zlib/zlib.h

   1 /* zlib.h -- interface of the 'zlib' general purpose compression library
   2   version 1.1.3, July 9th, 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 "zconf.h"
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 #define ZLIB_VERSION "1.1.3"
  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 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
 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 ZEXTERN 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 ZEXTERN 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   (for example avail_in or avail_out was zero).
 276 */
 277
 278
 279 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
 280 /*
 281      All dynamically allocated data structures for this stream are freed.
 282    This function discards any unprocessed input and does not flush any
 283    pending output.
 284
 285      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
 286    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
 287    prematurely (some input or output was discarded). In the error case,
 288    msg may be set but then points to a static string (which must not be
 289    deallocated).
 290 */
 291
 292
 293 /*
 294 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
 295
 296      Initializes the internal stream state for decompression. The fields
 297    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
 298    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
 299    value depends on the compression method), inflateInit determines the
 300    compression method from the zlib header and allocates all data structures
 301    accordingly; otherwise the allocation will be deferred to the first call of
 302    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
 303    use default allocation functions.
 304
 305      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
 306    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 307    version assumed by the caller.  msg is set to null if there is no error
 308    message. inflateInit does not perform any decompression apart from reading
 309    the zlib header if present: this will be done by inflate().  (So next_in and
 310    avail_in may be modified, but next_out and avail_out are unchanged.)
 311 */
 312
 313
 314 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
 315 /*
 316     inflate decompresses as much data as possible, and stops when the input
 317   buffer becomes empty or the output buffer becomes full. It may some
 318   introduce some output latency (reading input without producing any output)
 319   except when forced to flush.
 320
 321   The detailed semantics are as follows. inflate performs one or both of the
 322   following actions:
 323
 324   - Decompress more input starting at next_in and update next_in and avail_in
 325     accordingly. If not all input can be processed (because there is not
 326     enough room in the output buffer), next_in is updated and processing
 327     will resume at this point for the next call of inflate().
 328
 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
 331     is no more input data or no more space in the output buffer (see below
 332     about the flush parameter).
 333
 334   Before the call of inflate(), the application should ensure that at least
 335   one of the actions is possible, by providing more input and/or consuming
 336   more output, and updating the next_* and avail_* values accordingly.
 337   The application can consume the uncompressed output when it wants, for
 338   example when the output buffer is full (avail_out == 0), or after each
 339   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
 340   must be called again after making room in the output buffer because there
 341   might be more output pending.
 342
 343     If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
 344   output as possible to the output buffer. The flushing behavior of inflate is
 345   not specified for values of the flush parameter other than Z_SYNC_FLUSH
 346   and Z_FINISH, but the current implementation actually flushes as much output
 347   as possible anyway.
 348
 349     inflate() should normally be called until it returns Z_STREAM_END or an
 350   error. However if all decompression is to be performed in a single step
 351   (a single call of inflate), the parameter flush should be set to
 352   Z_FINISH. In this case all pending input is processed and all pending
 353   output is flushed; avail_out must be large enough to hold all the
 354   uncompressed data. (The size of the uncompressed data may have been saved
 355   by the compressor for this purpose.) The next operation on this stream must
 356   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
 357   is never required, but can be used to inform inflate that a faster routine
 358   may be used for the single inflate() call.
 359
 360      If a preset dictionary is needed at this point (see inflateSetDictionary
 361   below), inflate sets strm-adler to the adler32 checksum of the
 362   dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
 363   it sets strm->adler to the adler32 checksum of all output produced
 364   so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
 365   an error code as described below. At the end of the stream, inflate()
 366   checks that its computed adler32 checksum is equal to that saved by the
 367   compressor and returns Z_STREAM_END only if the checksum is correct.
 368
 369     inflate() returns Z_OK if some progress has been made (more input processed
 370   or more output produced), Z_STREAM_END if the end of the compressed data has
 371   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
 372   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
 373   corrupted (input stream not conforming to the zlib format or incorrect
 374   adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
 375   (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
 376   enough memory, Z_BUF_ERROR if no progress is possible or if there was not
 377   enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
 378   case, the application may then call inflateSync to look for a good
 379   compression block.
 380 */
 381
 382
 383 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
 384 /*
 385      All dynamically allocated data structures for this stream are freed.
 386    This function discards any unprocessed input and does not flush any
 387    pending output.
 388
 389      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
 390    was inconsistent. In the error case, msg may be set but then points to a
 391    static string (which must not be deallocated).
