1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.0.8, Jan 27th, 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 "1.0.8"
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));
64 typedef void (*free_func) OF((voidpf opaque, voidpf address));
66 struct internal_state;
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 */
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 */
77 char *msg; /* last error message, NULL if no error */
78 struct internal_state FAR *state; /* not visible by applications */
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 */
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 */
89 typedef z_stream FAR *z_streamp;
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.
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
103 zalloc must return Z_NULL if there is not enough memory for the object.
104 On 16-bit systems, the functions zalloc and zfree must be able to allocate
105 exactly 65536 bytes, but will not be required to allocate more than this
106 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
107 pointers returned by zalloc for objects of exactly 65536 bytes *must*
108 have their offset normalized to zero. The default allocation function
109 provided by this library ensures this (see zutil.c). To reduce memory
110 requirements and avoid any allocation of 64K objects, at the expense of
111 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
113 The fields total_in and total_out can be used for statistics or
114 progress reports. After compression, total_in holds the total size of
115 the uncompressed data and may be saved for use in the decompressor
116 (particularly if the decompressor wants to decompress everything in
123 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
124 #define Z_SYNC_FLUSH 2
125 #define Z_FULL_FLUSH 3
127 /* Allowed flush values; see deflate() below for details */
130 #define Z_STREAM_END 1
131 #define Z_NEED_DICT 2
133 #define Z_STREAM_ERROR (-2)
134 #define Z_DATA_ERROR (-3)
135 #define Z_MEM_ERROR (-4)
136 #define Z_BUF_ERROR (-5)
137 #define Z_VERSION_ERROR (-6)
138 /* Return codes for the compression/decompression functions. Negative
139 * values are errors, positive values are used for special but normal events.
142 #define Z_NO_COMPRESSION 0
143 #define Z_BEST_SPEED 1
144 #define Z_BEST_COMPRESSION 9
145 #define Z_DEFAULT_COMPRESSION (-1)
146 /* compression levels */
149 #define Z_HUFFMAN_ONLY 2
150 #define Z_DEFAULT_STRATEGY 0
151 /* compression strategy; see deflateInit2() below for details */
156 /* Possible values of the data_type field */
159 /* The deflate compression method (the only one supported in this version) */
161 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
163 #define zlib_version zlibVersion()
164 /* for compatibility with versions < 1.0.2 */
166 /* basic functions */
168 extern const char * EXPORT zlibVersion OF((void));
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.
176 extern int EXPORT deflateInit OF((z_streamp strm, int level));
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.
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).
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().
198 extern int EXPORT deflate OF((z_streamp strm, int flush));
200 deflate compresses as much data as possible, and stops when the input
201 buffer becomes empty or the output buffer becomes full. It may introduce some
202 output latency (reading input without producing any output) except when
205 The detailed semantics are as follows. deflate performs one or both of the
208 - Compress more input starting at next_in and update next_in and avail_in
209 accordingly. If not all input can be processed (because there is not
210 enough room in the output buffer), next_in and avail_in are updated and
211 processing will resume at this point for the next call of deflate().
213 - Provide more output starting at next_out and update next_out and avail_out
214 accordingly. This action is forced if the parameter flush is non zero.
215 Forcing flush frequently degrades the compression ratio, so this parameter
216 should be set only when necessary (in interactive applications).
217 Some output may be provided even if flush is not set.
219 Before the call of deflate(), the application should ensure that at least
220 one of the actions is possible, by providing more input and/or consuming
221 more output, and updating avail_in or avail_out accordingly; avail_out
222 should never be zero before the call. The application can consume the
223 compressed output when it wants, for example when the output buffer is full
224 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
225 and with zero avail_out, it must be called again after making room in the
226 output buffer because there might be more output pending.
228 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
229 flushed to the output buffer and the output is aligned on a byte boundary, so
230 that the decompressor can get all input data available so far. (In particular
231 avail_in is zero after the call if enough output space has been provided
232 before the call.) Flushing may degrade compression for some compression
233 algorithms and so it should be used only when necessary.
