/src/zlib/zlib.h

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  1. /* zlib.h -- interface of the 'zlib' general purpose compression library
  2. version 1.2.8, April 28th, 2013
  3. Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
  4. This software is provided 'as-is', without any express or implied
  5. warranty. In no event will the authors be held liable for any damages
  6. arising from the use of this software.
  7. Permission is granted to anyone to use this software for any purpose,
  8. including commercial applications, and to alter it and redistribute it
  9. freely, subject to the following restrictions:
  10. 1. The origin of this software must not be misrepresented; you must not
  11. claim that you wrote the original software. If you use this software
  12. in a product, an acknowledgment in the product documentation would be
  13. appreciated but is not required.
  14. 2. Altered source versions must be plainly marked as such, and must not be
  15. misrepresented as being the original software.
  16. 3. This notice may not be removed or altered from any source distribution.
  17. Jean-loup Gailly Mark Adler
  18. jloup@gzip.org madler@alumni.caltech.edu
  19. The data format used by the zlib library is described by RFCs (Request for
  20. Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
  21. (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
  22. */
  23. #ifndef ZLIB_H
  24. #define ZLIB_H
  25. #include "zconf.h"
  26. #ifdef __cplusplus
  27. extern "C" {
  28. #endif
  29. #define ZLIB_VERSION "1.2.8"
  30. #define ZLIB_VERNUM 0x1280
  31. #define ZLIB_VER_MAJOR 1
  32. #define ZLIB_VER_MINOR 2
  33. #define ZLIB_VER_REVISION 8
  34. #define ZLIB_VER_SUBREVISION 0
  35. /*
  36. The 'zlib' compression library provides in-memory compression and
  37. decompression functions, including integrity checks of the uncompressed data.
  38. This version of the library supports only one compression method (deflation)
  39. but other algorithms will be added later and will have the same stream
  40. interface.
  41. Compression can be done in a single step if the buffers are large enough,
  42. or can be done by repeated calls of the compression function. In the latter
  43. case, the application must provide more input and/or consume the output
  44. (providing more output space) before each call.
  45. The compressed data format used by default by the in-memory functions is
  46. the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
  47. around a deflate stream, which is itself documented in RFC 1951.
  48. The library also supports reading and writing files in gzip (.gz) format
  49. with an interface similar to that of stdio using the functions that start
  50. with "gz". The gzip format is different from the zlib format. gzip is a
  51. gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
  52. This library can optionally read and write gzip streams in memory as well.
  53. The zlib format was designed to be compact and fast for use in memory
  54. and on communications channels. The gzip format was designed for single-
  55. file compression on file systems, has a larger header than zlib to maintain
  56. directory information, and uses a different, slower check method than zlib.
  57. The library does not install any signal handler. The decoder checks
  58. the consistency of the compressed data, so the library should never crash
  59. even in case of corrupted input.
  60. */
  61. typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
  62. typedef void (*free_func) OF((voidpf opaque, voidpf address));
  63. struct internal_state;
  64. typedef struct z_stream_s {
  65. z_const Bytef *next_in; /* next input byte */
  66. uInt avail_in; /* number of bytes available at next_in */
  67. uLong total_in; /* total number of input bytes read so far */
  68. Bytef *next_out; /* next output byte should be put there */
  69. uInt avail_out; /* remaining free space at next_out */
  70. uLong total_out; /* total number of bytes output so far */
  71. z_const char *msg; /* last error message, NULL if no error */
  72. struct internal_state FAR *state; /* not visible by applications */
  73. alloc_func zalloc; /* used to allocate the internal state */
  74. free_func zfree; /* used to free the internal state */
  75. voidpf opaque; /* private data object passed to zalloc and zfree */
  76. int data_type; /* best guess about the data type: binary or text */
  77. uLong adler; /* adler32 value of the uncompressed data */
  78. uLong reserved; /* reserved for future use */
  79. } z_stream;
  80. typedef z_stream FAR *z_streamp;
  81. /*
  82. gzip header information passed to and from zlib routines. See RFC 1952
  83. for more details on the meanings of these fields.
  84. */
  85. typedef struct gz_header_s {
  86. int text; /* true if compressed data believed to be text */
  87. uLong time; /* modification time */
  88. int xflags; /* extra flags (not used when writing a gzip file) */
  89. int os; /* operating system */
  90. Bytef *extra; /* pointer to extra field or Z_NULL if none */
  91. uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
  92. uInt extra_max; /* space at extra (only when reading header) */
  93. Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
  94. uInt name_max; /* space at name (only when reading header) */
  95. Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
  96. uInt comm_max; /* space at comment (only when reading header) */
  97. int hcrc; /* true if there was or will be a header crc */
  98. int done; /* true when done reading gzip header (not used
  99. when writing a gzip file) */
  100. } gz_header;
  101. typedef gz_header FAR *gz_headerp;
  102. /*
  103. The application must update next_in and avail_in when avail_in has dropped
  104. to zero. It must update next_out and avail_out when avail_out has dropped
  105. to zero. The application must initialize zalloc, zfree and opaque before
  106. calling the init function. All other fields are set by the compression
  107. library and must not be updated by the application.
