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"
41 #define ZLIB_VERNUM 0x1230
44 The 'zlib' compression library provides in-memory compression and
45 decompression functions, including integrity checks of the uncompressed
46 data. This version of the library supports only one compression method
47 (deflation) but other algorithms will be added later and will have the same
50 Compression can be done in a single step if the buffers are large
51 enough (for example if an input file is mmap'ed), or can be done by
52 repeated calls of the compression function. In the latter case, the
53 application must provide more input and/or consume the output
54 (providing more output space) before each call.
56 The compressed data format used by default by the in-memory functions is
57 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
58 around a deflate stream, which is itself documented in RFC 1951.
60 The library also supports reading and writing files in gzip (.gz) format
61 with an interface similar to that of stdio using the functions that start
62 with "gz". The gzip format is different from the zlib format. gzip is a
63 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
65 This library can optionally read and write gzip streams in memory as well.
67 The zlib format was designed to be compact and fast for use in memory
68 and on communications channels. The gzip format was designed for single-
69 file compression on file systems, has a larger header than zlib to maintain
70 directory information, and uses a different, slower check method than zlib.
72 The library does not install any signal handler. The decoder checks
73 the consistency of the compressed data, so the library should never
74 crash even in case of corrupted input.
77 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
78 typedef void (*free_func) OF((voidpf opaque, voidpf address));
80 struct internal_state;
82 typedef struct z_stream_s {
83 Bytef *next_in; /* next input byte */
84 uInt avail_in; /* number of bytes available at next_in */
85 uLong total_in; /* total nb of input bytes read so far */
87 Bytef *next_out; /* next output byte should be put there */
88 uInt avail_out; /* remaining free space at next_out */
89 uLong total_out; /* total nb of bytes output so far */
91 char *msg; /* last error message, NULL if no error */
92 struct internal_state FAR *state; /* not visible by applications */
94 alloc_func zalloc; /* used to allocate the internal state */
95 free_func zfree; /* used to free the internal state */
96 voidpf opaque; /* private data object passed to zalloc and zfree */
98 int data_type; /* best guess about the data type: binary or text */
99 uLong adler; /* adler32 value of the uncompressed data */
100 uLong reserved; /* reserved for future use */
103 typedef z_stream FAR *z_streamp;
106 gzip header information passed to and from zlib routines. See RFC 1952
107 for more details on the meanings of these fields.
109 typedef struct gz_header_s {
110 int text; /* true if compressed data believed to be text */
111 uLong time; /* modification time */
112 int xflags; /* extra flags (not used when writing a gzip file) */
113 int os; /* operating system */
114 Bytef *extra; /* pointer to extra field or Z_NULL if none */
115 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
116 uInt extra_max; /* space at extra (only when reading header) */
117 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
118 uInt name_max; /* space at name (only when reading header) */
119 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
120 uInt comm_max; /* space at comment (only when reading header) */
121 int hcrc; /* true if there was or will be a header crc */
122 int done; /* true when done reading gzip header (not used
123 when writing a gzip file) */
126 typedef gz_header FAR *gz_headerp;
129 The application must update next_in and avail_in when avail_in has
130 dropped to zero. It must update next_out and avail_out when avail_out
131 has dropped to zero. The application must initialize zalloc, zfree and
132 opaque before calling the init function. All other fields are set by the
133 compression library and must not be updated by the application.
135 The opaque value provided by the application will be passed as the first
136 parameter for calls of zalloc and zfree. This can be useful for custom
137 memory management. The compression library attaches no meaning to the
140 zalloc must return Z_NULL if there is not enough memory for the object.
141 If zlib is used in a multi-threaded application, zalloc and zfree must be
144 On 16-bit systems, the functions zalloc and zfree must be able to allocate
145 exactly 65536 bytes, but will not be required to allocate more than this
146 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
147 pointers returned by zalloc for objects of exactly 65536 bytes *must*
148 have their offset normalized to zero. The default allocation function
149 provided by this library ensures this (see zutil.c). To reduce memory
150 requirements and avoid any allocation of 64K objects, at the expense of
151 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
153 The fields total_in and total_out can be used for statistics or
154 progress reports. After compression, total_in holds the total size of
155 the uncompressed data and may be saved for use in the decompressor
156 (particularly if the decompressor wants to decompress everything in
163 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
164 #define Z_SYNC_FLUSH 2
165 #define Z_FULL_FLUSH 3
168 /* Allowed flush values; see deflate() and inflate() below for details */
171 #define Z_STREAM_END 1
172 #define Z_NEED_DICT 2
174 #define Z_STREAM_ERROR (-2)
175 #define Z_DATA_ERROR (-3)
176 #define Z_MEM_ERROR (-4)
177 #define Z_BUF_ERROR (-5)
178 #define Z_VERSION_ERROR (-6)
179 /* Return codes for the compression/decompression functions. Negative
180 * values are errors, positive values are used for special but normal events.
