zlib (1.3)
1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.3, August 18th, 2023
3
4 Copyright (C) 1995-2023 Jean-loup Gailly and Mark Adler
5
6 This software is provided 'as-is', without any express or implied
7 warranty. In no event will the authors be held liable for any damages
8 arising from the use of this software.
9
10 Permission is granted to anyone to use this software for any purpose,
11 including commercial applications, and to alter it and redistribute it
12 freely, subject to the following restrictions:
13
14 1. The origin of this software must not be misrepresented; you must not
15 claim that you wrote the original software. If you use this software
16 in a product, an acknowledgment in the product documentation would be
17 appreciated but is not required.
18 2. Altered source versions must be plainly marked as such, and must not be
19 misrepresented as being the original software.
20 3. This notice may not be removed or altered from any source distribution.
21
22 Jean-loup Gailly Mark Adler
23 jloup@gzip.org madler@alumni.caltech.edu
24
25
26 The data format used by the zlib library is described by RFCs (Request for
27 Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
28 (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
29 */
30
31 #ifndef ZLIB_H
32 #define ZLIB_H
33
34 #include "zconf.h"
35
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
39
40 #define ZLIB_VERSION "1.3"
41 #define ZLIB_VERNUM 0x1300
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 3
44 #define ZLIB_VER_REVISION 0
45 #define ZLIB_VER_SUBREVISION 0
46
47 /*
48 The 'zlib' compression library provides in-memory compression and
49 decompression functions, including integrity checks of the uncompressed data.
50 This version of the library supports only one compression method (deflation)
51 but other algorithms will be added later and will have the same stream
52 interface.
53
54 Compression can be done in a single step if the buffers are large enough,
55 or can be done by repeated calls of the compression function. In the latter
56 case, the application must provide more input and/or consume the output
57 (providing more output space) before each call.
58
59 The compressed data format used by default by the in-memory functions is
60 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
61 around a deflate stream, which is itself documented in RFC 1951.
62
63 The library also supports reading and writing files in gzip (.gz) format
64 with an interface similar to that of stdio using the functions that start
65 with "gz". The gzip format is different from the zlib format. gzip is a
66 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
67
68 This library can optionally read and write gzip and raw deflate streams in
69 memory as well.
70
71 The zlib format was designed to be compact and fast for use in memory
72 and on communications channels. The gzip format was designed for single-
73 file compression on file systems, has a larger header than zlib to maintain
74 directory information, and uses a different, slower check method than zlib.
75
76 The library does not install any signal handler. The decoder checks
77 the consistency of the compressed data, so the library should never crash
78 even in the case of corrupted input.
79 */
80
81 typedef voidpf (*alloc_func)(voidpf opaque, uInt items, uInt size);
82 typedef void (*free_func)(voidpf opaque, voidpf address);
83
84 struct internal_state;
85
86 typedef struct z_stream_s {
87 z_const Bytef *next_in; /* next input byte */
88 uInt avail_in; /* number of bytes available at next_in */
89 uLong total_in; /* total number of input bytes read so far */
90
91 Bytef *next_out; /* next output byte will go here */
92 uInt avail_out; /* remaining free space at next_out */
93 uLong total_out; /* total number of bytes output so far */
94
95 z_const char *msg; /* last error message, NULL if no error */
96 struct internal_state FAR *state; /* not visible by applications */
97
98 alloc_func zalloc; /* used to allocate the internal state */
99 free_func zfree; /* used to free the internal state */
100 voidpf opaque; /* private data object passed to zalloc and zfree */
101
102 int data_type; /* best guess about the data type: binary or text
103 for deflate, or the decoding state for inflate */
104 uLong adler; /* Adler-32 or CRC-32 value of the uncompressed data */
105 uLong reserved; /* reserved for future use */
106 } z_stream;
107
108 typedef z_stream FAR *z_streamp;
109
110 /*
111 gzip header information passed to and from zlib routines. See RFC 1952
112 for more details on the meanings of these fields.
113 */
114 typedef struct gz_header_s {
115 int text; /* true if compressed data believed to be text */
116 uLong time; /* modification time */
117 int xflags; /* extra flags (not used when writing a gzip file) */
118 int os; /* operating system */
119 Bytef *extra; /* pointer to extra field or Z_NULL if none */
120 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
121 uInt extra_max; /* space at extra (only when reading header) */
122 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
123 uInt name_max; /* space at name (only when reading header) */
124 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
125 uInt comm_max; /* space at comment (only when reading header) */
126 int hcrc; /* true if there was or will be a header crc */
127 int done; /* true when done reading gzip header (not used
128 when writing a gzip file) */
129 } gz_header;
130
131 typedef gz_header FAR *gz_headerp;
132
133 /*
134 The application must update next_in and avail_in when avail_in has dropped
135 to zero. It must update next_out and avail_out when avail_out has dropped
136 to zero. The application must initialize zalloc, zfree and opaque before
137 calling the init function. All other fields are set by the compression
138 library and must not be updated by the application.
139
140 The opaque value provided by the application will be passed as the first
141 parameter for calls of zalloc and zfree. This can be useful for custom
142 memory management. The compression library attaches no meaning to the
143 opaque value.
144
145 zalloc must return Z_NULL if there is not enough memory for the object.
146 If zlib is used in a multi-threaded application, zalloc and zfree must be
147 thread safe. In that case, zlib is thread-safe. When zalloc and zfree are
148 Z_NULL on entry to the initialization function, they are set to internal
149 routines that use the standard library functions malloc() and free().
150
151 On 16-bit systems, the functions zalloc and zfree must be able to allocate
152 exactly 65536 bytes, but will not be required to allocate more than this if
153 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
154 returned by zalloc for objects of exactly 65536 bytes *must* have their
155 offset normalized to zero. The default allocation function provided by this
156 library ensures this (see zutil.c). To reduce memory requirements and avoid
157 any allocation of 64K objects, at the expense of compression ratio, compile
158 the library with -DMAX_WBITS=14 (see zconf.h).
159
160 The fields total_in and total_out can be used for statistics or progress
161 reports. After compression, total_in holds the total size of the
162 uncompressed data and may be saved for use by the decompressor (particularly
163 if the decompressor wants to decompress everything in a single step).
164 */
165
166 /* constants */
167
168 #define Z_NO_FLUSH 0
169 #define Z_PARTIAL_FLUSH 1
170 #define Z_SYNC_FLUSH 2
171 #define Z_FULL_FLUSH 3
172 #define Z_FINISH 4
173 #define Z_BLOCK 5
174 #define Z_TREES 6
175 /* Allowed flush values; see deflate() and inflate() below for details */
176
177 #define Z_OK 0
178 #define Z_STREAM_END 1
179 #define Z_NEED_DICT 2
180 #define Z_ERRNO (-1)
181 #define Z_STREAM_ERROR (-2)
182 #define Z_DATA_ERROR (-3)
183 #define Z_MEM_ERROR (-4)
184 #define Z_BUF_ERROR (-5)
185 #define Z_VERSION_ERROR (-6)
186 /* Return codes for the compression/decompression functions. Negative values
187 * are errors, positive values are used for special but normal events.
188 */
189
190 #define Z_NO_COMPRESSION 0
191 #define Z_BEST_SPEED 1
192 #define Z_BEST_COMPRESSION 9
193 #define Z_DEFAULT_COMPRESSION (-1)
194 /* compression levels */
195
196 #define Z_FILTERED 1
197 #define Z_HUFFMAN_ONLY 2
198 #define Z_RLE 3
199 #define Z_FIXED 4
200 #define Z_DEFAULT_STRATEGY 0
201 /* compression strategy; see deflateInit2() below for details */
202
203 #define Z_BINARY 0
204 #define Z_TEXT 1
205 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
206 #define Z_UNKNOWN 2
207 /* Possible values of the data_type field for deflate() */
208
209 #define Z_DEFLATED 8
210 /* The deflate compression method (the only one supported in this version) */
211
212 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
213
214 #define zlib_version zlibVersion()
215 /* for compatibility with versions < 1.0.2 */
216
217
218 /* basic functions */
219
220 ZEXTERN const char * ZEXPORT zlibVersion(void);
221 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
222 If the first character differs, the library code actually used is not
223 compatible with the zlib.h header file used by the application. This check
224 is automatically made by deflateInit and inflateInit.
225 */
226
227 /*
228 ZEXTERN int ZEXPORT deflateInit(z_streamp strm, int level);
229
230 Initializes the internal stream state for compression. The fields
231 zalloc, zfree and opaque must be initialized before by the caller. If
232 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
233 allocation functions. total_in, total_out, adler, and msg are initialized.
234
235 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
236 1 gives best speed, 9 gives best compression, 0 gives no compression at all
237 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
238 requests a default compromise between speed and compression (currently
239 equivalent to level 6).
240
241 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
242 memory, Z_STREAM_ERROR if level is not a valid compression level, or
243 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
244 with the version assumed by the caller (ZLIB_VERSION). msg is set to null
245 if there is no error message. deflateInit does not perform any compression:
246 this will be done by deflate().
247 */
248
249
250 ZEXTERN int ZEXPORT deflate(z_streamp strm, int flush);
251 /*
252 deflate compresses as much data as possible, and stops when the input
253 buffer becomes empty or the output buffer becomes full. It may introduce
254 some output latency (reading input without producing any output) except when
255 forced to flush.
256
257 The detailed semantics are as follows. deflate performs one or both of the
258 following actions:
259
260 - Compress more input starting at next_in and update next_in and avail_in
261 accordingly. If not all input can be processed (because there is not
262 enough room in the output buffer), next_in and avail_in are updated and
263 processing will resume at this point for the next call of deflate().
264
265 - Generate more output starting at next_out and update next_out and avail_out
266 accordingly. This action is forced if the parameter flush is non zero.
267 Forcing flush frequently degrades the compression ratio, so this parameter
268 should be set only when necessary. Some output may be provided even if
269 flush is zero.
