1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.0.5, September 8th, 2003
4 Copyright (C) 1995-2003 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).
40 #define ZLIB_VERSION "1.2.0.5"
41 #define ZLIB_VERNUM 0x1205
44 The 'zlib' compression library provides in-memory compression and
45 decompression functions, including integrity checks of the uncompressed
46 data. This version of the library supports only one compression method
47 (deflation) but other algorithms will be added later and will have the same
50 Compression can be done in a single step if the buffers are large
51 enough (for example if an input file is mmap'ed), or can be done by
52 repeated calls of the compression function. In the latter case, the
53 application must provide more input and/or consume the output
54 (providing more output space) before each call.
56 The compressed data format used by the in-memory functions is the zlib
57 format, which is a zlib wrapper documented in RFC 1950, wrapped around a
58 deflate stream, which is itself documented in RFC 1951.
60 The library also supports reading and writing files in gzip (.gz) format
61 with an interface similar to that of stdio using the functions that start
62 with "gz". The gzip format is different from the zlib format. gzip is a
63 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
65 The zlib format was designed to be compact and fast for use in memory
66 and on communications channels. The gzip format was designed for single-
67 file compression on file systems, has a larger header than zlib to maintain
68 directory information, and uses a different, slower check method than zlib.
70 This library does not provide any functions to write gzip files in memory.
71 However such functions could be easily written using zlib's deflate function,
72 the documentation in the gzip RFC, and the examples in gzio.c.
74 The library does not install any signal handler. The decoder checks
75 the consistency of the compressed data, so the library should never
76 crash even in case of corrupted input.
79 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
80 typedef void (*free_func) OF((voidpf opaque, voidpf address));
82 struct internal_state;
84 typedef struct z_stream_s {
85 Bytef *next_in; /* next input byte */
86 uInt avail_in; /* number of bytes available at next_in */
87 uLong total_in; /* total nb of input bytes read so far */
89 Bytef *next_out; /* next output byte should be put there */
90 uInt avail_out; /* remaining free space at next_out */
91 uLong total_out; /* total nb of bytes output so far */
93 char *msg; /* last error message, NULL if no error */
94 struct internal_state FAR *state; /* not visible by applications */
96 alloc_func zalloc; /* used to allocate the internal state */
97 free_func zfree; /* used to free the internal state */
98 voidpf opaque; /* private data object passed to zalloc and zfree */
100 int data_type; /* best guess about the data type: ascii or binary */
101 uLong adler; /* adler32 value of the uncompressed data */
102 uLong reserved; /* reserved for future use */
105 typedef z_stream FAR *z_streamp;
108 The application must update next_in and avail_in when avail_in has
109 dropped to zero. It must update next_out and avail_out when avail_out
110 has dropped to zero. The application must initialize zalloc, zfree and
111 opaque before calling the init function. All other fields are set by the
112 compression library and must not be updated by the application.
114 The opaque value provided by the application will be passed as the first
115 parameter for calls of zalloc and zfree. This can be useful for custom
116 memory management. The compression library attaches no meaning to the
119 zalloc must return Z_NULL if there is not enough memory for the object.
120 If zlib is used in a multi-threaded application, zalloc and zfree must be
123 On 16-bit systems, the functions zalloc and zfree must be able to allocate
124 exactly 65536 bytes, but will not be required to allocate more than this
125 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
126 pointers returned by zalloc for objects of exactly 65536 bytes *must*
127 have their offset normalized to zero. The default allocation function
128 provided by this library ensures this (see zutil.c). To reduce memory
129 requirements and avoid any allocation of 64K objects, at the expense of
130 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
132 The fields total_in and total_out can be used for statistics or
133 progress reports. After compression, total_in holds the total size of
134 the uncompressed data and may be saved for use in the decompressor
135 (particularly if the decompressor wants to decompress everything in
142 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
143 #define Z_SYNC_FLUSH 2
144 #define Z_FULL_FLUSH 3
147 /* Allowed flush values; see deflate() and inflate() below for details */
150 #define Z_STREAM_END 1
151 #define Z_NEED_DICT 2
153 #define Z_STREAM_ERROR (-2)
154 #define Z_DATA_ERROR (-3)
155 #define Z_MEM_ERROR (-4)
156 #define Z_BUF_ERROR (-5)
157 #define Z_VERSION_ERROR (-6)
158 /* Return codes for the compression/decompression functions. Negative
159 * values are errors, positive values are used for special but normal events.
