1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.11, January 15th, 2017
4 Copyright (C) 1995-2017 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 "1.2.11"
41 #define ZLIB_VERNUM 0x12b0
42 #define ZLIB_VER_MAJOR 1
43 #define ZLIB_VER_MINOR 2
44 #define ZLIB_VER_REVISION 11
45 #define ZLIB_VER_SUBREVISION 0
48 The 'zlib' compression library provides in-memory compression and
49 decompression functions, including integrity checks of the uncompressed data.
50 This version of the library supports only one compression method (deflation)
51 but other algorithms will be added later and will have the same stream
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 provided input is not
383 read or consumed. The allocation of a sliding window will be deferred to
384 the first call of inflate (if the decompression does not complete on the
385 first call). If zalloc and zfree are set to Z_NULL, inflateInit updates
386 them to use default allocation functions.
388 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
389 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
390 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
391 invalid, such as a null pointer to the structure. msg is set to null if
392 there is no error message. inflateInit does not perform any decompression.
393 Actual decompression will be done by inflate(). So next_in, and avail_in,
394 next_out, and avail_out are unused and unchanged. The current
395 implementation of inflateInit() does not process any header information --
396 that is deferred until inflate() is called.
400 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
402 inflate decompresses as much data as possible, and stops when the input
403 buffer becomes empty or the output buffer becomes full. It may introduce
404 some output latency (reading input without producing any output) except when
407 The detailed semantics are as follows. inflate performs one or both of the
410 - Decompress more input starting at next_in and update next_in and avail_in
411 accordingly. If not all input can be processed (because there is not
412 enough room in the output buffer), then next_in and avail_in are updated
413 accordingly, and processing will resume at this point for the next call of
416 - Generate more output starting at next_out and update next_out and avail_out
417 accordingly. inflate() provides as much output as possible, until there is
418 no more input data or no more space in the output buffer (see below about
419 the flush parameter).
421 Before the call of inflate(), the application should ensure that at least
422 one of the actions is possible, by providing more input and/or consuming more
423 output, and updating the next_* and avail_* values accordingly. If the
424 caller of inflate() does not provide both available input and available
425 output space, it is possible that there will be no progress made. The
426 application can consume the uncompressed output when it wants, for example
427 when the output buffer is full (avail_out == 0), or after each call of
428 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
429 called again after making room in the output buffer because there might be
432 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
433 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
434 output as possible to the output buffer. Z_BLOCK requests that inflate()
435 stop if and when it gets to the next deflate block boundary. When decoding
436 the zlib or gzip format, this will cause inflate() to return immediately
437 after the header and before the first block. When doing a raw inflate,
438 inflate() will go ahead and process the first block, and will return when it
439 gets to the end of that block, or when it runs out of data.
441 The Z_BLOCK option assists in appending to or combining deflate streams.
442 To assist in this, on return inflate() always sets strm->data_type to the
443 number of unused bits in the last byte taken from strm->next_in, plus 64 if
444 inflate() is currently decoding the last block in the deflate stream, plus
445 128 if inflate() returned immediately after decoding an end-of-block code or
446 decoding the complete header up to just before the first byte of the deflate
447 stream. The end-of-block will not be indicated until all of the uncompressed
448 data from that block has been written to strm->next_out. The number of
449 unused bits may in general be greater than seven, except when bit 7 of
450 data_type is set, in which case the number of unused bits will be less than
451 eight. data_type is set as noted here every time inflate() returns for all
452 flush options, and so can be used to determine the amount of currently
453 consumed input in bits.
455 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
456 end of each deflate block header is reached, before any actual data in that
457 block is decoded. This allows the caller to determine the length of the
458 deflate block header for later use in random access within a deflate block.
459 256 is added to the value of strm->data_type when inflate() returns
460 immediately after reaching the end of the deflate block header.
462 inflate() should normally be called until it returns Z_STREAM_END or an
463 error. However if all decompression is to be performed in a single step (a
464 single call of inflate), the parameter flush should be set to Z_FINISH. In
465 this case all pending input is processed and all pending output is flushed;
466 avail_out must be large enough to hold all of the uncompressed data for the
467 operation to complete. (The size of the uncompressed data may have been
468 saved by the compressor for this purpose.) The use of Z_FINISH is not
469 required to perform an inflation in one step. However it may be used to
470 inform inflate that a faster approach can be used for the single inflate()
471 call. Z_FINISH also informs inflate to not maintain a sliding window if the
472 stream completes, which reduces inflate's memory footprint. If the stream
473 does not complete, either because not all of the stream is provided or not
474 enough output space is provided, then a sliding window will be allocated and
475 inflate() can be called again to continue the operation as if Z_NO_FLUSH had
478 In this implementation, inflate() always flushes as much output as
479 possible to the output buffer, and always uses the faster approach on the
480 first call. So the effects of the flush parameter in this implementation are
481 on the return value of inflate() as noted below, when inflate() returns early
482 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
483 memory for a sliding window when Z_FINISH is used.
485 If a preset dictionary is needed after this call (see inflateSetDictionary
486 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
487 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
488 strm->adler to the Adler-32 checksum of all output produced so far (that is,
489 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
490 below. At the end of the stream, inflate() checks that its computed Adler-32
491 checksum is equal to that saved by the compressor and returns Z_STREAM_END
492 only if the checksum is correct.
494 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
495 deflate data. The header type is detected automatically, if requested when
496 initializing with inflateInit2(). Any information contained in the gzip
497 header is not retained unless inflateGetHeader() is used. When processing
498 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
499 produced so far. The CRC-32 is checked against the gzip trailer, as is the
500 uncompressed length, modulo 2^32.
502 inflate() returns Z_OK if some progress has been made (more input processed
503 or more output produced), Z_STREAM_END if the end of the compressed data has
504 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
505 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
506 corrupted (input stream not conforming to the zlib format or incorrect check
507 value, in which case strm->msg points to a string with a more specific
508 error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
509 next_in or next_out was Z_NULL, or the state was inadvertently written over
510 by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
511 if no progress was possible or if there was not enough room in the output
512 buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
513 inflate() can be called again with more input and more output space to
514 continue decompressing. If Z_DATA_ERROR is returned, the application may
515 then call inflateSync() to look for a good compression block if a partial
516 recovery of the data is to be attempted.
