1/* zlib.h -- interface of the 'zlib' general purpose compression library
2  version 1.2.8, April 28th, 2013
3
4  Copyright (C) 1995-2013 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://tools.ietf.org/html/rfc1950
28  (zlib format), rfc1951 (deflate format) and rfc1952 (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 "1.2.8"
41#define ZLIB_VERNUM 0x1280
42#define ZLIB_VER_MAJOR 1
43#define ZLIB_VER_MINOR 2
44#define ZLIB_VER_REVISION 8
45#define ZLIB_VER_SUBREVISION 0
46
47/*
48    The 'zlib' compression library provides in-memory compression and
49  decompression functions, including integrity checks of the uncompressed data.
50  This version of the library supports only one compression method (deflation)
51  but other algorithms will be added later and will have the same stream
52  interface.
53
54    Compression can be done in a single step if the buffers are large enough,
55  or can be done by repeated calls of the compression function.  In the latter
56  case, the application must provide more input and/or consume the output
57  (providing more output space) before each call.
58
59    The compressed data format used by default by the in-memory functions is
60  the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
61  around a deflate stream, which is itself documented in RFC 1951.
62
63    The library also supports reading and writing files in gzip (.gz) format
64  with an interface similar to that of stdio using the functions that start
65  with "gz".  The gzip format is different from the zlib format.  gzip is a
66  gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
67
68    This library can optionally read and write gzip streams in memory as well.
69
70    The zlib format was designed to be compact and fast for use in memory
71  and on communications channels.  The gzip format was designed for single-
72  file compression on file systems, has a larger header than zlib to maintain
73  directory information, and uses a different, slower check method than zlib.
74
75    The library does not install any signal handler.  The decoder checks
76  the consistency of the compressed data, so the library should never crash
77  even in case of corrupted input.
78*/
79
80typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
81typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
82
83struct internal_state;
84
85typedef struct z_stream_s {
86    z_const Bytef *next_in;     /* next input byte */
87    uInt     avail_in;  /* number of bytes available at next_in */
88    uLong    total_in;  /* total number of input bytes read so far */
89
90    Bytef    *next_out; /* next output byte should be put there */
91    uInt     avail_out; /* remaining free space at next_out */
92    uLong    total_out; /* total number of bytes output so far */
93
94    z_const char *msg;  /* last error message, NULL if no error */
95    struct internal_state FAR *state; /* not visible by applications */
96
97    alloc_func zalloc;  /* used to allocate the internal state */
98    free_func  zfree;   /* used to free the internal state */
99    voidpf     opaque;  /* private data object passed to zalloc and zfree */
100
101    int     data_type;  /* best guess about the data type: binary or text */
102    uLong   adler;      /* adler32 value of the uncompressed data */
103    uLong   reserved;   /* reserved for future use */
104} z_stream;
105
106typedef z_stream FAR *z_streamp;
107
108/*
109     gzip header information passed to and from zlib routines.  See RFC 1952
110  for more details on the meanings of these fields.
111*/
112typedef struct gz_header_s {
113    int     text;       /* true if compressed data believed to be text */
114    uLong   time;       /* modification time */
115    int     xflags;     /* extra flags (not used when writing a gzip file) */
116    int     os;         /* operating system */
117    Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
118    uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
119    uInt    extra_max;  /* space at extra (only when reading header) */
120    Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
121    uInt    name_max;   /* space at name (only when reading header) */
122    Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
123    uInt    comm_max;   /* space at comment (only when reading header) */
124    int     hcrc;       /* true if there was or will be a header crc */
125    int     done;       /* true when done reading gzip header (not used
126                           when writing a gzip file) */
127} gz_header;
128
129typedef gz_header FAR *gz_headerp;
130
131/*
132     The application must update next_in and avail_in when avail_in has dropped
133   to zero.  It must update next_out and avail_out when avail_out has dropped
134   to zero.  The application must initialize zalloc, zfree and opaque before
135   calling the init function.  All other fields are set by the compression
136   library and must not be updated by the application.
137
138     The opaque value provided by the application will be passed as the first
139   parameter for calls of zalloc and zfree.  This can be useful for custom
140   memory management.  The compression library attaches no meaning to the
141   opaque value.
142
143     zalloc must return Z_NULL if there is not enough memory for the object.
144   If zlib is used in a multi-threaded application, zalloc and zfree must be
145   thread safe.
146
147     On 16-bit systems, the functions zalloc and zfree must be able to allocate
148   exactly 65536 bytes, but will not be required to allocate more than this if
149   the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
150   returned by zalloc for objects of exactly 65536 bytes *must* have their
151   offset normalized to zero.  The default allocation function provided by this
152   library ensures this (see zutil.c).  To reduce memory requirements and avoid
153   any allocation of 64K objects, at the expense of compression ratio, compile
154   the library with -DMAX_WBITS=14 (see zconf.h).
155
156     The fields total_in and total_out can be used for statistics or progress
157   reports.  After compression, total_in holds the total size of the
158   uncompressed data and may be saved for use in the decompressor (particularly
159   if the decompressor wants to decompress everything in a single step).
160*/
161
162                        /* constants */
163
164#define Z_NO_FLUSH      0
165#define Z_PARTIAL_FLUSH 1
166#define Z_SYNC_FLUSH    2
167#define Z_FULL_FLUSH    3
168#define Z_FINISH        4
169#define Z_BLOCK         5
170#define Z_TREES         6
171/* Allowed flush values; see deflate() and inflate() below for details */
172
173#define Z_OK            0
174#define Z_STREAM_END    1
175#define Z_NEED_DICT     2
176#define Z_ERRNO        (-1)
177#define Z_STREAM_ERROR (-2)
178#define Z_DATA_ERROR   (-3)
179#define Z_MEM_ERROR    (-4)
180#define Z_BUF_ERROR    (-5)
181#define Z_VERSION_ERROR (-6)
182/* Return codes for the compression/decompression functions. Negative values
183 * are errors, positive values are used for special but normal events.
184 */
185
186#define Z_NO_COMPRESSION         0
187#define Z_BEST_SPEED             1
188#define Z_BEST_COMPRESSION       9
189#define Z_DEFAULT_COMPRESSION  (-1)
190/* compression levels */
191
192#define Z_FILTERED            1
193#define Z_HUFFMAN_ONLY        2
194#define Z_RLE                 3
195#define Z_FIXED               4
196#define Z_DEFAULT_STRATEGY    0
197/* compression strategy; see deflateInit2() below for details */
198
199#define Z_BINARY   0
200#define Z_TEXT     1
201#define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
202#define Z_UNKNOWN  2
203/* Possible values of the data_type field (though see inflate()) */
204
205#define Z_DEFLATED   8
206/* The deflate compression method (the only one supported in this version) */
207
208#define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
209
210#define zlib_version zlibVersion()
211/* for compatibility with versions < 1.0.2 */
212
213
214                        /* basic functions */
215
216ZEXTERN const char * ZEXPORT zlibVersion OF((void));
217/* The application can compare zlibVersion and ZLIB_VERSION for consistency.
218   If the first character differs, the library code actually used is not
219   compatible with the zlib.h header file used by the application.  This check
220   is automatically made by deflateInit and inflateInit.
221 */
222
223/*
224ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
225
226     Initializes the internal stream state for compression.  The fields
227   zalloc, zfree and opaque must be initialized before by the caller.  If
228   zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
229   allocation functions.
230
231     The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
232   1 gives best speed, 9 gives best compression, 0 gives no compression at all
233   (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
234   requests a default compromise between speed and compression (currently
235   equivalent to level 6).
236
237     deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
238   memory, Z_STREAM_ERROR if level is not a valid compression level, or
239   Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
240   with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
241   if there is no error message.  deflateInit does not perform any compression:
242   this will be done by deflate().
243*/
244
245
246ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
247/*
248    deflate compresses as much data as possible, and stops when the input
249  buffer becomes empty or the output buffer becomes full.  It may introduce
250  some output latency (reading input without producing any output) except when
251  forced to flush.
