1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.5.2, September xxth, 2011
4 Copyright (C) 1995-2011 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 "1.2.5.2-motley"
41 #define ZLIB_VERNUM 0x1252
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 2
44 #define ZLIB_VER_REVISION 5
45 #define ZLIB_VER_SUBREVISION 2
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 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 */
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) */
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
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
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).
165 #define Z_PARTIAL_FLUSH 1
166 #define Z_SYNC_FLUSH 2
167 #define Z_FULL_FLUSH 3
171 /* Allowed flush values; see deflate() and inflate() below for details */
174 #define Z_STREAM_END 1
175 #define Z_NEED_DICT 2
177 #define Z_STREAM_ERROR (-2)
178 #define Z_DATA_ERROR (-3)
179 #define Z_MEM_ERROR (-4)
180 #define Z_BUF_ERROR (-5)
181 #define Z_VERSION_ERROR (-6)
182 /* Return codes for the compression/decompression functions. Negative values
183 * are errors, positive values are used for special but normal events.
186 #define Z_NO_COMPRESSION 0
187 #define Z_BEST_SPEED 1
188 #define Z_BEST_COMPRESSION 9
189 #define Z_DEFAULT_COMPRESSION (-1)
190 /* compression levels */
193 #define Z_HUFFMAN_ONLY 2
196 #define Z_DEFAULT_STRATEGY 0
197 /* compression strategy; see deflateInit2() below for details */
201 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
203 /* Possible values of the data_type field (though see inflate()) */
206 /* The deflate compression method (the only one supported in this version) */
208 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
210 #define zlib_version zlibVersion()
211 /* for compatibility with versions < 1.0.2 */
214 /* basic functions */
216 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
217 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
218 If the first character differs, the library code actually used is not
219 compatible with the zlib.h header file used by the application. This check
220 is automatically made by deflateInit and inflateInit.
224 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
226 Initializes the internal stream state for compression. The fields
227 zalloc, zfree and opaque must be initialized before by the caller. If
228 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
229 allocation functions.
231 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
232 1 gives best speed, 9 gives best compression, 0 gives no compression at all
233 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
234 requests a default compromise between speed and compression (currently
235 equivalent to level 6).
237 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
238 memory, Z_STREAM_ERROR if level is not a valid compression level, or
239 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
240 with the version assumed by the caller (ZLIB_VERSION). msg is set to null
241 if there is no error message. deflateInit does not perform any compression:
242 this will be done by deflate().
246 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
248 deflate compresses as much data as possible, and stops when the input
249 buffer becomes empty or the output buffer becomes full. It may introduce
250 some output latency (reading input without producing any output) except when
253 The detailed semantics are as follows. deflate performs one or both of the
256 - Compress more input starting at next_in and update next_in and avail_in
257 accordingly. If not all input can be processed (because there is not
258 enough room in the output buffer), next_in and avail_in are updated and
259 processing will resume at this point for the next call of deflate().
261 - Provide more output starting at next_out and update next_out and avail_out
262 accordingly. This action is forced if the parameter flush is non zero.
263 Forcing flush frequently degrades the compression ratio, so this parameter
264 should be set only when necessary (in interactive applications). Some
265 output may be provided even if flush is not set.
267 Before the call of deflate(), the application should ensure that at least
268 one of the actions is possible, by providing more input and/or consuming more
269 output, and updating avail_in or avail_out accordingly; avail_out should
270 never be zero before the call. The application can consume the compressed
271 output when it wants, for example when the output buffer is full (avail_out
272 == 0), or after each call of deflate(). If deflate returns Z_OK and with
273 zero avail_out, it must be called again after making room in the output
274 buffer because there might be more output pending.
276 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
277 decide how much data to accumulate before producing output, in order to
278 maximize compression.
280 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
281 flushed to the output buffer and the output is aligned on a byte boundary, so
282 that the decompressor can get all input data available so far. (In
283 particular avail_in is zero after the call if enough output space has been
284 provided before the call.) Flushing may degrade compression for some
285 compression algorithms and so it should be used only when necessary. This
286 completes the current deflate block and follows it with an empty stored block
287 that is three bits plus filler bits to the next byte, followed by four bytes
290 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
291 output buffer, but the output is not aligned to a byte boundary. All of the
292 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
293 This completes the current deflate block and follows it with an empty fixed
294 codes block that is 10 bits long. This assures that enough bytes are output
295 in order for the decompressor to finish the block before the empty fixed code
298 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
299 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
300 seven bits of the current block are held to be written as the next byte after
301 the next deflate block is completed. In this case, the decompressor may not
302 be provided enough bits at this point in order to complete decompression of
303 the data provided so far to the compressor. It may need to wait for the next
304 block to be emitted. This is for advanced applications that need to control
305 the emission of deflate blocks.
307 If flush is set to Z_FULL_FLUSH, all output is flushed as with
308 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
309 restart from this point if previous compressed data has been damaged or if
310 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
313 If deflate returns with avail_out == 0, this function must be called again
314 with the same value of the flush parameter and more output space (updated
315 avail_out), until the flush is complete (deflate returns with non-zero
316 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
317 avail_out is greater than six to avoid repeated flush markers due to
318 avail_out == 0 on return.
320 If the parameter flush is set to Z_FINISH, pending input is processed,
321 pending output is flushed and deflate returns with Z_STREAM_END if there was
322 enough output space; if deflate returns with Z_OK, this function must be
323 called again with Z_FINISH and more output space (updated avail_out) but no
324 more input data, until it returns with Z_STREAM_END or an error. After
325 deflate has returned Z_STREAM_END, the only possible operations on the stream
326 are deflateReset or deflateEnd.
328 Z_FINISH can be used immediately after deflateInit if all the compression
329 is to be done in a single step. In this case, avail_out must be at least the
330 value returned by deflateBound (see below). Then deflate is guaranteed to
331 return Z_STREAM_END. If not enough output space is provided, deflate will
332 not return Z_STREAM_END, and it must be called again as described above.
334 deflate() sets strm->adler to the adler32 checksum of all input read
335 so far (that is, total_in bytes).
337 deflate() may update strm->data_type if it can make a good guess about
338 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
339 binary. This field is only for information purposes and does not affect the
340 compression algorithm in any manner.
