1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.3, July 18th, 2005
4 Copyright (C) 1995-2005 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 http://www.ietf.org/rfc/rfc1950.txt
28 (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
40 #define ZLIB_VERSION "1.2.3.1.Samba"
41 #define ZLIB_VERNUM 0x1231
43 * Modified for Samba by Stefan Metzmacher <metze@samba.org> 2008
45 * inflateReset2() added and compiler warnings fixed
50 The 'zlib' compression library provides in-memory compression and
51 decompression functions, including integrity checks of the uncompressed
52 data. This version of the library supports only one compression method
53 (deflation) but other algorithms will be added later and will have the same
56 Compression can be done in a single step if the buffers are large
57 enough (for example if an input file is mmap'ed), or can be done by
58 repeated calls of the compression function. In the latter case, the
59 application must provide more input and/or consume the output
60 (providing more output space) before each call.
62 The compressed data format used by default by the in-memory functions is
63 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
64 around a deflate stream, which is itself documented in RFC 1951.
66 The library also supports reading and writing files in gzip (.gz) format
67 with an interface similar to that of stdio using the functions that start
68 with "gz". The gzip format is different from the zlib format. gzip is a
69 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
71 This library can optionally read and write gzip streams in memory as well.
73 The zlib format was designed to be compact and fast for use in memory
74 and on communications channels. The gzip format was designed for single-
75 file compression on file systems, has a larger header than zlib to maintain
76 directory information, and uses a different, slower check method than zlib.
78 The library does not install any signal handler. The decoder checks
79 the consistency of the compressed data, so the library should never
80 crash even in case of corrupted input.
83 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
84 typedef void (*free_func) OF((voidpf opaque, voidpf address));
86 struct internal_state;
88 typedef struct z_stream_s {
89 const Bytef *next_in; /* next input byte */
90 uInt avail_in; /* number of bytes available at next_in */
91 uLong total_in; /* total nb of input bytes read so far */
93 Bytef *next_out; /* next output byte should be put there */
94 uInt avail_out; /* remaining free space at next_out */
95 uLong total_out; /* total nb of bytes output so far */
97 const char *msg; /* last error message, NULL if no error */
98 struct internal_state FAR *state; /* not visible by applications */
100 alloc_func zalloc; /* used to allocate the internal state */
101 free_func zfree; /* used to free the internal state */
102 voidpf opaque; /* private data object passed to zalloc and zfree */
104 int data_type; /* best guess about the data type: binary or text */
105 uLong adler; /* adler32 value of the uncompressed data */
106 uLong reserved; /* reserved for future use */
109 typedef z_stream FAR *z_streamp;
112 gzip header information passed to and from zlib routines. See RFC 1952
113 for more details on the meanings of these fields.
115 typedef struct gz_header_s {
116 int text; /* true if compressed data believed to be text */
117 uLong time; /* modification time */
118 int xflags; /* extra flags (not used when writing a gzip file) */
119 int os; /* operating system */
120 Bytef *extra; /* pointer to extra field or Z_NULL if none */
121 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
122 uInt extra_max; /* space at extra (only when reading header) */
123 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
124 uInt name_max; /* space at name (only when reading header) */
125 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
126 uInt comm_max; /* space at comment (only when reading header) */
127 int hcrc; /* true if there was or will be a header crc */
128 int done; /* true when done reading gzip header (not used
129 when writing a gzip file) */
132 typedef gz_header FAR *gz_headerp;
135 The application must update next_in and avail_in when avail_in has
136 dropped to zero. It must update next_out and avail_out when avail_out
137 has dropped to zero. The application must initialize zalloc, zfree and
138 opaque before calling the init function. All other fields are set by the
139 compression library and must not be updated by the application.
141 The opaque value provided by the application will be passed as the first
142 parameter for calls of zalloc and zfree. This can be useful for custom
143 memory management. The compression library attaches no meaning to the
146 zalloc must return Z_NULL if there is not enough memory for the object.
147 If zlib is used in a multi-threaded application, zalloc and zfree must be
150 On 16-bit systems, the functions zalloc and zfree must be able to allocate
151 exactly 65536 bytes, but will not be required to allocate more than this
152 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
153 pointers returned by zalloc for objects of exactly 65536 bytes *must*
154 have their offset normalized to zero. The default allocation function
155 provided by this library ensures this (see zutil.c). To reduce memory
156 requirements and avoid any allocation of 64K objects, at the expense of
157 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
159 The fields total_in and total_out can be used for statistics or
160 progress reports. After compression, total_in holds the total size of
161 the uncompressed data and may be saved for use in the decompressor
162 (particularly if the decompressor wants to decompress everything in
169 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
170 #define Z_SYNC_FLUSH 2
171 #define Z_FULL_FLUSH 3
174 /* Allowed flush values; see deflate() and inflate() below for details */
177 #define Z_STREAM_END 1
178 #define Z_NEED_DICT 2
180 #define Z_STREAM_ERROR (-2)
181 #define Z_DATA_ERROR (-3)
182 #define Z_MEM_ERROR (-4)
183 #define Z_BUF_ERROR (-5)
184 #define Z_VERSION_ERROR (-6)
185 /* Return codes for the compression/decompression functions. Negative
186 * values are errors, positive values are used for special but normal events.