  108. The opaque value provided by the application will be passed as the first
  109. parameter for calls of zalloc and zfree. This can be useful for custom
  110. memory management. The compression library attaches no meaning to the
  111. opaque value.
  112. zalloc must return Z_NULL if there is not enough memory for the object.
  113. If zlib is used in a multi-threaded application, zalloc and zfree must be
  114. thread safe.
  115. On 16-bit systems, the functions zalloc and zfree must be able to allocate
  116. exactly 65536 bytes, but will not be required to allocate more than this if
  117. the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
  118. returned by zalloc for objects of exactly 65536 bytes *must* have their
  119. offset normalized to zero. The default allocation function provided by this
  120. library ensures this (see zutil.c). To reduce memory requirements and avoid
  121. any allocation of 64K objects, at the expense of compression ratio, compile
  122. the library with -DMAX_WBITS=14 (see zconf.h).
  123. The fields total_in and total_out can be used for statistics or progress
  124. reports. After compression, total_in holds the total size of the
  125. uncompressed data and may be saved for use in the decompressor (particularly
  126. if the decompressor wants to decompress everything in a single step).
  127. */
  128. /* constants */
  129. #define Z_NO_FLUSH 0
  130. #define Z_PARTIAL_FLUSH 1
  131. #define Z_SYNC_FLUSH 2
  132. #define Z_FULL_FLUSH 3
  133. #define Z_FINISH 4
  134. #define Z_BLOCK 5
  135. #define Z_TREES 6
  136. /* Allowed flush values; see deflate() and inflate() below for details */
  137. #define Z_OK 0
  138. #define Z_STREAM_END 1
  139. #define Z_NEED_DICT 2
  140. #define Z_ERRNO (-1)
  141. #define Z_STREAM_ERROR (-2)
  142. #define Z_DATA_ERROR (-3)
  143. #define Z_MEM_ERROR (-4)
  144. #define Z_BUF_ERROR (-5)
  145. #define Z_VERSION_ERROR (-6)
  146. /* Return codes for the compression/decompression functions. Negative values
  147. * are errors, positive values are used for special but normal events.
  148. */
  149. #define Z_NO_COMPRESSION 0
  150. #define Z_BEST_SPEED 1
  151. #define Z_BEST_COMPRESSION 9
  152. #define Z_DEFAULT_COMPRESSION (-1)
  153. /* compression levels */
  154. #define Z_FILTERED 1
  155. #define Z_HUFFMAN_ONLY 2
  156. #define Z_RLE 3
  157. #define Z_FIXED 4
  158. #define Z_DEFAULT_STRATEGY 0
  159. /* compression strategy; see deflateInit2() below for details */
  160. #define Z_BINARY 0
  161. #define Z_TEXT 1
  162. #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
  163. #define Z_UNKNOWN 2
  164. /* Possible values of the data_type field (though see inflate()) */
  165. #define Z_DEFLATED 8
  166. /* The deflate compression method (the only one supported in this version) */
  167. #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
  168. #define zlib_version zlibVersion()
  169. /* for compatibility with versions < 1.0.2 */
  170. /* basic functions */
  171. ZEXTERN const char * ZEXPORT zlibVersion OF((void));
  172. /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
  173. If the first character differs, the library code actually used is not
  174. compatible with the zlib.h header file used by the application. This check
  175. is automatically made by deflateInit and inflateInit.
  176. */
  177. /*
  178. ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
  179. Initializes the internal stream state for compression. The fields
  180. zalloc, zfree and opaque must be initialized before by the caller. If
  181. zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
  182. allocation functions.
  183. The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
  184. 1 gives best speed, 9 gives best compression, 0 gives no compression at all
  185. (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
  186. requests a default compromise between speed and compression (currently
  187. equivalent to level 6).
  188. deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  189. memory, Z_STREAM_ERROR if level is not a valid compression level, or
  190. Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
  191. with the version assumed by the caller (ZLIB_VERSION). msg is set to null
  192. if there is no error message. deflateInit does not perform any compression:
  193. this will be done by deflate().
  194. */
  195. ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
  196. /*
  197. deflate compresses as much data as possible, and stops when the input
  198. buffer becomes empty or the output buffer becomes full. It may introduce
  199. some output latency (reading input without producing any output) except when
  200. forced to flush.
  201. The detailed semantics are as follows. deflate performs one or both of the
  202. following actions:
  203. - Compress more input starting at next_in and update next_in and avail_in
  204. accordingly. If not all input can be processed (because there is not
  205. enough room in the output buffer), next_in and avail_in are updated and
  206. processing will resume at this point for the next call of deflate().
