1 /*
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  24 
  25 /* zlib.h -- interface of the 'zlib' general purpose compression library
  26   version 1.2.13, October 13th, 2022
  27 
  28   Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler
  29 
  30   This software is provided 'as-is', without any express or implied
  31   warranty.  In no event will the authors be held liable for any damages
  32   arising from the use of this software.
  33 
  34   Permission is granted to anyone to use this software for any purpose,
  35   including commercial applications, and to alter it and redistribute it
  36   freely, subject to the following restrictions:
  37 
  38   1. The origin of this software must not be misrepresented; you must not
  39      claim that you wrote the original software. If you use this software
  40      in a product, an acknowledgment in the product documentation would be
  41      appreciated but is not required.
  42   2. Altered source versions must be plainly marked as such, and must not be
  43      misrepresented as being the original software.
  44   3. This notice may not be removed or altered from any source distribution.
  45 
  46   Jean-loup Gailly        Mark Adler
  47   jloup@gzip.org          madler@alumni.caltech.edu
  48 
  49 
  50   The data format used by the zlib library is described by RFCs (Request for
  51   Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
  52   (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
  53 */
  54 
  55 #ifndef ZLIB_H
  56 #define ZLIB_H
  57 
  58 #include "zconf.h"
  59 
  60 #ifdef __cplusplus
  61 extern "C" {
  62 #endif
  63 
  64 #define ZLIB_VERSION "1.2.13"
  65 #define ZLIB_VERNUM 0x12d0
  66 #define ZLIB_VER_MAJOR 1
  67 #define ZLIB_VER_MINOR 2
  68 #define ZLIB_VER_REVISION 13
  69 #define ZLIB_VER_SUBREVISION 0
  70 
  71 /*
  72     The 'zlib' compression library provides in-memory compression and
  73   decompression functions, including integrity checks of the uncompressed data.
  74   This version of the library supports only one compression method (deflation)
  75   but other algorithms will be added later and will have the same stream
  76   interface.
  77 
  78     Compression can be done in a single step if the buffers are large enough,
  79   or can be done by repeated calls of the compression function.  In the latter
  80   case, the application must provide more input and/or consume the output
  81   (providing more output space) before each call.
  82 
  83     The compressed data format used by default by the in-memory functions is
  84   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
  85   around a deflate stream, which is itself documented in RFC 1951.
  86 
  87     The library also supports reading and writing files in gzip (.gz) format
  88   with an interface similar to that of stdio using the functions that start
  89   with "gz".  The gzip format is different from the zlib format.  gzip is a
  90   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
  91 
  92     This library can optionally read and write gzip and raw deflate streams in
  93   memory as well.
  94 
  95     The zlib format was designed to be compact and fast for use in memory
  96   and on communications channels.  The gzip format was designed for single-
  97   file compression on file systems, has a larger header than zlib to maintain
  98   directory information, and uses a different, slower check method than zlib.
  99 
 100     The library does not install any signal handler.  The decoder checks
 101   the consistency of the compressed data, so the library should never crash
 102   even in the case of corrupted input.
 103 */
 104 
 105 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
 106 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
 107 
 108 struct internal_state;
 109 
 110 typedef struct z_stream_s {
 111     z_const Bytef *next_in;     /* next input byte */
 112     uInt     avail_in;  /* number of bytes available at next_in */
 113     uLong    total_in;  /* total number of input bytes read so far */
 114 
 115     Bytef    *next_out; /* next output byte will go here */
 116     uInt     avail_out; /* remaining free space at next_out */
 117     uLong    total_out; /* total number of bytes output so far */
 118 
 119     z_const char *msg;  /* last error message, NULL if no error */
 120     struct internal_state FAR *state; /* not visible by applications */
 121 
 122     alloc_func zalloc;  /* used to allocate the internal state */
 123     free_func  zfree;   /* used to free the internal state */
 124     voidpf     opaque;  /* private data object passed to zalloc and zfree */
 125 
 126     int     data_type;  /* best guess about the data type: binary or text
 127                            for deflate, or the decoding state for inflate */
 128     uLong   adler;      /* Adler-32 or CRC-32 value of the uncompressed data */
 129     uLong   reserved;   /* reserved for future use */
 130 } z_stream;
 131 
 132 typedef z_stream FAR *z_streamp;
 133 
 134 /*
 135      gzip header information passed to and from zlib routines.  See RFC 1952
 136   for more details on the meanings of these fields.
 137 */
 138 typedef struct gz_header_s {
 139     int     text;       /* true if compressed data believed to be text */
 140     uLong   time;       /* modification time */
 141     int     xflags;     /* extra flags (not used when writing a gzip file) */
 142     int     os;         /* operating system */
 143     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
 144     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
 145     uInt    extra_max;  /* space at extra (only when reading header) */
 146     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
 147     uInt    name_max;   /* space at name (only when reading header) */
 148     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
 149     uInt    comm_max;   /* space at comment (only when reading header) */
 150     int     hcrc;       /* true if there was or will be a header crc */
 151     int     done;       /* true when done reading gzip header (not used
 152                            when writing a gzip file) */
 153 } gz_header;
 154 
 155 typedef gz_header FAR *gz_headerp;
 156 
 157 /*
 158      The application must update next_in and avail_in when avail_in has dropped
 159    to zero.  It must update next_out and avail_out when avail_out has dropped
 160    to zero.  The application must initialize zalloc, zfree and opaque before
 161    calling the init function.  All other fields are set by the compression
 162    library and must not be updated by the application.
 163 
 164      The opaque value provided by the application will be passed as the first
 165    parameter for calls of zalloc and zfree.  This can be useful for custom
 166    memory management.  The compression library attaches no meaning to the
 167    opaque value.
 168 
 169      zalloc must return Z_NULL if there is not enough memory for the object.
 170    If zlib is used in a multi-threaded application, zalloc and zfree must be
 171    thread safe.  In that case, zlib is thread-safe.  When zalloc and zfree are
 172    Z_NULL on entry to the initialization function, they are set to internal
 173    routines that use the standard library functions malloc() and free().
 174 
 175      On 16-bit systems, the functions zalloc and zfree must be able to allocate
 176    exactly 65536 bytes, but will not be required to allocate more than this if
 177    the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
 178    returned by zalloc for objects of exactly 65536 bytes *must* have their
 179    offset normalized to zero.  The default allocation function provided by this
 180    library ensures this (see zutil.c).  To reduce memory requirements and avoid
 181    any allocation of 64K objects, at the expense of compression ratio, compile
 182    the library with -DMAX_WBITS=14 (see zconf.h).
 183 
 184      The fields total_in and total_out can be used for statistics or progress
 185    reports.  After compression, total_in holds the total size of the
 186    uncompressed data and may be saved for use by the decompressor (particularly
 187    if the decompressor wants to decompress everything in a single step).
