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
37extern "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
81typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
82typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
83
84struct internal_state;
85
86typedef 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
108typedef 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*/
114typedef 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
131typedef 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
220ZEXTERN 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/*
228ZEXTERN 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
250ZEXTERN 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
363ZEXTERN 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/*
378ZEXTERN 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
400ZEXTERN 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
520ZEXTERN 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/*
538ZEXTERN 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
611ZEXTERN 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
655ZEXTERN 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
677ZEXTERN 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
695ZEXTERN 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
706ZEXTERN 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 there have been any deflate() calls since the
716   state was initialized or reset, then the input available so far is
717   compressed with the old level and strategy using deflate(strm, Z_BLOCK).
718   There are three approaches for the compression levels 0, 1..3, and 4..9
719   respectively.  The new level and strategy will take effect at the next call
720   of deflate().
721
722     If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
723   not have enough output space to complete, then the parameter change will not
724   take effect.  In this case, deflateParams() can be called again with the
725   same parameters and more output space to try again.
726
727     In order to assure a change in the parameters on the first try, the
728   deflate stream should be flushed using deflate() with Z_BLOCK or other flush
729   request until strm.avail_out is not zero, before calling deflateParams().
730   Then no more input data should be provided before the deflateParams() call.
731   If this is done, the old level and strategy will be applied to the data
732   compressed before deflateParams(), and the new level and strategy will be
733   applied to the the data compressed after deflateParams().
734
735     deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
736   state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
737   there was not enough output space to complete the compression of the
738   available input data before a change in the strategy or approach.  Note that
739   in the case of a Z_BUF_ERROR, the parameters are not changed.  A return
740   value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
741   retried with more output space.
742*/
743
744ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
745                                    int good_length,
746                                    int max_lazy,
747                                    int nice_length,
748                                    int max_chain));
749/*
750     Fine tune deflate's internal compression parameters.  This should only be
751   used by someone who understands the algorithm used by zlib's deflate for
752   searching for the best matching string, and even then only by the most
753   fanatic optimizer trying to squeeze out the last compressed bit for their
754   specific input data.  Read the deflate.c source code for the meaning of the
755   max_lazy, good_length, nice_length, and max_chain parameters.
756
757     deflateTune() can be called after deflateInit() or deflateInit2(), and
758   returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
759 */
760
761ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
762                                       uLong sourceLen));
763/*
764     deflateBound() returns an upper bound on the compressed size after
765   deflation of sourceLen bytes.  It must be called after deflateInit() or
766   deflateInit2(), and after deflateSetHeader(), if used.  This would be used
767   to allocate an output buffer for deflation in a single pass, and so would be
768   called before deflate().  If that first deflate() call is provided the
769   sourceLen input bytes, an output buffer allocated to the size returned by
770   deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
771   to return Z_STREAM_END.  Note that it is possible for the compressed size to
772   be larger than the value returned by deflateBound() if flush options other
773   than Z_FINISH or Z_NO_FLUSH are used.
774*/
775
776ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
777                                       unsigned *pending,
778                                       int *bits));
779/*
780     deflatePending() returns the number of bytes and bits of output that have
781   been generated, but not yet provided in the available output.  The bytes not
782   provided would be due to the available output space having being consumed.
783   The number of bits of output not provided are between 0 and 7, where they
784   await more bits to join them in order to fill out a full byte.  If pending
785   or bits are Z_NULL, then those values are not set.
786
787     deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
788   stream state was inconsistent.
789 */
790
791ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
792                                     int bits,
793                                     int value));
794/*
795     deflatePrime() inserts bits in the deflate output stream.  The intent
796   is that this function is used to start off the deflate output with the bits
797   leftover from a previous deflate stream when appending to it.  As such, this
798   function can only be used for raw deflate, and must be used before the first
799   deflate() call after a deflateInit2() or deflateReset().  bits must be less
800   than or equal to 16, and that many of the least significant bits of value
801   will be inserted in the output.
802
803     deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
804   room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
805   source stream state was inconsistent.
806*/
807
808ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
809                                         gz_headerp head));
810/*
811     deflateSetHeader() provides gzip header information for when a gzip
812   stream is requested by deflateInit2().  deflateSetHeader() may be called
813   after deflateInit2() or deflateReset() and before the first call of
814   deflate().  The text, time, os, extra field, name, and comment information
815   in the provided gz_header structure are written to the gzip header (xflag is
816   ignored -- the extra flags are set according to the compression level).  The
817   caller must assure that, if not Z_NULL, name and comment are terminated with
818   a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
819   available there.  If hcrc is true, a gzip header crc is included.  Note that
820   the current versions of the command-line version of gzip (up through version
821   1.3.x) do not support header crc's, and will report that it is a "multi-part
822   gzip file" and give up.
823
824     If deflateSetHeader is not used, the default gzip header has text false,
825   the time set to zero, and os set to 255, with no extra, name, or comment
826   fields.  The gzip header is returned to the default state by deflateReset().
827
828     deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
829   stream state was inconsistent.
830*/
831
832/*
833ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
834                                     int  windowBits));
835
836     This is another version of inflateInit with an extra parameter.  The
837   fields next_in, avail_in, zalloc, zfree and opaque must be initialized
838   before by the caller.
839
840     The windowBits parameter is the base two logarithm of the maximum window
841   size (the size of the history buffer).  It should be in the range 8..15 for
842   this version of the library.  The default value is 15 if inflateInit is used
843   instead.  windowBits must be greater than or equal to the windowBits value
844   provided to deflateInit2() while compressing, or it must be equal to 15 if
845   deflateInit2() was not used.  If a compressed stream with a larger window
846   size is given as input, inflate() will return with the error code
847   Z_DATA_ERROR instead of trying to allocate a larger window.
848
849     windowBits can also be zero to request that inflate use the window size in
850   the zlib header of the compressed stream.
