usr/src/cmd/cmd-inet/usr.bin/pppdump/zlib.h

   1 /*      $Id: zlib.h,v 1.1 1999/03/23 03:21:58 paulus Exp $      */
   2
   3 /*
   4  * This file is derived from zlib.h and zconf.h from the zlib-0.95
   5  * distribution by Jean-loup Gailly and Mark Adler, with some additions
   6  * by Paul Mackerras to aid in implementing Deflate compression and
   7  * decompression for PPP packets.
   8  */
   9
  10 /* zlib.h -- interface of the 'zlib' general purpose compression library
  11   version 0.95, Aug 16th, 1995.
  12
  13   Copyright (C) 1995 Jean-loup Gailly and Mark Adler
  14
  15   This software is provided 'as-is', without any express or implied
  16   warranty.  In no event will the authors be held liable for any damages
  17   arising from the use of this software.
  18
  19   Permission is granted to anyone to use this software for any purpose,
  20   including commercial applications, and to alter it and redistribute it
  21   freely, subject to the following restrictions:
  22
  23   1. The origin of this software must not be misrepresented; you must not
  24      claim that you wrote the original software. If you use this software
  25      in a product, an acknowledgment in the product documentation would be
  26      appreciated but is not required.
  27   2. Altered source versions must be plainly marked as such, and must not be
  28      misrepresented as being the original software.
  29   3. This notice may not be removed or altered from any source distribution.
  30
  31   Jean-loup Gailly        Mark Adler
  32   gzip@prep.ai.mit.edu    madler@alumni.caltech.edu
  33  */
  34
  35 #ifndef _ZLIB_H
  36 #define _ZLIB_H
  37
  38 /* #include "zconf.h" */        /* included directly here */
  39
  40 /* zconf.h -- configuration of the zlib compression library
  41  * Copyright (C) 1995 Jean-loup Gailly.
  42  * For conditions of distribution and use, see copyright notice in zlib.h
  43  */
  44
  45 /* From: zconf.h,v 1.12 1995/05/03 17:27:12 jloup Exp */
  46
  47 /*
  48      The library does not install any signal handler. It is recommended to
  49   add at least a handler for SIGSEGV when decompressing; the library checks
  50   the consistency of the input data whenever possible but may go nuts
  51   for some forms of corrupted input.
  52  */
  53
  54 /*
  55  * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
  56  * than 64k bytes at a time (needed on systems with 16-bit int).
  57  * Compile with -DUNALIGNED_OK if it is OK to access shorts or ints
  58  * at addresses which are not a multiple of their size.
  59  * Under DOS, -DFAR=far or -DFAR=__far may be needed.
  60  */
  61
  62 #ifndef STDC
  63 #  if defined(MSDOS) || defined(__STDC__) || defined(__cplusplus)
  64 #    define STDC
  65 #  endif
  66 #endif
  67
  68 #ifdef  __MWERKS__ /* Metrowerks CodeWarrior declares fileno() in unix.h */
  69 #  include <unix.h>
  70 #endif
  71
  72 /* Maximum value for memLevel in deflateInit2 */
  73 #ifndef MAX_MEM_LEVEL
  74 #  ifdef MAXSEG_64K
  75 #    define MAX_MEM_LEVEL 8
  76 #  else
  77 #    define MAX_MEM_LEVEL 9
  78 #  endif
  79 #endif
  80
  81 #ifndef FAR
  82 #  define FAR
  83 #endif
  84
  85 /* Maximum value for windowBits in deflateInit2 and inflateInit2 */
  86 #ifndef MAX_WBITS
  87 #  define MAX_WBITS   15 /* 32K LZ77 window */
  88 #endif
  89
  90 /* The memory requirements for deflate are (in bytes):
  91             1 << (windowBits+2)   +  1 << (memLevel+9)
  92  that is: 128K for windowBits=15  +  128K for memLevel = 8  (default values)
  93  plus a few kilobytes for small objects. For example, if you want to reduce
  94  the default memory requirements from 256K to 128K, compile with
  95      make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
  96  Of course this will generally degrade compression (there's no free lunch).
  97
  98    The memory requirements for inflate are (in bytes) 1 << windowBits
  99  that is, 32K for windowBits=15 (default value) plus a few kilobytes
 100  for small objects.
