* remaining free space at next_out */
77 uLong total_out; /* total nb of bytes output so far */
80 char *msg; /* last error message, NULL if no error */
81 struct internal_state FAR *state; /* not visible by applications */
83 alloc_func zalloc; /* used to allocate the internal state */
84 free_func zfree; /* used to free the internal state */
85 voidpf opaque; /* private data object passed to zalloc and zfree */
87 int data_type; /* best guess about the data type: ascii or binary */
88 uLong adler; /* adler32 value of the uncompressed data */
89 uLong crc; /* crc32 as updated during decompression */
92 typedef /*@abstract@*/ z_stream FAR *z_streamp;
95 The application must update next_in and avail_in when avail_in has
96 dropped to zero. It must update next_out and avail_out when avail_out
97 has dropped to zero. The application must initialize zalloc, zfree and
98 opaque before calling the init function. All other fields are set by the
99 compression library and must not be updated by the application.
101 The opaque value provided by the application will be passed as the first
102 parameter for calls of zalloc and zfree. This can be useful for custom
103 memory management. The compression library attaches no meaning to the
106 zalloc must return Z_NULL if there is not enough memory for the object.
107 If zlib is used in a multi-threaded application, zalloc and zfree must be
110 On 16-bit systems, the functions zalloc and zfree must be able to allocate
111 exactly 65536 bytes, but will not be required to allocate more than this
112 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
113 pointers returned by zalloc for objects of exactly 65536 bytes *must*
114 have their offset normalized to zero. The default allocation function
115 provided by this library ensures this (see zutil.c). To reduce memory
116 requirements and avoid any allocation of 64K objects, at the expense of
117 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
119 The fields total_in and total_out can be used for statistics or
120 progress reports. After compression, total_in holds the total size of
121 the uncompressed data and may be saved for use in the decompressor
122 (particularly if the decompressor wants to decompress everything in
129 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
130 #define Z_SYNC_FLUSH 2
131 #define Z_FULL_FLUSH 3
133 /* Allowed flush values; see deflate() below for details */
136 #define Z_STREAM_END 1
137 #define Z_NEED_DICT 2
139 #define Z_STREAM_ERROR (-2)
140 #define Z_DATA_ERROR (-3)
141 #define Z_MEM_ERROR (-4)
142 #define Z_BUF_ERROR (-5)
143 #define Z_VERSION_ERROR (-6)
144 /* Return codes for the compression/decompression functions. Negative
145 * values are errors, positive values are used for special but normal events.
148 #define Z_NO_COMPRESSION 0
149 #define Z_BEST_SPEED 1
150 #define Z_BEST_COMPRESSION 9
151 #define Z_DEFAULT_COMPRESSION (-1)
152 /* compression levels */
155 #define Z_HUFFMAN_ONLY 2
156 #define Z_DEFAULT_STRATEGY 0
157 /* compression strategy; see deflateInit2() below for details */
162 /* Possible values of the data_type field */
165 /* The deflate compression method (the only one supported in this version) */
167 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
169 #define zlib_version zlibVersion()
170 /* for compatibility with versions < 1.0.2 */
172 /* basic functions */
175 ZEXTERN const char * ZEXPORT zlibVersion OF((void))
177 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
178 If the first character differs, the library code actually used is
179 not compatible with the zlib.h header file used by the application.
180 This check is automatically made by deflateInit and inflateInit.
184 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
186 Initializes the internal stream state for compression. The fields
187 zalloc, zfree and opaque must be initialized before by the caller.
188 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
189 use default allocation functions.
191 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
192 1 gives best speed, 9 gives best compression, 0 gives no compression at
193 all (the input data is simply copied a block at a time).
194 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
195 compression (currently equivalent to level 6).
197 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
198 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
199 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
200 with the version assumed by the caller (ZLIB_VERSION).
201 msg is set to null if there is no error message. deflateInit does not
202 perform any compression: this will be done by deflate().