851
852     windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
853   determines the window size.  inflate() will then process raw deflate data,
854   not looking for a zlib or gzip header, not generating a check value, and not
855   looking for any check values for comparison at the end of the stream.  This
856   is for use with other formats that use the deflate compressed data format
857   such as zip.  Those formats provide their own check values.  If a custom
858   format is developed using the raw deflate format for compressed data, it is
859   recommended that a check value such as an Adler-32 or a CRC-32 be applied to
860   the uncompressed data as is done in the zlib, gzip, and zip formats.  For
861   most applications, the zlib format should be used as is.  Note that comments
862   above on the use in deflateInit2() applies to the magnitude of windowBits.
863
864     windowBits can also be greater than 15 for optional gzip decoding.  Add
865   32 to windowBits to enable zlib and gzip decoding with automatic header
866   detection, or add 16 to decode only the gzip format (the zlib format will
867   return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
868   CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
869   below), inflate() will not automatically decode concatenated gzip streams.
870   inflate() will return Z_STREAM_END at the end of the gzip stream.  The state
871   would need to be reset to continue decoding a subsequent gzip stream.
872
873     inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
874   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
875   version assumed by the caller, or Z_STREAM_ERROR if the parameters are
876   invalid, such as a null pointer to the structure.  msg is set to null if
877   there is no error message.  inflateInit2 does not perform any decompression
878   apart from possibly reading the zlib header if present: actual decompression
879   will be done by inflate().  (So next_in and avail_in may be modified, but
880   next_out and avail_out are unused and unchanged.) The current implementation
881   of inflateInit2() does not process any header information -- that is
882   deferred until inflate() is called.
883*/
884
885ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
886                                             const Bytef *dictionary,
887                                             uInt  dictLength));
888/*
889     Initializes the decompression dictionary from the given uncompressed byte
890   sequence.  This function must be called immediately after a call of inflate,
891   if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
892   can be determined from the Adler-32 value returned by that call of inflate.
893   The compressor and decompressor must use exactly the same dictionary (see
894   deflateSetDictionary).  For raw inflate, this function can be called at any
895   time to set the dictionary.  If the provided dictionary is smaller than the
896   window and there is already data in the window, then the provided dictionary
897   will amend what's there.  The application must insure that the dictionary
898   that was used for compression is provided.
899
900     inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
901   parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
902   inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
903   expected one (incorrect Adler-32 value).  inflateSetDictionary does not
904   perform any decompression: this will be done by subsequent calls of
905   inflate().
906*/
907
908ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
909                                             Bytef *dictionary,
910                                             uInt  *dictLength));
911/*
912     Returns the sliding dictionary being maintained by inflate.  dictLength is
913   set to the number of bytes in the dictionary, and that many bytes are copied
914   to dictionary.  dictionary must have enough space, where 32768 bytes is
915   always enough.  If inflateGetDictionary() is called with dictionary equal to
916   Z_NULL, then only the dictionary length is returned, and nothing is copied.
917   Similary, if dictLength is Z_NULL, then it is not set.
918
919     inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
920   stream state is inconsistent.
921*/
922
923ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
924/*
925     Skips invalid compressed data until a possible full flush point (see above
926   for the description of deflate with Z_FULL_FLUSH) can be found, or until all
927   available input is skipped.  No output is provided.
928
929     inflateSync searches for a 00 00 FF FF pattern in the compressed data.
930   All full flush points have this pattern, but not all occurrences of this
931   pattern are full flush points.
932
933     inflateSync returns Z_OK if a possible full flush point has been found,
934   Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
935   has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
936   In the success case, the application may save the current current value of
937   total_in which indicates where valid compressed data was found.  In the
938   error case, the application may repeatedly call inflateSync, providing more
939   input each time, until success or end of the input data.
940*/
941
942ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
943                                    z_streamp source));
944/*
945     Sets the destination stream as a complete copy of the source stream.
946
947     This function can be useful when randomly accessing a large stream.  The
948   first pass through the stream can periodically record the inflate state,
949   allowing restarting inflate at those points when randomly accessing the
950   stream.
951
952     inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
953   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
954   (such as zalloc being Z_NULL).  msg is left unchanged in both source and
955   destination.
956*/
957
958ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
959/*
960     This function is equivalent to inflateEnd followed by inflateInit,
961   but does not free and reallocate the internal decompression state.  The
962   stream will keep attributes that may have been set by inflateInit2.
963
964     inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
965   stream state was inconsistent (such as zalloc or state being Z_NULL).
966*/
967
968ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
969                                      int windowBits));
970/*
971     This function is the same as inflateReset, but it also permits changing
972   the wrap and window size requests.  The windowBits parameter is interpreted
973   the same as it is for inflateInit2.  If the window size is changed, then the
974   memory allocated for the window is freed, and the window will be reallocated
975   by inflate() if needed.
976
977     inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
978   stream state was inconsistent (such as zalloc or state being Z_NULL), or if
979   the windowBits parameter is invalid.
980*/
981
982ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
983                                     int bits,
984                                     int value));
985/*
986     This function inserts bits in the inflate input stream.  The intent is
987   that this function is used to start inflating at a bit position in the
988   middle of a byte.  The provided bits will be used before any bytes are used
989   from next_in.  This function should only be used with raw inflate, and
990   should be used before the first inflate() call after inflateInit2() or
991   inflateReset().  bits must be less than or equal to 16, and that many of the
992   least significant bits of value will be inserted in the input.
993
994     If bits is negative, then the input stream bit buffer is emptied.  Then
995   inflatePrime() can be called again to put bits in the buffer.  This is used
996   to clear out bits leftover after feeding inflate a block description prior
997   to feeding inflate codes.
