1	/* zlib.h -- interface of the 'zlib' general purpose compression library
2	version 1.2.11, January 15th, 2017
3
4	Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
5
6	This software is provided 'as-is', without any express or implied
7	warranty. In no event will the authors be held liable for any damages
8	arising from the use of this software.
9
10	Permission is granted to anyone to use this software for any purpose,
11	including commercial applications, and to alter it and redistribute it
12	freely, subject to the following restrictions:
13
14	1. The origin of this software must not be misrepresented; you must not
15	claim that you wrote the original software. If you use this software
16	in a product, an acknowledgment in the product documentation would be
17	appreciated but is not required.
18	2. Altered source versions must be plainly marked as such, and must not be
19	misrepresented as being the original software.
20	3. This notice may not be removed or altered from any source distribution.
21
22	Jean-loup Gailly Mark Adler
23	jloup@gzip.org madler@alumni.caltech.edu
24
25
26	The data format used by the zlib library is described by RFCs (Request for
27	Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
28	(zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
29	*/
30
31	#ifndef ZLIB_H
32	#define ZLIB_H
33
34	#include "zconf.h"
35
36	#ifdef __cplusplus
37	extern "C" {
38	#endif
39
40	#define ZLIB_VERSION "1.2.11"
41	#define ZLIB_VERNUM 0x12b0
42	#define ZLIB_VER_MAJOR 1
43	#define ZLIB_VER_MINOR 2
44	#define ZLIB_VER_REVISION 11
45	#define ZLIB_VER_SUBREVISION 0
46
47	/*
48	The 'zlib' compression library provides in-memory compression and
49	decompression functions, including integrity checks of the uncompressed data.
50	This version of the library supports only one compression method (deflation)
51	but other algorithms will be added later and will have the same stream
52	interface.
53
54	Compression can be done in a single step if the buffers are large enough,
55	or can be done by repeated calls of the compression function. In the latter
56	case, the application must provide more input and/or consume the output
57	(providing more output space) before each call.
58
59	The compressed data format used by default by the in-memory functions is
60	the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
61	around a deflate stream, which is itself documented in RFC 1951.
62
63	The library also supports reading and writing files in gzip (.gz) format
64	with an interface similar to that of stdio using the functions that start
65	with "gz". The gzip format is different from the zlib format. gzip is a
66	gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
67
68	This library can optionally read and write gzip and raw deflate streams in
69	memory as well.
70
71	The zlib format was designed to be compact and fast for use in memory
72	and on communications channels. The gzip format was designed for single-
73	file compression on file systems, has a larger header than zlib to maintain
74	directory information, and uses a different, slower check method than zlib.
75
76	The library does not install any signal handler. The decoder checks
77	the consistency of the compressed data, so the library should never crash
78	even in the case of corrupted input.
79	*/
80
81	typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
82	typedef void (*free_func) OF((voidpf opaque, voidpf address));
83
84	struct internal_state;
85
86	typedef struct z_stream_s {
87	z_const Bytef *next_in; /* next input byte */
88	uInt avail_in; /* number of bytes available at next_in */
89	uLong total_in; /* total number of input bytes read so far */
90
91	Bytef *next_out; /* next output byte will go here */
92	uInt avail_out; /* remaining free space at next_out */
93	uLong total_out; /* total number of bytes output so far */
94
95	z_const char *msg; /* last error message, NULL if no error */
96	struct internal_state FAR *state; /* not visible by applications */
97
98	alloc_func zalloc; /* used to allocate the internal state */
99	free_func zfree; /* used to free the internal state */
100	voidpf opaque; /* private data object passed to zalloc and zfree */
101
102	int data_type; /* best guess about the data type: binary or text
103	for deflate, or the decoding state for inflate */
104	uLong adler; /* Adler-32 or CRC-32 value of the uncompressed data */
105	uLong reserved; /* reserved for future use */
106	} z_stream;
107
108	typedef z_stream FAR *z_streamp;
109
110	/*
111	gzip header information passed to and from zlib routines. See RFC 1952
112	for more details on the meanings of these fields.
113	*/
114	typedef struct gz_header_s {
115	int text; /* true if compressed data believed to be text */
116	uLong time; /* modification time */
117	int xflags; /* extra flags (not used when writing a gzip file) */
118	int os; /* operating system */
119	Bytef *extra; /* pointer to extra field or Z_NULL if none */
120	uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
121	uInt extra_max; /* space at extra (only when reading header) */
122	Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
123	uInt name_max; /* space at name (only when reading header) */
124	Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
125	uInt comm_max; /* space at comment (only when reading header) */
126	int hcrc; /* true if there was or will be a header crc */
127	int done; /* true when done reading gzip header (not used
128	when writing a gzip file) */
129	} gz_header;
130
131	typedef gz_header FAR *gz_headerp;
132
133	/*
134	The application must update next_in and avail_in when avail_in has dropped
135	to zero. It must update next_out and avail_out when avail_out has dropped
136	to zero. The application must initialize zalloc, zfree and opaque before
137	calling the init function. All other fields are set by the compression
138	library and must not be updated by the application.
139
140	The opaque value provided by the application will be passed as the first
141	parameter for calls of zalloc and zfree. This can be useful for custom
142	memory management. The compression library attaches no meaning to the
143	opaque value.
144
145	zalloc must return Z_NULL if there is not enough memory for the object.
146	If zlib is used in a multi-threaded application, zalloc and zfree must be
147	thread safe. In that case, zlib is thread-safe. When zalloc and zfree are
148	Z_NULL on entry to the initialization function, they are set to internal
149	routines that use the standard library functions malloc() and free().
150
151	On 16-bit systems, the functions zalloc and zfree must be able to allocate
152	exactly 65536 bytes, but will not be required to allocate more than this if
153	the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
154	returned by zalloc for objects of exactly 65536 bytes *must* have their
155	offset normalized to zero. The default allocation function provided by this
156	library ensures this (see zutil.c). To reduce memory requirements and avoid
157	any allocation of 64K objects, at the expense of compression ratio, compile
158	the library with -DMAX_WBITS=14 (see zconf.h).
159
160	The fields total_in and total_out can be used for statistics or progress
161	reports. After compression, total_in holds the total size of the
162	uncompressed data and may be saved for use by the decompressor (particularly
163	if the decompressor wants to decompress everything in a single step).
164	*/
165
166	/* constants */
167
168	#define Z_NO_FLUSH 0
169	#define Z_PARTIAL_FLUSH 1
170	#define Z_SYNC_FLUSH 2
171	#define Z_FULL_FLUSH 3
172	#define Z_FINISH 4
173	#define Z_BLOCK 5
174	#define Z_TREES 6
175	/* Allowed flush values; see deflate() and inflate() below for details */
176
177	#define Z_OK 0
178	#define Z_STREAM_END 1
179	#define Z_NEED_DICT 2
180	#define Z_ERRNO (-1)
181	#define Z_STREAM_ERROR (-2)
182	#define Z_DATA_ERROR (-3)
183	#define Z_MEM_ERROR (-4)
184	#define Z_BUF_ERROR (-5)
185	#define Z_VERSION_ERROR (-6)
186	/* Return codes for the compression/decompression functions. Negative values
187	* are errors, positive values are used for special but normal events.
188	*/
189
190	#define Z_NO_COMPRESSION 0
191	#define Z_BEST_SPEED 1
192	#define Z_BEST_COMPRESSION 9
193	#define Z_DEFAULT_COMPRESSION (-1)
194	/* compression levels */
195
196	#define Z_FILTERED 1
197	#define Z_HUFFMAN_ONLY 2
198	#define Z_RLE 3
199	#define Z_FIXED 4
200	#define Z_DEFAULT_STRATEGY 0
201	/* compression strategy; see deflateInit2() below for details */
202
203	#define Z_BINARY 0
204	#define Z_TEXT 1
205	#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
206	#define Z_UNKNOWN 2
207	/* Possible values of the data_type field for deflate() */
208
209	#define Z_DEFLATED 8
210	/* The deflate compression method (the only one supported in this version) */
211
212	#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
213
214	#define zlib_version zlibVersion()
215	/* for compatibility with versions < 1.0.2 */
216
217
218	/* basic functions */
219
220	ZEXTERN const char * ZEXPORT zlibVersion OF((void));
221	/* The application can compare zlibVersion and ZLIB_VERSION for consistency.
222	If the first character differs, the library code actually used is not
223	compatible with the zlib.h header file used by the application. This check
224	is automatically made by deflateInit and inflateInit.
225	*/
226
227	/*
228	ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
229
230	Initializes the internal stream state for compression. The fields
231	zalloc, zfree and opaque must be initialized before by the caller. If
232	zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
233	allocation functions.
234
235	The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
236	1 gives best speed, 9 gives best compression, 0 gives no compression at all
237	(the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
238	requests a default compromise between speed and compression (currently
239	equivalent to level 6).
240
241	deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
242	memory, Z_STREAM_ERROR if level is not a valid compression level, or
243	Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
244	with the version assumed by the caller (ZLIB_VERSION). msg is set to null
245	if there is no error message. deflateInit does not perform any compression:
246	this will be done by deflate().