270
271 Before the call of deflate(), the application should ensure that at least
272 one of the actions is possible, by providing more input and/or consuming more
273 output, and updating avail_in or avail_out accordingly; avail_out should
274 never be zero before the call. The application can consume the compressed
275 output when it wants, for example when the output buffer is full (avail_out
276 == 0), or after each call of deflate(). If deflate returns Z_OK and with
277 zero avail_out, it must be called again after making room in the output
278 buffer because there might be more output pending. See deflatePending(),
279 which can be used if desired to determine whether or not there is more output
280 in that case.
281
282 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
283 decide how much data to accumulate before producing output, in order to
284 maximize compression.
285
286 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
287 flushed to the output buffer and the output is aligned on a byte boundary, so
288 that the decompressor can get all input data available so far. (In
289 particular avail_in is zero after the call if enough output space has been
290 provided before the call.) Flushing may degrade compression for some
291 compression algorithms and so it should be used only when necessary. This
292 completes the current deflate block and follows it with an empty stored block
293 that is three bits plus filler bits to the next byte, followed by four bytes
294 (00 00 ff ff).
295
296 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
297 output buffer, but the output is not aligned to a byte boundary. All of the
298 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
299 This completes the current deflate block and follows it with an empty fixed
300 codes block that is 10 bits long. This assures that enough bytes are output
301 in order for the decompressor to finish the block before the empty fixed
302 codes block.
303
304 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
305 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
306 seven bits of the current block are held to be written as the next byte after
307 the next deflate block is completed. In this case, the decompressor may not
308 be provided enough bits at this point in order to complete decompression of
309 the data provided so far to the compressor. It may need to wait for the next
310 block to be emitted. This is for advanced applications that need to control
311 the emission of deflate blocks.
312
313 If flush is set to Z_FULL_FLUSH, all output is flushed as with
314 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
315 restart from this point if previous compressed data has been damaged or if
316 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
317 compression.
318
319 If deflate returns with avail_out == 0, this function must be called again
320 with the same value of the flush parameter and more output space (updated
321 avail_out), until the flush is complete (deflate returns with non-zero
322 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
323 avail_out is greater than six when the flush marker begins, in order to avoid
324 repeated flush markers upon calling deflate() again when avail_out == 0.
325
326 If the parameter flush is set to Z_FINISH, pending input is processed,
327 pending output is flushed and deflate returns with Z_STREAM_END if there was
328 enough output space. If deflate returns with Z_OK or Z_BUF_ERROR, this
329 function must be called again with Z_FINISH and more output space (updated
330 avail_out) but no more input data, until it returns with Z_STREAM_END or an
331 error. After deflate has returned Z_STREAM_END, the only possible operations
332 on the stream are deflateReset or deflateEnd.
333
334 Z_FINISH can be used in the first deflate call after deflateInit if all the
335 compression is to be done in a single step. In order to complete in one
336 call, avail_out must be at least the value returned by deflateBound (see
337 below). Then deflate is guaranteed to return Z_STREAM_END. If not enough
338 output space is provided, deflate will not return Z_STREAM_END, and it must
339 be called again as described above.
340
341 deflate() sets strm->adler to the Adler-32 checksum of all input read
342 so far (that is, total_in bytes). If a gzip stream is being generated, then
343 strm->adler will be the CRC-32 checksum of the input read so far. (See
344 deflateInit2 below.)
345
346 deflate() may update strm->data_type if it can make a good guess about
347 the input data type (Z_BINARY or Z_TEXT). If in doubt, the data is
348 considered binary. This field is only for information purposes and does not
349 affect the compression algorithm in any manner.
350
351 deflate() returns Z_OK if some progress has been made (more input
352 processed or more output produced), Z_STREAM_END if all input has been
353 consumed and all output has been produced (only when flush is set to
354 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
355 if next_in or next_out was Z_NULL or the state was inadvertently written over
356 by the application), or Z_BUF_ERROR if no progress is possible (for example
357 avail_in or avail_out was zero). Note that Z_BUF_ERROR is not fatal, and
358 deflate() can be called again with more input and more output space to
359 continue compressing.
360 */
361
362
363 ZEXTERN int ZEXPORT deflateEnd(z_streamp strm);
364 /*
365 All dynamically allocated data structures for this stream are freed.
366 This function discards any unprocessed input and does not flush any pending
367 output.
368
369 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
370 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
371 prematurely (some input or output was discarded). In the error case, msg
372 may be set but then points to a static string (which must not be
373 deallocated).
374 */
375
376
377 /*
378 ZEXTERN int ZEXPORT inflateInit(z_streamp strm);
379
380 Initializes the internal stream state for decompression. The fields
381 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
382 the caller. In the current version of inflate, the provided input is not
383 read or consumed. The allocation of a sliding window will be deferred to
384 the first call of inflate (if the decompression does not complete on the
385 first call). If zalloc and zfree are set to Z_NULL, inflateInit updates
386 them to use default allocation functions. total_in, total_out, adler, and
387 msg are initialized.
388
389 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
390 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
391 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
392 invalid, such as a null pointer to the structure. msg is set to null if
393 there is no error message. inflateInit does not perform any decompression.
394 Actual decompression will be done by inflate(). So next_in, and avail_in,
395 next_out, and avail_out are unused and unchanged. The current
396 implementation of inflateInit() does not process any header information --
397 that is deferred until inflate() is called.
398 */
399
400
401 ZEXTERN int ZEXPORT inflate(z_streamp strm, int flush);
402 /*
403 inflate decompresses as much data as possible, and stops when the input
404 buffer becomes empty or the output buffer becomes full. It may introduce
405 some output latency (reading input without producing any output) except when
406 forced to flush.
407
408 The detailed semantics are as follows. inflate performs one or both of the
409 following actions:
410
411 - Decompress more input starting at next_in and update next_in and avail_in
412 accordingly. If not all input can be processed (because there is not
413 enough room in the output buffer), then next_in and avail_in are updated
414 accordingly, and processing will resume at this point for the next call of
415 inflate().
416
417 - Generate more output starting at next_out and update next_out and avail_out
418 accordingly. inflate() provides as much output as possible, until there is
419 no more input data or no more space in the output buffer (see below about
420 the flush parameter).
421
422 Before the call of inflate(), the application should ensure that at least
423 one of the actions is possible, by providing more input and/or consuming more
424 output, and updating the next_* and avail_* values accordingly. If the
425 caller of inflate() does not provide both available input and available
426 output space, it is possible that there will be no progress made. The
427 application can consume the uncompressed output when it wants, for example
428 when the output buffer is full (avail_out == 0), or after each call of
429 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
430 called again after making room in the output buffer because there might be
431 more output pending.
432
433 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
434 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
435 output as possible to the output buffer. Z_BLOCK requests that inflate()
436 stop if and when it gets to the next deflate block boundary. When decoding
437 the zlib or gzip format, this will cause inflate() to return immediately
438 after the header and before the first block. When doing a raw inflate,
439 inflate() will go ahead and process the first block, and will return when it
440 gets to the end of that block, or when it runs out of data.
441
442 The Z_BLOCK option assists in appending to or combining deflate streams.
443 To assist in this, on return inflate() always sets strm->data_type to the
444 number of unused bits in the last byte taken from strm->next_in, plus 64 if
445 inflate() is currently decoding the last block in the deflate stream, plus
446 128 if inflate() returned immediately after decoding an end-of-block code or
447 decoding the complete header up to just before the first byte of the deflate
448 stream. The end-of-block will not be indicated until all of the uncompressed
449 data from that block has been written to strm->next_out. The number of
450 unused bits may in general be greater than seven, except when bit 7 of
451 data_type is set, in which case the number of unused bits will be less than
452 eight. data_type is set as noted here every time inflate() returns for all
453 flush options, and so can be used to determine the amount of currently
454 consumed input in bits.
455
456 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
457 end of each deflate block header is reached, before any actual data in that
458 block is decoded. This allows the caller to determine the length of the
459 deflate block header for later use in random access within a deflate block.
460 256 is added to the value of strm->data_type when inflate() returns
461 immediately after reaching the end of the deflate block header.
462
463 inflate() should normally be called until it returns Z_STREAM_END or an
464 error. However if all decompression is to be performed in a single step (a
465 single call of inflate), the parameter flush should be set to Z_FINISH. In
466 this case all pending input is processed and all pending output is flushed;
467 avail_out must be large enough to hold all of the uncompressed data for the
468 operation to complete. (The size of the uncompressed data may have been
469 saved by the compressor for this purpose.) The use of Z_FINISH is not
470 required to perform an inflation in one step. However it may be used to
471 inform inflate that a faster approach can be used for the single inflate()
472 call. Z_FINISH also informs inflate to not maintain a sliding window if the
473 stream completes, which reduces inflate's memory footprint. If the stream
474 does not complete, either because not all of the stream is provided or not
475 enough output space is provided, then a sliding window will be allocated and
476 inflate() can be called again to continue the operation as if Z_NO_FLUSH had
477 been used.
478
479 In this implementation, inflate() always flushes as much output as
480 possible to the output buffer, and always uses the faster approach on the
481 first call. So the effects of the flush parameter in this implementation are
482 on the return value of inflate() as noted below, when inflate() returns early
483 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
484 memory for a sliding window when Z_FINISH is used.
485
486 If a preset dictionary is needed after this call (see inflateSetDictionary
487 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
488 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
489 strm->adler to the Adler-32 checksum of all output produced so far (that is,
490 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
491 below. At the end of the stream, inflate() checks that its computed Adler-32
492 checksum is equal to that saved by the compressor and returns Z_STREAM_END
493 only if the checksum is correct.
494
495 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
496 deflate data. The header type is detected automatically, if requested when
497 initializing with inflateInit2(). Any information contained in the gzip
498 header is not retained unless inflateGetHeader() is used. When processing
499 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
500 produced so far. The CRC-32 is checked against the gzip trailer, as is the
501 uncompressed length, modulo 2^32.
