2010-06-17 Geoff Norton <gnorton@novell.com>
[mono.git] / support / zlib.h
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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.3.3, October 2nd, 2006
4 Copyright (C) 1995-2006 Jean-loup Gailly and Mark Adler
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.
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:
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.
22 Jean-loup Gailly Mark Adler
23 jloup@gzip.org madler@alumni.caltech.edu
26 The data format used by the zlib library is described by RFCs (Request for
27 Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
28 (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
31 #ifndef ZLIB_H
32 #define ZLIB_H
34 #include "zconf.h"
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
40 #define ZLIB_VERSION "1.2.3.3"
41 #define ZLIB_VERNUM 0x1233
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 2
44 #define ZLIB_VER_REVISION 3
47 The 'zlib' compression library provides in-memory compression and
48 decompression functions, including integrity checks of the uncompressed
49 data. This version of the library supports only one compression method
50 (deflation) but other algorithms will be added later and will have the same
51 stream interface.
53 Compression can be done in a single step if the buffers are large
54 enough (for example if an input file is mmap'ed), or can be done by
55 repeated calls of the compression function. In the latter case, the
56 application must provide more input and/or consume the output
57 (providing more output space) before each call.
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.
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.
68 This library can optionally read and write gzip streams in memory as well.
70 The zlib format was designed to be compact and fast for use in memory
71 and on communications channels. The gzip format was designed for single-
72 file compression on file systems, has a larger header than zlib to maintain
73 directory information, and uses a different, slower check method than zlib.
75 The library does not install any signal handler. The decoder checks
76 the consistency of the compressed data, so the library should never
77 crash even in case of corrupted input.
80 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
81 typedef void (*free_func) OF((voidpf opaque, voidpf address));
83 struct internal_state;
85 typedef struct z_stream_s {
86 Bytef *next_in; /* next input byte */
87 uInt avail_in; /* number of bytes available at next_in */
88 uLong total_in; /* total nb of input bytes read so far */
90 Bytef *next_out; /* next output byte should be put there */
91 uInt avail_out; /* remaining free space at next_out */
92 uLong total_out; /* total nb of bytes output so far */
94 char *msg; /* last error message, NULL if no error */
95 struct internal_state FAR *state; /* not visible by applications */
97 alloc_func zalloc; /* used to allocate the internal state */
98 free_func zfree; /* used to free the internal state */
99 voidpf opaque; /* private data object passed to zalloc and zfree */
101 int data_type; /* best guess about the data type: binary or text */
102 uLong adler; /* adler32 value of the uncompressed data */
103 uLong reserved; /* reserved for future use */
104 } z_stream;
106 typedef z_stream FAR *z_streamp;
109 gzip header information passed to and from zlib routines. See RFC 1952
110 for more details on the meanings of these fields.
112 typedef struct gz_header_s {
113 int text; /* true if compressed data believed to be text */
114 uLong time; /* modification time */
115 int xflags; /* extra flags (not used when writing a gzip file) */
116 int os; /* operating system */
117 Bytef *extra; /* pointer to extra field or Z_NULL if none */
118 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
119 uInt extra_max; /* space at extra (only when reading header) */
120 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
121 uInt name_max; /* space at name (only when reading header) */
122 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
123 uInt comm_max; /* space at comment (only when reading header) */
124 int hcrc; /* true if there was or will be a header crc */
125 int done; /* true when done reading gzip header (not used
126 when writing a gzip file) */
127 } gz_header;
129 typedef gz_header FAR *gz_headerp;
132 The application must update next_in and avail_in when avail_in has
133 dropped to zero. It must update next_out and avail_out when avail_out
134 has dropped to zero. The application must initialize zalloc, zfree and
135 opaque before calling the init function. All other fields are set by the
136 compression library and must not be updated by the application.
138 The opaque value provided by the application will be passed as the first
139 parameter for calls of zalloc and zfree. This can be useful for custom
140 memory management. The compression library attaches no meaning to the
141 opaque value.
143 zalloc must return Z_NULL if there is not enough memory for the object.
144 If zlib is used in a multi-threaded application, zalloc and zfree must be
145 thread safe.
147 On 16-bit systems, the functions zalloc and zfree must be able to allocate
148 exactly 65536 bytes, but will not be required to allocate more than this
149 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
150 pointers returned by zalloc for objects of exactly 65536 bytes *must*
151 have their offset normalized to zero. The default allocation function
152 provided by this library ensures this (see zutil.c). To reduce memory
153 requirements and avoid any allocation of 64K objects, at the expense of
154 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
156 The fields total_in and total_out can be used for statistics or
157 progress reports. After compression, total_in holds the total size of
158 the uncompressed data and may be saved for use in the decompressor
159 (particularly if the decompressor wants to decompress everything in
160 a single step).
163 /* constants */
165 #define Z_NO_FLUSH 0
166 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
167 #define Z_SYNC_FLUSH 2
168 #define Z_FULL_FLUSH 3
169 #define Z_FINISH 4
170 #define Z_BLOCK 5
171 /* Allowed flush values; see deflate() and inflate() below for details */
173 #define Z_OK 0
174 #define Z_STREAM_END 1
175 #define Z_NEED_DICT 2
176 #define Z_ERRNO (-1)
177 #define Z_STREAM_ERROR (-2)
178 #define Z_DATA_ERROR (-3)
179 #define Z_MEM_ERROR (-4)
180 #define Z_BUF_ERROR (-5)
181 #define Z_VERSION_ERROR (-6)
182 /* Return codes for the compression/decompression functions. Negative
183 * values are errors, positive values are used for special but normal events.