247	*/
248
249
250	ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
251	/*
252	deflate compresses as much data as possible, and stops when the input
253	buffer becomes empty or the output buffer becomes full. It may introduce
254	some output latency (reading input without producing any output) except when
255	forced to flush.
256
257	The detailed semantics are as follows. deflate performs one or both of the
258	following actions:
259
260	- Compress more input starting at next_in and update next_in and avail_in
261	accordingly. If not all input can be processed (because there is not
262	enough room in the output buffer), next_in and avail_in are updated and
263	processing will resume at this point for the next call of deflate().
264
265	- Generate more output starting at next_out and update next_out and avail_out
266	accordingly. This action is forced if the parameter flush is non zero.
267	Forcing flush frequently degrades the compression ratio, so this parameter
268	should be set only when necessary. Some output may be provided even if
269	flush is zero.
270
271	Before the call of deflate(), the application should ensure that at least
272	one of the actions is possible, by providing more input and/or consuming more
273	output, and updating avail_in or avail_out accordingly; avail_out should
274	never be zero before the call. The application can consume the compressed
275	output when it wants, for example when the output buffer is full (avail_out
276	== 0), or after each call of deflate(). If deflate returns Z_OK and with
277	zero avail_out, it must be called again after making room in the output
278	buffer because there might be more output pending. See deflatePending(),
279	which can be used if desired to determine whether or not there is more ouput
280	in that case.
281
282	Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
283	decide how much data to accumulate before producing output, in order to
284	maximize compression.
285
286	If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
287	flushed to the output buffer and the output is aligned on a byte boundary, so
288	that the decompressor can get all input data available so far. (In
289	particular avail_in is zero after the call if enough output space has been
290	provided before the call.) Flushing may degrade compression for some
291	compression algorithms and so it should be used only when necessary. This
292	completes the current deflate block and follows it with an empty stored block
293	that is three bits plus filler bits to the next byte, followed by four bytes
294	(00 00 ff ff).
295
296	If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
297	output buffer, but the output is not aligned to a byte boundary. All of the
298	input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
299	This completes the current deflate block and follows it with an empty fixed
300	codes block that is 10 bits long. This assures that enough bytes are output
301	in order for the decompressor to finish the block before the empty fixed
302	codes block.
303
304	If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
305	for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
306	seven bits of the current block are held to be written as the next byte after
307	the next deflate block is completed. In this case, the decompressor may not
308	be provided enough bits at this point in order to complete decompression of
309	the data provided so far to the compressor. It may need to wait for the next
310	block to be emitted. This is for advanced applications that need to control
311	the emission of deflate blocks.
312
313	If flush is set to Z_FULL_FLUSH, all output is flushed as with
314	Z_SYNC_FLUSH, and the compression state is reset so that decompression can
315	restart from this point if previous compressed data has been damaged or if
316	random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
317	compression.
318
319	If deflate returns with avail_out == 0, this function must be called again
320	with the same value of the flush parameter and more output space (updated
321	avail_out), until the flush is complete (deflate returns with non-zero
322	avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
323	avail_out is greater than six to avoid repeated flush markers due to
324	avail_out == 0 on return.
325
326	If the parameter flush is set to Z_FINISH, pending input is processed,
327	pending output is flushed and deflate returns with Z_STREAM_END if there was
328	enough output space. If deflate returns with Z_OK or Z_BUF_ERROR, this
329	function must be called again with Z_FINISH and more output space (updated
330	avail_out) but no more input data, until it returns with Z_STREAM_END or an
331	error. After deflate has returned Z_STREAM_END, the only possible operations
332	on the stream are deflateReset or deflateEnd.
333
334	Z_FINISH can be used in the first deflate call after deflateInit if all the
335	compression is to be done in a single step. In order to complete in one
336	call, avail_out must be at least the value returned by deflateBound (see
337	below). Then deflate is guaranteed to return Z_STREAM_END. If not enough
338	output space is provided, deflate will not return Z_STREAM_END, and it must
339	be called again as described above.
340
341	deflate() sets strm->adler to the Adler-32 checksum of all input read
342	so far (that is, total_in bytes). If a gzip stream is being generated, then
343	strm->adler will be the CRC-32 checksum of the input read so far. (See
344	deflateInit2 below.)
345
346	deflate() may update strm->data_type if it can make a good guess about
347	the input data type (Z_BINARY or Z_TEXT). If in doubt, the data is
348	considered binary. This field is only for information purposes and does not
349	affect the compression algorithm in any manner.
350
351	deflate() returns Z_OK if some progress has been made (more input
352	processed or more output produced), Z_STREAM_END if all input has been
353	consumed and all output has been produced (only when flush is set to
354	Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
355	if next_in or next_out was Z_NULL or the state was inadvertently written over
356	by the application), or Z_BUF_ERROR if no progress is possible (for example
357	avail_in or avail_out was zero). Note that Z_BUF_ERROR is not fatal, and
358	deflate() can be called again with more input and more output space to
359	continue compressing.
360	*/
361
362
363	ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
364	/*
365	All dynamically allocated data structures for this stream are freed.
366	This function discards any unprocessed input and does not flush any pending
367	output.
368
369	deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
370	stream state was inconsistent, Z_DATA_ERROR if the stream was freed
371	prematurely (some input or output was discarded). In the error case, msg
372	may be set but then points to a static string (which must not be
373	deallocated).
374	*/
375
376
377	/*
378	ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
379
380	Initializes the internal stream state for decompression. The fields
381	next_in, avail_in, zalloc, zfree and opaque must be initialized before by
382	the caller. In the current version of inflate, the provided input is not
383	read or consumed. The allocation of a sliding window will be deferred to
384	the first call of inflate (if the decompression does not complete on the
385	first call). If zalloc and zfree are set to Z_NULL, inflateInit updates
386	them to use default allocation functions.
387
388	inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
389	memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
390	version assumed by the caller, or Z_STREAM_ERROR if the parameters are
391	invalid, such as a null pointer to the structure. msg is set to null if
392	there is no error message. inflateInit does not perform any decompression.
393	Actual decompression will be done by inflate(). So next_in, and avail_in,
394	next_out, and avail_out are unused and unchanged. The current
395	implementation of inflateInit() does not process any header information --
396	that is deferred until inflate() is called.
397	*/
398
399
400	ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
401	/*
402	inflate decompresses as much data as possible, and stops when the input
403	buffer becomes empty or the output buffer becomes full. It may introduce
404	some output latency (reading input without producing any output) except when
405	forced to flush.
406
407	The detailed semantics are as follows. inflate performs one or both of the
408	following actions:
409
410	- Decompress more input starting at next_in and update next_in and avail_in
411	accordingly. If not all input can be processed (because there is not
412	enough room in the output buffer), then next_in and avail_in are updated
413	accordingly, and processing will resume at this point for the next call of
414	inflate().
415
416	- Generate more output starting at next_out and update next_out and avail_out
417	accordingly. inflate() provides as much output as possible, until there is
418	no more input data or no more space in the output buffer (see below about
419	the flush parameter).
420
421	Before the call of inflate(), the application should ensure that at least
422	one of the actions is possible, by providing more input and/or consuming more
423	output, and updating the next_* and avail_* values accordingly. If the
424	caller of inflate() does not provide both available input and available
425	output space, it is possible that there will be no progress made. The
426	application can consume the uncompressed output when it wants, for example
427	when the output buffer is full (avail_out == 0), or after each call of
428	inflate(). If inflate returns Z_OK and with zero avail_out, it must be
429	called again after making room in the output buffer because there might be
430	more output pending.
431
432	The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
433	Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
434	output as possible to the output buffer. Z_BLOCK requests that inflate()
435	stop if and when it gets to the next deflate block boundary. When decoding
436	the zlib or gzip format, this will cause inflate() to return immediately
437	after the header and before the first block. When doing a raw inflate,
438	inflate() will go ahead and process the first block, and will return when it
439	gets to the end of that block, or when it runs out of data.
440
441	The Z_BLOCK option assists in appending to or combining deflate streams.
442	To assist in this, on return inflate() always sets strm->data_type to the
443	number of unused bits in the last byte taken from strm->next_in, plus 64 if
444	inflate() is currently decoding the last block in the deflate stream, plus
445	128 if inflate() returned immediately after decoding an end-of-block code or
446	decoding the complete header up to just before the first byte of the deflate
447	stream. The end-of-block will not be indicated until all of the uncompressed
448	data from that block has been written to strm->next_out. The number of
449	unused bits may in general be greater than seven, except when bit 7 of
450	data_type is set, in which case the number of unused bits will be less than
451	eight. data_type is set as noted here every time inflate() returns for all
452	flush options, and so can be used to determine the amount of currently
453	consumed input in bits.
454
455	The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
456	end of each deflate block header is reached, before any actual data in that
457	block is decoded. This allows the caller to determine the length of the
458	deflate block header for later use in random access within a deflate block.
459	256 is added to the value of strm->data_type when inflate() returns
460	immediately after reaching the end of the deflate block header.