 101 */
 102
 103                         /* Type declarations */
 104
 105 #ifndef OF /* function prototypes */
 106 #  ifdef STDC
 107 #    define OF(args)  args
 108 #  else
 109 #    define OF(args)  ()
 110 #  endif
 111 #endif
 112
 113 typedef unsigned char  Byte;  /* 8 bits */
 114 typedef unsigned int   uInt;  /* 16 bits or more */
 115 typedef unsigned long  uLong; /* 32 bits or more */
 116
 117 typedef Byte FAR Bytef;
 118 typedef char FAR charf;
 119 typedef int FAR intf;
 120 typedef uInt FAR uIntf;
 121 typedef uLong FAR uLongf;
 122
 123 #ifdef STDC
 124    typedef void FAR *voidpf;
 125    typedef void     *voidp;
 126 #else
 127    typedef Byte FAR *voidpf;
 128    typedef Byte     *voidp;
 129 #endif
 130
 131 /* end of original zconf.h */
 132
 133 #define ZLIB_VERSION "0.95P"
 134
 135 /*
 136      The 'zlib' compression library provides in-memory compression and
 137   decompression functions, including integrity checks of the uncompressed
 138   data.  This version of the library supports only one compression method
 139   (deflation) but other algorithms may be added later and will have the same
 140   stream interface.
 141
 142      For compression the application must provide the output buffer and
 143   may optionally provide the input buffer for optimization. For decompression,
 144   the application must provide the input buffer and may optionally provide
 145   the output buffer for optimization.
 146
 147      Compression can be done in a single step if the buffers are large
 148   enough (for example if an input file is mmap'ed), or can be done by
 149   repeated calls of the compression function.  In the latter case, the
 150   application must provide more input and/or consume the output
 151   (providing more output space) before each call.
 152 */
 153
 154 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
 155 typedef void   (*free_func)  OF((voidpf opaque, voidpf address, uInt nbytes));
 156
 157 struct internal_state;
 158
 159 typedef struct z_stream_s {
 160     Bytef    *next_in;  /* next input byte */
 161     uInt     avail_in;  /* number of bytes available at next_in */
 162     uLong    total_in;  /* total nb of input bytes read so far */
 163
 164     Bytef    *next_out; /* next output byte should be put there */
 165     uInt     avail_out; /* remaining free space at next_out */
 166     uLong    total_out; /* total nb of bytes output so far */
 167
 168     char     *msg;      /* last error message, NULL if no error */
 169     struct internal_state FAR *state; /* not visible by applications */
 170
 171     alloc_func zalloc;  /* used to allocate the internal state */
 172     free_func  zfree;   /* used to free the internal state */
 173     voidp      opaque;  /* private data object passed to zalloc and zfree */
 174
 175     Byte     data_type; /* best guess about the data type: ascii or binary */
 176
 177 } z_stream;
 178
 179 /*
 180    The application must update next_in and avail_in when avail_in has
 181    dropped to zero. It must update next_out and avail_out when avail_out
 182    has dropped to zero. The application must initialize zalloc, zfree and
 183    opaque before calling the init function. All other fields are set by the
 184    compression library and must not be updated by the application.
 185
 186    The opaque value provided by the application will be passed as the first
 187    parameter for calls of zalloc and zfree. This can be useful for custom
 188    memory management. The compression library attaches no meaning to the
 189    opaque value.
 190
 191    zalloc must return Z_NULL if there is not enough memory for the object.
 192    On 16-bit systems, the functions zalloc and zfree must be able to allocate
 193    exactly 65536 bytes, but will not be required to allocate more than this
 194    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
 195    pointers returned by zalloc for objects of exactly 65536 bytes *must*
 196    have their offset normalized to zero. The default allocation function
 197    provided by this library ensures this (see zutil.c). To reduce memory
 198    requirements and avoid any allocation of 64K objects, at the expense of
 199    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
 200
 201    The fields total_in and total_out can be used for statistics or
 202    progress reports. After compression, total_in holds the total size of
 203    the uncompressed data and may be saved for use in the decompressor
 204    (particularly if the decompressor wants to decompress everything in
 205    a single step).
