4 * This file is derived from zlib.h and zconf.h from the zlib-1.0.4
5 * distribution by Jean-loup Gailly and Mark Adler, with some additions
6 * by Paul Mackerras to aid in implementing Deflate compression and
7 * decompression for PPP packets.
11 * ==FILEVERSION 971127==
13 * This marker is used by the Linux installation script to determine
14 * whether an up-to-date version of this file is already installed.
20 SPDX-License-Identifier: BSD-3-Clause
22 zlib.h -- interface of the 'zlib' general purpose compression library
23 version 1.0.4, Jul 24th, 1996.
25 Copyright (C) 1995-1996 Jean-loup Gailly and Mark Adler
27 This software is provided 'as-is', without any express or implied
28 warranty. In no event will the authors be held liable for any damages
29 arising from the use of this software.
31 Permission is granted to anyone to use this software for any purpose,
32 including commercial applications, and to alter it and redistribute it
33 freely, subject to the following restrictions:
35 1. The origin of this software must not be misrepresented; you must not
36 claim that you wrote the original software. If you use this software
37 in a product, an acknowledgment in the product documentation would be
38 appreciated but is not required.
39 2. Altered source versions must be plainly marked as such, and must not be
40 misrepresented as being the original software.
41 3. This notice may not be removed or altered from any source distribution.
43 Jean-loup Gailly Mark Adler
44 gzip@prep.ai.mit.edu madler@alumni.caltech.edu
47 The data format used by the zlib library is described by RFCs (Request for
48 Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
49 (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
61 /* zconf.h -- configuration of the zlib compression library
62 * Copyright (C) 1995-1996 Jean-loup Gailly.
63 * For conditions of distribution and use, see copyright notice in zlib.h
66 /* From: zconf.h,v 1.20 1996/07/02 15:09:28 me Exp $ */
72 * If you *really* need a unique prefix for all types and library functions,
73 * compile with -DZ_PREFIX. The "standard" zlib should be compiled without it.
76 # define deflateInit_ z_deflateInit_
77 # define deflate z_deflate
78 # define deflateEnd z_deflateEnd
79 # define inflateInit_ z_inflateInit_
80 # define inflate z_inflate
81 # define inflateEnd z_inflateEnd
82 # define deflateInit2_ z_deflateInit2_
83 # define deflateSetDictionary z_deflateSetDictionary
84 # define deflateCopy z_deflateCopy
85 # define deflateReset z_deflateReset
86 # define deflateParams z_deflateParams
87 # define inflateInit2_ z_inflateInit2_
88 # define inflateSetDictionary z_inflateSetDictionary
89 # define inflateSync z_inflateSync
90 # define inflateReset z_inflateReset
91 # define compress z_compress
92 # define uncompress z_uncompress
93 # define adler32 z_adler32
95 # define crc32 z_crc32
96 # define get_crc_table z_get_crc_table
101 # define uLong z_uLong
102 # define Bytef z_Bytef
103 # define charf z_charf
105 # define uIntf z_uIntf
106 # define uLongf z_uLongf
107 # define voidpf z_voidpf
108 # define voidp z_voidp
111 #if (defined(_WIN32) || defined(__WIN32__)) && !defined(WIN32)
114 #if defined(__GNUC__) || defined(WIN32) || defined(__386__) || defined(__i386__)
119 #if defined(__MSDOS__) && !defined(MSDOS)
124 * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
125 * than 64k bytes at a time (needed on systems with 16-bit int).
127 #if defined(MSDOS) && !defined(__32BIT__)
131 # define UNALIGNED_OK
134 #if (defined(MSDOS) || defined(_WINDOWS) || defined(WIN32)) && !defined(STDC)
137 #if (defined(__STDC__) || defined(__cplusplus)) && !defined(STDC)
142 # ifndef const /* cannot use !defined(STDC) && !defined(const) on Mac */
147 /* Some Mac compilers merge all .h files incorrectly: */
148 #if defined(__MWERKS__) || defined(applec) ||defined(THINK_C) ||defined(__SC__)
149 # define NO_DUMMY_DECL
152 /* Maximum value for memLevel in deflateInit2 */
153 #ifndef MAX_MEM_LEVEL
155 # define MAX_MEM_LEVEL 8
157 # define MAX_MEM_LEVEL 9
161 /* Maximum value for windowBits in deflateInit2 and inflateInit2 */
163 # define MAX_WBITS 15 /* 32K LZ77 window */
166 /* The memory requirements for deflate are (in bytes):
167 1 << (windowBits+2) + 1 << (memLevel+9)
168 that is: 128K for windowBits=15 + 128K for memLevel = 8 (default values)