502
503 inflate() returns Z_OK if some progress has been made (more input processed
504 or more output produced), Z_STREAM_END if the end of the compressed data has
505 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
506 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
507 corrupted (input stream not conforming to the zlib format or incorrect check
508 value, in which case strm->msg points to a string with a more specific
509 error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
510 next_in or next_out was Z_NULL, or the state was inadvertently written over
511 by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
512 if no progress was possible or if there was not enough room in the output
513 buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
514 inflate() can be called again with more input and more output space to
515 continue decompressing. If Z_DATA_ERROR is returned, the application may
516 then call inflateSync() to look for a good compression block if a partial
517 recovery of the data is to be attempted.
518 */
519
520
521 ZEXTERN int ZEXPORT inflateEnd(z_streamp strm);
522 /*
523 All dynamically allocated data structures for this stream are freed.
524 This function discards any unprocessed input and does not flush any pending
525 output.
526
527 inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
528 was inconsistent.
529 */
530
531
532 /* Advanced functions */
533
534 /*
535 The following functions are needed only in some special applications.
536 */
537
538 /*
539 ZEXTERN int ZEXPORT deflateInit2(z_streamp strm,
540 int level,
541 int method,
542 int windowBits,
543 int memLevel,
544 int strategy);
545
546 This is another version of deflateInit with more compression options. The
547 fields zalloc, zfree and opaque must be initialized before by the caller.
548
549 The method parameter is the compression method. It must be Z_DEFLATED in
550 this version of the library.
551
552 The windowBits parameter is the base two logarithm of the window size
553 (the size of the history buffer). It should be in the range 8..15 for this
554 version of the library. Larger values of this parameter result in better
555 compression at the expense of memory usage. The default value is 15 if
556 deflateInit is used instead.
557
558 For the current implementation of deflate(), a windowBits value of 8 (a
559 window size of 256 bytes) is not supported. As a result, a request for 8
560 will result in 9 (a 512-byte window). In that case, providing 8 to
561 inflateInit2() will result in an error when the zlib header with 9 is
562 checked against the initialization of inflate(). The remedy is to not use 8
563 with deflateInit2() with this initialization, or at least in that case use 9
564 with inflateInit2().
565
566 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
567 determines the window size. deflate() will then generate raw deflate data
568 with no zlib header or trailer, and will not compute a check value.
569
570 windowBits can also be greater than 15 for optional gzip encoding. Add
571 16 to windowBits to write a simple gzip header and trailer around the
572 compressed data instead of a zlib wrapper. The gzip header will have no
573 file name, no extra data, no comment, no modification time (set to zero), no
574 header crc, and the operating system will be set to the appropriate value,
575 if the operating system was determined at compile time. If a gzip stream is
576 being written, strm->adler is a CRC-32 instead of an Adler-32.
577
578 For raw deflate or gzip encoding, a request for a 256-byte window is
579 rejected as invalid, since only the zlib header provides a means of
580 transmitting the window size to the decompressor.
581
582 The memLevel parameter specifies how much memory should be allocated
583 for the internal compression state. memLevel=1 uses minimum memory but is
584 slow and reduces compression ratio; memLevel=9 uses maximum memory for
585 optimal speed. The default value is 8. See zconf.h for total memory usage
586 as a function of windowBits and memLevel.
587
588 The strategy parameter is used to tune the compression algorithm. Use the
589 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
590 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
591 string match), or Z_RLE to limit match distances to one (run-length
592 encoding). Filtered data consists mostly of small values with a somewhat
593 random distribution. In this case, the compression algorithm is tuned to
594 compress them better. The effect of Z_FILTERED is to force more Huffman
595 coding and less string matching; it is somewhat intermediate between
596 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
597 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
598 strategy parameter only affects the compression ratio but not the
599 correctness of the compressed output even if it is not set appropriately.
600 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
601 decoder for special applications.
602
603 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
604 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
605 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
606 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
607 set to null if there is no error message. deflateInit2 does not perform any
608 compression: this will be done by deflate().
609 */
610
611 ZEXTERN int ZEXPORT deflateSetDictionary(z_streamp strm,
612 const Bytef *dictionary,
613 uInt dictLength);
614 /*
615 Initializes the compression dictionary from the given byte sequence
616 without producing any compressed output. When using the zlib format, this
617 function must be called immediately after deflateInit, deflateInit2 or
618 deflateReset, and before any call of deflate. When doing raw deflate, this
619 function must be called either before any call of deflate, or immediately
620 after the completion of a deflate block, i.e. after all input has been
621 consumed and all output has been delivered when using any of the flush
622 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
623 compressor and decompressor must use exactly the same dictionary (see
624 inflateSetDictionary).
625
626 The dictionary should consist of strings (byte sequences) that are likely
627 to be encountered later in the data to be compressed, with the most commonly
628 used strings preferably put towards the end of the dictionary. Using a
629 dictionary is most useful when the data to be compressed is short and can be
630 predicted with good accuracy; the data can then be compressed better than
631 with the default empty dictionary.
632
633 Depending on the size of the compression data structures selected by
634 deflateInit or deflateInit2, a part of the dictionary may in effect be
635 discarded, for example if the dictionary is larger than the window size
636 provided in deflateInit or deflateInit2. Thus the strings most likely to be
637 useful should be put at the end of the dictionary, not at the front. In
638 addition, the current implementation of deflate will use at most the window
639 size minus 262 bytes of the provided dictionary.
640
641 Upon return of this function, strm->adler is set to the Adler-32 value
642 of the dictionary; the decompressor may later use this value to determine
643 which dictionary has been used by the compressor. (The Adler-32 value
644 applies to the whole dictionary even if only a subset of the dictionary is
645 actually used by the compressor.) If a raw deflate was requested, then the
646 Adler-32 value is not computed and strm->adler is not set.
647
648 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
649 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
650 inconsistent (for example if deflate has already been called for this stream
651 or if not at a block boundary for raw deflate). deflateSetDictionary does
652 not perform any compression: this will be done by deflate().
653 */
654
655 ZEXTERN int ZEXPORT deflateGetDictionary(z_streamp strm,
656 Bytef *dictionary,
657 uInt *dictLength);
658 /*
659 Returns the sliding dictionary being maintained by deflate. dictLength is
660 set to the number of bytes in the dictionary, and that many bytes are copied
661 to dictionary. dictionary must have enough space, where 32768 bytes is
662 always enough. If deflateGetDictionary() is called with dictionary equal to
663 Z_NULL, then only the dictionary length is returned, and nothing is copied.
664 Similarly, if dictLength is Z_NULL, then it is not set.
665
666 deflateGetDictionary() may return a length less than the window size, even
667 when more than the window size in input has been provided. It may return up
668 to 258 bytes less in that case, due to how zlib's implementation of deflate
669 manages the sliding window and lookahead for matches, where matches can be
670 up to 258 bytes long. If the application needs the last window-size bytes of
671 input, then that would need to be saved by the application outside of zlib.
672
673 deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
674 stream state is inconsistent.
675 */
676
677 ZEXTERN int ZEXPORT deflateCopy(z_streamp dest,
678 z_streamp source);
679 /*
680 Sets the destination stream as a complete copy of the source stream.
681
682 This function can be useful when several compression strategies will be
683 tried, for example when there are several ways of pre-processing the input
684 data with a filter. The streams that will be discarded should then be freed
685 by calling deflateEnd. Note that deflateCopy duplicates the internal
686 compression state which can be quite large, so this strategy is slow and can
687 consume lots of memory.
688
689 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
690 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
691 (such as zalloc being Z_NULL). msg is left unchanged in both source and
692 destination.
693 */
694
695 ZEXTERN int ZEXPORT deflateReset(z_streamp strm);
696 /*
697 This function is equivalent to deflateEnd followed by deflateInit, but
698 does not free and reallocate the internal compression state. The stream
699 will leave the compression level and any other attributes that may have been
700 set unchanged. total_in, total_out, adler, and msg are initialized.
701
702 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
703 stream state was inconsistent (such as zalloc or state being Z_NULL).
704 */
705
706 ZEXTERN int ZEXPORT deflateParams(z_streamp strm,
707 int level,
708 int strategy);
709 /*
710 Dynamically update the compression level and compression strategy. The
711 interpretation of level and strategy is as in deflateInit2(). This can be
712 used to switch between compression and straight copy of the input data, or
713 to switch to a different kind of input data requiring a different strategy.
714 If the compression approach (which is a function of the level) or the
715 strategy is changed, and if there have been any deflate() calls since the
716 state was initialized or reset, then the input available so far is
717 compressed with the old level and strategy using deflate(strm, Z_BLOCK).
718 There are three approaches for the compression levels 0, 1..3, and 4..9
719 respectively. The new level and strategy will take effect at the next call
720 of deflate().
721
722 If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
723 not have enough output space to complete, then the parameter change will not
724 take effect. In this case, deflateParams() can be called again with the
725 same parameters and more output space to try again.
726
727 In order to assure a change in the parameters on the first try, the
728 deflate stream should be flushed using deflate() with Z_BLOCK or other flush
729 request until strm.avail_out is not zero, before calling deflateParams().
730 Then no more input data should be provided before the deflateParams() call.
731 If this is done, the old level and strategy will be applied to the data
732 compressed before deflateParams(), and the new level and strategy will be
733 applied to the data compressed after deflateParams().
734
735 deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
736 state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
737 there was not enough output space to complete the compression of the
738 available input data before a change in the strategy or approach. Note that
739 in the case of a Z_BUF_ERROR, the parameters are not changed. A return
740 value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
741 retried with more output space.
742 */
743
744 ZEXTERN int ZEXPORT deflateTune(z_streamp strm,
745 int good_length,
746 int max_lazy,
747 int nice_length,
748 int max_chain);
749 /*
750 Fine tune deflate's internal compression parameters. This should only be
751 used by someone who understands the algorithm used by zlib's deflate for
752 searching for the best matching string, and even then only by the most
753 fanatic optimizer trying to squeeze out the last compressed bit for their
754 specific input data. Read the deflate.c source code for the meaning of the
755 max_lazy, good_length, nice_length, and max_chain parameters.
