src/zlib/zlib.h

   1 /* zlib.h -- interface of the 'zlib' general purpose compression library
   2   version 1.1.2, March 19th, 1998
   3
   4   Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
   5
   6   This software is provided 'as-is', without any express or implied
   7   warranty.  In no event will the authors be held liable for any damages
   8   arising from the use of this software.
   9
  10   Permission is granted to anyone to use this software for any purpose,
  11   including commercial applications, and to alter it and redistribute it
  12   freely, subject to the following restrictions:
  13
  14   1. The origin of this software must not be misrepresented; you must not
  15      claim that you wrote the original software. If you use this software
  16      in a product, an acknowledgment in the product documentation would be
  17      appreciated but is not required.
  18   2. Altered source versions must be plainly marked as such, and must not be
  19      misrepresented as being the original software.
  20   3. This notice may not be removed or altered from any source distribution.
  21
  22   Jean-loup Gailly        Mark Adler
  23   jloup@gzip.org          madler@alumni.caltech.edu
  24
  25
  26   The data format used by the zlib library is described by RFCs (Request for
  27   Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
  28   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
  29 */
  30
  31 #ifndef _ZLIB_H
  32 #define _ZLIB_H
  33
  34 #include "../zlib/zconf.h"
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 #define ZLIB_VERSION "1.1.2"
  41
  42 /*
  43      The 'zlib' compression library provides in-memory compression and
  44   decompression functions, including integrity checks of the uncompressed
  45   data.  This version of the library supports only one compression method
  46   (deflation) but other algorithms will be added later and will have the same
  47   stream interface.
  48
  49      Compression can be done in a single step if the buffers are large
  50   enough (for example if an input file is mmap'ed), or can be done by
  51   repeated calls of the compression function.  In the latter case, the
  52   application must provide more input and/or consume the output
  53   (providing more output space) before each call.
  54
  55      The library also supports reading and writing files in gzip (.gz) format
  56   with an interface similar to that of stdio.
  57
  58      The library does not install any signal handler. The decoder checks
  59   the consistency of the compressed data, so the library should never
  60   crash even in case of corrupted input.
  61 */
  62
  63 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
  64 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
  65
  66 struct internal_state;
  67
  68 typedef struct z_stream_s {
  69     Bytef    *next_in;  /* next input byte */
  70     uInt     avail_in;  /* number of bytes available at next_in */
  71     uLong    total_in;  /* total nb of input bytes read so far */
  72
  73     Bytef    *next_out; /* next output byte should be put there */
  74     uInt     avail_out; /* remaining free space at next_out */
  75     uLong    total_out; /* total nb of bytes output so far */
  76
  77     char     *msg;      /* last error message, NULL if no error */
  78     struct internal_state FAR *state; /* not visible by applications */
  79
  80     alloc_func zalloc;  /* used to allocate the internal state */
  81     free_func  zfree;   /* used to free the internal state */
  82     voidpf     opaque;  /* private data object passed to zalloc and zfree */
  83
  84     int     data_type;  /* best guess about the data type: ascii or binary */
  85     uLong   adler;      /* adler32 value of the uncompressed data */
  86     uLong   reserved;   /* reserved for future use */
  87 } z_stream;
  88
  89 typedef z_stream FAR *z_streamp;
  90
  91 /*
  92    The application must update next_in and avail_in when avail_in has
  93    dropped to zero. It must update next_out and avail_out when avail_out
  94    has dropped to zero. The application must initialize zalloc, zfree and
  95    opaque before calling the init function. All other fields are set by the
  96    compression library and must not be updated by the application.
  97
  98    The opaque value provided by the application will be passed as the first
  99    parameter for calls of zalloc and zfree. This can be useful for custom
 100    memory management. The compression library attaches no meaning to the
 101    opaque value.
 102
 103    zalloc must return Z_NULL if there is not enough memory for the object.
 104    If zlib is used in a multi-threaded application, zalloc and zfree must be
 105    thread safe.
