1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 
3   Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
4 
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.
8 
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:
12 
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.
20 
21   Jean-loup Gailly        Mark Adler
22   jloup@gzip.org          madler@alumni.caltech.edu
23 
24 
25   The data format used by the zlib library is described by RFCs (Request for
26   Comments) 1950 to 1952 in the files https://www.ietf.org/rfc/rfc1950.txt
27   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
28 */
29 
30 #ifndef _ZLIB_H
31 #define _ZLIB_H
32 
33 #include <linux/zconf.h>
34 
35 /* zlib deflate based on ZLIB_VERSION "1.1.3" */
36 /* zlib inflate based on ZLIB_VERSION "1.2.3" */
37 
38 /*
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.
41 
42   Inflation Changes:
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.
50 */
51 
52 /*
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
57   stream interface.
58 
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.
64 
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.
68 
69      The library also supports reading and writing files in gzip (.gz) format
70   with an interface similar to that of stdio.
71 
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.
76 
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.
80 */
81 
82 struct internal_state;
83 
84 typedef struct z_stream_s {
85     const Byte *next_in;   /* next input byte */
86 	uLong avail_in;  /* number of bytes available at next_in */
87     uLong    total_in;  /* total nb of input bytes read so far */
88 
89     Byte    *next_out;  /* next output byte should be put there */
90 	uLong avail_out; /* remaining free space at next_out */
91     uLong    total_out; /* total nb of bytes output so far */
92 
93     char     *msg;      /* last error message, NULL if no error */
94     struct internal_state *state; /* not visible by applications */
95 
96     void     *workspace; /* memory allocated for this stream */
97 
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 */
101 } z_stream;
102 
103 typedef z_stream *z_streamp;
104 
105 /*
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.
111 
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
115    opaque value.
116 
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
119    thread safe.
120 
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).
129 
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
134    a single step).
135 */
136 
137                         /* constants */
138 
139 #define Z_NO_FLUSH      0
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
144 #define Z_FINISH        5
145 #define Z_BLOCK         6 /* Only for inflate at present */
146 /* Allowed flush values; see deflate() and inflate() below for details */
147 
148 #define Z_OK            0
149 #define Z_STREAM_END    1
150 #define Z_NEED_DICT     2
151 #define Z_ERRNO        (-1)
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.
159  */
160 
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 */
166 
167 #define Z_FILTERED            1
168 #define Z_HUFFMAN_ONLY        2
169 #define Z_DEFAULT_STRATEGY    0
170 /* compression strategy; see deflateInit2() below for details */
171 
172 #define Z_BINARY   0
173 #define Z_ASCII    1
174 #define Z_UNKNOWN  2
175 /* Possible values of the data_type field */
176 
177 #define Z_DEFLATED   8
178 /* The deflate compression method (the only one supported in this version) */
179 
180                         /* basic functions */
181 
182 extern int zlib_deflate_workspacesize (int windowBits, int memLevel);
183 /*
184    Returns the number of bytes that needs to be allocated for a per-
185    stream workspace with the specified parameters.  A pointer to this
186    number of bytes should be returned in stream->workspace before
187    you call zlib_deflateInit() or zlib_deflateInit2().  If you call
188    zlib_deflateInit(), specify windowBits = MAX_WBITS and memLevel =
189    MAX_MEM_LEVEL here.  If you call zlib_deflateInit2(), the windowBits
190    and memLevel parameters passed to zlib_deflateInit2() must not
191    exceed those passed here.
192 */
193 
194 extern int zlib_deflate_dfltcc_enabled (void);
195 /*
196    Returns 1 if Deflate-Conversion facility is installed and enabled,
197    otherwise 0.
198 */
199 
200 /*
201 extern int deflateInit (z_streamp strm, int level);
202 
203      Initializes the internal stream state for compression. The fields
204    zalloc, zfree and opaque must be initialized before by the caller.