756
757 deflateTune() can be called after deflateInit() or deflateInit2(), and
758 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
759 */
760
761 ZEXTERN uLong ZEXPORT deflateBound(z_streamp strm,
762 uLong sourceLen);
763 /*
764 deflateBound() returns an upper bound on the compressed size after
765 deflation of sourceLen bytes. It must be called after deflateInit() or
766 deflateInit2(), and after deflateSetHeader(), if used. This would be used
767 to allocate an output buffer for deflation in a single pass, and so would be
768 called before deflate(). If that first deflate() call is provided the
769 sourceLen input bytes, an output buffer allocated to the size returned by
770 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
771 to return Z_STREAM_END. Note that it is possible for the compressed size to
772 be larger than the value returned by deflateBound() if flush options other
773 than Z_FINISH or Z_NO_FLUSH are used.
774 */
775
776 ZEXTERN int ZEXPORT deflatePending(z_streamp strm,
777 unsigned *pending,
778 int *bits);
779 /*
780 deflatePending() returns the number of bytes and bits of output that have
781 been generated, but not yet provided in the available output. The bytes not
782 provided would be due to the available output space having being consumed.
783 The number of bits of output not provided are between 0 and 7, where they
784 await more bits to join them in order to fill out a full byte. If pending
785 or bits are Z_NULL, then those values are not set.
786
787 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
788 stream state was inconsistent.
789 */
790
791 ZEXTERN int ZEXPORT deflatePrime(z_streamp strm,
792 int bits,
793 int value);
794 /*
795 deflatePrime() inserts bits in the deflate output stream. The intent
796 is that this function is used to start off the deflate output with the bits
797 leftover from a previous deflate stream when appending to it. As such, this
798 function can only be used for raw deflate, and must be used before the first
799 deflate() call after a deflateInit2() or deflateReset(). bits must be less
800 than or equal to 16, and that many of the least significant bits of value
801 will be inserted in the output.
802
803 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
804 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
805 source stream state was inconsistent.
806 */
807
808 ZEXTERN int ZEXPORT deflateSetHeader(z_streamp strm,
809 gz_headerp head);
810 /*
811 deflateSetHeader() provides gzip header information for when a gzip
812 stream is requested by deflateInit2(). deflateSetHeader() may be called
813 after deflateInit2() or deflateReset() and before the first call of
814 deflate(). The text, time, os, extra field, name, and comment information
815 in the provided gz_header structure are written to the gzip header (xflag is
816 ignored -- the extra flags are set according to the compression level). The
817 caller must assure that, if not Z_NULL, name and comment are terminated with
818 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
819 available there. If hcrc is true, a gzip header crc is included. Note that
820 the current versions of the command-line version of gzip (up through version
821 1.3.x) do not support header crc's, and will report that it is a "multi-part
822 gzip file" and give up.
823
824 If deflateSetHeader is not used, the default gzip header has text false,
825 the time set to zero, and os set to the current operating system, with no
826 extra, name, or comment fields. The gzip header is returned to the default
827 state by deflateReset().
828
829 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
830 stream state was inconsistent.
831 */
832
833 /*
834 ZEXTERN int ZEXPORT inflateInit2(z_streamp strm,
835 int windowBits);
836
837 This is another version of inflateInit with an extra parameter. The
838 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
839 before by the caller.
840
841 The windowBits parameter is the base two logarithm of the maximum window
842 size (the size of the history buffer). It should be in the range 8..15 for
843 this version of the library. The default value is 15 if inflateInit is used
844 instead. windowBits must be greater than or equal to the windowBits value
845 provided to deflateInit2() while compressing, or it must be equal to 15 if
846 deflateInit2() was not used. If a compressed stream with a larger window
847 size is given as input, inflate() will return with the error code
848 Z_DATA_ERROR instead of trying to allocate a larger window.
849
850 windowBits can also be zero to request that inflate use the window size in
851 the zlib header of the compressed stream.
852
853 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
854 determines the window size. inflate() will then process raw deflate data,
855 not looking for a zlib or gzip header, not generating a check value, and not
856 looking for any check values for comparison at the end of the stream. This
857 is for use with other formats that use the deflate compressed data format
858 such as zip. Those formats provide their own check values. If a custom
859 format is developed using the raw deflate format for compressed data, it is
860 recommended that a check value such as an Adler-32 or a CRC-32 be applied to
861 the uncompressed data as is done in the zlib, gzip, and zip formats. For
862 most applications, the zlib format should be used as is. Note that comments
863 above on the use in deflateInit2() applies to the magnitude of windowBits.
864
865 windowBits can also be greater than 15 for optional gzip decoding. Add
866 32 to windowBits to enable zlib and gzip decoding with automatic header
867 detection, or add 16 to decode only the gzip format (the zlib format will
868 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
869 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see
870 below), inflate() will *not* automatically decode concatenated gzip members.
871 inflate() will return Z_STREAM_END at the end of the gzip member. The state
872 would need to be reset to continue decoding a subsequent gzip member. This
873 *must* be done if there is more data after a gzip member, in order for the
874 decompression to be compliant with the gzip standard (RFC 1952).
875
876 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
877 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
878 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
879 invalid, such as a null pointer to the structure. msg is set to null if
880 there is no error message. inflateInit2 does not perform any decompression
881 apart from possibly reading the zlib header if present: actual decompression
882 will be done by inflate(). (So next_in and avail_in may be modified, but
883 next_out and avail_out are unused and unchanged.) The current implementation
884 of inflateInit2() does not process any header information -- that is
885 deferred until inflate() is called.
886 */
887
888 ZEXTERN int ZEXPORT inflateSetDictionary(z_streamp strm,
889 const Bytef *dictionary,
890 uInt dictLength);
891 /*
892 Initializes the decompression dictionary from the given uncompressed byte
893 sequence. This function must be called immediately after a call of inflate,
894 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
895 can be determined from the Adler-32 value returned by that call of inflate.
896 The compressor and decompressor must use exactly the same dictionary (see
897 deflateSetDictionary). For raw inflate, this function can be called at any
898 time to set the dictionary. If the provided dictionary is smaller than the
899 window and there is already data in the window, then the provided dictionary
900 will amend what's there. The application must insure that the dictionary
901 that was used for compression is provided.
902
903 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
904 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
905 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
906 expected one (incorrect Adler-32 value). inflateSetDictionary does not
907 perform any decompression: this will be done by subsequent calls of
908 inflate().
909 */
910
911 ZEXTERN int ZEXPORT inflateGetDictionary(z_streamp strm,
912 Bytef *dictionary,
913 uInt *dictLength);
914 /*
915 Returns the sliding dictionary being maintained by inflate. dictLength is
916 set to the number of bytes in the dictionary, and that many bytes are copied
917 to dictionary. dictionary must have enough space, where 32768 bytes is
918 always enough. If inflateGetDictionary() is called with dictionary equal to
919 Z_NULL, then only the dictionary length is returned, and nothing is copied.
920 Similarly, if dictLength is Z_NULL, then it is not set.
921
922 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
923 stream state is inconsistent.
924 */
925
926 ZEXTERN int ZEXPORT inflateSync(z_streamp strm);
927 /*
928 Skips invalid compressed data until a possible full flush point (see above
929 for the description of deflate with Z_FULL_FLUSH) can be found, or until all
930 available input is skipped. No output is provided.
931
932 inflateSync searches for a 00 00 FF FF pattern in the compressed data.
933 All full flush points have this pattern, but not all occurrences of this
934 pattern are full flush points.
935
936 inflateSync returns Z_OK if a possible full flush point has been found,
937 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
938 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
939 In the success case, the application may save the current current value of
940 total_in which indicates where valid compressed data was found. In the
941 error case, the application may repeatedly call inflateSync, providing more
942 input each time, until success or end of the input data.
943 */
944
945 ZEXTERN int ZEXPORT inflateCopy(z_streamp dest,
946 z_streamp source);
947 /*
948 Sets the destination stream as a complete copy of the source stream.
949
950 This function can be useful when randomly accessing a large stream. The
951 first pass through the stream can periodically record the inflate state,
952 allowing restarting inflate at those points when randomly accessing the
953 stream.
954
955 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
956 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
957 (such as zalloc being Z_NULL). msg is left unchanged in both source and
958 destination.
959 */
960
961 ZEXTERN int ZEXPORT inflateReset(z_streamp strm);
962 /*
963 This function is equivalent to inflateEnd followed by inflateInit,
964 but does not free and reallocate the internal decompression state. The
965 stream will keep attributes that may have been set by inflateInit2.
966 total_in, total_out, adler, and msg are initialized.
967
968 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
969 stream state was inconsistent (such as zalloc or state being Z_NULL).
970 */
971
972 ZEXTERN int ZEXPORT inflateReset2(z_streamp strm,
973 int windowBits);
974 /*
975 This function is the same as inflateReset, but it also permits changing
976 the wrap and window size requests. The windowBits parameter is interpreted
977 the same as it is for inflateInit2. If the window size is changed, then the
978 memory allocated for the window is freed, and the window will be reallocated
979 by inflate() if needed.
980
981 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
982 stream state was inconsistent (such as zalloc or state being Z_NULL), or if
983 the windowBits parameter is invalid.
984 */
985
986 ZEXTERN int ZEXPORT inflatePrime(z_streamp strm,
987 int bits,
988 int value);
989 /*
990 This function inserts bits in the inflate input stream. The intent is
991 that this function is used to start inflating at a bit position in the
992 middle of a byte. The provided bits will be used before any bytes are used
993 from next_in. This function should only be used with raw inflate, and
994 should be used before the first inflate() call after inflateInit2() or
995 inflateReset(). bits must be less than or equal to 16, and that many of the
996 least significant bits of value will be inserted in the input.
997
998 If bits is negative, then the input stream bit buffer is emptied. Then
999 inflatePrime() can be called again to put bits in the buffer. This is used
1000 to clear out bits leftover after feeding inflate a block description prior
1001 to feeding inflate codes.
