1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.8.1, May xxth, 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).
40 #define ZLIB_VERSION "1.2.8.1-motley"
41 #define ZLIB_VERNUM 0x1281
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 2
44 #define ZLIB_VER_REVISION 8
45 #define ZLIB_VER_SUBREVISION 1
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
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 and raw deflate streams in
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.
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.
81 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
82 typedef void (*free_func) OF((voidpf opaque, voidpf address));
84 struct internal_state;
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 */
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 */
95 z_const char *msg; /* last error message, NULL if no error */
96 struct internal_state FAR *state; /* not visible by applications */
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 */
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 */
108 typedef z_stream FAR *z_streamp;
111 gzip header information passed to and from zlib routines. See RFC 1952
112 for more details on the meanings of these fields.
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) */
131 typedef gz_header FAR *gz_headerp;
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.
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
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().
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).
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).
169 #define Z_PARTIAL_FLUSH 1
170 #define Z_SYNC_FLUSH 2
171 #define Z_FULL_FLUSH 3
175 /* Allowed flush values; see deflate() and inflate() below for details */
178 #define Z_STREAM_END 1
179 #define Z_NEED_DICT 2
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.
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 */
197 #define Z_HUFFMAN_ONLY 2
200 #define Z_DEFAULT_STRATEGY 0
201 /* compression strategy; see deflateInit2() below for details */
205 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
207 /* Possible values of the data_type field for deflate() */
210 /* The deflate compression method (the only one supported in this version) */
212 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
214 #define zlib_version zlibVersion()
215 /* for compatibility with versions < 1.0.2 */
218 /* basic functions */
220 ZEXTERN const char * ZEXPORT zlibVersion OF((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.
228 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
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.
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).
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().
250 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
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
257 The detailed semantics are as follows. deflate performs one or both of the
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().
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
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 ouput
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.
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
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
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.
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
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 to avoid repeated flush markers due to
324 avail_out == 0 on return.
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.
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.
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
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.
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.
363 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
365 All dynamically allocated data structures for this stream are freed.
366 This function discards any unprocessed input and does not flush any pending
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
378 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
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 provide input is not
383 read or consumed. Any memory allocation will be deferred to the first call
384 of inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them
385 to use default allocation functions.
387 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
388 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
389 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
390 invalid, such as a null pointer to the structure. msg is set to null if
391 there is no error message. inflateInit does not perform any decompression.
392 Actual decompression will be done by inflate(). So next_in, and avail_in,
393 next_out, and avail_out are unused and unchanged. The current
394 implementation of inflateInit() does not process any header information --
395 that is deferred until inflate() is called.
399 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
401 inflate decompresses as much data as possible, and stops when the input
402 buffer becomes empty or the output buffer becomes full. It may introduce
403 some output latency (reading input without producing any output) except when
406 The detailed semantics are as follows. inflate performs one or both of the
409 - Decompress more input starting at next_in and update next_in and avail_in
410 accordingly. If not all input can be processed (because there is not
411 enough room in the output buffer), then next_in and avail_on are updated
412 accordingly, and processing will resume at this point for the next call of
415 - Generate more output starting at next_out and update next_out and avail_out
416 accordingly. inflate() provides as much output as possible, until there is
417 no more input data or no more space in the output buffer (see below about
418 the flush parameter).
420 Before the call of inflate(), the application should ensure that at least
421 one of the actions is possible, by providing more input and/or consuming more
422 output, and updating the next_* and avail_* values accordingly. If the
423 caller of inflate() does not provide both available input and available
424 output space, it is possible that there will be no progress made. The
425 application can consume the uncompressed output when it wants, for example
426 when the output buffer is full (avail_out == 0), or after each call of
427 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
428 called again after making room in the output buffer because there might be
431 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
432 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
433 output as possible to the output buffer. Z_BLOCK requests that inflate()
434 stop if and when it gets to the next deflate block boundary. When decoding
435 the zlib or gzip format, this will cause inflate() to return immediately
436 after the header and before the first block. When doing a raw inflate,
437 inflate() will go ahead and process the first block, and will return when it
438 gets to the end of that block, or when it runs out of data.
440 The Z_BLOCK option assists in appending to or combining deflate streams.
441 To assist in this, on return inflate() always sets strm->data_type to the
442 number of unused bits in the last byte taken from strm->next_in, plus 64 if
443 inflate() is currently decoding the last block in the deflate stream, plus
444 128 if inflate() returned immediately after decoding an end-of-block code or
445 decoding the complete header up to just before the first byte of the deflate
446 stream. The end-of-block will not be indicated until all of the uncompressed
447 data from that block has been written to strm->next_out. The number of
448 unused bits may in general be greater than seven, except when bit 7 of
449 data_type is set, in which case the number of unused bits will be less than
450 eight. data_type is set as noted here every time inflate() returns for all
451 flush options, and so can be used to determine the amount of currently
452 consumed input in bits.
454 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
455 end of each deflate block header is reached, before any actual data in that
456 block is decoded. This allows the caller to determine the length of the
457 deflate block header for later use in random access within a deflate block.
458 256 is added to the value of strm->data_type when inflate() returns
459 immediately after reaching the end of the deflate block header.
461 inflate() should normally be called until it returns Z_STREAM_END or an
462 error. However if all decompression is to be performed in a single step (a
463 single call of inflate), the parameter flush should be set to Z_FINISH. In
464 this case all pending input is processed and all pending output is flushed;
465 avail_out must be large enough to hold all of the uncompressed data for the
466 operation to complete. (The size of the uncompressed data may have been
467 saved by the compressor for this purpose.) The use of Z_FINISH is not
468 required to perform an inflation in one step. However it may be used to
469 inform inflate that a faster approach can be used for the single inflate()
470 call. Z_FINISH also informs inflate to not maintain a sliding window if the
471 stream completes, which reduces inflate's memory footprint. If the stream
472 does not complete, either because not all of the stream is provided or not
473 enough output space is provided, then a sliding window will be allocated and
474 inflate() can be called again to continue the operation as if Z_NO_FLUSH had
477 In this implementation, inflate() always flushes as much output as
478 possible to the output buffer, and always uses the faster approach on the
479 first call. So the effects of the flush parameter in this implementation are
480 on the return value of inflate() as noted below, when inflate() returns early
481 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
482 memory for a sliding window when Z_FINISH is used.
