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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2   version 1.2.8, April 28th, 2013
3 
4   Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
5 
6   This software is provided 'as-is', without any express or implied
7   warranty.  In no event will the authors be held liable for any damages
8   arising from the use of this software.
9 
10   Permission is granted to anyone to use this software for any purpose,
11   including commercial applications, and to alter it and redistribute it
12   freely, subject to the following restrictions:
13 
14   1. The origin of this software must not be misrepresented; you must not
15      claim that you wrote the original software. If you use this software
16      in a product, an acknowledgment in the product documentation would be
17      appreciated but is not required.
18   2. Altered source versions must be plainly marked as such, and must not be
19      misrepresented as being the original software.
20   3. This notice may not be removed or altered from any source distribution.
21 
22   Jean-loup Gailly        Mark Adler
23   jloup@gzip.org          madler@alumni.caltech.edu
24 
25 
26   The data format used by the zlib library is described by RFCs (Request for
27   Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
28   (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
29 */
30 
31 #ifndef ZLIB_H
32 #define ZLIB_H
33 
34 #ifdef _MSC_VER
35 #define _CRT_SECURE_NO_WARNINGS
36 #endif
37 
38 #define deflate_copyright FPDFAPI_deflate_copyright
39 #define adler32 FPDFAPI_adler32
40 #define compress2 FPDFAPI_compress2
41 #define compress FPDFAPI_compress
42 #define compressBound FPDFAPI_compressBound
43 #define get_crc_table FPDFAPI_get_crc_table
44 #define crc32 FPDFAPI_crc32
45 #define deflateInit_ FPDFAPI_deflateInit_
46 #define deflateInit2_ FPDFAPI_deflateInit2_
47 #define deflateSetDictionary FPDFAPI_deflateSetDictionary
48 #define deflateReset FPDFAPI_deflateReset
49 #define deflatePending FPDFAPI_deflatePending
50 #define deflatePrime FPDFAPI_deflatePrime
51 #define deflateParams FPDFAPI_deflateParams
52 #define deflateBound FPDFAPI_deflateBound
53 #define deflateSetHeader FPDFAPI_deflateSetHeader
54 #define deflateTune FPDFAPI_deflateTune
55 #define deflate FPDFAPI_deflate
56 #define deflateEnd FPDFAPI_deflateEnd
57 #define deflateCopy FPDFAPI_deflateCopy
58 #define inflateBackInit_ FPDFAPI_inflateBackInit_
59 #define inflateBack FPDFAPI_inflateBack
60 #define inflateBackEnd FPDFAPI_inflateBackEnd
61 #define inflateReset FPDFAPI_inflateReset
62 #define inflateInit2_ FPDFAPI_inflateInit2_
63 #define inflateInit_ FPDFAPI_inflateInit_
64 #define inflate FPDFAPI_inflate
65 #define inflateEnd FPDFAPI_inflateEnd
66 #define inflateSetDictionary FPDFAPI_inflateSetDictionary
67 #define inflateSync FPDFAPI_inflateSync
68 #define inflateSyncPoint FPDFAPI_inflateSyncPoint
69 #define inflateCopy FPDFAPI_inflateCopy
70 #define uncompress FPDFAPI_uncompress
71 #define zlibVersion FPDFAPI_zlibVersion
72 #define zlibCompileFlags FPDFAPI_zlibCompileFlags
73 #define zError FPDFAPI_zError
74 #define z_errmsg FPDFAPI_z_errmsg
75 #define zcfree FPDFAPI_zcfree
76 #define zcalloc FPDFAPI_zcalloc
77 #define inflate_fast FPDFAPI_inflate_fast
78 #define inflate_table FPDFAPI_inflate_table
79 #define inflate_copyright FPDFAPI_inflate_copyright
80 #define _length_code FPDFAPI_length_code
81 #define _tr_flush_block FPDFAPI_tr_flush_block
82 #define _dist_code FPDFAPI_dist_code
83 #define _tr_stored_block FPDFAPI_tr_stored_block
84 #define _tr_init FPDFAPI_tr_init
85 #define _tr_align FPDFAPI_tr_align
86 #define _tr_tally FPDFAPI_tr_tally
87 #define _tr_flush_bits FPDFAPI_tr_flush_bits
88 #define adler32_combine FPDFAPI_adler32_combine
89 #define inflatePrime FPDFAPI_inflatePrime
90 #define inflateGetDictionary FPDFAPI_inflateGetDictionary
91 #define inflateGetHeader FPDFAPI_inflateGetHeader
92 #define crc32_combine FPDFAPI_crc32_combine
93 #define inflateReset2 FPDFAPI_inflateReset2
94 #define inflateUndermine FPDFAPI_inflateUndermine
95 #define inflateMark FPDFAPI_inflateMark
96 #define adler32_combine64 FPDFAPI_adler32_combine64
97 #define inflateResetKeep FPDFAPI_inflateResetKeep
98 #define deflateResetKeep FPDFAPI_deflateResetKeep
99 
100 #include "zconf.h"
101 
102 /* Sunliang.Liu 20100908 sync the config to the old revision. NO_GZIP */
103 #define NO_GZIP		/* XYQ */
104 
105 #ifdef __cplusplus
106 extern "C" {
107 #endif
108 
109 #define ZLIB_VERSION "1.2.8"
110 #define ZLIB_VERNUM 0x1280
111 #define ZLIB_VER_MAJOR 1
112 #define ZLIB_VER_MINOR 2
113 #define ZLIB_VER_REVISION 8
114 #define ZLIB_VER_SUBREVISION 0
115 
116 /*
117     The 'zlib' compression library provides in-memory compression and
118   decompression functions, including integrity checks of the uncompressed data.
119   This version of the library supports only one compression method (deflation)
120   but other algorithms will be added later and will have the same stream
121   interface.
122 
123     Compression can be done in a single step if the buffers are large enough,
124   or can be done by repeated calls of the compression function.  In the latter
125   case, the application must provide more input and/or consume the output
126   (providing more output space) before each call.
127 
128     The compressed data format used by default by the in-memory functions is
129   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
130   around a deflate stream, which is itself documented in RFC 1951.
131 
132     The library also supports reading and writing files in gzip (.gz) format
133   with an interface similar to that of stdio using the functions that start
134   with "gz".  The gzip format is different from the zlib format.  gzip is a
135   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
136 
137     This library can optionally read and write gzip streams in memory as well.
138 
139     The zlib format was designed to be compact and fast for use in memory
140   and on communications channels.  The gzip format was designed for single-
141   file compression on file systems, has a larger header than zlib to maintain
142   directory information, and uses a different, slower check method than zlib.
143 
144     The library does not install any signal handler.  The decoder checks
145   the consistency of the compressed data, so the library should never crash
146   even in case of corrupted input.
147 */
148 
149 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
150 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
151 
152 struct internal_state;
153 
154 typedef struct z_stream_s {
155     z_const Bytef *next_in;     /* next input byte */
156     uInt     avail_in;  /* number of bytes available at next_in */
157     uLong    total_in;  /* total number of input bytes read so far */
158 
159     Bytef    *next_out; /* next output byte should be put there */
160     uInt     avail_out; /* remaining free space at next_out */
161     uLong    total_out; /* total number of bytes output so far */
162 
163     z_const char *msg;  /* last error message, NULL if no error */
164     struct internal_state FAR *state; /* not visible by applications */
165 
166     alloc_func zalloc;  /* used to allocate the internal state */
167     free_func  zfree;   /* used to free the internal state */
168     voidpf     opaque;  /* private data object passed to zalloc and zfree */
169 
170     int     data_type;  /* best guess about the data type: binary or text */
171     uLong   adler;      /* adler32 value of the uncompressed data */
172     uLong   reserved;   /* reserved for future use */
173 } z_stream;
174 
175 typedef z_stream FAR *z_streamp;
176 
177 /*
178      gzip header information passed to and from zlib routines.  See RFC 1952
179   for more details on the meanings of these fields.
180 */
181 typedef struct gz_header_s {
182     int     text;       /* true if compressed data believed to be text */
183     uLong   time;       /* modification time */
184     int     xflags;     /* extra flags (not used when writing a gzip file) */
185     int     os;         /* operating system */
186     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
187     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
188     uInt    extra_max;  /* space at extra (only when reading header) */
189     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
190     uInt    name_max;   /* space at name (only when reading header) */
191     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
192     uInt    comm_max;   /* space at comment (only when reading header) */
193     int     hcrc;       /* true if there was or will be a header crc */
194     int     done;       /* true when done reading gzip header (not used
195                            when writing a gzip file) */
196 } gz_header;
197 
198 typedef gz_header FAR *gz_headerp;
199 
200 /*
201      The application must update next_in and avail_in when avail_in has dropped
202    to zero.  It must update next_out and avail_out when avail_out has dropped
203    to zero.  The application must initialize zalloc, zfree and opaque before
204    calling the init function.  All other fields are set by the compression
205    library and must not be updated by the application.