998
999     inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1000   stream state was inconsistent.
1001*/
1002
1003ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
1004/*
1005     This function returns two values, one in the lower 16 bits of the return
1006   value, and the other in the remaining upper bits, obtained by shifting the
1007   return value down 16 bits.  If the upper value is -1 and the lower value is
1008   zero, then inflate() is currently decoding information outside of a block.
1009   If the upper value is -1 and the lower value is non-zero, then inflate is in
1010   the middle of a stored block, with the lower value equaling the number of
1011   bytes from the input remaining to copy.  If the upper value is not -1, then
1012   it is the number of bits back from the current bit position in the input of
1013   the code (literal or length/distance pair) currently being processed.  In
1014   that case the lower value is the number of bytes already emitted for that
1015   code.
1016
1017     A code is being processed if inflate is waiting for more input to complete
1018   decoding of the code, or if it has completed decoding but is waiting for
1019   more output space to write the literal or match data.
1020
1021     inflateMark() is used to mark locations in the input data for random
1022   access, which may be at bit positions, and to note those cases where the
1023   output of a code may span boundaries of random access blocks.  The current
1024   location in the input stream can be determined from avail_in and data_type
1025   as noted in the description for the Z_BLOCK flush parameter for inflate.
1026
1027     inflateMark returns the value noted above, or -65536 if the provided
1028   source stream state was inconsistent.
1029*/
1030
1031ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1032                                         gz_headerp head));
1033/*
1034     inflateGetHeader() requests that gzip header information be stored in the
1035   provided gz_header structure.  inflateGetHeader() may be called after
1036   inflateInit2() or inflateReset(), and before the first call of inflate().
1037   As inflate() processes the gzip stream, head->done is zero until the header
1038   is completed, at which time head->done is set to one.  If a zlib stream is
1039   being decoded, then head->done is set to -1 to indicate that there will be
1040   no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
1041   used to force inflate() to return immediately after header processing is
1042   complete and before any actual data is decompressed.
1043
1044     The text, time, xflags, and os fields are filled in with the gzip header
1045   contents.  hcrc is set to true if there is a header CRC.  (The header CRC
1046   was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1047   contains the maximum number of bytes to write to extra.  Once done is true,
1048   extra_len contains the actual extra field length, and extra contains the
1049   extra field, or that field truncated if extra_max is less than extra_len.
1050   If name is not Z_NULL, then up to name_max characters are written there,
1051   terminated with a zero unless the length is greater than name_max.  If
1052   comment is not Z_NULL, then up to comm_max characters are written there,
1053   terminated with a zero unless the length is greater than comm_max.  When any
1054   of extra, name, or comment are not Z_NULL and the respective field is not
1055   present in the header, then that field is set to Z_NULL to signal its
1056   absence.  This allows the use of deflateSetHeader() with the returned
1057   structure to duplicate the header.  However if those fields are set to
1058   allocated memory, then the application will need to save those pointers
1059   elsewhere so that they can be eventually freed.
1060
1061     If inflateGetHeader is not used, then the header information is simply
1062   discarded.  The header is always checked for validity, including the header
1063   CRC if present.  inflateReset() will reset the process to discard the header
1064   information.  The application would need to call inflateGetHeader() again to
1065   retrieve the header from the next gzip stream.
1066
1067     inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1068   stream state was inconsistent.
1069*/
1070
1071/*
1072ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1073                                        unsigned char FAR *window));
1074
1075     Initialize the internal stream state for decompression using inflateBack()
1076   calls.  The fields zalloc, zfree and opaque in strm must be initialized
1077   before the call.  If zalloc and zfree are Z_NULL, then the default library-
1078   derived memory allocation routines are used.  windowBits is the base two
1079   logarithm of the window size, in the range 8..15.  window is a caller
1080   supplied buffer of that size.  Except for special applications where it is
1081   assured that deflate was used with small window sizes, windowBits must be 15
1082   and a 32K byte window must be supplied to be able to decompress general
1083   deflate streams.
1084
1085     See inflateBack() for the usage of these routines.
1086
1087     inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1088   the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1089   allocated, or Z_VERSION_ERROR if the version of the library does not match
1090   the version of the header file.
1091*/
1092
1093typedef unsigned (*in_func) OF((void FAR *,
1094                                z_const unsigned char FAR * FAR *));
1095typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1096
1097ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1098                                    in_func in, void FAR *in_desc,
1099                                    out_func out, void FAR *out_desc));
1100/*
1101     inflateBack() does a raw inflate with a single call using a call-back
1102   interface for input and output.  This is potentially more efficient than
1103   inflate() for file i/o applications, in that it avoids copying between the
1104   output and the sliding window by simply making the window itself the output
1105   buffer.  inflate() can be faster on modern CPUs when used with large
1106   buffers.  inflateBack() trusts the application to not change the output
1107   buffer passed by the output function, at least until inflateBack() returns.
1108
1109     inflateBackInit() must be called first to allocate the internal state
1110   and to initialize the state with the user-provided window buffer.
1111   inflateBack() may then be used multiple times to inflate a complete, raw
1112   deflate stream with each call.  inflateBackEnd() is then called to free the
1113   allocated state.
1114
1115     A raw deflate stream is one with no zlib or gzip header or trailer.
1116   This routine would normally be used in a utility that reads zip or gzip
1117   files and writes out uncompressed files.  The utility would decode the
1118   header and process the trailer on its own, hence this routine expects only
1119   the raw deflate stream to decompress.  This is different from the default
1120   behavior of inflate(), which expects a zlib header and trailer around the
1121   deflate stream.
