akaros/kern/include/zlib.h
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   1/* zlib.h -- interface of the 'zlib' general purpose compression library
   2
   3  Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
   4
   5  This software is provided 'as-is', without any express or implied
   6  warranty.  In no event will the authors be held liable for any damages
   7  arising from the use of this software.
   8
   9  Permission is granted to anyone to use this software for any purpose,
  10  including commercial applications, and to alter it and redistribute it
  11  freely, subject to the following restrictions:
  12
  13  1. The origin of this software must not be misrepresented; you must not
  14     claim that you wrote the original software. If you use this software
  15     in a product, an acknowledgment in the product documentation would be
  16     appreciated but is not required.
  17  2. Altered source versions must be plainly marked as such, and must not be
  18     misrepresented as being the original software.
  19  3. This notice may not be removed or altered from any source distribution.
  20
  21  Jean-loup Gailly        Mark Adler
  22  jloup@gzip.org          madler@alumni.caltech.edu
  23
  24
  25  The data format used by the zlib library is described by RFCs (Request for
  26  Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
  27  (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
  28*/
  29
  30#pragma once
  31
  32#include <zconf.h>
  33
  34/* zlib deflate based on ZLIB_VERSION "1.1.3" */
  35/* zlib inflate based on ZLIB_VERSION "1.2.3" */
  36
  37/*
  38  This is a modified version of zlib for use inside the Linux kernel.
  39  The main changes are to perform all memory allocation in advance.
  40
  41  Inflation Changes:
  42    * Z_PACKET_FLUSH is added and used by ppp_deflate. Before returning
  43      this checks there is no more input data available and the next data
  44      is a STORED block. It also resets the mode to be read for the next
  45      data, all as per PPP requirements.
  46    * Addition of zlib_inflateIncomp which copies incompressible data into
  47      the history window and adjusts the accoutning without calling
  48      zlib_inflate itself to inflate the data.
  49*/
  50
  51/*
  52     The 'zlib' compression library provides in-memory compression and
  53  decompression functions, including integrity checks of the uncompressed
  54  data.  This version of the library supports only one compression method
  55  (deflation) but other algorithms will be added later and will have the same
  56  stream interface.
  57
  58     Compression can be done in a single step if the buffers are large
  59  enough (for example if an input file is mmap'ed), or can be done by
  60  repeated calls of the compression function.  In the latter case, the
  61  application must provide more input and/or consume the output
  62  (providing more output space) before each call.
  63
  64     The compressed data format used by default by the in-memory functions is
  65  the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
  66  around a deflate stream, which is itself documented in RFC 1951.
  67
  68     The library also supports reading and writing files in gzip (.gz) format
  69  with an interface similar to that of stdio.
  70
  71     The zlib format was designed to be compact and fast for use in memory
  72  and on communications channels.  The gzip format was designed for single-
  73  file compression on file systems, has a larger header than zlib to maintain
  74  directory information, and uses a different, slower check method than zlib.
  75
  76     The library does not install any signal handler. The decoder checks
  77  the consistency of the compressed data, so the library should never
  78  crash even in case of corrupted input.
  79*/
  80
  81struct internal_state;
  82
  83typedef struct z_stream_s {
  84    const Byte *next_in;   /* next input byte */
  85        uLong avail_in;  /* number of bytes available at next_in */
  86    uLong    total_in;  /* total nb of input bytes read so far */
  87
  88    Byte    *next_out;  /* next output byte should be put there */
  89        uLong avail_out; /* remaining free space at next_out */
  90    uLong    total_out; /* total nb of bytes output so far */
  91
  92    char     *msg;      /* last error message, NULL if no error */
  93    struct internal_state *state; /* not visible by applications */
  94
  95    void     *workspace; /* memory allocated for this stream */
  96
  97    int     data_type;  /* best guess about the data type: ascii or binary */
  98    uLong   adler;      /* adler32 value of the uncompressed data */
  99    uLong   reserved;   /* reserved for future use */
 100} z_stream;
 101
 102typedef z_stream *z_streamp;
 103
 104/*
 105   The application must update next_in and avail_in when avail_in has
 106   dropped to zero. It must update next_out and avail_out when avail_out
 107   has dropped to zero. The application must initialize zalloc, zfree and
 108   opaque before calling the init function. All other fields are set by the
 109   compression library and must not be updated by the application.
