zlib.h 28 KB

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  1. /* zlib.h -- interface of the 'zlib' general purpose compression library
  2. Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
  3. This software is provided 'as-is', without any express or implied
  4. warranty. In no event will the authors be held liable for any damages
  5. arising from the use of this software.
  6. Permission is granted to anyone to use this software for any purpose,
  7. including commercial applications, and to alter it and redistribute it
  8. freely, subject to the following restrictions:
  9. 1. The origin of this software must not be misrepresented; you must not
  10. claim that you wrote the original software. If you use this software
  11. in a product, an acknowledgment in the product documentation would be
  12. appreciated but is not required.
  13. 2. Altered source versions must be plainly marked as such, and must not be
  14. misrepresented as being the original software.
  15. 3. This notice may not be removed or altered from any source distribution.
  16. Jean-loup Gailly Mark Adler
  17. jloup@gzip.org madler@alumni.caltech.edu
  18. The data format used by the zlib library is described by RFCs (Request for
  19. Comments) 1950 to 1952 in the files https://www.ietf.org/rfc/rfc1950.txt
  20. (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
  21. */
  22. #ifndef _ZLIB_H
  23. #define _ZLIB_H
  24. #include <linux/zconf.h>
  25. /* zlib deflate based on ZLIB_VERSION "1.1.3" */
  26. /* zlib inflate based on ZLIB_VERSION "1.2.3" */
  27. /*
  28. This is a modified version of zlib for use inside the Linux kernel.
  29. The main changes are to perform all memory allocation in advance.
  30. Inflation Changes:
  31. * Z_PACKET_FLUSH is added and used by ppp_deflate. Before returning
  32. this checks there is no more input data available and the next data
  33. is a STORED block. It also resets the mode to be read for the next
  34. data, all as per PPP requirements.
  35. * Addition of zlib_inflateIncomp which copies incompressible data into
  36. the history window and adjusts the accoutning without calling
  37. zlib_inflate itself to inflate the data.
  38. */
  39. /*
  40. The 'zlib' compression library provides in-memory compression and
  41. decompression functions, including integrity checks of the uncompressed
  42. data. This version of the library supports only one compression method
  43. (deflation) but other algorithms will be added later and will have the same
  44. stream interface.
  45. Compression can be done in a single step if the buffers are large
  46. enough (for example if an input file is mmap'ed), or can be done by
  47. repeated calls of the compression function. In the latter case, the
  48. application must provide more input and/or consume the output
  49. (providing more output space) before each call.
  50. The compressed data format used by default by the in-memory functions is
  51. the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
  52. around a deflate stream, which is itself documented in RFC 1951.
  53. The library also supports reading and writing files in gzip (.gz) format
  54. with an interface similar to that of stdio.
  55. The zlib format was designed to be compact and fast for use in memory
  56. and on communications channels. The gzip format was designed for single-
  57. file compression on file systems, has a larger header than zlib to maintain
  58. directory information, and uses a different, slower check method than zlib.
  59. The library does not install any signal handler. The decoder checks
  60. the consistency of the compressed data, so the library should never
  61. crash even in case of corrupted input.
  62. */
  63. struct internal_state;
  64. typedef struct z_stream_s {
  65. const Byte *next_in; /* next input byte */
  66. uLong avail_in; /* number of bytes available at next_in */
  67. uLong total_in; /* total nb of input bytes read so far */
  68. Byte *next_out; /* next output byte should be put there */
  69. uLong avail_out; /* remaining free space at next_out */
  70. uLong total_out; /* total nb of bytes output so far */
  71. char *msg; /* last error message, NULL if no error */
  72. struct internal_state *state; /* not visible by applications */
  73. void *workspace; /* memory allocated for this stream */
  74. int data_type; /* best guess about the data type: ascii or binary */
  75. uLong adler; /* adler32 value of the uncompressed data */
  76. uLong reserved; /* reserved for future use */
  77. } z_stream;
  78. typedef z_stream *z_streamp;
  79. /*
  80. The application must update next_in and avail_in when avail_in has
  81. dropped to zero. It must update next_out and avail_out when avail_out
  82. has dropped to zero. The application must initialize zalloc, zfree and
  83. opaque before calling the init function. All other fields are set by the
  84. compression library and must not be updated by the application.