162 #define Z_NO_COMPRESSION 0
163 #define Z_BEST_SPEED 1
164 #define Z_BEST_COMPRESSION 9
165 #define Z_DEFAULT_COMPRESSION (-1)
166 /* compression levels */
169 #define Z_HUFFMAN_ONLY 2
171 #define Z_DEFAULT_STRATEGY 0
172 /* compression strategy; see deflateInit2() below for details */
177 /* Possible values of the data_type field */
180 /* The deflate compression method (the only one supported in this version) */
182 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
184 #define zlib_version zlibVersion()
185 /* for compatibility with versions < 1.0.2 */
187 /* basic functions */
189 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
190 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
191 If the first character differs, the library code actually used is
192 not compatible with the zlib.h header file used by the application.
193 This check is automatically made by deflateInit and inflateInit.
197 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
199 Initializes the internal stream state for compression. The fields
200 zalloc, zfree and opaque must be initialized before by the caller.
201 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
202 use default allocation functions.
204 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
205 1 gives best speed, 9 gives best compression, 0 gives no compression at
206 all (the input data is simply copied a block at a time).
207 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
208 compression (currently equivalent to level 6).
210 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
211 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
212 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
213 with the version assumed by the caller (ZLIB_VERSION).
214 msg is set to null if there is no error message. deflateInit does not
215 perform any compression: this will be done by deflate().
219 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
221 deflate compresses as much data as possible, and stops when the input
222 buffer becomes empty or the output buffer becomes full. It may introduce some
223 output latency (reading input without producing any output) except when
226 The detailed semantics are as follows. deflate performs one or both of the
229 - Compress more input starting at next_in and update next_in and avail_in
230 accordingly. If not all input can be processed (because there is not
231 enough room in the output buffer), next_in and avail_in are updated and
232 processing will resume at this point for the next call of deflate().
234 - Provide more output starting at next_out and update next_out and avail_out
235 accordingly. This action is forced if the parameter flush is non zero.
236 Forcing flush frequently degrades the compression ratio, so this parameter
237 should be set only when necessary (in interactive applications).
238 Some output may be provided even if flush is not set.
240 Before the call of deflate(), the application should ensure that at least
241 one of the actions is possible, by providing more input and/or consuming
242 more output, and updating avail_in or avail_out accordingly; avail_out
243 should never be zero before the call. The application can consume the
244 compressed output when it wants, for example when the output buffer is full
245 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
246 and with zero avail_out, it must be called again after making room in the
247 output buffer because there might be more output pending.
249 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
250 flushed to the output buffer and the output is aligned on a byte boundary, so
251 that the decompressor can get all input data available so far. (In particular
252 avail_in is zero after the call if enough output space has been provided
253 before the call.) Flushing may degrade compression for some compression
254 algorithms and so it should be used only when necessary.
256 If flush is set to Z_FULL_FLUSH, all output is flushed as with
257 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
258 restart from this point if previous compressed data has been damaged or if
259 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
262 If deflate returns with avail_out == 0, this function must be called again
263 with the same value of the flush parameter and more output space (updated
264 avail_out), until the flush is complete (deflate returns with non-zero
265 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
266 avail_out is greater than six to avoid repeated flush markers due to
267 avail_out == 0 on return.
269 If the parameter flush is set to Z_FINISH, pending input is processed,
270 pending output is flushed and deflate returns with Z_STREAM_END if there
271 was enough output space; if deflate returns with Z_OK, this function must be
272 called again with Z_FINISH and more output space (updated avail_out) but no
273 more input data, until it returns with Z_STREAM_END or an error. After
274 deflate has returned Z_STREAM_END, the only possible operations on the
275 stream are deflateReset or deflateEnd.
277 Z_FINISH can be used immediately after deflateInit if all the compression
278 is to be done in a single step. In this case, avail_out must be at least
279 the value returned by deflateBound (see below). If deflate does not return
280 Z_STREAM_END, then it must be called again as described above.
282 deflate() sets strm->adler to the adler32 checksum of all input read
283 so far (that is, total_in bytes).
285 deflate() may update data_type if it can make a good guess about
286 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
287 binary. This field is only for information purposes and does not affect
288 the compression algorithm in any manner.
290 deflate() returns Z_OK if some progress has been made (more input
291 processed or more output produced), Z_STREAM_END if all input has been
292 consumed and all output has been produced (only when flush is set to
293 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
294 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
295 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
296 fatal, and deflate() can be called again with more input and more output
297 space to continue compressing.
301 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
303 All dynamically allocated data structures for this stream are freed.
304 This function discards any unprocessed input and does not flush any
307 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
308 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
309 prematurely (some input or output was discarded). In the error case,
310 msg may be set but then points to a static string (which must not be
316 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
318 Initializes the internal stream state for decompression. The fields
319 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
320 the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
321 value depends on the compression method), inflateInit determines the
322 compression method from the zlib header and allocates all data structures
323 accordingly; otherwise the allocation will be deferred to the first call of
324 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
325 use default allocation functions.