 106
 107    On 16-bit systems, the functions zalloc and zfree must be able to allocate
 108    exactly 65536 bytes, but will not be required to allocate more than this
 109    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
 110    pointers returned by zalloc for objects of exactly 65536 bytes *must*
 111    have their offset normalized to zero. The default allocation function
 112    provided by this library ensures this (see zutil.c). To reduce memory
 113    requirements and avoid any allocation of 64K objects, at the expense of
 114    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
 115
 116    The fields total_in and total_out can be used for statistics or
 117    progress reports. After compression, total_in holds the total size of
 118    the uncompressed data and may be saved for use in the decompressor
 119    (particularly if the decompressor wants to decompress everything in
 120    a single step).
 121 */
 122
 123                         /* constants */
 124
 125 #define Z_NO_FLUSH      0
 126 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
 127 #define Z_SYNC_FLUSH    2
 128 #define Z_FULL_FLUSH    3
 129 #define Z_FINISH        4
 130 /* Allowed flush values; see deflate() below for details */
 131
 132 #define Z_OK            0
 133 #define Z_STREAM_END    1
 134 #define Z_NEED_DICT     2
 135 #define Z_ERRNO        (-1)
 136 #define Z_STREAM_ERROR (-2)
 137 #define Z_DATA_ERROR   (-3)
 138 #define Z_MEM_ERROR    (-4)
 139 #define Z_BUF_ERROR    (-5)
 140 #define Z_VERSION_ERROR (-6)
 141 /* Return codes for the compression/decompression functions. Negative
 142  * values are errors, positive values are used for special but normal events.
 143  */
 144
 145 #define Z_NO_COMPRESSION         0
 146 #define Z_BEST_SPEED             1
 147 #define Z_BEST_COMPRESSION       9
 148 #define Z_DEFAULT_COMPRESSION  (-1)
 149 /* compression levels */
 150
 151 #define Z_FILTERED            1
 152 #define Z_HUFFMAN_ONLY        2
 153 #define Z_DEFAULT_STRATEGY    0
 154 /* compression strategy; see deflateInit2() below for details */
 155
 156 #define Z_BINARY   0
 157 #define Z_ASCII    1
 158 #define Z_UNKNOWN  2
 159 /* Possible values of the data_type field */
 160
 161 #define Z_DEFLATED   8
 162 /* The deflate compression method (the only one supported in this version) */
 163
 164 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
 165
 166 #define zlib_version zlibVersion()
 167 /* for compatibility with versions < 1.0.2 */
 168
 169                         /* basic functions */
 170
 171 extern 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
 174    not compatible with the zlib.h header file used by the application.
 175    This check is automatically made by deflateInit and inflateInit.
 176  */
 177
 178 /*
 179 extern int ZEXPORT deflateInit OF((z_streamp strm, int level));
 180
 181      Initializes the internal stream state for compression. The fields
 182    zalloc, zfree and opaque must be initialized before by the caller.
 183    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
 184    use default allocation functions.
 185
 186      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
 187    1 gives best speed, 9 gives best compression, 0 gives no compression at
 188    all (the input data is simply copied a block at a time).
 189    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
 190    compression (currently equivalent to level 6).
 191
 192      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
 193    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
 194    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
 195    with the version assumed by the caller (ZLIB_VERSION).
 196    msg is set to null if there is no error message.  deflateInit does not
 197    perform any compression: this will be done by deflate().
 198 */
 199
 200
 201 extern int ZEXPORT deflate OF((z_streamp strm, int flush));
 202 /*
 203     deflate compresses as much data as possible, and stops when the input
 204   buffer becomes empty or the output buffer becomes full. It may introduce some
 205   output latency (reading input without producing any output) except when
 206   forced to flush.
 207
 208     The detailed semantics are as follows. deflate performs one or both of the
 209   following actions:
 210
 211   - Compress more input starting at next_in and update next_in and avail_in
 212     accordingly. If not all input can be processed (because there is not
 213     enough room in the output buffer), next_in and avail_in are updated and
 214     processing will resume at this point for the next call of deflate().
 215
 216   - Provide more output starting at next_out and update next_out and avail_out
 217     accordingly. This action is forced if the parameter flush is non zero.
 218     Forcing flush frequently degrades the compression ratio, so this parameter
 219     should be set only when necessary (in interactive applications).