206 
207      The opaque value provided by the application will be passed as the first
208    parameter for calls of zalloc and zfree.  This can be useful for custom
209    memory management.  The compression library attaches no meaning to the
210    opaque value.
211 
212      zalloc must return Z_NULL if there is not enough memory for the object.
213    If zlib is used in a multi-threaded application, zalloc and zfree must be
214    thread safe.
215 
216      On 16-bit systems, the functions zalloc and zfree must be able to allocate
217    exactly 65536 bytes, but will not be required to allocate more than this if
218    the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
219    returned by zalloc for objects of exactly 65536 bytes *must* have their
220    offset normalized to zero.  The default allocation function provided by this
221    library ensures this (see zutil.c).  To reduce memory requirements and avoid
222    any allocation of 64K objects, at the expense of compression ratio, compile
223    the library with -DMAX_WBITS=14 (see zconf.h).
224 
225      The fields total_in and total_out can be used for statistics or progress
226    reports.  After compression, total_in holds the total size of the
227    uncompressed data and may be saved for use in the decompressor (particularly
228    if the decompressor wants to decompress everything in a single step).
229 */
230 
231                         /* constants */
232 
233 #define Z_NO_FLUSH      0
234 #define Z_PARTIAL_FLUSH 1
235 #define Z_SYNC_FLUSH    2
236 #define Z_FULL_FLUSH    3
237 #define Z_FINISH        4
238 #define Z_BLOCK         5
239 #define Z_TREES         6
240 /* Allowed flush values; see deflate() and inflate() below for details */
241 
242 #define Z_OK            0
243 #define Z_STREAM_END    1
244 #define Z_NEED_DICT     2
245 #define Z_ERRNO        (-1)
246 #define Z_STREAM_ERROR (-2)
247 #define Z_DATA_ERROR   (-3)
248 #define Z_MEM_ERROR    (-4)
249 #define Z_BUF_ERROR    (-5)
250 #define Z_VERSION_ERROR (-6)
251 /* Return codes for the compression/decompression functions. Negative values
252  * are errors, positive values are used for special but normal events.
253  */
254 
255 #define Z_NO_COMPRESSION         0
256 #define Z_BEST_SPEED             1
257 #define Z_BEST_COMPRESSION       9
258 #define Z_DEFAULT_COMPRESSION  (-1)
259 /* compression levels */
260 
261 #define Z_FILTERED            1
262 #define Z_HUFFMAN_ONLY        2
263 #define Z_RLE                 3
264 #define Z_FIXED               4
265 #define Z_DEFAULT_STRATEGY    0
266 /* compression strategy; see deflateInit2() below for details */
267 
268 #define Z_BINARY   0
269 #define Z_TEXT     1
270 #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
271 #define Z_UNKNOWN  2
272 /* Possible values of the data_type field (though see inflate()) */
273 
274 #define Z_DEFLATED   8
275 /* The deflate compression method (the only one supported in this version) */
276 
277 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
278 
279 #define zlib_version zlibVersion()
280 /* for compatibility with versions < 1.0.2 */
281 
282 
283                         /* basic functions */
284 
285 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
286 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
287    If the first character differs, the library code actually used is not
288    compatible with the zlib.h header file used by the application.  This check
289    is automatically made by deflateInit and inflateInit.
290  */
291 
292 /*
293 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
294 
295      Initializes the internal stream state for compression.  The fields
296    zalloc, zfree and opaque must be initialized before by the caller.  If
297    zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
298    allocation functions.
299 
300      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
301    1 gives best speed, 9 gives best compression, 0 gives no compression at all
302    (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
303    requests a default compromise between speed and compression (currently
304    equivalent to level 6).
305 
306      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
307    memory, Z_STREAM_ERROR if level is not a valid compression level, or
308    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
309    with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
310    if there is no error message.  deflateInit does not perform any compression:
311    this will be done by deflate().
312 */
313 
314 
315 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
316 /*
317     deflate compresses as much data as possible, and stops when the input
318   buffer becomes empty or the output buffer becomes full.  It may introduce
319   some output latency (reading input without producing any output) except when
320   forced to flush.
321 
322     The detailed semantics are as follows.  deflate performs one or both of the
323   following actions:
324 
325   - Compress more input starting at next_in and update next_in and avail_in
326     accordingly.  If not all input can be processed (because there is not
327     enough room in the output buffer), next_in and avail_in are updated and
328     processing will resume at this point for the next call of deflate().
329 
330   - Provide more output starting at next_out and update next_out and avail_out
331     accordingly.  This action is forced if the parameter flush is non zero.
332     Forcing flush frequently degrades the compression ratio, so this parameter
333     should be set only when necessary (in interactive applications).  Some
334     output may be provided even if flush is not set.
335 
336     Before the call of deflate(), the application should ensure that at least
337   one of the actions is possible, by providing more input and/or consuming more
338   output, and updating avail_in or avail_out accordingly; avail_out should
339   never be zero before the call.  The application can consume the compressed
340   output when it wants, for example when the output buffer is full (avail_out
341   == 0), or after each call of deflate().  If deflate returns Z_OK and with
342   zero avail_out, it must be called again after making room in the output
343   buffer because there might be more output pending.
344 
345     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
346   decide how much data to accumulate before producing output, in order to
347   maximize compression.
348 
349     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
350   flushed to the output buffer and the output is aligned on a byte boundary, so
351   that the decompressor can get all input data available so far.  (In
352   particular avail_in is zero after the call if enough output space has been
353   provided before the call.) Flushing may degrade compression for some
354   compression algorithms and so it should be used only when necessary.  This
355   completes the current deflate block and follows it with an empty stored block
356   that is three bits plus filler bits to the next byte, followed by four bytes
357   (00 00 ff ff).
358 
359     If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
360   output buffer, but the output is not aligned to a byte boundary.  All of the
361   input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
362   This completes the current deflate block and follows it with an empty fixed
363   codes block that is 10 bits long.  This assures that enough bytes are output
364   in order for the decompressor to finish the block before the empty fixed code
365   block.
366 
367     If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
368   for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
369   seven bits of the current block are held to be written as the next byte after
370   the next deflate block is completed.  In this case, the decompressor may not
371   be provided enough bits at this point in order to complete decompression of
372   the data provided so far to the compressor.  It may need to wait for the next
373   block to be emitted.  This is for advanced applications that need to control
374   the emission of deflate blocks.
375 
376     If flush is set to Z_FULL_FLUSH, all output is flushed as with
377   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
378   restart from this point if previous compressed data has been damaged or if
379   random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
380   compression.
381 
382     If deflate returns with avail_out == 0, this function must be called again
383   with the same value of the flush parameter and more output space (updated
384   avail_out), until the flush is complete (deflate returns with non-zero
385   avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
386   avail_out is greater than six to avoid repeated flush markers due to
387   avail_out == 0 on return.
388 
389     If the parameter flush is set to Z_FINISH, pending input is processed,
390   pending output is flushed and deflate returns with Z_STREAM_END if there was
391   enough output space; if deflate returns with Z_OK, this function must be
392   called again with Z_FINISH and more output space (updated avail_out) but no
393   more input data, until it returns with Z_STREAM_END or an error.  After
394   deflate has returned Z_STREAM_END, the only possible operations on the stream
395   are deflateReset or deflateEnd.
396 
397     Z_FINISH can be used immediately after deflateInit if all the compression
398   is to be done in a single step.  In this case, avail_out must be at least the
399   value returned by deflateBound (see below).  Then deflate is guaranteed to
400   return Z_STREAM_END.  If not enough output space is provided, deflate will
401   not return Z_STREAM_END, and it must be called again as described above.
402 
403     deflate() sets strm->adler to the adler32 checksum of all input read
404   so far (that is, total_in bytes).
405 
406     deflate() may update strm->data_type if it can make a good guess about
407   the input data type (Z_BINARY or Z_TEXT).  In doubt, the data is considered
408   binary.  This field is only for information purposes and does not affect the
409   compression algorithm in any manner.