327 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
328 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
329 version assumed by the caller. msg is set to null if there is no error
330 message. inflateInit does not perform any decompression apart from reading
331 the zlib header if present: this will be done by inflate(). (So next_in and
332 avail_in may be modified, but next_out and avail_out are unchanged.)
336 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
338 inflate decompresses as much data as possible, and stops when the input
339 buffer becomes empty or the output buffer becomes full. It may introduce
340 some output latency (reading input without producing any output) except when
343 The detailed semantics are as follows. inflate performs one or both of the
346 - Decompress more input starting at next_in and update next_in and avail_in
347 accordingly. If not all input can be processed (because there is not
348 enough room in the output buffer), next_in is updated and processing
349 will resume at this point for the next call of inflate().
351 - Provide more output starting at next_out and update next_out and avail_out
352 accordingly. inflate() provides as much output as possible, until there
353 is no more input data or no more space in the output buffer (see below
354 about the flush parameter).
356 Before the call of inflate(), the application should ensure that at least
357 one of the actions is possible, by providing more input and/or consuming
358 more output, and updating the next_* and avail_* values accordingly.
359 The application can consume the uncompressed output when it wants, for
360 example when the output buffer is full (avail_out == 0), or after each
361 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
362 must be called again after making room in the output buffer because there
363 might be more output pending.
365 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
366 Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
367 output as possible to the output buffer. Z_BLOCK requests that inflate() stop
368 if and when it get to the next deflate block boundary. When decoding the zlib
369 or gzip format, this will cause inflate() to return immediately after the
370 header and before the first block. When doing a raw inflate, inflate() will
371 go ahead and process the first block, and will return when it gets to the end
372 of that block, or when it runs out of data.
374 The Z_BLOCK option assists in appending to or combining deflate streams.
375 Also to assist in this, on return inflate() will set strm->data_type to the
376 number of unused bits in the last byte taken from strm->next_in, plus eight
377 if inflate() is currently decoding the last block in the deflate stream,
378 plus 16 if inflate() returned immediately after decoding an end-of-block
379 code or decoding the complete header up just before the first byte of the
380 deflate stream. The end-of-block will not be indicated until all of the
381 uncompressed data from that block has been written to strm->next_out.
383 inflate() should normally be called until it returns Z_STREAM_END or an
384 error. However if all decompression is to be performed in a single step
385 (a single call of inflate), the parameter flush should be set to
386 Z_FINISH. In this case all pending input is processed and all pending
387 output is flushed; avail_out must be large enough to hold all the
388 uncompressed data. (The size of the uncompressed data may have been saved
389 by the compressor for this purpose.) The next operation on this stream must
390 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
391 is never required, but can be used to inform inflate that a faster approach
392 may be used for the single inflate() call.
394 In this implementation, inflate() always flushes as much output as
395 possible to the output buffer, and always uses the faster approach on the
396 first call. So the only effect of the flush parameter in this implementation
397 is on the return value of inflate(), as noted below, or when it returns early
398 because Z_BLOCK is used.
400 If a preset dictionary is needed after this call (see inflateSetDictionary
401 below), inflate sets strm-adler to the adler32 checksum of the dictionary
402 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
403 strm->adler to the adler32 checksum of all output produced so far (that is,
404 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
405 below. At the end of the stream, inflate() checks that its computed adler32
406 checksum is equal to that saved by the compressor and returns Z_STREAM_END
407 only if the checksum is correct.
409 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
410 deflate data. The header type is detected automatically. Any information
411 contained in the gzip header is not retained, so applications that need that
412 information should instead use raw inflate, see inflateInit2() below, or
413 inflateBack() and perform their own processing of the gzip header and
416 inflate() returns Z_OK if some progress has been made (more input processed
417 or more output produced), Z_STREAM_END if the end of the compressed data has
418 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
419 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
420 corrupted (input stream not conforming to the zlib format or incorrect check
421 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
422 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
423 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
424 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
425 inflate() can be called again with more input and more output space to
426 continue decompressing. If Z_DATA_ERROR is returned, the application may then
427 call inflateSync() to look for a good compression block if a partial recovery
428 of the data is desired.
432 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
434 All dynamically allocated data structures for this stream are freed.
435 This function discards any unprocessed input and does not flush any
438 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
439 was inconsistent. In the error case, msg may be set but then points to a
440 static string (which must not be deallocated).