 188 */
 189 
 190                         /* constants */
 191 
 192 #define Z_NO_FLUSH      0
 193 #define Z_PARTIAL_FLUSH 1
 194 #define Z_SYNC_FLUSH    2
 195 #define Z_FULL_FLUSH    3
 196 #define Z_FINISH        4
 197 #define Z_BLOCK         5
 198 #define Z_TREES         6
 199 /* Allowed flush values; see deflate() and inflate() below for details */
 200 
 201 #define Z_OK            0
 202 #define Z_STREAM_END    1
 203 #define Z_NEED_DICT     2
 204 #define Z_ERRNO        (-1)
 205 #define Z_STREAM_ERROR (-2)
 206 #define Z_DATA_ERROR   (-3)
 207 #define Z_MEM_ERROR    (-4)
 208 #define Z_BUF_ERROR    (-5)
 209 #define Z_VERSION_ERROR (-6)
 210 /* Return codes for the compression/decompression functions. Negative values
 211  * are errors, positive values are used for special but normal events.
 212  */
 213 
 214 #define Z_NO_COMPRESSION         0
 215 #define Z_BEST_SPEED             1
 216 #define Z_BEST_COMPRESSION       9
 217 #define Z_DEFAULT_COMPRESSION  (-1)
 218 /* compression levels */
 219 
 220 #define Z_FILTERED            1
 221 #define Z_HUFFMAN_ONLY        2
 222 #define Z_RLE                 3
 223 #define Z_FIXED               4
 224 #define Z_DEFAULT_STRATEGY    0
 225 /* compression strategy; see deflateInit2() below for details */
 226 
 227 #define Z_BINARY   0
 228 #define Z_TEXT     1
 229 #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
 230 #define Z_UNKNOWN  2
 231 /* Possible values of the data_type field for deflate() */
 232 
 233 #define Z_DEFLATED   8
 234 /* The deflate compression method (the only one supported in this version) */
 235 
 236 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
 237 
 238 #define zlib_version zlibVersion()
 239 /* for compatibility with versions < 1.0.2 */
 240 
 241 
 242                         /* basic functions */
 243 
 244 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
 245 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
 246    If the first character differs, the library code actually used is not
 247    compatible with the zlib.h header file used by the application.  This check
 248    is automatically made by deflateInit and inflateInit.
 249  */
 250 
 251 /*
 252 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
 253 
 254      Initializes the internal stream state for compression.  The fields
 255    zalloc, zfree and opaque must be initialized before by the caller.  If
 256    zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
 257    allocation functions.
 258 
 259      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
 260    1 gives best speed, 9 gives best compression, 0 gives no compression at all
 261    (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
 262    requests a default compromise between speed and compression (currently
 263    equivalent to level 6).
 264 
 265      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
 266    memory, Z_STREAM_ERROR if level is not a valid compression level, or
 267    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
 268    with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
 269    if there is no error message.  deflateInit does not perform any compression:
 270    this will be done by deflate().
 271 */
 272 
 273 
 274 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
 275 /*
 276     deflate compresses as much data as possible, and stops when the input
 277   buffer becomes empty or the output buffer becomes full.  It may introduce
 278   some output latency (reading input without producing any output) except when
 279   forced to flush.
 280 
 281     The detailed semantics are as follows.  deflate performs one or both of the
 282   following actions:
 283 
 284   - Compress more input starting at next_in and update next_in and avail_in
 285     accordingly.  If not all input can be processed (because there is not
 286     enough room in the output buffer), next_in and avail_in are updated and
 287     processing will resume at this point for the next call of deflate().
 288 
 289   - Generate more output starting at next_out and update next_out and avail_out
 290     accordingly.  This action is forced if the parameter flush is non zero.
 291     Forcing flush frequently degrades the compression ratio, so this parameter
 292     should be set only when necessary.  Some output may be provided even if
 293     flush is zero.
 294 
 295     Before the call of deflate(), the application should ensure that at least
 296   one of the actions is possible, by providing more input and/or consuming more
 297   output, and updating avail_in or avail_out accordingly; avail_out should
 298   never be zero before the call.  The application can consume the compressed
 299   output when it wants, for example when the output buffer is full (avail_out
 300   == 0), or after each call of deflate().  If deflate returns Z_OK and with
 301   zero avail_out, it must be called again after making room in the output
 302   buffer because there might be more output pending. See deflatePending(),
 303   which can be used if desired to determine whether or not there is more output
 304   in that case.
 305 
 306     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
 307   decide how much data to accumulate before producing output, in order to
 308   maximize compression.
 309 
 310     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
 311   flushed to the output buffer and the output is aligned on a byte boundary, so
 312   that the decompressor can get all input data available so far.  (In
 313   particular avail_in is zero after the call if enough output space has been
 314   provided before the call.) Flushing may degrade compression for some
 315   compression algorithms and so it should be used only when necessary.  This
 316   completes the current deflate block and follows it with an empty stored block
 317   that is three bits plus filler bits to the next byte, followed by four bytes
 318   (00 00 ff ff).
 319 
 320     If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
 321   output buffer, but the output is not aligned to a byte boundary.  All of the
 322   input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
 323   This completes the current deflate block and follows it with an empty fixed
 324   codes block that is 10 bits long.  This assures that enough bytes are output
 325   in order for the decompressor to finish the block before the empty fixed
 326   codes block.
 327 
 328     If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
 329   for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
 330   seven bits of the current block are held to be written as the next byte after
 331   the next deflate block is completed.  In this case, the decompressor may not
 332   be provided enough bits at this point in order to complete decompression of
 333   the data provided so far to the compressor.  It may need to wait for the next
 334   block to be emitted.  This is for advanced applications that need to control
 335   the emission of deflate blocks.
 336 
 337     If flush is set to Z_FULL_FLUSH, all output is flushed as with
 338   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
 339   restart from this point if previous compressed data has been damaged or if
 340   random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
 341   compression.
 342 
 343     If deflate returns with avail_out == 0, this function must be called again
 344   with the same value of the flush parameter and more output space (updated
 345   avail_out), until the flush is complete (deflate returns with non-zero
 346   avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
 347   avail_out is greater than six to avoid repeated flush markers due to
 348   avail_out == 0 on return.
 349 
 350     If the parameter flush is set to Z_FINISH, pending input is processed,
 351   pending output is flushed and deflate returns with Z_STREAM_END if there was
 352   enough output space.  If deflate returns with Z_OK or Z_BUF_ERROR, this
 353   function must be called again with Z_FINISH and more output space (updated
 354   avail_out) but no more input data, until it returns with Z_STREAM_END or an
 355   error.  After deflate has returned Z_STREAM_END, the only possible operations
 356   on the stream are deflateReset or deflateEnd.