235 If flush is set to Z_FULL_FLUSH, all output is flushed as with
236 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
237 restart from this point if previous compressed data has been damaged or if
238 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
241 If deflate returns with avail_out == 0, this function must be called again
242 with the same value of the flush parameter and more output space (updated
243 avail_out), until the flush is complete (deflate returns with non-zero
246 If the parameter flush is set to Z_FINISH, pending input is processed,
247 pending output is flushed and deflate returns with Z_STREAM_END if there
248 was enough output space; if deflate returns with Z_OK, this function must be
249 called again with Z_FINISH and more output space (updated avail_out) but no
250 more input data, until it returns with Z_STREAM_END or an error. After
251 deflate has returned Z_STREAM_END, the only possible operations on the
252 stream are deflateReset or deflateEnd.
254 Z_FINISH can be used immediately after deflateInit if all the compression
255 is to be done in a single step. In this case, avail_out must be at least
256 0.1% larger than avail_in plus 12 bytes. If deflate does not return
257 Z_STREAM_END, then it must be called again as described above.
259 deflate() sets strm->adler to the adler32 checksum of all input read
260 so far (that is, total_in bytes).
262 deflate() may update data_type if it can make a good guess about
263 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
264 binary. This field is only for information purposes and does not affect
265 the compression algorithm in any manner.
267 deflate() returns Z_OK if some progress has been made (more input
268 processed or more output produced), Z_STREAM_END if all input has been
269 consumed and all output has been produced (only when flush is set to
270 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
271 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
275 extern int EXPORT deflateEnd OF((z_streamp strm));
277 All dynamically allocated data structures for this stream are freed.
278 This function discards any unprocessed input and does not flush any
281 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
282 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
283 prematurely (some input or output was discarded). In the error case,
284 msg may be set but then points to a static string (which must not be
290 extern int EXPORT inflateInit OF((z_streamp strm));
292 Initializes the internal stream state for decompression. The fields
293 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
294 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
295 value depends on the compression method), inflateInit determines the
296 compression method from the zlib header and allocates all data structures
297 accordingly; otherwise the allocation will be deferred to the first call of
298 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
299 use default allocation functions.
301 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
302 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
303 version assumed by the caller. msg is set to null if there is no error
304 message. inflateInit does not perform any decompression apart from reading
305 the zlib header if present: this will be done by inflate(). (So next_in and
306 avail_in may be modified, but next_out and avail_out are unchanged.)
310 extern int EXPORT inflate OF((z_streamp strm, int flush));
312 inflate decompresses as much data as possible, and stops when the input
313 buffer becomes empty or the output buffer becomes full. It may some
314 introduce some output latency (reading input without producing any output)
315 except when forced to flush.
317 The detailed semantics are as follows. inflate performs one or both of the
320 - Decompress more input starting at next_in and update next_in and avail_in
321 accordingly. If not all input can be processed (because there is not
322 enough room in the output buffer), next_in is updated and processing
323 will resume at this point for the next call of inflate().
325 - Provide more output starting at next_out and update next_out and avail_out
326 accordingly. inflate() provides as much output as possible, until there
327 is no more input data or no more space in the output buffer (see below
328 about the flush parameter).
330 Before the call of inflate(), the application should ensure that at least
331 one of the actions is possible, by providing more input and/or consuming
332 more output, and updating the next_* and avail_* values accordingly.
333 The application can consume the uncompressed output when it wants, for
334 example when the output buffer is full (avail_out == 0), or after each
335 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
336 must be called again after making room in the output buffer because there
337 might be more output pending.
339 If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
340 output as possible to the output buffer. The flushing behavior of inflate is
341 not specified for values of the flush parameter other than Z_SYNC_FLUSH
342 and Z_FINISH, but the current implementation actually flushes as much output
345 inflate() should normally be called until it returns Z_STREAM_END or an
346 error. However if all decompression is to be performed in a single step
347 (a single call of inflate), the parameter flush should be set to
348 Z_FINISH. In this case all pending input is processed and all pending
349 output is flushed; avail_out must be large enough to hold all the
350 uncompressed data. (The size of the uncompressed data may have been saved
351 by the compressor for this purpose.) The next operation on this stream must
352 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
353 is never required, but can be used to inform inflate that a faster routine
354 may be used for the single inflate() call.
