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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 http://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 | uInt 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 | uInt 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 | /* |
195 | extern int deflateInit (z_streamp strm, int level); |
196 | |
197 | Initializes the internal stream state for compression. The fields |
198 | zalloc, zfree and opaque must be initialized before by the caller. |
199 | If zalloc and zfree are set to NULL, deflateInit updates them to |
200 | use default allocation functions. |
201 | |
202 | The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9: |
203 | 1 gives best speed, 9 gives best compression, 0 gives no compression at |
204 | all (the input data is simply copied a block at a time). |
205 | Z_DEFAULT_COMPRESSION requests a default compromise between speed and |
206 | compression (currently equivalent to level 6). |
207 | |
208 | deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not |
209 | enough memory, Z_STREAM_ERROR if level is not a valid compression level, |
210 | Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible |
211 | with the version assumed by the caller (ZLIB_VERSION). |
212 | msg is set to null if there is no error message. deflateInit does not |
213 | perform any compression: this will be done by deflate(). |
214 | */ |
215 | |
216 | |
217 | extern int zlib_deflate (z_streamp strm, int flush); |
218 | /* |
219 | deflate compresses as much data as possible, and stops when the input |
220 | buffer becomes empty or the output buffer becomes full. It may introduce some |
221 | output latency (reading input without producing any output) except when |
222 | forced to flush. |
223 | |
224 | The detailed semantics are as follows. deflate performs one or both of the |
225 | following actions: |
226 | |
227 | - Compress more input starting at next_in and update next_in and avail_in |
228 | accordingly. If not all input can be processed (because there is not |
229 | enough room in the output buffer), next_in and avail_in are updated and |
230 | processing will resume at this point for the next call of deflate(). |
231 | |
232 | - Provide more output starting at next_out and update next_out and avail_out |
233 | accordingly. This action is forced if the parameter flush is non zero. |
234 | Forcing flush frequently degrades the compression ratio, so this parameter |
235 | should be set only when necessary (in interactive applications). |
236 | Some output may be provided even if flush is not set. |
237 | |
238 | Before the call of deflate(), the application should ensure that at least |
239 | one of the actions is possible, by providing more input and/or consuming |
240 | more output, and updating avail_in or avail_out accordingly; avail_out |
241 | should never be zero before the call. The application can consume the |
242 | compressed output when it wants, for example when the output buffer is full |
243 | (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK |
244 | and with zero avail_out, it must be called again after making room in the |
245 | output buffer because there might be more output pending. |
246 | |
247 | If the parameter flush is set to Z_SYNC_FLUSH, all pending output is |
248 | flushed to the output buffer and the output is aligned on a byte boundary, so |
249 | that the decompressor can get all input data available so far. (In particular |
250 | avail_in is zero after the call if enough output space has been provided |
251 | before the call.) Flushing may degrade compression for some compression |
252 | algorithms and so it should be used only when necessary. |
253 | |
254 | If flush is set to Z_FULL_FLUSH, all output is flushed as with |
255 | Z_SYNC_FLUSH, and the compression state is reset so that decompression can |
256 | restart from this point if previous compressed data has been damaged or if |
257 | random access is desired. Using Z_FULL_FLUSH too often can seriously degrade |
258 | the compression. |
259 | |
260 | If deflate returns with avail_out == 0, this function must be called again |
261 | with the same value of the flush parameter and more output space (updated |
262 | avail_out), until the flush is complete (deflate returns with non-zero |
263 | avail_out). |
264 | |
265 | If the parameter flush is set to Z_FINISH, pending input is processed, |
266 | pending output is flushed and deflate returns with Z_STREAM_END if there |
267 | was enough output space; if deflate returns with Z_OK, this function must be |
268 | called again with Z_FINISH and more output space (updated avail_out) but no |
269 | more input data, until it returns with Z_STREAM_END or an error. After |
270 | deflate has returned Z_STREAM_END, the only possible operations on the |