 220     Some output may be provided even if flush is not set.
 221
 222   Before the call of deflate(), the application should ensure that at least
 223   one of the actions is possible, by providing more input and/or consuming
 224   more output, and updating avail_in or avail_out accordingly; avail_out
 225   should never be zero before the call. The application can consume the
 226   compressed output when it wants, for example when the output buffer is full
 227   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
 228   and with zero avail_out, it must be called again after making room in the
 229   output buffer because there might be more output pending.
 230
 231     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
 232   flushed to the output buffer and the output is aligned on a byte boundary, so
 233   that the decompressor can get all input data available so far. (In particular
 234   avail_in is zero after the call if enough output space has been provided
 235   before the call.)  Flushing may degrade compression for some compression
 236   algorithms and so it should be used only when necessary.
 237
 238     If flush is set to Z_FULL_FLUSH, all output is flushed as with
 239   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
 240   restart from this point if previous compressed data has been damaged or if
 241   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
 242   the compression.
 243
 244     If deflate returns with avail_out == 0, this function must be called again
 245   with the same value of the flush parameter and more output space (updated
 246   avail_out), until the flush is complete (deflate returns with non-zero
 247   avail_out).
 248
 249     If the parameter flush is set to Z_FINISH, pending input is processed,
 250   pending output is flushed and deflate returns with Z_STREAM_END if there
 251   was enough output space; if deflate returns with Z_OK, this function must be
 252   called again with Z_FINISH and more output space (updated avail_out) but no
 253   more input data, until it returns with Z_STREAM_END or an error. After
 254   deflate has returned Z_STREAM_END, the only possible operations on the
 255   stream are deflateReset or deflateEnd.
 256
 257     Z_FINISH can be used immediately after deflateInit if all the compression
 258   is to be done in a single step. In this case, avail_out must be at least
 259   0.1% larger than avail_in plus 12 bytes.  If deflate does not return
 260   Z_STREAM_END, then it must be called again as described above.
 261
 262     deflate() sets strm->adler to the adler32 checksum of all input read
 263   so far (that is, total_in bytes).
 264
 265     deflate() may update data_type if it can make a good guess about
 266   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
 267   binary. This field is only for information purposes and does not affect
 268   the compression algorithm in any manner.
 269
 270     deflate() returns Z_OK if some progress has been made (more input
 271   processed or more output produced), Z_STREAM_END if all input has been
 272   consumed and all output has been produced (only when flush is set to
 273   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
 274   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
 275 */
 276
 277
 278 extern int ZEXPORT deflateEnd OF((z_streamp strm));
 279 /*
 280      All dynamically allocated data structures for this stream are freed.
 281    This function discards any unprocessed input and does not flush any
 282    pending output.
 283
 284      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
 285    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
 286    prematurely (some input or output was discarded). In the error case,
 287    msg may be set but then points to a static string (which must not be
 288    deallocated).
 289 */
 290
 291
 292 /*
 293 extern int ZEXPORT inflateInit OF((z_streamp strm));
 294
 295      Initializes the internal stream state for decompression. The fields
 296    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
 297    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
 298    value depends on the compression method), inflateInit determines the
 299    compression method from the zlib header and allocates all data structures
 300    accordingly; otherwise the allocation will be deferred to the first call of
 301    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
 302    use default allocation functions.
 303
 304      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
 305    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 306    version assumed by the caller.  msg is set to null if there is no error
 307    message. inflateInit does not perform any decompression apart from reading
 308    the zlib header if present: this will be done by inflate().  (So next_in and
 309    avail_in may be modified, but next_out and avail_out are unchanged.)
 310 */
 311
 312
 313 extern int ZEXPORT inflate OF((z_streamp strm, int flush));
 314 /*
 315     inflate decompresses as much data as possible, and stops when the input
 316   buffer becomes empty or the output buffer becomes full. It may some
 317   introduce some output latency (reading input without producing any output)
 318   except when forced to flush.
 319
 320   The detailed semantics are as follows. inflate performs one or both of the
 321   following actions:
 322
 323   - Decompress more input starting at next_in and update next_in and avail_in
 324     accordingly. If not all input can be processed (because there is not
 325     enough room in the output buffer), next_in is updated and processing
 326     will resume at this point for the next call of inflate().
 327
 328   - Provide more output starting at next_out and update next_out and avail_out
 329     accordingly.  inflate() provides as much output as possible, until there
 330     is no more input data or no more space in the output buffer (see below
 331     about the flush parameter).
