xref: /netbsd-src/sys/net/zlib.h (revision e5ba6e4e61ec01c5b07847356b13749c99993c99)
1 /* $NetBSD: zlib.h,v 1.15 2020/03/05 07:46:49 riastradh Exp $ */
2 
3 /* zlib.h -- interface of the 'zlib' general purpose compression library
4   version 1.1.4, March 11th, 2002
5 
6   Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler
7 
8   This software is provided 'as-is', without any express or implied
9   warranty.  In no event will the authors be held liable for any damages
10   arising from the use of this software.
11 
12   Permission is granted to anyone to use this software for any purpose,
13   including commercial applications, and to alter it and redistribute it
14   freely, subject to the following restrictions:
15 
16   1. The origin of this software must not be misrepresented; you must not
17      claim that you wrote the original software. If you use this software
18      in a product, an acknowledgment in the product documentation would be
19      appreciated but is not required.
20   2. Altered source versions must be plainly marked as such, and must not be
21      misrepresented as being the original software.
22   3. This notice may not be removed or altered from any source distribution.
23 
24   Jean-loup Gailly        Mark Adler
25   jloup@gzip.org          madler@alumni.caltech.edu
26 
27 
28   The data format used by the zlib library is described by RFCs (Request for
29   Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
30   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
31 */
32 
33 #ifndef _NET_ZLIB_H_
34 #define _NET_ZLIB_H_
35 
36 #ifdef __NetBSD__
37 #include <sys/cdefs.h>
38 #endif
39 
40 /* +++ zconf.h */
41 /* zconf.h -- configuration of the zlib compression library
42  * Copyright (C) 1995-2002 Jean-loup Gailly.
43  * For conditions of distribution and use, see copyright notice in zlib.h
44  */
45 
46 /* @(#) $Id: zlib.h,v 1.15 2020/03/05 07:46:49 riastradh Exp $ */
47 
48 #ifndef ZCONF_H
49 #define ZCONF_H
50 
51 /*
52  * Warning:  This file pollutes the user's namespace with:
53  * 	Byte Bytef EXPORT FAR OF STDC
54  *  charf intf uInt uIntf uLong uLonf
55  * Programs using this library appear to expect those...
56  */
57 
58 #include <sys/types.h>
59 
60 /*
61  * If you *really* need a unique prefix for all types and library functions,
62  * compile with -DZ_PREFIX. The "standard" zlib should be compiled without it.
63  */
64 #ifdef Z_PREFIX
65 #  define deflateInit_	z_deflateInit_
66 #  define deflate	z_deflate
67 #  define deflateEnd	z_deflateEnd
68 #  define inflateInit_ 	z_inflateInit_
69 #  define inflate	z_inflate
70 #  define inflateEnd	z_inflateEnd
71 #  define deflateInit2_	z_deflateInit2_
72 #  define deflateSetDictionary z_deflateSetDictionary
73 #  define deflateCopy	z_deflateCopy
74 #  define deflateReset	z_deflateReset
75 #  define deflateParams	z_deflateParams
76 #  define inflateInit2_	z_inflateInit2_
77 #  define inflateSetDictionary z_inflateSetDictionary
78 #  define inflateSync	z_inflateSync
79 #  define inflateSyncPoint z_inflateSyncPoint
80 #  define inflateReset	z_inflateReset
81 #  define compress	z_compress
82 #  define compress2	z_compress2
83 #  define uncompress	z_uncompress
84 #  define adler32	z_adler32
85 #  define crc32		z_crc32
86 #  define get_crc_table z_get_crc_table
87 
88 #  define Byte		z_Byte
89 #  define uInt		z_uInt
90 #  define uLong		z_uLong
91 #  define Bytef	        z_Bytef
92 #  define charf		z_charf
93 #  define intf		z_intf
94 #  define uIntf		z_uIntf
95 #  define uLongf	z_uLongf
96 #  define voidpf	z_voidpf
97 #  define voidp		z_voidp
98 #endif
99 
100 #ifndef __32BIT__
101 /* Don't be alarmed; this just means we have at least 32-bits */
102 #  define __32BIT__
103 #endif
104 
105 /*
106  * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
107  * than 64k bytes at a time (needed on systems with 16-bit int).
108  */
109 #if defined(MSDOS) && !defined(__32BIT__)
110 #  define MAXSEG_64K
111 #endif
112 
113 #if 0
114 /* XXX: Are there machines where we should define this?  m68k? */
115 #  define UNALIGNED_OK
116 #endif
117 
118 #if (defined(__STDC__) || defined(__cplusplus)) && !defined(STDC)
119 /* XXX: Look out - this is used in zutil.h and elsewhere... */
120 #  define STDC
121 #endif
122 #if defined(__STDC__) || defined(__cplusplus) || defined(__OS2__)
123 #  ifndef STDC
124 #    define STDC
125 #  endif
126 #endif
127 
128 #ifndef STDC
129 #  ifndef const
130 #    define const
131 #  endif
132 #endif
133 
134 /* Some Mac compilers merge all .h files incorrectly: */
135 #if defined(__MWERKS__) || defined(applec) ||defined(THINK_C) ||defined(__SC__)
136 #  define NO_DUMMY_DECL
137 #endif
138 #define NO_DUMMY_DECL
139 
140 /* Old Borland C incorrectly complains about missing returns: */
141 #if defined(__BORLANDC__) && (__BORLANDC__ < 0x500)
142 #  define NEED_DUMMY_RETURN
143 #endif
144 
145 
146 /* Maximum value for memLevel in deflateInit2 */
147 #ifndef MAX_MEM_LEVEL
148 #  ifdef MAXSEG_64K
149 #    define MAX_MEM_LEVEL 8
150 #  else
151 #    define MAX_MEM_LEVEL 9
152 #  endif
153 #endif
154 
155 /* Maximum value for windowBits in deflateInit2 and inflateInit2.