520 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
522 All dynamically allocated data structures for this stream are freed.
523 This function discards any unprocessed input and does not flush any pending
526 inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
531 /* Advanced functions */
534 The following functions are needed only in some special applications.
538 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
545 This is another version of deflateInit with more compression options. The
546 fields next_in, zalloc, zfree and opaque must be initialized before by the
549 The method parameter is the compression method. It must be Z_DEFLATED in
550 this version of the library.
552 The windowBits parameter is the base two logarithm of the window size
553 (the size of the history buffer). It should be in the range 8..15 for this
554 version of the library. Larger values of this parameter result in better
555 compression at the expense of memory usage. The default value is 15 if
556 deflateInit is used instead.
558 For the current implementation of deflate(), a windowBits value of 8 (a
559 window size of 256 bytes) is not supported. As a result, a request for 8
560 will result in 9 (a 512-byte window). In that case, providing 8 to
561 inflateInit2() will result in an error when the zlib header with 9 is
562 checked against the initialization of inflate(). The remedy is to not use 8
563 with deflateInit2() with this initialization, or at least in that case use 9
566 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
567 determines the window size. deflate() will then generate raw deflate data
568 with no zlib header or trailer, and will not compute a check value.
570 windowBits can also be greater than 15 for optional gzip encoding. Add
571 16 to windowBits to write a simple gzip header and trailer around the
572 compressed data instead of a zlib wrapper. The gzip header will have no
573 file name, no extra data, no comment, no modification time (set to zero), no
574 header crc, and the operating system will be set to the appropriate value,
575 if the operating system was determined at compile time. If a gzip stream is
576 being written, strm->adler is a CRC-32 instead of an Adler-32.
578 For raw deflate or gzip encoding, a request for a 256-byte window is
579 rejected as invalid, since only the zlib header provides a means of
580 transmitting the window size to the decompressor.
582 The memLevel parameter specifies how much memory should be allocated
583 for the internal compression state. memLevel=1 uses minimum memory but is
584 slow and reduces compression ratio; memLevel=9 uses maximum memory for
585 optimal speed. The default value is 8. See zconf.h for total memory usage
586 as a function of windowBits and memLevel.
588 The strategy parameter is used to tune the compression algorithm. Use the
589 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
590 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
591 string match), or Z_RLE to limit match distances to one (run-length
592 encoding). Filtered data consists mostly of small values with a somewhat
593 random distribution. In this case, the compression algorithm is tuned to
594 compress them better. The effect of Z_FILTERED is to force more Huffman
595 coding and less string matching; it is somewhat intermediate between
596 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
597 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
598 strategy parameter only affects the compression ratio but not the
599 correctness of the compressed output even if it is not set appropriately.
600 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
601 decoder for special applications.
603 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
604 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
605 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
606 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
607 set to null if there is no error message. deflateInit2 does not perform any
608 compression: this will be done by deflate().
611 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
612 const Bytef *dictionary,
615 Initializes the compression dictionary from the given byte sequence
616 without producing any compressed output. When using the zlib format, this
617 function must be called immediately after deflateInit, deflateInit2 or
618 deflateReset, and before any call of deflate. When doing raw deflate, this
619 function must be called either before any call of deflate, or immediately
620 after the completion of a deflate block, i.e. after all input has been
621 consumed and all output has been delivered when using any of the flush
622 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
623 compressor and decompressor must use exactly the same dictionary (see
624 inflateSetDictionary).
626 The dictionary should consist of strings (byte sequences) that are likely
627 to be encountered later in the data to be compressed, with the most commonly
628 used strings preferably put towards the end of the dictionary. Using a
629 dictionary is most useful when the data to be compressed is short and can be
630 predicted with good accuracy; the data can then be compressed better than
631 with the default empty dictionary.
633 Depending on the size of the compression data structures selected by
634 deflateInit or deflateInit2, a part of the dictionary may in effect be
635 discarded, for example if the dictionary is larger than the window size
636 provided in deflateInit or deflateInit2. Thus the strings most likely to be
637 useful should be put at the end of the dictionary, not at the front. In
638 addition, the current implementation of deflate will use at most the window
639 size minus 262 bytes of the provided dictionary.
641 Upon return of this function, strm->adler is set to the Adler-32 value
642 of the dictionary; the decompressor may later use this value to determine
643 which dictionary has been used by the compressor. (The Adler-32 value
644 applies to the whole dictionary even if only a subset of the dictionary is
645 actually used by the compressor.) If a raw deflate was requested, then the
646 Adler-32 value is not computed and strm->adler is not set.
648 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
649 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
650 inconsistent (for example if deflate has already been called for this stream
651 or if not at a block boundary for raw deflate). deflateSetDictionary does
652 not perform any compression: this will be done by deflate().
655 ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
659 Returns the sliding dictionary being maintained by deflate. dictLength is
660 set to the number of bytes in the dictionary, and that many bytes are copied
661 to dictionary. dictionary must have enough space, where 32768 bytes is
662 always enough. If deflateGetDictionary() is called with dictionary equal to
663 Z_NULL, then only the dictionary length is returned, and nothing is copied.
664 Similary, if dictLength is Z_NULL, then it is not set.
666 deflateGetDictionary() may return a length less than the window size, even
667 when more than the window size in input has been provided. It may return up
668 to 258 bytes less in that case, due to how zlib's implementation of deflate
669 manages the sliding window and lookahead for matches, where matches can be
670 up to 258 bytes long. If the application needs the last window-size bytes of
671 input, then that would need to be saved by the application outside of zlib.
673 deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
674 stream state is inconsistent.
677 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
680 Sets the destination stream as a complete copy of the source stream.
682 This function can be useful when several compression strategies will be
683 tried, for example when there are several ways of pre-processing the input
684 data with a filter. The streams that will be discarded should then be freed
685 by calling deflateEnd. Note that deflateCopy duplicates the internal
686 compression state which can be quite large, so this strategy is slow and can
687 consume lots of memory.
689 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
690 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
691 (such as zalloc being Z_NULL). msg is left unchanged in both source and
695 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
697 This function is equivalent to deflateEnd followed by deflateInit, but
698 does not free and reallocate the internal compression state. The stream
699 will leave the compression level and any other attributes that may have been
702 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
703 stream state was inconsistent (such as zalloc or state being Z_NULL).
706 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
710 Dynamically update the compression level and compression strategy. The
711 interpretation of level and strategy is as in deflateInit2(). This can be
712 used to switch between compression and straight copy of the input data, or
713 to switch to a different kind of input data requiring a different strategy.