189 #define Z_NO_COMPRESSION 0
190 #define Z_BEST_SPEED 1
191 #define Z_BEST_COMPRESSION 9
192 #define Z_DEFAULT_COMPRESSION (-1)
193 /* compression levels */
196 #define Z_HUFFMAN_ONLY 2
199 #define Z_DEFAULT_STRATEGY 0
200 /* compression strategy; see deflateInit2() below for details */
204 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
206 /* Possible values of the data_type field (though see inflate()) */
209 /* The deflate compression method (the only one supported in this version) */
211 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
213 #define zlib_version zlibVersion()
214 /* for compatibility with versions < 1.0.2 */
216 #if (__GNUC__ >= 3) && (__GNUC_MINOR__ >= 1)
217 /** Use gcc attribute to check printf fns. a1 is the 1-based index of
218 * the parameter containing the format, and a2 the index of the first
219 * argument. Note that some gcc 2.x versions don't handle this
221 #define _Z_PRINTF_ATTRIBUTE(a1, a2) __attribute__ ((format (__printf__, a1, a2)))
223 #define _Z_PRINTF_ATTRIBUTE(a1, a2)
226 /* basic functions */
228 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
229 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
230 If the first character differs, the library code actually used is
231 not compatible with the zlib.h header file used by the application.
232 This check is automatically made by deflateInit and inflateInit.
236 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
238 Initializes the internal stream state for compression. The fields
239 zalloc, zfree and opaque must be initialized before by the caller.
240 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
241 use default allocation functions.
243 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
244 1 gives best speed, 9 gives best compression, 0 gives no compression at
245 all (the input data is simply copied a block at a time).
246 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
247 compression (currently equivalent to level 6).
249 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
250 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
251 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
252 with the version assumed by the caller (ZLIB_VERSION).
253 msg is set to null if there is no error message. deflateInit does not
254 perform any compression: this will be done by deflate().
258 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
260 deflate compresses as much data as possible, and stops when the input
261 buffer becomes empty or the output buffer becomes full. It may introduce some
262 output latency (reading input without producing any output) except when
265 The detailed semantics are as follows. deflate performs one or both of the
268 - Compress more input starting at next_in and update next_in and avail_in
269 accordingly. If not all input can be processed (because there is not
270 enough room in the output buffer), next_in and avail_in are updated and
271 processing will resume at this point for the next call of deflate().
273 - Provide more output starting at next_out and update next_out and avail_out
274 accordingly. This action is forced if the parameter flush is non zero.
275 Forcing flush frequently degrades the compression ratio, so this parameter
276 should be set only when necessary (in interactive applications).
277 Some output may be provided even if flush is not set.
279 Before the call of deflate(), the application should ensure that at least
280 one of the actions is possible, by providing more input and/or consuming
281 more output, and updating avail_in or avail_out accordingly; avail_out
282 should never be zero before the call. The application can consume the
283 compressed output when it wants, for example when the output buffer is full
284 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
285 and with zero avail_out, it must be called again after making room in the
286 output buffer because there might be more output pending.
288 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
289 decide how much data to accumualte before producing output, in order to
290 maximize compression.
292 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
293 flushed to the output buffer and the output is aligned on a byte boundary, so
294 that the decompressor can get all input data available so far. (In particular
295 avail_in is zero after the call if enough output space has been provided
296 before the call.) Flushing may degrade compression for some compression
297 algorithms and so it should be used only when necessary.
299 If flush is set to Z_FULL_FLUSH, all output is flushed as with
300 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
301 restart from this point if previous compressed data has been damaged or if
302 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
305 If deflate returns with avail_out == 0, this function must be called again
306 with the same value of the flush parameter and more output space (updated
307 avail_out), until the flush is complete (deflate returns with non-zero
308 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
309 avail_out is greater than six to avoid repeated flush markers due to
310 avail_out == 0 on return.
312 If the parameter flush is set to Z_FINISH, pending input is processed,
313 pending output is flushed and deflate returns with Z_STREAM_END if there
314 was enough output space; if deflate returns with Z_OK, this function must be
315 called again with Z_FINISH and more output space (updated avail_out) but no
316 more input data, until it returns with Z_STREAM_END or an error. After
317 deflate has returned Z_STREAM_END, the only possible operations on the
318 stream are deflateReset or deflateEnd.
320 Z_FINISH can be used immediately after deflateInit if all the compression
321 is to be done in a single step. In this case, avail_out must be at least
322 the value returned by deflateBound (see below). If deflate does not return
323 Z_STREAM_END, then it must be called again as described above.
325 deflate() sets strm->adler to the adler32 checksum of all input read
326 so far (that is, total_in bytes).
328 deflate() may update strm->data_type if it can make a good guess about
329 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
330 binary. This field is only for information purposes and does not affect
331 the compression algorithm in any manner.
333 deflate() returns Z_OK if some progress has been made (more input
334 processed or more output produced), Z_STREAM_END if all input has been
335 consumed and all output has been produced (only when flush is set to
336 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
337 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
338 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
339 fatal, and deflate() can be called again with more input and more output
340 space to continue compressing.
344 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
346 All dynamically allocated data structures for this stream are freed.
347 This function discards any unprocessed input and does not flush any
350 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
351 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
352 prematurely (some input or output was discarded). In the error case,
353 msg may be set but then points to a static string (which must not be
359 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
361 Initializes the internal stream state for decompression. The fields
362 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
363 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
364 value depends on the compression method), inflateInit determines the
365 compression method from the zlib header and allocates all data structures
366 accordingly; otherwise the allocation will be deferred to the first call of
367 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
368 use default allocation functions.