484 If a preset dictionary is needed after this call (see inflateSetDictionary
485 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
486 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
487 strm->adler to the Adler-32 checksum of all output produced so far (that is,
488 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
489 below. At the end of the stream, inflate() checks that its computed Adler-32
490 checksum is equal to that saved by the compressor and returns Z_STREAM_END
491 only if the checksum is correct.
493 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
494 deflate data. The header type is detected automatically, if requested when
495 initializing with inflateInit2(). Any information contained in the gzip
496 header is not retained unless inflateGetHeader() is used. When processing
497 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
498 produced so far. The CRC-32 is checked against the gzip trailer, as is the
499 uncompressed length, modulo 2^32.
501 inflate() returns Z_OK if some progress has been made (more input processed
502 or more output produced), Z_STREAM_END if the end of the compressed data has
503 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
504 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
505 corrupted (input stream not conforming to the zlib format or incorrect check
506 value, in which case strm->msg points to a string with a more specific
507 error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
508 next_in or next_out was Z_NULL, or the state was inadvertently written over
509 by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
510 if no progress was possible or if there was not enough room in the output
511 buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
512 inflate() can be called again with more input and more output space to
513 continue decompressing. If Z_DATA_ERROR is returned, the application may
514 then call inflateSync() to look for a good compression block if a partial
515 recovery of the data is to be attempted.
519 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
521 All dynamically allocated data structures for this stream are freed.
522 This function discards any unprocessed input and does not flush any pending
525 inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
530 /* Advanced functions */
533 The following functions are needed only in some special applications.
537 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
544 This is another version of deflateInit with more compression options. The
545 fields next_in, zalloc, zfree and opaque must be initialized before by the
548 The method parameter is the compression method. It must be Z_DEFLATED in
549 this version of the library.
551 The windowBits parameter is the base two logarithm of the window size
552 (the size of the history buffer). It should be in the range 8..15 for this
553 version of the library. Larger values of this parameter result in better
554 compression at the expense of memory usage. The default value is 15 if
555 deflateInit is used instead.
557 For the current implementation of deflate(), a windowBits value of 8 (a
558 window size of 256 bytes) is not supported. As a result, a request for 8
559 will result in 9 (a 512-byte window). In that case, providing 8 to
560 inflateInit2() will result in an error when the zlib header with 9 is
561 checked against the initialization of inflate(). The remedy is to not use 8
562 with deflateInit2() with this initialization, or at least in that case use 9
565 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
566 determines the window size. deflate() will then generate raw deflate data
567 with no zlib header or trailer, and will not compute a check value.
569 windowBits can also be greater than 15 for optional gzip encoding. Add
570 16 to windowBits to write a simple gzip header and trailer around the
571 compressed data instead of a zlib wrapper. The gzip header will have no
572 file name, no extra data, no comment, no modification time (set to zero), no
573 header crc, and the operating system will be set to the appropriate value,
574 if the operating system was determined at compile time. If a gzip stream is
575 being written, strm->adler is a CRC-32 instead of an Adler-32.
577 For raw deflate or gzip encoding, a request for a 256-byte window is
578 rejected as invalid, since only the zlib header provides a means of
579 transmitting the window size to the decompressor.
581 The memLevel parameter specifies how much memory should be allocated
582 for the internal compression state. memLevel=1 uses minimum memory but is
583 slow and reduces compression ratio; memLevel=9 uses maximum memory for
584 optimal speed. The default value is 8. See zconf.h for total memory usage
585 as a function of windowBits and memLevel.
587 The strategy parameter is used to tune the compression algorithm. Use the
588 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
589 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
590 string match), or Z_RLE to limit match distances to one (run-length
591 encoding). Filtered data consists mostly of small values with a somewhat
592 random distribution. In this case, the compression algorithm is tuned to
593 compress them better. The effect of Z_FILTERED is to force more Huffman
594 coding and less string matching; it is somewhat intermediate between
595 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
596 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
597 strategy parameter only affects the compression ratio but not the
598 correctness of the compressed output even if it is not set appropriately.
599 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
600 decoder for special applications.
602 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
603 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
604 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
605 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
606 set to null if there is no error message. deflateInit2 does not perform any
607 compression: this will be done by deflate().
610 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
611 const Bytef *dictionary,
614 Initializes the compression dictionary from the given byte sequence
615 without producing any compressed output. When using the zlib format, this
616 function must be called immediately after deflateInit, deflateInit2 or
617 deflateReset, and before any call of deflate. When doing raw deflate, this
618 function must be called either before any call of deflate, or immediately
619 after the completion of a deflate block, i.e. after all input has been
620 consumed and all output has been delivered when using any of the flush
621 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
622 compressor and decompressor must use exactly the same dictionary (see
623 inflateSetDictionary).
625 The dictionary should consist of strings (byte sequences) that are likely
626 to be encountered later in the data to be compressed, with the most commonly
627 used strings preferably put towards the end of the dictionary. Using a
628 dictionary is most useful when the data to be compressed is short and can be
629 predicted with good accuracy; the data can then be compressed better than
630 with the default empty dictionary.
632 Depending on the size of the compression data structures selected by
633 deflateInit or deflateInit2, a part of the dictionary may in effect be
634 discarded, for example if the dictionary is larger than the window size
635 provided in deflateInit or deflateInit2. Thus the strings most likely to be
636 useful should be put at the end of the dictionary, not at the front. In
637 addition, the current implementation of deflate will use at most the window
638 size minus 262 bytes of the provided dictionary.
640 Upon return of this function, strm->adler is set to the Adler-32 value
641 of the dictionary; the decompressor may later use this value to determine
642 which dictionary has been used by the compressor. (The Adler-32 value
643 applies to the whole dictionary even if only a subset of the dictionary is
644 actually used by the compressor.) If a raw deflate was requested, then the
645 Adler-32 value is not computed and strm->adler is not set.
647 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
648 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
649 inconsistent (for example if deflate has already been called for this stream
650 or if not at a block boundary for raw deflate). deflateSetDictionary does
651 not perform any compression: this will be done by deflate().
