1 /* zlib.h -- interface of the 'zlib' general purpose compression library
3 Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
5 This software is provided 'as-is', without any express or implied
6 warranty. In no event will the authors be held liable for any damages
7 arising from the use of this software.
9 Permission is granted to anyone to use this software for any purpose,
10 including commercial applications, and to alter it and redistribute it
11 freely, subject to the following restrictions:
13 1. The origin of this software must not be misrepresented; you must not
14 claim that you wrote the original software. If you use this software
15 in a product, an acknowledgment in the product documentation would be
16 appreciated but is not required.
17 2. Altered source versions must be plainly marked as such, and must not be
18 misrepresented as being the original software.
19 3. This notice may not be removed or altered from any source distribution.
21 Jean-loup Gailly Mark Adler
22 jloup@gzip.org madler@alumni.caltech.edu
25 The data format used by the zlib library is described by RFCs (Request for
26 Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
27 (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
33 #include <linux/zconf.h>
35 /* zlib deflate based on ZLIB_VERSION "1.1.3" */
36 /* zlib inflate based on ZLIB_VERSION "1.2.3" */
39 This is a modified version of zlib for use inside the Linux kernel.
40 The main changes are to perform all memory allocation in advance.
43 * Z_PACKET_FLUSH is added and used by ppp_deflate. Before returning
44 this checks there is no more input data available and the next data
45 is a STORED block. It also resets the mode to be read for the next
46 data, all as per PPP requirements.
47 * Addition of zlib_inflateIncomp which copies incompressible data into
48 the history window and adjusts the accoutning without calling
49 zlib_inflate itself to inflate the data.
53 The 'zlib' compression library provides in-memory compression and
54 decompression functions, including integrity checks of the uncompressed
55 data. This version of the library supports only one compression method
56 (deflation) but other algorithms will be added later and will have the same
59 Compression can be done in a single step if the buffers are large
60 enough (for example if an input file is mmap'ed), or can be done by
61 repeated calls of the compression function. In the latter case, the
62 application must provide more input and/or consume the output
63 (providing more output space) before each call.
65 The compressed data format used by default by the in-memory functions is
66 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
67 around a deflate stream, which is itself documented in RFC 1951.
69 The library also supports reading and writing files in gzip (.gz) format
70 with an interface similar to that of stdio.
72 The zlib format was designed to be compact and fast for use in memory
73 and on communications channels. The gzip format was designed for single-
74 file compression on file systems, has a larger header than zlib to maintain
75 directory information, and uses a different, slower check method than zlib.
77 The library does not install any signal handler. The decoder checks
78 the consistency of the compressed data, so the library should never
79 crash even in case of corrupted input.
82 struct internal_state;
84 typedef struct z_stream_s {
85 const Byte *next_in; /* next input byte */
86 uInt avail_in; /* number of bytes available at next_in */
87 uLong total_in; /* total nb of input bytes read so far */
89 Byte *next_out; /* next output byte should be put there */
90 uInt avail_out; /* remaining free space at next_out */
91 uLong total_out; /* total nb of bytes output so far */
93 char *msg; /* last error message, NULL if no error */
94 struct internal_state *state; /* not visible by applications */
96 void *workspace; /* memory allocated for this stream */
98 int data_type; /* best guess about the data type: ascii or binary */
99 uLong adler; /* adler32 value of the uncompressed data */
100 uLong reserved; /* reserved for future use */
103 typedef z_stream *z_streamp;
106 The application must update next_in and avail_in when avail_in has
107 dropped to zero. It must update next_out and avail_out when avail_out
108 has dropped to zero. The application must initialize zalloc, zfree and
109 opaque before calling the init function. All other fields are set by the
110 compression library and must not be updated by the application.
112 The opaque value provided by the application will be passed as the first
113 parameter for calls of zalloc and zfree. This can be useful for custom
114 memory management. The compression library attaches no meaning to the
117 zalloc must return NULL if there is not enough memory for the object.