186 #define Z_NO_COMPRESSION 0
187 #define Z_BEST_SPEED 1
188 #define Z_BEST_COMPRESSION 9
189 #define Z_DEFAULT_COMPRESSION (-1)
190 /* compression levels */
192 #define Z_FILTERED 1
193 #define Z_HUFFMAN_ONLY 2
194 #define Z_RLE 3
195 #define Z_FIXED 4
196 #define Z_DEFAULT_STRATEGY 0
197 /* compression strategy; see deflateInit2() below for details */
199 #define Z_BINARY 0
200 #define Z_TEXT 1
201 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
202 #define Z_UNKNOWN 2
203 /* Possible values of the data_type field (though see inflate()) */
205 #define Z_DEFLATED 8
206 /* The deflate compression method (the only one supported in this version) */
208 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
210 #define zlib_version zlibVersion()
211 /* for compatibility with versions < 1.0.2 */
213 /* basic functions */
215 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
216 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
217 If the first character differs, the library code actually used is
218 not compatible with the zlib.h header file used by the application.
219 This check is automatically made by deflateInit and inflateInit.
223 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
225 Initializes the internal stream state for compression. The fields
226 zalloc, zfree and opaque must be initialized before by the caller.
227 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
228 use default allocation functions.
230 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
231 1 gives best speed, 9 gives best compression, 0 gives no compression at
232 all (the input data is simply copied a block at a time).
233 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
234 compression (currently equivalent to level 6).
236 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
237 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
238 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
239 with the version assumed by the caller (ZLIB_VERSION).
240 msg is set to null if there is no error message. deflateInit does not
241 perform any compression: this will be done by deflate().
245 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
247 deflate compresses as much data as possible, and stops when the input
248 buffer becomes empty or the output buffer becomes full. It may introduce some
249 output latency (reading input without producing any output) except when
250 forced to flush.
252 The detailed semantics are as follows. deflate performs one or both of the
253 following actions:
255 - Compress more input starting at next_in and update next_in and avail_in
256 accordingly. If not all input can be processed (because there is not
257 enough room in the output buffer), next_in and avail_in are updated and
258 processing will resume at this point for the next call of deflate().
260 - Provide more output starting at next_out and update next_out and avail_out
261 accordingly. This action is forced if the parameter flush is non zero.
262 Forcing flush frequently degrades the compression ratio, so this parameter
263 should be set only when necessary (in interactive applications).
264 Some output may be provided even if flush is not set.
266 Before the call of deflate(), the application should ensure that at least
267 one of the actions is possible, by providing more input and/or consuming
268 more output, and updating avail_in or avail_out accordingly; avail_out
269 should never be zero before the call. The application can consume the
270 compressed output when it wants, for example when the output buffer is full
271 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
272 and with zero avail_out, it must be called again after making room in the
273 output buffer because there might be more output pending.
275 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
276 decide how much data to accumualte before producing output, in order to
277 maximize compression.
279 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
280 flushed to the output buffer and the output is aligned on a byte boundary, so
281 that the decompressor can get all input data available so far. (In particular
282 avail_in is zero after the call if enough output space has been provided
283 before the call.) Flushing may degrade compression for some compression
284 algorithms and so it should be used only when necessary.
286 If flush is set to Z_FULL_FLUSH, all output is flushed as with
287 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
288 restart from this point if previous compressed data has been damaged or if
289 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
290 compression.
292 If deflate returns with avail_out == 0, this function must be called again
293 with the same value of the flush parameter and more output space (updated
294 avail_out), until the flush is complete (deflate returns with non-zero
295 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
296 avail_out is greater than six to avoid repeated flush markers due to
297 avail_out == 0 on return.
299 If the parameter flush is set to Z_FINISH, pending input is processed,
300 pending output is flushed and deflate returns with Z_STREAM_END if there
301 was enough output space; if deflate returns with Z_OK, this function must be
302 called again with Z_FINISH and more output space (updated avail_out) but no
303 more input data, until it returns with Z_STREAM_END or an error. After
304 deflate has returned Z_STREAM_END, the only possible operations on the
305 stream are deflateReset or deflateEnd.
307 Z_FINISH can be used immediately after deflateInit if all the compression
308 is to be done in a single step. In this case, avail_out must be at least
309 the value returned by deflateBound (see below). If deflate does not return
310 Z_STREAM_END, then it must be called again as described above.
312 deflate() sets strm->adler to the adler32 checksum of all input read
313 so far (that is, total_in bytes).
315 deflate() may update strm->data_type if it can make a good guess about
316 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
317 binary. This field is only for information purposes and does not affect
318 the compression algorithm in any manner.
320 deflate() returns Z_OK if some progress has been made (more input
321 processed or more output produced), Z_STREAM_END if all input has been
322 consumed and all output has been produced (only when flush is set to
323 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
324 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
325 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
326 fatal, and deflate() can be called again with more input and more output
327 space to continue compressing.
331 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
333 All dynamically allocated data structures for this stream are freed.
334 This function discards any unprocessed input and does not flush any
335 pending output.
337 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
338 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
339 prematurely (some input or output was discarded). In the error case,
340 msg may be set but then points to a static string (which must not be
341 deallocated).
346 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
348 Initializes the internal stream state for decompression. The fields
349 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
350 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
351 value depends on the compression method), inflateInit determines the
352 compression method from the zlib header and allocates all data structures
353 accordingly; otherwise the allocation will be deferred to the first call of
354 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
355 use default allocation functions.
357 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
358 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
359 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
360 invalid, such as a null pointer to the structure. msg is set to null if
361 there is no error message. inflateInit does not perform any decompression
362 apart from possibly reading the zlib header if present: actual decompression
363 will be done by inflate(). (So next_in and avail_in may be modified, but
364 next_out and avail_out are unused and unchanged.) The current
365 implementation of inflateInit() does not process any header information --
366 that is deferred until inflate() is called.