654 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
657 Sets the destination stream as a complete copy of the source stream.
659 This function can be useful when several compression strategies will be
660 tried, for example when there are several ways of pre-processing the input
661 data with a filter. The streams that will be discarded should then be freed
662 by calling deflateEnd. Note that deflateCopy duplicates the internal
663 compression state which can be quite large, so this strategy is slow and can
664 consume lots of memory.
666 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
667 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
668 (such as zalloc being Z_NULL). msg is left unchanged in both source and
672 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
674 This function is equivalent to deflateEnd followed by deflateInit, but
675 does not free and reallocate the internal compression state. The stream
676 will leave the compression level and any other attributes that may have been
679 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
680 stream state was inconsistent (such as zalloc or state being Z_NULL).
683 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
687 Dynamically update the compression level and compression strategy. The
688 interpretation of level and strategy is as in deflateInit2(). This can be
689 used to switch between compression and straight copy of the input data, or
690 to switch to a different kind of input data requiring a different strategy.
691 If the compression approach (which is a function of the level) or the
692 strategy is changed, then the input available so far is compressed with the
693 old level and strategy using deflate(strm, Z_BLOCK). There are three
694 approaches for the compression levels 0, 1..3, and 4..9 respectively. The
695 new level and strategy will take effect at the next call of deflate().
697 If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
698 not have enough output space to complete, then the parameter change will not
699 take effect. In this case, deflateParams() can be called again with the
700 same parameters and more output space to try again.
702 In order to assure a change in the parameters on the first try, the
703 deflate stream should be flushed using deflate() with Z_BLOCK or other flush
704 request until strm.avail_out is not zero, before calling deflateParams().
705 Then no more input data should be provided before the deflateParams() call.
706 If this is done, the old level and strategy will be applied to the data
707 compressed before deflateParams(), and the new level and strategy will be
708 applied to the the data compressed after deflateParams().
710 deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
711 state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
712 there was not enough output space to complete the compression of the
713 available input data before a change in the strategy or approach. Note that
714 in the case of a Z_BUF_ERROR, the parameters are not changed. A return
715 value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
716 retried with more output space.
719 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
725 Fine tune deflate's internal compression parameters. This should only be
726 used by someone who understands the algorithm used by zlib's deflate for
727 searching for the best matching string, and even then only by the most
728 fanatic optimizer trying to squeeze out the last compressed bit for their
729 specific input data. Read the deflate.c source code for the meaning of the
730 max_lazy, good_length, nice_length, and max_chain parameters.
732 deflateTune() can be called after deflateInit() or deflateInit2(), and
733 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
736 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
739 deflateBound() returns an upper bound on the compressed size after
740 deflation of sourceLen bytes. It must be called after deflateInit() or
741 deflateInit2(), and after deflateSetHeader(), if used. This would be used
742 to allocate an output buffer for deflation in a single pass, and so would be
743 called before deflate(). If that first deflate() call is provided the
744 sourceLen input bytes, an output buffer allocated to the size returned by
745 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
746 to return Z_STREAM_END. Note that it is possible for the compressed size to
747 be larger than the value returned by deflateBound() if flush options other
748 than Z_FINISH or Z_NO_FLUSH are used.
751 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
755 deflatePending() returns the number of bytes and bits of output that have
756 been generated, but not yet provided in the available output. The bytes not
757 provided would be due to the available output space having being consumed.
758 The number of bits of output not provided are between 0 and 7, where they
759 await more bits to join them in order to fill out a full byte. If pending
760 or bits are Z_NULL, then those values are not set.
762 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
763 stream state was inconsistent.
766 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
770 deflatePrime() inserts bits in the deflate output stream. The intent
771 is that this function is used to start off the deflate output with the bits
772 leftover from a previous deflate stream when appending to it. As such, this
773 function can only be used for raw deflate, and must be used before the first
774 deflate() call after a deflateInit2() or deflateReset(). bits must be less
775 than or equal to 16, and that many of the least significant bits of value
776 will be inserted in the output.
778 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
779 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
780 source stream state was inconsistent.
783 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
786 deflateSetHeader() provides gzip header information for when a gzip
787 stream is requested by deflateInit2(). deflateSetHeader() may be called
788 after deflateInit2() or deflateReset() and before the first call of
789 deflate(). The text, time, os, extra field, name, and comment information
790 in the provided gz_header structure are written to the gzip header (xflag is
791 ignored -- the extra flags are set according to the compression level). The
792 caller must assure that, if not Z_NULL, name and comment are terminated with
793 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
794 available there. If hcrc is true, a gzip header crc is included. Note that
795 the current versions of the command-line version of gzip (up through version
796 1.3.x) do not support header crc's, and will report that it is a "multi-part
797 gzip file" and give up.
799 If deflateSetHeader is not used, the default gzip header has text false,
800 the time set to zero, and os set to 255, with no extra, name, or comment
801 fields. The gzip header is returned to the default state by deflateReset().
803 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
804 stream state was inconsistent.
808 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
811 This is another version of inflateInit with an extra parameter. The
812 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
813 before by the caller.
815 The windowBits parameter is the base two logarithm of the maximum window
816 size (the size of the history buffer). It should be in the range 8..15 for
817 this version of the library. The default value is 15 if inflateInit is used
818 instead. windowBits must be greater than or equal to the windowBits value
819 provided to deflateInit2() while compressing, or it must be equal to 15 if
820 deflateInit2() was not used. If a compressed stream with a larger window
821 size is given as input, inflate() will return with the error code
822 Z_DATA_ERROR instead of trying to allocate a larger window.
824 windowBits can also be zero to request that inflate use the window size in
825 the zlib header of the compressed stream.
827 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
828 determines the window size. inflate() will then process raw deflate data,
829 not looking for a zlib or gzip header, not generating a check value, and not
830 looking for any check values for comparison at the end of the stream. This
831 is for use with other formats that use the deflate compressed data format
832 such as zip. Those formats provide their own check values. If a custom
833 format is developed using the raw deflate format for compressed data, it is
834 recommended that a check value such as an Adler-32 or a CRC-32 be applied to
835 the uncompressed data as is done in the zlib, gzip, and zip formats. For
836 most applications, the zlib format should be used as is. Note that comments
837 above on the use in deflateInit2() applies to the magnitude of windowBits.
