1 /* $OpenBSD: zlib.h,v 1.9 2005/07/20 15:56:46 millert Exp $ */
2 /* zlib.h -- interface of the 'zlib' general purpose compression library
3 version 1.2.3, July 18th, 2005
4
5 Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
6
7 This software is provided 'as-is', without any express or implied
8 warranty. In no event will the authors be held liable for any damages
9 arising from the use of this software.
10
11 Permission is granted to anyone to use this software for any purpose,
12 including commercial applications, and to alter it and redistribute it
13 freely, subject to the following restrictions:
14
15 1. The origin of this software must not be misrepresented; you must not
16 claim that you wrote the original software. If you use this software
17 in a product, an acknowledgment in the product documentation would be
18 appreciated but is not required.
19 2. Altered source versions must be plainly marked as such, and must not be
20 misrepresented as being the original software.
21 3. This notice may not be removed or altered from any source distribution.
22
23 Jean-loup Gailly Mark Adler
24 jloup@gzip.org madler@alumni.caltech.edu
25
26
27 The data format used by the zlib library is described by RFCs (Request for
28 Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
29 (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
30 */
31
32 #ifndef ZLIB_H
33 #define ZLIB_H
34
35 #include "zconf.h"
36
37 #ifdef __cplusplus
38 extern "C" {
39 #endif
40
41 #define ZLIB_VERSION "1.2.3"
42 #define ZLIB_VERNUM 0x1230
43
44 /*
45 The 'zlib' compression library provides in-memory compression and
46 decompression functions, including integrity checks of the uncompressed
47 data. This version of the library supports only one compression method
48 (deflation) but other algorithms will be added later and will have the same
49 stream interface.
50
51 Compression can be done in a single step if the buffers are large
52 enough (for example if an input file is mmap'ed), or can be done by
53 repeated calls of the compression function. In the latter case, the
54 application must provide more input and/or consume the output
55 (providing more output space) before each call.
56
57 The compressed data format used by default by the in-memory functions is
58 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
59 around a deflate stream, which is itself documented in RFC 1951.
60
61 The library also supports reading and writing files in gzip (.gz) format
62 with an interface similar to that of stdio using the functions that start
63 with "gz". The gzip format is different from the zlib format. gzip is a
64 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
65
66 This library can optionally read and write gzip streams in memory as well.
67
68 The zlib format was designed to be compact and fast for use in memory
69 and on communications channels. The gzip format was designed for single-
70 file compression on file systems, has a larger header than zlib to maintain
71 directory information, and uses a different, slower check method than zlib.
72
73 The library does not install any signal handler. The decoder checks
74 the consistency of the compressed data, so the library should never
75 crash even in case of corrupted input.
76 */
77
78 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
79 typedef void (*free_func) OF((voidpf opaque, voidpf address));
80
81 struct internal_state;
82
83 typedef struct z_stream_s {
84 Bytef *next_in; /* next input byte */
85 uInt avail_in; /* number of bytes available at next_in */
86 z_off_t total_in; /* total nb of input bytes read so far */
87
88 Bytef *next_out; /* next output byte should be put there */
89 uInt avail_out; /* remaining free space at next_out */
90 z_off_t total_out; /* total nb of bytes output so far */
91
92 char *msg; /* last error message, NULL if no error */
93 struct internal_state FAR *state; /* not visible by applications */
94
95 alloc_func zalloc; /* used to allocate the internal state */
96 free_func zfree; /* used to free the internal state */
97 voidpf opaque; /* private data object passed to zalloc and zfree */
98
99 int data_type; /* best guess about the data type: binary or text */
100 uLong adler; /* adler32 value of the uncompressed data */
101 uLong reserved; /* reserved for future use */
102 } z_stream;
103
104 typedef z_stream FAR *z_streamp;
105
106 /*
107 gzip header information passed to and from zlib routines. See RFC 1952
108 for more details on the meanings of these fields.
109 */
110 typedef struct gz_header_s {
111 int text; /* true if compressed data believed to be text */
112 uLong time; /* modification time */
113 int xflags; /* extra flags (not used when writing a gzip file) */
114 int os; /* operating system */
115 Bytef *extra; /* pointer to extra field or Z_NULL if none */
116 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
117 uInt extra_max; /* space at extra (only when reading header) */
118 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
119 uInt name_max; /* space at name (only when reading header) */
120 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
121 uInt comm_max; /* space at comment (only when reading header) */
122 int hcrc; /* true if there was or will be a header crc */
123 int done; /* true when done reading gzip header (not used
124 when writing a gzip file) */
125 } gz_header;
126
127 typedef gz_header FAR *gz_headerp;
128
129 /*
130 The application must update next_in and avail_in when avail_in has
131 dropped to zero. It must update next_out and avail_out when avail_out
132 has dropped to zero. The application must initialize zalloc, zfree and
133 opaque before calling the init function. All other fields are set by the
134 compression library and must not be updated by the application.
135
136 The opaque value provided by the application will be passed as the first
137 parameter for calls of zalloc and zfree. This can be useful for custom
138 memory management. The compression library attaches no meaning to the
139 opaque value.
140
141 zalloc must return Z_NULL if there is not enough memory for the object.
142 If zlib is used in a multi-threaded application, zalloc and zfree must be
143 thread safe.
144
145 On 16-bit systems, the functions zalloc and zfree must be able to allocate
146 exactly 65536 bytes, but will not be required to allocate more than this
147 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
148 pointers returned by zalloc for objects of exactly 65536 bytes *must*
149 have their offset normalized to zero. The default allocation function
150 provided by this library ensures this (see zutil.c). To reduce memory
151 requirements and avoid any allocation of 64K objects, at the expense of
152 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
153
154 The fields total_in and total_out can be used for statistics or
155 progress reports. After compression, total_in holds the total size of
156 the uncompressed data and may be saved for use in the decompressor
157 (particularly if the decompressor wants to decompress everything in
158 a single step).
