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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.1, November 17th, 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).
29 */
31 #ifndef ZLIB_H
32 #define ZLIB_H
36 #ifdef __cplusplus
38 #endif
41 #define ZLIB_VERNUM 0x1210
43 /*
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
48 stream interface.
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.
77 */
107 /*
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
117 opaque value.
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
121 thread safe.
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
136 a single step).
137 */
139 /* constants */
141 #define Z_NO_FLUSH 0
143 #define Z_SYNC_FLUSH 2
144 #define Z_FULL_FLUSH 3
145 #define Z_FINISH 4
146 #define Z_BLOCK 5
147 /* Allowed flush values; see deflate() and inflate() below for details */
149 #define Z_OK 0
150 #define Z_STREAM_END 1
151 #define Z_NEED_DICT 2
152 #define Z_ERRNO (-1)
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.
160 */
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 */
168 #define Z_FILTERED 1
169 #define Z_HUFFMAN_ONLY 2
170 #define Z_RLE 3
171 #define Z_DEFAULT_STRATEGY 0
172 /* compression strategy; see deflateInit2() below for details */
174 #define Z_BINARY 0
175 #define Z_ASCII 1
176 #define Z_UNKNOWN 2
177 /* Possible values of the data_type field (though see inflate()) */
179 #define Z_DEFLATED 8
180 /* The deflate compression method (the only one supported in this version) */
184 #define zlib_version zlibVersion()
185 /* for compatibility with versions < 1.0.2 */
187 /* basic functions */
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.
194 */
196 /*
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().
216 */
220 /*
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
224 forced to flush.
226 The detailed semantics are as follows. deflate performs one or both of the
227 following actions:
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
260 the compression.
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.
298 */
302 /*
303 All dynamically allocated data structures for this stream are freed.
304 This function discards any unprocessed input and does not flush any
305 pending output.
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
311 deallocated).
312 */
315 /*
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.)
333 */
337 /*
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
341 forced to flush.
343 The detailed semantics are as follows. inflate performs one or both of the
344 following actions:
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 64
377 if inflate() is currently decoding the last block in the deflate stream,
378 plus 128 if inflate() returned immediately after decoding an end-of-block
379 code or decoding the complete header up to 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. The
382 number of unused bits may in general be greater than seven, except when
383 bit 7 of data_type is set, in which case the number of unused bits will be
384 less than eight.
386 inflate() should normally be called until it returns Z_STREAM_END or an
387 error. However if all decompression is to be performed in a single step
388 (a single call of inflate), the parameter flush should be set to
389 Z_FINISH. In this case all pending input is processed and all pending
390 output is flushed; avail_out must be large enough to hold all the
391 uncompressed data. (The size of the uncompressed data may have been saved
392 by the compressor for this purpose.) The next operation on this stream must
393 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
394 is never required, but can be used to inform inflate that a faster approach
395 may be used for the single inflate() call.
397 In this implementation, inflate() always flushes as much output as
398 possible to the output buffer, and always uses the faster approach on the
399 first call. So the only effect of the flush parameter in this implementation
400 is on the return value of inflate(), as noted below, or when it returns early
401 because Z_BLOCK is used.
403 If a preset dictionary is needed after this call (see inflateSetDictionary
404 below), inflate sets strm-adler to the adler32 checksum of the dictionary
405 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
406 strm->adler to the adler32 checksum of all output produced so far (that is,
407 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
408 below. At the end of the stream, inflate() checks that its computed adler32
409 checksum is equal to that saved by the compressor and returns Z_STREAM_END
410 only if the checksum is correct.
412 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
413 deflate data. The header type is detected automatically. Any information
414 contained in the gzip header is not retained, so applications that need that
415 information should instead use raw inflate, see inflateInit2() below, or
416 inflateBack() and perform their own processing of the gzip header and
417 trailer.
419 inflate() returns Z_OK if some progress has been made (more input processed
420 or more output produced), Z_STREAM_END if the end of the compressed data has
421 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
422 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
423 corrupted (input stream not conforming to the zlib format or incorrect check
424 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
425 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
426 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
427 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
428 inflate() can be called again with more input and more output space to
429 continue decompressing. If Z_DATA_ERROR is returned, the application may then
430 call inflateSync() to look for a good compression block if a partial recovery
431 of the data is desired.