839 windowBits can also be greater than 15 for optional gzip decoding. Add
840 32 to windowBits to enable zlib and gzip decoding with automatic header
841 detection, or add 16 to decode only the gzip format (the zlib format will
842 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
843 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see
844 below), inflate() will not automatically decode concatenated gzip streams.
845 inflate() will return Z_STREAM_END at the end of the gzip stream. The state
846 would need to be reset to continue decoding a subsequent gzip stream.
848 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
849 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
850 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
851 invalid, such as a null pointer to the structure. msg is set to null if
852 there is no error message. inflateInit2 does not perform any decompression
853 apart from possibly reading the zlib header if present: actual decompression
854 will be done by inflate(). (So next_in and avail_in may be modified, but
855 next_out and avail_out are unused and unchanged.) The current implementation
856 of inflateInit2() does not process any header information -- that is
857 deferred until inflate() is called.
860 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
861 const Bytef *dictionary,
864 Initializes the decompression dictionary from the given uncompressed byte
865 sequence. This function must be called immediately after a call of inflate,
866 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
867 can be determined from the Adler-32 value returned by that call of inflate.
868 The compressor and decompressor must use exactly the same dictionary (see
869 deflateSetDictionary). For raw inflate, this function can be called at any
870 time to set the dictionary. If the provided dictionary is smaller than the
871 window and there is already data in the window, then the provided dictionary
872 will amend what's there. The application must insure that the dictionary
873 that was used for compression is provided.
875 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
876 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
877 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
878 expected one (incorrect Adler-32 value). inflateSetDictionary does not
879 perform any decompression: this will be done by subsequent calls of
883 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
887 Returns the sliding dictionary being maintained by inflate. dictLength is
888 set to the number of bytes in the dictionary, and that many bytes are copied
889 to dictionary. dictionary must have enough space, where 32768 bytes is
890 always enough. If inflateGetDictionary() is called with dictionary equal to
891 Z_NULL, then only the dictionary length is returned, and nothing is copied.
892 Similary, if dictLength is Z_NULL, then it is not set.
894 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
895 stream state is inconsistent.
898 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
900 Skips invalid compressed data until a possible full flush point (see above
901 for the description of deflate with Z_FULL_FLUSH) can be found, or until all
902 available input is skipped. No output is provided.
904 inflateSync searches for a 00 00 FF FF pattern in the compressed data.
905 All full flush points have this pattern, but not all occurrences of this
906 pattern are full flush points.
908 inflateSync returns Z_OK if a possible full flush point has been found,
909 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
910 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
911 In the success case, the application may save the current current value of
912 total_in which indicates where valid compressed data was found. In the
913 error case, the application may repeatedly call inflateSync, providing more
914 input each time, until success or end of the input data.
917 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
920 Sets the destination stream as a complete copy of the source stream.
922 This function can be useful when randomly accessing a large stream. The
923 first pass through the stream can periodically record the inflate state,
924 allowing restarting inflate at those points when randomly accessing the
927 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
928 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
929 (such as zalloc being Z_NULL). msg is left unchanged in both source and
933 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
935 This function is equivalent to inflateEnd followed by inflateInit,
936 but does not free and reallocate the internal decompression state. The
937 stream will keep attributes that may have been set by inflateInit2.
939 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
940 stream state was inconsistent (such as zalloc or state being Z_NULL).
943 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
946 This function is the same as inflateReset, but it also permits changing
947 the wrap and window size requests. The windowBits parameter is interpreted
948 the same as it is for inflateInit2. If the window size is changed, then the
949 memory allocated for the window is freed, and the window will be reallocated
950 by inflate() if needed.
952 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
953 stream state was inconsistent (such as zalloc or state being Z_NULL), or if
954 the windowBits parameter is invalid.
957 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
961 This function inserts bits in the inflate input stream. The intent is
962 that this function is used to start inflating at a bit position in the
963 middle of a byte. The provided bits will be used before any bytes are used
964 from next_in. This function should only be used with raw inflate, and
965 should be used before the first inflate() call after inflateInit2() or
966 inflateReset(). bits must be less than or equal to 16, and that many of the
967 least significant bits of value will be inserted in the input.
969 If bits is negative, then the input stream bit buffer is emptied. Then
970 inflatePrime() can be called again to put bits in the buffer. This is used
971 to clear out bits leftover after feeding inflate a block description prior
972 to feeding inflate codes.
974 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
975 stream state was inconsistent.
978 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
980 This function returns two values, one in the lower 16 bits of the return
981 value, and the other in the remaining upper bits, obtained by shifting the
982 return value down 16 bits. If the upper value is -1 and the lower value is
983 zero, then inflate() is currently decoding information outside of a block.
984 If the upper value is -1 and the lower value is non-zero, then inflate is in
985 the middle of a stored block, with the lower value equaling the number of
986 bytes from the input remaining to copy. If the upper value is not -1, then
987 it is the number of bits back from the current bit position in the input of
988 the code (literal or length/distance pair) currently being processed. In
989 that case the lower value is the number of bytes already emitted for that
992 A code is being processed if inflate is waiting for more input to complete
993 decoding of the code, or if it has completed decoding but is waiting for
994 more output space to write the literal or match data.
996 inflateMark() is used to mark locations in the input data for random
997 access, which may be at bit positions, and to note those cases where the
998 output of a code may span boundaries of random access blocks. The current
999 location in the input stream can be determined from avail_in and data_type
1000 as noted in the description for the Z_BLOCK flush parameter for inflate.
1002 inflateMark returns the value noted above, or -65536 if the provided
1003 source stream state was inconsistent.
1006 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1009 inflateGetHeader() requests that gzip header information be stored in the
1010 provided gz_header structure. inflateGetHeader() may be called after
1011 inflateInit2() or inflateReset(), and before the first call of inflate().
1012 As inflate() processes the gzip stream, head->done is zero until the header
1013 is completed, at which time head->done is set to one. If a zlib stream is
1014 being decoded, then head->done is set to -1 to indicate that there will be
1015 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
1016 used to force inflate() to return immediately after header processing is
1017 complete and before any actual data is decompressed.