159 */
160
161 /* constants */
162
163 #define Z_NO_FLUSH 0
164 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
165 #define Z_SYNC_FLUSH 2
166 #define Z_FULL_FLUSH 3
167 #define Z_FINISH 4
168 #define Z_BLOCK 5
169 /* Allowed flush values; see deflate() and inflate() below for details */
170
171 #define Z_OK 0
172 #define Z_STREAM_END 1
173 #define Z_NEED_DICT 2
174 #define Z_ERRNO (-1)
175 #define Z_STREAM_ERROR (-2)
176 #define Z_DATA_ERROR (-3)
177 #define Z_MEM_ERROR (-4)
178 #define Z_BUF_ERROR (-5)
179 #define Z_VERSION_ERROR (-6)
180 /* Return codes for the compression/decompression functions. Negative
181 * values are errors, positive values are used for special but normal events.
182 */
183
184 #define Z_NO_COMPRESSION 0
185 #define Z_BEST_SPEED 1
186 #define Z_BEST_COMPRESSION 9
187 #define Z_DEFAULT_COMPRESSION (-1)
188 /* compression levels */
189
190 #define Z_FILTERED 1
191 #define Z_HUFFMAN_ONLY 2
192 #define Z_RLE 3
193 #define Z_FIXED 4
194 #define Z_DEFAULT_STRATEGY 0
195 /* compression strategy; see deflateInit2() below for details */
196
197 #define Z_BINARY 0
198 #define Z_TEXT 1
199 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
200 #define Z_UNKNOWN 2
201 /* Possible values of the data_type field (though see inflate()) */
202
203 #define Z_DEFLATED 8
204 /* The deflate compression method (the only one supported in this version) */
205
206 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
207
208 #define zlib_version zlibVersion()
209 /* for compatibility with versions < 1.0.2 */
210
211 /* basic functions */
212
213 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
214 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
215 If the first character differs, the library code actually used is
216 not compatible with the zlib.h header file used by the application.
217 This check is automatically made by deflateInit and inflateInit.
218 */
219
220 /*
221 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
222
223 Initializes the internal stream state for compression. The fields
224 zalloc, zfree and opaque must be initialized before by the caller.
225 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
226 use default allocation functions.
227
228 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
229 1 gives best speed, 9 gives best compression, 0 gives no compression at
230 all (the input data is simply copied a block at a time).
231 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
232 compression (currently equivalent to level 6).
233
234 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
235 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
236 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
237 with the version assumed by the caller (ZLIB_VERSION).
238 msg is set to null if there is no error message. deflateInit does not
239 perform any compression: this will be done by deflate().
240 */
241
242
243 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
244 /*
245 deflate compresses as much data as possible, and stops when the input
246 buffer becomes empty or the output buffer becomes full. It may introduce some
247 output latency (reading input without producing any output) except when
248 forced to flush.
249
250 The detailed semantics are as follows. deflate performs one or both of the
251 following actions:
252
253 - Compress more input starting at next_in and update next_in and avail_in
254 accordingly. If not all input can be processed (because there is not
255 enough room in the output buffer), next_in and avail_in are updated and
256 processing will resume at this point for the next call of deflate().
257
258 - Provide more output starting at next_out and update next_out and avail_out
259 accordingly. This action is forced if the parameter flush is non zero.
260 Forcing flush frequently degrades the compression ratio, so this parameter
261 should be set only when necessary (in interactive applications).
262 Some output may be provided even if flush is not set.
263
264 Before the call of deflate(), the application should ensure that at least
265 one of the actions is possible, by providing more input and/or consuming
266 more output, and updating avail_in or avail_out accordingly; avail_out
267 should never be zero before the call. The application can consume the
268 compressed output when it wants, for example when the output buffer is full
269 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
270 and with zero avail_out, it must be called again after making room in the
271 output buffer because there might be more output pending.
272
273 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
274 decide how much data to accumualte before producing output, in order to
275 maximize compression.
276
277 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
278 flushed to the output buffer and the output is aligned on a byte boundary, so
279 that the decompressor can get all input data available so far. (In particular
280 avail_in is zero after the call if enough output space has been provided
281 before the call.) Flushing may degrade compression for some compression
282 algorithms and so it should be used only when necessary.
283
284 If flush is set to Z_FULL_FLUSH, all output is flushed as with
285 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
286 restart from this point if previous compressed data has been damaged or if
287 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
288 compression.
289
290 If deflate returns with avail_out == 0, this function must be called again
291 with the same value of the flush parameter and more output space (updated
292 avail_out), until the flush is complete (deflate returns with non-zero
293 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
294 avail_out is greater than six to avoid repeated flush markers due to
295 avail_out == 0 on return.
296
297 If the parameter flush is set to Z_FINISH, pending input is processed,
298 pending output is flushed and deflate returns with Z_STREAM_END if there
299 was enough output space; if deflate returns with Z_OK, this function must be
300 called again with Z_FINISH and more output space (updated avail_out) but no
301 more input data, until it returns with Z_STREAM_END or an error. After
302 deflate has returned Z_STREAM_END, the only possible operations on the
303 stream are deflateReset or deflateEnd.
304
305 Z_FINISH can be used immediately after deflateInit if all the compression
306 is to be done in a single step. In this case, avail_out must be at least
307 the value returned by deflateBound (see below). If deflate does not return
308 Z_STREAM_END, then it must be called again as described above.
309
310 deflate() sets strm->adler to the adler32 checksum of all input read
311 so far (that is, total_in bytes).
312
313 deflate() may update strm->data_type if it can make a good guess about
314 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
315 binary. This field is only for information purposes and does not affect
316 the compression algorithm in any manner.
317
318 deflate() returns Z_OK if some progress has been made (more input
319 processed or more output produced), Z_STREAM_END if all input has been
320 consumed and all output has been produced (only when flush is set to
321 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
322 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
323 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
324 fatal, and deflate() can be called again with more input and more output
325 space to continue compressing.
326 */
327
328
329 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
330 /*
331 All dynamically allocated data structures for this stream are freed.
332 This function discards any unprocessed input and does not flush any
333 pending output.