252
253    The detailed semantics are as follows.  deflate performs one or both of the
254  following actions:
255
256  - Compress more input starting at next_in and update next_in and avail_in
257    accordingly.  If not all input can be processed (because there is not
258    enough room in the output buffer), next_in and avail_in are updated and
259    processing will resume at this point for the next call of deflate().
260
261  - Provide more output starting at next_out and update next_out and avail_out
262    accordingly.  This action is forced if the parameter flush is non zero.
263    Forcing flush frequently degrades the compression ratio, so this parameter
264    should be set only when necessary (in interactive applications).  Some
265    output may be provided even if flush is not set.
266
267    Before the call of deflate(), the application should ensure that at least
268  one of the actions is possible, by providing more input and/or consuming more
269  output, and updating avail_in or avail_out accordingly; avail_out should
270  never be zero before the call.  The application can consume the compressed
271  output when it wants, for example when the output buffer is full (avail_out
272  == 0), or after each call of deflate().  If deflate returns Z_OK and with
273  zero avail_out, it must be called again after making room in the output
274  buffer because there might be more output pending.
275
276    Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
277  decide how much data to accumulate before producing output, in order to
278  maximize compression.
279
280    If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
281  flushed to the output buffer and the output is aligned on a byte boundary, so
282  that the decompressor can get all input data available so far.  (In
283  particular avail_in is zero after the call if enough output space has been
284  provided before the call.) Flushing may degrade compression for some
285  compression algorithms and so it should be used only when necessary.  This
286  completes the current deflate block and follows it with an empty stored block
287  that is three bits plus filler bits to the next byte, followed by four bytes
288  (00 00 ff ff).
289
290    If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
291  output buffer, but the output is not aligned to a byte boundary.  All of the
292  input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
293  This completes the current deflate block and follows it with an empty fixed
294  codes block that is 10 bits long.  This assures that enough bytes are output
295  in order for the decompressor to finish the block before the empty fixed code
296  block.
297
298    If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
299  for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
300  seven bits of the current block are held to be written as the next byte after
301  the next deflate block is completed.  In this case, the decompressor may not
302  be provided enough bits at this point in order to complete decompression of
303  the data provided so far to the compressor.  It may need to wait for the next
304  block to be emitted.  This is for advanced applications that need to control
305  the emission of deflate blocks.
306
307    If flush is set to Z_FULL_FLUSH, all output is flushed as with
308  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
309  restart from this point if previous compressed data has been damaged or if
310  random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
311  compression.
312
313    If deflate returns with avail_out == 0, this function must be called again
314  with the same value of the flush parameter and more output space (updated
315  avail_out), until the flush is complete (deflate returns with non-zero
316  avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
317  avail_out is greater than six to avoid repeated flush markers due to
318  avail_out == 0 on return.
319
320    If the parameter flush is set to Z_FINISH, pending input is processed,
321  pending output is flushed and deflate returns with Z_STREAM_END if there was
322  enough output space; if deflate returns with Z_OK, this function must be
323  called again with Z_FINISH and more output space (updated avail_out) but no
324  more input data, until it returns with Z_STREAM_END or an error.  After
325  deflate has returned Z_STREAM_END, the only possible operations on the stream
326  are deflateReset or deflateEnd.
327
328    Z_FINISH can be used immediately after deflateInit if all the compression
329  is to be done in a single step.  In this case, avail_out must be at least the
330  value returned by deflateBound (see below).  Then deflate is guaranteed to
331  return Z_STREAM_END.  If not enough output space is provided, deflate will
332  not return Z_STREAM_END, and it must be called again as described above.
333
334    deflate() sets strm->adler to the adler32 checksum of all input read
335  so far (that is, total_in bytes).
336
337    deflate() may update strm->data_type if it can make a good guess about
338  the input data type (Z_BINARY or Z_TEXT).  In doubt, the data is considered
339  binary.  This field is only for information purposes and does not affect the
340  compression algorithm in any manner.
341
342    deflate() returns Z_OK if some progress has been made (more input
343  processed or more output produced), Z_STREAM_END if all input has been
344  consumed and all output has been produced (only when flush is set to
345  Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
346  if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
347  (for example avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not
348  fatal, and deflate() can be called again with more input and more output
349  space to continue compressing.
350*/
351
352
353ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
354/*
355     All dynamically allocated data structures for this stream are freed.
356   This function discards any unprocessed input and does not flush any pending
357   output.
358
359     deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
360   stream state was inconsistent, Z_DATA_ERROR if the stream was freed
361   prematurely (some input or output was discarded).  In the error case, msg
362   may be set but then points to a static string (which must not be
363   deallocated).
364*/
365
366
367/*
368ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
369
370     Initializes the internal stream state for decompression.  The fields
371   next_in, avail_in, zalloc, zfree and opaque must be initialized before by
372   the caller.  If next_in is not Z_NULL and avail_in is large enough (the
373   exact value depends on the compression method), inflateInit determines the
374   compression method from the zlib header and allocates all data structures
375   accordingly; otherwise the allocation will be deferred to the first call of
376   inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
377   use default allocation functions.
378
379     inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
380   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
381   version assumed by the caller, or Z_STREAM_ERROR if the parameters are
382   invalid, such as a null pointer to the structure.  msg is set to null if
383   there is no error message.  inflateInit does not perform any decompression
384   apart from possibly reading the zlib header if present: actual decompression
385   will be done by inflate().  (So next_in and avail_in may be modified, but
386   next_out and avail_out are unused and unchanged.) The current implementation
387   of inflateInit() does not process any header information -- that is deferred
388   until inflate() is called.
389*/
390
391
392ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
393/*
394    inflate decompresses as much data as possible, and stops when the input
395  buffer becomes empty or the output buffer becomes full.  It may introduce
396  some output latency (reading input without producing any output) except when
397  forced to flush.
398
399  The detailed semantics are as follows.  inflate performs one or both of the
400  following actions:
401
402  - Decompress more input starting at next_in and update next_in and avail_in
403    accordingly.  If not all input can be processed (because there is not
404    enough room in the output buffer), next_in is updated and processing will
405    resume at this point for the next call of inflate().
406
407  - Provide more output starting at next_out and update next_out and avail_out
408    accordingly.  inflate() provides as much output as possible, until there is
409    no more input data or no more space in the output buffer (see below about
410    the flush parameter).
411
412    Before the call of inflate(), the application should ensure that at least
413  one of the actions is possible, by providing more input and/or consuming more
414  output, and updating the next_* and avail_* values accordingly.  The
415  application can consume the uncompressed output when it wants, for example
416  when the output buffer is full (avail_out == 0), or after each call of
417  inflate().  If inflate returns Z_OK and with zero avail_out, it must be
418  called again after making room in the output buffer because there might be
419  more output pending.
420
421    The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
422  Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
423  output as possible to the output buffer.  Z_BLOCK requests that inflate()
424  stop if and when it gets to the next deflate block boundary.  When decoding
425  the zlib or gzip format, this will cause inflate() to return immediately
426  after the header and before the first block.  When doing a raw inflate,
427  inflate() will go ahead and process the first block, and will return when it
428  gets to the end of that block, or when it runs out of data.
429
430    The Z_BLOCK option assists in appending to or combining deflate streams.
431  Also to assist in this, on return inflate() will set strm->data_type to the
432  number of unused bits in the last byte taken from strm->next_in, plus 64 if
433  inflate() is currently decoding the last block in the deflate stream, plus
434  128 if inflate() returned immediately after decoding an end-of-block code or
435  decoding the complete header up to just before the first byte of the deflate
436  stream.  The end-of-block will not be indicated until all of the uncompressed
437  data from that block has been written to strm->next_out.  The number of
438  unused bits may in general be greater than seven, except when bit 7 of
439  data_type is set, in which case the number of unused bits will be less than
440  eight.  data_type is set as noted here every time inflate() returns for all
441  flush options, and so can be used to determine the amount of currently
442  consumed input in bits.
443
444    The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
445  end of each deflate block header is reached, before any actual data in that
446  block is decoded.  This allows the caller to determine the length of the
447  deflate block header for later use in random access within a deflate block.