  85. The opaque value provided by the application will be passed as the first
  86. parameter for calls of zalloc and zfree. This can be useful for custom
  87. memory management. The compression library attaches no meaning to the
  88. opaque value.
  89. zalloc must return NULL if there is not enough memory for the object.
  90. If zlib is used in a multi-threaded application, zalloc and zfree must be
  91. thread safe.
  92. On 16-bit systems, the functions zalloc and zfree must be able to allocate
  93. exactly 65536 bytes, but will not be required to allocate more than this
  94. if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
  95. pointers returned by zalloc for objects of exactly 65536 bytes *must*
  96. have their offset normalized to zero. The default allocation function
  97. provided by this library ensures this (see zutil.c). To reduce memory
  98. requirements and avoid any allocation of 64K objects, at the expense of
  99. compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
  100. The fields total_in and total_out can be used for statistics or
  101. progress reports. After compression, total_in holds the total size of
  102. the uncompressed data and may be saved for use in the decompressor
  103. (particularly if the decompressor wants to decompress everything in
  104. a single step).
  105. */
  106. /* constants */
  107. #define Z_NO_FLUSH 0
  108. #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
  109. #define Z_PACKET_FLUSH 2
  110. #define Z_SYNC_FLUSH 3
  111. #define Z_FULL_FLUSH 4
  112. #define Z_FINISH 5
  113. #define Z_BLOCK 6 /* Only for inflate at present */
  114. /* Allowed flush values; see deflate() and inflate() below for details */
  115. #define Z_OK 0
  116. #define Z_STREAM_END 1
  117. #define Z_NEED_DICT 2
  118. #define Z_ERRNO (-1)
  119. #define Z_STREAM_ERROR (-2)
  120. #define Z_DATA_ERROR (-3)
  121. #define Z_MEM_ERROR (-4)
  122. #define Z_BUF_ERROR (-5)
  123. #define Z_VERSION_ERROR (-6)
  124. /* Return codes for the compression/decompression functions. Negative
  125. * values are errors, positive values are used for special but normal events.
  126. */
  127. #define Z_NO_COMPRESSION 0
  128. #define Z_BEST_SPEED 1
  129. #define Z_BEST_COMPRESSION 9
  130. #define Z_DEFAULT_COMPRESSION (-1)
  131. /* compression levels */
  132. #define Z_FILTERED 1
  133. #define Z_HUFFMAN_ONLY 2
  134. #define Z_DEFAULT_STRATEGY 0
  135. /* compression strategy; see deflateInit2() below for details */
  136. #define Z_BINARY 0
  137. #define Z_ASCII 1
  138. #define Z_UNKNOWN 2
  139. /* Possible values of the data_type field */
  140. #define Z_DEFLATED 8
  141. /* The deflate compression method (the only one supported in this version) */
  142. /* basic functions */
  143. extern int zlib_deflate_workspacesize (int windowBits, int memLevel);
  144. /*
  145. Returns the number of bytes that needs to be allocated for a per-
  146. stream workspace with the specified parameters. A pointer to this
  147. number of bytes should be returned in stream->workspace before
  148. you call zlib_deflateInit() or zlib_deflateInit2(). If you call
  149. zlib_deflateInit(), specify windowBits = MAX_WBITS and memLevel =
  150. MAX_MEM_LEVEL here. If you call zlib_deflateInit2(), the windowBits
  151. and memLevel parameters passed to zlib_deflateInit2() must not
  152. exceed those passed here.
  153. */
  154. extern int zlib_deflate_dfltcc_enabled (void);
  155. /*
  156. Returns 1 if Deflate-Conversion facility is installed and enabled,
  157. otherwise 0.
  158. */
  159. /*
  160. extern int deflateInit (z_streamp strm, int level);
  161. Initializes the internal stream state for compression. The fields
  162. zalloc, zfree and opaque must be initialized before by the caller.
  163. If zalloc and zfree are set to NULL, deflateInit updates them to
  164. use default allocation functions.