1019 The text, time, xflags, and os fields are filled in with the gzip header
1020 contents. hcrc is set to true if there is a header CRC. (The header CRC
1021 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1022 contains the maximum number of bytes to write to extra. Once done is true,
1023 extra_len contains the actual extra field length, and extra contains the
1024 extra field, or that field truncated if extra_max is less than extra_len.
1025 If name is not Z_NULL, then up to name_max characters are written there,
1026 terminated with a zero unless the length is greater than name_max. If
1027 comment is not Z_NULL, then up to comm_max characters are written there,
1028 terminated with a zero unless the length is greater than comm_max. When any
1029 of extra, name, or comment are not Z_NULL and the respective field is not
1030 present in the header, then that field is set to Z_NULL to signal its
1031 absence. This allows the use of deflateSetHeader() with the returned
1032 structure to duplicate the header. However if those fields are set to
1033 allocated memory, then the application will need to save those pointers
1034 elsewhere so that they can be eventually freed.
1036 If inflateGetHeader is not used, then the header information is simply
1037 discarded. The header is always checked for validity, including the header
1038 CRC if present. inflateReset() will reset the process to discard the header
1039 information. The application would need to call inflateGetHeader() again to
1040 retrieve the header from the next gzip stream.
1042 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1043 stream state was inconsistent.
1047 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1048 unsigned char FAR *window));
1050 Initialize the internal stream state for decompression using inflateBack()
1051 calls. The fields zalloc, zfree and opaque in strm must be initialized
1052 before the call. If zalloc and zfree are Z_NULL, then the default library-
1053 derived memory allocation routines are used. windowBits is the base two
1054 logarithm of the window size, in the range 8..15. window is a caller
1055 supplied buffer of that size. Except for special applications where it is
1056 assured that deflate was used with small window sizes, windowBits must be 15
1057 and a 32K byte window must be supplied to be able to decompress general
1060 See inflateBack() for the usage of these routines.
1062 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1063 the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1064 allocated, or Z_VERSION_ERROR if the version of the library does not match
1065 the version of the header file.
1068 typedef unsigned (*in_func) OF((void FAR *,
1069 z_const unsigned char FAR * FAR *));
1070 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1072 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1073 in_func in, void FAR *in_desc,
1074 out_func out, void FAR *out_desc));
1076 inflateBack() does a raw inflate with a single call using a call-back
1077 interface for input and output. This is potentially more efficient than
1078 inflate() for file i/o applications, in that it avoids copying between the
1079 output and the sliding window by simply making the window itself the output
1080 buffer. inflate() can be faster on modern CPUs when used with large
1081 buffers. inflateBack() trusts the application to not change the output
1082 buffer passed by the output function, at least until inflateBack() returns.
1084 inflateBackInit() must be called first to allocate the internal state
1085 and to initialize the state with the user-provided window buffer.
1086 inflateBack() may then be used multiple times to inflate a complete, raw
1087 deflate stream with each call. inflateBackEnd() is then called to free the
1090 A raw deflate stream is one with no zlib or gzip header or trailer.
1091 This routine would normally be used in a utility that reads zip or gzip
1092 files and writes out uncompressed files. The utility would decode the
1093 header and process the trailer on its own, hence this routine expects only
1094 the raw deflate stream to decompress. This is different from the default
1095 behavior of inflate(), which expects a zlib header and trailer around the
1098 inflateBack() uses two subroutines supplied by the caller that are then
1099 called by inflateBack() for input and output. inflateBack() calls those
1100 routines until it reads a complete deflate stream and writes out all of the
1101 uncompressed data, or until it encounters an error. The function's
1102 parameters and return types are defined above in the in_func and out_func
1103 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1104 number of bytes of provided input, and a pointer to that input in buf. If
1105 there is no input available, in() must return zero -- buf is ignored in that
1106 case -- and inflateBack() will return a buffer error. inflateBack() will
1107 call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1108 out() should return zero on success, or non-zero on failure. If out()
1109 returns non-zero, inflateBack() will return with an error. Neither in() nor
1110 out() are permitted to change the contents of the window provided to
1111 inflateBackInit(), which is also the buffer that out() uses to write from.
1112 The length written by out() will be at most the window size. Any non-zero
1113 amount of input may be provided by in().
1115 For convenience, inflateBack() can be provided input on the first call by
1116 setting strm->next_in and strm->avail_in. If that input is exhausted, then
1117 in() will be called. Therefore strm->next_in must be initialized before
1118 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1119 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1120 must also be initialized, and then if strm->avail_in is not zero, input will
1121 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1123 The in_desc and out_desc parameters of inflateBack() is passed as the
1124 first parameter of in() and out() respectively when they are called. These
1125 descriptors can be optionally used to pass any information that the caller-
1126 supplied in() and out() functions need to do their job.
1128 On return, inflateBack() will set strm->next_in and strm->avail_in to
1129 pass back any unused input that was provided by the last in() call. The
1130 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1131 if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1132 in the deflate stream (in which case strm->msg is set to indicate the nature
1133 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1134 In the case of Z_BUF_ERROR, an input or output error can be distinguished
1135 using strm->next_in which will be Z_NULL only if in() returned an error. If
1136 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1137 non-zero. (in() will always be called before out(), so strm->next_in is
1138 assured to be defined if out() returns non-zero.) Note that inflateBack()
1142 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1144 All memory allocated by inflateBackInit() is freed.
1146 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1147 state was inconsistent.
1150 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1151 /* Return flags indicating compile-time options.
1153 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1156 5.4: size of voidpf (pointer)
1157 7.6: size of z_off_t
1159 Compiler, assembler, and debug options:
1161 9: ASMV or ASMINF -- use ASM code
1162 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1165 One-time table building (smaller code, but not thread-safe if true):
1166 12: BUILDFIXED -- build static block decoding tables when needed
1167 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1170 Library content (indicates missing functionality):
1171 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1172 deflate code when not needed)
1173 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1174 and decode gzip streams (to avoid linking crc code)
1177 Operation variations (changes in library functionality):
1178 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1179 21: FASTEST -- deflate algorithm with only one, lowest compression level
1182 The sprintf variant used by gzprintf (zero is best):
1183 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1184 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1185 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1193 /* utility functions */
1196 The following utility functions are implemented on top of the basic
1197 stream-oriented functions. To simplify the interface, some default options
1198 are assumed (compression level and memory usage, standard memory allocation
1199 functions). The source code of these utility functions can be modified if
1200 you need special options.