410 
411     deflate() returns Z_OK if some progress has been made (more input
412   processed or more output produced), Z_STREAM_END if all input has been
413   consumed and all output has been produced (only when flush is set to
414   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
415   if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
416   (for example avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not
417   fatal, and deflate() can be called again with more input and more output
418   space to continue compressing.
419 */
420 
421 
422 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
423 /*
424      All dynamically allocated data structures for this stream are freed.
425    This function discards any unprocessed input and does not flush any pending
426    output.
427 
428      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
429    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
430    prematurely (some input or output was discarded).  In the error case, msg
431    may be set but then points to a static string (which must not be
432    deallocated).
433 */
434 
435 
436 /*
437 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
438 
439      Initializes the internal stream state for decompression.  The fields
440    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
441    the caller.  If next_in is not Z_NULL and avail_in is large enough (the
442    exact value depends on the compression method), inflateInit determines the
443    compression method from the zlib header and allocates all data structures
444    accordingly; otherwise the allocation will be deferred to the first call of
445    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
446    use default allocation functions.
447 
448      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
449    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
450    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
451    invalid, such as a null pointer to the structure.  msg is set to null if
452    there is no error message.  inflateInit does not perform any decompression
453    apart from possibly reading the zlib header if present: actual decompression
454    will be done by inflate().  (So next_in and avail_in may be modified, but
455    next_out and avail_out are unused and unchanged.) The current implementation
456    of inflateInit() does not process any header information -- that is deferred
457    until inflate() is called.
458 */
459 
460 
461 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
462 /*
463     inflate decompresses as much data as possible, and stops when the input
464   buffer becomes empty or the output buffer becomes full.  It may introduce
465   some output latency (reading input without producing any output) except when
466   forced to flush.
467 
468   The detailed semantics are as follows.  inflate performs one or both of the
469   following actions:
470 
471   - Decompress more input starting at next_in and update next_in and avail_in
472     accordingly.  If not all input can be processed (because there is not
473     enough room in the output buffer), next_in is updated and processing will
474     resume at this point for the next call of inflate().
475 
476   - Provide more output starting at next_out and update next_out and avail_out
477     accordingly.  inflate() provides as much output as possible, until there is
478     no more input data or no more space in the output buffer (see below about
479     the flush parameter).
480 
481     Before the call of inflate(), the application should ensure that at least
482   one of the actions is possible, by providing more input and/or consuming more
483   output, and updating the next_* and avail_* values accordingly.  The
484   application can consume the uncompressed output when it wants, for example
485   when the output buffer is full (avail_out == 0), or after each call of
486   inflate().  If inflate returns Z_OK and with zero avail_out, it must be
487   called again after making room in the output buffer because there might be
488   more output pending.
489 
490     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
491   Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
492   output as possible to the output buffer.  Z_BLOCK requests that inflate()
493   stop if and when it gets to the next deflate block boundary.  When decoding
494   the zlib or gzip format, this will cause inflate() to return immediately
495   after the header and before the first block.  When doing a raw inflate,
496   inflate() will go ahead and process the first block, and will return when it
497   gets to the end of that block, or when it runs out of data.
498 
499     The Z_BLOCK option assists in appending to or combining deflate streams.
500   Also to assist in this, on return inflate() will set strm->data_type to the
501   number of unused bits in the last byte taken from strm->next_in, plus 64 if
502   inflate() is currently decoding the last block in the deflate stream, plus
503   128 if inflate() returned immediately after decoding an end-of-block code or
504   decoding the complete header up to just before the first byte of the deflate
505   stream.  The end-of-block will not be indicated until all of the uncompressed
506   data from that block has been written to strm->next_out.  The number of
507   unused bits may in general be greater than seven, except when bit 7 of
508   data_type is set, in which case the number of unused bits will be less than
509   eight.  data_type is set as noted here every time inflate() returns for all
510   flush options, and so can be used to determine the amount of currently
511   consumed input in bits.
512 
513     The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
514   end of each deflate block header is reached, before any actual data in that
515   block is decoded.  This allows the caller to determine the length of the
516   deflate block header for later use in random access within a deflate block.
517   256 is added to the value of strm->data_type when inflate() returns
518   immediately after reaching the end of the deflate block header.
519 
520     inflate() should normally be called until it returns Z_STREAM_END or an
521   error.  However if all decompression is to be performed in a single step (a
522   single call of inflate), the parameter flush should be set to Z_FINISH.  In
523   this case all pending input is processed and all pending output is flushed;
524   avail_out must be large enough to hold all of the uncompressed data for the
525   operation to complete.  (The size of the uncompressed data may have been
526   saved by the compressor for this purpose.) The use of Z_FINISH is not
527   required to perform an inflation in one step.  However it may be used to
528   inform inflate that a faster approach can be used for the single inflate()
529   call.  Z_FINISH also informs inflate to not maintain a sliding window if the
530   stream completes, which reduces inflate's memory footprint.  If the stream
531   does not complete, either because not all of the stream is provided or not
532   enough output space is provided, then a sliding window will be allocated and
533   inflate() can be called again to continue the operation as if Z_NO_FLUSH had
534   been used.
535 
536      In this implementation, inflate() always flushes as much output as
537   possible to the output buffer, and always uses the faster approach on the
538   first call.  So the effects of the flush parameter in this implementation are
539   on the return value of inflate() as noted below, when inflate() returns early
540   when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
541   memory for a sliding window when Z_FINISH is used.
542 
543      If a preset dictionary is needed after this call (see inflateSetDictionary
544   below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
545   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
546   strm->adler to the Adler-32 checksum of all output produced so far (that is,
547   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
548   below.  At the end of the stream, inflate() checks that its computed adler32
549   checksum is equal to that saved by the compressor and returns Z_STREAM_END
550   only if the checksum is correct.
551 
552     inflate() can decompress and check either zlib-wrapped or gzip-wrapped
553   deflate data.  The header type is detected automatically, if requested when
554   initializing with inflateInit2().  Any information contained in the gzip
555   header is not retained, so applications that need that information should
556   instead use raw inflate, see inflateInit2() below, or inflateBack() and
557   perform their own processing of the gzip header and trailer.  When processing
558   gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
559   producted so far.  The CRC-32 is checked against the gzip trailer.
560 
561     inflate() returns Z_OK if some progress has been made (more input processed
562   or more output produced), Z_STREAM_END if the end of the compressed data has
563   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
564   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
565   corrupted (input stream not conforming to the zlib format or incorrect check
566   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
567   next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
568   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
569   output buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
570   inflate() can be called again with more input and more output space to
571   continue decompressing.  If Z_DATA_ERROR is returned, the application may
572   then call inflateSync() to look for a good compression block if a partial
573   recovery of the data is desired.
574 */
575 
576 
577 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
578 /*
579      All dynamically allocated data structures for this stream are freed.
580    This function discards any unprocessed input and does not flush any pending
581    output.
582 
583      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
584    was inconsistent.  In the error case, msg may be set but then points to a
585    static string (which must not be deallocated).
586 */
587 
588 
589                         /* Advanced functions */
590 
591 /*
592     The following functions are needed only in some special applications.
593 */
594 
595 /*
596 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
597                                      int  level,
598                                      int  method,
599                                      int  windowBits,
600                                      int  memLevel,
601                                      int  strategy));
602 
603      This is another version of deflateInit with more compression options.  The
604    fields next_in, zalloc, zfree and opaque must be initialized before by the
605    caller.
606 
607      The method parameter is the compression method.  It must be Z_DEFLATED in
608    this version of the library.
609 
610      The windowBits parameter is the base two logarithm of the window size
611    (the size of the history buffer).  It should be in the range 8..15 for this
612    version of the library.  Larger values of this parameter result in better
613    compression at the expense of memory usage.  The default value is 15 if
614    deflateInit is used instead.
615 
616      windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
617    determines the window size.  deflate() will then generate raw deflate data
618    with no zlib header or trailer, and will not compute an adler32 check value.
619 
620      windowBits can also be greater than 15 for optional gzip encoding.  Add
621    16 to windowBits to write a simple gzip header and trailer around the
622    compressed data instead of a zlib wrapper.  The gzip header will have no
623    file name, no extra data, no comment, no modification time (set to zero), no
624    header crc, and the operating system will be set to 255 (unknown).  If a
625    gzip stream is being written, strm->adler is a crc32 instead of an adler32.
626 
627      The memLevel parameter specifies how much memory should be allocated
628    for the internal compression state.  memLevel=1 uses minimum memory but is
629    slow and reduces compression ratio; memLevel=9 uses maximum memory for
630    optimal speed.  The default value is 8.  See zconf.h for total memory usage
631    as a function of windowBits and memLevel.