448  256 is added to the value of strm->data_type when inflate() returns
449  immediately after reaching the end of the deflate block header.
450
451    inflate() should normally be called until it returns Z_STREAM_END or an
452  error.  However if all decompression is to be performed in a single step (a
453  single call of inflate), the parameter flush should be set to Z_FINISH.  In
454  this case all pending input is processed and all pending output is flushed;
455  avail_out must be large enough to hold all of the uncompressed data for the
456  operation to complete.  (The size of the uncompressed data may have been
457  saved by the compressor for this purpose.) The use of Z_FINISH is not
458  required to perform an inflation in one step.  However it may be used to
459  inform inflate that a faster approach can be used for the single inflate()
460  call.  Z_FINISH also informs inflate to not maintain a sliding window if the
461  stream completes, which reduces inflate's memory footprint.  If the stream
462  does not complete, either because not all of the stream is provided or not
463  enough output space is provided, then a sliding window will be allocated and
464  inflate() can be called again to continue the operation as if Z_NO_FLUSH had
465  been used.
466
467     In this implementation, inflate() always flushes as much output as
468  possible to the output buffer, and always uses the faster approach on the
469  first call.  So the effects of the flush parameter in this implementation are
470  on the return value of inflate() as noted below, when inflate() returns early
471  when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
472  memory for a sliding window when Z_FINISH is used.
473
474     If a preset dictionary is needed after this call (see inflateSetDictionary
475  below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
476  chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
477  strm->adler to the Adler-32 checksum of all output produced so far (that is,
478  total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
479  below.  At the end of the stream, inflate() checks that its computed adler32
480  checksum is equal to that saved by the compressor and returns Z_STREAM_END
481  only if the checksum is correct.
482
483    inflate() can decompress and check either zlib-wrapped or gzip-wrapped
484  deflate data.  The header type is detected automatically, if requested when
485  initializing with inflateInit2().  Any information contained in the gzip
486  header is not retained, so applications that need that information should
487  instead use raw inflate, see inflateInit2() below, or inflateBack() and
488  perform their own processing of the gzip header and trailer.  When processing
489  gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
490  producted so far.  The CRC-32 is checked against the gzip trailer.
491
492    inflate() returns Z_OK if some progress has been made (more input processed
493  or more output produced), Z_STREAM_END if the end of the compressed data has
494  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
495  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
496  corrupted (input stream not conforming to the zlib format or incorrect check
497  value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
498  next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
499  Z_BUF_ERROR if no progress is possible or if there was not enough room in the
500  output buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
501  inflate() can be called again with more input and more output space to
502  continue decompressing.  If Z_DATA_ERROR is returned, the application may
503  then call inflateSync() to look for a good compression block if a partial
504  recovery of the data is desired.
505*/
506
507
508ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
509/*
510     All dynamically allocated data structures for this stream are freed.
511   This function discards any unprocessed input and does not flush any pending
512   output.
513
514     inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
515   was inconsistent.  In the error case, msg may be set but then points to a
516   static string (which must not be deallocated).
517*/
518
519
520                        /* Advanced functions */
521
522/*
523    The following functions are needed only in some special applications.
524*/
525
526/*
527ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
528                                     int  level,
529                                     int  method,
530                                     int  windowBits,
531                                     int  memLevel,
532                                     int  strategy));
533
534     This is another version of deflateInit with more compression options.  The
535   fields next_in, zalloc, zfree and opaque must be initialized before by the
536   caller.
537
538     The method parameter is the compression method.  It must be Z_DEFLATED in
539   this version of the library.
540
541     The windowBits parameter is the base two logarithm of the window size
542   (the size of the history buffer).  It should be in the range 8..15 for this
543   version of the library.  Larger values of this parameter result in better
544   compression at the expense of memory usage.  The default value is 15 if
545   deflateInit is used instead.
546
547     windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
548   determines the window size.  deflate() will then generate raw deflate data
549   with no zlib header or trailer, and will not compute an adler32 check value.
550
551     windowBits can also be greater than 15 for optional gzip encoding.  Add
552   16 to windowBits to write a simple gzip header and trailer around the
553   compressed data instead of a zlib wrapper.  The gzip header will have no
554   file name, no extra data, no comment, no modification time (set to zero), no
555   header crc, and the operating system will be set to 255 (unknown).  If a
556   gzip stream is being written, strm->adler is a crc32 instead of an adler32.
557
558     The memLevel parameter specifies how much memory should be allocated
559   for the internal compression state.  memLevel=1 uses minimum memory but is
560   slow and reduces compression ratio; memLevel=9 uses maximum memory for
561   optimal speed.  The default value is 8.  See zconf.h for total memory usage
562   as a function of windowBits and memLevel.
563
564     The strategy parameter is used to tune the compression algorithm.  Use the
565   value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
566   filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
567   string match), or Z_RLE to limit match distances to one (run-length
568   encoding).  Filtered data consists mostly of small values with a somewhat
569   random distribution.  In this case, the compression algorithm is tuned to
570   compress them better.  The effect of Z_FILTERED is to force more Huffman
571   coding and less string matching; it is somewhat intermediate between
572   Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
573   fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
574   strategy parameter only affects the compression ratio but not the
575   correctness of the compressed output even if it is not set appropriately.
576   Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
577   decoder for special applications.
578
579     deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
580   memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
581   method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
582   incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
583   set to null if there is no error message.  deflateInit2 does not perform any
584   compression: this will be done by deflate().
585*/
586
587ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
588                                             const Bytef *dictionary,
589                                             uInt  dictLength));
590/*
591     Initializes the compression dictionary from the given byte sequence
592   without producing any compressed output.  When using the zlib format, this
593   function must be called immediately after deflateInit, deflateInit2 or
594   deflateReset, and before any call of deflate.  When doing raw deflate, this
595   function must be called either before any call of deflate, or immediately
596   after the completion of a deflate block, i.e. after all input has been
597   consumed and all output has been delivered when using any of the flush
598   options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
599   compressor and decompressor must use exactly the same dictionary (see
600   inflateSetDictionary).
601
602     The dictionary should consist of strings (byte sequences) that are likely
603   to be encountered later in the data to be compressed, with the most commonly
604   used strings preferably put towards the end of the dictionary.  Using a
605   dictionary is most useful when the data to be compressed is short and can be
606   predicted with good accuracy; the data can then be compressed better than
607   with the default empty dictionary.
608
609     Depending on the size of the compression data structures selected by
610   deflateInit or deflateInit2, a part of the dictionary may in effect be
611   discarded, for example if the dictionary is larger than the window size
612   provided in deflateInit or deflateInit2.  Thus the strings most likely to be
613   useful should be put at the end of the dictionary, not at the front.  In
614   addition, the current implementation of deflate will use at most the window
615   size minus 262 bytes of the provided dictionary.
616
617     Upon return of this function, strm->adler is set to the adler32 value
618   of the dictionary; the decompressor may later use this value to determine
619   which dictionary has been used by the compressor.  (The adler32 value
620   applies to the whole dictionary even if only a subset of the dictionary is
621   actually used by the compressor.) If a raw deflate was requested, then the
622   adler32 value is not computed and strm->adler is not set.
623
624     deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
625   parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
626   inconsistent (for example if deflate has already been called for this stream
627   or if not at a block boundary for raw deflate).  deflateSetDictionary does
628   not perform any compression: this will be done by deflate().
629*/
630
631ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
632                                    z_streamp source));
633/*
634     Sets the destination stream as a complete copy of the source stream.
635
636     This function can be useful when several compression strategies will be
637   tried, for example when there are several ways of pre-processing the input
638   data with a filter.  The streams that will be discarded should then be freed
639   by calling deflateEnd.  Note that deflateCopy duplicates the internal
640   compression state which can be quite large, so this strategy is slow and can
641   consume lots of memory.
642
643     deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
644   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
645   (such as zalloc being Z_NULL).  msg is left unchanged in both source and
646   destination.
647*/
648
649ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
650/*
651     This function is equivalent to deflateEnd followed by deflateInit,
652   but does not free and reallocate all the internal compression state.  The
653   stream will keep the same compression level and any other attributes that
654   may have been set by deflateInit2.