1122
1123     inflateBack() uses two subroutines supplied by the caller that are then
1124   called by inflateBack() for input and output.  inflateBack() calls those
1125   routines until it reads a complete deflate stream and writes out all of the
1126   uncompressed data, or until it encounters an error.  The function's
1127   parameters and return types are defined above in the in_func and out_func
1128   typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
1129   number of bytes of provided input, and a pointer to that input in buf.  If
1130   there is no input available, in() must return zero -- buf is ignored in that
1131   case -- and inflateBack() will return a buffer error.  inflateBack() will
1132   call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1133   out() should return zero on success, or non-zero on failure.  If out()
1134   returns non-zero, inflateBack() will return with an error.  Neither in() nor
1135   out() are permitted to change the contents of the window provided to
1136   inflateBackInit(), which is also the buffer that out() uses to write from.
1137   The length written by out() will be at most the window size.  Any non-zero
1138   amount of input may be provided by in().
1139
1140     For convenience, inflateBack() can be provided input on the first call by
1141   setting strm->next_in and strm->avail_in.  If that input is exhausted, then
1142   in() will be called.  Therefore strm->next_in must be initialized before
1143   calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
1144   immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
1145   must also be initialized, and then if strm->avail_in is not zero, input will
1146   initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
1147
1148     The in_desc and out_desc parameters of inflateBack() is passed as the
1149   first parameter of in() and out() respectively when they are called.  These
1150   descriptors can be optionally used to pass any information that the caller-
1151   supplied in() and out() functions need to do their job.
1152
1153     On return, inflateBack() will set strm->next_in and strm->avail_in to
1154   pass back any unused input that was provided by the last in() call.  The
1155   return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1156   if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1157   in the deflate stream (in which case strm->msg is set to indicate the nature
1158   of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1159   In the case of Z_BUF_ERROR, an input or output error can be distinguished
1160   using strm->next_in which will be Z_NULL only if in() returned an error.  If
1161   strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1162   non-zero.  (in() will always be called before out(), so strm->next_in is
1163   assured to be defined if out() returns non-zero.)  Note that inflateBack()
1164   cannot return Z_OK.
1165*/
1166
1167ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1168/*
1169     All memory allocated by inflateBackInit() is freed.
1170
1171     inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1172   state was inconsistent.
1173*/
1174
1175ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1176/* Return flags indicating compile-time options.
1177
1178    Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1179     1.0: size of uInt
1180     3.2: size of uLong
1181     5.4: size of voidpf (pointer)
1182     7.6: size of z_off_t
1183
1184    Compiler, assembler, and debug options:
1185     8: ZLIB_DEBUG
1186     9: ASMV or ASMINF -- use ASM code
1187     10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1188     11: 0 (reserved)
1189
1190    One-time table building (smaller code, but not thread-safe if true):
1191     12: BUILDFIXED -- build static block decoding tables when needed
1192     13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1193     14,15: 0 (reserved)
1194
1195    Library content (indicates missing functionality):
1196     16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1197                          deflate code when not needed)
1198     17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1199                    and decode gzip streams (to avoid linking crc code)
1200     18-19: 0 (reserved)
1201
1202    Operation variations (changes in library functionality):
1203     20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1204     21: FASTEST -- deflate algorithm with only one, lowest compression level
1205     22,23: 0 (reserved)
1206
1207    The sprintf variant used by gzprintf (zero is best):
1208     24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1209     25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1210     26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1211
1212    Remainder:
1213     27-31: 0 (reserved)
1214 */
1215
1216#if !defined(Z_SOLO) || defined(_KERNEL)
1217
1218                        /* utility functions */
1219
1220/*
1221     The following utility functions are implemented on top of the basic
1222   stream-oriented functions.  To simplify the interface, some default options
1223   are assumed (compression level and memory usage, standard memory allocation
1224   functions).  The source code of these utility functions can be modified if
1225   you need special options.
1226*/
1227
1228ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
1229                                 const Bytef *source, uLong sourceLen));
1230/*
1231     Compresses the source buffer into the destination buffer.  sourceLen is
1232   the byte length of the source buffer.  Upon entry, destLen is the total size
1233   of the destination buffer, which must be at least the value returned by
1234   compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1235   compressed data.  compress() is equivalent to compress2() with a level
1236   parameter of Z_DEFAULT_COMPRESSION.
1237
1238     compress returns Z_OK if success, Z_MEM_ERROR if there was not
1239   enough memory, Z_BUF_ERROR if there was not enough room in the output
1240   buffer.
1241*/
1242
1243ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
1244                                  const Bytef *source, uLong sourceLen,
1245                                  int level));
1246/*
1247     Compresses the source buffer into the destination buffer.  The level
1248   parameter has the same meaning as in deflateInit.  sourceLen is the byte
1249   length of the source buffer.  Upon entry, destLen is the total size of the
1250   destination buffer, which must be at least the value returned by
1251   compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1252   compressed data.
1253
1254     compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1255   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1256   Z_STREAM_ERROR if the level parameter is invalid.
1257*/
1258
1259ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1260/*
1261     compressBound() returns an upper bound on the compressed size after
1262   compress() or compress2() on sourceLen bytes.  It would be used before a
1263   compress() or compress2() call to allocate the destination buffer.
1264*/
1265
1266ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
1267                                   const Bytef *source, uLong sourceLen));
1268/*
1269     Decompresses the source buffer into the destination buffer.  sourceLen is
1270   the byte length of the source buffer.  Upon entry, destLen is the total size
1271   of the destination buffer, which must be large enough to hold the entire
1272   uncompressed data.  (The size of the uncompressed data must have been saved
1273   previously by the compressor and transmitted to the decompressor by some
1274   mechanism outside the scope of this compression library.) Upon exit, destLen
1275   is the actual size of the uncompressed data.