370 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
372 inflate decompresses as much data as possible, and stops when the input
373 buffer becomes empty or the output buffer becomes full. It may introduce
374 some output latency (reading input without producing any output) except when
375 forced to flush.
377 The detailed semantics are as follows. inflate performs one or both of the
378 following actions:
380 - Decompress more input starting at next_in and update next_in and avail_in
381 accordingly. If not all input can be processed (because there is not
382 enough room in the output buffer), next_in is updated and processing
383 will resume at this point for the next call of inflate().
385 - Provide more output starting at next_out and update next_out and avail_out
386 accordingly. inflate() provides as much output as possible, until there
387 is no more input data or no more space in the output buffer (see below
388 about the flush parameter).
390 Before the call of inflate(), the application should ensure that at least
391 one of the actions is possible, by providing more input and/or consuming
392 more output, and updating the next_* and avail_* values accordingly.
393 The application can consume the uncompressed output when it wants, for
394 example when the output buffer is full (avail_out == 0), or after each
395 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
396 must be called again after making room in the output buffer because there
397 might be more output pending.
399 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
400 Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
401 output as possible to the output buffer. Z_BLOCK requests that inflate() stop
402 if and when it gets to the next deflate block boundary. When decoding the
403 zlib or gzip format, this will cause inflate() to return immediately after
404 the header and before the first block. When doing a raw inflate, inflate()
405 will go ahead and process the first block, and will return when it gets to
406 the end of that block, or when it runs out of data.
408 The Z_BLOCK option assists in appending to or combining deflate streams.
409 Also to assist in this, on return inflate() will set strm->data_type to the
410 number of unused bits in the last byte taken from strm->next_in, plus 64
411 if inflate() is currently decoding the last block in the deflate stream,
412 plus 128 if inflate() returned immediately after decoding an end-of-block
413 code or decoding the complete header up to just before the first byte of the
414 deflate stream. The end-of-block will not be indicated until all of the
415 uncompressed data from that block has been written to strm->next_out. The
416 number of unused bits may in general be greater than seven, except when
417 bit 7 of data_type is set, in which case the number of unused bits will be
418 less than eight.
420 inflate() should normally be called until it returns Z_STREAM_END or an
421 error. However if all decompression is to be performed in a single step
422 (a single call of inflate), the parameter flush should be set to
423 Z_FINISH. In this case all pending input is processed and all pending
424 output is flushed; avail_out must be large enough to hold all the
425 uncompressed data. (The size of the uncompressed data may have been saved
426 by the compressor for this purpose.) The next operation on this stream must
427 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
428 is never required, but can be used to inform inflate that a faster approach
429 may be used for the single inflate() call.
431 In this implementation, inflate() always flushes as much output as
432 possible to the output buffer, and always uses the faster approach on the
433 first call. So the only effect of the flush parameter in this implementation
434 is on the return value of inflate(), as noted below, or when it returns early
435 because Z_BLOCK is used.
437 If a preset dictionary is needed after this call (see inflateSetDictionary
438 below), inflate sets strm->adler to the adler32 checksum of the dictionary
439 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
440 strm->adler to the adler32 checksum of all output produced so far (that is,
441 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
442 below. At the end of the stream, inflate() checks that its computed adler32
443 checksum is equal to that saved by the compressor and returns Z_STREAM_END
444 only if the checksum is correct.
446 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
447 deflate data. The header type is detected automatically. Any information
448 contained in the gzip header is not retained, so applications that need that
449 information should instead use raw inflate, see inflateInit2() below, or
450 inflateBack() and perform their own processing of the gzip header and
451 trailer.
453 inflate() returns Z_OK if some progress has been made (more input processed
454 or more output produced), Z_STREAM_END if the end of the compressed data has
455 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
456 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
457 corrupted (input stream not conforming to the zlib format or incorrect check
458 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
459 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
460 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
461 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
462 inflate() can be called again with more input and more output space to
463 continue decompressing. If Z_DATA_ERROR is returned, the application may then
464 call inflateSync() to look for a good compression block if a partial recovery
465 of the data is desired.
469 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
471 All dynamically allocated data structures for this stream are freed.
472 This function discards any unprocessed input and does not flush any
473 pending output.
475 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
476 was inconsistent. In the error case, msg may be set but then points to a
477 static string (which must not be deallocated).
480 /* Advanced functions */
483 The following functions are needed only in some special applications.
487 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
488 int level,
489 int method,
490 int windowBits,
491 int memLevel,
492 int strategy));
494 This is another version of deflateInit with more compression options. The
495 fields next_in, zalloc, zfree and opaque must be initialized before by
496 the caller.
498 The method parameter is the compression method. It must be Z_DEFLATED in
499 this version of the library.
501 The windowBits parameter is the base two logarithm of the window size
502 (the size of the history buffer). It should be in the range 8..15 for this
503 version of the library. Larger values of this parameter result in better
504 compression at the expense of memory usage. The default value is 15 if
505 deflateInit is used instead.
507 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
508 determines the window size. deflate() will then generate raw deflate data
509 with no zlib header or trailer, and will not compute an adler32 check value.
511 windowBits can also be greater than 15 for optional gzip encoding. Add
512 16 to windowBits to write a simple gzip header and trailer around the
513 compressed data instead of a zlib wrapper. The gzip header will have no
514 file name, no extra data, no comment, no modification time (set to zero),
515 no header crc, and the operating system will be set to 255 (unknown). If a
516 gzip stream is being written, strm->adler is a crc32 instead of an adler32.
518 The memLevel parameter specifies how much memory should be allocated
519 for the internal compression state. memLevel=1 uses minimum memory but
520 is slow and reduces compression ratio; memLevel=9 uses maximum memory
521 for optimal speed. The default value is 8. See zconf.h for total memory
522 usage as a function of windowBits and memLevel.