 110
 111   The opaque value provided by the application will be passed as the first
 112   parameter for calls of zalloc and zfree. This can be useful for custom
 113   memory management. The compression library attaches no meaning to the
 114   opaque value.
 115
 116   zalloc must return NULL if there is not enough memory for the object.
 117   If zlib is used in a multi-threaded application, zalloc and zfree must be
 118   thread safe.
 119
 120   On 16-bit systems, the functions zalloc and zfree must be able to allocate
 121   exactly 65536 bytes, but will not be required to allocate more than this
 122   if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
 123   pointers returned by zalloc for objects of exactly 65536 bytes *must*
 124   have their offset normalized to zero. The default allocation function
 125   provided by this library ensures this (see zutil.c). To reduce memory
 126   requirements and avoid any allocation of 64K objects, at the expense of
 127   compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
 128
 129   The fields total_in and total_out can be used for statistics or
 130   progress reports. After compression, total_in holds the total size of
 131   the uncompressed data and may be saved for use in the decompressor
 132   (particularly if the decompressor wants to decompress everything in
 133   a single step).
 134*/
 135
 136                        /* constants */
 137
 138#define Z_NO_FLUSH      0
 139#define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
 140#define Z_PACKET_FLUSH  2
 141#define Z_SYNC_FLUSH    3
 142#define Z_FULL_FLUSH    4
 143#define Z_FINISH        5
 144#define Z_BLOCK         6 /* Only for inflate at present */
 145/* Allowed flush values; see deflate() and inflate() below for details */
 146
 147#define Z_OK            0
 148#define Z_STREAM_END    1
 149#define Z_NEED_DICT     2
 150#define Z_ERRNO        (-1)
 151#define Z_STREAM_ERROR (-2)
 152#define Z_DATA_ERROR   (-3)
 153#define Z_MEM_ERROR    (-4)
 154#define Z_BUF_ERROR    (-5)
 155#define Z_VERSION_ERROR (-6)
 156/* Return codes for the compression/decompression functions. Negative
 157 * values are errors, positive values are used for special but normal events.
 158 */
 159
 160#define Z_NO_COMPRESSION         0
 161#define Z_BEST_SPEED             1
 162#define Z_BEST_COMPRESSION       9
 163#define Z_DEFAULT_COMPRESSION  (-1)
 164/* compression levels */
 165
 166#define Z_FILTERED            1
 167#define Z_HUFFMAN_ONLY        2
 168#define Z_DEFAULT_STRATEGY    0
 169/* compression strategy; see deflateInit2() below for details */
 170
 171#define Z_BINARY   0
 172#define Z_ASCII    1
 173#define Z_UNKNOWN  2
 174/* Possible values of the data_type field */
 175
 176#define Z_DEFLATED   8
 177/* The deflate compression method (the only one supported in this version) */
 178
 179                        /* basic functions */
 180
 181extern int zlib_deflate_workspacesize (int windowBits, int memLevel);
 182/*
 183   Returns the number of bytes that needs to be allocated for a per-
 184   stream workspace with the specified parameters.  A pointer to this
 185   number of bytes should be returned in stream->workspace before
 186   you call zlib_deflateInit() or zlib_deflateInit2().  If you call
 187   zlib_deflateInit(), specify windowBits = MAX_WBITS and memLevel =
 188   MAX_MEM_LEVEL here.  If you call zlib_deflateInit2(), the windowBits
 189   and memLevel parameters passed to zlib_deflateInit2() must not
 190   exceed those passed here.
 191*/
 192
 193/*
 194extern int deflateInit (z_streamp strm, int level);
 195
 196     Initializes the internal stream state for compression. The fields
 197   zalloc, zfree and opaque must be initialized before by the caller.
 198   If zalloc and zfree are set to NULL, deflateInit updates them to
 199   use default allocation functions.
 200
 201     The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
 202   1 gives best speed, 9 gives best compression, 0 gives no compression at
 203   all (the input data is simply copied a block at a time).