169 plus a few kilobytes for small objects. For example, if you want to reduce
170 the default memory requirements from 256K to 128K, compile with
171 make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
172 Of course this will generally degrade compression (there's no free lunch).
174 The memory requirements for inflate are (in bytes) 1 << windowBits
175 that is, 32K for windowBits=15 (default value) plus a few kilobytes
179 /* Type declarations */
181 #ifndef OF /* function prototypes */
183 # define OF(args) args
189 /* The following definitions for FAR are needed only for MSDOS mixed
190 * model programming (small or medium model with some far allocations).
191 * This was tested only with MSC; for other MSDOS compilers you may have
192 * to define NO_MEMCPY in zutil.h. If you don't need the mixed model,
193 * just define FAR to be empty.
195 #if (defined(M_I86SM) || defined(M_I86MM)) && !defined(__32BIT__)
196 /* MSC small or medium model */
197 # define SMALL_MEDIUM
204 #if defined(__BORLANDC__) && (defined(__SMALL__) || defined(__MEDIUM__))
206 # define SMALL_MEDIUM
214 typedef unsigned char Byte; /* 8 bits */
215 typedef unsigned int uInt; /* 16 bits or more */
216 typedef unsigned long uLong; /* 32 bits or more */
218 #if defined(__BORLANDC__) && defined(SMALL_MEDIUM)
219 /* Borland C/C++ ignores FAR inside typedef */
220 # define Bytef Byte FAR
222 typedef Byte FAR Bytef;
224 typedef char FAR charf;
225 typedef int FAR intf;
226 typedef uInt FAR uIntf;
227 typedef uLong FAR uLongf;
230 typedef void FAR *voidpf;
233 typedef Byte FAR *voidpf;
238 /* Compile with -DZLIB_DLL for Windows DLL support */
239 #if (defined(_WINDOWS) || defined(WINDOWS)) && defined(ZLIB_DLL)
240 # include <windows.h>
241 # define EXPORT WINAPI
246 #endif /* _ZCONF_H */
249 #define ZLIB_VERSION "1.0.4P"
252 The 'zlib' compression library provides in-memory compression and
253 decompression functions, including integrity checks of the uncompressed
254 data. This version of the library supports only one compression method
255 (deflation) but other algorithms may be added later and will have the same
258 For compression the application must provide the output buffer and
259 may optionally provide the input buffer for optimization. For decompression,
260 the application must provide the input buffer and may optionally provide
261 the output buffer for optimization.
263 Compression can be done in a single step if the buffers are large
264 enough (for example if an input file is mmap'ed), or can be done by
265 repeated calls of the compression function. In the latter case, the
266 application must provide more input and/or consume the output
267 (providing more output space) before each call.
269 The library does not install any signal handler. It is recommended to
270 add at least a handler for SIGSEGV when decompressing; the library checks
271 the consistency of the input data whenever possible but may go nuts
272 for some forms of corrupted input.
275 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
276 typedef void (*free_func) OF((voidpf opaque, voidpf address));
278 struct internal_state;
280 typedef struct z_stream_s {
281 Bytef *next_in; /* next input byte */
282 uInt avail_in; /* number of bytes available at next_in */
283 uLong total_in; /* total nb of input bytes read so far */
285 Bytef *next_out; /* next output byte should be put there */
286 uInt avail_out; /* remaining free space at next_out */
287 uLong total_out; /* total nb of bytes output so far */
289 const char *msg; /* last error message, NULL if no error */
290 struct internal_state FAR *state; /* not visible by applications */
292 alloc_func zalloc; /* used to allocate the internal state */
293 free_func zfree; /* used to free the internal state */
294 voidpf opaque; /* private data object passed to zalloc and zfree */
296 int data_type; /* best guess about the data type: ascii or binary */
297 uLong adler; /* adler32 value of the uncompressed data */
298 uLong reserved; /* reserved for future use */
301 typedef z_stream FAR *z_streamp;
304 The application must update next_in and avail_in when avail_in has
305 dropped to zero. It must update next_out and avail_out when avail_out
306 has dropped to zero. The application must initialize zalloc, zfree and
307 opaque before calling the init function. All other fields are set by the
308 compression library and must not be updated by the application.