443 /* Advanced functions */
446 The following functions are needed only in some special applications.
450 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
457 This is another version of deflateInit with more compression options. The
458 fields next_in, zalloc, zfree and opaque must be initialized before by
461 The method parameter is the compression method. It must be Z_DEFLATED in
462 this version of the library.
464 The windowBits parameter is the base two logarithm of the window size
465 (the size of the history buffer). It should be in the range 8..15 for this
466 version of the library. Larger values of this parameter result in better
467 compression at the expense of memory usage. The default value is 15 if
468 deflateInit is used instead.
470 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
471 determines the window size. deflate() will then generate raw deflate data
472 with no zlib header or trailer, and will not compute an adler32 check value.
474 windowBits can also be greater than 15 for optional gzip encoding. Add
475 16 to windowBits to write a simple gzip header and trailer around the
476 compressed data instead of a zlib wrapper. The gzip header will have no
477 file name, no extra data, no comment, no modification time (set to zero),
478 no header crc, and the operating system will be set to 255 (unknown).
480 The memLevel parameter specifies how much memory should be allocated
481 for the internal compression state. memLevel=1 uses minimum memory but
482 is slow and reduces compression ratio; memLevel=9 uses maximum memory
483 for optimal speed. The default value is 8. See zconf.h for total memory
484 usage as a function of windowBits and memLevel.
486 The strategy parameter is used to tune the compression algorithm. Use the
487 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
488 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
489 string match), or Z_RLE to limit match distances to one (run-length
490 encoding). Filtered data consists mostly of small values with a somewhat
491 random distribution. In this case, the compression algorithm is tuned to
492 compress them better. The effect of Z_FILTERED is to force more Huffman
493 coding and less string matching; it is somewhat intermediate between
494 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
495 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
496 parameter only affects the compression ratio but not the correctness of the
497 compressed output even if it is not set appropriately.
499 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
500 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
501 method). msg is set to null if there is no error message. deflateInit2 does
502 not perform any compression: this will be done by deflate().
505 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
506 const Bytef *dictionary,
509 Initializes the compression dictionary from the given byte sequence
510 without producing any compressed output. This function must be called
511 immediately after deflateInit, deflateInit2 or deflateReset, before any
512 call of deflate. The compressor and decompressor must use exactly the same
513 dictionary (see inflateSetDictionary).
515 The dictionary should consist of strings (byte sequences) that are likely
516 to be encountered later in the data to be compressed, with the most commonly
517 used strings preferably put towards the end of the dictionary. Using a
518 dictionary is most useful when the data to be compressed is short and can be
519 predicted with good accuracy; the data can then be compressed better than
520 with the default empty dictionary.
522 Depending on the size of the compression data structures selected by
523 deflateInit or deflateInit2, a part of the dictionary may in effect be
524 discarded, for example if the dictionary is larger than the window size in
525 deflate or deflate2. Thus the strings most likely to be useful should be
526 put at the end of the dictionary, not at the front.
528 Upon return of this function, strm->adler is set to the adler32 value
529 of the dictionary; the decompressor may later use this value to determine
530 which dictionary has been used by the compressor. (The adler32 value
531 applies to the whole dictionary even if only a subset of the dictionary is
532 actually used by the compressor.) If a raw deflate was requested, then the
533 adler32 value is not computed and strm->adler is not set.
535 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
536 parameter is invalid (such as NULL dictionary) or the stream state is
537 inconsistent (for example if deflate has already been called for this stream
538 or if the compression method is bsort). deflateSetDictionary does not
539 perform any compression: this will be done by deflate().
542 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
545 Sets the destination stream as a complete copy of the source stream.
547 This function can be useful when several compression strategies will be
548 tried, for example when there are several ways of pre-processing the input
549 data with a filter. The streams that will be discarded should then be freed
550 by calling deflateEnd. Note that deflateCopy duplicates the internal
551 compression state which can be quite large, so this strategy is slow and
552 can consume lots of memory.
554 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
555 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
556 (such as zalloc being NULL). msg is left unchanged in both source and
560 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
562 This function is equivalent to deflateEnd followed by deflateInit,
563 but does not free and reallocate all the internal compression state.
564 The stream will keep the same compression level and any other attributes
565 that may have been set by deflateInit2.
567 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
568 stream state was inconsistent (such as zalloc or state being NULL).
571 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
575 Dynamically update the compression level and compression strategy. The
576 interpretation of level and strategy is as in deflateInit2. This can be
577 used to switch between compression and straight copy of the input data, or
578 to switch to a different kind of input data requiring a different
579 strategy. If the compression level is changed, the input available so far
580 is compressed with the old level (and may be flushed); the new level will
581 take effect only at the next call of deflate().