156  * WARNING: reducing MAX_WBITS makes minigzip unable to extract .gz files
157  * created by gzip. (Files created by minigzip can still be extracted by
158  * gzip.)
159  */
160 #ifndef MAX_WBITS
161 #  define MAX_WBITS   15 /* 32K LZ77 window */
162 #endif
163 
164 /* The memory requirements for deflate are (in bytes):
165             (1 << (windowBits+2)) +  (1 << (memLevel+9))
166  that is: 128K for windowBits=15  +  128K for memLevel = 8  (default values)
167  plus a few kilobytes for small objects. For example, if you want to reduce
168  the default memory requirements from 256K to 128K, compile with
169      make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
170  Of course this will generally degrade compression (there's no free lunch).
171 
172    The memory requirements for inflate are (in bytes) 1 << windowBits
173  that is, 32K for windowBits=15 (default value) plus a few kilobytes
174  for small objects.
175 */
176 
177                         /* Type declarations */
178 
179 #ifndef __P /* function prototypes */
180 #  ifdef STDC
181 #    define __P(args)  args
182 #  else
183 #    define __P(args)  ()
184 #  endif
185 #endif
186 
187 /* The following definitions for FAR are needed only for MSDOS mixed
188  * model programming (small or medium model with some far allocations).
189  * This was tested only with MSC; for other MSDOS compilers you may have
190  * to define NO_MEMCPY in zutil.h.  If you don't need the mixed model,
191  * just define FAR to be empty.
192  */
193 #if (defined(M_I86SM) || defined(M_I86MM)) && !defined(__32BIT__)
194    /* MSC small or medium model */
195 #  define SMALL_MEDIUM
196 #  ifdef _MSC_VER
197 #    define FAR _far
198 #  else
199 #    define FAR far
200 #  endif
201 #endif
202 #if defined(__BORLANDC__) && (defined(__SMALL__) || defined(__MEDIUM__))
203 #  ifndef __32BIT__
204 #    define SMALL_MEDIUM
205 #    define FAR _far
206 #  endif
207 #endif
208 
209 /* Compile with -DZLIB_DLL for Windows DLL support */
210 #if defined(ZLIB_DLL)
211 #  if defined(_WINDOWS) || defined(WINDOWS)
212 #    ifdef FAR
213 #      undef FAR
214 #    endif
215 #    include <windows.h>
216 #    define ZEXPORT  WINAPI
217 #    ifdef WIN32
218 #      define ZEXPORTVA  WINAPIV
219 #    else
220 #      define ZEXPORTVA  FAR _cdecl _export
221 #    endif
222 #  endif
223 #  if defined (__BORLANDC__)
224 #    if (__BORLANDC__ >= 0x0500) && defined (WIN32)
225 #      include <windows.h>
226 #      define ZEXPORT __declspec(dllexport) WINAPI
227 #      define ZEXPORTRVA __declspec(dllexport) WINAPIV
228 #    else
229 #      if defined (_Windows) && defined (__DLL__)
230 #        define ZEXPORT _export
231 #        define ZEXPORTVA _export
232 #      endif
233 #    endif
234 #  endif
235 #endif
236 
237 #if defined (__BEOS__)
238 #  if defined (ZLIB_DLL)
239 #    define ZEXTERN extern __declspec(dllexport)
240 #  else
241 #    define ZEXTERN extern __declspec(dllimport)
242 #  endif
243 #endif
244 
245 #ifndef ZEXPORT
246 #  define ZEXPORT
247 #endif
248 #ifndef ZEXPORTVA
249 #  define ZEXPORTVA
250 #endif
251 #ifndef ZEXTERN
252 #  define ZEXTERN extern
253 #endif
254 
255 #ifndef FAR
256 #   define FAR
257 #endif
258 
259 #if !defined(MACOS) && !defined(TARGET_OS_MAC)
260 typedef unsigned char  Byte;  /* 8 bits */
261 #endif
262 typedef unsigned int   uInt;  /* 16 bits or more */
263 typedef unsigned long  uLong; /* 32 bits or more */
264 
265 #ifdef SMALL_MEDIUM
266    /* Borland C/C++ and some old MSC versions ignore FAR inside typedef */
267 #  define Bytef Byte FAR
268 #else
269    typedef Byte  FAR Bytef;
270 #endif
271 typedef char  FAR charf;
272 typedef int   FAR intf;
273 typedef uInt  FAR uIntf;
274 typedef uLong FAR uLongf;
275 
276 #ifdef STDC
277    typedef void FAR *voidpf;
278    typedef void     *voidp;
279 #else
280    typedef Byte FAR *voidpf;
281    typedef Byte     *voidp;
282 #endif
283 
284 #if (defined(HAVE_UNISTD_H) || defined(__NetBSD__)) && !defined(_KERNEL)
285 #  include <sys/types.h> /* for off_t */
286 #  include <unistd.h>    /* for SEEK_* and off_t */
287 #  define z_off_t  off_t
288 #endif
289 #ifndef SEEK_SET
290 #  define SEEK_SET        0       /* Seek from beginning of file.  */
291 #  define SEEK_CUR        1       /* Seek from current position.  */
292 #  define SEEK_END        2       /* Set file pointer to EOF plus "offset" */
293 #endif
294 #ifndef z_off_t
295 #  define  z_off_t long
296 #endif
297 
298 /* MVS linker does not support external names larger than 8 bytes */
299 #if defined(__MVS__)
300 #   pragma map(deflateInit_,"DEIN")
301 #   pragma map(deflateInit2_,"DEIN2")
302 #   pragma map(deflateEnd,"DEEND")
303 #   pragma map(inflateInit_,"ININ")
304 #   pragma map(inflateInit2_,"ININ2")
305 #   pragma map(inflateEnd,"INEND")
306 #   pragma map(inflateSync,"INSY")
307 #   pragma map(inflateSetDictionary,"INSEDI")
308 #   pragma map(inflate_blocks,"INBL")
309 #   pragma map(inflate_blocks_new,"INBLNE")
310 #   pragma map(inflate_blocks_free,"INBLFR")
311 #   pragma map(inflate_blocks_reset,"INBLRE")
312 #   pragma map(inflate_codes_free,"INCOFR")
313 #   pragma map(inflate_codes,"INCO")
314 #   pragma map(inflate_fast,"INFA")
315 #   pragma map(inflate_flush,"INFLU")
316 #   pragma map(inflate_mask,"INMA")
317 #   pragma map(inflate_set_dictionary,"INSEDI2")
318 #   pragma map(inflate_copyright,"INCOPY")
319 #   pragma map(inflate_trees_bits,"INTRBI")
320 #   pragma map(inflate_trees_dynamic,"INTRDY")
321 #   pragma map(inflate_trees_fixed,"INTRFI")
322 #   pragma map(inflate_trees_free,"INTRFR")
323 #endif
324 
325 #endif /* !ZCONF_H */
326 /* --- zconf.h */
327 
328 #ifndef ZLIB_H
329 #define ZLIB_H
330 #ifdef __cplusplus
331 extern "C" {
332 #endif
333 
334 #define ZLIB_VERSION "1.1.4"
335 
336 /*
337      The 'zlib' compression library provides in-memory compression and
338   decompression functions, including integrity checks of the uncompressed
339   data.  This version of the library supports only one compression method
340   (deflation) but other algorithms will be added later and will have the same
341   stream interface.
