source: NonGTP/Zlib/include/zlib.h @ 178

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1/* zlib.h -- interface of the 'zlib' general purpose compression library
2  version 1.2.1, November 17th, 2003
3
4  Copyright (C) 1995-2003 Jean-loup Gailly and Mark Adler
5
6  This software is provided 'as-is', without any express or implied
7  warranty.  In no event will the authors be held liable for any damages
8  arising from the use of this software.
9
10  Permission is granted to anyone to use this software for any purpose,
11  including commercial applications, and to alter it and redistribute it
12  freely, subject to the following restrictions:
13
14  1. The origin of this software must not be misrepresented; you must not
15     claim that you wrote the original software. If you use this software
16     in a product, an acknowledgment in the product documentation would be
17     appreciated but is not required.
18  2. Altered source versions must be plainly marked as such, and must not be
19     misrepresented as being the original software.
20  3. This notice may not be removed or altered from any source distribution.
21
22  Jean-loup Gailly        Mark Adler
23  jloup@gzip.org          madler@alumni.caltech.edu
24
25
26  The data format used by the zlib library is described by RFCs (Request for
27  Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
28  (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
29*/
30
31#ifndef ZLIB_H
32#define ZLIB_H
33
34#include "zconf.h"
35
36#ifdef __cplusplus
37extern "C" {
38#endif
39
40#define ZLIB_VERSION "1.2.1"
41#define ZLIB_VERNUM 0x1210
42
43/*
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
48  stream interface.
49
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.
55
56     The compressed data format used by the in-memory functions is the zlib
57  format, which is a zlib wrapper documented in RFC 1950, wrapped around a
58  deflate stream, which is itself documented in RFC 1951.
59
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.
64
65     The zlib format was designed to be compact and fast for use in memory
66  and on communications channels.  The gzip format was designed for single-
67  file compression on file systems, has a larger header than zlib to maintain
68  directory information, and uses a different, slower check method than zlib.
69
70     This library does not provide any functions to write gzip files in memory.
71  However such functions could be easily written using zlib's deflate function,
72  the documentation in the gzip RFC, and the examples in gzio.c.
73
74     The library does not install any signal handler. The decoder checks
75  the consistency of the compressed data, so the library should never
76  crash even in case of corrupted input.
77*/
78
79typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
80typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
81
82struct internal_state;
83
84typedef struct z_stream_s {
85    Bytef    *next_in;  /* next input byte */
86    uInt     avail_in;  /* number of bytes available at next_in */
87    uLong    total_in;  /* total nb of input bytes read so far */
88
89    Bytef    *next_out; /* next output byte should be put there */
90    uInt     avail_out; /* remaining free space at next_out */
91    uLong    total_out; /* total nb of bytes output so far */
92
93    char     *msg;      /* last error message, NULL if no error */
94    struct internal_state FAR *state; /* not visible by applications */
95
96    alloc_func zalloc;  /* used to allocate the internal state */
97    free_func  zfree;   /* used to free the internal state */
98    voidpf     opaque;  /* private data object passed to zalloc and zfree */
99
100    int     data_type;  /* best guess about the data type: ascii or binary */
101    uLong   adler;      /* adler32 value of the uncompressed data */
102    uLong   reserved;   /* reserved for future use */
103} z_stream;
104
105typedef z_stream FAR *z_streamp;
106
107/*
108   The application must update next_in and avail_in when avail_in has
109   dropped to zero. It must update next_out and avail_out when avail_out
110   has dropped to zero. The application must initialize zalloc, zfree and
111   opaque before calling the init function. All other fields are set by the
112   compression library and must not be updated by the application.
113
114   The opaque value provided by the application will be passed as the first
115   parameter for calls of zalloc and zfree. This can be useful for custom
116   memory management. The compression library attaches no meaning to the
117   opaque value.
118
119   zalloc must return Z_NULL if there is not enough memory for the object.
120   If zlib is used in a multi-threaded application, zalloc and zfree must be
121   thread safe.
122
123   On 16-bit systems, the functions zalloc and zfree must be able to allocate
124   exactly 65536 bytes, but will not be required to allocate more than this
125   if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
126   pointers returned by zalloc for objects of exactly 65536 bytes *must*
127   have their offset normalized to zero. The default allocation function
128   provided by this library ensures this (see zutil.c). To reduce memory
129   requirements and avoid any allocation of 64K objects, at the expense of
130   compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
131
132   The fields total_in and total_out can be used for statistics or
133   progress reports. After compression, total_in holds the total size of
134   the uncompressed data and may be saved for use in the decompressor
135   (particularly if the decompressor wants to decompress everything in
136   a single step).
137*/
138
139                        /* constants */
140
141#define Z_NO_FLUSH      0
142#define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
143#define Z_SYNC_FLUSH    2
144#define Z_FULL_FLUSH    3
145#define Z_FINISH        4
146#define Z_BLOCK         5
147/* Allowed flush values; see deflate() and inflate() below for details */
148
149#define Z_OK            0
150#define Z_STREAM_END    1
151#define Z_NEED_DICT     2
152#define Z_ERRNO        (-1)
153#define Z_STREAM_ERROR (-2)
154#define Z_DATA_ERROR   (-3)
155#define Z_MEM_ERROR    (-4)
156#define Z_BUF_ERROR    (-5)
157#define Z_VERSION_ERROR (-6)
158/* Return codes for the compression/decompression functions. Negative
159 * values are errors, positive values are used for special but normal events.
