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zlib.h
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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2  version 1.2.3, July 18th, 2005
3 
4  Copyright (C) 1995-2005 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 "1.2.3"
41 #define ZLIB_VERNUM 0x1230
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 default by the in-memory functions is
57  the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
58  around a deflate stream, which is itself documented in RFC 1951.
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  This library can optionally read and write gzip streams in memory as well.
66 
67  The zlib format was designed to be compact and fast for use in memory
68  and on communications channels. The gzip format was designed for single-
69  file compression on file systems, has a larger header than zlib to maintain
70  directory information, and uses a different, slower check method than zlib.
71 
72  The library does not install any signal handler. The decoder checks
73  the consistency of the compressed data, so the library should never
74  crash even in case of corrupted input.
75 */
76 
77 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
78 typedef void (*free_func) OF((voidpf opaque, voidpf address));
79 
80 struct internal_state;
81 
82 typedef struct z_stream_s {
83  Bytef *next_in; /* next input byte */
84  uInt avail_in; /* number of bytes available at next_in */
85  uLong total_in; /* total nb of input bytes read so far */
86 
87  Bytef *next_out; /* next output byte should be put there */
88  uInt avail_out; /* remaining free space at next_out */
89  uLong total_out; /* total nb of bytes output so far */
90 
91  char *msg; /* last error message, NULL if no error */
92  struct internal_state FAR *state; /* not visible by applications */
93 
94  alloc_func zalloc; /* used to allocate the internal state */
95  free_func zfree; /* used to free the internal state */
96  voidpf opaque; /* private data object passed to zalloc and zfree */
97 
98  int data_type; /* best guess about the data type: binary or text */
99  uLong adler; /* adler32 value of the uncompressed data */
100  uLong reserved; /* reserved for future use */
101 } z_stream;
102 
104 
105 /*
106  gzip header information passed to and from zlib routines. See RFC 1952
107  for more details on the meanings of these fields.
108 */
109 typedef struct gz_header_s {
110  int text; /* true if compressed data believed to be text */
111  uLong time; /* modification time */
112  int xflags; /* extra flags (not used when writing a gzip file) */
113  int os; /* operating system */
114  Bytef *extra; /* pointer to extra field or Z_NULL if none */
115  uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
116  uInt extra_max; /* space at extra (only when reading header) */
117  Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
118  uInt name_max; /* space at name (only when reading header) */
119  Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
120  uInt comm_max; /* space at comment (only when reading header) */
121  int hcrc; /* true if there was or will be a header crc */
122  int done; /* true when done reading gzip header (not used
123  when writing a gzip file) */
124 } gz_header;
125 
127 
128 /*
129  The application must update next_in and avail_in when avail_in has
130  dropped to zero. It must update next_out and avail_out when avail_out
131  has dropped to zero. The application must initialize zalloc, zfree and
132  opaque before calling the init function. All other fields are set by the
133  compression library and must not be updated by the application.
134 
135  The opaque value provided by the application will be passed as the first
136  parameter for calls of zalloc and zfree. This can be useful for custom
137  memory management. The compression library attaches no meaning to the
138  opaque value.
139 
140  zalloc must return Z_NULL if there is not enough memory for the object.
141  If zlib is used in a multi-threaded application, zalloc and zfree must be
142  thread safe.
143 
144  On 16-bit systems, the functions zalloc and zfree must be able to allocate
145  exactly 65536 bytes, but will not be required to allocate more than this
146  if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
147  pointers returned by zalloc for objects of exactly 65536 bytes *must*
148  have their offset normalized to zero. The default allocation function
149  provided by this library ensures this (see zutil.c). To reduce memory
150  requirements and avoid any allocation of 64K objects, at the expense of
151  compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
152 
153  The fields total_in and total_out can be used for statistics or
154  progress reports. After compression, total_in holds the total size of
155  the uncompressed data and may be saved for use in the decompressor
156  (particularly if the decompressor wants to decompress everything in
157  a single step).
158 */
159 
160  /* constants */
161 
162 #define Z_NO_FLUSH 0
163 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
164 #define Z_SYNC_FLUSH 2
165 #define Z_FULL_FLUSH 3
166 #define Z_FINISH 4
167 #define Z_BLOCK 5
168 /* Allowed flush values; see deflate() and inflate() below for details */
169 
170 #define Z_OK 0
171 #define Z_STREAM_END 1
172 #define Z_NEED_DICT 2
173 #define Z_ERRNO (-1)
174 #define Z_STREAM_ERROR (-2)
175 #define Z_DATA_ERROR (-3)
176 #define Z_MEM_ERROR (-4)
177 #define Z_BUF_ERROR (-5)
178 #define Z_VERSION_ERROR (-6)
179 /* Return codes for the compression/decompression functions. Negative
180  * values are errors, positive values are used for special but normal events.
181  */
182 
183 #define Z_NO_COMPRESSION 0
184 #define Z_BEST_SPEED 1
185 #define Z_BEST_COMPRESSION 9
186 #define Z_DEFAULT_COMPRESSION (-1)
187 /* compression levels */
188 
189 #define Z_FILTERED 1
190 #define Z_HUFFMAN_ONLY 2
191 #define Z_RLE 3
192 #define Z_FIXED 4
193 #define Z_DEFAULT_STRATEGY 0
194 /* compression strategy; see deflateInit2() below for details */
195 
196 #define Z_BINARY 0
197 #define Z_TEXT 1
198 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
199 #define Z_UNKNOWN 2
200 /* Possible values of the data_type field (though see inflate()) */
201 
202 #define Z_DEFLATED 8
203 /* The deflate compression method (the only one supported in this version) */
204 
205 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
206 
207 #define zlib_version zlibVersion()
208 /* for compatibility with versions < 1.0.2 */
209 
210  /* basic functions */
211 
212 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
213 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
214  If the first character differs, the library code actually used is
215  not compatible with the zlib.h header file used by the application.
216  This check is automatically made by deflateInit and inflateInit.
217  */
218 
219 /*
220 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
221 
222  Initializes the internal stream state for compression. The fields
223  zalloc, zfree and opaque must be initialized before by the caller.