 332
 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
 335   more output, and updating the next_* and avail_* values accordingly.
 336   The application can consume the uncompressed output when it wants, for
 337   example when the output buffer is full (avail_out == 0), or after each
 338   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
 339   must be called again after making room in the output buffer because there
 340   might be more output pending.
 341
 342     If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
 343   output as possible to the output buffer. The flushing behavior of inflate is
 344   not specified for values of the flush parameter other than Z_SYNC_FLUSH
 345   and Z_FINISH, but the current implementation actually flushes as much output
 346   as possible anyway.
 347
 348     inflate() should normally be called until it returns Z_STREAM_END or an
 349   error. However if all decompression is to be performed in a single step
 350   (a single call of inflate), the parameter flush should be set to
 351   Z_FINISH. In this case all pending input is processed and all pending
 352   output is flushed; avail_out must be large enough to hold all the
 353   uncompressed data. (The size of the uncompressed data may have been saved
 354   by the compressor for this purpose.) The next operation on this stream must
 355   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
 356   is never required, but can be used to inform inflate that a faster routine
 357   may be used for the single inflate() call.
 358
 359      If a preset dictionary is needed at this point (see inflateSetDictionary
 360   below), inflate sets strm-adler to the adler32 checksum of the
 361   dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
 362   it sets strm->adler to the adler32 checksum of all output produced
 363   so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
 364   an error code as described below. At the end of the stream, inflate()
 365   checks that its computed adler32 checksum is equal to that saved by the
 366   compressor and returns Z_STREAM_END only if the checksum is correct.
 367
 368     inflate() returns Z_OK if some progress has been made (more input processed
 369   or more output produced), Z_STREAM_END if the end of the compressed data has
 370   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
 371   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
 372   corrupted (input stream not conforming to the zlib format or incorrect
 373   adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
 374   (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
 375   enough memory, Z_BUF_ERROR if no progress is possible or if there was not
 376   enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
 377   case, the application may then call inflateSync to look for a good
 378   compression block.
 379 */
 380
 381
 382 extern int ZEXPORT inflateEnd OF((z_streamp strm));
 383 /*
 384      All dynamically allocated data structures for this stream are freed.
 385    This function discards any unprocessed input and does not flush any
 386    pending output.
 387
 388      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
 389    was inconsistent. In the error case, msg may be set but then points to a
 390    static string (which must not be deallocated).
 391 */
 392
 393                         /* Advanced functions */
 394
 395 /*
 396     The following functions are needed only in some special applications.
 397 */
 398
 399 /*
 400 extern int ZEXPORT deflateInit2 OF((z_streamp strm,
 401                                     int  level,
 402                                     int  method,
 403                                     int  windowBits,
 404                                     int  memLevel,
 405                                     int  strategy));
 406
 407      This is another version of deflateInit with more compression options. The
 408    fields next_in, zalloc, zfree and opaque must be initialized before by
 409    the caller.
 410
 411      The method parameter is the compression method. It must be Z_DEFLATED in
 412    this version of the library.
 413
 414      The windowBits parameter is the base two logarithm of the window size
 415    (the size of the history buffer).  It should be in the range 8..15 for this
 416    version of the library. Larger values of this parameter result in better
 417    compression at the expense of memory usage. The default value is 15 if
 418    deflateInit is used instead.
 419
 420      The memLevel parameter specifies how much memory should be allocated
 421    for the internal compression state. memLevel=1 uses minimum memory but
 422    is slow and reduces compression ratio; memLevel=9 uses maximum memory
 423    for optimal speed. The default value is 8. See zconf.h for total memory
 424    usage as a function of windowBits and memLevel.
 425
 426      The strategy parameter is used to tune the compression algorithm. Use the
 427    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
 428    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
 429    string match).  Filtered data consists mostly of small values with a
 430    somewhat random distribution. In this case, the compression algorithm is
 431    tuned to compress them better. The effect of Z_FILTERED is to force more
 432    Huffman coding and less string matching; it is somewhat intermediate
 433    between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
 434    the compression ratio but not the correctness of the compressed output even
 435    if it is not set appropriately.
 436
 437       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 438    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
 439    method). msg is set to null if there is no error message.  deflateInit2 does
 440    not perform any compression: this will be done by deflate().