342 deflate() returns Z_OK if some progress has been made (more input
343 processed or more output produced), Z_STREAM_END if all input has been
344 consumed and all output has been produced (only when flush is set to
345 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
346 if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
347 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
348 fatal, and deflate() can be called again with more input and more output
349 space to continue compressing.
353 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
355 All dynamically allocated data structures for this stream are freed.
356 This function discards any unprocessed input and does not flush any pending
359 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
360 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
361 prematurely (some input or output was discarded). In the error case, msg
362 may be set but then points to a static string (which must not be
368 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
370 Initializes the internal stream state for decompression. The fields
371 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
372 the caller. If next_in is not Z_NULL and avail_in is large enough (the
373 exact value depends on the compression method), inflateInit determines the
374 compression method from the zlib header and allocates all data structures
375 accordingly; otherwise the allocation will be deferred to the first call of
376 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
377 use default allocation functions.
379 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
380 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
381 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
382 invalid, such as a null pointer to the structure. msg is set to null if
383 there is no error message. inflateInit does not perform any decompression
384 apart from possibly reading the zlib header if present: actual decompression
385 will be done by inflate(). (So next_in and avail_in may be modified, but
386 next_out and avail_out are unused and unchanged.) The current implementation
387 of inflateInit() does not process any header information -- that is deferred
388 until inflate() is called.
392 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
394 inflate decompresses as much data as possible, and stops when the input
395 buffer becomes empty or the output buffer becomes full. It may introduce
396 some output latency (reading input without producing any output) except when
399 The detailed semantics are as follows. inflate performs one or both of the
402 - Decompress more input starting at next_in and update next_in and avail_in
403 accordingly. If not all input can be processed (because there is not
404 enough room in the output buffer), next_in is updated and processing will
405 resume at this point for the next call of inflate().
407 - Provide more output starting at next_out and update next_out and avail_out
408 accordingly. inflate() provides as much output as possible, until there is
409 no more input data or no more space in the output buffer (see below about
410 the flush parameter).
412 Before the call of inflate(), the application should ensure that at least
413 one of the actions is possible, by providing more input and/or consuming more
414 output, and updating the next_* and avail_* values accordingly. The
415 application can consume the uncompressed output when it wants, for example
416 when the output buffer is full (avail_out == 0), or after each call of
417 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
418 called again after making room in the output buffer because there might be
421 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
422 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
423 output as possible to the output buffer. Z_BLOCK requests that inflate()
424 stop if and when it gets to the next deflate block boundary. When decoding
425 the zlib or gzip format, this will cause inflate() to return immediately
426 after the header and before the first block. When doing a raw inflate,
427 inflate() will go ahead and process the first block, and will return when it
428 gets to the end of that block, or when it runs out of data.
430 The Z_BLOCK option assists in appending to or combining deflate streams.
431 Also to assist in this, on return inflate() will set strm->data_type to the
432 number of unused bits in the last byte taken from strm->next_in, plus 64 if
433 inflate() is currently decoding the last block in the deflate stream, plus
434 128 if inflate() returned immediately after decoding an end-of-block code or
435 decoding the complete header up to just before the first byte of the deflate
436 stream. The end-of-block will not be indicated until all of the uncompressed
437 data from that block has been written to strm->next_out. The number of
438 unused bits may in general be greater than seven, except when bit 7 of
439 data_type is set, in which case the number of unused bits will be less than
440 eight. data_type is set as noted here every time inflate() returns for all
441 flush options, and so can be used to determine the amount of currently
442 consumed input in bits.
444 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
445 end of each deflate block header is reached, before any actual data in that
446 block is decoded. This allows the caller to determine the length of the
447 deflate block header for later use in random access within a deflate block.
448 256 is added to the value of strm->data_type when inflate() returns
449 immediately after reaching the end of the deflate block header.
451 inflate() should normally be called until it returns Z_STREAM_END or an
452 error. However if all decompression is to be performed in a single step (a
453 single call of inflate), the parameter flush should be set to Z_FINISH. In
454 this case all pending input is processed and all pending output is flushed;
455 avail_out must be large enough to hold all the uncompressed data. (The size
456 of the uncompressed data may have been saved by the compressor for this
457 purpose.) The next operation on this stream must be inflateEnd to deallocate
458 the decompression state. The use of Z_FINISH is never required, but can be
459 used to inform inflate that a faster approach may be used for the single
462 In this implementation, inflate() always flushes as much output as
463 possible to the output buffer, and always uses the faster approach on the
464 first call. So the only effect of the flush parameter in this implementation
465 is on the return value of inflate(), as noted below, or when it returns early
466 because Z_BLOCK or Z_TREES is used.
468 If a preset dictionary is needed after this call (see inflateSetDictionary
469 below), inflate sets strm->adler to the adler32 checksum of the dictionary
470 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
471 strm->adler to the adler32 checksum of all output produced so far (that is,
472 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
473 below. At the end of the stream, inflate() checks that its computed adler32
474 checksum is equal to that saved by the compressor and returns Z_STREAM_END
475 only if the checksum is correct.
477 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
478 deflate data. The header type is detected automatically, if requested when
479 initializing with inflateInit2(). Any information contained in the gzip
480 header is not retained, so applications that need that information should
481 instead use raw inflate, see inflateInit2() below, or inflateBack() and
482 perform their own processing of the gzip header and trailer.
484 inflate() returns Z_OK if some progress has been made (more input processed
485 or more output produced), Z_STREAM_END if the end of the compressed data has
486 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
487 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
488 corrupted (input stream not conforming to the zlib format or incorrect check
489 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
490 next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
491 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
492 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
493 inflate() can be called again with more input and more output space to
494 continue decompressing. If Z_DATA_ERROR is returned, the application may
495 then call inflateSync() to look for a good compression block if a partial
496 recovery of the data is desired.
500 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
502 All dynamically allocated data structures for this stream are freed.
503 This function discards any unprocessed input and does not flush any pending
506 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
507 was inconsistent. In the error case, msg may be set but then points to a
508 static string (which must not be deallocated).
512 /* Advanced functions */
515 The following functions are needed only in some special applications.
519 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
526 This is another version of deflateInit with more compression options. The
527 fields next_in, zalloc, zfree and opaque must be initialized before by the
530 The method parameter is the compression method. It must be Z_DEFLATED in
531 this version of the library.