1002
1003 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1004 stream state was inconsistent.
1005 */
1006
1007 ZEXTERN long ZEXPORT inflateMark(z_streamp strm);
1008 /*
1009 This function returns two values, one in the lower 16 bits of the return
1010 value, and the other in the remaining upper bits, obtained by shifting the
1011 return value down 16 bits. If the upper value is -1 and the lower value is
1012 zero, then inflate() is currently decoding information outside of a block.
1013 If the upper value is -1 and the lower value is non-zero, then inflate is in
1014 the middle of a stored block, with the lower value equaling the number of
1015 bytes from the input remaining to copy. If the upper value is not -1, then
1016 it is the number of bits back from the current bit position in the input of
1017 the code (literal or length/distance pair) currently being processed. In
1018 that case the lower value is the number of bytes already emitted for that
1019 code.
1020
1021 A code is being processed if inflate is waiting for more input to complete
1022 decoding of the code, or if it has completed decoding but is waiting for
1023 more output space to write the literal or match data.
1024
1025 inflateMark() is used to mark locations in the input data for random
1026 access, which may be at bit positions, and to note those cases where the
1027 output of a code may span boundaries of random access blocks. The current
1028 location in the input stream can be determined from avail_in and data_type
1029 as noted in the description for the Z_BLOCK flush parameter for inflate.
1030
1031 inflateMark returns the value noted above, or -65536 if the provided
1032 source stream state was inconsistent.
1033 */
1034
1035 ZEXTERN int ZEXPORT inflateGetHeader(z_streamp strm,
1036 gz_headerp head);
1037 /*
1038 inflateGetHeader() requests that gzip header information be stored in the
1039 provided gz_header structure. inflateGetHeader() may be called after
1040 inflateInit2() or inflateReset(), and before the first call of inflate().
1041 As inflate() processes the gzip stream, head->done is zero until the header
1042 is completed, at which time head->done is set to one. If a zlib stream is
1043 being decoded, then head->done is set to -1 to indicate that there will be
1044 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
1045 used to force inflate() to return immediately after header processing is
1046 complete and before any actual data is decompressed.
1047
1048 The text, time, xflags, and os fields are filled in with the gzip header
1049 contents. hcrc is set to true if there is a header CRC. (The header CRC
1050 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1051 contains the maximum number of bytes to write to extra. Once done is true,
1052 extra_len contains the actual extra field length, and extra contains the
1053 extra field, or that field truncated if extra_max is less than extra_len.
1054 If name is not Z_NULL, then up to name_max characters are written there,
1055 terminated with a zero unless the length is greater than name_max. If
1056 comment is not Z_NULL, then up to comm_max characters are written there,
1057 terminated with a zero unless the length is greater than comm_max. When any
1058 of extra, name, or comment are not Z_NULL and the respective field is not
1059 present in the header, then that field is set to Z_NULL to signal its
1060 absence. This allows the use of deflateSetHeader() with the returned
1061 structure to duplicate the header. However if those fields are set to
1062 allocated memory, then the application will need to save those pointers
1063 elsewhere so that they can be eventually freed.
1064
1065 If inflateGetHeader is not used, then the header information is simply
1066 discarded. The header is always checked for validity, including the header
1067 CRC if present. inflateReset() will reset the process to discard the header
1068 information. The application would need to call inflateGetHeader() again to
1069 retrieve the header from the next gzip stream.
1070
1071 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1072 stream state was inconsistent.
1073 */
1074
1075 /*
1076 ZEXTERN int ZEXPORT inflateBackInit(z_streamp strm, int windowBits,
1077 unsigned char FAR *window);
1078
1079 Initialize the internal stream state for decompression using inflateBack()
1080 calls. The fields zalloc, zfree and opaque in strm must be initialized
1081 before the call. If zalloc and zfree are Z_NULL, then the default library-
1082 derived memory allocation routines are used. windowBits is the base two
1083 logarithm of the window size, in the range 8..15. window is a caller
1084 supplied buffer of that size. Except for special applications where it is
1085 assured that deflate was used with small window sizes, windowBits must be 15
1086 and a 32K byte window must be supplied to be able to decompress general
1087 deflate streams.
1088
1089 See inflateBack() for the usage of these routines.
1090
1091 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1092 the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1093 allocated, or Z_VERSION_ERROR if the version of the library does not match
1094 the version of the header file.
1095 */
1096
1097 typedef unsigned (*in_func)(void FAR *,
1098 z_const unsigned char FAR * FAR *);
1099 typedef int (*out_func)(void FAR *, unsigned char FAR *, unsigned);
1100
1101 ZEXTERN int ZEXPORT inflateBack(z_streamp strm,
1102 in_func in, void FAR *in_desc,
1103 out_func out, void FAR *out_desc);
1104 /*
1105 inflateBack() does a raw inflate with a single call using a call-back
1106 interface for input and output. This is potentially more efficient than
1107 inflate() for file i/o applications, in that it avoids copying between the
1108 output and the sliding window by simply making the window itself the output
1109 buffer. inflate() can be faster on modern CPUs when used with large
1110 buffers. inflateBack() trusts the application to not change the output
1111 buffer passed by the output function, at least until inflateBack() returns.
1112
1113 inflateBackInit() must be called first to allocate the internal state
1114 and to initialize the state with the user-provided window buffer.
1115 inflateBack() may then be used multiple times to inflate a complete, raw
1116 deflate stream with each call. inflateBackEnd() is then called to free the
1117 allocated state.
1118
1119 A raw deflate stream is one with no zlib or gzip header or trailer.
1120 This routine would normally be used in a utility that reads zip or gzip
1121 files and writes out uncompressed files. The utility would decode the
1122 header and process the trailer on its own, hence this routine expects only
1123 the raw deflate stream to decompress. This is different from the default
1124 behavior of inflate(), which expects a zlib header and trailer around the
1125 deflate stream.
1126
1127 inflateBack() uses two subroutines supplied by the caller that are then
1128 called by inflateBack() for input and output. inflateBack() calls those
1129 routines until it reads a complete deflate stream and writes out all of the
1130 uncompressed data, or until it encounters an error. The function's
1131 parameters and return types are defined above in the in_func and out_func
1132 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1133 number of bytes of provided input, and a pointer to that input in buf. If
1134 there is no input available, in() must return zero -- buf is ignored in that
1135 case -- and inflateBack() will return a buffer error. inflateBack() will
1136 call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1137 out() should return zero on success, or non-zero on failure. If out()
1138 returns non-zero, inflateBack() will return with an error. Neither in() nor
1139 out() are permitted to change the contents of the window provided to
1140 inflateBackInit(), which is also the buffer that out() uses to write from.
1141 The length written by out() will be at most the window size. Any non-zero
1142 amount of input may be provided by in().
1143
1144 For convenience, inflateBack() can be provided input on the first call by
1145 setting strm->next_in and strm->avail_in. If that input is exhausted, then
1146 in() will be called. Therefore strm->next_in must be initialized before
1147 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1148 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1149 must also be initialized, and then if strm->avail_in is not zero, input will
1150 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1151
1152 The in_desc and out_desc parameters of inflateBack() is passed as the
1153 first parameter of in() and out() respectively when they are called. These
1154 descriptors can be optionally used to pass any information that the caller-
1155 supplied in() and out() functions need to do their job.
1156
1157 On return, inflateBack() will set strm->next_in and strm->avail_in to
1158 pass back any unused input that was provided by the last in() call. The
1159 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1160 if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1161 in the deflate stream (in which case strm->msg is set to indicate the nature
1162 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1163 In the case of Z_BUF_ERROR, an input or output error can be distinguished
1164 using strm->next_in which will be Z_NULL only if in() returned an error. If
1165 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1166 non-zero. (in() will always be called before out(), so strm->next_in is
1167 assured to be defined if out() returns non-zero.) Note that inflateBack()
1168 cannot return Z_OK.
1169 */
1170
1171 ZEXTERN int ZEXPORT inflateBackEnd(z_streamp strm);
1172 /*
1173 All memory allocated by inflateBackInit() is freed.
1174
1175 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1176 state was inconsistent.
1177 */
1178
1179 ZEXTERN uLong ZEXPORT zlibCompileFlags(void);
1180 /* Return flags indicating compile-time options.
1181
1182 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1183 1.0: size of uInt
1184 3.2: size of uLong
1185 5.4: size of voidpf (pointer)
1186 7.6: size of z_off_t
1187
1188 Compiler, assembler, and debug options:
1189 8: ZLIB_DEBUG
1190 9: ASMV or ASMINF -- use ASM code
1191 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1192 11: 0 (reserved)
1193
1194 One-time table building (smaller code, but not thread-safe if true):
1195 12: BUILDFIXED -- build static block decoding tables when needed
1196 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1197 14,15: 0 (reserved)
1198
1199 Library content (indicates missing functionality):
1200 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1201 deflate code when not needed)
1202 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1203 and decode gzip streams (to avoid linking crc code)
1204 18-19: 0 (reserved)
1205
1206 Operation variations (changes in library functionality):
1207 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1208 21: FASTEST -- deflate algorithm with only one, lowest compression level
1209 22,23: 0 (reserved)
1210
1211 The sprintf variant used by gzprintf (zero is best):
1212 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1213 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1214 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1215
1216 Remainder:
1217 27-31: 0 (reserved)
1218 */
1219
1220 #ifndef Z_SOLO
1221
1222 /* utility functions */
1223
1224 /*
1225 The following utility functions are implemented on top of the basic
1226 stream-oriented functions. To simplify the interface, some default options
1227 are assumed (compression level and memory usage, standard memory allocation
1228 functions). The source code of these utility functions can be modified if
1229 you need special options.
1230 */
1231
1232 ZEXTERN int ZEXPORT compress(Bytef *dest, uLongf *destLen,
1233 const Bytef *source, uLong sourceLen);
1234 /*
1235 Compresses the source buffer into the destination buffer. sourceLen is
1236 the byte length of the source buffer. Upon entry, destLen is the total size
1237 of the destination buffer, which must be at least the value returned by
1238 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1239 compressed data. compress() is equivalent to compress2() with a level
1240 parameter of Z_DEFAULT_COMPRESSION.