370 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
371 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
372 version assumed by the caller. msg is set to null if there is no error
373 message. inflateInit does not perform any decompression apart from reading
374 the zlib header if present: this will be done by inflate(). (So next_in and
375 avail_in may be modified, but next_out and avail_out are unchanged.)
379 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
381 inflate decompresses as much data as possible, and stops when the input
382 buffer becomes empty or the output buffer becomes full. It may introduce
383 some output latency (reading input without producing any output) except when
386 The detailed semantics are as follows. inflate performs one or both of the
389 - Decompress more input starting at next_in and update next_in and avail_in
390 accordingly. If not all input can be processed (because there is not
391 enough room in the output buffer), next_in is updated and processing
392 will resume at this point for the next call of inflate().
394 - Provide more output starting at next_out and update next_out and avail_out
395 accordingly. inflate() provides as much output as possible, until there
396 is no more input data or no more space in the output buffer (see below
397 about the flush parameter).
399 Before the call of inflate(), the application should ensure that at least
400 one of the actions is possible, by providing more input and/or consuming
401 more output, and updating the next_* and avail_* values accordingly.
402 The application can consume the uncompressed output when it wants, for
403 example when the output buffer is full (avail_out == 0), or after each
404 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
405 must be called again after making room in the output buffer because there
406 might be more output pending.
408 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
409 Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
410 output as possible to the output buffer. Z_BLOCK requests that inflate() stop
411 if and when it gets to the next deflate block boundary. When decoding the
412 zlib or gzip format, this will cause inflate() to return immediately after
413 the header and before the first block. When doing a raw inflate, inflate()
414 will go ahead and process the first block, and will return when it gets to
415 the end of that block, or when it runs out of data.
417 The Z_BLOCK option assists in appending to or combining deflate streams.
418 Also to assist in this, on return inflate() will set strm->data_type to the
419 number of unused bits in the last byte taken from strm->next_in, plus 64
420 if inflate() is currently decoding the last block in the deflate stream,
421 plus 128 if inflate() returned immediately after decoding an end-of-block
422 code or decoding the complete header up to just before the first byte of the
423 deflate stream. The end-of-block will not be indicated until all of the
424 uncompressed data from that block has been written to strm->next_out. The
425 number of unused bits may in general be greater than seven, except when
426 bit 7 of data_type is set, in which case the number of unused bits will be
429 inflate() should normally be called until it returns Z_STREAM_END or an
430 error. However if all decompression is to be performed in a single step
431 (a single call of inflate), the parameter flush should be set to
432 Z_FINISH. In this case all pending input is processed and all pending
433 output is flushed; avail_out must be large enough to hold all the
434 uncompressed data. (The size of the uncompressed data may have been saved
435 by the compressor for this purpose.) The next operation on this stream must
436 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
437 is never required, but can be used to inform inflate that a faster approach
438 may be used for the single inflate() call.
440 In this implementation, inflate() always flushes as much output as
441 possible to the output buffer, and always uses the faster approach on the
442 first call. So the only effect of the flush parameter in this implementation
443 is on the return value of inflate(), as noted below, or when it returns early
444 because Z_BLOCK is used.
446 If a preset dictionary is needed after this call (see inflateSetDictionary
447 below), inflate sets strm->adler to the adler32 checksum of the dictionary
448 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
449 strm->adler to the adler32 checksum of all output produced so far (that is,
450 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
451 below. At the end of the stream, inflate() checks that its computed adler32
452 checksum is equal to that saved by the compressor and returns Z_STREAM_END
453 only if the checksum is correct.
455 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
456 deflate data. The header type is detected automatically. Any information
457 contained in the gzip header is not retained, so applications that need that
458 information should instead use raw inflate, see inflateInit2() below, or
459 inflateBack() and perform their own processing of the gzip header and
462 inflate() returns Z_OK if some progress has been made (more input processed
463 or more output produced), Z_STREAM_END if the end of the compressed data has
464 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
465 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
466 corrupted (input stream not conforming to the zlib format or incorrect check
467 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
468 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
469 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
470 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
471 inflate() can be called again with more input and more output space to
472 continue decompressing. If Z_DATA_ERROR is returned, the application may then
473 call inflateSync() to look for a good compression block if a partial recovery
474 of the data is desired.
478 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
480 All dynamically allocated data structures for this stream are freed.
481 This function discards any unprocessed input and does not flush any
484 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
485 was inconsistent. In the error case, msg may be set but then points to a
486 static string (which must not be deallocated).
489 /* Advanced functions */
492 The following functions are needed only in some special applications.
496 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
503 This is another version of deflateInit with more compression options. The
504 fields next_in, zalloc, zfree and opaque must be initialized before by
507 The method parameter is the compression method. It must be Z_DEFLATED in
508 this version of the library.
510 The windowBits parameter is the base two logarithm of the window size
511 (the size of the history buffer). It should be in the range 8..15 for this
512 version of the library. Larger values of this parameter result in better
513 compression at the expense of memory usage. The default value is 15 if
514 deflateInit is used instead.
516 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
517 determines the window size. deflate() will then generate raw deflate data
518 with no zlib header or trailer, and will not compute an adler32 check value.