714 If the compression approach (which is a function of the level) or the
715 strategy is changed, and if there have been any deflate() calls since the
716 state was initialized or reset, then the input available so far is
717 compressed with the old level and strategy using deflate(strm, Z_BLOCK).
718 There are three approaches for the compression levels 0, 1..3, and 4..9
719 respectively. The new level and strategy will take effect at the next call
722 If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
723 not have enough output space to complete, then the parameter change will not
724 take effect. In this case, deflateParams() can be called again with the
725 same parameters and more output space to try again.
727 In order to assure a change in the parameters on the first try, the
728 deflate stream should be flushed using deflate() with Z_BLOCK or other flush
729 request until strm.avail_out is not zero, before calling deflateParams().
730 Then no more input data should be provided before the deflateParams() call.
731 If this is done, the old level and strategy will be applied to the data
732 compressed before deflateParams(), and the new level and strategy will be
733 applied to the the data compressed after deflateParams().
735 deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
736 state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
737 there was not enough output space to complete the compression of the
738 available input data before a change in the strategy or approach. Note that
739 in the case of a Z_BUF_ERROR, the parameters are not changed. A return
740 value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
741 retried with more output space.
744 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
750 Fine tune deflate's internal compression parameters. This should only be
751 used by someone who understands the algorithm used by zlib's deflate for
752 searching for the best matching string, and even then only by the most
753 fanatic optimizer trying to squeeze out the last compressed bit for their
754 specific input data. Read the deflate.c source code for the meaning of the
755 max_lazy, good_length, nice_length, and max_chain parameters.
757 deflateTune() can be called after deflateInit() or deflateInit2(), and
758 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
761 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
764 deflateBound() returns an upper bound on the compressed size after
765 deflation of sourceLen bytes. It must be called after deflateInit() or
766 deflateInit2(), and after deflateSetHeader(), if used. This would be used
767 to allocate an output buffer for deflation in a single pass, and so would be
768 called before deflate(). If that first deflate() call is provided the
769 sourceLen input bytes, an output buffer allocated to the size returned by
770 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
771 to return Z_STREAM_END. Note that it is possible for the compressed size to
772 be larger than the value returned by deflateBound() if flush options other
773 than Z_FINISH or Z_NO_FLUSH are used.
776 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
780 deflatePending() returns the number of bytes and bits of output that have
781 been generated, but not yet provided in the available output. The bytes not
782 provided would be due to the available output space having being consumed.
783 The number of bits of output not provided are between 0 and 7, where they
784 await more bits to join them in order to fill out a full byte. If pending
785 or bits are Z_NULL, then those values are not set.
787 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
788 stream state was inconsistent.
791 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
795 deflatePrime() inserts bits in the deflate output stream. The intent
796 is that this function is used to start off the deflate output with the bits
797 leftover from a previous deflate stream when appending to it. As such, this
798 function can only be used for raw deflate, and must be used before the first
799 deflate() call after a deflateInit2() or deflateReset(). bits must be less
800 than or equal to 16, and that many of the least significant bits of value
801 will be inserted in the output.
803 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
804 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
805 source stream state was inconsistent.
808 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
811 deflateSetHeader() provides gzip header information for when a gzip
812 stream is requested by deflateInit2(). deflateSetHeader() may be called
813 after deflateInit2() or deflateReset() and before the first call of
814 deflate(). The text, time, os, extra field, name, and comment information
815 in the provided gz_header structure are written to the gzip header (xflag is
816 ignored -- the extra flags are set according to the compression level). The
817 caller must assure that, if not Z_NULL, name and comment are terminated with
818 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
819 available there. If hcrc is true, a gzip header crc is included. Note that
820 the current versions of the command-line version of gzip (up through version
821 1.3.x) do not support header crc's, and will report that it is a "multi-part
822 gzip file" and give up.
824 If deflateSetHeader is not used, the default gzip header has text false,
825 the time set to zero, and os set to 255, with no extra, name, or comment
826 fields. The gzip header is returned to the default state by deflateReset().
828 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
829 stream state was inconsistent.
833 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
836 This is another version of inflateInit with an extra parameter. The
837 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
838 before by the caller.
840 The windowBits parameter is the base two logarithm of the maximum window
841 size (the size of the history buffer). It should be in the range 8..15 for
842 this version of the library. The default value is 15 if inflateInit is used
843 instead. windowBits must be greater than or equal to the windowBits value
844 provided to deflateInit2() while compressing, or it must be equal to 15 if
845 deflateInit2() was not used. If a compressed stream with a larger window
846 size is given as input, inflate() will return with the error code
847 Z_DATA_ERROR instead of trying to allocate a larger window.
849 windowBits can also be zero to request that inflate use the window size in
850 the zlib header of the compressed stream.
852 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
853 determines the window size. inflate() will then process raw deflate data,
854 not looking for a zlib or gzip header, not generating a check value, and not
855 looking for any check values for comparison at the end of the stream. This
856 is for use with other formats that use the deflate compressed data format
857 such as zip. Those formats provide their own check values. If a custom
858 format is developed using the raw deflate format for compressed data, it is
859 recommended that a check value such as an Adler-32 or a CRC-32 be applied to
860 the uncompressed data as is done in the zlib, gzip, and zip formats. For
861 most applications, the zlib format should be used as is. Note that comments
862 above on the use in deflateInit2() applies to the magnitude of windowBits.
864 windowBits can also be greater than 15 for optional gzip decoding. Add
865 32 to windowBits to enable zlib and gzip decoding with automatic header
866 detection, or add 16 to decode only the gzip format (the zlib format will
867 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
868 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see
869 below), inflate() will not automatically decode concatenated gzip streams.
870 inflate() will return Z_STREAM_END at the end of the gzip stream. The state
871 would need to be reset to continue decoding a subsequent gzip stream.
873 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
874 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
875 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
876 invalid, such as a null pointer to the structure. msg is set to null if
877 there is no error message. inflateInit2 does not perform any decompression
878 apart from possibly reading the zlib header if present: actual decompression
879 will be done by inflate(). (So next_in and avail_in may be modified, but
880 next_out and avail_out are unused and unchanged.) The current implementation
881 of inflateInit2() does not process any header information -- that is
882 deferred until inflate() is called.
885 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
886 const Bytef *dictionary,
889 Initializes the decompression dictionary from the given uncompressed byte
890 sequence. This function must be called immediately after a call of inflate,
891 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
892 can be determined from the Adler-32 value returned by that call of inflate.