583 Before the call of deflateParams, the stream state must be set as for
584 a call of deflate(), since the currently available input may have to
585 be compressed and flushed. In particular, strm->avail_out must be non-zero.
587 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
588 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
589 if strm->avail_out was zero.
592 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
595 deflateBound() returns an upper bound on the compressed size after
596 deflation of sourceLen bytes. It must be called after deflateInit()
597 or deflateInit2(). This would be used to allocate an output buffer
598 for deflation in a single pass, and so would be called before deflate().
602 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
605 This is another version of inflateInit with an extra parameter. The
606 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
607 before by the caller.
609 The windowBits parameter is the base two logarithm of the maximum window
610 size (the size of the history buffer). It should be in the range 8..15 for
611 this version of the library. The default value is 15 if inflateInit is used
612 instead. windowBits must be greater than or equal to the windowBits value
613 provided to deflateInit2() while compressing, or it must be equal to 15 if
614 deflateInit2() was not used. If a compressed stream with a larger window
615 size is given as input, inflate() will return with the error code
616 Z_DATA_ERROR instead of trying to allocate a larger window.
618 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
619 determines the window size. inflate() will then process raw deflate data,
620 not looking for a zlib or gzip header, not generating a check value, and not
621 looking for any check values for comparison at the end of the stream. This
622 is for use with other formats that use the deflate compressed data format
623 such as zip. Those formats provide their own check values. If a custom
624 format is developed using the raw deflate format for compressed data, it is
625 recommended that a check value such as an adler32 or a crc32 be applied to
626 the uncompressed data as is done in the zlib, gzip, and zip formats. For
627 most applications, the zlib format should be used as is. Note that comments
628 above on the use in deflateInit2() applies to the magnitude of windowBits.
630 windowBits can also be greater than 15 for optional gzip decoding. Add
631 32 to windowBits to enable zlib and gzip decoding with automatic header
632 detection, or add 16 to decode only the gzip format (the zlib format will
633 return a Z_DATA_ERROR).
635 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
636 memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
637 memLevel). msg is set to null if there is no error message. inflateInit2
638 does not perform any decompression apart from reading the zlib header if
639 present: this will be done by inflate(). (So next_in and avail_in may be
640 modified, but next_out and avail_out are unchanged.)
643 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
644 const Bytef *dictionary,
647 Initializes the decompression dictionary from the given uncompressed byte
648 sequence. This function must be called immediately after a call of inflate
649 if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
650 can be determined from the adler32 value returned by this call of
651 inflate. The compressor and decompressor must use exactly the same
652 dictionary (see deflateSetDictionary).
654 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
655 parameter is invalid (such as NULL dictionary) or the stream state is
656 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
657 expected one (incorrect adler32 value). inflateSetDictionary does not
658 perform any decompression: this will be done by subsequent calls of
662 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
664 Skips invalid compressed data until a full flush point (see above the
665 description of deflate with Z_FULL_FLUSH) can be found, or until all
666 available input is skipped. No output is provided.
668 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
669 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
670 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
671 case, the application may save the current current value of total_in which
672 indicates where valid compressed data was found. In the error case, the
673 application may repeatedly call inflateSync, providing more input each time,
674 until success or end of the input data.
677 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
680 Sets the destination stream as a complete copy of the source stream.
682 This function can be useful when randomly accessing a large stream. The
683 first pass through the stream can periodically record the inflate state,
684 allowing restarting inflate at those points when randomly accessing the
687 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
688 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
689 (such as zalloc being NULL). msg is left unchanged in both source and
693 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
695 This function is equivalent to inflateEnd followed by inflateInit,
696 but does not free and reallocate all the internal decompression state.
697 The stream will keep attributes that may have been set by inflateInit2.
699 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
700 stream state was inconsistent (such as zalloc or state being NULL).
704 ZEXTERN int ZEXPORT inflateBackInit OF((z_stream FAR *strm, int windowBits,
705 unsigned char FAR *window));
707 Initialize the internal stream state for decompression using inflateBack()
708 calls. The fields zalloc, zfree and opaque in strm must be initialized
709 before the call. If zalloc and zfree are Z_NULL, then the default library-
710 derived memory allocation routines are used. windowBits is the base two
711 logarithm of the window size, in the range 8..15. window is a caller
712 supplied buffer of that size. Except for special applications where it is
713 assured that deflate was used with small window sizes, windowBits must be 15
714 and a 32K byte window must be supplied to be able to decompress general
717 See inflateBack() for the usage of these routines.
719 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
720 the paramaters are invalid, Z_MEM_ERROR if the internal state could not
721 be allocated, or Z_VERSION_ERROR if the version of the library does not
722 match the version of the header file.
