1 /* $Id: zlib.h,v 1.6 1997/05/22 06:44:40 paulus Exp $ */
4 * This file is derived from zlib.h and zconf.h from the zlib-0.95
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 970501==
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.
17 /* zlib.h -- interface of the 'zlib' general purpose compression library
18 version 0.95, Aug 16th, 1995.
20 Copyright (C) 1995 Jean-loup Gailly and Mark Adler
22 This software is provided 'as-is', without any express or implied
23 warranty. In no event will the authors be held liable for any damages
24 arising from the use of this software.
26 Permission is granted to anyone to use this software for any purpose,
27 including commercial applications, and to alter it and redistribute it
28 freely, subject to the following restrictions:
30 1. The origin of this software must not be misrepresented; you must not
31 claim that you wrote the original software. If you use this software
32 in a product, an acknowledgment in the product documentation would be
33 appreciated but is not required.
34 2. Altered source versions must be plainly marked as such, and must not be
35 misrepresented as being the original software.
36 3. This notice may not be removed or altered from any source distribution.
38 Jean-loup Gailly Mark Adler
39 gzip@prep.ai.mit.edu madler@alumni.caltech.edu
45 /* #include "zconf.h" */ /* included directly here */
47 /* zconf.h -- configuration of the zlib compression library
48 * Copyright (C) 1995 Jean-loup Gailly.
49 * For conditions of distribution and use, see copyright notice in zlib.h
52 /* From: zconf.h,v 1.12 1995/05/03 17:27:12 jloup Exp */
55 The library does not install any signal handler. It is recommended to
56 add at least a handler for SIGSEGV when decompressing; the library checks
57 the consistency of the input data whenever possible but may go nuts
58 for some forms of corrupted input.
62 * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
63 * than 64k bytes at a time (needed on systems with 16-bit int).
64 * Compile with -DUNALIGNED_OK if it is OK to access shorts or ints
65 * at addresses which are not a multiple of their size.
66 * Under DOS, -DFAR=far or -DFAR=__far may be needed.
70 # if defined(MSDOS) || defined(__STDC__) || defined(__cplusplus)
75 #ifdef __MWERKS__ /* Metrowerks CodeWarrior declares fileno() in unix.h */
79 /* Maximum value for memLevel in deflateInit2 */
82 # define MAX_MEM_LEVEL 8
84 # define MAX_MEM_LEVEL 9
92 /* Maximum value for windowBits in deflateInit2 and inflateInit2 */
94 # define MAX_WBITS 15 /* 32K LZ77 window */
97 /* The memory requirements for deflate are (in bytes):
98 1 << (windowBits+2) + 1 << (memLevel+9)
99 that is: 128K for windowBits=15 + 128K for memLevel = 8 (default values)
100 plus a few kilobytes for small objects. For example, if you want to reduce
101 the default memory requirements from 256K to 128K, compile with
102 make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
103 Of course this will generally degrade compression (there's no free lunch).
105 The memory requirements for inflate are (in bytes) 1 << windowBits
106 that is, 32K for windowBits=15 (default value) plus a few kilobytes
110 /* Type declarations */
112 #ifndef OF /* function prototypes */
114 # define OF(args) args
120 typedef unsigned char Byte; /* 8 bits */
121 typedef unsigned int uInt; /* 16 bits or more */
122 typedef unsigned long uLong; /* 32 bits or more */
124 typedef Byte FAR Bytef;
125 typedef char FAR charf;
126 typedef int FAR intf;
127 typedef uInt FAR uIntf;
128 typedef uLong FAR uLongf;
131 typedef void FAR *voidpf;
134 typedef Byte FAR *voidpf;
138 /* end of original zconf.h */
140 #define ZLIB_VERSION "0.95P"
143 The 'zlib' compression library provides in-memory compression and
144 decompression functions, including integrity checks of the uncompressed
145 data. This version of the library supports only one compression method
146 (deflation) but other algorithms may be added later and will have the same
149 For compression the application must provide the output buffer and
150 may optionally provide the input buffer for optimization. For decompression,
151 the application must provide the input buffer and may optionally provide
152 the output buffer for optimization.