 357 
 358     Z_FINISH can be used in the first deflate call after deflateInit if all the
 359   compression is to be done in a single step.  In order to complete in one
 360   call, avail_out must be at least the value returned by deflateBound (see
 361   below).  Then deflate is guaranteed to return Z_STREAM_END.  If not enough
 362   output space is provided, deflate will not return Z_STREAM_END, and it must
 363   be called again as described above.
 364 
 365     deflate() sets strm->adler to the Adler-32 checksum of all input read
 366   so far (that is, total_in bytes).  If a gzip stream is being generated, then
 367   strm->adler will be the CRC-32 checksum of the input read so far.  (See
 368   deflateInit2 below.)
 369 
 370     deflate() may update strm->data_type if it can make a good guess about
 371   the input data type (Z_BINARY or Z_TEXT).  If in doubt, the data is
 372   considered binary.  This field is only for information purposes and does not
 373   affect the compression algorithm in any manner.
 374 
 375     deflate() returns Z_OK if some progress has been made (more input
 376   processed or more output produced), Z_STREAM_END if all input has been
 377   consumed and all output has been produced (only when flush is set to
 378   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
 379   if next_in or next_out was Z_NULL or the state was inadvertently written over
 380   by the application), or Z_BUF_ERROR if no progress is possible (for example
 381   avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not fatal, and
 382   deflate() can be called again with more input and more output space to
 383   continue compressing.
 384 */
 385 
 386 
 387 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
 388 /*
 389      All dynamically allocated data structures for this stream are freed.
 390    This function discards any unprocessed input and does not flush any pending
 391    output.
 392 
 393      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
 394    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
 395    prematurely (some input or output was discarded).  In the error case, msg
 396    may be set but then points to a static string (which must not be
 397    deallocated).
 398 */
 399 
 400 
 401 /*
 402 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
 403 
 404      Initializes the internal stream state for decompression.  The fields
 405    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
 406    the caller.  In the current version of inflate, the provided input is not
 407    read or consumed.  The allocation of a sliding window will be deferred to
 408    the first call of inflate (if the decompression does not complete on the
 409    first call).  If zalloc and zfree are set to Z_NULL, inflateInit updates
 410    them to use default allocation functions.
 411 
 412      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
 413    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 414    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
 415    invalid, such as a null pointer to the structure.  msg is set to null if
 416    there is no error message.  inflateInit does not perform any decompression.
 417    Actual decompression will be done by inflate().  So next_in, and avail_in,
 418    next_out, and avail_out are unused and unchanged.  The current
 419    implementation of inflateInit() does not process any header information --
 420    that is deferred until inflate() is called.
 421 */
 422 
 423 
 424 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
 425 /*
 426     inflate decompresses as much data as possible, and stops when the input
 427   buffer becomes empty or the output buffer becomes full.  It may introduce
 428   some output latency (reading input without producing any output) except when
 429   forced to flush.
 430 
 431   The detailed semantics are as follows.  inflate performs one or both of the
 432   following actions:
 433 
 434   - Decompress more input starting at next_in and update next_in and avail_in
 435     accordingly.  If not all input can be processed (because there is not
 436     enough room in the output buffer), then next_in and avail_in are updated
 437     accordingly, and processing will resume at this point for the next call of
 438     inflate().
 439 
 440   - Generate more output starting at next_out and update next_out and avail_out
 441     accordingly.  inflate() provides as much output as possible, until there is
 442     no more input data or no more space in the output buffer (see below about
 443     the flush parameter).
 444 
 445     Before the call of inflate(), the application should ensure that at least
 446   one of the actions is possible, by providing more input and/or consuming more
 447   output, and updating the next_* and avail_* values accordingly.  If the
 448   caller of inflate() does not provide both available input and available
 449   output space, it is possible that there will be no progress made.  The
 450   application can consume the uncompressed output when it wants, for example
 451   when the output buffer is full (avail_out == 0), or after each call of
 452   inflate().  If inflate returns Z_OK and with zero avail_out, it must be
 453   called again after making room in the output buffer because there might be
 454   more output pending.
 455 
 456     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
 457   Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
 458   output as possible to the output buffer.  Z_BLOCK requests that inflate()
 459   stop if and when it gets to the next deflate block boundary.  When decoding
 460   the zlib or gzip format, this will cause inflate() to return immediately
 461   after the header and before the first block.  When doing a raw inflate,
 462   inflate() will go ahead and process the first block, and will return when it
 463   gets to the end of that block, or when it runs out of data.
 464 
 465     The Z_BLOCK option assists in appending to or combining deflate streams.
 466   To assist in this, on return inflate() always sets strm->data_type to the
 467   number of unused bits in the last byte taken from strm->next_in, plus 64 if
 468   inflate() is currently decoding the last block in the deflate stream, plus
 469   128 if inflate() returned immediately after decoding an end-of-block code or
 470   decoding the complete header up to just before the first byte of the deflate
 471   stream.  The end-of-block will not be indicated until all of the uncompressed
 472   data from that block has been written to strm->next_out.  The number of
 473   unused bits may in general be greater than seven, except when bit 7 of
 474   data_type is set, in which case the number of unused bits will be less than
 475   eight.  data_type is set as noted here every time inflate() returns for all
 476   flush options, and so can be used to determine the amount of currently
 477   consumed input in bits.
 478 
 479     The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
 480   end of each deflate block header is reached, before any actual data in that
 481   block is decoded.  This allows the caller to determine the length of the
 482   deflate block header for later use in random access within a deflate block.
 483   256 is added to the value of strm->data_type when inflate() returns
 484   immediately after reaching the end of the deflate block header.
 485 
 486     inflate() should normally be called until it returns Z_STREAM_END or an
 487   error.  However if all decompression is to be performed in a single step (a
 488   single call of inflate), the parameter flush should be set to Z_FINISH.  In
 489   this case all pending input is processed and all pending output is flushed;
 490   avail_out must be large enough to hold all of the uncompressed data for the
 491   operation to complete.  (The size of the uncompressed data may have been
 492   saved by the compressor for this purpose.)  The use of Z_FINISH is not
 493   required to perform an inflation in one step.  However it may be used to
 494   inform inflate that a faster approach can be used for the single inflate()
 495   call.  Z_FINISH also informs inflate to not maintain a sliding window if the
 496   stream completes, which reduces inflate's memory footprint.  If the stream
 497   does not complete, either because not all of the stream is provided or not
 498   enough output space is provided, then a sliding window will be allocated and
 499   inflate() can be called again to continue the operation as if Z_NO_FLUSH had
 500   been used.