893 The compressor and decompressor must use exactly the same dictionary (see
894 deflateSetDictionary). For raw inflate, this function can be called at any
895 time to set the dictionary. If the provided dictionary is smaller than the
896 window and there is already data in the window, then the provided dictionary
897 will amend what's there. The application must insure that the dictionary
898 that was used for compression is provided.
900 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
901 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
902 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
903 expected one (incorrect Adler-32 value). inflateSetDictionary does not
904 perform any decompression: this will be done by subsequent calls of
908 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
912 Returns the sliding dictionary being maintained by inflate. dictLength is
913 set to the number of bytes in the dictionary, and that many bytes are copied
914 to dictionary. dictionary must have enough space, where 32768 bytes is
915 always enough. If inflateGetDictionary() is called with dictionary equal to
916 Z_NULL, then only the dictionary length is returned, and nothing is copied.
917 Similary, if dictLength is Z_NULL, then it is not set.
919 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
920 stream state is inconsistent.
923 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
925 Skips invalid compressed data until a possible full flush point (see above
926 for the description of deflate with Z_FULL_FLUSH) can be found, or until all
927 available input is skipped. No output is provided.
929 inflateSync searches for a 00 00 FF FF pattern in the compressed data.
930 All full flush points have this pattern, but not all occurrences of this
931 pattern are full flush points.
933 inflateSync returns Z_OK if a possible full flush point has been found,
934 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
935 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
936 In the success case, the application may save the current current value of
937 total_in which indicates where valid compressed data was found. In the
938 error case, the application may repeatedly call inflateSync, providing more
939 input each time, until success or end of the input data.
942 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
945 Sets the destination stream as a complete copy of the source stream.
947 This function can be useful when randomly accessing a large stream. The
948 first pass through the stream can periodically record the inflate state,
949 allowing restarting inflate at those points when randomly accessing the
952 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
953 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
954 (such as zalloc being Z_NULL). msg is left unchanged in both source and
958 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
960 This function is equivalent to inflateEnd followed by inflateInit,
961 but does not free and reallocate the internal decompression state. The
962 stream will keep attributes that may have been set by inflateInit2.
964 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
965 stream state was inconsistent (such as zalloc or state being Z_NULL).
968 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
971 This function is the same as inflateReset, but it also permits changing
972 the wrap and window size requests. The windowBits parameter is interpreted
973 the same as it is for inflateInit2. If the window size is changed, then the
974 memory allocated for the window is freed, and the window will be reallocated
975 by inflate() if needed.
977 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
978 stream state was inconsistent (such as zalloc or state being Z_NULL), or if
979 the windowBits parameter is invalid.
982 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
986 This function inserts bits in the inflate input stream. The intent is
987 that this function is used to start inflating at a bit position in the
988 middle of a byte. The provided bits will be used before any bytes are used
989 from next_in. This function should only be used with raw inflate, and
990 should be used before the first inflate() call after inflateInit2() or
991 inflateReset(). bits must be less than or equal to 16, and that many of the
992 least significant bits of value will be inserted in the input.
994 If bits is negative, then the input stream bit buffer is emptied. Then
995 inflatePrime() can be called again to put bits in the buffer. This is used
996 to clear out bits leftover after feeding inflate a block description prior
997 to feeding inflate codes.
999 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1000 stream state was inconsistent.
1003 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
1005 This function returns two values, one in the lower 16 bits of the return
1006 value, and the other in the remaining upper bits, obtained by shifting the
1007 return value down 16 bits. If the upper value is -1 and the lower value is
1008 zero, then inflate() is currently decoding information outside of a block.
1009 If the upper value is -1 and the lower value is non-zero, then inflate is in
1010 the middle of a stored block, with the lower value equaling the number of
1011 bytes from the input remaining to copy. If the upper value is not -1, then
1012 it is the number of bits back from the current bit position in the input of
1013 the code (literal or length/distance pair) currently being processed. In
1014 that case the lower value is the number of bytes already emitted for that
1017 A code is being processed if inflate is waiting for more input to complete
1018 decoding of the code, or if it has completed decoding but is waiting for
1019 more output space to write the literal or match data.
1021 inflateMark() is used to mark locations in the input data for random
1022 access, which may be at bit positions, and to note those cases where the
1023 output of a code may span boundaries of random access blocks. The current
1024 location in the input stream can be determined from avail_in and data_type
1025 as noted in the description for the Z_BLOCK flush parameter for inflate.
1027 inflateMark returns the value noted above, or -65536 if the provided
1028 source stream state was inconsistent.
1031 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1034 inflateGetHeader() requests that gzip header information be stored in the
1035 provided gz_header structure. inflateGetHeader() may be called after
1036 inflateInit2() or inflateReset(), and before the first call of inflate().
1037 As inflate() processes the gzip stream, head->done is zero until the header
1038 is completed, at which time head->done is set to one. If a zlib stream is
1039 being decoded, then head->done is set to -1 to indicate that there will be
1040 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
1041 used to force inflate() to return immediately after header processing is
1042 complete and before any actual data is decompressed.
1044 The text, time, xflags, and os fields are filled in with the gzip header
1045 contents. hcrc is set to true if there is a header CRC. (The header CRC
1046 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1047 contains the maximum number of bytes to write to extra. Once done is true,
1048 extra_len contains the actual extra field length, and extra contains the
1049 extra field, or that field truncated if extra_max is less than extra_len.
1050 If name is not Z_NULL, then up to name_max characters are written there,
1051 terminated with a zero unless the length is greater than name_max. If
1052 comment is not Z_NULL, then up to comm_max characters are written there,
1053 terminated with a zero unless the length is greater than comm_max. When any
1054 of extra, name, or comment are not Z_NULL and the respective field is not
1055 present in the header, then that field is set to Z_NULL to signal its
1056 absence. This allows the use of deflateSetHeader() with the returned
1057 structure to duplicate the header. However if those fields are set to
1058 allocated memory, then the application will need to save those pointers
1059 elsewhere so that they can be eventually freed.
1061 If inflateGetHeader is not used, then the header information is simply
1062 discarded. The header is always checked for validity, including the header
1063 CRC if present. inflateReset() will reset the process to discard the header
1064 information. The application would need to call inflateGetHeader() again to
1065 retrieve the header from the next gzip stream.
1067 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1068 stream state was inconsistent.