 392 */
 393
 394                         /* Advanced functions */
 395
 396 /*
 397     The following functions are needed only in some special applications.
 398 */
 399
 400 /*
 401 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
 402                                      int  level,
 403                                      int  method,
 404                                      int  windowBits,
 405                                      int  memLevel,
 406                                      int  strategy));
 407
 408      This is another version of deflateInit with more compression options. The
 409    fields next_in, zalloc, zfree and opaque must be initialized before by
 410    the caller.
 411
 412      The method parameter is the compression method. It must be Z_DEFLATED in
 413    this version of the library.
 414
 415      The windowBits parameter is the base two logarithm of the window size
 416    (the size of the history buffer).  It should be in the range 8..15 for this
 417    version of the library. Larger values of this parameter result in better
 418    compression at the expense of memory usage. The default value is 15 if
 419    deflateInit is used instead.
 420
 421      The memLevel parameter specifies how much memory should be allocated
 422    for the internal compression state. memLevel=1 uses minimum memory but
 423    is slow and reduces compression ratio; memLevel=9 uses maximum memory
 424    for optimal speed. The default value is 8. See zconf.h for total memory
 425    usage as a function of windowBits and memLevel.
 426
 427      The strategy parameter is used to tune the compression algorithm. Use the
 428    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
 429    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
 430    string match).  Filtered data consists mostly of small values with a
 431    somewhat random distribution. In this case, the compression algorithm is
 432    tuned to compress them better. The effect of Z_FILTERED is to force more
 433    Huffman coding and less string matching; it is somewhat intermediate
 434    between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
 435    the compression ratio but not the correctness of the compressed output even
 436    if it is not set appropriately.
 437
 438       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 439    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
 440    method). msg is set to null if there is no error message.  deflateInit2 does
 441    not perform any compression: this will be done by deflate().
 442 */
 443
 444 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
 445                                              const Bytef *dictionary,
 446                                              uInt  dictLength));
 447 /*
 448      Initializes the compression dictionary from the given byte sequence
 449    without producing any compressed output. This function must be called
 450    immediately after deflateInit, deflateInit2 or deflateReset, before any
 451    call of deflate. The compressor and decompressor must use exactly the same
 452    dictionary (see inflateSetDictionary).
 453
 454      The dictionary should consist of strings (byte sequences) that are likely
 455    to be encountered later in the data to be compressed, with the most commonly
 456    used strings preferably put towards the end of the dictionary. Using a
 457    dictionary is most useful when the data to be compressed is short and can be
 458    predicted with good accuracy; the data can then be compressed better than
 459    with the default empty dictionary.
 460
 461      Depending on the size of the compression data structures selected by
 462    deflateInit or deflateInit2, a part of the dictionary may in effect be
 463    discarded, for example if the dictionary is larger than the window size in
 464    deflate or deflate2. Thus the strings most likely to be useful should be
 465    put at the end of the dictionary, not at the front.
 466
 467      Upon return of this function, strm->adler is set to the Adler32 value
 468    of the dictionary; the decompressor may later use this value to determine
 469    which dictionary has been used by the compressor. (The Adler32 value
 470    applies to the whole dictionary even if only a subset of the dictionary is
 471    actually used by the compressor.)
 472
 473      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
 474    parameter is invalid (such as NULL dictionary) or the stream state is
 475    inconsistent (for example if deflate has already been called for this stream
 476    or if the compression method is bsort). deflateSetDictionary does not
 477    perform any compression: this will be done by deflate().
 478 */
 479
 480 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
 481                                     z_streamp source));
 482 /*
 483      Sets the destination stream as a complete copy of the source stream.
 484
 485      This function can be useful when several compression strategies will be
 486    tried, for example when there are several ways of pre-processing the input
 487    data with a filter. The streams that will be discarded should then be freed
 488    by calling deflateEnd.  Note that deflateCopy duplicates the internal
 489    compression state which can be quite large, so this strategy is slow and
 490    can consume lots of memory.
 491
 492      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 493    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 494    (such as zalloc being NULL). msg is left unchanged in both source and
 495    destination.
 496 */
 497
 498 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
 499 /*
 500      This function is equivalent to deflateEnd followed by deflateInit,
 501    but does not free and reallocate all the internal compression state.
 502    The stream will keep the same compression level and any other attributes
 503    that may have been set by deflateInit2.
 504
 505       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 506    stream state was inconsistent (such as zalloc or state being NULL).