224  If zalloc and zfree are set to Z_NULL, deflateInit updates them to
225  use default allocation functions.
226 
227  The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
228  1 gives best speed, 9 gives best compression, 0 gives no compression at
229  all (the input data is simply copied a block at a time).
230  Z_DEFAULT_COMPRESSION requests a default compromise between speed and
231  compression (currently equivalent to level 6).
232 
233  deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
234  enough memory, Z_STREAM_ERROR if level is not a valid compression level,
235  Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
236  with the version assumed by the caller (ZLIB_VERSION).
237  msg is set to null if there is no error message. deflateInit does not
238  perform any compression: this will be done by deflate().
239 */
240 
241 
242 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
243 /*
244  deflate compresses as much data as possible, and stops when the input
245  buffer becomes empty or the output buffer becomes full. It may introduce some
246  output latency (reading input without producing any output) except when
247  forced to flush.
248 
249  The detailed semantics are as follows. deflate performs one or both of the
250  following actions:
251 
252  - Compress more input starting at next_in and update next_in and avail_in
253  accordingly. If not all input can be processed (because there is not
254  enough room in the output buffer), next_in and avail_in are updated and
255  processing will resume at this point for the next call of deflate().
256 
257  - Provide more output starting at next_out and update next_out and avail_out
258  accordingly. This action is forced if the parameter flush is non zero.
259  Forcing flush frequently degrades the compression ratio, so this parameter
260  should be set only when necessary (in interactive applications).
261  Some output may be provided even if flush is not set.
262 
263  Before the call of deflate(), the application should ensure that at least
264  one of the actions is possible, by providing more input and/or consuming
265  more output, and updating avail_in or avail_out accordingly; avail_out
266  should never be zero before the call. The application can consume the
267  compressed output when it wants, for example when the output buffer is full
268  (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
269  and with zero avail_out, it must be called again after making room in the
270  output buffer because there might be more output pending.
271 
272  Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
273  decide how much data to accumualte before producing output, in order to
274  maximize compression.
275 
276  If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
277  flushed to the output buffer and the output is aligned on a byte boundary, so
278  that the decompressor can get all input data available so far. (In particular
279  avail_in is zero after the call if enough output space has been provided
280  before the call.) Flushing may degrade compression for some compression
281  algorithms and so it should be used only when necessary.
282 
283  If flush is set to Z_FULL_FLUSH, all output is flushed as with
284  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
285  restart from this point if previous compressed data has been damaged or if
286  random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
287  compression.
288 
289  If deflate returns with avail_out == 0, this function must be called again
290  with the same value of the flush parameter and more output space (updated
291  avail_out), until the flush is complete (deflate returns with non-zero
292  avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
293  avail_out is greater than six to avoid repeated flush markers due to
294  avail_out == 0 on return.
295 
296  If the parameter flush is set to Z_FINISH, pending input is processed,
297  pending output is flushed and deflate returns with Z_STREAM_END if there
298  was enough output space; if deflate returns with Z_OK, this function must be
299  called again with Z_FINISH and more output space (updated avail_out) but no
300  more input data, until it returns with Z_STREAM_END or an error. After
301  deflate has returned Z_STREAM_END, the only possible operations on the
302  stream are deflateReset or deflateEnd.
303 
304  Z_FINISH can be used immediately after deflateInit if all the compression
305  is to be done in a single step. In this case, avail_out must be at least
306  the value returned by deflateBound (see below). If deflate does not return
307  Z_STREAM_END, then it must be called again as described above.
308 
309  deflate() sets strm->adler to the adler32 checksum of all input read
310  so far (that is, total_in bytes).
311 
312  deflate() may update strm->data_type if it can make a good guess about
313  the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
314  binary. This field is only for information purposes and does not affect
315  the compression algorithm in any manner.
316 
317  deflate() returns Z_OK if some progress has been made (more input
318  processed or more output produced), Z_STREAM_END if all input has been
319  consumed and all output has been produced (only when flush is set to
320  Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
321  if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
322  (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
323  fatal, and deflate() can be called again with more input and more output
324  space to continue compressing.
325 */
326 
327 
328 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
329 /*
330  All dynamically allocated data structures for this stream are freed.
331  This function discards any unprocessed input and does not flush any
332  pending output.
333 
334  deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
335  stream state was inconsistent, Z_DATA_ERROR if the stream was freed
336  prematurely (some input or output was discarded). In the error case,
337  msg may be set but then points to a static string (which must not be
338  deallocated).
339 */
340 
341 
342 /*
343 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
344 
345  Initializes the internal stream state for decompression. The fields
346  next_in, avail_in, zalloc, zfree and opaque must be initialized before by
347  the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
348  value depends on the compression method), inflateInit determines the
349  compression method from the zlib header and allocates all data structures
350  accordingly; otherwise the allocation will be deferred to the first call of
351  inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
352  use default allocation functions.
353 
354  inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
355  memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
356  version assumed by the caller. msg is set to null if there is no error
357  message. inflateInit does not perform any decompression apart from reading
358  the zlib header if present: this will be done by inflate(). (So next_in and
359  avail_in may be modified, but next_out and avail_out are unchanged.)
360 */
361 
362 
363 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
364 /*
365  inflate decompresses as much data as possible, and stops when the input
366  buffer becomes empty or the output buffer becomes full. It may introduce
367  some output latency (reading input without producing any output) except when
368  forced to flush.
369 
370  The detailed semantics are as follows. inflate performs one or both of the
371  following actions:
372 
373  - Decompress more input starting at next_in and update next_in and avail_in
374  accordingly. If not all input can be processed (because there is not
375  enough room in the output buffer), next_in is updated and processing
376  will resume at this point for the next call of inflate().
377 
378  - Provide more output starting at next_out and update next_out and avail_out
379  accordingly. inflate() provides as much output as possible, until there
380  is no more input data or no more space in the output buffer (see below
381  about the flush parameter).