1072 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1073 unsigned char FAR *window));
1075 Initialize the internal stream state for decompression using inflateBack()
1076 calls. The fields zalloc, zfree and opaque in strm must be initialized
1077 before the call. If zalloc and zfree are Z_NULL, then the default library-
1078 derived memory allocation routines are used. windowBits is the base two
1079 logarithm of the window size, in the range 8..15. window is a caller
1080 supplied buffer of that size. Except for special applications where it is
1081 assured that deflate was used with small window sizes, windowBits must be 15
1082 and a 32K byte window must be supplied to be able to decompress general
1085 See inflateBack() for the usage of these routines.
1087 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1088 the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1089 allocated, or Z_VERSION_ERROR if the version of the library does not match
1090 the version of the header file.
1093 typedef unsigned (*in_func) OF((void FAR *,
1094 z_const unsigned char FAR * FAR *));
1095 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1097 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1098 in_func in, void FAR *in_desc,
1099 out_func out, void FAR *out_desc));
1101 inflateBack() does a raw inflate with a single call using a call-back
1102 interface for input and output. This is potentially more efficient than
1103 inflate() for file i/o applications, in that it avoids copying between the
1104 output and the sliding window by simply making the window itself the output
1105 buffer. inflate() can be faster on modern CPUs when used with large
1106 buffers. inflateBack() trusts the application to not change the output
1107 buffer passed by the output function, at least until inflateBack() returns.
1109 inflateBackInit() must be called first to allocate the internal state
1110 and to initialize the state with the user-provided window buffer.
1111 inflateBack() may then be used multiple times to inflate a complete, raw
1112 deflate stream with each call. inflateBackEnd() is then called to free the
1115 A raw deflate stream is one with no zlib or gzip header or trailer.
1116 This routine would normally be used in a utility that reads zip or gzip
1117 files and writes out uncompressed files. The utility would decode the
1118 header and process the trailer on its own, hence this routine expects only
1119 the raw deflate stream to decompress. This is different from the default
1120 behavior of inflate(), which expects a zlib header and trailer around the
1123 inflateBack() uses two subroutines supplied by the caller that are then
1124 called by inflateBack() for input and output. inflateBack() calls those
1125 routines until it reads a complete deflate stream and writes out all of the
1126 uncompressed data, or until it encounters an error. The function's
1127 parameters and return types are defined above in the in_func and out_func
1128 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1129 number of bytes of provided input, and a pointer to that input in buf. If
1130 there is no input available, in() must return zero -- buf is ignored in that
1131 case -- and inflateBack() will return a buffer error. inflateBack() will
1132 call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1133 out() should return zero on success, or non-zero on failure. If out()
1134 returns non-zero, inflateBack() will return with an error. Neither in() nor
1135 out() are permitted to change the contents of the window provided to
1136 inflateBackInit(), which is also the buffer that out() uses to write from.
1137 The length written by out() will be at most the window size. Any non-zero
1138 amount of input may be provided by in().
1140 For convenience, inflateBack() can be provided input on the first call by
1141 setting strm->next_in and strm->avail_in. If that input is exhausted, then
1142 in() will be called. Therefore strm->next_in must be initialized before
1143 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1144 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1145 must also be initialized, and then if strm->avail_in is not zero, input will
1146 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1148 The in_desc and out_desc parameters of inflateBack() is passed as the
1149 first parameter of in() and out() respectively when they are called. These
1150 descriptors can be optionally used to pass any information that the caller-
1151 supplied in() and out() functions need to do their job.
1153 On return, inflateBack() will set strm->next_in and strm->avail_in to
1154 pass back any unused input that was provided by the last in() call. The
1155 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1156 if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1157 in the deflate stream (in which case strm->msg is set to indicate the nature
1158 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1159 In the case of Z_BUF_ERROR, an input or output error can be distinguished
1160 using strm->next_in which will be Z_NULL only if in() returned an error. If
1161 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1162 non-zero. (in() will always be called before out(), so strm->next_in is
1163 assured to be defined if out() returns non-zero.) Note that inflateBack()
1167 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1169 All memory allocated by inflateBackInit() is freed.
1171 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1172 state was inconsistent.
1175 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1176 /* Return flags indicating compile-time options.
1178 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1181 5.4: size of voidpf (pointer)
1182 7.6: size of z_off_t
1184 Compiler, assembler, and debug options:
1186 9: ASMV or ASMINF -- use ASM code
1187 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1190 One-time table building (smaller code, but not thread-safe if true):
1191 12: BUILDFIXED -- build static block decoding tables when needed
1192 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1195 Library content (indicates missing functionality):
1196 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1197 deflate code when not needed)
1198 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1199 and decode gzip streams (to avoid linking crc code)
1202 Operation variations (changes in library functionality):
1203 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1204 21: FASTEST -- deflate algorithm with only one, lowest compression level
1207 The sprintf variant used by gzprintf (zero is best):
1208 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1209 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1210 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1218 /* utility functions */
1221 The following utility functions are implemented on top of the basic
1222 stream-oriented functions. To simplify the interface, some default options
1223 are assumed (compression level and memory usage, standard memory allocation
1224 functions). The source code of these utility functions can be modified if
1225 you need special options.
1228 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1229 const Bytef *source, uLong sourceLen));
1231 Compresses the source buffer into the destination buffer. sourceLen is
1232 the byte length of the source buffer. Upon entry, destLen is the total size
1233 of the destination buffer, which must be at least the value returned by
1234 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1235 compressed data. compress() is equivalent to compress2() with a level
1236 parameter of Z_DEFAULT_COMPRESSION.
1238 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1239 enough memory, Z_BUF_ERROR if there was not enough room in the output
1243 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1244 const Bytef *source, uLong sourceLen,
1247 Compresses the source buffer into the destination buffer. The level
1248 parameter has the same meaning as in deflateInit. sourceLen is the byte
1249 length of the source buffer. Upon entry, destLen is the total size of the
1250 destination buffer, which must be at least the value returned by
1251 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1254 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1255 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1256 Z_STREAM_ERROR if the level parameter is invalid.
1259 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1261 compressBound() returns an upper bound on the compressed size after
1262 compress() or compress2() on sourceLen bytes. It would be used before a
1263 compress() or compress2() call to allocate the destination buffer.
1266 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1267 const Bytef *source, uLong sourceLen));
1269 Decompresses the source buffer into the destination buffer. sourceLen is
1270 the byte length of the source buffer. Upon entry, destLen is the total size
1271 of the destination buffer, which must be large enough to hold the entire
1272 uncompressed data. (The size of the uncompressed data must have been saved
1273 previously by the compressor and transmitted to the decompressor by some
1274 mechanism outside the scope of this compression library.) Upon exit, destLen
1275 is the actual size of the uncompressed data.