533 The windowBits parameter is the base two logarithm of the window size
534 (the size of the history buffer). It should be in the range 8..15 for this
535 version of the library. Larger values of this parameter result in better
536 compression at the expense of memory usage. The default value is 15 if
537 deflateInit is used instead.
539 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
540 determines the window size. deflate() will then generate raw deflate data
541 with no zlib header or trailer, and will not compute an adler32 check value.
543 windowBits can also be greater than 15 for optional gzip encoding. Add
544 16 to windowBits to write a simple gzip header and trailer around the
545 compressed data instead of a zlib wrapper. The gzip header will have no
546 file name, no extra data, no comment, no modification time (set to zero), no
547 header crc, and the operating system will be set to 255 (unknown). If a
548 gzip stream is being written, strm->adler is a crc32 instead of an adler32.
550 The memLevel parameter specifies how much memory should be allocated
551 for the internal compression state. memLevel=1 uses minimum memory but is
552 slow and reduces compression ratio; memLevel=9 uses maximum memory for
553 optimal speed. The default value is 8. See zconf.h for total memory usage
554 as a function of windowBits and memLevel.
556 The strategy parameter is used to tune the compression algorithm. Use the
557 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
558 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
559 string match), or Z_RLE to limit match distances to one (run-length
560 encoding). Filtered data consists mostly of small values with a somewhat
561 random distribution. In this case, the compression algorithm is tuned to
562 compress them better. The effect of Z_FILTERED is to force more Huffman
563 coding and less string matching; it is somewhat intermediate between
564 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
565 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
566 strategy parameter only affects the compression ratio but not the
567 correctness of the compressed output even if it is not set appropriately.
568 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
569 decoder for special applications.
571 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
572 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
573 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
574 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
575 set to null if there is no error message. deflateInit2 does not perform any
576 compression: this will be done by deflate().
579 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
580 const Bytef *dictionary,
583 Initializes the compression dictionary from the given byte sequence
584 without producing any compressed output. When using the zlib format, this
585 function must be called immediately after deflateInit, deflateInit2 or
586 deflateReset, and before any call of deflate. When doing raw deflate, this
587 function must be called either before any call of deflate, or immediately
588 after the completion of a deflate block, i.e. after all input has been
589 consumed and all output has been delivered when using any of the flush
590 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
591 compressor and decompressor must use exactly the same dictionary (see
592 inflateSetDictionary).
594 The dictionary should consist of strings (byte sequences) that are likely
595 to be encountered later in the data to be compressed, with the most commonly
596 used strings preferably put towards the end of the dictionary. Using a
597 dictionary is most useful when the data to be compressed is short and can be
598 predicted with good accuracy; the data can then be compressed better than
599 with the default empty dictionary.
601 Depending on the size of the compression data structures selected by
602 deflateInit or deflateInit2, a part of the dictionary may in effect be
603 discarded, for example if the dictionary is larger than the window size
604 provided in deflateInit or deflateInit2. Thus the strings most likely to be
605 useful should be put at the end of the dictionary, not at the front. In
606 addition, the current implementation of deflate will use at most the window
607 size minus 262 bytes of the provided dictionary.
609 Upon return of this function, strm->adler is set to the adler32 value
610 of the dictionary; the decompressor may later use this value to determine
611 which dictionary has been used by the compressor. (The adler32 value
612 applies to the whole dictionary even if only a subset of the dictionary is
613 actually used by the compressor.) If a raw deflate was requested, then the
614 adler32 value is not computed and strm->adler is not set.
616 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
617 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
618 inconsistent (for example if deflate has already been called for this stream
619 or if not at a block boundary for raw deflate). deflateSetDictionary does
620 not perform any compression: this will be done by deflate().
623 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
626 Sets the destination stream as a complete copy of the source stream.
628 This function can be useful when several compression strategies will be
629 tried, for example when there are several ways of pre-processing the input
630 data with a filter. The streams that will be discarded should then be freed
631 by calling deflateEnd. Note that deflateCopy duplicates the internal
632 compression state which can be quite large, so this strategy is slow and can
633 consume lots of memory.
635 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
636 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
637 (such as zalloc being Z_NULL). msg is left unchanged in both source and
641 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
643 This function is equivalent to deflateEnd followed by deflateInit,
644 but does not free and reallocate all the internal compression state. The
645 stream will keep the same compression level and any other attributes that
646 may have been set by deflateInit2.
648 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
649 stream state was inconsistent (such as zalloc or state being Z_NULL).
652 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
656 Dynamically update the compression level and compression strategy. The
657 interpretation of level and strategy is as in deflateInit2. This can be
658 used to switch between compression and straight copy of the input data, or
659 to switch to a different kind of input data requiring a different strategy.
660 If the compression level is changed, the input available so far is
661 compressed with the old level (and may be flushed); the new level will take
662 effect only at the next call of deflate().
664 Before the call of deflateParams, the stream state must be set as for
665 a call of deflate(), since the currently available input may have to be
666 compressed and flushed. In particular, strm->avail_out must be non-zero.
668 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
669 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
670 strm->avail_out was zero.
673 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
679 Fine tune deflate's internal compression parameters. This should only be
680 used by someone who understands the algorithm used by zlib's deflate for
681 searching for the best matching string, and even then only by the most
682 fanatic optimizer trying to squeeze out the last compressed bit for their
683 specific input data. Read the deflate.c source code for the meaning of the
684 max_lazy, good_length, nice_length, and max_chain parameters.
686 deflateTune() can be called after deflateInit() or deflateInit2(), and
687 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
690 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
693 deflateBound() returns an upper bound on the compressed size after
694 deflation of sourceLen bytes. It must be called after deflateInit() or
695 deflateInit2(), and after deflateSetHeader(), if used. This would be used
696 to allocate an output buffer for deflation in a single pass, and so would be
697 called before deflate(). If that first deflate() call is provided the
698 sourceLen input bytes, an output buffer allocated to the size returned by
699 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
700 to return Z_STREAM_END. Note that it is possible for the compressed size to
701 be larger than the value returned by deflateBound() if flush options other
702 than Z_FINISH or Z_NO_FLUSH are used.
705 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
709 deflatePending() returns the number of bytes and bits of output that have
710 been generated, but not yet provided in the available output. The bytes not
711 provided would be due to the available output space having being consumed.