  207. - Provide more output starting at next_out and update next_out and avail_out
  208. accordingly. This action is forced if the parameter flush is non zero.
  209. Forcing flush frequently degrades the compression ratio, so this parameter
  210. should be set only when necessary (in interactive applications). Some
  211. output may be provided even if flush is not set.
  212. Before the call of deflate(), the application should ensure that at least
  213. one of the actions is possible, by providing more input and/or consuming more
  214. output, and updating avail_in or avail_out accordingly; avail_out should
  215. never be zero before the call. The application can consume the compressed
  216. output when it wants, for example when the output buffer is full (avail_out
  217. == 0), or after each call of deflate(). If deflate returns Z_OK and with
  218. zero avail_out, it must be called again after making room in the output
  219. buffer because there might be more output pending.
  220. Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
  221. decide how much data to accumulate before producing output, in order to
  222. maximize compression.
  223. If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
  224. flushed to the output buffer and the output is aligned on a byte boundary, so
  225. that the decompressor can get all input data available so far. (In
  226. particular avail_in is zero after the call if enough output space has been
  227. provided before the call.) Flushing may degrade compression for some
  228. compression algorithms and so it should be used only when necessary. This
  229. completes the current deflate block and follows it with an empty stored block
  230. that is three bits plus filler bits to the next byte, followed by four bytes
  231. (00 00 ff ff).
  232. If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
  233. output buffer, but the output is not aligned to a byte boundary. All of the
  234. input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
  235. This completes the current deflate block and follows it with an empty fixed
  236. codes block that is 10 bits long. This assures that enough bytes are output
  237. in order for the decompressor to finish the block before the empty fixed code
  238. block.
  239. If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
  240. for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
  241. seven bits of the current block are held to be written as the next byte after
  242. the next deflate block is completed. In this case, the decompressor may not
  243. be provided enough bits at this point in order to complete decompression of
  244. the data provided so far to the compressor. It may need to wait for the next
  245. block to be emitted. This is for advanced applications that need to control
  246. the emission of deflate blocks.
  247. If flush is set to Z_FULL_FLUSH, all output is flushed as with
  248. Z_SYNC_FLUSH, and the compression state is reset so that decompression can
  249. restart from this point if previous compressed data has been damaged or if
  250. random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
  251. compression.
  252. If deflate returns with avail_out == 0, this function must be called again
  253. with the same value of the flush parameter and more output space (updated
  254. avail_out), until the flush is complete (deflate returns with non-zero
  255. avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
  256. avail_out is greater than six to avoid repeated flush markers due to
  257. avail_out == 0 on return.
  258. If the parameter flush is set to Z_FINISH, pending input is processed,
  259. pending output is flushed and deflate returns with Z_STREAM_END if there was
  260. enough output space; if deflate returns with Z_OK, this function must be
  261. called again with Z_FINISH and more output space (updated avail_out) but no
  262. more input data, until it returns with Z_STREAM_END or an error. After
  263. deflate has returned Z_STREAM_END, the only possible operations on the stream
  264. are deflateReset or deflateEnd.
  265. Z_FINISH can be used immediately after deflateInit if all the compression
  266. is to be done in a single step. In this case, avail_out must be at least the
  267. value returned by deflateBound (see below). Then deflate is guaranteed to
  268. return Z_STREAM_END. If not enough output space is provided, deflate will
  269. not return Z_STREAM_END, and it must be called again as described above.
  270. deflate() sets strm->adler to the adler32 checksum of all input read
  271. so far (that is, total_in bytes).
  272. deflate() may update strm->data_type if it can make a good guess about
  273. the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
  274. binary. This field is only for information purposes and does not affect the
  275. compression algorithm in any manner.
  276. deflate() returns Z_OK if some progress has been made (more input
  277. processed or more output produced), Z_STREAM_END if all input has been
  278. consumed and all output has been produced (only when flush is set to
  279. Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
  280. if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
  281. (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
  282. fatal, and deflate() can be called again with more input and more output
  283. space to continue compressing.
  284. */
  285. ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
  286. /*
  287. All dynamically allocated data structures for this stream are freed.
  288. This function discards any unprocessed input and does not flush any pending
  289. output.
  290. deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
  291. stream state was inconsistent, Z_DATA_ERROR if the stream was freed
  292. prematurely (some input or output was discarded). In the error case, msg
  293. may be set but then points to a static string (which must not be
  294. deallocated).
  295. */
  296. /*
  297. ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
  298. Initializes the internal stream state for decompression. The fields
  299. next_in, avail_in, zalloc, zfree and opaque must be initialized before by
  300. the caller. If next_in is not Z_NULL and avail_in is large enough (the
  301. exact value depends on the compression method), inflateInit determines the
  302. compression method from the zlib header and allocates all data structures
  303. accordingly; otherwise the allocation will be deferred to the first call of
  304. inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
  305. use default allocation functions.