334
335 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
336 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
337 prematurely (some input or output was discarded). In the error case,
338 msg may be set but then points to a static string (which must not be
339 deallocated).
340 */
341
342
343 /*
344 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
345
346 Initializes the internal stream state for decompression. The fields
347 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
348 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
349 value depends on the compression method), inflateInit determines the
350 compression method from the zlib header and allocates all data structures
351 accordingly; otherwise the allocation will be deferred to the first call of
352 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
353 use default allocation functions.
354
355 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
356 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
357 version assumed by the caller. msg is set to null if there is no error
358 message. inflateInit does not perform any decompression apart from reading
359 the zlib header if present: this will be done by inflate(). (So next_in and
360 avail_in may be modified, but next_out and avail_out are unchanged.)
361 */
362
363
364 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
365 /*
366 inflate decompresses as much data as possible, and stops when the input
367 buffer becomes empty or the output buffer becomes full. It may introduce
368 some output latency (reading input without producing any output) except when
369 forced to flush.
370
371 The detailed semantics are as follows. inflate performs one or both of the
372 following actions:
373
374 - Decompress more input starting at next_in and update next_in and avail_in
375 accordingly. If not all input can be processed (because there is not
376 enough room in the output buffer), next_in is updated and processing
377 will resume at this point for the next call of inflate().
378
379 - Provide more output starting at next_out and update next_out and avail_out
380 accordingly. inflate() provides as much output as possible, until there
381 is no more input data or no more space in the output buffer (see below
382 about the flush parameter).
383
384 Before the call of inflate(), the application should ensure that at least
385 one of the actions is possible, by providing more input and/or consuming
386 more output, and updating the next_* and avail_* values accordingly.
387 The application can consume the uncompressed output when it wants, for
388 example when the output buffer is full (avail_out == 0), or after each
389 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
390 must be called again after making room in the output buffer because there
391 might be more output pending.
392
393 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
394 Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
395 output as possible to the output buffer. Z_BLOCK requests that inflate() stop
396 if and when it gets to the next deflate block boundary. When decoding the
397 zlib or gzip format, this will cause inflate() to return immediately after
398 the header and before the first block. When doing a raw inflate, inflate()
399 will go ahead and process the first block, and will return when it gets to
400 the end of that block, or when it runs out of data.
401
402 The Z_BLOCK option assists in appending to or combining deflate streams.
403 Also to assist in this, on return inflate() will set strm->data_type to the
404 number of unused bits in the last byte taken from strm->next_in, plus 64
405 if inflate() is currently decoding the last block in the deflate stream,
406 plus 128 if inflate() returned immediately after decoding an end-of-block
407 code or decoding the complete header up to just before the first byte of the
408 deflate stream. The end-of-block will not be indicated until all of the
409 uncompressed data from that block has been written to strm->next_out. The
410 number of unused bits may in general be greater than seven, except when
411 bit 7 of data_type is set, in which case the number of unused bits will be
412 less than eight.
413
414 inflate() should normally be called until it returns Z_STREAM_END or an
415 error. However if all decompression is to be performed in a single step
416 (a single call of inflate), the parameter flush should be set to
417 Z_FINISH. In this case all pending input is processed and all pending
418 output is flushed; avail_out must be large enough to hold all the
419 uncompressed data. (The size of the uncompressed data may have been saved
420 by the compressor for this purpose.) The next operation on this stream must
421 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
422 is never required, but can be used to inform inflate that a faster approach
423 may be used for the single inflate() call.
424
425 In this implementation, inflate() always flushes as much output as
426 possible to the output buffer, and always uses the faster approach on the
427 first call. So the only effect of the flush parameter in this implementation
428 is on the return value of inflate(), as noted below, or when it returns early
429 because Z_BLOCK is used.
430
431 If a preset dictionary is needed after this call (see inflateSetDictionary
432 below), inflate sets strm->adler to the adler32 checksum of the dictionary
433 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
434 strm->adler to the adler32 checksum of all output produced so far (that is,
435 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
436 below. At the end of the stream, inflate() checks that its computed adler32
437 checksum is equal to that saved by the compressor and returns Z_STREAM_END
438 only if the checksum is correct.
439
440 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
441 deflate data. The header type is detected automatically. Any information
442 contained in the gzip header is not retained, so applications that need that
443 information should instead use raw inflate, see inflateInit2() below, or
444 inflateBack() and perform their own processing of the gzip header and
445 trailer.
446
447 inflate() returns Z_OK if some progress has been made (more input processed
448 or more output produced), Z_STREAM_END if the end of the compressed data has
449 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
450 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
451 corrupted (input stream not conforming to the zlib format or incorrect check
452 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
453 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
454 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
455 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
456 inflate() can be called again with more input and more output space to
457 continue decompressing. If Z_DATA_ERROR is returned, the application may then
458 call inflateSync() to look for a good compression block if a partial recovery
459 of the data is desired.
460 */
461
462
463 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
464 /*
465 All dynamically allocated data structures for this stream are freed.
466 This function discards any unprocessed input and does not flush any
467 pending output.
468
469 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
470 was inconsistent. In the error case, msg may be set but then points to a
471 static string (which must not be deallocated).
472 */
473
474 /* Advanced functions */
475
476 /*
477 The following functions are needed only in some special applications.
478 */
479
480 /*
481 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
482 int level,
483 int method,
484 int windowBits,
485 int memLevel,
486 int strategy));
487
488 This is another version of deflateInit with more compression options. The
489 fields next_in, zalloc, zfree and opaque must be initialized before by
490 the caller.
491
492 The method parameter is the compression method. It must be Z_DEFLATED in
493 this version of the library.
494
495 The windowBits parameter is the base two logarithm of the window size
496 (the size of the history buffer). It should be in the range 8..15 for this
497 version of the library. Larger values of this parameter result in better
498 compression at the expense of memory usage. The default value is 15 if
499 deflateInit is used instead.
500
501 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
502 determines the window size. deflate() will then generate raw deflate data
503 with no zlib header or trailer, and will not compute an adler32 check value.