160 */
161
162#define Z_NO_COMPRESSION         0
163#define Z_BEST_SPEED             1
164#define Z_BEST_COMPRESSION       9
165#define Z_DEFAULT_COMPRESSION  (-1)
166/* compression levels */
167
168#define Z_FILTERED            1
169#define Z_HUFFMAN_ONLY        2
170#define Z_RLE                 3
171#define Z_DEFAULT_STRATEGY    0
172/* compression strategy; see deflateInit2() below for details */
173
174#define Z_BINARY   0
175#define Z_ASCII    1
176#define Z_UNKNOWN  2
177/* Possible values of the data_type field (though see inflate()) */
178
179#define Z_DEFLATED   8
180/* The deflate compression method (the only one supported in this version) */
181
182#define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
183
184#define zlib_version zlibVersion()
185/* for compatibility with versions < 1.0.2 */
186
187                        /* basic functions */
188
189ZEXTERN const char * ZEXPORT zlibVersion OF((void));
190/* The application can compare zlibVersion and ZLIB_VERSION for consistency.
191   If the first character differs, the library code actually used is
192   not compatible with the zlib.h header file used by the application.
193   This check is automatically made by deflateInit and inflateInit.
194 */
195
196/*
197ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
198
199     Initializes the internal stream state for compression. The fields
200   zalloc, zfree and opaque must be initialized before by the caller.
201   If zalloc and zfree are set to Z_NULL, deflateInit updates them to
202   use default allocation functions.
203
204     The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
205   1 gives best speed, 9 gives best compression, 0 gives no compression at
206   all (the input data is simply copied a block at a time).
207   Z_DEFAULT_COMPRESSION requests a default compromise between speed and
208   compression (currently equivalent to level 6).
209
210     deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
211   enough memory, Z_STREAM_ERROR if level is not a valid compression level,
212   Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
213   with the version assumed by the caller (ZLIB_VERSION).
214   msg is set to null if there is no error message.  deflateInit does not
215   perform any compression: this will be done by deflate().
216*/
217
218
219ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
220/*
221    deflate compresses as much data as possible, and stops when the input
222  buffer becomes empty or the output buffer becomes full. It may introduce some
223  output latency (reading input without producing any output) except when
224  forced to flush.
225
226    The detailed semantics are as follows. deflate performs one or both of the
227  following actions:
228
229  - Compress more input starting at next_in and update next_in and avail_in
230    accordingly. If not all input can be processed (because there is not
231    enough room in the output buffer), next_in and avail_in are updated and
232    processing will resume at this point for the next call of deflate().
233
234  - Provide more output starting at next_out and update next_out and avail_out
235    accordingly. This action is forced if the parameter flush is non zero.
236    Forcing flush frequently degrades the compression ratio, so this parameter
237    should be set only when necessary (in interactive applications).
238    Some output may be provided even if flush is not set.
239
240  Before the call of deflate(), the application should ensure that at least
241  one of the actions is possible, by providing more input and/or consuming
242  more output, and updating avail_in or avail_out accordingly; avail_out
243  should never be zero before the call. The application can consume the
244  compressed output when it wants, for example when the output buffer is full
245  (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
246  and with zero avail_out, it must be called again after making room in the
247  output buffer because there might be more output pending.
248
249    If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
250  flushed to the output buffer and the output is aligned on a byte boundary, so
251  that the decompressor can get all input data available so far. (In particular
252  avail_in is zero after the call if enough output space has been provided
253  before the call.)  Flushing may degrade compression for some compression
254  algorithms and so it should be used only when necessary.
255
256    If flush is set to Z_FULL_FLUSH, all output is flushed as with
257  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
258  restart from this point if previous compressed data has been damaged or if
259  random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
260  the compression.
261
262    If deflate returns with avail_out == 0, this function must be called again
263  with the same value of the flush parameter and more output space (updated
264  avail_out), until the flush is complete (deflate returns with non-zero
265  avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
266  avail_out is greater than six to avoid repeated flush markers due to
267  avail_out == 0 on return.
268
269    If the parameter flush is set to Z_FINISH, pending input is processed,
270  pending output is flushed and deflate returns with Z_STREAM_END if there
271  was enough output space; if deflate returns with Z_OK, this function must be
272  called again with Z_FINISH and more output space (updated avail_out) but no
273  more input data, until it returns with Z_STREAM_END or an error. After
274  deflate has returned Z_STREAM_END, the only possible operations on the
275  stream are deflateReset or deflateEnd.
276
277    Z_FINISH can be used immediately after deflateInit if all the compression
278  is to be done in a single step. In this case, avail_out must be at least
279  the value returned by deflateBound (see below). If deflate does not return
280  Z_STREAM_END, then it must be called again as described above.
281
282    deflate() sets strm->adler to the adler32 checksum of all input read
283  so far (that is, total_in bytes).
284
285    deflate() may update data_type if it can make a good guess about
286  the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
287  binary. This field is only for information purposes and does not affect
288  the compression algorithm in any manner.
289
290    deflate() returns Z_OK if some progress has been made (more input
291  processed or more output produced), Z_STREAM_END if all input has been
292  consumed and all output has been produced (only when flush is set to
293  Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
294  if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
295  (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
296  fatal, and deflate() can be called again with more input and more output
297  space to continue compressing.
298*/
299
300
301ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
302/*
303     All dynamically allocated data structures for this stream are freed.
304   This function discards any unprocessed input and does not flush any
305   pending output.
306
307     deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
308   stream state was inconsistent, Z_DATA_ERROR if the stream was freed
309   prematurely (some input or output was discarded). In the error case,
310   msg may be set but then points to a static string (which must not be
311   deallocated).
