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zlib.h
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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2  version 1.2.11, January 15th, 2017
3 
4  Copyright (C) 1995-2017 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 "1.2.11"
41 #define ZLIB_VERNUM 0x12b0
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 2
44 #define ZLIB_VER_REVISION 11
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 and raw deflate streams in
69  memory as well.
70 
71  The zlib format was designed to be compact and fast for use in memory
72  and on communications channels. The gzip format was designed for single-
73  file compression on file systems, has a larger header than zlib to maintain
74  directory information, and uses a different, slower check method than zlib.
75 
76  The library does not install any signal handler. The decoder checks
77  the consistency of the compressed data, so the library should never crash
78  even in the case of corrupted input.
79 */
80 
81 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
82 typedef void (*free_func) OF((voidpf opaque, voidpf address));
83 
84 struct internal_state;
85 
86 typedef struct z_stream_s {
87  z_const Bytef *next_in; /* next input byte */
88  uInt avail_in; /* number of bytes available at next_in */
89  uLong total_in; /* total number of input bytes read so far */
90 
91  Bytef *next_out; /* next output byte will go here */
92  uInt avail_out; /* remaining free space at next_out */
93  uLong total_out; /* total number of bytes output so far */
94 
95  z_const char *msg; /* last error message, NULL if no error */
96  struct internal_state FAR *state; /* not visible by applications */
97 
98  alloc_func zalloc; /* used to allocate the internal state */
99  free_func zfree; /* used to free the internal state */
100  voidpf opaque; /* private data object passed to zalloc and zfree */
101 
102  int data_type; /* best guess about the data type: binary or text
103  for deflate, or the decoding state for inflate */
104  uLong adler; /* Adler-32 or CRC-32 value of the uncompressed data */
105  uLong reserved; /* reserved for future use */
106 } z_stream;
107 
108 typedef z_stream FAR *z_streamp;
109 
110 /*
111  gzip header information passed to and from zlib routines. See RFC 1952
112  for more details on the meanings of these fields.
113 */
114 typedef struct gz_header_s {
115  int text; /* true if compressed data believed to be text */
116  uLong time; /* modification time */
117  int xflags; /* extra flags (not used when writing a gzip file) */
118  int os; /* operating system */
119  Bytef *extra; /* pointer to extra field or Z_NULL if none */
120  uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
121  uInt extra_max; /* space at extra (only when reading header) */
122  Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
123  uInt name_max; /* space at name (only when reading header) */
124  Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
125  uInt comm_max; /* space at comment (only when reading header) */
126  int hcrc; /* true if there was or will be a header crc */
127  int done; /* true when done reading gzip header (not used
128  when writing a gzip file) */
129 } gz_header;
130 
131 typedef gz_header FAR *gz_headerp;
132 
133 /*
134  The application must update next_in and avail_in when avail_in has dropped
135  to zero. It must update next_out and avail_out when avail_out has dropped
136  to zero. The application must initialize zalloc, zfree and opaque before
137  calling the init function. All other fields are set by the compression
138  library and must not be updated by the application.
139 
140  The opaque value provided by the application will be passed as the first
141  parameter for calls of zalloc and zfree. This can be useful for custom
142  memory management. The compression library attaches no meaning to the
143  opaque value.
144 
145  zalloc must return Z_NULL if there is not enough memory for the object.
146  If zlib is used in a multi-threaded application, zalloc and zfree must be
147  thread safe. In that case, zlib is thread-safe. When zalloc and zfree are
148  Z_NULL on entry to the initialization function, they are set to internal
149  routines that use the standard library functions malloc() and free().
150 
151  On 16-bit systems, the functions zalloc and zfree must be able to allocate
152  exactly 65536 bytes, but will not be required to allocate more than this if
153  the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
154  returned by zalloc for objects of exactly 65536 bytes *must* have their
155  offset normalized to zero. The default allocation function provided by this
156  library ensures this (see zutil.c). To reduce memory requirements and avoid
157  any allocation of 64K objects, at the expense of compression ratio, compile
158  the library with -DMAX_WBITS=14 (see zconf.h).
159 
160  The fields total_in and total_out can be used for statistics or progress
161  reports. After compression, total_in holds the total size of the
162  uncompressed data and may be saved for use by the decompressor (particularly
163  if the decompressor wants to decompress everything in a single step).
164 */
165 
166  /* constants */
167 
168 #define Z_NO_FLUSH 0
169 #define Z_PARTIAL_FLUSH 1
170 #define Z_SYNC_FLUSH 2
171 #define Z_FULL_FLUSH 3
172 #define Z_FINISH 4
173 #define Z_BLOCK 5
174 #define Z_TREES 6
175 /* Allowed flush values; see deflate() and inflate() below for details */
176 
177 #define Z_OK 0
178 #define Z_STREAM_END 1
179 #define Z_NEED_DICT 2
180 #define Z_ERRNO (-1)
181 #define Z_STREAM_ERROR (-2)
182 #define Z_DATA_ERROR (-3)
183 #define Z_MEM_ERROR (-4)
184 #define Z_BUF_ERROR (-5)
185 #define Z_VERSION_ERROR (-6)
186 /* Return codes for the compression/decompression functions. Negative values
187  * are errors, positive values are used for special but normal events.
188  */
189 
190 #define Z_NO_COMPRESSION 0
191 #define Z_BEST_SPEED 1
192 #define Z_BEST_COMPRESSION 9
193 #define Z_DEFAULT_COMPRESSION (-1)
194 /* compression levels */
195 
196 #define Z_FILTERED 1
197 #define Z_HUFFMAN_ONLY 2
198 #define Z_RLE 3
199 #define Z_FIXED 4
200 #define Z_DEFAULT_STRATEGY 0
201 /* compression strategy; see deflateInit2() below for details */
202 
203 #define Z_BINARY 0
204 #define Z_TEXT 1
205 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
206 #define Z_UNKNOWN 2
207 /* Possible values of the data_type field for deflate() */
208 
209 #define Z_DEFLATED 8
210 /* The deflate compression method (the only one supported in this version) */
211 
212 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
213 
214 #define zlib_version zlibVersion()
215 /* for compatibility with versions < 1.0.2 */
216 
217 
218  /* basic functions */
219 
220 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
221 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
222  If the first character differs, the library code actually used is not
223  compatible with the zlib.h header file used by the application. This check
224  is automatically made by deflateInit and inflateInit.
225  */
226 
227 /*
228 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
229 
230  Initializes the internal stream state for compression. The fields
231  zalloc, zfree and opaque must be initialized before by the caller. If
232  zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
233  allocation functions.
234 
235  The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
236  1 gives best speed, 9 gives best compression, 0 gives no compression at all
237  (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
238  requests a default compromise between speed and compression (currently
239  equivalent to level 6).
240 
241  deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
242  memory, Z_STREAM_ERROR if level is not a valid compression level, or
243  Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
244  with the version assumed by the caller (ZLIB_VERSION). msg is set to null
245  if there is no error message. deflateInit does not perform any compression:
246  this will be done by deflate().
247 */
248 
249 
250 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
251 /*
252  deflate compresses as much data as possible, and stops when the input
253  buffer becomes empty or the output buffer becomes full. It may introduce
254  some output latency (reading input without producing any output) except when
255  forced to flush.
256 
257  The detailed semantics are as follows. deflate performs one or both of the
258  following actions:
259 
260  - Compress more input starting at next_in and update next_in and avail_in
261  accordingly. If not all input can be processed (because there is not
262  enough room in the output buffer), next_in and avail_in are updated and
263  processing will resume at this point for the next call of deflate().
264 
265  - Generate more output starting at next_out and update next_out and avail_out
266  accordingly. This action is forced if the parameter flush is non zero.
267  Forcing flush frequently degrades the compression ratio, so this parameter
268  should be set only when necessary. Some output may be provided even if
269  flush is zero.
270 
271  Before the call of deflate(), the application should ensure that at least
272  one of the actions is possible, by providing more input and/or consuming more
273  output, and updating avail_in or avail_out accordingly; avail_out should
274  never be zero before the call. The application can consume the compressed
275  output when it wants, for example when the output buffer is full (avail_out
276  == 0), or after each call of deflate(). If deflate returns Z_OK and with
277  zero avail_out, it must be called again after making room in the output
278  buffer because there might be more output pending. See deflatePending(),
279  which can be used if desired to determine whether or not there is more ouput
280  in that case.
281 
282  Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
283  decide how much data to accumulate before producing output, in order to
284  maximize compression.
285 
286  If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
287  flushed to the output buffer and the output is aligned on a byte boundary, so
288  that the decompressor can get all input data available so far. (In
289  particular avail_in is zero after the call if enough output space has been
290  provided before the call.) Flushing may degrade compression for some
291  compression algorithms and so it should be used only when necessary. This
292  completes the current deflate block and follows it with an empty stored block
293  that is three bits plus filler bits to the next byte, followed by four bytes
294  (00 00 ff ff).