 501 
 502      In this implementation, inflate() always flushes as much output as
 503   possible to the output buffer, and always uses the faster approach on the
 504   first call.  So the effects of the flush parameter in this implementation are
 505   on the return value of inflate() as noted below, when inflate() returns early
 506   when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
 507   memory for a sliding window when Z_FINISH is used.
 508 
 509      If a preset dictionary is needed after this call (see inflateSetDictionary
 510   below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
 511   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
 512   strm->adler to the Adler-32 checksum of all output produced so far (that is,
 513   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
 514   below.  At the end of the stream, inflate() checks that its computed Adler-32
 515   checksum is equal to that saved by the compressor and returns Z_STREAM_END
 516   only if the checksum is correct.
 517 
 518     inflate() can decompress and check either zlib-wrapped or gzip-wrapped
 519   deflate data.  The header type is detected automatically, if requested when
 520   initializing with inflateInit2().  Any information contained in the gzip
 521   header is not retained unless inflateGetHeader() is used.  When processing
 522   gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
 523   produced so far.  The CRC-32 is checked against the gzip trailer, as is the
 524   uncompressed length, modulo 2^32.
 525 
 526     inflate() returns Z_OK if some progress has been made (more input processed
 527   or more output produced), Z_STREAM_END if the end of the compressed data has
 528   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
 529   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
 530   corrupted (input stream not conforming to the zlib format or incorrect check
 531   value, in which case strm->msg points to a string with a more specific
 532   error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
 533   next_in or next_out was Z_NULL, or the state was inadvertently written over
 534   by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
 535   if no progress was possible or if there was not enough room in the output
 536   buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
 537   inflate() can be called again with more input and more output space to
 538   continue decompressing.  If Z_DATA_ERROR is returned, the application may
 539   then call inflateSync() to look for a good compression block if a partial
 540   recovery of the data is to be attempted.
 541 */
 542 
 543 
 544 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
 545 /*
 546      All dynamically allocated data structures for this stream are freed.
 547    This function discards any unprocessed input and does not flush any pending
 548    output.
 549 
 550      inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
 551    was inconsistent.
 552 */
 553 
 554 
 555                         /* Advanced functions */
 556 
 557 /*
 558     The following functions are needed only in some special applications.
 559 */
 560 
 561 /*
 562 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
 563                                      int  level,
 564                                      int  method,
 565                                      int  windowBits,
 566                                      int  memLevel,
 567                                      int  strategy));
 568 
 569      This is another version of deflateInit with more compression options.  The
 570    fields zalloc, zfree and opaque must be initialized before by the caller.
 571 
 572      The method parameter is the compression method.  It must be Z_DEFLATED in
 573    this version of the library.
 574 
 575      The windowBits parameter is the base two logarithm of the window size
 576    (the size of the history buffer).  It should be in the range 8..15 for this
 577    version of the library.  Larger values of this parameter result in better
 578    compression at the expense of memory usage.  The default value is 15 if
 579    deflateInit is used instead.
 580 
 581      For the current implementation of deflate(), a windowBits value of 8 (a
 582    window size of 256 bytes) is not supported.  As a result, a request for 8
 583    will result in 9 (a 512-byte window).  In that case, providing 8 to
 584    inflateInit2() will result in an error when the zlib header with 9 is
 585    checked against the initialization of inflate().  The remedy is to not use 8
 586    with deflateInit2() with this initialization, or at least in that case use 9
 587    with inflateInit2().
 588 
 589      windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
 590    determines the window size.  deflate() will then generate raw deflate data
 591    with no zlib header or trailer, and will not compute a check value.
 592 
 593      windowBits can also be greater than 15 for optional gzip encoding.  Add
 594    16 to windowBits to write a simple gzip header and trailer around the
 595    compressed data instead of a zlib wrapper.  The gzip header will have no
 596    file name, no extra data, no comment, no modification time (set to zero), no
 597    header crc, and the operating system will be set to the appropriate value,
 598    if the operating system was determined at compile time.  If a gzip stream is
 599    being written, strm->adler is a CRC-32 instead of an Adler-32.
 600 
 601      For raw deflate or gzip encoding, a request for a 256-byte window is
 602    rejected as invalid, since only the zlib header provides a means of
 603    transmitting the window size to the decompressor.
 604 
 605      The memLevel parameter specifies how much memory should be allocated
 606    for the internal compression state.  memLevel=1 uses minimum memory but is
 607    slow and reduces compression ratio; memLevel=9 uses maximum memory for
 608    optimal speed.  The default value is 8.  See zconf.h for total memory usage
 609    as a function of windowBits and memLevel.
 610 
 611      The strategy parameter is used to tune the compression algorithm.  Use the
 612    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
 613    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
 614    string match), or Z_RLE to limit match distances to one (run-length
 615    encoding).  Filtered data consists mostly of small values with a somewhat
 616    random distribution.  In this case, the compression algorithm is tuned to
 617    compress them better.  The effect of Z_FILTERED is to force more Huffman
 618    coding and less string matching; it is somewhat intermediate between
 619    Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
 620    fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
 621    strategy parameter only affects the compression ratio but not the
 622    correctness of the compressed output even if it is not set appropriately.
 623    Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
 624    decoder for special applications.
 625 
 626      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 627    memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
 628    method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
 629    incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
 630    set to null if there is no error message.  deflateInit2 does not perform any
 631    compression: this will be done by deflate().
 632 */
 633 
 634 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
 635                                              const Bytef *dictionary,
 636                                              uInt  dictLength));
 637 /*
 638      Initializes the compression dictionary from the given byte sequence
 639    without producing any compressed output.  When using the zlib format, this
 640    function must be called immediately after deflateInit, deflateInit2 or
 641    deflateReset, and before any call of deflate.  When doing raw deflate, this
 642    function must be called either before any call of deflate, or immediately
 643    after the completion of a deflate block, i.e. after all input has been
 644    consumed and all output has been delivered when using any of the flush
 645    options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
 646    compressor and decompressor must use exactly the same dictionary (see
 647    inflateSetDictionary).
 648 
 649      The dictionary should consist of strings (byte sequences) that are likely
 650    to be encountered later in the data to be compressed, with the most commonly
 651    used strings preferably put towards the end of the dictionary.  Using a
 652    dictionary is most useful when the data to be compressed is short and can be
 653    predicted with good accuracy; the data can then be compressed better than
 654    with the default empty dictionary.
 655 
 656      Depending on the size of the compression data structures selected by
 657    deflateInit or deflateInit2, a part of the dictionary may in effect be
 658    discarded, for example if the dictionary is larger than the window size
 659    provided in deflateInit or deflateInit2.  Thus the strings most likely to be
 660    useful should be put at the end of the dictionary, not at the front.  In
 661    addition, the current implementation of deflate will use at most the window
 662    size minus 262 bytes of the provided dictionary.