432 */
436 /*
437 All dynamically allocated data structures for this stream are freed.
438 This function discards any unprocessed input and does not flush any
439 pending output.
441 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
442 was inconsistent. In the error case, msg may be set but then points to a
443 static string (which must not be deallocated).
444 */
446 /* Advanced functions */
448 /*
449 The following functions are needed only in some special applications.
450 */
452 /*
453 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
454 int level,
455 int method,
456 int windowBits,
457 int memLevel,
458 int strategy));
460 This is another version of deflateInit with more compression options. The
461 fields next_in, zalloc, zfree and opaque must be initialized before by
462 the caller.
464 The method parameter is the compression method. It must be Z_DEFLATED in
465 this version of the library.
467 The windowBits parameter is the base two logarithm of the window size
468 (the size of the history buffer). It should be in the range 8..15 for this
469 version of the library. Larger values of this parameter result in better
470 compression at the expense of memory usage. The default value is 15 if
471 deflateInit is used instead.
473 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
474 determines the window size. deflate() will then generate raw deflate data
475 with no zlib header or trailer, and will not compute an adler32 check value.
477 windowBits can also be greater than 15 for optional gzip encoding. Add
478 16 to windowBits to write a simple gzip header and trailer around the
479 compressed data instead of a zlib wrapper. The gzip header will have no
480 file name, no extra data, no comment, no modification time (set to zero),
481 no header crc, and the operating system will be set to 255 (unknown).
483 The memLevel parameter specifies how much memory should be allocated
484 for the internal compression state. memLevel=1 uses minimum memory but
485 is slow and reduces compression ratio; memLevel=9 uses maximum memory
486 for optimal speed. The default value is 8. See zconf.h for total memory
487 usage as a function of windowBits and memLevel.
489 The strategy parameter is used to tune the compression algorithm. Use the
490 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
491 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
492 string match), or Z_RLE to limit match distances to one (run-length
493 encoding). Filtered data consists mostly of small values with a somewhat
494 random distribution. In this case, the compression algorithm is tuned to
495 compress them better. The effect of Z_FILTERED is to force more Huffman
496 coding and less string matching; it is somewhat intermediate between
497 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
498 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
499 parameter only affects the compression ratio but not the correctness of the
500 compressed output even if it is not set appropriately.
502 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
503 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
504 method). msg is set to null if there is no error message. deflateInit2 does
505 not perform any compression: this will be done by deflate().
506 */
510 uInt dictLength));
511 /*
512 Initializes the compression dictionary from the given byte sequence
513 without producing any compressed output. This function must be called
514 immediately after deflateInit, deflateInit2 or deflateReset, before any
515 call of deflate. The compressor and decompressor must use exactly the same
516 dictionary (see inflateSetDictionary).
518 The dictionary should consist of strings (byte sequences) that are likely
519 to be encountered later in the data to be compressed, with the most commonly
520 used strings preferably put towards the end of the dictionary. Using a
521 dictionary is most useful when the data to be compressed is short and can be
522 predicted with good accuracy; the data can then be compressed better than
523 with the default empty dictionary.
525 Depending on the size of the compression data structures selected by
526 deflateInit or deflateInit2, a part of the dictionary may in effect be
527 discarded, for example if the dictionary is larger than the window size in
528 deflate or deflate2. Thus the strings most likely to be useful should be
529 put at the end of the dictionary, not at the front.
531 Upon return of this function, strm->adler is set to the adler32 value
532 of the dictionary; the decompressor may later use this value to determine
533 which dictionary has been used by the compressor. (The adler32 value
534 applies to the whole dictionary even if only a subset of the dictionary is
535 actually used by the compressor.) If a raw deflate was requested, then the
536 adler32 value is not computed and strm->adler is not set.
538 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
539 parameter is invalid (such as NULL dictionary) or the stream state is
540 inconsistent (for example if deflate has already been called for this stream
541 or if the compression method is bsort). deflateSetDictionary does not
542 perform any compression: this will be done by deflate().