382 
383  Before the call of inflate(), the application should ensure that at least
384  one of the actions is possible, by providing more input and/or consuming
385  more output, and updating the next_* and avail_* values accordingly.
386  The application can consume the uncompressed output when it wants, for
387  example when the output buffer is full (avail_out == 0), or after each
388  call of inflate(). If inflate returns Z_OK and with zero avail_out, it
389  must be called again after making room in the output buffer because there
390  might be more output pending.
391 
392  The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
393  Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
394  output as possible to the output buffer. Z_BLOCK requests that inflate() stop
395  if and when it gets to the next deflate block boundary. When decoding the
396  zlib or gzip format, this will cause inflate() to return immediately after
397  the header and before the first block. When doing a raw inflate, inflate()
398  will go ahead and process the first block, and will return when it gets to
399  the end of that block, or when it runs out of data.
400 
401  The Z_BLOCK option assists in appending to or combining deflate streams.
402  Also to assist in this, on return inflate() will set strm->data_type to the
403  number of unused bits in the last byte taken from strm->next_in, plus 64
404  if inflate() is currently decoding the last block in the deflate stream,
405  plus 128 if inflate() returned immediately after decoding an end-of-block
406  code or decoding the complete header up to just before the first byte of the
407  deflate stream. The end-of-block will not be indicated until all of the
408  uncompressed data from that block has been written to strm->next_out. The
409  number of unused bits may in general be greater than seven, except when
410  bit 7 of data_type is set, in which case the number of unused bits will be
411  less than eight.
412 
413  inflate() should normally be called until it returns Z_STREAM_END or an
414  error. However if all decompression is to be performed in a single step
415  (a single call of inflate), the parameter flush should be set to
416  Z_FINISH. In this case all pending input is processed and all pending
417  output is flushed; avail_out must be large enough to hold all the
418  uncompressed data. (The size of the uncompressed data may have been saved
419  by the compressor for this purpose.) The next operation on this stream must
420  be inflateEnd to deallocate the decompression state. The use of Z_FINISH
421  is never required, but can be used to inform inflate that a faster approach
422  may be used for the single inflate() call.
423 
424  In this implementation, inflate() always flushes as much output as
425  possible to the output buffer, and always uses the faster approach on the
426  first call. So the only effect of the flush parameter in this implementation
427  is on the return value of inflate(), as noted below, or when it returns early
428  because Z_BLOCK is used.
429 
430  If a preset dictionary is needed after this call (see inflateSetDictionary
431  below), inflate sets strm->adler to the adler32 checksum of the dictionary
432  chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
433  strm->adler to the adler32 checksum of all output produced so far (that is,
434  total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
435  below. At the end of the stream, inflate() checks that its computed adler32
436  checksum is equal to that saved by the compressor and returns Z_STREAM_END
437  only if the checksum is correct.
438 
439  inflate() will decompress and check either zlib-wrapped or gzip-wrapped
440  deflate data. The header type is detected automatically. Any information
441  contained in the gzip header is not retained, so applications that need that
442  information should instead use raw inflate, see inflateInit2() below, or
443  inflateBack() and perform their own processing of the gzip header and
444  trailer.
445 
446  inflate() returns Z_OK if some progress has been made (more input processed
447  or more output produced), Z_STREAM_END if the end of the compressed data has
448  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
449  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
450  corrupted (input stream not conforming to the zlib format or incorrect check
451  value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
452  if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
453  Z_BUF_ERROR if no progress is possible or if there was not enough room in the
454  output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
455  inflate() can be called again with more input and more output space to
456  continue decompressing. If Z_DATA_ERROR is returned, the application may then
457  call inflateSync() to look for a good compression block if a partial recovery
458  of the data is desired.
459 */
460 
461 
462 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
463 /*
464  All dynamically allocated data structures for this stream are freed.
465  This function discards any unprocessed input and does not flush any
466  pending output.
467 
468  inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
469  was inconsistent. In the error case, msg may be set but then points to a
470  static string (which must not be deallocated).
471 */
472 
473  /* Advanced functions */
474 
475 /*
476  The following functions are needed only in some special applications.
477 */
478 
479 /*
480 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
481  int level,
482  int method,
483  int windowBits,
484  int memLevel,
485  int strategy));
486 
487  This is another version of deflateInit with more compression options. The
488  fields next_in, zalloc, zfree and opaque must be initialized before by
489  the caller.
490 
491  The method parameter is the compression method. It must be Z_DEFLATED in
492  this version of the library.
493 
494  The windowBits parameter is the base two logarithm of the window size
495  (the size of the history buffer). It should be in the range 8..15 for this
496  version of the library. Larger values of this parameter result in better
497  compression at the expense of memory usage. The default value is 15 if
498  deflateInit is used instead.
499 
500  windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
501  determines the window size. deflate() will then generate raw deflate data
502  with no zlib header or trailer, and will not compute an adler32 check value.
503 
504  windowBits can also be greater than 15 for optional gzip encoding. Add
505  16 to windowBits to write a simple gzip header and trailer around the
506  compressed data instead of a zlib wrapper. The gzip header will have no
507  file name, no extra data, no comment, no modification time (set to zero),
508  no header crc, and the operating system will be set to 255 (unknown). If a
509  gzip stream is being written, strm->adler is a crc32 instead of an adler32.
510 
511  The memLevel parameter specifies how much memory should be allocated
512  for the internal compression state. memLevel=1 uses minimum memory but
513  is slow and reduces compression ratio; memLevel=9 uses maximum memory
514  for optimal speed. The default value is 8. See zconf.h for total memory
515  usage as a function of windowBits and memLevel.
516 
517  The strategy parameter is used to tune the compression algorithm. Use the
518  value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
519  filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
520  string match), or Z_RLE to limit match distances to one (run-length
521  encoding). Filtered data consists mostly of small values with a somewhat
522  random distribution. In this case, the compression algorithm is tuned to
523  compress them better. The effect of Z_FILTERED is to force more Huffman
524  coding and less string matching; it is somewhat intermediate between
525  Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
526  Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
527  parameter only affects the compression ratio but not the correctness of the
528  compressed output even if it is not set appropriately. Z_FIXED prevents the
529  use of dynamic Huffman codes, allowing for a simpler decoder for special
530  applications.