655
656     deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
657   stream state was inconsistent (such as zalloc or state being Z_NULL).
658*/
659
660ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
661                                      int level,
662                                      int strategy));
663/*
664     Dynamically update the compression level and compression strategy.  The
665   interpretation of level and strategy is as in deflateInit2.  This can be
666   used to switch between compression and straight copy of the input data, or
667   to switch to a different kind of input data requiring a different strategy.
668   If the compression level is changed, the input available so far is
669   compressed with the old level (and may be flushed); the new level will take
670   effect only at the next call of deflate().
671
672     Before the call of deflateParams, the stream state must be set as for
673   a call of deflate(), since the currently available input may have to be
674   compressed and flushed.  In particular, strm->avail_out must be non-zero.
675
676     deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
677   stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
678   strm->avail_out was zero.
679*/
680
681ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
682                                    int good_length,
683                                    int max_lazy,
684                                    int nice_length,
685                                    int max_chain));
686/*
687     Fine tune deflate's internal compression parameters.  This should only be
688   used by someone who understands the algorithm used by zlib's deflate for
689   searching for the best matching string, and even then only by the most
690   fanatic optimizer trying to squeeze out the last compressed bit for their
691   specific input data.  Read the deflate.c source code for the meaning of the
692   max_lazy, good_length, nice_length, and max_chain parameters.
693
694     deflateTune() can be called after deflateInit() or deflateInit2(), and
695   returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
696 */
697
698ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
699                                       uLong sourceLen));
700/*
701     deflateBound() returns an upper bound on the compressed size after
702   deflation of sourceLen bytes.  It must be called after deflateInit() or
703   deflateInit2(), and after deflateSetHeader(), if used.  This would be used
704   to allocate an output buffer for deflation in a single pass, and so would be
705   called before deflate().  If that first deflate() call is provided the
706   sourceLen input bytes, an output buffer allocated to the size returned by
707   deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
708   to return Z_STREAM_END.  Note that it is possible for the compressed size to
709   be larger than the value returned by deflateBound() if flush options other
710   than Z_FINISH or Z_NO_FLUSH are used.
711*/
712
713ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
714                                       unsigned *pending,
715                                       int *bits));
716/*
717     deflatePending() returns the number of bytes and bits of output that have
718   been generated, but not yet provided in the available output.  The bytes not
719   provided would be due to the available output space having being consumed.
720   The number of bits of output not provided are between 0 and 7, where they
721   await more bits to join them in order to fill out a full byte.  If pending
722   or bits are Z_NULL, then those values are not set.
723
724     deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
725   stream state was inconsistent.
726 */
727
728ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
729                                     int bits,
730                                     int value));
731/*
732     deflatePrime() inserts bits in the deflate output stream.  The intent
733   is that this function is used to start off the deflate output with the bits
734   leftover from a previous deflate stream when appending to it.  As such, this
735   function can only be used for raw deflate, and must be used before the first
736   deflate() call after a deflateInit2() or deflateReset().  bits must be less
737   than or equal to 16, and that many of the least significant bits of value
738   will be inserted in the output.
739
740     deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
741   room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
742   source stream state was inconsistent.
743*/
744
745ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
746                                         gz_headerp head));
747/*
748     deflateSetHeader() provides gzip header information for when a gzip
749   stream is requested by deflateInit2().  deflateSetHeader() may be called
750   after deflateInit2() or deflateReset() and before the first call of
751   deflate().  The text, time, os, extra field, name, and comment information
752   in the provided gz_header structure are written to the gzip header (xflag is
753   ignored -- the extra flags are set according to the compression level).  The
754   caller must assure that, if not Z_NULL, name and comment are terminated with
755   a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
756   available there.  If hcrc is true, a gzip header crc is included.  Note that
757   the current versions of the command-line version of gzip (up through version
758   1.3.x) do not support header crc's, and will report that it is a "multi-part
759   gzip file" and give up.
760
761     If deflateSetHeader is not used, the default gzip header has text false,
762   the time set to zero, and os set to 255, with no extra, name, or comment
763   fields.  The gzip header is returned to the default state by deflateReset().
764
765     deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
766   stream state was inconsistent.
767*/
768
769/*
770ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
771                                     int  windowBits));
772
773     This is another version of inflateInit with an extra parameter.  The
774   fields next_in, avail_in, zalloc, zfree and opaque must be initialized
775   before by the caller.
776
777     The windowBits parameter is the base two logarithm of the maximum window
778   size (the size of the history buffer).  It should be in the range 8..15 for
779   this version of the library.  The default value is 15 if inflateInit is used
780   instead.  windowBits must be greater than or equal to the windowBits value
781   provided to deflateInit2() while compressing, or it must be equal to 15 if
782   deflateInit2() was not used.  If a compressed stream with a larger window
783   size is given as input, inflate() will return with the error code
784   Z_DATA_ERROR instead of trying to allocate a larger window.
785
786     windowBits can also be zero to request that inflate use the window size in
787   the zlib header of the compressed stream.
788
789     windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
790   determines the window size.  inflate() will then process raw deflate data,
791   not looking for a zlib or gzip header, not generating a check value, and not
792   looking for any check values for comparison at the end of the stream.  This
793   is for use with other formats that use the deflate compressed data format
794   such as zip.  Those formats provide their own check values.  If a custom
795   format is developed using the raw deflate format for compressed data, it is
796   recommended that a check value such as an adler32 or a crc32 be applied to
797   the uncompressed data as is done in the zlib, gzip, and zip formats.  For
798   most applications, the zlib format should be used as is.  Note that comments
799   above on the use in deflateInit2() applies to the magnitude of windowBits.
800
801     windowBits can also be greater than 15 for optional gzip decoding.  Add
802   32 to windowBits to enable zlib and gzip decoding with automatic header
803   detection, or add 16 to decode only the gzip format (the zlib format will
804   return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
805   crc32 instead of an adler32.
806
807     inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
808   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
809   version assumed by the caller, or Z_STREAM_ERROR if the parameters are
810   invalid, such as a null pointer to the structure.  msg is set to null if
811   there is no error message.  inflateInit2 does not perform any decompression
812   apart from possibly reading the zlib header if present: actual decompression
813   will be done by inflate().  (So next_in and avail_in may be modified, but
814   next_out and avail_out are unused and unchanged.) The current implementation
815   of inflateInit2() does not process any header information -- that is
816   deferred until inflate() is called.
817*/
818
819ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
820                                             const Bytef *dictionary,
821                                             uInt  dictLength));
822/*
823     Initializes the decompression dictionary from the given uncompressed byte
824   sequence.  This function must be called immediately after a call of inflate,
825   if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
826   can be determined from the adler32 value returned by that call of inflate.
827   The compressor and decompressor must use exactly the same dictionary (see
828   deflateSetDictionary).  For raw inflate, this function can be called at any
829   time to set the dictionary.  If the provided dictionary is smaller than the
830   window and there is already data in the window, then the provided dictionary
831   will amend what's there.  The application must insure that the dictionary
832   that was used for compression is provided.
833
834     inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
835   parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
836   inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
837   expected one (incorrect adler32 value).  inflateSetDictionary does not
838   perform any decompression: this will be done by subsequent calls of
839   inflate().
840*/
841
842ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
843                                             Bytef *dictionary,
844                                             uInt  *dictLength));
845/*
846     Returns the sliding dictionary being maintained by inflate.  dictLength is
847   set to the number of bytes in the dictionary, and that many bytes are copied
848   to dictionary.  dictionary must have enough space, where 32768 bytes is
849   always enough.  If inflateGetDictionary() is called with dictionary equal to
850   Z_NULL, then only the dictionary length is returned, and nothing is copied.
851   Similary, if dictLength is Z_NULL, then it is not set.
852
853     inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
854   stream state is inconsistent.
855*/
856
857ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
858/*
859     Skips invalid compressed data until a possible full flush point (see above
860   for the description of deflate with Z_FULL_FLUSH) can be found, or until all
861   available input is skipped.  No output is provided.
862
863     inflateSync searches for a 00 00 FF FF pattern in the compressed data.
