Stellarium  0.90.0
zlib.h
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
37 extern "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 
80 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
81 typedef void (*free_func) OF((voidpf opaque, voidpf address));
82 
83 struct internal_state;
84 
85 typedef 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 
106 typedef 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 */
112 typedef 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 
129 typedef 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 
216 ZEXTERN 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 /*
224 ZEXTERN 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 
246 ZEXTERN 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 
353 ZEXTERN 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 /*
368 ZEXTERN 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 
392 ZEXTERN 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 
508 ZEXTERN 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 /*
527 ZEXTERN 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 
587 ZEXTERN 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 
631 ZEXTERN 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 
649 ZEXTERN 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 
660 ZEXTERN 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 
681 ZEXTERN 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 
698 ZEXTERN 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 
713 ZEXTERN 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 
728 ZEXTERN 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 
745 ZEXTERN 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 /*
770 ZEXTERN 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 
819 ZEXTERN 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 
842 ZEXTERN 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 
857 ZEXTERN 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 
876 ZEXTERN 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 
892 ZEXTERN 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 
902 ZEXTERN 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 
914 ZEXTERN 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 
935 ZEXTERN 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 
963 ZEXTERN 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 /*
1004 ZEXTERN 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 
1025 typedef unsigned (*in_func) OF((void FAR *,
1026  z_const unsigned char FAR * FAR *));
1027 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1028 
1029 ZEXTERN 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 
1099 ZEXTERN 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 
1107 ZEXTERN 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 
1160 ZEXTERN 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 
1174 ZEXTERN 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 
1190 ZEXTERN 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 
1197 ZEXTERN 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 
1224 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1225 
1226 /*
1227 ZEXTERN 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 
1264 ZEXTERN 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 
1287 ZEXTERN 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 
1304 ZEXTERN 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 
1313 ZEXTERN 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 
1341 ZEXTERN 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 
1349 ZEXTERN 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 
1364 ZEXTERN 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 
1372 ZEXTERN 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 
1385 ZEXTERN 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 
1391 ZEXTERN 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 
1400 ZEXTERN 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 
1412 ZEXTERN 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 /*
1428 ZEXTERN 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 
1447 ZEXTERN 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 /*
1455 ZEXTERN 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 /*
1466 ZEXTERN 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 
1475 ZEXTERN 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 
1490 ZEXTERN 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 
1511 ZEXTERN 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 
1524 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1525 ZEXTERN 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 
1536 ZEXTERN 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 
1552 ZEXTERN 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 
1569 ZEXTERN 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 /*
1589 ZEXTERN 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 
1600 ZEXTERN 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 /*
1618 ZEXTERN 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  */
1633 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1634  const char *version, int stream_size));
1635 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1636  const char *version, int stream_size));
1637 ZEXTERN 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));
1641 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1642  const char *version, int stream_size));
1643 ZEXTERN 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  */
1670 struct gzFile_s {
1671  unsigned have;
1672  unsigned char *next;
1673  z_off64_t pos;
1674 };
1675 ZEXTERN 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 */
1746 ZEXTERN const char * ZEXPORT zError OF((int));
1747 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1748 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void));
1749 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1750 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1751 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1752 #if defined(_WIN32) && !defined(Z_SOLO)
1753 ZEXTERN 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
1758 ZEXTERN 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 */