295 
296  If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
297  output buffer, but the output is not aligned to a byte boundary. All of the
298  input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
299  This completes the current deflate block and follows it with an empty fixed
300  codes block that is 10 bits long. This assures that enough bytes are output
301  in order for the decompressor to finish the block before the empty fixed
302  codes block.
303 
304  If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
305  for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
306  seven bits of the current block are held to be written as the next byte after
307  the next deflate block is completed. In this case, the decompressor may not
308  be provided enough bits at this point in order to complete decompression of
309  the data provided so far to the compressor. It may need to wait for the next
310  block to be emitted. This is for advanced applications that need to control
311  the emission of deflate blocks.
312 
313  If flush is set to Z_FULL_FLUSH, all output is flushed as with
314  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
315  restart from this point if previous compressed data has been damaged or if
316  random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
317  compression.
318 
319  If deflate returns with avail_out == 0, this function must be called again
320  with the same value of the flush parameter and more output space (updated
321  avail_out), until the flush is complete (deflate returns with non-zero
322  avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
323  avail_out is greater than six to avoid repeated flush markers due to
324  avail_out == 0 on return.
325 
326  If the parameter flush is set to Z_FINISH, pending input is processed,
327  pending output is flushed and deflate returns with Z_STREAM_END if there was
328  enough output space. If deflate returns with Z_OK or Z_BUF_ERROR, this
329  function must be called again with Z_FINISH and more output space (updated
330  avail_out) but no more input data, until it returns with Z_STREAM_END or an
331  error. After deflate has returned Z_STREAM_END, the only possible operations
332  on the stream are deflateReset or deflateEnd.
333 
334  Z_FINISH can be used in the first deflate call after deflateInit if all the
335  compression is to be done in a single step. In order to complete in one
336  call, avail_out must be at least the value returned by deflateBound (see
337  below). Then deflate is guaranteed to return Z_STREAM_END. If not enough
338  output space is provided, deflate will not return Z_STREAM_END, and it must
339  be called again as described above.
340 
341  deflate() sets strm->adler to the Adler-32 checksum of all input read
342  so far (that is, total_in bytes). If a gzip stream is being generated, then
343  strm->adler will be the CRC-32 checksum of the input read so far. (See
344  deflateInit2 below.)
345 
346  deflate() may update strm->data_type if it can make a good guess about
347  the input data type (Z_BINARY or Z_TEXT). If in doubt, the data is
348  considered binary. This field is only for information purposes and does not
349  affect the compression algorithm in any manner.
350 
351  deflate() returns Z_OK if some progress has been made (more input
352  processed or more output produced), Z_STREAM_END if all input has been
353  consumed and all output has been produced (only when flush is set to
354  Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
355  if next_in or next_out was Z_NULL or the state was inadvertently written over
356  by the application), or Z_BUF_ERROR if no progress is possible (for example
357  avail_in or avail_out was zero). Note that Z_BUF_ERROR is not fatal, and
358  deflate() can be called again with more input and more output space to
359  continue compressing.
360 */
361 
362 
363 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
364 /*
365  All dynamically allocated data structures for this stream are freed.
366  This function discards any unprocessed input and does not flush any pending
367  output.
368 
369  deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
370  stream state was inconsistent, Z_DATA_ERROR if the stream was freed
371  prematurely (some input or output was discarded). In the error case, msg
372  may be set but then points to a static string (which must not be
373  deallocated).
374 */
375 
376 
377 /*
378 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
379 
380  Initializes the internal stream state for decompression. The fields
381  next_in, avail_in, zalloc, zfree and opaque must be initialized before by
382  the caller. In the current version of inflate, the provided input is not
383  read or consumed. The allocation of a sliding window will be deferred to
384  the first call of inflate (if the decompression does not complete on the
385  first call). If zalloc and zfree are set to Z_NULL, inflateInit updates
386  them to use default allocation functions.
387 
388  inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
389  memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
390  version assumed by the caller, or Z_STREAM_ERROR if the parameters are
391  invalid, such as a null pointer to the structure. msg is set to null if
392  there is no error message. inflateInit does not perform any decompression.
393  Actual decompression will be done by inflate(). So next_in, and avail_in,
394  next_out, and avail_out are unused and unchanged. The current
395  implementation of inflateInit() does not process any header information --
396  that is deferred until inflate() is called.
397 */
398 
399 
400 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
401 /*
402  inflate decompresses as much data as possible, and stops when the input
403  buffer becomes empty or the output buffer becomes full. It may introduce
404  some output latency (reading input without producing any output) except when
405  forced to flush.
406 
407  The detailed semantics are as follows. inflate performs one or both of the
408  following actions:
409 
410  - Decompress more input starting at next_in and update next_in and avail_in
411  accordingly. If not all input can be processed (because there is not
412  enough room in the output buffer), then next_in and avail_in are updated
413  accordingly, and processing will resume at this point for the next call of
414  inflate().
415 
416  - Generate more output starting at next_out and update next_out and avail_out
417  accordingly. inflate() provides as much output as possible, until there is
418  no more input data or no more space in the output buffer (see below about
419  the flush parameter).
420 
421  Before the call of inflate(), the application should ensure that at least
422  one of the actions is possible, by providing more input and/or consuming more
423  output, and updating the next_* and avail_* values accordingly. If the
424  caller of inflate() does not provide both available input and available
425  output space, it is possible that there will be no progress made. The
426  application can consume the uncompressed output when it wants, for example
427  when the output buffer is full (avail_out == 0), or after each call of
428  inflate(). If inflate returns Z_OK and with zero avail_out, it must be
429  called again after making room in the output buffer because there might be
430  more output pending.
431 
432  The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
433  Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
434  output as possible to the output buffer. Z_BLOCK requests that inflate()
435  stop if and when it gets to the next deflate block boundary. When decoding
436  the zlib or gzip format, this will cause inflate() to return immediately
437  after the header and before the first block. When doing a raw inflate,
438  inflate() will go ahead and process the first block, and will return when it
439  gets to the end of that block, or when it runs out of data.
440 
441  The Z_BLOCK option assists in appending to or combining deflate streams.
442  To assist in this, on return inflate() always sets strm->data_type to the
443  number of unused bits in the last byte taken from strm->next_in, plus 64 if
444  inflate() is currently decoding the last block in the deflate stream, plus
445  128 if inflate() returned immediately after decoding an end-of-block code or
446  decoding the complete header up to just before the first byte of the deflate
447  stream. The end-of-block will not be indicated until all of the uncompressed
448  data from that block has been written to strm->next_out. The number of
449  unused bits may in general be greater than seven, except when bit 7 of
450  data_type is set, in which case the number of unused bits will be less than
451  eight. data_type is set as noted here every time inflate() returns for all
452  flush options, and so can be used to determine the amount of currently
453  consumed input in bits.
454 
455  The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
456  end of each deflate block header is reached, before any actual data in that
457  block is decoded. This allows the caller to determine the length of the
458  deflate block header for later use in random access within a deflate block.
459  256 is added to the value of strm->data_type when inflate() returns
460  immediately after reaching the end of the deflate block header.
461 
462  inflate() should normally be called until it returns Z_STREAM_END or an
463  error. However if all decompression is to be performed in a single step (a
464  single call of inflate), the parameter flush should be set to Z_FINISH. In
465  this case all pending input is processed and all pending output is flushed;
466  avail_out must be large enough to hold all of the uncompressed data for the
467  operation to complete. (The size of the uncompressed data may have been
468  saved by the compressor for this purpose.) The use of Z_FINISH is not
469  required to perform an inflation in one step. However it may be used to
470  inform inflate that a faster approach can be used for the single inflate()
471  call. Z_FINISH also informs inflate to not maintain a sliding window if the
472  stream completes, which reduces inflate's memory footprint. If the stream
473  does not complete, either because not all of the stream is provided or not
474  enough output space is provided, then a sliding window will be allocated and
475  inflate() can be called again to continue the operation as if Z_NO_FLUSH had
476  been used.
477 
478  In this implementation, inflate() always flushes as much output as
479  possible to the output buffer, and always uses the faster approach on the
480  first call. So the effects of the flush parameter in this implementation are
481  on the return value of inflate() as noted below, when inflate() returns early
482  when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
483  memory for a sliding window when Z_FINISH is used.
484 
485  If a preset dictionary is needed after this call (see inflateSetDictionary
486  below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
487  chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
488  strm->adler to the Adler-32 checksum of all output produced so far (that is,
489  total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
490  below. At the end of the stream, inflate() checks that its computed Adler-32
491  checksum is equal to that saved by the compressor and returns Z_STREAM_END
492  only if the checksum is correct.