206 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush))
207 /*@modifies strm @*/;
209 deflate compresses as much data as possible, and stops when the input
210 buffer becomes empty or the output buffer becomes full. It may introduce some
211 output latency (reading input without producing any output) except when
214 The detailed semantics are as follows. deflate performs one or both of the
217 - Compress more input starting at next_in and update next_in and avail_in
218 accordingly. If not all input can be processed (because there is not
219 enough room in the output buffer), next_in and avail_in are updated and
220 processing will resume at this point for the next call of deflate().
222 - Provide more output starting at next_out and update next_out and avail_out
223 accordingly. This action is forced if the parameter flush is non zero.
224 Forcing flush frequently degrades the compression ratio, so this parameter
225 should be set only when necessary (in interactive applications).
226 Some output may be provided even if flush is not set.
228 Before the call of deflate(), the application should ensure that at least
229 one of the actions is possible, by providing more input and/or consuming
230 more output, and updating avail_in or avail_out accordingly; avail_out
231 should never be zero before the call. The application can consume the
232 compressed output when it wants, for example when the output buffer is full
233 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
234 and with zero avail_out, it must be called again after making room in the
235 output buffer because there might be more output pending.
237 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
238 flushed to the output buffer and the output is aligned on a byte boundary, so
239 that the decompressor can get all input data available so far. (In particular
240 avail_in is zero after the call if enough output space has been provided
241 before the call.) Flushing may degrade compression for some compression
242 algorithms and so it should be used only when necessary.
244 If flush is set to Z_FULL_FLUSH, all output is flushed as with
245 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
246 restart from this point if previous compressed data has been damaged or if
247 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
250 If deflate returns with avail_out == 0, this function must be called again
251 with the same value of the flush parameter and more output space (updated
252 avail_out), until the flush is complete (deflate returns with non-zero
255 If the parameter flush is set to Z_FINISH, pending input is processed,
256 pending output is flushed and deflate returns with Z_STREAM_END if there
257 was enough output space; if deflate returns with Z_OK, this function must be
258 called again with Z_FINISH and more output space (updated avail_out) but no
259 more input data, until it returns with Z_STREAM_END or an error. After
260 deflate has returned Z_STREAM_END, the only possible operations on the
261 stream are deflateReset or deflateEnd.
263 Z_FINISH can be used immediately after deflateInit if all the compression
264 is to be done in a single step. In this case, avail_out must be at least
265 0.1% larger than avail_in plus 12 bytes. If deflate does not return
266 Z_STREAM_END, then it must be called again as described above.
268 deflate() sets strm->adler to the adler32 checksum of all input read
269 so far (that is, total_in bytes).
271 deflate() may update data_type if it can make a good guess about
272 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
273 binary. This field is only for information purposes and does not affect
274 the compression algorithm in any manner.
276 deflate() returns Z_OK if some progress has been made (more input
277 processed or more output produced), Z_STREAM_END if all input has been
278 consumed and all output has been produced (only when flush is set to
279 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
280 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
281 (for example avail_in or avail_out was zero).
285 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm))
286 /*@modifies strm @*/;
288 All dynamically allocated data structures for this stream are freed.
289 This function discards any unprocessed input and does not flush any
292 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
293 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
294 prematurely (some input or output was discarded). In the error case,
295 msg may be set but then points to a static string (which must not be
301 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
303 Initializes the internal stream state for decompression. The fields
304 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
305 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
306 value depends on the compression method), inflateInit determines the
307 compression method from the zlib header and allocates all data structures
308 accordingly; otherwise the allocation will be deferred to the first call of
309 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
310 use default allocation functions.
312 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
313 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
314 version assumed by the caller. msg is set to null if there is no error
315 message. inflateInit does not perform any decompression apart from reading
316 the zlib header if present: this will be done by inflate(). (So next_in and
317 avail_in may be modified, but next_out and avail_out are unchanged.)