504
505 windowBits can also be greater than 15 for optional gzip encoding. Add
506 16 to windowBits to write a simple gzip header and trailer around the
507 compressed data instead of a zlib wrapper. The gzip header will have no
508 file name, no extra data, no comment, no modification time (set to zero),
509 no header crc, and the operating system will be set to 255 (unknown). If a
510 gzip stream is being written, strm->adler is a crc32 instead of an adler32.
511
512 The memLevel parameter specifies how much memory should be allocated
513 for the internal compression state. memLevel=1 uses minimum memory but
514 is slow and reduces compression ratio; memLevel=9 uses maximum memory
515 for optimal speed. The default value is 8. See zconf.h for total memory
516 usage as a function of windowBits and memLevel.
517
518 The strategy parameter is used to tune the compression algorithm. Use the
519 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
520 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
521 string match), or Z_RLE to limit match distances to one (run-length
522 encoding). Filtered data consists mostly of small values with a somewhat
523 random distribution. In this case, the compression algorithm is tuned to
524 compress them better. The effect of Z_FILTERED is to force more Huffman
525 coding and less string matching; it is somewhat intermediate between
526 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
527 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
528 parameter only affects the compression ratio but not the correctness of the
529 compressed output even if it is not set appropriately. Z_FIXED prevents the
530 use of dynamic Huffman codes, allowing for a simpler decoder for special
531 applications.
532
533 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
534 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
535 method). msg is set to null if there is no error message. deflateInit2 does
536 not perform any compression: this will be done by deflate().
537 */
538
539 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
540 const Bytef *dictionary,
541 uInt dictLength));
542 /*
543 Initializes the compression dictionary from the given byte sequence
544 without producing any compressed output. This function must be called
545 immediately after deflateInit, deflateInit2 or deflateReset, before any
546 call of deflate. The compressor and decompressor must use exactly the same
547 dictionary (see inflateSetDictionary).
548
549 The dictionary should consist of strings (byte sequences) that are likely
550 to be encountered later in the data to be compressed, with the most commonly
551 used strings preferably put towards the end of the dictionary. Using a
552 dictionary is most useful when the data to be compressed is short and can be
553 predicted with good accuracy; the data can then be compressed better than
554 with the default empty dictionary.
555
556 Depending on the size of the compression data structures selected by
557 deflateInit or deflateInit2, a part of the dictionary may in effect be
558 discarded, for example if the dictionary is larger than the window size in
559 deflate or deflate2. Thus the strings most likely to be useful should be
560 put at the end of the dictionary, not at the front. In addition, the
561 current implementation of deflate will use at most the window size minus
562 262 bytes of the provided dictionary.
563
564 Upon return of this function, strm->adler is set to the adler32 value
565 of the dictionary; the decompressor may later use this value to determine
566 which dictionary has been used by the compressor. (The adler32 value
567 applies to the whole dictionary even if only a subset of the dictionary is
568 actually used by the compressor.) If a raw deflate was requested, then the
569 adler32 value is not computed and strm->adler is not set.
570
571 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
572 parameter is invalid (such as NULL dictionary) or the stream state is
573 inconsistent (for example if deflate has already been called for this stream
574 or if the compression method is bsort). deflateSetDictionary does not
575 perform any compression: this will be done by deflate().
576 */
577
578 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
579 z_streamp source));
580 /*
581 Sets the destination stream as a complete copy of the source stream.
582
583 This function can be useful when several compression strategies will be
584 tried, for example when there are several ways of pre-processing the input
585 data with a filter. The streams that will be discarded should then be freed
586 by calling deflateEnd. Note that deflateCopy duplicates the internal
587 compression state which can be quite large, so this strategy is slow and
588 can consume lots of memory.
589
590 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
591 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
592 (such as zalloc being NULL). msg is left unchanged in both source and
593 destination.
594 */
595
596 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
597 /*
598 This function is equivalent to deflateEnd followed by deflateInit,
599 but does not free and reallocate all the internal compression state.
600 The stream will keep the same compression level and any other attributes
601 that may have been set by deflateInit2.
602
603 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
604 stream state was inconsistent (such as zalloc or state being NULL).
605 */
606
607 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
608 int level,
609 int strategy));
610 /*
611 Dynamically update the compression level and compression strategy. The
612 interpretation of level and strategy is as in deflateInit2. This can be
613 used to switch between compression and straight copy of the input data, or
614 to switch to a different kind of input data requiring a different
615 strategy. If the compression level is changed, the input available so far
616 is compressed with the old level (and may be flushed); the new level will
617 take effect only at the next call of deflate().
618
619 Before the call of deflateParams, the stream state must be set as for
620 a call of deflate(), since the currently available input may have to
621 be compressed and flushed. In particular, strm->avail_out must be non-zero.
622
623 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
624 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
625 if strm->avail_out was zero.
626 */
627
628 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
629 int good_length,
630 int max_lazy,
631 int nice_length,
632 int max_chain));
633 /*
634 Fine tune deflate's internal compression parameters. This should only be
635 used by someone who understands the algorithm used by zlib's deflate for
636 searching for the best matching string, and even then only by the most
637 fanatic optimizer trying to squeeze out the last compressed bit for their
638 specific input data. Read the deflate.c source code for the meaning of the
639 max_lazy, good_length, nice_length, and max_chain parameters.
640
641 deflateTune() can be called after deflateInit() or deflateInit2(), and
642 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
643 */
644
645 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
646 uLong sourceLen));
647 /*
648 deflateBound() returns an upper bound on the compressed size after
649 deflation of sourceLen bytes. It must be called after deflateInit()
650 or deflateInit2(). This would be used to allocate an output buffer
651 for deflation in a single pass, and so would be called before deflate().
652 */
653
654 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
655 int bits,
656 int value));
657 /*
658 deflatePrime() inserts bits in the deflate output stream. The intent
659 is that this function is used to start off the deflate output with the
660 bits leftover from a previous deflate stream when appending to it. As such,
661 this function can only be used for raw deflate, and must be used before the
662 first deflate() call after a deflateInit2() or deflateReset(). bits must be
663 less than or equal to 16, and that many of the least significant bits of
664 value will be inserted in the output.