493 
494  inflate() can decompress and check either zlib-wrapped or gzip-wrapped
495  deflate data. The header type is detected automatically, if requested when
496  initializing with inflateInit2(). Any information contained in the gzip
497  header is not retained unless inflateGetHeader() is used. When processing
498  gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
499  produced so far. The CRC-32 is checked against the gzip trailer, as is the
500  uncompressed length, modulo 2^32.
501 
502  inflate() returns Z_OK if some progress has been made (more input processed
503  or more output produced), Z_STREAM_END if the end of the compressed data has
504  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
505  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
506  corrupted (input stream not conforming to the zlib format or incorrect check
507  value, in which case strm->msg points to a string with a more specific
508  error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
509  next_in or next_out was Z_NULL, or the state was inadvertently written over
510  by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
511  if no progress was possible or if there was not enough room in the output
512  buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
513  inflate() can be called again with more input and more output space to
514  continue decompressing. If Z_DATA_ERROR is returned, the application may
515  then call inflateSync() to look for a good compression block if a partial
516  recovery of the data is to be attempted.
517 */
518 
519 
520 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
521 /*
522  All dynamically allocated data structures for this stream are freed.
523  This function discards any unprocessed input and does not flush any pending
524  output.
525 
526  inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
527  was inconsistent.
528 */
529 
530 
531  /* Advanced functions */
532 
533 /*
534  The following functions are needed only in some special applications.
535 */
536 
537 /*
538 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
539  int level,
540  int method,
541  int windowBits,
542  int memLevel,
543  int strategy));
544 
545  This is another version of deflateInit with more compression options. The
546  fields next_in, zalloc, zfree and opaque must be initialized before by the
547  caller.
548 
549  The method parameter is the compression method. It must be Z_DEFLATED in
550  this version of the library.
551 
552  The windowBits parameter is the base two logarithm of the window size
553  (the size of the history buffer). It should be in the range 8..15 for this
554  version of the library. Larger values of this parameter result in better
555  compression at the expense of memory usage. The default value is 15 if
556  deflateInit is used instead.
557 
558  For the current implementation of deflate(), a windowBits value of 8 (a
559  window size of 256 bytes) is not supported. As a result, a request for 8
560  will result in 9 (a 512-byte window). In that case, providing 8 to
561  inflateInit2() will result in an error when the zlib header with 9 is
562  checked against the initialization of inflate(). The remedy is to not use 8
563  with deflateInit2() with this initialization, or at least in that case use 9
564  with inflateInit2().
565 
566  windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
567  determines the window size. deflate() will then generate raw deflate data
568  with no zlib header or trailer, and will not compute a check value.
569 
570  windowBits can also be greater than 15 for optional gzip encoding. Add
571  16 to windowBits to write a simple gzip header and trailer around the
572  compressed data instead of a zlib wrapper. The gzip header will have no
573  file name, no extra data, no comment, no modification time (set to zero), no
574  header crc, and the operating system will be set to the appropriate value,
575  if the operating system was determined at compile time. If a gzip stream is
576  being written, strm->adler is a CRC-32 instead of an Adler-32.
577 
578  For raw deflate or gzip encoding, a request for a 256-byte window is
579  rejected as invalid, since only the zlib header provides a means of
580  transmitting the window size to the decompressor.
581 
582  The memLevel parameter specifies how much memory should be allocated
583  for the internal compression state. memLevel=1 uses minimum memory but is
584  slow and reduces compression ratio; memLevel=9 uses maximum memory for
585  optimal speed. The default value is 8. See zconf.h for total memory usage
586  as a function of windowBits and memLevel.
587 
588  The strategy parameter is used to tune the compression algorithm. Use the
589  value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
590  filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
591  string match), or Z_RLE to limit match distances to one (run-length
592  encoding). Filtered data consists mostly of small values with a somewhat
593  random distribution. In this case, the compression algorithm is tuned to
594  compress them better. The effect of Z_FILTERED is to force more Huffman
595  coding and less string matching; it is somewhat intermediate between
596  Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
597  fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
598  strategy parameter only affects the compression ratio but not the
599  correctness of the compressed output even if it is not set appropriately.
600  Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
601  decoder for special applications.
602 
603  deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
604  memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
605  method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
606  incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
607  set to null if there is no error message. deflateInit2 does not perform any
608  compression: this will be done by deflate().
609 */
610 
611 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
612  const Bytef *dictionary,
613  uInt dictLength));
614 /*
615  Initializes the compression dictionary from the given byte sequence
616  without producing any compressed output. When using the zlib format, this
617  function must be called immediately after deflateInit, deflateInit2 or
618  deflateReset, and before any call of deflate. When doing raw deflate, this
619  function must be called either before any call of deflate, or immediately
620  after the completion of a deflate block, i.e. after all input has been
621  consumed and all output has been delivered when using any of the flush
622  options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
623  compressor and decompressor must use exactly the same dictionary (see
624  inflateSetDictionary).
625 
626  The dictionary should consist of strings (byte sequences) that are likely
627  to be encountered later in the data to be compressed, with the most commonly
628  used strings preferably put towards the end of the dictionary. Using a
629  dictionary is most useful when the data to be compressed is short and can be
630  predicted with good accuracy; the data can then be compressed better than
631  with the default empty dictionary.
632 
633  Depending on the size of the compression data structures selected by
634  deflateInit or deflateInit2, a part of the dictionary may in effect be
635  discarded, for example if the dictionary is larger than the window size
636  provided in deflateInit or deflateInit2. Thus the strings most likely to be
637  useful should be put at the end of the dictionary, not at the front. In
638  addition, the current implementation of deflate will use at most the window
639  size minus 262 bytes of the provided dictionary.
640 
641  Upon return of this function, strm->adler is set to the Adler-32 value
642  of the dictionary; the decompressor may later use this value to determine
643  which dictionary has been used by the compressor. (The Adler-32 value
644  applies to the whole dictionary even if only a subset of the dictionary is
645  actually used by the compressor.) If a raw deflate was requested, then the
646  Adler-32 value is not computed and strm->adler is not set.
647 
648  deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
649  parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
650  inconsistent (for example if deflate has already been called for this stream
651  or if not at a block boundary for raw deflate). deflateSetDictionary does
652  not perform any compression: this will be done by deflate().
653 */
654 
655 ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
656  Bytef *dictionary,
657  uInt *dictLength));
658 /*
659  Returns the sliding dictionary being maintained by deflate. dictLength is
660  set to the number of bytes in the dictionary, and that many bytes are copied
661  to dictionary. dictionary must have enough space, where 32768 bytes is
662  always enough. If deflateGetDictionary() is called with dictionary equal to
663  Z_NULL, then only the dictionary length is returned, and nothing is copied.
664  Similary, if dictLength is Z_NULL, then it is not set.
665 
666  deflateGetDictionary() may return a length less than the window size, even
667  when more than the window size in input has been provided. It may return up
668  to 258 bytes less in that case, due to how zlib's implementation of deflate
669  manages the sliding window and lookahead for matches, where matches can be
670  up to 258 bytes long. If the application needs the last window-size bytes of
671  input, then that would need to be saved by the application outside of zlib.
672 
673  deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
674  stream state is inconsistent.
675 */
676 
677 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
678  z_streamp source));
679 /*
680  Sets the destination stream as a complete copy of the source stream.
681 
682  This function can be useful when several compression strategies will be
683  tried, for example when there are several ways of pre-processing the input
684  data with a filter. The streams that will be discarded should then be freed
685  by calling deflateEnd. Note that deflateCopy duplicates the internal
686  compression state which can be quite large, so this strategy is slow and can
687  consume lots of memory.
688 
689  deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
690  enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
691  (such as zalloc being Z_NULL). msg is left unchanged in both source and
692  destination.
693 */
694 
695 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
696 /*
697  This function is equivalent to deflateEnd followed by deflateInit, but
698  does not free and reallocate the internal compression state. The stream
699  will leave the compression level and any other attributes that may have been
700  set unchanged.
701 
702  deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
703  stream state was inconsistent (such as zalloc or state being Z_NULL).
704 */
705 
706 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
707  int level,
708  int strategy));
709 /*
710  Dynamically update the compression level and compression strategy. The
711  interpretation of level and strategy is as in deflateInit2(). This can be
712  used to switch between compression and straight copy of the input data, or
713  to switch to a different kind of input data requiring a different strategy.
714  If the compression approach (which is a function of the level) or the
715  strategy is changed, and if any input has been consumed in a previous
716  deflate() call, then the input available so far is compressed with the old
717  level and strategy using deflate(strm, Z_BLOCK). There are three approaches
718  for the compression levels 0, 1..3, and 4..9 respectively. The new level
719  and strategy will take effect at the next call of deflate().
720 
721  If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
722  not have enough output space to complete, then the parameter change will not
723  take effect. In this case, deflateParams() can be called again with the
724  same parameters and more output space to try again.