183 #define Z_NO_COMPRESSION 0
184 #define Z_BEST_SPEED 1
185 #define Z_BEST_COMPRESSION 9
186 #define Z_DEFAULT_COMPRESSION (-1)
187 /* compression levels */
190 #define Z_HUFFMAN_ONLY 2
193 #define Z_DEFAULT_STRATEGY 0
194 /* compression strategy; see deflateInit2() below for details */
198 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
200 /* Possible values of the data_type field (though see inflate()) */
203 /* The deflate compression method (the only one supported in this version) */
205 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
207 #define zlib_version zlibVersion()
208 /* for compatibility with versions < 1.0.2 */
210 /* basic functions */
212 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
213 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
214 If the first character differs, the library code actually used is
215 not compatible with the zlib.h header file used by the application.
216 This check is automatically made by deflateInit and inflateInit.
220 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
222 Initializes the internal stream state for compression. The fields
223 zalloc, zfree and opaque must be initialized before by the caller.
224 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
225 use default allocation functions.
227 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
228 1 gives best speed, 9 gives best compression, 0 gives no compression at
229 all (the input data is simply copied a block at a time).
230 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
231 compression (currently equivalent to level 6).
233 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
234 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
235 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
236 with the version assumed by the caller (ZLIB_VERSION).
237 msg is set to null if there is no error message. deflateInit does not
238 perform any compression: this will be done by deflate().
242 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
244 deflate compresses as much data as possible, and stops when the input
245 buffer becomes empty or the output buffer becomes full. It may introduce some
246 output latency (reading input without producing any output) except when
249 The detailed semantics are as follows. deflate performs one or both of the
252 - Compress more input starting at next_in and update next_in and avail_in
253 accordingly. If not all input can be processed (because there is not
254 enough room in the output buffer), next_in and avail_in are updated and
255 processing will resume at this point for the next call of deflate().
257 - Provide more output starting at next_out and update next_out and avail_out
258 accordingly. This action is forced if the parameter flush is non zero.
259 Forcing flush frequently degrades the compression ratio, so this parameter
260 should be set only when necessary (in interactive applications).
261 Some output may be provided even if flush is not set.
263 Before the call of deflate(), the application should ensure that at least
264 one of the actions is possible, by providing more input and/or consuming
265 more output, and updating avail_in or avail_out accordingly; avail_out
266 should never be zero before the call. The application can consume the
267 compressed output when it wants, for example when the output buffer is full
268 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
269 and with zero avail_out, it must be called again after making room in the
270 output buffer because there might be more output pending.
272 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
273 decide how much data to accumualte before producing output, in order to
274 maximize compression.
276 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
277 flushed to the output buffer and the output is aligned on a byte boundary, so
278 that the decompressor can get all input data available so far. (In particular
279 avail_in is zero after the call if enough output space has been provided
280 before the call.) Flushing may degrade compression for some compression
281 algorithms and so it should be used only when necessary.
283 If flush is set to Z_FULL_FLUSH, all output is flushed as with
284 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
285 restart from this point if previous compressed data has been damaged or if
286 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
289 If deflate returns with avail_out == 0, this function must be called again
290 with the same value of the flush parameter and more output space (updated
291 avail_out), until the flush is complete (deflate returns with non-zero
292 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
293 avail_out is greater than six to avoid repeated flush markers due to
294 avail_out == 0 on return.
296 If the parameter flush is set to Z_FINISH, pending input is processed,
297 pending output is flushed and deflate returns with Z_STREAM_END if there
298 was enough output space; if deflate returns with Z_OK, this function must be
299 called again with Z_FINISH and more output space (updated avail_out) but no
300 more input data, until it returns with Z_STREAM_END or an error. After
301 deflate has returned Z_STREAM_END, the only possible operations on the
302 stream are deflateReset or deflateEnd.
304 Z_FINISH can be used immediately after deflateInit if all the compression
305 is to be done in a single step. In this case, avail_out must be at least
306 the value returned by deflateBound (see below). If deflate does not return
307 Z_STREAM_END, then it must be called again as described above.
309 deflate() sets strm->adler to the adler32 checksum of all input read
310 so far (that is, total_in bytes).
312 deflate() may update strm->data_type if it can make a good guess about
313 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
314 binary. This field is only for information purposes and does not affect
315 the compression algorithm in any manner.
317 deflate() returns Z_OK if some progress has been made (more input
318 processed or more output produced), Z_STREAM_END if all input has been
319 consumed and all output has been produced (only when flush is set to
320 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
321 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
322 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
323 fatal, and deflate() can be called again with more input and more output
324 space to continue compressing.
328 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
330 All dynamically allocated data structures for this stream are freed.
331 This function discards any unprocessed input and does not flush any
334 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
335 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
336 prematurely (some input or output was discarded). In the error case,
337 msg may be set but then points to a static string (which must not be
343 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
345 Initializes the internal stream state for decompression. The fields
346 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
347 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
348 value depends on the compression method), inflateInit determines the
349 compression method from the zlib header and allocates all data structures
350 accordingly; otherwise the allocation will be deferred to the first call of
351 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
352 use default allocation functions.
354 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
355 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
356 version assumed by the caller. msg is set to null if there is no error
357 message. inflateInit does not perform any decompression apart from reading
358 the zlib header if present: this will be done by inflate(). (So next_in and
359 avail_in may be modified, but next_out and avail_out are unchanged.)