154 Compression can be done in a single step if the buffers are large
155 enough (for example if an input file is mmap'ed), or can be done by
156 repeated calls of the compression function. In the latter case, the
157 application must provide more input and/or consume the output
158 (providing more output space) before each call.
161 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
162 typedef void (*free_func) OF((voidpf opaque, voidpf address, uInt nbytes));
164 struct internal_state;
166 typedef struct z_stream_s {
167 Bytef *next_in; /* next input byte */
168 uInt avail_in; /* number of bytes available at next_in */
169 uLong total_in; /* total nb of input bytes read so far */
171 Bytef *next_out; /* next output byte should be put there */
172 uInt avail_out; /* remaining free space at next_out */
173 uLong total_out; /* total nb of bytes output so far */
175 char *msg; /* last error message, NULL if no error */
176 struct internal_state FAR *state; /* not visible by applications */
178 alloc_func zalloc; /* used to allocate the internal state */
179 alloc_func zalloc_init; /* used to allocate the internal state during initialization */
180 free_func zfree; /* used to free the internal state */
181 voidp opaque; /* private data object passed to zalloc and zfree */
183 Byte data_type; /* best guess about the data type: ascii or binary */
188 The application must update next_in and avail_in when avail_in has
189 dropped to zero. It must update next_out and avail_out when avail_out
190 has dropped to zero. The application must initialize zalloc, zfree and
191 opaque before calling the init function. All other fields are set by the
192 compression library and must not be updated by the application.
194 The opaque value provided by the application will be passed as the first
195 parameter for calls of zalloc and zfree. This can be useful for custom
196 memory management. The compression library attaches no meaning to the
199 zalloc must return Z_NULL if there is not enough memory for the object.
200 On 16-bit systems, the functions zalloc and zfree must be able to allocate
201 exactly 65536 bytes, but will not be required to allocate more than this
202 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
203 pointers returned by zalloc for objects of exactly 65536 bytes *must*
204 have their offset normalized to zero. The default allocation function
205 provided by this library ensures this (see zutil.c). To reduce memory
206 requirements and avoid any allocation of 64K objects, at the expense of
207 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
209 The fields total_in and total_out can be used for statistics or
210 progress reports. After compression, total_in holds the total size of
211 the uncompressed data and may be saved for use in the decompressor
212 (particularly if the decompressor wants to decompress everything in
219 #define Z_PARTIAL_FLUSH 1
220 #define Z_FULL_FLUSH 2
221 #define Z_SYNC_FLUSH 3 /* experimental: partial_flush + byte align */
223 #define Z_PACKET_FLUSH 5
224 /* See deflate() below for the usage of these constants */
227 #define Z_STREAM_END 1
229 #define Z_STREAM_ERROR (-2)
230 #define Z_DATA_ERROR (-3)
231 #define Z_MEM_ERROR (-4)
232 #define Z_BUF_ERROR (-5)
233 /* error codes for the compression/decompression functions */
235 #define Z_BEST_SPEED 1
236 #define Z_BEST_COMPRESSION 9
237 #define Z_DEFAULT_COMPRESSION (-1)
238 /* compression levels */
241 #define Z_HUFFMAN_ONLY 2
242 #define Z_DEFAULT_STRATEGY 0
247 /* Used to set the data_type field */
249 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
251 extern char *zlib_version;
252 /* The application can compare zlib_version and ZLIB_VERSION for consistency.
253 If the first character differs, the library code actually used is
254 not compatible with the zlib.h header file used by the application.
257 /* basic functions */
259 extern int deflateInit OF((z_stream *strm, int level));
261 Initializes the internal stream state for compression. The fields
262 zalloc, zfree and opaque must be initialized before by the caller.
263 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
264 use default allocation functions.
266 The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
267 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
268 a default compromise between speed and compression (currently equivalent
271 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
272 enough memory, Z_STREAM_ERROR if level is not a valid compression level.
273 msg is set to null if there is no error message. deflateInit does not
274 perform any compression: this will be done by deflate().
278 extern int deflate OF((z_stream *strm, int flush));
280 Performs one or both of the following actions:
282 - Compress more input starting at next_in and update next_in and avail_in
283 accordingly. If not all input can be processed (because there is not
284 enough room in the output buffer), next_in and avail_in are updated and
285 processing will resume at this point for the next call of deflate().