632 
633      The strategy parameter is used to tune the compression algorithm.  Use the
634    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
635    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
636    string match), or Z_RLE to limit match distances to one (run-length
637    encoding).  Filtered data consists mostly of small values with a somewhat
638    random distribution.  In this case, the compression algorithm is tuned to
639    compress them better.  The effect of Z_FILTERED is to force more Huffman
640    coding and less string matching; it is somewhat intermediate between
641    Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
642    fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
643    strategy parameter only affects the compression ratio but not the
644    correctness of the compressed output even if it is not set appropriately.
645    Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
646    decoder for special applications.
647 
648      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
649    memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
650    method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
651    incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
652    set to null if there is no error message.  deflateInit2 does not perform any
653    compression: this will be done by deflate().
654 */
655 
656 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
657                                              const Bytef *dictionary,
658                                              uInt  dictLength));
659 /*
660      Initializes the compression dictionary from the given byte sequence
661    without producing any compressed output.  When using the zlib format, this
662    function must be called immediately after deflateInit, deflateInit2 or
663    deflateReset, and before any call of deflate.  When doing raw deflate, this
664    function must be called either before any call of deflate, or immediately
665    after the completion of a deflate block, i.e. after all input has been
666    consumed and all output has been delivered when using any of the flush
667    options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
668    compressor and decompressor must use exactly the same dictionary (see
669    inflateSetDictionary).
670 
671      The dictionary should consist of strings (byte sequences) that are likely
672    to be encountered later in the data to be compressed, with the most commonly
673    used strings preferably put towards the end of the dictionary.  Using a
674    dictionary is most useful when the data to be compressed is short and can be
675    predicted with good accuracy; the data can then be compressed better than
676    with the default empty dictionary.
677 
678      Depending on the size of the compression data structures selected by
679    deflateInit or deflateInit2, a part of the dictionary may in effect be
680    discarded, for example if the dictionary is larger than the window size
681    provided in deflateInit or deflateInit2.  Thus the strings most likely to be
682    useful should be put at the end of the dictionary, not at the front.  In
683    addition, the current implementation of deflate will use at most the window
684    size minus 262 bytes of the provided dictionary.
685 
686      Upon return of this function, strm->adler is set to the adler32 value
687    of the dictionary; the decompressor may later use this value to determine
688    which dictionary has been used by the compressor.  (The adler32 value
689    applies to the whole dictionary even if only a subset of the dictionary is
690    actually used by the compressor.) If a raw deflate was requested, then the
691    adler32 value is not computed and strm->adler is not set.
692 
693      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
694    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
695    inconsistent (for example if deflate has already been called for this stream
696    or if not at a block boundary for raw deflate).  deflateSetDictionary does
697    not perform any compression: this will be done by deflate().
698 */
699 
700 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
701                                     z_streamp source));
702 /*
703      Sets the destination stream as a complete copy of the source stream.
704 
705      This function can be useful when several compression strategies will be
706    tried, for example when there are several ways of pre-processing the input
707    data with a filter.  The streams that will be discarded should then be freed
708    by calling deflateEnd.  Note that deflateCopy duplicates the internal
709    compression state which can be quite large, so this strategy is slow and can
710    consume lots of memory.
711 
712      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
713    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
714    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
715    destination.
716 */
717 
718 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
719 /*
720      This function is equivalent to deflateEnd followed by deflateInit,
721    but does not free and reallocate all the internal compression state.  The
722    stream will keep the same compression level and any other attributes that
723    may have been set by deflateInit2.
724 
725      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
726    stream state was inconsistent (such as zalloc or state being Z_NULL).
727 */
728 
729 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
730                                       int level,
731                                       int strategy));
732 /*
733      Dynamically update the compression level and compression strategy.  The
734    interpretation of level and strategy is as in deflateInit2.  This can be
735    used to switch between compression and straight copy of the input data, or
736    to switch to a different kind of input data requiring a different strategy.
737    If the compression level is changed, the input available so far is
738    compressed with the old level (and may be flushed); the new level will take
739    effect only at the next call of deflate().
740 
741      Before the call of deflateParams, the stream state must be set as for
742    a call of deflate(), since the currently available input may have to be
743    compressed and flushed.  In particular, strm->avail_out must be non-zero.
744 
745      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
746    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
747    strm->avail_out was zero.
748 */
749 
750 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
751                                     int good_length,
752                                     int max_lazy,
753                                     int nice_length,
754                                     int max_chain));
755 /*
756      Fine tune deflate's internal compression parameters.  This should only be
757    used by someone who understands the algorithm used by zlib's deflate for
758    searching for the best matching string, and even then only by the most
759    fanatic optimizer trying to squeeze out the last compressed bit for their
760    specific input data.  Read the deflate.c source code for the meaning of the
761    max_lazy, good_length, nice_length, and max_chain parameters.
762 
763      deflateTune() can be called after deflateInit() or deflateInit2(), and
764    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
765  */
766 
767 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
768                                        uLong sourceLen));
769 /*
770      deflateBound() returns an upper bound on the compressed size after
771    deflation of sourceLen bytes.  It must be called after deflateInit() or
772    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
773    to allocate an output buffer for deflation in a single pass, and so would be
774    called before deflate().  If that first deflate() call is provided the
775    sourceLen input bytes, an output buffer allocated to the size returned by
776    deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
777    to return Z_STREAM_END.  Note that it is possible for the compressed size to
778    be larger than the value returned by deflateBound() if flush options other
779    than Z_FINISH or Z_NO_FLUSH are used.
780 */
781 
782 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
783                                        unsigned *pending,
784                                        int *bits));
785 /*
786      deflatePending() returns the number of bytes and bits of output that have
787    been generated, but not yet provided in the available output.  The bytes not
788    provided would be due to the available output space having being consumed.
789    The number of bits of output not provided are between 0 and 7, where they
790    await more bits to join them in order to fill out a full byte.  If pending
791    or bits are Z_NULL, then those values are not set.
792 
793      deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
794    stream state was inconsistent.
795  */
796 
797 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
798                                      int bits,
799                                      int value));
800 /*
801      deflatePrime() inserts bits in the deflate output stream.  The intent
802    is that this function is used to start off the deflate output with the bits
803    leftover from a previous deflate stream when appending to it.  As such, this
804    function can only be used for raw deflate, and must be used before the first
805    deflate() call after a deflateInit2() or deflateReset().  bits must be less
806    than or equal to 16, and that many of the least significant bits of value
807    will be inserted in the output.
808 
809      deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
810    room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
811    source stream state was inconsistent.
812 */
813 
814 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
815                                          gz_headerp head));
816 /*
817      deflateSetHeader() provides gzip header information for when a gzip
818    stream is requested by deflateInit2().  deflateSetHeader() may be called
819    after deflateInit2() or deflateReset() and before the first call of
820    deflate().  The text, time, os, extra field, name, and comment information
821    in the provided gz_header structure are written to the gzip header (xflag is
822    ignored -- the extra flags are set according to the compression level).  The
823    caller must assure that, if not Z_NULL, name and comment are terminated with
824    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
825    available there.  If hcrc is true, a gzip header crc is included.  Note that
826    the current versions of the command-line version of gzip (up through version
827    1.3.x) do not support header crc's, and will report that it is a "multi-part
828    gzip file" and give up.
829 
830      If deflateSetHeader is not used, the default gzip header has text false,
831    the time set to zero, and os set to 255, with no extra, name, or comment
832    fields.  The gzip header is returned to the default state by deflateReset().
833 
834      deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
835    stream state was inconsistent.
836 */
837 
838 /*
839 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
840                                      int  windowBits));
841 
842      This is another version of inflateInit with an extra parameter.  The
843    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
844    before by the caller.
845 
846      The windowBits parameter is the base two logarithm of the maximum window
847    size (the size of the history buffer).  It should be in the range 8..15 for
848    this version of the library.  The default value is 15 if inflateInit is used
849    instead.  windowBits must be greater than or equal to the windowBits value
850    provided to deflateInit2() while compressing, or it must be equal to 15 if
851    deflateInit2() was not used.  If a compressed stream with a larger window
852    size is given as input, inflate() will return with the error code
853    Z_DATA_ERROR instead of trying to allocate a larger window.
854 
855      windowBits can also be zero to request that inflate use the window size in
856    the zlib header of the compressed stream.