1276
1277     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1278   enough memory, Z_BUF_ERROR if there was not enough room in the output
1279   buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
1280   the case where there is not enough room, uncompress() will fill the output
1281   buffer with the uncompressed data up to that point.
1282*/
1283
1284ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest,   uLongf *destLen,
1285                                    const Bytef *source, uLong *sourceLen));
1286/*
1287     Same as uncompress, except that sourceLen is a pointer, where the
1288   length of the source is *sourceLen.  On return, *sourceLen is the number of
1289   source bytes consumed.
1290*/
1291#endif /* !Z_SOLO || _KERNEL */
1292
1293#ifndef Z_SOLO
1294
1295                        /* gzip file access functions */
1296
1297/*
1298     This library supports reading and writing files in gzip (.gz) format with
1299   an interface similar to that of stdio, using the functions that start with
1300   "gz".  The gzip format is different from the zlib format.  gzip is a gzip
1301   wrapper, documented in RFC 1952, wrapped around a deflate stream.
1302*/
1303
1304typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
1305
1306/*
1307ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1308
1309     Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
1310   in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1311   a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1312   compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1313   for fixed code compression as in "wb9F".  (See the description of
1314   deflateInit2 for more information about the strategy parameter.)  'T' will
1315   request transparent writing or appending with no compression and not using
1316   the gzip format.
1317
1318     "a" can be used instead of "w" to request that the gzip stream that will
1319   be written be appended to the file.  "+" will result in an error, since
1320   reading and writing to the same gzip file is not supported.  The addition of
1321   "x" when writing will create the file exclusively, which fails if the file
1322   already exists.  On systems that support it, the addition of "e" when
1323   reading or writing will set the flag to close the file on an execve() call.
1324
1325     These functions, as well as gzip, will read and decode a sequence of gzip
1326   streams in a file.  The append function of gzopen() can be used to create
1327   such a file.  (Also see gzflush() for another way to do this.)  When
1328   appending, gzopen does not test whether the file begins with a gzip stream,
1329   nor does it look for the end of the gzip streams to begin appending.  gzopen
1330   will simply append a gzip stream to the existing file.
1331
1332     gzopen can be used to read a file which is not in gzip format; in this
1333   case gzread will directly read from the file without decompression.  When
1334   reading, this will be detected automatically by looking for the magic two-
1335   byte gzip header.
1336
1337     gzopen returns NULL if the file could not be opened, if there was
1338   insufficient memory to allocate the gzFile state, or if an invalid mode was
1339   specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1340   errno can be checked to determine if the reason gzopen failed was that the
1341   file could not be opened.
1342*/
1343
1344ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1345/*
1346     gzdopen associates a gzFile with the file descriptor fd.  File descriptors
1347   are obtained from calls like open, dup, creat, pipe or fileno (if the file
1348   has been previously opened with fopen).  The mode parameter is as in gzopen.
1349
1350     The next call of gzclose on the returned gzFile will also close the file
1351   descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1352   fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1353   mode);.  The duplicated descriptor should be saved to avoid a leak, since
1354   gzdopen does not close fd if it fails.  If you are using fileno() to get the
1355   file descriptor from a FILE *, then you will have to use dup() to avoid
1356   double-close()ing the file descriptor.  Both gzclose() and fclose() will
1357   close the associated file descriptor, so they need to have different file
1358   descriptors.
1359
1360     gzdopen returns NULL if there was insufficient memory to allocate the
1361   gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1362   provided, or '+' was provided), or if fd is -1.  The file descriptor is not
1363   used until the next gz* read, write, seek, or close operation, so gzdopen
1364   will not detect if fd is invalid (unless fd is -1).
1365*/
1366
1367ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1368/*
1369     Set the internal buffer size used by this library's functions.  The
1370   default buffer size is 8192 bytes.  This function must be called after
1371   gzopen() or gzdopen(), and before any other calls that read or write the
1372   file.  The buffer memory allocation is always deferred to the first read or
1373   write.  Three times that size in buffer space is allocated.  A larger buffer
1374   size of, for example, 64K or 128K bytes will noticeably increase the speed
1375   of decompression (reading).
1376
1377     The new buffer size also affects the maximum length for gzprintf().
1378
1379     gzbuffer() returns 0 on success, or -1 on failure, such as being called
1380   too late.
1381*/
1382
1383ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1384/*
1385     Dynamically update the compression level or strategy.  See the description
1386   of deflateInit2 for the meaning of these parameters.  Previously provided
1387   data is flushed before the parameter change.
1388
1389     gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1390   opened for writing, Z_ERRNO if there is an error writing the flushed data,
1391   or Z_MEM_ERROR if there is a memory allocation error.
1392*/
1393
1394ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1395/*
1396     Reads the given number of uncompressed bytes from the compressed file.  If
1397   the input file is not in gzip format, gzread copies the given number of
1398   bytes into the buffer directly from the file.
1399
1400     After reaching the end of a gzip stream in the input, gzread will continue
1401   to read, looking for another gzip stream.  Any number of gzip streams may be
1402   concatenated in the input file, and will all be decompressed by gzread().
1403   If something other than a gzip stream is encountered after a gzip stream,
1404   that remaining trailing garbage is ignored (and no error is returned).
1405
1406     gzread can be used to read a gzip file that is being concurrently written.
1407   Upon reaching the end of the input, gzread will return with the available
1408   data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1409   gzclearerr can be used to clear the end of file indicator in order to permit
1410   gzread to be tried again.  Z_OK indicates that a gzip stream was completed
1411   on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
1412   middle of a gzip stream.  Note that gzread does not return -1 in the event
1413   of an incomplete gzip stream.  This error is deferred until gzclose(), which
1414   will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1415   stream.  Alternatively, gzerror can be used before gzclose to detect this
1416   case.