 204   Z_DEFAULT_COMPRESSION requests a default compromise between speed and
 205   compression (currently equivalent to level 6).
 206
 207     deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
 208   enough memory, Z_STREAM_ERROR if level is not a valid compression level,
 209   Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
 210   with the version assumed by the caller (ZLIB_VERSION).
 211   msg is set to null if there is no error message.  deflateInit does not
 212   perform any compression: this will be done by deflate().
 213*/
 214
 215
 216extern int zlib_deflate (z_streamp strm, int flush);
 217/*
 218    deflate compresses as much data as possible, and stops when the input
 219  buffer becomes empty or the output buffer becomes full. It may introduce some
 220  output latency (reading input without producing any output) except when
 221  forced to flush.
 222
 223    The detailed semantics are as follows. deflate performs one or both of the
 224  following actions:
 225
 226  - Compress more input starting at next_in and update next_in and avail_in
 227    accordingly. If not all input can be processed (because there is not
 228    enough room in the output buffer), next_in and avail_in are updated and
 229    processing will resume at this point for the next call of deflate().
 230
 231  - Provide more output starting at next_out and update next_out and avail_out
 232    accordingly. This action is forced if the parameter flush is non zero.
 233    Forcing flush frequently degrades the compression ratio, so this parameter
 234    should be set only when necessary (in interactive applications).
 235    Some output may be provided even if flush is not set.
 236
 237  Before the call of deflate(), the application should ensure that at least
 238  one of the actions is possible, by providing more input and/or consuming
 239  more output, and updating avail_in or avail_out accordingly; avail_out
 240  should never be zero before the call. The application can consume the
 241  compressed output when it wants, for example when the output buffer is full
 242  (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
 243  and with zero avail_out, it must be called again after making room in the
 244  output buffer because there might be more output pending.
 245
 246    If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
 247  flushed to the output buffer and the output is aligned on a byte boundary, so
 248  that the decompressor can get all input data available so far. (In particular
 249  avail_in is zero after the call if enough output space has been provided
 250  before the call.)  Flushing may degrade compression for some compression
 251  algorithms and so it should be used only when necessary.
 252
 253    If flush is set to Z_FULL_FLUSH, all output is flushed as with
 254  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
 255  restart from this point if previous compressed data has been damaged or if
 256  random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
 257  the compression.
 258
 259    If deflate returns with avail_out == 0, this function must be called again
 260  with the same value of the flush parameter and more output space (updated
 261  avail_out), until the flush is complete (deflate returns with non-zero
 262  avail_out).
 263
 264    If the parameter flush is set to Z_FINISH, pending input is processed,
 265  pending output is flushed and deflate returns with Z_STREAM_END if there
 266  was enough output space; if deflate returns with Z_OK, this function must be
 267  called again with Z_FINISH and more output space (updated avail_out) but no
 268  more input data, until it returns with Z_STREAM_END or an error. After
 269  deflate has returned Z_STREAM_END, the only possible operations on the
 270  stream are deflateReset or deflateEnd.
 271
 272    Z_FINISH can be used immediately after deflateInit if all the compression
 273  is to be done in a single step. In this case, avail_out must be at least
 274  0.1% larger than avail_in plus 12 bytes.  If deflate does not return
 275  Z_STREAM_END, then it must be called again as described above.
 276
 277    deflate() sets strm->adler to the adler32 checksum of all input read
 278  so far (that is, total_in bytes).
 279
 280    deflate() may update data_type if it can make a good guess about
 281  the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
 282  binary. This field is only for information purposes and does not affect
 283  the compression algorithm in any manner.
 284
 285    deflate() returns Z_OK if some progress has been made (more input
 286  processed or more output produced), Z_STREAM_END if all input has been
 287  consumed and all output has been produced (only when flush is set to
 288  Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
 289  if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
 290  (for example avail_in or avail_out was zero).
 291*/
 292
 293
 294extern int zlib_deflateEnd (z_streamp strm);
 295/*
 296     All dynamically allocated data structures for this stream are freed.
 297   This function discards any unprocessed input and does not flush any
 298   pending output.