321 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush))
322 /*@modifies strm @*/;
324 inflate decompresses as much data as possible, and stops when the input
325 buffer becomes empty or the output buffer becomes full. It may some
326 introduce some output latency (reading input without producing any output)
327 except when forced to flush.
329 The detailed semantics are as follows. inflate performs one or both of the
332 - Decompress more input starting at next_in and update next_in and avail_in
333 accordingly. If not all input can be processed (because there is not
334 enough room in the output buffer), next_in is updated and processing
335 will resume at this point for the next call of inflate().
337 - Provide more output starting at next_out and update next_out and avail_out
338 accordingly. inflate() provides as much output as possible, until there
339 is no more input data or no more space in the output buffer (see below
340 about the flush parameter).
342 Before the call of inflate(), the application should ensure that at least
343 one of the actions is possible, by providing more input and/or consuming
344 more output, and updating the next_* and avail_* values accordingly.
345 The application can consume the uncompressed output when it wants, for
346 example when the output buffer is full (avail_out == 0), or after each
347 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
348 must be called again after making room in the output buffer because there
349 might be more output pending.
351 If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
352 output as possible to the output buffer. The flushing behavior of inflate is
353 not specified for values of the flush parameter other than Z_SYNC_FLUSH
354 and Z_FINISH, but the current implementation actually flushes as much output
357 inflate() should normally be called until it returns Z_STREAM_END or an
358 error. However if all decompression is to be performed in a single step
359 (a single call of inflate), the parameter flush should be set to
360 Z_FINISH. In this case all pending input is processed and all pending
361 output is flushed; avail_out must be large enough to hold all the
362 uncompressed data. (The size of the uncompressed data may have been saved
363 by the compressor for this purpose.) The next operation on this stream must
364 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
365 is never required, but can be used to inform inflate that a faster routine
366 may be used for the single inflate() call.
368 If a preset dictionary is needed at this point (see inflateSetDictionary
369 below), inflate sets strm-adler to the adler32 checksum of the
370 dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
371 it sets strm->adler to the adler32 checksum of all output produced
372 so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
373 an error code as described below. At the end of the stream, inflate()
374 checks that its computed adler32 checksum is equal to that saved by the
375 compressor and returns Z_STREAM_END only if the checksum is correct.
377 inflate() returns Z_OK if some progress has been made (more input processed
378 or more output produced), Z_STREAM_END if the end of the compressed data has
379 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
380 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
381 corrupted (input stream not conforming to the zlib format or incorrect
382 adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
383 (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
384 enough memory, Z_BUF_ERROR if no progress is possible or if there was not
385 enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
386 case, the application may then call inflateSync to look for a good
391 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm))
392 /*@modifies strm @*/;
394 All dynamically allocated data structures for this stream are freed.
395 This function discards any unprocessed input and does not flush any
398 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
399 was inconsistent. In the error case, msg may be set but then points to a
400 static string (which must not be deallocated).
403 /* Advanced functions */
406 The following functions are needed only in some special applications.
410 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
417 This is another version of deflateInit with more compression options. The
418 fields next_in, zalloc, zfree and opaque must be initialized before by
421 The method parameter is the compression method. It must be Z_DEFLATED in
422 this version of the library.
424 The windowBits parameter is the base two logarithm of the window size
425 (the size of the history buffer). It should be in the range 8..15 for this
426 version of the library. Larger values of this parameter result in better
427 compression at the expense of memory usage. The default value is 15 if
428 deflateInit is used instead.
430 The memLevel parameter specifies how much memory should be allocated
431 for the internal compression state. memLevel=1 uses minimum memory but
432 is slow and reduces compression ratio; memLevel=9 uses maximum memory
433 for optimal speed. The default value is 8. See zconf.h for total memory
434 usage as a function of windowBits and memLevel.