1417
1418     gzread returns the number of uncompressed bytes actually read, less than
1419   len for end of file, or -1 for error.  If len is too large to fit in an int,
1420   then nothing is read, -1 is returned, and the error state is set to
1421   Z_STREAM_ERROR.
1422*/
1423
1424ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
1425                                     gzFile file));
1426/*
1427     Read up to nitems items of size size from file to buf, otherwise operating
1428   as gzread() does.  This duplicates the interface of stdio's fread(), with
1429   size_t request and return types.  If the library defines size_t, then
1430   z_size_t is identical to size_t.  If not, then z_size_t is an unsigned
1431   integer type that can contain a pointer.
1432
1433     gzfread() returns the number of full items read of size size, or zero if
1434   the end of the file was reached and a full item could not be read, or if
1435   there was an error.  gzerror() must be consulted if zero is returned in
1436   order to determine if there was an error.  If the multiplication of size and
1437   nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1438   is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1439
1440     In the event that the end of file is reached and only a partial item is
1441   available at the end, i.e. the remaining uncompressed data length is not a
1442   multiple of size, then the final partial item is nevetheless read into buf
1443   and the end-of-file flag is set.  The length of the partial item read is not
1444   provided, but could be inferred from the result of gztell().  This behavior
1445   is the same as the behavior of fread() implementations in common libraries,
1446   but it prevents the direct use of gzfread() to read a concurrently written
1447   file, reseting and retrying on end-of-file, when size is not 1.
1448*/
1449
1450ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1451                                voidpc buf, unsigned len));
1452/*
1453     Writes the given number of uncompressed bytes into the compressed file.
1454   gzwrite returns the number of uncompressed bytes written or 0 in case of
1455   error.
1456*/
1457
1458ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
1459                                      z_size_t nitems, gzFile file));
1460/*
1461     gzfwrite() writes nitems items of size size from buf to file, duplicating
1462   the interface of stdio's fwrite(), with size_t request and return types.  If
1463   the library defines size_t, then z_size_t is identical to size_t.  If not,
1464   then z_size_t is an unsigned integer type that can contain a pointer.
1465
1466     gzfwrite() returns the number of full items written of size size, or zero
1467   if there was an error.  If the multiplication of size and nitems overflows,
1468   i.e. the product does not fit in a z_size_t, then nothing is written, zero
1469   is returned, and the error state is set to Z_STREAM_ERROR.
1470*/
1471
1472ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1473/*
1474     Converts, formats, and writes the arguments to the compressed file under
1475   control of the format string, as in fprintf.  gzprintf returns the number of
1476   uncompressed bytes actually written, or a negative zlib error code in case
1477   of error.  The number of uncompressed bytes written is limited to 8191, or
1478   one less than the buffer size given to gzbuffer().  The caller should assure
1479   that this limit is not exceeded.  If it is exceeded, then gzprintf() will
1480   return an error (0) with nothing written.  In this case, there may also be a
1481   buffer overflow with unpredictable consequences, which is possible only if
1482   zlib was compiled with the insecure functions sprintf() or vsprintf()
1483   because the secure snprintf() or vsnprintf() functions were not available.
1484   This can be determined using zlibCompileFlags().
1485*/
1486
1487ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1488/*
1489     Writes the given null-terminated string to the compressed file, excluding
1490   the terminating null character.
1491
1492     gzputs returns the number of characters written, or -1 in case of error.
1493*/
1494
1495ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1496/*
1497     Reads bytes from the compressed file until len-1 characters are read, or a
1498   newline character is read and transferred to buf, or an end-of-file
1499   condition is encountered.  If any characters are read or if len == 1, the
1500   string is terminated with a null character.  If no characters are read due
1501   to an end-of-file or len < 1, then the buffer is left untouched.
1502
1503     gzgets returns buf which is a null-terminated string, or it returns NULL
1504   for end-of-file or in case of error.  If there was an error, the contents at
1505   buf are indeterminate.
1506*/
1507
1508ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1509/*
1510     Writes c, converted to an unsigned char, into the compressed file.  gzputc
1511   returns the value that was written, or -1 in case of error.
1512*/
1513
1514ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1515/*
1516     Reads one byte from the compressed file.  gzgetc returns this byte or -1
1517   in case of end of file or error.  This is implemented as a macro for speed.
1518   As such, it does not do all of the checking the other functions do.  I.e.
1519   it does not check to see if file is NULL, nor whether the structure file
1520   points to has been clobbered or not.
1521*/
1522
1523ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1524/*
1525     Push one character back onto the stream to be read as the first character
1526   on the next read.  At least one character of push-back is allowed.
1527   gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
1528   fail if c is -1, and may fail if a character has been pushed but not read
1529   yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
1530   output buffer size of pushed characters is allowed.  (See gzbuffer above.)
1531   The pushed character will be discarded if the stream is repositioned with
1532   gzseek() or gzrewind().
1533*/
1534
1535ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1536/*
1537     Flushes all pending output into the compressed file.  The parameter flush
1538   is as in the deflate() function.  The return value is the zlib error number
1539   (see function gzerror below).  gzflush is only permitted when writing.
1540
1541     If the flush parameter is Z_FINISH, the remaining data is written and the
1542   gzip stream is completed in the output.  If gzwrite() is called again, a new
1543   gzip stream will be started in the output.  gzread() is able to read such
1544   concatenated gzip streams.
1545
1546     gzflush should be called only when strictly necessary because it will
1547   degrade compression if called too often.