531 
532  deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
533  memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
534  method). msg is set to null if there is no error message. deflateInit2 does
535  not perform any compression: this will be done by deflate().
536 */
537 
538 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
539  const Bytef *dictionary,
540  uInt dictLength));
541 /*
542  Initializes the compression dictionary from the given byte sequence
543  without producing any compressed output. This function must be called
544  immediately after deflateInit, deflateInit2 or deflateReset, before any
545  call of deflate. The compressor and decompressor must use exactly the same
546  dictionary (see inflateSetDictionary).
547 
548  The dictionary should consist of strings (byte sequences) that are likely
549  to be encountered later in the data to be compressed, with the most commonly
550  used strings preferably put towards the end of the dictionary. Using a
551  dictionary is most useful when the data to be compressed is short and can be
552  predicted with good accuracy; the data can then be compressed better than
553  with the default empty dictionary.
554 
555  Depending on the size of the compression data structures selected by
556  deflateInit or deflateInit2, a part of the dictionary may in effect be
557  discarded, for example if the dictionary is larger than the window size in
558  deflate or deflate2. Thus the strings most likely to be useful should be
559  put at the end of the dictionary, not at the front. In addition, the
560  current implementation of deflate will use at most the window size minus
561  262 bytes of the provided dictionary.
562 
563  Upon return of this function, strm->adler is set to the adler32 value
564  of the dictionary; the decompressor may later use this value to determine
565  which dictionary has been used by the compressor. (The adler32 value
566  applies to the whole dictionary even if only a subset of the dictionary is
567  actually used by the compressor.) If a raw deflate was requested, then the
568  adler32 value is not computed and strm->adler is not set.
569 
570  deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
571  parameter is invalid (such as NULL dictionary) or the stream state is
572  inconsistent (for example if deflate has already been called for this stream
573  or if the compression method is bsort). deflateSetDictionary does not
574  perform any compression: this will be done by deflate().
575 */
576 
577 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
578  z_streamp source));
579 /*
580  Sets the destination stream as a complete copy of the source stream.
581 
582  This function can be useful when several compression strategies will be
583  tried, for example when there are several ways of pre-processing the input
584  data with a filter. The streams that will be discarded should then be freed
585  by calling deflateEnd. Note that deflateCopy duplicates the internal
586  compression state which can be quite large, so this strategy is slow and
587  can consume lots of memory.
588 
589  deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
590  enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
591  (such as zalloc being NULL). msg is left unchanged in both source and
592  destination.
593 */
594 
595 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
596 /*
597  This function is equivalent to deflateEnd followed by deflateInit,
598  but does not free and reallocate all the internal compression state.
599  The stream will keep the same compression level and any other attributes
600  that may have been set by deflateInit2.
601 
602  deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
603  stream state was inconsistent (such as zalloc or state being NULL).
604 */
605 
606 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
607  int level,
608  int strategy));
609 /*
610  Dynamically update the compression level and compression strategy. The
611  interpretation of level and strategy is as in deflateInit2. This can be
612  used to switch between compression and straight copy of the input data, or
613  to switch to a different kind of input data requiring a different
614  strategy. If the compression level is changed, the input available so far
615  is compressed with the old level (and may be flushed); the new level will
616  take effect only at the next call of deflate().
617 
618  Before the call of deflateParams, the stream state must be set as for
619  a call of deflate(), since the currently available input may have to
620  be compressed and flushed. In particular, strm->avail_out must be non-zero.
621 
622  deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
623  stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
624  if strm->avail_out was zero.
625 */
626 
627 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
628  int good_length,
629  int max_lazy,
630  int nice_length,
631  int max_chain));
632 /*
633  Fine tune deflate's internal compression parameters. This should only be
634  used by someone who understands the algorithm used by zlib's deflate for
635  searching for the best matching string, and even then only by the most
636  fanatic optimizer trying to squeeze out the last compressed bit for their
637  specific input data. Read the deflate.c source code for the meaning of the
638  max_lazy, good_length, nice_length, and max_chain parameters.
639 
640  deflateTune() can be called after deflateInit() or deflateInit2(), and
641  returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
642  */
643 
644 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
645  uLong sourceLen));
646 /*
647  deflateBound() returns an upper bound on the compressed size after
648  deflation of sourceLen bytes. It must be called after deflateInit()
649  or deflateInit2(). This would be used to allocate an output buffer
650  for deflation in a single pass, and so would be called before deflate().
651 */
652 
653 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
654  int bits,
655  int value));
656 /*
657  deflatePrime() inserts bits in the deflate output stream. The intent
658  is that this function is used to start off the deflate output with the
659  bits leftover from a previous deflate stream when appending to it. As such,
660  this function can only be used for raw deflate, and must be used before the
661  first deflate() call after a deflateInit2() or deflateReset(). bits must be
662  less than or equal to 16, and that many of the least significant bits of
663  value will be inserted in the output.
664 
665  deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
666  stream state was inconsistent.
667 */
668 
669 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
670  gz_headerp head));
671 /*
672  deflateSetHeader() provides gzip header information for when a gzip
673  stream is requested by deflateInit2(). deflateSetHeader() may be called
674  after deflateInit2() or deflateReset() and before the first call of
675  deflate(). The text, time, os, extra field, name, and comment information
676  in the provided gz_header structure are written to the gzip header (xflag is
677  ignored -- the extra flags are set according to the compression level). The
678  caller must assure that, if not Z_NULL, name and comment are terminated with
679  a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
680  available there. If hcrc is true, a gzip header crc is included. Note that
681  the current versions of the command-line version of gzip (up through version
682  1.3.x) do not support header crc's, and will report that it is a "multi-part
683  gzip file" and give up.