864   All full flush points have this pattern, but not all occurrences of this
865   pattern are full flush points.
866
867     inflateSync returns Z_OK if a possible full flush point has been found,
868   Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
869   has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
870   In the success case, the application may save the current current value of
871   total_in which indicates where valid compressed data was found.  In the
872   error case, the application may repeatedly call inflateSync, providing more
873   input each time, until success or end of the input data.
874*/
875
876ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
877                                    z_streamp source));
878/*
879     Sets the destination stream as a complete copy of the source stream.
880
881     This function can be useful when randomly accessing a large stream.  The
882   first pass through the stream can periodically record the inflate state,
883   allowing restarting inflate at those points when randomly accessing the
884   stream.
885
886     inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
887   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
888   (such as zalloc being Z_NULL).  msg is left unchanged in both source and
889   destination.
890*/
891
892ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
893/*
894     This function is equivalent to inflateEnd followed by inflateInit,
895   but does not free and reallocate all the internal decompression state.  The
896   stream will keep attributes that may have been set by inflateInit2.
897
898     inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
899   stream state was inconsistent (such as zalloc or state being Z_NULL).
900*/
901
902ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
903                                      int windowBits));
904/*
905     This function is the same as inflateReset, but it also permits changing
906   the wrap and window size requests.  The windowBits parameter is interpreted
907   the same as it is for inflateInit2.
908
909     inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
910   stream state was inconsistent (such as zalloc or state being Z_NULL), or if
911   the windowBits parameter is invalid.
912*/
913
914ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
915                                     int bits,
916                                     int value));
917/*
918     This function inserts bits in the inflate input stream.  The intent is
919   that this function is used to start inflating at a bit position in the
920   middle of a byte.  The provided bits will be used before any bytes are used
921   from next_in.  This function should only be used with raw inflate, and
922   should be used before the first inflate() call after inflateInit2() or
923   inflateReset().  bits must be less than or equal to 16, and that many of the
924   least significant bits of value will be inserted in the input.
925
926     If bits is negative, then the input stream bit buffer is emptied.  Then
927   inflatePrime() can be called again to put bits in the buffer.  This is used
928   to clear out bits leftover after feeding inflate a block description prior
929   to feeding inflate codes.
930
931     inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
932   stream state was inconsistent.
933*/
934
935ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
936/*
937     This function returns two values, one in the lower 16 bits of the return
938   value, and the other in the remaining upper bits, obtained by shifting the
939   return value down 16 bits.  If the upper value is -1 and the lower value is
940   zero, then inflate() is currently decoding information outside of a block.
941   If the upper value is -1 and the lower value is non-zero, then inflate is in
942   the middle of a stored block, with the lower value equaling the number of
943   bytes from the input remaining to copy.  If the upper value is not -1, then
944   it is the number of bits back from the current bit position in the input of
945   the code (literal or length/distance pair) currently being processed.  In
946   that case the lower value is the number of bytes already emitted for that
947   code.
948
949     A code is being processed if inflate is waiting for more input to complete
950   decoding of the code, or if it has completed decoding but is waiting for
951   more output space to write the literal or match data.
952
953     inflateMark() is used to mark locations in the input data for random
954   access, which may be at bit positions, and to note those cases where the
955   output of a code may span boundaries of random access blocks.  The current
956   location in the input stream can be determined from avail_in and data_type
957   as noted in the description for the Z_BLOCK flush parameter for inflate.
958
959     inflateMark returns the value noted above or -1 << 16 if the provided
960   source stream state was inconsistent.
961*/
962
963ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
964                                         gz_headerp head));
965/*
966     inflateGetHeader() requests that gzip header information be stored in the
967   provided gz_header structure.  inflateGetHeader() may be called after
968   inflateInit2() or inflateReset(), and before the first call of inflate().
969   As inflate() processes the gzip stream, head->done is zero until the header
970   is completed, at which time head->done is set to one.  If a zlib stream is
971   being decoded, then head->done is set to -1 to indicate that there will be
972   no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
973   used to force inflate() to return immediately after header processing is
974   complete and before any actual data is decompressed.
975
976     The text, time, xflags, and os fields are filled in with the gzip header
977   contents.  hcrc is set to true if there is a header CRC.  (The header CRC
978   was valid if done is set to one.) If extra is not Z_NULL, then extra_max
979   contains the maximum number of bytes to write to extra.  Once done is true,
980   extra_len contains the actual extra field length, and extra contains the
981   extra field, or that field truncated if extra_max is less than extra_len.
982   If name is not Z_NULL, then up to name_max characters are written there,
983   terminated with a zero unless the length is greater than name_max.  If
984   comment is not Z_NULL, then up to comm_max characters are written there,
985   terminated with a zero unless the length is greater than comm_max.  When any
986   of extra, name, or comment are not Z_NULL and the respective field is not
987   present in the header, then that field is set to Z_NULL to signal its
988   absence.  This allows the use of deflateSetHeader() with the returned
989   structure to duplicate the header.  However if those fields are set to
990   allocated memory, then the application will need to save those pointers
991   elsewhere so that they can be eventually freed.
992
993     If inflateGetHeader is not used, then the header information is simply
994   discarded.  The header is always checked for validity, including the header
995   CRC if present.  inflateReset() will reset the process to discard the header
996   information.  The application would need to call inflateGetHeader() again to
997   retrieve the header from the next gzip stream.
998
999     inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1000   stream state was inconsistent.
1001*/
1002
1003/*
1004ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1005                                        unsigned char FAR *window));
1006
1007     Initialize the internal stream state for decompression using inflateBack()
1008   calls.  The fields zalloc, zfree and opaque in strm must be initialized
1009   before the call.  If zalloc and zfree are Z_NULL, then the default library-
1010   derived memory allocation routines are used.  windowBits is the base two
1011   logarithm of the window size, in the range 8..15.  window is a caller
1012   supplied buffer of that size.  Except for special applications where it is
1013   assured that deflate was used with small window sizes, windowBits must be 15
1014   and a 32K byte window must be supplied to be able to decompress general
1015   deflate streams.
1016
1017     See inflateBack() for the usage of these routines.
1018
1019     inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1020   the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1021   allocated, or Z_VERSION_ERROR if the version of the library does not match
1022   the version of the header file.
1023*/
1024
1025typedef unsigned (*in_func) OF((void FAR *,
1026                                z_const unsigned char FAR * FAR *));
1027typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1028
1029ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1030                                    in_func in, void FAR *in_desc,
1031                                    out_func out, void FAR *out_desc));
1032/*
1033     inflateBack() does a raw inflate with a single call using a call-back
1034   interface for input and output.  This is potentially more efficient than
1035   inflate() for file i/o applications, in that it avoids copying between the
1036   output and the sliding window by simply making the window itself the output
1037   buffer.  inflate() can be faster on modern CPUs when used with large
1038   buffers.  inflateBack() trusts the application to not change the output
1039   buffer passed by the output function, at least until inflateBack() returns.
1040
1041     inflateBackInit() must be called first to allocate the internal state
1042   and to initialize the state with the user-provided window buffer.
1043   inflateBack() may then be used multiple times to inflate a complete, raw
1044   deflate stream with each call.  inflateBackEnd() is then called to free the
1045   allocated state.
1046
1047     A raw deflate stream is one with no zlib or gzip header or trailer.
1048   This routine would normally be used in a utility that reads zip or gzip
1049   files and writes out uncompressed files.  The utility would decode the
1050   header and process the trailer on its own, hence this routine expects only
1051   the raw deflate stream to decompress.  This is different from the normal
1052   behavior of inflate(), which expects either a zlib or gzip header and
1053   trailer around the deflate stream.
1054
1055     inflateBack() uses two subroutines supplied by the caller that are then
1056   called by inflateBack() for input and output.  inflateBack() calls those
1057   routines until it reads a complete deflate stream and writes out all of the
1058   uncompressed data, or until it encounters an error.  The function's
1059   parameters and return types are defined above in the in_func and out_func
1060   typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
1061   number of bytes of provided input, and a pointer to that input in buf.  If
1062   there is no input available, in() must return zero--buf is ignored in that
1063   case--and inflateBack() will return a buffer error.  inflateBack() will call
1064   out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
1065   should return zero on success, or non-zero on failure.  If out() returns
1066   non-zero, inflateBack() will return with an error.  Neither in() nor out()
1067   are permitted to change the contents of the window provided to
1068   inflateBackInit(), which is also the buffer that out() uses to write from.