436 The strategy parameter is used to tune the compression algorithm. Use the
437 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
438 filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
439 string match). Filtered data consists mostly of small values with a
440 somewhat random distribution. In this case, the compression algorithm is
441 tuned to compress them better. The effect of Z_FILTERED is to force more
442 Huffman coding and less string matching; it is somewhat intermediate
443 between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
444 the compression ratio but not the correctness of the compressed output even
445 if it is not set appropriately.
447 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
448 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
449 method). msg is set to null if there is no error message. deflateInit2 does
450 not perform any compression: this will be done by deflate().
453 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
454 const Bytef *dictionary,
456 /*@modifies strm @*/;
458 Initializes the compression dictionary from the given byte sequence
459 without producing any compressed output. This function must be called
460 immediately after deflateInit, deflateInit2 or deflateReset, before any
461 call of deflate. The compressor and decompressor must use exactly the same
462 dictionary (see inflateSetDictionary).
464 The dictionary should consist of strings (byte sequences) that are likely
465 to be encountered later in the data to be compressed, with the most commonly
466 used strings preferably put towards the end of the dictionary. Using a
467 dictionary is most useful when the data to be compressed is short and can be
468 predicted with good accuracy; the data can then be compressed better than
469 with the default empty dictionary.
471 Depending on the size of the compression data structures selected by
472 deflateInit or deflateInit2, a part of the dictionary may in effect be
473 discarded, for example if the dictionary is larger than the window size in
474 deflate or deflate2. Thus the strings most likely to be useful should be
475 put at the end of the dictionary, not at the front.
477 Upon return of this function, strm->adler is set to the Adler32 value
478 of the dictionary; the decompressor may later use this value to determine
479 which dictionary has been used by the compressor. (The Adler32 value
480 applies to the whole dictionary even if only a subset of the dictionary is
481 actually used by the compressor.)
483 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
484 parameter is invalid (such as NULL dictionary) or the stream state is
485 inconsistent (for example if deflate has already been called for this stream
486 or if the compression method is bsort). deflateSetDictionary does not
487 perform any compression: this will be done by deflate().
490 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
492 /*@modifies dest, source @*/;
494 Sets the destination stream as a complete copy of the source stream.
496 This function can be useful when several compression strategies will be
497 tried, for example when there are several ways of pre-processing the input
498 data with a filter. The streams that will be discarded should then be freed
499 by calling deflateEnd. Note that deflateCopy duplicates the internal
500 compression state which can be quite large, so this strategy is slow and
501 can consume lots of memory.
503 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
504 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
505 (such as zalloc being NULL). msg is left unchanged in both source and
509 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm))
510 /*@modifies strm @*/;
512 This function is equivalent to deflateEnd followed by deflateInit,
513 but does not free and reallocate all the internal compression state.
514 The stream will keep the same compression level and any other attributes
515 that may have been set by deflateInit2.
517 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
518 stream state was inconsistent (such as zalloc or state being NULL).
521 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
524 /*@modifies strm @*/;
526 Dynamically update the compression level and compression strategy. The
527 interpretation of level and strategy is as in deflateInit2. This can be
528 used to switch between compression and straight copy of the input data, or
529 to switch to a different kind of input data requiring a different
530 strategy. If the compression level is changed, the input available so far
531 is compressed with the old level (and may be flushed); the new level will
532 take effect only at the next call of deflate().
534 Before the call of deflateParams, the stream state must be set as for
535 a call of deflate(), since the currently available input may have to
536 be compressed and flushed. In particular, strm->avail_out must be non-zero.
538 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
539 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
540 if strm->avail_out was zero.
544 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
547 This is another version of inflateInit with an extra parameter. The
548 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
549 before by the caller.
551 The windowBits parameter is the base two logarithm of the maximum window
552 size (the size of the history buffer). It should be in the range 8..15 for
553 this version of the library. The default value is 15 if inflateInit is used
554 instead. If a compressed stream with a larger window size is given as
555 input, inflate() will return with the error code Z_DATA_ERROR instead of
556 trying to allocate a larger window.