342 
343      Compression can be done in a single step if the buffers are large
344   enough (for example if an input file is mmap'ed), or can be done by
345   repeated calls of the compression function.  In the latter case, the
346   application must provide more input and/or consume the output
347   (providing more output space) before each call.
348 
349      The library also supports reading and writing files in gzip (.gz) format
350   with an interface similar to that of stdio.
351 
352      The library does not install any signal handler. The decoder checks
353   the consistency of the compressed data, so the library should never
354   crash even in case of corrupted input.
355 */
356 
357 typedef voidpf (*alloc_func)(voidpf, uInt, uInt);
358 typedef void   (*free_func)(voidpf, voidpf);
359 
360 struct internal_state;
361 
362 typedef struct z_stream_s {
363     Bytef    *next_in;  /* next input byte */
364     uInt     avail_in;  /* number of bytes available at next_in */
365     uLong    total_in;  /* total nb of input bytes read so far */
366 
367     Bytef    *next_out; /* next output byte should be put there */
368     uInt     avail_out; /* remaining free space at next_out */
369     uLong    total_out; /* total nb of bytes output so far */
370 
371     const char *msg;      /* last error message, NULL if no error */
372     struct internal_state FAR *state; /* not visible by applications */
373 
374     alloc_func zalloc;  /* used to allocate the internal state */
375     free_func  zfree;   /* used to free the internal state */
376     voidpf     opaque;  /* private data object passed to zalloc and zfree */
377 
378     int     data_type;  /* best guess about the data type: ascii or binary */
379     uLong   adler;      /* adler32 value of the uncompressed data */
380     uLong   reserved;   /* reserved for future use */
381 } z_stream;
382 
383 typedef z_stream FAR *z_streamp;
384 
385 /*
386    The application must update next_in and avail_in when avail_in has
387    dropped to zero. It must update next_out and avail_out when avail_out
388    has dropped to zero. The application must initialize zalloc, zfree and
389    opaque before calling the init function. All other fields are set by the
390    compression library and must not be updated by the application.
391 
392    The opaque value provided by the application will be passed as the first
393    parameter for calls of zalloc and zfree. This can be useful for custom
394    memory management. The compression library attaches no meaning to the
395    opaque value.
396 
397    zalloc must return Z_NULL if there is not enough memory for the object.
398    If zlib is used in a multi-threaded application, zalloc and zfree must be
399    thread safe.
400 
401    On 16-bit systems, the functions zalloc and zfree must be able to allocate
402    exactly 65536 bytes, but will not be required to allocate more than this
403    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
404    pointers returned by zalloc for objects of exactly 65536 bytes *must*
405    have their offset normalized to zero. The default allocation function
406    provided by this library ensures this (see zutil.c). To reduce memory
407    requirements and avoid any allocation of 64K objects, at the expense of
408    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
409 
410    The fields total_in and total_out can be used for statistics or
411    progress reports. After compression, total_in holds the total size of
412    the uncompressed data and may be saved for use in the decompressor
413    (particularly if the decompressor wants to decompress everything in
414    a single step).
415 */
416 
417                         /* constants */
418 
419 #define Z_NO_FLUSH      0
420 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
421 #define Z_PACKET_FLUSH  2
422 #define Z_SYNC_FLUSH    3
423 #define Z_FULL_FLUSH    4
424 #define Z_FINISH        5
425 /* Allowed flush values; see deflate() below for details */
426 
427 #define Z_OK            0
428 #define Z_STREAM_END    1
429 #define Z_NEED_DICT     2
430 #define Z_ERRNO        (-1)
431 #define Z_STREAM_ERROR (-2)
432 #define Z_DATA_ERROR   (-3)
433 #define Z_MEM_ERROR    (-4)
434 #define Z_BUF_ERROR    (-5)
435 #define Z_VERSION_ERROR (-6)
436 /* Return codes for the compression/decompression functions. Negative
437  * values are errors, positive values are used for special but normal events.
