Annotation of sys/lib/libz/zlib.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: zlib.h,v 1.9 2005/07/20 15:56:46 millert Exp $ */
2: /* zlib.h -- interface of the 'zlib' general purpose compression library
3: version 1.2.3, July 18th, 2005
4:
5: Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
6:
7: This software is provided 'as-is', without any express or implied
8: warranty. In no event will the authors be held liable for any damages
9: arising from the use of this software.
10:
11: Permission is granted to anyone to use this software for any purpose,
12: including commercial applications, and to alter it and redistribute it
13: freely, subject to the following restrictions:
14:
15: 1. The origin of this software must not be misrepresented; you must not
16: claim that you wrote the original software. If you use this software
17: in a product, an acknowledgment in the product documentation would be
18: appreciated but is not required.
19: 2. Altered source versions must be plainly marked as such, and must not be
20: misrepresented as being the original software.
21: 3. This notice may not be removed or altered from any source distribution.
22:
23: Jean-loup Gailly Mark Adler
24: jloup@gzip.org madler@alumni.caltech.edu
25:
26:
27: The data format used by the zlib library is described by RFCs (Request for
28: Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
29: (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
30: */
31:
32: #ifndef ZLIB_H
33: #define ZLIB_H
34:
35: #include "zconf.h"
36:
37: #ifdef __cplusplus
38: extern "C" {
39: #endif
40:
41: #define ZLIB_VERSION "1.2.3"
42: #define ZLIB_VERNUM 0x1230
43:
44: /*
45: The 'zlib' compression library provides in-memory compression and
46: decompression functions, including integrity checks of the uncompressed
47: data. This version of the library supports only one compression method
48: (deflation) but other algorithms will be added later and will have the same
49: stream interface.
50:
51: Compression can be done in a single step if the buffers are large
52: enough (for example if an input file is mmap'ed), or can be done by
53: repeated calls of the compression function. In the latter case, the
54: application must provide more input and/or consume the output
55: (providing more output space) before each call.
56:
57: The compressed data format used by default by the in-memory functions is
58: the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
59: around a deflate stream, which is itself documented in RFC 1951.
60:
61: The library also supports reading and writing files in gzip (.gz) format
62: with an interface similar to that of stdio using the functions that start
63: with "gz". The gzip format is different from the zlib format. gzip is a
64: gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
65:
66: This library can optionally read and write gzip streams in memory as well.
67:
68: The zlib format was designed to be compact and fast for use in memory
69: and on communications channels. The gzip format was designed for single-
70: file compression on file systems, has a larger header than zlib to maintain
71: directory information, and uses a different, slower check method than zlib.
72:
73: The library does not install any signal handler. The decoder checks
74: the consistency of the compressed data, so the library should never
75: crash even in case of corrupted input.
76: */
77:
78: typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
79: typedef void (*free_func) OF((voidpf opaque, voidpf address));
80:
81: struct internal_state;
82:
83: typedef struct z_stream_s {
84: Bytef *next_in; /* next input byte */
85: uInt avail_in; /* number of bytes available at next_in */
86: z_off_t total_in; /* total nb of input bytes read so far */
87:
88: Bytef *next_out; /* next output byte should be put there */
89: uInt avail_out; /* remaining free space at next_out */
90: z_off_t total_out; /* total nb of bytes output so far */
91:
92: char *msg; /* last error message, NULL if no error */
93: struct internal_state FAR *state; /* not visible by applications */
94:
95: alloc_func zalloc; /* used to allocate the internal state */
96: free_func zfree; /* used to free the internal state */
97: voidpf opaque; /* private data object passed to zalloc and zfree */
98:
99: int data_type; /* best guess about the data type: binary or text */
100: uLong adler; /* adler32 value of the uncompressed data */
101: uLong reserved; /* reserved for future use */
102: } z_stream;
103:
104: typedef z_stream FAR *z_streamp;
105:
106: /*
107: gzip header information passed to and from zlib routines. See RFC 1952
108: for more details on the meanings of these fields.
109: */
110: typedef struct gz_header_s {
111: int text; /* true if compressed data believed to be text */
112: uLong time; /* modification time */
113: int xflags; /* extra flags (not used when writing a gzip file) */
114: int os; /* operating system */
115: Bytef *extra; /* pointer to extra field or Z_NULL if none */
116: uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
117: uInt extra_max; /* space at extra (only when reading header) */
118: Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
119: uInt name_max; /* space at name (only when reading header) */
120: Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
121: uInt comm_max; /* space at comment (only when reading header) */
122: int hcrc; /* true if there was or will be a header crc */
123: int done; /* true when done reading gzip header (not used
124: when writing a gzip file) */
125: } gz_header;
126:
127: typedef gz_header FAR *gz_headerp;
128:
129: /*
130: The application must update next_in and avail_in when avail_in has
131: dropped to zero. It must update next_out and avail_out when avail_out
132: has dropped to zero. The application must initialize zalloc, zfree and
133: opaque before calling the init function. All other fields are set by the
134: compression library and must not be updated by the application.
135:
136: The opaque value provided by the application will be passed as the first
137: parameter for calls of zalloc and zfree. This can be useful for custom
138: memory management. The compression library attaches no meaning to the
139: opaque value.
140:
141: zalloc must return Z_NULL if there is not enough memory for the object.
142: If zlib is used in a multi-threaded application, zalloc and zfree must be
143: thread safe.
144:
145: On 16-bit systems, the functions zalloc and zfree must be able to allocate
146: exactly 65536 bytes, but will not be required to allocate more than this
147: if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
148: pointers returned by zalloc for objects of exactly 65536 bytes *must*
149: have their offset normalized to zero. The default allocation function
150: provided by this library ensures this (see zutil.c). To reduce memory
151: requirements and avoid any allocation of 64K objects, at the expense of
152: compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
153:
154: The fields total_in and total_out can be used for statistics or
155: progress reports. After compression, total_in holds the total size of
156: the uncompressed data and may be saved for use in the decompressor
157: (particularly if the decompressor wants to decompress everything in
158: a single step).