1277 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1278 enough memory, Z_BUF_ERROR if there was not enough room in the output
1279 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1280 the case where there is not enough room, uncompress() will fill the output
1281 buffer with the uncompressed data up to that point.
1284 ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest, uLongf *destLen,
1285 const Bytef *source, uLong *sourceLen));
1287 Same as uncompress, except that sourceLen is a pointer, where the
1288 length of the source is *sourceLen. On return, *sourceLen is the number of
1289 source bytes consumed.
1292 /* gzip file access functions */
1295 This library supports reading and writing files in gzip (.gz) format with
1296 an interface similar to that of stdio, using the functions that start with
1297 "gz". The gzip format is different from the zlib format. gzip is a gzip
1298 wrapper, documented in RFC 1952, wrapped around a deflate stream.
1301 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */
1304 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1306 Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1307 in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1308 a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1309 compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1310 for fixed code compression as in "wb9F". (See the description of
1311 deflateInit2 for more information about the strategy parameter.) 'T' will
1312 request transparent writing or appending with no compression and not using
1315 "a" can be used instead of "w" to request that the gzip stream that will
1316 be written be appended to the file. "+" will result in an error, since
1317 reading and writing to the same gzip file is not supported. The addition of
1318 "x" when writing will create the file exclusively, which fails if the file
1319 already exists. On systems that support it, the addition of "e" when
1320 reading or writing will set the flag to close the file on an execve() call.
1322 These functions, as well as gzip, will read and decode a sequence of gzip
1323 streams in a file. The append function of gzopen() can be used to create
1324 such a file. (Also see gzflush() for another way to do this.) When
1325 appending, gzopen does not test whether the file begins with a gzip stream,
1326 nor does it look for the end of the gzip streams to begin appending. gzopen
1327 will simply append a gzip stream to the existing file.
1329 gzopen can be used to read a file which is not in gzip format; in this
1330 case gzread will directly read from the file without decompression. When
1331 reading, this will be detected automatically by looking for the magic two-
1334 gzopen returns NULL if the file could not be opened, if there was
1335 insufficient memory to allocate the gzFile state, or if an invalid mode was
1336 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1337 errno can be checked to determine if the reason gzopen failed was that the
1338 file could not be opened.
1341 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1343 gzdopen associates a gzFile with the file descriptor fd. File descriptors
1344 are obtained from calls like open, dup, creat, pipe or fileno (if the file
1345 has been previously opened with fopen). The mode parameter is as in gzopen.
1347 The next call of gzclose on the returned gzFile will also close the file
1348 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1349 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1350 mode);. The duplicated descriptor should be saved to avoid a leak, since
1351 gzdopen does not close fd if it fails. If you are using fileno() to get the
1352 file descriptor from a FILE *, then you will have to use dup() to avoid
1353 double-close()ing the file descriptor. Both gzclose() and fclose() will
1354 close the associated file descriptor, so they need to have different file
1357 gzdopen returns NULL if there was insufficient memory to allocate the
1358 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1359 provided, or '+' was provided), or if fd is -1. The file descriptor is not
1360 used until the next gz* read, write, seek, or close operation, so gzdopen
1361 will not detect if fd is invalid (unless fd is -1).
1364 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1366 Set the internal buffer size used by this library's functions. The
1367 default buffer size is 8192 bytes. This function must be called after
1368 gzopen() or gzdopen(), and before any other calls that read or write the
1369 file. The buffer memory allocation is always deferred to the first read or
1370 write. Three times that size in buffer space is allocated. A larger buffer
1371 size of, for example, 64K or 128K bytes will noticeably increase the speed
1372 of decompression (reading).
1374 The new buffer size also affects the maximum length for gzprintf().
1376 gzbuffer() returns 0 on success, or -1 on failure, such as being called
1380 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1382 Dynamically update the compression level or strategy. See the description
1383 of deflateInit2 for the meaning of these parameters. Previously provided
1384 data is flushed before the parameter change.
1386 gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1387 opened for writing, Z_ERRNO if there is an error writing the flushed data,
1388 or Z_MEM_ERROR if there is a memory allocation error.
1391 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1393 Reads the given number of uncompressed bytes from the compressed file. If
1394 the input file is not in gzip format, gzread copies the given number of
1395 bytes into the buffer directly from the file.
1397 After reaching the end of a gzip stream in the input, gzread will continue
1398 to read, looking for another gzip stream. Any number of gzip streams may be
1399 concatenated in the input file, and will all be decompressed by gzread().
1400 If something other than a gzip stream is encountered after a gzip stream,
1401 that remaining trailing garbage is ignored (and no error is returned).
1403 gzread can be used to read a gzip file that is being concurrently written.
1404 Upon reaching the end of the input, gzread will return with the available
1405 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1406 gzclearerr can be used to clear the end of file indicator in order to permit
1407 gzread to be tried again. Z_OK indicates that a gzip stream was completed
1408 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1409 middle of a gzip stream. Note that gzread does not return -1 in the event
1410 of an incomplete gzip stream. This error is deferred until gzclose(), which
1411 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1412 stream. Alternatively, gzerror can be used before gzclose to detect this
1415 gzread returns the number of uncompressed bytes actually read, less than
1416 len for end of file, or -1 for error. If len is too large to fit in an int,
1417 then nothing is read, -1 is returned, and the error state is set to
1421 ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
1424 Read up to nitems items of size size from file to buf, otherwise operating
1425 as gzread() does. This duplicates the interface of stdio's fread(), with
1426 size_t request and return types. If the library defines size_t, then
1427 z_size_t is identical to size_t. If not, then z_size_t is an unsigned
1428 integer type that can contain a pointer.
1430 gzfread() returns the number of full items read of size size, or zero if
1431 the end of the file was reached and a full item could not be read, or if
1432 there was an error. gzerror() must be consulted if zero is returned in
1433 order to determine if there was an error. If the multiplication of size and
1434 nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1435 is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1437 In the event that the end of file is reached and only a partial item is
1438 available at the end, i.e. the remaining uncompressed data length is not a
1439 multiple of size, then the final partial item is nevetheless read into buf
1440 and the end-of-file flag is set. The length of the partial item read is not
1441 provided, but could be inferred from the result of gztell(). This behavior
1442 is the same as the behavior of fread() implementations in common libraries,
1443 but it prevents the direct use of gzfread() to read a concurrently written
1444 file, reseting and retrying on end-of-file, when size is not 1.