271 | stream are deflateReset or deflateEnd. |
272 | |
273 | Z_FINISH can be used immediately after deflateInit if all the compression |
274 | is to be done in a single step. In this case, avail_out must be at least |
275 | 0.1% larger than avail_in plus 12 bytes. If deflate does not return |
276 | Z_STREAM_END, then it must be called again as described above. |
277 | |
278 | deflate() sets strm->adler to the adler32 checksum of all input read |
279 | so far (that is, total_in bytes). |
280 | |
281 | deflate() may update data_type if it can make a good guess about |
282 | the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered |
283 | binary. This field is only for information purposes and does not affect |
284 | the compression algorithm in any manner. |
285 | |
286 | deflate() returns Z_OK if some progress has been made (more input |
287 | processed or more output produced), Z_STREAM_END if all input has been |
288 | consumed and all output has been produced (only when flush is set to |
289 | Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example |
290 | if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible |
291 | (for example avail_in or avail_out was zero). |
292 | */ |
293 | |
294 | |
295 | extern int zlib_deflateEnd (z_streamp strm); |
296 | /* |
297 | All dynamically allocated data structures for this stream are freed. |
298 | This function discards any unprocessed input and does not flush any |
299 | pending output. |
300 | |
301 | deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the |
302 | stream state was inconsistent, Z_DATA_ERROR if the stream was freed |
303 | prematurely (some input or output was discarded). In the error case, |
304 | msg may be set but then points to a static string (which must not be |
305 | deallocated). |
306 | */ |
307 | |
308 | |
309 | extern int zlib_inflate_workspacesize (void); |
310 | /* |
311 | Returns the number of bytes that needs to be allocated for a per- |
312 | stream workspace. A pointer to this number of bytes should be |
313 | returned in stream->workspace before calling zlib_inflateInit(). |
314 | */ |
315 | |
316 | /* |
317 | extern int zlib_inflateInit (z_streamp strm); |
318 | |
319 | Initializes the internal stream state for decompression. The fields |
320 | next_in, avail_in, and workspace must be initialized before by |
321 | the caller. If next_in is not NULL and avail_in is large enough (the exact |
322 | value depends on the compression method), inflateInit determines the |
323 | compression method from the zlib header and allocates all data structures |
324 | accordingly; otherwise the allocation will be deferred to the first call of |
325 | inflate. If zalloc and zfree are set to NULL, inflateInit updates them to |
326 | use default allocation functions. |
327 | |
328 | inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough |
329 | memory, Z_VERSION_ERROR if the zlib library version is incompatible with the |
330 | version assumed by the caller. msg is set to null if there is no error |
331 | message. inflateInit does not perform any decompression apart from reading |
332 | the zlib header if present: this will be done by inflate(). (So next_in and |
333 | avail_in may be modified, but next_out and avail_out are unchanged.) |
334 | */ |
335 | |
336 | |
337 | extern int zlib_inflate (z_streamp strm, int flush); |
338 | /* |
339 | inflate decompresses as much data as possible, and stops when the input |
340 | buffer becomes empty or the output buffer becomes full. It may introduce |
341 | some output latency (reading input without producing any output) except when |
342 | forced to flush. |
343 | |
344 | The detailed semantics are as follows. inflate performs one or both of the |
345 | following actions: |
346 | |
347 | - Decompress more input starting at next_in and update next_in and avail_in |
348 | accordingly. If not all input can be processed (because there is not |
349 | enough room in the output buffer), next_in is updated and processing |
350 | will resume at this point for the next call of inflate(). |
351 | |
352 | - Provide more output starting at next_out and update next_out and avail_out |
353 | accordingly. inflate() provides as much output as possible, until there |
354 | is no more input data or no more space in the output buffer (see below |
355 | about the flush parameter). |
356 | |
357 | Before the call of inflate(), the application should ensure that at least |
358 | one of the actions is possible, by providing more input and/or consuming |
359 | more output, and updating the next_* and avail_* values accordingly. |
360 | The application can consume the uncompressed output when it wants, for |
361 | example when the output buffer is full (avail_out == 0), or after each |
362 | call of inflate(). If inflate returns Z_OK and with zero avail_out, it |