310 The opaque value provided by the application will be passed as the first
311 parameter for calls of zalloc and zfree. This can be useful for custom
312 memory management. The compression library attaches no meaning to the
315 zalloc must return Z_NULL if there is not enough memory for the object.
316 On 16-bit systems, the functions zalloc and zfree must be able to allocate
317 exactly 65536 bytes, but will not be required to allocate more than this
318 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
319 pointers returned by zalloc for objects of exactly 65536 bytes *must*
320 have their offset normalized to zero. The default allocation function
321 provided by this library ensures this (see zutil.c). To reduce memory
322 requirements and avoid any allocation of 64K objects, at the expense of
323 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
325 The fields total_in and total_out can be used for statistics or
326 progress reports. After compression, total_in holds the total size of
327 the uncompressed data and may be saved for use in the decompressor
328 (particularly if the decompressor wants to decompress everything in
335 #define Z_PARTIAL_FLUSH 1
336 #define Z_PACKET_FLUSH 2
337 #define Z_SYNC_FLUSH 3
338 #define Z_FULL_FLUSH 4
340 /* Allowed flush values; see deflate() below for details */
343 #define Z_STREAM_END 1
344 #define Z_NEED_DICT 2
346 #define Z_STREAM_ERROR (-2)
347 #define Z_DATA_ERROR (-3)
348 #define Z_MEM_ERROR (-4)
349 #define Z_BUF_ERROR (-5)
350 #define Z_VERSION_ERROR (-6)
351 /* Return codes for the compression/decompression functions. Negative
352 * values are errors, positive values are used for special but normal events.
355 #define Z_NO_COMPRESSION 0
356 #define Z_BEST_SPEED 1
357 #define Z_BEST_COMPRESSION 9
358 #define Z_DEFAULT_COMPRESSION (-1)
359 /* compression levels */
362 #define Z_HUFFMAN_ONLY 2
363 #define Z_DEFAULT_STRATEGY 0
364 /* compression strategy; see deflateInit2() below for details */
369 /* Possible values of the data_type field */
372 /* The deflate compression method (the only one supported in this version) */
374 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
376 #define zlib_version zlibVersion()
377 /* for compatibility with versions < 1.0.2 */
379 /* basic functions */
381 extern const char * EXPORT zlibVersion OF((void));
382 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
383 If the first character differs, the library code actually used is
384 not compatible with the zlib.h header file used by the application.
385 This check is automatically made by deflateInit and inflateInit.
389 extern int EXPORT deflateInit OF((z_streamp strm, int level));
391 Initializes the internal stream state for compression. The fields
392 zalloc, zfree and opaque must be initialized before by the caller.
393 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
394 use default allocation functions.
396 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
397 1 gives best speed, 9 gives best compression, 0 gives no compression at
398 all (the input data is simply copied a block at a time).
399 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
400 compression (currently equivalent to level 6).
402 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
403 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
404 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
405 with the version assumed by the caller (ZLIB_VERSION).
406 msg is set to null if there is no error message. deflateInit does not
407 perform any compression: this will be done by deflate().
411 extern int EXPORT deflate OF((z_streamp strm, int flush));
413 Performs one or both of the following actions:
415 - Compress more input starting at next_in and update next_in and avail_in
416 accordingly. If not all input can be processed (because there is not
417 enough room in the output buffer), next_in and avail_in are updated and
418 processing will resume at this point for the next call of deflate().
420 - Provide more output starting at next_out and update next_out and avail_out
421 accordingly. This action is forced if the parameter flush is non zero.
422 Forcing flush frequently degrades the compression ratio, so this parameter
423 should be set only when necessary (in interactive applications).
424 Some output may be provided even if flush is not set.
426 Before the call of deflate(), the application should ensure that at least
427 one of the actions is possible, by providing more input and/or consuming
428 more output, and updating avail_in or avail_out accordingly; avail_out
429 should never be zero before the call. The application can consume the
430 compressed output when it wants, for example when the output buffer is full
431 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
432 and with zero avail_out, it must be called again after making room in the
433 output buffer because there might be more output pending.