 441 */
 442
 443 extern int ZEXPORT deflateSetDictionary OF((z_streamp strm,
 444                                             const Bytef *dictionary,
 445                                             uInt  dictLength));
 446 /*
 447      Initializes the compression dictionary from the given byte sequence
 448    without producing any compressed output. This function must be called
 449    immediately after deflateInit or deflateInit2, before any call of
 450    deflate. The compressor and decompressor must use exactly the same
 451    dictionary (see inflateSetDictionary).
 452
 453      The dictionary should consist of strings (byte sequences) that are likely
 454    to be encountered later in the data to be compressed, with the most commonly
 455    used strings preferably put towards the end of the dictionary. Using a
 456    dictionary is most useful when the data to be compressed is short and can be
 457    predicted with good accuracy; the data can then be compressed better than
 458    with the default empty dictionary.
 459
 460      Depending on the size of the compression data structures selected by
 461    deflateInit or deflateInit2, a part of the dictionary may in effect be
 462    discarded, for example if the dictionary is larger than the window size in
 463    deflate or deflate2. Thus the strings most likely to be useful should be
 464    put at the end of the dictionary, not at the front.
 465
 466      Upon return of this function, strm->adler is set to the Adler32 value
 467    of the dictionary; the decompressor may later use this value to determine
 468    which dictionary has been used by the compressor. (The Adler32 value
 469    applies to the whole dictionary even if only a subset of the dictionary is
 470    actually used by the compressor.)
 471
 472      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
 473    parameter is invalid (such as NULL dictionary) or the stream state is
 474    inconsistent (for example if deflate has already been called for this stream
 475    or if the compression method is bsort). deflateSetDictionary does not
 476    perform any compression: this will be done by deflate().
 477 */
 478
 479 extern int ZEXPORT deflateCopy OF((z_streamp dest,
 480                                    z_streamp source));
 481 /*
 482      Sets the destination stream as a complete copy of the source stream.
 483
 484      This function can be useful when several compression strategies will be
 485    tried, for example when there are several ways of pre-processing the input
 486    data with a filter. The streams that will be discarded should then be freed
 487    by calling deflateEnd.  Note that deflateCopy duplicates the internal
 488    compression state which can be quite large, so this strategy is slow and
 489    can consume lots of memory.
 490
 491      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 492    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 493    (such as zalloc being NULL). msg is left unchanged in both source and
 494    destination.
 495 */
 496
 497 extern int ZEXPORT deflateReset OF((z_streamp strm));
 498 /*
 499      This function is equivalent to deflateEnd followed by deflateInit,
 500    but does not free and reallocate all the internal compression state.
 501    The stream will keep the same compression level and any other attributes
 502    that may have been set by deflateInit2.
 503
 504       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 505    stream state was inconsistent (such as zalloc or state being NULL).
 506 */
 507
 508 extern int ZEXPORT deflateParams OF((z_streamp strm, int level, int strategy));
 509 /*
 510      Dynamically update the compression level and compression strategy.  The
 511    interpretation of level and strategy is as in deflateInit2.  This can be
 512    used to switch between compression and straight copy of the input data, or
 513    to switch to a different kind of input data requiring a different
 514    strategy. If the compression level is changed, the input available so far
 515    is compressed with the old level (and may be flushed); the new level will
 516    take effect only at the next call of deflate().
 517
 518      Before the call of deflateParams, the stream state must be set as for
 519    a call of deflate(), since the currently available input may have to
 520    be compressed and flushed. In particular, strm->avail_out must be non-zero.
 521
 522      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
 523    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
 524    if strm->avail_out was zero.
 525 */
 526
 527 /*
 528 extern int ZEXPORT inflateInit2 OF((z_streamp strm,
 529                                     int  windowBits));
 530
 531      This is another version of inflateInit with an extra parameter. The
 532    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
 533    before by the caller.
 534
 535      The windowBits parameter is the base two logarithm of the maximum window
 536    size (the size of the history buffer).  It should be in the range 8..15 for
 537    this version of the library. The default value is 15 if inflateInit is used
 538    instead. If a compressed stream with a larger window size is given as
 539    input, inflate() will return with the error code Z_DATA_ERROR instead of
 540    trying to allocate a larger window.
