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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.8, April 28th, 2013
4 Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
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.
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:
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.
22 Jean-loup Gailly Mark Adler
23 jloup@gzip.org madler@alumni.caltech.edu
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).
31 #ifndef ZLIB_H
32 #define ZLIB_H
34 #include "zconf.h"
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
40 #define ZLIB_VERSION "1.2.8"
41 #define ZLIB_VERNUM 0x1280
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 2
44 #define ZLIB_VER_REVISION 8
45 #define ZLIB_VER_SUBREVISION 0
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.
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.
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.
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.
68 This library can optionally read and write gzip streams in memory as well.
70 The zlib format was designed to be compact and fast for use in memory
71 and on communications channels. The gzip format was designed for single-
72 file compression on file systems, has a larger header than zlib to maintain
73 directory information, and uses a different, slower check method than zlib.
75 The library does not install any signal handler. The decoder checks
76 the consistency of the compressed data, so the library should never crash
77 even in case of corrupted input.
80 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
81 typedef void (*free_func) OF((voidpf opaque, voidpf address));
83 struct internal_state;
85 typedef struct z_stream_s {
86 z_const Bytef *next_in; /* next input byte */
87 uInt avail_in; /* number of bytes available at next_in */
88 uLong total_in; /* total number of input bytes read so far */
90 Bytef *next_out; /* next output byte should be put there */
91 uInt avail_out; /* remaining free space at next_out */
92 uLong total_out; /* total number of bytes output so far */
94 z_const char *msg; /* last error message, NULL if no error */
95 struct internal_state FAR *state; /* not visible by applications */
97 alloc_func zalloc; /* used to allocate the internal state */
98 free_func zfree; /* used to free the internal state */
99 voidpf opaque; /* private data object passed to zalloc and zfree */
101 int data_type; /* best guess about the data type: binary or text */
102 uLong adler; /* adler32 value of the uncompressed data */
103 uLong reserved; /* reserved for future use */
104 } z_stream;
106 typedef z_stream FAR *z_streamp;
109 gzip header information passed to and from zlib routines. See RFC 1952
110 for more details on the meanings of these fields.
112 typedef struct gz_header_s {
113 int text; /* true if compressed data believed to be text */
114 uLong time; /* modification time */
115 int xflags; /* extra flags (not used when writing a gzip file) */
116 int os; /* operating system */
117 Bytef *extra; /* pointer to extra field or Z_NULL if none */
118 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
119 uInt extra_max; /* space at extra (only when reading header) */
120 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
121 uInt name_max; /* space at name (only when reading header) */
122 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
123 uInt comm_max; /* space at comment (only when reading header) */
124 int hcrc; /* true if there was or will be a header crc */
125 int done; /* true when done reading gzip header (not used
126 when writing a gzip file) */
127 } gz_header;
129 typedef gz_header FAR *gz_headerp;
132 The application must update next_in and avail_in when avail_in has dropped
133 to zero. It must update next_out and avail_out when avail_out has dropped
134 to zero. The application must initialize zalloc, zfree and opaque before
135 calling the init function. All other fields are set by the compression
136 library and must not be updated by the application.
138 The opaque value provided by the application will be passed as the first
139 parameter for calls of zalloc and zfree. This can be useful for custom
140 memory management. The compression library attaches no meaning to the
141 opaque value.
143 zalloc must return Z_NULL if there is not enough memory for the object.
144 If zlib is used in a multi-threaded application, zalloc and zfree must be
145 thread safe.
147 On 16-bit systems, the functions zalloc and zfree must be able to allocate
148 exactly 65536 bytes, but will not be required to allocate more than this if
149 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
150 returned by zalloc for objects of exactly 65536 bytes *must* have their
151 offset normalized to zero. The default allocation function provided by this
152 library ensures this (see zutil.c). To reduce memory requirements and avoid
153 any allocation of 64K objects, at the expense of compression ratio, compile
154 the library with -DMAX_WBITS=14 (see zconf.h).
156 The fields total_in and total_out can be used for statistics or progress
157 reports. After compression, total_in holds the total size of the
158 uncompressed data and may be saved for use in the decompressor (particularly
159 if the decompressor wants to decompress everything in a single step).
162 /* constants */
164 #define Z_NO_FLUSH 0
165 #define Z_PARTIAL_FLUSH 1
166 #define Z_SYNC_FLUSH 2
167 #define Z_FULL_FLUSH 3
168 #define Z_FINISH 4
169 #define Z_BLOCK 5
170 #define Z_TREES 6
171 /* Allowed flush values; see deflate() and inflate() below for details */
172 #define Z_INSERT_ONLY 7
174 #define Z_OK 0
175 #define Z_STREAM_END 1
176 #define Z_NEED_DICT 2
177 #define Z_ERRNO (-1)
178 #define Z_STREAM_ERROR (-2)
179 #define Z_DATA_ERROR (-3)
180 #define Z_MEM_ERROR (-4)
181 #define Z_BUF_ERROR (-5)
182 #define Z_VERSION_ERROR (-6)
183 /* Return codes for the compression/decompression functions. Negative values
184 * are errors, positive values are used for special but normal events.
187 #define Z_NO_COMPRESSION 0
188 #define Z_BEST_SPEED 1
189 #define Z_BEST_COMPRESSION 9
190 #define Z_DEFAULT_COMPRESSION (-1)
191 /* compression levels */
193 #define Z_FILTERED 1
194 #define Z_HUFFMAN_ONLY 2
195 #define Z_RLE 3
196 #define Z_FIXED 4
197 #define Z_DEFAULT_STRATEGY 0
198 /* compression strategy; see deflateInit2() below for details */
200 #define Z_BINARY 0
201 #define Z_TEXT 1
202 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
203 #define Z_UNKNOWN 2
204 /* Possible values of the data_type field (though see inflate()) */
206 #define Z_DEFLATED 8
207 /* The deflate compression method (the only one supported in this version) */
209 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
211 #define zlib_version zlibVersion()
212 /* for compatibility with versions < 1.0.2 */
215 /* basic functions */
217 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
218 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
219 If the first character differs, the library code actually used is not
220 compatible with the zlib.h header file used by the application. This check
221 is automatically made by deflateInit and inflateInit.
225 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
227 Initializes the internal stream state for compression. The fields
228 zalloc, zfree and opaque must be initialized before by the caller. If
229 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
230 allocation functions.
232 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
233 1 gives best speed, 9 gives best compression, 0 gives no compression at all
234 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
235 requests a default compromise between speed and compression (currently
236 equivalent to level 6).
238 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
239 memory, Z_STREAM_ERROR if level is not a valid compression level, or
240 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
241 with the version assumed by the caller (ZLIB_VERSION). msg is set to null
242 if there is no error message. deflateInit does not perform any compression:
243 this will be done by deflate().
247 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
249 deflate compresses as much data as possible, and stops when the input
250 buffer becomes empty or the output buffer becomes full. It may introduce
251 some output latency (reading input without producing any output) except when
252 forced to flush.
254 The detailed semantics are as follows. deflate performs one or both of the
255 following actions:
257 - Compress more input starting at next_in and update next_in and avail_in
258 accordingly. If not all input can be processed (because there is not
259 enough room in the output buffer), next_in and avail_in are updated and
260 processing will resume at this point for the next call of deflate().
262 - Provide more output starting at next_out and update next_out and avail_out
263 accordingly. This action is forced if the parameter flush is non zero.