159: */
160:
161: /* constants */
162:
163: #define Z_NO_FLUSH 0
164: #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
165: #define Z_SYNC_FLUSH 2
166: #define Z_FULL_FLUSH 3
167: #define Z_FINISH 4
168: #define Z_BLOCK 5
169: /* Allowed flush values; see deflate() and inflate() below for details */
170:
171: #define Z_OK 0
172: #define Z_STREAM_END 1
173: #define Z_NEED_DICT 2
174: #define Z_ERRNO (-1)
175: #define Z_STREAM_ERROR (-2)
176: #define Z_DATA_ERROR (-3)
177: #define Z_MEM_ERROR (-4)
178: #define Z_BUF_ERROR (-5)
179: #define Z_VERSION_ERROR (-6)
180: /* Return codes for the compression/decompression functions. Negative
181: * values are errors, positive values are used for special but normal events.
182: */
183:
184: #define Z_NO_COMPRESSION 0
185: #define Z_BEST_SPEED 1
186: #define Z_BEST_COMPRESSION 9
187: #define Z_DEFAULT_COMPRESSION (-1)
188: /* compression levels */
189:
190: #define Z_FILTERED 1
191: #define Z_HUFFMAN_ONLY 2
192: #define Z_RLE 3
193: #define Z_FIXED 4
194: #define Z_DEFAULT_STRATEGY 0
195: /* compression strategy; see deflateInit2() below for details */
196:
197: #define Z_BINARY 0
198: #define Z_TEXT 1
199: #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
200: #define Z_UNKNOWN 2
201: /* Possible values of the data_type field (though see inflate()) */
202:
203: #define Z_DEFLATED 8
204: /* The deflate compression method (the only one supported in this version) */
205:
206: #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
207:
208: #define zlib_version zlibVersion()
209: /* for compatibility with versions < 1.0.2 */
210:
211: /* basic functions */
212:
213: ZEXTERN const char * ZEXPORT zlibVersion OF((void));
214: /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
215: If the first character differs, the library code actually used is
216: not compatible with the zlib.h header file used by the application.
217: This check is automatically made by deflateInit and inflateInit.
218: */
219:
220: /*
221: ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
222:
223: Initializes the internal stream state for compression. The fields
224: zalloc, zfree and opaque must be initialized before by the caller.
225: If zalloc and zfree are set to Z_NULL, deflateInit updates them to
226: use default allocation functions.
227:
228: The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
229: 1 gives best speed, 9 gives best compression, 0 gives no compression at
230: all (the input data is simply copied a block at a time).
231: Z_DEFAULT_COMPRESSION requests a default compromise between speed and
232: compression (currently equivalent to level 6).
233:
234: deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
235: enough memory, Z_STREAM_ERROR if level is not a valid compression level,
236: Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
237: with the version assumed by the caller (ZLIB_VERSION).
238: msg is set to null if there is no error message. deflateInit does not
239: perform any compression: this will be done by deflate().
240: */
241:
242:
243: ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
244: /*
245: deflate compresses as much data as possible, and stops when the input
246: buffer becomes empty or the output buffer becomes full. It may introduce some
247: output latency (reading input without producing any output) except when
248: forced to flush.
249:
250: The detailed semantics are as follows. deflate performs one or both of the
251: following actions:
252:
253: - Compress more input starting at next_in and update next_in and avail_in
254: accordingly. If not all input can be processed (because there is not
255: enough room in the output buffer), next_in and avail_in are updated and
256: processing will resume at this point for the next call of deflate().
257:
258: - Provide more output starting at next_out and update next_out and avail_out
259: accordingly. This action is forced if the parameter flush is non zero.
260: Forcing flush frequently degrades the compression ratio, so this parameter
261: should be set only when necessary (in interactive applications).
262: Some output may be provided even if flush is not set.
263:
264: Before the call of deflate(), the application should ensure that at least
265: one of the actions is possible, by providing more input and/or consuming
266: more output, and updating avail_in or avail_out accordingly; avail_out
267: should never be zero before the call. The application can consume the
268: compressed output when it wants, for example when the output buffer is full
269: (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
270: and with zero avail_out, it must be called again after making room in the
271: output buffer because there might be more output pending.
272:
273: Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
274: decide how much data to accumualte before producing output, in order to
275: maximize compression.
276:
277: If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
278: flushed to the output buffer and the output is aligned on a byte boundary, so
279: that the decompressor can get all input data available so far. (In particular
280: avail_in is zero after the call if enough output space has been provided
281: before the call.) Flushing may degrade compression for some compression
282: algorithms and so it should be used only when necessary.
283:
284: If flush is set to Z_FULL_FLUSH, all output is flushed as with
285: Z_SYNC_FLUSH, and the compression state is reset so that decompression can
286: restart from this point if previous compressed data has been damaged or if
287: random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
288: compression.
289:
290: If deflate returns with avail_out == 0, this function must be called again
291: with the same value of the flush parameter and more output space (updated
292: avail_out), until the flush is complete (deflate returns with non-zero
293: avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
294: avail_out is greater than six to avoid repeated flush markers due to
295: avail_out == 0 on return.
296:
297: If the parameter flush is set to Z_FINISH, pending input is processed,
298: pending output is flushed and deflate returns with Z_STREAM_END if there
299: was enough output space; if deflate returns with Z_OK, this function must be
300: called again with Z_FINISH and more output space (updated avail_out) but no
301: more input data, until it returns with Z_STREAM_END or an error. After
302: deflate has returned Z_STREAM_END, the only possible operations on the
303: stream are deflateReset or deflateEnd.
304:
305: Z_FINISH can be used immediately after deflateInit if all the compression
306: is to be done in a single step. In this case, avail_out must be at least
307: the value returned by deflateBound (see below). If deflate does not return
308: Z_STREAM_END, then it must be called again as described above.
309:
310: deflate() sets strm->adler to the adler32 checksum of all input read
311: so far (that is, total_in bytes).
312:
313: deflate() may update strm->data_type if it can make a good guess about
314: the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
315: binary. This field is only for information purposes and does not affect
316: the compression algorithm in any manner.
317:
318: deflate() returns Z_OK if some progress has been made (more input
319: processed or more output produced), Z_STREAM_END if all input has been
320: consumed and all output has been produced (only when flush is set to
321: Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
322: if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
323: (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
324: fatal, and deflate() can be called again with more input and more output
325: space to continue compressing.
326: */
327:
328:
329: ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
330: /*
331: All dynamically allocated data structures for this stream are freed.