543 */
546 z_streamp source));
547 /*
548 Sets the destination stream as a complete copy of the source stream.
550 This function can be useful when several compression strategies will be
551 tried, for example when there are several ways of pre-processing the input
552 data with a filter. The streams that will be discarded should then be freed
553 by calling deflateEnd. Note that deflateCopy duplicates the internal
554 compression state which can be quite large, so this strategy is slow and
555 can consume lots of memory.
557 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
558 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
559 (such as zalloc being NULL). msg is left unchanged in both source and
560 destination.
561 */
564 /*
565 This function is equivalent to deflateEnd followed by deflateInit,
566 but does not free and reallocate all the internal compression state.
567 The stream will keep the same compression level and any other attributes
568 that may have been set by deflateInit2.
570 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
571 stream state was inconsistent (such as zalloc or state being NULL).
572 */
577 /*
578 Dynamically update the compression level and compression strategy. The
579 interpretation of level and strategy is as in deflateInit2. This can be
580 used to switch between compression and straight copy of the input data, or
581 to switch to a different kind of input data requiring a different
582 strategy. If the compression level is changed, the input available so far
583 is compressed with the old level (and may be flushed); the new level will
584 take effect only at the next call of deflate().
586 Before the call of deflateParams, the stream state must be set as for
587 a call of deflate(), since the currently available input may have to
588 be compressed and flushed. In particular, strm->avail_out must be non-zero.
590 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
591 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
592 if strm->avail_out was zero.
593 */
596 uLong sourceLen));
597 /*
598 deflateBound() returns an upper bound on the compressed size after
599 deflation of sourceLen bytes. It must be called after deflateInit()
600 or deflateInit2(). This would be used to allocate an output buffer
601 for deflation in a single pass, and so would be called before deflate().
602 */
607 /*
608 deflatePrime() inserts bits in the deflate output stream. The intent
609 is that this function is used to start off the deflate output with the
610 bits leftover from a previous deflate stream when appending to it. As such,
611 this function can only be used for raw deflate, and must be used before the
612 first deflate() call after a deflateInit2() or deflateReset(). bits must be
613 less than or equal to 16, and that many of the least significant bits of
614 value will be inserted in the output.
616 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
617 stream state was inconsistent.
618 */
620 /*
621 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
622 int windowBits));
624 This is another version of inflateInit with an extra parameter. The
625 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
626 before by the caller.
628 The windowBits parameter is the base two logarithm of the maximum window
629 size (the size of the history buffer). It should be in the range 8..15 for
630 this version of the library. The default value is 15 if inflateInit is used
631 instead. windowBits must be greater than or equal to the windowBits value
632 provided to deflateInit2() while compressing, or it must be equal to 15 if
633 deflateInit2() was not used. If a compressed stream with a larger window
634 size is given as input, inflate() will return with the error code
635 Z_DATA_ERROR instead of trying to allocate a larger window.
637 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
638 determines the window size. inflate() will then process raw deflate data,
639 not looking for a zlib or gzip header, not generating a check value, and not
640 looking for any check values for comparison at the end of the stream. This
641 is for use with other formats that use the deflate compressed data format
642 such as zip. Those formats provide their own check values. If a custom
643 format is developed using the raw deflate format for compressed data, it is
644 recommended that a check value such as an adler32 or a crc32 be applied to
645 the uncompressed data as is done in the zlib, gzip, and zip formats. For
646 most applications, the zlib format should be used as is. Note that comments
647 above on the use in deflateInit2() applies to the magnitude of windowBits.
649 windowBits can also be greater than 15 for optional gzip decoding. Add
650 32 to windowBits to enable zlib and gzip decoding with automatic header
651 detection, or add 16 to decode only the gzip format (the zlib format will
652 return a Z_DATA_ERROR).
654 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
655 memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
656 memLevel). msg is set to null if there is no error message. inflateInit2
657 does not perform any decompression apart from reading the zlib header if
658 present: this will be done by inflate(). (So next_in and avail_in may be
659 modified, but next_out and avail_out are unchanged.)