 541
 542       inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 543    memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
 544    memLevel). msg is set to null if there is no error message.  inflateInit2
 545    does not perform any decompression apart from reading the zlib header if
 546    present: this will be done by inflate(). (So next_in and avail_in may be
 547    modified, but next_out and avail_out are unchanged.)
 548 */
 549
 550 extern int ZEXPORT inflateSetDictionary OF((z_streamp strm,
 551                                             const Bytef *dictionary,
 552                                             uInt  dictLength));
 553 /*
 554      Initializes the decompression dictionary from the given uncompressed byte
 555    sequence. This function must be called immediately after a call of inflate
 556    if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
 557    can be determined from the Adler32 value returned by this call of
 558    inflate. The compressor and decompressor must use exactly the same
 559    dictionary (see deflateSetDictionary).
 560
 561      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
 562    parameter is invalid (such as NULL dictionary) or the stream state is
 563    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
 564    expected one (incorrect Adler32 value). inflateSetDictionary does not
 565    perform any decompression: this will be done by subsequent calls of
 566    inflate().
 567 */
 568
 569 extern int ZEXPORT inflateSync OF((z_streamp strm));
 570 /*
 571     Skips invalid compressed data until a full flush point (see above the
 572   description of deflate with Z_FULL_FLUSH) can be found, or until all
 573   available input is skipped. No output is provided.
 574
 575     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
 576   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
 577   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
 578   case, the application may save the current current value of total_in which
 579   indicates where valid compressed data was found. In the error case, the
 580   application may repeatedly call inflateSync, providing more input each time,
 581   until success or end of the input data.
 582 */
 583
 584 extern int ZEXPORT inflateReset OF((z_streamp strm));
 585 /*
 586      This function is equivalent to inflateEnd followed by inflateInit,
 587    but does not free and reallocate all the internal decompression state.
 588    The stream will keep attributes that may have been set by inflateInit2.
 589
 590       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 591    stream state was inconsistent (such as zalloc or state being NULL).
 592 */
 593
 594
 595                         /* utility functions */
 596
 597 /*
 598      The following utility functions are implemented on top of the
 599    basic stream-oriented functions. To simplify the interface, some
 600    default options are assumed (compression level and memory usage,
 601    standard memory allocation functions). The source code of these
 602    utility functions can easily be modified if you need special options.
 603 */
 604
 605 extern int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
 606                                 const Bytef *source, uLong sourceLen));
 607 /*
 608      Compresses the source buffer into the destination buffer.  sourceLen is
 609    the byte length of the source buffer. Upon entry, destLen is the total
 610    size of the destination buffer, which must be at least 0.1% larger than
 611    sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
 612    compressed buffer.
 613      This function can be used to compress a whole file at once if the
 614    input file is mmap'ed.
 615      compress returns Z_OK if success, Z_MEM_ERROR if there was not
 616    enough memory, Z_BUF_ERROR if there was not enough room in the output
 617    buffer.
 618 */
 619
 620 extern int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
 621                                  const Bytef *source, uLong sourceLen,
 622                                  int level));
 623 /*
 624      Compresses the source buffer into the destination buffer. The level
 625    parameter has the same meaning as in deflateInit.  sourceLen is the byte
 626    length of the source buffer. Upon entry, destLen is the total size of the
 627    destination buffer, which must be at least 0.1% larger than sourceLen plus
 628    12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
 629
 630      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 631    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
 632    Z_STREAM_ERROR if the level parameter is invalid.
 633 */
 634
 635 extern int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
 636                                   const Bytef *source, uLong sourceLen));
 637 /*
 638      Decompresses the source buffer into the destination buffer.  sourceLen is
 639    the byte length of the source buffer. Upon entry, destLen is the total
 640    size of the destination buffer, which must be large enough to hold the
 641    entire uncompressed data. (The size of the uncompressed data must have
 642    been saved previously by the compressor and transmitted to the decompressor
 643    by some mechanism outside the scope of this compression library.)
 644    Upon exit, destLen is the actual size of the compressed buffer.
 645      This function can be used to decompress a whole file at once if the
 646    input file is mmap'ed.
 647
 648      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
 649    enough memory, Z_BUF_ERROR if there was not enough room in the output
 650    buffer, or Z_DATA_ERROR if the input data was corrupted.