 663 
 664      Upon return of this function, strm->adler is set to the Adler-32 value
 665    of the dictionary; the decompressor may later use this value to determine
 666    which dictionary has been used by the compressor.  (The Adler-32 value
 667    applies to the whole dictionary even if only a subset of the dictionary is
 668    actually used by the compressor.) If a raw deflate was requested, then the
 669    Adler-32 value is not computed and strm->adler is not set.
 670 
 671      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
 672    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
 673    inconsistent (for example if deflate has already been called for this stream
 674    or if not at a block boundary for raw deflate).  deflateSetDictionary does
 675    not perform any compression: this will be done by deflate().
 676 */
 677 
 678 ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
 679                                              Bytef *dictionary,
 680                                              uInt  *dictLength));
 681 /*
 682      Returns the sliding dictionary being maintained by deflate.  dictLength is
 683    set to the number of bytes in the dictionary, and that many bytes are copied
 684    to dictionary.  dictionary must have enough space, where 32768 bytes is
 685    always enough.  If deflateGetDictionary() is called with dictionary equal to
 686    Z_NULL, then only the dictionary length is returned, and nothing is copied.
 687    Similarly, if dictLength is Z_NULL, then it is not set.
 688 
 689      deflateGetDictionary() may return a length less than the window size, even
 690    when more than the window size in input has been provided. It may return up
 691    to 258 bytes less in that case, due to how zlib's implementation of deflate
 692    manages the sliding window and lookahead for matches, where matches can be
 693    up to 258 bytes long. If the application needs the last window-size bytes of
 694    input, then that would need to be saved by the application outside of zlib.
 695 
 696      deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
 697    stream state is inconsistent.
 698 */
 699 
 700 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
 701                                     z_streamp source));
 702 /*
 703      Sets the destination stream as a complete copy of the source stream.
 704 
 705      This function can be useful when several compression strategies will be
 706    tried, for example when there are several ways of pre-processing the input
 707    data with a filter.  The streams that will be discarded should then be freed
 708    by calling deflateEnd.  Note that deflateCopy duplicates the internal
 709    compression state which can be quite large, so this strategy is slow and can
 710    consume lots of memory.
 711 
 712      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 713    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 714    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
 715    destination.
 716 */
 717 
 718 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
 719 /*
 720      This function is equivalent to deflateEnd followed by deflateInit, but
 721    does not free and reallocate the internal compression state.  The stream
 722    will leave the compression level and any other attributes that may have been
 723    set unchanged.
 724 
 725      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 726    stream state was inconsistent (such as zalloc or state being Z_NULL).
 727 */
 728 
 729 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
 730                                       int level,
 731                                       int strategy));
 732 /*
 733      Dynamically update the compression level and compression strategy.  The
 734    interpretation of level and strategy is as in deflateInit2().  This can be
 735    used to switch between compression and straight copy of the input data, or
 736    to switch to a different kind of input data requiring a different strategy.
 737    If the compression approach (which is a function of the level) or the
 738    strategy is changed, and if there have been any deflate() calls since the
 739    state was initialized or reset, then the input available so far is
 740    compressed with the old level and strategy using deflate(strm, Z_BLOCK).
 741    There are three approaches for the compression levels 0, 1..3, and 4..9
 742    respectively.  The new level and strategy will take effect at the next call
 743    of deflate().
 744 
 745      If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
 746    not have enough output space to complete, then the parameter change will not
 747    take effect.  In this case, deflateParams() can be called again with the
 748    same parameters and more output space to try again.
 749 
 750      In order to assure a change in the parameters on the first try, the
 751    deflate stream should be flushed using deflate() with Z_BLOCK or other flush
 752    request until strm.avail_out is not zero, before calling deflateParams().
 753    Then no more input data should be provided before the deflateParams() call.
 754    If this is done, the old level and strategy will be applied to the data
 755    compressed before deflateParams(), and the new level and strategy will be
 756    applied to the the data compressed after deflateParams().
 757 
 758      deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
 759    state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
 760    there was not enough output space to complete the compression of the
 761    available input data before a change in the strategy or approach.  Note that
 762    in the case of a Z_BUF_ERROR, the parameters are not changed.  A return
 763    value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
 764    retried with more output space.
 765 */
 766 
 767 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
 768                                     int good_length,
 769                                     int max_lazy,
 770                                     int nice_length,
 771                                     int max_chain));
 772 /*
 773      Fine tune deflate's internal compression parameters.  This should only be
 774    used by someone who understands the algorithm used by zlib's deflate for
 775    searching for the best matching string, and even then only by the most
 776    fanatic optimizer trying to squeeze out the last compressed bit for their
 777    specific input data.  Read the deflate.c source code for the meaning of the
 778    max_lazy, good_length, nice_length, and max_chain parameters.
 779 
 780      deflateTune() can be called after deflateInit() or deflateInit2(), and
 781    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
 782  */
 783 
 784 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
 785                                        uLong sourceLen));
 786 /*
 787      deflateBound() returns an upper bound on the compressed size after
 788    deflation of sourceLen bytes.  It must be called after deflateInit() or
 789    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
 790    to allocate an output buffer for deflation in a single pass, and so would be
 791    called before deflate().  If that first deflate() call is provided the
 792    sourceLen input bytes, an output buffer allocated to the size returned by
 793    deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
 794    to return Z_STREAM_END.  Note that it is possible for the compressed size to
 795    be larger than the value returned by deflateBound() if flush options other
 796    than Z_FINISH or Z_NO_FLUSH are used.
 797 */
 798 
 799 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
 800                                        unsigned *pending,
 801                                        int *bits));
 802 /*
 803      deflatePending() returns the number of bytes and bits of output that have
 804    been generated, but not yet provided in the available output.  The bytes not
 805    provided would be due to the available output space having being consumed.
 806    The number of bits of output not provided are between 0 and 7, where they
 807    await more bits to join them in order to fill out a full byte.  If pending
 808    or bits are Z_NULL, then those values are not set.
 809 
 810      deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
 811    stream state was inconsistent.
 812  */
 813 
 814 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
 815                                      int bits,
 816                                      int value));
 817 /*
 818      deflatePrime() inserts bits in the deflate output stream.  The intent
 819    is that this function is used to start off the deflate output with the bits
 820    leftover from a previous deflate stream when appending to it.  As such, this
 821    function can only be used for raw deflate, and must be used before the first
 822    deflate() call after a deflateInit2() or deflateReset().  bits must be less
 823    than or equal to 16, and that many of the least significant bits of value
 824    will be inserted in the output.
 825 
 826      deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
 827    room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
 828    source stream state was inconsistent.