660 */
664 uInt dictLength));
665 /*
666 Initializes the decompression dictionary from the given uncompressed byte
667 sequence. This function must be called immediately after a call of inflate
668 if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
669 can be determined from the adler32 value returned by this call of
670 inflate. The compressor and decompressor must use exactly the same
671 dictionary (see deflateSetDictionary).
673 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
674 parameter is invalid (such as NULL dictionary) or the stream state is
675 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
676 expected one (incorrect adler32 value). inflateSetDictionary does not
677 perform any decompression: this will be done by subsequent calls of
678 inflate().
679 */
682 /*
683 Skips invalid compressed data until a full flush point (see above the
684 description of deflate with Z_FULL_FLUSH) can be found, or until all
685 available input is skipped. No output is provided.
687 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
688 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
689 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
690 case, the application may save the current current value of total_in which
691 indicates where valid compressed data was found. In the error case, the
692 application may repeatedly call inflateSync, providing more input each time,
693 until success or end of the input data.
694 */
697 z_streamp source));
698 /*
699 Sets the destination stream as a complete copy of the source stream.
701 This function can be useful when randomly accessing a large stream. The
702 first pass through the stream can periodically record the inflate state,
703 allowing restarting inflate at those points when randomly accessing the
704 stream.
706 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
707 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
708 (such as zalloc being NULL). msg is left unchanged in both source and
709 destination.
710 */
713 /*
714 This function is equivalent to inflateEnd followed by inflateInit,
715 but does not free and reallocate all the internal decompression state.
716 The stream will keep attributes that may have been set by inflateInit2.
718 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
719 stream state was inconsistent (such as zalloc or state being NULL).
720 */
722 /*
723 ZEXTERN int ZEXPORT inflateBackInit OF((z_stream FAR *strm, int windowBits,
724 unsigned char FAR *window));
726 Initialize the internal stream state for decompression using inflateBack()
727 calls. The fields zalloc, zfree and opaque in strm must be initialized
728 before the call. If zalloc and zfree are Z_NULL, then the default library-
729 derived memory allocation routines are used. windowBits is the base two
730 logarithm of the window size, in the range 8..15. window is a caller
731 supplied buffer of that size. Except for special applications where it is
732 assured that deflate was used with small window sizes, windowBits must be 15
733 and a 32K byte window must be supplied to be able to decompress general
734 deflate streams.
736 See inflateBack() for the usage of these routines.
738 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
739 the paramaters are invalid, Z_MEM_ERROR if the internal state could not
740 be allocated, or Z_VERSION_ERROR if the version of the library does not
741 match the version of the header file.
742 */
750 /*
751 inflateBack() does a raw inflate with a single call using a call-back
752 interface for input and output. This is more efficient than inflate() for
753 file i/o applications in that it avoids copying between the output and the
754 sliding window by simply making the window itself the output buffer. This
755 function trusts the application to not change the output buffer passed by
756 the output function, at least until inflateBack() returns.
758 inflateBackInit() must be called first to allocate the internal state
759 and to initialize the state with the user-provided window buffer.
760 inflateBack() may then be used multiple times to inflate a complete, raw
761 deflate stream with each call. inflateBackEnd() is then called to free
762 the allocated state.
764 A raw deflate stream is one with no zlib or gzip header or trailer.
765 This routine would normally be used in a utility that reads zip or gzip
766 files and writes out uncompressed files. The utility would decode the
767 header and process the trailer on its own, hence this routine expects
768 only the raw deflate stream to decompress. This is different from the
769 normal behavior of inflate(), which expects either a zlib or gzip header and
770 trailer around the deflate stream.
772 inflateBack() uses two subroutines supplied by the caller that are then
773 called by inflateBack() for input and output. inflateBack() calls those
774 routines until it reads a complete deflate stream and writes out all of the
775 uncompressed data, or until it encounters an error. The function's
776 parameters and return types are defined above in the in_func and out_func
777 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
778 number of bytes of provided input, and a pointer to that input in buf. If
779 there is no input available, in() must return zero--buf is ignored in that
780 case--and inflateBack() will return a buffer error. inflateBack() will call
781 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
782 should return zero on success, or non-zero on failure. If out() returns
783 non-zero, inflateBack() will return with an error. Neither in() nor out()
784 are permitted to change the contents of the window provided to
785 inflateBackInit(), which is also the buffer that out() uses to write from.