363 | must be called again after making room in the output buffer because there |
364 | might be more output pending. |
365 | |
366 | The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, |
367 | Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much |
368 | output as possible to the output buffer. Z_BLOCK requests that inflate() stop |
369 | if and when it gets to the next deflate block boundary. When decoding the |
370 | zlib or gzip format, this will cause inflate() to return immediately after |
371 | the header and before the first block. When doing a raw inflate, inflate() |
372 | will go ahead and process the first block, and will return when it gets to |
373 | the end of that block, or when it runs out of data. |
374 | |
375 | The Z_BLOCK option assists in appending to or combining deflate streams. |
376 | Also to assist in this, on return inflate() will set strm->data_type to the |
377 | number of unused bits in the last byte taken from strm->next_in, plus 64 |
378 | if inflate() is currently decoding the last block in the deflate stream, |
379 | plus 128 if inflate() returned immediately after decoding an end-of-block |
380 | code or decoding the complete header up to just before the first byte of the |
381 | deflate stream. The end-of-block will not be indicated until all of the |
382 | uncompressed data from that block has been written to strm->next_out. The |
383 | number of unused bits may in general be greater than seven, except when |
384 | bit 7 of data_type is set, in which case the number of unused bits will be |
385 | less than eight. |
386 | |
387 | inflate() should normally be called until it returns Z_STREAM_END or an |
388 | error. However if all decompression is to be performed in a single step |
389 | (a single call of inflate), the parameter flush should be set to |
390 | Z_FINISH. In this case all pending input is processed and all pending |
391 | output is flushed; avail_out must be large enough to hold all the |
392 | uncompressed data. (The size of the uncompressed data may have been saved |
393 | by the compressor for this purpose.) The next operation on this stream must |
394 | be inflateEnd to deallocate the decompression state. The use of Z_FINISH |
395 | is never required, but can be used to inform inflate that a faster approach |
396 | may be used for the single inflate() call. |
397 | |
398 | In this implementation, inflate() always flushes as much output as |
399 | possible to the output buffer, and always uses the faster approach on the |
400 | first call. So the only effect of the flush parameter in this implementation |
401 | is on the return value of inflate(), as noted below, or when it returns early |
402 | because Z_BLOCK is used. |
403 | |
404 | If a preset dictionary is needed after this call (see inflateSetDictionary |
405 | below), inflate sets strm->adler to the adler32 checksum of the dictionary |
406 | chosen by the compressor and returns Z_NEED_DICT; otherwise it sets |
407 | strm->adler to the adler32 checksum of all output produced so far (that is, |
408 | total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described |
409 | below. At the end of the stream, inflate() checks that its computed adler32 |
410 | checksum is equal to that saved by the compressor and returns Z_STREAM_END |
411 | only if the checksum is correct. |
412 | |
413 | inflate() will decompress and check either zlib-wrapped or gzip-wrapped |
414 | deflate data. The header type is detected automatically. Any information |
415 | contained in the gzip header is not retained, so applications that need that |
416 | information should instead use raw inflate, see inflateInit2() below, or |
417 | inflateBack() and perform their own processing of the gzip header and |
418 | trailer. |
419 | |
420 | inflate() returns Z_OK if some progress has been made (more input processed |
421 | or more output produced), Z_STREAM_END if the end of the compressed data has |
422 | been reached and all uncompressed output has been produced, Z_NEED_DICT if a |
423 | preset dictionary is needed at this point, Z_DATA_ERROR if the input data was |
424 | corrupted (input stream not conforming to the zlib format or incorrect check |
425 | value), Z_STREAM_ERROR if the stream structure was inconsistent (for example |
426 | if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory, |
427 | Z_BUF_ERROR if no progress is possible or if there was not enough room in the |
428 | output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and |
429 | inflate() can be called again with more input and more output space to |
430 | continue decompressing. If Z_DATA_ERROR is returned, the application may then |
431 | call inflateSync() to look for a good compression block if a partial recovery |