725 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
726 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
728 ZEXTERN int ZEXPORT inflateBack OF((z_stream FAR *strm,
729 in_func in, void FAR *in_desc,
730 out_func out, void FAR *out_desc));
732 inflateBack() does a raw inflate with a single call using a call-back
733 interface for input and output. This is more efficient than inflate() for
734 file i/o applications in that it avoids copying between the output and the
735 sliding window by simply making the window itself the output buffer. This
736 function trusts the application to not change the output buffer passed by
737 the output function, at least until inflateBack() returns.
739 inflateBackInit() must be called first to allocate the internal state
740 and to initialize the state with the user-provided window buffer.
741 inflateBack() may then be used multiple times to inflate a complete, raw
742 deflate stream with each call. inflateBackEnd() is then called to free
745 A raw deflate stream is one with no zlib or gzip header or trailer.
746 This routine would normally be used in a utility that reads zip or gzip
747 files and writes out uncompressed files. The utility would decode the
748 header and process the trailer on its own, hence this routine expects
749 only the raw deflate stream to decompress. This is different from the
750 normal behavior of inflate(), which expects either a zlib or gzip header and
751 trailer around the deflate stream.
753 inflateBack() uses two subroutines supplied by the caller that are then
754 called by inflateBack() for input and output. inflateBack() calls those
755 routines until it reads a complete deflate stream and writes out all of the
756 uncompressed data, or until it encounters an error. The function's
757 parameters and return types are defined above in the in_func and out_func
758 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
759 number of bytes of provided input, and a pointer to that input in buf. If
760 there is no input available, in() must return zero--buf is ignored in that
761 case--and inflateBack() will return a buffer error. inflateBack() will call
762 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
763 should return zero on success, or non-zero on failure. If out() returns
764 non-zero, inflateBack() will return with an error. Neither in() nor out()
765 are permitted to change the contents of the window provided to
766 inflateBackInit(), which is also the buffer that out() uses to write from.
767 The length written by out() will be at most the window size. Any non-zero
768 amount of input may be provided by in().
770 For convenience, inflateBack() can be provided input on the first call by
771 setting strm->next_in and strm->avail_in. If that input is exhausted, then
772 in() will be called. Therefore strm->next_in must be initialized before
773 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
774 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
775 must also be initialized, and then if strm->avail_in is not zero, input will
776 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
778 The in_desc and out_desc parameters of inflateBack() is passed as the
779 first parameter of in() and out() respectively when they are called. These
780 descriptors can be optinally used to pass any information that the caller-
781 supplied in() and out() functions need to do their job.
783 On return, inflateBack() will set strm->next_in and strm->avail_in to
784 pass back any unused input that was provided by the last in() call. The
785 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
786 if in() or out() returned an error, Z_DATA_ERROR if there was a format
787 error in the deflate stream (in which case strm->msg is set to indicate the
788 nature of the error), or Z_STREAM_ERROR if the stream was not properly
789 initialized. In the case of Z_BUF_ERROR, an input or output error can be
790 distinguished using strm->next_in which will be Z_NULL only if in() returned
791 an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
792 out() returning non-zero. (in() will always be called before out(), so
793 strm->next_in is assured to be defined if out() returns non-zero.) Note
794 that inflateBack() cannot return Z_OK.
797 ZEXTERN int ZEXPORT inflateBackEnd OF((z_stream FAR *strm));
799 All memory allocated by inflateBackInit() is freed.
801 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
802 state was inconsistent.
805 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
806 /* Return flags indicating compile-time options.
808 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
811 5.4: size of voidpf (pointer)
814 Compiler, assembler, and debug options:
816 9: ASMV or ASMINF -- use ASM code
817 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
820 One-time table building (smaller code, but not thread-safe if true):
821 12: BUILDFIXED -- build static block decoding tables when needed
822 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
825 Library content (indicates missing functionality):
826 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
827 deflate code when not needed)
828 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
829 and decode gzip streams (to avoid linking crc code)
832 Operation variations (changes in library functionality):
833 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
834 21: FASTEST -- deflate algorithm with only one, lowest compression level
837 The sprintf variant used by gzprintf (zero is best):
838 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
839 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
840 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
847 /* utility functions */
850 The following utility functions are implemented on top of the
851 basic stream-oriented functions. To simplify the interface, some
852 default options are assumed (compression level and memory usage,
853 standard memory allocation functions). The source code of these
854 utility functions can easily be modified if you need special options.