  165. The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
  166. 1 gives best speed, 9 gives best compression, 0 gives no compression at
  167. all (the input data is simply copied a block at a time).
  168. Z_DEFAULT_COMPRESSION requests a default compromise between speed and
  169. compression (currently equivalent to level 6).
  170. deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
  171. enough memory, Z_STREAM_ERROR if level is not a valid compression level,
  172. Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
  173. with the version assumed by the caller (ZLIB_VERSION).
  174. msg is set to null if there is no error message. deflateInit does not
  175. perform any compression: this will be done by deflate().
  176. */
  177. extern int zlib_deflate (z_streamp strm, int flush);
  178. /*
  179. deflate compresses as much data as possible, and stops when the input
  180. buffer becomes empty or the output buffer becomes full. It may introduce some
  181. output latency (reading input without producing any output) except when
  182. forced to flush.
  183. The detailed semantics are as follows. deflate performs one or both of the
  184. following actions:
  185. - Compress more input starting at next_in and update next_in and avail_in
  186. accordingly. If not all input can be processed (because there is not
  187. enough room in the output buffer), next_in and avail_in are updated and
  188. processing will resume at this point for the next call of deflate().
  189. - Provide more output starting at next_out and update next_out and avail_out
  190. accordingly. This action is forced if the parameter flush is non zero.
  191. Forcing flush frequently degrades the compression ratio, so this parameter
  192. should be set only when necessary (in interactive applications).
  193. Some output may be provided even if flush is not set.
  194. Before the call of deflate(), the application should ensure that at least
  195. one of the actions is possible, by providing more input and/or consuming
  196. more output, and updating avail_in or avail_out accordingly; avail_out
  197. should never be zero before the call. The application can consume the
  198. compressed output when it wants, for example when the output buffer is full
  199. (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
  200. and with zero avail_out, it must be called again after making room in the
  201. output buffer because there might be more output pending.
  202. If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
  203. flushed to the output buffer and the output is aligned on a byte boundary, so
  204. that the decompressor can get all input data available so far. (In particular
  205. avail_in is zero after the call if enough output space has been provided
  206. before the call.) Flushing may degrade compression for some compression
  207. algorithms and so it should be used only when necessary.
  208. If flush is set to Z_FULL_FLUSH, all output is flushed as with
  209. Z_SYNC_FLUSH, and the compression state is reset so that decompression can
  210. restart from this point if previous compressed data has been damaged or if
  211. random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
  212. the compression.
  213. If deflate returns with avail_out == 0, this function must be called again
  214. with the same value of the flush parameter and more output space (updated
  215. avail_out), until the flush is complete (deflate returns with non-zero
  216. avail_out).
  217. If the parameter flush is set to Z_FINISH, pending input is processed,
  218. pending output is flushed and deflate returns with Z_STREAM_END if there
  219. was enough output space; if deflate returns with Z_OK, this function must be
  220. called again with Z_FINISH and more output space (updated avail_out) but no
  221. more input data, until it returns with Z_STREAM_END or an error. After
  222. deflate has returned Z_STREAM_END, the only possible operations on the
  223. stream are deflateReset or deflateEnd.
  224. Z_FINISH can be used immediately after deflateInit if all the compression
  225. is to be done in a single step. In this case, avail_out must be at least
  226. 0.1% larger than avail_in plus 12 bytes. If deflate does not return
  227. Z_STREAM_END, then it must be called again as described above.
  228. deflate() sets strm->adler to the adler32 checksum of all input read
  229. so far (that is, total_in bytes).
  230. deflate() may update data_type if it can make a good guess about
  231. the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
  232. binary. This field is only for information purposes and does not affect
  233. the compression algorithm in any manner.
  234. deflate() returns Z_OK if some progress has been made (more input
  235. processed or more output produced), Z_STREAM_END if all input has been
  236. consumed and all output has been produced (only when flush is set to
  237. Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
  238. if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
  239. (for example avail_in or avail_out was zero).
  240. */
  241. extern int zlib_deflateEnd (z_streamp strm);
  242. /*
  243. All dynamically allocated data structures for this stream are freed.
  244. This function discards any unprocessed input and does not flush any
  245. pending output.