356 If a preset dictionary is needed at this point (see inflateSetDictionary
357 below), inflate sets strm-adler to the adler32 checksum of the
358 dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
359 it sets strm->adler to the adler32 checksum of all output produced
360 so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
361 an error code as described below. At the end of the stream, inflate()
362 checks that its computed adler32 checksum is equal to that saved by the
363 compressor and returns Z_STREAM_END only if the checksum is correct.
365 inflate() returns Z_OK if some progress has been made (more input processed
366 or more output produced), Z_STREAM_END if the end of the compressed data has
367 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
368 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
369 corrupted (input stream not conforming to the zlib format or incorrect
370 adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
371 (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
372 enough memory, Z_BUF_ERROR if no progress is possible or if there was not
373 enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
374 case, the application may then call inflateSync to look for a good
379 extern int EXPORT inflateEnd OF((z_streamp strm));
381 All dynamically allocated data structures for this stream are freed.
382 This function discards any unprocessed input and does not flush any
385 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
386 was inconsistent. In the error case, msg may be set but then points to a
387 static string (which must not be deallocated).
390 /* Advanced functions */
393 The following functions are needed only in some special applications.
397 extern int EXPORT deflateInit2 OF((z_streamp strm,
404 This is another version of deflateInit with more compression options. The
405 fields next_in, zalloc, zfree and opaque must be initialized before by
408 The method parameter is the compression method. It must be Z_DEFLATED in
409 this version of the library.
411 The windowBits parameter is the base two logarithm of the window size
412 (the size of the history buffer). It should be in the range 8..15 for this
413 version of the library. Larger values of this parameter result in better
414 compression at the expense of memory usage. The default value is 15 if
415 deflateInit is used instead.
417 The memLevel parameter specifies how much memory should be allocated
418 for the internal compression state. memLevel=1 uses minimum memory but
419 is slow and reduces compression ratio; memLevel=9 uses maximum memory
420 for optimal speed. The default value is 8. See zconf.h for total memory
421 usage as a function of windowBits and memLevel.
423 The strategy parameter is used to tune the compression algorithm. Use the
424 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
425 filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
426 string match). Filtered data consists mostly of small values with a
427 somewhat random distribution. In this case, the compression algorithm is
428 tuned to compress them better. The effect of Z_FILTERED is to force more
429 Huffman coding and less string matching; it is somewhat intermediate
430 between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
431 the compression ratio but not the correctness of the compressed output even
432 if it is not set appropriately.
434 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
435 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
436 method). msg is set to null if there is no error message. deflateInit2 does
437 not perform any compression: this will be done by deflate().
440 extern int EXPORT deflateSetDictionary OF((z_streamp strm,
441 const Bytef *dictionary,
444 Initializes the compression dictionary from the given byte sequence
445 without producing any compressed output. This function must be called
446 immediately after deflateInit or deflateInit2, before any call of
447 deflate. The compressor and decompressor must use exactly the same
448 dictionary (see inflateSetDictionary).
450 The dictionary should consist of strings (byte sequences) that are likely
451 to be encountered later in the data to be compressed, with the most commonly
452 used strings preferably put towards the end of the dictionary. Using a
453 dictionary is most useful when the data to be compressed is short and can be
454 predicted with good accuracy; the data can then be compressed better than
455 with the default empty dictionary.
457 Depending on the size of the compression data structures selected by
458 deflateInit or deflateInit2, a part of the dictionary may in effect be
459 discarded, for example if the dictionary is larger than the window size in
460 deflate or deflate2. Thus the strings most likely to be useful should be
461 put at the end of the dictionary, not at the front.
463 Upon return of this function, strm->adler is set to the Adler32 value
464 of the dictionary; the decompressor may later use this value to determine
465 which dictionary has been used by the compressor. (The Adler32 value
466 applies to the whole dictionary even if only a subset of the dictionary is
467 actually used by the compressor.)
469 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
470 parameter is invalid (such as NULL dictionary) or the stream state is
471 inconsistent (for example if deflate has already been called for this stream
472 or if the compression method is bsort). deflateSetDictionary does not
473 perform any compression: this will be done by deflate().