1069   The length written by out() will be at most the window size.  Any non-zero
1070   amount of input may be provided by in().
1071
1072     For convenience, inflateBack() can be provided input on the first call by
1073   setting strm->next_in and strm->avail_in.  If that input is exhausted, then
1074   in() will be called.  Therefore strm->next_in must be initialized before
1075   calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
1076   immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
1077   must also be initialized, and then if strm->avail_in is not zero, input will
1078   initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
1079
1080     The in_desc and out_desc parameters of inflateBack() is passed as the
1081   first parameter of in() and out() respectively when they are called.  These
1082   descriptors can be optionally used to pass any information that the caller-
1083   supplied in() and out() functions need to do their job.
1084
1085     On return, inflateBack() will set strm->next_in and strm->avail_in to
1086   pass back any unused input that was provided by the last in() call.  The
1087   return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1088   if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1089   in the deflate stream (in which case strm->msg is set to indicate the nature
1090   of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1091   In the case of Z_BUF_ERROR, an input or output error can be distinguished
1092   using strm->next_in which will be Z_NULL only if in() returned an error.  If
1093   strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1094   non-zero.  (in() will always be called before out(), so strm->next_in is
1095   assured to be defined if out() returns non-zero.) Note that inflateBack()
1096   cannot return Z_OK.
1097*/
1098
1099ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1100/*
1101     All memory allocated by inflateBackInit() is freed.
1102
1103     inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1104   state was inconsistent.
1105*/
1106
1107ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1108/* Return flags indicating compile-time options.
1109
1110    Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1111     1.0: size of uInt
1112     3.2: size of uLong
1113     5.4: size of voidpf (pointer)
1114     7.6: size of z_off_t
1115
1116    Compiler, assembler, and debug options:
1117     8: DEBUG
1118     9: ASMV or ASMINF -- use ASM code
1119     10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1120     11: 0 (reserved)
1121
1122    One-time table building (smaller code, but not thread-safe if true):
1123     12: BUILDFIXED -- build static block decoding tables when needed
1124     13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1125     14,15: 0 (reserved)
1126
1127    Library content (indicates missing functionality):
1128     16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1129                          deflate code when not needed)
1130     17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1131                    and decode gzip streams (to avoid linking crc code)
1132     18-19: 0 (reserved)
1133
1134    Operation variations (changes in library functionality):
1135     20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1136     21: FASTEST -- deflate algorithm with only one, lowest compression level
1137     22,23: 0 (reserved)
1138
1139    The sprintf variant used by gzprintf (zero is best):
1140     24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1141     25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1142     26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1143
1144    Remainder:
1145     27-31: 0 (reserved)
1146 */
1147
1148#ifndef Z_SOLO
1149
1150                        /* utility functions */
1151
1152/*
1153     The following utility functions are implemented on top of the basic
1154   stream-oriented functions.  To simplify the interface, some default options
1155   are assumed (compression level and memory usage, standard memory allocation
1156   functions).  The source code of these utility functions can be modified if
1157   you need special options.
1158*/
1159
1160ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
1161                                 const Bytef *source, uLong sourceLen));
1162/*
1163     Compresses the source buffer into the destination buffer.  sourceLen is
1164   the byte length of the source buffer.  Upon entry, destLen is the total size
1165   of the destination buffer, which must be at least the value returned by
1166   compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1167   compressed buffer.
1168
1169     compress returns Z_OK if success, Z_MEM_ERROR if there was not
1170   enough memory, Z_BUF_ERROR if there was not enough room in the output
1171   buffer.
1172*/
1173
1174ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
1175                                  const Bytef *source, uLong sourceLen,
1176                                  int level));
1177/*
1178     Compresses the source buffer into the destination buffer.  The level
1179   parameter has the same meaning as in deflateInit.  sourceLen is the byte
1180   length of the source buffer.  Upon entry, destLen is the total size of the
1181   destination buffer, which must be at least the value returned by
1182   compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1183   compressed buffer.
1184
1185     compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1186   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1187   Z_STREAM_ERROR if the level parameter is invalid.
1188*/
1189
1190ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1191/*
1192     compressBound() returns an upper bound on the compressed size after
1193   compress() or compress2() on sourceLen bytes.  It would be used before a
1194   compress() or compress2() call to allocate the destination buffer.
1195*/
1196
1197ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
1198                                   const Bytef *source, uLong sourceLen));
1199/*
1200     Decompresses the source buffer into the destination buffer.  sourceLen is
1201   the byte length of the source buffer.  Upon entry, destLen is the total size
1202   of the destination buffer, which must be large enough to hold the entire
1203   uncompressed data.  (The size of the uncompressed data must have been saved
1204   previously by the compressor and transmitted to the decompressor by some
1205   mechanism outside the scope of this compression library.) Upon exit, destLen
1206   is the actual size of the uncompressed buffer.
1207
1208     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1209   enough memory, Z_BUF_ERROR if there was not enough room in the output
1210   buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
1211   the case where there is not enough room, uncompress() will fill the output
1212   buffer with the uncompressed data up to that point.
1213*/
1214
1215                        /* gzip file access functions */
1216
1217/*
1218     This library supports reading and writing files in gzip (.gz) format with
1219   an interface similar to that of stdio, using the functions that start with
1220   "gz".  The gzip format is different from the zlib format.  gzip is a gzip
1221   wrapper, documented in RFC 1952, wrapped around a deflate stream.
1222*/
1223
1224typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
1225
1226/*
1227ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1228
1229     Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
1230   in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1231   a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1232   compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1233   for fixed code compression as in "wb9F".  (See the description of
1234   deflateInit2 for more information about the strategy parameter.)  'T' will
1235   request transparent writing or appending with no compression and not using
1236   the gzip format.
1237
1238     "a" can be used instead of "w" to request that the gzip stream that will
1239   be written be appended to the file.  "+" will result in an error, since
1240   reading and writing to the same gzip file is not supported.  The addition of
1241   "x" when writing will create the file exclusively, which fails if the file
1242   already exists.  On systems that support it, the addition of "e" when
1243   reading or writing will set the flag to close the file on an execve() call.
1244
1245     These functions, as well as gzip, will read and decode a sequence of gzip
1246   streams in a file.  The append function of gzopen() can be used to create
1247   such a file.  (Also see gzflush() for another way to do this.)  When
1248   appending, gzopen does not test whether the file begins with a gzip stream,
1249   nor does it look for the end of the gzip streams to begin appending.  gzopen
1250   will simply append a gzip stream to the existing file.
1251
1252     gzopen can be used to read a file which is not in gzip format; in this
1253   case gzread will directly read from the file without decompression.  When
1254   reading, this will be detected automatically by looking for the magic two-
1255   byte gzip header.
1256
1257     gzopen returns NULL if the file could not be opened, if there was
1258   insufficient memory to allocate the gzFile state, or if an invalid mode was
1259   specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1260   errno can be checked to determine if the reason gzopen failed was that the
1261   file could not be opened.
1262*/
1263
1264ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1265/*
1266     gzdopen associates a gzFile with the file descriptor fd.  File descriptors
1267   are obtained from calls like open, dup, creat, pipe or fileno (if the file
1268   has been previously opened with fopen).  The mode parameter is as in gzopen.
1269
1270     The next call of gzclose on the returned gzFile will also close the file
1271   descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1272   fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1273   mode);.  The duplicated descriptor should be saved to avoid a leak, since
1274   gzdopen does not close fd if it fails.  If you are using fileno() to get the
1275   file descriptor from a FILE *, then you will have to use dup() to avoid
1276   double-close()ing the file descriptor.  Both gzclose() and fclose() will
1277   close the associated file descriptor, so they need to have different file
1278   descriptors.