287 - Provide more output starting at next_out and update next_out and avail_out
288 accordingly. This action is forced if the parameter flush is non zero.
289 Forcing flush frequently degrades the compression ratio, so this parameter
290 should be set only when necessary (in interactive applications).
291 Some output may be provided even if flush is not set.
293 Before the call of deflate(), the application should ensure that at least
294 one of the actions is possible, by providing more input and/or consuming
295 more output, and updating avail_in or avail_out accordingly; avail_out
296 should never be zero before the call. The application can consume the
297 compressed output when it wants, for example when the output buffer is full
298 (avail_out == 0), or after each call of deflate().
300 If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
301 block is terminated and flushed to the output buffer so that the
302 decompressor can get all input data available so far. For method 9, a future
303 variant on method 8, the current block will be flushed but not terminated.
304 If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
305 special marker is output and the compression dictionary is discarded; this
306 is useful to allow the decompressor to synchronize if one compressed block
307 has been damaged (see inflateSync below). Flushing degrades compression and
308 so should be used only when necessary. Using Z_FULL_FLUSH too often can
309 seriously degrade the compression. If deflate returns with avail_out == 0,
310 this function must be called again with the same value of the flush
311 parameter and more output space (updated avail_out), until the flush is
312 complete (deflate returns with non-zero avail_out).
314 If the parameter flush is set to Z_PACKET_FLUSH, the compression
315 block is terminated, and a zero-length stored block is output,
316 omitting the length bytes (the effect of this is that the 3-bit type
317 code 000 for a stored block is output, and the output is then
318 byte-aligned). This is designed for use at the end of a PPP packet.
319 In addition, if the current compression block contains all the data
320 since the last Z_PACKET_FLUSH, it is never output as a stored block.
321 If the current compression block output as a static or dynamic block
322 would not be at least `minCompression' bytes smaller than the
323 original data, then nothing is output for that block. (The type
324 code for the zero-length stored block is still output, resulting in
325 a single zero byte being output for the whole packet.)
326 `MinCompression' is a parameter to deflateInit2, or 0 if deflateInit
329 If the parameter flush is set to Z_FINISH, all pending input is processed,
330 all pending output is flushed and deflate returns with Z_STREAM_END if there
331 was enough output space; if deflate returns with Z_OK, this function must be
332 called again with Z_FINISH and more output space (updated avail_out) but no
333 more input data, until it returns with Z_STREAM_END or an error. After
334 deflate has returned Z_STREAM_END, the only possible operations on the
335 stream are deflateReset or deflateEnd.
337 Z_FINISH can be used immediately after deflateInit if all the compression
338 is to be done in a single step. In this case, avail_out must be at least
339 0.1% larger than avail_in plus 12 bytes. If deflate does not return
340 Z_STREAM_END, then it must be called again as described above.
342 deflate() may update data_type if it can make a good guess about
343 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
344 binary. This field is only for information purposes and does not affect
345 the compression algorithm in any manner.
347 deflate() returns Z_OK if some progress has been made (more input
348 processed or more output produced), Z_STREAM_END if all input has been
349 consumed and all output has been produced (only when flush is set to
350 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
351 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
355 extern int deflateEnd OF((z_stream *strm));
357 All dynamically allocated data structures for this stream are freed.
358 This function discards any unprocessed input and does not flush any
361 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
362 stream state was inconsistent. In the error case, msg may be set
363 but then points to a static string (which must not be deallocated).
367 extern int inflateInit OF((z_stream *strm));
369 Initializes the internal stream state for decompression. The fields
370 zalloc and zfree must be initialized before by the caller. If zalloc and
371 zfree are set to Z_NULL, inflateInit updates them to use default allocation
374 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
375 enough memory. msg is set to null if there is no error message.
376 inflateInit does not perform any decompression: this will be done by
381 #if defined(__FreeBSD__) && (defined(KERNEL) || defined(_KERNEL))
382 #define inflate inflate_ppp /* FreeBSD already has an inflate :-( */
385 extern int inflate OF((z_stream *strm, int flush));
387 Performs one or both of the following actions:
389 - Decompress more input starting at next_in and update next_in and avail_in
390 accordingly. If not all input can be processed (because there is not
391 enough room in the output buffer), next_in is updated and processing
392 will resume at this point for the next call of inflate().