332: This function discards any unprocessed input and does not flush any
333: pending output.
334:
335: deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
336: stream state was inconsistent, Z_DATA_ERROR if the stream was freed
337: prematurely (some input or output was discarded). In the error case,
338: msg may be set but then points to a static string (which must not be
339: deallocated).
340: */
341:
342:
343: /*
344: ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
345:
346: Initializes the internal stream state for decompression. The fields
347: next_in, avail_in, zalloc, zfree and opaque must be initialized before by
348: the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
349: value depends on the compression method), inflateInit determines the
350: compression method from the zlib header and allocates all data structures
351: accordingly; otherwise the allocation will be deferred to the first call of
352: inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
353: use default allocation functions.
354:
355: inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
356: memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
357: version assumed by the caller. msg is set to null if there is no error
358: message. inflateInit does not perform any decompression apart from reading
359: the zlib header if present: this will be done by inflate(). (So next_in and
360: avail_in may be modified, but next_out and avail_out are unchanged.)
361: */
362:
363:
364: ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
365: /*
366: inflate decompresses as much data as possible, and stops when the input
367: buffer becomes empty or the output buffer becomes full. It may introduce
368: some output latency (reading input without producing any output) except when
369: forced to flush.
370:
371: The detailed semantics are as follows. inflate performs one or both of the
372: following actions:
373:
374: - Decompress more input starting at next_in and update next_in and avail_in
375: accordingly. If not all input can be processed (because there is not
376: enough room in the output buffer), next_in is updated and processing
377: will resume at this point for the next call of inflate().
378:
379: - Provide more output starting at next_out and update next_out and avail_out
380: accordingly. inflate() provides as much output as possible, until there
381: is no more input data or no more space in the output buffer (see below
382: about the flush parameter).
383:
384: Before the call of inflate(), the application should ensure that at least
385: one of the actions is possible, by providing more input and/or consuming
386: more output, and updating the next_* and avail_* values accordingly.
387: The application can consume the uncompressed output when it wants, for
388: example when the output buffer is full (avail_out == 0), or after each
389: call of inflate(). If inflate returns Z_OK and with zero avail_out, it
390: must be called again after making room in the output buffer because there
391: might be more output pending.
392:
393: The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
394: Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
395: output as possible to the output buffer. Z_BLOCK requests that inflate() stop
396: if and when it gets to the next deflate block boundary. When decoding the
397: zlib or gzip format, this will cause inflate() to return immediately after
398: the header and before the first block. When doing a raw inflate, inflate()
399: will go ahead and process the first block, and will return when it gets to
400: the end of that block, or when it runs out of data.
401:
402: The Z_BLOCK option assists in appending to or combining deflate streams.
403: Also to assist in this, on return inflate() will set strm->data_type to the
404: number of unused bits in the last byte taken from strm->next_in, plus 64
405: if inflate() is currently decoding the last block in the deflate stream,
406: plus 128 if inflate() returned immediately after decoding an end-of-block
407: code or decoding the complete header up to just before the first byte of the
408: deflate stream. The end-of-block will not be indicated until all of the
409: uncompressed data from that block has been written to strm->next_out. The
410: number of unused bits may in general be greater than seven, except when
411: bit 7 of data_type is set, in which case the number of unused bits will be
412: less than eight.
413:
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 approach
423: may be used for the single inflate() call.
424:
425: In this implementation, inflate() always flushes as much output as
426: possible to the output buffer, and always uses the faster approach on the
427: first call. So the only effect of the flush parameter in this implementation
428: is on the return value of inflate(), as noted below, or when it returns early
429: because Z_BLOCK is used.
430:
431: If a preset dictionary is needed after this call (see inflateSetDictionary
432: below), inflate sets strm->adler to the adler32 checksum of the dictionary
433: chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
434: strm->adler to the adler32 checksum of all output produced so far (that is,
435: total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
436: below. At the end of the stream, inflate() checks that its computed adler32
437: checksum is equal to that saved by the compressor and returns Z_STREAM_END
438: only if the checksum is correct.
439:
440: inflate() will decompress and check either zlib-wrapped or gzip-wrapped
441: deflate data. The header type is detected automatically. Any information
442: contained in the gzip header is not retained, so applications that need that
443: information should instead use raw inflate, see inflateInit2() below, or
444: inflateBack() and perform their own processing of the gzip header and
445: trailer.
446:
447: inflate() returns Z_OK if some progress has been made (more input processed
448: or more output produced), Z_STREAM_END if the end of the compressed data has
449: been reached and all uncompressed output has been produced, Z_NEED_DICT if a
450: preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
451: corrupted (input stream not conforming to the zlib format or incorrect check
452: value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
453: if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
454: Z_BUF_ERROR if no progress is possible or if there was not enough room in the
455: output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
456: inflate() can be called again with more input and more output space to
457: continue decompressing. If Z_DATA_ERROR is returned, the application may then
458: call inflateSync() to look for a good compression block if a partial recovery
459: of the data is desired.
460: */
461:
462:
463: ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
464: /*
465: All dynamically allocated data structures for this stream are freed.
466: This function discards any unprocessed input and does not flush any
467: pending output.
468:
469: inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
470: was inconsistent. In the error case, msg may be set but then points to a
471: static string (which must not be deallocated).
472: */
473:
474: /* Advanced functions */
475:
476: /*
477: The following functions are needed only in some special applications.
478: */
479:
480: /*
481: ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
482: int level,
483: int method,
484: int windowBits,
485: int memLevel,
486: int strategy));
487:
488: This is another version of deflateInit with more compression options. The
489: fields next_in, zalloc, zfree and opaque must be initialized before by
490: the caller.
491:
492: The method parameter is the compression method. It must be Z_DEFLATED in
493: this version of the library.
494:
495: The windowBits parameter is the base two logarithm of the window size
496: (the size of the history buffer). It should be in the range 8..15 for this
497: version of the library. Larger values of this parameter result in better
498: compression at the expense of memory usage. The default value is 15 if
499: deflateInit is used instead.
500:
501: windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
502: determines the window size. deflate() will then generate raw deflate data
503: with no zlib header or trailer, and will not compute an adler32 check value.
