1 /* zlib.h -- interface of the 'zlib' general purpose compression library
3 * ==FILEVERSION 960122==
6 version 0.95, Aug 16th, 1995.
8 Copyright (C) 1995 Jean-loup Gailly and Mark Adler
10 This software is provided 'as-is', without any express or implied
11 warranty. In no event will the authors be held liable for any damages
12 arising from the use of this software.
14 Permission is granted to anyone to use this software for any purpose,
15 including commercial applications, and to alter it and redistribute it
16 freely, subject to the following restrictions:
18 1. The origin of this software must not be misrepresented; you must not
19 claim that you wrote the original software. If you use this software
20 in a product, an acknowledgment in the product documentation would be
21 appreciated but is not required.
22 2. Altered source versions must be plainly marked as such, and must not be
23 misrepresented as being the original software.
24 3. This notice may not be removed or altered from any source distribution.
26 Jean-loup Gailly Mark Adler
27 gzip@prep.ai.mit.edu madler@alumni.caltech.edu
33 /* #include "zconf.h" */ /* The zconf.h file is included directly. */
35 /* zconf.h -- configuration of the zlib compression library
36 * Copyright (C) 1995 Jean-loup Gailly.
37 * For conditions of distribution and use, see copyright notice in zlib.h
40 /* $Id: zlib.h,v 1.1 1996/06/11 06:41:40 paulus Exp $ */
46 The library does not install any signal handler. It is recommended to
47 add at least a handler for SIGSEGV when decompressing; the library checks
48 the consistency of the input data whenever possible but may go nuts
49 for some forms of corrupted input.
53 * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
54 * than 64k bytes at a time (needed on systems with 16-bit int).
56 #if defined(_GNUC__) && !defined(__32BIT__)
59 #if defined(__MSDOS__) && !defined(MSDOS)
62 #if defined(MSDOS) && !defined(__32BIT__)
70 # if defined(MSDOS) || defined(__STDC__) || defined(__cplusplus)
81 #ifdef __MWERKS__ /* Metrowerks CodeWarrior declares fileno() in unix.h */
85 /* Maximum value for memLevel in deflateInit2 */
88 # define MAX_MEM_LEVEL 8
90 # define MAX_MEM_LEVEL 9
94 /* Maximum value for windowBits in deflateInit2 and inflateInit2 */
96 # define MAX_WBITS 15 /* 32K LZ77 window */
99 /* The memory requirements for deflate are (in bytes):
100 1 << (windowBits+2) + 1 << (memLevel+9)
101 that is: 128K for windowBits=15 + 128K for memLevel = 8 (default values)
102 plus a few kilobytes for small objects. For example, if you want to reduce
103 the default memory requirements from 256K to 128K, compile with
104 make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
105 Of course this will generally degrade compression (there's no free lunch).
107 The memory requirements for inflate are (in bytes) 1 << windowBits
108 that is, 32K for windowBits=15 (default value) plus a few kilobytes
112 /* Type declarations */
114 #ifndef OF /* function prototypes */
116 # define OF(args) args
122 /* The following definitions for FAR are needed only for MSDOS mixed
123 * model programming (small or medium model with some far allocations).
124 * This was tested only with MSC; for other MSDOS compilers you may have
125 * to define NO_MEMCPY in zutil.h. If you don't need the mixed model,
126 * just define FAR to be empty.
128 #if defined(M_I86SM) || defined(M_I86MM) /* MSC small or medium model */
135 #if defined(__BORLANDC__) && (defined(__SMALL__) || defined(__MEDIUM__))
136 # define FAR __far /* completely untested, just a best guess */
142 typedef unsigned char Byte; /* 8 bits */
143 typedef unsigned int uInt; /* 16 bits or more */
144 typedef unsigned long uLong; /* 32 bits or more */
146 typedef Byte FAR Bytef;
147 typedef char FAR charf;
148 typedef int FAR intf;
149 typedef uInt FAR uIntf;
150 typedef uLong FAR uLongf;
153 typedef void FAR *voidpf;
156 typedef Byte FAR *voidpf;
160 #endif /* _ZCONF_H */
163 #define ZLIB_VERSION "0.95P"
166 The 'zlib' compression library provides in-memory compression and
167 decompression functions, including integrity checks of the uncompressed
168 data. This version of the library supports only one compression method
169 (deflation) but other algorithms may be added later and will have the same
172 For compression the application must provide the output buffer and
173 may optionally provide the input buffer for optimization. For decompression,
174 the application must provide the input buffer and may optionally provide
175 the output buffer for optimization.