435 If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
436 block is terminated and flushed to the output buffer so that the
437 decompressor can get all input data available so far. For method 9, a future
438 variant on method 8, the current block will be flushed but not terminated.
439 Z_SYNC_FLUSH has the same effect as partial flush except that the compressed
440 output is byte aligned (the compressor can clear its internal bit buffer)
441 and the current block is always terminated; this can be useful if the
442 compressor has to be restarted from scratch after an interruption (in which
443 case the internal state of the compressor may be lost).
444 If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
445 special marker is output and the compression dictionary is discarded; this
446 is useful to allow the decompressor to synchronize if one compressed block
447 has been damaged (see inflateSync below). Flushing degrades compression and
448 so should be used only when necessary. Using Z_FULL_FLUSH too often can
449 seriously degrade the compression. If deflate returns with avail_out == 0,
450 this function must be called again with the same value of the flush
451 parameter and more output space (updated avail_out), until the flush is
452 complete (deflate returns with non-zero avail_out).
454 If the parameter flush is set to Z_PACKET_FLUSH, the compression
455 block is terminated, and a zero-length stored block is output,
456 omitting the length bytes (the effect of this is that the 3-bit type
457 code 000 for a stored block is output, and the output is then
458 byte-aligned). This is designed for use at the end of a PPP packet.
460 If the parameter flush is set to Z_FINISH, pending input is processed,
461 pending output is flushed and deflate returns with Z_STREAM_END if there
462 was enough output space; if deflate returns with Z_OK, this function must be
463 called again with Z_FINISH and more output space (updated avail_out) but no
464 more input data, until it returns with Z_STREAM_END or an error. After
465 deflate has returned Z_STREAM_END, the only possible operations on the
466 stream are deflateReset or deflateEnd.
468 Z_FINISH can be used immediately after deflateInit if all the compression
469 is to be done in a single step. In this case, avail_out must be at least
470 0.1% larger than avail_in plus 12 bytes. If deflate does not return
471 Z_STREAM_END, then it must be called again as described above.
473 deflate() may update data_type if it can make a good guess about
474 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
475 binary. This field is only for information purposes and does not affect
476 the compression algorithm in any manner.
478 deflate() returns Z_OK if some progress has been made (more input
479 processed or more output produced), Z_STREAM_END if all input has been
480 consumed and all output has been produced (only when flush is set to
481 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
482 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
486 extern int EXPORT deflateEnd OF((z_streamp strm));
488 All dynamically allocated data structures for this stream are freed.
489 This function discards any unprocessed input and does not flush any
492 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
493 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
494 prematurely (some input or output was discarded). In the error case,
495 msg may be set but then points to a static string (which must not be
501 extern int EXPORT inflateInit OF((z_streamp strm));
503 Initializes the internal stream state for decompression. The fields
504 zalloc, zfree and opaque must be initialized before by the caller. If
505 zalloc and zfree are set to Z_NULL, inflateInit updates them to use default
506 allocation functions.
508 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
509 enough memory, Z_VERSION_ERROR if the zlib library version is incompatible
510 with the version assumed by the caller. msg is set to null if there is no
511 error message. inflateInit does not perform any decompression: this will be
515 #if defined(__FreeBSD__) && defined(_KERNEL)
516 #define inflate _zlib104_inflate /* FreeBSD already has an inflate :-( */
519 extern int EXPORT inflate OF((z_streamp strm, int flush));
521 Performs one or both of the following actions:
523 - Decompress more input starting at next_in and update next_in and avail_in
524 accordingly. If not all input can be processed (because there is not
525 enough room in the output buffer), next_in is updated and processing
526 will resume at this point for the next call of inflate().
528 - Provide more output starting at next_out and update next_out and avail_out
529 accordingly. inflate() provides as much output as possible, until there
530 is no more input data or no more space in the output buffer (see below
531 about the flush parameter).
533 Before the call of inflate(), the application should ensure that at least
534 one of the actions is possible, by providing more input and/or consuming
535 more output, and updating the next_* and avail_* values accordingly.