205    If zalloc and zfree are set to NULL, deflateInit updates them to
206    use default allocation functions.
207 
208      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
209    1 gives best speed, 9 gives best compression, 0 gives no compression at
210    all (the input data is simply copied a block at a time).
211    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
212    compression (currently equivalent to level 6).
213 
214      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
215    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
216    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
217    with the version assumed by the caller (ZLIB_VERSION).
218    msg is set to null if there is no error message.  deflateInit does not
219    perform any compression: this will be done by deflate().
220 */
221 
222 
223 extern int zlib_deflate (z_streamp strm, int flush);
224 /*
225     deflate compresses as much data as possible, and stops when the input
226   buffer becomes empty or the output buffer becomes full. It may introduce some
227   output latency (reading input without producing any output) except when
228   forced to flush.
229 
230     The detailed semantics are as follows. deflate performs one or both of the
231   following actions:
232 
233   - Compress more input starting at next_in and update next_in and avail_in
234     accordingly. If not all input can be processed (because there is not
235     enough room in the output buffer), next_in and avail_in are updated and
236     processing will resume at this point for the next call of deflate().
237 
238   - Provide more output starting at next_out and update next_out and avail_out
239     accordingly. This action is forced if the parameter flush is non zero.
240     Forcing flush frequently degrades the compression ratio, so this parameter
241     should be set only when necessary (in interactive applications).
242     Some output may be provided even if flush is not set.
243 
244   Before the call of deflate(), the application should ensure that at least
245   one of the actions is possible, by providing more input and/or consuming
246   more output, and updating avail_in or avail_out accordingly; avail_out
247   should never be zero before the call. The application can consume the
248   compressed output when it wants, for example when the output buffer is full
249   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
250   and with zero avail_out, it must be called again after making room in the
251   output buffer because there might be more output pending.
252 
253     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
254   flushed to the output buffer and the output is aligned on a byte boundary, so
255   that the decompressor can get all input data available so far. (In particular
256   avail_in is zero after the call if enough output space has been provided
257   before the call.)  Flushing may degrade compression for some compression
258   algorithms and so it should be used only when necessary.
259 
260     If flush is set to Z_FULL_FLUSH, all output is flushed as with
261   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
262   restart from this point if previous compressed data has been damaged or if
263   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
264   the compression.
265 
266     If deflate returns with avail_out == 0, this function must be called again
267   with the same value of the flush parameter and more output space (updated
268   avail_out), until the flush is complete (deflate returns with non-zero
269   avail_out).
270 
271     If the parameter flush is set to Z_FINISH, pending input is processed,
272   pending output is flushed and deflate returns with Z_STREAM_END if there
273   was enough output space; if deflate returns with Z_OK, this function must be
274   called again with Z_FINISH and more output space (updated avail_out) but no
275   more input data, until it returns with Z_STREAM_END or an error. After
276   deflate has returned Z_STREAM_END, the only possible operations on the
277   stream are deflateReset or deflateEnd.
278 
279     Z_FINISH can be used immediately after deflateInit if all the compression
280   is to be done in a single step. In this case, avail_out must be at least
281   0.1% larger than avail_in plus 12 bytes.  If deflate does not return
282   Z_STREAM_END, then it must be called again as described above.
283 
284     deflate() sets strm->adler to the adler32 checksum of all input read
285   so far (that is, total_in bytes).
286 
287     deflate() may update data_type if it can make a good guess about
288   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
289   binary. This field is only for information purposes and does not affect
290   the compression algorithm in any manner.
291 
292     deflate() returns Z_OK if some progress has been made (more input
293   processed or more output produced), Z_STREAM_END if all input has been
294   consumed and all output has been produced (only when flush is set to
295   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
296   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
297   (for example avail_in or avail_out was zero).
298 */
299 
300 
301 extern int zlib_deflateEnd (z_streamp strm);
302 /*
303      All dynamically allocated data structures for this stream are freed.
304    This function discards any unprocessed input and does not flush any
305    pending output.