524 The strategy parameter is used to tune the compression algorithm. Use the
525 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
526 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
527 string match), or Z_RLE to limit match distances to one (run-length
528 encoding). Filtered data consists mostly of small values with a somewhat
529 random distribution. In this case, the compression algorithm is tuned to
530 compress them better. The effect of Z_FILTERED is to force more Huffman
531 coding and less string matching; it is somewhat intermediate between
532 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
533 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
534 parameter only affects the compression ratio but not the correctness of the
535 compressed output even if it is not set appropriately. Z_FIXED prevents the
536 use of dynamic Huffman codes, allowing for a simpler decoder for special
537 applications.
539 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
540 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
541 method). msg is set to null if there is no error message. deflateInit2 does
542 not perform any compression: this will be done by deflate().
545 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
546 const Bytef *dictionary,
547 uInt dictLength));
549 Initializes the compression dictionary from the given byte sequence
550 without producing any compressed output. This function must be called
551 immediately after deflateInit, deflateInit2 or deflateReset, before any
552 call of deflate. The compressor and decompressor must use exactly the same
553 dictionary (see inflateSetDictionary).
555 The dictionary should consist of strings (byte sequences) that are likely
556 to be encountered later in the data to be compressed, with the most commonly
557 used strings preferably put towards the end of the dictionary. Using a
558 dictionary is most useful when the data to be compressed is short and can be
559 predicted with good accuracy; the data can then be compressed better than
560 with the default empty dictionary.
562 Depending on the size of the compression data structures selected by
563 deflateInit or deflateInit2, a part of the dictionary may in effect be
564 discarded, for example if the dictionary is larger than the window size in
565 deflate or deflate2. Thus the strings most likely to be useful should be
566 put at the end of the dictionary, not at the front. In addition, the
567 current implementation of deflate will use at most the window size minus
568 262 bytes of the provided dictionary.
570 Upon return of this function, strm->adler is set to the adler32 value
571 of the dictionary; the decompressor may later use this value to determine
572 which dictionary has been used by the compressor. (The adler32 value
573 applies to the whole dictionary even if only a subset of the dictionary is
574 actually used by the compressor.) If a raw deflate was requested, then the
575 adler32 value is not computed and strm->adler is not set.
577 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
578 parameter is invalid (such as NULL dictionary) or the stream state is
579 inconsistent (for example if deflate has already been called for this stream
580 or if the compression method is bsort). deflateSetDictionary does not
581 perform any compression: this will be done by deflate().
584 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
585 z_streamp source));
587 Sets the destination stream as a complete copy of the source stream.
589 This function can be useful when several compression strategies will be
590 tried, for example when there are several ways of pre-processing the input
591 data with a filter. The streams that will be discarded should then be freed
592 by calling deflateEnd. Note that deflateCopy duplicates the internal
593 compression state which can be quite large, so this strategy is slow and
594 can consume lots of memory.
596 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
597 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
598 (such as zalloc being NULL). msg is left unchanged in both source and
599 destination.
602 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
604 This function is equivalent to deflateEnd followed by deflateInit,
605 but does not free and reallocate all the internal compression state.
606 The stream will keep the same compression level and any other attributes
607 that may have been set by deflateInit2.
609 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
610 stream state was inconsistent (such as zalloc or state being NULL).
613 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
614 int level,
615 int strategy));
617 Dynamically update the compression level and compression strategy. The
618 interpretation of level and strategy is as in deflateInit2. This can be
619 used to switch between compression and straight copy of the input data, or
620 to switch to a different kind of input data requiring a different
621 strategy. If the compression level is changed, the input available so far
622 is compressed with the old level (and may be flushed); the new level will
623 take effect only at the next call of deflate().
625 Before the call of deflateParams, the stream state must be set as for
626 a call of deflate(), since the currently available input may have to
627 be compressed and flushed. In particular, strm->avail_out must be non-zero.
629 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
630 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
631 if strm->avail_out was zero.
634 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
635 int good_length,
636 int max_lazy,
637 int nice_length,
638 int max_chain));
640 Fine tune deflate's internal compression parameters. This should only be
641 used by someone who understands the algorithm used by zlib's deflate for
642 searching for the best matching string, and even then only by the most
643 fanatic optimizer trying to squeeze out the last compressed bit for their
644 specific input data. Read the deflate.c source code for the meaning of the
645 max_lazy, good_length, nice_length, and max_chain parameters.
647 deflateTune() can be called after deflateInit() or deflateInit2(), and
648 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
651 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
652 uLong sourceLen));
654 deflateBound() returns an upper bound on the compressed size after
655 deflation of sourceLen bytes. It must be called after deflateInit() or
656 deflateInit2(), and after deflateSetHeader(), if used. This would be used
657 to allocate an output buffer for deflation in a single pass, and so would be
658 called before deflate().
661 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
662 int bits,
663 int value));
665 deflatePrime() inserts bits in the deflate output stream. The intent
666 is that this function is used to start off the deflate output with the
667 bits leftover from a previous deflate stream when appending to it. As such,
668 this function can only be used for raw deflate, and must be used before the
669 first deflate() call after a deflateInit2() or deflateReset(). bits must be
670 less than or equal to 16, and that many of the least significant bits of
671 value will be inserted in the output.
673 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
674 stream state was inconsistent.