264 Forcing flush frequently degrades the compression ratio, so this parameter
265 should be set only when necessary (in interactive applications). Some
266 output may be provided even if flush is not set.
268 Before the call of deflate(), the application should ensure that at least
269 one of the actions is possible, by providing more input and/or consuming more
270 output, and updating avail_in or avail_out accordingly; avail_out should
271 never be zero before the call. The application can consume the compressed
272 output when it wants, for example when the output buffer is full (avail_out
273 == 0), or after each call of deflate(). If deflate returns Z_OK and with
274 zero avail_out, it must be called again after making room in the output
275 buffer because there might be more output pending.
277 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
278 decide how much data to accumulate before producing output, in order to
279 maximize compression.
281 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
282 flushed to the output buffer and the output is aligned on a byte boundary, so
283 that the decompressor can get all input data available so far. (In
284 particular avail_in is zero after the call if enough output space has been
285 provided before the call.) Flushing may degrade compression for some
286 compression algorithms and so it should be used only when necessary. This
287 completes the current deflate block and follows it with an empty stored block
288 that is three bits plus filler bits to the next byte, followed by four bytes
289 (00 00 ff ff).
291 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
292 output buffer, but the output is not aligned to a byte boundary. All of the
293 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
294 This completes the current deflate block and follows it with an empty fixed
295 codes block that is 10 bits long. This assures that enough bytes are output
296 in order for the decompressor to finish the block before the empty fixed code
297 block.
299 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
300 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
301 seven bits of the current block are held to be written as the next byte after
302 the next deflate block is completed. In this case, the decompressor may not
303 be provided enough bits at this point in order to complete decompression of
304 the data provided so far to the compressor. It may need to wait for the next
305 block to be emitted. This is for advanced applications that need to control
306 the emission of deflate blocks.
308 If flush is set to Z_FULL_FLUSH, all output is flushed as with
309 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
310 restart from this point if previous compressed data has been damaged or if
311 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
312 compression.
314 If deflate returns with avail_out == 0, this function must be called again
315 with the same value of the flush parameter and more output space (updated
316 avail_out), until the flush is complete (deflate returns with non-zero
317 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
318 avail_out is greater than six to avoid repeated flush markers due to
319 avail_out == 0 on return.
321 If the parameter flush is set to Z_FINISH, pending input is processed,
322 pending output is flushed and deflate returns with Z_STREAM_END if there was
323 enough output space; if deflate returns with Z_OK, this function must be
324 called again with Z_FINISH and more output space (updated avail_out) but no
325 more input data, until it returns with Z_STREAM_END or an error. After
326 deflate has returned Z_STREAM_END, the only possible operations on the stream
327 are deflateReset or deflateEnd.
329 Z_FINISH can be used immediately after deflateInit if all the compression
330 is to be done in a single step. In this case, avail_out must be at least the
331 value returned by deflateBound (see below). Then deflate is guaranteed to
332 return Z_STREAM_END. If not enough output space is provided, deflate will
333 not return Z_STREAM_END, and it must be called again as described above.
335 deflate() sets strm->adler to the adler32 checksum of all input read
336 so far (that is, total_in bytes).
338 deflate() may update strm->data_type if it can make a good guess about
339 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
340 binary. This field is only for information purposes and does not affect the
341 compression algorithm in any manner.
343 deflate() returns Z_OK if some progress has been made (more input
344 processed or more output produced), Z_STREAM_END if all input has been
345 consumed and all output has been produced (only when flush is set to
346 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
347 if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
348 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
349 fatal, and deflate() can be called again with more input and more output
350 space to continue compressing.
354 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
356 All dynamically allocated data structures for this stream are freed.
357 This function discards any unprocessed input and does not flush any pending
358 output.
360 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
361 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
362 prematurely (some input or output was discarded). In the error case, msg
363 may be set but then points to a static string (which must not be
364 deallocated).
369 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
371 Initializes the internal stream state for decompression. The fields
372 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
373 the caller. If next_in is not Z_NULL and avail_in is large enough (the
374 exact value depends on the compression method), inflateInit determines the
375 compression method from the zlib header and allocates all data structures
376 accordingly; otherwise the allocation will be deferred to the first call of
377 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
378 use default allocation functions.
380 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
381 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
382 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
383 invalid, such as a null pointer to the structure. msg is set to null if
384 there is no error message. inflateInit does not perform any decompression
385 apart from possibly reading the zlib header if present: actual decompression
386 will be done by inflate(). (So next_in and avail_in may be modified, but
387 next_out and avail_out are unused and unchanged.) The current implementation
388 of inflateInit() does not process any header information -- that is deferred
389 until inflate() is called.
393 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
395 inflate decompresses as much data as possible, and stops when the input
396 buffer becomes empty or the output buffer becomes full. It may introduce
397 some output latency (reading input without producing any output) except when
398 forced to flush.
400 The detailed semantics are as follows. inflate performs one or both of the
401 following actions:
403 - Decompress more input starting at next_in and update next_in and avail_in
404 accordingly. If not all input can be processed (because there is not
405 enough room in the output buffer), next_in is updated and processing will
406 resume at this point for the next call of inflate().
408 - Provide more output starting at next_out and update next_out and avail_out
409 accordingly. inflate() provides as much output as possible, until there is
410 no more input data or no more space in the output buffer (see below about
411 the flush parameter).
413 Before the call of inflate(), the application should ensure that at least
414 one of the actions is possible, by providing more input and/or consuming more
415 output, and updating the next_* and avail_* values accordingly. The
416 application can consume the uncompressed output when it wants, for example
417 when the output buffer is full (avail_out == 0), or after each call of
418 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
419 called again after making room in the output buffer because there might be
420 more output pending.
422 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
423 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
424 output as possible to the output buffer. Z_BLOCK requests that inflate()
425 stop if and when it gets to the next deflate block boundary. When decoding
426 the zlib or gzip format, this will cause inflate() to return immediately
427 after the header and before the first block. When doing a raw inflate,
428 inflate() will go ahead and process the first block, and will return when it
429 gets to the end of that block, or when it runs out of data.
431 The Z_BLOCK option assists in appending to or combining deflate streams.
432 Also to assist in this, on return inflate() will set strm->data_type to the
433 number of unused bits in the last byte taken from strm->next_in, plus 64 if
434 inflate() is currently decoding the last block in the deflate stream, plus
435 128 if inflate() returned immediately after decoding an end-of-block code or
436 decoding the complete header up to just before the first byte of the deflate
437 stream. The end-of-block will not be indicated until all of the uncompressed
438 data from that block has been written to strm->next_out. The number of
439 unused bits may in general be greater than seven, except when bit 7 of
440 data_type is set, in which case the number of unused bits will be less than
441 eight. data_type is set as noted here every time inflate() returns for all
442 flush options, and so can be used to determine the amount of currently
443 consumed input in bits.
445 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
446 end of each deflate block header is reached, before any actual data in that
447 block is decoded. This allows the caller to determine the length of the
448 deflate block header for later use in random access within a deflate block.
449 256 is added to the value of strm->data_type when inflate() returns
450 immediately after reaching the end of the deflate block header.