504:
505: windowBits can also be greater than 15 for optional gzip encoding. Add
506: 16 to windowBits to write a simple gzip header and trailer around the
507: compressed data instead of a zlib wrapper. The gzip header will have no
508: file name, no extra data, no comment, no modification time (set to zero),
509: no header crc, and the operating system will be set to 255 (unknown). If a
510: gzip stream is being written, strm->adler is a crc32 instead of an adler32.
511:
512: The memLevel parameter specifies how much memory should be allocated
513: for the internal compression state. memLevel=1 uses minimum memory but
514: is slow and reduces compression ratio; memLevel=9 uses maximum memory
515: for optimal speed. The default value is 8. See zconf.h for total memory
516: usage as a function of windowBits and memLevel.
517:
518: The strategy parameter is used to tune the compression algorithm. Use the
519: value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
520: filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
521: string match), or Z_RLE to limit match distances to one (run-length
522: encoding). Filtered data consists mostly of small values with a somewhat
523: random distribution. In this case, the compression algorithm is tuned to
524: compress them better. The effect of Z_FILTERED is to force more Huffman
525: coding and less string matching; it is somewhat intermediate between
526: Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
527: Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
528: parameter only affects the compression ratio but not the correctness of the
529: compressed output even if it is not set appropriately. Z_FIXED prevents the
530: use of dynamic Huffman codes, allowing for a simpler decoder for special
531: applications.
532:
533: deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
534: memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
535: method). msg is set to null if there is no error message. deflateInit2 does
536: not perform any compression: this will be done by deflate().
537: */
538:
539: ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
540: const Bytef *dictionary,
541: uInt dictLength));
542: /*
543: Initializes the compression dictionary from the given byte sequence
544: without producing any compressed output. This function must be called
545: immediately after deflateInit, deflateInit2 or deflateReset, before any
546: call of deflate. The compressor and decompressor must use exactly the same
547: dictionary (see inflateSetDictionary).
548:
549: The dictionary should consist of strings (byte sequences) that are likely
550: to be encountered later in the data to be compressed, with the most commonly
551: used strings preferably put towards the end of the dictionary. Using a
552: dictionary is most useful when the data to be compressed is short and can be
553: predicted with good accuracy; the data can then be compressed better than
554: with the default empty dictionary.
555:
556: Depending on the size of the compression data structures selected by
557: deflateInit or deflateInit2, a part of the dictionary may in effect be
558: discarded, for example if the dictionary is larger than the window size in
559: deflate or deflate2. Thus the strings most likely to be useful should be
560: put at the end of the dictionary, not at the front. In addition, the
561: current implementation of deflate will use at most the window size minus
562: 262 bytes of the provided dictionary.
563:
564: Upon return of this function, strm->adler is set to the adler32 value
565: of the dictionary; the decompressor may later use this value to determine
566: which dictionary has been used by the compressor. (The adler32 value
567: applies to the whole dictionary even if only a subset of the dictionary is
568: actually used by the compressor.) If a raw deflate was requested, then the
569: adler32 value is not computed and strm->adler is not set.
570:
571: deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
572: parameter is invalid (such as NULL dictionary) or the stream state is
573: inconsistent (for example if deflate has already been called for this stream
574: or if the compression method is bsort). deflateSetDictionary does not
575: perform any compression: this will be done by deflate().
576: */
577:
578: ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
579: z_streamp source));
580: /*
581: Sets the destination stream as a complete copy of the source stream.
582:
583: This function can be useful when several compression strategies will be
584: tried, for example when there are several ways of pre-processing the input
585: data with a filter. The streams that will be discarded should then be freed
586: by calling deflateEnd. Note that deflateCopy duplicates the internal
587: compression state which can be quite large, so this strategy is slow and
588: can consume lots of memory.
589:
590: deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
591: enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
592: (such as zalloc being NULL). msg is left unchanged in both source and
593: destination.
594: */
595:
596: ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
597: /*
598: This function is equivalent to deflateEnd followed by deflateInit,
599: but does not free and reallocate all the internal compression state.
600: The stream will keep the same compression level and any other attributes
601: that may have been set by deflateInit2.
602:
603: deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
604: stream state was inconsistent (such as zalloc or state being NULL).
605: */
606:
607: ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
608: int level,
609: int strategy));
610: /*
611: Dynamically update the compression level and compression strategy. The
612: interpretation of level and strategy is as in deflateInit2. This can be
613: used to switch between compression and straight copy of the input data, or
614: to switch to a different kind of input data requiring a different
615: strategy. If the compression level is changed, the input available so far
616: is compressed with the old level (and may be flushed); the new level will
617: take effect only at the next call of deflate().
618:
619: Before the call of deflateParams, the stream state must be set as for
620: a call of deflate(), since the currently available input may have to
621: be compressed and flushed. In particular, strm->avail_out must be non-zero.
622:
623: deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
624: stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
625: if strm->avail_out was zero.
626: */
627:
628: ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
629: int good_length,
630: int max_lazy,
631: int nice_length,
632: int max_chain));
633: /*
634: Fine tune deflate's internal compression parameters. This should only be
635: used by someone who understands the algorithm used by zlib's deflate for
636: searching for the best matching string, and even then only by the most
637: fanatic optimizer trying to squeeze out the last compressed bit for their
638: specific input data. Read the deflate.c source code for the meaning of the
639: max_lazy, good_length, nice_length, and max_chain parameters.
640:
641: deflateTune() can be called after deflateInit() or deflateInit2(), and
642: returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
643: */
644:
645: ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
646: uLong sourceLen));
647: /*
648: deflateBound() returns an upper bound on the compressed size after
649: deflation of sourceLen bytes. It must be called after deflateInit()
650: or deflateInit2(). This would be used to allocate an output buffer
651: for deflation in a single pass, and so would be called before deflate().
652: */
653:
654: ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
655: int bits,
656: int value));
657: /*
658: deflatePrime() inserts bits in the deflate output stream. The intent
659: is that this function is used to start off the deflate output with the
660: bits leftover from a previous deflate stream when appending to it. As such,
661: this function can only be used for raw deflate, and must be used before the
662: first deflate() call after a deflateInit2() or deflateReset(). bits must be
663: less than or equal to 16, and that many of the least significant bits of
664: value will be inserted in the output.
665:
666: deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
667: stream state was inconsistent.