  306. inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  307. memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  308. version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  309. invalid, such as a null pointer to the structure. msg is set to null if
  310. there is no error message. inflateInit does not perform any decompression
  311. apart from possibly reading the zlib header if present: actual decompression
  312. will be done by inflate(). (So next_in and avail_in may be modified, but
  313. next_out and avail_out are unused and unchanged.) The current implementation
  314. of inflateInit() does not process any header information -- that is deferred
  315. until inflate() is called.
  316. */
  317. ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
  318. /*
  319. inflate decompresses as much data as possible, and stops when the input
  320. buffer becomes empty or the output buffer becomes full. It may introduce
  321. some output latency (reading input without producing any output) except when
  322. forced to flush.
  323. The detailed semantics are as follows. inflate performs one or both of the
  324. following actions:
  325. - Decompress more input starting at next_in and update next_in and avail_in
  326. accordingly. If not all input can be processed (because there is not
  327. enough room in the output buffer), next_in is updated and processing will
  328. resume at this point for the next call of inflate().
  329. - Provide more output starting at next_out and update next_out and avail_out
  330. accordingly. inflate() provides as much output as possible, until there is
  331. no more input data or no more space in the output buffer (see below about
  332. the flush parameter).
  333. Before the call of inflate(), the application should ensure that at least
  334. one of the actions is possible, by providing more input and/or consuming more
  335. output, and updating the next_* and avail_* values accordingly. The
  336. application can consume the uncompressed output when it wants, for example
  337. when the output buffer is full (avail_out == 0), or after each call of
  338. inflate(). If inflate returns Z_OK and with zero avail_out, it must be
  339. called again after making room in the output buffer because there might be
  340. more output pending.
  341. The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
  342. Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
  343. output as possible to the output buffer. Z_BLOCK requests that inflate()
  344. stop if and when it gets to the next deflate block boundary. When decoding
  345. the zlib or gzip format, this will cause inflate() to return immediately
  346. after the header and before the first block. When doing a raw inflate,
  347. inflate() will go ahead and process the first block, and will return when it
  348. gets to the end of that block, or when it runs out of data.
  349. The Z_BLOCK option assists in appending to or combining deflate streams.
  350. Also to assist in this, on return inflate() will set strm->data_type to the
  351. number of unused bits in the last byte taken from strm->next_in, plus 64 if
  352. inflate() is currently decoding the last block in the deflate stream, plus
  353. 128 if inflate() returned immediately after decoding an end-of-block code or
  354. decoding the complete header up to just before the first byte of the deflate
  355. stream. The end-of-block will not be indicated until all of the uncompressed
  356. data from that block has been written to strm->next_out. The number of
  357. unused bits may in general be greater than seven, except when bit 7 of
  358. data_type is set, in which case the number of unused bits will be less than
  359. eight. data_type is set as noted here every time inflate() returns for all
  360. flush options, and so can be used to determine the amount of currently
  361. consumed input in bits.
  362. The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
  363. end of each deflate block header is reached, before any actual data in that
  364. block is decoded. This allows the caller to determine the length of the
  365. deflate block header for later use in random access within a deflate block.
  366. 256 is added to the value of strm->data_type when inflate() returns
  367. immediately after reaching the end of the deflate block header.
  368. inflate() should normally be called until it returns Z_STREAM_END or an
  369. error. However if all decompression is to be performed in a single step (a
  370. single call of inflate), the parameter flush should be set to Z_FINISH. In
  371. this case all pending input is processed and all pending output is flushed;
  372. avail_out must be large enough to hold all of the uncompressed data for the
  373. operation to complete. (The size of the uncompressed data may have been
  374. saved by the compressor for this purpose.) The use of Z_FINISH is not
  375. required to perform an inflation in one step. However it may be used to
  376. inform inflate that a faster approach can be used for the single inflate()
  377. call. Z_FINISH also informs inflate to not maintain a sliding window if the
  378. stream completes, which reduces inflate's memory footprint. If the stream
  379. does not complete, either because not all of the stream is provided or not
  380. enough output space is provided, then a sliding window will be allocated and
  381. inflate() can be called again to continue the operation as if Z_NO_FLUSH had
  382. been used.
  383. In this implementation, inflate() always flushes as much output as
  384. possible to the output buffer, and always uses the faster approach on the
  385. first call. So the effects of the flush parameter in this implementation are
  386. on the return value of inflate() as noted below, when inflate() returns early
  387. when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
  388. memory for a sliding window when Z_FINISH is used.