461
462	inflate() should normally be called until it returns Z_STREAM_END or an
463	error. However if all decompression is to be performed in a single step (a
464	single call of inflate), the parameter flush should be set to Z_FINISH. In
465	this case all pending input is processed and all pending output is flushed;
466	avail_out must be large enough to hold all of the uncompressed data for the
467	operation to complete. (The size of the uncompressed data may have been
468	saved by the compressor for this purpose.) The use of Z_FINISH is not
469	required to perform an inflation in one step. However it may be used to
470	inform inflate that a faster approach can be used for the single inflate()
471	call. Z_FINISH also informs inflate to not maintain a sliding window if the
472	stream completes, which reduces inflate's memory footprint. If the stream
473	does not complete, either because not all of the stream is provided or not
474	enough output space is provided, then a sliding window will be allocated and
475	inflate() can be called again to continue the operation as if Z_NO_FLUSH had
476	been used.
477
478	In this implementation, inflate() always flushes as much output as
479	possible to the output buffer, and always uses the faster approach on the
480	first call. So the effects of the flush parameter in this implementation are
481	on the return value of inflate() as noted below, when inflate() returns early
482	when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
483	memory for a sliding window when Z_FINISH is used.
484
485	If a preset dictionary is needed after this call (see inflateSetDictionary
486	below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
487	chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
488	strm->adler to the Adler-32 checksum of all output produced so far (that is,
489	total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
490	below. At the end of the stream, inflate() checks that its computed Adler-32
491	checksum is equal to that saved by the compressor and returns Z_STREAM_END
492	only if the checksum is correct.
493
494	inflate() can decompress and check either zlib-wrapped or gzip-wrapped
495	deflate data. The header type is detected automatically, if requested when
496	initializing with inflateInit2(). Any information contained in the gzip
497	header is not retained unless inflateGetHeader() is used. When processing
498	gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
499	produced so far. The CRC-32 is checked against the gzip trailer, as is the
500	uncompressed length, modulo 2^32.
501
502	inflate() returns Z_OK if some progress has been made (more input processed
503	or more output produced), Z_STREAM_END if the end of the compressed data has
504	been reached and all uncompressed output has been produced, Z_NEED_DICT if a
505	preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
506	corrupted (input stream not conforming to the zlib format or incorrect check
507	value, in which case strm->msg points to a string with a more specific
508	error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
509	next_in or next_out was Z_NULL, or the state was inadvertently written over
510	by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
511	if no progress was possible or if there was not enough room in the output
512	buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
513	inflate() can be called again with more input and more output space to
514	continue decompressing. If Z_DATA_ERROR is returned, the application may
515	then call inflateSync() to look for a good compression block if a partial
516	recovery of the data is to be attempted.
517	*/
518
519
520	ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
521	/*
522	All dynamically allocated data structures for this stream are freed.
523	This function discards any unprocessed input and does not flush any pending
524	output.
525
526	inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
527	was inconsistent.
528	*/
529
530
531	/* Advanced functions */
532
533	/*
534	The following functions are needed only in some special applications.
535	*/
536
537	/*
538	ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
539	int level,
540	int method,
541	int windowBits,
542	int memLevel,
543	int strategy));
544
545	This is another version of deflateInit with more compression options. The
546	fields next_in, zalloc, zfree and opaque must be initialized before by the
547	caller.
548
549	The method parameter is the compression method. It must be Z_DEFLATED in
550	this version of the library.
551
552	The windowBits parameter is the base two logarithm of the window size
553	(the size of the history buffer). It should be in the range 8..15 for this
554	version of the library. Larger values of this parameter result in better
555	compression at the expense of memory usage. The default value is 15 if
556	deflateInit is used instead.
557
558	For the current implementation of deflate(), a windowBits value of 8 (a
559	window size of 256 bytes) is not supported. As a result, a request for 8
560	will result in 9 (a 512-byte window). In that case, providing 8 to
561	inflateInit2() will result in an error when the zlib header with 9 is
562	checked against the initialization of inflate(). The remedy is to not use 8
563	with deflateInit2() with this initialization, or at least in that case use 9
564	with inflateInit2().
565
566	windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
567	determines the window size. deflate() will then generate raw deflate data
568	with no zlib header or trailer, and will not compute a check value.
569
570	windowBits can also be greater than 15 for optional gzip encoding. Add
571	16 to windowBits to write a simple gzip header and trailer around the
572	compressed data instead of a zlib wrapper. The gzip header will have no
573	file name, no extra data, no comment, no modification time (set to zero), no
574	header crc, and the operating system will be set to the appropriate value,
575	if the operating system was determined at compile time. If a gzip stream is
576	being written, strm->adler is a CRC-32 instead of an Adler-32.
577
578	For raw deflate or gzip encoding, a request for a 256-byte window is
579	rejected as invalid, since only the zlib header provides a means of
580	transmitting the window size to the decompressor.
581
582	The memLevel parameter specifies how much memory should be allocated
583	for the internal compression state. memLevel=1 uses minimum memory but is
584	slow and reduces compression ratio; memLevel=9 uses maximum memory for
585	optimal speed. The default value is 8. See zconf.h for total memory usage
586	as a function of windowBits and memLevel.
587
588	The strategy parameter is used to tune the compression algorithm. Use the
589	value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
590	filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
591	string match), or Z_RLE to limit match distances to one (run-length
592	encoding). Filtered data consists mostly of small values with a somewhat
593	random distribution. In this case, the compression algorithm is tuned to
594	compress them better. The effect of Z_FILTERED is to force more Huffman
595	coding and less string matching; it is somewhat intermediate between
596	Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
597	fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
598	strategy parameter only affects the compression ratio but not the
599	correctness of the compressed output even if it is not set appropriately.
600	Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
601	decoder for special applications.
602
603	deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
604	memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
605	method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
606	incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
607	set to null if there is no error message. deflateInit2 does not perform any
608	compression: this will be done by deflate().
609	*/
610
611	ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
612	const Bytef *dictionary,
613	uInt dictLength));
614	/*
615	Initializes the compression dictionary from the given byte sequence
616	without producing any compressed output. When using the zlib format, this
617	function must be called immediately after deflateInit, deflateInit2 or
618	deflateReset, and before any call of deflate. When doing raw deflate, this
619	function must be called either before any call of deflate, or immediately
620	after the completion of a deflate block, i.e. after all input has been
621	consumed and all output has been delivered when using any of the flush
622	options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
623	compressor and decompressor must use exactly the same dictionary (see
624	inflateSetDictionary).
625
626	The dictionary should consist of strings (byte sequences) that are likely
627	to be encountered later in the data to be compressed, with the most commonly
628	used strings preferably put towards the end of the dictionary. Using a
629	dictionary is most useful when the data to be compressed is short and can be
630	predicted with good accuracy; the data can then be compressed better than
631	with the default empty dictionary.
632
633	Depending on the size of the compression data structures selected by
634	deflateInit or deflateInit2, a part of the dictionary may in effect be
635	discarded, for example if the dictionary is larger than the window size
636	provided in deflateInit or deflateInit2. Thus the strings most likely to be
637	useful should be put at the end of the dictionary, not at the front. In
638	addition, the current implementation of deflate will use at most the window
639	size minus 262 bytes of the provided dictionary.
640
641	Upon return of this function, strm->adler is set to the Adler-32 value
642	of the dictionary; the decompressor may later use this value to determine
643	which dictionary has been used by the compressor. (The Adler-32 value
644	applies to the whole dictionary even if only a subset of the dictionary is
645	actually used by the compressor.) If a raw deflate was requested, then the
646	Adler-32 value is not computed and strm->adler is not set.
647
648	deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
649	parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
650	inconsistent (for example if deflate has already been called for this stream
651	or if not at a block boundary for raw deflate). deflateSetDictionary does
652	not perform any compression: this will be done by deflate().
653	*/
654
655	ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
656	Bytef *dictionary,
657	uInt *dictLength));
658	/*
659	Returns the sliding dictionary being maintained by deflate. dictLength is
660	set to the number of bytes in the dictionary, and that many bytes are copied
661	to dictionary. dictionary must have enough space, where 32768 bytes is
662	always enough. If deflateGetDictionary() is called with dictionary equal to
663	Z_NULL, then only the dictionary length is returned, and nothing is copied.
664	Similary, if dictLength is Z_NULL, then it is not set.
665
666	deflateGetDictionary() may return a length less than the window size, even
667	when more than the window size in input has been provided. It may return up
668	to 258 bytes less in that case, due to how zlib's implementation of deflate
669	manages the sliding window and lookahead for matches, where matches can be
670	up to 258 bytes long. If the application needs the last window-size bytes of
671	input, then that would need to be saved by the application outside of zlib.
672
673	deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
674	stream state is inconsistent.
675	*/
676
677	ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
678	z_streamp source));
679	/*
680	Sets the destination stream as a complete copy of the source stream.
681
682	This function can be useful when several compression strategies will be
683	tried, for example when there are several ways of pre-processing the input
684	data with a filter. The streams that will be discarded should then be freed
685	by calling deflateEnd. Note that deflateCopy duplicates the internal
686	compression state which can be quite large, so this strategy is slow and can
687	consume lots of memory.