857 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
858 const Bytef *source, uLong sourceLen));
860 Compresses the source buffer into the destination buffer. sourceLen is
861 the byte length of the source buffer. Upon entry, destLen is the total
862 size of the destination buffer, which must be at least the value returned
863 by compressBound(sourceLen). Upon exit, destLen is the actual size of the
865 This function can be used to compress a whole file at once if the
866 input file is mmap'ed.
867 compress returns Z_OK if success, Z_MEM_ERROR if there was not
868 enough memory, Z_BUF_ERROR if there was not enough room in the output
872 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
873 const Bytef *source, uLong sourceLen,
876 Compresses the source buffer into the destination buffer. The level
877 parameter has the same meaning as in deflateInit. sourceLen is the byte
878 length of the source buffer. Upon entry, destLen is the total size of the
879 destination buffer, which must be at least the value returned by
880 compressBound(sourceLen). Upon exit, destLen is the actual size of the
883 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
884 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
885 Z_STREAM_ERROR if the level parameter is invalid.
888 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
890 compressBound() returns an upper bound on the compressed size after
891 compress() or compress2() on sourceLen bytes. It would be used before
892 a compress() or compress2() call to allocate the destination buffer.
895 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
896 const Bytef *source, uLong sourceLen));
898 Decompresses the source buffer into the destination buffer. sourceLen is
899 the byte length of the source buffer. Upon entry, destLen is the total
900 size of the destination buffer, which must be large enough to hold the
901 entire uncompressed data. (The size of the uncompressed data must have
902 been saved previously by the compressor and transmitted to the decompressor
903 by some mechanism outside the scope of this compression library.)
904 Upon exit, destLen is the actual size of the compressed buffer.
905 This function can be used to decompress a whole file at once if the
906 input file is mmap'ed.
908 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
909 enough memory, Z_BUF_ERROR if there was not enough room in the output
910 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
914 typedef voidp gzFile;
916 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
918 Opens a gzip (.gz) file for reading or writing. The mode parameter
919 is as in fopen ("rb" or "wb") but can also include a compression level
920 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
921 Huffman only compression as in "wb1h", or 'R' for run-length encoding
922 as in "wb1R". (See the description of deflateInit2 for more information
923 about the strategy parameter.)
925 gzopen can be used to read a file which is not in gzip format; in this
926 case gzread will directly read from the file without decompression.
928 gzopen returns NULL if the file could not be opened or if there was
929 insufficient memory to allocate the (de)compression state; errno
930 can be checked to distinguish the two cases (if errno is zero, the
931 zlib error is Z_MEM_ERROR). */
933 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
935 gzdopen() associates a gzFile with the file descriptor fd. File
936 descriptors are obtained from calls like open, dup, creat, pipe or
937 fileno (in the file has been previously opened with fopen).
938 The mode parameter is as in gzopen.
939 The next call of gzclose on the returned gzFile will also close the
940 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
941 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
942 gzdopen returns NULL if there was insufficient memory to allocate
943 the (de)compression state.
946 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
948 Dynamically update the compression level or strategy. See the description
949 of deflateInit2 for the meaning of these parameters.
950 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
954 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
956 Reads the given number of uncompressed bytes from the compressed file.
957 If the input file was not in gzip format, gzread copies the given number
958 of bytes into the buffer.
959 gzread returns the number of uncompressed bytes actually read (0 for
960 end of file, -1 for error). */
962 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
963 voidpc buf, unsigned len));
965 Writes the given number of uncompressed bytes into the compressed file.
966 gzwrite returns the number of uncompressed bytes actually written
967 (0 in case of error).
970 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
972 Converts, formats, and writes the args to the compressed file under
973 control of the format string, as in fprintf. gzprintf returns the number of
974 uncompressed bytes actually written (0 in case of error). The number of
975 uncompressed bytes written is limited to 4095. The caller should assure that
976 this limit is not exceeded. If it is exceeded, then gzprintf() will return
977 return an error (0) with nothing written. In this case, there may also be a
978 buffer overflow with unpredictable consequences, which is possible only if
979 zlib was compiled with the insecure functions sprintf() or vsprintf()
980 because the secure snprintf() or vsnprintf() functions were not available.
983 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
985 Writes the given null-terminated string to the compressed file, excluding
986 the terminating null character.
987 gzputs returns the number of characters written, or -1 in case of error.
990 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
992 Reads bytes from the compressed file until len-1 characters are read, or
993 a newline character is read and transferred to buf, or an end-of-file
994 condition is encountered. The string is then terminated with a null
996 gzgets returns buf, or Z_NULL in case of error.
999 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1001 Writes c, converted to an unsigned char, into the compressed file.
1002 gzputc returns the value that was written, or -1 in case of error.