 829 */
 830 
 831 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
 832                                          gz_headerp head));
 833 /*
 834      deflateSetHeader() provides gzip header information for when a gzip
 835    stream is requested by deflateInit2().  deflateSetHeader() may be called
 836    after deflateInit2() or deflateReset() and before the first call of
 837    deflate().  The text, time, os, extra field, name, and comment information
 838    in the provided gz_header structure are written to the gzip header (xflag is
 839    ignored -- the extra flags are set according to the compression level).  The
 840    caller must assure that, if not Z_NULL, name and comment are terminated with
 841    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
 842    available there.  If hcrc is true, a gzip header crc is included.  Note that
 843    the current versions of the command-line version of gzip (up through version
 844    1.3.x) do not support header crc's, and will report that it is a "multi-part
 845    gzip file" and give up.
 846 
 847      If deflateSetHeader is not used, the default gzip header has text false,
 848    the time set to zero, and os set to 255, with no extra, name, or comment
 849    fields.  The gzip header is returned to the default state by deflateReset().
 850 
 851      deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
 852    stream state was inconsistent.
 853 */
 854 
 855 /*
 856 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
 857                                      int  windowBits));
 858 
 859      This is another version of inflateInit with an extra parameter.  The
 860    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
 861    before by the caller.
 862 
 863      The windowBits parameter is the base two logarithm of the maximum window
 864    size (the size of the history buffer).  It should be in the range 8..15 for
 865    this version of the library.  The default value is 15 if inflateInit is used
 866    instead.  windowBits must be greater than or equal to the windowBits value
 867    provided to deflateInit2() while compressing, or it must be equal to 15 if
 868    deflateInit2() was not used.  If a compressed stream with a larger window
 869    size is given as input, inflate() will return with the error code
 870    Z_DATA_ERROR instead of trying to allocate a larger window.
 871 
 872      windowBits can also be zero to request that inflate use the window size in
 873    the zlib header of the compressed stream.
 874 
 875      windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
 876    determines the window size.  inflate() will then process raw deflate data,
 877    not looking for a zlib or gzip header, not generating a check value, and not
 878    looking for any check values for comparison at the end of the stream.  This
 879    is for use with other formats that use the deflate compressed data format
 880    such as zip.  Those formats provide their own check values.  If a custom
 881    format is developed using the raw deflate format for compressed data, it is
 882    recommended that a check value such as an Adler-32 or a CRC-32 be applied to
 883    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
 884    most applications, the zlib format should be used as is.  Note that comments
 885    above on the use in deflateInit2() applies to the magnitude of windowBits.
 886 
 887      windowBits can also be greater than 15 for optional gzip decoding.  Add
 888    32 to windowBits to enable zlib and gzip decoding with automatic header
 889    detection, or add 16 to decode only the gzip format (the zlib format will
 890    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
 891    CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
 892    below), inflate() will *not* automatically decode concatenated gzip members.
 893    inflate() will return Z_STREAM_END at the end of the gzip member.  The state
 894    would need to be reset to continue decoding a subsequent gzip member.  This
 895    *must* be done if there is more data after a gzip member, in order for the
 896    decompression to be compliant with the gzip standard (RFC 1952).
 897 
 898      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 899    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 900    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
 901    invalid, such as a null pointer to the structure.  msg is set to null if
 902    there is no error message.  inflateInit2 does not perform any decompression
 903    apart from possibly reading the zlib header if present: actual decompression
 904    will be done by inflate().  (So next_in and avail_in may be modified, but
 905    next_out and avail_out are unused and unchanged.) The current implementation
 906    of inflateInit2() does not process any header information -- that is
 907    deferred until inflate() is called.
 908 */
 909 
 910 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
 911                                              const Bytef *dictionary,
 912                                              uInt  dictLength));
 913 /*
 914      Initializes the decompression dictionary from the given uncompressed byte
 915    sequence.  This function must be called immediately after a call of inflate,
 916    if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
 917    can be determined from the Adler-32 value returned by that call of inflate.
 918    The compressor and decompressor must use exactly the same dictionary (see
 919    deflateSetDictionary).  For raw inflate, this function can be called at any
 920    time to set the dictionary.  If the provided dictionary is smaller than the
 921    window and there is already data in the window, then the provided dictionary
 922    will amend what's there.  The application must insure that the dictionary
 923    that was used for compression is provided.
 924 
 925      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
 926    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
 927    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
 928    expected one (incorrect Adler-32 value).  inflateSetDictionary does not
 929    perform any decompression: this will be done by subsequent calls of
 930    inflate().
 931 */
 932 
 933 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
 934                                              Bytef *dictionary,
 935                                              uInt  *dictLength));
 936 /*
 937      Returns the sliding dictionary being maintained by inflate.  dictLength is
 938    set to the number of bytes in the dictionary, and that many bytes are copied
 939    to dictionary.  dictionary must have enough space, where 32768 bytes is
 940    always enough.  If inflateGetDictionary() is called with dictionary equal to
 941    Z_NULL, then only the dictionary length is returned, and nothing is copied.
 942    Similarly, if dictLength is Z_NULL, then it is not set.
 943 
 944      inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
 945    stream state is inconsistent.
 946 */
 947 
 948 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
 949 /*
 950      Skips invalid compressed data until a possible full flush point (see above
 951    for the description of deflate with Z_FULL_FLUSH) can be found, or until all
 952    available input is skipped.  No output is provided.
 953 
 954      inflateSync searches for a 00 00 FF FF pattern in the compressed data.
 955    All full flush points have this pattern, but not all occurrences of this
 956    pattern are full flush points.
 957 
 958      inflateSync returns Z_OK if a possible full flush point has been found,
 959    Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
 960    has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
 961    In the success case, the application may save the current current value of
 962    total_in which indicates where valid compressed data was found.  In the
 963    error case, the application may repeatedly call inflateSync, providing more
 964    input each time, until success or end of the input data.
 965 */
 966 
 967 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
 968                                     z_streamp source));
 969 /*
 970      Sets the destination stream as a complete copy of the source stream.
 971 
 972      This function can be useful when randomly accessing a large stream.  The
 973    first pass through the stream can periodically record the inflate state,
 974    allowing restarting inflate at those points when randomly accessing the
 975    stream.
 976 
 977      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 978    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 979    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
 980    destination.
 981 */
 982 
 983 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
 984 /*
 985      This function is equivalent to inflateEnd followed by inflateInit,
 986    but does not free and reallocate the internal decompression state.  The
 987    stream will keep attributes that may have been set by inflateInit2.
 988 
 989      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 990    stream state was inconsistent (such as zalloc or state being Z_NULL).
 991 */
 992 
 993 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
 994                                       int windowBits));
 995 /*
 996      This function is the same as inflateReset, but it also permits changing
 997    the wrap and window size requests.  The windowBits parameter is interpreted
 998    the same as it is for inflateInit2.  If the window size is changed, then the
 999    memory allocated for the window is freed, and the window will be reallocated
1000    by inflate() if needed.