312*/
313
314
315/*
316ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
317
318     Initializes the internal stream state for decompression. The fields
319   next_in, avail_in, zalloc, zfree and opaque must be initialized before by
320   the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
321   value depends on the compression method), inflateInit determines the
322   compression method from the zlib header and allocates all data structures
323   accordingly; otherwise the allocation will be deferred to the first call of
324   inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
325   use default allocation functions.
326
327     inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
328   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
329   version assumed by the caller.  msg is set to null if there is no error
330   message. inflateInit does not perform any decompression apart from reading
331   the zlib header if present: this will be done by inflate().  (So next_in and
332   avail_in may be modified, but next_out and avail_out are unchanged.)
333*/
334
335
336ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
337/*
338    inflate decompresses as much data as possible, and stops when the input
339  buffer becomes empty or the output buffer becomes full. It may introduce
340  some output latency (reading input without producing any output) except when
341  forced to flush.
342
343  The detailed semantics are as follows. inflate performs one or both of the
344  following actions:
345
346  - Decompress more input starting at next_in and update next_in and avail_in
347    accordingly. If not all input can be processed (because there is not
348    enough room in the output buffer), next_in is updated and processing
349    will resume at this point for the next call of inflate().
350
351  - Provide more output starting at next_out and update next_out and avail_out
352    accordingly.  inflate() provides as much output as possible, until there
353    is no more input data or no more space in the output buffer (see below
354    about the flush parameter).
355
356  Before the call of inflate(), the application should ensure that at least
357  one of the actions is possible, by providing more input and/or consuming
358  more output, and updating the next_* and avail_* values accordingly.
359  The application can consume the uncompressed output when it wants, for
360  example when the output buffer is full (avail_out == 0), or after each
361  call of inflate(). If inflate returns Z_OK and with zero avail_out, it
362  must be called again after making room in the output buffer because there
363  might be more output pending.
364
365    The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
366  Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
367  output as possible to the output buffer. Z_BLOCK requests that inflate() stop
368  if and when it get to the next deflate block boundary. When decoding the zlib
369  or gzip format, this will cause inflate() to return immediately after the
370  header and before the first block. When doing a raw inflate, inflate() will
371  go ahead and process the first block, and will return when it gets to the end
372  of that block, or when it runs out of data.
373
374    The Z_BLOCK option assists in appending to or combining deflate streams.
375  Also to assist in this, on return inflate() will set strm->data_type to the
376  number of unused bits in the last byte taken from strm->next_in, plus 64
377  if inflate() is currently decoding the last block in the deflate stream,
378  plus 128 if inflate() returned immediately after decoding an end-of-block
379  code or decoding the complete header up to just before the first byte of the
380  deflate stream. The end-of-block will not be indicated until all of the
381  uncompressed data from that block has been written to strm->next_out.  The
382  number of unused bits may in general be greater than seven, except when
383  bit 7 of data_type is set, in which case the number of unused bits will be
384  less than eight.
385
386    inflate() should normally be called until it returns Z_STREAM_END or an
387  error. However if all decompression is to be performed in a single step
388  (a single call of inflate), the parameter flush should be set to
389  Z_FINISH. In this case all pending input is processed and all pending
390  output is flushed; avail_out must be large enough to hold all the
391  uncompressed data. (The size of the uncompressed data may have been saved
392  by the compressor for this purpose.) The next operation on this stream must
393  be inflateEnd to deallocate the decompression state. The use of Z_FINISH
394  is never required, but can be used to inform inflate that a faster approach
395  may be used for the single inflate() call.
396
397     In this implementation, inflate() always flushes as much output as
398  possible to the output buffer, and always uses the faster approach on the
399  first call. So the only effect of the flush parameter in this implementation
400  is on the return value of inflate(), as noted below, or when it returns early
401  because Z_BLOCK is used.
402
403     If a preset dictionary is needed after this call (see inflateSetDictionary
404  below), inflate sets strm-adler to the adler32 checksum of the dictionary
405  chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
406  strm->adler to the adler32 checksum of all output produced so far (that is,
407  total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
408  below. At the end of the stream, inflate() checks that its computed adler32
409  checksum is equal to that saved by the compressor and returns Z_STREAM_END
410  only if the checksum is correct.
411
412    inflate() will decompress and check either zlib-wrapped or gzip-wrapped
413  deflate data.  The header type is detected automatically.  Any information
414  contained in the gzip header is not retained, so applications that need that
415  information should instead use raw inflate, see inflateInit2() below, or
416  inflateBack() and perform their own processing of the gzip header and
417  trailer.
418
419    inflate() returns Z_OK if some progress has been made (more input processed
420  or more output produced), Z_STREAM_END if the end of the compressed data has
421  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
422  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
423  corrupted (input stream not conforming to the zlib format or incorrect check
424  value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
425  if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
426  Z_BUF_ERROR if no progress is possible or if there was not enough room in the
427  output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
428  inflate() can be called again with more input and more output space to
429  continue decompressing. If Z_DATA_ERROR is returned, the application may then
430  call inflateSync() to look for a good compression block if a partial recovery
431  of the data is desired.
432*/
433
434
435ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
436/*
437     All dynamically allocated data structures for this stream are freed.
438   This function discards any unprocessed input and does not flush any
439   pending output.
440
441     inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
442   was inconsistent. In the error case, msg may be set but then points to a
443   static string (which must not be deallocated).