452 inflate() should normally be called until it returns Z_STREAM_END or an
453 error. However if all decompression is to be performed in a single step (a
454 single call of inflate), the parameter flush should be set to Z_FINISH. In
455 this case all pending input is processed and all pending output is flushed;
456 avail_out must be large enough to hold all of the uncompressed data for the
457 operation to complete. (The size of the uncompressed data may have been
458 saved by the compressor for this purpose.) The use of Z_FINISH is not
459 required to perform an inflation in one step. However it may be used to
460 inform inflate that a faster approach can be used for the single inflate()
461 call. Z_FINISH also informs inflate to not maintain a sliding window if the
462 stream completes, which reduces inflate's memory footprint. If the stream
463 does not complete, either because not all of the stream is provided or not
464 enough output space is provided, then a sliding window will be allocated and
465 inflate() can be called again to continue the operation as if Z_NO_FLUSH had
466 been used.
468 In this implementation, inflate() always flushes as much output as
469 possible to the output buffer, and always uses the faster approach on the
470 first call. So the effects of the flush parameter in this implementation are
471 on the return value of inflate() as noted below, when inflate() returns early
472 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
473 memory for a sliding window when Z_FINISH is used.
475 If a preset dictionary is needed after this call (see inflateSetDictionary
476 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
477 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
478 strm->adler to the Adler-32 checksum of all output produced so far (that is,
479 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
480 below. At the end of the stream, inflate() checks that its computed adler32
481 checksum is equal to that saved by the compressor and returns Z_STREAM_END
482 only if the checksum is correct.
484 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
485 deflate data. The header type is detected automatically, if requested when
486 initializing with inflateInit2(). Any information contained in the gzip
487 header is not retained, so applications that need that information should
488 instead use raw inflate, see inflateInit2() below, or inflateBack() and
489 perform their own processing of the gzip header and trailer. When processing
490 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
491 producted so far. The CRC-32 is checked against the gzip trailer.
493 inflate() returns Z_OK if some progress has been made (more input processed
494 or more output produced), Z_STREAM_END if the end of the compressed data has
495 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
496 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
497 corrupted (input stream not conforming to the zlib format or incorrect check
498 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
499 next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
500 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
501 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
502 inflate() can be called again with more input and more output space to
503 continue decompressing. If Z_DATA_ERROR is returned, the application may
504 then call inflateSync() to look for a good compression block if a partial
505 recovery of the data is desired.
509 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
511 All dynamically allocated data structures for this stream are freed.
512 This function discards any unprocessed input and does not flush any pending
513 output.
515 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
516 was inconsistent. In the error case, msg may be set but then points to a
517 static string (which must not be deallocated).
521 /* Advanced functions */
524 The following functions are needed only in some special applications.
528 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
529 int level,
530 int method,
531 int windowBits,
532 int memLevel,
533 int strategy));
535 This is another version of deflateInit with more compression options. The
536 fields next_in, zalloc, zfree and opaque must be initialized before by the
537 caller.
539 The method parameter is the compression method. It must be Z_DEFLATED in
540 this version of the library.
542 The windowBits parameter is the base two logarithm of the window size
543 (the size of the history buffer). It should be in the range 8..15 for this
544 version of the library. Larger values of this parameter result in better
545 compression at the expense of memory usage. The default value is 15 if
546 deflateInit is used instead.
548 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
549 determines the window size. deflate() will then generate raw deflate data
550 with no zlib header or trailer, and will not compute an adler32 check value.
552 windowBits can also be greater than 15 for optional gzip encoding. Add
553 16 to windowBits to write a simple gzip header and trailer around the
554 compressed data instead of a zlib wrapper. The gzip header will have no
555 file name, no extra data, no comment, no modification time (set to zero), no
556 header crc, and the operating system will be set to 255 (unknown). If a
557 gzip stream is being written, strm->adler is a crc32 instead of an adler32.
559 The memLevel parameter specifies how much memory should be allocated
560 for the internal compression state. memLevel=1 uses minimum memory but is
561 slow and reduces compression ratio; memLevel=9 uses maximum memory for
562 optimal speed. The default value is 8. See zconf.h for total memory usage
563 as a function of windowBits and memLevel.
565 The strategy parameter is used to tune the compression algorithm. Use the
566 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
567 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
568 string match), or Z_RLE to limit match distances to one (run-length
569 encoding). Filtered data consists mostly of small values with a somewhat
570 random distribution. In this case, the compression algorithm is tuned to
571 compress them better. The effect of Z_FILTERED is to force more Huffman
572 coding and less string matching; it is somewhat intermediate between
573 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
574 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
575 strategy parameter only affects the compression ratio but not the
576 correctness of the compressed output even if it is not set appropriately.
577 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
578 decoder for special applications.
580 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
581 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
582 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
583 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
584 set to null if there is no error message. deflateInit2 does not perform any
585 compression: this will be done by deflate().
588 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
589 const Bytef *dictionary,
590 uInt dictLength));
592 Initializes the compression dictionary from the given byte sequence
593 without producing any compressed output. When using the zlib format, this
594 function must be called immediately after deflateInit, deflateInit2 or
595 deflateReset, and before any call of deflate. When doing raw deflate, this
596 function must be called either before any call of deflate, or immediately
597 after the completion of a deflate block, i.e. after all input has been
598 consumed and all output has been delivered when using any of the flush
599 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
600 compressor and decompressor must use exactly the same dictionary (see
601 inflateSetDictionary).
603 The dictionary should consist of strings (byte sequences) that are likely
604 to be encountered later in the data to be compressed, with the most commonly
605 used strings preferably put towards the end of the dictionary. Using a
606 dictionary is most useful when the data to be compressed is short and can be
607 predicted with good accuracy; the data can then be compressed better than
608 with the default empty dictionary.
610 Depending on the size of the compression data structures selected by
611 deflateInit or deflateInit2, a part of the dictionary may in effect be
612 discarded, for example if the dictionary is larger than the window size
613 provided in deflateInit or deflateInit2. Thus the strings most likely to be
614 useful should be put at the end of the dictionary, not at the front. In
615 addition, the current implementation of deflate will use at most the window
616 size minus 262 bytes of the provided dictionary.
618 Upon return of this function, strm->adler is set to the adler32 value
619 of the dictionary; the decompressor may later use this value to determine
620 which dictionary has been used by the compressor. (The adler32 value
621 applies to the whole dictionary even if only a subset of the dictionary is
622 actually used by the compressor.) If a raw deflate was requested, then the
623 adler32 value is not computed and strm->adler is not set.
625 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
626 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
627 inconsistent (for example if deflate has already been called for this stream
628 or if not at a block boundary for raw deflate). deflateSetDictionary does
629 not perform any compression: this will be done by deflate().
632 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
633 z_streamp source));
635 Sets the destination stream as a complete copy of the source stream.
637 This function can be useful when several compression strategies will be
638 tried, for example when there are several ways of pre-processing the input
639 data with a filter. The streams that will be discarded should then be freed
640 by calling deflateEnd. Note that deflateCopy duplicates the internal
641 compression state which can be quite large, so this strategy is slow and can
642 consume lots of memory.
644 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
645 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
646 (such as zalloc being Z_NULL). msg is left unchanged in both source and
647 destination.
650 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
652 This function is equivalent to deflateEnd followed by deflateInit,
653 but does not free and reallocate all the internal compression state. The
654 stream will keep the same compression level and any other attributes that
655 may have been set by deflateInit2.
657 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
658 stream state was inconsistent (such as zalloc or state being Z_NULL).