1001 
1002      inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
1003    stream state was inconsistent (such as zalloc or state being Z_NULL), or if
1004    the windowBits parameter is invalid.
1005 */
1006 
1007 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
1008                                      int bits,
1009                                      int value));
1010 /*
1011      This function inserts bits in the inflate input stream.  The intent is
1012    that this function is used to start inflating at a bit position in the
1013    middle of a byte.  The provided bits will be used before any bytes are used
1014    from next_in.  This function should only be used with raw inflate, and
1015    should be used before the first inflate() call after inflateInit2() or
1016    inflateReset().  bits must be less than or equal to 16, and that many of the
1017    least significant bits of value will be inserted in the input.
1018 
1019      If bits is negative, then the input stream bit buffer is emptied.  Then
1020    inflatePrime() can be called again to put bits in the buffer.  This is used
1021    to clear out bits leftover after feeding inflate a block description prior
1022    to feeding inflate codes.
1023 
1024      inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1025    stream state was inconsistent.
1026 */
1027 
1028 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
1029 /*
1030      This function returns two values, one in the lower 16 bits of the return
1031    value, and the other in the remaining upper bits, obtained by shifting the
1032    return value down 16 bits.  If the upper value is -1 and the lower value is
1033    zero, then inflate() is currently decoding information outside of a block.
1034    If the upper value is -1 and the lower value is non-zero, then inflate is in
1035    the middle of a stored block, with the lower value equaling the number of
1036    bytes from the input remaining to copy.  If the upper value is not -1, then
1037    it is the number of bits back from the current bit position in the input of
1038    the code (literal or length/distance pair) currently being processed.  In
1039    that case the lower value is the number of bytes already emitted for that
1040    code.
1041 
1042      A code is being processed if inflate is waiting for more input to complete
1043    decoding of the code, or if it has completed decoding but is waiting for
1044    more output space to write the literal or match data.
1045 
1046      inflateMark() is used to mark locations in the input data for random
1047    access, which may be at bit positions, and to note those cases where the
1048    output of a code may span boundaries of random access blocks.  The current
1049    location in the input stream can be determined from avail_in and data_type
1050    as noted in the description for the Z_BLOCK flush parameter for inflate.
1051 
1052      inflateMark returns the value noted above, or -65536 if the provided
1053    source stream state was inconsistent.
1054 */
1055 
1056 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
1057                                          gz_headerp head));
1058 /*
1059      inflateGetHeader() requests that gzip header information be stored in the
1060    provided gz_header structure.  inflateGetHeader() may be called after
1061    inflateInit2() or inflateReset(), and before the first call of inflate().
1062    As inflate() processes the gzip stream, head->done is zero until the header
1063    is completed, at which time head->done is set to one.  If a zlib stream is
1064    being decoded, then head->done is set to -1 to indicate that there will be
1065    no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
1066    used to force inflate() to return immediately after header processing is
1067    complete and before any actual data is decompressed.
1068 
1069      The text, time, xflags, and os fields are filled in with the gzip header
1070    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
1071    was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1072    contains the maximum number of bytes to write to extra.  Once done is true,
1073    extra_len contains the actual extra field length, and extra contains the
1074    extra field, or that field truncated if extra_max is less than extra_len.
1075    If name is not Z_NULL, then up to name_max characters are written there,
1076    terminated with a zero unless the length is greater than name_max.  If
1077    comment is not Z_NULL, then up to comm_max characters are written there,
1078    terminated with a zero unless the length is greater than comm_max.  When any
1079    of extra, name, or comment are not Z_NULL and the respective field is not
1080    present in the header, then that field is set to Z_NULL to signal its
1081    absence.  This allows the use of deflateSetHeader() with the returned
1082    structure to duplicate the header.  However if those fields are set to
1083    allocated memory, then the application will need to save those pointers
1084    elsewhere so that they can be eventually freed.
1085 
1086      If inflateGetHeader is not used, then the header information is simply
1087    discarded.  The header is always checked for validity, including the header
1088    CRC if present.  inflateReset() will reset the process to discard the header
1089    information.  The application would need to call inflateGetHeader() again to
1090    retrieve the header from the next gzip stream.
1091 
1092      inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1093    stream state was inconsistent.
1094 */
1095 
1096 /*
1097 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
1098                                         unsigned char FAR *window));
1099 
1100      Initialize the internal stream state for decompression using inflateBack()
1101    calls.  The fields zalloc, zfree and opaque in strm must be initialized
1102    before the call.  If zalloc and zfree are Z_NULL, then the default library-
1103    derived memory allocation routines are used.  windowBits is the base two
1104    logarithm of the window size, in the range 8..15.  window is a caller
1105    supplied buffer of that size.  Except for special applications where it is
1106    assured that deflate was used with small window sizes, windowBits must be 15
1107    and a 32K byte window must be supplied to be able to decompress general
1108    deflate streams.
1109 
1110      See inflateBack() for the usage of these routines.
1111 
1112      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1113    the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1114    allocated, or Z_VERSION_ERROR if the version of the library does not match
1115    the version of the header file.
1116 */
1117 
1118 typedef unsigned (*in_func) OF((void FAR *,
1119                                 z_const unsigned char FAR * FAR *));
1120 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
1121 
1122 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
1123                                     in_func in, void FAR *in_desc,
1124                                     out_func out, void FAR *out_desc));
1125 /*
1126      inflateBack() does a raw inflate with a single call using a call-back
1127    interface for input and output.  This is potentially more efficient than
1128    inflate() for file i/o applications, in that it avoids copying between the
1129    output and the sliding window by simply making the window itself the output
1130    buffer.  inflate() can be faster on modern CPUs when used with large
1131    buffers.  inflateBack() trusts the application to not change the output
1132    buffer passed by the output function, at least until inflateBack() returns.
1133 
1134      inflateBackInit() must be called first to allocate the internal state
1135    and to initialize the state with the user-provided window buffer.
1136    inflateBack() may then be used multiple times to inflate a complete, raw
1137    deflate stream with each call.  inflateBackEnd() is then called to free the
1138    allocated state.
1139 
1140      A raw deflate stream is one with no zlib or gzip header or trailer.
1141    This routine would normally be used in a utility that reads zip or gzip
1142    files and writes out uncompressed files.  The utility would decode the
1143    header and process the trailer on its own, hence this routine expects only
1144    the raw deflate stream to decompress.  This is different from the default
1145    behavior of inflate(), which expects a zlib header and trailer around the
1146    deflate stream.