668: */
669:
670: ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
671: gz_headerp head));
672: /*
673: deflateSetHeader() provides gzip header information for when a gzip
674: stream is requested by deflateInit2(). deflateSetHeader() may be called
675: after deflateInit2() or deflateReset() and before the first call of
676: deflate(). The text, time, os, extra field, name, and comment information
677: in the provided gz_header structure are written to the gzip header (xflag is
678: ignored -- the extra flags are set according to the compression level). The
679: caller must assure that, if not Z_NULL, name and comment are terminated with
680: a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
681: available there. If hcrc is true, a gzip header crc is included. Note that
682: the current versions of the command-line version of gzip (up through version
683: 1.3.x) do not support header crc's, and will report that it is a "multi-part
684: gzip file" and give up.
685:
686: If deflateSetHeader is not used, the default gzip header has text false,
687: the time set to zero, and os set to 255, with no extra, name, or comment
688: fields. The gzip header is returned to the default state by deflateReset().
689:
690: deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
691: stream state was inconsistent.
692: */
693:
694: /*
695: ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
696: int windowBits));
697:
698: This is another version of inflateInit with an extra parameter. The
699: fields next_in, avail_in, zalloc, zfree and opaque must be initialized
700: before by the caller.
701:
702: The windowBits parameter is the base two logarithm of the maximum window
703: size (the size of the history buffer). It should be in the range 8..15 for
704: this version of the library. The default value is 15 if inflateInit is used
705: instead. windowBits must be greater than or equal to the windowBits value
706: provided to deflateInit2() while compressing, or it must be equal to 15 if
707: deflateInit2() was not used. If a compressed stream with a larger window
708: size is given as input, inflate() will return with the error code
709: Z_DATA_ERROR instead of trying to allocate a larger window.
710:
711: windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
712: determines the window size. inflate() will then process raw deflate data,
713: not looking for a zlib or gzip header, not generating a check value, and not
714: looking for any check values for comparison at the end of the stream. This
715: is for use with other formats that use the deflate compressed data format
716: such as zip. Those formats provide their own check values. If a custom
717: format is developed using the raw deflate format for compressed data, it is
718: recommended that a check value such as an adler32 or a crc32 be applied to
719: the uncompressed data as is done in the zlib, gzip, and zip formats. For
720: most applications, the zlib format should be used as is. Note that comments
721: above on the use in deflateInit2() applies to the magnitude of windowBits.
722:
723: windowBits can also be greater than 15 for optional gzip decoding. Add
724: 32 to windowBits to enable zlib and gzip decoding with automatic header
725: detection, or add 16 to decode only the gzip format (the zlib format will
726: return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
727: a crc32 instead of an adler32.
728:
729: inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
730: memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
731: is set to null if there is no error message. inflateInit2 does not perform
732: any decompression apart from reading the zlib header if present: this will
733: be done by inflate(). (So next_in and avail_in may be modified, but next_out
734: and avail_out are unchanged.)
735: */
736:
737: ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
738: const Bytef *dictionary,
739: uInt dictLength));
740: /*
741: Initializes the decompression dictionary from the given uncompressed byte
742: sequence. This function must be called immediately after a call of inflate,
743: if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
744: can be determined from the adler32 value returned by that call of inflate.
745: The compressor and decompressor must use exactly the same dictionary (see
746: deflateSetDictionary). For raw inflate, this function can be called
747: immediately after inflateInit2() or inflateReset() and before any call of
748: inflate() to set the dictionary. The application must insure that the
749: dictionary that was used for compression is provided.
750:
751: inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
752: parameter is invalid (such as NULL dictionary) or the stream state is
753: inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
754: expected one (incorrect adler32 value). inflateSetDictionary does not
755: perform any decompression: this will be done by subsequent calls of
756: inflate().
757: */
758:
759: ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
760: /*
761: Skips invalid compressed data until a full flush point (see above the
762: description of deflate with Z_FULL_FLUSH) can be found, or until all
763: available input is skipped. No output is provided.
764:
765: inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
766: if no more input was provided, Z_DATA_ERROR if no flush point has been found,
767: or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
768: case, the application may save the current current value of total_in which
769: indicates where valid compressed data was found. In the error case, the
770: application may repeatedly call inflateSync, providing more input each time,
771: until success or end of the input data.
772: */
773:
774: ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
775: z_streamp source));
776: /*
777: Sets the destination stream as a complete copy of the source stream.
778:
779: This function can be useful when randomly accessing a large stream. The
780: first pass through the stream can periodically record the inflate state,
781: allowing restarting inflate at those points when randomly accessing the
782: stream.
783:
784: inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
785: enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
786: (such as zalloc being NULL). msg is left unchanged in both source and
787: destination.
788: */
789:
790: ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
791: /*
792: This function is equivalent to inflateEnd followed by inflateInit,
793: but does not free and reallocate all the internal decompression state.
794: The stream will keep attributes that may have been set by inflateInit2.
795:
796: inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
797: stream state was inconsistent (such as zalloc or state being NULL).
798: */
799:
800: ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
801: int bits,
802: int value));
803: /*
804: This function inserts bits in the inflate input stream. The intent is
805: that this function is used to start inflating at a bit position in the
806: middle of a byte. The provided bits will be used before any bytes are used
807: from next_in. This function should only be used with raw inflate, and
808: should be used before the first inflate() call after inflateInit2() or
809: inflateReset(). bits must be less than or equal to 16, and that many of the
810: least significant bits of value will be inserted in the input.
811:
812: inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
813: stream state was inconsistent.
814: */
815:
816: ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
817: gz_headerp head));
818: /*
819: inflateGetHeader() requests that gzip header information be stored in the
820: provided gz_header structure. inflateGetHeader() may be called after
821: inflateInit2() or inflateReset(), and before the first call of inflate().
822: As inflate() processes the gzip stream, head->done is zero until the header
823: is completed, at which time head->done is set to one. If a zlib stream is
824: being decoded, then head->done is set to -1 to indicate that there will be
825: no gzip header information forthcoming. Note that Z_BLOCK can be used to
826: force inflate() to return immediately after header processing is complete
827: and before any actual data is decompressed.