520 windowBits can also be greater than 15 for optional gzip encoding. Add
521 16 to windowBits to write a simple gzip header and trailer around the
522 compressed data instead of a zlib wrapper. The gzip header will have no
523 file name, no extra data, no comment, no modification time (set to zero),
524 no header crc, and the operating system will be set to 255 (unknown). If a
525 gzip stream is being written, strm->adler is a crc32 instead of an adler32.
527 The memLevel parameter specifies how much memory should be allocated
528 for the internal compression state. memLevel=1 uses minimum memory but
529 is slow and reduces compression ratio; memLevel=9 uses maximum memory
530 for optimal speed. The default value is 8. See zconf.h for total memory
531 usage as a function of windowBits and memLevel.
533 The strategy parameter is used to tune the compression algorithm. Use the
534 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
535 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
536 string match), or Z_RLE to limit match distances to one (run-length
537 encoding). Filtered data consists mostly of small values with a somewhat
538 random distribution. In this case, the compression algorithm is tuned to
539 compress them better. The effect of Z_FILTERED is to force more Huffman
540 coding and less string matching; it is somewhat intermediate between
541 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
542 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
543 parameter only affects the compression ratio but not the correctness of the
544 compressed output even if it is not set appropriately. Z_FIXED prevents the
545 use of dynamic Huffman codes, allowing for a simpler decoder for special
548 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
549 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
550 method). msg is set to null if there is no error message. deflateInit2 does
551 not perform any compression: this will be done by deflate().
554 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
555 const Bytef *dictionary,
558 Initializes the compression dictionary from the given byte sequence
559 without producing any compressed output. This function must be called
560 immediately after deflateInit, deflateInit2 or deflateReset, before any
561 call of deflate. The compressor and decompressor must use exactly the same
562 dictionary (see inflateSetDictionary).
564 The dictionary should consist of strings (byte sequences) that are likely
565 to be encountered later in the data to be compressed, with the most commonly
566 used strings preferably put towards the end of the dictionary. Using a
567 dictionary is most useful when the data to be compressed is short and can be
568 predicted with good accuracy; the data can then be compressed better than
569 with the default empty dictionary.
571 Depending on the size of the compression data structures selected by
572 deflateInit or deflateInit2, a part of the dictionary may in effect be
573 discarded, for example if the dictionary is larger than the window size in
574 deflate or deflate2. Thus the strings most likely to be useful should be
575 put at the end of the dictionary, not at the front. In addition, the
576 current implementation of deflate will use at most the window size minus
577 262 bytes of the provided dictionary.
579 Upon return of this function, strm->adler is set to the adler32 value
580 of the dictionary; the decompressor may later use this value to determine
581 which dictionary has been used by the compressor. (The adler32 value
582 applies to the whole dictionary even if only a subset of the dictionary is
583 actually used by the compressor.) If a raw deflate was requested, then the
584 adler32 value is not computed and strm->adler is not set.
586 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
587 parameter is invalid (such as NULL dictionary) or the stream state is
588 inconsistent (for example if deflate has already been called for this stream
589 or if the compression method is bsort). deflateSetDictionary does not
590 perform any compression: this will be done by deflate().
593 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
596 Sets the destination stream as a complete copy of the source stream.
598 This function can be useful when several compression strategies will be
599 tried, for example when there are several ways of pre-processing the input
600 data with a filter. The streams that will be discarded should then be freed
601 by calling deflateEnd. Note that deflateCopy duplicates the internal
602 compression state which can be quite large, so this strategy is slow and
603 can consume lots of memory.
605 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
606 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
607 (such as zalloc being NULL). msg is left unchanged in both source and
611 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
613 This function is equivalent to deflateEnd followed by deflateInit,
614 but does not free and reallocate all the internal compression state.
615 The stream will keep the same compression level and any other attributes
616 that may have been set by deflateInit2.
618 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
619 stream state was inconsistent (such as zalloc or state being NULL).
622 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
626 Dynamically update the compression level and compression strategy. The
627 interpretation of level and strategy is as in deflateInit2. This can be
628 used to switch between compression and straight copy of the input data, or
629 to switch to a different kind of input data requiring a different
630 strategy. If the compression level is changed, the input available so far
631 is compressed with the old level (and may be flushed); the new level will
632 take effect only at the next call of deflate().
634 Before the call of deflateParams, the stream state must be set as for
635 a call of deflate(), since the currently available input may have to
636 be compressed and flushed. In particular, strm->avail_out must be non-zero.
638 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
639 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
640 if strm->avail_out was zero.
643 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
649 Fine tune deflate's internal compression parameters. This should only be
650 used by someone who understands the algorithm used by zlib's deflate for
651 searching for the best matching string, and even then only by the most
652 fanatic optimizer trying to squeeze out the last compressed bit for their
653 specific input data. Read the deflate.c source code for the meaning of the
654 max_lazy, good_length, nice_length, and max_chain parameters.
656 deflateTune() can be called after deflateInit() or deflateInit2(), and
657 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
660 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
663 deflateBound() returns an upper bound on the compressed size after
664 deflation of sourceLen bytes. It must be called after deflateInit()
665 or deflateInit2(). This would be used to allocate an output buffer
666 for deflation in a single pass, and so would be called before deflate().
669 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
673 deflatePrime() inserts bits in the deflate output stream. The intent
674 is that this function is used to start off the deflate output with the
675 bits leftover from a previous deflate stream when appending to it. As such,
676 this function can only be used for raw deflate, and must be used before the
677 first deflate() call after a deflateInit2() or deflateReset(). bits must be
678 less than or equal to 16, and that many of the least significant bits of
679 value will be inserted in the output.