684 
685  If deflateSetHeader is not used, the default gzip header has text false,
686  the time set to zero, and os set to 255, with no extra, name, or comment
687  fields. The gzip header is returned to the default state by deflateReset().
688 
689  deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
690  stream state was inconsistent.
691 */
692 
693 /*
694 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
695  int windowBits));
696 
697  This is another version of inflateInit with an extra parameter. The
698  fields next_in, avail_in, zalloc, zfree and opaque must be initialized
699  before by the caller.
700 
701  The windowBits parameter is the base two logarithm of the maximum window
702  size (the size of the history buffer). It should be in the range 8..15 for
703  this version of the library. The default value is 15 if inflateInit is used
704  instead. windowBits must be greater than or equal to the windowBits value
705  provided to deflateInit2() while compressing, or it must be equal to 15 if
706  deflateInit2() was not used. If a compressed stream with a larger window
707  size is given as input, inflate() will return with the error code
708  Z_DATA_ERROR instead of trying to allocate a larger window.
709 
710  windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
711  determines the window size. inflate() will then process raw deflate data,
712  not looking for a zlib or gzip header, not generating a check value, and not
713  looking for any check values for comparison at the end of the stream. This
714  is for use with other formats that use the deflate compressed data format
715  such as zip. Those formats provide their own check values. If a custom
716  format is developed using the raw deflate format for compressed data, it is
717  recommended that a check value such as an adler32 or a crc32 be applied to
718  the uncompressed data as is done in the zlib, gzip, and zip formats. For
719  most applications, the zlib format should be used as is. Note that comments
720  above on the use in deflateInit2() applies to the magnitude of windowBits.
721 
722  windowBits can also be greater than 15 for optional gzip decoding. Add
723  32 to windowBits to enable zlib and gzip decoding with automatic header
724  detection, or add 16 to decode only the gzip format (the zlib format will
725  return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
726  a crc32 instead of an adler32.
727 
728  inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
729  memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
730  is set to null if there is no error message. inflateInit2 does not perform
731  any decompression apart from reading the zlib header if present: this will
732  be done by inflate(). (So next_in and avail_in may be modified, but next_out
733  and avail_out are unchanged.)
734 */
735 
736 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
737  const Bytef *dictionary,
738  uInt dictLength));
739 /*
740  Initializes the decompression dictionary from the given uncompressed byte
741  sequence. This function must be called immediately after a call of inflate,
742  if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
743  can be determined from the adler32 value returned by that call of inflate.
744  The compressor and decompressor must use exactly the same dictionary (see
745  deflateSetDictionary). For raw inflate, this function can be called
746  immediately after inflateInit2() or inflateReset() and before any call of
747  inflate() to set the dictionary. The application must insure that the
748  dictionary that was used for compression is provided.
749 
750  inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
751  parameter is invalid (such as NULL dictionary) or the stream state is
752  inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
753  expected one (incorrect adler32 value). inflateSetDictionary does not
754  perform any decompression: this will be done by subsequent calls of
755  inflate().
756 */
757 
758 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
759 /*
760  Skips invalid compressed data until a full flush point (see above the
761  description of deflate with Z_FULL_FLUSH) can be found, or until all
762  available input is skipped. No output is provided.
763 
764  inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
765  if no more input was provided, Z_DATA_ERROR if no flush point has been found,
766  or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
767  case, the application may save the current current value of total_in which
768  indicates where valid compressed data was found. In the error case, the
769  application may repeatedly call inflateSync, providing more input each time,
770  until success or end of the input data.
771 */
772 
773 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
774  z_streamp source));
775 /*
776  Sets the destination stream as a complete copy of the source stream.
777 
778  This function can be useful when randomly accessing a large stream. The
779  first pass through the stream can periodically record the inflate state,
780  allowing restarting inflate at those points when randomly accessing the
781  stream.
782 
783  inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
784  enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
785  (such as zalloc being NULL). msg is left unchanged in both source and
786  destination.
787 */
788 
789 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
790 /*
791  This function is equivalent to inflateEnd followed by inflateInit,
792  but does not free and reallocate all the internal decompression state.
793  The stream will keep attributes that may have been set by inflateInit2.
794 
795  inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
796  stream state was inconsistent (such as zalloc or state being NULL).
797 */
798 
799 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
800  int bits,
801  int value));
802 /*
803  This function inserts bits in the inflate input stream. The intent is
804  that this function is used to start inflating at a bit position in the
805  middle of a byte. The provided bits will be used before any bytes are used
806  from next_in. This function should only be used with raw inflate, and
807  should be used before the first inflate() call after inflateInit2() or
808  inflateReset(). bits must be less than or equal to 16, and that many of the
809  least significant bits of value will be inserted in the input.
810 
811  inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
812  stream state was inconsistent.
813 */
814 
815 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
816  gz_headerp head));
817 /*
818  inflateGetHeader() requests that gzip header information be stored in the
819  provided gz_header structure. inflateGetHeader() may be called after
820  inflateInit2() or inflateReset(), and before the first call of inflate().
821  As inflate() processes the gzip stream, head->done is zero until the header
822  is completed, at which time head->done is set to one. If a zlib stream is
823  being decoded, then head->done is set to -1 to indicate that there will be
824  no gzip header information forthcoming. Note that Z_BLOCK can be used to
825  force inflate() to return immediately after header processing is complete
826  and before any actual data is decompressed.
827 
828  The text, time, xflags, and os fields are filled in with the gzip header
829  contents. hcrc is set to true if there is a header CRC. (The header CRC
830  was valid if done is set to one.) If extra is not Z_NULL, then extra_max
831  contains the maximum number of bytes to write to extra. Once done is true,
832  extra_len contains the actual extra field length, and extra contains the
833  extra field, or that field truncated if extra_max is less than extra_len.
834  If name is not Z_NULL, then up to name_max characters are written there,
835  terminated with a zero unless the length is greater than name_max. If
836  comment is not Z_NULL, then up to comm_max characters are written there,
837  terminated with a zero unless the length is greater than comm_max. When
838  any of extra, name, or comment are not Z_NULL and the respective field is
839  not present in the header, then that field is set to Z_NULL to signal its
840  absence. This allows the use of deflateSetHeader() with the returned
841  structure to duplicate the header. However if those fields are set to
842  allocated memory, then the application will need to save those pointers
843  elsewhere so that they can be eventually freed.