363 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
365 inflate decompresses as much data as possible, and stops when the input
366 buffer becomes empty or the output buffer becomes full. It may introduce
367 some output latency (reading input without producing any output) except when
370 The detailed semantics are as follows. inflate performs one or both of the
373 - Decompress more input starting at next_in and update next_in and avail_in
374 accordingly. If not all input can be processed (because there is not
375 enough room in the output buffer), next_in is updated and processing
376 will resume at this point for the next call of inflate().
378 - Provide more output starting at next_out and update next_out and avail_out
379 accordingly. inflate() provides as much output as possible, until there
380 is no more input data or no more space in the output buffer (see below
381 about the flush parameter).
383 Before the call of inflate(), the application should ensure that at least
384 one of the actions is possible, by providing more input and/or consuming
385 more output, and updating the next_* and avail_* values accordingly.
386 The application can consume the uncompressed output when it wants, for
387 example when the output buffer is full (avail_out == 0), or after each
388 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
389 must be called again after making room in the output buffer because there
390 might be more output pending.
392 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
393 Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
394 output as possible to the output buffer. Z_BLOCK requests that inflate() stop
395 if and when it gets to the next deflate block boundary. When decoding the
396 zlib or gzip format, this will cause inflate() to return immediately after
397 the header and before the first block. When doing a raw inflate, inflate()
398 will go ahead and process the first block, and will return when it gets to
399 the end of that block, or when it runs out of data.
401 The Z_BLOCK option assists in appending to or combining deflate streams.
402 Also to assist in this, on return inflate() will set strm->data_type to the
403 number of unused bits in the last byte taken from strm->next_in, plus 64
404 if inflate() is currently decoding the last block in the deflate stream,
405 plus 128 if inflate() returned immediately after decoding an end-of-block
406 code or decoding the complete header up to just before the first byte of the
407 deflate stream. The end-of-block will not be indicated until all of the
408 uncompressed data from that block has been written to strm->next_out. The
409 number of unused bits may in general be greater than seven, except when
410 bit 7 of data_type is set, in which case the number of unused bits will be
413 inflate() should normally be called until it returns Z_STREAM_END or an
414 error. However if all decompression is to be performed in a single step
415 (a single call of inflate), the parameter flush should be set to
416 Z_FINISH. In this case all pending input is processed and all pending
417 output is flushed; avail_out must be large enough to hold all the
418 uncompressed data. (The size of the uncompressed data may have been saved
419 by the compressor for this purpose.) The next operation on this stream must
420 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
421 is never required, but can be used to inform inflate that a faster approach
422 may be used for the single inflate() call.
424 In this implementation, inflate() always flushes as much output as
425 possible to the output buffer, and always uses the faster approach on the
426 first call. So the only effect of the flush parameter in this implementation
427 is on the return value of inflate(), as noted below, or when it returns early
428 because Z_BLOCK is used.
430 If a preset dictionary is needed after this call (see inflateSetDictionary
431 below), inflate sets strm->adler to the adler32 checksum of the dictionary
432 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
433 strm->adler to the adler32 checksum of all output produced so far (that is,
434 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
435 below. At the end of the stream, inflate() checks that its computed adler32
436 checksum is equal to that saved by the compressor and returns Z_STREAM_END
437 only if the checksum is correct.
439 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
440 deflate data. The header type is detected automatically. Any information
441 contained in the gzip header is not retained, so applications that need that
442 information should instead use raw inflate, see inflateInit2() below, or
443 inflateBack() and perform their own processing of the gzip header and
446 inflate() returns Z_OK if some progress has been made (more input processed
447 or more output produced), Z_STREAM_END if the end of the compressed data has
448 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
449 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
450 corrupted (input stream not conforming to the zlib format or incorrect check
451 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
452 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
453 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
454 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
455 inflate() can be called again with more input and more output space to
456 continue decompressing. If Z_DATA_ERROR is returned, the application may then
457 call inflateSync() to look for a good compression block if a partial recovery
458 of the data is desired.
462 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
464 All dynamically allocated data structures for this stream are freed.
465 This function discards any unprocessed input and does not flush any
468 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
469 was inconsistent. In the error case, msg may be set but then points to a
470 static string (which must not be deallocated).
473 /* Advanced functions */
476 The following functions are needed only in some special applications.
480 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
487 This is another version of deflateInit with more compression options. The
488 fields next_in, zalloc, zfree and opaque must be initialized before by
491 The method parameter is the compression method. It must be Z_DEFLATED in
492 this version of the library.
494 The windowBits parameter is the base two logarithm of the window size
495 (the size of the history buffer). It should be in the range 8..15 for this
496 version of the library. Larger values of this parameter result in better
497 compression at the expense of memory usage. The default value is 15 if
498 deflateInit is used instead.
500 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
501 determines the window size. deflate() will then generate raw deflate data
502 with no zlib header or trailer, and will not compute an adler32 check value.
504 windowBits can also be greater than 15 for optional gzip encoding. Add
505 16 to windowBits to write a simple gzip header and trailer around the
506 compressed data instead of a zlib wrapper. The gzip header will have no
507 file name, no extra data, no comment, no modification time (set to zero),
508 no header crc, and the operating system will be set to 255 (unknown). If a
509 gzip stream is being written, strm->adler is a crc32 instead of an adler32.
511 The memLevel parameter specifies how much memory should be allocated
512 for the internal compression state. memLevel=1 uses minimum memory but
513 is slow and reduces compression ratio; memLevel=9 uses maximum memory
514 for optimal speed. The default value is 8. See zconf.h for total memory
515 usage as a function of windowBits and memLevel.