 299
 300     deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
 301   stream state was inconsistent, Z_DATA_ERROR if the stream was freed
 302   prematurely (some input or output was discarded). In the error case,
 303   msg may be set but then points to a static string (which must not be
 304   deallocated).
 305*/
 306
 307
 308extern int zlib_inflate_workspacesize (void);
 309/*
 310   Returns the number of bytes that needs to be allocated for a per-
 311   stream workspace.  A pointer to this number of bytes should be
 312   returned in stream->workspace before calling zlib_inflateInit().
 313*/
 314
 315/*
 316extern int zlib_inflateInit (z_streamp strm);
 317
 318     Initializes the internal stream state for decompression. The fields
 319   next_in, avail_in, and workspace must be initialized before by
 320   the caller. If next_in is not NULL and avail_in is large enough (the exact
 321   value depends on the compression method), inflateInit determines the
 322   compression method from the zlib header and allocates all data structures
 323   accordingly; otherwise the allocation will be deferred to the first call of
 324   inflate.  If zalloc and zfree are set to NULL, inflateInit updates them to
 325   use default allocation functions.
 326
 327     inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
 328   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 329   version assumed by the caller.  msg is set to null if there is no error
 330   message. inflateInit does not perform any decompression apart from reading
 331   the zlib header if present: this will be done by inflate().  (So next_in and
 332   avail_in may be modified, but next_out and avail_out are unchanged.)
 333*/
 334
 335
 336extern int zlib_inflate (z_streamp strm, int flush);
 337/*
 338    inflate decompresses as much data as possible, and stops when the input
 339  buffer becomes empty or the output buffer becomes full. It may introduce
 340  some output latency (reading input without producing any output) except when
 341  forced to flush.
 342
 343  The detailed semantics are as follows. inflate performs one or both of the
 344  following actions:
 345
 346  - Decompress more input starting at next_in and update next_in and avail_in
 347    accordingly. If not all input can be processed (because there is not
 348    enough room in the output buffer), next_in is updated and processing
 349    will resume at this point for the next call of inflate().
 350
 351  - Provide more output starting at next_out and update next_out and avail_out
 352    accordingly.  inflate() provides as much output as possible, until there
 353    is no more input data or no more space in the output buffer (see below
 354    about the flush parameter).
 355
 356  Before the call of inflate(), the application should ensure that at least
 357  one of the actions is possible, by providing more input and/or consuming
 358  more output, and updating the next_* and avail_* values accordingly.
 359  The application can consume the uncompressed output when it wants, for
 360  example when the output buffer is full (avail_out == 0), or after each
 361  call of inflate(). If inflate returns Z_OK and with zero avail_out, it
 362  must be called again after making room in the output buffer because there
 363  might be more output pending.
 364
 365    The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
 366  Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
 367  output as possible to the output buffer. Z_BLOCK requests that inflate() stop
 368  if and when it gets to the next deflate block boundary. When decoding the
 369  zlib or gzip format, this will cause inflate() to return immediately after
 370  the header and before the first block. When doing a raw inflate, inflate()
 371  will go ahead and process the first block, and will return when it gets to
 372  the end of that block, or when it runs out of data.
 373
 374    The Z_BLOCK option assists in appending to or combining deflate streams.
 375  Also to assist in this, on return inflate() will set strm->data_type to the
 376  number of unused bits in the last byte taken from strm->next_in, plus 64
 377  if inflate() is currently decoding the last block in the deflate stream,
 378  plus 128 if inflate() returned immediately after decoding an end-of-block
 379  code or decoding the complete header up to just before the first byte of the
 380  deflate stream. The end-of-block will not be indicated until all of the
 381  uncompressed data from that block has been written to strm->next_out.  The
 382  number of unused bits may in general be greater than seven, except when
 383  bit 7 of data_type is set, in which case the number of unused bits will be
 384  less than eight.
 385
 386    inflate() should normally be called until it returns Z_STREAM_END or an
 387  error. However if all decompression is to be performed in a single step
 388  (a single call of inflate), the parameter flush should be set to
 389  Z_FINISH. In this case all pending input is processed and all pending
 390  output is flushed; avail_out must be large enough to hold all the
 391  uncompressed data. (The size of the uncompressed data may have been saved
 392  by the compressor for this purpose.) The next operation on this stream must
 393  be inflateEnd to deallocate the decompression state. The use of Z_FINISH
 394  is never required, but can be used to inform inflate that a faster approach
 395  may be used for the single inflate() call.