786 The length written by out() will be at most the window size. Any non-zero
787 amount of input may be provided by in().
789 For convenience, inflateBack() can be provided input on the first call by
790 setting strm->next_in and strm->avail_in. If that input is exhausted, then
791 in() will be called. Therefore strm->next_in must be initialized before
792 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
793 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
794 must also be initialized, and then if strm->avail_in is not zero, input will
795 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
797 The in_desc and out_desc parameters of inflateBack() is passed as the
798 first parameter of in() and out() respectively when they are called. These
799 descriptors can be optionally used to pass any information that the caller-
800 supplied in() and out() functions need to do their job.
802 On return, inflateBack() will set strm->next_in and strm->avail_in to
803 pass back any unused input that was provided by the last in() call. The
804 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
805 if in() or out() returned an error, Z_DATA_ERROR if there was a format
806 error in the deflate stream (in which case strm->msg is set to indicate the
807 nature of the error), or Z_STREAM_ERROR if the stream was not properly
808 initialized. In the case of Z_BUF_ERROR, an input or output error can be
809 distinguished using strm->next_in which will be Z_NULL only if in() returned
810 an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
811 out() returning non-zero. (in() will always be called before out(), so
812 strm->next_in is assured to be defined if out() returns non-zero.) Note
813 that inflateBack() cannot return Z_OK.
814 */
817 /*
818 All memory allocated by inflateBackInit() is freed.
820 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
821 state was inconsistent.
822 */
825 /* Return flags indicating compile-time options.
827 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
828 1.0: size of uInt
829 3.2: size of uLong
830 5.4: size of voidpf (pointer)
831 7.6: size of z_off_t
833 Compiler, assembler, and debug options:
834 8: DEBUG
835 9: ASMV or ASMINF -- use ASM code
836 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
837 11: 0 (reserved)
839 One-time table building (smaller code, but not thread-safe if true):
840 12: BUILDFIXED -- build static block decoding tables when needed
841 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
842 14,15: 0 (reserved)
844 Library content (indicates missing functionality):
845 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
846 deflate code when not needed)
847 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
848 and decode gzip streams (to avoid linking crc code)
849 18-19: 0 (reserved)
851 Operation variations (changes in library functionality):
852 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
853 21: FASTEST -- deflate algorithm with only one, lowest compression level
854 22,23: 0 (reserved)
856 The sprintf variant used by gzprintf (zero is best):
857 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
858 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
859 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
861 Remainder:
862 27-31: 0 (reserved)
863 */
866 /* utility functions */
868 /*
869 The following utility functions are implemented on top of the
870 basic stream-oriented functions. To simplify the interface, some
871 default options are assumed (compression level and memory usage,
872 standard memory allocation functions). The source code of these
873 utility functions can easily be modified if you need special options.
874 */
878 /*
879 Compresses the source buffer into the destination buffer. sourceLen is
880 the byte length of the source buffer. Upon entry, destLen is the total
881 size of the destination buffer, which must be at least the value returned
882 by compressBound(sourceLen). Upon exit, destLen is the actual size of the
883 compressed buffer.
884 This function can be used to compress a whole file at once if the
885 input file is mmap'ed.
886 compress returns Z_OK if success, Z_MEM_ERROR if there was not
887 enough memory, Z_BUF_ERROR if there was not enough room in the output
888 buffer.
889 */
894 /*
895 Compresses the source buffer into the destination buffer. The level
896 parameter has the same meaning as in deflateInit. sourceLen is the byte
897 length of the source buffer. Upon entry, destLen is the total size of the
898 destination buffer, which must be at least the value returned by
899 compressBound(sourceLen). Upon exit, destLen is the actual size of the
900 compressed buffer.
902 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
903 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
904 Z_STREAM_ERROR if the level parameter is invalid.
905 */
908 /*
909 compressBound() returns an upper bound on the compressed size after
910 compress() or compress2() on sourceLen bytes. It would be used before
911 a compress() or compress2() call to allocate the destination buffer.