661 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
662 int level,
663 int strategy));
665 Dynamically update the compression level and compression strategy. The
666 interpretation of level and strategy is as in deflateInit2. This can be
667 used to switch between compression and straight copy of the input data, or
668 to switch to a different kind of input data requiring a different strategy.
669 If the compression level is changed, the input available so far is
670 compressed with the old level (and may be flushed); the new level will take
671 effect only at the next call of deflate().
673 Before the call of deflateParams, the stream state must be set as for
674 a call of deflate(), since the currently available input may have to be
675 compressed and flushed. In particular, strm->avail_out must be non-zero.
677 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
678 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
679 strm->avail_out was zero.
682 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
683 int good_length,
684 int max_lazy,
685 int nice_length,
686 int max_chain));
688 Fine tune deflate's internal compression parameters. This should only be
689 used by someone who understands the algorithm used by zlib's deflate for
690 searching for the best matching string, and even then only by the most
691 fanatic optimizer trying to squeeze out the last compressed bit for their
692 specific input data. Read the deflate.c source code for the meaning of the
693 max_lazy, good_length, nice_length, and max_chain parameters.
695 deflateTune() can be called after deflateInit() or deflateInit2(), and
696 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
699 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
700 uLong sourceLen));
702 deflateBound() returns an upper bound on the compressed size after
703 deflation of sourceLen bytes. It must be called after deflateInit() or
704 deflateInit2(), and after deflateSetHeader(), if used. This would be used
705 to allocate an output buffer for deflation in a single pass, and so would be
706 called before deflate(). If that first deflate() call is provided the
707 sourceLen input bytes, an output buffer allocated to the size returned by
708 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
709 to return Z_STREAM_END. Note that it is possible for the compressed size to
710 be larger than the value returned by deflateBound() if flush options other
711 than Z_FINISH or Z_NO_FLUSH are used.
714 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
715 unsigned *pending,
716 int *bits));
718 deflatePending() returns the number of bytes and bits of output that have
719 been generated, but not yet provided in the available output. The bytes not
720 provided would be due to the available output space having being consumed.
721 The number of bits of output not provided are between 0 and 7, where they
722 await more bits to join them in order to fill out a full byte. If pending
723 or bits are Z_NULL, then those values are not set.
725 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
726 stream state was inconsistent.
729 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
730 int bits,
731 int value));
733 deflatePrime() inserts bits in the deflate output stream. The intent
734 is that this function is used to start off the deflate output with the bits
735 leftover from a previous deflate stream when appending to it. As such, this
736 function can only be used for raw deflate, and must be used before the first
737 deflate() call after a deflateInit2() or deflateReset(). bits must be less
738 than or equal to 16, and that many of the least significant bits of value
739 will be inserted in the output.
741 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
742 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
743 source stream state was inconsistent.
746 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
747 gz_headerp head));
749 deflateSetHeader() provides gzip header information for when a gzip
750 stream is requested by deflateInit2(). deflateSetHeader() may be called
751 after deflateInit2() or deflateReset() and before the first call of
752 deflate(). The text, time, os, extra field, name, and comment information
753 in the provided gz_header structure are written to the gzip header (xflag is
754 ignored -- the extra flags are set according to the compression level). The
755 caller must assure that, if not Z_NULL, name and comment are terminated with
756 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
757 available there. If hcrc is true, a gzip header crc is included. Note that
758 the current versions of the command-line version of gzip (up through version
759 1.3.x) do not support header crc's, and will report that it is a "multi-part
760 gzip file" and give up.
762 If deflateSetHeader is not used, the default gzip header has text false,
763 the time set to zero, and os set to 255, with no extra, name, or comment
764 fields. The gzip header is returned to the default state by deflateReset().
766 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
767 stream state was inconsistent.
771 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
772 int windowBits));
774 This is another version of inflateInit with an extra parameter. The
775 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
776 before by the caller.
778 The windowBits parameter is the base two logarithm of the maximum window
779 size (the size of the history buffer). It should be in the range 8..15 for
780 this version of the library. The default value is 15 if inflateInit is used
781 instead. windowBits must be greater than or equal to the windowBits value
782 provided to deflateInit2() while compressing, or it must be equal to 15 if
783 deflateInit2() was not used. If a compressed stream with a larger window
784 size is given as input, inflate() will return with the error code
785 Z_DATA_ERROR instead of trying to allocate a larger window.
787 windowBits can also be zero to request that inflate use the window size in
788 the zlib header of the compressed stream.
790 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
791 determines the window size. inflate() will then process raw deflate data,
792 not looking for a zlib or gzip header, not generating a check value, and not
793 looking for any check values for comparison at the end of the stream. This
794 is for use with other formats that use the deflate compressed data format
795 such as zip. Those formats provide their own check values. If a custom
796 format is developed using the raw deflate format for compressed data, it is
797 recommended that a check value such as an adler32 or a crc32 be applied to
798 the uncompressed data as is done in the zlib, gzip, and zip formats. For
799 most applications, the zlib format should be used as is. Note that comments
800 above on the use in deflateInit2() applies to the magnitude of windowBits.
802 windowBits can also be greater than 15 for optional gzip decoding. Add
803 32 to windowBits to enable zlib and gzip decoding with automatic header
804 detection, or add 16 to decode only the gzip format (the zlib format will
805 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
806 crc32 instead of an adler32.
808 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
809 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
810 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
811 invalid, such as a null pointer to the structure. msg is set to null if
812 there is no error message. inflateInit2 does not perform any decompression
813 apart from possibly reading the zlib header if present: actual decompression
814 will be done by inflate(). (So next_in and avail_in may be modified, but
815 next_out and avail_out are unused and unchanged.) The current implementation
816 of inflateInit2() does not process any header information -- that is
817 deferred until inflate() is called.
820 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
821 const Bytef *dictionary,
822 uInt dictLength));
824 Initializes the decompression dictionary from the given uncompressed byte
825 sequence. This function must be called immediately after a call of inflate,
826 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
827 can be determined from the adler32 value returned by that call of inflate.
828 The compressor and decompressor must use exactly the same dictionary (see
829 deflateSetDictionary). For raw inflate, this function can be called at any
830 time to set the dictionary. If the provided dictionary is smaller than the
831 window and there is already data in the window, then the provided dictionary
832 will amend what's there. The application must insure that the dictionary
833 that was used for compression is provided.
835 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
836 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
837 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
838 expected one (incorrect adler32 value). inflateSetDictionary does not
839 perform any decompression: this will be done by subsequent calls of
840 inflate().
843 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
844 Bytef *dictionary,
845 uInt *dictLength));
847 Returns the sliding dictionary being maintained by inflate. dictLength is
848 set to the number of bytes in the dictionary, and that many bytes are copied
849 to dictionary. dictionary must have enough space, where 32768 bytes is
850 always enough. If inflateGetDictionary() is called with dictionary equal to
851 Z_NULL, then only the dictionary length is returned, and nothing is copied.
852 Similary, if dictLength is Z_NULL, then it is not set.
854 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
855 stream state is inconsistent.
858 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
860 Skips invalid compressed data until a possible full flush point (see above
861 for the description of deflate with Z_FULL_FLUSH) can be found, or until all
862 available input is skipped. No output is provided.
864 inflateSync searches for a 00 00 FF FF pattern in the compressed data.
865 All full flush points have this pattern, but not all occurrences of this
866 pattern are full flush points.