1241
1242 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1243 enough memory, Z_BUF_ERROR if there was not enough room in the output
1244 buffer.
1245 */
1246
1247 ZEXTERN int ZEXPORT compress2(Bytef *dest, uLongf *destLen,
1248 const Bytef *source, uLong sourceLen,
1249 int level);
1250 /*
1251 Compresses the source buffer into the destination buffer. The level
1252 parameter has the same meaning as in deflateInit. sourceLen is the byte
1253 length of the source buffer. Upon entry, destLen is the total size of the
1254 destination buffer, which must be at least the value returned by
1255 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1256 compressed data.
1257
1258 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1259 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1260 Z_STREAM_ERROR if the level parameter is invalid.
1261 */
1262
1263 ZEXTERN uLong ZEXPORT compressBound(uLong sourceLen);
1264 /*
1265 compressBound() returns an upper bound on the compressed size after
1266 compress() or compress2() on sourceLen bytes. It would be used before a
1267 compress() or compress2() call to allocate the destination buffer.
1268 */
1269
1270 ZEXTERN int ZEXPORT uncompress(Bytef *dest, uLongf *destLen,
1271 const Bytef *source, uLong sourceLen);
1272 /*
1273 Decompresses the source buffer into the destination buffer. sourceLen is
1274 the byte length of the source buffer. Upon entry, destLen is the total size
1275 of the destination buffer, which must be large enough to hold the entire
1276 uncompressed data. (The size of the uncompressed data must have been saved
1277 previously by the compressor and transmitted to the decompressor by some
1278 mechanism outside the scope of this compression library.) Upon exit, destLen
1279 is the actual size of the uncompressed data.
1280
1281 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1282 enough memory, Z_BUF_ERROR if there was not enough room in the output
1283 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1284 the case where there is not enough room, uncompress() will fill the output
1285 buffer with the uncompressed data up to that point.
1286 */
1287
1288 ZEXTERN int ZEXPORT uncompress2(Bytef *dest, uLongf *destLen,
1289 const Bytef *source, uLong *sourceLen);
1290 /*
1291 Same as uncompress, except that sourceLen is a pointer, where the
1292 length of the source is *sourceLen. On return, *sourceLen is the number of
1293 source bytes consumed.
1294 */
1295
1296 /* gzip file access functions */
1297
1298 /*
1299 This library supports reading and writing files in gzip (.gz) format with
1300 an interface similar to that of stdio, using the functions that start with
1301 "gz". The gzip format is different from the zlib format. gzip is a gzip
1302 wrapper, documented in RFC 1952, wrapped around a deflate stream.
1303 */
1304
1305 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1306
1307 /*
1308 ZEXTERN gzFile ZEXPORT gzopen(const char *path, const char *mode);
1309
1310 Open the gzip (.gz) file at path for reading and decompressing, or
1311 compressing and writing. The mode parameter is as in fopen ("rb" or "wb")
1312 but can also include a compression level ("wb9") or a strategy: 'f' for
1313 filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
1314 'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
1315 as in "wb9F". (See the description of deflateInit2 for more information
1316 about the strategy parameter.) 'T' will request transparent writing or
1317 appending with no compression and not using the gzip format.
1318
1319 "a" can be used instead of "w" to request that the gzip stream that will
1320 be written be appended to the file. "+" will result in an error, since
1321 reading and writing to the same gzip file is not supported. The addition of
1322 "x" when writing will create the file exclusively, which fails if the file
1323 already exists. On systems that support it, the addition of "e" when
1324 reading or writing will set the flag to close the file on an execve() call.
1325
1326 These functions, as well as gzip, will read and decode a sequence of gzip
1327 streams in a file. The append function of gzopen() can be used to create
1328 such a file. (Also see gzflush() for another way to do this.) When
1329 appending, gzopen does not test whether the file begins with a gzip stream,
1330 nor does it look for the end of the gzip streams to begin appending. gzopen
1331 will simply append a gzip stream to the existing file.
1332
1333 gzopen can be used to read a file which is not in gzip format; in this
1334 case gzread will directly read from the file without decompression. When
1335 reading, this will be detected automatically by looking for the magic two-
1336 byte gzip header.
1337
1338 gzopen returns NULL if the file could not be opened, if there was
1339 insufficient memory to allocate the gzFile state, or if an invalid mode was
1340 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1341 errno can be checked to determine if the reason gzopen failed was that the
1342 file could not be opened.
1343 */
1344
1345 ZEXTERN gzFile ZEXPORT gzdopen(int fd, const char *mode);
1346 /*
1347 Associate a gzFile with the file descriptor fd. File descriptors are
1348 obtained from calls like open, dup, creat, pipe or fileno (if the file has
1349 been previously opened with fopen). The mode parameter is as in gzopen.
1350
1351 The next call of gzclose on the returned gzFile will also close the file
1352 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1353 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1354 mode);. The duplicated descriptor should be saved to avoid a leak, since
1355 gzdopen does not close fd if it fails. If you are using fileno() to get the
1356 file descriptor from a FILE *, then you will have to use dup() to avoid
1357 double-close()ing the file descriptor. Both gzclose() and fclose() will
1358 close the associated file descriptor, so they need to have different file
1359 descriptors.
1360
1361 gzdopen returns NULL if there was insufficient memory to allocate the
1362 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1363 provided, or '+' was provided), or if fd is -1. The file descriptor is not
1364 used until the next gz* read, write, seek, or close operation, so gzdopen
1365 will not detect if fd is invalid (unless fd is -1).
1366 */
1367
1368 ZEXTERN int ZEXPORT gzbuffer(gzFile file, unsigned size);
1369 /*
1370 Set the internal buffer size used by this library's functions for file to
1371 size. The default buffer size is 8192 bytes. This function must be called
1372 after gzopen() or gzdopen(), and before any other calls that read or write
1373 the file. The buffer memory allocation is always deferred to the first read
1374 or write. Three times that size in buffer space is allocated. A larger
1375 buffer size of, for example, 64K or 128K bytes will noticeably increase the
1376 speed of decompression (reading).
1377
1378 The new buffer size also affects the maximum length for gzprintf().
1379
1380 gzbuffer() returns 0 on success, or -1 on failure, such as being called
1381 too late.
1382 */
1383
1384 ZEXTERN int ZEXPORT gzsetparams(gzFile file, int level, int strategy);
1385 /*
1386 Dynamically update the compression level and strategy for file. See the
1387 description of deflateInit2 for the meaning of these parameters. Previously
1388 provided data is flushed before applying the parameter changes.
1389
1390 gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1391 opened for writing, Z_ERRNO if there is an error writing the flushed data,
1392 or Z_MEM_ERROR if there is a memory allocation error.
1393 */
1394
1395 ZEXTERN int ZEXPORT gzread(gzFile file, voidp buf, unsigned len);
1396 /*
1397 Read and decompress up to len uncompressed bytes from file into buf. If
1398 the input file is not in gzip format, gzread copies the given number of
1399 bytes into the buffer directly from the file.
1400
1401 After reaching the end of a gzip stream in the input, gzread will continue
1402 to read, looking for another gzip stream. Any number of gzip streams may be
1403 concatenated in the input file, and will all be decompressed by gzread().
1404 If something other than a gzip stream is encountered after a gzip stream,
1405 that remaining trailing garbage is ignored (and no error is returned).
1406
1407 gzread can be used to read a gzip file that is being concurrently written.
1408 Upon reaching the end of the input, gzread will return with the available
1409 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1410 gzclearerr can be used to clear the end of file indicator in order to permit
1411 gzread to be tried again. Z_OK indicates that a gzip stream was completed
1412 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1413 middle of a gzip stream. Note that gzread does not return -1 in the event
1414 of an incomplete gzip stream. This error is deferred until gzclose(), which
1415 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1416 stream. Alternatively, gzerror can be used before gzclose to detect this
1417 case.
1418
1419 gzread returns the number of uncompressed bytes actually read, less than
1420 len for end of file, or -1 for error. If len is too large to fit in an int,
1421 then nothing is read, -1 is returned, and the error state is set to
1422 Z_STREAM_ERROR.
1423 */
1424
1425 ZEXTERN z_size_t ZEXPORT gzfread(voidp buf, z_size_t size, z_size_t nitems,
1426 gzFile file);
1427 /*
1428 Read and decompress up to nitems items of size size from file into buf,
1429 otherwise operating as gzread() does. This duplicates the interface of
1430 stdio's fread(), with size_t request and return types. If the library
1431 defines size_t, then z_size_t is identical to size_t. If not, then z_size_t
1432 is an unsigned integer type that can contain a pointer.
1433
1434 gzfread() returns the number of full items read of size size, or zero if
1435 the end of the file was reached and a full item could not be read, or if
1436 there was an error. gzerror() must be consulted if zero is returned in
1437 order to determine if there was an error. If the multiplication of size and
1438 nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1439 is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1440
1441 In the event that the end of file is reached and only a partial item is
1442 available at the end, i.e. the remaining uncompressed data length is not a
1443 multiple of size, then the final partial item is nevertheless read into buf
1444 and the end-of-file flag is set. The length of the partial item read is not
1445 provided, but could be inferred from the result of gztell(). This behavior
1446 is the same as the behavior of fread() implementations in common libraries,
1447 but it prevents the direct use of gzfread() to read a concurrently written
1448 file, resetting and retrying on end-of-file, when size is not 1.
1449 */
1450
1451 ZEXTERN int ZEXPORT gzwrite(gzFile file, voidpc buf, unsigned len);
1452 /*
1453 Compress and write the len uncompressed bytes at buf to file. gzwrite
1454 returns the number of uncompressed bytes written or 0 in case of error.