712 The number of bits of output not provided are between 0 and 7, where they
713 await more bits to join them in order to fill out a full byte.
715 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
716 stream state was inconsistent.
719 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
723 deflatePrime() inserts bits in the deflate output stream. The intent
724 is that this function is used to start off the deflate output with the bits
725 leftover from a previous deflate stream when appending to it. As such, this
726 function can only be used for raw deflate, and must be used before the first
727 deflate() call after a deflateInit2() or deflateReset(). bits must be less
728 than or equal to 16, and that many of the least significant bits of value
729 will be inserted in the output.
731 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
732 stream state was inconsistent.
735 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
738 deflateSetHeader() provides gzip header information for when a gzip
739 stream is requested by deflateInit2(). deflateSetHeader() may be called
740 after deflateInit2() or deflateReset() and before the first call of
741 deflate(). The text, time, os, extra field, name, and comment information
742 in the provided gz_header structure are written to the gzip header (xflag is
743 ignored -- the extra flags are set according to the compression level). The
744 caller must assure that, if not Z_NULL, name and comment are terminated with
745 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
746 available there. If hcrc is true, a gzip header crc is included. Note that
747 the current versions of the command-line version of gzip (up through version
748 1.3.x) do not support header crc's, and will report that it is a "multi-part
749 gzip file" and give up.
751 If deflateSetHeader is not used, the default gzip header has text false,
752 the time set to zero, and os set to 255, with no extra, name, or comment
753 fields. The gzip header is returned to the default state by deflateReset().
755 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
756 stream state was inconsistent.
760 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
763 This is another version of inflateInit with an extra parameter. The
764 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
765 before by the caller.
767 The windowBits parameter is the base two logarithm of the maximum window
768 size (the size of the history buffer). It should be in the range 8..15 for
769 this version of the library. The default value is 15 if inflateInit is used
770 instead. windowBits must be greater than or equal to the windowBits value
771 provided to deflateInit2() while compressing, or it must be equal to 15 if
772 deflateInit2() was not used. If a compressed stream with a larger window
773 size is given as input, inflate() will return with the error code
774 Z_DATA_ERROR instead of trying to allocate a larger window.
776 windowBits can also be zero to request that inflate use the window size in
777 the zlib header of the compressed stream.
779 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
780 determines the window size. inflate() will then process raw deflate data,
781 not looking for a zlib or gzip header, not generating a check value, and not
782 looking for any check values for comparison at the end of the stream. This
783 is for use with other formats that use the deflate compressed data format
784 such as zip. Those formats provide their own check values. If a custom
785 format is developed using the raw deflate format for compressed data, it is
786 recommended that a check value such as an adler32 or a crc32 be applied to
787 the uncompressed data as is done in the zlib, gzip, and zip formats. For
788 most applications, the zlib format should be used as is. Note that comments
789 above on the use in deflateInit2() applies to the magnitude of windowBits.
791 windowBits can also be greater than 15 for optional gzip decoding. Add
792 32 to windowBits to enable zlib and gzip decoding with automatic header
793 detection, or add 16 to decode only the gzip format (the zlib format will
794 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
795 crc32 instead of an adler32.
797 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
798 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
799 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
800 invalid, such as a null pointer to the structure. msg is set to null if
801 there is no error message. inflateInit2 does not perform any decompression
802 apart from possibly reading the zlib header if present: actual decompression
803 will be done by inflate(). (So next_in and avail_in may be modified, but
804 next_out and avail_out are unused and unchanged.) The current implementation
805 of inflateInit2() does not process any header information -- that is
806 deferred until inflate() is called.
809 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
810 const Bytef *dictionary,
813 Initializes the decompression dictionary from the given uncompressed byte
814 sequence. This function must be called immediately after a call of inflate,
815 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
816 can be determined from the adler32 value returned by that call of inflate.
817 The compressor and decompressor must use exactly the same dictionary (see
818 deflateSetDictionary). For raw inflate, this function can be called at any
819 time to set the dictionary. If the provided dictionary is smaller than the
820 window and there is already data in the window, then the provided dictionary
821 will amend what's there. The application must insure that the dictionary
822 that was used for compression is provided.
824 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
825 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
826 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
827 expected one (incorrect adler32 value). inflateSetDictionary does not
828 perform any decompression: this will be done by subsequent calls of
832 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
834 Skips invalid compressed data until a possible full flush point (see above
835 for the description of deflate with Z_FULL_FLUSH) can be found, or until all
836 available input is skipped. No output is provided.
838 inflateSync searches for a 00 00 FF FF pattern in the compressed data.
839 All full flush points have this pattern, but not all occurences of this
840 pattern are full flush points.
842 inflateSync returns Z_OK if a possible full flush point has been found,
843 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
844 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
845 In the success case, the application may save the current current value of
846 total_in which indicates where valid compressed data was found. In the
847 error case, the application may repeatedly call inflateSync, providing more
848 input each time, until success or end of the input data.
851 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
854 Sets the destination stream as a complete copy of the source stream.
856 This function can be useful when randomly accessing a large stream. The
857 first pass through the stream can periodically record the inflate state,
858 allowing restarting inflate at those points when randomly accessing the
861 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
862 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
863 (such as zalloc being Z_NULL). msg is left unchanged in both source and
867 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
869 This function is equivalent to inflateEnd followed by inflateInit,
870 but does not free and reallocate all the internal decompression state. The
871 stream will keep attributes that may have been set by inflateInit2.
873 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
874 stream state was inconsistent (such as zalloc or state being Z_NULL).
877 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
880 This function is the same as inflateReset, but it also permits changing
881 the wrap and window size requests. The windowBits parameter is interpreted
882 the same as it is for inflateInit2.
884 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
885 stream state was inconsistent (such as zalloc or state being Z_NULL), or if
886 the windowBits parameter is invalid.
889 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
893 This function inserts bits in the inflate input stream. The intent is
894 that this function is used to start inflating at a bit position in the
895 middle of a byte. The provided bits will be used before any bytes are used
896 from next_in. This function should only be used with raw inflate, and
897 should be used before the first inflate() call after inflateInit2() or
898 inflateReset(). bits must be less than or equal to 16, and that many of the
899 least significant bits of value will be inserted in the input.