868 inflateSync returns Z_OK if a possible full flush point has been found,
869 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
870 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
871 In the success case, the application may save the current current value of
872 total_in which indicates where valid compressed data was found. In the
873 error case, the application may repeatedly call inflateSync, providing more
874 input each time, until success or end of the input data.
877 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
878 z_streamp source));
880 Sets the destination stream as a complete copy of the source stream.
882 This function can be useful when randomly accessing a large stream. The
883 first pass through the stream can periodically record the inflate state,
884 allowing restarting inflate at those points when randomly accessing the
885 stream.
887 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
888 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
889 (such as zalloc being Z_NULL). msg is left unchanged in both source and
890 destination.
893 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
895 This function is equivalent to inflateEnd followed by inflateInit,
896 but does not free and reallocate all the internal decompression state. The
897 stream will keep attributes that may have been set by inflateInit2.
899 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
900 stream state was inconsistent (such as zalloc or state being Z_NULL).
903 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
904 int windowBits));
906 This function is the same as inflateReset, but it also permits changing
907 the wrap and window size requests. The windowBits parameter is interpreted
908 the same as it is for inflateInit2.
910 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
911 stream state was inconsistent (such as zalloc or state being Z_NULL), or if
912 the windowBits parameter is invalid.
915 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
916 int bits,
917 int value));
919 This function inserts bits in the inflate input stream. The intent is
920 that this function is used to start inflating at a bit position in the
921 middle of a byte. The provided bits will be used before any bytes are used
922 from next_in. This function should only be used with raw inflate, and
923 should be used before the first inflate() call after inflateInit2() or
924 inflateReset(). bits must be less than or equal to 16, and that many of the
925 least significant bits of value will be inserted in the input.
927 If bits is negative, then the input stream bit buffer is emptied. Then
928 inflatePrime() can be called again to put bits in the buffer. This is used
929 to clear out bits leftover after feeding inflate a block description prior
930 to feeding inflate codes.
932 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
933 stream state was inconsistent.
936 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
938 This function returns two values, one in the lower 16 bits of the return
939 value, and the other in the remaining upper bits, obtained by shifting the
940 return value down 16 bits. If the upper value is -1 and the lower value is
941 zero, then inflate() is currently decoding information outside of a block.
942 If the upper value is -1 and the lower value is non-zero, then inflate is in
943 the middle of a stored block, with the lower value equaling the number of
944 bytes from the input remaining to copy. If the upper value is not -1, then
945 it is the number of bits back from the current bit position in the input of
946 the code (literal or length/distance pair) currently being processed. In
947 that case the lower value is the number of bytes already emitted for that
948 code.
950 A code is being processed if inflate is waiting for more input to complete
951 decoding of the code, or if it has completed decoding but is waiting for
952 more output space to write the literal or match data.
954 inflateMark() is used to mark locations in the input data for random
955 access, which may be at bit positions, and to note those cases where the
956 output of a code may span boundaries of random access blocks. The current
957 location in the input stream can be determined from avail_in and data_type
958 as noted in the description for the Z_BLOCK flush parameter for inflate.
960 inflateMark returns the value noted above or -1 << 16 if the provided
961 source stream state was inconsistent.
964 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
965 gz_headerp head));
967 inflateGetHeader() requests that gzip header information be stored in the
968 provided gz_header structure. inflateGetHeader() may be called after
969 inflateInit2() or inflateReset(), and before the first call of inflate().
970 As inflate() processes the gzip stream, head->done is zero until the header
971 is completed, at which time head->done is set to one. If a zlib stream is
972 being decoded, then head->done is set to -1 to indicate that there will be
973 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
974 used to force inflate() to return immediately after header processing is
975 complete and before any actual data is decompressed.
977 The text, time, xflags, and os fields are filled in with the gzip header
978 contents. hcrc is set to true if there is a header CRC. (The header CRC
979 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
980 contains the maximum number of bytes to write to extra. Once done is true,
981 extra_len contains the actual extra field length, and extra contains the
982 extra field, or that field truncated if extra_max is less than extra_len.
983 If name is not Z_NULL, then up to name_max characters are written there,
984 terminated with a zero unless the length is greater than name_max. If
985 comment is not Z_NULL, then up to comm_max characters are written there,
986 terminated with a zero unless the length is greater than comm_max. When any
987 of extra, name, or comment are not Z_NULL and the respective field is not
988 present in the header, then that field is set to Z_NULL to signal its
989 absence. This allows the use of deflateSetHeader() with the returned
990 structure to duplicate the header. However if those fields are set to
991 allocated memory, then the application will need to save those pointers
992 elsewhere so that they can be eventually freed.
994 If inflateGetHeader is not used, then the header information is simply
995 discarded. The header is always checked for validity, including the header
996 CRC if present. inflateReset() will reset the process to discard the header
997 information. The application would need to call inflateGetHeader() again to
998 retrieve the header from the next gzip stream.
1000 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1001 stream state was inconsistent.
1005 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1006 unsigned char FAR *window));
1008 Initialize the internal stream state for decompression using inflateBack()
1009 calls. The fields zalloc, zfree and opaque in strm must be initialized
1010 before the call. If zalloc and zfree are Z_NULL, then the default library-
1011 derived memory allocation routines are used. windowBits is the base two
1012 logarithm of the window size, in the range 8..15. window is a caller
1013 supplied buffer of that size. Except for special applications where it is
1014 assured that deflate was used with small window sizes, windowBits must be 15
1015 and a 32K byte window must be supplied to be able to decompress general
1016 deflate streams.
1018 See inflateBack() for the usage of these routines.
1020 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1021 the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1022 allocated, or Z_VERSION_ERROR if the version of the library does not match
1023 the version of the header file.
1026 typedef unsigned (*in_func) OF((void FAR *,
1027 z_const unsigned char FAR * FAR *));
1028 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1030 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1031 in_func in, void FAR *in_desc,
1032 out_func out, void FAR *out_desc));
1034 inflateBack() does a raw inflate with a single call using a call-back
1035 interface for input and output. This is potentially more efficient than
1036 inflate() for file i/o applications, in that it avoids copying between the
1037 output and the sliding window by simply making the window itself the output
1038 buffer. inflate() can be faster on modern CPUs when used with large
1039 buffers. inflateBack() trusts the application to not change the output
1040 buffer passed by the output function, at least until inflateBack() returns.
1042 inflateBackInit() must be called first to allocate the internal state
1043 and to initialize the state with the user-provided window buffer.
1044 inflateBack() may then be used multiple times to inflate a complete, raw
1045 deflate stream with each call. inflateBackEnd() is then called to free the
1046 allocated state.
1048 A raw deflate stream is one with no zlib or gzip header or trailer.
1049 This routine would normally be used in a utility that reads zip or gzip
1050 files and writes out uncompressed files. The utility would decode the
1051 header and process the trailer on its own, hence this routine expects only
1052 the raw deflate stream to decompress. This is different from the normal
1053 behavior of inflate(), which expects either a zlib or gzip header and
1054 trailer around the deflate stream.