688
689	deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
690	enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
691	(such as zalloc being Z_NULL). msg is left unchanged in both source and
692	destination.
693	*/
694
695	ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
696	/*
697	This function is equivalent to deflateEnd followed by deflateInit, but
698	does not free and reallocate the internal compression state. The stream
699	will leave the compression level and any other attributes that may have been
700	set unchanged.
701
702	deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
703	stream state was inconsistent (such as zalloc or state being Z_NULL).
704	*/
705
706	ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
707	int level,
708	int strategy));
709	/*
710	Dynamically update the compression level and compression strategy. The
711	interpretation of level and strategy is as in deflateInit2(). This can be
712	used to switch between compression and straight copy of the input data, or
713	to switch to a different kind of input data requiring a different strategy.
714	If the compression approach (which is a function of the level) or the
715	strategy is changed, and if any input has been consumed in a previous
716	deflate() call, then the input available so far is compressed with the old
717	level and strategy using deflate(strm, Z_BLOCK). There are three approaches
718	for the compression levels 0, 1..3, and 4..9 respectively. The new level
719	and strategy will take effect at the next call of deflate().
720
721	If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
722	not have enough output space to complete, then the parameter change will not
723	take effect. In this case, deflateParams() can be called again with the
724	same parameters and more output space to try again.
725
726	In order to assure a change in the parameters on the first try, the
727	deflate stream should be flushed using deflate() with Z_BLOCK or other flush
728	request until strm.avail_out is not zero, before calling deflateParams().
729	Then no more input data should be provided before the deflateParams() call.
730	If this is done, the old level and strategy will be applied to the data
731	compressed before deflateParams(), and the new level and strategy will be
732	applied to the the data compressed after deflateParams().
733
734	deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
735	state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
736	there was not enough output space to complete the compression of the
737	available input data before a change in the strategy or approach. Note that
738	in the case of a Z_BUF_ERROR, the parameters are not changed. A return
739	value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
740	retried with more output space.
741	*/
742
743	ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
744	int good_length,
745	int max_lazy,
746	int nice_length,
747	int max_chain));
748	/*
749	Fine tune deflate's internal compression parameters. This should only be
750	used by someone who understands the algorithm used by zlib's deflate for
751	searching for the best matching string, and even then only by the most
752	fanatic optimizer trying to squeeze out the last compressed bit for their
753	specific input data. Read the deflate.c source code for the meaning of the
754	max_lazy, good_length, nice_length, and max_chain parameters.
755
756	deflateTune() can be called after deflateInit() or deflateInit2(), and
757	returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
758	*/
759
760	ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
761	uLong sourceLen));
762	/*
763	deflateBound() returns an upper bound on the compressed size after
764	deflation of sourceLen bytes. It must be called after deflateInit() or
765	deflateInit2(), and after deflateSetHeader(), if used. This would be used
766	to allocate an output buffer for deflation in a single pass, and so would be
767	called before deflate(). If that first deflate() call is provided the
768	sourceLen input bytes, an output buffer allocated to the size returned by
769	deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
770	to return Z_STREAM_END. Note that it is possible for the compressed size to
771	be larger than the value returned by deflateBound() if flush options other
772	than Z_FINISH or Z_NO_FLUSH are used.
773	*/
774
775	ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
776	unsigned *pending,
777	int *bits));
778	/*
779	deflatePending() returns the number of bytes and bits of output that have
780	been generated, but not yet provided in the available output. The bytes not
781	provided would be due to the available output space having being consumed.
782	The number of bits of output not provided are between 0 and 7, where they
783	await more bits to join them in order to fill out a full byte. If pending
784	or bits are Z_NULL, then those values are not set.
785
786	deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
787	stream state was inconsistent.
788	*/
789
790	ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
791	int bits,
792	int value));
793	/*
794	deflatePrime() inserts bits in the deflate output stream. The intent
795	is that this function is used to start off the deflate output with the bits
796	leftover from a previous deflate stream when appending to it. As such, this
797	function can only be used for raw deflate, and must be used before the first
798	deflate() call after a deflateInit2() or deflateReset(). bits must be less
799	than or equal to 16, and that many of the least significant bits of value
800	will be inserted in the output.
801
802	deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
803	room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
804	source stream state was inconsistent.
805	*/
806
807	ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
808	gz_headerp head));
809	/*
810	deflateSetHeader() provides gzip header information for when a gzip
811	stream is requested by deflateInit2(). deflateSetHeader() may be called
812	after deflateInit2() or deflateReset() and before the first call of
813	deflate(). The text, time, os, extra field, name, and comment information
814	in the provided gz_header structure are written to the gzip header (xflag is
815	ignored -- the extra flags are set according to the compression level). The
816	caller must assure that, if not Z_NULL, name and comment are terminated with
817	a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
818	available there. If hcrc is true, a gzip header crc is included. Note that
819	the current versions of the command-line version of gzip (up through version
820	1.3.x) do not support header crc's, and will report that it is a "multi-part
821	gzip file" and give up.
822
823	If deflateSetHeader is not used, the default gzip header has text false,
824	the time set to zero, and os set to 255, with no extra, name, or comment
825	fields. The gzip header is returned to the default state by deflateReset().
826
827	deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
828	stream state was inconsistent.
829	*/
830
831	/*
832	ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
833	int windowBits));
834
835	This is another version of inflateInit with an extra parameter. The
836	fields next_in, avail_in, zalloc, zfree and opaque must be initialized
837	before by the caller.
838
839	The windowBits parameter is the base two logarithm of the maximum window
840	size (the size of the history buffer). It should be in the range 8..15 for
841	this version of the library. The default value is 15 if inflateInit is used
842	instead. windowBits must be greater than or equal to the windowBits value
843	provided to deflateInit2() while compressing, or it must be equal to 15 if
844	deflateInit2() was not used. If a compressed stream with a larger window
845	size is given as input, inflate() will return with the error code
846	Z_DATA_ERROR instead of trying to allocate a larger window.
847
848	windowBits can also be zero to request that inflate use the window size in
849	the zlib header of the compressed stream.
850
851	windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
852	determines the window size. inflate() will then process raw deflate data,
853	not looking for a zlib or gzip header, not generating a check value, and not
854	looking for any check values for comparison at the end of the stream. This
855	is for use with other formats that use the deflate compressed data format
856	such as zip. Those formats provide their own check values. If a custom
857	format is developed using the raw deflate format for compressed data, it is
858	recommended that a check value such as an Adler-32 or a CRC-32 be applied to
859	the uncompressed data as is done in the zlib, gzip, and zip formats. For
860	most applications, the zlib format should be used as is. Note that comments
861	above on the use in deflateInit2() applies to the magnitude of windowBits.
862
863	windowBits can also be greater than 15 for optional gzip decoding. Add
864	32 to windowBits to enable zlib and gzip decoding with automatic header
865	detection, or add 16 to decode only the gzip format (the zlib format will
866	return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
867	CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see
868	below), inflate() will not automatically decode concatenated gzip streams.
869	inflate() will return Z_STREAM_END at the end of the gzip stream. The state
870	would need to be reset to continue decoding a subsequent gzip stream.
871
872	inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
873	memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
874	version assumed by the caller, or Z_STREAM_ERROR if the parameters are
875	invalid, such as a null pointer to the structure. msg is set to null if
876	there is no error message. inflateInit2 does not perform any decompression
877	apart from possibly reading the zlib header if present: actual decompression
878	will be done by inflate(). (So next_in and avail_in may be modified, but
879	next_out and avail_out are unused and unchanged.) The current implementation
880	of inflateInit2() does not process any header information -- that is
881	deferred until inflate() is called.
882	*/
883
884	ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
885	const Bytef *dictionary,
886	uInt dictLength));
887	/*
888	Initializes the decompression dictionary from the given uncompressed byte
889	sequence. This function must be called immediately after a call of inflate,
890	if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
891	can be determined from the Adler-32 value returned by that call of inflate.
892	The compressor and decompressor must use exactly the same dictionary (see
893	deflateSetDictionary). For raw inflate, this function can be called at any
894	time to set the dictionary. If the provided dictionary is smaller than the
895	window and there is already data in the window, then the provided dictionary
896	will amend what's there. The application must insure that the dictionary
897	that was used for compression is provided.
898
899	inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
900	parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
901	inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
902	expected one (incorrect Adler-32 value). inflateSetDictionary does not
903	perform any decompression: this will be done by subsequent calls of
904	inflate().
905	*/
906
907	ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
908	Bytef *dictionary,
909	uInt *dictLength));
910	/*
911	Returns the sliding dictionary being maintained by inflate. dictLength is
912	set to the number of bytes in the dictionary, and that many bytes are copied
913	to dictionary. dictionary must have enough space, where 32768 bytes is
914	always enough. If inflateGetDictionary() is called with dictionary equal to
915	Z_NULL, then only the dictionary length is returned, and nothing is copied.
916	Similary, if dictLength is Z_NULL, then it is not set.
917
918	inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
919	stream state is inconsistent.