 206 */
 207
 208                         /* constants */
 209
 210 #define Z_NO_FLUSH      0
 211 #define Z_PARTIAL_FLUSH 1
 212 #define Z_FULL_FLUSH    2
 213 #define Z_SYNC_FLUSH    3 /* experimental: partial_flush + byte align */
 214 #define Z_FINISH        4
 215 #define Z_PACKET_FLUSH  5
 216 /* See deflate() below for the usage of these constants */
 217
 218 #define Z_OK            0
 219 #define Z_STREAM_END    1
 220 #define Z_ERRNO        (-1)
 221 #define Z_STREAM_ERROR (-2)
 222 #define Z_DATA_ERROR   (-3)
 223 #define Z_MEM_ERROR    (-4)
 224 #define Z_BUF_ERROR    (-5)
 225 /* error codes for the compression/decompression functions */
 226
 227 #define Z_BEST_SPEED             1
 228 #define Z_BEST_COMPRESSION       9
 229 #define Z_DEFAULT_COMPRESSION  (-1)
 230 /* compression levels */
 231
 232 #define Z_FILTERED            1
 233 #define Z_HUFFMAN_ONLY        2
 234 #define Z_DEFAULT_STRATEGY    0
 235
 236 #define Z_BINARY   0
 237 #define Z_ASCII    1
 238 #define Z_UNKNOWN  2
 239 /* Used to set the data_type field */
 240
 241 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
 242
 243 extern char *zlib_version;
 244 /* The application can compare zlib_version and ZLIB_VERSION for consistency.
 245    If the first character differs, the library code actually used is
 246    not compatible with the zlib.h header file used by the application.
 247  */
 248
 249                         /* basic functions */
 250
 251 extern int deflateInit OF((z_stream *strm, int level));
 252 /*
 253      Initializes the internal stream state for compression. The fields
 254    zalloc, zfree and opaque must be initialized before by the caller.
 255    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
 256    use default allocation functions.
 257
 258      The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
 259    1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
 260    a default compromise between speed and compression (currently equivalent
 261    to level 6).
 262
 263      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
 264    enough memory, Z_STREAM_ERROR if level is not a valid compression level.
 265    msg is set to null if there is no error message.  deflateInit does not
 266    perform any compression: this will be done by deflate().
 267 */
 268
 269
 270 extern int deflate OF((z_stream *strm, int flush));
 271 /*
 272   Performs one or both of the following actions:
 273
 274   - Compress more input starting at next_in and update next_in and avail_in
 275     accordingly. If not all input can be processed (because there is not
 276     enough room in the output buffer), next_in and avail_in are updated and
 277     processing will resume at this point for the next call of deflate().
 278
 279   - Provide more output starting at next_out and update next_out and avail_out
 280     accordingly. This action is forced if the parameter flush is non zero.
 281     Forcing flush frequently degrades the compression ratio, so this parameter
 282     should be set only when necessary (in interactive applications).
 283     Some output may be provided even if flush is not set.
 284
 285   Before the call of deflate(), the application should ensure that at least
 286   one of the actions is possible, by providing more input and/or consuming
 287   more output, and updating avail_in or avail_out accordingly; avail_out
 288   should never be zero before the call. The application can consume the
 289   compressed output when it wants, for example when the output buffer is full
 290   (avail_out == 0), or after each call of deflate().
 291
 292     If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
 293   block is terminated and flushed to the output buffer so that the
 294   decompressor can get all input data available so far. For method 9, a future
 295   variant on method 8, the current block will be flushed but not terminated.
 296   If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
 297   special marker is output and the compression dictionary is discarded; this
 298   is useful to allow the decompressor to synchronize if one compressed block
 299   has been damaged (see inflateSync below).  Flushing degrades compression and
 300   so should be used only when necessary.  Using Z_FULL_FLUSH too often can
 301   seriously degrade the compression. If deflate returns with avail_out == 0,
 302   this function must be called again with the same value of the flush
 303   parameter and more output space (updated avail_out), until the flush is
 304   complete (deflate returns with non-zero avail_out).
 305
 306     If the parameter flush is set to Z_PACKET_FLUSH, the compression
 307   block is terminated, and a zero-length stored block is output,
 308   omitting the length bytes (the effect of this is that the 3-bit type
 309   code 000 for a stored block is output, and the output is then
 310   byte-aligned).  This is designed for use at the end of a PPP packet.