665
666 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
667 stream state was inconsistent.
668 */
669
670 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
671 gz_headerp head));
672 /*
673 deflateSetHeader() provides gzip header information for when a gzip
674 stream is requested by deflateInit2(). deflateSetHeader() may be called
675 after deflateInit2() or deflateReset() and before the first call of
676 deflate(). The text, time, os, extra field, name, and comment information
677 in the provided gz_header structure are written to the gzip header (xflag is
678 ignored -- the extra flags are set according to the compression level). The
679 caller must assure that, if not Z_NULL, name and comment are terminated with
680 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
681 available there. If hcrc is true, a gzip header crc is included. Note that
682 the current versions of the command-line version of gzip (up through version
683 1.3.x) do not support header crc's, and will report that it is a "multi-part
684 gzip file" and give up.
685
686 If deflateSetHeader is not used, the default gzip header has text false,
687 the time set to zero, and os set to 255, with no extra, name, or comment
688 fields. The gzip header is returned to the default state by deflateReset().
689
690 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
691 stream state was inconsistent.
692 */
693
694 /*
695 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
696 int windowBits));
697
698 This is another version of inflateInit with an extra parameter. The
699 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
700 before by the caller.
701
702 The windowBits parameter is the base two logarithm of the maximum window
703 size (the size of the history buffer). It should be in the range 8..15 for
704 this version of the library. The default value is 15 if inflateInit is used
705 instead. windowBits must be greater than or equal to the windowBits value
706 provided to deflateInit2() while compressing, or it must be equal to 15 if
707 deflateInit2() was not used. If a compressed stream with a larger window
708 size is given as input, inflate() will return with the error code
709 Z_DATA_ERROR instead of trying to allocate a larger window.
710
711 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
712 determines the window size. inflate() will then process raw deflate data,
713 not looking for a zlib or gzip header, not generating a check value, and not
714 looking for any check values for comparison at the end of the stream. This
715 is for use with other formats that use the deflate compressed data format
716 such as zip. Those formats provide their own check values. If a custom
717 format is developed using the raw deflate format for compressed data, it is
718 recommended that a check value such as an adler32 or a crc32 be applied to
719 the uncompressed data as is done in the zlib, gzip, and zip formats. For
720 most applications, the zlib format should be used as is. Note that comments
721 above on the use in deflateInit2() applies to the magnitude of windowBits.
722
723 windowBits can also be greater than 15 for optional gzip decoding. Add
724 32 to windowBits to enable zlib and gzip decoding with automatic header
725 detection, or add 16 to decode only the gzip format (the zlib format will
726 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
727 a crc32 instead of an adler32.
728
729 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
730 memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
731 is set to null if there is no error message. inflateInit2 does not perform
732 any decompression apart from reading the zlib header if present: this will
733 be done by inflate(). (So next_in and avail_in may be modified, but next_out
734 and avail_out are unchanged.)
735 */
736
737 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
738 const Bytef *dictionary,
739 uInt dictLength));
740 /*
741 Initializes the decompression dictionary from the given uncompressed byte
742 sequence. This function must be called immediately after a call of inflate,
743 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
744 can be determined from the adler32 value returned by that call of inflate.
745 The compressor and decompressor must use exactly the same dictionary (see
746 deflateSetDictionary). For raw inflate, this function can be called
747 immediately after inflateInit2() or inflateReset() and before any call of
748 inflate() to set the dictionary. The application must insure that the
749 dictionary that was used for compression is provided.
750
751 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
752 parameter is invalid (such as NULL dictionary) or the stream state is
753 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
754 expected one (incorrect adler32 value). inflateSetDictionary does not
755 perform any decompression: this will be done by subsequent calls of
756 inflate().
757 */
758
759 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
760 /*
761 Skips invalid compressed data until a full flush point (see above the
762 description of deflate with Z_FULL_FLUSH) can be found, or until all
763 available input is skipped. No output is provided.
764
765 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
766 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
767 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
768 case, the application may save the current current value of total_in which
769 indicates where valid compressed data was found. In the error case, the
770 application may repeatedly call inflateSync, providing more input each time,
771 until success or end of the input data.
772 */
773
774 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
775 z_streamp source));
776 /*
777 Sets the destination stream as a complete copy of the source stream.
778
779 This function can be useful when randomly accessing a large stream. The
780 first pass through the stream can periodically record the inflate state,
781 allowing restarting inflate at those points when randomly accessing the
782 stream.
783
784 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
785 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
786 (such as zalloc being NULL). msg is left unchanged in both source and
787 destination.
788 */
789
790 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
791 /*
792 This function is equivalent to inflateEnd followed by inflateInit,
793 but does not free and reallocate all the internal decompression state.
794 The stream will keep attributes that may have been set by inflateInit2.
795
796 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
797 stream state was inconsistent (such as zalloc or state being NULL).
798 */
799
800 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
801 int bits,
802 int value));
803 /*
804 This function inserts bits in the inflate input stream. The intent is
805 that this function is used to start inflating at a bit position in the
806 middle of a byte. The provided bits will be used before any bytes are used
807 from next_in. This function should only be used with raw inflate, and
808 should be used before the first inflate() call after inflateInit2() or
809 inflateReset(). bits must be less than or equal to 16, and that many of the
810 least significant bits of value will be inserted in the input.
811
812 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
813 stream state was inconsistent.
814 */
815
816 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
817 gz_headerp head));
818 /*
819 inflateGetHeader() requests that gzip header information be stored in the
820 provided gz_header structure. inflateGetHeader() may be called after
821 inflateInit2() or inflateReset(), and before the first call of inflate().
822 As inflate() processes the gzip stream, head->done is zero until the header
823 is completed, at which time head->done is set to one. If a zlib stream is
824 being decoded, then head->done is set to -1 to indicate that there will be
825 no gzip header information forthcoming. Note that Z_BLOCK can be used to
826 force inflate() to return immediately after header processing is complete
827 and before any actual data is decompressed.