 651 */
 652
 653
 654 typedef voidp gzFile;
 655
 656 extern gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
 657 /*
 658      Opens a gzip (.gz) file for reading or writing. The mode parameter
 659    is as in fopen ("rb" or "wb") but can also include a compression level
 660    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
 661    Huffman only compression as in "wb1h". (See the description
 662    of deflateInit2 for more information about the strategy parameter.)
 663
 664      gzopen can be used to read a file which is not in gzip format; in this
 665    case gzread will directly read from the file without decompression.
 666
 667      gzopen returns NULL if the file could not be opened or if there was
 668    insufficient memory to allocate the (de)compression state; errno
 669    can be checked to distinguish the two cases (if errno is zero, the
 670    zlib error is Z_MEM_ERROR).  */
 671
 672 extern gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
 673 /*
 674      gzdopen() associates a gzFile with the file descriptor fd.  File
 675    descriptors are obtained from calls like open, dup, creat, pipe or
 676    fileno (in the file has been previously opened with fopen).
 677    The mode parameter is as in gzopen.
 678      The next call of gzclose on the returned gzFile will also close the
 679    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
 680    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
 681      gzdopen returns NULL if there was insufficient memory to allocate
 682    the (de)compression state.
 683 */
 684
 685 extern int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
 686 /*
 687      Dynamically update the compression level or strategy. See the description
 688    of deflateInit2 for the meaning of these parameters.
 689      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
 690    opened for writing.
 691 */
 692
 693 extern int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
 694 /*
 695      Reads the given number of uncompressed bytes from the compressed file.
 696    If the input file was not in gzip format, gzread copies the given number
 697    of bytes into the buffer.
 698      gzread returns the number of uncompressed bytes actually read (0 for
 699    end of file, -1 for error). */
 700
 701 extern int ZEXPORT    gzwrite OF((gzFile file, const voidp buf, unsigned len));
 702 /*
 703      Writes the given number of uncompressed bytes into the compressed file.
 704    gzwrite returns the number of uncompressed bytes actually written
 705    (0 in case of error).
 706 */
 707
 708 extern int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
 709 /*
 710      Converts, formats, and writes the args to the compressed file under
 711    control of the format string, as in fprintf. gzprintf returns the number of
 712    uncompressed bytes actually written (0 in case of error).
 713 */
 714
 715 extern int ZEXPORT gzputs OF((gzFile file, const char *s));
 716 /*
 717       Writes the given null-terminated string to the compressed file, excluding
 718    the terminating null character.
 719       gzputs returns the number of characters written, or -1 in case of error.
 720 */
 721
 722 extern char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
 723 /*
 724       Reads bytes from the compressed file until len-1 characters are read, or
 725    a newline character is read and transferred to buf, or an end-of-file
 726    condition is encountered.  The string is then terminated with a null
 727    character.
 728       gzgets returns buf, or Z_NULL in case of error.
 729 */
 730
 731 extern int ZEXPORT    gzputc OF((gzFile file, int c));
 732 /*
 733       Writes c, converted to an unsigned char, into the compressed file.
 734    gzputc returns the value that was written, or -1 in case of error.
 735 */
 736
 737 extern int ZEXPORT    gzgetc OF((gzFile file));
 738 /*
 739       Reads one byte from the compressed file. gzgetc returns this byte
 740    or -1 in case of end of file or error.
 741 */
 742
 743 extern int ZEXPORT    gzflush OF((gzFile file, int flush));
 744 /*
 745      Flushes all pending output into the compressed file. The parameter
 746    flush is as in the deflate() function. The return value is the zlib
 747    error number (see function gzerror below). gzflush returns Z_OK if
 748    the flush parameter is Z_FINISH and all output could be flushed.
 749      gzflush should be called only when strictly necessary because it can
 750    degrade compression.
 751 */
 752
 753 extern z_off_t ZEXPORT    gzseek OF((gzFile file, z_off_t offset, int whence));
 754 /*
 755       Sets the starting position for the next gzread or gzwrite on the given
 756    compressed file. The offset represents a number of bytes in the
 757    uncompressed data stream. The whence parameter is defined as in lseek(2);
 758    the value SEEK_END is not supported.