118 If zlib is used in a multi-threaded application, zalloc and zfree must be
121 On 16-bit systems, the functions zalloc and zfree must be able to allocate
122 exactly 65536 bytes, but will not be required to allocate more than this
123 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
124 pointers returned by zalloc for objects of exactly 65536 bytes *must*
125 have their offset normalized to zero. The default allocation function
126 provided by this library ensures this (see zutil.c). To reduce memory
127 requirements and avoid any allocation of 64K objects, at the expense of
128 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
130 The fields total_in and total_out can be used for statistics or
131 progress reports. After compression, total_in holds the total size of
132 the uncompressed data and may be saved for use in the decompressor
133 (particularly if the decompressor wants to decompress everything in
140 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
141 #define Z_PACKET_FLUSH 2
142 #define Z_SYNC_FLUSH 3
143 #define Z_FULL_FLUSH 4
145 #define Z_BLOCK 6 /* Only for inflate at present */
146 /* Allowed flush values; see deflate() and inflate() below for details */
149 #define Z_STREAM_END 1
150 #define Z_NEED_DICT 2
152 #define Z_STREAM_ERROR (-2)
153 #define Z_DATA_ERROR (-3)
154 #define Z_MEM_ERROR (-4)
155 #define Z_BUF_ERROR (-5)
156 #define Z_VERSION_ERROR (-6)
157 /* Return codes for the compression/decompression functions. Negative
158 * values are errors, positive values are used for special but normal events.
161 #define Z_NO_COMPRESSION 0
162 #define Z_BEST_SPEED 1
163 #define Z_BEST_COMPRESSION 9
164 #define Z_DEFAULT_COMPRESSION (-1)
165 /* compression levels */
168 #define Z_HUFFMAN_ONLY 2
169 #define Z_DEFAULT_STRATEGY 0
170 /* compression strategy; see deflateInit2() below for details */
175 /* Possible values of the data_type field */
178 /* The deflate compression method (the only one supported in this version) */
180 /* basic functions */
182 extern int zlib_deflate_workspacesize (void);
184 Returns the number of bytes that needs to be allocated for a per-
185 stream workspace. A pointer to this number of bytes should be
186 returned in stream->workspace before calling zlib_deflateInit().
190 extern int deflateInit (z_streamp strm, int level);
192 Initializes the internal stream state for compression. The fields
193 zalloc, zfree and opaque must be initialized before by the caller.
194 If zalloc and zfree are set to NULL, deflateInit updates them to
195 use default allocation functions.
197 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
198 1 gives best speed, 9 gives best compression, 0 gives no compression at
199 all (the input data is simply copied a block at a time).
200 Z_DEFAULT_COMPRESSION requests a default compromise between speed and
201 compression (currently equivalent to level 6).
203 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
204 enough memory, Z_STREAM_ERROR if level is not a valid compression level,
205 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
206 with the version assumed by the caller (ZLIB_VERSION).
207 msg is set to null if there is no error message. deflateInit does not
208 perform any compression: this will be done by deflate().
212 extern int zlib_deflate (z_streamp strm, int flush);
214 deflate compresses as much data as possible, and stops when the input
215 buffer becomes empty or the output buffer becomes full. It may introduce some
216 output latency (reading input without producing any output) except when
219 The detailed semantics are as follows. deflate performs one or both of the
222 - Compress more input starting at next_in and update next_in and avail_in
223 accordingly. If not all input can be processed (because there is not
224 enough room in the output buffer), next_in and avail_in are updated and
225 processing will resume at this point for the next call of deflate().
227 - Provide more output starting at next_out and update next_out and avail_out
228 accordingly. This action is forced if the parameter flush is non zero.
229 Forcing flush frequently degrades the compression ratio, so this parameter
230 should be set only when necessary (in interactive applications).
231 Some output may be provided even if flush is not set.
233 Before the call of deflate(), the application should ensure that at least
234 one of the actions is possible, by providing more input and/or consuming
235 more output, and updating avail_in or avail_out accordingly; avail_out
236 should never be zero before the call. The application can consume the
237 compressed output when it wants, for example when the output buffer is full
238 (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
239 and with zero avail_out, it must be called again after making room in the
240 output buffer because there might be more output pending.
242 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
243 flushed to the output buffer and the output is aligned on a byte boundary, so
244 that the decompressor can get all input data available so far. (In particular
245 avail_in is zero after the call if enough output space has been provided
246 before the call.) Flushing may degrade compression for some compression
247 algorithms and so it should be used only when necessary.