920	*/
921
922	ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
923	/*
924	Skips invalid compressed data until a possible full flush point (see above
925	for the description of deflate with Z_FULL_FLUSH) can be found, or until all
926	available input is skipped. No output is provided.
927
928	inflateSync searches for a 00 00 FF FF pattern in the compressed data.
929	All full flush points have this pattern, but not all occurrences of this
930	pattern are full flush points.
931
932	inflateSync returns Z_OK if a possible full flush point has been found,
933	Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
934	has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
935	In the success case, the application may save the current current value of
936	total_in which indicates where valid compressed data was found. In the
937	error case, the application may repeatedly call inflateSync, providing more
938	input each time, until success or end of the input data.
939	*/
940
941	ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
942	z_streamp source));
943	/*
944	Sets the destination stream as a complete copy of the source stream.
945
946	This function can be useful when randomly accessing a large stream. The
947	first pass through the stream can periodically record the inflate state,
948	allowing restarting inflate at those points when randomly accessing the
949	stream.
950
951	inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
952	enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
953	(such as zalloc being Z_NULL). msg is left unchanged in both source and
954	destination.
955	*/
956
957	ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
958	/*
959	This function is equivalent to inflateEnd followed by inflateInit,
960	but does not free and reallocate the internal decompression state. The
961	stream will keep attributes that may have been set by inflateInit2.
962
963	inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
964	stream state was inconsistent (such as zalloc or state being Z_NULL).
965	*/
966
967	ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
968	int windowBits));
969	/*
970	This function is the same as inflateReset, but it also permits changing
971	the wrap and window size requests. The windowBits parameter is interpreted
972	the same as it is for inflateInit2. If the window size is changed, then the
973	memory allocated for the window is freed, and the window will be reallocated
974	by inflate() if needed.
975
976	inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
977	stream state was inconsistent (such as zalloc or state being Z_NULL), or if
978	the windowBits parameter is invalid.
979	*/
980
981	ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
982	int bits,
983	int value));
984	/*
985	This function inserts bits in the inflate input stream. The intent is
986	that this function is used to start inflating at a bit position in the
987	middle of a byte. The provided bits will be used before any bytes are used
988	from next_in. This function should only be used with raw inflate, and
989	should be used before the first inflate() call after inflateInit2() or
990	inflateReset(). bits must be less than or equal to 16, and that many of the
991	least significant bits of value will be inserted in the input.
992
993	If bits is negative, then the input stream bit buffer is emptied. Then
994	inflatePrime() can be called again to put bits in the buffer. This is used
995	to clear out bits leftover after feeding inflate a block description prior
996	to feeding inflate codes.
997
998	inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
999	stream state was inconsistent.
1000	*/
1001
1002	ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
1003	/*
1004	This function returns two values, one in the lower 16 bits of the return
1005	value, and the other in the remaining upper bits, obtained by shifting the
1006	return value down 16 bits. If the upper value is -1 and the lower value is
1007	zero, then inflate() is currently decoding information outside of a block.
1008	If the upper value is -1 and the lower value is non-zero, then inflate is in
1009	the middle of a stored block, with the lower value equaling the number of
1010	bytes from the input remaining to copy. If the upper value is not -1, then
1011	it is the number of bits back from the current bit position in the input of
1012	the code (literal or length/distance pair) currently being processed. In
1013	that case the lower value is the number of bytes already emitted for that
1014	code.
1015
1016	A code is being processed if inflate is waiting for more input to complete
1017	decoding of the code, or if it has completed decoding but is waiting for
1018	more output space to write the literal or match data.
1019
1020	inflateMark() is used to mark locations in the input data for random
1021	access, which may be at bit positions, and to note those cases where the
1022	output of a code may span boundaries of random access blocks. The current
1023	location in the input stream can be determined from avail_in and data_type
1024	as noted in the description for the Z_BLOCK flush parameter for inflate.
1025
1026	inflateMark returns the value noted above, or -65536 if the provided
1027	source stream state was inconsistent.
1028	*/
1029
1030	ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1031	gz_headerp head));
1032	/*
1033	inflateGetHeader() requests that gzip header information be stored in the
1034	provided gz_header structure. inflateGetHeader() may be called after
1035	inflateInit2() or inflateReset(), and before the first call of inflate().
1036	As inflate() processes the gzip stream, head->done is zero until the header
1037	is completed, at which time head->done is set to one. If a zlib stream is
1038	being decoded, then head->done is set to -1 to indicate that there will be
1039	no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
1040	used to force inflate() to return immediately after header processing is
1041	complete and before any actual data is decompressed.
1042
1043	The text, time, xflags, and os fields are filled in with the gzip header
1044	contents. hcrc is set to true if there is a header CRC. (The header CRC
1045	was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1046	contains the maximum number of bytes to write to extra. Once done is true,
1047	extra_len contains the actual extra field length, and extra contains the
1048	extra field, or that field truncated if extra_max is less than extra_len.
1049	If name is not Z_NULL, then up to name_max characters are written there,
1050	terminated with a zero unless the length is greater than name_max. If
1051	comment is not Z_NULL, then up to comm_max characters are written there,
1052	terminated with a zero unless the length is greater than comm_max. When any
1053	of extra, name, or comment are not Z_NULL and the respective field is not
1054	present in the header, then that field is set to Z_NULL to signal its
1055	absence. This allows the use of deflateSetHeader() with the returned
1056	structure to duplicate the header. However if those fields are set to
1057	allocated memory, then the application will need to save those pointers
1058	elsewhere so that they can be eventually freed.
1059
1060	If inflateGetHeader is not used, then the header information is simply
1061	discarded. The header is always checked for validity, including the header
1062	CRC if present. inflateReset() will reset the process to discard the header
1063	information. The application would need to call inflateGetHeader() again to
1064	retrieve the header from the next gzip stream.
1065
1066	inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1067	stream state was inconsistent.
1068	*/
1069
1070	/*
1071	ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1072	unsigned char FAR *window));
1073
1074	Initialize the internal stream state for decompression using inflateBack()
1075	calls. The fields zalloc, zfree and opaque in strm must be initialized
1076	before the call. If zalloc and zfree are Z_NULL, then the default library-
1077	derived memory allocation routines are used. windowBits is the base two
1078	logarithm of the window size, in the range 8..15. window is a caller
1079	supplied buffer of that size. Except for special applications where it is
1080	assured that deflate was used with small window sizes, windowBits must be 15
1081	and a 32K byte window must be supplied to be able to decompress general
1082	deflate streams.
1083
1084	See inflateBack() for the usage of these routines.
1085
1086	inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1087	the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1088	allocated, or Z_VERSION_ERROR if the version of the library does not match
1089	the version of the header file.
1090	*/
1091
1092	typedef unsigned (*in_func) OF((void FAR *,
1093	z_const unsigned char FAR * FAR *));
1094	typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1095
1096	ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1097	in_func in, void FAR *in_desc,
1098	out_func out, void FAR *out_desc));
1099	/*
1100	inflateBack() does a raw inflate with a single call using a call-back
1101	interface for input and output. This is potentially more efficient than
1102	inflate() for file i/o applications, in that it avoids copying between the
1103	output and the sliding window by simply making the window itself the output
1104	buffer. inflate() can be faster on modern CPUs when used with large
1105	buffers. inflateBack() trusts the application to not change the output
1106	buffer passed by the output function, at least until inflateBack() returns.
1107
1108	inflateBackInit() must be called first to allocate the internal state
1109	and to initialize the state with the user-provided window buffer.
1110	inflateBack() may then be used multiple times to inflate a complete, raw
1111	deflate stream with each call. inflateBackEnd() is then called to free the
1112	allocated state.
1113
1114	A raw deflate stream is one with no zlib or gzip header or trailer.
1115	This routine would normally be used in a utility that reads zip or gzip
1116	files and writes out uncompressed files. The utility would decode the
1117	header and process the trailer on its own, hence this routine expects only
1118	the raw deflate stream to decompress. This is different from the default
1119	behavior of inflate(), which expects a zlib header and trailer around the
1120	deflate stream.
1121
1122	inflateBack() uses two subroutines supplied by the caller that are then
1123	called by inflateBack() for input and output. inflateBack() calls those
1124	routines until it reads a complete deflate stream and writes out all of the
1125	uncompressed data, or until it encounters an error. The function's
1126	parameters and return types are defined above in the in_func and out_func
1127	typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1128	number of bytes of provided input, and a pointer to that input in buf. If
1129	there is no input available, in() must return zero -- buf is ignored in that
1130	case -- and inflateBack() will return a buffer error. inflateBack() will
1131	call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1132	out() should return zero on success, or non-zero on failure. If out()
1133	returns non-zero, inflateBack() will return with an error. Neither in() nor
1134	out() are permitted to change the contents of the window provided to
1135	inflateBackInit(), which is also the buffer that out() uses to write from.
1136	The length written by out() will be at most the window size. Any non-zero
1137	amount of input may be provided by in().