536 The application can consume the uncompressed output when it wants, for
537 example when the output buffer is full (avail_out == 0), or after each
538 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
539 must be called again after making room in the output buffer because there
540 might be more output pending.
542 If the parameter flush is set to Z_PARTIAL_FLUSH or Z_PACKET_FLUSH,
543 inflate flushes as much output as possible to the output buffer. The
544 flushing behavior of inflate is not specified for values of the flush
545 parameter other than Z_PARTIAL_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
546 current implementation actually flushes as much output as possible
547 anyway. For Z_PACKET_FLUSH, inflate checks that once all the input data
548 has been consumed, it is expecting to see the length field of a stored
549 block; if not, it returns Z_DATA_ERROR.
551 inflate() should normally be called until it returns Z_STREAM_END or an
552 error. However if all decompression is to be performed in a single step
553 (a single call of inflate), the parameter flush should be set to
554 Z_FINISH. In this case all pending input is processed and all pending
555 output is flushed; avail_out must be large enough to hold all the
556 uncompressed data. (The size of the uncompressed data may have been saved
557 by the compressor for this purpose.) The next operation on this stream must
558 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
559 is never required, but can be used to inform inflate that a faster routine
560 may be used for the single inflate() call.
562 inflate() returns Z_OK if some progress has been made (more input
563 processed or more output produced), Z_STREAM_END if the end of the
564 compressed data has been reached and all uncompressed output has been
565 produced, Z_NEED_DICT if a preset dictionary is needed at this point (see
566 inflateSetDictionary below), Z_DATA_ERROR if the input data was corrupted,
567 Z_STREAM_ERROR if the stream structure was inconsistent (for example if
568 next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
569 Z_BUF_ERROR if no progress is possible or if there was not enough room in
570 the output buffer when Z_FINISH is used. In the Z_DATA_ERROR case, the
571 application may then call inflateSync to look for a good compression block.
572 In the Z_NEED_DICT case, strm->adler is set to the Adler32 value of the
573 dictionary chosen by the compressor.
577 extern int EXPORT inflateEnd OF((z_streamp strm));
579 All dynamically allocated data structures for this stream are freed.
580 This function discards any unprocessed input and does not flush any
583 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
584 was inconsistent. In the error case, msg may be set but then points to a
585 static string (which must not be deallocated).
588 /* Advanced functions */
591 The following functions are needed only in some special applications.
595 extern int EXPORT deflateInit2 OF((z_streamp strm,
602 This is another version of deflateInit with more compression options. The
603 fields next_in, zalloc, zfree and opaque must be initialized before by
606 The method parameter is the compression method. It must be Z_DEFLATED in
607 this version of the library. (Method 9 will allow a 64K history buffer and
608 partial block flushes.)
610 The windowBits parameter is the base two logarithm of the window size
611 (the size of the history buffer). It should be in the range 8..15 for this
612 version of the library (the value 16 will be allowed for method 9). Larger
613 values of this parameter result in better compression at the expense of
614 memory usage. The default value is 15 if deflateInit is used instead.
616 The memLevel parameter specifies how much memory should be allocated
617 for the internal compression state. memLevel=1 uses minimum memory but
618 is slow and reduces compression ratio; memLevel=9 uses maximum memory
619 for optimal speed. The default value is 8. See zconf.h for total memory
620 usage as a function of windowBits and memLevel.
622 The strategy parameter is used to tune the compression algorithm. Use the
623 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
624 filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
625 string match). Filtered data consists mostly of small values with a
626 somewhat random distribution. In this case, the compression algorithm is
627 tuned to compress them better. The effect of Z_FILTERED is to force more
628 Huffman coding and less string matching; it is somewhat intermediate
629 between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
630 the compression ratio but not the correctness of the compressed output even
631 if it is not set appropriately.
633 If next_in is not null, the library will use this buffer to hold also
634 some history information; the buffer must either hold the entire input
635 data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
636 is null, the library will allocate its own history buffer (and leave next_in
637 null). next_out need not be provided here but must be provided by the
638 application for the next call of deflate().
640 If the history buffer is provided by the application, next_in must
641 must never be changed by the application since the compressor maintains
642 information inside this buffer from call to call; the application
643 must provide more input only by increasing avail_in. next_in is always
644 reset by the library in this case.