  246. deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
  247. stream state was inconsistent, Z_DATA_ERROR if the stream was freed
  248. prematurely (some input or output was discarded). In the error case,
  249. msg may be set but then points to a static string (which must not be
  250. deallocated).
  251. */
  252. extern int zlib_inflate_workspacesize (void);
  253. /*
  254. Returns the number of bytes that needs to be allocated for a per-
  255. stream workspace. A pointer to this number of bytes should be
  256. returned in stream->workspace before calling zlib_inflateInit().
  257. */
  258. /*
  259. extern int zlib_inflateInit (z_streamp strm);
  260. Initializes the internal stream state for decompression. The fields
  261. next_in, avail_in, and workspace must be initialized before by
  262. the caller. If next_in is not NULL and avail_in is large enough (the exact
  263. value depends on the compression method), inflateInit determines the
  264. compression method from the zlib header and allocates all data structures
  265. accordingly; otherwise the allocation will be deferred to the first call of
  266. inflate. If zalloc and zfree are set to NULL, inflateInit updates them to
  267. use default allocation functions.
  268. inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  269. memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  270. version assumed by the caller. msg is set to null if there is no error
  271. message. inflateInit does not perform any decompression apart from reading
  272. the zlib header if present: this will be done by inflate(). (So next_in and
  273. avail_in may be modified, but next_out and avail_out are unchanged.)
  274. */
  275. extern int zlib_inflate (z_streamp strm, int flush);
  276. /*
  277. inflate decompresses as much data as possible, and stops when the input
  278. buffer becomes empty or the output buffer becomes full. It may introduce
  279. some output latency (reading input without producing any output) except when
  280. forced to flush.
  281. The detailed semantics are as follows. inflate performs one or both of the
  282. following actions:
  283. - Decompress more input starting at next_in and update next_in and avail_in
  284. accordingly. If not all input can be processed (because there is not
  285. enough room in the output buffer), next_in is updated and processing
  286. will resume at this point for the next call of inflate().
  287. - Provide more output starting at next_out and update next_out and avail_out
  288. accordingly. inflate() provides as much output as possible, until there
  289. is no more input data or no more space in the output buffer (see below
  290. about the flush parameter).
  291. Before the call of inflate(), the application should ensure that at least
  292. one of the actions is possible, by providing more input and/or consuming
  293. more output, and updating the next_* and avail_* values accordingly.
  294. The application can consume the uncompressed output when it wants, for
  295. example when the output buffer is full (avail_out == 0), or after each
  296. call of inflate(). If inflate returns Z_OK and with zero avail_out, it
  297. must be called again after making room in the output buffer because there
  298. might be more output pending.
  299. The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
  300. Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
  301. output as possible to the output buffer. Z_BLOCK requests that inflate() stop
  302. if and when it gets to the next deflate block boundary. When decoding the
  303. zlib or gzip format, this will cause inflate() to return immediately after
  304. the header and before the first block. When doing a raw inflate, inflate()
  305. will go ahead and process the first block, and will return when it gets to
  306. the end of that block, or when it runs out of data.
  307. The Z_BLOCK option assists in appending to or combining deflate streams.
  308. Also to assist in this, on return inflate() will set strm->data_type to the
  309. number of unused bits in the last byte taken from strm->next_in, plus 64
  310. if inflate() is currently decoding the last block in the deflate stream,
  311. plus 128 if inflate() returned immediately after decoding an end-of-block
  312. code or decoding the complete header up to just before the first byte of the
  313. deflate stream. The end-of-block will not be indicated until all of the
  314. uncompressed data from that block has been written to strm->next_out. The
  315. number of unused bits may in general be greater than seven, except when
  316. bit 7 of data_type is set, in which case the number of unused bits will be
  317. less than eight.