1138
1139	For convenience, inflateBack() can be provided input on the first call by
1140	setting strm->next_in and strm->avail_in. If that input is exhausted, then
1141	in() will be called. Therefore strm->next_in must be initialized before
1142	calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1143	immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1144	must also be initialized, and then if strm->avail_in is not zero, input will
1145	initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1146
1147	The in_desc and out_desc parameters of inflateBack() is passed as the
1148	first parameter of in() and out() respectively when they are called. These
1149	descriptors can be optionally used to pass any information that the caller-
1150	supplied in() and out() functions need to do their job.
1151
1152	On return, inflateBack() will set strm->next_in and strm->avail_in to
1153	pass back any unused input that was provided by the last in() call. The
1154	return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1155	if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1156	in the deflate stream (in which case strm->msg is set to indicate the nature
1157	of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1158	In the case of Z_BUF_ERROR, an input or output error can be distinguished
1159	using strm->next_in which will be Z_NULL only if in() returned an error. If
1160	strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1161	non-zero. (in() will always be called before out(), so strm->next_in is
1162	assured to be defined if out() returns non-zero.) Note that inflateBack()
1163	cannot return Z_OK.
1164	*/
1165
1166	ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1167	/*
1168	All memory allocated by inflateBackInit() is freed.
1169
1170	inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1171	state was inconsistent.
1172	*/
1173
1174	ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1175	/* Return flags indicating compile-time options.
1176
1177	Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1178	1.0: size of uInt
1179	3.2: size of uLong
1180	5.4: size of voidpf (pointer)
1181	7.6: size of z_off_t
1182
1183	Compiler, assembler, and debug options:
1184	8: ZLIB_DEBUG
1185	9: ASMV or ASMINF -- use ASM code
1186	10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1187	11: 0 (reserved)
1188
1189	One-time table building (smaller code, but not thread-safe if true):
1190	12: BUILDFIXED -- build static block decoding tables when needed
1191	13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1192	14,15: 0 (reserved)
1193
1194	Library content (indicates missing functionality):
1195	16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1196	deflate code when not needed)
1197	17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1198	and decode gzip streams (to avoid linking crc code)
1199	18-19: 0 (reserved)
1200
1201	Operation variations (changes in library functionality):
1202	20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1203	21: FASTEST -- deflate algorithm with only one, lowest compression level
1204	22,23: 0 (reserved)
1205
1206	The sprintf variant used by gzprintf (zero is best):
1207	24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1208	25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1209	26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1210
1211	Remainder:
1212	27-31: 0 (reserved)
1213	*/
1214
1215	#ifndef Z_SOLO
1216
1217	/* utility functions */
1218
1219	/*
1220	The following utility functions are implemented on top of the basic
1221	stream-oriented functions. To simplify the interface, some default options
1222	are assumed (compression level and memory usage, standard memory allocation
1223	functions). The source code of these utility functions can be modified if
1224	you need special options.
1225	*/
1226
1227	ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1228	const Bytef *source, uLong sourceLen));
1229	/*
1230	Compresses the source buffer into the destination buffer. sourceLen is
1231	the byte length of the source buffer. Upon entry, destLen is the total size
1232	of the destination buffer, which must be at least the value returned by
1233	compressBound(sourceLen). Upon exit, destLen is the actual size of the
1234	compressed data. compress() is equivalent to compress2() with a level
1235	parameter of Z_DEFAULT_COMPRESSION.
1236
1237	compress returns Z_OK if success, Z_MEM_ERROR if there was not
1238	enough memory, Z_BUF_ERROR if there was not enough room in the output
1239	buffer.
1240	*/
1241
1242	ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1243	const Bytef *source, uLong sourceLen,
1244	int level));
1245	/*
1246	Compresses the source buffer into the destination buffer. The level
1247	parameter has the same meaning as in deflateInit. sourceLen is the byte
1248	length of the source buffer. Upon entry, destLen is the total size of the
1249	destination buffer, which must be at least the value returned by
1250	compressBound(sourceLen). Upon exit, destLen is the actual size of the
1251	compressed data.
1252
1253	compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1254	memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1255	Z_STREAM_ERROR if the level parameter is invalid.
1256	*/
1257
1258	ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1259	/*
1260	compressBound() returns an upper bound on the compressed size after
1261	compress() or compress2() on sourceLen bytes. It would be used before a
1262	compress() or compress2() call to allocate the destination buffer.
1263	*/
1264
1265	ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1266	const Bytef *source, uLong sourceLen));
1267	/*
1268	Decompresses the source buffer into the destination buffer. sourceLen is
1269	the byte length of the source buffer. Upon entry, destLen is the total size
1270	of the destination buffer, which must be large enough to hold the entire
1271	uncompressed data. (The size of the uncompressed data must have been saved
1272	previously by the compressor and transmitted to the decompressor by some
1273	mechanism outside the scope of this compression library.) Upon exit, destLen
1274	is the actual size of the uncompressed data.
1275
1276	uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1277	enough memory, Z_BUF_ERROR if there was not enough room in the output
1278	buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1279	the case where there is not enough room, uncompress() will fill the output
1280	buffer with the uncompressed data up to that point.
1281	*/
1282
1283	ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest, uLongf *destLen,
1284	const Bytef *source, uLong *sourceLen));
1285	/*
1286	Same as uncompress, except that sourceLen is a pointer, where the
1287	length of the source is *sourceLen. On return, *sourceLen is the number of
1288	source bytes consumed.
1289	*/
1290
1291	/* gzip file access functions */
1292
1293	/*
1294	This library supports reading and writing files in gzip (.gz) format with
1295	an interface similar to that of stdio, using the functions that start with
1296	"gz". The gzip format is different from the zlib format. gzip is a gzip
1297	wrapper, documented in RFC 1952, wrapped around a deflate stream.
1298	*/
1299
1300	typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1301
1302	/*
1303	ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1304
1305	Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1306	in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1307	a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1308	compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1309	for fixed code compression as in "wb9F". (See the description of
1310	deflateInit2 for more information about the strategy parameter.) 'T' will
1311	request transparent writing or appending with no compression and not using
1312	the gzip format.
1313
1314	"a" can be used instead of "w" to request that the gzip stream that will
1315	be written be appended to the file. "+" will result in an error, since
1316	reading and writing to the same gzip file is not supported. The addition of
1317	"x" when writing will create the file exclusively, which fails if the file
1318	already exists. On systems that support it, the addition of "e" when
1319	reading or writing will set the flag to close the file on an execve() call.
1320
1321	These functions, as well as gzip, will read and decode a sequence of gzip
1322	streams in a file. The append function of gzopen() can be used to create
1323	such a file. (Also see gzflush() for another way to do this.) When
1324	appending, gzopen does not test whether the file begins with a gzip stream,
1325	nor does it look for the end of the gzip streams to begin appending. gzopen
1326	will simply append a gzip stream to the existing file.
1327
1328	gzopen can be used to read a file which is not in gzip format; in this
1329	case gzread will directly read from the file without decompression. When
1330	reading, this will be detected automatically by looking for the magic two-
1331	byte gzip header.
1332
1333	gzopen returns NULL if the file could not be opened, if there was
1334	insufficient memory to allocate the gzFile state, or if an invalid mode was
1335	specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1336	errno can be checked to determine if the reason gzopen failed was that the
1337	file could not be opened.
1338	*/
1339
1340	ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1341	/*
1342	gzdopen associates a gzFile with the file descriptor fd. File descriptors
1343	are obtained from calls like open, dup, creat, pipe or fileno (if the file
1344	has been previously opened with fopen). The mode parameter is as in gzopen.
1345
1346	The next call of gzclose on the returned gzFile will also close the file
1347	descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1348	fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1349	mode);. The duplicated descriptor should be saved to avoid a leak, since
1350	gzdopen does not close fd if it fails. If you are using fileno() to get the
1351	file descriptor from a FILE *, then you will have to use dup() to avoid
1352	double-close()ing the file descriptor. Both gzclose() and fclose() will
1353	close the associated file descriptor, so they need to have different file
1354	descriptors.
1355
1356	gzdopen returns NULL if there was insufficient memory to allocate the
1357	gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1358	provided, or '+' was provided), or if fd is -1. The file descriptor is not
1359	used until the next gz* read, write, seek, or close operation, so gzdopen
1360	will not detect if fd is invalid (unless fd is -1).
1361	*/
1362
1363	ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1364	/*
1365	Set the internal buffer size used by this library's functions. The
1366	default buffer size is 8192 bytes. This function must be called after
1367	gzopen() or gzdopen(), and before any other calls that read or write the
1368	file. The buffer memory allocation is always deferred to the first read or
1369	write. Three times that size in buffer space is allocated. A larger buffer
1370	size of, for example, 64K or 128K bytes will noticeably increase the speed
1371	of decompression (reading).
1372
1373	The new buffer size also affects the maximum length for gzprintf().
1374
1375	gzbuffer() returns 0 on success, or -1 on failure, such as being called
1376	too late.
1377	*/
1378
1379	ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1380	/*
1381	Dynamically update the compression level or strategy. See the description
1382	of deflateInit2 for the meaning of these parameters. Previously provided
1383	data is flushed before the parameter change.