 311   In addition, if the current compression block contains all the data
 312   since the last Z_PACKET_FLUSH, it is never output as a stored block.
 313   If the current compression block output as a static or dynamic block
 314   would not be at least `minCompression' bytes smaller than the
 315   original data, then nothing is output for that block.  (The type
 316   code for the zero-length stored block is still output, resulting in
 317   a single zero byte being output for the whole packet.)
 318   `MinCompression' is a parameter to deflateInit2, or 0 if deflateInit
 319   is used.
 320
 321     If the parameter flush is set to Z_FINISH, all pending input is processed,
 322   all pending output is flushed and deflate returns with Z_STREAM_END if there
 323   was enough output space; if deflate returns with Z_OK, this function must be
 324   called again with Z_FINISH and more output space (updated avail_out) but no
 325   more input data, until it returns with Z_STREAM_END or an error. After
 326   deflate has returned Z_STREAM_END, the only possible operations on the
 327   stream are deflateReset or deflateEnd.
 328
 329     Z_FINISH can be used immediately after deflateInit if all the compression
 330   is to be done in a single step. In this case, avail_out must be at least
 331   0.1% larger than avail_in plus 12 bytes.  If deflate does not return
 332   Z_STREAM_END, then it must be called again as described above.
 333
 334     deflate() may update data_type if it can make a good guess about
 335   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
 336   binary. This field is only for information purposes and does not affect
 337   the compression algorithm in any manner.
 338
 339     deflate() returns Z_OK if some progress has been made (more input
 340   processed or more output produced), Z_STREAM_END if all input has been
 341   consumed and all output has been produced (only when flush is set to
 342   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
 343   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
 344 */
 345
 346
 347 extern int deflateEnd OF((z_stream *strm));
 348 /*
 349      All dynamically allocated data structures for this stream are freed.
 350    This function discards any unprocessed input and does not flush any
 351    pending output.
 352
 353      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
 354    stream state was inconsistent. In the error case, msg may be set
 355    but then points to a static string (which must not be deallocated).
 356 */
 357
 358
 359 extern int inflateInit OF((z_stream *strm));
 360 /*
 361      Initializes the internal stream state for decompression. The fields
 362    zalloc and zfree must be initialized before by the caller.  If zalloc and
 363    zfree are set to Z_NULL, inflateInit updates them to use default allocation
 364    functions.
 365
 366      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
 367    enough memory.  msg is set to null if there is no error message.
 368    inflateInit does not perform any decompression: this will be done by
 369    inflate().
 370 */
 371
 372
 373 extern int inflate OF((z_stream *strm, int flush));
 374 /*
 375   Performs one or both of the following actions:
 376
 377   - Decompress more input starting at next_in and update next_in and avail_in
 378     accordingly. If not all input can be processed (because there is not
 379     enough room in the output buffer), next_in is updated and processing
 380     will resume at this point for the next call of inflate().
 381
 382   - Provide more output starting at next_out and update next_out and avail_out
 383     accordingly.  inflate() always provides as much output as possible
 384     (until there is no more input data or no more space in the output buffer).
 385
 386   Before the call of inflate(), the application should ensure that at least
 387   one of the actions is possible, by providing more input and/or consuming
 388   more output, and updating the next_* and avail_* values accordingly.
 389   The application can consume the uncompressed output when it wants, for
 390   example when the output buffer is full (avail_out == 0), or after each
 391   call of inflate().
 392
 393     If the parameter flush is set to Z_PARTIAL_FLUSH or Z_PACKET_FLUSH,
 394   inflate flushes as much output as possible to the output buffer. The
 395   flushing behavior of inflate is not specified for values of the flush
 396   parameter other than Z_PARTIAL_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
 397   current implementation actually flushes as much output as possible
 398   anyway.  For Z_PACKET_FLUSH, inflate checks that once all the input data
 399   has been consumed, it is expecting to see the length field of a stored
 400   block; if not, it returns Z_DATA_ERROR.
 401
 402     inflate() should normally be called until it returns Z_STREAM_END or an
 403   error. However if all decompression is to be performed in a single step
 404   (a single call of inflate), the parameter flush should be set to
 405   Z_FINISH. In this case all pending input is processed and all pending
 406   output is flushed; avail_out must be large enough to hold all the
 407   uncompressed data. (The size of the uncompressed data may have been saved
 408   by the compressor for this purpose.) The next operation on this stream must
 409   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
 410   is never required, but can be used to inform inflate that a faster routine
 411   may be used for the single inflate() call.