 396
 397     In this implementation, inflate() always flushes as much output as
 398  possible to the output buffer, and always uses the faster approach on the
 399  first call. So the only effect of the flush parameter in this implementation
 400  is on the return value of inflate(), as noted below, or when it returns early
 401  because Z_BLOCK is used.
 402
 403     If a preset dictionary is needed after this call (see inflateSetDictionary
 404  below), inflate sets strm->adler to the adler32 checksum of the dictionary
 405  chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
 406  strm->adler to the adler32 checksum of all output produced so far (that is,
 407  total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
 408  below. At the end of the stream, inflate() checks that its computed adler32
 409  checksum is equal to that saved by the compressor and returns Z_STREAM_END
 410  only if the checksum is correct.
 411
 412    inflate() will decompress and check either zlib-wrapped or gzip-wrapped
 413  deflate data.  The header type is detected automatically.  Any information
 414  contained in the gzip header is not retained, so applications that need that
 415  information should instead use raw inflate, see inflateInit2() below, or
 416  inflateBack() and perform their own processing of the gzip header and
 417  trailer.
 418
 419    inflate() returns Z_OK if some progress has been made (more input processed
 420  or more output produced), Z_STREAM_END if the end of the compressed data has
 421  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
 422  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
 423  corrupted (input stream not conforming to the zlib format or incorrect check
 424  value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
 425  if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
 426  Z_BUF_ERROR if no progress is possible or if there was not enough room in the
 427  output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
 428  inflate() can be called again with more input and more output space to
 429  continue decompressing. If Z_DATA_ERROR is returned, the application may then
 430  call inflateSync() to look for a good compression block if a partial recovery
 431  of the data is desired.
 432*/
 433
 434
 435extern int zlib_inflateEnd (z_streamp strm);
 436/*
 437     All dynamically allocated data structures for this stream are freed.
 438   This function discards any unprocessed input and does not flush any
 439   pending output.
 440
 441     inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
 442   was inconsistent. In the error case, msg may be set but then points to a
 443   static string (which must not be deallocated).
 444*/
 445
 446                        /* Advanced functions */
 447
 448/*
 449    The following functions are needed only in some special applications.
 450*/
 451
 452/*
 453extern int deflateInit2 (z_streamp strm,
 454                                     int  level,
 455                                     int  method,
 456                                     int  windowBits,
 457                                     int  memLevel,
 458                                     int  strategy);
 459
 460     This is another version of deflateInit with more compression options. The
 461   fields next_in, zalloc, zfree and opaque must be initialized before by
 462   the caller.
 463
 464     The method parameter is the compression method. It must be Z_DEFLATED in
 465   this version of the library.
 466
 467     The windowBits parameter is the base two logarithm of the window size
 468   (the size of the history buffer).  It should be in the range 8..15 for this
 469   version of the library. Larger values of this parameter result in better
 470   compression at the expense of memory usage. The default value is 15 if
 471   deflateInit is used instead.
 472
 473     The memLevel parameter specifies how much memory should be allocated
 474   for the internal compression state. memLevel=1 uses minimum memory but
 475   is slow and reduces compression ratio; memLevel=9 uses maximum memory
 476   for optimal speed. The default value is 8. See zconf.h for total memory
 477   usage as a function of windowBits and memLevel.
 478
 479     The strategy parameter is used to tune the compression algorithm. Use the
 480   value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
 481   filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
 482   string match).  Filtered data consists mostly of small values with a
 483   somewhat random distribution. In this case, the compression algorithm is
 484   tuned to compress them better. The effect of Z_FILTERED is to force more
 485   Huffman coding and less string matching; it is somewhat intermediate
 486   between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
 487   the compression ratio but not the correctness of the compressed output even
 488   if it is not set appropriately.
 489
 490      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 491   memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
 492   method). msg is set to null if there is no error message.  deflateInit2 does
 493   not perform any compression: this will be done by deflate().