438  */
439 
440 #define Z_NO_COMPRESSION         0
441 #define Z_BEST_SPEED             1
442 #define Z_BEST_COMPRESSION       9
443 #define Z_DEFAULT_COMPRESSION  (-1)
444 /* compression levels */
445 
446 #define Z_FILTERED            1
447 #define Z_HUFFMAN_ONLY        2
448 #define Z_DEFAULT_STRATEGY    0
449 /* compression strategy; see deflateInit2() below for details */
450 
451 #define Z_BINARY   0
452 #define Z_ASCII    1
453 #define Z_UNKNOWN  2
454 /* Possible values of the data_type field */
455 
456 #define Z_DEFLATED   8
457 /* The deflate compression method (the only one supported in this version) */
458 
459 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
460 
461 #define zlib_version zlibVersion()
462 /* for compatibility with versions < 1.0.2 */
463 
464                         /* basic functions */
465 
466 ZEXTERN const char * ZEXPORT zlibVersion(void);
467 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
468    If the first character differs, the library code actually used is
469    not compatible with the zlib.h header file used by the application.
470    This check is automatically made by deflateInit and inflateInit.
471  */
472 
473 /*
474 ZEXTERN int ZEXPORT deflateInit(z_streamp, int);
475 
476      Initializes the internal stream state for compression. The fields
477    zalloc, zfree and opaque must be initialized before by the caller.
478    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
479    use default allocation functions.
480 
481      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
482    1 gives best speed, 9 gives best compression, 0 gives no compression at
483    all (the input data is simply copied a block at a time).
484    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
485    compression (currently equivalent to level 6).
486 
487      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
488    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
489    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
490    with the version assumed by the caller (ZLIB_VERSION).
491    msg is set to null if there is no error message.  deflateInit does not
492    perform any compression: this will be done by deflate().
493 */
494 
495 
496 ZEXTERN int ZEXPORT deflate(z_streamp, int);
497 /*
498     deflate compresses as much data as possible, and stops when the input
499   buffer becomes empty or the output buffer becomes full. It may introduce some
500   output latency (reading input without producing any output) except when
501   forced to flush.
502 
503     The detailed semantics are as follows. deflate performs one or both of the
504   following actions:
505 
506   - Compress more input starting at next_in and update next_in and avail_in
507     accordingly. If not all input can be processed (because there is not
508     enough room in the output buffer), next_in and avail_in are updated and
509     processing will resume at this point for the next call of deflate().
510 
511   - Provide more output starting at next_out and update next_out and avail_out
512     accordingly. This action is forced if the parameter flush is non zero.
513     Forcing flush frequently degrades the compression ratio, so this parameter
514     should be set only when necessary (in interactive applications).
515     Some output may be provided even if flush is not set.
516 
517   Before the call of deflate(), the application should ensure that at least
518   one of the actions is possible, by providing more input and/or consuming
519   more output, and updating avail_in or avail_out accordingly; avail_out
520   should never be zero before the call. The application can consume the
521   compressed output when it wants, for example when the output buffer is full
522   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
523   and with zero avail_out, it must be called again after making room in the
524   output buffer because there might be more output pending.
525 
526     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
527   flushed to the output buffer and the output is aligned on a byte boundary, so
528   that the decompressor can get all input data available so far. (In particular
529   avail_in is zero after the call if enough output space has been provided
530   before the call.)  Flushing may degrade compression for some compression
531   algorithms and so it should be used only when necessary.
532 
533     If flush is set to Z_FULL_FLUSH, all output is flushed as with
534   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
535   restart from this point if previous compressed data has been damaged or if
536   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
537   the compression.
538 
539     If deflate returns with avail_out == 0, this function must be called again
540   with the same value of the flush parameter and more output space (updated
541   avail_out), until the flush is complete (deflate returns with non-zero
542   avail_out).
543 
544     If the parameter flush is set to Z_PACKET_FLUSH, the compression
545   block is terminated, and a zero-length stored block is output,
546   omitting the length bytes (the effect of this is that the 3-bit type
547   code 000 for a stored block is output, and the output is then
548   byte-aligned).  This is designed for use at the end of a PPP packet.
549 
550 
551     If the parameter flush is set to Z_FINISH, pending input is processed,
552   pending output is flushed and deflate returns with Z_STREAM_END if there
553   was enough output space; if deflate returns with Z_OK, this function must be
554   called again with Z_FINISH and more output space (updated avail_out) but no
555   more input data, until it returns with Z_STREAM_END or an error. After
556   deflate has returned Z_STREAM_END, the only possible operations on the
557   stream are deflateReset or deflateEnd.
558 
559     Z_FINISH can be used immediately after deflateInit if all the compression
560   is to be done in a single step. In this case, avail_out must be at least
561   0.1% larger than avail_in plus 12 bytes.  If deflate does not return
562   Z_STREAM_END, then it must be called again as described above.
563 
564     deflate() sets strm->adler to the adler32 checksum of all input read
565   so far (that is, total_in bytes).
566 
567     deflate() may update data_type if it can make a good guess about
568   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
569   binary. This field is only for information purposes and does not affect
570   the compression algorithm in any manner.
571 
572     deflate() returns Z_OK if some progress has been made (more input
573   processed or more output produced), Z_STREAM_END if all input has been
574   consumed and all output has been produced (only when flush is set to
575   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
576   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
577   (for example avail_in or avail_out was zero).
578 */
579 
580 
581 ZEXTERN int ZEXPORT deflateEnd(z_streamp);
582 /*
583      All dynamically allocated data structures for this stream are freed.
584    This function discards any unprocessed input and does not flush any
585    pending output.
586 
587      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
588    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
589    prematurely (some input or output was discarded). In the error case,
590    msg may be set but then points to a static string (which must not be
591    deallocated).
592 */
593 
594 
595 /*
596 ZEXTERN int ZEXPORT inflateInit(z_streamp);
597 
598      Initializes the internal stream state for decompression. The fields
599    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
600    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
601    value depends on the compression method), inflateInit determines the
602    compression method from the zlib header and allocates all data structures
603    accordingly; otherwise the allocation will be deferred to the first call of
604    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
605    use default allocation functions.
606 
607      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
608    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
609    version assumed by the caller.  msg is set to null if there is no error
610    message. inflateInit does not perform any decompression apart from reading
611    the zlib header if present: this will be done by inflate().  (So next_in and
612    avail_in may be modified, but next_out and avail_out are unchanged.)
