Watt-32 tcp/ip  2.2 dev-rel.10
zlib.h
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
37 extern "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 
79 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
80 typedef void (*free_func) OF((voidpf opaque, voidpf address));
81 
82 struct internal_state;
83 
84 typedef 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 
105 typedef 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 
189 ZEXTERN 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 /*
197 ZEXTERN 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 
219 ZEXTERN 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 
301 ZEXTERN 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 /*
316 ZEXTERN 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 
336 ZEXTERN 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 
435 ZEXTERN 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 /*
453 ZEXTERN 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 
508 ZEXTERN 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 
545 ZEXTERN 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 
563 ZEXTERN 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 
574 ZEXTERN 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 
595 ZEXTERN 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 
604 ZEXTERN 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 /*
621 ZEXTERN 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 
662 ZEXTERN 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 
681 ZEXTERN 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 
696 ZEXTERN 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 
712 ZEXTERN 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 /*
723 ZEXTERN 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 
744 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
745 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
746 
747 ZEXTERN 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 
816 ZEXTERN 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 
824 ZEXTERN 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 
876 ZEXTERN 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 
891 ZEXTERN 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 
907 ZEXTERN 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 
914 ZEXTERN 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 
933 typedef voidp gzFile;
934 
935 ZEXTERN 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 
952 ZEXTERN 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 
965 ZEXTERN 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 
973 ZEXTERN 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 
981 ZEXTERN 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 
989 ZEXTERN 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 
1002 ZEXTERN 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 
1009 ZEXTERN 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 
1018 ZEXTERN 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 
1024 ZEXTERN 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 
1030 ZEXTERN 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 
1040 ZEXTERN 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 
1050 ZEXTERN 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 
1068 ZEXTERN 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 
1075 ZEXTERN 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 
1084 ZEXTERN 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 
1090 ZEXTERN 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 
1097 ZEXTERN 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 
1106 ZEXTERN 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 
1121 ZEXTERN 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 
1138 ZEXTERN 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  */
1160 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1161  const char *version, int stream_size));
1162 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1163  const char *version, int stream_size));
1164 ZEXTERN 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));
1168 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1169  const char *version, int stream_size));
1170 ZEXTERN 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 
1192 ZEXTERN const char * ZEXPORT zError OF((int err));
1193 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1194 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1195 
1196 #ifdef __cplusplus
1197 }
1198 #endif
1199 
1200 #endif /* ZLIB_H */