1384
1385	gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1386	opened for writing, Z_ERRNO if there is an error writing the flushed data,
1387	or Z_MEM_ERROR if there is a memory allocation error.
1388	*/
1389
1390	ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1391	/*
1392	Reads the given number of uncompressed bytes from the compressed file. If
1393	the input file is not in gzip format, gzread copies the given number of
1394	bytes into the buffer directly from the file.
1395
1396	After reaching the end of a gzip stream in the input, gzread will continue
1397	to read, looking for another gzip stream. Any number of gzip streams may be
1398	concatenated in the input file, and will all be decompressed by gzread().
1399	If something other than a gzip stream is encountered after a gzip stream,
1400	that remaining trailing garbage is ignored (and no error is returned).
1401
1402	gzread can be used to read a gzip file that is being concurrently written.
1403	Upon reaching the end of the input, gzread will return with the available
1404	data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1405	gzclearerr can be used to clear the end of file indicator in order to permit
1406	gzread to be tried again. Z_OK indicates that a gzip stream was completed
1407	on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1408	middle of a gzip stream. Note that gzread does not return -1 in the event
1409	of an incomplete gzip stream. This error is deferred until gzclose(), which
1410	will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1411	stream. Alternatively, gzerror can be used before gzclose to detect this
1412	case.
1413
1414	gzread returns the number of uncompressed bytes actually read, less than
1415	len for end of file, or -1 for error. If len is too large to fit in an int,
1416	then nothing is read, -1 is returned, and the error state is set to
1417	Z_STREAM_ERROR.
1418	*/
1419
1420	ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
1421	gzFile file));
1422	/*
1423	Read up to nitems items of size size from file to buf, otherwise operating
1424	as gzread() does. This duplicates the interface of stdio's fread(), with
1425	size_t request and return types. If the library defines size_t, then
1426	z_size_t is identical to size_t. If not, then z_size_t is an unsigned
1427	integer type that can contain a pointer.
1428
1429	gzfread() returns the number of full items read of size size, or zero if
1430	the end of the file was reached and a full item could not be read, or if
1431	there was an error. gzerror() must be consulted if zero is returned in
1432	order to determine if there was an error. If the multiplication of size and
1433	nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1434	is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1435
1436	In the event that the end of file is reached and only a partial item is
1437	available at the end, i.e. the remaining uncompressed data length is not a
1438	multiple of size, then the final partial item is nevetheless read into buf
1439	and the end-of-file flag is set. The length of the partial item read is not
1440	provided, but could be inferred from the result of gztell(). This behavior
1441	is the same as the behavior of fread() implementations in common libraries,
1442	but it prevents the direct use of gzfread() to read a concurrently written
1443	file, reseting and retrying on end-of-file, when size is not 1.
1444	*/
1445
1446	ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1447	voidpc buf, unsigned len));
1448	/*
1449	Writes the given number of uncompressed bytes into the compressed file.
1450	gzwrite returns the number of uncompressed bytes written or 0 in case of
1451	error.
1452	*/
1453
1454	ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
1455	z_size_t nitems, gzFile file));
1456	/*
1457	gzfwrite() writes nitems items of size size from buf to file, duplicating
1458	the interface of stdio's fwrite(), with size_t request and return types. If
1459	the library defines size_t, then z_size_t is identical to size_t. If not,
1460	then z_size_t is an unsigned integer type that can contain a pointer.
1461
1462	gzfwrite() returns the number of full items written of size size, or zero
1463	if there was an error. If the multiplication of size and nitems overflows,
1464	i.e. the product does not fit in a z_size_t, then nothing is written, zero
1465	is returned, and the error state is set to Z_STREAM_ERROR.
1466	*/
1467
1468	ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1469	/*
1470	Converts, formats, and writes the arguments to the compressed file under
1471	control of the format string, as in fprintf. gzprintf returns the number of
1472	uncompressed bytes actually written, or a negative zlib error code in case
1473	of error. The number of uncompressed bytes written is limited to 8191, or
1474	one less than the buffer size given to gzbuffer(). The caller should assure
1475	that this limit is not exceeded. If it is exceeded, then gzprintf() will
1476	return an error (0) with nothing written. In this case, there may also be a
1477	buffer overflow with unpredictable consequences, which is possible only if
1478	zlib was compiled with the insecure functions sprintf() or vsprintf()
1479	because the secure snprintf() or vsnprintf() functions were not available.
1480	This can be determined using zlibCompileFlags().
1481	*/
1482
1483	ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1484	/*
1485	Writes the given null-terminated string to the compressed file, excluding
1486	the terminating null character.
1487
1488	gzputs returns the number of characters written, or -1 in case of error.
1489	*/
1490
1491	ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1492	/*
1493	Reads bytes from the compressed file until len-1 characters are read, or a
1494	newline character is read and transferred to buf, or an end-of-file
1495	condition is encountered. If any characters are read or if len == 1, the
1496	string is terminated with a null character. If no characters are read due
1497	to an end-of-file or len < 1, then the buffer is left untouched.
1498
1499	gzgets returns buf which is a null-terminated string, or it returns NULL
1500	for end-of-file or in case of error. If there was an error, the contents at
1501	buf are indeterminate.
1502	*/
1503
1504	ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1505	/*
1506	Writes c, converted to an unsigned char, into the compressed file. gzputc
1507	returns the value that was written, or -1 in case of error.
1508	*/
1509
1510	ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1511	/*
1512	Reads one byte from the compressed file. gzgetc returns this byte or -1
1513	in case of end of file or error. This is implemented as a macro for speed.
1514	As such, it does not do all of the checking the other functions do. I.e.
1515	it does not check to see if file is NULL, nor whether the structure file
1516	points to has been clobbered or not.
1517	*/
1518
1519	ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1520	/*
1521	Push one character back onto the stream to be read as the first character
1522	on the next read. At least one character of push-back is allowed.
1523	gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1524	fail if c is -1, and may fail if a character has been pushed but not read
1525	yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1526	output buffer size of pushed characters is allowed. (See gzbuffer above.)
1527	The pushed character will be discarded if the stream is repositioned with
1528	gzseek() or gzrewind().
1529	*/
1530
1531	ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1532	/*
1533	Flushes all pending output into the compressed file. The parameter flush
1534	is as in the deflate() function. The return value is the zlib error number
1535	(see function gzerror below). gzflush is only permitted when writing.
1536
1537	If the flush parameter is Z_FINISH, the remaining data is written and the
1538	gzip stream is completed in the output. If gzwrite() is called again, a new
1539	gzip stream will be started in the output. gzread() is able to read such
1540	concatenated gzip streams.
1541
1542	gzflush should be called only when strictly necessary because it will
1543	degrade compression if called too often.
1544	*/
1545
1546	/*
1547	ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1548	z_off_t offset, int whence));
1549
1550	Sets the starting position for the next gzread or gzwrite on the given
1551	compressed file. The offset represents a number of bytes in the
1552	uncompressed data stream. The whence parameter is defined as in lseek(2);
1553	the value SEEK_END is not supported.
1554
1555	If the file is opened for reading, this function is emulated but can be
1556	extremely slow. If the file is opened for writing, only forward seeks are
1557	supported; gzseek then compresses a sequence of zeroes up to the new
1558	starting position.
1559
1560	gzseek returns the resulting offset location as measured in bytes from
1561	the beginning of the uncompressed stream, or -1 in case of error, in
1562	particular if the file is opened for writing and the new starting position
1563	would be before the current position.
1564	*/
1565
1566	ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1567	/*
1568	Rewinds the given file. This function is supported only for reading.
1569
1570	gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1571	*/
1572
1573	/*
1574	ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1575
1576	Returns the starting position for the next gzread or gzwrite on the given
1577	compressed file. This position represents a number of bytes in the
1578	uncompressed data stream, and is zero when starting, even if appending or
1579	reading a gzip stream from the middle of a file using gzdopen().
1580
1581	gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1582	*/
1583
1584	/*
1585	ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1586
1587	Returns the current offset in the file being read or written. This offset
1588	includes the count of bytes that precede the gzip stream, for example when
1589	appending or when using gzdopen() for reading. When reading, the offset
1590	does not include as yet unused buffered input. This information can be used
1591	for a progress indicator. On error, gzoffset() returns -1.
1592	*/
1593
1594	ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1595	/*
1596	Returns true (1) if the end-of-file indicator has been set while reading,
1597	false (0) otherwise. Note that the end-of-file indicator is set only if the
1598	read tried to go past the end of the input, but came up short. Therefore,
1599	just like feof(), gzeof() may return false even if there is no more data to
1600	read, in the event that the last read request was for the exact number of
1601	bytes remaining in the input file. This will happen if the input file size
1602	is an exact multiple of the buffer size.
1603
1604	If gzeof() returns true, then the read functions will return no more data,
1605	unless the end-of-file indicator is reset by gzclearerr() and the input file
1606	has grown since the previous end of file was detected.
1607	*/
1608
1609	ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1610	/*
1611	Returns true (1) if file is being copied directly while reading, or false
1612	(0) if file is a gzip stream being decompressed.
1613
1614	If the input file is empty, gzdirect() will return true, since the input
1615	does not contain a gzip stream.