725 
726  In order to assure a change in the parameters on the first try, the
727  deflate stream should be flushed using deflate() with Z_BLOCK or other flush
728  request until strm.avail_out is not zero, before calling deflateParams().
729  Then no more input data should be provided before the deflateParams() call.
730  If this is done, the old level and strategy will be applied to the data
731  compressed before deflateParams(), and the new level and strategy will be
732  applied to the the data compressed after deflateParams().
733 
734  deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
735  state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
736  there was not enough output space to complete the compression of the
737  available input data before a change in the strategy or approach. Note that
738  in the case of a Z_BUF_ERROR, the parameters are not changed. A return
739  value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
740  retried with more output space.
741 */
742 
743 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
744  int good_length,
745  int max_lazy,
746  int nice_length,
747  int max_chain));
748 /*
749  Fine tune deflate's internal compression parameters. This should only be
750  used by someone who understands the algorithm used by zlib's deflate for
751  searching for the best matching string, and even then only by the most
752  fanatic optimizer trying to squeeze out the last compressed bit for their
753  specific input data. Read the deflate.c source code for the meaning of the
754  max_lazy, good_length, nice_length, and max_chain parameters.
755 
756  deflateTune() can be called after deflateInit() or deflateInit2(), and
757  returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
758  */
759 
760 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
761  uLong sourceLen));
762 /*
763  deflateBound() returns an upper bound on the compressed size after
764  deflation of sourceLen bytes. It must be called after deflateInit() or
765  deflateInit2(), and after deflateSetHeader(), if used. This would be used
766  to allocate an output buffer for deflation in a single pass, and so would be
767  called before deflate(). If that first deflate() call is provided the
768  sourceLen input bytes, an output buffer allocated to the size returned by
769  deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
770  to return Z_STREAM_END. Note that it is possible for the compressed size to
771  be larger than the value returned by deflateBound() if flush options other
772  than Z_FINISH or Z_NO_FLUSH are used.
773 */
774 
775 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
776  unsigned *pending,
777  int *bits));
778 /*
779  deflatePending() returns the number of bytes and bits of output that have
780  been generated, but not yet provided in the available output. The bytes not
781  provided would be due to the available output space having being consumed.
782  The number of bits of output not provided are between 0 and 7, where they
783  await more bits to join them in order to fill out a full byte. If pending
784  or bits are Z_NULL, then those values are not set.
785 
786  deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
787  stream state was inconsistent.
788  */
789 
790 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
791  int bits,
792  int value));
793 /*
794  deflatePrime() inserts bits in the deflate output stream. The intent
795  is that this function is used to start off the deflate output with the bits
796  leftover from a previous deflate stream when appending to it. As such, this
797  function can only be used for raw deflate, and must be used before the first
798  deflate() call after a deflateInit2() or deflateReset(). bits must be less
799  than or equal to 16, and that many of the least significant bits of value
800  will be inserted in the output.
801 
802  deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
803  room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
804  source stream state was inconsistent.
805 */
806 
807 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
808  gz_headerp head));
809 /*
810  deflateSetHeader() provides gzip header information for when a gzip
811  stream is requested by deflateInit2(). deflateSetHeader() may be called
812  after deflateInit2() or deflateReset() and before the first call of
813  deflate(). The text, time, os, extra field, name, and comment information
814  in the provided gz_header structure are written to the gzip header (xflag is
815  ignored -- the extra flags are set according to the compression level). The
816  caller must assure that, if not Z_NULL, name and comment are terminated with
817  a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
818  available there. If hcrc is true, a gzip header crc is included. Note that
819  the current versions of the command-line version of gzip (up through version
820  1.3.x) do not support header crc's, and will report that it is a "multi-part
821  gzip file" and give up.
822 
823  If deflateSetHeader is not used, the default gzip header has text false,
824  the time set to zero, and os set to 255, with no extra, name, or comment
825  fields. The gzip header is returned to the default state by deflateReset().
826 
827  deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
828  stream state was inconsistent.
829 */
830 
831 /*
832 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
833  int windowBits));
834 
835  This is another version of inflateInit with an extra parameter. The
836  fields next_in, avail_in, zalloc, zfree and opaque must be initialized
837  before by the caller.
838 
839  The windowBits parameter is the base two logarithm of the maximum window
840  size (the size of the history buffer). It should be in the range 8..15 for
841  this version of the library. The default value is 15 if inflateInit is used
842  instead. windowBits must be greater than or equal to the windowBits value
843  provided to deflateInit2() while compressing, or it must be equal to 15 if
844  deflateInit2() was not used. If a compressed stream with a larger window
845  size is given as input, inflate() will return with the error code
846  Z_DATA_ERROR instead of trying to allocate a larger window.
847 
848  windowBits can also be zero to request that inflate use the window size in
849  the zlib header of the compressed stream.
850 
851  windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
852  determines the window size. inflate() will then process raw deflate data,
853  not looking for a zlib or gzip header, not generating a check value, and not
854  looking for any check values for comparison at the end of the stream. This
855  is for use with other formats that use the deflate compressed data format
856  such as zip. Those formats provide their own check values. If a custom
857  format is developed using the raw deflate format for compressed data, it is
858  recommended that a check value such as an Adler-32 or a CRC-32 be applied to
859  the uncompressed data as is done in the zlib, gzip, and zip formats. For
860  most applications, the zlib format should be used as is. Note that comments
861  above on the use in deflateInit2() applies to the magnitude of windowBits.
862 
863  windowBits can also be greater than 15 for optional gzip decoding. Add
864  32 to windowBits to enable zlib and gzip decoding with automatic header
865  detection, or add 16 to decode only the gzip format (the zlib format will
866  return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
867  CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see
868  below), inflate() will not automatically decode concatenated gzip streams.
869  inflate() will return Z_STREAM_END at the end of the gzip stream. The state
870  would need to be reset to continue decoding a subsequent gzip stream.
871 
872  inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
873  memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
874  version assumed by the caller, or Z_STREAM_ERROR if the parameters are
875  invalid, such as a null pointer to the structure. msg is set to null if
876  there is no error message. inflateInit2 does not perform any decompression
877  apart from possibly reading the zlib header if present: actual decompression
878  will be done by inflate(). (So next_in and avail_in may be modified, but
879  next_out and avail_out are unused and unchanged.) The current implementation
880  of inflateInit2() does not process any header information -- that is
881  deferred until inflate() is called.
882 */
883 
884 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
885  const Bytef *dictionary,
886  uInt dictLength));
887 /*
888  Initializes the decompression dictionary from the given uncompressed byte
889  sequence. This function must be called immediately after a call of inflate,
890  if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
891  can be determined from the Adler-32 value returned by that call of inflate.
892  The compressor and decompressor must use exactly the same dictionary (see
893  deflateSetDictionary). For raw inflate, this function can be called at any
894  time to set the dictionary. If the provided dictionary is smaller than the
895  window and there is already data in the window, then the provided dictionary
896  will amend what's there. The application must insure that the dictionary
897  that was used for compression is provided.
898 
899  inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
900  parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
901  inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
902  expected one (incorrect Adler-32 value). inflateSetDictionary does not
903  perform any decompression: this will be done by subsequent calls of
904  inflate().
905 */
906 
907 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
908  Bytef *dictionary,
909  uInt *dictLength));
910 /*
911  Returns the sliding dictionary being maintained by inflate. dictLength is
912  set to the number of bytes in the dictionary, and that many bytes are copied
913  to dictionary. dictionary must have enough space, where 32768 bytes is
914  always enough. If inflateGetDictionary() is called with dictionary equal to
915  Z_NULL, then only the dictionary length is returned, and nothing is copied.
916  Similary, if dictLength is Z_NULL, then it is not set.
917 
918  inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
919  stream state is inconsistent.
920 */
921 
922 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
923 /*
924  Skips invalid compressed data until a possible full flush point (see above
925  for the description of deflate with Z_FULL_FLUSH) can be found, or until all
926  available input is skipped. No output is provided.
927 
928  inflateSync searches for a 00 00 FF FF pattern in the compressed data.
929  All full flush points have this pattern, but not all occurrences of this
930  pattern are full flush points.
931 
932  inflateSync returns Z_OK if a possible full flush point has been found,
933  Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
934  has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
935  In the success case, the application may save the current current value of
936  total_in which indicates where valid compressed data was found. In the
937  error case, the application may repeatedly call inflateSync, providing more
938  input each time, until success or end of the input data.
939 */
940 
941 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
942  z_streamp source));
943 /*
944  Sets the destination stream as a complete copy of the source stream.
945 
946  This function can be useful when randomly accessing a large stream. The
947  first pass through the stream can periodically record the inflate state,
948  allowing restarting inflate at those points when randomly accessing the
949  stream.
950 
951  inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
952  enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
953  (such as zalloc being Z_NULL). msg is left unchanged in both source and
954  destination.