306 
307      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
308    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
309    prematurely (some input or output was discarded). In the error case,
310    msg may be set but then points to a static string (which must not be
311    deallocated).
312 */
313 
314 
315 extern int zlib_inflate_workspacesize (void);
316 /*
317    Returns the number of bytes that needs to be allocated for a per-
318    stream workspace.  A pointer to this number of bytes should be
319    returned in stream->workspace before calling zlib_inflateInit().
320 */
321 
322 /*
323 extern int zlib_inflateInit (z_streamp strm);
324 
325      Initializes the internal stream state for decompression. The fields
326    next_in, avail_in, and workspace must be initialized before by
327    the caller. If next_in is not NULL and avail_in is large enough (the exact
328    value depends on the compression method), inflateInit determines the
329    compression method from the zlib header and allocates all data structures
330    accordingly; otherwise the allocation will be deferred to the first call of
331    inflate.  If zalloc and zfree are set to NULL, inflateInit updates them to
332    use default allocation functions.
333 
334      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
335    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
336    version assumed by the caller.  msg is set to null if there is no error
337    message. inflateInit does not perform any decompression apart from reading
338    the zlib header if present: this will be done by inflate().  (So next_in and
339    avail_in may be modified, but next_out and avail_out are unchanged.)
340 */
341 
342 
343 extern int zlib_inflate (z_streamp strm, int flush);
344 /*
345     inflate decompresses as much data as possible, and stops when the input
346   buffer becomes empty or the output buffer becomes full. It may introduce
347   some output latency (reading input without producing any output) except when
348   forced to flush.
349 
350   The detailed semantics are as follows. inflate performs one or both of the
351   following actions:
352 
353   - Decompress more input starting at next_in and update next_in and avail_in
354     accordingly. If not all input can be processed (because there is not
355     enough room in the output buffer), next_in is updated and processing
356     will resume at this point for the next call of inflate().
357 
358   - Provide more output starting at next_out and update next_out and avail_out
359     accordingly.  inflate() provides as much output as possible, until there
360     is no more input data or no more space in the output buffer (see below
361     about the flush parameter).
362 
363   Before the call of inflate(), the application should ensure that at least
364   one of the actions is possible, by providing more input and/or consuming
365   more output, and updating the next_* and avail_* values accordingly.
366   The application can consume the uncompressed output when it wants, for
367   example when the output buffer is full (avail_out == 0), or after each
368   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
369   must be called again after making room in the output buffer because there
370   might be more output pending.
371 
372     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
373   Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
374   output as possible to the output buffer. Z_BLOCK requests that inflate() stop
375   if and when it gets to the next deflate block boundary. When decoding the
376   zlib or gzip format, this will cause inflate() to return immediately after
377   the header and before the first block. When doing a raw inflate, inflate()
378   will go ahead and process the first block, and will return when it gets to
379   the end of that block, or when it runs out of data.
380 
381     The Z_BLOCK option assists in appending to or combining deflate streams.
382   Also to assist in this, on return inflate() will set strm->data_type to the
383   number of unused bits in the last byte taken from strm->next_in, plus 64
384   if inflate() is currently decoding the last block in the deflate stream,
385   plus 128 if inflate() returned immediately after decoding an end-of-block
386   code or decoding the complete header up to just before the first byte of the
387   deflate stream. The end-of-block will not be indicated until all of the
388   uncompressed data from that block has been written to strm->next_out.  The
389   number of unused bits may in general be greater than seven, except when
390   bit 7 of data_type is set, in which case the number of unused bits will be
391   less than eight.