901 If bits is negative, then the input stream bit buffer is emptied. Then
902 inflatePrime() can be called again to put bits in the buffer. This is used
903 to clear out bits leftover after feeding inflate a block description prior
904 to feeding inflate codes.
906 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
907 stream state was inconsistent.
910 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
912 This function returns two values, one in the lower 16 bits of the return
913 value, and the other in the remaining upper bits, obtained by shifting the
914 return value down 16 bits. If the upper value is -1 and the lower value is
915 zero, then inflate() is currently decoding information outside of a block.
916 If the upper value is -1 and the lower value is non-zero, then inflate is in
917 the middle of a stored block, with the lower value equaling the number of
918 bytes from the input remaining to copy. If the upper value is not -1, then
919 it is the number of bits back from the current bit position in the input of
920 the code (literal or length/distance pair) currently being processed. In
921 that case the lower value is the number of bytes already emitted for that
924 A code is being processed if inflate is waiting for more input to complete
925 decoding of the code, or if it has completed decoding but is waiting for
926 more output space to write the literal or match data.
928 inflateMark() is used to mark locations in the input data for random
929 access, which may be at bit positions, and to note those cases where the
930 output of a code may span boundaries of random access blocks. The current
931 location in the input stream can be determined from avail_in and data_type
932 as noted in the description for the Z_BLOCK flush parameter for inflate.
934 inflateMark returns the value noted above or -1 << 16 if the provided
935 source stream state was inconsistent.
938 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
941 inflateGetHeader() requests that gzip header information be stored in the
942 provided gz_header structure. inflateGetHeader() may be called after
943 inflateInit2() or inflateReset(), and before the first call of inflate().
944 As inflate() processes the gzip stream, head->done is zero until the header
945 is completed, at which time head->done is set to one. If a zlib stream is
946 being decoded, then head->done is set to -1 to indicate that there will be
947 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
948 used to force inflate() to return immediately after header processing is
949 complete and before any actual data is decompressed.
951 The text, time, xflags, and os fields are filled in with the gzip header
952 contents. hcrc is set to true if there is a header CRC. (The header CRC
953 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
954 contains the maximum number of bytes to write to extra. Once done is true,
955 extra_len contains the actual extra field length, and extra contains the
956 extra field, or that field truncated if extra_max is less than extra_len.
957 If name is not Z_NULL, then up to name_max characters are written there,
958 terminated with a zero unless the length is greater than name_max. If
959 comment is not Z_NULL, then up to comm_max characters are written there,
960 terminated with a zero unless the length is greater than comm_max. When any
961 of extra, name, or comment are not Z_NULL and the respective field is not
962 present in the header, then that field is set to Z_NULL to signal its
963 absence. This allows the use of deflateSetHeader() with the returned
964 structure to duplicate the header. However if those fields are set to
965 allocated memory, then the application will need to save those pointers
966 elsewhere so that they can be eventually freed.
968 If inflateGetHeader is not used, then the header information is simply
969 discarded. The header is always checked for validity, including the header
970 CRC if present. inflateReset() will reset the process to discard the header
971 information. The application would need to call inflateGetHeader() again to
972 retrieve the header from the next gzip stream.
974 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
975 stream state was inconsistent.
979 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
980 unsigned char FAR *window));
982 Initialize the internal stream state for decompression using inflateBack()
983 calls. The fields zalloc, zfree and opaque in strm must be initialized
984 before the call. If zalloc and zfree are Z_NULL, then the default library-
985 derived memory allocation routines are used. windowBits is the base two
986 logarithm of the window size, in the range 8..15. window is a caller
987 supplied buffer of that size. Except for special applications where it is
988 assured that deflate was used with small window sizes, windowBits must be 15
989 and a 32K byte window must be supplied to be able to decompress general
992 See inflateBack() for the usage of these routines.
994 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
995 the parameters are invalid, Z_MEM_ERROR if the internal state could not be
996 allocated, or Z_VERSION_ERROR if the version of the library does not match
997 the version of the header file.
1000 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
1001 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1003 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1004 in_func in, void FAR *in_desc,
1005 out_func out, void FAR *out_desc));
1007 inflateBack() does a raw inflate with a single call using a call-back
1008 interface for input and output. This is more efficient than inflate() for
1009 file i/o applications in that it avoids copying between the output and the
1010 sliding window by simply making the window itself the output buffer. This
1011 function trusts the application to not change the output buffer passed by
1012 the output function, at least until inflateBack() returns.
1014 inflateBackInit() must be called first to allocate the internal state
1015 and to initialize the state with the user-provided window buffer.
1016 inflateBack() may then be used multiple times to inflate a complete, raw
1017 deflate stream with each call. inflateBackEnd() is then called to free the
1020 A raw deflate stream is one with no zlib or gzip header or trailer.
1021 This routine would normally be used in a utility that reads zip or gzip
1022 files and writes out uncompressed files. The utility would decode the
1023 header and process the trailer on its own, hence this routine expects only
1024 the raw deflate stream to decompress. This is different from the normal
1025 behavior of inflate(), which expects either a zlib or gzip header and
1026 trailer around the deflate stream.
1028 inflateBack() uses two subroutines supplied by the caller that are then
1029 called by inflateBack() for input and output. inflateBack() calls those
1030 routines until it reads a complete deflate stream and writes out all of the
1031 uncompressed data, or until it encounters an error. The function's
1032 parameters and return types are defined above in the in_func and out_func
1033 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1034 number of bytes of provided input, and a pointer to that input in buf. If
1035 there is no input available, in() must return zero--buf is ignored in that
1036 case--and inflateBack() will return a buffer error. inflateBack() will call
1037 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
1038 should return zero on success, or non-zero on failure. If out() returns
1039 non-zero, inflateBack() will return with an error. Neither in() nor out()
1040 are permitted to change the contents of the window provided to
1041 inflateBackInit(), which is also the buffer that out() uses to write from.
1042 The length written by out() will be at most the window size. Any non-zero
1043 amount of input may be provided by in().
1045 For convenience, inflateBack() can be provided input on the first call by
1046 setting strm->next_in and strm->avail_in. If that input is exhausted, then
1047 in() will be called. Therefore strm->next_in must be initialized before
1048 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1049 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1050 must also be initialized, and then if strm->avail_in is not zero, input will
1051 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1053 The in_desc and out_desc parameters of inflateBack() is passed as the
1054 first parameter of in() and out() respectively when they are called. These
1055 descriptors can be optionally used to pass any information that the caller-
1056 supplied in() and out() functions need to do their job.