  389. If a preset dictionary is needed after this call (see inflateSetDictionary
  390. below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
  391. chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
  392. strm->adler to the Adler-32 checksum of all output produced so far (that is,
  393. total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
  394. below. At the end of the stream, inflate() checks that its computed adler32
  395. checksum is equal to that saved by the compressor and returns Z_STREAM_END
  396. only if the checksum is correct.
  397. inflate() can decompress and check either zlib-wrapped or gzip-wrapped
  398. deflate data. The header type is detected automatically, if requested when
  399. initializing with inflateInit2(). Any information contained in the gzip
  400. header is not retained, so applications that need that information should
  401. instead use raw inflate, see inflateInit2() below, or inflateBack() and
  402. perform their own processing of the gzip header and trailer. When processing
  403. gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
  404. producted so far. The CRC-32 is checked against the gzip trailer.
  405. inflate() returns Z_OK if some progress has been made (more input processed
  406. or more output produced), Z_STREAM_END if the end of the compressed data has
  407. been reached and all uncompressed output has been produced, Z_NEED_DICT if a
  408. preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
  409. corrupted (input stream not conforming to the zlib format or incorrect check
  410. value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
  411. next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
  412. Z_BUF_ERROR if no progress is possible or if there was not enough room in the
  413. output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
  414. inflate() can be called again with more input and more output space to
  415. continue decompressing. If Z_DATA_ERROR is returned, the application may
  416. then call inflateSync() to look for a good compression block if a partial
  417. recovery of the data is desired.
  418. */
  419. ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
  420. /*
  421. All dynamically allocated data structures for this stream are freed.
  422. This function discards any unprocessed input and does not flush any pending
  423. output.
  424. inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
  425. was inconsistent. In the error case, msg may be set but then points to a
  426. static string (which must not be deallocated).
  427. */
  428. /* Advanced functions */
  429. /*
  430. The following functions are needed only in some special applications.
  431. */
  432. /*
  433. ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
  434. int level,
  435. int method,
  436. int windowBits,
  437. int memLevel,
  438. int strategy));
  439. This is another version of deflateInit with more compression options. The
  440. fields next_in, zalloc, zfree and opaque must be initialized before by the
  441. caller.
  442. The method parameter is the compression method. It must be Z_DEFLATED in
  443. this version of the library.
  444. The windowBits parameter is the base two logarithm of the window size
  445. (the size of the history buffer). It should be in the range 8..15 for this
  446. version of the library. Larger values of this parameter result in better
  447. compression at the expense of memory usage. The default value is 15 if
  448. deflateInit is used instead.
  449. windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
  450. determines the window size. deflate() will then generate raw deflate data
  451. with no zlib header or trailer, and will not compute an adler32 check value.
  452. windowBits can also be greater than 15 for optional gzip encoding. Add
  453. 16 to windowBits to write a simple gzip header and trailer around the
  454. compressed data instead of a zlib wrapper. The gzip header will have no
  455. file name, no extra data, no comment, no modification time (set to zero), no
  456. header crc, and the operating system will be set to 255 (unknown). If a
  457. gzip stream is being written, strm->adler is a crc32 instead of an adler32.
  458. The memLevel parameter specifies how much memory should be allocated
  459. for the internal compression state. memLevel=1 uses minimum memory but is
  460. slow and reduces compression ratio; memLevel=9 uses maximum memory for
  461. optimal speed. The default value is 8. See zconf.h for total memory usage
  462. as a function of windowBits and memLevel.
  463. The strategy parameter is used to tune the compression algorithm. Use the
  464. value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
  465. filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
  466. string match), or Z_RLE to limit match distances to one (run-length
  467. encoding). Filtered data consists mostly of small values with a somewhat
  468. random distribution. In this case, the compression algorithm is tuned to
  469. compress them better. The effect of Z_FILTERED is to force more Huffman
  470. coding and less string matching; it is somewhat intermediate between
  471. Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
  472. fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
  473. strategy parameter only affects the compression ratio but not the
  474. correctness of the compressed output even if it is not set appropriately.
  475. Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
  476. decoder for special applications.
  477. deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  478. memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
  479. method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
  480. incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
  481. set to null if there is no error message. deflateInit2 does not perform any
  482. compression: this will be done by deflate().
  483. */
  484. ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
  485. const Bytef *dictionary,
  486. uInt dictLength));
  487. /*
  488. Initializes the compression dictionary from the given byte sequence
  489. without producing any compressed output. When using the zlib format, this
  490. function must be called immediately after deflateInit, deflateInit2 or
  491. deflateReset, and before any call of deflate. When doing raw deflate, this
  492. function must be called either before any call of deflate, or immediately
  493. after the completion of a deflate block, i.e. after all input has been
  494. consumed and all output has been delivered when using any of the flush
  495. options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
  496. compressor and decompressor must use exactly the same dictionary (see
  497. inflateSetDictionary).