177 Compression can be done in a single step if the buffers are large
178 enough (for example if an input file is mmap'ed), or can be done by
179 repeated calls of the compression function. In the latter case, the
180 application must provide more input and/or consume the output
181 (providing more output space) before each call.
184 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
185 typedef void (*free_func) OF((voidpf opaque, voidpf address, uInt nbytes));
187 struct internal_state;
189 typedef struct z_stream_s {
190 Bytef *next_in; /* next input byte */
191 uInt avail_in; /* number of bytes available at next_in */
192 uLong total_in; /* total nb of input bytes read so far */
194 Bytef *next_out; /* next output byte should be put there */
195 uInt avail_out; /* remaining free space at next_out */
196 uLong total_out; /* total nb of bytes output so far */
198 char *msg; /* last error message, NULL if no error */
199 struct internal_state FAR *state; /* not visible by applications */
201 alloc_func zalloc; /* used to allocate the internal state */
202 free_func zfree; /* used to free the internal state */
203 voidp opaque; /* private data object passed to zalloc and zfree */
205 Byte data_type; /* best guess about the data type: ascii or binary */
210 The application must update next_in and avail_in when avail_in has
211 dropped to zero. It must update next_out and avail_out when avail_out
212 has dropped to zero. The application must initialize zalloc, zfree and
213 opaque before calling the init function. All other fields are set by the
214 compression library and must not be updated by the application.
216 The opaque value provided by the application will be passed as the first
217 parameter for calls of zalloc and zfree. This can be useful for custom
218 memory management. The compression library attaches no meaning to the
221 zalloc must return Z_NULL if there is not enough memory for the object.
222 On 16-bit systems, the functions zalloc and zfree must be able to allocate
223 exactly 65536 bytes, but will not be required to allocate more than this
224 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
225 pointers returned by zalloc for objects of exactly 65536 bytes *must*
226 have their offset normalized to zero. The default allocation function
227 provided by this library ensures this (see zutil.c). To reduce memory
228 requirements and avoid any allocation of 64K objects, at the expense of
229 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
231 The fields total_in and total_out can be used for statistics or
232 progress reports. After compression, total_in holds the total size of
233 the uncompressed data and may be saved for use in the decompressor
234 (particularly if the decompressor wants to decompress everything in
241 #define Z_PARTIAL_FLUSH 1
242 #define Z_FULL_FLUSH 2
243 #define Z_SYNC_FLUSH 3 /* experimental: partial_flush + byte align */
245 #define Z_PACKET_FLUSH 5
246 /* See deflate() below for the usage of these constants */
249 #define Z_STREAM_END 1
251 #define Z_STREAM_ERROR (-2)
252 #define Z_DATA_ERROR (-3)
253 #define Z_MEM_ERROR (-4)
254 #define Z_BUF_ERROR (-5)
255 /* error codes for the compression/decompression functions */
257 #define Z_BEST_SPEED 1
258 #define Z_BEST_COMPRESSION 9
259 #define Z_DEFAULT_COMPRESSION (-1)
260 /* compression levels */
263 #define Z_HUFFMAN_ONLY 2
264 #define Z_DEFAULT_STRATEGY 0
269 /* Used to set the data_type field */
271 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
273 extern char *zlib_version;
274 /* The application can compare zlib_version and ZLIB_VERSION for consistency.
275 If the first character differs, the library code actually used is
276 not compatible with the zlib.h header file used by the application.
279 /* basic functions */
281 extern int deflateInit OF((z_stream *strm, int level));
283 Initializes the internal stream state for compression. The fields
284 zalloc, zfree and opaque must be initialized before by the caller.
285 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
286 use default allocation functions.
288 The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
289 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
290 a default compromise between speed and compression (currently equivalent
293 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
294 enough memory, Z_STREAM_ERROR if level is not a valid compression level.
295 msg is set to null if there is no error message. deflateInit does not
296 perform any compression: this will be done by deflate().
300 extern int deflate OF((z_stream *strm, int flush));
302 Performs one or both of the following actions:
304 - Compress more input starting at next_in and update next_in and avail_in
305 accordingly. If not all input can be processed (because there is not
306 enough room in the output buffer), next_in and avail_in are updated and
307 processing will resume at this point for the next call of deflate().