828:
829: The text, time, xflags, and os fields are filled in with the gzip header
830: contents. hcrc is set to true if there is a header CRC. (The header CRC
831: was valid if done is set to one.) If extra is not Z_NULL, then extra_max
832: contains the maximum number of bytes to write to extra. Once done is true,
833: extra_len contains the actual extra field length, and extra contains the
834: extra field, or that field truncated if extra_max is less than extra_len.
835: If name is not Z_NULL, then up to name_max characters are written there,
836: terminated with a zero unless the length is greater than name_max. If
837: comment is not Z_NULL, then up to comm_max characters are written there,
838: terminated with a zero unless the length is greater than comm_max. When
839: any of extra, name, or comment are not Z_NULL and the respective field is
840: not present in the header, then that field is set to Z_NULL to signal its
841: absence. This allows the use of deflateSetHeader() with the returned
842: structure to duplicate the header. However if those fields are set to
843: allocated memory, then the application will need to save those pointers
844: elsewhere so that they can be eventually freed.
845:
846: If inflateGetHeader is not used, then the header information is simply
847: discarded. The header is always checked for validity, including the header
848: CRC if present. inflateReset() will reset the process to discard the header
849: information. The application would need to call inflateGetHeader() again to
850: retrieve the header from the next gzip stream.
851:
852: inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
853: stream state was inconsistent.
854: */
855:
856: /*
857: ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
858: unsigned char FAR *window));
859:
860: Initialize the internal stream state for decompression using inflateBack()
861: calls. The fields zalloc, zfree and opaque in strm must be initialized
862: before the call. If zalloc and zfree are Z_NULL, then the default library-
863: derived memory allocation routines are used. windowBits is the base two
864: logarithm of the window size, in the range 8..15. window is a caller
865: supplied buffer of that size. Except for special applications where it is
866: assured that deflate was used with small window sizes, windowBits must be 15
867: and a 32K byte window must be supplied to be able to decompress general
868: deflate streams.
869:
870: See inflateBack() for the usage of these routines.
871:
872: inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
873: the paramaters are invalid, Z_MEM_ERROR if the internal state could not
874: be allocated, or Z_VERSION_ERROR if the version of the library does not
875: match the version of the header file.
876: */
877:
878: typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
879: typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
880:
881: ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
882: in_func in, void FAR *in_desc,
883: out_func out, void FAR *out_desc));
884: /*
885: inflateBack() does a raw inflate with a single call using a call-back
886: interface for input and output. This is more efficient than inflate() for
887: file i/o applications in that it avoids copying between the output and the
888: sliding window by simply making the window itself the output buffer. This
889: function trusts the application to not change the output buffer passed by
890: the output function, at least until inflateBack() returns.
891:
892: inflateBackInit() must be called first to allocate the internal state
893: and to initialize the state with the user-provided window buffer.
894: inflateBack() may then be used multiple times to inflate a complete, raw
895: deflate stream with each call. inflateBackEnd() is then called to free
896: the allocated state.
897:
898: A raw deflate stream is one with no zlib or gzip header or trailer.
899: This routine would normally be used in a utility that reads zip or gzip
900: files and writes out uncompressed files. The utility would decode the
901: header and process the trailer on its own, hence this routine expects
902: only the raw deflate stream to decompress. This is different from the
903: normal behavior of inflate(), which expects either a zlib or gzip header and
904: trailer around the deflate stream.
905:
906: inflateBack() uses two subroutines supplied by the caller that are then
907: called by inflateBack() for input and output. inflateBack() calls those
908: routines until it reads a complete deflate stream and writes out all of the
909: uncompressed data, or until it encounters an error. The function's
910: parameters and return types are defined above in the in_func and out_func
911: typedefs. inflateBack() will call in(in_desc, &buf) which should return the
912: number of bytes of provided input, and a pointer to that input in buf. If
913: there is no input available, in() must return zero--buf is ignored in that
914: case--and inflateBack() will return a buffer error. inflateBack() will call
915: out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
916: should return zero on success, or non-zero on failure. If out() returns
917: non-zero, inflateBack() will return with an error. Neither in() nor out()
918: are permitted to change the contents of the window provided to
919: inflateBackInit(), which is also the buffer that out() uses to write from.
920: The length written by out() will be at most the window size. Any non-zero
921: amount of input may be provided by in().
922:
923: For convenience, inflateBack() can be provided input on the first call by
924: setting strm->next_in and strm->avail_in. If that input is exhausted, then
925: in() will be called. Therefore strm->next_in must be initialized before
926: calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
927: immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
928: must also be initialized, and then if strm->avail_in is not zero, input will
929: initially be taken from strm->next_in[0 .. strm->avail_in - 1].
930:
931: The in_desc and out_desc parameters of inflateBack() is passed as the
932: first parameter of in() and out() respectively when they are called. These
933: descriptors can be optionally used to pass any information that the caller-
934: supplied in() and out() functions need to do their job.
935:
936: On return, inflateBack() will set strm->next_in and strm->avail_in to
937: pass back any unused input that was provided by the last in() call. The
938: return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
939: if in() or out() returned an error, Z_DATA_ERROR if there was a format
940: error in the deflate stream (in which case strm->msg is set to indicate the
941: nature of the error), or Z_STREAM_ERROR if the stream was not properly
942: initialized. In the case of Z_BUF_ERROR, an input or output error can be
943: distinguished using strm->next_in which will be Z_NULL only if in() returned
944: an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
945: out() returning non-zero. (in() will always be called before out(), so
946: strm->next_in is assured to be defined if out() returns non-zero.) Note
947: that inflateBack() cannot return Z_OK.
948: */
949:
950: ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
951: /*
952: All memory allocated by inflateBackInit() is freed.
953:
954: inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
955: state was inconsistent.
956: */
957:
958: ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
959: /* Return flags indicating compile-time options.