844 
845  If inflateGetHeader is not used, then the header information is simply
846  discarded. The header is always checked for validity, including the header
847  CRC if present. inflateReset() will reset the process to discard the header
848  information. The application would need to call inflateGetHeader() again to
849  retrieve the header from the next gzip stream.
850 
851  inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
852  stream state was inconsistent.
853 */
854 
855 /*
856 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
857  unsigned char FAR *window));
858 
859  Initialize the internal stream state for decompression using inflateBack()
860  calls. The fields zalloc, zfree and opaque in strm must be initialized
861  before the call. If zalloc and zfree are Z_NULL, then the default library-
862  derived memory allocation routines are used. windowBits is the base two
863  logarithm of the window size, in the range 8..15. window is a caller
864  supplied buffer of that size. Except for special applications where it is
865  assured that deflate was used with small window sizes, windowBits must be 15
866  and a 32K byte window must be supplied to be able to decompress general
867  deflate streams.
868 
869  See inflateBack() for the usage of these routines.
870 
871  inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
872  the paramaters are invalid, Z_MEM_ERROR if the internal state could not
873  be allocated, or Z_VERSION_ERROR if the version of the library does not
874  match the version of the header file.
875 */
876 
877 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
878 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
879 
880 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
881  in_func in, void FAR *in_desc,
882  out_func out, void FAR *out_desc));
883 /*
884  inflateBack() does a raw inflate with a single call using a call-back
885  interface for input and output. This is more efficient than inflate() for
886  file i/o applications in that it avoids copying between the output and the
887  sliding window by simply making the window itself the output buffer. This
888  function trusts the application to not change the output buffer passed by
889  the output function, at least until inflateBack() returns.
890 
891  inflateBackInit() must be called first to allocate the internal state
892  and to initialize the state with the user-provided window buffer.
893  inflateBack() may then be used multiple times to inflate a complete, raw
894  deflate stream with each call. inflateBackEnd() is then called to free
895  the allocated state.
896 
897  A raw deflate stream is one with no zlib or gzip header or trailer.
898  This routine would normally be used in a utility that reads zip or gzip
899  files and writes out uncompressed files. The utility would decode the
900  header and process the trailer on its own, hence this routine expects
901  only the raw deflate stream to decompress. This is different from the
902  normal behavior of inflate(), which expects either a zlib or gzip header and
903  trailer around the deflate stream.
904 
905  inflateBack() uses two subroutines supplied by the caller that are then
906  called by inflateBack() for input and output. inflateBack() calls those
907  routines until it reads a complete deflate stream and writes out all of the
908  uncompressed data, or until it encounters an error. The function's
909  parameters and return types are defined above in the in_func and out_func
910  typedefs. inflateBack() will call in(in_desc, &buf) which should return the
911  number of bytes of provided input, and a pointer to that input in buf. If
912  there is no input available, in() must return zero--buf is ignored in that
913  case--and inflateBack() will return a buffer error. inflateBack() will call
914  out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
915  should return zero on success, or non-zero on failure. If out() returns
916  non-zero, inflateBack() will return with an error. Neither in() nor out()
917  are permitted to change the contents of the window provided to
918  inflateBackInit(), which is also the buffer that out() uses to write from.
919  The length written by out() will be at most the window size. Any non-zero
920  amount of input may be provided by in().
921 
922  For convenience, inflateBack() can be provided input on the first call by
923  setting strm->next_in and strm->avail_in. If that input is exhausted, then
924  in() will be called. Therefore strm->next_in must be initialized before
925  calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
926  immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
927  must also be initialized, and then if strm->avail_in is not zero, input will
928  initially be taken from strm->next_in[0 .. strm->avail_in - 1].
929 
930  The in_desc and out_desc parameters of inflateBack() is passed as the
931  first parameter of in() and out() respectively when they are called. These
932  descriptors can be optionally used to pass any information that the caller-
933  supplied in() and out() functions need to do their job.
934 
935  On return, inflateBack() will set strm->next_in and strm->avail_in to
936  pass back any unused input that was provided by the last in() call. The
937  return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
938  if in() or out() returned an error, Z_DATA_ERROR if there was a format
939  error in the deflate stream (in which case strm->msg is set to indicate the
940  nature of the error), or Z_STREAM_ERROR if the stream was not properly
941  initialized. In the case of Z_BUF_ERROR, an input or output error can be
942  distinguished using strm->next_in which will be Z_NULL only if in() returned
943  an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
944  out() returning non-zero. (in() will always be called before out(), so
945  strm->next_in is assured to be defined if out() returns non-zero.) Note
946  that inflateBack() cannot return Z_OK.
947 */
948 
949 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
950 /*
951  All memory allocated by inflateBackInit() is freed.
952 
953  inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
954  state was inconsistent.
955 */
956 
957 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
958 /* Return flags indicating compile-time options.
959 
960  Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
961  1.0: size of uInt
962  3.2: size of uLong
963  5.4: size of voidpf (pointer)
964  7.6: size of z_off_t
965 
966  Compiler, assembler, and debug options:
967  8: DEBUG
968  9: ASMV or ASMINF -- use ASM code
969  10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
970  11: 0 (reserved)
971 
972  One-time table building (smaller code, but not thread-safe if true):
973  12: BUILDFIXED -- build static block decoding tables when needed
974  13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
975  14,15: 0 (reserved)
976 
977  Library content (indicates missing functionality):
978  16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
979  deflate code when not needed)
980  17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
981  and decode gzip streams (to avoid linking crc code)
982  18-19: 0 (reserved)
983 
984  Operation variations (changes in library functionality):
985  20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
986  21: FASTEST -- deflate algorithm with only one, lowest compression level
987  22,23: 0 (reserved)
988 
989  The sprintf variant used by gzprintf (zero is best):
990  24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
991  25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
992  26: 0 = returns value, 1 = void -- 1 means inferred string length returned
993 
994  Remainder:
995  27-31: 0 (reserved)
996  */
997 
998 
999  /* utility functions */
1000 
1001 /*
1002  The following utility functions are implemented on top of the
1003  basic stream-oriented functions. To simplify the interface, some
1004  default options are assumed (compression level and memory usage,
1005  standard memory allocation functions). The source code of these
1006  utility functions can easily be modified if you need special options.