1056 inflateBack() uses two subroutines supplied by the caller that are then
1057 called by inflateBack() for input and output. inflateBack() calls those
1058 routines until it reads a complete deflate stream and writes out all of the
1059 uncompressed data, or until it encounters an error. The function's
1060 parameters and return types are defined above in the in_func and out_func
1061 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1062 number of bytes of provided input, and a pointer to that input in buf. If
1063 there is no input available, in() must return zero--buf is ignored in that
1064 case--and inflateBack() will return a buffer error. inflateBack() will call
1065 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
1066 should return zero on success, or non-zero on failure. If out() returns
1067 non-zero, inflateBack() will return with an error. Neither in() nor out()
1068 are permitted to change the contents of the window provided to
1069 inflateBackInit(), which is also the buffer that out() uses to write from.
1070 The length written by out() will be at most the window size. Any non-zero
1071 amount of input may be provided by in().
1073 For convenience, inflateBack() can be provided input on the first call by
1074 setting strm->next_in and strm->avail_in. If that input is exhausted, then
1075 in() will be called. Therefore strm->next_in must be initialized before
1076 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1077 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1078 must also be initialized, and then if strm->avail_in is not zero, input will
1079 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1081 The in_desc and out_desc parameters of inflateBack() is passed as the
1082 first parameter of in() and out() respectively when they are called. These
1083 descriptors can be optionally used to pass any information that the caller-
1084 supplied in() and out() functions need to do their job.
1086 On return, inflateBack() will set strm->next_in and strm->avail_in to
1087 pass back any unused input that was provided by the last in() call. The
1088 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1089 if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1090 in the deflate stream (in which case strm->msg is set to indicate the nature
1091 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1092 In the case of Z_BUF_ERROR, an input or output error can be distinguished
1093 using strm->next_in which will be Z_NULL only if in() returned an error. If
1094 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1095 non-zero. (in() will always be called before out(), so strm->next_in is
1096 assured to be defined if out() returns non-zero.) Note that inflateBack()
1097 cannot return Z_OK.
1100 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1102 All memory allocated by inflateBackInit() is freed.
1104 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1105 state was inconsistent.
1108 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1109 /* Return flags indicating compile-time options.
1111 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1112 1.0: size of uInt
1113 3.2: size of uLong
1114 5.4: size of voidpf (pointer)
1115 7.6: size of z_off_t
1117 Compiler, assembler, and debug options:
1118 8: DEBUG
1119 9: ASMV or ASMINF -- use ASM code
1120 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1121 11: 0 (reserved)
1123 One-time table building (smaller code, but not thread-safe if true):
1124 12: BUILDFIXED -- build static block decoding tables when needed
1125 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1126 14,15: 0 (reserved)
1128 Library content (indicates missing functionality):
1129 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1130 deflate code when not needed)
1131 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1132 and decode gzip streams (to avoid linking crc code)
1133 18-19: 0 (reserved)
1135 Operation variations (changes in library functionality):
1136 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1137 21: FASTEST -- deflate algorithm with only one, lowest compression level
1138 22,23: 0 (reserved)
1140 The sprintf variant used by gzprintf (zero is best):
1141 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1142 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1143 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1145 Remainder:
1146 27-31: 0 (reserved)
1149 #ifndef Z_SOLO
1151 /* utility functions */
1154 The following utility functions are implemented on top of the basic
1155 stream-oriented functions. To simplify the interface, some default options
1156 are assumed (compression level and memory usage, standard memory allocation
1157 functions). The source code of these utility functions can be modified if
1158 you need special options.
1161 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1162 const Bytef *source, uLong sourceLen));
1164 Compresses the source buffer into the destination buffer. sourceLen is
1165 the byte length of the source buffer. Upon entry, destLen is the total size
1166 of the destination buffer, which must be at least the value returned by
1167 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1168 compressed buffer.
1170 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1171 enough memory, Z_BUF_ERROR if there was not enough room in the output
1172 buffer.
1175 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1176 const Bytef *source, uLong sourceLen,
1177 int level));
1179 Compresses the source buffer into the destination buffer. The level
1180 parameter has the same meaning as in deflateInit. sourceLen is the byte
1181 length of the source buffer. Upon entry, destLen is the total size of the
1182 destination buffer, which must be at least the value returned by
1183 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1184 compressed buffer.
1186 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1187 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1188 Z_STREAM_ERROR if the level parameter is invalid.
1191 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1193 compressBound() returns an upper bound on the compressed size after
1194 compress() or compress2() on sourceLen bytes. It would be used before a
1195 compress() or compress2() call to allocate the destination buffer.
1198 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1199 const Bytef *source, uLong sourceLen));
1201 Decompresses the source buffer into the destination buffer. sourceLen is
1202 the byte length of the source buffer. Upon entry, destLen is the total size
1203 of the destination buffer, which must be large enough to hold the entire
1204 uncompressed data. (The size of the uncompressed data must have been saved
1205 previously by the compressor and transmitted to the decompressor by some
1206 mechanism outside the scope of this compression library.) Upon exit, destLen
1207 is the actual size of the uncompressed buffer.
1209 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1210 enough memory, Z_BUF_ERROR if there was not enough room in the output
1211 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1212 the case where there is not enough room, uncompress() will fill the output
1213 buffer with the uncompressed data up to that point.
1216 /* gzip file access functions */
1219 This library supports reading and writing files in gzip (.gz) format with
1220 an interface similar to that of stdio, using the functions that start with
1221 "gz". The gzip format is different from the zlib format. gzip is a gzip
1222 wrapper, documented in RFC 1952, wrapped around a deflate stream.
1225 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1228 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1230 Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1231 in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1232 a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1233 compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1234 for fixed code compression as in "wb9F". (See the description of
1235 deflateInit2 for more information about the strategy parameter.) 'T' will
1236 request transparent writing or appending with no compression and not using
1237 the gzip format.
1239 "a" can be used instead of "w" to request that the gzip stream that will
1240 be written be appended to the file. "+" will result in an error, since
1241 reading and writing to the same gzip file is not supported. The addition of
1242 "x" when writing will create the file exclusively, which fails if the file
1243 already exists. On systems that support it, the addition of "e" when
1244 reading or writing will set the flag to close the file on an execve() call.
1246 These functions, as well as gzip, will read and decode a sequence of gzip
1247 streams in a file. The append function of gzopen() can be used to create
1248 such a file. (Also see gzflush() for another way to do this.) When
1249 appending, gzopen does not test whether the file begins with a gzip stream,
1250 nor does it look for the end of the gzip streams to begin appending. gzopen
1251 will simply append a gzip stream to the existing file.
1253 gzopen can be used to read a file which is not in gzip format; in this
1254 case gzread will directly read from the file without decompression. When
1255 reading, this will be detected automatically by looking for the magic two-
1256 byte gzip header.
1258 gzopen returns NULL if the file could not be opened, if there was
1259 insufficient memory to allocate the gzFile state, or if an invalid mode was
1260 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1261 errno can be checked to determine if the reason gzopen failed was that the
1262 file could not be opened.
1265 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1267 gzdopen associates a gzFile with the file descriptor fd. File descriptors
1268 are obtained from calls like open, dup, creat, pipe or fileno (if the file
1269 has been previously opened with fopen). The mode parameter is as in gzopen.
1271 The next call of gzclose on the returned gzFile will also close the file
1272 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1273 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1274 mode);. The duplicated descriptor should be saved to avoid a leak, since
1275 gzdopen does not close fd if it fails. If you are using fileno() to get the
1276 file descriptor from a FILE *, then you will have to use dup() to avoid
1277 double-close()ing the file descriptor. Both gzclose() and fclose() will
1278 close the associated file descriptor, so they need to have different file
1279 descriptors.