 494*/
 495
 496extern int zlib_deflateReset (z_streamp strm);
 497/*
 498     This function is equivalent to deflateEnd followed by deflateInit,
 499   but does not free and reallocate all the internal compression state.
 500   The stream will keep the same compression level and any other attributes
 501   that may have been set by deflateInit2.
 502
 503      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 504   stream state was inconsistent (such as zalloc or state being NULL).
 505*/
 506
 507static inline unsigned long deflateBound(unsigned long s)
 508{
 509        return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11;
 510}
 511
 512/*
 513extern int inflateInit2 (z_streamp strm, int  windowBits);
 514
 515     This is another version of inflateInit with an extra parameter. The
 516   fields next_in, avail_in, zalloc, zfree and opaque must be initialized
 517   before by the caller.
 518
 519     The windowBits parameter is the base two logarithm of the maximum window
 520   size (the size of the history buffer).  It should be in the range 8..15 for
 521   this version of the library. The default value is 15 if inflateInit is used
 522   instead. windowBits must be greater than or equal to the windowBits value
 523   provided to deflateInit2() while compressing, or it must be equal to 15 if
 524   deflateInit2() was not used. If a compressed stream with a larger window
 525   size is given as input, inflate() will return with the error code
 526   Z_DATA_ERROR instead of trying to allocate a larger window.
 527
 528     windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
 529   determines the window size. inflate() will then process raw deflate data,
 530   not looking for a zlib or gzip header, not generating a check value, and not
 531   looking for any check values for comparison at the end of the stream. This
 532   is for use with other formats that use the deflate compressed data format
 533   such as zip.  Those formats provide their own check values. If a custom
 534   format is developed using the raw deflate format for compressed data, it is
 535   recommended that a check value such as an adler32 or a crc32 be applied to
 536   the uncompressed data as is done in the zlib, gzip, and zip formats.  For
 537   most applications, the zlib format should be used as is. Note that comments
 538   above on the use in deflateInit2() applies to the magnitude of windowBits.
 539
 540     windowBits can also be greater than 15 for optional gzip decoding. Add
 541   32 to windowBits to enable zlib and gzip decoding with automatic header
 542   detection, or add 16 to decode only the gzip format (the zlib format will
 543   return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is
 544   a crc32 instead of an adler32.
 545
 546     inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 547   memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
 548   is set to null if there is no error message.  inflateInit2 does not perform
 549   any decompression apart from reading the zlib header if present: this will
 550   be done by inflate(). (So next_in and avail_in may be modified, but next_out
 551   and avail_out are unchanged.)
 552*/
 553
 554extern int zlib_inflateReset (z_streamp strm);
 555/*
 556     This function is equivalent to inflateEnd followed by inflateInit,
 557   but does not free and reallocate all the internal decompression state.
 558   The stream will keep attributes that may have been set by inflateInit2.
 559
 560      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 561   stream state was inconsistent (such as zalloc or state being NULL).
 562*/
 563
 564extern int zlib_inflateIncomp (z_stream *strm);
 565/*
 566     This function adds the data at next_in (avail_in bytes) to the output
 567   history without performing any output.  There must be no pending output,
 568   and the decompressor must be expecting to see the start of a block.
 569   Calling this function is equivalent to decompressing a stored block
 570   containing the data at next_in (except that the data is not output).
 571*/
 572
 573#define zlib_deflateInit(strm, level) \
 574        zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \
 575                              DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
 576#define zlib_inflateInit(strm) \
 577        zlib_inflateInit2((strm), DEF_WBITS)
 578
 579extern int zlib_deflateInit2(z_streamp strm, int  level, int  method,
 580                                      int windowBits, int memLevel,
 581                                      int strategy);
 582extern int zlib_inflateInit2(z_streamp strm, int  windowBits);
 583
 584#if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
 585    struct internal_state {int dummy;}; /* hack for buggy compilers */
 586#endif
 587
 588/* Utility function: initialize zlib, unpack binary blob, clean up zlib,
 589 * return len or negative error code. */
 590extern int zlib_inflate_blob(void *dst, unsigned dst_sz, const void *src, unsigned src_sz);
 591