857 
858      windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
859    determines the window size.  inflate() will then process raw deflate data,
860    not looking for a zlib or gzip header, not generating a check value, and not
861    looking for any check values for comparison at the end of the stream.  This
862    is for use with other formats that use the deflate compressed data format
863    such as zip.  Those formats provide their own check values.  If a custom
864    format is developed using the raw deflate format for compressed data, it is
865    recommended that a check value such as an adler32 or a crc32 be applied to
866    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
867    most applications, the zlib format should be used as is.  Note that comments
868    above on the use in deflateInit2() applies to the magnitude of windowBits.
869 
870      windowBits can also be greater than 15 for optional gzip decoding.  Add
871    32 to windowBits to enable zlib and gzip decoding with automatic header
872    detection, or add 16 to decode only the gzip format (the zlib format will
873    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
874    crc32 instead of an adler32.
875 
876      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
877    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
878    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
879    invalid, such as a null pointer to the structure.  msg is set to null if
880    there is no error message.  inflateInit2 does not perform any decompression
881    apart from possibly reading the zlib header if present: actual decompression
882    will be done by inflate().  (So next_in and avail_in may be modified, but
883    next_out and avail_out are unused and unchanged.) The current implementation
884    of inflateInit2() does not process any header information -- that is
885    deferred until inflate() is called.
886 */
887 
888 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
889                                              const Bytef *dictionary,
890                                              uInt  dictLength));
891 /*
892      Initializes the decompression dictionary from the given uncompressed byte
893    sequence.  This function must be called immediately after a call of inflate,
894    if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
895    can be determined from the adler32 value returned by that call of inflate.
896    The compressor and decompressor must use exactly the same dictionary (see
897    deflateSetDictionary).  For raw inflate, this function can be called at any
898    time to set the dictionary.  If the provided dictionary is smaller than the
899    window and there is already data in the window, then the provided dictionary
900    will amend what's there.  The application must insure that the dictionary
901    that was used for compression is provided.
902 
903      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
904    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
905    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
906    expected one (incorrect adler32 value).  inflateSetDictionary does not
907    perform any decompression: this will be done by subsequent calls of
908    inflate().
909 */
910 
911 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
912                                              Bytef *dictionary,
913                                              uInt  *dictLength));
914 /*
915      Returns the sliding dictionary being maintained by inflate.  dictLength is
916    set to the number of bytes in the dictionary, and that many bytes are copied
917    to dictionary.  dictionary must have enough space, where 32768 bytes is
918    always enough.  If inflateGetDictionary() is called with dictionary equal to
919    Z_NULL, then only the dictionary length is returned, and nothing is copied.
920    Similary, if dictLength is Z_NULL, then it is not set.
921 
922      inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
923    stream state is inconsistent.
924 */
925 
926 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
927 /*
928      Skips invalid compressed data until a possible full flush point (see above
929    for the description of deflate with Z_FULL_FLUSH) can be found, or until all
930    available input is skipped.  No output is provided.
931 
932      inflateSync searches for a 00 00 FF FF pattern in the compressed data.
933    All full flush points have this pattern, but not all occurrences of this
934    pattern are full flush points.
935 
936      inflateSync returns Z_OK if a possible full flush point has been found,
937    Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
938    has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
939    In the success case, the application may save the current current value of
940    total_in which indicates where valid compressed data was found.  In the
941    error case, the application may repeatedly call inflateSync, providing more
942    input each time, until success or end of the input data.
943 */
944 
945 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
946                                     z_streamp source));
947 /*
948      Sets the destination stream as a complete copy of the source stream.
949 
950      This function can be useful when randomly accessing a large stream.  The
951    first pass through the stream can periodically record the inflate state,
952    allowing restarting inflate at those points when randomly accessing the
953    stream.
954 
955      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
956    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
957    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
958    destination.
959 */
960 
961 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
962 /*
963      This function is equivalent to inflateEnd followed by inflateInit,
964    but does not free and reallocate all the internal decompression state.  The
965    stream will keep attributes that may have been set by inflateInit2.
966 
967      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
968    stream state was inconsistent (such as zalloc or state being Z_NULL).
969 */
970 
971 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
972                                       int windowBits));
973 /*
974      This function is the same as inflateReset, but it also permits changing
975    the wrap and window size requests.  The windowBits parameter is interpreted
976    the same as it is for inflateInit2.
977 
978      inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
979    stream state was inconsistent (such as zalloc or state being Z_NULL), or if
980    the windowBits parameter is invalid.
981 */
982 
983 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
984                                      int bits,
985                                      int value));
986 /*
987      This function inserts bits in the inflate input stream.  The intent is
988    that this function is used to start inflating at a bit position in the
989    middle of a byte.  The provided bits will be used before any bytes are used
990    from next_in.  This function should only be used with raw inflate, and
991    should be used before the first inflate() call after inflateInit2() or
992    inflateReset().  bits must be less than or equal to 16, and that many of the
993    least significant bits of value will be inserted in the input.
994 
995      If bits is negative, then the input stream bit buffer is emptied.  Then
996    inflatePrime() can be called again to put bits in the buffer.  This is used
997    to clear out bits leftover after feeding inflate a block description prior
998    to feeding inflate codes.
999 
1000      inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1001    stream state was inconsistent.
1002 */
1003 
1004 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
1005 /*
1006      This function returns two values, one in the lower 16 bits of the return
1007    value, and the other in the remaining upper bits, obtained by shifting the
1008    return value down 16 bits.  If the upper value is -1 and the lower value is
1009    zero, then inflate() is currently decoding information outside of a block.
1010    If the upper value is -1 and the lower value is non-zero, then inflate is in
1011    the middle of a stored block, with the lower value equaling the number of
1012    bytes from the input remaining to copy.  If the upper value is not -1, then
1013    it is the number of bits back from the current bit position in the input of
1014    the code (literal or length/distance pair) currently being processed.  In
1015    that case the lower value is the number of bytes already emitted for that
1016    code.
1017 
1018      A code is being processed if inflate is waiting for more input to complete
1019    decoding of the code, or if it has completed decoding but is waiting for
1020    more output space to write the literal or match data.
1021 
1022      inflateMark() is used to mark locations in the input data for random
1023    access, which may be at bit positions, and to note those cases where the
1024    output of a code may span boundaries of random access blocks.  The current
1025    location in the input stream can be determined from avail_in and data_type
1026    as noted in the description for the Z_BLOCK flush parameter for inflate.
1027 
1028      inflateMark returns the value noted above or -1 << 16 if the provided
1029    source stream state was inconsistent.
1030 */
1031 
1032 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1033                                          gz_headerp head));
1034 /*
1035      inflateGetHeader() requests that gzip header information be stored in the
1036    provided gz_header structure.  inflateGetHeader() may be called after
1037    inflateInit2() or inflateReset(), and before the first call of inflate().
1038    As inflate() processes the gzip stream, head->done is zero until the header
1039    is completed, at which time head->done is set to one.  If a zlib stream is
1040    being decoded, then head->done is set to -1 to indicate that there will be
1041    no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
1042    used to force inflate() to return immediately after header processing is
1043    complete and before any actual data is decompressed.
1044 
1045      The text, time, xflags, and os fields are filled in with the gzip header
1046    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
1047    was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1048    contains the maximum number of bytes to write to extra.  Once done is true,
1049    extra_len contains the actual extra field length, and extra contains the
1050    extra field, or that field truncated if extra_max is less than extra_len.
1051    If name is not Z_NULL, then up to name_max characters are written there,
1052    terminated with a zero unless the length is greater than name_max.  If
1053    comment is not Z_NULL, then up to comm_max characters are written there,
1054    terminated with a zero unless the length is greater than comm_max.  When any
1055    of extra, name, or comment are not Z_NULL and the respective field is not
1056    present in the header, then that field is set to Z_NULL to signal its
1057    absence.  This allows the use of deflateSetHeader() with the returned
1058    structure to duplicate the header.  However if those fields are set to
1059    allocated memory, then the application will need to save those pointers
1060    elsewhere so that they can be eventually freed.
1061 
1062      If inflateGetHeader is not used, then the header information is simply
1063    discarded.  The header is always checked for validity, including the header
1064    CRC if present.  inflateReset() will reset the process to discard the header
1065    information.  The application would need to call inflateGetHeader() again to
1066    retrieve the header from the next gzip stream.
1067 
1068      inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1069    stream state was inconsistent.
1070 */
1071 
1072 /*
1073 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1074                                         unsigned char FAR *window));
1075 
1076      Initialize the internal stream state for decompression using inflateBack()
1077    calls.  The fields zalloc, zfree and opaque in strm must be initialized
1078    before the call.  If zalloc and zfree are Z_NULL, then the default library-
1079    derived memory allocation routines are used.  windowBits is the base two
1080    logarithm of the window size, in the range 8..15.  window is a caller
1081    supplied buffer of that size.  Except for special applications where it is
1082    assured that deflate was used with small window sizes, windowBits must be 15
1083    and a 32K byte window must be supplied to be able to decompress general
1084    deflate streams.