828
829 The text, time, xflags, and os fields are filled in with the gzip header
830 contents. hcrc is set to true if there is a header CRC. (The header CRC
831 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
832 contains the maximum number of bytes to write to extra. Once done is true,
833 extra_len contains the actual extra field length, and extra contains the
834 extra field, or that field truncated if extra_max is less than extra_len.
835 If name is not Z_NULL, then up to name_max characters are written there,
836 terminated with a zero unless the length is greater than name_max. If
837 comment is not Z_NULL, then up to comm_max characters are written there,
838 terminated with a zero unless the length is greater than comm_max. When
839 any of extra, name, or comment are not Z_NULL and the respective field is
840 not present in the header, then that field is set to Z_NULL to signal its
841 absence. This allows the use of deflateSetHeader() with the returned
842 structure to duplicate the header. However if those fields are set to
843 allocated memory, then the application will need to save those pointers
844 elsewhere so that they can be eventually freed.
845
846 If inflateGetHeader is not used, then the header information is simply
847 discarded. The header is always checked for validity, including the header
848 CRC if present. inflateReset() will reset the process to discard the header
849 information. The application would need to call inflateGetHeader() again to
850 retrieve the header from the next gzip stream.
851
852 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
853 stream state was inconsistent.
854 */
855
856 /*
857 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
858 unsigned char FAR *window));
859
860 Initialize the internal stream state for decompression using inflateBack()
861 calls. The fields zalloc, zfree and opaque in strm must be initialized
862 before the call. If zalloc and zfree are Z_NULL, then the default library-
863 derived memory allocation routines are used. windowBits is the base two
864 logarithm of the window size, in the range 8..15. window is a caller
865 supplied buffer of that size. Except for special applications where it is
866 assured that deflate was used with small window sizes, windowBits must be 15
867 and a 32K byte window must be supplied to be able to decompress general
868 deflate streams.
869
870 See inflateBack() for the usage of these routines.
871
872 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
873 the paramaters are invalid, Z_MEM_ERROR if the internal state could not
874 be allocated, or Z_VERSION_ERROR if the version of the library does not
875 match the version of the header file.
876 */
877
878 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
879 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
880
881 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
882 in_func in, void FAR *in_desc,
883 out_func out, void FAR *out_desc));
884 /*
885 inflateBack() does a raw inflate with a single call using a call-back
886 interface for input and output. This is more efficient than inflate() for
887 file i/o applications in that it avoids copying between the output and the
888 sliding window by simply making the window itself the output buffer. This
889 function trusts the application to not change the output buffer passed by
890 the output function, at least until inflateBack() returns.
891
892 inflateBackInit() must be called first to allocate the internal state
893 and to initialize the state with the user-provided window buffer.
894 inflateBack() may then be used multiple times to inflate a complete, raw
895 deflate stream with each call. inflateBackEnd() is then called to free
896 the allocated state.
897
898 A raw deflate stream is one with no zlib or gzip header or trailer.
899 This routine would normally be used in a utility that reads zip or gzip
900 files and writes out uncompressed files. The utility would decode the
901 header and process the trailer on its own, hence this routine expects
902 only the raw deflate stream to decompress. This is different from the
903 normal behavior of inflate(), which expects either a zlib or gzip header and
904 trailer around the deflate stream.
905
906 inflateBack() uses two subroutines supplied by the caller that are then
907 called by inflateBack() for input and output. inflateBack() calls those
908 routines until it reads a complete deflate stream and writes out all of the
909 uncompressed data, or until it encounters an error. The function's
910 parameters and return types are defined above in the in_func and out_func
911 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
912 number of bytes of provided input, and a pointer to that input in buf. If
913 there is no input available, in() must return zero--buf is ignored in that
914 case--and inflateBack() will return a buffer error. inflateBack() will call
915 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
916 should return zero on success, or non-zero on failure. If out() returns
917 non-zero, inflateBack() will return with an error. Neither in() nor out()
918 are permitted to change the contents of the window provided to
919 inflateBackInit(), which is also the buffer that out() uses to write from.
920 The length written by out() will be at most the window size. Any non-zero
921 amount of input may be provided by in().
922
923 For convenience, inflateBack() can be provided input on the first call by
924 setting strm->next_in and strm->avail_in. If that input is exhausted, then
925 in() will be called. Therefore strm->next_in must be initialized before
926 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
927 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
928 must also be initialized, and then if strm->avail_in is not zero, input will
929 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
930
931 The in_desc and out_desc parameters of inflateBack() is passed as the
932 first parameter of in() and out() respectively when they are called. These
933 descriptors can be optionally used to pass any information that the caller-
934 supplied in() and out() functions need to do their job.
935
936 On return, inflateBack() will set strm->next_in and strm->avail_in to
937 pass back any unused input that was provided by the last in() call. The
938 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
939 if in() or out() returned an error, Z_DATA_ERROR if there was a format
940 error in the deflate stream (in which case strm->msg is set to indicate the
941 nature of the error), or Z_STREAM_ERROR if the stream was not properly
942 initialized. In the case of Z_BUF_ERROR, an input or output error can be
943 distinguished using strm->next_in which will be Z_NULL only if in() returned
944 an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
945 out() returning non-zero. (in() will always be called before out(), so
946 strm->next_in is assured to be defined if out() returns non-zero.) Note
947 that inflateBack() cannot return Z_OK.
948 */
949
950 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
951 /*
952 All memory allocated by inflateBackInit() is freed.
953
954 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
955 state was inconsistent.
956 */
957
958 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
959 /* Return flags indicating compile-time options.