681 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
682 stream state was inconsistent.
685 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
688 deflateSetHeader() provides gzip header information for when a gzip
689 stream is requested by deflateInit2(). deflateSetHeader() may be called
690 after deflateInit2() or deflateReset() and before the first call of
691 deflate(). The text, time, os, extra field, name, and comment information
692 in the provided gz_header structure are written to the gzip header (xflag is
693 ignored -- the extra flags are set according to the compression level). The
694 caller must assure that, if not Z_NULL, name and comment are terminated with
695 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
696 available there. If hcrc is true, a gzip header crc is included. Note that
697 the current versions of the command-line version of gzip (up through version
698 1.3.x) do not support header crc's, and will report that it is a "multi-part
699 gzip file" and give up.
701 If deflateSetHeader is not used, the default gzip header has text false,
702 the time set to zero, and os set to 255, with no extra, name, or comment
703 fields. The gzip header is returned to the default state by deflateReset().
705 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
706 stream state was inconsistent.
710 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
713 This is another version of inflateInit with an extra parameter. The
714 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
715 before by the caller.
717 The windowBits parameter is the base two logarithm of the maximum window
718 size (the size of the history buffer). It should be in the range 8..15 for
719 this version of the library. The default value is 15 if inflateInit is used
720 instead. windowBits must be greater than or equal to the windowBits value
721 provided to deflateInit2() while compressing, or it must be equal to 15 if
722 deflateInit2() was not used. If a compressed stream with a larger window
723 size is given as input, inflate() will return with the error code
724 Z_DATA_ERROR instead of trying to allocate a larger window.
726 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
727 determines the window size. inflate() will then process raw deflate data,
728 not looking for a zlib or gzip header, not generating a check value, and not
729 looking for any check values for comparison at the end of the stream. This
730 is for use with other formats that use the deflate compressed data format
731 such as zip. Those formats provide their own check values. If a custom
732 format is developed using the raw deflate format for compressed data, it is
733 recommended that a check value such as an adler32 or a crc32 be applied to
734 the uncompressed data as is done in the zlib, gzip, and zip formats. For
735 most applications, the zlib format should be used as is. Note that comments
736 above on the use in deflateInit2() applies to the magnitude of windowBits.
738 windowBits can also be greater than 15 for optional gzip decoding. Add
739 32 to windowBits to enable zlib and gzip decoding with automatic header
740 detection, or add 16 to decode only the gzip format (the zlib format will
741 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
742 a crc32 instead of an adler32.
744 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
745 memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
746 is set to null if there is no error message. inflateInit2 does not perform
747 any decompression apart from reading the zlib header if present: this will
748 be done by inflate(). (So next_in and avail_in may be modified, but next_out
749 and avail_out are unchanged.)
752 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
753 const Bytef *dictionary,
756 Initializes the decompression dictionary from the given uncompressed byte
757 sequence. This function must be called immediately after a call of inflate,
758 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
759 can be determined from the adler32 value returned by that call of inflate.
760 The compressor and decompressor must use exactly the same dictionary (see
761 deflateSetDictionary). For raw inflate, this function can be called
762 immediately after inflateInit2() or inflateReset() and before any call of
763 inflate() to set the dictionary. The application must insure that the
764 dictionary that was used for compression is provided.
766 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
767 parameter is invalid (such as NULL dictionary) or the stream state is
768 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
769 expected one (incorrect adler32 value). inflateSetDictionary does not
770 perform any decompression: this will be done by subsequent calls of
774 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
776 Skips invalid compressed data until a full flush point (see above the
777 description of deflate with Z_FULL_FLUSH) can be found, or until all
778 available input is skipped. No output is provided.
780 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
781 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
782 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
783 case, the application may save the current current value of total_in which
784 indicates where valid compressed data was found. In the error case, the
785 application may repeatedly call inflateSync, providing more input each time,
786 until success or end of the input data.
789 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
792 Sets the destination stream as a complete copy of the source stream.
794 This function can be useful when randomly accessing a large stream. The
795 first pass through the stream can periodically record the inflate state,
796 allowing restarting inflate at those points when randomly accessing the
799 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
800 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
801 (such as zalloc being NULL). msg is left unchanged in both source and
805 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
807 This function is equivalent to inflateEnd followed by inflateInit,
808 but does not free and reallocate all the internal decompression state.
809 The stream will keep attributes that may have been set by inflateInit2.
811 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
812 stream state was inconsistent (such as zalloc or state being NULL).
815 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
819 This function inserts bits in the inflate input stream. The intent is
820 that this function is used to start inflating at a bit position in the
821 middle of a byte. The provided bits will be used before any bytes are used
822 from next_in. This function should only be used with raw inflate, and
823 should be used before the first inflate() call after inflateInit2() or
824 inflateReset(). bits must be less than or equal to 16, and that many of the
825 least significant bits of value will be inserted in the input.
827 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
828 stream state was inconsistent.
831 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
834 inflateGetHeader() requests that gzip header information be stored in the
835 provided gz_header structure. inflateGetHeader() may be called after
836 inflateInit2() or inflateReset(), and before the first call of inflate().