613 */
614 
615 
616 ZEXTERN int ZEXPORT inflate(z_streamp, int);
617 /*
618     inflate decompresses as much data as possible, and stops when the input
619   buffer becomes empty or the output buffer becomes full. It may some
620   introduce some output latency (reading input without producing any output)
621   except when forced to flush.
622 
623   The detailed semantics are as follows. inflate performs one or both of the
624   following actions:
625 
626   - Decompress more input starting at next_in and update next_in and avail_in
627     accordingly. If not all input can be processed (because there is not
628     enough room in the output buffer), next_in is updated and processing
629     will resume at this point for the next call of inflate().
630 
631   - Provide more output starting at next_out and update next_out and avail_out
632     accordingly.  inflate() provides as much output as possible, until there
633     is no more input data or no more space in the output buffer (see below
634     about the flush parameter).
635 
636   Before the call of inflate(), the application should ensure that at least
637   one of the actions is possible, by providing more input and/or consuming
638   more output, and updating the next_* and avail_* values accordingly.
639   The application can consume the uncompressed output when it wants, for
640   example when the output buffer is full (avail_out == 0), or after each
641   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
642   must be called again after making room in the output buffer because there
643   might be more output pending.
644 
645     If the parameter flush is set to Z_SYNC_FLUSH or Z_PACKET_FLUSH,
646   inflate flushes as much output as possible to the output buffer. The
647   flushing behavior of inflate is not specified for values of the flush
648   parameter other than Z_SYNC_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
649   current implementation actually flushes as much output as possible
650   anyway. For Z_PACKET_FLUSH, inflate checks that once all the input data
651   has been consumed, it is expecting to see the length field of a stored
652   block; if not, it returns Z_DATA_ERROR.
653 
654     inflate() should normally be called until it returns Z_STREAM_END or an
655   error. However if all decompression is to be performed in a single step
656   (a single call of inflate), the parameter flush should be set to
657   Z_FINISH. In this case all pending input is processed and all pending
658   output is flushed; avail_out must be large enough to hold all the
659   uncompressed data. (The size of the uncompressed data may have been saved
660   by the compressor for this purpose.) The next operation on this stream must
661   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
662   is never required, but can be used to inform inflate that a faster routine
663   may be used for the single inflate() call.
664 
665      If a preset dictionary is needed at this point (see inflateSetDictionary
666   below), inflate sets strm-adler to the adler32 checksum of the
667   dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
668   it sets strm->adler to the adler32 checksum of all output produced
669   so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
670   an error code as described below. At the end of the stream, inflate()
671   checks that its computed adler32 checksum is equal to that saved by the
672   compressor and returns Z_STREAM_END only if the checksum is correct.
673 
674     inflate() returns Z_OK if some progress has been made (more input processed
675   or more output produced), Z_STREAM_END if the end of the compressed data has
676   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
677   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
678   corrupted (input stream not conforming to the zlib format or incorrect
679   adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
680   (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
681   enough memory, Z_BUF_ERROR if no progress is possible or if there was not
682   enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
683   case, the application may then call inflateSync to look for a good
684   compression block.
685 */
686 
687 
688 ZEXTERN int ZEXPORT inflateEnd(z_streamp);
689 /*
690      All dynamically allocated data structures for this stream are freed.
691    This function discards any unprocessed input and does not flush any
692    pending output.
693 
694      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
695    was inconsistent. In the error case, msg may be set but then points to a
696    static string (which must not be deallocated).
697 */
698 
699                         /* Advanced functions */
700 
701 /*
702     The following functions are needed only in some special applications.
703 */
704 
705 /*
706 ZEXTERN int ZEXPORT deflateInit2(z_streamp, int, int, int, int, int);
707 
708      This is another version of deflateInit with more compression options. The
709    fields next_in, zalloc, zfree and opaque must be initialized before by
710    the caller.
711 
712      The method parameter is the compression method. It must be Z_DEFLATED in
713    this version of the library.
714 
715      The windowBits parameter is the base two logarithm of the window size
716    (the size of the history buffer).  It should be in the range 8..15 for this
717    version of the library. Larger values of this parameter result in better
718    compression at the expense of memory usage. The default value is 15 if
719    deflateInit is used instead.
720 
721      The memLevel parameter specifies how much memory should be allocated
722    for the internal compression state. memLevel=1 uses minimum memory but
723    is slow and reduces compression ratio; memLevel=9 uses maximum memory
724    for optimal speed. The default value is 8. See zconf.h for total memory
725    usage as a function of windowBits and memLevel.
726 
727      The strategy parameter is used to tune the compression algorithm. Use the
728    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
729    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
730    string match).  Filtered data consists mostly of small values with a
731    somewhat random distribution. In this case, the compression algorithm is
732    tuned to compress them better. The effect of Z_FILTERED is to force more
733    Huffman coding and less string matching; it is somewhat intermediate
734    between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
735    the compression ratio but not the correctness of the compressed output even
736    if it is not set appropriately.
737 
738       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
739    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
740    method). msg is set to null if there is no error message.  deflateInit2 does
741    not perform any compression: this will be done by deflate().
742 */
743 
744 ZEXTERN int ZEXPORT deflateSetDictionary(z_streamp, const Bytef *, uInt);
745 /*
746      Initializes the compression dictionary from the given byte sequence
747    without producing any compressed output. This function must be called
748    immediately after deflateInit, deflateInit2 or deflateReset, before any
749    call of deflate. The compressor and decompressor must use exactly the same
750    dictionary (see inflateSetDictionary).
751 
752      The dictionary should consist of strings (byte sequences) that are likely
753    to be encountered later in the data to be compressed, with the most commonly
754    used strings preferably put towards the end of the dictionary. Using a
755    dictionary is most useful when the data to be compressed is short and can be
756    predicted with good accuracy; the data can then be compressed better than
757    with the default empty dictionary.