444*/
445
446                        /* Advanced functions */
447
448/*
449    The following functions are needed only in some special applications.
450*/
451
452/*
453ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
454                                     int  level,
455                                     int  method,
456                                     int  windowBits,
457                                     int  memLevel,
458                                     int  strategy));
459
460     This is another version of deflateInit with more compression options. The
461   fields next_in, zalloc, zfree and opaque must be initialized before by
462   the caller.
463
464     The method parameter is the compression method. It must be Z_DEFLATED in
465   this version of the library.
466
467     The windowBits parameter is the base two logarithm of the window size
468   (the size of the history buffer). It should be in the range 8..15 for this
469   version of the library. Larger values of this parameter result in better
470   compression at the expense of memory usage. The default value is 15 if
471   deflateInit is used instead.
472
473     windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
474   determines the window size. deflate() will then generate raw deflate data
475   with no zlib header or trailer, and will not compute an adler32 check value.
476
477     windowBits can also be greater than 15 for optional gzip encoding. Add
478   16 to windowBits to write a simple gzip header and trailer around the
479   compressed data instead of a zlib wrapper. The gzip header will have no
480   file name, no extra data, no comment, no modification time (set to zero),
481   no header crc, and the operating system will be set to 255 (unknown).
482
483     The memLevel parameter specifies how much memory should be allocated
484   for the internal compression state. memLevel=1 uses minimum memory but
485   is slow and reduces compression ratio; memLevel=9 uses maximum memory
486   for optimal speed. The default value is 8. See zconf.h for total memory
487   usage as a function of windowBits and memLevel.
488
489     The strategy parameter is used to tune the compression algorithm. Use the
490   value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
491   filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
492   string match), or Z_RLE to limit match distances to one (run-length
493   encoding). Filtered data consists mostly of small values with a somewhat
494   random distribution. In this case, the compression algorithm is tuned to
495   compress them better. The effect of Z_FILTERED is to force more Huffman
496   coding and less string matching; it is somewhat intermediate between
497   Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
498   Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
499   parameter only affects the compression ratio but not the correctness of the
500   compressed output even if it is not set appropriately.
501
502      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
503   memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
504   method). msg is set to null if there is no error message.  deflateInit2 does
505   not perform any compression: this will be done by deflate().
506*/
507
508ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
509                                             const Bytef *dictionary,
510                                             uInt  dictLength));
511/*
512     Initializes the compression dictionary from the given byte sequence
513   without producing any compressed output. This function must be called
514   immediately after deflateInit, deflateInit2 or deflateReset, before any
515   call of deflate. The compressor and decompressor must use exactly the same
516   dictionary (see inflateSetDictionary).
517
518     The dictionary should consist of strings (byte sequences) that are likely
519   to be encountered later in the data to be compressed, with the most commonly
520   used strings preferably put towards the end of the dictionary. Using a
521   dictionary is most useful when the data to be compressed is short and can be
522   predicted with good accuracy; the data can then be compressed better than
523   with the default empty dictionary.
524
525     Depending on the size of the compression data structures selected by
526   deflateInit or deflateInit2, a part of the dictionary may in effect be
527   discarded, for example if the dictionary is larger than the window size in
528   deflate or deflate2. Thus the strings most likely to be useful should be
529   put at the end of the dictionary, not at the front.
530
531     Upon return of this function, strm->adler is set to the adler32 value
532   of the dictionary; the decompressor may later use this value to determine
533   which dictionary has been used by the compressor. (The adler32 value
534   applies to the whole dictionary even if only a subset of the dictionary is
535   actually used by the compressor.) If a raw deflate was requested, then the
536   adler32 value is not computed and strm->adler is not set.
537
538     deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
539   parameter is invalid (such as NULL dictionary) or the stream state is
540   inconsistent (for example if deflate has already been called for this stream
541   or if the compression method is bsort). deflateSetDictionary does not
542   perform any compression: this will be done by deflate().
543*/
544
545ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
546                                    z_streamp source));
547/*
548     Sets the destination stream as a complete copy of the source stream.
549
550     This function can be useful when several compression strategies will be
551   tried, for example when there are several ways of pre-processing the input
552   data with a filter. The streams that will be discarded should then be freed
553   by calling deflateEnd.  Note that deflateCopy duplicates the internal
554   compression state which can be quite large, so this strategy is slow and
555   can consume lots of memory.
556
557     deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
558   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
559   (such as zalloc being NULL). msg is left unchanged in both source and
560   destination.
561*/
562
563ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
564/*
565     This function is equivalent to deflateEnd followed by deflateInit,
566   but does not free and reallocate all the internal compression state.
567   The stream will keep the same compression level and any other attributes
568   that may have been set by deflateInit2.
569
570      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
571   stream state was inconsistent (such as zalloc or state being NULL).
572*/
573
574ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
575                                      int level,
576                                      int strategy));
577/*
578     Dynamically update the compression level and compression strategy.  The
579   interpretation of level and strategy is as in deflateInit2.  This can be
580   used to switch between compression and straight copy of the input data, or
581   to switch to a different kind of input data requiring a different
582   strategy. If the compression level is changed, the input available so far
583   is compressed with the old level (and may be flushed); the new level will
584   take effect only at the next call of deflate().
585
586     Before the call of deflateParams, the stream state must be set as for
587   a call of deflate(), since the currently available input may have to
588   be compressed and flushed. In particular, strm->avail_out must be non-zero.
589
590     deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
591   stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
592   if strm->avail_out was zero.