1058 On return, inflateBack() will set strm->next_in and strm->avail_in to
1059 pass back any unused input that was provided by the last in() call. The
1060 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1061 if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1062 in the deflate stream (in which case strm->msg is set to indicate the nature
1063 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1064 In the case of Z_BUF_ERROR, an input or output error can be distinguished
1065 using strm->next_in which will be Z_NULL only if in() returned an error. If
1066 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1067 non-zero. (in() will always be called before out(), so strm->next_in is
1068 assured to be defined if out() returns non-zero.) Note that inflateBack()
1072 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1074 All memory allocated by inflateBackInit() is freed.
1076 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1077 state was inconsistent.
1080 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1081 /* Return flags indicating compile-time options.
1083 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1086 5.4: size of voidpf (pointer)
1087 7.6: size of z_off_t
1089 Compiler, assembler, and debug options:
1091 9: ASMV or ASMINF -- use ASM code
1092 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1095 One-time table building (smaller code, but not thread-safe if true):
1096 12: BUILDFIXED -- build static block decoding tables when needed
1097 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1100 Library content (indicates missing functionality):
1101 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1102 deflate code when not needed)
1103 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1104 and decode gzip streams (to avoid linking crc code)
1107 Operation variations (changes in library functionality):
1108 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1109 21: FASTEST -- deflate algorithm with only one, lowest compression level
1112 The sprintf variant used by gzprintf (zero is best):
1113 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1114 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1115 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1123 /* utility functions */
1126 The following utility functions are implemented on top of the basic
1127 stream-oriented functions. To simplify the interface, some default options
1128 are assumed (compression level and memory usage, standard memory allocation
1129 functions). The source code of these utility functions can be modified if
1130 you need special options.
1133 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1134 const Bytef *source, uLong sourceLen));
1136 Compresses the source buffer into the destination buffer. sourceLen is
1137 the byte length of the source buffer. Upon entry, destLen is the total size
1138 of the destination buffer, which must be at least the value returned by
1139 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1142 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1143 enough memory, Z_BUF_ERROR if there was not enough room in the output
1147 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1148 const Bytef *source, uLong sourceLen,
1151 Compresses the source buffer into the destination buffer. The level
1152 parameter has the same meaning as in deflateInit. sourceLen is the byte
1153 length of the source buffer. Upon entry, destLen is the total size of the
1154 destination buffer, which must be at least the value returned by
1155 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1158 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1159 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1160 Z_STREAM_ERROR if the level parameter is invalid.
1163 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1165 compressBound() returns an upper bound on the compressed size after
1166 compress() or compress2() on sourceLen bytes. It would be used before a
1167 compress() or compress2() call to allocate the destination buffer.
1170 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1171 const Bytef *source, uLong sourceLen));
1173 Decompresses the source buffer into the destination buffer. sourceLen is
1174 the byte length of the source buffer. Upon entry, destLen is the total size
1175 of the destination buffer, which must be large enough to hold the entire
1176 uncompressed data. (The size of the uncompressed data must have been saved
1177 previously by the compressor and transmitted to the decompressor by some
1178 mechanism outside the scope of this compression library.) Upon exit, destLen
1179 is the actual size of the uncompressed buffer.
1181 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1182 enough memory, Z_BUF_ERROR if there was not enough room in the output
1183 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1184 the case where there is not enough room, uncompress() will fill the output
1185 buffer with the uncompressed data up to that point.
1188 /* gzip file access functions */
1191 This library supports reading and writing files in gzip (.gz) format with
1192 an interface similar to that of stdio, using the functions that start with
1193 "gz". The gzip format is different from the zlib format. gzip is a gzip
1194 wrapper, documented in RFC 1952, wrapped around a deflate stream.
1197 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1200 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1202 Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1203 in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1204 a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1205 compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1206 for fixed code compression as in "wb9F". (See the description of
1207 deflateInit2 for more information about the strategy parameter.) 'T' will
1208 request transparent writing or appending with no compression and not using
1211 "a" can be used instead of "w" to request that the gzip stream that will
1212 be written be appended to the file. "+" will result in an error, since
1213 reading and writing to the same gzip file is not supported.
1215 These functions, as well as gzip, will read and decode a sequence of gzip
1216 streams in a file. The append function of gzopen() can be used to create
1217 such a file. (Also see gzflush() for another way to do this.) When
1218 appending, gzopen does not test whether the file begins with a gzip stream,
1219 nor does it look for the end of the gzip streams to begin appending. gzopen
1220 will simply append a gzip stream to the existing file.
1222 gzopen can be used to read a file which is not in gzip format; in this
1223 case gzread will directly read from the file without decompression. When
1224 reading, this will be detected automatically by looking for the magic two-
1227 gzopen returns NULL if the file could not be opened, if there was
1228 insufficient memory to allocate the gzFile state, or if an invalid mode was
1229 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1230 errno can be checked to determine if the reason gzopen failed was that the
1231 file could not be opened.
1234 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1236 gzdopen associates a gzFile with the file descriptor fd. File descriptors
1237 are obtained from calls like open, dup, creat, pipe or fileno (if the file
1238 has been previously opened with fopen). The mode parameter is as in gzopen.
1240 The next call of gzclose on the returned gzFile will also close the file
1241 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1242 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1243 mode);. The duplicated descriptor should be saved to avoid a leak, since
1244 gzdopen does not close fd if it fails. If you are using fileno() to get the
1245 file descriptor from a FILE *, then you will have to use dup() to avoid
1246 double-close()ing the file descriptor. Both gzclose() and fclose() will
1247 close the associated file descriptor, so they need to have different file
1250 gzdopen returns NULL if there was insufficient memory to allocate the
1251 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1252 provided, or '+' was provided), or if fd is -1. The file descriptor is not
1253 used until the next gz* read, write, seek, or close operation, so gzdopen
1254 will not detect if fd is invalid (unless fd is -1).