309 - Provide more output starting at next_out and update next_out and avail_out
310 accordingly. This action is forced if the parameter flush is non zero.
311 Forcing flush frequently degrades the compression ratio, so this parameter
312 should be set only when necessary (in interactive applications).
313 Some output may be provided even if flush is not set.
315 Before the call of deflate(), the application should ensure that at least
316 one of the actions is possible, by providing more input and/or consuming
317 more output, and updating avail_in or avail_out accordingly; avail_out
318 should never be zero before the call. The application can consume the
319 compressed output when it wants, for example when the output buffer is full
320 (avail_out == 0), or after each call of deflate().
322 If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
323 block is terminated and flushed to the output buffer so that the
324 decompressor can get all input data available so far. For method 9, a future
325 variant on method 8, the current block will be flushed but not terminated.
326 If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
327 special marker is output and the compression dictionary is discarded; this
328 is useful to allow the decompressor to synchronize if one compressed block
329 has been damaged (see inflateSync below). Flushing degrades compression and
330 so should be used only when necessary. Using Z_FULL_FLUSH too often can
331 seriously degrade the compression. If deflate returns with avail_out == 0,
332 this function must be called again with the same value of the flush
333 parameter and more output space (updated avail_out), until the flush is
334 complete (deflate returns with non-zero avail_out).
336 If the parameter flush is set to Z_PACKET_FLUSH, the compression
337 block is terminated, and a zero-length stored block is output,
338 omitting the length bytes (the effect of this is that the 3-bit type
339 code 000 for a stored block is output, and the output is then
340 byte-aligned). This is designed for use at the end of a PPP packet.
341 In addition, if the current compression block contains all the data
342 since the last Z_PACKET_FLUSH, it is never output as a stored block.
343 If the current compression block output as a static or dynamic block
344 would not be at least `minCompression' bytes smaller than the
345 original data, then nothing is output for that block. (The type
346 code for the zero-length stored block is still output, resulting in
347 a single zero byte being output for the whole packet.)
348 `MinCompression' is a parameter to deflateInit2, or 0 if deflateInit
351 If the parameter flush is set to Z_FINISH, all pending input is processed,
352 all pending output is flushed and deflate returns with Z_STREAM_END if there
353 was enough output space; if deflate returns with Z_OK, this function must be
354 called again with Z_FINISH and more output space (updated avail_out) but no
355 more input data, until it returns with Z_STREAM_END or an error. After
356 deflate has returned Z_STREAM_END, the only possible operations on the
357 stream are deflateReset or deflateEnd.
359 Z_FINISH can be used immediately after deflateInit if all the compression
360 is to be done in a single step. In this case, avail_out must be at least
361 0.1% larger than avail_in plus 12 bytes. If deflate does not return
362 Z_STREAM_END, then it must be called again as described above.
364 deflate() may update data_type if it can make a good guess about
365 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
366 binary. This field is only for information purposes and does not affect
367 the compression algorithm in any manner.
369 deflate() returns Z_OK if some progress has been made (more input
370 processed or more output produced), Z_STREAM_END if all input has been
371 consumed and all output has been produced (only when flush is set to
372 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
373 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
377 extern int deflateEnd OF((z_stream *strm));
379 All dynamically allocated data structures for this stream are freed.
380 This function discards any unprocessed input and does not flush any
383 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
384 stream state was inconsistent. In the error case, msg may be set
385 but then points to a static string (which must not be deallocated).
389 extern int inflateInit OF((z_stream *strm));
391 Initializes the internal stream state for decompression. The fields
392 zalloc and zfree must be initialized before by the caller. If zalloc and
393 zfree are set to Z_NULL, inflateInit updates them to use default allocation
396 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
397 enough memory. msg is set to null if there is no error message.
398 inflateInit does not perform any decompression: this will be done by
403 extern int inflate OF((z_stream *strm, int flush));
405 Performs one or both of the following actions:
407 - Decompress more input starting at next_in and update next_in and avail_in
408 accordingly. If not all input can be processed (because there is not
409 enough room in the output buffer), next_in is updated and processing
410 will resume at this point for the next call of inflate().
412 - Provide more output starting at next_out and update next_out and avail_out
413 accordingly. inflate() always provides as much output as possible
414 (until there is no more input data or no more space in the output buffer).