1281 gzdopen returns NULL if there was insufficient memory to allocate the
1282 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1283 provided, or '+' was provided), or if fd is -1. The file descriptor is not
1284 used until the next gz* read, write, seek, or close operation, so gzdopen
1285 will not detect if fd is invalid (unless fd is -1).
1288 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1290 Set the internal buffer size used by this library's functions. The
1291 default buffer size is 8192 bytes. This function must be called after
1292 gzopen() or gzdopen(), and before any other calls that read or write the
1293 file. The buffer memory allocation is always deferred to the first read or
1294 write. Two buffers are allocated, either both of the specified size when
1295 writing, or one of the specified size and the other twice that size when
1296 reading. A larger buffer size of, for example, 64K or 128K bytes will
1297 noticeably increase the speed of decompression (reading).
1299 The new buffer size also affects the maximum length for gzprintf().
1301 gzbuffer() returns 0 on success, or -1 on failure, such as being called
1302 too late.
1305 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1307 Dynamically update the compression level or strategy. See the description
1308 of deflateInit2 for the meaning of these parameters.
1310 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1311 opened for writing.
1314 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1316 Reads the given number of uncompressed bytes from the compressed file. If
1317 the input file is not in gzip format, gzread copies the given number of
1318 bytes into the buffer directly from the file.
1320 After reaching the end of a gzip stream in the input, gzread will continue
1321 to read, looking for another gzip stream. Any number of gzip streams may be
1322 concatenated in the input file, and will all be decompressed by gzread().
1323 If something other than a gzip stream is encountered after a gzip stream,
1324 that remaining trailing garbage is ignored (and no error is returned).
1326 gzread can be used to read a gzip file that is being concurrently written.
1327 Upon reaching the end of the input, gzread will return with the available
1328 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1329 gzclearerr can be used to clear the end of file indicator in order to permit
1330 gzread to be tried again. Z_OK indicates that a gzip stream was completed
1331 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1332 middle of a gzip stream. Note that gzread does not return -1 in the event
1333 of an incomplete gzip stream. This error is deferred until gzclose(), which
1334 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1335 stream. Alternatively, gzerror can be used before gzclose to detect this
1336 case.
1338 gzread returns the number of uncompressed bytes actually read, less than
1339 len for end of file, or -1 for error.
1342 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1343 voidpc buf, unsigned len));
1345 Writes the given number of uncompressed bytes into the compressed file.
1346 gzwrite returns the number of uncompressed bytes written or 0 in case of
1347 error.
1350 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1352 Converts, formats, and writes the arguments to the compressed file under
1353 control of the format string, as in fprintf. gzprintf returns the number of
1354 uncompressed bytes actually written, or 0 in case of error. The number of
1355 uncompressed bytes written is limited to 8191, or one less than the buffer
1356 size given to gzbuffer(). The caller should assure that this limit is not
1357 exceeded. If it is exceeded, then gzprintf() will return an error (0) with
1358 nothing written. In this case, there may also be a buffer overflow with
1359 unpredictable consequences, which is possible only if zlib was compiled with
1360 the insecure functions sprintf() or vsprintf() because the secure snprintf()
1361 or vsnprintf() functions were not available. This can be determined using
1362 zlibCompileFlags().
1365 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1367 Writes the given null-terminated string to the compressed file, excluding
1368 the terminating null character.
1370 gzputs returns the number of characters written, or -1 in case of error.
1373 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1375 Reads bytes from the compressed file until len-1 characters are read, or a
1376 newline character is read and transferred to buf, or an end-of-file
1377 condition is encountered. If any characters are read or if len == 1, the
1378 string is terminated with a null character. If no characters are read due
1379 to an end-of-file or len < 1, then the buffer is left untouched.
1381 gzgets returns buf which is a null-terminated string, or it returns NULL
1382 for end-of-file or in case of error. If there was an error, the contents at
1383 buf are indeterminate.
1386 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1388 Writes c, converted to an unsigned char, into the compressed file. gzputc
1389 returns the value that was written, or -1 in case of error.
1392 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1394 Reads one byte from the compressed file. gzgetc returns this byte or -1
1395 in case of end of file or error. This is implemented as a macro for speed.
1396 As such, it does not do all of the checking the other functions do. I.e.
1397 it does not check to see if file is NULL, nor whether the structure file
1398 points to has been clobbered or not.
1401 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1403 Push one character back onto the stream to be read as the first character
1404 on the next read. At least one character of push-back is allowed.
1405 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1406 fail if c is -1, and may fail if a character has been pushed but not read
1407 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1408 output buffer size of pushed characters is allowed. (See gzbuffer above.)
1409 The pushed character will be discarded if the stream is repositioned with
1410 gzseek() or gzrewind().
1413 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1415 Flushes all pending output into the compressed file. The parameter flush
1416 is as in the deflate() function. The return value is the zlib error number
1417 (see function gzerror below). gzflush is only permitted when writing.
1419 If the flush parameter is Z_FINISH, the remaining data is written and the
1420 gzip stream is completed in the output. If gzwrite() is called again, a new
1421 gzip stream will be started in the output. gzread() is able to read such
1422 concatented gzip streams.
1424 gzflush should be called only when strictly necessary because it will
1425 degrade compression if called too often.
1429 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1430 z_off_t offset, int whence));
1432 Sets the starting position for the next gzread or gzwrite on the given
1433 compressed file. The offset represents a number of bytes in the
1434 uncompressed data stream. The whence parameter is defined as in lseek(2);
1435 the value SEEK_END is not supported.
1437 If the file is opened for reading, this function is emulated but can be
1438 extremely slow. If the file is opened for writing, only forward seeks are
1439 supported; gzseek then compresses a sequence of zeroes up to the new
1440 starting position.
1442 gzseek returns the resulting offset location as measured in bytes from
1443 the beginning of the uncompressed stream, or -1 in case of error, in
1444 particular if the file is opened for writing and the new starting position
1445 would be before the current position.
1448 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1450 Rewinds the given file. This function is supported only for reading.
1452 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1456 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1458 Returns the starting position for the next gzread or gzwrite on the given
1459 compressed file. This position represents a number of bytes in the
1460 uncompressed data stream, and is zero when starting, even if appending or
1461 reading a gzip stream from the middle of a file using gzdopen().
1463 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1467 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1469 Returns the current offset in the file being read or written. This offset
1470 includes the count of bytes that precede the gzip stream, for example when
1471 appending or when using gzdopen() for reading. When reading, the offset
1472 does not include as yet unused buffered input. This information can be used
1473 for a progress indicator. On error, gzoffset() returns -1.
1476 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1478 Returns true (1) if the end-of-file indicator has been set while reading,
1479 false (0) otherwise. Note that the end-of-file indicator is set only if the
1480 read tried to go past the end of the input, but came up short. Therefore,
1481 just like feof(), gzeof() may return false even if there is no more data to
1482 read, in the event that the last read request was for the exact number of
1483 bytes remaining in the input file. This will happen if the input file size
1484 is an exact multiple of the buffer size.
1486 If gzeof() returns true, then the read functions will return no more data,
1487 unless the end-of-file indicator is reset by gzclearerr() and the input file
1488 has grown since the previous end of file was detected.
1491 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1493 Returns true (1) if file is being copied directly while reading, or false
1494 (0) if file is a gzip stream being decompressed.