1548*/
1549
1550/*
1551ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1552                                   z_off_t offset, int whence));
1553
1554     Sets the starting position for the next gzread or gzwrite on the given
1555   compressed file.  The offset represents a number of bytes in the
1556   uncompressed data stream.  The whence parameter is defined as in lseek(2);
1557   the value SEEK_END is not supported.
1558
1559     If the file is opened for reading, this function is emulated but can be
1560   extremely slow.  If the file is opened for writing, only forward seeks are
1561   supported; gzseek then compresses a sequence of zeroes up to the new
1562   starting position.
1563
1564     gzseek returns the resulting offset location as measured in bytes from
1565   the beginning of the uncompressed stream, or -1 in case of error, in
1566   particular if the file is opened for writing and the new starting position
1567   would be before the current position.
1568*/
1569
1570ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
1571/*
1572     Rewinds the given file. This function is supported only for reading.
1573
1574     gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1575*/
1576
1577/*
1578ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
1579
1580     Returns the starting position for the next gzread or gzwrite on the given
1581   compressed file.  This position represents a number of bytes in the
1582   uncompressed data stream, and is zero when starting, even if appending or
1583   reading a gzip stream from the middle of a file using gzdopen().
1584
1585     gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1586*/
1587
1588/*
1589ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1590
1591     Returns the current offset in the file being read or written.  This offset
1592   includes the count of bytes that precede the gzip stream, for example when
1593   appending or when using gzdopen() for reading.  When reading, the offset
1594   does not include as yet unused buffered input.  This information can be used
1595   for a progress indicator.  On error, gzoffset() returns -1.
1596*/
1597
1598ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1599/*
1600     Returns true (1) if the end-of-file indicator has been set while reading,
1601   false (0) otherwise.  Note that the end-of-file indicator is set only if the
1602   read tried to go past the end of the input, but came up short.  Therefore,
1603   just like feof(), gzeof() may return false even if there is no more data to
1604   read, in the event that the last read request was for the exact number of
1605   bytes remaining in the input file.  This will happen if the input file size
1606   is an exact multiple of the buffer size.
1607
1608     If gzeof() returns true, then the read functions will return no more data,
1609   unless the end-of-file indicator is reset by gzclearerr() and the input file
1610   has grown since the previous end of file was detected.
1611*/
1612
1613ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1614/*
1615     Returns true (1) if file is being copied directly while reading, or false
1616   (0) if file is a gzip stream being decompressed.
1617
1618     If the input file is empty, gzdirect() will return true, since the input
1619   does not contain a gzip stream.
1620
1621     If gzdirect() is used immediately after gzopen() or gzdopen() it will
1622   cause buffers to be allocated to allow reading the file to determine if it
1623   is a gzip file.  Therefore if gzbuffer() is used, it should be called before
1624   gzdirect().
1625
1626     When writing, gzdirect() returns true (1) if transparent writing was
1627   requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
1628   gzdirect() is not needed when writing.  Transparent writing must be
1629   explicitly requested, so the application already knows the answer.  When
1630   linking statically, using gzdirect() will include all of the zlib code for
1631   gzip file reading and decompression, which may not be desired.)
1632*/
1633
1634ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
1635/*
1636     Flushes all pending output if necessary, closes the compressed file and
1637   deallocates the (de)compression state.  Note that once file is closed, you
1638   cannot call gzerror with file, since its structures have been deallocated.
1639   gzclose must not be called more than once on the same file, just as free
1640   must not be called more than once on the same allocation.
1641
1642     gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1643   file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1644   last read ended in the middle of a gzip stream, or Z_OK on success.
1645*/
1646
1647ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1648ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1649/*
1650     Same as gzclose(), but gzclose_r() is only for use when reading, and
1651   gzclose_w() is only for use when writing or appending.  The advantage to
1652   using these instead of gzclose() is that they avoid linking in zlib
1653   compression or decompression code that is not used when only reading or only
1654   writing respectively.  If gzclose() is used, then both compression and
1655   decompression code will be included the application when linking to a static
1656   zlib library.
1657*/
1658
1659ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1660/*
1661     Returns the error message for the last error which occurred on the given
1662   compressed file.  errnum is set to zlib error number.  If an error occurred
1663   in the file system and not in the compression library, errnum is set to
1664   Z_ERRNO and the application may consult errno to get the exact error code.
1665
1666     The application must not modify the returned string.  Future calls to
1667   this function may invalidate the previously returned string.  If file is
1668   closed, then the string previously returned by gzerror will no longer be
1669   available.
1670
1671     gzerror() should be used to distinguish errors from end-of-file for those
1672   functions above that do not distinguish those cases in their return values.
1673*/
1674
1675ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1676/*
1677     Clears the error and end-of-file flags for file.  This is analogous to the
1678   clearerr() function in stdio.  This is useful for continuing to read a gzip
1679   file that is being written concurrently.
1680*/
1681
1682#endif /* !Z_SOLO */
1683
1684                        /* checksum functions */
1685
1686/*
1687     These functions are not related to compression but are exported
1688   anyway because they might be useful in applications using the compression
1689   library.
1690*/
1691
1692ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1693/*
1694     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1695   return the updated checksum.  If buf is Z_NULL, this function returns the
1696   required initial value for the checksum.
1697
1698     An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1699   much faster.
1700
1701   Usage example:
1702
1703     uLong adler = adler32(0L, Z_NULL, 0);
1704
1705     while (read_buffer(buffer, length) != EOF) {
1706       adler = adler32(adler, buffer, length);
1707     }
1708     if (adler != original_adler) error();
1709*/
1710
1711ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
1712                                    z_size_t len));
1713/*
1714     Same as adler32(), but with a size_t length.
1715*/
1716
1717/*
1718ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1719                                          z_off_t len2));
1720
1721     Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
1722   and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1723   each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
1724   seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
1725   that the z_off_t type (like off_t) is a signed integer.  If len2 is
1726   negative, the result has no meaning or utility.