912 */
916 /*
917 Decompresses the source buffer into the destination buffer. sourceLen is
918 the byte length of the source buffer. Upon entry, destLen is the total
919 size of the destination buffer, which must be large enough to hold the
920 entire uncompressed data. (The size of the uncompressed data must have
921 been saved previously by the compressor and transmitted to the decompressor
922 by some mechanism outside the scope of this compression library.)
923 Upon exit, destLen is the actual size of the compressed buffer.
924 This function can be used to decompress a whole file at once if the
925 input file is mmap'ed.
927 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
928 enough memory, Z_BUF_ERROR if there was not enough room in the output
929 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
930 */
936 /*
937 Opens a gzip (.gz) file for reading or writing. The mode parameter
938 is as in fopen ("rb" or "wb") but can also include a compression level
939 ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
940 Huffman only compression as in "wb1h", or 'R' for run-length encoding
941 as in "wb1R". (See the description of deflateInit2 for more information
942 about the strategy parameter.)
944 gzopen can be used to read a file which is not in gzip format; in this
945 case gzread will directly read from the file without decompression.
947 gzopen returns NULL if the file could not be opened or if there was
948 insufficient memory to allocate the (de)compression state; errno
949 can be checked to distinguish the two cases (if errno is zero, the
950 zlib error is Z_MEM_ERROR). */
953 /*
954 gzdopen() associates a gzFile with the file descriptor fd. File
955 descriptors are obtained from calls like open, dup, creat, pipe or
956 fileno (in the file has been previously opened with fopen).
957 The mode parameter is as in gzopen.
958 The next call of gzclose on the returned gzFile will also close the
959 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
960 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
961 gzdopen returns NULL if there was insufficient memory to allocate
962 the (de)compression state.
963 */
966 /*
967 Dynamically update the compression level or strategy. See the description
968 of deflateInit2 for the meaning of these parameters.
969 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
970 opened for writing.
971 */
974 /*
975 Reads the given number of uncompressed bytes from the compressed file.
976 If the input file was not in gzip format, gzread copies the given number
977 of bytes into the buffer.
978 gzread returns the number of uncompressed bytes actually read (0 for
979 end of file, -1 for error). */
983 /*
984 Writes the given number of uncompressed bytes into the compressed file.
985 gzwrite returns the number of uncompressed bytes actually written
986 (0 in case of error).
987 */
990 /*
991 Converts, formats, and writes the args to the compressed file under
992 control of the format string, as in fprintf. gzprintf returns the number of
993 uncompressed bytes actually written (0 in case of error). The number of
994 uncompressed bytes written is limited to 4095. The caller should assure that
995 this limit is not exceeded. If it is exceeded, then gzprintf() will return
996 return an error (0) with nothing written. In this case, there may also be a
997 buffer overflow with unpredictable consequences, which is possible only if
998 zlib was compiled with the insecure functions sprintf() or vsprintf()
999 because the secure snprintf() or vsnprintf() functions were not available.
1000 */
1003 /*
1004 Writes the given null-terminated string to the compressed file, excluding
1005 the terminating null character.
1006 gzputs returns the number of characters written, or -1 in case of error.
1007 */
1010 /*
1011 Reads bytes from the compressed file until len-1 characters are read, or
1012 a newline character is read and transferred to buf, or an end-of-file
1013 condition is encountered. The string is then terminated with a null
1014 character.
1015 gzgets returns buf, or Z_NULL in case of error.
1016 */
1019 /*
1020 Writes c, converted to an unsigned char, into the compressed file.
1021 gzputc returns the value that was written, or -1 in case of error.
1022 */
1025 /*
1026 Reads one byte from the compressed file. gzgetc returns this byte
1027 or -1 in case of end of file or error.
1028 */
1031 /*
1032 Push one character back onto the stream to be read again later.
1033 Only one character of push-back is allowed. gzungetc() returns the
1034 character pushed, or -1 on failure. gzungetc() will fail if a
1035 character has been pushed but not read yet, or if c is -1. The pushed
1036 character will be discarded if the stream is repositioned with gzseek()
1037 or gzrewind().