1496 If the input file is empty, gzdirect() will return true, since the input
1497 does not contain a gzip stream.
1499 If gzdirect() is used immediately after gzopen() or gzdopen() it will
1500 cause buffers to be allocated to allow reading the file to determine if it
1501 is a gzip file. Therefore if gzbuffer() is used, it should be called before
1502 gzdirect().
1504 When writing, gzdirect() returns true (1) if transparent writing was
1505 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1506 gzdirect() is not needed when writing. Transparent writing must be
1507 explicitly requested, so the application already knows the answer. When
1508 linking statically, using gzdirect() will include all of the zlib code for
1509 gzip file reading and decompression, which may not be desired.)
1512 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1514 Flushes all pending output if necessary, closes the compressed file and
1515 deallocates the (de)compression state. Note that once file is closed, you
1516 cannot call gzerror with file, since its structures have been deallocated.
1517 gzclose must not be called more than once on the same file, just as free
1518 must not be called more than once on the same allocation.
1520 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1521 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1522 last read ended in the middle of a gzip stream, or Z_OK on success.
1525 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1526 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1528 Same as gzclose(), but gzclose_r() is only for use when reading, and
1529 gzclose_w() is only for use when writing or appending. The advantage to
1530 using these instead of gzclose() is that they avoid linking in zlib
1531 compression or decompression code that is not used when only reading or only
1532 writing respectively. If gzclose() is used, then both compression and
1533 decompression code will be included the application when linking to a static
1534 zlib library.
1537 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1539 Returns the error message for the last error which occurred on the given
1540 compressed file. errnum is set to zlib error number. If an error occurred
1541 in the file system and not in the compression library, errnum is set to
1542 Z_ERRNO and the application may consult errno to get the exact error code.
1544 The application must not modify the returned string. Future calls to
1545 this function may invalidate the previously returned string. If file is
1546 closed, then the string previously returned by gzerror will no longer be
1547 available.
1549 gzerror() should be used to distinguish errors from end-of-file for those
1550 functions above that do not distinguish those cases in their return values.
1553 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1555 Clears the error and end-of-file flags for file. This is analogous to the
1556 clearerr() function in stdio. This is useful for continuing to read a gzip
1557 file that is being written concurrently.
1560 #endif /* !Z_SOLO */
1562 /* checksum functions */
1565 These functions are not related to compression but are exported
1566 anyway because they might be useful in applications using the compression
1567 library.
1570 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1572 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1573 return the updated checksum. If buf is Z_NULL, this function returns the
1574 required initial value for the checksum.
1576 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1577 much faster.
1579 Usage example:
1581 uLong adler = adler32(0L, Z_NULL, 0);
1583 while (read_buffer(buffer, length) != EOF) {
1584 adler = adler32(adler, buffer, length);
1586 if (adler != original_adler) error();
1590 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1591 z_off_t len2));
1593 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1594 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1595 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1596 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1597 that the z_off_t type (like off_t) is a signed integer. If len2 is
1598 negative, the result has no meaning or utility.
1601 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1603 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1604 updated CRC-32. If buf is Z_NULL, this function returns the required
1605 initial value for the crc. Pre- and post-conditioning (one's complement) is
1606 performed within this function so it shouldn't be done by the application.
1608 Usage example:
1610 uLong crc = crc32(0L, Z_NULL, 0);
1612 while (read_buffer(buffer, length) != EOF) {
1613 crc = crc32(crc, buffer, length);
1615 if (crc != original_crc) error();
1619 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1621 Combine two CRC-32 check values into one. For two sequences of bytes,
1622 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1623 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1624 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1625 len2.
1629 /* various hacks, don't look :) */
1631 /* deflateInit and inflateInit are macros to allow checking the zlib version
1632 * and the compiler's view of z_stream:
1634 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1635 const char *version, int stream_size));
1636 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1637 const char *version, int stream_size));
1638 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1639 int windowBits, int memLevel,
1640 int strategy, const char *version,
1641 int stream_size));
1642 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1643 const char *version, int stream_size));
1644 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1645 unsigned char FAR *window,
1646 const char *version,
1647 int stream_size));
1648 #define deflateInit(strm, level) \
1649 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1650 #define inflateInit(strm) \
1651 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1652 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1653 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1654 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1655 #define inflateInit2(strm, windowBits) \
1656 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1657 (int)sizeof(z_stream))
1658 #define inflateBackInit(strm, windowBits, window) \
1659 inflateBackInit_((strm), (windowBits), (window), \
1660 ZLIB_VERSION, (int)sizeof(z_stream))
1662 #ifndef Z_SOLO
1664 /* gzgetc() macro and its supporting function and exposed data structure. Note
1665 * that the real internal state is much larger than the exposed structure.
1666 * This abbreviated structure exposes just enough for the gzgetc() macro. The
1667 * user should not mess with these exposed elements, since their names or
1668 * behavior could change in the future, perhaps even capriciously. They can
1669 * only be used by the gzgetc() macro. You have been warned.
1671 struct gzFile_s {
1672 unsigned have;
1673 unsigned char *next;
1674 z_off64_t pos;
1676 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */
1677 #ifdef Z_PREFIX_SET
1678 # undef z_gzgetc
1679 # define z_gzgetc(g) \
1680 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
1681 #else
1682 # define gzgetc(g) \
1683 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
1684 #endif
1686 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1687 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1688 * both are true, the application gets the *64 functions, and the regular
1689 * functions are changed to 64 bits) -- in case these are set on systems
1690 * without large file support, _LFS64_LARGEFILE must also be true
1692 #ifdef Z_LARGE64
1693 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1694 ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1695 ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1696 ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1697 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1698 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1699 #endif
1701 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1702 # ifdef Z_PREFIX_SET
1703 # define z_gzopen z_gzopen64
1704 # define z_gzseek z_gzseek64
1705 # define z_gztell z_gztell64
1706 # define z_gzoffset z_gzoffset64
1707 # define z_adler32_combine z_adler32_combine64
1708 # define z_crc32_combine z_crc32_combine64
1709 # else
1710 # define gzopen gzopen64
1711 # define gzseek gzseek64
1712 # define gztell gztell64
1713 # define gzoffset gzoffset64
1714 # define adler32_combine adler32_combine64
1715 # define crc32_combine crc32_combine64
1716 # endif
1717 # ifndef Z_LARGE64
1718 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1719 ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1720 ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1721 ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1722 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1723 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1724 # endif
1725 #else
1726 ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1727 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1728 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1729 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1730 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1731 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1732 #endif
1734 #else /* Z_SOLO */
1736 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1737 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1739 #endif /* !Z_SOLO */
1741 /* hack for buggy compilers */
1742 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1743 struct internal_state {int dummy;};
1744 #endif
1746 /* undocumented functions */
1747 ZEXTERN const char * ZEXPORT zError OF((int));
1748 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1749 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void));
1750 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1751 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1752 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1753 #if defined(_WIN32) && !defined(Z_SOLO)
1754 ZEXTERN gzFile ZEXPORT gzopen_w OF((const wchar_t *path,
1755 const char *mode));
1756 #endif
1757 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1758 # ifndef Z_SOLO
1759 ZEXTERN int ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1760 const char *format,
1761 va_list va));
1762 # endif
1763 #endif
1765 #ifdef __cplusplus
1767 #endif
1769 #endif /* ZLIB_H */