677 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
678 gz_headerp head));
680 deflateSetHeader() provides gzip header information for when a gzip
681 stream is requested by deflateInit2(). deflateSetHeader() may be called
682 after deflateInit2() or deflateReset() and before the first call of
683 deflate(). The text, time, os, extra field, name, and comment information
684 in the provided gz_header structure are written to the gzip header (xflag is
685 ignored -- the extra flags are set according to the compression level). The
686 caller must assure that, if not Z_NULL, name and comment are terminated with
687 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
688 available there. If hcrc is true, a gzip header crc is included. Note that
689 the current versions of the command-line version of gzip (up through version
690 1.3.x) do not support header crc's, and will report that it is a "multi-part
691 gzip file" and give up.
693 If deflateSetHeader is not used, the default gzip header has text false,
694 the time set to zero, and os set to 255, with no extra, name, or comment
695 fields. The gzip header is returned to the default state by deflateReset().
697 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
698 stream state was inconsistent.
702 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
703 int windowBits));
705 This is another version of inflateInit with an extra parameter. The
706 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
707 before by the caller.
709 The windowBits parameter is the base two logarithm of the maximum window
710 size (the size of the history buffer). It should be in the range 8..15 for
711 this version of the library. The default value is 15 if inflateInit is used
712 instead. windowBits must be greater than or equal to the windowBits value
713 provided to deflateInit2() while compressing, or it must be equal to 15 if
714 deflateInit2() was not used. If a compressed stream with a larger window
715 size is given as input, inflate() will return with the error code
716 Z_DATA_ERROR instead of trying to allocate a larger window.
718 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
719 determines the window size. inflate() will then process raw deflate data,
720 not looking for a zlib or gzip header, not generating a check value, and not
721 looking for any check values for comparison at the end of the stream. This
722 is for use with other formats that use the deflate compressed data format
723 such as zip. Those formats provide their own check values. If a custom
724 format is developed using the raw deflate format for compressed data, it is
725 recommended that a check value such as an adler32 or a crc32 be applied to
726 the uncompressed data as is done in the zlib, gzip, and zip formats. For
727 most applications, the zlib format should be used as is. Note that comments
728 above on the use in deflateInit2() applies to the magnitude of windowBits.
730 windowBits can also be greater than 15 for optional gzip decoding. Add
731 32 to windowBits to enable zlib and gzip decoding with automatic header
732 detection, or add 16 to decode only the gzip format (the zlib format will
733 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
734 a crc32 instead of an adler32.
736 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
737 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
738 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
739 invalid, such as a null pointer to the structure. msg is set to null if
740 there is no error message. inflateInit2 does not perform any decompression
741 apart from possibly reading the zlib header if present: actual decompression
742 will be done by inflate(). (So next_in and avail_in may be modified, but
743 next_out and avail_out are unused and unchanged.) The current
744 implementation of inflateInit2() does not process any header information --
745 that is deferred until inflate() is called.
748 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
749 const Bytef *dictionary,
750 uInt dictLength));
752 Initializes the decompression dictionary from the given uncompressed byte
753 sequence. This function must be called immediately after a call of inflate,
754 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
755 can be determined from the adler32 value returned by that call of inflate.
756 The compressor and decompressor must use exactly the same dictionary (see
757 deflateSetDictionary). For raw inflate, this function can be called
758 immediately after inflateInit2() or inflateReset() and before any call of
759 inflate() to set the dictionary. The application must insure that the
760 dictionary that was used for compression is provided.
762 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
763 parameter is invalid (such as NULL dictionary) or the stream state is
764 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
765 expected one (incorrect adler32 value). inflateSetDictionary does not
766 perform any decompression: this will be done by subsequent calls of
767 inflate().
770 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
772 Skips invalid compressed data until a full flush point (see above the
773 description of deflate with Z_FULL_FLUSH) can be found, or until all
774 available input is skipped. No output is provided.
776 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
777 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
778 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
779 case, the application may save the current current value of total_in which
780 indicates where valid compressed data was found. In the error case, the
781 application may repeatedly call inflateSync, providing more input each time,
782 until success or end of the input data.
785 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
786 z_streamp source));
788 Sets the destination stream as a complete copy of the source stream.
790 This function can be useful when randomly accessing a large stream. The
791 first pass through the stream can periodically record the inflate state,
792 allowing restarting inflate at those points when randomly accessing the
793 stream.
795 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
796 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
797 (such as zalloc being NULL). msg is left unchanged in both source and
798 destination.
801 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
803 This function is equivalent to inflateEnd followed by inflateInit,
804 but does not free and reallocate all the internal decompression state.
805 The stream will keep attributes that may have been set by inflateInit2.
807 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
808 stream state was inconsistent (such as zalloc or state being NULL).
811 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
812 int bits,
813 int value));
815 This function inserts bits in the inflate input stream. The intent is
816 that this function is used to start inflating at a bit position in the
817 middle of a byte. The provided bits will be used before any bytes are used
818 from next_in. This function should only be used with raw inflate, and
819 should be used before the first inflate() call after inflateInit2() or
820 inflateReset(). bits must be less than or equal to 16, and that many of the
821 least significant bits of value will be inserted in the input.
823 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
824 stream state was inconsistent.
827 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
828 gz_headerp head));
830 inflateGetHeader() requests that gzip header information be stored in the
831 provided gz_header structure. inflateGetHeader() may be called after
832 inflateInit2() or inflateReset(), and before the first call of inflate().
833 As inflate() processes the gzip stream, head->done is zero until the header
834 is completed, at which time head->done is set to one. If a zlib stream is
835 being decoded, then head->done is set to -1 to indicate that there will be
836 no gzip header information forthcoming. Note that Z_BLOCK can be used to
837 force inflate() to return immediately after header processing is complete
838 and before any actual data is decompressed.
840 The text, time, xflags, and os fields are filled in with the gzip header
841 contents. hcrc is set to true if there is a header CRC. (The header CRC
842 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
843 contains the maximum number of bytes to write to extra. Once done is true,
844 extra_len contains the actual extra field length, and extra contains the
845 extra field, or that field truncated if extra_max is less than extra_len.