837 As inflate() processes the gzip stream, head->done is zero until the header
838 is completed, at which time head->done is set to one. If a zlib stream is
839 being decoded, then head->done is set to -1 to indicate that there will be
840 no gzip header information forthcoming. Note that Z_BLOCK can be used to
841 force inflate() to return immediately after header processing is complete
842 and before any actual data is decompressed.
844 The text, time, xflags, and os fields are filled in with the gzip header
845 contents. hcrc is set to true if there is a header CRC. (The header CRC
846 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
847 contains the maximum number of bytes to write to extra. Once done is true,
848 extra_len contains the actual extra field length, and extra contains the
849 extra field, or that field truncated if extra_max is less than extra_len.
850 If name is not Z_NULL, then up to name_max characters are written there,
851 terminated with a zero unless the length is greater than name_max. If
852 comment is not Z_NULL, then up to comm_max characters are written there,
853 terminated with a zero unless the length is greater than comm_max. When
854 any of extra, name, or comment are not Z_NULL and the respective field is
855 not present in the header, then that field is set to Z_NULL to signal its
856 absence. This allows the use of deflateSetHeader() with the returned
857 structure to duplicate the header. However if those fields are set to
858 allocated memory, then the application will need to save those pointers
859 elsewhere so that they can be eventually freed.
861 If inflateGetHeader is not used, then the header information is simply
862 discarded. The header is always checked for validity, including the header
863 CRC if present. inflateReset() will reset the process to discard the header
864 information. The application would need to call inflateGetHeader() again to
865 retrieve the header from the next gzip stream.
867 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
868 stream state was inconsistent.
872 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
873 unsigned char FAR *window));
875 Initialize the internal stream state for decompression using inflateBack()
876 calls. The fields zalloc, zfree and opaque in strm must be initialized
877 before the call. If zalloc and zfree are Z_NULL, then the default library-
878 derived memory allocation routines are used. windowBits is the base two
879 logarithm of the window size, in the range 8..15. window is a caller
880 supplied buffer of that size. Except for special applications where it is
881 assured that deflate was used with small window sizes, windowBits must be 15
882 and a 32K byte window must be supplied to be able to decompress general
885 See inflateBack() for the usage of these routines.
887 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
888 the paramaters are invalid, Z_MEM_ERROR if the internal state could not
889 be allocated, or Z_VERSION_ERROR if the version of the library does not
890 match the version of the header file.
893 typedef unsigned (*in_func) OF((void FAR *, unsigned const char FAR * FAR *));
894 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
896 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
897 in_func in, void FAR *in_desc,
898 out_func out, void FAR *out_desc));
900 inflateBack() does a raw inflate with a single call using a call-back
901 interface for input and output. This is more efficient than inflate() for
902 file i/o applications in that it avoids copying between the output and the
903 sliding window by simply making the window itself the output buffer. This
904 function trusts the application to not change the output buffer passed by
905 the output function, at least until inflateBack() returns.
907 inflateBackInit() must be called first to allocate the internal state
908 and to initialize the state with the user-provided window buffer.
909 inflateBack() may then be used multiple times to inflate a complete, raw
910 deflate stream with each call. inflateBackEnd() is then called to free
913 A raw deflate stream is one with no zlib or gzip header or trailer.
914 This routine would normally be used in a utility that reads zip or gzip
915 files and writes out uncompressed files. The utility would decode the
916 header and process the trailer on its own, hence this routine expects
917 only the raw deflate stream to decompress. This is different from the
918 normal behavior of inflate(), which expects either a zlib or gzip header and
919 trailer around the deflate stream.
921 inflateBack() uses two subroutines supplied by the caller that are then
922 called by inflateBack() for input and output. inflateBack() calls those
923 routines until it reads a complete deflate stream and writes out all of the
924 uncompressed data, or until it encounters an error. The function's
925 parameters and return types are defined above in the in_func and out_func
926 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
927 number of bytes of provided input, and a pointer to that input in buf. If
928 there is no input available, in() must return zero--buf is ignored in that
929 case--and inflateBack() will return a buffer error. inflateBack() will call
930 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
931 should return zero on success, or non-zero on failure. If out() returns
932 non-zero, inflateBack() will return with an error. Neither in() nor out()
933 are permitted to change the contents of the window provided to
934 inflateBackInit(), which is also the buffer that out() uses to write from.
935 The length written by out() will be at most the window size. Any non-zero
936 amount of input may be provided by in().
938 For convenience, inflateBack() can be provided input on the first call by
939 setting strm->next_in and strm->avail_in. If that input is exhausted, then
940 in() will be called. Therefore strm->next_in must be initialized before
941 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
942 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
943 must also be initialized, and then if strm->avail_in is not zero, input will
944 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
946 The in_desc and out_desc parameters of inflateBack() is passed as the
947 first parameter of in() and out() respectively when they are called. These
948 descriptors can be optionally used to pass any information that the caller-
949 supplied in() and out() functions need to do their job.
951 On return, inflateBack() will set strm->next_in and strm->avail_in to
952 pass back any unused input that was provided by the last in() call. The
953 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
954 if in() or out() returned an error, Z_DATA_ERROR if there was a format
955 error in the deflate stream (in which case strm->msg is set to indicate the
956 nature of the error), or Z_STREAM_ERROR if the stream was not properly
957 initialized. In the case of Z_BUF_ERROR, an input or output error can be
958 distinguished using strm->next_in which will be Z_NULL only if in() returned
959 an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
960 out() returning non-zero. (in() will always be called before out(), so
961 strm->next_in is assured to be defined if out() returns non-zero.) Note
962 that inflateBack() cannot return Z_OK.