960
961 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
962 1.0: size of uInt
963 3.2: size of uLong
964 5.4: size of voidpf (pointer)
965 7.6: size of z_off_t
966
967 Compiler, assembler, and debug options:
968 8: DEBUG
969 9: ASMV or ASMINF -- use ASM code
970 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
971 11: 0 (reserved)
972
973 One-time table building (smaller code, but not thread-safe if true):
974 12: BUILDFIXED -- build static block decoding tables when needed
975 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
976 14,15: 0 (reserved)
977
978 Library content (indicates missing functionality):
979 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
980 deflate code when not needed)
981 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
982 and decode gzip streams (to avoid linking crc code)
983 18-19: 0 (reserved)
984
985 Operation variations (changes in library functionality):
986 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
987 21: FASTEST -- deflate algorithm with only one, lowest compression level
988 22,23: 0 (reserved)
989
990 The sprintf variant used by gzprintf (zero is best):
991 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
992 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
993 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
994
995 Remainder:
996 27-31: 0 (reserved)
997 */
998
999
1000 /* utility functions */
1001
1002 /*
1003 The following utility functions are implemented on top of the
1004 basic stream-oriented functions. To simplify the interface, some
1005 default options are assumed (compression level and memory usage,
1006 standard memory allocation functions). The source code of these
1007 utility functions can easily be modified if you need special options.
1008 */
1009
1010 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1011 const Bytef *source, uLong sourceLen));
1012 /*
1013 Compresses the source buffer into the destination buffer. sourceLen is
1014 the byte length of the source buffer. Upon entry, destLen is the total
1015 size of the destination buffer, which must be at least the value returned
1016 by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1017 compressed buffer.
1018 This function can be used to compress a whole file at once if the
1019 input file is mmap'ed.
1020 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1021 enough memory, Z_BUF_ERROR if there was not enough room in the output
1022 buffer.
1023 */
1024
1025 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1026 const Bytef *source, uLong sourceLen,
1027 int level));
1028 /*
1029 Compresses the source buffer into the destination buffer. The level
1030 parameter has the same meaning as in deflateInit. sourceLen is the byte
1031 length of the source buffer. Upon entry, destLen is the total size of the
1032 destination buffer, which must be at least the value returned by
1033 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1034 compressed buffer.
1035
1036 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1037 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1038 Z_STREAM_ERROR if the level parameter is invalid.
1039 */
1040
1041 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1042 /*
1043 compressBound() returns an upper bound on the compressed size after
1044 compress() or compress2() on sourceLen bytes. It would be used before
1045 a compress() or compress2() call to allocate the destination buffer.
1046 */
1047
1048 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1049 const Bytef *source, uLong sourceLen));
1050 /*
1051 Decompresses the source buffer into the destination buffer. sourceLen is
1052 the byte length of the source buffer. Upon entry, destLen is the total
1053 size of the destination buffer, which must be large enough to hold the
1054 entire uncompressed data. (The size of the uncompressed data must have
1055 been saved previously by the compressor and transmitted to the decompressor
1056 by some mechanism outside the scope of this compression library.)
1057 Upon exit, destLen is the actual size of the compressed buffer.
1058 This function can be used to decompress a whole file at once if the
1059 input file is mmap'ed.
1060
1061 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1062 enough memory, Z_BUF_ERROR if there was not enough room in the output
1063 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1064 */
1065
1066
1067 typedef voidp gzFile;
1068
1069 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1070 /*
1071 Opens a gzip (.gz) file for reading or writing. The mode parameter
1072 is as in fopen ("rb" or "wb") but can also include a compression level
1073 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1074 Huffman only compression as in "wb1h", or 'R' for run-length encoding
1075 as in "wb1R". (See the description of deflateInit2 for more information
1076 about the strategy parameter.)
1077
1078 gzopen can be used to read a file which is not in gzip format; in this
1079 case gzread will directly read from the file without decompression.
1080
1081 gzopen returns NULL if the file could not be opened or if there was
1082 insufficient memory to allocate the (de)compression state; errno
1083 can be checked to distinguish the two cases (if errno is zero, the
1084 zlib error is Z_MEM_ERROR). */
1085
1086 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1087 /*
1088 gzdopen() associates a gzFile with the file descriptor fd. File
1089 descriptors are obtained from calls like open, dup, creat, pipe or
1090 fileno (in the file has been previously opened with fopen).
1091 The mode parameter is as in gzopen.
1092 The next call of gzclose on the returned gzFile will also close the
1093 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1094 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1095 gzdopen returns NULL if there was insufficient memory to allocate
1096 the (de)compression state.
1097 */
1098
1099 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1100 /*
1101 Dynamically update the compression level or strategy. See the description
1102 of deflateInit2 for the meaning of these parameters.
1103 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1104 opened for writing.
1105 */
1106
1107 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1108 /*
1109 Reads the given number of uncompressed bytes from the compressed file.
1110 If the input file was not in gzip format, gzread copies the given number
1111 of bytes into the buffer.
1112 gzread returns the number of uncompressed bytes actually read (0 for
1113 end of file, -1 for error). */
1114
1115 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1116 voidpc buf, unsigned len));
1117 /*
1118 Writes the given number of uncompressed bytes into the compressed file.
1119 gzwrite returns the number of uncompressed bytes actually written
1120 (0 in case of error).
1121 */
1122
1123 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
1124 /*
1125 Converts, formats, and writes the args to the compressed file under
1126 control of the format string, as in fprintf. gzprintf returns the number of
1127 uncompressed bytes actually written (0 in case of error). The number of
1128 uncompressed bytes written is limited to 4095. The caller should assure that
1129 this limit is not exceeded. If it is exceeded, then gzprintf() will return
1130 return an error (0) with nothing written. In this case, there may also be a
1131 buffer overflow with unpredictable consequences, which is possible only if
1132 zlib was compiled with the insecure functions sprintf() or vsprintf()
1133 because the secure snprintf() or vsnprintf() functions were not available.
1134 */
1135
1136 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1137 /*
1138 Writes the given null-terminated string to the compressed file, excluding
1139 the terminating null character.
1140 gzputs returns the number of characters written, or -1 in case of error.
1141 */
1142
1143 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1144 /*
1145 Reads bytes from the compressed file until len-1 characters are read, or
1146 a newline character is read and transferred to buf, or an end-of-file
1147 condition is encountered. The string is then terminated with a null
1148 character.