  318. inflate() should normally be called until it returns Z_STREAM_END or an
  319. error. However if all decompression is to be performed in a single step
  320. (a single call of inflate), the parameter flush should be set to
  321. Z_FINISH. In this case all pending input is processed and all pending
  322. output is flushed; avail_out must be large enough to hold all the
  323. uncompressed data. (The size of the uncompressed data may have been saved
  324. by the compressor for this purpose.) The next operation on this stream must
  325. be inflateEnd to deallocate the decompression state. The use of Z_FINISH
  326. is never required, but can be used to inform inflate that a faster approach
  327. may be used for the single inflate() call.
  328. In this implementation, inflate() always flushes as much output as
  329. possible to the output buffer, and always uses the faster approach on the
  330. first call. So the only effect of the flush parameter in this implementation
  331. is on the return value of inflate(), as noted below, or when it returns early
  332. because Z_BLOCK is used.
  333. If a preset dictionary is needed after this call (see inflateSetDictionary
  334. below), inflate sets strm->adler to the adler32 checksum of the dictionary
  335. chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
  336. strm->adler to the adler32 checksum of all output produced so far (that is,
  337. total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
  338. below. At the end of the stream, inflate() checks that its computed adler32
  339. checksum is equal to that saved by the compressor and returns Z_STREAM_END
  340. only if the checksum is correct.
  341. inflate() will decompress and check either zlib-wrapped or gzip-wrapped
  342. deflate data. The header type is detected automatically. Any information
  343. contained in the gzip header is not retained, so applications that need that
  344. information should instead use raw inflate, see inflateInit2() below, or
  345. inflateBack() and perform their own processing of the gzip header and
  346. trailer.
  347. inflate() returns Z_OK if some progress has been made (more input processed
  348. or more output produced), Z_STREAM_END if the end of the compressed data has
  349. been reached and all uncompressed output has been produced, Z_NEED_DICT if a
  350. preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
  351. corrupted (input stream not conforming to the zlib format or incorrect check
  352. value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
  353. if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
  354. Z_BUF_ERROR if no progress is possible or if there was not enough room in the
  355. output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
  356. inflate() can be called again with more input and more output space to
  357. continue decompressing. If Z_DATA_ERROR is returned, the application may then
  358. call inflateSync() to look for a good compression block if a partial recovery
  359. of the data is desired.
  360. */
  361. extern int zlib_inflateEnd (z_streamp strm);
  362. /*
  363. All dynamically allocated data structures for this stream are freed.
  364. This function discards any unprocessed input and does not flush any
  365. pending output.
  366. inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
  367. was inconsistent. In the error case, msg may be set but then points to a
  368. static string (which must not be deallocated).
  369. */
  370. /* Advanced functions */
  371. /*
  372. The following functions are needed only in some special applications.
  373. */
  374. /*
  375. extern int deflateInit2 (z_streamp strm,
  376. int level,
  377. int method,
  378. int windowBits,
  379. int memLevel,
  380. int strategy);
  381. This is another version of deflateInit with more compression options. The
  382. fields next_in, zalloc, zfree and opaque must be initialized before by
  383. the caller.
  384. The method parameter is the compression method. It must be Z_DEFLATED in
  385. this version of the library.
  386. The windowBits parameter is the base two logarithm of the window size
  387. (the size of the history buffer). It should be in the range 8..15 for this
  388. version of the library. Larger values of this parameter result in better
  389. compression at the expense of memory usage. The default value is 15 if
  390. deflateInit is used instead.
  391. The memLevel parameter specifies how much memory should be allocated
  392. for the internal compression state. memLevel=1 uses minimum memory but
  393. is slow and reduces compression ratio; memLevel=9 uses maximum memory
  394. for optimal speed. The default value is 8. See zconf.h for total memory
  395. usage as a function of windowBits and memLevel.
  396. The strategy parameter is used to tune the compression algorithm. Use the
  397. value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
  398. filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
  399. string match). Filtered data consists mostly of small values with a
  400. somewhat random distribution. In this case, the compression algorithm is
  401. tuned to compress them better. The effect of Z_FILTERED is to force more
  402. Huffman coding and less string matching; it is somewhat intermediate
  403. between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
  404. the compression ratio but not the correctness of the compressed output even
  405. if it is not set appropriately.
  406. deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  407. memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
  408. method). msg is set to null if there is no error message. deflateInit2 does
  409. not perform any compression: this will be done by deflate().