955 */
956 
957 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
958 /*
959  This function is equivalent to inflateEnd followed by inflateInit,
960  but does not free and reallocate the internal decompression state. The
961  stream will keep attributes that may have been set by inflateInit2.
962 
963  inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
964  stream state was inconsistent (such as zalloc or state being Z_NULL).
965 */
966 
967 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
968  int windowBits));
969 /*
970  This function is the same as inflateReset, but it also permits changing
971  the wrap and window size requests. The windowBits parameter is interpreted
972  the same as it is for inflateInit2. If the window size is changed, then the
973  memory allocated for the window is freed, and the window will be reallocated
974  by inflate() if needed.
975 
976  inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
977  stream state was inconsistent (such as zalloc or state being Z_NULL), or if
978  the windowBits parameter is invalid.
979 */
980 
981 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
982  int bits,
983  int value));
984 /*
985  This function inserts bits in the inflate input stream. The intent is
986  that this function is used to start inflating at a bit position in the
987  middle of a byte. The provided bits will be used before any bytes are used
988  from next_in. This function should only be used with raw inflate, and
989  should be used before the first inflate() call after inflateInit2() or
990  inflateReset(). bits must be less than or equal to 16, and that many of the
991  least significant bits of value will be inserted in the input.
992 
993  If bits is negative, then the input stream bit buffer is emptied. Then
994  inflatePrime() can be called again to put bits in the buffer. This is used
995  to clear out bits leftover after feeding inflate a block description prior
996  to feeding inflate codes.
997 
998  inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
999  stream state was inconsistent.
1000 */
1001 
1002 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
1003 /*
1004  This function returns two values, one in the lower 16 bits of the return
1005  value, and the other in the remaining upper bits, obtained by shifting the
1006  return value down 16 bits. If the upper value is -1 and the lower value is
1007  zero, then inflate() is currently decoding information outside of a block.
1008  If the upper value is -1 and the lower value is non-zero, then inflate is in
1009  the middle of a stored block, with the lower value equaling the number of
1010  bytes from the input remaining to copy. If the upper value is not -1, then
1011  it is the number of bits back from the current bit position in the input of
1012  the code (literal or length/distance pair) currently being processed. In
1013  that case the lower value is the number of bytes already emitted for that
1014  code.
1015 
1016  A code is being processed if inflate is waiting for more input to complete
1017  decoding of the code, or if it has completed decoding but is waiting for
1018  more output space to write the literal or match data.
1019 
1020  inflateMark() is used to mark locations in the input data for random
1021  access, which may be at bit positions, and to note those cases where the
1022  output of a code may span boundaries of random access blocks. The current
1023  location in the input stream can be determined from avail_in and data_type
1024  as noted in the description for the Z_BLOCK flush parameter for inflate.
1025 
1026  inflateMark returns the value noted above, or -65536 if the provided
1027  source stream state was inconsistent.
1028 */
1029 
1030 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1031  gz_headerp head));
1032 /*
1033  inflateGetHeader() requests that gzip header information be stored in the
1034  provided gz_header structure. inflateGetHeader() may be called after
1035  inflateInit2() or inflateReset(), and before the first call of inflate().
1036  As inflate() processes the gzip stream, head->done is zero until the header
1037  is completed, at which time head->done is set to one. If a zlib stream is
1038  being decoded, then head->done is set to -1 to indicate that there will be
1039  no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
1040  used to force inflate() to return immediately after header processing is
1041  complete and before any actual data is decompressed.
1042 
1043  The text, time, xflags, and os fields are filled in with the gzip header
1044  contents. hcrc is set to true if there is a header CRC. (The header CRC
1045  was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1046  contains the maximum number of bytes to write to extra. Once done is true,
1047  extra_len contains the actual extra field length, and extra contains the
1048  extra field, or that field truncated if extra_max is less than extra_len.
1049  If name is not Z_NULL, then up to name_max characters are written there,
1050  terminated with a zero unless the length is greater than name_max. If
1051  comment is not Z_NULL, then up to comm_max characters are written there,
1052  terminated with a zero unless the length is greater than comm_max. When any
1053  of extra, name, or comment are not Z_NULL and the respective field is not
1054  present in the header, then that field is set to Z_NULL to signal its
1055  absence. This allows the use of deflateSetHeader() with the returned
1056  structure to duplicate the header. However if those fields are set to
1057  allocated memory, then the application will need to save those pointers
1058  elsewhere so that they can be eventually freed.
1059 
1060  If inflateGetHeader is not used, then the header information is simply
1061  discarded. The header is always checked for validity, including the header
1062  CRC if present. inflateReset() will reset the process to discard the header
1063  information. The application would need to call inflateGetHeader() again to
1064  retrieve the header from the next gzip stream.
1065 
1066  inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1067  stream state was inconsistent.
1068 */
1069 
1070 /*
1071 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1072  unsigned char FAR *window));
1073 
1074  Initialize the internal stream state for decompression using inflateBack()
1075  calls. The fields zalloc, zfree and opaque in strm must be initialized
1076  before the call. If zalloc and zfree are Z_NULL, then the default library-
1077  derived memory allocation routines are used. windowBits is the base two
1078  logarithm of the window size, in the range 8..15. window is a caller
1079  supplied buffer of that size. Except for special applications where it is
1080  assured that deflate was used with small window sizes, windowBits must be 15
1081  and a 32K byte window must be supplied to be able to decompress general
1082  deflate streams.
1083 
1084  See inflateBack() for the usage of these routines.
1085 
1086  inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1087  the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1088  allocated, or Z_VERSION_ERROR if the version of the library does not match
1089  the version of the header file.
1090 */
1091 
1092 typedef unsigned (*in_func) OF((void FAR *,
1093  z_const unsigned char FAR * FAR *));
1094 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1095 
1096 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1097  in_func in, void FAR *in_desc,
1098  out_func out, void FAR *out_desc));
1099 /*
1100  inflateBack() does a raw inflate with a single call using a call-back
1101  interface for input and output. This is potentially more efficient than
1102  inflate() for file i/o applications, in that it avoids copying between the
1103  output and the sliding window by simply making the window itself the output
1104  buffer. inflate() can be faster on modern CPUs when used with large
1105  buffers. inflateBack() trusts the application to not change the output
1106  buffer passed by the output function, at least until inflateBack() returns.
1107 
1108  inflateBackInit() must be called first to allocate the internal state
1109  and to initialize the state with the user-provided window buffer.
1110  inflateBack() may then be used multiple times to inflate a complete, raw
1111  deflate stream with each call. inflateBackEnd() is then called to free the
1112  allocated state.
1113 
1114  A raw deflate stream is one with no zlib or gzip header or trailer.
1115  This routine would normally be used in a utility that reads zip or gzip
1116  files and writes out uncompressed files. The utility would decode the
1117  header and process the trailer on its own, hence this routine expects only
1118  the raw deflate stream to decompress. This is different from the default
1119  behavior of inflate(), which expects a zlib header and trailer around the
1120  deflate stream.
1121 
1122  inflateBack() uses two subroutines supplied by the caller that are then
1123  called by inflateBack() for input and output. inflateBack() calls those
1124  routines until it reads a complete deflate stream and writes out all of the
1125  uncompressed data, or until it encounters an error. The function's
1126  parameters and return types are defined above in the in_func and out_func
1127  typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1128  number of bytes of provided input, and a pointer to that input in buf. If
1129  there is no input available, in() must return zero -- buf is ignored in that
1130  case -- and inflateBack() will return a buffer error. inflateBack() will
1131  call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1132  out() should return zero on success, or non-zero on failure. If out()
1133  returns non-zero, inflateBack() will return with an error. Neither in() nor
1134  out() are permitted to change the contents of the window provided to
1135  inflateBackInit(), which is also the buffer that out() uses to write from.
1136  The length written by out() will be at most the window size. Any non-zero
1137  amount of input may be provided by in().
1138 
1139  For convenience, inflateBack() can be provided input on the first call by
1140  setting strm->next_in and strm->avail_in. If that input is exhausted, then
1141  in() will be called. Therefore strm->next_in must be initialized before
1142  calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1143  immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1144  must also be initialized, and then if strm->avail_in is not zero, input will
1145  initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1146 
1147  The in_desc and out_desc parameters of inflateBack() is passed as the
1148  first parameter of in() and out() respectively when they are called. These
1149  descriptors can be optionally used to pass any information that the caller-
1150  supplied in() and out() functions need to do their job.
1151 
1152  On return, inflateBack() will set strm->next_in and strm->avail_in to
1153  pass back any unused input that was provided by the last in() call. The
1154  return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1155  if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1156  in the deflate stream (in which case strm->msg is set to indicate the nature
1157  of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1158  In the case of Z_BUF_ERROR, an input or output error can be distinguished
1159  using strm->next_in which will be Z_NULL only if in() returned an error. If
1160  strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1161  non-zero. (in() will always be called before out(), so strm->next_in is
1162  assured to be defined if out() returns non-zero.) Note that inflateBack()
1163  cannot return Z_OK.