1447 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1448 voidpc buf, unsigned len));
1450 Writes the given number of uncompressed bytes into the compressed file.
1451 gzwrite returns the number of uncompressed bytes written or 0 in case of
1455 ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
1456 z_size_t nitems, gzFile file));
1458 gzfwrite() writes nitems items of size size from buf to file, duplicating
1459 the interface of stdio's fwrite(), with size_t request and return types. If
1460 the library defines size_t, then z_size_t is identical to size_t. If not,
1461 then z_size_t is an unsigned integer type that can contain a pointer.
1463 gzfwrite() returns the number of full items written of size size, or zero
1464 if there was an error. If the multiplication of size and nitems overflows,
1465 i.e. the product does not fit in a z_size_t, then nothing is written, zero
1466 is returned, and the error state is set to Z_STREAM_ERROR.
1469 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1471 Converts, formats, and writes the arguments to the compressed file under
1472 control of the format string, as in fprintf. gzprintf returns the number of
1473 uncompressed bytes actually written, or a negative zlib error code in case
1474 of error. The number of uncompressed bytes written is limited to 8191, or
1475 one less than the buffer size given to gzbuffer(). The caller should assure
1476 that this limit is not exceeded. If it is exceeded, then gzprintf() will
1477 return an error (0) with nothing written. In this case, there may also be a
1478 buffer overflow with unpredictable consequences, which is possible only if
1479 zlib was compiled with the insecure functions sprintf() or vsprintf()
1480 because the secure snprintf() or vsnprintf() functions were not available.
1481 This can be determined using zlibCompileFlags().
1484 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1486 Writes the given null-terminated string to the compressed file, excluding
1487 the terminating null character.
1489 gzputs returns the number of characters written, or -1 in case of error.
1492 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1494 Reads bytes from the compressed file until len-1 characters are read, or a
1495 newline character is read and transferred to buf, or an end-of-file
1496 condition is encountered. If any characters are read or if len == 1, the
1497 string is terminated with a null character. If no characters are read due
1498 to an end-of-file or len < 1, then the buffer is left untouched.
1500 gzgets returns buf which is a null-terminated string, or it returns NULL
1501 for end-of-file or in case of error. If there was an error, the contents at
1502 buf are indeterminate.
1505 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1507 Writes c, converted to an unsigned char, into the compressed file. gzputc
1508 returns the value that was written, or -1 in case of error.
1511 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1513 Reads one byte from the compressed file. gzgetc returns this byte or -1
1514 in case of end of file or error. This is implemented as a macro for speed.
1515 As such, it does not do all of the checking the other functions do. I.e.
1516 it does not check to see if file is NULL, nor whether the structure file
1517 points to has been clobbered or not.
1520 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1522 Push one character back onto the stream to be read as the first character
1523 on the next read. At least one character of push-back is allowed.
1524 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1525 fail if c is -1, and may fail if a character has been pushed but not read
1526 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1527 output buffer size of pushed characters is allowed. (See gzbuffer above.)
1528 The pushed character will be discarded if the stream is repositioned with
1529 gzseek() or gzrewind().
1532 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1534 Flushes all pending output into the compressed file. The parameter flush
1535 is as in the deflate() function. The return value is the zlib error number
1536 (see function gzerror below). gzflush is only permitted when writing.
1538 If the flush parameter is Z_FINISH, the remaining data is written and the
1539 gzip stream is completed in the output. If gzwrite() is called again, a new
1540 gzip stream will be started in the output. gzread() is able to read such
1541 concatenated gzip streams.
1543 gzflush should be called only when strictly necessary because it will
1544 degrade compression if called too often.
1548 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1549 z_off_t offset, int whence));
1551 Sets the starting position for the next gzread or gzwrite on the given
1552 compressed file. The offset represents a number of bytes in the
1553 uncompressed data stream. The whence parameter is defined as in lseek(2);
1554 the value SEEK_END is not supported.
1556 If the file is opened for reading, this function is emulated but can be
1557 extremely slow. If the file is opened for writing, only forward seeks are
1558 supported; gzseek then compresses a sequence of zeroes up to the new
1561 gzseek returns the resulting offset location as measured in bytes from
1562 the beginning of the uncompressed stream, or -1 in case of error, in
1563 particular if the file is opened for writing and the new starting position
1564 would be before the current position.
1567 ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1569 Rewinds the given file. This function is supported only for reading.
1571 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1575 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1577 Returns the starting position for the next gzread or gzwrite on the given
1578 compressed file. This position represents a number of bytes in the
1579 uncompressed data stream, and is zero when starting, even if appending or
1580 reading a gzip stream from the middle of a file using gzdopen().
1582 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1586 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1588 Returns the current offset in the file being read or written. This offset
1589 includes the count of bytes that precede the gzip stream, for example when
1590 appending or when using gzdopen() for reading. When reading, the offset
1591 does not include as yet unused buffered input. This information can be used
1592 for a progress indicator. On error, gzoffset() returns -1.
1595 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1597 Returns true (1) if the end-of-file indicator has been set while reading,
1598 false (0) otherwise. Note that the end-of-file indicator is set only if the
1599 read tried to go past the end of the input, but came up short. Therefore,
1600 just like feof(), gzeof() may return false even if there is no more data to
1601 read, in the event that the last read request was for the exact number of
1602 bytes remaining in the input file. This will happen if the input file size
1603 is an exact multiple of the buffer size.
1605 If gzeof() returns true, then the read functions will return no more data,
1606 unless the end-of-file indicator is reset by gzclearerr() and the input file
1607 has grown since the previous end of file was detected.
1610 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1612 Returns true (1) if file is being copied directly while reading, or false
1613 (0) if file is a gzip stream being decompressed.
1615 If the input file is empty, gzdirect() will return true, since the input
1616 does not contain a gzip stream.
1618 If gzdirect() is used immediately after gzopen() or gzdopen() it will
1619 cause buffers to be allocated to allow reading the file to determine if it
1620 is a gzip file. Therefore if gzbuffer() is used, it should be called before
1623 When writing, gzdirect() returns true (1) if transparent writing was
1624 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1625 gzdirect() is not needed when writing. Transparent writing must be
1626 explicitly requested, so the application already knows the answer. When
1627 linking statically, using gzdirect() will include all of the zlib code for
1628 gzip file reading and decompression, which may not be desired.)
1631 ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1633 Flushes all pending output if necessary, closes the compressed file and
1634 deallocates the (de)compression state. Note that once file is closed, you
1635 cannot call gzerror with file, since its structures have been deallocated.