476 extern int EXPORT deflateCopy OF((z_streamp dest,
479 Sets the destination stream as a complete copy of the source stream.
481 This function can be useful when several compression strategies will be
482 tried, for example when there are several ways of pre-processing the input
483 data with a filter. The streams that will be discarded should then be freed
484 by calling deflateEnd. Note that deflateCopy duplicates the internal
485 compression state which can be quite large, so this strategy is slow and
486 can consume lots of memory.
488 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
489 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
490 (such as zalloc being NULL). msg is left unchanged in both source and
494 extern int EXPORT deflateReset OF((z_streamp strm));
496 This function is equivalent to deflateEnd followed by deflateInit,
497 but does not free and reallocate all the internal compression state.
498 The stream will keep the same compression level and any other attributes
499 that may have been set by deflateInit2.
501 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
502 stream state was inconsistent (such as zalloc or state being NULL).
505 extern int EXPORT deflateParams OF((z_streamp strm, int level, int strategy));
507 Dynamically update the compression level and compression strategy. The
508 interpretation of level and strategy is as in deflateInit2. This can be
509 used to switch between compression and straight copy of the input data, or
510 to switch to a different kind of input data requiring a different
511 strategy. If the compression level is changed, the input available so far
512 is compressed with the old level (and may be flushed); the new level will
513 take effect only at the next call of deflate().
515 Before the call of deflateParams, the stream state must be set as for
516 a call of deflate(), since the currently available input may have to
517 be compressed and flushed. In particular, strm->avail_out must be non-zero.
519 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
520 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
521 if strm->avail_out was zero.
525 extern int EXPORT inflateInit2 OF((z_streamp strm,
528 This is another version of inflateInit with an extra parameter. The
529 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
530 before by the caller.
532 The windowBits parameter is the base two logarithm of the maximum window
533 size (the size of the history buffer). It should be in the range 8..15 for
534 this version of the library. The default value is 15 if inflateInit is used
535 instead. If a compressed stream with a larger window size is given as
536 input, inflate() will return with the error code Z_DATA_ERROR instead of
537 trying to allocate a larger window.
539 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
540 memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
541 memLevel). msg is set to null if there is no error message. inflateInit2
542 does not perform any decompression apart from reading the zlib header if
543 present: this will be done by inflate(). (So next_in and avail_in may be
544 modified, but next_out and avail_out are unchanged.)
547 extern int EXPORT inflateSetDictionary OF((z_streamp strm,
548 const Bytef *dictionary,
551 Initializes the decompression dictionary from the given uncompressed byte
552 sequence. This function must be called immediately after a call of inflate
553 if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
554 can be determined from the Adler32 value returned by this call of
555 inflate. The compressor and decompressor must use exactly the same
556 dictionary (see deflateSetDictionary).
558 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
559 parameter is invalid (such as NULL dictionary) or the stream state is
560 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
561 expected one (incorrect Adler32 value). inflateSetDictionary does not
562 perform any decompression: this will be done by subsequent calls of
566 extern int EXPORT inflateSync OF((z_streamp strm));
568 Skips invalid compressed data until a full flush point (see above the
569 description of deflate with Z_FULL_FLUSH) can be found, or until all
570 available input is skipped. No output is provided.
572 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
573 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
574 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
575 case, the application may save the current current value of total_in which
576 indicates where valid compressed data was found. In the error case, the
577 application may repeatedly call inflateSync, providing more input each time,
578 until success or end of the input data.
581 extern int EXPORT inflateReset OF((z_streamp strm));
583 This function is equivalent to inflateEnd followed by inflateInit,
584 but does not free and reallocate all the internal decompression state.
585 The stream will keep attributes that may have been set by inflateInit2.
587 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
588 stream state was inconsistent (such as zalloc or state being NULL).
592 /* utility functions */
595 The following utility functions are implemented on top of the
596 basic stream-oriented functions. To simplify the interface, some
597 default options are assumed (compression level and memory usage,
598 standard memory allocation functions). The source code of these
599 utility functions can easily be modified if you need special options.
602 extern int EXPORT compress OF((Bytef *dest, uLongf *destLen,
603 const Bytef *source, uLong sourceLen));
605 Compresses the source buffer into the destination buffer. sourceLen is
606 the byte length of the source buffer. Upon entry, destLen is the total
607 size of the destination buffer, which must be at least 0.1% larger than
608 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
610 This function can be used to compress a whole file at once if the
611 input file is mmap'ed.