1164 */
1165 
1166 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1167 /*
1168  All memory allocated by inflateBackInit() is freed.
1169 
1170  inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1171  state was inconsistent.
1172 */
1173 
1174 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1175 /* Return flags indicating compile-time options.
1176 
1177  Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1178  1.0: size of uInt
1179  3.2: size of uLong
1180  5.4: size of voidpf (pointer)
1181  7.6: size of z_off_t
1182 
1183  Compiler, assembler, and debug options:
1184  8: ZLIB_DEBUG
1185  9: ASMV or ASMINF -- use ASM code
1186  10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1187  11: 0 (reserved)
1188 
1189  One-time table building (smaller code, but not thread-safe if true):
1190  12: BUILDFIXED -- build static block decoding tables when needed
1191  13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1192  14,15: 0 (reserved)
1193 
1194  Library content (indicates missing functionality):
1195  16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1196  deflate code when not needed)
1197  17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1198  and decode gzip streams (to avoid linking crc code)
1199  18-19: 0 (reserved)
1200 
1201  Operation variations (changes in library functionality):
1202  20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1203  21: FASTEST -- deflate algorithm with only one, lowest compression level
1204  22,23: 0 (reserved)
1205 
1206  The sprintf variant used by gzprintf (zero is best):
1207  24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1208  25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1209  26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1210 
1211  Remainder:
1212  27-31: 0 (reserved)
1213  */
1214 
1215 #ifndef Z_SOLO
1216 
1217  /* utility functions */
1218 
1219 /*
1220  The following utility functions are implemented on top of the basic
1221  stream-oriented functions. To simplify the interface, some default options
1222  are assumed (compression level and memory usage, standard memory allocation
1223  functions). The source code of these utility functions can be modified if
1224  you need special options.
1225 */
1226 
1227 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1228  const Bytef *source, uLong sourceLen));
1229 /*
1230  Compresses the source buffer into the destination buffer. sourceLen is
1231  the byte length of the source buffer. Upon entry, destLen is the total size
1232  of the destination buffer, which must be at least the value returned by
1233  compressBound(sourceLen). Upon exit, destLen is the actual size of the
1234  compressed data. compress() is equivalent to compress2() with a level
1235  parameter of Z_DEFAULT_COMPRESSION.
1236 
1237  compress returns Z_OK if success, Z_MEM_ERROR if there was not
1238  enough memory, Z_BUF_ERROR if there was not enough room in the output
1239  buffer.
1240 */
1241 
1242 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1243  const Bytef *source, uLong sourceLen,
1244  int level));
1245 /*
1246  Compresses the source buffer into the destination buffer. The level
1247  parameter has the same meaning as in deflateInit. sourceLen is the byte
1248  length of the source buffer. Upon entry, destLen is the total size of the
1249  destination buffer, which must be at least the value returned by
1250  compressBound(sourceLen). Upon exit, destLen is the actual size of the
1251  compressed data.
1252 
1253  compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1254  memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1255  Z_STREAM_ERROR if the level parameter is invalid.
1256 */
1257 
1258 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1259 /*
1260  compressBound() returns an upper bound on the compressed size after
1261  compress() or compress2() on sourceLen bytes. It would be used before a
1262  compress() or compress2() call to allocate the destination buffer.
1263 */
1264 
1265 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1266  const Bytef *source, uLong sourceLen));
1267 /*
1268  Decompresses the source buffer into the destination buffer. sourceLen is
1269  the byte length of the source buffer. Upon entry, destLen is the total size
1270  of the destination buffer, which must be large enough to hold the entire
1271  uncompressed data. (The size of the uncompressed data must have been saved
1272  previously by the compressor and transmitted to the decompressor by some
1273  mechanism outside the scope of this compression library.) Upon exit, destLen
1274  is the actual size of the uncompressed data.
1275 
1276  uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1277  enough memory, Z_BUF_ERROR if there was not enough room in the output
1278  buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1279  the case where there is not enough room, uncompress() will fill the output
1280  buffer with the uncompressed data up to that point.
1281 */
1282 
1283 ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest, uLongf *destLen,
1284  const Bytef *source, uLong *sourceLen));
1285 /*
1286  Same as uncompress, except that sourceLen is a pointer, where the
1287  length of the source is *sourceLen. On return, *sourceLen is the number of
1288  source bytes consumed.
1289 */
1290 
1291  /* gzip file access functions */
1292 
1293 /*
1294  This library supports reading and writing files in gzip (.gz) format with
1295  an interface similar to that of stdio, using the functions that start with
1296  "gz". The gzip format is different from the zlib format. gzip is a gzip
1297  wrapper, documented in RFC 1952, wrapped around a deflate stream.
1298 */
1299 
1300 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1301 
1302 /*
1303 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1304 
1305  Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1306  in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1307  a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1308  compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1309  for fixed code compression as in "wb9F". (See the description of
1310  deflateInit2 for more information about the strategy parameter.) 'T' will
1311  request transparent writing or appending with no compression and not using
1312  the gzip format.
1313 
1314  "a" can be used instead of "w" to request that the gzip stream that will
1315  be written be appended to the file. "+" will result in an error, since
1316  reading and writing to the same gzip file is not supported. The addition of
1317  "x" when writing will create the file exclusively, which fails if the file
1318  already exists. On systems that support it, the addition of "e" when
1319  reading or writing will set the flag to close the file on an execve() call.
1320 
1321  These functions, as well as gzip, will read and decode a sequence of gzip
1322  streams in a file. The append function of gzopen() can be used to create
1323  such a file. (Also see gzflush() for another way to do this.) When
1324  appending, gzopen does not test whether the file begins with a gzip stream,
1325  nor does it look for the end of the gzip streams to begin appending. gzopen
1326  will simply append a gzip stream to the existing file.
1327 
1328  gzopen can be used to read a file which is not in gzip format; in this
1329  case gzread will directly read from the file without decompression. When
1330  reading, this will be detected automatically by looking for the magic two-
1331  byte gzip header.
1332 
1333  gzopen returns NULL if the file could not be opened, if there was
1334  insufficient memory to allocate the gzFile state, or if an invalid mode was
1335  specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1336  errno can be checked to determine if the reason gzopen failed was that the
1337  file could not be opened.
1338 */
1339 
1340 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1341 /*
1342  gzdopen associates a gzFile with the file descriptor fd. File descriptors
1343  are obtained from calls like open, dup, creat, pipe or fileno (if the file
1344  has been previously opened with fopen). The mode parameter is as in gzopen.
1345 
1346  The next call of gzclose on the returned gzFile will also close the file
1347  descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1348  fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1349  mode);. The duplicated descriptor should be saved to avoid a leak, since
1350  gzdopen does not close fd if it fails. If you are using fileno() to get the
1351  file descriptor from a FILE *, then you will have to use dup() to avoid
1352  double-close()ing the file descriptor. Both gzclose() and fclose() will
1353  close the associated file descriptor, so they need to have different file
1354  descriptors.
1355 
1356  gzdopen returns NULL if there was insufficient memory to allocate the
1357  gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1358  provided, or '+' was provided), or if fd is -1. The file descriptor is not
1359  used until the next gz* read, write, seek, or close operation, so gzdopen
1360  will not detect if fd is invalid (unless fd is -1).
1361 */
1362 
1363 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1364 /*
1365  Set the internal buffer size used by this library's functions. The
1366  default buffer size is 8192 bytes. This function must be called after
1367  gzopen() or gzdopen(), and before any other calls that read or write the
1368  file. The buffer memory allocation is always deferred to the first read or
1369  write. Three times that size in buffer space is allocated. A larger buffer
1370  size of, for example, 64K or 128K bytes will noticeably increase the speed
1371  of decompression (reading).
1372 
1373  The new buffer size also affects the maximum length for gzprintf().
1374 
1375  gzbuffer() returns 0 on success, or -1 on failure, such as being called
1376  too late.
1377 */
1378 
1379 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1380 /*
1381  Dynamically update the compression level or strategy. See the description
1382  of deflateInit2 for the meaning of these parameters. Previously provided
1383  data is flushed before the parameter change.
1384 
1385  gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1386  opened for writing, Z_ERRNO if there is an error writing the flushed data,
1387  or Z_MEM_ERROR if there is a memory allocation error.
1388 */
1389 
1390 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1391 /*
1392  Reads the given number of uncompressed bytes from the compressed file. If
1393  the input file is not in gzip format, gzread copies the given number of
1394  bytes into the buffer directly from the file.
1395 
1396  After reaching the end of a gzip stream in the input, gzread will continue
1397  to read, looking for another gzip stream. Any number of gzip streams may be
1398  concatenated in the input file, and will all be decompressed by gzread().