517 The strategy parameter is used to tune the compression algorithm. Use the
518 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
519 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
520 string match), or Z_RLE to limit match distances to one (run-length
521 encoding). Filtered data consists mostly of small values with a somewhat
522 random distribution. In this case, the compression algorithm is tuned to
523 compress them better. The effect of Z_FILTERED is to force more Huffman
524 coding and less string matching; it is somewhat intermediate between
525 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
526 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
527 parameter only affects the compression ratio but not the correctness of the
528 compressed output even if it is not set appropriately. Z_FIXED prevents the
529 use of dynamic Huffman codes, allowing for a simpler decoder for special
532 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
533 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
534 method). msg is set to null if there is no error message. deflateInit2 does
535 not perform any compression: this will be done by deflate().
538 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
539 const Bytef *dictionary,
542 Initializes the compression dictionary from the given byte sequence
543 without producing any compressed output. This function must be called
544 immediately after deflateInit, deflateInit2 or deflateReset, before any
545 call of deflate. The compressor and decompressor must use exactly the same
546 dictionary (see inflateSetDictionary).
548 The dictionary should consist of strings (byte sequences) that are likely
549 to be encountered later in the data to be compressed, with the most commonly
550 used strings preferably put towards the end of the dictionary. Using a
551 dictionary is most useful when the data to be compressed is short and can be
552 predicted with good accuracy; the data can then be compressed better than
553 with the default empty dictionary.
555 Depending on the size of the compression data structures selected by
556 deflateInit or deflateInit2, a part of the dictionary may in effect be
557 discarded, for example if the dictionary is larger than the window size in
558 deflate or deflate2. Thus the strings most likely to be useful should be
559 put at the end of the dictionary, not at the front. In addition, the
560 current implementation of deflate will use at most the window size minus
561 262 bytes of the provided dictionary.
563 Upon return of this function, strm->adler is set to the adler32 value
564 of the dictionary; the decompressor may later use this value to determine
565 which dictionary has been used by the compressor. (The adler32 value
566 applies to the whole dictionary even if only a subset of the dictionary is
567 actually used by the compressor.) If a raw deflate was requested, then the
568 adler32 value is not computed and strm->adler is not set.
570 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
571 parameter is invalid (such as NULL dictionary) or the stream state is
572 inconsistent (for example if deflate has already been called for this stream
573 or if the compression method is bsort). deflateSetDictionary does not
574 perform any compression: this will be done by deflate().
577 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
580 Sets the destination stream as a complete copy of the source stream.
582 This function can be useful when several compression strategies will be
583 tried, for example when there are several ways of pre-processing the input
584 data with a filter. The streams that will be discarded should then be freed
585 by calling deflateEnd. Note that deflateCopy duplicates the internal
586 compression state which can be quite large, so this strategy is slow and
587 can consume lots of memory.
589 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
590 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
591 (such as zalloc being NULL). msg is left unchanged in both source and
595 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
597 This function is equivalent to deflateEnd followed by deflateInit,
598 but does not free and reallocate all the internal compression state.
599 The stream will keep the same compression level and any other attributes
600 that may have been set by deflateInit2.
602 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
603 stream state was inconsistent (such as zalloc or state being NULL).
606 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
610 Dynamically update the compression level and compression strategy. The
611 interpretation of level and strategy is as in deflateInit2. This can be
612 used to switch between compression and straight copy of the input data, or
613 to switch to a different kind of input data requiring a different
614 strategy. If the compression level is changed, the input available so far
615 is compressed with the old level (and may be flushed); the new level will
616 take effect only at the next call of deflate().
618 Before the call of deflateParams, the stream state must be set as for
619 a call of deflate(), since the currently available input may have to
620 be compressed and flushed. In particular, strm->avail_out must be non-zero.
622 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
623 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
624 if strm->avail_out was zero.
627 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
633 Fine tune deflate's internal compression parameters. This should only be
634 used by someone who understands the algorithm used by zlib's deflate for
635 searching for the best matching string, and even then only by the most
636 fanatic optimizer trying to squeeze out the last compressed bit for their
637 specific input data. Read the deflate.c source code for the meaning of the
638 max_lazy, good_length, nice_length, and max_chain parameters.
640 deflateTune() can be called after deflateInit() or deflateInit2(), and
641 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
644 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
647 deflateBound() returns an upper bound on the compressed size after
648 deflation of sourceLen bytes. It must be called after deflateInit()
649 or deflateInit2(). This would be used to allocate an output buffer
650 for deflation in a single pass, and so would be called before deflate().
653 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
657 deflatePrime() inserts bits in the deflate output stream. The intent
658 is that this function is used to start off the deflate output with the
659 bits leftover from a previous deflate stream when appending to it. As such,
660 this function can only be used for raw deflate, and must be used before the
661 first deflate() call after a deflateInit2() or deflateReset(). bits must be
662 less than or equal to 16, and that many of the least significant bits of
663 value will be inserted in the output.
665 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
666 stream state was inconsistent.