  498. The dictionary should consist of strings (byte sequences) that are likely
  499. to be encountered later in the data to be compressed, with the most commonly
  500. used strings preferably put towards the end of the dictionary. Using a
  501. dictionary is most useful when the data to be compressed is short and can be
  502. predicted with good accuracy; the data can then be compressed better than
  503. with the default empty dictionary.
  504. Depending on the size of the compression data structures selected by
  505. deflateInit or deflateInit2, a part of the dictionary may in effect be
  506. discarded, for example if the dictionary is larger than the window size
  507. provided in deflateInit or deflateInit2. Thus the strings most likely to be
  508. useful should be put at the end of the dictionary, not at the front. In
  509. addition, the current implementation of deflate will use at most the window
  510. size minus 262 bytes of the provided dictionary.
  511. Upon return of this function, strm->adler is set to the adler32 value
  512. of the dictionary; the decompressor may later use this value to determine
  513. which dictionary has been used by the compressor. (The adler32 value
  514. applies to the whole dictionary even if only a subset of the dictionary is
  515. actually used by the compressor.) If a raw deflate was requested, then the
  516. adler32 value is not computed and strm->adler is not set.
  517. deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
  518. parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
  519. inconsistent (for example if deflate has already been called for this stream
  520. or if not at a block boundary for raw deflate). deflateSetDictionary does
  521. not perform any compression: this will be done by deflate().
  522. */
  523. ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
  524. z_streamp source));
  525. /*
  526. Sets the destination stream as a complete copy of the source stream.
  527. This function can be useful when several compression strategies will be
  528. tried, for example when there are several ways of pre-processing the input
  529. data with a filter. The streams that will be discarded should then be freed
  530. by calling deflateEnd. Note that deflateCopy duplicates the internal
  531. compression state which can be quite large, so this strategy is slow and can
  532. consume lots of memory.
  533. deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  534. enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  535. (such as zalloc being Z_NULL). msg is left unchanged in both source and
  536. destination.
  537. */
  538. ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
  539. /*
  540. This function is equivalent to deflateEnd followed by deflateInit,
  541. but does not free and reallocate all the internal compression state. The
  542. stream will keep the same compression level and any other attributes that
  543. may have been set by deflateInit2.
  544. deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  545. stream state was inconsistent (such as zalloc or state being Z_NULL).
  546. */
  547. ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
  548. int level,
  549. int strategy));
  550. /*
  551. Dynamically update the compression level and compression strategy. The
  552. interpretation of level and strategy is as in deflateInit2. This can be
  553. used to switch between compression and straight copy of the input data, or
  554. to switch to a different kind of input data requiring a different strategy.
  555. If the compression level is changed, the input available so far is
  556. compressed with the old level (and may be flushed); the new level will take
  557. effect only at the next call of deflate().
  558. Before the call of deflateParams, the stream state must be set as for
  559. a call of deflate(), since the currently available input may have to be
  560. compressed and flushed. In particular, strm->avail_out must be non-zero.
  561. deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
  562. stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
  563. strm->avail_out was zero.
  564. */
  565. ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
  566. int good_length,
  567. int max_lazy,
  568. int nice_length,
  569. int max_chain));
  570. /*
  571. Fine tune deflate's internal compression parameters. This should only be
  572. used by someone who understands the algorithm used by zlib's deflate for
  573. searching for the best matching string, and even then only by the most
  574. fanatic optimizer trying to squeeze out the last compressed bit for their
  575. specific input data. Read the deflate.c source code for the meaning of the
  576. max_lazy, good_length, nice_length, and max_chain parameters.
  577. deflateTune() can be called after deflateInit() or deflateInit2(), and
  578. returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
  579. */
  580. ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
  581. uLong sourceLen));
  582. /*
  583. deflateBound() returns an upper bound on the compressed size after
  584. deflation of sourceLen bytes. It must be called after deflateInit() or
  585. deflateInit2(), and after deflateSetHeader(), if used. This would be used
  586. to allocate an output buffer for deflation in a single pass, and so would be
  587. called before deflate(). If that first deflate() call is provided the
  588. sourceLen input bytes, an output buffer allocated to the size returned by
  589. deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
  590. to return Z_STREAM_END. Note that it is possible for the compressed size to
  591. be larger than the value returned by deflateBound() if flush options other
  592. than Z_FINISH or Z_NO_FLUSH are used.
  593. */
  594. ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
  595. unsigned *pending,
  596. int *bits));
  597. /*
  598. deflatePending() returns the number of bytes and bits of output that have
  599. been generated, but not yet provided in the available output. The bytes not
  600. provided would be due to the available output space having being consumed.
  601. The number of bits of output not provided are between 0 and 7, where they
  602. await more bits to join them in order to fill out a full byte. If pending
  603. or bits are Z_NULL, then those values are not set.