593*/
594
595ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
596                                       uLong sourceLen));
597/*
598     deflateBound() returns an upper bound on the compressed size after
599   deflation of sourceLen bytes.  It must be called after deflateInit()
600   or deflateInit2().  This would be used to allocate an output buffer
601   for deflation in a single pass, and so would be called before deflate().
602*/
603
604ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
605                                     int bits,
606                                     int value));
607/*
608     deflatePrime() inserts bits in the deflate output stream.  The intent
609  is that this function is used to start off the deflate output with the
610  bits leftover from a previous deflate stream when appending to it.  As such,
611  this function can only be used for raw deflate, and must be used before the
612  first deflate() call after a deflateInit2() or deflateReset().  bits must be
613  less than or equal to 16, and that many of the least significant bits of
614  value will be inserted in the output.
615
616      deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
617   stream state was inconsistent.
618*/
619
620/*
621ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
622                                     int  windowBits));
623
624     This is another version of inflateInit with an extra parameter. The
625   fields next_in, avail_in, zalloc, zfree and opaque must be initialized
626   before by the caller.
627
628     The windowBits parameter is the base two logarithm of the maximum window
629   size (the size of the history buffer).  It should be in the range 8..15 for
630   this version of the library. The default value is 15 if inflateInit is used
631   instead. windowBits must be greater than or equal to the windowBits value
632   provided to deflateInit2() while compressing, or it must be equal to 15 if
633   deflateInit2() was not used. If a compressed stream with a larger window
634   size is given as input, inflate() will return with the error code
635   Z_DATA_ERROR instead of trying to allocate a larger window.
636
637     windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
638   determines the window size. inflate() will then process raw deflate data,
639   not looking for a zlib or gzip header, not generating a check value, and not
640   looking for any check values for comparison at the end of the stream. This
641   is for use with other formats that use the deflate compressed data format
642   such as zip.  Those formats provide their own check values. If a custom
643   format is developed using the raw deflate format for compressed data, it is
644   recommended that a check value such as an adler32 or a crc32 be applied to
645   the uncompressed data as is done in the zlib, gzip, and zip formats.  For
646   most applications, the zlib format should be used as is. Note that comments
647   above on the use in deflateInit2() applies to the magnitude of windowBits.
648
649     windowBits can also be greater than 15 for optional gzip decoding. Add
650   32 to windowBits to enable zlib and gzip decoding with automatic header
651   detection, or add 16 to decode only the gzip format (the zlib format will
652   return a Z_DATA_ERROR).
653
654     inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
655   memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
656   memLevel). msg is set to null if there is no error message.  inflateInit2
657   does not perform any decompression apart from reading the zlib header if
658   present: this will be done by inflate(). (So next_in and avail_in may be
659   modified, but next_out and avail_out are unchanged.)
660*/
661
662ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
663                                             const Bytef *dictionary,
664                                             uInt  dictLength));
665/*
666     Initializes the decompression dictionary from the given uncompressed byte
667   sequence. This function must be called immediately after a call of inflate
668   if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
669   can be determined from the adler32 value returned by this call of
670   inflate. The compressor and decompressor must use exactly the same
671   dictionary (see deflateSetDictionary).
672
673     inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
674   parameter is invalid (such as NULL dictionary) or the stream state is
675   inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
676   expected one (incorrect adler32 value). inflateSetDictionary does not
677   perform any decompression: this will be done by subsequent calls of
678   inflate().
679*/
680
681ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
682/*
683    Skips invalid compressed data until a full flush point (see above the
684  description of deflate with Z_FULL_FLUSH) can be found, or until all
685  available input is skipped. No output is provided.
686
687    inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
688  if no more input was provided, Z_DATA_ERROR if no flush point has been found,
689  or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
690  case, the application may save the current current value of total_in which
691  indicates where valid compressed data was found. In the error case, the
692  application may repeatedly call inflateSync, providing more input each time,
693  until success or end of the input data.
694*/
695
696ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
697                                    z_streamp source));
698/*
699     Sets the destination stream as a complete copy of the source stream.
700
701     This function can be useful when randomly accessing a large stream.  The
702   first pass through the stream can periodically record the inflate state,
703   allowing restarting inflate at those points when randomly accessing the
704   stream.
705
706     inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
707   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
708   (such as zalloc being NULL). msg is left unchanged in both source and
709   destination.
710*/
711
712ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
713/*
714     This function is equivalent to inflateEnd followed by inflateInit,
715   but does not free and reallocate all the internal decompression state.
716   The stream will keep attributes that may have been set by inflateInit2.
717
718      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
719   stream state was inconsistent (such as zalloc or state being NULL).
720*/
721
722/*
723ZEXTERN int ZEXPORT inflateBackInit OF((z_stream FAR *strm, int windowBits,
724                                        unsigned char FAR *window));
725
726     Initialize the internal stream state for decompression using inflateBack()
727   calls.  The fields zalloc, zfree and opaque in strm must be initialized
728   before the call.  If zalloc and zfree are Z_NULL, then the default library-
729   derived memory allocation routines are used.  windowBits is the base two
730   logarithm of the window size, in the range 8..15.  window is a caller
731   supplied buffer of that size.  Except for special applications where it is
732   assured that deflate was used with small window sizes, windowBits must be 15
733   and a 32K byte window must be supplied to be able to decompress general
734   deflate streams.
735
736     See inflateBack() for the usage of these routines.
737
738     inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
739   the paramaters are invalid, Z_MEM_ERROR if the internal state could not
740   be allocated, or Z_VERSION_ERROR if the version of the library does not
741   match the version of the header file.