1636 gzclose must not be called more than once on the same file, just as free
1637 must not be called more than once on the same allocation.
1639 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1640 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1641 last read ended in the middle of a gzip stream, or Z_OK on success.
1644 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1645 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1647 Same as gzclose(), but gzclose_r() is only for use when reading, and
1648 gzclose_w() is only for use when writing or appending. The advantage to
1649 using these instead of gzclose() is that they avoid linking in zlib
1650 compression or decompression code that is not used when only reading or only
1651 writing respectively. If gzclose() is used, then both compression and
1652 decompression code will be included the application when linking to a static
1656 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1658 Returns the error message for the last error which occurred on the given
1659 compressed file. errnum is set to zlib error number. If an error occurred
1660 in the file system and not in the compression library, errnum is set to
1661 Z_ERRNO and the application may consult errno to get the exact error code.
1663 The application must not modify the returned string. Future calls to
1664 this function may invalidate the previously returned string. If file is
1665 closed, then the string previously returned by gzerror will no longer be
1668 gzerror() should be used to distinguish errors from end-of-file for those
1669 functions above that do not distinguish those cases in their return values.
1672 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1674 Clears the error and end-of-file flags for file. This is analogous to the
1675 clearerr() function in stdio. This is useful for continuing to read a gzip
1676 file that is being written concurrently.
1679 #endif /* !Z_SOLO */
1681 /* checksum functions */
1684 These functions are not related to compression but are exported
1685 anyway because they might be useful in applications using the compression
1689 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1691 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1692 return the updated checksum. If buf is Z_NULL, this function returns the
1693 required initial value for the checksum.
1695 An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1700 uLong adler = adler32(0L, Z_NULL, 0);
1702 while (read_buffer(buffer, length) != EOF) {
1703 adler = adler32(adler, buffer, length);
1705 if (adler != original_adler) error();
1708 ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
1711 Same as adler32(), but with a size_t length.
1715 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1718 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1719 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1720 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1721 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1722 that the z_off_t type (like off_t) is a signed integer. If len2 is
1723 negative, the result has no meaning or utility.
1726 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1728 Update a running CRC-32 with the bytes buf[0..len-1] and return the
1729 updated CRC-32. If buf is Z_NULL, this function returns the required
1730 initial value for the crc. Pre- and post-conditioning (one's complement) is
1731 performed within this function so it shouldn't be done by the application.
1735 uLong crc = crc32(0L, Z_NULL, 0);
1737 while (read_buffer(buffer, length) != EOF) {
1738 crc = crc32(crc, buffer, length);
1740 if (crc != original_crc) error();
1743 ZEXTERN uLong ZEXPORT crc32_z OF((uLong adler, const Bytef *buf,
1746 Same as crc32(), but with a size_t length.
1750 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1752 Combine two CRC-32 check values into one. For two sequences of bytes,
1753 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1754 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1755 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1760 /* various hacks, don't look :) */
1762 /* deflateInit and inflateInit are macros to allow checking the zlib version
1763 * and the compiler's view of z_stream:
1765 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1766 const char *version, int stream_size));
1767 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1768 const char *version, int stream_size));
1769 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1770 int windowBits, int memLevel,
1771 int strategy, const char *version,
1773 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1774 const char *version, int stream_size));
1775 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1776 unsigned char FAR *window,
1777 const char *version,
1780 # define z_deflateInit(strm, level) \
1781 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1782 # define z_inflateInit(strm) \
1783 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1784 # define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1785 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1786 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1787 # define z_inflateInit2(strm, windowBits) \
1788 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1789 (int)sizeof(z_stream))
1790 # define z_inflateBackInit(strm, windowBits, window) \
1791 inflateBackInit_((strm), (windowBits), (window), \
1792 ZLIB_VERSION, (int)sizeof(z_stream))
1794 # define deflateInit(strm, level) \
1795 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1796 # define inflateInit(strm) \
1797 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1798 # define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1799 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1800 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1801 # define inflateInit2(strm, windowBits) \
1802 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1803 (int)sizeof(z_stream))
1804 # define inflateBackInit(strm, windowBits, window) \
1805 inflateBackInit_((strm), (windowBits), (window), \
1806 ZLIB_VERSION, (int)sizeof(z_stream))
1811 /* gzgetc() macro and its supporting function and exposed data structure. Note
1812 * that the real internal state is much larger than the exposed structure.
1813 * This abbreviated structure exposes just enough for the gzgetc() macro. The
1814 * user should not mess with these exposed elements, since their names or
1815 * behavior could change in the future, perhaps even capriciously. They can
1816 * only be used by the gzgetc() macro. You have been warned.
1820 unsigned char *next;
1823 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */
1826 # define z_gzgetc(g) \
1827 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1829 # define gzgetc(g) \
1830 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1833 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1834 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1835 * both are true, the application gets the *64 functions, and the regular
1836 * functions are changed to 64 bits) -- in case these are set on systems
1837 * without large file support, _LFS64_LARGEFILE must also be true
1840 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1841 ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1842 ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1843 ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1844 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1845 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1848 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1849 # ifdef Z_PREFIX_SET
1850 # define z_gzopen z_gzopen64
1851 # define z_gzseek z_gzseek64
1852 # define z_gztell z_gztell64
1853 # define z_gzoffset z_gzoffset64
1854 # define z_adler32_combine z_adler32_combine64
1855 # define z_crc32_combine z_crc32_combine64
1857 # define gzopen gzopen64
1858 # define gzseek gzseek64
1859 # define gztell gztell64
1860 # define gzoffset gzoffset64
1861 # define adler32_combine adler32_combine64
1862 # define crc32_combine crc32_combine64
1865 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1866 ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1867 ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1868 ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1869 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1870 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1873 ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1874 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1875 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1876 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1877 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1878 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1883 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1884 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1886 #endif /* !Z_SOLO */
1888 /* undocumented functions */
1889 ZEXTERN const char * ZEXPORT zError OF((int));
1890 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1891 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void));
1892 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
1893 ZEXTERN int ZEXPORT inflateValidate OF((z_streamp, int));
1894 ZEXTERN unsigned long ZEXPORT inflateCodesUsed OF ((z_streamp));
1895 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp));
1896 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp));
1897 #if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(Z_SOLO)
1898 ZEXTERN gzFile ZEXPORT gzopen_w OF((const wchar_t *path,
1901 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1903 ZEXTERN int ZEXPORTVA gzvprintf Z_ARG((gzFile file,
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