249 If flush is set to Z_FULL_FLUSH, all output is flushed as with
250 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
251 restart from this point if previous compressed data has been damaged or if
252 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
255 If deflate returns with avail_out == 0, this function must be called again
256 with the same value of the flush parameter and more output space (updated
257 avail_out), until the flush is complete (deflate returns with non-zero
260 If the parameter flush is set to Z_FINISH, pending input is processed,
261 pending output is flushed and deflate returns with Z_STREAM_END if there
262 was enough output space; if deflate returns with Z_OK, this function must be
263 called again with Z_FINISH and more output space (updated avail_out) but no
264 more input data, until it returns with Z_STREAM_END or an error. After
265 deflate has returned Z_STREAM_END, the only possible operations on the
266 stream are deflateReset or deflateEnd.
268 Z_FINISH can be used immediately after deflateInit if all the compression
269 is to be done in a single step. In this case, avail_out must be at least
270 0.1% larger than avail_in plus 12 bytes. If deflate does not return
271 Z_STREAM_END, then it must be called again as described above.
273 deflate() sets strm->adler to the adler32 checksum of all input read
274 so far (that is, total_in bytes).
276 deflate() may update data_type if it can make a good guess about
277 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
278 binary. This field is only for information purposes and does not affect
279 the compression algorithm in any manner.
281 deflate() returns Z_OK if some progress has been made (more input
282 processed or more output produced), Z_STREAM_END if all input has been
283 consumed and all output has been produced (only when flush is set to
284 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
285 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
286 (for example avail_in or avail_out was zero).
290 extern int zlib_deflateEnd (z_streamp strm);
292 All dynamically allocated data structures for this stream are freed.
293 This function discards any unprocessed input and does not flush any
296 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
297 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
298 prematurely (some input or output was discarded). In the error case,
299 msg may be set but then points to a static string (which must not be
304 extern int zlib_inflate_workspacesize (void);
306 Returns the number of bytes that needs to be allocated for a per-
307 stream workspace. A pointer to this number of bytes should be
308 returned in stream->workspace before calling zlib_inflateInit().
312 extern int zlib_inflateInit (z_streamp strm);
314 Initializes the internal stream state for decompression. The fields
315 next_in, avail_in, and workspace must be initialized before by
316 the caller. If next_in is not NULL and avail_in is large enough (the exact
317 value depends on the compression method), inflateInit determines the
318 compression method from the zlib header and allocates all data structures
319 accordingly; otherwise the allocation will be deferred to the first call of
320 inflate. If zalloc and zfree are set to NULL, inflateInit updates them to
321 use default allocation functions.
323 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
324 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
325 version assumed by the caller. msg is set to null if there is no error
326 message. inflateInit does not perform any decompression apart from reading
327 the zlib header if present: this will be done by inflate(). (So next_in and
328 avail_in may be modified, but next_out and avail_out are unchanged.)
332 extern int zlib_inflate (z_streamp strm, int flush);
334 inflate decompresses as much data as possible, and stops when the input
335 buffer becomes empty or the output buffer becomes full. It may introduce
336 some output latency (reading input without producing any output) except when
339 The detailed semantics are as follows. inflate performs one or both of the
342 - Decompress more input starting at next_in and update next_in and avail_in
343 accordingly. If not all input can be processed (because there is not
344 enough room in the output buffer), next_in is updated and processing
345 will resume at this point for the next call of inflate().
347 - Provide more output starting at next_out and update next_out and avail_out
348 accordingly. inflate() provides as much output as possible, until there
349 is no more input data or no more space in the output buffer (see below
350 about the flush parameter).
352 Before the call of inflate(), the application should ensure that at least
353 one of the actions is possible, by providing more input and/or consuming
354 more output, and updating the next_* and avail_* values accordingly.
355 The application can consume the uncompressed output when it wants, for
356 example when the output buffer is full (avail_out == 0), or after each
357 call of inflate(). If inflate returns Z_OK and with zero avail_out, it
358 must be called again after making room in the output buffer because there
359 might be more output pending.