1203 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1204 const Bytef *source, uLong sourceLen));
1206 Compresses the source buffer into the destination buffer. sourceLen is
1207 the byte length of the source buffer. Upon entry, destLen is the total size
1208 of the destination buffer, which must be at least the value returned by
1209 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1210 compressed buffer. compress() is equivalent to compress2() with a level
1211 parameter of Z_DEFAULT_COMPRESSION.
1213 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1214 enough memory, Z_BUF_ERROR if there was not enough room in the output
1218 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1219 const Bytef *source, uLong sourceLen,
1222 Compresses the source buffer into the destination buffer. The level
1223 parameter has the same meaning as in deflateInit. sourceLen is the byte
1224 length of the source buffer. Upon entry, destLen is the total size of the
1225 destination buffer, which must be at least the value returned by
1226 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1229 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1230 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1231 Z_STREAM_ERROR if the level parameter is invalid.
1234 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1236 compressBound() returns an upper bound on the compressed size after
1237 compress() or compress2() on sourceLen bytes. It would be used before a
1238 compress() or compress2() call to allocate the destination buffer.
1241 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1242 const Bytef *source, uLong sourceLen));
1244 Decompresses the source buffer into the destination buffer. sourceLen is
1245 the byte length of the source buffer. Upon entry, destLen is the total size
1246 of the destination buffer, which must be large enough to hold the entire
1247 uncompressed data. (The size of the uncompressed data must have been saved
1248 previously by the compressor and transmitted to the decompressor by some
1249 mechanism outside the scope of this compression library.) Upon exit, destLen
1250 is the actual size of the uncompressed data.
1252 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1253 enough memory, Z_BUF_ERROR if there was not enough room in the output
1254 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1255 the case where there is not enough room, uncompress() will fill the output
1256 buffer with the uncompressed data up to that point.
1259 ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest, uLongf *destLen,
1260 const Bytef *source, uLong *sourceLen));
1262 Same as uncompress, except that sourceLen is a pointer, where the
1263 length of the source is *sourceLen. On return, *sourceLen is the number of
1264 source bytes consumed.
1267 /* gzip file access functions */
1270 This library supports reading and writing files in gzip (.gz) format with
1271 an interface similar to that of stdio, using the functions that start with
1272 "gz". The gzip format is different from the zlib format. gzip is a gzip
1273 wrapper, documented in RFC 1952, wrapped around a deflate stream.
1276 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1279 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1281 Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1282 in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1283 a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1284 compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1285 for fixed code compression as in "wb9F". (See the description of
1286 deflateInit2 for more information about the strategy parameter.) 'T' will
1287 request transparent writing or appending with no compression and not using
1290 "a" can be used instead of "w" to request that the gzip stream that will
1291 be written be appended to the file. "+" will result in an error, since
1292 reading and writing to the same gzip file is not supported. The addition of
1293 "x" when writing will create the file exclusively, which fails if the file
1294 already exists. On systems that support it, the addition of "e" when
1295 reading or writing will set the flag to close the file on an execve() call.
1297 These functions, as well as gzip, will read and decode a sequence of gzip
1298 streams in a file. The append function of gzopen() can be used to create
1299 such a file. (Also see gzflush() for another way to do this.) When
1300 appending, gzopen does not test whether the file begins with a gzip stream,
1301 nor does it look for the end of the gzip streams to begin appending. gzopen
1302 will simply append a gzip stream to the existing file.
1304 gzopen can be used to read a file which is not in gzip format; in this
1305 case gzread will directly read from the file without decompression. When
1306 reading, this will be detected automatically by looking for the magic two-
1309 gzopen returns NULL if the file could not be opened, if there was
1310 insufficient memory to allocate the gzFile state, or if an invalid mode was
1311 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1312 errno can be checked to determine if the reason gzopen failed was that the
1313 file could not be opened.
1316 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1318 gzdopen associates a gzFile with the file descriptor fd. File descriptors
1319 are obtained from calls like open, dup, creat, pipe or fileno (if the file
1320 has been previously opened with fopen). The mode parameter is as in gzopen.
1322 The next call of gzclose on the returned gzFile will also close the file
1323 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1324 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1325 mode);. The duplicated descriptor should be saved to avoid a leak, since
1326 gzdopen does not close fd if it fails. If you are using fileno() to get the
1327 file descriptor from a FILE *, then you will have to use dup() to avoid
1328 double-close()ing the file descriptor. Both gzclose() and fclose() will
1329 close the associated file descriptor, so they need to have different file
1332 gzdopen returns NULL if there was insufficient memory to allocate the
1333 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1334 provided, or '+' was provided), or if fd is -1. The file descriptor is not
1335 used until the next gz* read, write, seek, or close operation, so gzdopen
1336 will not detect if fd is invalid (unless fd is -1).
1339 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1341 Set the internal buffer size used by this library's functions. The
1342 default buffer size is 8192 bytes. This function must be called after
1343 gzopen() or gzdopen(), and before any other calls that read or write the
1344 file. The buffer memory allocation is always deferred to the first read or
1345 write. Three times that size in buffer space is allocated. A larger buffer
1346 size of, for example, 64K or 128K bytes will noticeably increase the speed
1347 of decompression (reading).
1349 The new buffer size also affects the maximum length for gzprintf().
1351 gzbuffer() returns 0 on success, or -1 on failure, such as being called
1355 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1357 Dynamically update the compression level or strategy. See the description
1358 of deflateInit2 for the meaning of these parameters. Previously provided
1359 data is flushed before the parameter change.
1361 gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1362 opened for writing, Z_ERRNO if there is an error writing the flushed data,
1363 or Z_MEM_ERROR if there is a memory allocation error.
1366 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1368 Reads the given number of uncompressed bytes from the compressed file. If
1369 the input file is not in gzip format, gzread copies the given number of
1370 bytes into the buffer directly from the file.
1372 After reaching the end of a gzip stream in the input, gzread will continue
1373 to read, looking for another gzip stream. Any number of gzip streams may be
1374 concatenated in the input file, and will all be decompressed by gzread().