965 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
967 All memory allocated by inflateBackInit() is freed.
969 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
970 state was inconsistent.
973 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
974 /* Return flags indicating compile-time options.
976 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
979 5.4: size of voidpf (pointer)
982 Compiler, assembler, and debug options:
984 9: ASMV or ASMINF -- use ASM code
985 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
988 One-time table building (smaller code, but not thread-safe if true):
989 12: BUILDFIXED -- build static block decoding tables when needed
990 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
993 Library content (indicates missing functionality):
994 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
995 deflate code when not needed)
996 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
997 and decode gzip streams (to avoid linking crc code)
1000 Operation variations (changes in library functionality):
1001 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1002 21: FASTEST -- deflate algorithm with only one, lowest compression level
1005 The sprintf variant used by gzprintf (zero is best):
1006 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1007 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1008 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1015 /* utility functions */
1018 The following utility functions are implemented on top of the
1019 basic stream-oriented functions. To simplify the interface, some
1020 default options are assumed (compression level and memory usage,
1021 standard memory allocation functions). The source code of these
1022 utility functions can easily be modified if you need special options.
1025 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1026 const Bytef *source, uLong sourceLen));
1028 Compresses the source buffer into the destination buffer. sourceLen is
1029 the byte length of the source buffer. Upon entry, destLen is the total
1030 size of the destination buffer, which must be at least the value returned
1031 by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1033 This function can be used to compress a whole file at once if the
1034 input file is mmap'ed.
1035 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1036 enough memory, Z_BUF_ERROR if there was not enough room in the output
1040 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1041 const Bytef *source, uLong sourceLen,
1044 Compresses the source buffer into the destination buffer. The level
1045 parameter has the same meaning as in deflateInit. sourceLen is the byte
1046 length of the source buffer. Upon entry, destLen is the total size of the
1047 destination buffer, which must be at least the value returned by
1048 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1051 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1052 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1053 Z_STREAM_ERROR if the level parameter is invalid.
1056 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1058 compressBound() returns an upper bound on the compressed size after
1059 compress() or compress2() on sourceLen bytes. It would be used before
1060 a compress() or compress2() call to allocate the destination buffer.
1063 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1064 const Bytef *source, uLong sourceLen));
1066 Decompresses the source buffer into the destination buffer. sourceLen is
1067 the byte length of the source buffer. Upon entry, destLen is the total
1068 size of the destination buffer, which must be large enough to hold the
1069 entire uncompressed data. (The size of the uncompressed data must have
1070 been saved previously by the compressor and transmitted to the decompressor
1071 by some mechanism outside the scope of this compression library.)
1072 Upon exit, destLen is the actual size of the compressed buffer.
1073 This function can be used to decompress a whole file at once if the
1074 input file is mmap'ed.
1076 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1077 enough memory, Z_BUF_ERROR if there was not enough room in the output
1078 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1082 typedef voidp gzFile;
1084 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1086 Opens a gzip (.gz) file for reading or writing. The mode parameter
1087 is as in fopen ("rb" or "wb") but can also include a compression level
1088 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1089 Huffman only compression as in "wb1h", or 'R' for run-length encoding
1090 as in "wb1R". (See the description of deflateInit2 for more information
1091 about the strategy parameter.)
1093 gzopen can be used to read a file which is not in gzip format; in this
1094 case gzread will directly read from the file without decompression.
1096 gzopen returns NULL if the file could not be opened or if there was
1097 insufficient memory to allocate the (de)compression state; errno
1098 can be checked to distinguish the two cases (if errno is zero, the
1099 zlib error is Z_MEM_ERROR). */
1101 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1103 gzdopen() associates a gzFile with the file descriptor fd. File
1104 descriptors are obtained from calls like open, dup, creat, pipe or
1105 fileno (in the file has been previously opened with fopen).
1106 The mode parameter is as in gzopen.
1107 The next call of gzclose on the returned gzFile will also close the
1108 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1109 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1110 gzdopen returns NULL if there was insufficient memory to allocate
1111 the (de)compression state.
1114 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1116 Dynamically update the compression level or strategy. See the description
1117 of deflateInit2 for the meaning of these parameters.
1118 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1122 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1124 Reads the given number of uncompressed bytes from the compressed file.
1125 If the input file was not in gzip format, gzread copies the given number
1126 of bytes into the buffer.
1127 gzread returns the number of uncompressed bytes actually read (0 for
1128 end of file, -1 for error). */
1130 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1131 voidpc buf, unsigned len));
1133 Writes the given number of uncompressed bytes into the compressed file.
1134 gzwrite returns the number of uncompressed bytes actually written
1135 (0 in case of error).
1138 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...))
1139 _Z_PRINTF_ATTRIBUTE(2, 3);
1141 Converts, formats, and writes the args to the compressed file under
1142 control of the format string, as in fprintf. gzprintf returns the number of
1143 uncompressed bytes actually written (0 in case of error). The number of
1144 uncompressed bytes written is limited to 4095. The caller should assure that
1145 this limit is not exceeded. If it is exceeded, then gzprintf() will return
1146 return an error (0) with nothing written. In this case, there may also be a
1147 buffer overflow with unpredictable consequences, which is possible only if
1148 zlib was compiled with the insecure functions sprintf() or vsprintf()
1149 because the secure snprintf() or vsnprintf() functions were not available.