394 - Provide more output starting at next_out and update next_out and avail_out
395 accordingly. inflate() always provides as much output as possible
396 (until there is no more input data or no more space in the output buffer).
398 Before the call of inflate(), the application should ensure that at least
399 one of the actions is possible, by providing more input and/or consuming
400 more output, and updating the next_* and avail_* values accordingly.
401 The application can consume the uncompressed output when it wants, for
402 example when the output buffer is full (avail_out == 0), or after each
405 If the parameter flush is set to Z_PARTIAL_FLUSH or Z_PACKET_FLUSH,
406 inflate flushes as much output as possible to the output buffer. The
407 flushing behavior of inflate is not specified for values of the flush
408 parameter other than Z_PARTIAL_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
409 current implementation actually flushes as much output as possible
410 anyway. For Z_PACKET_FLUSH, inflate checks that once all the input data
411 has been consumed, it is expecting to see the length field of a stored
412 block; if not, it returns Z_DATA_ERROR.
414 inflate() should normally be called until it returns Z_STREAM_END or an
415 error. However if all decompression is to be performed in a single step
416 (a single call of inflate), the parameter flush should be set to
417 Z_FINISH. In this case all pending input is processed and all pending
418 output is flushed; avail_out must be large enough to hold all the
419 uncompressed data. (The size of the uncompressed data may have been saved
420 by the compressor for this purpose.) The next operation on this stream must
421 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
422 is never required, but can be used to inform inflate that a faster routine
423 may be used for the single inflate() call.
425 inflate() returns Z_OK if some progress has been made (more input
426 processed or more output produced), Z_STREAM_END if the end of the
427 compressed data has been reached and all uncompressed output has been
428 produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
429 the stream structure was inconsistent (for example if next_in or next_out
430 was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
431 progress is possible or if there was not enough room in the output buffer
432 when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
433 call inflateSync to look for a good compression block. */
436 extern int inflateEnd OF((z_stream *strm));
438 All dynamically allocated data structures for this stream are freed.
439 This function discards any unprocessed input and does not flush any
442 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
443 was inconsistent. In the error case, msg may be set but then points to a
444 static string (which must not be deallocated).
447 /* advanced functions */
450 The following functions are needed only in some special applications.
453 extern int deflateInit2 OF((z_stream *strm,
459 int minCompression));
461 This is another version of deflateInit with more compression options. The
462 fields next_in, zalloc and zfree must be initialized before by the caller.
464 The method parameter is the compression method. It must be 8 in this
465 version of the library. (Method 9 will allow a 64K history buffer and
466 partial block flushes.)
468 The windowBits parameter is the base two logarithm of the window size
469 (the size of the history buffer). It should be in the range 8..15 for this
470 version of the library (the value 16 will be allowed for method 9). Larger
471 values of this parameter result in better compression at the expense of
472 memory usage. The default value is 15 if deflateInit is used instead.
474 The memLevel parameter specifies how much memory should be allocated
475 for the internal compression state. memLevel=1 uses minimum memory but
476 is slow and reduces compression ratio; memLevel=9 uses maximum memory
477 for optimal speed. The default value is 8. See zconf.h for total memory
478 usage as a function of windowBits and memLevel.
480 The strategy parameter is used to tune the compression algorithm. Use
481 the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
482 produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
483 encoding only (no string match). Filtered data consists mostly of small
484 values with a somewhat random distribution. In this case, the
485 compression algorithm is tuned to compress them better. The strategy
486 parameter only affects the compression ratio but not the correctness of
487 the compressed output even if it is not set appropriately.
489 The minCompression parameter specifies the minimum reduction in size
490 required for a compressed block to be output when Z_PACKET_FLUSH is
491 used (see the description of deflate above).
493 If next_in is not null, the library will use this buffer to hold also
494 some history information; the buffer must either hold the entire input
495 data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
496 is null, the library will allocate its own history buffer (and leave next_in
497 null). next_out need not be provided here but must be provided by the
498 application for the next call of deflate().
500 If the history buffer is provided by the application, next_in must
501 must never be changed by the application since the compressor maintains
502 information inside this buffer from call to call; the application
503 must provide more input only by increasing avail_in. next_in is always
504 reset by the library in this case.