361 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
362 Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
363 output as possible to the output buffer. Z_BLOCK requests that inflate() stop
364 if and when it gets to the next deflate block boundary. When decoding the
365 zlib or gzip format, this will cause inflate() to return immediately after
366 the header and before the first block. When doing a raw inflate, inflate()
367 will go ahead and process the first block, and will return when it gets to
368 the end of that block, or when it runs out of data.
370 The Z_BLOCK option assists in appending to or combining deflate streams.
371 Also to assist in this, on return inflate() will set strm->data_type to the
372 number of unused bits in the last byte taken from strm->next_in, plus 64
373 if inflate() is currently decoding the last block in the deflate stream,
374 plus 128 if inflate() returned immediately after decoding an end-of-block
375 code or decoding the complete header up to just before the first byte of the
376 deflate stream. The end-of-block will not be indicated until all of the
377 uncompressed data from that block has been written to strm->next_out. The
378 number of unused bits may in general be greater than seven, except when
379 bit 7 of data_type is set, in which case the number of unused bits will be
382 inflate() should normally be called until it returns Z_STREAM_END or an
383 error. However if all decompression is to be performed in a single step
384 (a single call of inflate), the parameter flush should be set to
385 Z_FINISH. In this case all pending input is processed and all pending
386 output is flushed; avail_out must be large enough to hold all the
387 uncompressed data. (The size of the uncompressed data may have been saved
388 by the compressor for this purpose.) The next operation on this stream must
389 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
390 is never required, but can be used to inform inflate that a faster approach
391 may be used for the single inflate() call.
393 In this implementation, inflate() always flushes as much output as
394 possible to the output buffer, and always uses the faster approach on the
395 first call. So the only effect of the flush parameter in this implementation
396 is on the return value of inflate(), as noted below, or when it returns early
397 because Z_BLOCK is used.
399 If a preset dictionary is needed after this call (see inflateSetDictionary
400 below), inflate sets strm->adler to the adler32 checksum of the dictionary
401 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
402 strm->adler to the adler32 checksum of all output produced so far (that is,
403 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
404 below. At the end of the stream, inflate() checks that its computed adler32
405 checksum is equal to that saved by the compressor and returns Z_STREAM_END
406 only if the checksum is correct.
408 inflate() will decompress and check either zlib-wrapped or gzip-wrapped
409 deflate data. The header type is detected automatically. Any information
410 contained in the gzip header is not retained, so applications that need that
411 information should instead use raw inflate, see inflateInit2() below, or
412 inflateBack() and perform their own processing of the gzip header and
415 inflate() returns Z_OK if some progress has been made (more input processed
416 or more output produced), Z_STREAM_END if the end of the compressed data has
417 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
418 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
419 corrupted (input stream not conforming to the zlib format or incorrect check
420 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
421 if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
422 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
423 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
424 inflate() can be called again with more input and more output space to
425 continue decompressing. If Z_DATA_ERROR is returned, the application may then
426 call inflateSync() to look for a good compression block if a partial recovery
427 of the data is desired.
431 extern int zlib_inflateEnd (z_streamp strm);
433 All dynamically allocated data structures for this stream are freed.
434 This function discards any unprocessed input and does not flush any
437 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
438 was inconsistent. In the error case, msg may be set but then points to a
439 static string (which must not be deallocated).
442 /* Advanced functions */
445 The following functions are needed only in some special applications.
449 extern int deflateInit2 (z_streamp strm,
456 This is another version of deflateInit with more compression options. The
457 fields next_in, zalloc, zfree and opaque must be initialized before by
460 The method parameter is the compression method. It must be Z_DEFLATED in
461 this version of the library.
463 The windowBits parameter is the base two logarithm of the window size
464 (the size of the history buffer). It should be in the range 8..15 for this
465 version of the library. Larger values of this parameter result in better
466 compression at the expense of memory usage. The default value is 15 if
467 deflateInit is used instead.
469 The memLevel parameter specifies how much memory should be allocated
470 for the internal compression state. memLevel=1 uses minimum memory but
471 is slow and reduces compression ratio; memLevel=9 uses maximum memory
472 for optimal speed. The default value is 8. See zconf.h for total memory
473 usage as a function of windowBits and memLevel.