1399  If something other than a gzip stream is encountered after a gzip stream,
1400  that remaining trailing garbage is ignored (and no error is returned).
1401 
1402  gzread can be used to read a gzip file that is being concurrently written.
1403  Upon reaching the end of the input, gzread will return with the available
1404  data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1405  gzclearerr can be used to clear the end of file indicator in order to permit
1406  gzread to be tried again. Z_OK indicates that a gzip stream was completed
1407  on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1408  middle of a gzip stream. Note that gzread does not return -1 in the event
1409  of an incomplete gzip stream. This error is deferred until gzclose(), which
1410  will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1411  stream. Alternatively, gzerror can be used before gzclose to detect this
1412  case.
1413 
1414  gzread returns the number of uncompressed bytes actually read, less than
1415  len for end of file, or -1 for error. If len is too large to fit in an int,
1416  then nothing is read, -1 is returned, and the error state is set to
1417  Z_STREAM_ERROR.
1418 */
1419 
1420 ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
1421  gzFile file));
1422 /*
1423  Read up to nitems items of size size from file to buf, otherwise operating
1424  as gzread() does. This duplicates the interface of stdio's fread(), with
1425  size_t request and return types. If the library defines size_t, then
1426  z_size_t is identical to size_t. If not, then z_size_t is an unsigned
1427  integer type that can contain a pointer.
1428 
1429  gzfread() returns the number of full items read of size size, or zero if
1430  the end of the file was reached and a full item could not be read, or if
1431  there was an error. gzerror() must be consulted if zero is returned in
1432  order to determine if there was an error. If the multiplication of size and
1433  nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1434  is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1435 
1436  In the event that the end of file is reached and only a partial item is
1437  available at the end, i.e. the remaining uncompressed data length is not a
1438  multiple of size, then the final partial item is nevetheless read into buf
1439  and the end-of-file flag is set. The length of the partial item read is not
1440  provided, but could be inferred from the result of gztell(). This behavior
1441  is the same as the behavior of fread() implementations in common libraries,
1442  but it prevents the direct use of gzfread() to read a concurrently written
1443  file, reseting and retrying on end-of-file, when size is not 1.
1444 */
1445 
1446 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1447  voidpc buf, unsigned len));
1448 /*
1449  Writes the given number of uncompressed bytes into the compressed file.
1450  gzwrite returns the number of uncompressed bytes written or 0 in case of
1451  error.
1452 */
1453 
1454 ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
1455  z_size_t nitems, gzFile file));
1456 /*
1457  gzfwrite() writes nitems items of size size from buf to file, duplicating
1458  the interface of stdio's fwrite(), with size_t request and return types. If
1459  the library defines size_t, then z_size_t is identical to size_t. If not,
1460  then z_size_t is an unsigned integer type that can contain a pointer.
1461 
1462  gzfwrite() returns the number of full items written of size size, or zero
1463  if there was an error. If the multiplication of size and nitems overflows,
1464  i.e. the product does not fit in a z_size_t, then nothing is written, zero
1465  is returned, and the error state is set to Z_STREAM_ERROR.
1466 */
1467 
1468 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1469 /*
1470  Converts, formats, and writes the arguments to the compressed file under
1471  control of the format string, as in fprintf. gzprintf returns the number of
1472  uncompressed bytes actually written, or a negative zlib error code in case
1473  of error. The number of uncompressed bytes written is limited to 8191, or
1474  one less than the buffer size given to gzbuffer(). The caller should assure
1475  that this limit is not exceeded. If it is exceeded, then gzprintf() will
1476  return an error (0) with nothing written. In this case, there may also be a
1477  buffer overflow with unpredictable consequences, which is possible only if
1478  zlib was compiled with the insecure functions sprintf() or vsprintf()
1479  because the secure snprintf() or vsnprintf() functions were not available.
1480  This can be determined using zlibCompileFlags().
1481 */
1482 
1483 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1484 /*
1485  Writes the given null-terminated string to the compressed file, excluding
1486  the terminating null character.
1487 
1488  gzputs returns the number of characters written, or -1 in case of error.
1489 */
1490 
1491 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1492 /*
1493  Reads bytes from the compressed file until len-1 characters are read, or a
1494  newline character is read and transferred to buf, or an end-of-file
1495  condition is encountered. If any characters are read or if len == 1, the
1496  string is terminated with a null character. If no characters are read due
1497  to an end-of-file or len < 1, then the buffer is left untouched.
1498 
1499  gzgets returns buf which is a null-terminated string, or it returns NULL
1500  for end-of-file or in case of error. If there was an error, the contents at
1501  buf are indeterminate.
1502 */
1503 
1504 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1505 /*
1506  Writes c, converted to an unsigned char, into the compressed file. gzputc
1507  returns the value that was written, or -1 in case of error.
1508 */
1509 
1510 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1511 /*
1512  Reads one byte from the compressed file. gzgetc returns this byte or -1
1513  in case of end of file or error. This is implemented as a macro for speed.
1514  As such, it does not do all of the checking the other functions do. I.e.
1515  it does not check to see if file is NULL, nor whether the structure file
1516  points to has been clobbered or not.
1517 */
1518 
1519 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1520 /*
1521  Push one character back onto the stream to be read as the first character
1522  on the next read. At least one character of push-back is allowed.
1523  gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1524  fail if c is -1, and may fail if a character has been pushed but not read
1525  yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1526  output buffer size of pushed characters is allowed. (See gzbuffer above.)
1527  The pushed character will be discarded if the stream is repositioned with
1528  gzseek() or gzrewind().
1529 */
1530 
1531 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1532 /*
1533  Flushes all pending output into the compressed file. The parameter flush
1534  is as in the deflate() function. The return value is the zlib error number
1535  (see function gzerror below). gzflush is only permitted when writing.
1536 
1537  If the flush parameter is Z_FINISH, the remaining data is written and the
1538  gzip stream is completed in the output. If gzwrite() is called again, a new
1539  gzip stream will be started in the output. gzread() is able to read such
1540  concatenated gzip streams.
1541 
1542  gzflush should be called only when strictly necessary because it will
1543  degrade compression if called too often.
1544 */
1545 
1546 /*
1547 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1548  z_off_t offset, int whence));
1549 
1550  Sets the starting position for the next gzread or gzwrite on the given
1551  compressed file. The offset represents a number of bytes in the
1552  uncompressed data stream. The whence parameter is defined as in lseek(2);
1553  the value SEEK_END is not supported.
1554 
1555  If the file is opened for reading, this function is emulated but can be
1556  extremely slow. If the file is opened for writing, only forward seeks are
1557  supported; gzseek then compresses a sequence of zeroes up to the new
1558  starting position.
1559 
1560  gzseek returns the resulting offset location as measured in bytes from
1561  the beginning of the uncompressed stream, or -1 in case of error, in
1562  particular if the file is opened for writing and the new starting position
1563  would be before the current position.
1564 */
1565 
1566 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1567 /*
1568  Rewinds the given file. This function is supported only for reading.
1569 
1570  gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1571 */
1572 
1573 /*
1574 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1575 
1576  Returns the starting position for the next gzread or gzwrite on the given
1577  compressed file. This position represents a number of bytes in the
1578  uncompressed data stream, and is zero when starting, even if appending or
1579  reading a gzip stream from the middle of a file using gzdopen().
1580 
1581  gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1582 */
1583 
1584 /*
1585 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1586 
1587  Returns the current offset in the file being read or written. This offset
1588  includes the count of bytes that precede the gzip stream, for example when
1589  appending or when using gzdopen() for reading. When reading, the offset
1590  does not include as yet unused buffered input. This information can be used
1591  for a progress indicator. On error, gzoffset() returns -1.
1592 */
1593 
1594 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1595 /*
1596  Returns true (1) if the end-of-file indicator has been set while reading,
1597  false (0) otherwise. Note that the end-of-file indicator is set only if the
1598  read tried to go past the end of the input, but came up short. Therefore,
1599  just like feof(), gzeof() may return false even if there is no more data to
1600  read, in the event that the last read request was for the exact number of
1601  bytes remaining in the input file. This will happen if the input file size
1602  is an exact multiple of the buffer size.
1603 
1604  If gzeof() returns true, then the read functions will return no more data,
1605  unless the end-of-file indicator is reset by gzclearerr() and the input file
1606  has grown since the previous end of file was detected.
1607 */
1608 
1609 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1610 /*
1611  Returns true (1) if file is being copied directly while reading, or false
1612  (0) if file is a gzip stream being decompressed.
1613 
1614  If the input file is empty, gzdirect() will return true, since the input
1615  does not contain a gzip stream.
1616 
1617  If gzdirect() is used immediately after gzopen() or gzdopen() it will
1618  cause buffers to be allocated to allow reading the file to determine if it
1619  is a gzip file. Therefore if gzbuffer() is used, it should be called before
1620  gzdirect().