432 | of the data is desired. |
433 | */ |
434 | |
435 | |
436 | extern int zlib_inflateEnd (z_streamp strm); |
437 | /* |
438 | All dynamically allocated data structures for this stream are freed. |
439 | This function discards any unprocessed input and does not flush any |
440 | pending output. |
441 | |
442 | inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state |
443 | was inconsistent. In the error case, msg may be set but then points to a |
444 | static string (which must not be deallocated). |
445 | */ |
446 | |
447 | /* Advanced functions */ |
448 | |
449 | /* |
450 | The following functions are needed only in some special applications. |
451 | */ |
452 | |
453 | /* |
454 | extern int deflateInit2 (z_streamp strm, |
455 | int level, |
456 | int method, |
457 | int windowBits, |
458 | int memLevel, |
459 | int strategy); |
460 | |
461 | This is another version of deflateInit with more compression options. The |
462 | fields next_in, zalloc, zfree and opaque must be initialized before by |
463 | the caller. |
464 | |
465 | The method parameter is the compression method. It must be Z_DEFLATED in |
466 | this version of the library. |
467 | |
468 | The windowBits parameter is the base two logarithm of the window size |
469 | (the size of the history buffer). It should be in the range 8..15 for this |
470 | version of the library. Larger values of this parameter result in better |
471 | compression at the expense of memory usage. The default value is 15 if |
472 | deflateInit is used instead. |
473 | |
474 | The memLevel parameter specifies how much memory should be allocated |
475 | for the internal compression state. memLevel=1 uses minimum memory but |
476 | is slow and reduces compression ratio; memLevel=9 uses maximum memory |
477 | for optimal speed. The default value is 8. See zconf.h for total memory |
478 | usage as a function of windowBits and memLevel. |
479 | |
480 | The strategy parameter is used to tune the compression algorithm. Use the |
481 | value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a |
482 | filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no |
483 | string match). Filtered data consists mostly of small values with a |
484 | somewhat random distribution. In this case, the compression algorithm is |
485 | tuned to compress them better. The effect of Z_FILTERED is to force more |
486 | Huffman coding and less string matching; it is somewhat intermediate |
487 | between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects |
488 | the compression ratio but not the correctness of the compressed output even |
489 | if it is not set appropriately. |
490 | |
491 | deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough |
492 | memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid |
493 | method). msg is set to null if there is no error message. deflateInit2 does |
494 | not perform any compression: this will be done by deflate(). |
495 | */ |
496 | |
497 | #if 0 |
498 | extern int zlib_deflateSetDictionary (z_streamp strm, |
499 | const Byte *dictionary, |
500 | uInt dictLength); |
501 | #endif |
502 | /* |
503 | Initializes the compression dictionary from the given byte sequence |
504 | without producing any compressed output. This function must be called |
505 | immediately after deflateInit, deflateInit2 or deflateReset, before any |
506 | call of deflate. The compressor and decompressor must use exactly the same |
507 | dictionary (see inflateSetDictionary). |
508 | |
509 | The dictionary should consist of strings (byte sequences) that are likely |
510 | to be encountered later in the data to be compressed, with the most commonly |
511 | used strings preferably put towards the end of the dictionary. Using a |
512 | dictionary is most useful when the data to be compressed is short and can be |
513 | predicted with good accuracy; the data can then be compressed better than |
514 | with the default empty dictionary. |
515 | |
516 | Depending on the size of the compression data structures selected by |
517 | deflateInit or deflateInit2, a part of the dictionary may in effect be |
518 | discarded, for example if the dictionary is larger than the window size in |
519 | deflate or deflate2. Thus the strings most likely to be useful should be |
520 | put at the end of the dictionary, not at the front. |
521 | |
522 | Upon return of this function, strm->adler is set to the Adler32 value |
523 | of the dictionary; the decompressor may later use this value to determine |
524 | which dictionary has been used by the compressor. (The Adler32 value |
525 | applies to the whole dictionary even if only a subset of the dictionary is |
526 | actually used by the compressor.) |
527 | |
528 | deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a |
529 | parameter is invalid (such as NULL dictionary) or the stream state is |