 412
 413     inflate() returns Z_OK if some progress has been made (more input
 414   processed or more output produced), Z_STREAM_END if the end of the
 415   compressed data has been reached and all uncompressed output has been
 416   produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
 417   the stream structure was inconsistent (for example if next_in or next_out
 418   was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
 419   progress is possible or if there was not enough room in the output buffer
 420   when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
 421   call inflateSync to look for a good compression block.  */
 422
 423
 424 extern int inflateEnd OF((z_stream *strm));
 425 /*
 426      All dynamically allocated data structures for this stream are freed.
 427    This function discards any unprocessed input and does not flush any
 428    pending output.
 429
 430      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
 431    was inconsistent. In the error case, msg may be set but then points to a
 432    static string (which must not be deallocated).
 433 */
 434
 435                         /* advanced functions */
 436
 437 /*
 438     The following functions are needed only in some special applications.
 439 */
 440
 441 extern int deflateInit2 OF((z_stream *strm,
 442                             int  level,
 443                             int  method,
 444                             int  windowBits,
 445                             int  memLevel,
 446                             int  strategy,
 447                             int  minCompression));
 448 /*
 449      This is another version of deflateInit with more compression options. The
 450    fields next_in, zalloc and zfree must be initialized before by the caller.
 451
 452      The method parameter is the compression method. It must be 8 in this
 453    version of the library. (Method 9 will allow a 64K history buffer and
 454    partial block flushes.)
 455
 456      The windowBits parameter is the base two logarithm of the window size
 457    (the size of the history buffer).  It should be in the range 8..15 for this
 458    version of the library (the value 16 will be allowed for method 9). Larger
 459    values of this parameter result in better compression at the expense of
 460    memory usage. The default value is 15 if deflateInit is used instead.
 461
 462     The memLevel parameter specifies how much memory should be allocated
 463    for the internal compression state. memLevel=1 uses minimum memory but
 464    is slow and reduces compression ratio; memLevel=9 uses maximum memory
 465    for optimal speed. The default value is 8. See zconf.h for total memory
 466    usage as a function of windowBits and memLevel.
 467
 468      The strategy parameter is used to tune the compression algorithm. Use
 469    the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
 470    produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
 471    encoding only (no string match).  Filtered data consists mostly of small
 472    values with a somewhat random distribution. In this case, the
 473    compression algorithm is tuned to compress them better. The strategy
 474    parameter only affects the compression ratio but not the correctness of
 475    the compressed output even if it is not set appropriately.
 476
 477      The minCompression parameter specifies the minimum reduction in size
 478    required for a compressed block to be output when Z_PACKET_FLUSH is
 479    used (see the description of deflate above).
 480
 481      If next_in is not null, the library will use this buffer to hold also
 482    some history information; the buffer must either hold the entire input
 483    data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
 484    is null, the library will allocate its own history buffer (and leave next_in
 485    null). next_out need not be provided here but must be provided by the
 486    application for the next call of deflate().
 487
 488      If the history buffer is provided by the application, next_in must
 489    must never be changed by the application since the compressor maintains
 490    information inside this buffer from call to call; the application
 491    must provide more input only by increasing avail_in. next_in is always
 492    reset by the library in this case.
 493
 494       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
 495    not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
 496    an invalid method). msg is set to null if there is no error message.
 497    deflateInit2 does not perform any compression: this will be done by
 498    deflate().
 499 */
 500
 501 extern int deflateCopy OF((z_stream *dest,
 502                            z_stream *source));
 503 /*
 504      Sets the destination stream as a complete copy of the source stream.  If
 505    the source stream is using an application-supplied history buffer, a new
 506    buffer is allocated for the destination stream.  The compressed output
 507    buffer is always application-supplied. It's the responsibility of the
 508    application to provide the correct values of next_out and avail_out for the
 509    next call of deflate.
 510
 511      This function is useful when several compression strategies will be
 512    tried, for example when there are several ways of pre-processing the input
 513    data with a filter. The streams that will be discarded should then be freed
 514    by calling deflateEnd.  Note that deflateCopy duplicates the internal
 515    compression state which can be quite large, so this strategy is slow and
 516    can consume lots of memory.