1257 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1259 Set the internal buffer size used by this library's functions. The
1260 default buffer size is 8192 bytes. This function must be called after
1261 gzopen() or gzdopen(), and before any other calls that read or write the
1262 file. The buffer memory allocation is always deferred to the first read or
1263 write. Two buffers are allocated, either both of the specified size when
1264 writing, or one of the specified size and the other twice that size when
1265 reading. A larger buffer size of, for example, 64K or 128K bytes will
1266 noticeably increase the speed of decompression (reading).
1268 The new buffer size also affects the maximum length for gzprintf().
1270 gzbuffer() returns 0 on success, or -1 on failure, such as being called
1274 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1276 Dynamically update the compression level or strategy. See the description
1277 of deflateInit2 for the meaning of these parameters.
1279 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1283 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1285 Reads the given number of uncompressed bytes from the compressed file. If
1286 the input file is not in gzip format, gzread copies the given number of
1287 bytes into the buffer directly from the file.
1289 After reaching the end of a gzip stream in the input, gzread will continue
1290 to read, looking for another gzip stream. Any number of gzip streams may be
1291 concatenated in the input file, and will all be decompressed by gzread().
1292 If something other than a gzip stream is encountered after a gzip stream,
1293 that remaining trailing garbage is ignored (and no error is returned).
1295 gzread returns the number of uncompressed bytes actually read, less than
1296 len for end of file, or -1 for error.
1299 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1300 voidpc buf, unsigned len));
1302 Writes the given number of uncompressed bytes into the compressed file.
1303 gzwrite returns the number of uncompressed bytes written or 0 in case of
1307 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1309 Converts, formats, and writes the arguments to the compressed file under
1310 control of the format string, as in fprintf. gzprintf returns the number of
1311 uncompressed bytes actually written, or 0 in case of error. The number of
1312 uncompressed bytes written is limited to 8191, or one less than the buffer
1313 size given to gzbuffer(). The caller should assure that this limit is not
1314 exceeded. If it is exceeded, then gzprintf() will return an error (0) with
1315 nothing written. In this case, there may also be a buffer overflow with
1316 unpredictable consequences, which is possible only if zlib was compiled with
1317 the insecure functions sprintf() or vsprintf() because the secure snprintf()
1318 or vsnprintf() functions were not available. This can be determined using
1322 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1324 Writes the given null-terminated string to the compressed file, excluding
1325 the terminating null character.
1327 gzputs returns the number of characters written, or -1 in case of error.
1330 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1332 Reads bytes from the compressed file until len-1 characters are read, or a
1333 newline character is read and transferred to buf, or an end-of-file
1334 condition is encountered. If any characters are read or if len == 1, the
1335 string is terminated with a null character. If no characters are read due
1336 to an end-of-file or len < 1, then the buffer is left untouched.
1338 gzgets returns buf which is a null-terminated string, or it returns NULL
1339 for end-of-file or in case of error. If there was an error, the contents at
1340 buf are indeterminate.
1343 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1345 Writes c, converted to an unsigned char, into the compressed file. gzputc
1346 returns the value that was written, or -1 in case of error.
1350 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1351 Reads one byte from the compressed file. gzgetc returns this byte or -1
1352 in case of end of file or error. This is implemented as a macro for speed.
1353 As such, it does not do all of the checking the other functions do. I.e.
1354 it does not check to see if file is NULL, nor whether the structure file
1355 points to has been clobbered or not.
1358 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1360 Push one character back onto the stream to be read as the first character
1361 on the next read. At least one character of push-back is allowed.
1362 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1363 fail if c is -1, and may fail if a character has been pushed but not read
1364 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1365 output buffer size of pushed characters is allowed. (See gzbuffer above.)
1366 The pushed character will be discarded if the stream is repositioned with
1367 gzseek() or gzrewind().
1370 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1372 Flushes all pending output into the compressed file. The parameter flush
1373 is as in the deflate() function. The return value is the zlib error number
1374 (see function gzerror below). gzflush is only permitted when writing.
1376 If the flush parameter is Z_FINISH, the remaining data is written and the
1377 gzip stream is completed in the output. If gzwrite() is called again, a new
1378 gzip stream will be started in the output. gzread() is able to read such
1379 concatented gzip streams.
1381 gzflush should be called only when strictly necessary because it will
1382 degrade compression if called too often.
1386 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1387 z_off_t offset, int whence));
1389 Sets the starting position for the next gzread or gzwrite on the given
1390 compressed file. The offset represents a number of bytes in the
1391 uncompressed data stream. The whence parameter is defined as in lseek(2);
1392 the value SEEK_END is not supported.
1394 If the file is opened for reading, this function is emulated but can be
1395 extremely slow. If the file is opened for writing, only forward seeks are
1396 supported; gzseek then compresses a sequence of zeroes up to the new
1399 gzseek returns the resulting offset location as measured in bytes from
1400 the beginning of the uncompressed stream, or -1 in case of error, in
1401 particular if the file is opened for writing and the new starting position
1402 would be before the current position.
1405 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1407 Rewinds the given file. This function is supported only for reading.
1409 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1413 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1415 Returns the starting position for the next gzread or gzwrite on the given
1416 compressed file. This position represents a number of bytes in the
1417 uncompressed data stream, and is zero when starting, even if appending or
1418 reading a gzip stream from the middle of a file using gzdopen().
1420 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1424 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1426 Returns the current offset in the file being read or written. This offset
1427 includes the count of bytes that precede the gzip stream, for example when
1428 appending or when using gzdopen() for reading. When reading, the offset
1429 does not include as yet unused buffered input. This information can be used
1430 for a progress indicator. On error, gzoffset() returns -1.
1433 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1435 Returns true (1) if the end-of-file indicator has been set while reading,
1436 false (0) otherwise. Note that the end-of-file indicator is set only if the
1437 read tried to go past the end of the input, but came up short. Therefore,
1438 just like feof(), gzeof() may return false even if there is no more data to
1439 read, in the event that the last read request was for the exact number of
1440 bytes remaining in the input file. This will happen if the input file size
1441 is an exact multiple of the buffer size.
1443 If gzeof() returns true, then the read functions will return no more data,
1444 unless the end-of-file indicator is reset by gzclearerr() and the input file
1445 has grown since the previous end of file was detected.
1448 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1450 Returns true (1) if file is being copied directly while reading, or false
1451 (0) if file is a gzip stream being decompressed.
1453 If the input file is empty, gzdirect() will return true, since the input
1454 does not contain a gzip stream.