758 
759      Depending on the size of the compression data structures selected by
760    deflateInit or deflateInit2, a part of the dictionary may in effect be
761    discarded, for example if the dictionary is larger than the window size in
762    deflate or deflate2. Thus the strings most likely to be useful should be
763    put at the end of the dictionary, not at the front.
764 
765      Upon return of this function, strm->adler is set to the Adler32 value
766    of the dictionary; the decompressor may later use this value to determine
767    which dictionary has been used by the compressor. (The Adler32 value
768    applies to the whole dictionary even if only a subset of the dictionary is
769    actually used by the compressor.)
770 
771      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
772    parameter is invalid (such as NULL dictionary) or the stream state is
773    inconsistent (for example if deflate has already been called for this stream
774    or if the compression method is bsort). deflateSetDictionary does not
775    perform any compression: this will be done by deflate().
776 */
777 
778 ZEXTERN int ZEXPORT deflateCopy(z_streamp, z_streamp);
779 /*
780      Sets the destination stream as a complete copy of the source stream.
781 
782      This function can be useful when several compression strategies will be
783    tried, for example when there are several ways of pre-processing the input
784    data with a filter. The streams that will be discarded should then be freed
785    by calling deflateEnd.  Note that deflateCopy duplicates the internal
786    compression state which can be quite large, so this strategy is slow and
787    can consume lots of memory.
788 
789      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
790    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
791    (such as zalloc being NULL). msg is left unchanged in both source and
792    destination.
793 */
794 
795 extern int inflateIncomp(z_stream *);
796 /*
797      This function adds the data at next_in (avail_in bytes) to the output
798    history without performing any output.  There must be no pending output,
799    and the decompressor must be expecting to see the start of a block.
800    Calling this function is equivalent to decompressing a stored block
801    containing the data at next_in (except that the data is not output).
802 */
803 
804 ZEXTERN int ZEXPORT deflateReset(z_streamp);
805 /*
806      This function is equivalent to deflateEnd followed by deflateInit,
807    but does not free and reallocate all the internal compression state.
808    The stream will keep the same compression level and any other attributes
809    that may have been set by deflateInit2.
810 
811       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
812    stream state was inconsistent (such as zalloc or state being NULL).
813 */
814 
815 ZEXTERN int ZEXPORT deflateParams(z_streamp, int, int);
816 /*
817      Dynamically update the compression level and compression strategy.  The
818    interpretation of level and strategy is as in deflateInit2.  This can be
819    used to switch between compression and straight copy of the input data, or
820    to switch to a different kind of input data requiring a different
821    strategy. If the compression level is changed, the input available so far
822    is compressed with the old level (and may be flushed); the new level will
823    take effect only at the next call of deflate().
824 
825      Before the call of deflateParams, the stream state must be set as for
826    a call of deflate(), since the currently available input may have to
827    be compressed and flushed. In particular, strm->avail_out must be non-zero.
828 
829      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
830    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
831    if strm->avail_out was zero.
832 */
833 
834 ZEXTERN int ZEXPORT deflateOutputPending(z_streamp);
835 /*
836      Returns the number of bytes of output which are immediately
837    available from the compressor (i.e. without any further input
838    or flush).
839 */
840 
841 /*
842 ZEXTERN int ZEXPORT inflateInit2(z_streamp, int);
843 
844      This is another version of inflateInit with an extra parameter. The
845    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
846    before by the caller.
847 
848      The windowBits parameter is the base two logarithm of the maximum window
849    size (the size of the history buffer).  It should be in the range 8..15 for
850    this version of the library. The default value is 15 if inflateInit is used
851    instead. If a compressed stream with a larger window size is given as
852    input, inflate() will return with the error code Z_DATA_ERROR instead of
853    trying to allocate a larger window.
854 
855       inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
856    memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
857    memLevel). msg is set to null if there is no error message.  inflateInit2
858    does not perform any decompression apart from reading the zlib header if
859    present: this will be done by inflate(). (So next_in and avail_in may be
860    modified, but next_out and avail_out are unchanged.)
861 */
862 
863 ZEXTERN int ZEXPORT inflateSetDictionary(z_streamp, const Bytef *, uInt);
864 /*
865      Initializes the decompression dictionary from the given uncompressed byte
866    sequence. This function must be called immediately after a call of inflate
867    if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
868    can be determined from the Adler32 value returned by this call of
869    inflate. The compressor and decompressor must use exactly the same
870    dictionary (see deflateSetDictionary).
871 
872      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
873    parameter is invalid (such as NULL dictionary) or the stream state is
874    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
875    expected one (incorrect Adler32 value). inflateSetDictionary does not
876    perform any decompression: this will be done by subsequent calls of
877    inflate().
878 */
879 
880 ZEXTERN int ZEXPORT inflateSync(z_streamp);
881 /*
882     Skips invalid compressed data until a full flush point (see above the
883   description of deflate with Z_FULL_FLUSH) can be found, or until all
884   available input is skipped. No output is provided.
885 
886     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
887   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
888   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
889   case, the application may save the current current value of total_in which
890   indicates where valid compressed data was found. In the error case, the
891   application may repeatedly call inflateSync, providing more input each time,
892   until success or end of the input data.
893 */
894 
895 ZEXTERN int ZEXPORT inflateReset(z_streamp);
896 /*
897      This function is equivalent to inflateEnd followed by inflateInit,
898    but does not free and reallocate all the internal decompression state.
899    The stream will keep attributes that may have been set by inflateInit2.
900 
901       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
902    stream state was inconsistent (such as zalloc or state being NULL).
903 */
904 
905 
906                         /* utility functions */
907 
908 /*
909      The following utility functions are implemented on top of the
910    basic stream-oriented functions. To simplify the interface, some
911    default options are assumed (compression level and memory usage,
912    standard memory allocation functions). The source code of these
913    utility functions can easily be modified if you need special options.