742*/
743
744typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
745typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
746
747ZEXTERN int ZEXPORT inflateBack OF((z_stream FAR *strm,
748                                    in_func in, void FAR *in_desc,
749                                    out_func out, void FAR *out_desc));
750/*
751     inflateBack() does a raw inflate with a single call using a call-back
752   interface for input and output.  This is more efficient than inflate() for
753   file i/o applications in that it avoids copying between the output and the
754   sliding window by simply making the window itself the output buffer.  This
755   function trusts the application to not change the output buffer passed by
756   the output function, at least until inflateBack() returns.
757
758     inflateBackInit() must be called first to allocate the internal state
759   and to initialize the state with the user-provided window buffer.
760   inflateBack() may then be used multiple times to inflate a complete, raw
761   deflate stream with each call.  inflateBackEnd() is then called to free
762   the allocated state.
763
764     A raw deflate stream is one with no zlib or gzip header or trailer.
765   This routine would normally be used in a utility that reads zip or gzip
766   files and writes out uncompressed files.  The utility would decode the
767   header and process the trailer on its own, hence this routine expects
768   only the raw deflate stream to decompress.  This is different from the
769   normal behavior of inflate(), which expects either a zlib or gzip header and
770   trailer around the deflate stream.
771
772     inflateBack() uses two subroutines supplied by the caller that are then
773   called by inflateBack() for input and output.  inflateBack() calls those
774   routines until it reads a complete deflate stream and writes out all of the
775   uncompressed data, or until it encounters an error.  The function's
776   parameters and return types are defined above in the in_func and out_func
777   typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
778   number of bytes of provided input, and a pointer to that input in buf.  If
779   there is no input available, in() must return zero--buf is ignored in that
780   case--and inflateBack() will return a buffer error.  inflateBack() will call
781   out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
782   should return zero on success, or non-zero on failure.  If out() returns
783   non-zero, inflateBack() will return with an error.  Neither in() nor out()
784   are permitted to change the contents of the window provided to
785   inflateBackInit(), which is also the buffer that out() uses to write from.
786   The length written by out() will be at most the window size.  Any non-zero
787   amount of input may be provided by in().
788
789     For convenience, inflateBack() can be provided input on the first call by
790   setting strm->next_in and strm->avail_in.  If that input is exhausted, then
791   in() will be called.  Therefore strm->next_in must be initialized before
792   calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
793   immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
794   must also be initialized, and then if strm->avail_in is not zero, input will
795   initially be taken from strm->next_in[0 .. strm->avail_in - 1].
796
797     The in_desc and out_desc parameters of inflateBack() is passed as the
798   first parameter of in() and out() respectively when they are called.  These
799   descriptors can be optionally used to pass any information that the caller-
800   supplied in() and out() functions need to do their job.
801
802     On return, inflateBack() will set strm->next_in and strm->avail_in to
803   pass back any unused input that was provided by the last in() call.  The
804   return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
805   if in() or out() returned an error, Z_DATA_ERROR if there was a format
806   error in the deflate stream (in which case strm->msg is set to indicate the
807   nature of the error), or Z_STREAM_ERROR if the stream was not properly
808   initialized.  In the case of Z_BUF_ERROR, an input or output error can be
809   distinguished using strm->next_in which will be Z_NULL only if in() returned
810   an error.  If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
811   out() returning non-zero.  (in() will always be called before out(), so
812   strm->next_in is assured to be defined if out() returns non-zero.)  Note
813   that inflateBack() cannot return Z_OK.
814*/
815
816ZEXTERN int ZEXPORT inflateBackEnd OF((z_stream FAR *strm));
817/*
818     All memory allocated by inflateBackInit() is freed.
819
820     inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
821   state was inconsistent.
822*/
823
824ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
825/* Return flags indicating compile-time options.
826
827    Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
828     1.0: size of uInt
829     3.2: size of uLong
830     5.4: size of voidpf (pointer)
831     7.6: size of z_off_t
832
833    Compiler, assembler, and debug options:
834     8: DEBUG
835     9: ASMV or ASMINF -- use ASM code
836     10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
837     11: 0 (reserved)
838
839    One-time table building (smaller code, but not thread-safe if true):
840     12: BUILDFIXED -- build static block decoding tables when needed
841     13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
842     14,15: 0 (reserved)
843
844    Library content (indicates missing functionality):
845     16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
846                          deflate code when not needed)
847     17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
848                    and decode gzip streams (to avoid linking crc code)
849     18-19: 0 (reserved)
850
851    Operation variations (changes in library functionality):
852     20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
853     21: FASTEST -- deflate algorithm with only one, lowest compression level
854     22,23: 0 (reserved)
855
856    The sprintf variant used by gzprintf (zero is best):
857     24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
858     25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
859     26: 0 = returns value, 1 = void -- 1 means inferred string length returned
860
861    Remainder:
862     27-31: 0 (reserved)
863 */
864
865
866                        /* utility functions */
867
868/*
869     The following utility functions are implemented on top of the
870   basic stream-oriented functions. To simplify the interface, some
871   default options are assumed (compression level and memory usage,
872   standard memory allocation functions). The source code of these
873   utility functions can easily be modified if you need special options.
874*/
875
876ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
877                                 const Bytef *source, uLong sourceLen));
878/*
879     Compresses the source buffer into the destination buffer.  sourceLen is
880   the byte length of the source buffer. Upon entry, destLen is the total
881   size of the destination buffer, which must be at least the value returned
882   by compressBound(sourceLen). Upon exit, destLen is the actual size of the
883   compressed buffer.