392 
393     inflate() should normally be called until it returns Z_STREAM_END or an
394   error. However if all decompression is to be performed in a single step
395   (a single call of inflate), the parameter flush should be set to
396   Z_FINISH. In this case all pending input is processed and all pending
397   output is flushed; avail_out must be large enough to hold all the
398   uncompressed data. (The size of the uncompressed data may have been saved
399   by the compressor for this purpose.) The next operation on this stream must
400   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
401   is never required, but can be used to inform inflate that a faster approach
402   may be used for the single inflate() call.
403 
404      In this implementation, inflate() always flushes as much output as
405   possible to the output buffer, and always uses the faster approach on the
406   first call. So the only effect of the flush parameter in this implementation
407   is on the return value of inflate(), as noted below, or when it returns early
408   because Z_BLOCK is used.
409 
410      If a preset dictionary is needed after this call (see inflateSetDictionary
411   below), inflate sets strm->adler to the adler32 checksum of the dictionary
412   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
413   strm->adler to the adler32 checksum of all output produced so far (that is,
414   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
415   below. At the end of the stream, inflate() checks that its computed adler32
416   checksum is equal to that saved by the compressor and returns Z_STREAM_END
417   only if the checksum is correct.
418 
419     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
420   deflate data.  The header type is detected automatically.  Any information
421   contained in the gzip header is not retained, so applications that need that
422   information should instead use raw inflate, see inflateInit2() below, or
423   inflateBack() and perform their own processing of the gzip header and
424   trailer.
425 
426     inflate() returns Z_OK if some progress has been made (more input processed
427   or more output produced), Z_STREAM_END if the end of the compressed data has
428   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
429   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
430   corrupted (input stream not conforming to the zlib format or incorrect check
431   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
432   if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
433   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
434   output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
435   inflate() can be called again with more input and more output space to
436   continue decompressing. If Z_DATA_ERROR is returned, the application may then
437   call inflateSync() to look for a good compression block if a partial recovery
438   of the data is desired.
439 */
440 
441 
442 extern int zlib_inflateEnd (z_streamp strm);
443 /*
444      All dynamically allocated data structures for this stream are freed.
445    This function discards any unprocessed input and does not flush any
446    pending output.
447 
448      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
449    was inconsistent. In the error case, msg may be set but then points to a
450    static string (which must not be deallocated).
451 */
452 
453                         /* Advanced functions */
454 
455 /*
456     The following functions are needed only in some special applications.
457 */
458 
459 /*
460 extern int deflateInit2 (z_streamp strm,
461                                      int  level,
462                                      int  method,
463                                      int  windowBits,
464                                      int  memLevel,
465                                      int  strategy);
466 
467      This is another version of deflateInit with more compression options. The
468    fields next_in, zalloc, zfree and opaque must be initialized before by
469    the caller.
470 
471      The method parameter is the compression method. It must be Z_DEFLATED in
472    this version of the library.
473 
474      The windowBits parameter is the base two logarithm of the window size
475    (the size of the history buffer).  It should be in the range 8..15 for this
476    version of the library. Larger values of this parameter result in better
477    compression at the expense of memory usage. The default value is 15 if
478    deflateInit is used instead.
479 
480      The memLevel parameter specifies how much memory should be allocated
481    for the internal compression state. memLevel=1 uses minimum memory but
482    is slow and reduces compression ratio; memLevel=9 uses maximum memory
483    for optimal speed. The default value is 8. See zconf.h for total memory
484    usage as a function of windowBits and memLevel.
485 
486      The strategy parameter is used to tune the compression algorithm. Use the
487    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
488    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
489    string match).  Filtered data consists mostly of small values with a
490    somewhat random distribution. In this case, the compression algorithm is
491    tuned to compress them better. The effect of Z_FILTERED is to force more
492    Huffman coding and less string matching; it is somewhat intermediate
493    between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
494    the compression ratio but not the correctness of the compressed output even
495    if it is not set appropriately.
496 
497       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
498    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
499    method). msg is set to null if there is no error message.  deflateInit2 does
500    not perform any compression: this will be done by deflate().