914 */
915 
916 ZEXTERN int ZEXPORT compress(Bytef *, uLongf *, const Bytef *, uLong);
917 /*
918      Compresses the source buffer into the destination buffer.  sourceLen is
919    the byte length of the source buffer. Upon entry, destLen is the total
920    size of the destination buffer, which must be at least 0.1% larger than
921    sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
922    compressed buffer.
923      This function can be used to compress a whole file at once if the
924    input file is mmap'ed.
925      compress returns Z_OK if success, Z_MEM_ERROR if there was not
926    enough memory, Z_BUF_ERROR if there was not enough room in the output
927    buffer.
928 */
929 
930 ZEXTERN int ZEXPORT compress2(Bytef *, uLongf *, const Bytef *,
931 	    uLong, int);
932 /*
933      Compresses the source buffer into the destination buffer. The level
934    parameter has the same meaning as in deflateInit.  sourceLen is the byte
935    length of the source buffer. Upon entry, destLen is the total size of the
936    destination buffer, which must be at least 0.1% larger than sourceLen plus
937    12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
938 
939      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
940    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
941    Z_STREAM_ERROR if the level parameter is invalid.
942 */
943 
944 ZEXTERN int ZEXPORT uncompress(Bytef *, uLongf *, const Bytef *, uLong);
945 /*
946      Decompresses the source buffer into the destination buffer.  sourceLen is
947    the byte length of the source buffer. Upon entry, destLen is the total
948    size of the destination buffer, which must be large enough to hold the
949    entire uncompressed data. (The size of the uncompressed data must have
950    been saved previously by the compressor and transmitted to the decompressor
951    by some mechanism outside the scope of this compression library.)
952    Upon exit, destLen is the actual size of the compressed buffer.
953      This function can be used to decompress a whole file at once if the
954    input file is mmap'ed.
955 
956      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
957    enough memory, Z_BUF_ERROR if there was not enough room in the output
958    buffer, or Z_DATA_ERROR if the input data was corrupted.
959 */
960 
961 
962 typedef voidp gzFile;
963 
964 ZEXTERN gzFile ZEXPORT gzopen(const char *, const char *);
965 /*
966      Opens a gzip (.gz) file for reading or writing. The mode parameter
967    is as in fopen ("rb" or "wb") but can also include a compression level
968    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
969    Huffman only compression as in "wb1h". (See the description
970    of deflateInit2 for more information about the strategy parameter.)
971 
972      gzopen can be used to read a file which is not in gzip format; in this
973    case gzread will directly read from the file without decompression.
974 
975      gzopen returns NULL if the file could not be opened or if there was
976    insufficient memory to allocate the (de)compression state; errno
977    can be checked to distinguish the two cases (if errno is zero, the
978    zlib error is Z_MEM_ERROR).  */
979 
980 ZEXTERN gzFile ZEXPORT gzdopen(int, const char *);
981 /*
982      gzdopen() associates a gzFile with the file descriptor fd.  File
983    descriptors are obtained from calls like open, dup, creat, pipe or
984    fileno (in the file has been previously opened with fopen).
985    The mode parameter is as in gzopen.
986      The next call of gzclose on the returned gzFile will also close the
987    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
988    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
989      gzdopen returns NULL if there was insufficient memory to allocate
990    the (de)compression state.
991 */
992 
993 ZEXTERN int ZEXPORT gzsetparams(gzFile, int, int);
994 /*
995      Dynamically update the compression level or strategy. See the description
996    of deflateInit2 for the meaning of these parameters.
997      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
998    opened for writing.
999 */
1000 
1001 ZEXTERN int ZEXPORT    gzread(gzFile, voidp, unsigned);
1002 /*
1003      Reads the given number of uncompressed bytes from the compressed file.
1004    If the input file was not in gzip format, gzread copies the given number
1005    of bytes into the buffer.
1006      gzread returns the number of uncompressed bytes actually read (0 for
1007    end of file, -1 for error). */
1008 
1009 ZEXTERN int ZEXPORT    gzwrite(gzFile, const voidp, unsigned);
1010 /*
1011      Writes the given number of uncompressed bytes into the compressed file.
1012    gzwrite returns the number of uncompressed bytes actually written
1013    (0 in case of error).
1014 */
1015 
1016 ZEXTERN int ZEXPORTVA   gzprintf(gzFile, const char *, ...)
1017 		__attribute__((__format__(__printf__, 2, 3)));
1018 /*
1019      Converts, formats, and writes the args to the compressed file under
1020    control of the format string, as in fprintf. gzprintf returns the number of
1021    uncompressed bytes actually written (0 in case of error).
1022 */
1023 
1024 ZEXTERN int ZEXPORT gzputs(gzFile, const char *);
1025 /*
1026       Writes the given null-terminated string to the compressed file, excluding
1027    the terminating null character.
1028       gzputs returns the number of characters written, or -1 in case of error.
1029 */
1030 
1031 ZEXTERN char * ZEXPORT gzgets(gzFile, char *, int);
1032 /*
1033       Reads bytes from the compressed file until len-1 characters are read, or
1034    a newline character is read and transferred to buf, or an end-of-file
1035    condition is encountered.  The string is then terminated with a null
1036    character.
1037       gzgets returns buf, or Z_NULL in case of error.
1038 */
1039 
1040 ZEXTERN int ZEXPORT    gzputc(gzFile, int);
1041 /*
1042       Writes c, converted to an unsigned char, into the compressed file.
1043    gzputc returns the value that was written, or -1 in case of error.
1044 */
1045 
1046 ZEXTERN int ZEXPORT    gzgetc(gzFile);
1047 /*
1048       Reads one byte from the compressed file. gzgetc returns this byte
1049    or -1 in case of end of file or error.