612 compress returns Z_OK if success, Z_MEM_ERROR if there was not
613 enough memory, Z_BUF_ERROR if there was not enough room in the output
617 extern int EXPORT compress2 OF((Bytef *dest, uLongf *destLen,
618 const Bytef *source, uLong sourceLen,
621 Compresses the source buffer into the destination buffer. The level
622 parameter has the same meaning as in deflateInit. sourceLen is the byte
623 length of the source buffer. Upon entry, destLen is the total size of the
624 destination buffer, which must be at least 0.1% larger than sourceLen plus
625 12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
627 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
628 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
629 Z_STREAM_ERROR if the level parameter is invalid.
632 extern int EXPORT uncompress OF((Bytef *dest, uLongf *destLen,
633 const Bytef *source, uLong sourceLen));
635 Decompresses the source buffer into the destination buffer. sourceLen is
636 the byte length of the source buffer. Upon entry, destLen is the total
637 size of the destination buffer, which must be large enough to hold the
638 entire uncompressed data. (The size of the uncompressed data must have
639 been saved previously by the compressor and transmitted to the decompressor
640 by some mechanism outside the scope of this compression library.)
641 Upon exit, destLen is the actual size of the compressed buffer.
642 This function can be used to decompress a whole file at once if the
643 input file is mmap'ed.
645 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
646 enough memory, Z_BUF_ERROR if there was not enough room in the output
647 buffer, or Z_DATA_ERROR if the input data was corrupted.
651 typedef voidp gzFile;
653 extern gzFile EXPORT gzopen OF((const char *path, const char *mode));
655 Opens a gzip (.gz) file for reading or writing. The mode parameter
656 is as in fopen ("rb" or "wb") but can also include a compression level
657 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
658 Huffman only compression as in "wb1h". (See the description
659 of deflateInit2 for more information about the strategy parameter.)
661 gzopen can be used to read a file which is not in gzip format; in this
662 case gzread will directly read from the file without decompression.
664 gzopen returns NULL if the file could not be opened or if there was
665 insufficient memory to allocate the (de)compression state; errno
666 can be checked to distinguish the two cases (if errno is zero, the
667 zlib error is Z_MEM_ERROR). */
669 extern gzFile EXPORT gzdopen OF((int fd, const char *mode));
671 gzdopen() associates a gzFile with the file descriptor fd. File
672 descriptors are obtained from calls like open, dup, creat, pipe or
673 fileno (in the file has been previously opened with fopen).
674 The mode parameter is as in gzopen.
675 The next call of gzclose on the returned gzFile will also close the
676 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
677 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
678 gzdopen returns NULL if there was insufficient memory to allocate
679 the (de)compression state.
682 extern int EXPORT gzsetparams OF((gzFile file, int level, int strategy));
684 Dynamically update the compression level or strategy. See the description
685 of deflateInit2 for the meaning of these parameters.
686 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
690 extern int EXPORT gzread OF((gzFile file, voidp buf, unsigned len));
692 Reads the given number of uncompressed bytes from the compressed file.
693 If the input file was not in gzip format, gzread copies the given number
694 of bytes into the buffer.
695 gzread returns the number of uncompressed bytes actually read (0 for
696 end of file, -1 for error). */
698 extern int EXPORT gzwrite OF((gzFile file, const voidp buf, unsigned len));
700 Writes the given number of uncompressed bytes into the compressed file.
701 gzwrite returns the number of uncompressed bytes actually written
702 (0 in case of error).
705 extern int EXPORTVA gzprintf OF((gzFile file, const char *format, ...));
707 Converts, formats, and writes the args to the compressed file under
708 control of the format string, as in fprintf. gzprintf returns the number of
709 uncompressed bytes actually written (0 in case of error).
712 extern int EXPORT gzputc OF((gzFile file, int c));
714 Writes c, converted to an unsigned char, into the compressed file.
715 gzputc returns the value that was written, or -1 in case of error.
718 extern int EXPORT gzgetc OF((gzFile file));
720 Reads one byte from the compressed file. gzgetc returns this byte
721 or -1 in case of end of file or error.