1085 
1086      See inflateBack() for the usage of these routines.
1087 
1088      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1089    the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1090    allocated, or Z_VERSION_ERROR if the version of the library does not match
1091    the version of the header file.
1092 */
1093 
1094 typedef unsigned (*in_func) OF((void FAR *,
1095                                 z_const unsigned char FAR * FAR *));
1096 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1097 
1098 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1099                                     in_func in, void FAR *in_desc,
1100                                     out_func out, void FAR *out_desc));
1101 /*
1102      inflateBack() does a raw inflate with a single call using a call-back
1103    interface for input and output.  This is potentially more efficient than
1104    inflate() for file i/o applications, in that it avoids copying between the
1105    output and the sliding window by simply making the window itself the output
1106    buffer.  inflate() can be faster on modern CPUs when used with large
1107    buffers.  inflateBack() trusts the application to not change the output
1108    buffer passed by the output function, at least until inflateBack() returns.
1109 
1110      inflateBackInit() must be called first to allocate the internal state
1111    and to initialize the state with the user-provided window buffer.
1112    inflateBack() may then be used multiple times to inflate a complete, raw
1113    deflate stream with each call.  inflateBackEnd() is then called to free the
1114    allocated state.
1115 
1116      A raw deflate stream is one with no zlib or gzip header or trailer.
1117    This routine would normally be used in a utility that reads zip or gzip
1118    files and writes out uncompressed files.  The utility would decode the
1119    header and process the trailer on its own, hence this routine expects only
1120    the raw deflate stream to decompress.  This is different from the normal
1121    behavior of inflate(), which expects either a zlib or gzip header and
1122    trailer around the deflate stream.
1123 
1124      inflateBack() uses two subroutines supplied by the caller that are then
1125    called by inflateBack() for input and output.  inflateBack() calls those
1126    routines until it reads a complete deflate stream and writes out all of the
1127    uncompressed data, or until it encounters an error.  The function's
1128    parameters and return types are defined above in the in_func and out_func
1129    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
1130    number of bytes of provided input, and a pointer to that input in buf.  If
1131    there is no input available, in() must return zero--buf is ignored in that
1132    case--and inflateBack() will return a buffer error.  inflateBack() will call
1133    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
1134    should return zero on success, or non-zero on failure.  If out() returns
1135    non-zero, inflateBack() will return with an error.  Neither in() nor out()
1136    are permitted to change the contents of the window provided to
1137    inflateBackInit(), which is also the buffer that out() uses to write from.
1138    The length written by out() will be at most the window size.  Any non-zero
1139    amount of input may be provided by in().
1140 
1141      For convenience, inflateBack() can be provided input on the first call by
1142    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
1143    in() will be called.  Therefore strm->next_in must be initialized before
1144    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
1145    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
1146    must also be initialized, and then if strm->avail_in is not zero, input will
1147    initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
1148 
1149      The in_desc and out_desc parameters of inflateBack() is passed as the
1150    first parameter of in() and out() respectively when they are called.  These
1151    descriptors can be optionally used to pass any information that the caller-
1152    supplied in() and out() functions need to do their job.
1153 
1154      On return, inflateBack() will set strm->next_in and strm->avail_in to
1155    pass back any unused input that was provided by the last in() call.  The
1156    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1157    if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1158    in the deflate stream (in which case strm->msg is set to indicate the nature
1159    of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1160    In the case of Z_BUF_ERROR, an input or output error can be distinguished
1161    using strm->next_in which will be Z_NULL only if in() returned an error.  If
1162    strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1163    non-zero.  (in() will always be called before out(), so strm->next_in is
1164    assured to be defined if out() returns non-zero.) Note that inflateBack()
1165    cannot return Z_OK.
1166 */
1167 
1168 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1169 /*
1170      All memory allocated by inflateBackInit() is freed.
1171 
1172      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1173    state was inconsistent.
1174 */
1175 
1176 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1177 /* Return flags indicating compile-time options.
1178 
1179     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1180      1.0: size of uInt
1181      3.2: size of uLong
1182      5.4: size of voidpf (pointer)
1183      7.6: size of z_off_t
1184 
1185     Compiler, assembler, and debug options:
1186      8: DEBUG
1187      9: ASMV or ASMINF -- use ASM code
1188      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1189      11: 0 (reserved)
1190 
1191     One-time table building (smaller code, but not thread-safe if true):
1192      12: BUILDFIXED -- build static block decoding tables when needed
1193      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1194      14,15: 0 (reserved)
1195 
1196     Library content (indicates missing functionality):
1197      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1198                           deflate code when not needed)
1199      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1200                     and decode gzip streams (to avoid linking crc code)
1201      18-19: 0 (reserved)
1202 
1203     Operation variations (changes in library functionality):
1204      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1205      21: FASTEST -- deflate algorithm with only one, lowest compression level
1206      22,23: 0 (reserved)
1207 
1208     The sprintf variant used by gzprintf (zero is best):
1209      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1210      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1211      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1212 
1213     Remainder:
1214      27-31: 0 (reserved)
1215  */
1216 
1217 #ifndef Z_SOLO
1218 
1219                         /* utility functions */
1220 
1221 /*
1222      The following utility functions are implemented on top of the basic
1223    stream-oriented functions.  To simplify the interface, some default options
1224    are assumed (compression level and memory usage, standard memory allocation
1225    functions).  The source code of these utility functions can be modified if
1226    you need special options.
1227 */
1228 
1229 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
1230                                  const Bytef *source, uLong sourceLen));
1231 /*
1232      Compresses the source buffer into the destination buffer.  sourceLen is
1233    the byte length of the source buffer.  Upon entry, destLen is the total size
1234    of the destination buffer, which must be at least the value returned by
1235    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1236    compressed buffer.
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 
1243 ZEXTERN 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 buffer.
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 
1259 ZEXTERN 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 
1266 ZEXTERN 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 buffer.
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 
1284                         /* gzip file access functions */
1285 
1286 /*
1287      This library supports reading and writing files in gzip (.gz) format with
1288    an interface similar to that of stdio, using the functions that start with
1289    "gz".  The gzip format is different from the zlib format.  gzip is a gzip
1290    wrapper, documented in RFC 1952, wrapped around a deflate stream.
1291 */
1292 
1293 typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
1294 
1295 /*
1296 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1297 
1298      Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
1299    in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1300    a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1301    compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1302    for fixed code compression as in "wb9F".  (See the description of
1303    deflateInit2 for more information about the strategy parameter.)  'T' will
1304    request transparent writing or appending with no compression and not using
1305    the gzip format.
1306 
1307      "a" can be used instead of "w" to request that the gzip stream that will
1308    be written be appended to the file.  "+" will result in an error, since
1309    reading and writing to the same gzip file is not supported.  The addition of
1310    "x" when writing will create the file exclusively, which fails if the file
1311    already exists.  On systems that support it, the addition of "e" when
1312    reading or writing will set the flag to close the file on an execve() call.
1313 
1314      These functions, as well as gzip, will read and decode a sequence of gzip
1315    streams in a file.  The append function of gzopen() can be used to create
1316    such a file.  (Also see gzflush() for another way to do this.)  When
1317    appending, gzopen does not test whether the file begins with a gzip stream,
1318    nor does it look for the end of the gzip streams to begin appending.  gzopen
1319    will simply append a gzip stream to the existing file.
1320 
1321      gzopen can be used to read a file which is not in gzip format; in this
1322    case gzread will directly read from the file without decompression.  When
1323    reading, this will be detected automatically by looking for the magic two-
1324    byte gzip header.
1325 
1326      gzopen returns NULL if the file could not be opened, if there was
1327    insufficient memory to allocate the gzFile state, or if an invalid mode was
1328    specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1329    errno can be checked to determine if the reason gzopen failed was that the
1330    file could not be opened.
1331 */
1332 
1333 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1334 /*
1335      gzdopen associates a gzFile with the file descriptor fd.  File descriptors
1336    are obtained from calls like open, dup, creat, pipe or fileno (if the file
1337    has been previously opened with fopen).  The mode parameter is as in gzopen.