 759      If the file is opened for reading, this function is emulated but can be
 760    extremely slow. If the file is opened for writing, only forward seeks are
 761    supported; gzseek then compresses a sequence of zeroes up to the new
 762    starting position.
 763
 764       gzseek returns the resulting offset location as measured in bytes from
 765    the beginning of the uncompressed stream, or -1 in case of error, in
 766    particular if the file is opened for writing and the new starting position
 767    would be before the current position.
 768 */
 769
 770 extern int ZEXPORT    gzrewind OF((gzFile file));
 771 /*
 772      Rewinds the given file. This function is supported only for reading.
 773
 774    gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
 775 */
 776
 777 extern z_off_t ZEXPORT    gztell OF((gzFile file));
 778 /*
 779      Returns the starting position for the next gzread or gzwrite on the
 780    given compressed file. This position represents a number of bytes in the
 781    uncompressed data stream.
 782
 783    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
 784 */
 785
 786 extern int ZEXPORT gzeof OF((gzFile file));
 787 /*
 788      Returns 1 when EOF has previously been detected reading the given
 789    input stream, otherwise zero.
 790 */
 791
 792 extern int ZEXPORT    gzclose OF((gzFile file));
 793 /*
 794      Flushes all pending output if necessary, closes the compressed file
 795    and deallocates all the (de)compression state. The return value is the zlib
 796    error number (see function gzerror below).
 797 */
 798
 799 extern const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
 800 /*
 801      Returns the error message for the last error which occurred on the
 802    given compressed file. errnum is set to zlib error number. If an
 803    error occurred in the file system and not in the compression library,
 804    errnum is set to Z_ERRNO and the application may consult errno
 805    to get the exact error code.
 806 */
 807
 808                         /* checksum functions */
 809
 810 /*
 811      These functions are not related to compression but are exported
 812    anyway because they might be useful in applications using the
 813    compression library.
 814 */
 815
 816 extern uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
 817
 818 /*
 819      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
 820    return the updated checksum. If buf is NULL, this function returns
 821    the required initial value for the checksum.
 822    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
 823    much faster. Usage example:
 824
 825      uLong adler = adler32(0L, Z_NULL, 0);
 826
 827      while (read_buffer(buffer, length) != EOF) {
 828        adler = adler32(adler, buffer, length);
 829      }
 830      if (adler != original_adler) error();
 831 */
 832
 833 extern uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
 834 /*
 835      Update a running crc with the bytes buf[0..len-1] and return the updated
 836    crc. If buf is NULL, this function returns the required initial value
 837    for the crc. Pre- and post-conditioning (one's complement) is performed
 838    within this function so it shouldn't be done by the application.
 839    Usage example:
 840
 841      uLong crc = crc32(0L, Z_NULL, 0);
 842
 843      while (read_buffer(buffer, length) != EOF) {
 844        crc = crc32(crc, buffer, length);
 845      }
 846      if (crc != original_crc) error();
 847 */
 848
 849
 850                         /* various hacks, don't look :) */
 851
 852 /* deflateInit and inflateInit are macros to allow checking the zlib version
 853  * and the compiler's view of z_stream:
 854  */
 855 extern int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
 856                                     const char *version, int stream_size));
 857 extern int ZEXPORT inflateInit_ OF((z_streamp strm,
 858                                     const char *version, int stream_size));
 859 extern int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
 860                                      int windowBits, int memLevel,
 861                                      int strategy, const char *version,
 862                                      int stream_size));
 863 extern int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
 864                                      const char *version, int stream_size));
 865 #define deflateInit(strm, level) \
 866         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
 867 #define inflateInit(strm) \
 868         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
 869 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
 870         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
 871                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
 872 #define inflateInit2(strm, windowBits) \
 873         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
 874
 875
 876 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
 877     struct internal_state {int dummy;}; /* hack for buggy compilers */
 878 #endif
 879
 880 extern const char   * ZEXPORT zError           OF((int err));
 881 extern int            ZEXPORT inflateSyncPoint OF((z_streamp z));
 882 extern const uLongf * ZEXPORT get_crc_table    OF((void));
 883
 884 #ifdef __cplusplus
 885 }
 886 #endif
 887
 888 #endif /* _ZLIB_H */