  604. deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
  605. stream state was inconsistent.
  606. */
  607. ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
  608. int bits,
  609. int value));
  610. /*
  611. deflatePrime() inserts bits in the deflate output stream. The intent
  612. is that this function is used to start off the deflate output with the bits
  613. leftover from a previous deflate stream when appending to it. As such, this
  614. function can only be used for raw deflate, and must be used before the first
  615. deflate() call after a deflateInit2() or deflateReset(). bits must be less
  616. than or equal to 16, and that many of the least significant bits of value
  617. will be inserted in the output.
  618. deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
  619. room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
  620. source stream state was inconsistent.
  621. */
  622. ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
  623. gz_headerp head));
  624. /*
  625. deflateSetHeader() provides gzip header information for when a gzip
  626. stream is requested by deflateInit2(). deflateSetHeader() may be called
  627. after deflateInit2() or deflateReset() and before the first call of
  628. deflate(). The text, time, os, extra field, name, and comment information
  629. in the provided gz_header structure are written to the gzip header (xflag is
  630. ignored -- the extra flags are set according to the compression level). The
  631. caller must assure that, if not Z_NULL, name and comment are terminated with
  632. a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
  633. available there. If hcrc is true, a gzip header crc is included. Note that
  634. the current versions of the command-line version of gzip (up through version
  635. 1.3.x) do not support header crc's, and will report that it is a "multi-part
  636. gzip file" and give up.
  637. If deflateSetHeader is not used, the default gzip header has text false,
  638. the time set to zero, and os set to 255, with no extra, name, or comment
  639. fields. The gzip header is returned to the default state by deflateReset().
  640. deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
  641. stream state was inconsistent.
  642. */
  643. /*
  644. ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
  645. int windowBits));
  646. This is another version of inflateInit with an extra parameter. The
  647. fields next_in, avail_in, zalloc, zfree and opaque must be initialized
  648. before by the caller.
  649. The windowBits parameter is the base two logarithm of the maximum window
  650. size (the size of the history buffer). It should be in the range 8..15 for
  651. this version of the library. The default value is 15 if inflateInit is used
  652. instead. windowBits must be greater than or equal to the windowBits value
  653. provided to deflateInit2() while compressing, or it must be equal to 15 if
  654. deflateInit2() was not used. If a compressed stream with a larger window
  655. size is given as input, inflate() will return with the error code
  656. Z_DATA_ERROR instead of trying to allocate a larger window.
  657. windowBits can also be zero to request that inflate use the window size in
  658. the zlib header of the compressed stream.
  659. windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
  660. determines the window size. inflate() will then process raw deflate data,
  661. not looking for a zlib or gzip header, not generating a check value, and not
  662. looking for any check values for comparison at the end of the stream. This
  663. is for use with other formats that use the deflate compressed data format
  664. such as zip. Those formats provide their own check values. If a custom
  665. format is developed using the raw deflate format for compressed data, it is
  666. recommended that a check value such as an adler32 or a crc32 be applied to
  667. the uncompressed data as is done in the zlib, gzip, and zip formats. For
  668. most applications, the zlib format should be used as is. Note that comments
  669. above on the use in deflateInit2() applies to the magnitude of windowBits.
  670. windowBits can also be greater than 15 for optional gzip decoding. Add
  671. 32 to windowBits to enable zlib and gzip decoding with automatic header
  672. detection, or add 16 to decode only the gzip format (the zlib format will
  673. return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
  674. crc32 instead of an adler32.
  675. inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  676. memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  677. version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  678. invalid, such as a null pointer to the structure. msg is set to null if
  679. there is no error message. inflateInit2 does not perform any decompression
  680. apart from possibly reading the zlib header if present: actual decompression
  681. will be done by inflate(). (So next_in and avail_in may be modified, but
  682. next_out and avail_out are unused and unchanged.) The current implementation
  683. of inflateInit2() does not process any header information -- that is
  684. deferred until inflate() is called.
  685. */
  686. ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
  687. const Bytef *dictionary,
  688. uInt dictLength));
  689. /*
  690. Initializes the decompression dictionary from the given uncompressed byte
  691. sequence. This function must be called immediately after a call of inflate,
  692. if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
  693. can be determined from the adler32 value returned by that call of inflate.
  694. The compressor and decompressor must use exactly the same dictionary (see
  695. deflateSetDictionary). For raw inflate, this function can be called at any
  696. time to set the dictionary. If the provided dictionary is smaller than the
  697. window and there is already data in the window, then the provided dictionary
  698. will amend what's there. The application must insure that the dictionary
  699. that was used for compression is provided.
  700. inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
  701. parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
  702. inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
  703. expected one (incorrect adler32 value). inflateSetDictionary does not
  704. perform any decompression: this will be done by subsequent calls of
  705. inflate().