1621 
1622  When writing, gzdirect() returns true (1) if transparent writing was
1623  requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1624  gzdirect() is not needed when writing. Transparent writing must be
1625  explicitly requested, so the application already knows the answer. When
1626  linking statically, using gzdirect() will include all of the zlib code for
1627  gzip file reading and decompression, which may not be desired.)
1628 */
1629 
1630 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1631 /*
1632  Flushes all pending output if necessary, closes the compressed file and
1633  deallocates the (de)compression state. Note that once file is closed, you
1634  cannot call gzerror with file, since its structures have been deallocated.
1635  gzclose must not be called more than once on the same file, just as free
1636  must not be called more than once on the same allocation.
1637 
1638  gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1639  file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1640  last read ended in the middle of a gzip stream, or Z_OK on success.
1641 */
1642 
1643 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1644 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1645 /*
1646  Same as gzclose(), but gzclose_r() is only for use when reading, and
1647  gzclose_w() is only for use when writing or appending. The advantage to
1648  using these instead of gzclose() is that they avoid linking in zlib
1649  compression or decompression code that is not used when only reading or only
1650  writing respectively. If gzclose() is used, then both compression and
1651  decompression code will be included the application when linking to a static
1652  zlib library.
1653 */
1654 
1655 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1656 /*
1657  Returns the error message for the last error which occurred on the given
1658  compressed file. errnum is set to zlib error number. If an error occurred
1659  in the file system and not in the compression library, errnum is set to
1660  Z_ERRNO and the application may consult errno to get the exact error code.
1661 
1662  The application must not modify the returned string. Future calls to
1663  this function may invalidate the previously returned string. If file is
1664  closed, then the string previously returned by gzerror will no longer be
1665  available.
1666 
1667  gzerror() should be used to distinguish errors from end-of-file for those
1668  functions above that do not distinguish those cases in their return values.
1669 */
1670 
1671 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1672 /*
1673  Clears the error and end-of-file flags for file. This is analogous to the
1674  clearerr() function in stdio. This is useful for continuing to read a gzip
1675  file that is being written concurrently.
1676 */
1677 
1678 #endif /* !Z_SOLO */
1679 
1680  /* checksum functions */
1681 
1682 /*
1683  These functions are not related to compression but are exported
1684  anyway because they might be useful in applications using the compression
1685  library.
1686 */
1687 
1688 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1689 /*
1690  Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1691  return the updated checksum. If buf is Z_NULL, this function returns the
1692  required initial value for the checksum.
1693 
1694  An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1695  much faster.
1696 
1697  Usage example:
1698 
1699  uLong adler = adler32(0L, Z_NULL, 0);
1700 
1701  while (read_buffer(buffer, length) != EOF) {
1702  adler = adler32(adler, buffer, length);
1703  }
1704  if (adler != original_adler) error();
1705 */
1706 
1707 ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
1708  z_size_t len));
1709 /*
1710  Same as adler32(), but with a size_t length.
1711 */
1712 
1713 /*
1714 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1715  z_off_t len2));
1716 
1717  Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1718  and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1719  each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1720  seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1721  that the z_off_t type (like off_t) is a signed integer. If len2 is
1722  negative, the result has no meaning or utility.
1723 */
1724 
1725 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1726 /*
1727  Update a running CRC-32 with the bytes buf[0..len-1] and return the
1728  updated CRC-32. If buf is Z_NULL, this function returns the required
1729  initial value for the crc. Pre- and post-conditioning (one's complement) is
1730  performed within this function so it shouldn't be done by the application.
1731 
1732  Usage example:
1733 
1734  uLong crc = crc32(0L, Z_NULL, 0);
1735 
1736  while (read_buffer(buffer, length) != EOF) {
1737  crc = crc32(crc, buffer, length);
1738  }
1739  if (crc != original_crc) error();
1740 */
1741 
1742 ZEXTERN uLong ZEXPORT crc32_z OF((uLong adler, const Bytef *buf,
1743  z_size_t len));
1744 /*
1745  Same as crc32(), but with a size_t length.
1746 */
1747 
1748 /*
1749 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1750 
1751  Combine two CRC-32 check values into one. For two sequences of bytes,
1752  seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1753  calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1754  check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1755  len2.
1756 */
1757 
1758 
1759  /* various hacks, don't look :) */
1760 
1761 /* deflateInit and inflateInit are macros to allow checking the zlib version
1762  * and the compiler's view of z_stream:
1763  */
1764 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1765  const char *version, int stream_size));
1766 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1767  const char *version, int stream_size));
1768 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1769  int windowBits, int memLevel,
1770  int strategy, const char *version,
1771  int stream_size));
1772 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1773  const char *version, int stream_size));
1774 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1775  unsigned char FAR *window,
1776  const char *version,
1777  int stream_size));
1778 #ifdef Z_PREFIX_SET
1779 # define z_deflateInit(strm, level) \
1780  deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1781 # define z_inflateInit(strm) \
1782  inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1783 # define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1784  deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1785  (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1786 # define z_inflateInit2(strm, windowBits) \
1787  inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1788  (int)sizeof(z_stream))
1789 # define z_inflateBackInit(strm, windowBits, window) \
1790  inflateBackInit_((strm), (windowBits), (window), \
1791  ZLIB_VERSION, (int)sizeof(z_stream))
1792 #else
1793 # define deflateInit(strm, level) \
1794  deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1795 # define inflateInit(strm) \
1796  inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1797 # define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1798  deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1799  (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1800 # define inflateInit2(strm, windowBits) \
1801  inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1802  (int)sizeof(z_stream))
1803 # define inflateBackInit(strm, windowBits, window) \
1804  inflateBackInit_((strm), (windowBits), (window), \
1805  ZLIB_VERSION, (int)sizeof(z_stream))
1806 #endif
1807 
1808 #ifndef Z_SOLO
1809 
1810 /* gzgetc() macro and its supporting function and exposed data structure. Note
1811  * that the real internal state is much larger than the exposed structure.
1812  * This abbreviated structure exposes just enough for the gzgetc() macro. The
1813  * user should not mess with these exposed elements, since their names or
1814  * behavior could change in the future, perhaps even capriciously. They can
1815  * only be used by the gzgetc() macro. You have been warned.
1816  */
1817 struct gzFile_s {
1818  unsigned have;
1819  unsigned char *next;
1820  z_off64_t pos;
1821 };
1822 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */
1823 #ifdef Z_PREFIX_SET
1824 # undef z_gzgetc
1825 # define z_gzgetc(g) \
1826  ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1827 #else
1828 # define gzgetc(g) \
1829  ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1830 #endif
1831 
1832 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1833  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1834  * both are true, the application gets the *64 functions, and the regular
1835  * functions are changed to 64 bits) -- in case these are set on systems
1836  * without large file support, _LFS64_LARGEFILE must also be true
1837  */
1838 #ifdef Z_LARGE64
1839  ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1840  ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1841  ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1842  ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1843  ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1844  ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1845 #endif
1846 
1847 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1848 # ifdef Z_PREFIX_SET
1849 # define z_gzopen z_gzopen64
1850 # define z_gzseek z_gzseek64
1851 # define z_gztell z_gztell64
1852 # define z_gzoffset z_gzoffset64
1853 # define z_adler32_combine z_adler32_combine64
1854 # define z_crc32_combine z_crc32_combine64
1855 # else
1856 # define gzopen gzopen64
1857 # define gzseek gzseek64
1858 # define gztell gztell64
1859 # define gzoffset gzoffset64
1860 # define adler32_combine adler32_combine64
1861 # define crc32_combine crc32_combine64
1862 # endif
1863 # ifndef Z_LARGE64
1864  ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1865  ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1866  ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1867  ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1868  ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1869  ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1870 # endif
1871 #else
1872  ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1873  ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1874  ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1875  ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1876  ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1877  ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1878 #endif
1879 
1880 #else /* Z_SOLO */
1881 
1882  ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1883  ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1884 
1885 #endif /* !Z_SOLO */
1886 
1887 /* undocumented functions */
1888 ZEXTERN const char * ZEXPORT zError OF((int));
1889 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1890 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void));
1891 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1892 ZEXTERN int ZEXPORT inflateValidate OF((z_streamp, int));
1893 ZEXTERN unsigned long ZEXPORT inflateCodesUsed OF ((z_streamp));
1894 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1895 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1896 #if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(Z_SOLO)
1897 ZEXTERN gzFile ZEXPORT gzopen_w OF((const wchar_t *path,
1898  const char *mode));
1899 #endif
1900 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1901 # ifndef Z_SOLO
1902 ZEXTERN int ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1903  const char *format,
1904  va_list va));
1905 # endif
1906 #endif
1907 
1908 #ifdef __cplusplus
1909 }
1910 #endif
1911 
1912 #endif /* ZLIB_H */