884     This function can be used to compress a whole file at once if the
885   input file is mmap'ed.
886     compress returns Z_OK if success, Z_MEM_ERROR if there was not
887   enough memory, Z_BUF_ERROR if there was not enough room in the output
888   buffer.
889*/
890
891ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
892                                  const Bytef *source, uLong sourceLen,
893                                  int level));
894/*
895     Compresses the source buffer into the destination buffer. The level
896   parameter has the same meaning as in deflateInit.  sourceLen is the byte
897   length of the source buffer. Upon entry, destLen is the total size of the
898   destination buffer, which must be at least the value returned by
899   compressBound(sourceLen). Upon exit, destLen is the actual size of the
900   compressed buffer.
901
902     compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
903   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
904   Z_STREAM_ERROR if the level parameter is invalid.
905*/
906
907ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
908/*
909     compressBound() returns an upper bound on the compressed size after
910   compress() or compress2() on sourceLen bytes.  It would be used before
911   a compress() or compress2() call to allocate the destination buffer.
912*/
913
914ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
915                                   const Bytef *source, uLong sourceLen));
916/*
917     Decompresses the source buffer into the destination buffer.  sourceLen is
918   the byte length of the source buffer. Upon entry, destLen is the total
919   size of the destination buffer, which must be large enough to hold the
920   entire uncompressed data. (The size of the uncompressed data must have
921   been saved previously by the compressor and transmitted to the decompressor
922   by some mechanism outside the scope of this compression library.)
923   Upon exit, destLen is the actual size of the compressed buffer.
924     This function can be used to decompress a whole file at once if the
925   input file is mmap'ed.
926
927     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
928   enough memory, Z_BUF_ERROR if there was not enough room in the output
929   buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
930*/
931
932
933typedef voidp gzFile;
934
935ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
936/*
937     Opens a gzip (.gz) file for reading or writing. The mode parameter
938   is as in fopen ("rb" or "wb") but can also include a compression level
939   ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
940   Huffman only compression as in "wb1h", or 'R' for run-length encoding
941   as in "wb1R". (See the description of deflateInit2 for more information
942   about the strategy parameter.)
943
944     gzopen can be used to read a file which is not in gzip format; in this
945   case gzread will directly read from the file without decompression.
946
947     gzopen returns NULL if the file could not be opened or if there was
948   insufficient memory to allocate the (de)compression state; errno
949   can be checked to distinguish the two cases (if errno is zero, the
950   zlib error is Z_MEM_ERROR).  */
951
952ZEXTERN gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
953/*
954     gzdopen() associates a gzFile with the file descriptor fd.  File
955   descriptors are obtained from calls like open, dup, creat, pipe or
956   fileno (in the file has been previously opened with fopen).
957   The mode parameter is as in gzopen.
958     The next call of gzclose on the returned gzFile will also close the
959   file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
960   descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
961     gzdopen returns NULL if there was insufficient memory to allocate
962   the (de)compression state.
963*/
964
965ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
966/*
967     Dynamically update the compression level or strategy. See the description
968   of deflateInit2 for the meaning of these parameters.
969     gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
970   opened for writing.
971*/
972
973ZEXTERN int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
974/*
975     Reads the given number of uncompressed bytes from the compressed file.
976   If the input file was not in gzip format, gzread copies the given number
977   of bytes into the buffer.
978     gzread returns the number of uncompressed bytes actually read (0 for
979   end of file, -1 for error). */
980
981ZEXTERN int ZEXPORT    gzwrite OF((gzFile file,
982                                   voidpc buf, unsigned len));
983/*
984     Writes the given number of uncompressed bytes into the compressed file.
985   gzwrite returns the number of uncompressed bytes actually written
986   (0 in case of error).
987*/
988
989ZEXTERN int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
990/*
991     Converts, formats, and writes the args to the compressed file under
992   control of the format string, as in fprintf. gzprintf returns the number of
993   uncompressed bytes actually written (0 in case of error).  The number of
994   uncompressed bytes written is limited to 4095. The caller should assure that
995   this limit is not exceeded. If it is exceeded, then gzprintf() will return
996   return an error (0) with nothing written. In this case, there may also be a
997   buffer overflow with unpredictable consequences, which is possible only if
998   zlib was compiled with the insecure functions sprintf() or vsprintf()
999   because the secure snprintf() or vsnprintf() functions were not available.
1000*/
1001
1002ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1003/*
1004      Writes the given null-terminated string to the compressed file, excluding
1005   the terminating null character.
1006      gzputs returns the number of characters written, or -1 in case of error.
1007*/
1008
1009ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1010/*
1011      Reads bytes from the compressed file until len-1 characters are read, or
1012   a newline character is read and transferred to buf, or an end-of-file
1013   condition is encountered.  The string is then terminated with a null
1014   character.
1015      gzgets returns buf, or Z_NULL in case of error.
1016*/
1017
1018ZEXTERN int ZEXPORT    gzputc OF((gzFile file, int c));
1019/*
1020      Writes c, converted to an unsigned char, into the compressed file.
1021   gzputc returns the value that was written, or -1 in case of error.
1022*/
1023
1024ZEXTERN int ZEXPORT    gzgetc OF((gzFile file));
1025/*
1026      Reads one byte from the compressed file. gzgetc returns this byte
1027   or -1 in case of end of file or error.