1005 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1007 Reads one byte from the compressed file. gzgetc returns this byte
1008 or -1 in case of end of file or error.
1011 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1013 Push one character back onto the stream to be read again later.
1014 Only one character of push-back is allowed. gzungetc() returns the
1015 character pushed, or -1 on failure. gzungetc() will fail if a
1016 character has been pushed but not read yet, or if c is -1. The pushed
1017 character will be discarded if the stream is repositioned with gzseek()
1021 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1023 Flushes all pending output into the compressed file. The parameter
1024 flush is as in the deflate() function. The return value is the zlib
1025 error number (see function gzerror below). gzflush returns Z_OK if
1026 the flush parameter is Z_FINISH and all output could be flushed.
1027 gzflush should be called only when strictly necessary because it can
1028 degrade compression.
1031 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1032 z_off_t offset, int whence));
1034 Sets the starting position for the next gzread or gzwrite on the
1035 given compressed file. The offset represents a number of bytes in the
1036 uncompressed data stream. The whence parameter is defined as in lseek(2);
1037 the value SEEK_END is not supported.
1038 If the file is opened for reading, this function is emulated but can be
1039 extremely slow. If the file is opened for writing, only forward seeks are
1040 supported; gzseek then compresses a sequence of zeroes up to the new
1043 gzseek returns the resulting offset location as measured in bytes from
1044 the beginning of the uncompressed stream, or -1 in case of error, in
1045 particular if the file is opened for writing and the new starting position
1046 would be before the current position.
1049 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1051 Rewinds the given file. This function is supported only for reading.
1053 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1056 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1058 Returns the starting position for the next gzread or gzwrite on the
1059 given compressed file. This position represents a number of bytes in the
1060 uncompressed data stream.
1062 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1065 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1067 Returns 1 when EOF has previously been detected reading the given
1068 input stream, otherwise zero.
1071 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1073 Flushes all pending output if necessary, closes the compressed file
1074 and deallocates all the (de)compression state. The return value is the zlib
1075 error number (see function gzerror below).
1078 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1080 Returns the error message for the last error which occurred on the
1081 given compressed file. errnum is set to zlib error number. If an
1082 error occurred in the file system and not in the compression library,
1083 errnum is set to Z_ERRNO and the application may consult errno
1084 to get the exact error code.
1087 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1089 Clears the error and end-of-file flags for file. This is analogous to the
1090 clearerr() function in stdio. This is useful for continuing to read a gzip
1091 file that is being written concurrently.
1094 /* checksum functions */
1097 These functions are not related to compression but are exported
1098 anyway because they might be useful in applications using the
1099 compression library.
1102 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1105 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1106 return the updated checksum. If buf is NULL, this function returns
1107 the required initial value for the checksum.
1108 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1109 much faster. Usage example:
1111 uLong adler = adler32(0L, Z_NULL, 0);
1113 while (read_buffer(buffer, length) != EOF) {
1114 adler = adler32(adler, buffer, length);
1116 if (adler != original_adler) error();
1119 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1121 Update a running crc with the bytes buf[0..len-1] and return the updated
1122 crc. If buf is NULL, this function returns the required initial value
1123 for the crc. Pre- and post-conditioning (one's complement) is performed
1124 within this function so it shouldn't be done by the application.
1127 uLong crc = crc32(0L, Z_NULL, 0);
1129 while (read_buffer(buffer, length) != EOF) {
1130 crc = crc32(crc, buffer, length);
1132 if (crc != original_crc) error();
1136 /* various hacks, don't look :) */
1138 /* deflateInit and inflateInit are macros to allow checking the zlib version
1139 * and the compiler's view of z_stream:
1141 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1142 const char *version, int stream_size));
1143 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1144 const char *version, int stream_size));
1145 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1146 int windowBits, int memLevel,
1147 int strategy, const char *version,
1149 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1150 const char *version, int stream_size));
1151 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_stream FAR *strm, int windowBits,
1152 unsigned char FAR *window,
1153 const char *version,
1155 #define deflateInit(strm, level) \
1156 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1157 #define inflateInit(strm) \
1158 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1159 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1160 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1161 (strategy), ZLIB_VERSION, sizeof(z_stream))
1162 #define inflateInit2(strm, windowBits) \
1163 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1164 #define inflateBackInit(strm, windowBits, window) \
1165 inflateBackInit_((strm), (windowBits), (window), \
1166 ZLIB_VERSION, sizeof(z_stream))
1169 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1170 struct internal_state {int dummy;}; /* hack for buggy compilers */
1173 ZEXTERN const char * ZEXPORT zError OF((int err));
1174 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1175 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
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