475 The strategy parameter is used to tune the compression algorithm. Use the
476 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
477 filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
478 string match). Filtered data consists mostly of small values with a
479 somewhat random distribution. In this case, the compression algorithm is
480 tuned to compress them better. The effect of Z_FILTERED is to force more
481 Huffman coding and less string matching; it is somewhat intermediate
482 between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
483 the compression ratio but not the correctness of the compressed output even
484 if it is not set appropriately.
486 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
487 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
488 method). msg is set to null if there is no error message. deflateInit2 does
489 not perform any compression: this will be done by deflate().
493 extern int zlib_deflateSetDictionary (z_streamp strm,
494 const Byte *dictionary,
498 Initializes the compression dictionary from the given byte sequence
499 without producing any compressed output. This function must be called
500 immediately after deflateInit, deflateInit2 or deflateReset, before any
501 call of deflate. The compressor and decompressor must use exactly the same
502 dictionary (see inflateSetDictionary).
504 The dictionary should consist of strings (byte sequences) that are likely
505 to be encountered later in the data to be compressed, with the most commonly
506 used strings preferably put towards the end of the dictionary. Using a
507 dictionary is most useful when the data to be compressed is short and can be
508 predicted with good accuracy; the data can then be compressed better than
509 with the default empty dictionary.
511 Depending on the size of the compression data structures selected by
512 deflateInit or deflateInit2, a part of the dictionary may in effect be
513 discarded, for example if the dictionary is larger than the window size in
514 deflate or deflate2. Thus the strings most likely to be useful should be
515 put at the end of the dictionary, not at the front.
517 Upon return of this function, strm->adler is set to the Adler32 value
518 of the dictionary; the decompressor may later use this value to determine
519 which dictionary has been used by the compressor. (The Adler32 value
520 applies to the whole dictionary even if only a subset of the dictionary is
521 actually used by the compressor.)
523 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
524 parameter is invalid (such as NULL dictionary) or the stream state is
525 inconsistent (for example if deflate has already been called for this stream
526 or if the compression method is bsort). deflateSetDictionary does not
527 perform any compression: this will be done by deflate().
531 extern int zlib_deflateCopy (z_streamp dest, z_streamp source);
535 Sets the destination stream as a complete copy of the source stream.
537 This function can be useful when several compression strategies will be
538 tried, for example when there are several ways of pre-processing the input
539 data with a filter. The streams that will be discarded should then be freed
540 by calling deflateEnd. Note that deflateCopy duplicates the internal
541 compression state which can be quite large, so this strategy is slow and
542 can consume lots of memory.
544 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
545 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
546 (such as zalloc being NULL). msg is left unchanged in both source and
550 extern int zlib_deflateReset (z_streamp strm);
552 This function is equivalent to deflateEnd followed by deflateInit,
553 but does not free and reallocate all the internal compression state.
554 The stream will keep the same compression level and any other attributes
555 that may have been set by deflateInit2.
557 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
558 stream state was inconsistent (such as zalloc or state being NULL).
561 static inline unsigned long deflateBound(unsigned long s)
563 return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11;
567 extern int zlib_deflateParams (z_streamp strm, int level, int strategy);
570 Dynamically update the compression level and compression strategy. The
571 interpretation of level and strategy is as in deflateInit2. This can be
572 used to switch between compression and straight copy of the input data, or
573 to switch to a different kind of input data requiring a different
574 strategy. If the compression level is changed, the input available so far
575 is compressed with the old level (and may be flushed); the new level will
576 take effect only at the next call of deflate().
578 Before the call of deflateParams, the stream state must be set as for
579 a call of deflate(), since the currently available input may have to
580 be compressed and flushed. In particular, strm->avail_out must be non-zero.
582 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
583 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
584 if strm->avail_out was zero.
588 extern int inflateInit2 (z_streamp strm, int windowBits);
590 This is another version of inflateInit with an extra parameter. The
591 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
592 before by the caller.