846 If name is not Z_NULL, then up to name_max characters are written there,
847 terminated with a zero unless the length is greater than name_max. If
848 comment is not Z_NULL, then up to comm_max characters are written there,
849 terminated with a zero unless the length is greater than comm_max. When
850 any of extra, name, or comment are not Z_NULL and the respective field is
851 not present in the header, then that field is set to Z_NULL to signal its
852 absence. This allows the use of deflateSetHeader() with the returned
853 structure to duplicate the header. However if those fields are set to
854 allocated memory, then the application will need to save those pointers
855 elsewhere so that they can be eventually freed.
857 If inflateGetHeader is not used, then the header information is simply
858 discarded. The header is always checked for validity, including the header
859 CRC if present. inflateReset() will reset the process to discard the header
860 information. The application would need to call inflateGetHeader() again to
861 retrieve the header from the next gzip stream.
863 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
864 stream state was inconsistent.
868 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
869 unsigned char FAR *window));
871 Initialize the internal stream state for decompression using inflateBack()
872 calls. The fields zalloc, zfree and opaque in strm must be initialized
873 before the call. If zalloc and zfree are Z_NULL, then the default library-
874 derived memory allocation routines are used. windowBits is the base two
875 logarithm of the window size, in the range 8..15. window is a caller
876 supplied buffer of that size. Except for special applications where it is
877 assured that deflate was used with small window sizes, windowBits must be 15
878 and a 32K byte window must be supplied to be able to decompress general
879 deflate streams.
881 See inflateBack() for the usage of these routines.
883 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
884 the paramaters are invalid, Z_MEM_ERROR if the internal state could not
885 be allocated, or Z_VERSION_ERROR if the version of the library does not
886 match the version of the header file.
889 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
890 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
892 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
893 in_func in, void FAR *in_desc,
894 out_func out, void FAR *out_desc));
896 inflateBack() does a raw inflate with a single call using a call-back
897 interface for input and output. This is more efficient than inflate() for
898 file i/o applications in that it avoids copying between the output and the
899 sliding window by simply making the window itself the output buffer. This
900 function trusts the application to not change the output buffer passed by
901 the output function, at least until inflateBack() returns.
903 inflateBackInit() must be called first to allocate the internal state
904 and to initialize the state with the user-provided window buffer.
905 inflateBack() may then be used multiple times to inflate a complete, raw
906 deflate stream with each call. inflateBackEnd() is then called to free
907 the allocated state.
909 A raw deflate stream is one with no zlib or gzip header or trailer.
910 This routine would normally be used in a utility that reads zip or gzip
911 files and writes out uncompressed files. The utility would decode the
912 header and process the trailer on its own, hence this routine expects
913 only the raw deflate stream to decompress. This is different from the
914 normal behavior of inflate(), which expects either a zlib or gzip header and
915 trailer around the deflate stream.
917 inflateBack() uses two subroutines supplied by the caller that are then
918 called by inflateBack() for input and output. inflateBack() calls those
919 routines until it reads a complete deflate stream and writes out all of the
920 uncompressed data, or until it encounters an error. The function's
921 parameters and return types are defined above in the in_func and out_func
922 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
923 number of bytes of provided input, and a pointer to that input in buf. If
924 there is no input available, in() must return zero--buf is ignored in that
925 case--and inflateBack() will return a buffer error. inflateBack() will call
926 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
927 should return zero on success, or non-zero on failure. If out() returns
928 non-zero, inflateBack() will return with an error. Neither in() nor out()
929 are permitted to change the contents of the window provided to
930 inflateBackInit(), which is also the buffer that out() uses to write from.
931 The length written by out() will be at most the window size. Any non-zero
932 amount of input may be provided by in().
934 For convenience, inflateBack() can be provided input on the first call by
935 setting strm->next_in and strm->avail_in. If that input is exhausted, then
936 in() will be called. Therefore strm->next_in must be initialized before
937 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
938 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
939 must also be initialized, and then if strm->avail_in is not zero, input will
940 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
942 The in_desc and out_desc parameters of inflateBack() is passed as the
943 first parameter of in() and out() respectively when they are called. These
944 descriptors can be optionally used to pass any information that the caller-
945 supplied in() and out() functions need to do their job.
947 On return, inflateBack() will set strm->next_in and strm->avail_in to
948 pass back any unused input that was provided by the last in() call. The
949 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
950 if in() or out() returned an error, Z_DATA_ERROR if there was a format
951 error in the deflate stream (in which case strm->msg is set to indicate the
952 nature of the error), or Z_STREAM_ERROR if the stream was not properly
953 initialized. In the case of Z_BUF_ERROR, an input or output error can be
954 distinguished using strm->next_in which will be Z_NULL only if in() returned
955 an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
956 out() returning non-zero. (in() will always be called before out(), so
957 strm->next_in is assured to be defined if out() returns non-zero.) Note
958 that inflateBack() cannot return Z_OK.
961 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
963 All memory allocated by inflateBackInit() is freed.
965 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
966 state was inconsistent.
969 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
970 /* Return flags indicating compile-time options.