 507 */
 508
 509 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
 510                                       int level,
 511                                       int strategy));
 512 /*
 513      Dynamically update the compression level and compression strategy.  The
 514    interpretation of level and strategy is as in deflateInit2.  This can be
 515    used to switch between compression and straight copy of the input data, or
 516    to switch to a different kind of input data requiring a different
 517    strategy. If the compression level is changed, the input available so far
 518    is compressed with the old level (and may be flushed); the new level will
 519    take effect only at the next call of deflate().
 520
 521      Before the call of deflateParams, the stream state must be set as for
 522    a call of deflate(), since the currently available input may have to
 523    be compressed and flushed. In particular, strm->avail_out must be non-zero.
 524
 525      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
 526    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
 527    if strm->avail_out was zero.
 528 */
 529
 530 /*
 531 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
 532                                      int  windowBits));
 533
 534      This is another version of inflateInit with an extra parameter. The
 535    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
 536    before by the caller.
 537
 538      The windowBits parameter is the base two logarithm of the maximum window
 539    size (the size of the history buffer).  It should be in the range 8..15 for
 540    this version of the library. The default value is 15 if inflateInit is used
 541    instead. If a compressed stream with a larger window size is given as
 542    input, inflate() will return with the error code Z_DATA_ERROR instead of
 543    trying to allocate a larger window.
 544
 545       inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 546    memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
 547    memLevel). msg is set to null if there is no error message.  inflateInit2
 548    does not perform any decompression apart from reading the zlib header if
 549    present: this will be done by inflate(). (So next_in and avail_in may be
 550    modified, but next_out and avail_out are unchanged.)
 551 */
 552
 553 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
 554                                              const Bytef *dictionary,
 555                                              uInt  dictLength));
 556 /*
 557      Initializes the decompression dictionary from the given uncompressed byte
 558    sequence. This function must be called immediately after a call of inflate
 559    if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
 560    can be determined from the Adler32 value returned by this call of
 561    inflate. The compressor and decompressor must use exactly the same
 562    dictionary (see deflateSetDictionary).
 563
 564      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
 565    parameter is invalid (such as NULL dictionary) or the stream state is
 566    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
 567    expected one (incorrect Adler32 value). inflateSetDictionary does not
 568    perform any decompression: this will be done by subsequent calls of
 569    inflate().
 570 */
 571
 572 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
 573 /*
 574     Skips invalid compressed data until a full flush point (see above the
 575   description of deflate with Z_FULL_FLUSH) can be found, or until all
 576   available input is skipped. No output is provided.
 577
 578     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
 579   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
 580   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
 581   case, the application may save the current current value of total_in which
 582   indicates where valid compressed data was found. In the error case, the
 583   application may repeatedly call inflateSync, providing more input each time,
 584   until success or end of the input data.
 585 */
 586
 587 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
 588 /*
 589      This function is equivalent to inflateEnd followed by inflateInit,
 590    but does not free and reallocate all the internal decompression state.
 591    The stream will keep attributes that may have been set by inflateInit2.
 592
 593       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 594    stream state was inconsistent (such as zalloc or state being NULL).
 595 */
 596
 597
 598                         /* utility functions */
 599
 600 /*
 601      The following utility functions are implemented on top of the
 602    basic stream-oriented functions. To simplify the interface, some
 603    default options are assumed (compression level and memory usage,
 604    standard memory allocation functions). The source code of these
 605    utility functions can easily be modified if you need special options.
 606 */
 607
 608 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
 609                                  const Bytef *source, uLong sourceLen));
 610 /*
 611      Compresses the source buffer into the destination buffer.  sourceLen is
 612    the byte length of the source buffer. Upon entry, destLen is the total
 613    size of the destination buffer, which must be at least 0.1% larger than
 614    sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
 615    compressed buffer.
 616      This function can be used to compress a whole file at once if the
 617    input file is mmap'ed.
 618      compress returns Z_OK if success, Z_MEM_ERROR if there was not
 619    enough memory, Z_BUF_ERROR if there was not enough room in the output
 620    buffer.