960:
961: Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
962: 1.0: size of uInt
963: 3.2: size of uLong
964: 5.4: size of voidpf (pointer)
965: 7.6: size of z_off_t
966:
967: Compiler, assembler, and debug options:
968: 8: DEBUG
969: 9: ASMV or ASMINF -- use ASM code
970: 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
971: 11: 0 (reserved)
972:
973: One-time table building (smaller code, but not thread-safe if true):
974: 12: BUILDFIXED -- build static block decoding tables when needed
975: 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
976: 14,15: 0 (reserved)
977:
978: Library content (indicates missing functionality):
979: 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
980: deflate code when not needed)
981: 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
982: and decode gzip streams (to avoid linking crc code)
983: 18-19: 0 (reserved)
984:
985: Operation variations (changes in library functionality):
986: 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
987: 21: FASTEST -- deflate algorithm with only one, lowest compression level
988: 22,23: 0 (reserved)
989:
990: The sprintf variant used by gzprintf (zero is best):
991: 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
992: 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
993: 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
994:
995: Remainder:
996: 27-31: 0 (reserved)
997: */
998:
999:
1000: /* utility functions */
1001:
1002: /*
1003: The following utility functions are implemented on top of the
1004: basic stream-oriented functions. To simplify the interface, some
1005: default options are assumed (compression level and memory usage,
1006: standard memory allocation functions). The source code of these
1007: utility functions can easily be modified if you need special options.
1008: */
1009:
1010: ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1011: const Bytef *source, uLong sourceLen));
1012: /*
1013: Compresses the source buffer into the destination buffer. sourceLen is
1014: the byte length of the source buffer. Upon entry, destLen is the total
1015: size of the destination buffer, which must be at least the value returned
1016: by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1017: compressed buffer.
1018: This function can be used to compress a whole file at once if the
1019: input file is mmap'ed.
1020: compress returns Z_OK if success, Z_MEM_ERROR if there was not
1021: enough memory, Z_BUF_ERROR if there was not enough room in the output
1022: buffer.
1023: */
1024:
1025: ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1026: const Bytef *source, uLong sourceLen,
1027: int level));
1028: /*
1029: Compresses the source buffer into the destination buffer. The level
1030: parameter has the same meaning as in deflateInit. sourceLen is the byte
1031: length of the source buffer. Upon entry, destLen is the total size of the
1032: destination buffer, which must be at least the value returned by
1033: compressBound(sourceLen). Upon exit, destLen is the actual size of the
1034: compressed buffer.
1035:
1036: compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1037: memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1038: Z_STREAM_ERROR if the level parameter is invalid.
1039: */
1040:
1041: ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1042: /*
1043: compressBound() returns an upper bound on the compressed size after
1044: compress() or compress2() on sourceLen bytes. It would be used before
1045: a compress() or compress2() call to allocate the destination buffer.
1046: */
1047:
1048: ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1049: const Bytef *source, uLong sourceLen));
1050: /*
1051: Decompresses the source buffer into the destination buffer. sourceLen is
1052: the byte length of the source buffer. Upon entry, destLen is the total
1053: size of the destination buffer, which must be large enough to hold the
1054: entire uncompressed data. (The size of the uncompressed data must have
1055: been saved previously by the compressor and transmitted to the decompressor
1056: by some mechanism outside the scope of this compression library.)
1057: Upon exit, destLen is the actual size of the compressed buffer.
1058: This function can be used to decompress a whole file at once if the
1059: input file is mmap'ed.
1060:
1061: uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1062: enough memory, Z_BUF_ERROR if there was not enough room in the output
1063: buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1064: */
1065:
1066:
1067: typedef voidp gzFile;
1068:
1069: ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1070: /*
1071: Opens a gzip (.gz) file for reading or writing. The mode parameter
1072: is as in fopen ("rb" or "wb") but can also include a compression level
1073: ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1074: Huffman only compression as in "wb1h", or 'R' for run-length encoding
1075: as in "wb1R". (See the description of deflateInit2 for more information
1076: about the strategy parameter.)
1077:
1078: gzopen can be used to read a file which is not in gzip format; in this
1079: case gzread will directly read from the file without decompression.
1080:
1081: gzopen returns NULL if the file could not be opened or if there was
1082: insufficient memory to allocate the (de)compression state; errno
1083: can be checked to distinguish the two cases (if errno is zero, the
1084: zlib error is Z_MEM_ERROR). */
1085:
1086: ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1087: /*
1088: gzdopen() associates a gzFile with the file descriptor fd. File
1089: descriptors are obtained from calls like open, dup, creat, pipe or
1090: fileno (in the file has been previously opened with fopen).
1091: The mode parameter is as in gzopen.
1092: The next call of gzclose on the returned gzFile will also close the
1093: file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1094: descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1095: gzdopen returns NULL if there was insufficient memory to allocate
1096: the (de)compression state.
1097: */
1098:
1099: ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1100: /*
1101: Dynamically update the compression level or strategy. See the description
1102: of deflateInit2 for the meaning of these parameters.
1103: gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1104: opened for writing.
1105: */
1106:
1107: ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1108: /*
1109: Reads the given number of uncompressed bytes from the compressed file.
1110: If the input file was not in gzip format, gzread copies the given number
1111: of bytes into the buffer.
1112: gzread returns the number of uncompressed bytes actually read (0 for
1113: end of file, -1 for error). */
1114:
1115: ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1116: voidpc buf, unsigned len));
1117: /*
1118: Writes the given number of uncompressed bytes into the compressed file.
1119: gzwrite returns the number of uncompressed bytes actually written
1120: (0 in case of error).
1121: */
1122:
1123: ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
1124: /*
1125: Converts, formats, and writes the args to the compressed file under
1126: control of the format string, as in fprintf. gzprintf returns the number of
1127: uncompressed bytes actually written (0 in case of error). The number of
1128: uncompressed bytes written is limited to 4095. The caller should assure that
1129: this limit is not exceeded. If it is exceeded, then gzprintf() will return
1130: return an error (0) with nothing written. In this case, there may also be a
1131: buffer overflow with unpredictable consequences, which is possible only if
1132: zlib was compiled with the insecure functions sprintf() or vsprintf()
1133: because the secure snprintf() or vsnprintf() functions were not available.
1134: */
1135:
1136: ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1137: /*
1138: Writes the given null-terminated string to the compressed file, excluding
1139: the terminating null character.
1140: gzputs returns the number of characters written, or -1 in case of error.
1141: */
1142:
1143: ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1144: /*
1145: Reads bytes from the compressed file until len-1 characters are read, or
1146: a newline character is read and transferred to buf, or an end-of-file
1147: condition is encountered. The string is then terminated with a null
1148: character.