646 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
647 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
648 an invalid method). msg is set to null if there is no error message.
649 deflateInit2 does not perform any compression: this will be done by
653 extern int EXPORT deflateSetDictionary OF((z_streamp strm,
654 const Bytef *dictionary,
657 Initializes the compression dictionary (history buffer) from the given
658 byte sequence without producing any compressed output. This function must
659 be called immediately after deflateInit or deflateInit2, before any call
660 of deflate. The compressor and decompressor must use exactly the same
661 dictionary (see inflateSetDictionary).
662 The dictionary should consist of strings (byte sequences) that are likely
663 to be encountered later in the data to be compressed, with the most commonly
664 used strings preferably put towards the end of the dictionary. Using a
665 dictionary is most useful when the data to be compressed is short and
666 can be predicted with good accuracy; the data can then be compressed better
667 than with the default empty dictionary. In this version of the library,
668 only the last 32K bytes of the dictionary are used.
669 Upon return of this function, strm->adler is set to the Adler32 value
670 of the dictionary; the decompressor may later use this value to determine
671 which dictionary has been used by the compressor. (The Adler32 value
672 applies to the whole dictionary even if only a subset of the dictionary is
673 actually used by the compressor.)
675 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
676 parameter is invalid (such as NULL dictionary) or the stream state
677 is inconsistent (for example if deflate has already been called for this
678 stream). deflateSetDictionary does not perform any compression: this will
679 be done by deflate().
682 extern int EXPORT deflateCopy OF((z_streamp dest,
685 Sets the destination stream as a complete copy of the source stream. If
686 the source stream is using an application-supplied history buffer, a new
687 buffer is allocated for the destination stream. The compressed output
688 buffer is always application-supplied. It's the responsibility of the
689 application to provide the correct values of next_out and avail_out for the
690 next call of deflate.
692 This function can be useful when several compression strategies will be
693 tried, for example when there are several ways of pre-processing the input
694 data with a filter. The streams that will be discarded should then be freed
695 by calling deflateEnd. Note that deflateCopy duplicates the internal
696 compression state which can be quite large, so this strategy is slow and
697 can consume lots of memory.
699 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
700 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
701 (such as zalloc being NULL). msg is left unchanged in both source and
705 extern int EXPORT deflateReset OF((z_streamp strm));
707 This function is equivalent to deflateEnd followed by deflateInit,
708 but does not free and reallocate all the internal compression state.
709 The stream will keep the same compression level and any other attributes
710 that may have been set by deflateInit2.
712 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
713 stream state was inconsistent (such as zalloc or state being NULL).
716 extern int EXPORT deflateParams OF((z_streamp strm, int level, int strategy));
718 Dynamically update the compression level and compression strategy.
719 This can be used to switch between compression and straight copy of
720 the input data, or to switch to a different kind of input data requiring
721 a different strategy. If the compression level is changed, the input
722 available so far is compressed with the old level (and may be flushed);
723 the new level will take effect only at the next call of deflate().
725 Before the call of deflateParams, the stream state must be set as for
726 a call of deflate(), since the currently available input may have to
727 be compressed and flushed. In particular, strm->avail_out must be non-zero.
729 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
730 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
731 if strm->avail_out was zero.
734 extern int EXPORT deflateOutputPending OF((z_streamp strm));
736 Returns the number of bytes of output which are immediately
737 available from the compressor (i.e. without any further input
742 extern int EXPORT inflateInit2 OF((z_streamp strm,
745 This is another version of inflateInit with more compression options. The
746 fields next_out, zalloc, zfree and opaque must be initialized before by
749 The windowBits parameter is the base two logarithm of the maximum window
750 size (the size of the history buffer). It should be in the range 8..15 for
751 this version of the library (the value 16 will be allowed soon). The
752 default value is 15 if inflateInit is used instead. If a compressed stream
753 with a larger window size is given as input, inflate() will return with
754 the error code Z_DATA_ERROR instead of trying to allocate a larger window.
756 If next_out is not null, the library will use this buffer for the history
757 buffer; the buffer must either be large enough to hold the entire output
758 data, or have at least 1<<windowBits bytes. If next_out is null, the
759 library will allocate its own buffer (and leave next_out null). next_in
760 need not be provided here but must be provided by the application for the
761 next call of inflate().