1455 */
1456
1457 ZEXTERN z_size_t ZEXPORT gzfwrite(voidpc buf, z_size_t size,
1458 z_size_t nitems, gzFile file);
1459 /*
1460 Compress and write nitems items of size size from buf to file, duplicating
1461 the interface of stdio's fwrite(), with size_t request and return types. If
1462 the library defines size_t, then z_size_t is identical to size_t. If not,
1463 then z_size_t is an unsigned integer type that can contain a pointer.
1464
1465 gzfwrite() returns the number of full items written of size size, or zero
1466 if there was an error. If the multiplication of size and nitems overflows,
1467 i.e. the product does not fit in a z_size_t, then nothing is written, zero
1468 is returned, and the error state is set to Z_STREAM_ERROR.
1469 */
1470
1471 ZEXTERN int ZEXPORTVA gzprintf(gzFile file, const char *format, ...);
1472 /*
1473 Convert, format, compress, and write the arguments (...) to file under
1474 control of the string format, as in fprintf. gzprintf returns the number of
1475 uncompressed bytes actually written, or a negative zlib error code in case
1476 of error. The number of uncompressed bytes written is limited to 8191, or
1477 one less than the buffer size given to gzbuffer(). The caller should assure
1478 that this limit is not exceeded. If it is exceeded, then gzprintf() will
1479 return an error (0) with nothing written. In this case, there may also be a
1480 buffer overflow with unpredictable consequences, which is possible only if
1481 zlib was compiled with the insecure functions sprintf() or vsprintf(),
1482 because the secure snprintf() or vsnprintf() functions were not available.
1483 This can be determined using zlibCompileFlags().
1484 */
1485
1486 ZEXTERN int ZEXPORT gzputs(gzFile file, const char *s);
1487 /*
1488 Compress and write the given null-terminated string s to file, excluding
1489 the terminating null character.
1490
1491 gzputs returns the number of characters written, or -1 in case of error.
1492 */
1493
1494 ZEXTERN char * ZEXPORT gzgets(gzFile file, char *buf, int len);
1495 /*
1496 Read and decompress bytes from file into buf, until len-1 characters are
1497 read, or until a newline character is read and transferred to buf, or an
1498 end-of-file condition is encountered. If any characters are read or if len
1499 is one, the string is terminated with a null character. If no characters
1500 are read due to an end-of-file or len is less than one, then the buffer is
1501 left untouched.
1502
1503 gzgets returns buf which is a null-terminated string, or it returns NULL
1504 for end-of-file or in case of error. If there was an error, the contents at
1505 buf are indeterminate.
1506 */
1507
1508 ZEXTERN int ZEXPORT gzputc(gzFile file, int c);
1509 /*
1510 Compress and write c, converted to an unsigned char, into file. gzputc
1511 returns the value that was written, or -1 in case of error.
1512 */
1513
1514 ZEXTERN int ZEXPORT gzgetc(gzFile file);
1515 /*
1516 Read and decompress one byte from file. gzgetc returns this byte or -1
1517 in case of end of file or error. This is implemented as a macro for speed.
1518 As such, it does not do all of the checking the other functions do. I.e.
1519 it does not check to see if file is NULL, nor whether the structure file
1520 points to has been clobbered or not.
1521 */
1522
1523 ZEXTERN int ZEXPORT gzungetc(int c, gzFile file);
1524 /*
1525 Push c back onto the stream for file to be read as the first character on
1526 the next read. At least one character of push-back is always allowed.
1527 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1528 fail if c is -1, and may fail if a character has been pushed but not read
1529 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1530 output buffer size of pushed characters is allowed. (See gzbuffer above.)
1531 The pushed character will be discarded if the stream is repositioned with
1532 gzseek() or gzrewind().
1533 */
1534
1535 ZEXTERN int ZEXPORT gzflush(gzFile file, int flush);
1536 /*
1537 Flush all pending output to file. The parameter flush is as in the
1538 deflate() function. The return value is the zlib error number (see function
1539 gzerror below). gzflush is only permitted when writing.
1540
1541 If the flush parameter is Z_FINISH, the remaining data is written and the
1542 gzip stream is completed in the output. If gzwrite() is called again, a new
1543 gzip stream will be started in the output. gzread() is able to read such
1544 concatenated gzip streams.
1545
1546 gzflush should be called only when strictly necessary because it will
1547 degrade compression if called too often.
1548 */
1549
1550 /*
1551 ZEXTERN z_off_t ZEXPORT gzseek(gzFile file,
1552 z_off_t offset, int whence);
1553
1554 Set the starting position to offset relative to whence for the next gzread
1555 or gzwrite on file. The offset represents a number of bytes in the
1556 uncompressed data stream. The whence parameter is defined as in lseek(2);
1557 the value SEEK_END is not supported.
1558
1559 If the file is opened for reading, this function is emulated but can be
1560 extremely slow. If the file is opened for writing, only forward seeks are
1561 supported; gzseek then compresses a sequence of zeroes up to the new
1562 starting position.
1563
1564 gzseek returns the resulting offset location as measured in bytes from
1565 the beginning of the uncompressed stream, or -1 in case of error, in
1566 particular if the file is opened for writing and the new starting position
1567 would be before the current position.
1568 */
1569
1570 ZEXTERN int ZEXPORT gzrewind(gzFile file);
1571 /*
1572 Rewind file. This function is supported only for reading.
1573
1574 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
1575 */
1576
1577 /*
1578 ZEXTERN z_off_t ZEXPORT gztell(gzFile file);
1579
1580 Return the starting position for the next gzread or gzwrite on file.
1581 This position represents a number of bytes in the uncompressed data stream,
1582 and is zero when starting, even if appending or reading a gzip stream from
1583 the middle of a file using gzdopen().
1584
1585 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1586 */
1587
1588 /*
1589 ZEXTERN z_off_t ZEXPORT gzoffset(gzFile file);
1590
1591 Return the current compressed (actual) read or write offset of file. This
1592 offset includes the count of bytes that precede the gzip stream, for example
1593 when appending or when using gzdopen() for reading. When reading, the
1594 offset does not include as yet unused buffered input. This information can
1595 be used for a progress indicator. On error, gzoffset() returns -1.
1596 */
1597
1598 ZEXTERN int ZEXPORT gzeof(gzFile file);
1599 /*
1600 Return true (1) if the end-of-file indicator for file has been set while
1601 reading, false (0) otherwise. Note that the end-of-file indicator is set
1602 only if the read tried to go past the end of the input, but came up short.
1603 Therefore, just like feof(), gzeof() may return false even if there is no
1604 more data to read, in the event that the last read request was for the exact
1605 number of bytes remaining in the input file. This will happen if the input
1606 file size is an exact multiple of the buffer size.
1607
1608 If gzeof() returns true, then the read functions will return no more data,
1609 unless the end-of-file indicator is reset by gzclearerr() and the input file
1610 has grown since the previous end of file was detected.
1611 */
1612
1613 ZEXTERN int ZEXPORT gzdirect(gzFile file);
1614 /*
1615 Return true (1) if file is being copied directly while reading, or false
1616 (0) if file is a gzip stream being decompressed.
1617
1618 If the input file is empty, gzdirect() will return true, since the input
1619 does not contain a gzip stream.
1620
1621 If gzdirect() is used immediately after gzopen() or gzdopen() it will
1622 cause buffers to be allocated to allow reading the file to determine if it
1623 is a gzip file. Therefore if gzbuffer() is used, it should be called before
1624 gzdirect().
1625
1626 When writing, gzdirect() returns true (1) if transparent writing was
1627 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1628 gzdirect() is not needed when writing. Transparent writing must be
1629 explicitly requested, so the application already knows the answer. When
1630 linking statically, using gzdirect() will include all of the zlib code for
1631 gzip file reading and decompression, which may not be desired.)
1632 */
1633
1634 ZEXTERN int ZEXPORT gzclose(gzFile file);
1635 /*
1636 Flush all pending output for file, if necessary, close file and
1637 deallocate the (de)compression state. Note that once file is closed, you
1638 cannot call gzerror with file, since its structures have been deallocated.
1639 gzclose must not be called more than once on the same file, just as free
1640 must not be called more than once on the same allocation.
1641
1642 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1643 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1644 last read ended in the middle of a gzip stream, or Z_OK on success.
1645 */
1646
1647 ZEXTERN int ZEXPORT gzclose_r(gzFile file);
1648 ZEXTERN int ZEXPORT gzclose_w(gzFile file);
1649 /*
1650 Same as gzclose(), but gzclose_r() is only for use when reading, and
1651 gzclose_w() is only for use when writing or appending. The advantage to
1652 using these instead of gzclose() is that they avoid linking in zlib
1653 compression or decompression code that is not used when only reading or only
1654 writing respectively. If gzclose() is used, then both compression and
1655 decompression code will be included the application when linking to a static
1656 zlib library.
1657 */
1658
1659 ZEXTERN const char * ZEXPORT gzerror(gzFile file, int *errnum);
1660 /*
1661 Return the error message for the last error which occurred on file.
1662 errnum is set to zlib error number. If an error occurred in the file system
1663 and not in the compression library, errnum is set to Z_ERRNO and the
1664 application may consult errno to get the exact error code.
1665
1666 The application must not modify the returned string. Future calls to
1667 this function may invalidate the previously returned string. If file is
1668 closed, then the string previously returned by gzerror will no longer be
1669 available.
1670
1671 gzerror() should be used to distinguish errors from end-of-file for those
1672 functions above that do not distinguish those cases in their return values.
1673 */
1674
1675 ZEXTERN void ZEXPORT gzclearerr(gzFile file);
1676 /*
1677 Clear the error and end-of-file flags for file. This is analogous to the
1678 clearerr() function in stdio. This is useful for continuing to read a gzip
1679 file that is being written concurrently.
1680 */
1681
1682 #endif /* !Z_SOLO */
1683
1684 /* checksum functions */
1685
1686 /*
1687 These functions are not related to compression but are exported
1688 anyway because they might be useful in applications using the compression
1689 library.