1050 */
1051 
1052 ZEXTERN int ZEXPORT    gzflush(gzFile, int);
1053 /*
1054      Flushes all pending output into the compressed file. The parameter
1055    flush is as in the deflate() function. The return value is the zlib
1056    error number (see function gzerror below). gzflush returns Z_OK if
1057    the flush parameter is Z_FINISH and all output could be flushed.
1058      gzflush should be called only when strictly necessary because it can
1059    degrade compression.
1060 
1061 */
1062 
1063 /*
1064  * NetBSD note:
1065  * "long" gzseek has been there till Oct 1999 (1.4L), which was wrong.
1066  */
1067 ZEXTERN z_off_t ZEXPORT    gzseek(gzFile, z_off_t, int);
1068 /*
1069       Sets the starting position for the next gzread or gzwrite on the
1070    given compressed file. The offset represents a number of bytes in the
1071    uncompressed data stream. The whence parameter is defined as in lseek(2);
1072    the value SEEK_END is not supported.
1073      If the file is opened for reading, this function is emulated but can be
1074    extremely slow. If the file is opened for writing, only forward seeks are
1075    supported; gzseek then compresses a sequence of zeroes up to the new
1076    starting position.
1077 
1078       gzseek returns the resulting offset location as measured in bytes from
1079    the beginning of the uncompressed stream, or -1 in case of error, in
1080    particular if the file is opened for writing and the new starting position
1081    would be before the current position.
1082 */
1083 
1084 ZEXTERN int ZEXPORT    gzrewind(gzFile);
1085 /*
1086      Rewinds the given file. This function is supported only for reading.
1087 
1088    gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1089 */
1090 
1091 /*
1092  * NetBSD note:
1093  * "long" gztell has been there till Oct 1999 (1.4L), which was wrong.
1094  */
1095 ZEXTERN z_off_t ZEXPORT    gztell(gzFile);
1096 /*
1097      Returns the starting position for the next gzread or gzwrite on the
1098    given compressed file. This position represents a number of bytes in the
1099    uncompressed data stream.
1100 
1101    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1102 */
1103 
1104 ZEXTERN int ZEXPORT gzeof(gzFile);
1105 /*
1106      Returns 1 when EOF has previously been detected reading the given
1107    input stream, otherwise zero.
1108 */
1109 
1110 ZEXTERN int ZEXPORT    gzclose(gzFile);
1111 /*
1112      Flushes all pending output if necessary, closes the compressed file
1113    and deallocates all the (de)compression state. The return value is the zlib
1114    error number (see function gzerror below).
1115 */
1116 
1117 ZEXTERN const char * ZEXPORT gzerror(gzFile, int *);
1118 /*
1119      Returns the error message for the last error which occurred on the
1120    given compressed file. errnum is set to zlib error number. If an
1121    error occurred in the file system and not in the compression library,
1122    errnum is set to Z_ERRNO and the application may consult errno
1123    to get the exact error code.
1124 */
1125 
1126                         /* checksum functions */
1127 
1128 /*
1129      These functions are not related to compression but are exported
1130    anyway because they might be useful in applications using the
1131    compression library.
1132 */
1133 
1134 ZEXTERN uLong ZEXPORT adler32(uLong, const Bytef *, uInt);
1135 
1136 /*
1137      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1138    return the updated checksum. If buf is NULL, this function returns
1139    the required initial value for the checksum.
1140    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1141    much faster. Usage example:
1142 
1143      uLong adler = adler32(0L, Z_NULL, 0);
1144 
1145      while (read_buffer(buffer, length) != EOF) {
1146        adler = adler32(adler, buffer, length);
1147      }
1148      if (adler != original_adler) error();
1149 */
1150 
1151 #ifdef STANDALONE
1152 ZEXTERN uLong ZEXPORT crc32(uLong, const Bytef *, uInt);
1153 #endif
1154 /*
1155      Update a running crc with the bytes buf[0..len-1] and return the updated
1156    crc. If buf is NULL, this function returns the required initial value
1157    for the crc. Pre- and post-conditioning (one's complement) is performed
1158    within this function so it shouldn't be done by the application.
1159    Usage example:
1160 
1161      uLong crc = crc32(0L, Z_NULL, 0);
1162 
1163      while (read_buffer(buffer, length) != EOF) {
1164        crc = crc32(crc, buffer, length);
1165      }
1166      if (crc != original_crc) error();
1167 */
1168 
1169 
1170                         /* various hacks, don't look :) */
1171 
1172 /* deflateInit and inflateInit are macros to allow checking the zlib version
1173  * and the compiler's view of z_stream:
1174  */
1175 ZEXTERN int ZEXPORT deflateInit_(z_streamp, int, const char *, int);
1176 ZEXTERN int ZEXPORT inflateInit_(z_streamp, const char *, int);
1177 ZEXTERN int ZEXPORT deflateInit2_(z_streamp, int, int, int, int,
1178                                       int, const char *, int);
1179 ZEXTERN int ZEXPORT inflateInit2_(z_streamp, int, const char *, int);
1180 #define deflateInit(strm, level) \
1181         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
1182 #define inflateInit(strm) \
1183         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
1184 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1185         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1186                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
1187 #define inflateInit2(strm, windowBits) \
1188         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1189 
1190 
1191 #if !defined(Z_UTIL_H) && !defined(NO_DUMMY_DECL)
1192     struct internal_state {int dummy;}; /* hack for buggy compilers */
1193 #endif
1194 
1195 ZEXTERN const char   * ZEXPORT zError(int);
1196 ZEXTERN int            ZEXPORT inflateSyncPoint(z_streamp);
1197 ZEXTERN const uLongf * ZEXPORT get_crc_table(void);
1198 
1199 #ifdef __cplusplus
1200 }
1201 #endif
1202 #endif /* !ZLIB_H */
1203 
1204 #endif /* !_NET_ZLIB_H_ */
1205 /* -- zlib.h */
1206