501 */
502 
503 extern int zlib_deflateReset (z_streamp strm);
504 /*
505      This function is equivalent to deflateEnd followed by deflateInit,
506    but does not free and reallocate all the internal compression state.
507    The stream will keep the same compression level and any other attributes
508    that may have been set by deflateInit2.
509 
510       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
511    stream state was inconsistent (such as zalloc or state being NULL).
512 */
513 
deflateBound(unsigned long s)514 static inline unsigned long deflateBound(unsigned long s)
515 {
516 	return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11;
517 }
518 
519 /*
520 extern int inflateInit2 (z_streamp strm, int  windowBits);
521 
522      This is another version of inflateInit with an extra parameter. The
523    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
524    before by the caller.
525 
526      The windowBits parameter is the base two logarithm of the maximum window
527    size (the size of the history buffer).  It should be in the range 8..15 for
528    this version of the library. The default value is 15 if inflateInit is used
529    instead. windowBits must be greater than or equal to the windowBits value
530    provided to deflateInit2() while compressing, or it must be equal to 15 if
531    deflateInit2() was not used. If a compressed stream with a larger window
532    size is given as input, inflate() will return with the error code
533    Z_DATA_ERROR instead of trying to allocate a larger window.
534 
535      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
536    determines the window size. inflate() will then process raw deflate data,
537    not looking for a zlib or gzip header, not generating a check value, and not
538    looking for any check values for comparison at the end of the stream. This
539    is for use with other formats that use the deflate compressed data format
540    such as zip.  Those formats provide their own check values. If a custom
541    format is developed using the raw deflate format for compressed data, it is
542    recommended that a check value such as an adler32 or a crc32 be applied to
543    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
544    most applications, the zlib format should be used as is. Note that comments
545    above on the use in deflateInit2() applies to the magnitude of windowBits.
546 
547      windowBits can also be greater than 15 for optional gzip decoding. Add
548    32 to windowBits to enable zlib and gzip decoding with automatic header
549    detection, or add 16 to decode only the gzip format (the zlib format will
550    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is
551    a crc32 instead of an adler32.
552 
553      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
554    memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
555    is set to null if there is no error message.  inflateInit2 does not perform
556    any decompression apart from reading the zlib header if present: this will
557    be done by inflate(). (So next_in and avail_in may be modified, but next_out
558    and avail_out are unchanged.)
559 */
560 
561 extern int zlib_inflateReset (z_streamp strm);
562 /*
563      This function is equivalent to inflateEnd followed by inflateInit,
564    but does not free and reallocate all the internal decompression state.
565    The stream will keep attributes that may have been set by inflateInit2.
566 
567       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
568    stream state was inconsistent (such as zalloc or state being NULL).
569 */
570 
571 extern int zlib_inflateIncomp (z_stream *strm);
572 /*
573      This function adds the data at next_in (avail_in bytes) to the output
574    history without performing any output.  There must be no pending output,
575    and the decompressor must be expecting to see the start of a block.
576    Calling this function is equivalent to decompressing a stored block
577    containing the data at next_in (except that the data is not output).
578 */
579 
580 #define zlib_deflateInit(strm, level) \
581 	zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \
582 			      DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
583 #define zlib_inflateInit(strm) \
584 	zlib_inflateInit2((strm), DEF_WBITS)
585 
586 extern int zlib_deflateInit2(z_streamp strm, int  level, int  method,
587                                       int windowBits, int memLevel,
588                                       int strategy);
589 extern int zlib_inflateInit2(z_streamp strm, int  windowBits);
590 
591 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
592     struct internal_state {int dummy;}; /* hack for buggy compilers */
593 #endif
594 
595 /* Utility function: initialize zlib, unpack binary blob, clean up zlib,
596  * return len or negative error code. */
597 extern int zlib_inflate_blob(void *dst, unsigned dst_sz, const void *src, unsigned src_sz);
598 
599 #endif /* _ZLIB_H */
600