1690 */
1691
1692 ZEXTERN uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len);
1693 /*
1694 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1695 return the updated checksum. An Adler-32 value is in the range of a 32-bit
1696 unsigned integer. If buf is Z_NULL, this function returns the required
1697 initial value for the checksum.
1698
1699 An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1700 much faster.
1701
1702 Usage example:
1703
1704 uLong adler = adler32(0L, Z_NULL, 0);
1705
1706 while (read_buffer(buffer, length) != EOF) {
1707 adler = adler32(adler, buffer, length);
1708 }
1709 if (adler != original_adler) error();
1710 */
1711
1712 ZEXTERN uLong ZEXPORT adler32_z(uLong adler, const Bytef *buf,
1713 z_size_t len);
1714 /*
1715 Same as adler32(), but with a size_t length.
1716 */
1717
1718 /*
1719 ZEXTERN uLong ZEXPORT adler32_combine(uLong adler1, uLong adler2,
1720 z_off_t len2);
1721
1722 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1723 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1724 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1725 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1726 that the z_off_t type (like off_t) is a signed integer. If len2 is
1727 negative, the result has no meaning or utility.
1728 */
1729
1730 ZEXTERN uLong ZEXPORT crc32(uLong crc, const Bytef *buf, uInt len);
1731 /*
1732 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1733 updated CRC-32. A CRC-32 value is in the range of a 32-bit unsigned integer.
1734 If buf is Z_NULL, this function returns the required initial value for the
1735 crc. Pre- and post-conditioning (one's complement) is performed within this
1736 function so it shouldn't be done by the application.
1737
1738 Usage example:
1739
1740 uLong crc = crc32(0L, Z_NULL, 0);
1741
1742 while (read_buffer(buffer, length) != EOF) {
1743 crc = crc32(crc, buffer, length);
1744 }
1745 if (crc != original_crc) error();
1746 */
1747
1748 ZEXTERN uLong ZEXPORT crc32_z(uLong crc, const Bytef *buf,
1749 z_size_t len);
1750 /*
1751 Same as crc32(), but with a size_t length.
1752 */
1753
1754 /*
1755 ZEXTERN uLong ZEXPORT crc32_combine(uLong crc1, uLong crc2, z_off_t len2);
1756
1757 Combine two CRC-32 check values into one. For two sequences of bytes,
1758 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1759 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1760 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1761 len2.
1762 */
1763
1764 /*
1765 ZEXTERN uLong ZEXPORT crc32_combine_gen(z_off_t len2);
1766
1767 Return the operator corresponding to length len2, to be used with
1768 crc32_combine_op().
1769 */
1770
1771 ZEXTERN uLong ZEXPORT crc32_combine_op(uLong crc1, uLong crc2, uLong op);
1772 /*
1773 Give the same result as crc32_combine(), using op in place of len2. op is
1774 is generated from len2 by crc32_combine_gen(). This will be faster than
1775 crc32_combine() if the generated op is used more than once.
1776 */
1777
1778
1779 /* various hacks, don't look :) */
1780
1781 /* deflateInit and inflateInit are macros to allow checking the zlib version
1782 * and the compiler's view of z_stream:
1783 */
1784 ZEXTERN int ZEXPORT deflateInit_(z_streamp strm, int level,
1785 const char *version, int stream_size);
1786 ZEXTERN int ZEXPORT inflateInit_(z_streamp strm,
1787 const char *version, int stream_size);
1788 ZEXTERN int ZEXPORT deflateInit2_(z_streamp strm, int level, int method,
1789 int windowBits, int memLevel,
1790 int strategy, const char *version,
1791 int stream_size);
1792 ZEXTERN int ZEXPORT inflateInit2_(z_streamp strm, int windowBits,
1793 const char *version, int stream_size);
1794 ZEXTERN int ZEXPORT inflateBackInit_(z_streamp strm, int windowBits,
1795 unsigned char FAR *window,
1796 const char *version,
1797 int stream_size);
1798 #ifdef Z_PREFIX_SET
1799 # define z_deflateInit(strm, level) \
1800 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1801 # define z_inflateInit(strm) \
1802 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1803 # define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1804 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1805 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1806 # define z_inflateInit2(strm, windowBits) \
1807 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1808 (int)sizeof(z_stream))
1809 # define z_inflateBackInit(strm, windowBits, window) \
1810 inflateBackInit_((strm), (windowBits), (window), \
1811 ZLIB_VERSION, (int)sizeof(z_stream))
1812 #else
1813 # define deflateInit(strm, level) \
1814 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1815 # define inflateInit(strm) \
1816 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1817 # define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1818 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1819 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1820 # define inflateInit2(strm, windowBits) \
1821 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1822 (int)sizeof(z_stream))
1823 # define inflateBackInit(strm, windowBits, window) \
1824 inflateBackInit_((strm), (windowBits), (window), \
1825 ZLIB_VERSION, (int)sizeof(z_stream))
1826 #endif
1827
1828 #ifndef Z_SOLO
1829
1830 /* gzgetc() macro and its supporting function and exposed data structure. Note
1831 * that the real internal state is much larger than the exposed structure.
1832 * This abbreviated structure exposes just enough for the gzgetc() macro. The
1833 * user should not mess with these exposed elements, since their names or
1834 * behavior could change in the future, perhaps even capriciously. They can
1835 * only be used by the gzgetc() macro. You have been warned.
1836 */
1837 struct gzFile_s {
1838 unsigned have;
1839 unsigned char *next;
1840 z_off64_t pos;
1841 };
1842 ZEXTERN int ZEXPORT gzgetc_(gzFile file); /* backward compatibility */
1843 #ifdef Z_PREFIX_SET
1844 # undef z_gzgetc
1845 # define z_gzgetc(g) \
1846 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1847 #else
1848 # define gzgetc(g) \
1849 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1850 #endif
1851
1852 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1853 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1854 * both are true, the application gets the *64 functions, and the regular
1855 * functions are changed to 64 bits) -- in case these are set on systems
1856 * without large file support, _LFS64_LARGEFILE must also be true
1857 */
1858 #ifdef Z_LARGE64
1859 ZEXTERN gzFile ZEXPORT gzopen64(const char *, const char *);
1860 ZEXTERN z_off64_t ZEXPORT gzseek64(gzFile, z_off64_t, int);
1861 ZEXTERN z_off64_t ZEXPORT gztell64(gzFile);
1862 ZEXTERN z_off64_t ZEXPORT gzoffset64(gzFile);
1863 ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off64_t);
1864 ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off64_t);
1865 ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off64_t);
1866 #endif
1867
1868 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1869 # ifdef Z_PREFIX_SET
1870 # define z_gzopen z_gzopen64
1871 # define z_gzseek z_gzseek64
1872 # define z_gztell z_gztell64
1873 # define z_gzoffset z_gzoffset64
1874 # define z_adler32_combine z_adler32_combine64
1875 # define z_crc32_combine z_crc32_combine64
1876 # define z_crc32_combine_gen z_crc32_combine_gen64
1877 # else
1878 # define gzopen gzopen64
1879 # define gzseek gzseek64
1880 # define gztell gztell64
1881 # define gzoffset gzoffset64
1882 # define adler32_combine adler32_combine64
1883 # define crc32_combine crc32_combine64
1884 # define crc32_combine_gen crc32_combine_gen64
1885 # endif
1886 # ifndef Z_LARGE64
1887 ZEXTERN gzFile ZEXPORT gzopen64(const char *, const char *);
1888 ZEXTERN z_off_t ZEXPORT gzseek64(gzFile, z_off_t, int);
1889 ZEXTERN z_off_t ZEXPORT gztell64(gzFile);
1890 ZEXTERN z_off_t ZEXPORT gzoffset64(gzFile);
1891 ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off_t);
1892 ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off_t);
1893 ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off_t);
1894 # endif
1895 #else
1896 ZEXTERN gzFile ZEXPORT gzopen(const char *, const char *);
1897 ZEXTERN z_off_t ZEXPORT gzseek(gzFile, z_off_t, int);
1898 ZEXTERN z_off_t ZEXPORT gztell(gzFile);
1899 ZEXTERN z_off_t ZEXPORT gzoffset(gzFile);
1900 ZEXTERN uLong ZEXPORT adler32_combine(uLong, uLong, z_off_t);
1901 ZEXTERN uLong ZEXPORT crc32_combine(uLong, uLong, z_off_t);
1902 ZEXTERN uLong ZEXPORT crc32_combine_gen(z_off_t);
1903 #endif
1904
1905 #else /* Z_SOLO */
1906
1907 ZEXTERN uLong ZEXPORT adler32_combine(uLong, uLong, z_off_t);
1908 ZEXTERN uLong ZEXPORT crc32_combine(uLong, uLong, z_off_t);
1909 ZEXTERN uLong ZEXPORT crc32_combine_gen(z_off_t);
1910
1911 #endif /* !Z_SOLO */
1912
1913 /* undocumented functions */
1914 ZEXTERN const char * ZEXPORT zError(int);
1915 ZEXTERN int ZEXPORT inflateSyncPoint(z_streamp);
1916 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table(void);
1917 ZEXTERN int ZEXPORT inflateUndermine(z_streamp, int);
1918 ZEXTERN int ZEXPORT inflateValidate(z_streamp, int);
1919 ZEXTERN unsigned long ZEXPORT inflateCodesUsed(z_streamp);
1920 ZEXTERN int ZEXPORT inflateResetKeep(z_streamp);
1921 ZEXTERN int ZEXPORT deflateResetKeep(z_streamp);
1922 #if defined(_WIN32) && !defined(Z_SOLO)
1923 ZEXTERN gzFile ZEXPORT gzopen_w(const wchar_t *path,
1924 const char *mode);
1925 #endif
1926 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1927 # ifndef Z_SOLO
1928 ZEXTERN int ZEXPORTVA gzvprintf(gzFile file,
1929 const char *format,
1930 va_list va);
1931 # endif
1932 #endif
1933
1934 #ifdef __cplusplus
1935 }
1936 #endif
1937
1938 #endif /* ZLIB_H */
Browse
Usage
Versions