669 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
672 deflateSetHeader() provides gzip header information for when a gzip
673 stream is requested by deflateInit2(). deflateSetHeader() may be called
674 after deflateInit2() or deflateReset() and before the first call of
675 deflate(). The text, time, os, extra field, name, and comment information
676 in the provided gz_header structure are written to the gzip header (xflag is
677 ignored -- the extra flags are set according to the compression level). The
678 caller must assure that, if not Z_NULL, name and comment are terminated with
679 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
680 available there. If hcrc is true, a gzip header crc is included. Note that
681 the current versions of the command-line version of gzip (up through version
682 1.3.x) do not support header crc's, and will report that it is a "multi-part
683 gzip file" and give up.
685 If deflateSetHeader is not used, the default gzip header has text false,
686 the time set to zero, and os set to 255, with no extra, name, or comment
687 fields. The gzip header is returned to the default state by deflateReset().
689 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
690 stream state was inconsistent.
694 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
697 This is another version of inflateInit with an extra parameter. The
698 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
699 before by the caller.
701 The windowBits parameter is the base two logarithm of the maximum window
702 size (the size of the history buffer). It should be in the range 8..15 for
703 this version of the library. The default value is 15 if inflateInit is used
704 instead. windowBits must be greater than or equal to the windowBits value
705 provided to deflateInit2() while compressing, or it must be equal to 15 if
706 deflateInit2() was not used. If a compressed stream with a larger window
707 size is given as input, inflate() will return with the error code
708 Z_DATA_ERROR instead of trying to allocate a larger window.
710 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
711 determines the window size. inflate() will then process raw deflate data,
712 not looking for a zlib or gzip header, not generating a check value, and not
713 looking for any check values for comparison at the end of the stream. This
714 is for use with other formats that use the deflate compressed data format
715 such as zip. Those formats provide their own check values. If a custom
716 format is developed using the raw deflate format for compressed data, it is
717 recommended that a check value such as an adler32 or a crc32 be applied to
718 the uncompressed data as is done in the zlib, gzip, and zip formats. For
719 most applications, the zlib format should be used as is. Note that comments
720 above on the use in deflateInit2() applies to the magnitude of windowBits.
722 windowBits can also be greater than 15 for optional gzip decoding. Add
723 32 to windowBits to enable zlib and gzip decoding with automatic header
724 detection, or add 16 to decode only the gzip format (the zlib format will
725 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
726 a crc32 instead of an adler32.
728 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
729 memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
730 is set to null if there is no error message. inflateInit2 does not perform
731 any decompression apart from reading the zlib header if present: this will
732 be done by inflate(). (So next_in and avail_in may be modified, but next_out
733 and avail_out are unchanged.)
736 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
737 const Bytef *dictionary,
740 Initializes the decompression dictionary from the given uncompressed byte
741 sequence. This function must be called immediately after a call of inflate,
742 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
743 can be determined from the adler32 value returned by that call of inflate.
744 The compressor and decompressor must use exactly the same dictionary (see
745 deflateSetDictionary). For raw inflate, this function can be called
746 immediately after inflateInit2() or inflateReset() and before any call of
747 inflate() to set the dictionary. The application must insure that the
748 dictionary that was used for compression is provided.
750 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
751 parameter is invalid (such as NULL dictionary) or the stream state is
752 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
753 expected one (incorrect adler32 value). inflateSetDictionary does not
754 perform any decompression: this will be done by subsequent calls of
758 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
760 Skips invalid compressed data until a full flush point (see above the
761 description of deflate with Z_FULL_FLUSH) can be found, or until all
762 available input is skipped. No output is provided.
764 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
765 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
766 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
767 case, the application may save the current current value of total_in which
768 indicates where valid compressed data was found. In the error case, the
769 application may repeatedly call inflateSync, providing more input each time,
770 until success or end of the input data.
773 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
776 Sets the destination stream as a complete copy of the source stream.
778 This function can be useful when randomly accessing a large stream. The
779 first pass through the stream can periodically record the inflate state,
780 allowing restarting inflate at those points when randomly accessing the
783 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
784 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
785 (such as zalloc being NULL). msg is left unchanged in both source and
789 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
791 This function is equivalent to inflateEnd followed by inflateInit,
792 but does not free and reallocate all the internal decompression state.
793 The stream will keep attributes that may have been set by inflateInit2.
795 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
796 stream state was inconsistent (such as zalloc or state being NULL).
799 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
803 This function inserts bits in the inflate input stream. The intent is
804 that this function is used to start inflating at a bit position in the
805 middle of a byte. The provided bits will be used before any bytes are used
806 from next_in. This function should only be used with raw inflate, and
807 should be used before the first inflate() call after inflateInit2() or
808 inflateReset(). bits must be less than or equal to 16, and that many of the
809 least significant bits of value will be inserted in the input.
811 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
812 stream state was inconsistent.
815 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
818 inflateGetHeader() requests that gzip header information be stored in the
819 provided gz_header structure. inflateGetHeader() may be called after
820 inflateInit2() or inflateReset(), and before the first call of inflate().
821 As inflate() processes the gzip stream, head->done is zero until the header
822 is completed, at which time head->done is set to one. If a zlib stream is
823 being decoded, then head->done is set to -1 to indicate that there will be
824 no gzip header information forthcoming. Note that Z_BLOCK can be used to
825 force inflate() to return immediately after header processing is complete
826 and before any actual data is decompressed.