 517
 518       deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 519    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 520    (such as zalloc being NULL). msg is left unchanged in both source and
 521    destination.
 522 */
 523
 524 extern int deflateReset OF((z_stream *strm));
 525 /*
 526      This function is equivalent to deflateEnd followed by deflateInit,
 527    but does not free and reallocate all the internal compression state.
 528    The stream will keep the same compression level and any other attributes
 529    that may have been set by deflateInit2.
 530
 531       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 532    stream state was inconsistent (such as zalloc or state being NULL).
 533 */
 534
 535 extern int inflateInit2 OF((z_stream *strm,
 536                             int  windowBits));
 537 /*
 538      This is another version of inflateInit with more compression options. The
 539    fields next_out, zalloc and zfree must be initialized before by the caller.
 540
 541      The windowBits parameter is the base two logarithm of the maximum window
 542    size (the size of the history buffer).  It should be in the range 8..15 for
 543    this version of the library (the value 16 will be allowed soon). The
 544    default value is 15 if inflateInit is used instead. If a compressed stream
 545    with a larger window size is given as input, inflate() will return with
 546    the error code Z_DATA_ERROR instead of trying to allocate a larger window.
 547
 548      If next_out is not null, the library will use this buffer for the history
 549    buffer; the buffer must either be large enough to hold the entire output
 550    data, or have at least 1<<windowBits bytes.  If next_out is null, the
 551    library will allocate its own buffer (and leave next_out null). next_in
 552    need not be provided here but must be provided by the application for the
 553    next call of inflate().
 554
 555      If the history buffer is provided by the application, next_out must
 556    never be changed by the application since the decompressor maintains
 557    history information inside this buffer from call to call; the application
 558    can only reset next_out to the beginning of the history buffer when
 559    avail_out is zero and all output has been consumed.
 560
 561       inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
 562    not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
 563    windowBits < 8). msg is set to null if there is no error message.
 564    inflateInit2 does not perform any decompression: this will be done by
 565    inflate().
 566 */
 567
 568 extern int inflateSync OF((z_stream *strm));
 569 /*
 570     Skips invalid compressed data until the special marker (see deflate()
 571   above) can be found, or until all available input is skipped. No output
 572   is provided.
 573
 574     inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
 575   if no more input was provided, Z_DATA_ERROR if no marker has been found,
 576   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
 577   case, the application may save the current current value of total_in which
 578   indicates where valid compressed data was found. In the error case, the
 579   application may repeatedly call inflateSync, providing more input each time,
 580   until success or end of the input data.
 581 */
 582
 583 extern int inflateReset OF((z_stream *strm));
 584 /*
 585      This function is equivalent to inflateEnd followed by inflateInit,
 586    but does not free and reallocate all the internal decompression state.
 587    The stream will keep attributes that may have been set by inflateInit2.
 588
 589       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 590    stream state was inconsistent (such as zalloc or state being NULL).
 591 */
 592
 593 extern int inflateIncomp OF((z_stream *strm));
 594 /*
 595      This function adds the data at next_in (avail_in bytes) to the output
 596    history without performing any output.  There must be no pending output,
 597    and the decompressor must be expecting to see the start of a block.
 598    Calling this function is equivalent to decompressing a stored block
 599    containing the data at next_in (except that the data is not output).
 600 */
 601
 602                         /* checksum functions */
 603
 604 /*
 605      This function is not related to compression but is exported
 606    anyway because it might be useful in applications using the
 607    compression library.
 608 */
 609
 610 extern uLong adler32 OF((uLong adler, Bytef *buf, uInt len));
 611
 612 /*
 613      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
 614    return the updated checksum. If buf is NULL, this function returns
 615    the required initial value for the checksum.
 616    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
 617    much faster. Usage example:
 618
 619      uLong adler = adler32(0L, Z_NULL, 0);
 620
 621      while (read_buffer(buffer, length) != EOF) {
 622        adler = adler32(adler, buffer, length);
 623      }
 624      if (adler != original_adler) error();
 625 */
 626
 627 #ifndef _Z_UTIL_H
 628     struct internal_state {int dummy;}; /* hack for buggy compilers */
 629 #endif
 630
 631 #endif /* _ZLIB_H */