763 If the history buffer is provided by the application, next_out must
764 never be changed by the application since the decompressor maintains
765 history information inside this buffer from call to call; the application
766 can only reset next_out to the beginning of the history buffer when
767 avail_out is zero and all output has been consumed.
769 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
770 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
771 windowBits < 8). msg is set to null if there is no error message.
772 inflateInit2 does not perform any decompression: this will be done by
776 extern int EXPORT inflateSetDictionary OF((z_streamp strm,
777 const Bytef *dictionary,
780 Initializes the decompression dictionary (history buffer) from the given
781 uncompressed byte sequence. This function must be called immediately after
782 a call of inflate if this call returned Z_NEED_DICT. The dictionary chosen
783 by the compressor can be determined from the Adler32 value returned by this
784 call of inflate. The compressor and decompressor must use exactly the same
785 dictionary (see deflateSetDictionary).
787 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
788 parameter is invalid (such as NULL dictionary) or the stream state is
789 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
790 expected one (incorrect Adler32 value). inflateSetDictionary does not
791 perform any decompression: this will be done by subsequent calls of
795 extern int EXPORT inflateSync OF((z_streamp strm));
797 Skips invalid compressed data until the special marker (see deflate()
798 above) can be found, or until all available input is skipped. No output
801 inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
802 if no more input was provided, Z_DATA_ERROR if no marker has been found,
803 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
804 case, the application may save the current current value of total_in which
805 indicates where valid compressed data was found. In the error case, the
806 application may repeatedly call inflateSync, providing more input each time,
807 until success or end of the input data.
810 extern int EXPORT inflateReset OF((z_streamp strm));
812 This function is equivalent to inflateEnd followed by inflateInit,
813 but does not free and reallocate all the internal decompression state.
814 The stream will keep attributes that may have been set by inflateInit2.
816 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
817 stream state was inconsistent (such as zalloc or state being NULL).
820 extern int inflateIncomp OF((z_stream *strm));
822 This function adds the data at next_in (avail_in bytes) to the output
823 history without performing any output. There must be no pending output,
824 and the decompressor must be expecting to see the start of a block.
825 Calling this function is equivalent to decompressing a stored block
826 containing the data at next_in (except that the data is not output).
829 /* utility functions */
832 The following utility functions are implemented on top of the
833 basic stream-oriented functions. To simplify the interface, some
834 default options are assumed (compression level, window size,
835 standard memory allocation functions). The source code of these
836 utility functions can easily be modified if you need special options.
839 extern int EXPORT compress OF((Bytef *dest, uLongf *destLen,
840 const Bytef *source, uLong sourceLen));
842 Compresses the source buffer into the destination buffer. sourceLen is
843 the byte length of the source buffer. Upon entry, destLen is the total
844 size of the destination buffer, which must be at least 0.1% larger than
845 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
847 This function can be used to compress a whole file at once if the
848 input file is mmap'ed.
849 compress returns Z_OK if success, Z_MEM_ERROR if there was not
850 enough memory, Z_BUF_ERROR if there was not enough room in the output
854 extern int EXPORT uncompress OF((Bytef *dest, uLongf *destLen,
855 const Bytef *source, uLong sourceLen));
857 Decompresses the source buffer into the destination buffer. sourceLen is
858 the byte length of the source buffer. Upon entry, destLen is the total
859 size of the destination buffer, which must be large enough to hold the
860 entire uncompressed data. (The size of the uncompressed data must have
861 been saved previously by the compressor and transmitted to the decompressor
862 by some mechanism outside the scope of this compression library.)
863 Upon exit, destLen is the actual size of the compressed buffer.
864 This function can be used to decompress a whole file at once if the
865 input file is mmap'ed.
867 uncompress 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
869 buffer, or Z_DATA_ERROR if the input data was corrupted.
873 typedef voidp gzFile;
875 extern gzFile EXPORT gzopen OF((const char *path, const char *mode));
877 Opens a gzip (.gz) file for reading or writing. The mode parameter
878 is as in fopen ("rb" or "wb") but can also include a compression level
879 ("wb9"). gzopen can be used to read a file which is not in gzip format;
880 in this case gzread will directly read from the file without decompression.