1456 If gzdirect() is used immediately after gzopen() or gzdopen() it will
1457 cause buffers to be allocated to allow reading the file to determine if it
1458 is a gzip file. Therefore if gzbuffer() is used, it should be called before
1461 When writing, gzdirect() returns true (1) if transparent writing was
1462 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1463 gzdirect() is not needed when writing. Transparent writing must be
1464 explicitly requested, so the application already knows the answer. When
1465 linking statically, using gzdirect() will include all of the zlib code for
1466 gzip file reading and decompression, which may not be desired.)
1469 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1471 Flushes all pending output if necessary, closes the compressed file and
1472 deallocates the (de)compression state. Note that once file is closed, you
1473 cannot call gzerror with file, since its structures have been deallocated.
1474 gzclose must not be called more than once on the same file, just as free
1475 must not be called more than once on the same allocation.
1477 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1478 file operation error, Z_MEM_ERROR if out of memory, or Z_OK on success.
1481 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1482 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1484 Same as gzclose(), but gzclose_r() is only for use when reading, and
1485 gzclose_w() is only for use when writing or appending. The advantage to
1486 using these instead of gzclose() is that they avoid linking in zlib
1487 compression or decompression code that is not used when only reading or only
1488 writing respectively. If gzclose() is used, then both compression and
1489 decompression code will be included the application when linking to a static
1493 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1495 Returns the error message for the last error which occurred on the given
1496 compressed file. errnum is set to zlib error number. If an error occurred
1497 in the file system and not in the compression library, errnum is set to
1498 Z_ERRNO and the application may consult errno to get the exact error code.
1500 The application must not modify the returned string. Future calls to
1501 this function may invalidate the previously returned string. If file is
1502 closed, then the string previously returned by gzerror will no longer be
1505 gzerror() should be used to distinguish errors from end-of-file for those
1506 functions above that do not distinguish those cases in their return values.
1509 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1511 Clears the error and end-of-file flags for file. This is analogous to the
1512 clearerr() function in stdio. This is useful for continuing to read a gzip
1513 file that is being written concurrently.
1516 #endif /* !Z_SOLO */
1518 /* checksum functions */
1521 These functions are not related to compression but are exported
1522 anyway because they might be useful in applications using the compression
1526 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1528 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1529 return the updated checksum. If buf is Z_NULL, this function returns the
1530 required initial value for the checksum.
1532 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1537 uLong adler = adler32(0L, Z_NULL, 0);
1539 while (read_buffer(buffer, length) != EOF) {
1540 adler = adler32(adler, buffer, length);
1542 if (adler != original_adler) error();
1546 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1549 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1550 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1551 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1552 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1553 that the z_off_t type (like off_t) is a signed integer. If len2 is
1554 negative, the result has no meaning or utility.
1557 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1559 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1560 updated CRC-32. If buf is Z_NULL, this function returns the required
1561 initial value for the for the crc. Pre- and post-conditioning (one's
1562 complement) is performed within this function so it shouldn't be done by the
1567 uLong crc = crc32(0L, Z_NULL, 0);
1569 while (read_buffer(buffer, length) != EOF) {
1570 crc = crc32(crc, buffer, length);
1572 if (crc != original_crc) error();
1576 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1578 Combine two CRC-32 check values into one. For two sequences of bytes,
1579 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1580 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1581 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1586 /* various hacks, don't look :) */
1588 /* deflateInit and inflateInit are macros to allow checking the zlib version
1589 * and the compiler's view of z_stream:
1591 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1592 const char *version, int stream_size));
1593 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1594 const char *version, int stream_size));
1595 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1596 int windowBits, int memLevel,
1597 int strategy, const char *version,
1599 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1600 const char *version, int stream_size));
1601 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1602 unsigned char FAR *window,
1603 const char *version,
1605 #define deflateInit(strm, level) \
1606 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1607 #define inflateInit(strm) \
1608 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1609 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1610 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1611 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1612 #define inflateInit2(strm, windowBits) \
1613 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1614 (int)sizeof(z_stream))
1615 #define inflateBackInit(strm, windowBits, window) \
1616 inflateBackInit_((strm), (windowBits), (window), \
1617 ZLIB_VERSION, (int)sizeof(z_stream))
1621 /* gzgetc() macro and its supporting function and exposed data structure. Note
1622 * that the real internal state is much larger than the exposed structure.
1623 * This abbreviated structure exposes just enough for the gzgetc() macro. The
1624 * user should not mess with these exposed elements, since their names or
1625 * behavior could change in the future, perhaps even capriciously. They can
1626 * only be used by the gzgetc() macro. You have been warned.
1630 unsigned char *next;
1633 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));
1635 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc_(g))
1637 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1638 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1639 * both are true, the application gets the *64 functions, and the regular
1640 * functions are changed to 64 bits) -- in case these are set on systems
1641 * without large file support, _LFS64_LARGEFILE must also be true
1643 #if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
1644 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1645 ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1646 ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1647 ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1648 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1649 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1652 #if !defined(ZLIB_INTERNAL) && _FILE_OFFSET_BITS-0 == 64 && _LFS64_LARGEFILE-0
1653 # ifdef Z_PREFIX_SET
1654 # define z_gzopen z_gzopen64
1655 # define z_gzseek z_gzseek64
1656 # define z_gztell z_gztell64
1657 # define z_gzoffset z_gzoffset64
1658 # define z_adler32_combine z_adler32_combine64
1659 # define z_crc32_combine z_crc32_combine64
1661 # define gzopen gzopen64
1662 # define gzseek gzseek64
1663 # define gztell gztell64
1664 # define gzoffset gzoffset64
1665 # define adler32_combine adler32_combine64
1666 # define crc32_combine crc32_combine64
1668 # ifndef _LARGEFILE64_SOURCE
1669 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1670 ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1671 ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1672 ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1673 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1674 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1677 ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1678 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1679 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1680 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1681 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1682 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1687 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1688 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1690 #endif /* !Z_SOLO */
1692 /* hack for buggy compilers */
1693 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1694 struct internal_state {int dummy;};
1697 /* undocumented functions */
1698 ZEXTERN const char * ZEXPORT zError OF((int));
1699 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1700 ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1701 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1702 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1703 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1705 ZEXTERN unsigned long ZEXPORT gzflags OF((void));