828 The text, time, xflags, and os fields are filled in with the gzip header
829 contents. hcrc is set to true if there is a header CRC. (The header CRC
830 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
831 contains the maximum number of bytes to write to extra. Once done is true,
832 extra_len contains the actual extra field length, and extra contains the
833 extra field, or that field truncated if extra_max is less than extra_len.
834 If name is not Z_NULL, then up to name_max characters are written there,
835 terminated with a zero unless the length is greater than name_max. If
836 comment is not Z_NULL, then up to comm_max characters are written there,
837 terminated with a zero unless the length is greater than comm_max. When
838 any of extra, name, or comment are not Z_NULL and the respective field is
839 not present in the header, then that field is set to Z_NULL to signal its
840 absence. This allows the use of deflateSetHeader() with the returned
841 structure to duplicate the header. However if those fields are set to
842 allocated memory, then the application will need to save those pointers
843 elsewhere so that they can be eventually freed.
845 If inflateGetHeader is not used, then the header information is simply
846 discarded. The header is always checked for validity, including the header
847 CRC if present. inflateReset() will reset the process to discard the header
848 information. The application would need to call inflateGetHeader() again to
849 retrieve the header from the next gzip stream.
851 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
852 stream state was inconsistent.
856 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
857 unsigned char FAR *window));
859 Initialize the internal stream state for decompression using inflateBack()
860 calls. The fields zalloc, zfree and opaque in strm must be initialized
861 before the call. If zalloc and zfree are Z_NULL, then the default library-
862 derived memory allocation routines are used. windowBits is the base two
863 logarithm of the window size, in the range 8..15. window is a caller
864 supplied buffer of that size. Except for special applications where it is
865 assured that deflate was used with small window sizes, windowBits must be 15
866 and a 32K byte window must be supplied to be able to decompress general
869 See inflateBack() for the usage of these routines.
871 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
872 the paramaters are invalid, Z_MEM_ERROR if the internal state could not
873 be allocated, or Z_VERSION_ERROR if the version of the library does not
874 match the version of the header file.
877 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
878 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
880 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
881 in_func in, void FAR *in_desc,
882 out_func out, void FAR *out_desc));
884 inflateBack() does a raw inflate with a single call using a call-back
885 interface for input and output. This is more efficient than inflate() for
886 file i/o applications in that it avoids copying between the output and the
887 sliding window by simply making the window itself the output buffer. This
888 function trusts the application to not change the output buffer passed by
889 the output function, at least until inflateBack() returns.
891 inflateBackInit() must be called first to allocate the internal state
892 and to initialize the state with the user-provided window buffer.
893 inflateBack() may then be used multiple times to inflate a complete, raw
894 deflate stream with each call. inflateBackEnd() is then called to free
897 A raw deflate stream is one with no zlib or gzip header or trailer.
898 This routine would normally be used in a utility that reads zip or gzip
899 files and writes out uncompressed files. The utility would decode the
900 header and process the trailer on its own, hence this routine expects
901 only the raw deflate stream to decompress. This is different from the
902 normal behavior of inflate(), which expects either a zlib or gzip header and
903 trailer around the deflate stream.
905 inflateBack() uses two subroutines supplied by the caller that are then
906 called by inflateBack() for input and output. inflateBack() calls those
907 routines until it reads a complete deflate stream and writes out all of the
908 uncompressed data, or until it encounters an error. The function's
909 parameters and return types are defined above in the in_func and out_func
910 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
911 number of bytes of provided input, and a pointer to that input in buf. If
912 there is no input available, in() must return zero--buf is ignored in that
913 case--and inflateBack() will return a buffer error. inflateBack() will call
914 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
915 should return zero on success, or non-zero on failure. If out() returns
916 non-zero, inflateBack() will return with an error. Neither in() nor out()
917 are permitted to change the contents of the window provided to
918 inflateBackInit(), which is also the buffer that out() uses to write from.
919 The length written by out() will be at most the window size. Any non-zero
920 amount of input may be provided by in().
922 For convenience, inflateBack() can be provided input on the first call by
923 setting strm->next_in and strm->avail_in. If that input is exhausted, then
924 in() will be called. Therefore strm->next_in must be initialized before
925 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
926 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
927 must also be initialized, and then if strm->avail_in is not zero, input will
928 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
930 The in_desc and out_desc parameters of inflateBack() is passed as the
931 first parameter of in() and out() respectively when they are called. These
932 descriptors can be optionally used to pass any information that the caller-
933 supplied in() and out() functions need to do their job.
935 On return, inflateBack() will set strm->next_in and strm->avail_in to
936 pass back any unused input that was provided by the last in() call. The
937 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
938 if in() or out() returned an error, Z_DATA_ERROR if there was a format
939 error in the deflate stream (in which case strm->msg is set to indicate the
940 nature of the error), or Z_STREAM_ERROR if the stream was not properly
941 initialized. In the case of Z_BUF_ERROR, an input or output error can be
942 distinguished using strm->next_in which will be Z_NULL only if in() returned
943 an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
944 out() returning non-zero. (in() will always be called before out(), so
945 strm->next_in is assured to be defined if out() returns non-zero.) Note
946 that inflateBack() cannot return Z_OK.