530 | inconsistent (for example if deflate has already been called for this stream |
531 | or if the compression method is bsort). deflateSetDictionary does not |
532 | perform any compression: this will be done by deflate(). |
533 | */ |
534 | |
535 | #if 0 |
536 | extern int zlib_deflateCopy (z_streamp dest, z_streamp source); |
537 | #endif |
538 | |
539 | /* |
540 | Sets the destination stream as a complete copy of the source stream. |
541 | |
542 | This function can be useful when several compression strategies will be |
543 | tried, for example when there are several ways of pre-processing the input |
544 | data with a filter. The streams that will be discarded should then be freed |
545 | by calling deflateEnd. Note that deflateCopy duplicates the internal |
546 | compression state which can be quite large, so this strategy is slow and |
547 | can consume lots of memory. |
548 | |
549 | deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not |
550 | enough memory, Z_STREAM_ERROR if the source stream state was inconsistent |
551 | (such as zalloc being NULL). msg is left unchanged in both source and |
552 | destination. |
553 | */ |
554 | |
555 | extern int zlib_deflateReset (z_streamp strm); |
556 | /* |
557 | This function is equivalent to deflateEnd followed by deflateInit, |
558 | but does not free and reallocate all the internal compression state. |
559 | The stream will keep the same compression level and any other attributes |
560 | that may have been set by deflateInit2. |
561 | |
562 | deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source |
563 | stream state was inconsistent (such as zalloc or state being NULL). |
564 | */ |
565 | |
566 | static inline unsigned long deflateBound(unsigned long s) |
567 | { |
568 | return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11; |
569 | } |
570 | |
571 | #if 0 |
572 | extern int zlib_deflateParams (z_streamp strm, int level, int strategy); |
573 | #endif |
574 | /* |
575 | Dynamically update the compression level and compression strategy. The |
576 | interpretation of level and strategy is as in deflateInit2. This can be |
577 | used to switch between compression and straight copy of the input data, or |
578 | to switch to a different kind of input data requiring a different |
579 | strategy. If the compression level is changed, the input available so far |
580 | is compressed with the old level (and may be flushed); the new level will |
581 | take effect only at the next call of deflate(). |
582 | |
583 | Before the call of deflateParams, the stream state must be set as for |
584 | a call of deflate(), since the currently available input may have to |
585 | be compressed and flushed. In particular, strm->avail_out must be non-zero. |
586 | |
587 | deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source |
588 | stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR |
589 | if strm->avail_out was zero. |
590 | */ |
591 | |
592 | /* |
593 | extern int inflateInit2 (z_streamp strm, int windowBits); |
594 | |
595 | This is another version of inflateInit with an extra parameter. The |
596 | fields next_in, avail_in, zalloc, zfree and opaque must be initialized |
597 | before by the caller. |
598 | |
599 | The windowBits parameter is the base two logarithm of the maximum window |
600 | size (the size of the history buffer). It should be in the range 8..15 for |
601 | this version of the library. The default value is 15 if inflateInit is used |
602 | instead. windowBits must be greater than or equal to the windowBits value |
603 | provided to deflateInit2() while compressing, or it must be equal to 15 if |
604 | deflateInit2() was not used. If a compressed stream with a larger window |
605 | size is given as input, inflate() will return with the error code |
606 | Z_DATA_ERROR instead of trying to allocate a larger window. |
607 | |
608 | windowBits can also be -8..-15 for raw inflate. In this case, -windowBits |
609 | determines the window size. inflate() will then process raw deflate data, |
610 | not looking for a zlib or gzip header, not generating a check value, and not |
611 | looking for any check values for comparison at the end of the stream. This |
612 | is for use with other formats that use the deflate compressed data format |
613 | such as zip. Those formats provide their own check values. If a custom |
614 | format is developed using the raw deflate format for compressed data, it is |
615 | recommended that a check value such as an adler32 or a crc32 be applied to |
616 | the uncompressed data as is done in the zlib, gzip, and zip formats. For |
617 | most applications, the zlib format should be used as is. Note that comments |
618 | above on the use in deflateInit2() applies to the magnitude of windowBits. |
619 | |