1727*/
1728
1729ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
1730/*
1731     Update a running CRC-32 with the bytes buf[0..len-1] and return the
1732   updated CRC-32.  If buf is Z_NULL, this function returns the required
1733   initial value for the crc.  Pre- and post-conditioning (one's complement) is
1734   performed within this function so it shouldn't be done by the application.
1735
1736   Usage example:
1737
1738     uLong crc = crc32(0L, Z_NULL, 0);
1739
1740     while (read_buffer(buffer, length) != EOF) {
1741       crc = crc32(crc, buffer, length);
1742     }
1743     if (crc != original_crc) error();
1744*/
1745
1746ZEXTERN uLong ZEXPORT crc32_z OF((uLong adler, const Bytef *buf,
1747                                  z_size_t len));
1748/*
1749     Same as crc32(), but with a size_t length.
1750*/
1751
1752/*
1753ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1754
1755     Combine two CRC-32 check values into one.  For two sequences of bytes,
1756   seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1757   calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
1758   check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1759   len2.
1760*/
1761
1762
1763                        /* various hacks, don't look :) */
1764
1765/* deflateInit and inflateInit are macros to allow checking the zlib version
1766 * and the compiler's view of z_stream:
1767 */
1768ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1769                                     const char *version, int stream_size));
1770ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1771                                     const char *version, int stream_size));
1772ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
1773                                      int windowBits, int memLevel,
1774                                      int strategy, const char *version,
1775                                      int stream_size));
1776ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
1777                                      const char *version, int stream_size));
1778ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1779                                         unsigned char FAR *window,
1780                                         const char *version,
1781                                         int stream_size));
1782#ifdef Z_PREFIX_SET
1783#  define z_deflateInit(strm, level) \
1784          deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1785#  define z_inflateInit(strm) \
1786          inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1787#  define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1788          deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1789                        (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1790#  define z_inflateInit2(strm, windowBits) \
1791          inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1792                        (int)sizeof(z_stream))
1793#  define z_inflateBackInit(strm, windowBits, window) \
1794          inflateBackInit_((strm), (windowBits), (window), \
1795                           ZLIB_VERSION, (int)sizeof(z_stream))
1796#else
1797#  define deflateInit(strm, level) \
1798          deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1799#  define inflateInit(strm) \
1800          inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1801#  define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1802          deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1803                        (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1804#  define inflateInit2(strm, windowBits) \
1805          inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1806                        (int)sizeof(z_stream))
1807#  define inflateBackInit(strm, windowBits, window) \
1808          inflateBackInit_((strm), (windowBits), (window), \
1809                           ZLIB_VERSION, (int)sizeof(z_stream))
1810#endif
1811
1812#ifndef Z_SOLO
1813
1814/* gzgetc() macro and its supporting function and exposed data structure.  Note
1815 * that the real internal state is much larger than the exposed structure.
1816 * This abbreviated structure exposes just enough for the gzgetc() macro.  The
1817 * user should not mess with these exposed elements, since their names or
1818 * behavior could change in the future, perhaps even capriciously.  They can
1819 * only be used by the gzgetc() macro.  You have been warned.
1820 */
1821struct gzFile_s {
1822    unsigned have;
1823    unsigned char *next;
1824    z_off64_t pos;
1825};
1826ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
1827#ifdef Z_PREFIX_SET
1828#  undef z_gzgetc
1829#  define z_gzgetc(g) \
1830          ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1831#else
1832#  define gzgetc(g) \
1833          ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1834#endif
1835
1836/* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1837 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1838 * both are true, the application gets the *64 functions, and the regular
1839 * functions are changed to 64 bits) -- in case these are set on systems
1840 * without large file support, _LFS64_LARGEFILE must also be true
1841 */
1842#ifdef Z_LARGE64
1843   ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1844   ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1845   ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1846   ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1847   ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1848   ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1849#endif
1850
1851#if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1852#  ifdef Z_PREFIX_SET
1853#    define z_gzopen z_gzopen64
1854#    define z_gzseek z_gzseek64
1855#    define z_gztell z_gztell64
1856#    define z_gzoffset z_gzoffset64
1857#    define z_adler32_combine z_adler32_combine64
1858#    define z_crc32_combine z_crc32_combine64
1859#  else
1860#    define gzopen gzopen64
1861#    define gzseek gzseek64
1862#    define gztell gztell64
1863#    define gzoffset gzoffset64
1864#    define adler32_combine adler32_combine64
1865#    define crc32_combine crc32_combine64
1866#  endif
1867#  ifndef Z_LARGE64
1868     ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1869     ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1870     ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1871     ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1872     ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1873     ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1874#  endif
1875#else
1876   ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1877   ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1878   ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1879   ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1880   ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1881   ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1882#endif
1883
1884#else /* Z_SOLO */
1885
1886   ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1887   ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1888
1889#endif /* !Z_SOLO */
1890
1891/* undocumented functions */
1892ZEXTERN const char   * ZEXPORT zError           OF((int));
1893ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
1894ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
1895ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
1896ZEXTERN int            ZEXPORT inflateValidate OF((z_streamp, int));
1897ZEXTERN unsigned long  ZEXPORT inflateCodesUsed OF ((z_streamp));
1898ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
1899ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
1900#if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(Z_SOLO)
1901ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
1902                                            const char *mode));
1903#endif
1904#if defined(STDC) || defined(Z_HAVE_STDARG_H)
1905#  ifndef Z_SOLO
1906ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1907                                                  const char *format,
1908                                                  va_list va));
1909#  endif
1910#endif
1911
1912#ifdef __cplusplus
1913}
1914#endif
1915
1916#endif /* ZLIB_H */
1917