506 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
507 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
508 an invalid method). msg is set to null if there is no error message.
509 deflateInit2 does not perform any compression: this will be done by
513 extern int deflateCopy OF((z_stream *dest,
516 Sets the destination stream as a complete copy of the source stream. If
517 the source stream is using an application-supplied history buffer, a new
518 buffer is allocated for the destination stream. The compressed output
519 buffer is always application-supplied. It's the responsibility of the
520 application to provide the correct values of next_out and avail_out for the
521 next call of deflate.
523 This function is useful when several compression strategies will be
524 tried, for example when there are several ways of pre-processing the input
525 data with a filter. The streams that will be discarded should then be freed
526 by calling deflateEnd. Note that deflateCopy duplicates the internal
527 compression state which can be quite large, so this strategy is slow and
528 can consume lots of memory.
530 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
531 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
532 (such as zalloc being NULL). msg is left unchanged in both source and
536 extern int deflateReset OF((z_stream *strm));
538 This function is equivalent to deflateEnd followed by deflateInit,
539 but does not free and reallocate all the internal compression state.
540 The stream will keep the same compression level and any other attributes
541 that may have been set by deflateInit2.
543 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
544 stream state was inconsistent (such as zalloc or state being NULL).
547 extern int inflateInit2 OF((z_stream *strm,
550 This is another version of inflateInit with more compression options. The
551 fields next_out, zalloc and zfree must be initialized before by the caller.
553 The windowBits parameter is the base two logarithm of the maximum window
554 size (the size of the history buffer). It should be in the range 8..15 for
555 this version of the library (the value 16 will be allowed soon). The
556 default value is 15 if inflateInit is used instead. If a compressed stream
557 with a larger window size is given as input, inflate() will return with
558 the error code Z_DATA_ERROR instead of trying to allocate a larger window.
560 If next_out is not null, the library will use this buffer for the history
561 buffer; the buffer must either be large enough to hold the entire output
562 data, or have at least 1<<windowBits bytes. If next_out is null, the
563 library will allocate its own buffer (and leave next_out null). next_in
564 need not be provided here but must be provided by the application for the
565 next call of inflate().
567 If the history buffer is provided by the application, next_out must
568 never be changed by the application since the decompressor maintains
569 history information inside this buffer from call to call; the application
570 can only reset next_out to the beginning of the history buffer when
571 avail_out is zero and all output has been consumed.
573 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
574 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
575 windowBits < 8). msg is set to null if there is no error message.
576 inflateInit2 does not perform any decompression: this will be done by
580 extern int inflateSync OF((z_stream *strm));
582 Skips invalid compressed data until the special marker (see deflate()
583 above) can be found, or until all available input is skipped. No output
586 inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
587 if no more input was provided, Z_DATA_ERROR if no marker has been found,
588 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
589 case, the application may save the current current value of total_in which
590 indicates where valid compressed data was found. In the error case, the
591 application may repeatedly call inflateSync, providing more input each time,
592 until success or end of the input data.
595 extern int inflateReset OF((z_stream *strm));
597 This function is equivalent to inflateEnd followed by inflateInit,
598 but does not free and reallocate all the internal decompression state.
599 The stream will keep attributes that may have been set by inflateInit2.
601 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
602 stream state was inconsistent (such as zalloc or state being NULL).
605 extern int inflateIncomp OF((z_stream *strm));
607 This function adds the data at next_in (avail_in bytes) to the output
608 history without performing any output. There must be no pending output,
609 and the decompressor must be expecting to see the start of a block.
610 Calling this function is equivalent to decompressing a stored block
611 containing the data at next_in (except that the data is not output).
614 /* checksum functions */
617 This function is not related to compression but is exported
618 anyway because it might be useful in applications using the
622 extern uLong adler32 OF((uLong adler, Bytef *buf, uInt len));
625 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
626 return the updated checksum. If buf is NULL, this function returns
627 the required initial value for the checksum.
628 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
629 much faster. Usage example:
631 uLong adler = adler32(0L, Z_NULL, 0);
633 while (read_buffer(buffer, length) != EOF) {
634 adler = adler32(adler, buffer, length);
636 if (adler != original_adler) error();
640 struct internal_state {int dummy;}; /* hack for buggy compilers */