594 The windowBits parameter is the base two logarithm of the maximum window
595 size (the size of the history buffer). It should be in the range 8..15 for
596 this version of the library. The default value is 15 if inflateInit is used
597 instead. windowBits must be greater than or equal to the windowBits value
598 provided to deflateInit2() while compressing, or it must be equal to 15 if
599 deflateInit2() was not used. If a compressed stream with a larger window
600 size is given as input, inflate() will return with the error code
601 Z_DATA_ERROR instead of trying to allocate a larger window.
603 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
604 determines the window size. inflate() will then process raw deflate data,
605 not looking for a zlib or gzip header, not generating a check value, and not
606 looking for any check values for comparison at the end of the stream. This
607 is for use with other formats that use the deflate compressed data format
608 such as zip. Those formats provide their own check values. If a custom
609 format is developed using the raw deflate format for compressed data, it is
610 recommended that a check value such as an adler32 or a crc32 be applied to
611 the uncompressed data as is done in the zlib, gzip, and zip formats. For
612 most applications, the zlib format should be used as is. Note that comments
613 above on the use in deflateInit2() applies to the magnitude of windowBits.
615 windowBits can also be greater than 15 for optional gzip decoding. Add
616 32 to windowBits to enable zlib and gzip decoding with automatic header
617 detection, or add 16 to decode only the gzip format (the zlib format will
618 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
619 a crc32 instead of an adler32.
621 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
622 memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
623 is set to null if there is no error message. inflateInit2 does not perform
624 any decompression apart from reading the zlib header if present: this will
625 be done by inflate(). (So next_in and avail_in may be modified, but next_out
626 and avail_out are unchanged.)
629 extern int zlib_inflateSetDictionary (z_streamp strm,
630 const Byte *dictionary,
633 Initializes the decompression dictionary from the given uncompressed byte
634 sequence. This function must be called immediately after a call of inflate,
635 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
636 can be determined from the adler32 value returned by that call of inflate.
637 The compressor and decompressor must use exactly the same dictionary (see
638 deflateSetDictionary). For raw inflate, this function can be called
639 immediately after inflateInit2() or inflateReset() and before any call of
640 inflate() to set the dictionary. The application must insure that the
641 dictionary that was used for compression is provided.
643 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
644 parameter is invalid (such as NULL dictionary) or the stream state is
645 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
646 expected one (incorrect adler32 value). inflateSetDictionary does not
647 perform any decompression: this will be done by subsequent calls of
652 extern int zlib_inflateSync (z_streamp strm);
655 Skips invalid compressed data until a full flush point (see above the
656 description of deflate with Z_FULL_FLUSH) can be found, or until all
657 available input is skipped. No output is provided.
659 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
660 if no more input was provided, Z_DATA_ERROR if no flush point has been found,
661 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
662 case, the application may save the current current value of total_in which
663 indicates where valid compressed data was found. In the error case, the
664 application may repeatedly call inflateSync, providing more input each time,
665 until success or end of the input data.
668 extern int zlib_inflateReset (z_streamp strm);
670 This function is equivalent to inflateEnd followed by inflateInit,
671 but does not free and reallocate all the internal decompression state.
672 The stream will keep attributes that may have been set by inflateInit2.
674 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
675 stream state was inconsistent (such as zalloc or state being NULL).
678 extern int zlib_inflateIncomp (z_stream *strm);
680 This function adds the data at next_in (avail_in bytes) to the output
681 history without performing any output. There must be no pending output,
682 and the decompressor must be expecting to see the start of a block.
683 Calling this function is equivalent to decompressing a stored block
684 containing the data at next_in (except that the data is not output).
687 #define zlib_deflateInit(strm, level) \
688 zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \
689 DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
690 #define zlib_inflateInit(strm) \
691 zlib_inflateInit2((strm), DEF_WBITS)
693 extern int zlib_deflateInit2(z_streamp strm, int level, int method,
694 int windowBits, int memLevel,
696 extern int zlib_inflateInit2(z_streamp strm, int windowBits);
698 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
699 struct internal_state {int dummy;}; /* hack for buggy compilers */
702 /* Utility function: initialize zlib, unpack binary blob, clean up zlib,
703 * return len or negative error code. */
704 extern int zlib_inflate_blob(void *dst, unsigned dst_sz, const void *src, unsigned src_sz);
Code Review / linux-2.6.git / blob