1338 
1339      The next call of gzclose on the returned gzFile will also close the file
1340    descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1341    fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1342    mode);.  The duplicated descriptor should be saved to avoid a leak, since
1343    gzdopen does not close fd if it fails.  If you are using fileno() to get the
1344    file descriptor from a FILE *, then you will have to use dup() to avoid
1345    double-close()ing the file descriptor.  Both gzclose() and fclose() will
1346    close the associated file descriptor, so they need to have different file
1347    descriptors.
1348 
1349      gzdopen returns NULL if there was insufficient memory to allocate the
1350    gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1351    provided, or '+' was provided), or if fd is -1.  The file descriptor is not
1352    used until the next gz* read, write, seek, or close operation, so gzdopen
1353    will not detect if fd is invalid (unless fd is -1).
1354 */
1355 
1356 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1357 /*
1358      Set the internal buffer size used by this library's functions.  The
1359    default buffer size is 8192 bytes.  This function must be called after
1360    gzopen() or gzdopen(), and before any other calls that read or write the
1361    file.  The buffer memory allocation is always deferred to the first read or
1362    write.  Two buffers are allocated, either both of the specified size when
1363    writing, or one of the specified size and the other twice that size when
1364    reading.  A larger buffer size of, for example, 64K or 128K bytes will
1365    noticeably increase the speed of decompression (reading).
1366 
1367      The new buffer size also affects the maximum length for gzprintf().
1368 
1369      gzbuffer() returns 0 on success, or -1 on failure, such as being called
1370    too late.
1371 */
1372 
1373 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1374 /*
1375      Dynamically update the compression level or strategy.  See the description
1376    of deflateInit2 for the meaning of these parameters.
1377 
1378      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1379    opened for writing.
1380 */
1381 
1382 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1383 /*
1384      Reads the given number of uncompressed bytes from the compressed file.  If
1385    the input file is not in gzip format, gzread copies the given number of
1386    bytes into the buffer directly from the file.
1387 
1388      After reaching the end of a gzip stream in the input, gzread will continue
1389    to read, looking for another gzip stream.  Any number of gzip streams may be
1390    concatenated in the input file, and will all be decompressed by gzread().
1391    If something other than a gzip stream is encountered after a gzip stream,
1392    that remaining trailing garbage is ignored (and no error is returned).
1393 
1394      gzread can be used to read a gzip file that is being concurrently written.
1395    Upon reaching the end of the input, gzread will return with the available
1396    data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1397    gzclearerr can be used to clear the end of file indicator in order to permit
1398    gzread to be tried again.  Z_OK indicates that a gzip stream was completed
1399    on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
1400    middle of a gzip stream.  Note that gzread does not return -1 in the event
1401    of an incomplete gzip stream.  This error is deferred until gzclose(), which
1402    will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1403    stream.  Alternatively, gzerror can be used before gzclose to detect this
1404    case.
1405 
1406      gzread returns the number of uncompressed bytes actually read, less than
1407    len for end of file, or -1 for error.
1408 */
1409 
1410 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1411                                 voidpc buf, unsigned len));
1412 /*
1413      Writes the given number of uncompressed bytes into the compressed file.
1414    gzwrite returns the number of uncompressed bytes written or 0 in case of
1415    error.
1416 */
1417 
1418 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1419 /*
1420      Converts, formats, and writes the arguments to the compressed file under
1421    control of the format string, as in fprintf.  gzprintf returns the number of
1422    uncompressed bytes actually written, or 0 in case of error.  The number of
1423    uncompressed bytes written is limited to 8191, or one less than the buffer
1424    size given to gzbuffer().  The caller should assure that this limit is not
1425    exceeded.  If it is exceeded, then gzprintf() will return an error (0) with
1426    nothing written.  In this case, there may also be a buffer overflow with
1427    unpredictable consequences, which is possible only if zlib was compiled with
1428    the insecure functions sprintf() or vsprintf() because the secure snprintf()
1429    or vsnprintf() functions were not available.  This can be determined using
1430    zlibCompileFlags().
1431 */
1432 
1433 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1434 /*
1435      Writes the given null-terminated string to the compressed file, excluding
1436    the terminating null character.
1437 
1438      gzputs returns the number of characters written, or -1 in case of error.
1439 */
1440 
1441 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1442 /*
1443      Reads bytes from the compressed file until len-1 characters are read, or a
1444    newline character is read and transferred to buf, or an end-of-file
1445    condition is encountered.  If any characters are read or if len == 1, the
1446    string is terminated with a null character.  If no characters are read due
1447    to an end-of-file or len < 1, then the buffer is left untouched.
1448 
1449      gzgets returns buf which is a null-terminated string, or it returns NULL
1450    for end-of-file or in case of error.  If there was an error, the contents at
1451    buf are indeterminate.
1452 */
1453 
1454 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1455 /*
1456      Writes c, converted to an unsigned char, into the compressed file.  gzputc
1457    returns the value that was written, or -1 in case of error.
1458 */
1459 
1460 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1461 /*
1462      Reads one byte from the compressed file.  gzgetc returns this byte or -1
1463    in case of end of file or error.  This is implemented as a macro for speed.
1464    As such, it does not do all of the checking the other functions do.  I.e.
1465    it does not check to see if file is NULL, nor whether the structure file
1466    points to has been clobbered or not.
1467 */
1468 
1469 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1470 /*
1471      Push one character back onto the stream to be read as the first character
1472    on the next read.  At least one character of push-back is allowed.
1473    gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
1474    fail if c is -1, and may fail if a character has been pushed but not read
1475    yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
1476    output buffer size of pushed characters is allowed.  (See gzbuffer above.)
1477    The pushed character will be discarded if the stream is repositioned with
1478    gzseek() or gzrewind().
1479 */
1480 
1481 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1482 /*
1483      Flushes all pending output into the compressed file.  The parameter flush
1484    is as in the deflate() function.  The return value is the zlib error number
1485    (see function gzerror below).  gzflush is only permitted when writing.
1486 
1487      If the flush parameter is Z_FINISH, the remaining data is written and the
1488    gzip stream is completed in the output.  If gzwrite() is called again, a new
1489    gzip stream will be started in the output.  gzread() is able to read such
1490    concatented gzip streams.
1491 
1492      gzflush should be called only when strictly necessary because it will
1493    degrade compression if called too often.
1494 */
1495 
1496 /*
1497 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1498                                    z_off_t offset, int whence));
1499 
1500      Sets the starting position for the next gzread or gzwrite on the given
1501    compressed file.  The offset represents a number of bytes in the
1502    uncompressed data stream.  The whence parameter is defined as in lseek(2);
1503    the value SEEK_END is not supported.
1504 
1505      If the file is opened for reading, this function is emulated but can be
1506    extremely slow.  If the file is opened for writing, only forward seeks are
1507    supported; gzseek then compresses a sequence of zeroes up to the new
1508    starting position.
1509 
1510      gzseek returns the resulting offset location as measured in bytes from
1511    the beginning of the uncompressed stream, or -1 in case of error, in
1512    particular if the file is opened for writing and the new starting position
1513    would be before the current position.
1514 */
1515 
1516 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
1517 /*
1518      Rewinds the given file. This function is supported only for reading.
1519 
1520      gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1521 */
1522 
1523 /*
1524 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
1525 
1526      Returns the starting position for the next gzread or gzwrite on the given
1527    compressed file.  This position represents a number of bytes in the
1528    uncompressed data stream, and is zero when starting, even if appending or
1529    reading a gzip stream from the middle of a file using gzdopen().
1530 
1531      gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1532 */
1533 
1534 /*
1535 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1536 
1537      Returns the current offset in the file being read or written.  This offset
1538    includes the count of bytes that precede the gzip stream, for example when
1539    appending or when using gzdopen() for reading.  When reading, the offset
1540    does not include as yet unused buffered input.  This information can be used
1541    for a progress indicator.  On error, gzoffset() returns -1.
1542 */
1543 
1544 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1545 /*
1546      Returns true (1) if the end-of-file indicator has been set while reading,
1547    false (0) otherwise.  Note that the end-of-file indicator is set only if the
1548    read tried to go past the end of the input, but came up short.  Therefore,
1549    just like feof(), gzeof() may return false even if there is no more data to
1550    read, in the event that the last read request was for the exact number of
1551    bytes remaining in the input file.  This will happen if the input file size
1552    is an exact multiple of the buffer size.
1553 
1554      If gzeof() returns true, then the read functions will return no more data,
1555    unless the end-of-file indicator is reset by gzclearerr() and the input file
1556    has grown since the previous end of file was detected.
1557 */
1558 
1559 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1560 /*
1561      Returns true (1) if file is being copied directly while reading, or false
1562    (0) if file is a gzip stream being decompressed.