949 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
951 All memory allocated by inflateBackInit() is freed.
953 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
954 state was inconsistent.
957 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
958 /* Return flags indicating compile-time options.
960 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
963 5.4: size of voidpf (pointer)
966 Compiler, assembler, and debug options:
968 9: ASMV or ASMINF -- use ASM code
969 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
972 One-time table building (smaller code, but not thread-safe if true):
973 12: BUILDFIXED -- build static block decoding tables when needed
974 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
977 Library content (indicates missing functionality):
978 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
979 deflate code when not needed)
980 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
981 and decode gzip streams (to avoid linking crc code)
984 Operation variations (changes in library functionality):
985 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
986 21: FASTEST -- deflate algorithm with only one, lowest compression level
989 The sprintf variant used by gzprintf (zero is best):
990 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
991 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
992 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
999 /* utility functions */
1002 The following utility functions are implemented on top of the
1003 basic stream-oriented functions. To simplify the interface, some
1004 default options are assumed (compression level and memory usage,
1005 standard memory allocation functions). The source code of these
1006 utility functions can easily be modified if you need special options.
1009 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1010 const Bytef *source, uLong sourceLen));
1012 Compresses the source buffer into the destination buffer. sourceLen is
1013 the byte length of the source buffer. Upon entry, destLen is the total
1014 size of the destination buffer, which must be at least the value returned
1015 by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1017 This function can be used to compress a whole file at once if the
1018 input file is mmap'ed.
1019 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1020 enough memory, Z_BUF_ERROR if there was not enough room in the output
1024 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1025 const Bytef *source, uLong sourceLen,
1028 Compresses the source buffer into the destination buffer. The level
1029 parameter has the same meaning as in deflateInit. sourceLen is the byte
1030 length of the source buffer. Upon entry, destLen is the total size of the
1031 destination buffer, which must be at least the value returned by
1032 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1035 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1036 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1037 Z_STREAM_ERROR if the level parameter is invalid.
1040 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1042 compressBound() returns an upper bound on the compressed size after
1043 compress() or compress2() on sourceLen bytes. It would be used before
1044 a compress() or compress2() call to allocate the destination buffer.
1047 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1048 const Bytef *source, uLong sourceLen));
1050 Decompresses the source buffer into the destination buffer. sourceLen is
1051 the byte length of the source buffer. Upon entry, destLen is the total
1052 size of the destination buffer, which must be large enough to hold the
1053 entire uncompressed data. (The size of the uncompressed data must have
1054 been saved previously by the compressor and transmitted to the decompressor
1055 by some mechanism outside the scope of this compression library.)
1056 Upon exit, destLen is the actual size of the compressed buffer.
1057 This function can be used to decompress a whole file at once if the
1058 input file is mmap'ed.
1060 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1061 enough memory, Z_BUF_ERROR if there was not enough room in the output
1062 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1066 typedef voidp gzFile;
1068 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1070 Opens a gzip (.gz) file for reading or writing. The mode parameter
1071 is as in fopen ("rb" or "wb") but can also include a compression level
1072 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1073 Huffman only compression as in "wb1h", or 'R' for run-length encoding
1074 as in "wb1R". (See the description of deflateInit2 for more information
1075 about the strategy parameter.)
1077 gzopen can be used to read a file which is not in gzip format; in this
1078 case gzread will directly read from the file without decompression.
1080 gzopen returns NULL if the file could not be opened or if there was
1081 insufficient memory to allocate the (de)compression state; errno
1082 can be checked to distinguish the two cases (if errno is zero, the
1083 zlib error is Z_MEM_ERROR). */
1085 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1087 gzdopen() associates a gzFile with the file descriptor fd. File
1088 descriptors are obtained from calls like open, dup, creat, pipe or
1089 fileno (in the file has been previously opened with fopen).
1090 The mode parameter is as in gzopen.
1091 The next call of gzclose on the returned gzFile will also close the
1092 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1093 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1094 gzdopen returns NULL if there was insufficient memory to allocate
1095 the (de)compression state.
1098 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1100 Dynamically update the compression level or strategy. See the description
1101 of deflateInit2 for the meaning of these parameters.
1102 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1106 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1108 Reads the given number of uncompressed bytes from the compressed file.
1109 If the input file was not in gzip format, gzread copies the given number
1110 of bytes into the buffer.
1111 gzread returns the number of uncompressed bytes actually read (0 for
1112 end of file, -1 for error). */
1114 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1115 voidpc buf, unsigned len));
1117 Writes the given number of uncompressed bytes into the compressed file.
1118 gzwrite returns the number of uncompressed bytes actually written
1119 (0 in case of error).
1122 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
1124 Converts, formats, and writes the args to the compressed file under
1125 control of the format string, as in fprintf. gzprintf returns the number of
1126 uncompressed bytes actually written (0 in case of error). The number of
1127 uncompressed bytes written is limited to 4095. The caller should assure that
1128 this limit is not exceeded. If it is exceeded, then gzprintf() will return
1129 return an error (0) with nothing written. In this case, there may also be a
1130 buffer overflow with unpredictable consequences, which is possible only if
1131 zlib was compiled with the insecure functions sprintf() or vsprintf()
1132 because the secure snprintf() or vsnprintf() functions were not available.
1135 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1137 Writes the given null-terminated string to the compressed file, excluding
1138 the terminating null character.