416 Before the call of inflate(), the application should ensure that at least
417 one of the actions is possible, by providing more input and/or consuming
418 more output, and updating the next_* and avail_* values accordingly.
419 The application can consume the uncompressed output when it wants, for
420 example when the output buffer is full (avail_out == 0), or after each
423 If the parameter flush is set to Z_PARTIAL_FLUSH or Z_PACKET_FLUSH,
424 inflate flushes as much output as possible to the output buffer. The
425 flushing behavior of inflate is not specified for values of the flush
426 parameter other than Z_PARTIAL_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
427 current implementation actually flushes as much output as possible
428 anyway. For Z_PACKET_FLUSH, inflate checks that once all the input data
429 has been consumed, it is expecting to see the length field of a stored
430 block; if not, it returns Z_DATA_ERROR.
432 inflate() should normally be called until it returns Z_STREAM_END or an
433 error. However if all decompression is to be performed in a single step
434 (a single call of inflate), the parameter flush should be set to
435 Z_FINISH. In this case all pending input is processed and all pending
436 output is flushed; avail_out must be large enough to hold all the
437 uncompressed data. (The size of the uncompressed data may have been saved
438 by the compressor for this purpose.) The next operation on this stream must
439 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
440 is never required, but can be used to inform inflate that a faster routine
441 may be used for the single inflate() call.
443 inflate() returns Z_OK if some progress has been made (more input
444 processed or more output produced), Z_STREAM_END if the end of the
445 compressed data has been reached and all uncompressed output has been
446 produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
447 the stream structure was inconsistent (for example if next_in or next_out
448 was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
449 progress is possible or if there was not enough room in the output buffer
450 when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
451 call inflateSync to look for a good compression block. */
454 extern int inflateEnd OF((z_stream *strm));
456 All dynamically allocated data structures for this stream are freed.
457 This function discards any unprocessed input and does not flush any
460 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
461 was inconsistent. In the error case, msg may be set but then points to a
462 static string (which must not be deallocated).
465 /* advanced functions */
468 The following functions are needed only in some special applications.
471 extern int deflateInit2 OF((z_stream *strm,
477 int minCompression));
479 This is another version of deflateInit with more compression options. The
480 fields next_in, zalloc and zfree must be initialized before by the caller.
482 The method parameter is the compression method. It must be 8 in this
483 version of the library. (Method 9 will allow a 64K history buffer and
484 partial block flushes.)
486 The windowBits parameter is the base two logarithm of the window size
487 (the size of the history buffer). It should be in the range 8..15 for this
488 version of the library (the value 16 will be allowed for method 9). Larger
489 values of this parameter result in better compression at the expense of
490 memory usage. The default value is 15 if deflateInit is used instead.
492 The memLevel parameter specifies how much memory should be allocated
493 for the internal compression state. memLevel=1 uses minimum memory but
494 is slow and reduces compression ratio; memLevel=9 uses maximum memory
495 for optimal speed. The default value is 8. See zconf.h for total memory
496 usage as a function of windowBits and memLevel.
498 The strategy parameter is used to tune the compression algorithm. Use
499 the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
500 produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
501 encoding only (no string match). Filtered data consists mostly of small
502 values with a somewhat random distribution. In this case, the
503 compression algorithm is tuned to compress them better. The strategy
504 parameter only affects the compression ratio but not the correctness of
505 the compressed output even if it is not set appropriately.
507 The minCompression parameter specifies the minimum reduction in size
508 required for a compressed block to be output when Z_PACKET_FLUSH is
509 used (see the description of deflate above).
511 If next_in is not null, the library will use this buffer to hold also
512 some history information; the buffer must either hold the entire input
513 data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
514 is null, the library will allocate its own history buffer (and leave next_in
515 null). next_out need not be provided here but must be provided by the
516 application for the next call of deflate().
518 If the history buffer is provided by the application, next_in must
519 must never be changed by the application since the compressor maintains
520 information inside this buffer from call to call; the application
521 must provide more input only by increasing avail_in. next_in is always
522 reset by the library in this case.
524 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
525 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
526 an invalid method). msg is set to null if there is no error message.
527 deflateInit2 does not perform any compression: this will be done by
531 extern int deflateCopy OF((z_stream *dest,
534 Sets the destination stream as a complete copy of the source stream. If
535 the source stream is using an application-supplied history buffer, a new
536 buffer is allocated for the destination stream. The compressed output
537 buffer is always application-supplied. It's the responsibility of the
538 application to provide the correct values of next_out and avail_out for the
539 next call of deflate.