1563 
1564      If the input file is empty, gzdirect() will return true, since the input
1565    does not contain a gzip stream.
1566 
1567      If gzdirect() is used immediately after gzopen() or gzdopen() it will
1568    cause buffers to be allocated to allow reading the file to determine if it
1569    is a gzip file.  Therefore if gzbuffer() is used, it should be called before
1570    gzdirect().
1571 
1572      When writing, gzdirect() returns true (1) if transparent writing was
1573    requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
1574    gzdirect() is not needed when writing.  Transparent writing must be
1575    explicitly requested, so the application already knows the answer.  When
1576    linking statically, using gzdirect() will include all of the zlib code for
1577    gzip file reading and decompression, which may not be desired.)
1578 */
1579 
1580 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
1581 /*
1582      Flushes all pending output if necessary, closes the compressed file and
1583    deallocates the (de)compression state.  Note that once file is closed, you
1584    cannot call gzerror with file, since its structures have been deallocated.
1585    gzclose must not be called more than once on the same file, just as free
1586    must not be called more than once on the same allocation.
1587 
1588      gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1589    file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1590    last read ended in the middle of a gzip stream, or Z_OK on success.
1591 */
1592 
1593 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1594 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1595 /*
1596      Same as gzclose(), but gzclose_r() is only for use when reading, and
1597    gzclose_w() is only for use when writing or appending.  The advantage to
1598    using these instead of gzclose() is that they avoid linking in zlib
1599    compression or decompression code that is not used when only reading or only
1600    writing respectively.  If gzclose() is used, then both compression and
1601    decompression code will be included the application when linking to a static
1602    zlib library.
1603 */
1604 
1605 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1606 /*
1607      Returns the error message for the last error which occurred on the given
1608    compressed file.  errnum is set to zlib error number.  If an error occurred
1609    in the file system and not in the compression library, errnum is set to
1610    Z_ERRNO and the application may consult errno to get the exact error code.
1611 
1612      The application must not modify the returned string.  Future calls to
1613    this function may invalidate the previously returned string.  If file is
1614    closed, then the string previously returned by gzerror will no longer be
1615    available.
1616 
1617      gzerror() should be used to distinguish errors from end-of-file for those
1618    functions above that do not distinguish those cases in their return values.
1619 */
1620 
1621 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1622 /*
1623      Clears the error and end-of-file flags for file.  This is analogous to the
1624    clearerr() function in stdio.  This is useful for continuing to read a gzip
1625    file that is being written concurrently.
1626 */
1627 
1628 #endif /* !Z_SOLO */
1629 
1630                         /* checksum functions */
1631 
1632 /*
1633      These functions are not related to compression but are exported
1634    anyway because they might be useful in applications using the compression
1635    library.
1636 */
1637 
1638 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1639 /*
1640      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1641    return the updated checksum.  If buf is Z_NULL, this function returns the
1642    required initial value for the checksum.
1643 
1644      An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1645    much faster.
1646 
1647    Usage example:
1648 
1649      uLong adler = adler32(0L, Z_NULL, 0);
1650 
1651      while (read_buffer(buffer, length) != EOF) {
1652        adler = adler32(adler, buffer, length);
1653      }
1654      if (adler != original_adler) error();
1655 */
1656 
1657 /*
1658 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1659                                           z_off_t len2));
1660 
1661      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
1662    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1663    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
1664    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
1665    that the z_off_t type (like off_t) is a signed integer.  If len2 is
1666    negative, the result has no meaning or utility.
1667 */
1668 
1669 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
1670 /*
1671      Update a running CRC-32 with the bytes buf[0..len-1] and return the
1672    updated CRC-32.  If buf is Z_NULL, this function returns the required
1673    initial value for the crc.  Pre- and post-conditioning (one's complement) is
1674    performed within this function so it shouldn't be done by the application.
1675 
1676    Usage example:
1677 
1678      uLong crc = crc32(0L, Z_NULL, 0);
1679 
1680      while (read_buffer(buffer, length) != EOF) {
1681        crc = crc32(crc, buffer, length);
1682      }
1683      if (crc != original_crc) error();
1684 */
1685 
1686 /*
1687 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1688 
1689      Combine two CRC-32 check values into one.  For two sequences of bytes,
1690    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1691    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
1692    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1693    len2.
1694 */
1695 
1696 
1697                         /* various hacks, don't look :) */
1698 
1699 /* deflateInit and inflateInit are macros to allow checking the zlib version
1700  * and the compiler's view of z_stream:
1701  */
1702 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1703                                      const char *version, int stream_size));
1704 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1705                                      const char *version, int stream_size));
1706 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
1707                                       int windowBits, int memLevel,
1708                                       int strategy, const char *version,
1709                                       int stream_size));
1710 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
1711                                       const char *version, int stream_size));
1712 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1713                                          unsigned char FAR *window,
1714                                          const char *version,
1715                                          int stream_size));
1716 #define deflateInit(strm, level) \
1717         deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1718 #define inflateInit(strm) \
1719         inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1720 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1721         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1722                       (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1723 #define inflateInit2(strm, windowBits) \
1724         inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1725                       (int)sizeof(z_stream))
1726 #define inflateBackInit(strm, windowBits, window) \
1727         inflateBackInit_((strm), (windowBits), (window), \
1728                       ZLIB_VERSION, (int)sizeof(z_stream))
1729 
1730 #ifndef Z_SOLO
1731 
1732 /* gzgetc() macro and its supporting function and exposed data structure.  Note
1733  * that the real internal state is much larger than the exposed structure.
1734  * This abbreviated structure exposes just enough for the gzgetc() macro.  The
1735  * user should not mess with these exposed elements, since their names or
1736  * behavior could change in the future, perhaps even capriciously.  They can
1737  * only be used by the gzgetc() macro.  You have been warned.
1738  */
1739 struct gzFile_s {
1740     unsigned have;
1741     unsigned char *next;
1742     z_off64_t pos;
1743 };
1744 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
1745 #ifdef Z_PREFIX_SET
1746 #  undef z_gzgetc
1747 #  define z_gzgetc(g) \
1748           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
1749 #else
1750 #  define gzgetc(g) \
1751           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
1752 #endif
1753 
1754 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1755  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1756  * both are true, the application gets the *64 functions, and the regular
1757  * functions are changed to 64 bits) -- in case these are set on systems
1758  * without large file support, _LFS64_LARGEFILE must also be true
1759  */
1760 #ifdef Z_LARGE64
1761    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1762    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1763    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1764    ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1765    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1766    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1767 #endif
1768 
1769 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1770 #  ifdef Z_PREFIX_SET
1771 #    define z_gzopen z_gzopen64
1772 #    define z_gzseek z_gzseek64
1773 #    define z_gztell z_gztell64
1774 #    define z_gzoffset z_gzoffset64
1775 #    define z_adler32_combine z_adler32_combine64
1776 #    define z_crc32_combine z_crc32_combine64
1777 #  else
1778 #    define gzopen gzopen64
1779 #    define gzseek gzseek64
1780 #    define gztell gztell64
1781 #    define gzoffset gzoffset64
1782 #    undef adler32_combine
1783 #    undef crc32_combine
1784 #    define adler32_combine adler32_combine64
1785 #    define crc32_combine crc32_combine64
1786 #  endif
1787 #  ifndef Z_LARGE64
1788      ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1789      ZEXTERN off64_t ZEXPORT gzseek64 OF((gzFile, off64_t, int));
1790      ZEXTERN off64_t ZEXPORT gztell64 OF((gzFile));
1791      ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1792      ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, off64_t));
1793      ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, off64_t));
1794 #  endif
1795 #else
1796    ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1797    ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1798    ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1799    ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1800    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1801    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1802 #endif
1803 
1804 #else /* Z_SOLO */
1805 
1806    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1807    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1808 
1809 #endif /* !Z_SOLO */
1810 
1811 /* hack for buggy compilers */
1812 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1813     struct internal_state {int dummy;};
1814 #endif
1815 
1816 /* undocumented functions */
1817 ZEXTERN const char   * ZEXPORT zError           OF((int));
1818 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
1819 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
1820 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
1821 ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
1822 ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
1823 #if defined(_WIN32) && !defined(Z_SOLO)
1824 ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
1825                                             const char *mode));
1826 #endif
1827 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1828 #  ifndef Z_SOLO
1829 ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1830                                                   const char *format,
1831                                                   va_list va));
1832 #  endif
1833 #endif
1834 
1835 #ifdef __cplusplus
1836 }
1837 #endif
1838 
1839 #endif /* ZLIB_H */
1840