1616
1617	If gzdirect() is used immediately after gzopen() or gzdopen() it will
1618	cause buffers to be allocated to allow reading the file to determine if it
1619	is a gzip file. Therefore if gzbuffer() is used, it should be called before
1620	gzdirect().
1621
1622	When writing, gzdirect() returns true (1) if transparent writing was
1623	requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1624	gzdirect() is not needed when writing. Transparent writing must be
1625	explicitly requested, so the application already knows the answer. When
1626	linking statically, using gzdirect() will include all of the zlib code for
1627	gzip file reading and decompression, which may not be desired.)
1628	*/
1629
1630	ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1631	/*
1632	Flushes all pending output if necessary, closes the compressed file and
1633	deallocates the (de)compression state. Note that once file is closed, you
1634	cannot call gzerror with file, since its structures have been deallocated.
1635	gzclose must not be called more than once on the same file, just as free
1636	must not be called more than once on the same allocation.
1637
1638	gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1639	file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1640	last read ended in the middle of a gzip stream, or Z_OK on success.
1641	*/
1642
1643	ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1644	ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1645	/*
1646	Same as gzclose(), but gzclose_r() is only for use when reading, and
1647	gzclose_w() is only for use when writing or appending. The advantage to
1648	using these instead of gzclose() is that they avoid linking in zlib
1649	compression or decompression code that is not used when only reading or only
1650	writing respectively. If gzclose() is used, then both compression and
1651	decompression code will be included the application when linking to a static
1652	zlib library.
1653	*/
1654
1655	ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1656	/*
1657	Returns the error message for the last error which occurred on the given
1658	compressed file. errnum is set to zlib error number. If an error occurred
1659	in the file system and not in the compression library, errnum is set to
1660	Z_ERRNO and the application may consult errno to get the exact error code.
1661
1662	The application must not modify the returned string. Future calls to
1663	this function may invalidate the previously returned string. If file is
1664	closed, then the string previously returned by gzerror will no longer be
1665	available.
1666
1667	gzerror() should be used to distinguish errors from end-of-file for those
1668	functions above that do not distinguish those cases in their return values.
1669	*/
1670
1671	ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1672	/*
1673	Clears the error and end-of-file flags for file. This is analogous to the
1674	clearerr() function in stdio. This is useful for continuing to read a gzip
1675	file that is being written concurrently.
1676	*/
1677
1678	#endif /* !Z_SOLO */
1679
1680	/* checksum functions */
1681
1682	/*
1683	These functions are not related to compression but are exported
1684	anyway because they might be useful in applications using the compression
1685	library.
1686	*/
1687
1688	ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1689	/*
1690	Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1691	return the updated checksum. If buf is Z_NULL, this function returns the
1692	required initial value for the checksum.
1693
1694	An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1695	much faster.
1696
1697	Usage example:
1698
1699	uLong adler = adler32(0L, Z_NULL, 0);
1700
1701	while (read_buffer(buffer, length) != EOF) {
1702	adler = adler32(adler, buffer, length);
1703	}
1704	if (adler != original_adler) error();
1705	*/
1706
1707	ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
1708	z_size_t len));
1709	/*
1710	Same as adler32(), but with a size_t length.
1711	*/
1712
1713	/*
1714	ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1715	z_off_t len2));
1716
1717	Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1718	and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1719	each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1720	seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1721	that the z_off_t type (like off_t) is a signed integer. If len2 is
1722	negative, the result has no meaning or utility.
1723	*/
1724
1725	ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1726	/*
1727	Update a running CRC-32 with the bytes buf[0..len-1] and return the
1728	updated CRC-32. If buf is Z_NULL, this function returns the required
1729	initial value for the crc. Pre- and post-conditioning (one's complement) is
1730	performed within this function so it shouldn't be done by the application.
1731
1732	Usage example:
1733
1734	uLong crc = crc32(0L, Z_NULL, 0);
1735
1736	while (read_buffer(buffer, length) != EOF) {
1737	crc = crc32(crc, buffer, length);
1738	}
1739	if (crc != original_crc) error();
1740	*/
1741
1742	ZEXTERN uLong ZEXPORT crc32_z OF((uLong adler, const Bytef *buf,
1743	z_size_t len));
1744	/*
1745	Same as crc32(), but with a size_t length.
1746	*/
1747
1748	/*
1749	ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1750
1751	Combine two CRC-32 check values into one. For two sequences of bytes,
1752	seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1753	calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1754	check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1755	len2.
1756	*/
1757
1758
1759	/* various hacks, don't look :) */
1760
1761	/* deflateInit and inflateInit are macros to allow checking the zlib version
1762	* and the compiler's view of z_stream:
1763	*/
1764	ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1765	const char *version, int stream_size));
1766	ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1767	const char *version, int stream_size));
1768	ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1769	int windowBits, int memLevel,
1770	int strategy, const char *version,
1771	int stream_size));
1772	ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1773	const char *version, int stream_size));
1774	ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1775	unsigned char FAR *window,
1776	const char *version,
1777	int stream_size));
1778	#ifdef Z_PREFIX_SET
1779	# define z_deflateInit(strm, level) \
1780	deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1781	# define z_inflateInit(strm) \
1782	inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1783	# define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1784	deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1785	(strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1786	# define z_inflateInit2(strm, windowBits) \
1787	inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1788	(int)sizeof(z_stream))
1789	# define z_inflateBackInit(strm, windowBits, window) \
1790	inflateBackInit_((strm), (windowBits), (window), \
1791	ZLIB_VERSION, (int)sizeof(z_stream))
1792	#else
1793	# define deflateInit(strm, level) \
1794	deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1795	# define inflateInit(strm) \
1796	inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1797	# define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1798	deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1799	(strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1800	# define inflateInit2(strm, windowBits) \
1801	inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1802	(int)sizeof(z_stream))
1803	# define inflateBackInit(strm, windowBits, window) \
1804	inflateBackInit_((strm), (windowBits), (window), \
1805	ZLIB_VERSION, (int)sizeof(z_stream))
1806	#endif
1807
1808	#ifndef Z_SOLO
1809
1810	/* gzgetc() macro and its supporting function and exposed data structure. Note
1811	* that the real internal state is much larger than the exposed structure.
1812	* This abbreviated structure exposes just enough for the gzgetc() macro. The
1813	* user should not mess with these exposed elements, since their names or
1814	* behavior could change in the future, perhaps even capriciously. They can
1815	* only be used by the gzgetc() macro. You have been warned.
1816	*/
1817	struct gzFile_s {
1818	unsigned have;
1819	unsigned char *next;
1820	z_off64_t pos;
1821	};
1822	ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */
1823	#ifdef Z_PREFIX_SET
1824	# undef z_gzgetc
1825	# define z_gzgetc(g) \
1826	((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1827	#else
1828	# define gzgetc(g) \
1829	((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1830	#endif
1831
1832	/* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1833	* change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1834	* both are true, the application gets the *64 functions, and the regular
1835	* functions are changed to 64 bits) -- in case these are set on systems
1836	* without large file support, _LFS64_LARGEFILE must also be true
1837	*/
1838	#ifdef Z_LARGE64
1839	ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1840	ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1841	ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1842	ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1843	ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1844	ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1845	#endif
1846
1847	#if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1848	# ifdef Z_PREFIX_SET
1849	# define z_gzopen z_gzopen64
1850	# define z_gzseek z_gzseek64
1851	# define z_gztell z_gztell64
1852	# define z_gzoffset z_gzoffset64
1853	# define z_adler32_combine z_adler32_combine64
1854	# define z_crc32_combine z_crc32_combine64
1855	# else
1856	# define gzopen gzopen64
1857	# define gzseek gzseek64
1858	# define gztell gztell64
1859	# define gzoffset gzoffset64
1860	# define adler32_combine adler32_combine64
1861	# define crc32_combine crc32_combine64
1862	# endif
1863	# ifndef Z_LARGE64
1864	ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1865	ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1866	ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1867	ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1868	ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1869	ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1870	# endif
1871	#else
1872	ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1873	ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1874	ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1875	ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1876	ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1877	ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1878	#endif
1879
1880	#else /* Z_SOLO */
1881
1882	ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1883	ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1884
1885	#endif /* !Z_SOLO */
1886
1887	/* undocumented functions */
1888	ZEXTERN const char * ZEXPORT zError OF((int));
1889	ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1890	ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void));
1891	ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1892	ZEXTERN int ZEXPORT inflateValidate OF((z_streamp, int));
1893	ZEXTERN unsigned long ZEXPORT inflateCodesUsed OF ((z_streamp));
1894	ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1895	ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1896	#if defined(_WIN32) && !defined(Z_SOLO)
1897	ZEXTERN gzFile ZEXPORT gzopen_w OF((const wchar_t *path,
1898	const char *mode));
1899	#endif
1900	#if defined(STDC) || defined(Z_HAVE_STDARG_H)
1901	# ifndef Z_SOLO
1902	ZEXTERN int ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1903	const char *format,
1904	va_list va));
1905	# endif
1906	#endif
1907
1908	#ifdef __cplusplus
1909	}
1910	#endif
1911
1912	#endif /* ZLIB_H */
1913