972 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
973 1.0: size of uInt
974 3.2: size of uLong
975 5.4: size of voidpf (pointer)
976 7.6: size of z_off_t
978 Compiler, assembler, and debug options:
979 8: DEBUG
980 9: ASMV or ASMINF -- use ASM code
981 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
982 11: 0 (reserved)
984 One-time table building (smaller code, but not thread-safe if true):
985 12: BUILDFIXED -- build static block decoding tables when needed
986 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
987 14,15: 0 (reserved)
989 Library content (indicates missing functionality):
990 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
991 deflate code when not needed)
992 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
993 and decode gzip streams (to avoid linking crc code)
994 18-19: 0 (reserved)
996 Operation variations (changes in library functionality):
997 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
998 21: FASTEST -- deflate algorithm with only one, lowest compression level
999 22,23: 0 (reserved)
1001 The sprintf variant used by gzprintf (zero is best):
1002 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1003 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1004 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1006 Remainder:
1007 27-31: 0 (reserved)
1011 /* utility functions */
1014 The following utility functions are implemented on top of the
1015 basic stream-oriented functions. To simplify the interface, some
1016 default options are assumed (compression level and memory usage,
1017 standard memory allocation functions). The source code of these
1018 utility functions can easily be modified if you need special options.
1021 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1022 const Bytef *source, uLong sourceLen));
1024 Compresses the source buffer into the destination buffer. sourceLen is
1025 the byte length of the source buffer. Upon entry, destLen is the total
1026 size of the destination buffer, which must be at least the value returned
1027 by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1028 compressed buffer.
1029 This function can be used to compress a whole file at once if the
1030 input file is mmap'ed.
1031 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1032 enough memory, Z_BUF_ERROR if there was not enough room in the output
1033 buffer.
1036 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1037 const Bytef *source, uLong sourceLen,
1038 int level));
1040 Compresses the source buffer into the destination buffer. The level
1041 parameter has the same meaning as in deflateInit. sourceLen is the byte
1042 length of the source buffer. Upon entry, destLen is the total size of the
1043 destination buffer, which must be at least the value returned by
1044 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1045 compressed buffer.
1047 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1048 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1049 Z_STREAM_ERROR if the level parameter is invalid.
1052 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1054 compressBound() returns an upper bound on the compressed size after
1055 compress() or compress2() on sourceLen bytes. It would be used before
1056 a compress() or compress2() call to allocate the destination buffer.
1059 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1060 const Bytef *source, uLong sourceLen));
1062 Decompresses the source buffer into the destination buffer. sourceLen is
1063 the byte length of the source buffer. Upon entry, destLen is the total
1064 size of the destination buffer, which must be large enough to hold the
1065 entire uncompressed data. (The size of the uncompressed data must have
1066 been saved previously by the compressor and transmitted to the decompressor
1067 by some mechanism outside the scope of this compression library.)
1068 Upon exit, destLen is the actual size of the compressed buffer.
1069 This function can be used to decompress a whole file at once if the
1070 input file is mmap'ed.
1072 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1073 enough memory, Z_BUF_ERROR if there was not enough room in the output
1074 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1078 typedef voidp gzFile;
1081 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1083 Opens a gzip (.gz) file for reading or writing. The mode parameter
1084 is as in fopen ("rb" or "wb") but can also include a compression level
1085 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1086 Huffman only compression as in "wb1h", or 'R' for run-length encoding
1087 as in "wb1R". (See the description of deflateInit2 for more information
1088 about the strategy parameter.)
1090 gzopen can be used to read a file which is not in gzip format; in this
1091 case gzread will directly read from the file without decompression.
1093 gzopen returns NULL if the file could not be opened or if there was
1094 insufficient memory to allocate the (de)compression state; errno
1095 can be checked to distinguish the two cases (if errno is zero, the
1096 zlib error is Z_MEM_ERROR). */
1098 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1100 gzdopen() associates a gzFile with the file descriptor fd. File
1101 descriptors are obtained from calls like open, dup, creat, pipe or
1102 fileno (in the file has been previously opened with fopen).
1103 The mode parameter is as in gzopen.
1104 The next call of gzclose on the returned gzFile will also close the
1105 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1106 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1107 gzdopen returns NULL if there was insufficient memory to allocate
1108 the (de)compression state.
1111 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1113 Dynamically update the compression level or strategy. See the description
1114 of deflateInit2 for the meaning of these parameters.
1115 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1116 opened for writing.
1119 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1121 Reads the given number of uncompressed bytes from the compressed file.
1122 If the input file was not in gzip format, gzread copies the given number
1123 of bytes into the buffer.
1124 gzread returns the number of uncompressed bytes actually read (0 for
1125 end of file, -1 for error). */
1127 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1128 voidpc buf, unsigned len));
1130 Writes the given number of uncompressed bytes into the compressed file.
1131 gzwrite returns the number of uncompressed bytes actually written
1132 (0 in case of error).
1135 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
1137 Converts, formats, and writes the args to the compressed file under
1138 control of the format string, as in fprintf. gzprintf returns the number of
1139 uncompressed bytes actually written (0 in case of error). The number of
1140 uncompressed bytes written is limited to 4095. The caller should assure that
1141 this limit is not exceeded. If it is exceeded, then gzprintf() will return
1142 return an error (0) with nothing written. In this case, there may also be a
1143 buffer overflow with unpredictable consequences, which is possible only if
1144 zlib was compiled with the insecure functions sprintf() or vsprintf()
1145 because the secure snprintf() or vsnprintf() functions were not available.
1148 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1150 Writes the given null-terminated string to the compressed file, excluding
1151 the terminating null character.
1152 gzputs returns the number of characters written, or -1 in case of error.
1155 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1157 Reads bytes from the compressed file until len-1 characters are read, or
1158 a newline character is read and transferred to buf, or an end-of-file
1159 condition is encountered. The string is then terminated with a null
1160 character.
1161 gzgets returns buf, or Z_NULL in case of error.
1164 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1166 Writes c, converted to an unsigned char, into the compressed file.
1167 gzputc returns the value that was written, or -1 in case of error.
1170 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1172 Reads one byte from the compressed file. gzgetc returns this byte
1173 or -1 in case of end of file or error.
1176 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1178 Push one character back onto the stream to be read again later.