1007 */
1008 
1009 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1010  const Bytef *source, uLong sourceLen));
1011 /*
1012  Compresses the source buffer into the destination buffer. sourceLen is
1013  the byte length of the source buffer. Upon entry, destLen is the total
1014  size of the destination buffer, which must be at least the value returned
1015  by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1016  compressed buffer.
1017  This function can be used to compress a whole file at once if the
1018  input file is mmap'ed.
1019  compress returns Z_OK if success, Z_MEM_ERROR if there was not
1020  enough memory, Z_BUF_ERROR if there was not enough room in the output
1021  buffer.
1022 */
1023 
1024 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1025  const Bytef *source, uLong sourceLen,
1026  int level));
1027 /*
1028  Compresses the source buffer into the destination buffer. The level
1029  parameter has the same meaning as in deflateInit. sourceLen is the byte
1030  length of the source buffer. Upon entry, destLen is the total size of the
1031  destination buffer, which must be at least the value returned by
1032  compressBound(sourceLen). Upon exit, destLen is the actual size of the
1033  compressed buffer.
1034 
1035  compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1036  memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1037  Z_STREAM_ERROR if the level parameter is invalid.
1038 */
1039 
1040 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1041 /*
1042  compressBound() returns an upper bound on the compressed size after
1043  compress() or compress2() on sourceLen bytes. It would be used before
1044  a compress() or compress2() call to allocate the destination buffer.
1045 */
1046 
1047 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1048  const Bytef *source, uLong sourceLen));
1049 /*
1050  Decompresses the source buffer into the destination buffer. sourceLen is
1051  the byte length of the source buffer. Upon entry, destLen is the total
1052  size of the destination buffer, which must be large enough to hold the
1053  entire uncompressed data. (The size of the uncompressed data must have
1054  been saved previously by the compressor and transmitted to the decompressor
1055  by some mechanism outside the scope of this compression library.)
1056  Upon exit, destLen is the actual size of the compressed buffer.
1057  This function can be used to decompress a whole file at once if the
1058  input file is mmap'ed.
1059 
1060  uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1061  enough memory, Z_BUF_ERROR if there was not enough room in the output
1062  buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1063 */
1064 
1065 
1066 typedef voidp gzFile;
1067 
1068 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1069 /*
1070  Opens a gzip (.gz) file for reading or writing. The mode parameter
1071  is as in fopen ("rb" or "wb") but can also include a compression level
1072  ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1073  Huffman only compression as in "wb1h", or 'R' for run-length encoding
1074  as in "wb1R". (See the description of deflateInit2 for more information
1075  about the strategy parameter.)
1076 
1077  gzopen can be used to read a file which is not in gzip format; in this
1078  case gzread will directly read from the file without decompression.
1079 
1080  gzopen returns NULL if the file could not be opened or if there was
1081  insufficient memory to allocate the (de)compression state; errno
1082  can be checked to distinguish the two cases (if errno is zero, the
1083  zlib error is Z_MEM_ERROR). */
1084 
1085 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1086 /*
1087  gzdopen() associates a gzFile with the file descriptor fd. File
1088  descriptors are obtained from calls like open, dup, creat, pipe or
1089  fileno (in the file has been previously opened with fopen).
1090  The mode parameter is as in gzopen.
1091  The next call of gzclose on the returned gzFile will also close the
1092  file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1093  descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1094  gzdopen returns NULL if there was insufficient memory to allocate
1095  the (de)compression state.
1096 */
1097 
1098 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1099 /*
1100  Dynamically update the compression level or strategy. See the description
1101  of deflateInit2 for the meaning of these parameters.
1102  gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1103  opened for writing.
1104 */
1105 
1106 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1107 /*
1108  Reads the given number of uncompressed bytes from the compressed file.
1109  If the input file was not in gzip format, gzread copies the given number
1110  of bytes into the buffer.
1111  gzread returns the number of uncompressed bytes actually read (0 for
1112  end of file, -1 for error). */
1113 
1114 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1115  voidpc buf, unsigned len));
1116 /*
1117  Writes the given number of uncompressed bytes into the compressed file.
1118  gzwrite returns the number of uncompressed bytes actually written
1119  (0 in case of error).
1120 */
1121 
1122 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
1123 /*
1124  Converts, formats, and writes the args to the compressed file under
1125  control of the format string, as in fprintf. gzprintf returns the number of
1126  uncompressed bytes actually written (0 in case of error). The number of
1127  uncompressed bytes written is limited to 4095. The caller should assure that
1128  this limit is not exceeded. If it is exceeded, then gzprintf() will return
1129  return an error (0) with nothing written. In this case, there may also be a
1130  buffer overflow with unpredictable consequences, which is possible only if
1131  zlib was compiled with the insecure functions sprintf() or vsprintf()
1132  because the secure snprintf() or vsnprintf() functions were not available.
1133 */
1134 
1135 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1136 /*
1137  Writes the given null-terminated string to the compressed file, excluding
1138  the terminating null character.
1139  gzputs returns the number of characters written, or -1 in case of error.
1140 */
1141 
1142 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1143 /*
1144  Reads bytes from the compressed file until len-1 characters are read, or
1145  a newline character is read and transferred to buf, or an end-of-file
1146  condition is encountered. The string is then terminated with a null
1147  character.
1148  gzgets returns buf, or Z_NULL in case of error.
1149 */
1150 
1151 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1152 /*
1153  Writes c, converted to an unsigned char, into the compressed file.
1154  gzputc returns the value that was written, or -1 in case of error.