1375 If something other than a gzip stream is encountered after a gzip stream,
1376 that remaining trailing garbage is ignored (and no error is returned).
1378 gzread can be used to read a gzip file that is being concurrently written.
1379 Upon reaching the end of the input, gzread will return with the available
1380 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1381 gzclearerr can be used to clear the end of file indicator in order to permit
1382 gzread to be tried again. Z_OK indicates that a gzip stream was completed
1383 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1384 middle of a gzip stream. Note that gzread does not return -1 in the event
1385 of an incomplete gzip stream. This error is deferred until gzclose(), which
1386 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1387 stream. Alternatively, gzerror can be used before gzclose to detect this
1390 gzread returns the number of uncompressed bytes actually read, less than
1391 len for end of file, or -1 for error.
1394 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1395 voidpc buf, unsigned len));
1397 Writes the given number of uncompressed bytes into the compressed file.
1398 gzwrite returns the number of uncompressed bytes written or 0 in case of
1402 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1404 Converts, formats, and writes the arguments to the compressed file under
1405 control of the format string, as in fprintf. gzprintf returns the number of
1406 uncompressed bytes actually written, or a negative zlib error code in case
1407 of error. The number of uncompressed bytes written is limited to 8191, or
1408 one less than the buffer size given to gzbuffer(). The caller should assure
1409 that this limit is not exceeded. If it is exceeded, then gzprintf() will
1410 return an error (0) with nothing written. In this case, there may also be a
1411 buffer overflow with unpredictable consequences, which is possible only if
1412 zlib was compiled with the insecure functions sprintf() or vsprintf()
1413 because the secure snprintf() or vsnprintf() functions were not available.
1414 This can be determined using zlibCompileFlags().
1417 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1419 Writes the given null-terminated string to the compressed file, excluding
1420 the terminating null character.
1422 gzputs returns the number of characters written, or -1 in case of error.
1425 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1427 Reads bytes from the compressed file until len-1 characters are read, or a
1428 newline character is read and transferred to buf, or an end-of-file
1429 condition is encountered. If any characters are read or if len == 1, the
1430 string is terminated with a null character. If no characters are read due
1431 to an end-of-file or len < 1, then the buffer is left untouched.
1433 gzgets returns buf which is a null-terminated string, or it returns NULL
1434 for end-of-file or in case of error. If there was an error, the contents at
1435 buf are indeterminate.
1438 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1440 Writes c, converted to an unsigned char, into the compressed file. gzputc
1441 returns the value that was written, or -1 in case of error.
1444 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1446 Reads one byte from the compressed file. gzgetc returns this byte or -1
1447 in case of end of file or error. This is implemented as a macro for speed.
1448 As such, it does not do all of the checking the other functions do. I.e.
1449 it does not check to see if file is NULL, nor whether the structure file
1450 points to has been clobbered or not.
1453 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1455 Push one character back onto the stream to be read as the first character
1456 on the next read. At least one character of push-back is allowed.
1457 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1458 fail if c is -1, and may fail if a character has been pushed but not read
1459 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1460 output buffer size of pushed characters is allowed. (See gzbuffer above.)
1461 The pushed character will be discarded if the stream is repositioned with
1462 gzseek() or gzrewind().
1465 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1467 Flushes all pending output into the compressed file. The parameter flush
1468 is as in the deflate() function. The return value is the zlib error number
1469 (see function gzerror below). gzflush is only permitted when writing.
1471 If the flush parameter is Z_FINISH, the remaining data is written and the
1472 gzip stream is completed in the output. If gzwrite() is called again, a new
1473 gzip stream will be started in the output. gzread() is able to read such
1474 concatenated gzip streams.
1476 gzflush should be called only when strictly necessary because it will
1477 degrade compression if called too often.
1481 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1482 z_off_t offset, int whence));
1484 Sets the starting position for the next gzread or gzwrite on the given
1485 compressed file. The offset represents a number of bytes in the
1486 uncompressed data stream. The whence parameter is defined as in lseek(2);
1487 the value SEEK_END is not supported.
1489 If the file is opened for reading, this function is emulated but can be
1490 extremely slow. If the file is opened for writing, only forward seeks are
1491 supported; gzseek then compresses a sequence of zeroes up to the new
1494 gzseek returns the resulting offset location as measured in bytes from
1495 the beginning of the uncompressed stream, or -1 in case of error, in
1496 particular if the file is opened for writing and the new starting position
1497 would be before the current position.
1500 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1502 Rewinds the given file. This function is supported only for reading.
1504 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1508 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1510 Returns the starting position for the next gzread or gzwrite on the given
1511 compressed file. This position represents a number of bytes in the
1512 uncompressed data stream, and is zero when starting, even if appending or
1513 reading a gzip stream from the middle of a file using gzdopen().
1515 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1519 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1521 Returns the current offset in the file being read or written. This offset
1522 includes the count of bytes that precede the gzip stream, for example when
1523 appending or when using gzdopen() for reading. When reading, the offset
1524 does not include as yet unused buffered input. This information can be used
1525 for a progress indicator. On error, gzoffset() returns -1.
1528 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1530 Returns true (1) if the end-of-file indicator has been set while reading,
1531 false (0) otherwise. Note that the end-of-file indicator is set only if the
1532 read tried to go past the end of the input, but came up short. Therefore,
1533 just like feof(), gzeof() may return false even if there is no more data to
1534 read, in the event that the last read request was for the exact number of
1535 bytes remaining in the input file. This will happen if the input file size
1536 is an exact multiple of the buffer size.
1538 If gzeof() returns true, then the read functions will return no more data,
1539 unless the end-of-file indicator is reset by gzclearerr() and the input file
1540 has grown since the previous end of file was detected.
1543 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1545 Returns true (1) if file is being copied directly while reading, or false
1546 (0) if file is a gzip stream being decompressed.
1548 If the input file is empty, gzdirect() will return true, since the input
1549 does not contain a gzip stream.