 621 */
 622
 623 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
 624                                   const Bytef *source, uLong sourceLen,
 625                                   int level));
 626 /*
 627      Compresses the source buffer into the destination buffer. The level
 628    parameter has the same meaning as in deflateInit.  sourceLen is the byte
 629    length of the source buffer. Upon entry, destLen is the total size of the
 630    destination buffer, which must be at least 0.1% larger than sourceLen plus
 631    12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
 632
 633      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 634    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
 635    Z_STREAM_ERROR if the level parameter is invalid.
 636 */
 637
 638 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
 639                                    const Bytef *source, uLong sourceLen));
 640 /*
 641      Decompresses the source buffer into the destination buffer.  sourceLen is
 642    the byte length of the source buffer. Upon entry, destLen is the total
 643    size of the destination buffer, which must be large enough to hold the
 644    entire uncompressed data. (The size of the uncompressed data must have
 645    been saved previously by the compressor and transmitted to the decompressor
 646    by some mechanism outside the scope of this compression library.)
 647    Upon exit, destLen is the actual size of the compressed buffer.
 648      This function can be used to decompress a whole file at once if the
 649    input file is mmap'ed.
 650
 651      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
 652    enough memory, Z_BUF_ERROR if there was not enough room in the output
 653    buffer, or Z_DATA_ERROR if the input data was corrupted.
 654 */
 655
 656
 657 typedef voidp gzFile;
 658
 659 ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
 660 /*
 661      Opens a gzip (.gz) file for reading or writing. The mode parameter
 662    is as in fopen ("rb" or "wb") but can also include a compression level
 663    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
 664    Huffman only compression as in "wb1h". (See the description
 665    of deflateInit2 for more information about the strategy parameter.)
 666
 667      gzopen can be used to read a file which is not in gzip format; in this
 668    case gzread will directly read from the file without decompression.
 669
 670      gzopen returns NULL if the file could not be opened or if there was
 671    insufficient memory to allocate the (de)compression state; errno
 672    can be checked to distinguish the two cases (if errno is zero, the
 673    zlib error is Z_MEM_ERROR).  */
 674
 675 ZEXTERN gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
 676 /*
 677      gzdopen() associates a gzFile with the file descriptor fd.  File
 678    descriptors are obtained from calls like open, dup, creat, pipe or
 679    fileno (in the file has been previously opened with fopen).
 680    The mode parameter is as in gzopen.
 681      The next call of gzclose on the returned gzFile will also close the
 682    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
 683    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
 684      gzdopen returns NULL if there was insufficient memory to allocate
 685    the (de)compression state.
 686 */
 687
 688 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
 689 /*
 690      Dynamically update the compression level or strategy. See the description
 691    of deflateInit2 for the meaning of these parameters.
 692      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
 693    opened for writing.
 694 */
 695
 696 ZEXTERN int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
 697 /*
 698      Reads the given number of uncompressed bytes from the compressed file.
 699    If the input file was not in gzip format, gzread copies the given number
 700    of bytes into the buffer.
 701      gzread returns the number of uncompressed bytes actually read (0 for
 702    end of file, -1 for error). */
 703
 704 ZEXTERN int ZEXPORT    gzwrite OF((gzFile file,
 705                                    const voidp buf, unsigned len));
 706 /*
 707      Writes the given number of uncompressed bytes into the compressed file.
 708    gzwrite returns the number of uncompressed bytes actually written
 709    (0 in case of error).
 710 */
 711
 712 ZEXTERN int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
 713 /*
 714      Converts, formats, and writes the args to the compressed file under
 715    control of the format string, as in fprintf. gzprintf returns the number of
 716    uncompressed bytes actually written (0 in case of error).
 717 */
 718
 719 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
 720 /*
 721       Writes the given null-terminated string to the compressed file, excluding
 722    the terminating null character.
 723       gzputs returns the number of characters written, or -1 in case of error.
 724 */
 725
 726 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
 727 /*
 728       Reads bytes from the compressed file until len-1 characters are read, or
 729    a newline character is read and transferred to buf, or an end-of-file
 730    condition is encountered.  The string is then terminated with a null
 731    character.
 732       gzgets returns buf, or Z_NULL in case of error.
 733 */
 734
 735 ZEXTERN int ZEXPORT    gzputc OF((gzFile file, int c));
 736 /*
 737       Writes c, converted to an unsigned char, into the compressed file.
 738    gzputc returns the value that was written, or -1 in case of error.
 739 */
 740
 741 ZEXTERN int ZEXPORT    gzgetc OF((gzFile file));
 742 /*
 743       Reads one byte from the compressed file. gzgetc returns this byte
 744    or -1 in case of end of file or error.