541 This function is useful when several compression strategies will be
542 tried, for example when there are several ways of pre-processing the input
543 data with a filter. The streams that will be discarded should then be freed
544 by calling deflateEnd. Note that deflateCopy duplicates the internal
545 compression state which can be quite large, so this strategy is slow and
546 can consume lots of memory.
548 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
549 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
550 (such as zalloc being NULL). msg is left unchanged in both source and
554 extern int deflateReset OF((z_stream *strm));
556 This function is equivalent to deflateEnd followed by deflateInit,
557 but does not free and reallocate all the internal compression state.
558 The stream will keep the same compression level and any other attributes
559 that may have been set by deflateInit2.
561 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
562 stream state was inconsistent (such as zalloc or state being NULL).
565 extern int inflateInit2 OF((z_stream *strm,
568 This is another version of inflateInit with more compression options. The
569 fields next_out, zalloc and zfree must be initialized before by the caller.
571 The windowBits parameter is the base two logarithm of the maximum window
572 size (the size of the history buffer). It should be in the range 8..15 for
573 this version of the library (the value 16 will be allowed soon). The
574 default value is 15 if inflateInit is used instead. If a compressed stream
575 with a larger window size is given as input, inflate() will return with
576 the error code Z_DATA_ERROR instead of trying to allocate a larger window.
578 If next_out is not null, the library will use this buffer for the history
579 buffer; the buffer must either be large enough to hold the entire output
580 data, or have at least 1<<windowBits bytes. If next_out is null, the
581 library will allocate its own buffer (and leave next_out null). next_in
582 need not be provided here but must be provided by the application for the
583 next call of inflate().
585 If the history buffer is provided by the application, next_out must
586 never be changed by the application since the decompressor maintains
587 history information inside this buffer from call to call; the application
588 can only reset next_out to the beginning of the history buffer when
589 avail_out is zero and all output has been consumed.
591 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
592 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
593 windowBits < 8). msg is set to null if there is no error message.
594 inflateInit2 does not perform any decompression: this will be done by
598 extern int inflateSync OF((z_stream *strm));
600 Skips invalid compressed data until the special marker (see deflate()
601 above) can be found, or until all available input is skipped. No output
604 inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
605 if no more input was provided, Z_DATA_ERROR if no marker has been found,
606 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
607 case, the application may save the current current value of total_in which
608 indicates where valid compressed data was found. In the error case, the
609 application may repeatedly call inflateSync, providing more input each time,
610 until success or end of the input data.
613 extern int inflateReset OF((z_stream *strm));
615 This function is equivalent to inflateEnd followed by inflateInit,
616 but does not free and reallocate all the internal decompression state.
617 The stream will keep attributes that may have been set by inflateInit2.
619 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
620 stream state was inconsistent (such as zalloc or state being NULL).
623 extern int inflateIncomp OF((z_stream *strm));
625 This function adds the data at next_in (avail_in bytes) to the output
626 history without performing any output. There must be no pending output,
627 and the decompressor must be expecting to see the start of a block.
628 Calling this function is equivalent to decompressing a stored block
629 containing the data at next_in (except that the data is not output).
632 /* checksum functions */
635 These functions are not related to compression but are exported
636 anyway because they might be useful in applications using the
640 extern uLong adler32 OF((uLong adler, Bytef *buf, uInt len));
643 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
644 return the updated checksum. If buf is NULL, this function returns
645 the required initial value for the checksum.
646 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
647 much faster. Usage example:
649 uLong adler = adler32(0L, Z_NULL, 0);
651 while (read_buffer(buffer, length) != EOF) {
652 adler = adler32(adler, buffer, length);
654 if (adler != original_adler) error();
657 extern uLong crc32 OF((uLong crc, Bytef *buf, uInt len));
659 Update a running crc with the bytes buf[0..len-1] and return the updated
660 crc. If buf is NULL, this function returns the required initial value
661 for the crc. Pre- and post-conditioning (one's complement) is performed
662 within this function so it shouldn't be done by the application.
665 uLong crc = crc32(0L, Z_NULL, 0);
667 while (read_buffer(buffer, length) != EOF) {
668 crc = crc32(crc, buffer, length);
670 if (crc != original_crc) error();
674 struct internal_state {int dummy;}; /* hack for buggy compilers */
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