1155 */
1156 
1157 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1158 /*
1159  Reads one byte from the compressed file. gzgetc returns this byte
1160  or -1 in case of end of file or error.
1161 */
1162 
1163 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1164 /*
1165  Push one character back onto the stream to be read again later.
1166  Only one character of push-back is allowed. gzungetc() returns the
1167  character pushed, or -1 on failure. gzungetc() will fail if a
1168  character has been pushed but not read yet, or if c is -1. The pushed
1169  character will be discarded if the stream is repositioned with gzseek()
1170  or gzrewind().
1171 */
1172 
1173 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1174 /*
1175  Flushes all pending output into the compressed file. The parameter
1176  flush is as in the deflate() function. The return value is the zlib
1177  error number (see function gzerror below). gzflush returns Z_OK if
1178  the flush parameter is Z_FINISH and all output could be flushed.
1179  gzflush should be called only when strictly necessary because it can
1180  degrade compression.
1181 */
1182 
1183 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1184  z_off_t offset, int whence));
1185 /*
1186  Sets the starting position for the next gzread or gzwrite on the
1187  given compressed file. The offset represents a number of bytes in the
1188  uncompressed data stream. The whence parameter is defined as in lseek(2);
1189  the value SEEK_END is not supported.
1190  If the file is opened for reading, this function is emulated but can be
1191  extremely slow. If the file is opened for writing, only forward seeks are
1192  supported; gzseek then compresses a sequence of zeroes up to the new
1193  starting position.
1194 
1195  gzseek returns the resulting offset location as measured in bytes from
1196  the beginning of the uncompressed stream, or -1 in case of error, in
1197  particular if the file is opened for writing and the new starting position
1198  would be before the current position.
1199 */
1200 
1201 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1202 /*
1203  Rewinds the given file. This function is supported only for reading.
1204 
1205  gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1206 */
1207 
1208 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1209 /*
1210  Returns the starting position for the next gzread or gzwrite on the
1211  given compressed file. This position represents a number of bytes in the
1212  uncompressed data stream.
1213 
1214  gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1215 */
1216 
1217 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1218 /*
1219  Returns 1 when EOF has previously been detected reading the given
1220  input stream, otherwise zero.
1221 */
1222 
1223 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1224 /*
1225  Returns 1 if file is being read directly without decompression, otherwise
1226  zero.
1227 */
1228 
1229 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1230 /*
1231  Flushes all pending output if necessary, closes the compressed file
1232  and deallocates all the (de)compression state. The return value is the zlib
1233  error number (see function gzerror below).
1234 */
1235 
1236 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1237 /*
1238  Returns the error message for the last error which occurred on the
1239  given compressed file. errnum is set to zlib error number. If an
1240  error occurred in the file system and not in the compression library,
1241  errnum is set to Z_ERRNO and the application may consult errno
1242  to get the exact error code.
1243 */
1244 
1245 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1246 /*
1247  Clears the error and end-of-file flags for file. This is analogous to the
1248  clearerr() function in stdio. This is useful for continuing to read a gzip
1249  file that is being written concurrently.
1250 */
1251 
1252  /* checksum functions */
1253 
1254 /*
1255  These functions are not related to compression but are exported
1256  anyway because they might be useful in applications using the
1257  compression library.
1258 */
1259 
1260 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1261 /*
1262  Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1263  return the updated checksum. If buf is NULL, this function returns
1264  the required initial value for the checksum.
1265  An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1266  much faster. Usage example:
1267 
1268  uLong adler = adler32(0L, Z_NULL, 0);
1269 
1270  while (read_buffer(buffer, length) != EOF) {
1271  adler = adler32(adler, buffer, length);
1272  }
1273  if (adler != original_adler) error();
1274 */
1275 
1276 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1277  z_off_t len2));
1278 /*
1279  Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1280  and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1281  each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1282  seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1283 */
1284 
1285 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1286 /*
1287  Update a running CRC-32 with the bytes buf[0..len-1] and return the
1288  updated CRC-32. If buf is NULL, this function returns the required initial
1289  value for the for the crc. Pre- and post-conditioning (one's complement) is
1290  performed within this function so it shouldn't be done by the application.
1291  Usage example:
1292 
1293  uLong crc = crc32(0L, Z_NULL, 0);
1294 
1295  while (read_buffer(buffer, length) != EOF) {
1296  crc = crc32(crc, buffer, length);
1297  }
1298  if (crc != original_crc) error();
1299 */
1300 
1301 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1302 
1303 /*
1304  Combine two CRC-32 check values into one. For two sequences of bytes,
1305  seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1306  calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1307  check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1308  len2.
1309 */
1310 
1311 
1312  /* various hacks, don't look :) */
1313 
1314 /* deflateInit and inflateInit are macros to allow checking the zlib version
1315  * and the compiler's view of z_stream:
1316  */
1317 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1318  const char *version, int stream_size));
1319 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1320  const char *version, int stream_size));
1321 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1322  int windowBits, int memLevel,
1323  int strategy, const char *version,
1324  int stream_size));
1325 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1326  const char *version, int stream_size));
1327 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1328  unsigned char FAR *window,
1329  const char *version,
1330  int stream_size));
1331 #define deflateInit(strm, level) \
1332  deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1333 #define inflateInit(strm) \
1334  inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1335 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1336  deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1337  (strategy), ZLIB_VERSION, sizeof(z_stream))
1338 #define inflateInit2(strm, windowBits) \
1339  inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1340 #define inflateBackInit(strm, windowBits, window) \
1341  inflateBackInit_((strm), (windowBits), (window), \
1342  ZLIB_VERSION, sizeof(z_stream))
1343 
1344 
1345 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1346  struct internal_state {int dummy;}; /* hack for buggy compilers */
1347 #endif
1348 
1349 ZEXTERN const char * ZEXPORT zError OF((int));
1350 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1351 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1352 
1353 #ifdef __cplusplus
1354 }
1355 #endif
1356 
1357 #endif /* ZLIB_H */