  410. */
  411. extern int zlib_deflateReset (z_streamp strm);
  412. /*
  413. This function is equivalent to deflateEnd followed by deflateInit,
  414. but does not free and reallocate all the internal compression state.
  415. The stream will keep the same compression level and any other attributes
  416. that may have been set by deflateInit2.
  417. deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  418. stream state was inconsistent (such as zalloc or state being NULL).
  419. */
  420. static inline unsigned long deflateBound(unsigned long s)
  421. {
  422. return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11;
  423. }
  424. /*
  425. extern int inflateInit2 (z_streamp strm, int windowBits);
  426. This is another version of inflateInit with an extra parameter. The
  427. fields next_in, avail_in, zalloc, zfree and opaque must be initialized
  428. before by the caller.
  429. The windowBits parameter is the base two logarithm of the maximum window
  430. size (the size of the history buffer). It should be in the range 8..15 for
  431. this version of the library. The default value is 15 if inflateInit is used
  432. instead. windowBits must be greater than or equal to the windowBits value
  433. provided to deflateInit2() while compressing, or it must be equal to 15 if
  434. deflateInit2() was not used. If a compressed stream with a larger window
  435. size is given as input, inflate() will return with the error code
  436. Z_DATA_ERROR instead of trying to allocate a larger window.
  437. windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
  438. determines the window size. inflate() will then process raw deflate data,
  439. not looking for a zlib or gzip header, not generating a check value, and not
  440. looking for any check values for comparison at the end of the stream. This
  441. is for use with other formats that use the deflate compressed data format
  442. such as zip. Those formats provide their own check values. If a custom
  443. format is developed using the raw deflate format for compressed data, it is
  444. recommended that a check value such as an adler32 or a crc32 be applied to
  445. the uncompressed data as is done in the zlib, gzip, and zip formats. For
  446. most applications, the zlib format should be used as is. Note that comments
  447. above on the use in deflateInit2() applies to the magnitude of windowBits.
  448. windowBits can also be greater than 15 for optional gzip decoding. Add
  449. 32 to windowBits to enable zlib and gzip decoding with automatic header
  450. detection, or add 16 to decode only the gzip format (the zlib format will
  451. return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
  452. a crc32 instead of an adler32.
  453. inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  454. memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
  455. is set to null if there is no error message. inflateInit2 does not perform
  456. any decompression apart from reading the zlib header if present: this will
  457. be done by inflate(). (So next_in and avail_in may be modified, but next_out
  458. and avail_out are unchanged.)
  459. */
  460. extern int zlib_inflateReset (z_streamp strm);
  461. /*
  462. This function is equivalent to inflateEnd followed by inflateInit,
  463. but does not free and reallocate all the internal decompression state.
  464. The stream will keep attributes that may have been set by inflateInit2.
  465. inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  466. stream state was inconsistent (such as zalloc or state being NULL).
  467. */
  468. extern int zlib_inflateIncomp (z_stream *strm);
  469. /*
  470. This function adds the data at next_in (avail_in bytes) to the output
  471. history without performing any output. There must be no pending output,
  472. and the decompressor must be expecting to see the start of a block.
  473. Calling this function is equivalent to decompressing a stored block
  474. containing the data at next_in (except that the data is not output).
  475. */
  476. #define zlib_deflateInit(strm, level) \
  477. zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \
  478. DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
  479. #define zlib_inflateInit(strm) \
  480. zlib_inflateInit2((strm), DEF_WBITS)
  481. extern int zlib_deflateInit2(z_streamp strm, int level, int method,
  482. int windowBits, int memLevel,
  483. int strategy);
  484. extern int zlib_inflateInit2(z_streamp strm, int windowBits);
  485. #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
  486. struct internal_state {int dummy;}; /* hack for buggy compilers */
  487. #endif
  488. /* Utility function: initialize zlib, unpack binary blob, clean up zlib,
  489. * return len or negative error code. */
  490. extern int zlib_inflate_blob(void *dst, unsigned dst_sz, const void *src, unsigned src_sz);
  491. #endif /* _ZLIB_H */