source: rtems/cpukit/zlib/zlib.h @ fb25694c

4.115
Last change on this file since fb25694c was 8198f69, checked in by Ralf Corsepius <ralf.corsepius@…>, on 03/18/11 at 10:10:55

Import zlib-1.2.3

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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
37extern "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
77typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
78typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
79
80struct internal_state;
81
82typedef 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
103typedef z_stream FAR *z_streamp;
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*/
109typedef 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
126typedef gz_header FAR *gz_headerp;
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
212ZEXTERN 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/*
220ZEXTERN 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
242ZEXTERN 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
328ZEXTERN 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/*
343ZEXTERN 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
363ZEXTERN 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
462ZEXTERN 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/*
480ZEXTERN 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
538ZEXTERN 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
577ZEXTERN 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
595ZEXTERN 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
606ZEXTERN 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
627ZEXTERN 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
644ZEXTERN 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
653ZEXTERN 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
669ZEXTERN 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/*
694ZEXTERN 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
736ZEXTERN 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
758ZEXTERN 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
773ZEXTERN 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
789ZEXTERN 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
799ZEXTERN 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
815ZEXTERN 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/*
856ZEXTERN 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
877typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
878typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
879
880ZEXTERN 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
949ZEXTERN 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
957ZEXTERN 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
1009ZEXTERN 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
1024ZEXTERN 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
1040ZEXTERN 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
1047ZEXTERN 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
1066typedef voidp gzFile;
1067
1068ZEXTERN 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
1085ZEXTERN 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
1098ZEXTERN 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
1106ZEXTERN 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
1114ZEXTERN 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
1122ZEXTERN 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
1135ZEXTERN 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
1142ZEXTERN 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
1151ZEXTERN 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
1157ZEXTERN 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
1163ZEXTERN 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
1173ZEXTERN 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
1183ZEXTERN 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
1201ZEXTERN 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
1208ZEXTERN 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
1217ZEXTERN 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
1223ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1224/*
1225     Returns 1 if file is being read directly without decompression, otherwise
1226   zero.
1227*/
1228
1229ZEXTERN 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
1236ZEXTERN 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
1245ZEXTERN 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
1260ZEXTERN 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
1276ZEXTERN 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
1285ZEXTERN 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
1301ZEXTERN 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 */
1317ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1318                                     const char *version, int stream_size));
1319ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1320                                     const char *version, int stream_size));
1321ZEXTERN 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));
1325ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
1326                                      const char *version, int stream_size));
1327ZEXTERN 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
1349ZEXTERN const char   * ZEXPORT zError           OF((int));
1350ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp z));
1351ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
1352
1353#ifdef __cplusplus
1354}
1355#endif
1356
1357#endif /* ZLIB_H */
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