1279
1280     gzdopen returns NULL if there was insufficient memory to allocate the
1281   gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1282   provided, or '+' was provided), or if fd is -1.  The file descriptor is not
1283   used until the next gz* read, write, seek, or close operation, so gzdopen
1284   will not detect if fd is invalid (unless fd is -1).
1285*/
1286
1287ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1288/*
1289     Set the internal buffer size used by this library's functions.  The
1290   default buffer size is 8192 bytes.  This function must be called after
1291   gzopen() or gzdopen(), and before any other calls that read or write the
1292   file.  The buffer memory allocation is always deferred to the first read or
1293   write.  Two buffers are allocated, either both of the specified size when
1294   writing, or one of the specified size and the other twice that size when
1295   reading.  A larger buffer size of, for example, 64K or 128K bytes will
1296   noticeably increase the speed of decompression (reading).
1297
1298     The new buffer size also affects the maximum length for gzprintf().
1299
1300     gzbuffer() returns 0 on success, or -1 on failure, such as being called
1301   too late.
1302*/
1303
1304ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1305/*
1306     Dynamically update the compression level or strategy.  See the description
1307   of deflateInit2 for the meaning of these parameters.
1308
1309     gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1310   opened for writing.
1311*/
1312
1313ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1314/*
1315     Reads the given number of uncompressed bytes from the compressed file.  If
1316   the input file is not in gzip format, gzread copies the given number of
1317   bytes into the buffer directly from the file.
1318
1319     After reaching the end of a gzip stream in the input, gzread will continue
1320   to read, looking for another gzip stream.  Any number of gzip streams may be
1321   concatenated in the input file, and will all be decompressed by gzread().
1322   If something other than a gzip stream is encountered after a gzip stream,
1323   that remaining trailing garbage is ignored (and no error is returned).
1324
1325     gzread can be used to read a gzip file that is being concurrently written.
1326   Upon reaching the end of the input, gzread will return with the available
1327   data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1328   gzclearerr can be used to clear the end of file indicator in order to permit
1329   gzread to be tried again.  Z_OK indicates that a gzip stream was completed
1330   on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
1331   middle of a gzip stream.  Note that gzread does not return -1 in the event
1332   of an incomplete gzip stream.  This error is deferred until gzclose(), which
1333   will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1334   stream.  Alternatively, gzerror can be used before gzclose to detect this
1335   case.
1336
1337     gzread returns the number of uncompressed bytes actually read, less than
1338   len for end of file, or -1 for error.
1339*/
1340
1341ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1342                                voidpc buf, unsigned len));
1343/*
1344     Writes the given number of uncompressed bytes into the compressed file.
1345   gzwrite returns the number of uncompressed bytes written or 0 in case of
1346   error.
1347*/
1348
1349ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1350/*
1351     Converts, formats, and writes the arguments to the compressed file under
1352   control of the format string, as in fprintf.  gzprintf returns the number of
1353   uncompressed bytes actually written, or 0 in case of error.  The number of
1354   uncompressed bytes written is limited to 8191, or one less than the buffer
1355   size given to gzbuffer().  The caller should assure that this limit is not
1356   exceeded.  If it is exceeded, then gzprintf() will return an error (0) with
1357   nothing written.  In this case, there may also be a buffer overflow with
1358   unpredictable consequences, which is possible only if zlib was compiled with
1359   the insecure functions sprintf() or vsprintf() because the secure snprintf()
1360   or vsnprintf() functions were not available.  This can be determined using
1361   zlibCompileFlags().
1362*/
1363
1364ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1365/*
1366     Writes the given null-terminated string to the compressed file, excluding
1367   the terminating null character.
1368
1369     gzputs returns the number of characters written, or -1 in case of error.
1370*/
1371
1372ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1373/*
1374     Reads bytes from the compressed file until len-1 characters are read, or a
1375   newline character is read and transferred to buf, or an end-of-file
1376   condition is encountered.  If any characters are read or if len == 1, the
1377   string is terminated with a null character.  If no characters are read due
1378   to an end-of-file or len < 1, then the buffer is left untouched.
1379
1380     gzgets returns buf which is a null-terminated string, or it returns NULL
1381   for end-of-file or in case of error.  If there was an error, the contents at
1382   buf are indeterminate.
1383*/
1384
1385ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1386/*
1387     Writes c, converted to an unsigned char, into the compressed file.  gzputc
1388   returns the value that was written, or -1 in case of error.
1389*/
1390
1391ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1392/*
1393     Reads one byte from the compressed file.  gzgetc returns this byte or -1
1394   in case of end of file or error.  This is implemented as a macro for speed.
1395   As such, it does not do all of the checking the other functions do.  I.e.
1396   it does not check to see if file is NULL, nor whether the structure file
1397   points to has been clobbered or not.
1398*/
1399
1400ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1401/*
1402     Push one character back onto the stream to be read as the first character
1403   on the next read.  At least one character of push-back is allowed.
1404   gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
1405   fail if c is -1, and may fail if a character has been pushed but not read
1406   yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
1407   output buffer size of pushed characters is allowed.  (See gzbuffer above.)
1408   The pushed character will be discarded if the stream is repositioned with
1409   gzseek() or gzrewind().
1410*/
1411
1412ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1413/*
1414     Flushes all pending output into the compressed file.  The parameter flush
1415   is as in the deflate() function.  The return value is the zlib error number
1416   (see function gzerror below).  gzflush is only permitted when writing.
1417
1418     If the flush parameter is Z_FINISH, the remaining data is written and the
1419   gzip stream is completed in the output.  If gzwrite() is called again, a new
1420   gzip stream will be started in the output.  gzread() is able to read such
1421   concatented gzip streams.
1422
1423     gzflush should be called only when strictly necessary because it will
1424   degrade compression if called too often.
1425*/
1426
1427/*
1428ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1429                                   z_off_t offset, int whence));
1430
1431     Sets the starting position for the next gzread or gzwrite on the given
1432   compressed file.  The offset represents a number of bytes in the
1433   uncompressed data stream.  The whence parameter is defined as in lseek(2);
1434   the value SEEK_END is not supported.
1435
1436     If the file is opened for reading, this function is emulated but can be
1437   extremely slow.  If the file is opened for writing, only forward seeks are
1438   supported; gzseek then compresses a sequence of zeroes up to the new
1439   starting position.
1440
1441     gzseek returns the resulting offset location as measured in bytes from
1442   the beginning of the uncompressed stream, or -1 in case of error, in
1443   particular if the file is opened for writing and the new starting position
1444   would be before the current position.
1445*/
1446
1447ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
1448/*
1449     Rewinds the given file. This function is supported only for reading.
1450
1451     gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1452*/
1453
1454/*
1455ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
1456
1457     Returns the starting position for the next gzread or gzwrite on the given
1458   compressed file.  This position represents a number of bytes in the
1459   uncompressed data stream, and is zero when starting, even if appending or
1460   reading a gzip stream from the middle of a file using gzdopen().
1461
1462     gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1463*/
1464
1465/*
1466ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1467
1468     Returns the current offset in the file being read or written.  This offset
1469   includes the count of bytes that precede the gzip stream, for example when
1470   appending or when using gzdopen() for reading.  When reading, the offset
1471   does not include as yet unused buffered input.  This information can be used
1472   for a progress indicator.  On error, gzoffset() returns -1.
1473*/
1474
1475ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1476/*
1477     Returns true (1) if the end-of-file indicator has been set while reading,
1478   false (0) otherwise.  Note that the end-of-file indicator is set only if the
1479   read tried to go past the end of the input, but came up short.  Therefore,
1480   just like feof(), gzeof() may return false even if there is no more data to
1481   read, in the event that the last read request was for the exact number of
1482   bytes remaining in the input file.  This will happen if the input file size
1483   is an exact multiple of the buffer size.
1484
1485     If gzeof() returns true, then the read functions will return no more data,
1486   unless the end-of-file indicator is reset by gzclearerr() and the input file
1487   has grown since the previous end of file was detected.
1488*/
1489
1490ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1491/*
1492     Returns true (1) if file is being copied directly while reading, or false
1493   (0) if file is a gzip stream being decompressed.