558 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
559 memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
560 memLevel). msg is set to null if there is no error message. inflateInit2
561 does not perform any decompression apart from reading the zlib header if
562 present: this will be done by inflate(). (So next_in and avail_in may be
563 modified, but next_out and avail_out are unchanged.)
566 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
567 const Bytef *dictionary,
571 Initializes the decompression dictionary from the given uncompressed byte
572 sequence. This function must be called immediately after a call of inflate
573 if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
574 can be determined from the Adler32 value returned by this call of
575 inflate. The compressor and decompressor must use exactly the same
576 dictionary (see deflateSetDictionary).
578 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
579 parameter is invalid (such as NULL dictionary) or the stream state is
580 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
581 expected one (incorrect Adler32 value). inflateSetDictionary does not
582 perform any decompression: this will be done by subsequent calls of
586 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm))
587 /*@modifies strm @*/;
589 Skips invalid compressed data until a full flush point (see above the
590 description of deflate with Z_FULL_FLUSH) can be found, or until all
591 available input is skipped. No output is provided.
593 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
594 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
595 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
596 case, the application may save the current current value of total_in which
597 indicates where valid compressed data was found. In the error case, the
598 application may repeatedly call inflateSync, providing more input each time,
599 until success or end of the input data.
602 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm))
603 /*@modifies strm @*/;
605 This function is equivalent to inflateEnd followed by inflateInit,
606 but does not free and reallocate all the internal decompression state.
607 The stream will keep attributes that may have been set by inflateInit2.
609 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
610 stream state was inconsistent (such as zalloc or state being NULL).
614 /* utility functions */
617 The following utility functions are implemented on top of the
618 basic stream-oriented functions. To simplify the interface, some
619 default options are assumed (compression level and memory usage,
620 standard memory allocation functions). The source code of these
621 utility functions can easily be modified if you need special options.
624 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
625 const Bytef *source, uLong sourceLen))
626 /*@modifies *dest, *destLen @*/;
628 Compresses the source buffer into the destination buffer. sourceLen is
629 the byte length of the source buffer. Upon entry, destLen is the total
630 size of the destination buffer, which must be at least 0.1% larger than
631 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
633 This function can be used to compress a whole file at once if the
634 input file is mmap'ed.
635 compress returns Z_OK if success, Z_MEM_ERROR if there was not
636 enough memory, Z_BUF_ERROR if there was not enough room in the output
640 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
641 const Bytef *source, uLong sourceLen,
643 /*@modifies *dest, *destLen @*/;
645 Compresses the source buffer into the destination buffer. The level
646 parameter has the same meaning as in deflateInit. sourceLen is the byte
647 length of the source buffer. Upon entry, destLen is the total size of the
648 destination buffer, which must be at least 0.1% larger than sourceLen plus
649 12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
651 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
652 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
653 Z_STREAM_ERROR if the level parameter is invalid.
656 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
657 const Bytef *source, uLong sourceLen))
658 /*@modifies *dest, *destLen @*/;
660 Decompresses the source buffer into the destination buffer. sourceLen is
661 the byte length of the source buffer. Upon entry, destLen is the total
662 size of the destination buffer, which must be large enough to hold the
663 entire uncompressed data. (The size of the uncompressed data must have
664 been saved previously by the compressor and transmitted to the decompressor
665 by some mechanism outside the scope of this compression library.)
666 Upon exit, destLen is the actual size of the compressed buffer.
667 This function can be used to decompress a whole file at once if the
668 input file is mmap'ed.
670 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
671 enough memory, Z_BUF_ERROR if there was not enough room in the output
672 buffer, or Z_DATA_ERROR if the input data was corrupted.