881 gzopen returns NULL if the file could not be opened or if there was
882 insufficient memory to allocate the (de)compression state; errno
883 can be checked to distinguish the two cases (if errno is zero, the
884 zlib error is Z_MEM_ERROR).
887 extern gzFile EXPORT gzdopen OF((int fd, const char *mode));
889 gzdopen() associates a gzFile with the file descriptor fd. File
890 descriptors are obtained from calls like open, dup, creat, pipe or
891 fileno (in the file has been previously opened with fopen).
892 The mode parameter is as in gzopen.
893 The next call of gzclose on the returned gzFile will also close the
894 file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
895 descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
896 gzdopen returns NULL if there was insufficient memory to allocate
897 the (de)compression state.
900 extern int EXPORT gzread OF((gzFile file, voidp buf, unsigned len));
902 Reads the given number of uncompressed bytes from the compressed file.
903 If the input file was not in gzip format, gzread copies the given number
904 of bytes into the buffer.
905 gzread returns the number of uncompressed bytes actually read (0 for
906 end of file, -1 for error). */
908 extern int EXPORT gzwrite OF((gzFile file, const voidp buf, unsigned len));
910 Writes the given number of uncompressed bytes into the compressed file.
911 gzwrite returns the number of uncompressed bytes actually written
912 (0 in case of error).
915 extern int EXPORT gzflush OF((gzFile file, int flush));
917 Flushes all pending output into the compressed file. The parameter
918 flush is as in the deflate() function. The return value is the zlib
919 error number (see function gzerror below). gzflush returns Z_OK if
920 the flush parameter is Z_FINISH and all output could be flushed.
921 gzflush should be called only when strictly necessary because it can
925 extern int EXPORT gzclose OF((gzFile file));
927 Flushes all pending output if necessary, closes the compressed file
928 and deallocates all the (de)compression state. The return value is the zlib
929 error number (see function gzerror below).
932 extern const char * EXPORT gzerror OF((gzFile file, int *errnum));
934 Returns the error message for the last error which occurred on the
935 given compressed file. errnum is set to zlib error number. If an
936 error occurred in the filesystem and not in the compression library,
937 errnum is set to Z_ERRNO and the application may consult errno
938 to get the exact error code.
941 /* checksum functions */
944 These functions are not related to compression but are exported
945 anyway because they might be useful in applications using the
949 extern uLong EXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
952 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
953 return the updated checksum. If buf is NULL, this function returns
954 the required initial value for the checksum.
955 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
956 much faster. Usage example:
958 uLong adler = adler32(0L, Z_NULL, 0);
960 while (read_buffer(buffer, length) != EOF) {
961 adler = adler32(adler, buffer, length);
963 if (adler != original_adler) error();
967 extern uLong EXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
969 Update a running crc with the bytes buf[0..len-1] and return the updated
970 crc. If buf is NULL, this function returns the required initial value
971 for the crc. Pre- and post-conditioning (one's complement) is performed
972 within this function so it shouldn't be done by the application.
975 uLong crc = crc32(0L, Z_NULL, 0);
977 while (read_buffer(buffer, length) != EOF) {
978 crc = crc32(crc, buffer, length);
980 if (crc != original_crc) error();
985 /* various hacks, don't look :) */
987 /* deflateInit and inflateInit are macros to allow checking the zlib version
988 * and the compiler's view of z_stream:
990 extern int EXPORT deflateInit_ OF((z_streamp strm, int level,
991 const char *version, int stream_size));
992 extern int EXPORT inflateInit_ OF((z_streamp strm,
993 const char *version, int stream_size));
994 extern int EXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
995 int windowBits, int memLevel, int strategy,
996 const char *version, int stream_size));
997 extern int EXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
998 const char *version, int stream_size));
999 #define deflateInit(strm, level) \
1000 deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1001 #define inflateInit(strm) \
1002 inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1003 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1004 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1005 (strategy), ZLIB_VERSION, sizeof(z_stream))
1006 #define inflateInit2(strm, windowBits) \
1007 inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1009 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
1010 struct internal_state {int dummy;}; /* hack for buggy compilers */
1013 uLongf *get_crc_table OF((void)); /* can be used by asm versions of crc32() */
1019 #endif /* _ZLIB_H */