1139 gzputs returns the number of characters written, or -1 in case of error.
1142 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1144 Reads bytes from the compressed file until len-1 characters are read, or
1145 a newline character is read and transferred to buf, or an end-of-file
1146 condition is encountered. The string is then terminated with a null
1148 gzgets returns buf, or Z_NULL in case of error.
1151 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1153 Writes c, converted to an unsigned char, into the compressed file.
1154 gzputc returns the value that was written, or -1 in case of error.
1157 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1159 Reads one byte from the compressed file. gzgetc returns this byte
1160 or -1 in case of end of file or error.
1163 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1165 Push one character back onto the stream to be read again later.
1166 Only one character of push-back is allowed. gzungetc() returns the
1167 character pushed, or -1 on failure. gzungetc() will fail if a
1168 character has been pushed but not read yet, or if c is -1. The pushed
1169 character will be discarded if the stream is repositioned with gzseek()
1173 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1175 Flushes all pending output into the compressed file. The parameter
1176 flush is as in the deflate() function. The return value is the zlib
1177 error number (see function gzerror below). gzflush returns Z_OK if
1178 the flush parameter is Z_FINISH and all output could be flushed.
1179 gzflush should be called only when strictly necessary because it can
1180 degrade compression.
1183 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1184 z_off_t offset, int whence));
1186 Sets the starting position for the next gzread or gzwrite on the
1187 given compressed file. The offset represents a number of bytes in the
1188 uncompressed data stream. The whence parameter is defined as in lseek(2);
1189 the value SEEK_END is not supported.
1190 If the file is opened for reading, this function is emulated but can be
1191 extremely slow. If the file is opened for writing, only forward seeks are
1192 supported; gzseek then compresses a sequence of zeroes up to the new
1195 gzseek returns the resulting offset location as measured in bytes from
1196 the beginning of the uncompressed stream, or -1 in case of error, in
1197 particular if the file is opened for writing and the new starting position
1198 would be before the current position.
1201 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1203 Rewinds the given file. This function is supported only for reading.
1205 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1208 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1210 Returns the starting position for the next gzread or gzwrite on the
1211 given compressed file. This position represents a number of bytes in the
1212 uncompressed data stream.
1214 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1217 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1219 Returns 1 when EOF has previously been detected reading the given
1220 input stream, otherwise zero.
1223 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1225 Returns 1 if file is being read directly without decompression, otherwise
1229 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1231 Flushes all pending output if necessary, closes the compressed file
1232 and deallocates all the (de)compression state. The return value is the zlib
1233 error number (see function gzerror below).
1236 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1238 Returns the error message for the last error which occurred on the
1239 given compressed file. errnum is set to zlib error number. If an
1240 error occurred in the file system and not in the compression library,
1241 errnum is set to Z_ERRNO and the application may consult errno
1242 to get the exact error code.
1245 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1247 Clears the error and end-of-file flags for file. This is analogous to the
1248 clearerr() function in stdio. This is useful for continuing to read a gzip
1249 file that is being written concurrently.
1252 /* checksum functions */
1255 These functions are not related to compression but are exported
1256 anyway because they might be useful in applications using the
1257 compression library.
1260 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1262 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1263 return the updated checksum. If buf is NULL, this function returns
1264 the required initial value for the checksum.
1265 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1266 much faster. Usage example:
1268 uLong adler = adler32(0L, Z_NULL, 0);
1270 while (read_buffer(buffer, length) != EOF) {
1271 adler = adler32(adler, buffer, length);
1273 if (adler != original_adler) error();
1276 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1279 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1280 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1281 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1282 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1285 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1287 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1288 updated CRC-32. If buf is NULL, this function returns the required initial
1289 value for the for the crc. Pre- and post-conditioning (one's complement) is
1290 performed within this function so it shouldn't be done by the application.
1293 uLong crc = crc32(0L, Z_NULL, 0);
1295 while (read_buffer(buffer, length) != EOF) {
1296 crc = crc32(crc, buffer, length);
1298 if (crc != original_crc) error();
1301 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1304 Combine two CRC-32 check values into one. For two sequences of bytes,
1305 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1306 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1307 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1312 /* various hacks, don't look :) */
1314 /* deflateInit and inflateInit are macros to allow checking the zlib version
1315 * and the compiler's view of z_stream:
1317 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1318 const char *version, int stream_size));
1319 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1320 const char *version, int stream_size));
1321 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1322 int windowBits, int memLevel,
1323 int strategy, const char *version,
1325 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1326 const char *version, int stream_size));
1327 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1328 unsigned char FAR *window,
1329 const char *version,
1331 #define deflateInit(strm, level) \
1332 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1333 #define inflateInit(strm) \
1334 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1335 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1336 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1337 (strategy), ZLIB_VERSION, sizeof(z_stream))
1338 #define inflateInit2(strm, windowBits) \
1339 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1340 #define inflateBackInit(strm, windowBits, window) \
1341 inflateBackInit_((strm), (windowBits), (window), \
1342 ZLIB_VERSION, sizeof(z_stream))
1345 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1346 struct internal_state {int dummy;}; /* hack for buggy compilers */
1349 ZEXTERN const char * ZEXPORT zError OF((int));
1350 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1351 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
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