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1da177e4 | 1 | /* zlib.h -- interface of the 'zlib' general purpose compression library |
1da177e4 | 2 | |
4f3865fb | 3 | Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler |
1da177e4 LT |
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 | |
7f317d34 | 26 | Comments) 1950 to 1952 in the files https://www.ietf.org/rfc/rfc1950.txt |
1da177e4 LT |
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 | ||
4f3865fb RP |
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 | */ | |
1da177e4 LT |
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 | ||
4f3865fb RP |
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 | ||
1da177e4 LT |
69 | The library also supports reading and writing files in gzip (.gz) format |
70 | with an interface similar to that of stdio. | |
71 | ||
4f3865fb RP |
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 | ||
1da177e4 LT |
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 { | |
8336793b | 85 | const Byte *next_in; /* next input byte */ |
d97b07c5 | 86 | uLong avail_in; /* number of bytes available at next_in */ |
1da177e4 LT |
87 | uLong total_in; /* total nb of input bytes read so far */ |
88 | ||
89 | Byte *next_out; /* next output byte should be put there */ | |
d97b07c5 | 90 | uLong avail_out; /* remaining free space at next_out */ |
1da177e4 LT |
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 | |
4f3865fb RP |
145 | #define Z_BLOCK 6 /* Only for inflate at present */ |
146 | /* Allowed flush values; see deflate() and inflate() below for details */ | |
1da177e4 LT |
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 | ||
565d76cb | 182 | extern int zlib_deflate_workspacesize (int windowBits, int memLevel); |
1da177e4 LT |
183 | /* |
184 | Returns the number of bytes that needs to be allocated for a per- | |
565d76cb JK |
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. | |
1da177e4 LT |
192 | */ |
193 | ||
803521b1 MZ |
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 | ||
1da177e4 LT |
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 | |
4f3865fb RP |
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. | |
1da177e4 LT |
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 | ||
4f3865fb RP |
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. | |
1da177e4 LT |
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 | |
4f3865fb | 401 | is never required, but can be used to inform inflate that a faster approach |
1da177e4 LT |
402 | may be used for the single inflate() call. |
403 | ||
4f3865fb RP |
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. | |
1da177e4 LT |
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 | |
4f3865fb RP |
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. | |
1da177e4 LT |
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 | */ | |
1da177e4 LT |
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 | ||
243393c9 LT |
514 | static inline unsigned long deflateBound(unsigned long s) |
515 | { | |
516 | return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11; | |
517 | } | |
518 | ||
1da177e4 LT |
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 | |
4f3865fb RP |
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.) | |
1da177e4 LT |
559 | */ |
560 | ||
1da177e4 LT |
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 | ||
1da177e4 | 580 | #define zlib_deflateInit(strm, level) \ |
4f3865fb RP |
581 | zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \ |
582 | DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY) | |
1da177e4 | 583 | #define zlib_inflateInit(strm) \ |
4f3865fb | 584 | zlib_inflateInit2((strm), DEF_WBITS) |
1da177e4 | 585 | |
4f3865fb RP |
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); | |
1da177e4 LT |
590 | |
591 | #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL) | |
592 | struct internal_state {int dummy;}; /* hack for buggy compilers */ | |
593 | #endif | |
594 | ||
8336793b DV |
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 | ||
1da177e4 | 599 | #endif /* _ZLIB_H */ |