1038 */
1041 /*
1042 Flushes all pending output into the compressed file. The parameter
1043 flush is as in the deflate() function. The return value is the zlib
1044 error number (see function gzerror below). gzflush returns Z_OK if
1045 the flush parameter is Z_FINISH and all output could be flushed.
1046 gzflush should be called only when strictly necessary because it can
1047 degrade compression.
1048 */
1052 /*
1053 Sets the starting position for the next gzread or gzwrite on the
1054 given compressed file. The offset represents a number of bytes in the
1055 uncompressed data stream. The whence parameter is defined as in lseek(2);
1056 the value SEEK_END is not supported.
1057 If the file is opened for reading, this function is emulated but can be
1058 extremely slow. If the file is opened for writing, only forward seeks are
1059 supported; gzseek then compresses a sequence of zeroes up to the new
1060 starting position.
1062 gzseek returns the resulting offset location as measured in bytes from
1063 the beginning of the uncompressed stream, or -1 in case of error, in
1064 particular if the file is opened for writing and the new starting position
1065 would be before the current position.
1066 */
1069 /*
1070 Rewinds the given file. This function is supported only for reading.
1072 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1073 */
1076 /*
1077 Returns the starting position for the next gzread or gzwrite on the
1078 given compressed file. This position represents a number of bytes in the
1079 uncompressed data stream.
1081 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1082 */
1085 /*
1086 Returns 1 when EOF has previously been detected reading the given
1087 input stream, otherwise zero.
1088 */
1091 /*
1092 Flushes all pending output if necessary, closes the compressed file
1093 and deallocates all the (de)compression state. The return value is the zlib
1094 error number (see function gzerror below).
1095 */
1098 /*
1099 Returns the error message for the last error which occurred on the
1100 given compressed file. errnum is set to zlib error number. If an
1101 error occurred in the file system and not in the compression library,
1102 errnum is set to Z_ERRNO and the application may consult errno
1103 to get the exact error code.
1104 */
1107 /*
1108 Clears the error and end-of-file flags for file. This is analogous to the
1109 clearerr() function in stdio. This is useful for continuing to read a gzip
1110 file that is being written concurrently.
1111 */
1113 /* checksum functions */
1115 /*
1116 These functions are not related to compression but are exported
1117 anyway because they might be useful in applications using the
1118 compression library.
1119 */
1123 /*
1124 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1125 return the updated checksum. If buf is NULL, this function returns
1126 the required initial value for the checksum.
1127 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1128 much faster. Usage example:
1130 uLong adler = adler32(0L, Z_NULL, 0);
1132 while (read_buffer(buffer, length) != EOF) {
1133 adler = adler32(adler, buffer, length);
1134 }
1135 if (adler != original_adler) error();
1136 */
1139 /*
1140 Update a running crc with the bytes buf[0..len-1] and return the updated
1141 crc. If buf is NULL, this function returns the required initial value
1142 for the crc. Pre- and post-conditioning (one's complement) is performed
1143 within this function so it shouldn't be done by the application.
1144 Usage example:
1146 uLong crc = crc32(0L, Z_NULL, 0);
1148 while (read_buffer(buffer, length) != EOF) {
1149 crc = crc32(crc, buffer, length);
1150 }
1151 if (crc != original_crc) error();
1152 */
1155 /* various hacks, don't look :) */
1157 /* deflateInit and inflateInit are macros to allow checking the zlib version
1158 * and the compiler's view of z_stream:
1159 */
1174 #define deflateInit(strm, level) \
1175 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1176 #define inflateInit(strm) \
1177 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1178 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1179 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1180 (strategy), ZLIB_VERSION, sizeof(z_stream))
1181 #define inflateInit2(strm, windowBits) \
1182 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1183 #define inflateBackInit(strm, windowBits, window) \
1184 inflateBackInit_((strm), (windowBits), (window), \
1185 ZLIB_VERSION, sizeof(z_stream))
1188 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1190 #endif
1196 #ifdef __cplusplus
1197 }
1198 #endif