676 typedef voidp gzFile;
678 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode))
679 /*@globals fileSystem @*/
680 /*@modifies fileSystem @*/;
682 Opens a gzip (.gz) file for reading or writing. The mode parameter
683 is as in fopen ("rb" or "wb") but can also include a compression level
684 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
685 Huffman only compression as in "wb1h". (See the description
686 of deflateInit2 for more information about the strategy parameter.)
688 gzopen can be used to read a file which is not in gzip format; in this
689 case gzread will directly read from the file without decompression.
691 gzopen returns NULL if the file could not be opened or if there was
692 insufficient memory to allocate the (de)compression state; errno
693 can be checked to distinguish the two cases (if errno is zero, the
694 zlib error is Z_MEM_ERROR). */
696 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode))
697 /*@globals fileSystem @*/
698 /*@modifies fileSystem @*/;
700 gzdopen() associates a gzFile with the file descriptor fd. File
701 descriptors are obtained from calls like open, dup, creat, pipe or
702 fileno (in the file has been previously opened with fopen).
703 The mode parameter is as in gzopen.
704 The next call of gzclose on the returned gzFile will also close the
705 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
706 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
707 gzdopen returns NULL if there was insufficient memory to allocate
708 the (de)compression state.
711 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy))
712 /*@globals fileSystem @*/
713 /*@modifies file, fileSystem @*/;
715 Dynamically update the compression level or strategy. See the description
716 of deflateInit2 for the meaning of these parameters.
717 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
721 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len))
722 /*@globals errno, fileSystem @*/
723 /*@modifies file, *buf, errno, fileSystem @*/;
725 Reads the given number of uncompressed bytes from the compressed file.
726 If the input file was not in gzip format, gzread copies the given number
727 of bytes into the buffer.
728 gzread returns the number of uncompressed bytes actually read (0 for
729 end of file, -1 for error). */
731 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
732 const voidp buf, unsigned len))
733 /*@globals fileSystem @*/
734 /*@modifies file, fileSystem @*/;
736 Writes the given number of uncompressed bytes into the compressed file.
737 gzwrite returns the number of uncompressed bytes actually written
738 (0 in case of error).
741 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...))
742 /*@globals fileSystem @*/
743 /*@modifies file, fileSystem @*/;
745 Converts, formats, and writes the args to the compressed file under
746 control of the format string, as in fprintf. gzprintf returns the number of
747 uncompressed bytes actually written (0 in case of error).
750 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s))
751 /*@globals fileSystem @*/
752 /*@modifies file, fileSystem @*/;
754 Writes the given null-terminated string to the compressed file, excluding
755 the terminating null character.
756 gzputs returns the number of characters written, or -1 in case of error.
759 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len))
760 /*@globals fileSystem @*/
761 /*@modifies file, buf, fileSystem @*/;
763 Reads bytes from the compressed file until len-1 characters are read, or
764 a newline character is read and transferred to buf, or an end-of-file
765 condition is encountered. The string is then terminated with a null
767 gzgets returns buf, or Z_NULL in case of error.
770 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c))
771 /*@globals fileSystem @*/
772 /*@modifies file, fileSystem @*/;
774 Writes c, converted to an unsigned char, into the compressed file.
775 gzputc returns the value that was written, or -1 in case of error.
778 ZEXTERN int ZEXPORT gzgetc OF((gzFile file))
779 /*@globals fileSystem @*/
780 /*@modifies file, fileSystem @*/;
782 Reads one byte from the compressed file. gzgetc returns this byte
783 or -1 in case of end of file or error.
786 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush))
787 /*@globals fileSystem @*/
788 /*@modifies file, fileSystem @*/;
790 Flushes all pending output into the compressed file. The parameter
791 flush is as in the deflate() function. The return value is the zlib
792 error number (see function gzerror below). gzflush returns Z_OK if
793 the flush parameter is Z_FINISH and all output could be flushed.