1179 Only one character of push-back is allowed. gzungetc() returns the
1180 character pushed, or -1 on failure. gzungetc() will fail if a
1181 character has been pushed but not read yet, or if c is -1. The pushed
1182 character will be discarded if the stream is repositioned with gzseek()
1183 or gzrewind().
1186 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1188 Flushes all pending output into the compressed file. The parameter
1189 flush is as in the deflate() function. The return value is the zlib
1190 error number (see function gzerror below). gzflush returns Z_OK if
1191 the flush parameter is Z_FINISH and all output could be flushed.
1192 gzflush should be called only when strictly necessary because it can
1193 degrade compression.
1197 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1198 z_off_t offset, int whence));
1200 Sets the starting position for the next gzread or gzwrite on the
1201 given compressed file. The offset represents a number of bytes in the
1202 uncompressed data stream. The whence parameter is defined as in lseek(2);
1203 the value SEEK_END is not supported.
1204 If the file is opened for reading, this function is emulated but can be
1205 extremely slow. If the file is opened for writing, only forward seeks are
1206 supported; gzseek then compresses a sequence of zeroes up to the new
1207 starting position.
1209 gzseek returns the resulting offset location as measured in bytes from
1210 the beginning of the uncompressed stream, or -1 in case of error, in
1211 particular if the file is opened for writing and the new starting position
1212 would be before the current position.
1215 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1217 Rewinds the given file. This function is supported only for reading.
1219 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1223 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1225 Returns the starting position for the next gzread or gzwrite on the
1226 given compressed file. This position represents a number of bytes in the
1227 uncompressed data stream.
1229 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1232 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1234 Returns 1 when EOF has previously been detected reading the given
1235 input stream, otherwise zero.
1238 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1240 Returns 1 if file is being read directly without decompression, otherwise
1241 zero.
1244 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1246 Flushes all pending output if necessary, closes the compressed file
1247 and deallocates all the (de)compression state. The return value is the zlib
1248 error number. Note that once file is close, you cannot call gzerror with
1249 file, since its structures have been deallocated.
1252 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1254 Returns the error message for the last error which occurred on the
1255 given compressed file. errnum is set to zlib error number. If an
1256 error occurred in the file system and not in the compression library,
1257 errnum is set to Z_ERRNO and the application may consult errno
1258 to get the exact error code.
1260 The application must not modify the returned string and future calls to
1261 this function may invalidate the returned string.
1264 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1266 Clears the error and end-of-file flags for file. This is analogous to the
1267 clearerr() function in stdio. This is useful for continuing to read a gzip
1268 file that is being written concurrently.
1271 /* checksum functions */
1274 These functions are not related to compression but are exported
1275 anyway because they might be useful in applications using the
1276 compression library.
1279 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1281 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1282 return the updated checksum. If buf is NULL, this function returns
1283 the required initial value for the checksum.
1284 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1285 much faster. Usage example:
1287 uLong adler = adler32(0L, Z_NULL, 0);
1289 while (read_buffer(buffer, length) != EOF) {
1290 adler = adler32(adler, buffer, length);
1292 if (adler != original_adler) error();
1296 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1297 z_off_t len2));
1299 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1300 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1301 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1302 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1305 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1307 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1308 updated CRC-32. If buf is NULL, this function returns the required initial
1309 value for the for the crc. Pre- and post-conditioning (one's complement) is
1310 performed within this function so it shouldn't be done by the application.
1311 Usage example:
1313 uLong crc = crc32(0L, Z_NULL, 0);
1315 while (read_buffer(buffer, length) != EOF) {
1316 crc = crc32(crc, buffer, length);
1318 if (crc != original_crc) error();
1322 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1324 Combine two CRC-32 check values into one. For two sequences of bytes,
1325 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1326 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1327 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1328 len2.
1332 /* various hacks, don't look :) */
1334 /* deflateInit and inflateInit are macros to allow checking the zlib version
1335 * and the compiler's view of z_stream:
1337 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1338 const char *version, int stream_size));
1339 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1340 const char *version, int stream_size));
1341 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1342 int windowBits, int memLevel,
1343 int strategy, const char *version,
1344 int stream_size));
1345 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1346 const char *version, int stream_size));
1347 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1348 unsigned char FAR *window,
1349 const char *version,
1350 int stream_size));
1351 #define deflateInit(strm, level) \
1352 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1353 #define inflateInit(strm) \
1354 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1355 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1356 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1357 (strategy), ZLIB_VERSION, sizeof(z_stream))
1358 #define inflateInit2(strm, windowBits) \
1359 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1360 #define inflateBackInit(strm, windowBits, window) \
1361 inflateBackInit_((strm), (windowBits), (window), \
1362 ZLIB_VERSION, sizeof(z_stream))
1364 #ifdef _LARGEFILE64_SOURCE
1365 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1366 ZEXTERN off64_t ZEXPORT gzseek64 OF((gzFile, off64_t, int));
1367 ZEXTERN off64_t ZEXPORT gztell64 OF((gzFile));
1368 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, off64_t));
1369 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, off64_t));
1370 #endif
1372 /* Mono: disable this. We don't use it and makes compilation fail
1373 #if _FILE_OFFSET_BITS == 64
1374 # define gzopen gzopen64
1375 # define gzseek gzseek64
1376 # define gztell gztell64
1377 # define adler32_combine adler32_combine64
1378 # define crc32_combine crc32_combine64
1379 #else
1381 ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1382 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1383 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1384 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1385 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1386 /*#endif*/
1388 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1389 struct internal_state {int dummy;}; /* hack for buggy compilers */
1390 #endif
1392 ZEXTERN const char * ZEXPORT zError OF((int));
1393 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1394 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1395 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1397 #ifdef __cplusplus
1399 #endif
1401 #endif /* ZLIB_H */