1494
1495     If the input file is empty, gzdirect() will return true, since the input
1496   does not contain a gzip stream.
1497
1498     If gzdirect() is used immediately after gzopen() or gzdopen() it will
1499   cause buffers to be allocated to allow reading the file to determine if it
1500   is a gzip file.  Therefore if gzbuffer() is used, it should be called before
1501   gzdirect().
1502
1503     When writing, gzdirect() returns true (1) if transparent writing was
1504   requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
1505   gzdirect() is not needed when writing.  Transparent writing must be
1506   explicitly requested, so the application already knows the answer.  When
1507   linking statically, using gzdirect() will include all of the zlib code for
1508   gzip file reading and decompression, which may not be desired.)
1509*/
1510
1511ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
1512/*
1513     Flushes all pending output if necessary, closes the compressed file and
1514   deallocates the (de)compression state.  Note that once file is closed, you
1515   cannot call gzerror with file, since its structures have been deallocated.
1516   gzclose must not be called more than once on the same file, just as free
1517   must not be called more than once on the same allocation.
1518
1519     gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1520   file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1521   last read ended in the middle of a gzip stream, or Z_OK on success.
1522*/
1523
1524ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1525ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1526/*
1527     Same as gzclose(), but gzclose_r() is only for use when reading, and
1528   gzclose_w() is only for use when writing or appending.  The advantage to
1529   using these instead of gzclose() is that they avoid linking in zlib
1530   compression or decompression code that is not used when only reading or only
1531   writing respectively.  If gzclose() is used, then both compression and
1532   decompression code will be included the application when linking to a static
1533   zlib library.
1534*/
1535
1536ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1537/*
1538     Returns the error message for the last error which occurred on the given
1539   compressed file.  errnum is set to zlib error number.  If an error occurred
1540   in the file system and not in the compression library, errnum is set to
1541   Z_ERRNO and the application may consult errno to get the exact error code.
1542
1543     The application must not modify the returned string.  Future calls to
1544   this function may invalidate the previously returned string.  If file is
1545   closed, then the string previously returned by gzerror will no longer be
1546   available.
1547
1548     gzerror() should be used to distinguish errors from end-of-file for those
1549   functions above that do not distinguish those cases in their return values.
1550*/
1551
1552ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1553/*
1554     Clears the error and end-of-file flags for file.  This is analogous to the
1555   clearerr() function in stdio.  This is useful for continuing to read a gzip
1556   file that is being written concurrently.
1557*/
1558
1559#endif /* !Z_SOLO */
1560
1561                        /* checksum functions */
1562
1563/*
1564     These functions are not related to compression but are exported
1565   anyway because they might be useful in applications using the compression
1566   library.
1567*/
1568
1569ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1570/*
1571     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1572   return the updated checksum.  If buf is Z_NULL, this function returns the
1573   required initial value for the checksum.
1574
1575     An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1576   much faster.
1577
1578   Usage example:
1579
1580     uLong adler = adler32(0L, Z_NULL, 0);
1581
1582     while (read_buffer(buffer, length) != EOF) {
1583       adler = adler32(adler, buffer, length);
1584     }
1585     if (adler != original_adler) error();
1586*/
1587
1588/*
1589ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1590                                          z_off_t len2));
1591
1592     Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
1593   and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1594   each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
1595   seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
1596   that the z_off_t type (like off_t) is a signed integer.  If len2 is
1597   negative, the result has no meaning or utility.
1598*/
1599
1600ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
1601/*
1602     Update a running CRC-32 with the bytes buf[0..len-1] and return the
1603   updated CRC-32.  If buf is Z_NULL, this function returns the required
1604   initial value for the crc.  Pre- and post-conditioning (one's complement) is
1605   performed within this function so it shouldn't be done by the application.
1606
1607   Usage example:
1608
1609     uLong crc = crc32(0L, Z_NULL, 0);
1610
1611     while (read_buffer(buffer, length) != EOF) {
1612       crc = crc32(crc, buffer, length);
1613     }
1614     if (crc != original_crc) error();
1615*/
1616
1617/*
1618ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1619
1620     Combine two CRC-32 check values into one.  For two sequences of bytes,
1621   seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1622   calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
1623   check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1624   len2.
1625*/
1626
1627
1628                        /* various hacks, don't look :) */
1629
1630/* deflateInit and inflateInit are macros to allow checking the zlib version
1631 * and the compiler's view of z_stream:
1632 */
1633ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1634                                     const char *version, int stream_size));
1635ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1636                                     const char *version, int stream_size));
1637ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
1638                                      int windowBits, int memLevel,
1639                                      int strategy, const char *version,
1640                                      int stream_size));
1641ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
1642                                      const char *version, int stream_size));
1643ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1644                                         unsigned char FAR *window,
1645                                         const char *version,
1646                                         int stream_size));
1647#define deflateInit(strm, level) \
1648        deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1649#define inflateInit(strm) \
1650        inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1651#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1652        deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1653                      (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1654#define inflateInit2(strm, windowBits) \
1655        inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1656                      (int)sizeof(z_stream))
1657#define inflateBackInit(strm, windowBits, window) \
1658        inflateBackInit_((strm), (windowBits), (window), \
1659                      ZLIB_VERSION, (int)sizeof(z_stream))
1660
1661#ifndef Z_SOLO
1662
1663/* gzgetc() macro and its supporting function and exposed data structure.  Note
1664 * that the real internal state is much larger than the exposed structure.
1665 * This abbreviated structure exposes just enough for the gzgetc() macro.  The
1666 * user should not mess with these exposed elements, since their names or
1667 * behavior could change in the future, perhaps even capriciously.  They can
1668 * only be used by the gzgetc() macro.  You have been warned.
1669 */
1670struct gzFile_s {
1671    unsigned have;
1672    unsigned char *next;
1673    z_off64_t pos;
1674};
1675ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
1676#ifdef Z_PREFIX_SET
1677#  undef z_gzgetc
1678#  define z_gzgetc(g) \
1679          ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
1680#else
1681#  define gzgetc(g) \
1682          ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
1683#endif
1684
1685/* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1686 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1687 * both are true, the application gets the *64 functions, and the regular
1688 * functions are changed to 64 bits) -- in case these are set on systems
1689 * without large file support, _LFS64_LARGEFILE must also be true
1690 */
1691#ifdef Z_LARGE64
1692   ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1693   ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1694   ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1695   ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1696   ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1697   ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1698#endif
1699
1700#if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1701#  ifdef Z_PREFIX_SET
1702#    define z_gzopen z_gzopen64
1703#    define z_gzseek z_gzseek64
1704#    define z_gztell z_gztell64
1705#    define z_gzoffset z_gzoffset64
1706#    define z_adler32_combine z_adler32_combine64
1707#    define z_crc32_combine z_crc32_combine64
1708#  else
1709#    define gzopen gzopen64
1710#    define gzseek gzseek64
1711#    define gztell gztell64
1712#    define gzoffset gzoffset64
1713#    define adler32_combine adler32_combine64
1714#    define crc32_combine crc32_combine64
1715#  endif
1716#  ifndef Z_LARGE64
1717     ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1718     ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1719     ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1720     ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1721     ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1722     ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1723#  endif
1724#else
1725   ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1726   ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1727   ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1728   ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1729   ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1730   ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1731#endif
1732
1733#else /* Z_SOLO */
1734
1735   ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1736   ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1737
1738#endif /* !Z_SOLO */
1739
1740/* hack for buggy compilers */
1741#if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1742    struct internal_state {int dummy;};
1743#endif
1744
1745/* undocumented functions */
1746ZEXTERN const char   * ZEXPORT zError           OF((int));
1747ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
1748ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
1749ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
1750ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
1751ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
1752#if defined(_WIN32) && !defined(Z_SOLO)
1753ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
1754                                            const char *mode));
1755#endif
1756#if defined(STDC) || defined(Z_HAVE_STDARG_H)
1757#  ifndef Z_SOLO
1758ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1759                                                  const char *format,
1760                                                  va_list va));
1761#  endif
1762#endif
1763
1764#ifdef __cplusplus
1765}
1766#endif
1767
1768#endif /* ZLIB_H */
1769