724 extern int EXPORT gzflush OF((gzFile file, int flush));
726 Flushes all pending output into the compressed file. The parameter
727 flush is as in the deflate() function. The return value is the zlib
728 error number (see function gzerror below). gzflush returns Z_OK if
729 the flush parameter is Z_FINISH and all output could be flushed.
730 gzflush should be called only when strictly necessary because it can
734 extern z_off_t EXPORT gzseek OF((gzFile file, z_off_t offset, int whence));
736 Sets the starting position for the next gzread or gzwrite on the given
737 compressed file. The offset represents a number of bytes in the
738 uncompressed data stream. The whence parameter is defined as in lseek(2);
739 the value SEEK_END is not supported.
740 If the file is opened for reading, this function is emulated but can be
741 extremely slow. If the file is opened for writing, only forward seeks are
742 supported; gzseek then compresses a sequence of zeroes up to the new
745 gzseek returns the resulting offset location as measured in bytes from
746 the beginning of the uncompressed stream, or -1 in case of error, in
747 particular if the file is opened for writing and the new starting position
748 would be before the current position.
751 extern int EXPORT gzrewind OF((gzFile file));
753 Rewinds the given file. This function is supported only for reading.
755 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
758 extern z_off_t EXPORT gztell OF((gzFile file));
760 Returns the starting position for the next gzread or gzwrite on the
761 given compressed file. This position represents a number of bytes in the
762 uncompressed data stream.
764 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
767 extern int EXPORT gzeof OF((gzFile file));
769 Returns 1 when EOF has previously been detected reading the given
770 input stream, otherwise zero.
773 extern int EXPORT gzclose OF((gzFile file));
775 Flushes all pending output if necessary, closes the compressed file
776 and deallocates all the (de)compression state. The return value is the zlib
777 error number (see function gzerror below).
780 extern const char * EXPORT gzerror OF((gzFile file, int *errnum));
782 Returns the error message for the last error which occurred on the
783 given compressed file. errnum is set to zlib error number. If an
784 error occurred in the file system and not in the compression library,
785 errnum is set to Z_ERRNO and the application may consult errno
786 to get the exact error code.
789 /* checksum functions */
792 These functions are not related to compression but are exported
793 anyway because they might be useful in applications using the
797 extern uLong EXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
800 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
801 return the updated checksum. If buf is NULL, this function returns
802 the required initial value for the checksum.
803 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
804 much faster. Usage example:
806 uLong adler = adler32(0L, Z_NULL, 0);
808 while (read_buffer(buffer, length) != EOF) {
809 adler = adler32(adler, buffer, length);
811 if (adler != original_adler) error();
814 extern uLong EXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
816 Update a running crc with the bytes buf[0..len-1] and return the updated
817 crc. If buf is NULL, this function returns the required initial value
818 for the crc. Pre- and post-conditioning (one's complement) is performed
819 within this function so it shouldn't be done by the application.
822 uLong crc = crc32(0L, Z_NULL, 0);
824 while (read_buffer(buffer, length) != EOF) {
825 crc = crc32(crc, buffer, length);
827 if (crc != original_crc) error();
831 /* various hacks, don't look :) */
833 /* deflateInit and inflateInit are macros to allow checking the zlib version
834 * and the compiler's view of z_stream:
836 extern int EXPORT deflateInit_ OF((z_streamp strm, int level,
837 const char *version, int stream_size));
838 extern int EXPORT inflateInit_ OF((z_streamp strm,
839 const char *version, int stream_size));
840 extern int EXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
841 int windowBits, int memLevel, int strategy,
842 const char *version, int stream_size));
843 extern int EXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
844 const char *version, int stream_size));
845 #define deflateInit(strm, level) \
846 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
847 #define inflateInit(strm) \
848 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
849 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
850 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
851 (strategy), ZLIB_VERSION, sizeof(z_stream))
852 #define inflateInit2(strm, windowBits) \
853 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
856 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
857 struct internal_state {int dummy;}; /* hack for buggy compilers */
860 extern const char * EXPORT zError OF((int err));
861 extern int EXPORT inflateSyncPoint OF((z_streamp z));
862 extern const uLongf * EXPORT get_crc_table OF((void));