794 gzflush should be called only when strictly necessary because it can
798 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
799 z_off_t offset, int whence))
800 /*@globals fileSystem @*/
801 /*@modifies file, fileSystem @*/;
803 Sets the starting position for the next gzread or gzwrite on the
804 given compressed file. The offset represents a number of bytes in the
805 uncompressed data stream. The whence parameter is defined as in lseek(2);
806 the value SEEK_END is not supported.
807 If the file is opened for reading, this function is emulated but can be
808 extremely slow. If the file is opened for writing, only forward seeks are
809 supported; gzseek then compresses a sequence of zeroes up to the new
812 gzseek returns the resulting offset location as measured in bytes from
813 the beginning of the uncompressed stream, or -1 in case of error, in
814 particular if the file is opened for writing and the new starting position
815 would be before the current position.
818 ZEXTERN int ZEXPORT gzrewind OF((gzFile file))
819 /*@globals fileSystem @*/
820 /*@modifies file, fileSystem @*/;
822 Rewinds the given file. This function is supported only for reading.
824 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
827 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file))
828 /*@globals fileSystem @*/
829 /*@modifies file, fileSystem @*/;
831 Returns the starting position for the next gzread or gzwrite on the
832 given compressed file. This position represents a number of bytes in the
833 uncompressed data stream.
835 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
838 ZEXTERN int ZEXPORT gzeof OF((gzFile file))
841 Returns 1 when EOF has previously been detected reading the given
842 input stream, otherwise zero.
845 ZEXTERN int ZEXPORT gzclose OF((/*@only@*/ gzFile file))
846 /*@globals fileSystem @*/
847 /*@modifies file, fileSystem @*/;
849 Flushes all pending output if necessary, closes the compressed file
850 and deallocates all the (de)compression state. The return value is the zlib
851 error number (see function gzerror below).
854 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum))
855 /*@modifies *errnum @*/;
857 Returns the error message for the last error which occurred on the
858 given compressed file. errnum is set to zlib error number. If an
859 error occurred in the file system and not in the compression library,
860 errnum is set to Z_ERRNO and the application may consult errno
861 to get the exact error code.
864 /* checksum functions */
867 These functions are not related to compression but are exported
868 anyway because they might be useful in applications using the
872 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len))
876 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
877 return the updated checksum. If buf is NULL, this function returns
878 the required initial value for the checksum.
879 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
880 much faster. Usage example:
882 uLong adler = adler32(0L, Z_NULL, 0);
884 while (read_buffer(buffer, length) != EOF) {
885 adler = adler32(adler, buffer, length);
887 if (adler != original_adler) error();
890 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len))
893 Update a running crc with the bytes buf[0..len-1] and return the updated
894 crc. If buf is NULL, this function returns the required initial value
895 for the crc. Pre- and post-conditioning (one's complement) is performed
896 within this function so it shouldn't be done by the application.
899 uLong crc = crc32(0L, Z_NULL, 0);
901 while (read_buffer(buffer, length) != EOF) {
902 crc = crc32(crc, buffer, length);
904 if (crc != original_crc) error();
908 /* various hacks, don't look :) */
910 /* deflateInit and inflateInit are macros to allow checking the zlib version
911 * and the compiler's view of z_stream:
913 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
914 const char *version, int stream_size))
915 /*@modifies strm @*/;
916 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
917 const char *version, int stream_size))
918 /*@modifies strm @*/;
919 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
920 int windowBits, int memLevel,
921 int strategy, const char *version,
923 /*@modifies strm @*/;
924 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
925 const char *version, int stream_size))
926 /*@modifies strm @*/;
927 #define deflateInit(strm, level) \
928 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
929 #define inflateInit(strm) \
930 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
931 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
932 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
933 (strategy), ZLIB_VERSION, sizeof(z_stream))
934 #define inflateInit2(strm, windowBits) \
935 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
938 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
939 struct internal_state {int dummy;}; /* hack for buggy compilers */
942 ZEXTERN const char * ZEXPORT zError OF((int err))
944 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z))
946 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void))