1028*/
1029
1030ZEXTERN int ZEXPORT    gzungetc OF((int c, gzFile file));
1031/*
1032      Push one character back onto the stream to be read again later.
1033   Only one character of push-back is allowed.  gzungetc() returns the
1034   character pushed, or -1 on failure.  gzungetc() will fail if a
1035   character has been pushed but not read yet, or if c is -1. The pushed
1036   character will be discarded if the stream is repositioned with gzseek()
1037   or gzrewind().
1038*/
1039
1040ZEXTERN int ZEXPORT    gzflush OF((gzFile file, int flush));
1041/*
1042     Flushes all pending output into the compressed file. The parameter
1043   flush is as in the deflate() function. The return value is the zlib
1044   error number (see function gzerror below). gzflush returns Z_OK if
1045   the flush parameter is Z_FINISH and all output could be flushed.
1046     gzflush should be called only when strictly necessary because it can
1047   degrade compression.
1048*/
1049
1050ZEXTERN z_off_t ZEXPORT    gzseek OF((gzFile file,
1051                                      z_off_t offset, int whence));
1052/*
1053      Sets the starting position for the next gzread or gzwrite on the
1054   given compressed file. The offset represents a number of bytes in the
1055   uncompressed data stream. The whence parameter is defined as in lseek(2);
1056   the value SEEK_END is not supported.
1057     If the file is opened for reading, this function is emulated but can be
1058   extremely slow. If the file is opened for writing, only forward seeks are
1059   supported; gzseek then compresses a sequence of zeroes up to the new
1060   starting position.
1061
1062      gzseek returns the resulting offset location as measured in bytes from
1063   the beginning of the uncompressed stream, or -1 in case of error, in
1064   particular if the file is opened for writing and the new starting position
1065   would be before the current position.
1066*/
1067
1068ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
1069/*
1070     Rewinds the given file. This function is supported only for reading.
1071
1072   gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1073*/
1074
1075ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
1076/*
1077     Returns the starting position for the next gzread or gzwrite on the
1078   given compressed file. This position represents a number of bytes in the
1079   uncompressed data stream.
1080
1081   gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1082*/
1083
1084ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1085/*
1086     Returns 1 when EOF has previously been detected reading the given
1087   input stream, otherwise zero.
1088*/
1089
1090ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
1091/*
1092     Flushes all pending output if necessary, closes the compressed file
1093   and deallocates all the (de)compression state. The return value is the zlib
1094   error number (see function gzerror below).
1095*/
1096
1097ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1098/*
1099     Returns the error message for the last error which occurred on the
1100   given compressed file. errnum is set to zlib error number. If an
1101   error occurred in the file system and not in the compression library,
1102   errnum is set to Z_ERRNO and the application may consult errno
1103   to get the exact error code.
1104*/
1105
1106ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1107/*
1108     Clears the error and end-of-file flags for file. This is analogous to the
1109   clearerr() function in stdio. This is useful for continuing to read a gzip
1110   file that is being written concurrently.
1111*/
1112
1113                        /* checksum functions */
1114
1115/*
1116     These functions are not related to compression but are exported
1117   anyway because they might be useful in applications using the
1118   compression library.
1119*/
1120
1121ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1122
1123/*
1124     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1125   return the updated checksum. If buf is NULL, this function returns
1126   the required initial value for the checksum.
1127   An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1128   much faster. Usage example:
1129
1130     uLong adler = adler32(0L, Z_NULL, 0);
1131
1132     while (read_buffer(buffer, length) != EOF) {
1133       adler = adler32(adler, buffer, length);
1134     }
1135     if (adler != original_adler) error();
1136*/
1137
1138ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
1139/*
1140     Update a running crc with the bytes buf[0..len-1] and return the updated
1141   crc. If buf is NULL, this function returns the required initial value
1142   for the crc. Pre- and post-conditioning (one's complement) is performed
1143   within this function so it shouldn't be done by the application.
1144   Usage example:
1145
1146     uLong crc = crc32(0L, Z_NULL, 0);
1147
1148     while (read_buffer(buffer, length) != EOF) {
1149       crc = crc32(crc, buffer, length);
1150     }
1151     if (crc != original_crc) error();
1152*/
1153
1154
1155                        /* various hacks, don't look :) */
1156
1157/* deflateInit and inflateInit are macros to allow checking the zlib version
1158 * and the compiler's view of z_stream:
1159 */
1160ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1161                                     const char *version, int stream_size));
1162ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1163                                     const char *version, int stream_size));
1164ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
1165                                      int windowBits, int memLevel,
1166                                      int strategy, const char *version,
1167                                      int stream_size));
1168ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
1169                                      const char *version, int stream_size));
1170ZEXTERN int ZEXPORT inflateBackInit_ OF((z_stream FAR *strm, int windowBits,
1171                                         unsigned char FAR *window,
1172                                         const char *version,
1173                                         int stream_size));
1174#define deflateInit(strm, level) \
1175        deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
1176#define inflateInit(strm) \
1177        inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
1178#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1179        deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1180                      (strategy),           ZLIB_VERSION, sizeof(z_stream))
1181#define inflateInit2(strm, windowBits) \
1182        inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1183#define inflateBackInit(strm, windowBits, window) \
1184        inflateBackInit_((strm), (windowBits), (window), \
1185        ZLIB_VERSION, sizeof(z_stream))
1186
1187
1188#if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1189    struct internal_state {int dummy;}; /* hack for buggy compilers */
1190#endif
1191
1192ZEXTERN const char   * ZEXPORT zError           OF((int err));
1193ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp z));
1194ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
1195
1196#ifdef __cplusplus
1197}
1198#endif
1199
1200#endif /* ZLIB_H */
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