1551 If gzdirect() is used immediately after gzopen() or gzdopen() it will
1552 cause buffers to be allocated to allow reading the file to determine if it
1553 is a gzip file. Therefore if gzbuffer() is used, it should be called before
1556 When writing, gzdirect() returns true (1) if transparent writing was
1557 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1558 gzdirect() is not needed when writing. Transparent writing must be
1559 explicitly requested, so the application already knows the answer. When
1560 linking statically, using gzdirect() will include all of the zlib code for
1561 gzip file reading and decompression, which may not be desired.)
1564 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1566 Flushes all pending output if necessary, closes the compressed file and
1567 deallocates the (de)compression state. Note that once file is closed, you
1568 cannot call gzerror with file, since its structures have been deallocated.
1569 gzclose must not be called more than once on the same file, just as free
1570 must not be called more than once on the same allocation.
1572 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1573 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1574 last read ended in the middle of a gzip stream, or Z_OK on success.
1577 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1578 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1580 Same as gzclose(), but gzclose_r() is only for use when reading, and
1581 gzclose_w() is only for use when writing or appending. The advantage to
1582 using these instead of gzclose() is that they avoid linking in zlib
1583 compression or decompression code that is not used when only reading or only
1584 writing respectively. If gzclose() is used, then both compression and
1585 decompression code will be included the application when linking to a static
1589 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1591 Returns the error message for the last error which occurred on the given
1592 compressed file. errnum is set to zlib error number. If an error occurred
1593 in the file system and not in the compression library, errnum is set to
1594 Z_ERRNO and the application may consult errno to get the exact error code.
1596 The application must not modify the returned string. Future calls to
1597 this function may invalidate the previously returned string. If file is
1598 closed, then the string previously returned by gzerror will no longer be
1601 gzerror() should be used to distinguish errors from end-of-file for those
1602 functions above that do not distinguish those cases in their return values.
1605 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1607 Clears the error and end-of-file flags for file. This is analogous to the
1608 clearerr() function in stdio. This is useful for continuing to read a gzip
1609 file that is being written concurrently.
1612 #endif /* !Z_SOLO */
1614 /* checksum functions */
1617 These functions are not related to compression but are exported
1618 anyway because they might be useful in applications using the compression
1622 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1624 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1625 return the updated checksum. If buf is Z_NULL, this function returns the
1626 required initial value for the checksum.
1628 An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1633 uLong adler = adler32(0L, Z_NULL, 0);
1635 while (read_buffer(buffer, length) != EOF) {
1636 adler = adler32(adler, buffer, length);
1638 if (adler != original_adler) error();
1642 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1645 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1646 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1647 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1648 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1649 that the z_off_t type (like off_t) is a signed integer. If len2 is
1650 negative, the result has no meaning or utility.
1653 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1655 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1656 updated CRC-32. If buf is Z_NULL, this function returns the required
1657 initial value for the crc. Pre- and post-conditioning (one's complement) is
1658 performed within this function so it shouldn't be done by the application.
1662 uLong crc = crc32(0L, Z_NULL, 0);
1664 while (read_buffer(buffer, length) != EOF) {
1665 crc = crc32(crc, buffer, length);
1667 if (crc != original_crc) error();
1671 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1673 Combine two CRC-32 check values into one. For two sequences of bytes,
1674 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1675 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1676 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1681 /* various hacks, don't look :) */
1683 /* deflateInit and inflateInit are macros to allow checking the zlib version
1684 * and the compiler's view of z_stream:
1686 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1687 const char *version, int stream_size));
1688 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1689 const char *version, int stream_size));
1690 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1691 int windowBits, int memLevel,
1692 int strategy, const char *version,
1694 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1695 const char *version, int stream_size));
1696 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1697 unsigned char FAR *window,
1698 const char *version,
1700 #define deflateInit(strm, level) \
1701 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1702 #define inflateInit(strm) \
1703 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1704 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1705 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1706 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1707 #define inflateInit2(strm, windowBits) \
1708 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1709 (int)sizeof(z_stream))
1710 #define inflateBackInit(strm, windowBits, window) \
1711 inflateBackInit_((strm), (windowBits), (window), \
1712 ZLIB_VERSION, (int)sizeof(z_stream))
1716 /* gzgetc() macro and its supporting function and exposed data structure. Note
1717 * that the real internal state is much larger than the exposed structure.
1718 * This abbreviated structure exposes just enough for the gzgetc() macro. The
1719 * user should not mess with these exposed elements, since their names or
1720 * behavior could change in the future, perhaps even capriciously. They can
1721 * only be used by the gzgetc() macro. You have been warned.
1725 unsigned char *next;
1728 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */
1731 # define z_gzgetc(g) \
1732 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1734 # define gzgetc(g) \
1735 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1738 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1739 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1740 * both are true, the application gets the *64 functions, and the regular
1741 * functions are changed to 64 bits) -- in case these are set on systems
1742 * without large file support, _LFS64_LARGEFILE must also be true
1745 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1746 ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1747 ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1748 ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1749 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1750 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1753 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1754 # ifdef Z_PREFIX_SET
1755 # define z_gzopen z_gzopen64
1756 # define z_gzseek z_gzseek64
1757 # define z_gztell z_gztell64
1758 # define z_gzoffset z_gzoffset64
1759 # define z_adler32_combine z_adler32_combine64
1760 # define z_crc32_combine z_crc32_combine64
1762 # define gzopen gzopen64
1763 # define gzseek gzseek64
1764 # define gztell gztell64
1765 # define gzoffset gzoffset64
1766 # define adler32_combine adler32_combine64
1767 # define crc32_combine crc32_combine64
1770 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1771 ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1772 ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1773 ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1774 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1775 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1778 ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1779 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1780 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1781 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1782 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1783 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1788 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1789 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1791 #endif /* !Z_SOLO */
1793 /* undocumented functions */
1794 ZEXTERN const char * ZEXPORT zError OF((int));
1795 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1796 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void));
1797 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1798 ZEXTERN int ZEXPORT inflateValidate OF((z_streamp, int));
1799 ZEXTERN unsigned long ZEXPORT inflateCodesUsed OF ((z_streamp));
1800 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1801 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1802 #if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(Z_SOLO)
1803 ZEXTERN gzFile ZEXPORT gzopen_w OF((const wchar_t *path,
1806 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1808 ZEXTERN int ZEXPORTVA gzvprintf Z_ARG((gzFile file,