620 | windowBits can also be greater than 15 for optional gzip decoding. Add |
621 | 32 to windowBits to enable zlib and gzip decoding with automatic header |
622 | detection, or add 16 to decode only the gzip format (the zlib format will |
623 | return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is |
624 | a crc32 instead of an adler32. |
625 | |
626 | inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough |
627 | memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg |
628 | is set to null if there is no error message. inflateInit2 does not perform |
629 | any decompression apart from reading the zlib header if present: this will |
630 | be done by inflate(). (So next_in and avail_in may be modified, but next_out |
631 | and avail_out are unchanged.) |
632 | */ |
633 | |
634 | extern int zlib_inflateSetDictionary (z_streamp strm, |
635 | const Byte *dictionary, |
636 | uInt dictLength); |
637 | /* |
638 | Initializes the decompression dictionary from the given uncompressed byte |
639 | sequence. This function must be called immediately after a call of inflate, |
640 | if that call returned Z_NEED_DICT. The dictionary chosen by the compressor |
641 | can be determined from the adler32 value returned by that call of inflate. |
642 | The compressor and decompressor must use exactly the same dictionary (see |
643 | deflateSetDictionary). For raw inflate, this function can be called |
644 | immediately after inflateInit2() or inflateReset() and before any call of |
645 | inflate() to set the dictionary. The application must insure that the |
646 | dictionary that was used for compression is provided. |
647 | |
648 | inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a |
649 | parameter is invalid (such as NULL dictionary) or the stream state is |
650 | inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the |
651 | expected one (incorrect adler32 value). inflateSetDictionary does not |
652 | perform any decompression: this will be done by subsequent calls of |
653 | inflate(). |
654 | */ |
655 | |
656 | #if 0 |
657 | extern int zlib_inflateSync (z_streamp strm); |
658 | #endif |
659 | /* |
660 | Skips invalid compressed data until a full flush point (see above the |
661 | description of deflate with Z_FULL_FLUSH) can be found, or until all |
662 | available input is skipped. No output is provided. |
663 | |
664 | inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR |
665 | if no more input was provided, Z_DATA_ERROR if no flush point has been found, |
666 | or Z_STREAM_ERROR if the stream structure was inconsistent. In the success |
667 | case, the application may save the current current value of total_in which |
668 | indicates where valid compressed data was found. In the error case, the |
669 | application may repeatedly call inflateSync, providing more input each time, |
670 | until success or end of the input data. |
671 | */ |
672 | |
673 | extern int zlib_inflateReset (z_streamp strm); |
674 | /* |
675 | This function is equivalent to inflateEnd followed by inflateInit, |
676 | but does not free and reallocate all the internal decompression state. |
677 | The stream will keep attributes that may have been set by inflateInit2. |
678 | |
679 | inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source |
680 | stream state was inconsistent (such as zalloc or state being NULL). |
681 | */ |
682 | |
683 | extern int zlib_inflateIncomp (z_stream *strm); |
684 | /* |
685 | This function adds the data at next_in (avail_in bytes) to the output |
686 | history without performing any output. There must be no pending output, |
687 | and the decompressor must be expecting to see the start of a block. |
688 | Calling this function is equivalent to decompressing a stored block |
689 | containing the data at next_in (except that the data is not output). |
690 | */ |
691 | |
692 | #define zlib_deflateInit(strm, level) \ |
693 | zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \ |
694 | DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY) |
695 | #define zlib_inflateInit(strm) \ |
696 | zlib_inflateInit2((strm), DEF_WBITS) |
697 | |
698 | extern int zlib_deflateInit2(z_streamp strm, int level, int method, |
699 | int windowBits, int memLevel, |
700 | int strategy); |
701 | extern int zlib_inflateInit2(z_streamp strm, int windowBits); |
702 | |
703 | #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL) |
704 | struct internal_state {int dummy;}; /* hack for buggy compilers */ |
705 | #endif |
706 | |
707 | /* Utility function: initialize zlib, unpack binary blob, clean up zlib, |
708 | * return len or negative error code. */ |
709 | extern int zlib_inflate_blob(void *dst, unsigned dst_sz, const void *src, unsigned src_sz); |
710 | |
711 | #endif /* _ZLIB_H */ |
712 |
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