1149 gzgets returns buf, or Z_NULL in case of error.
1150 */
1151
1152 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1153 /*
1154 Writes c, converted to an unsigned char, into the compressed file.
1155 gzputc returns the value that was written, or -1 in case of error.
1156 */
1157
1158 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1159 /*
1160 Reads one byte from the compressed file. gzgetc returns this byte
1161 or -1 in case of end of file or error.
1162 */
1163
1164 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1165 /*
1166 Push one character back onto the stream to be read again later.
1167 Only one character of push-back is allowed. gzungetc() returns the
1168 character pushed, or -1 on failure. gzungetc() will fail if a
1169 character has been pushed but not read yet, or if c is -1. The pushed
1170 character will be discarded if the stream is repositioned with gzseek()
1171 or gzrewind().
1172 */
1173
1174 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1175 /*
1176 Flushes all pending output into the compressed file. The parameter
1177 flush is as in the deflate() function. The return value is the zlib
1178 error number (see function gzerror below). gzflush returns Z_OK if
1179 the flush parameter is Z_FINISH and all output could be flushed.
1180 gzflush should be called only when strictly necessary because it can
1181 degrade compression.
1182 */
1183
1184 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1185 z_off_t offset, int whence));
1186 /*
1187 Sets the starting position for the next gzread or gzwrite on the
1188 given compressed file. The offset represents a number of bytes in the
1189 uncompressed data stream. The whence parameter is defined as in lseek(2);
1190 the value SEEK_END is not supported.
1191 If the file is opened for reading, this function is emulated but can be
1192 extremely slow. If the file is opened for writing, only forward seeks are
1193 supported; gzseek then compresses a sequence of zeroes up to the new
1194 starting position.
1195
1196 gzseek returns the resulting offset location as measured in bytes from
1197 the beginning of the uncompressed stream, or -1 in case of error, in
1198 particular if the file is opened for writing and the new starting position
1199 would be before the current position.
1200 */
1201
1202 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1203 /*
1204 Rewinds the given file. This function is supported only for reading.
1205
1206 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1207 */
1208
1209 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1210 /*
1211 Returns the starting position for the next gzread or gzwrite on the
1212 given compressed file. This position represents a number of bytes in the
1213 uncompressed data stream.
1214
1215 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1216 */
1217
1218 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1219 /*
1220 Returns 1 when EOF has previously been detected reading the given
1221 input stream, otherwise zero.
1222 */
1223
1224 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1225 /*
1226 Returns 1 if file is being read directly without decompression, otherwise
1227 zero.
1228 */
1229
1230 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1231 /*
1232 Flushes all pending output if necessary, closes the compressed file
1233 and deallocates all the (de)compression state. The return value is the zlib
1234 error number (see function gzerror below).
1235 */
1236
1237 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1238 /*
1239 Returns the error message for the last error which occurred on the
1240 given compressed file. errnum is set to zlib error number. If an
1241 error occurred in the file system and not in the compression library,
1242 errnum is set to Z_ERRNO and the application may consult errno
1243 to get the exact error code.
1244 */
1245
1246 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1247 /*
1248 Clears the error and end-of-file flags for file. This is analogous to the
1249 clearerr() function in stdio. This is useful for continuing to read a gzip
1250 file that is being written concurrently.
1251 */
1252
1253 /* checksum functions */
1254
1255 /*
1256 These functions are not related to compression but are exported
1257 anyway because they might be useful in applications using the
1258 compression library.
1259 */
1260
1261 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1262 /*
1263 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1264 return the updated checksum. If buf is NULL, this function returns
1265 the required initial value for the checksum.
1266 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1267 much faster. Usage example:
1268
1269 uLong adler = adler32(0L, Z_NULL, 0);
1270
1271 while (read_buffer(buffer, length) != EOF) {
1272 adler = adler32(adler, buffer, length);
1273 }
1274 if (adler != original_adler) error();
1275 */
1276
1277 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1278 z_off_t len2));
1279 /*
1280 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1281 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1282 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1283 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1284 */
1285
1286 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1287 /*
1288 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1289 updated CRC-32. If buf is NULL, this function returns the required initial
1290 value for the for the crc. Pre- and post-conditioning (one's complement) is
1291 performed within this function so it shouldn't be done by the application.
1292 Usage example:
1293
1294 uLong crc = crc32(0L, Z_NULL, 0);
1295
1296 while (read_buffer(buffer, length) != EOF) {
1297 crc = crc32(crc, buffer, length);
1298 }
1299 if (crc != original_crc) error();
1300 */
1301
1302 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1303
1304 /*
1305 Combine two CRC-32 check values into one. For two sequences of bytes,
1306 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1307 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1308 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1309 len2.
1310 */
1311
1312
1313 /* various hacks, don't look :) */
1314
1315 /* deflateInit and inflateInit are macros to allow checking the zlib version
1316 * and the compiler's view of z_stream:
1317 */
1318 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1319 const char *version, int stream_size));
1320 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1321 const char *version, int stream_size));
1322 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1323 int windowBits, int memLevel,
1324 int strategy, const char *version,
1325 int stream_size));
1326 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1327 const char *version, int stream_size));
1328 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1329 unsigned char FAR *window,
1330 const char *version,
1331 int stream_size));
1332 #define deflateInit(strm, level) \
1333 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1334 #define inflateInit(strm) \
1335 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1336 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1337 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1338 (strategy), ZLIB_VERSION, sizeof(z_stream))
1339 #define inflateInit2(strm, windowBits) \
1340 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1341 #define inflateBackInit(strm, windowBits, window) \
1342 inflateBackInit_((strm), (windowBits), (window), \
1343 ZLIB_VERSION, sizeof(z_stream))
1344
1345
1346 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1347 struct internal_state {int dummy;}; /* hack for buggy compilers */
1348 #endif
1349
1350 ZEXTERN const char * ZEXPORT zError OF((int));
1351 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1352 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1353
1354 #ifdef __cplusplus
1355 }
1356 #endif
1357
1358 #endif /* ZLIB_H */