  706. */
  707. ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
  708. Bytef *dictionary,
  709. uInt *dictLength));
  710. /*
  711. Returns the sliding dictionary being maintained by inflate. dictLength is
  712. set to the number of bytes in the dictionary, and that many bytes are copied
  713. to dictionary. dictionary must have enough space, where 32768 bytes is
  714. always enough. If inflateGetDictionary() is called with dictionary equal to
  715. Z_NULL, then only the dictionary length is returned, and nothing is copied.
  716. Similary, if dictLength is Z_NULL, then it is not set.
  717. inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
  718. stream state is inconsistent.
  719. */
  720. ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
  721. /*
  722. Skips invalid compressed data until a possible full flush point (see above
  723. for the description of deflate with Z_FULL_FLUSH) can be found, or until all
  724. available input is skipped. No output is provided.
  725. inflateSync searches for a 00 00 FF FF pattern in the compressed data.
  726. All full flush points have this pattern, but not all occurrences of this
  727. pattern are full flush points.
  728. inflateSync returns Z_OK if a possible full flush point has been found,
  729. Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
  730. has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
  731. In the success case, the application may save the current current value of
  732. total_in which indicates where valid compressed data was found. In the
  733. error case, the application may repeatedly call inflateSync, providing more
  734. input each time, until success or end of the input data.
  735. */
  736. ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
  737. z_streamp source));
  738. /*
  739. Sets the destination stream as a complete copy of the source stream.
  740. This function can be useful when randomly accessing a large stream. The
  741. first pass through the stream can periodically record the inflate state,
  742. allowing restarting inflate at those points when randomly accessing the
  743. stream.
  744. inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  745. enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  746. (such as zalloc being Z_NULL). msg is left unchanged in both source and
  747. destination.
  748. */
  749. ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
  750. /*
  751. This function is equivalent to inflateEnd followed by inflateInit,
  752. but does not free and reallocate all the internal decompression state. The
  753. stream will keep attributes that may have been set by inflateInit2.
  754. inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  755. stream state was inconsistent (such as zalloc or state being Z_NULL).
  756. */
  757. ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
  758. int windowBits));
  759. /*
  760. This function is the same as inflateReset, but it also permits changing
  761. the wrap and window size requests. The windowBits parameter is interpreted
  762. the same as it is for inflateInit2.
  763. inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
  764. stream state was inconsistent (such as zalloc or state being Z_NULL), or if
  765. the windowBits parameter is invalid.
  766. */
  767. ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
  768. int bits,
  769. int value));
  770. /*
  771. This function inserts bits in the inflate input stream. The intent is
  772. that this function is used to start inflating at a bit position in the
  773. middle of a byte. The provided bits will be used before any bytes are used
  774. from next_in. This function should only be used with raw inflate, and
  775. should be used before the first inflate() call after inflateInit2() or
  776. inflateReset(). bits must be less than or equal to 16, and that many of the
  777. least significant bits of value will be inserted in the input.
  778. If bits is negative, then the input stream bit buffer is emptied. Then
  779. inflatePrime() can be called again to put bits in the buffer. This is used
  780. to clear out bits leftover after feeding inflate a block description prior
  781. to feeding inflate codes.
  782. inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
  783. stream state was inconsistent.
  784. */
  785. ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
  786. /*
  787. This function returns two values, one in the lower 16 bits of the return
  788. value, and the other in the remaining upper bits, obtained by shifting the
  789. return value down 16 bits. If the upper value is -1 and the lower value is
  790. zero, then inflate() is currently decoding information outside of a block.
  791. If the upper value is -1 and the lower value is non-zero, then inflate is in
  792. the middle of a stored block, with the lower value equaling the number of
  793. bytes from the input remaining to copy. If the upper value is not -1, then
  794. it is the number of bits back from the current bit position in the input of
  795. the code (literal or length/distance pair) currently being processed. In
  796. that case the lower value is the number of bytes already emitted for that
  797. code.
  798. A code is being processed if inflate is waiting for more input to complete
  799. decoding of the code, or if it has completed decoding but is waiting for
  800. more output space to write the literal or match data.
  801. inflateMark() is used to mark locations in the input data for random
  802. access, which may be at bit positions, and to note those cases where the
  803. output of a code may span boundaries of random access blocks. The current
  804. location in the input stream can be determined from avail_in and data_type
  805. as noted in the description for the Z_BLOCK flush parameter for inflate.
  806. inflateMark returns the value noted above or -1 << 16 if the provided
  807. source stream state was inconsistent.
  808. */
  809. ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
  810. gz_headerp head));
  811. /*
  812. inflateGetHeader() requests that gzip header information be stored in the
  813. provided gz_header structure. inflateGetHeader() may be called after
  814. inflateInit2() or inflateReset(), and before the first call of inflate().
  815. As inflate() processes the gzip stream, head->done is zero until…