1152 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1154 Writes the given null-terminated string to the compressed file, excluding
1155 the terminating null character.
1156 gzputs returns the number of characters written, or -1 in case of error.
1159 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1161 Reads bytes from the compressed file until len-1 characters are read, or
1162 a newline character is read and transferred to buf, or an end-of-file
1163 condition is encountered. The string is then terminated with a null
1165 gzgets returns buf, or Z_NULL in case of error.
1168 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1170 Writes c, converted to an unsigned char, into the compressed file.
1171 gzputc returns the value that was written, or -1 in case of error.
1174 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1176 Reads one byte from the compressed file. gzgetc returns this byte
1177 or -1 in case of end of file or error.
1180 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1182 Push one character back onto the stream to be read again later.
1183 Only one character of push-back is allowed. gzungetc() returns the
1184 character pushed, or -1 on failure. gzungetc() will fail if a
1185 character has been pushed but not read yet, or if c is -1. The pushed
1186 character will be discarded if the stream is repositioned with gzseek()
1190 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1192 Flushes all pending output into the compressed file. The parameter
1193 flush is as in the deflate() function. The return value is the zlib
1194 error number (see function gzerror below). gzflush returns Z_OK if
1195 the flush parameter is Z_FINISH and all output could be flushed.
1196 gzflush should be called only when strictly necessary because it can
1197 degrade compression.
1200 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1201 z_off_t offset, int whence));
1203 Sets the starting position for the next gzread or gzwrite on the
1204 given compressed file. The offset represents a number of bytes in the
1205 uncompressed data stream. The whence parameter is defined as in lseek(2);
1206 the value SEEK_END is not supported.
1207 If the file is opened for reading, this function is emulated but can be
1208 extremely slow. If the file is opened for writing, only forward seeks are
1209 supported; gzseek then compresses a sequence of zeroes up to the new
1212 gzseek returns the resulting offset location as measured in bytes from
1213 the beginning of the uncompressed stream, or -1 in case of error, in
1214 particular if the file is opened for writing and the new starting position
1215 would be before the current position.
1218 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1220 Rewinds the given file. This function is supported only for reading.
1222 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1225 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1227 Returns the starting position for the next gzread or gzwrite on the
1228 given compressed file. This position represents a number of bytes in the
1229 uncompressed data stream.
1231 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1234 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1236 Returns 1 when EOF has previously been detected reading the given
1237 input stream, otherwise zero.
1240 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1242 Returns 1 if file is being read directly without decompression, otherwise
1246 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1248 Flushes all pending output if necessary, closes the compressed file
1249 and deallocates all the (de)compression state. The return value is the zlib
1250 error number (see function gzerror below).
1253 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1255 Returns the error message for the last error which occurred on the
1256 given compressed file. errnum is set to zlib error number. If an
1257 error occurred in the file system and not in the compression library,
1258 errnum is set to Z_ERRNO and the application may consult errno
1259 to get the exact error code.
1262 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1264 Clears the error and end-of-file flags for file. This is analogous to the
1265 clearerr() function in stdio. This is useful for continuing to read a gzip
1266 file that is being written concurrently.
1269 /* checksum functions */
1272 These functions are not related to compression but are exported
1273 anyway because they might be useful in applications using the
1274 compression library.
1277 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1279 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1280 return the updated checksum. If buf is NULL, this function returns
1281 the required initial value for the checksum.
1282 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1283 much faster. Usage example:
1285 uLong adler = adler32(0L, Z_NULL, 0);
1287 while (read_buffer(buffer, length) != EOF) {
1288 adler = adler32(adler, buffer, length);
1290 if (adler != original_adler) error();
1293 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1296 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1297 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1298 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1299 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1302 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1304 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1305 updated CRC-32. If buf is NULL, this function returns the required initial
1306 value for the for the crc. Pre- and post-conditioning (one's complement) is
1307 performed within this function so it shouldn't be done by the application.
1310 uLong crc = crc32(0L, Z_NULL, 0);
1312 while (read_buffer(buffer, length) != EOF) {
1313 crc = crc32(crc, buffer, length);
1315 if (crc != original_crc) error();
1318 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1321 Combine two CRC-32 check values into one. For two sequences of bytes,
1322 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1323 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1324 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1329 /* various hacks, don't look :) */
1331 /* deflateInit and inflateInit are macros to allow checking the zlib version
1332 * and the compiler's view of z_stream:
1334 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1335 const char *version, int stream_size));
1336 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1337 const char *version, int stream_size));
1338 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1339 int windowBits, int memLevel,
1340 int strategy, const char *version,
1342 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1343 const char *version, int stream_size));
1344 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1345 unsigned char FAR *window,
1346 const char *version,
1348 #define deflateInit(strm, level) \
1349 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1350 #define inflateInit(strm) \
1351 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1352 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1353 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1354 (strategy), ZLIB_VERSION, sizeof(z_stream))
1355 #define inflateInit2(strm, windowBits) \
1356 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1357 #define inflateBackInit(strm, windowBits, window) \
1358 inflateBackInit_((strm), (windowBits), (window), \
1359 ZLIB_VERSION, sizeof(z_stream))
1362 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1363 struct internal_state {int dummy;}; /* hack for buggy compilers */
1366 ZEXTERN const char * ZEXPORT zError OF((int));
1367 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1368 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
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