 745 */
 746
 747 ZEXTERN int ZEXPORT    gzflush OF((gzFile file, int flush));
 748 /*
 749      Flushes all pending output into the compressed file. The parameter
 750    flush is as in the deflate() function. The return value is the zlib
 751    error number (see function gzerror below). gzflush returns Z_OK if
 752    the flush parameter is Z_FINISH and all output could be flushed.
 753      gzflush should be called only when strictly necessary because it can
 754    degrade compression.
 755 */
 756
 757 ZEXTERN z_off_t ZEXPORT    gzseek OF((gzFile file,
 758                                       z_off_t offset, int whence));
 759 /*
 760       Sets the starting position for the next gzread or gzwrite on the
 761    given compressed file. The offset represents a number of bytes in the
 762    uncompressed data stream. The whence parameter is defined as in lseek(2);
 763    the value SEEK_END is not supported.
 764      If the file is opened for reading, this function is emulated but can be
 765    extremely slow. If the file is opened for writing, only forward seeks are
 766    supported; gzseek then compresses a sequence of zeroes up to the new
 767    starting position.
 768
 769       gzseek returns the resulting offset location as measured in bytes from
 770    the beginning of the uncompressed stream, or -1 in case of error, in
 771    particular if the file is opened for writing and the new starting position
 772    would be before the current position.
 773 */
 774
 775 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
 776 /*
 777      Rewinds the given file. This function is supported only for reading.
 778
 779    gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
 780 */
 781
 782 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
 783 /*
 784      Returns the starting position for the next gzread or gzwrite on the
 785    given compressed file. This position represents a number of bytes in the
 786    uncompressed data stream.
 787
 788    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
 789 */
 790
 791 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
 792 /*
 793      Returns 1 when EOF has previously been detected reading the given
 794    input stream, otherwise zero.
 795 */
 796
 797 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
 798 /*
 799      Flushes all pending output if necessary, closes the compressed file
 800    and deallocates all the (de)compression state. The return value is the zlib
 801    error number (see function gzerror below).
 802 */
 803
 804 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
 805 /*
 806      Returns the error message for the last error which occurred on the
 807    given compressed file. errnum is set to zlib error number. If an
 808    error occurred in the file system and not in the compression library,
 809    errnum is set to Z_ERRNO and the application may consult errno
 810    to get the exact error code.
 811 */
 812
 813                         /* checksum functions */
 814
 815 /*
 816      These functions are not related to compression but are exported
 817    anyway because they might be useful in applications using the
 818    compression library.
 819 */
 820
 821 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
 822
 823 /*
 824      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
 825    return the updated checksum. If buf is NULL, this function returns
 826    the required initial value for the checksum.
 827    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
 828    much faster. Usage example:
 829
 830      uLong adler = adler32(0L, Z_NULL, 0);
 831
 832      while (read_buffer(buffer, length) != EOF) {
 833        adler = adler32(adler, buffer, length);
 834      }
 835      if (adler != original_adler) error();
 836 */
 837
 838 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
 839 /*
 840      Update a running crc with the bytes buf[0..len-1] and return the updated
 841    crc. If buf is NULL, this function returns the required initial value
 842    for the crc. Pre- and post-conditioning (one's complement) is performed
 843    within this function so it shouldn't be done by the application.
 844    Usage example:
 845
 846      uLong crc = crc32(0L, Z_NULL, 0);
 847
 848      while (read_buffer(buffer, length) != EOF) {
 849        crc = crc32(crc, buffer, length);
 850      }
 851      if (crc != original_crc) error();
 852 */
 853
 854
 855                         /* various hacks, don't look :) */
 856
 857 /* deflateInit and inflateInit are macros to allow checking the zlib version
 858  * and the compiler's view of z_stream:
 859  */
 860 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
 861                                      const char *version, int stream_size));
 862 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
 863                                      const char *version, int stream_size));
 864 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
 865                                       int windowBits, int memLevel,
 866                                       int strategy, const char *version,
 867                                       int stream_size));
 868 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
 869                                       const char *version, int stream_size));
 870 #define deflateInit(strm, level) \
 871         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
 872 #define inflateInit(strm) \
 873         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
 874 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
 875         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
 876                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
 877 #define inflateInit2(strm, windowBits) \
 878         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
 879
 880
 881 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
 882     struct internal_state {int dummy;}; /* hack for buggy compilers */
 883 #endif
 884
 885 ZEXTERN const char   * ZEXPORT zError           OF((int err));
 886 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp z));
 887 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
 888
 889 #ifdef __cplusplus
 890 }
 891 #endif
 892
 893 #endif /* _ZLIB_H */