1149: gzgets returns buf, or Z_NULL in case of error.
1150: */
1151:
1152: ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1153: /*
1154: Writes c, converted to an unsigned char, into the compressed file.
1155: gzputc returns the value that was written, or -1 in case of error.
1156: */
1157:
1158: ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1159: /*
1160: Reads one byte from the compressed file. gzgetc returns this byte
1161: or -1 in case of end of file or error.
1162: */
1163:
1164: ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1165: /*
1166: Push one character back onto the stream to be read again later.
1167: Only one character of push-back is allowed. gzungetc() returns the
1168: character pushed, or -1 on failure. gzungetc() will fail if a
1169: character has been pushed but not read yet, or if c is -1. The pushed
1170: character will be discarded if the stream is repositioned with gzseek()
1171: or gzrewind().
1172: */
1173:
1174: ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1175: /*
1176: Flushes all pending output into the compressed file. The parameter
1177: flush is as in the deflate() function. The return value is the zlib
1178: error number (see function gzerror below). gzflush returns Z_OK if
1179: the flush parameter is Z_FINISH and all output could be flushed.
1180: gzflush should be called only when strictly necessary because it can
1181: degrade compression.
1182: */
1183:
1184: ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1185: z_off_t offset, int whence));
1186: /*
1187: Sets the starting position for the next gzread or gzwrite on the
1188: given compressed file. The offset represents a number of bytes in the
1189: uncompressed data stream. The whence parameter is defined as in lseek(2);
1190: the value SEEK_END is not supported.
1191: If the file is opened for reading, this function is emulated but can be
1192: extremely slow. If the file is opened for writing, only forward seeks are
1193: supported; gzseek then compresses a sequence of zeroes up to the new
1194: starting position.
1195:
1196: gzseek returns the resulting offset location as measured in bytes from
1197: the beginning of the uncompressed stream, or -1 in case of error, in
1198: particular if the file is opened for writing and the new starting position
1199: would be before the current position.
1200: */
1201:
1202: ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1203: /*
1204: Rewinds the given file. This function is supported only for reading.
1205:
1206: gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1207: */
1208:
1209: ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1210: /*
1211: Returns the starting position for the next gzread or gzwrite on the
1212: given compressed file. This position represents a number of bytes in the
1213: uncompressed data stream.
1214:
1215: gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1216: */
1217:
1218: ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1219: /*
1220: Returns 1 when EOF has previously been detected reading the given
1221: input stream, otherwise zero.
1222: */
1223:
1224: ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1225: /*
1226: Returns 1 if file is being read directly without decompression, otherwise
1227: zero.
1228: */
1229:
1230: ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1231: /*
1232: Flushes all pending output if necessary, closes the compressed file
1233: and deallocates all the (de)compression state. The return value is the zlib
1234: error number (see function gzerror below).
1235: */
1236:
1237: ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1238: /*
1239: Returns the error message for the last error which occurred on the
1240: given compressed file. errnum is set to zlib error number. If an
1241: error occurred in the file system and not in the compression library,
1242: errnum is set to Z_ERRNO and the application may consult errno
1243: to get the exact error code.
1244: */
1245:
1246: ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1247: /*
1248: Clears the error and end-of-file flags for file. This is analogous to the
1249: clearerr() function in stdio. This is useful for continuing to read a gzip
1250: file that is being written concurrently.
1251: */
1252:
1253: /* checksum functions */
1254:
1255: /*
1256: These functions are not related to compression but are exported
1257: anyway because they might be useful in applications using the
1258: compression library.
1259: */
1260:
1261: ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1262: /*
1263: Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1264: return the updated checksum. If buf is NULL, this function returns
1265: the required initial value for the checksum.
1266: An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1267: much faster. Usage example:
1268:
1269: uLong adler = adler32(0L, Z_NULL, 0);
1270:
1271: while (read_buffer(buffer, length) != EOF) {
1272: adler = adler32(adler, buffer, length);
1273: }
1274: if (adler != original_adler) error();
1275: */
1276:
1277: ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1278: z_off_t len2));
1279: /*
1280: Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1281: and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1282: each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1283: seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1284: */
1285:
1286: ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1287: /*
1288: Update a running CRC-32 with the bytes buf[0..len-1] and return the
1289: updated CRC-32. If buf is NULL, this function returns the required initial
1290: value for the for the crc. Pre- and post-conditioning (one's complement) is
1291: performed within this function so it shouldn't be done by the application.
1292: Usage example:
1293:
1294: uLong crc = crc32(0L, Z_NULL, 0);
1295:
1296: while (read_buffer(buffer, length) != EOF) {
1297: crc = crc32(crc, buffer, length);
1298: }
1299: if (crc != original_crc) error();
1300: */
1301:
1302: ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1303:
1304: /*
1305: Combine two CRC-32 check values into one. For two sequences of bytes,
1306: seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1307: calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1308: check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1309: len2.
1310: */
1311:
1312:
1313: /* various hacks, don't look :) */
1314:
1315: /* deflateInit and inflateInit are macros to allow checking the zlib version
1316: * and the compiler's view of z_stream:
1317: */
1318: ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1319: const char *version, int stream_size));
1320: ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1321: const char *version, int stream_size));
1322: ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1323: int windowBits, int memLevel,
1324: int strategy, const char *version,
1325: int stream_size));
1326: ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1327: const char *version, int stream_size));
1328: ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1329: unsigned char FAR *window,
1330: const char *version,
1331: int stream_size));
1332: #define deflateInit(strm, level) \
1333: deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1334: #define inflateInit(strm) \
1335: inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1336: #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1337: deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1338: (strategy), ZLIB_VERSION, sizeof(z_stream))
1339: #define inflateInit2(strm, windowBits) \
1340: inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1341: #define inflateBackInit(strm, windowBits, window) \
1342: inflateBackInit_((strm), (windowBits), (window), \
1343: ZLIB_VERSION, sizeof(z_stream))
1344:
1345:
1346: #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1347: struct internal_state {int dummy;}; /* hack for buggy compilers */
1348: #endif
1349:
1350: ZEXTERN const char * ZEXPORT zError OF((int));
1351: ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1352: ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1353:
1354: #ifdef __cplusplus
1355: }
1356: #endif
1357:
1358: #endif /* ZLIB_H */
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