1147 
1148      inflateBack() uses two subroutines supplied by the caller that are then
1149    called by inflateBack() for input and output.  inflateBack() calls those
1150    routines until it reads a complete deflate stream and writes out all of the
1151    uncompressed data, or until it encounters an error.  The function's
1152    parameters and return types are defined above in the in_func and out_func
1153    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
1154    number of bytes of provided input, and a pointer to that input in buf.  If
1155    there is no input available, in() must return zero -- buf is ignored in that
1156    case -- and inflateBack() will return a buffer error.  inflateBack() will
1157    call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1158    out() should return zero on success, or non-zero on failure.  If out()
1159    returns non-zero, inflateBack() will return with an error.  Neither in() nor
1160    out() are permitted to change the contents of the window provided to
1161    inflateBackInit(), which is also the buffer that out() uses to write from.
1162    The length written by out() will be at most the window size.  Any non-zero
1163    amount of input may be provided by in().
1164 
1165      For convenience, inflateBack() can be provided input on the first call by
1166    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
1167    in() will be called.  Therefore strm->next_in must be initialized before
1168    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
1169    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
1170    must also be initialized, and then if strm->avail_in is not zero, input will
1171    initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
1172 
1173      The in_desc and out_desc parameters of inflateBack() is passed as the
1174    first parameter of in() and out() respectively when they are called.  These
1175    descriptors can be optionally used to pass any information that the caller-
1176    supplied in() and out() functions need to do their job.
1177 
1178      On return, inflateBack() will set strm->next_in and strm->avail_in to
1179    pass back any unused input that was provided by the last in() call.  The
1180    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1181    if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1182    in the deflate stream (in which case strm->msg is set to indicate the nature
1183    of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1184    In the case of Z_BUF_ERROR, an input or output error can be distinguished
1185    using strm->next_in which will be Z_NULL only if in() returned an error.  If
1186    strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1187    non-zero.  (in() will always be called before out(), so strm->next_in is
1188    assured to be defined if out() returns non-zero.)  Note that inflateBack()
1189    cannot return Z_OK.
1190 */
1191 
1192 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1193 /*
1194      All memory allocated by inflateBackInit() is freed.
1195 
1196      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1197    state was inconsistent.
1198 */
1199 
1200 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1201 /* Return flags indicating compile-time options.
1202 
1203     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1204      1.0: size of uInt
1205      3.2: size of uLong
1206      5.4: size of voidpf (pointer)
1207      7.6: size of z_off_t
1208 
1209     Compiler, assembler, and debug options:
1210      8: ZLIB_DEBUG
1211      9: ASMV or ASMINF -- use ASM code
1212      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1213      11: 0 (reserved)
1214 
1215     One-time table building (smaller code, but not thread-safe if true):
1216      12: BUILDFIXED -- build static block decoding tables when needed
1217      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1218      14,15: 0 (reserved)
1219 
1220     Library content (indicates missing functionality):
1221      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1222                           deflate code when not needed)
1223      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1224                     and decode gzip streams (to avoid linking crc code)
1225      18-19: 0 (reserved)
1226 
1227     Operation variations (changes in library functionality):
1228      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1229      21: FASTEST -- deflate algorithm with only one, lowest compression level
1230      22,23: 0 (reserved)
1231 
1232     The sprintf variant used by gzprintf (zero is best):
1233      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1234      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1235      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1236 
1237     Remainder:
1238      27-31: 0 (reserved)
1239  */
1240 
1241 #ifndef Z_SOLO
1242 
1243                         /* utility functions */
1244 
1245 /*
1246      The following utility functions are implemented on top of the basic
1247    stream-oriented functions.  To simplify the interface, some default options
1248    are assumed (compression level and memory usage, standard memory allocation
1249    functions).  The source code of these utility functions can be modified if
1250    you need special options.
1251 */
1252 
1253 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
1254                                  const Bytef *source, uLong sourceLen));
1255 /*
1256      Compresses the source buffer into the destination buffer.  sourceLen is
1257    the byte length of the source buffer.  Upon entry, destLen is the total size
1258    of the destination buffer, which must be at least the value returned by
1259    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1260    compressed data.  compress() is equivalent to compress2() with a level
1261    parameter of Z_DEFAULT_COMPRESSION.
1262 
1263      compress returns Z_OK if success, Z_MEM_ERROR if there was not
1264    enough memory, Z_BUF_ERROR if there was not enough room in the output
1265    buffer.
1266 */
1267 
1268 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
1269                                   const Bytef *source, uLong sourceLen,
1270                                   int level));
1271 /*
1272      Compresses the source buffer into the destination buffer.  The level
1273    parameter has the same meaning as in deflateInit.  sourceLen is the byte
1274    length of the source buffer.  Upon entry, destLen is the total size of the
1275    destination buffer, which must be at least the value returned by
1276    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1277    compressed data.
1278 
1279      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1280    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1281    Z_STREAM_ERROR if the level parameter is invalid.
1282 */
1283 
1284 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1285 /*
1286      compressBound() returns an upper bound on the compressed size after
1287    compress() or compress2() on sourceLen bytes.  It would be used before a
1288    compress() or compress2() call to allocate the destination buffer.
1289 */
1290 
1291 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
1292                                    const Bytef *source, uLong sourceLen));
1293 /*
1294      Decompresses the source buffer into the destination buffer.  sourceLen is
1295    the byte length of the source buffer.  Upon entry, destLen is the total size
1296    of the destination buffer, which must be large enough to hold the entire
1297    uncompressed data.  (The size of the uncompressed data must have been saved
1298    previously by the compressor and transmitted to the decompressor by some
1299    mechanism outside the scope of this compression library.) Upon exit, destLen
1300    is the actual size of the uncompressed data.
1301 
1302      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1303    enough memory, Z_BUF_ERROR if there was not enough room in the output
1304    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
1305    the case where there is not enough room, uncompress() will fill the output
1306    buffer with the uncompressed data up to that point.
1307 */
1308 
1309 ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest,   uLongf *destLen,
1310                                     const Bytef *source, uLong *sourceLen));
1311 /*
1312      Same as uncompress, except that sourceLen is a pointer, where the
1313    length of the source is *sourceLen.  On return, *sourceLen is the number of
1314    source bytes consumed.
1315 */
1316 
1317                         /* gzip file access functions */
1318 
1319 /*
1320      This library supports reading and writing files in gzip (.gz) format with
1321    an interface similar to that of stdio, using the functions that start with
1322    "gz".  The gzip format is different from the zlib format.  gzip is a gzip
1323    wrapper, documented in RFC 1952, wrapped around a deflate stream.
1324 */
1325 
1326 typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
1327 
1328 /*
1329 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1330 
1331      Open the gzip (.gz) file at path for reading and decompressing, or
1332    compressing and writing.  The mode parameter is as in fopen ("rb" or "wb")
1333    but can also include a compression level ("wb9") or a strategy: 'f' for
1334    filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
1335    'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
1336    as in "wb9F".  (See the description of deflateInit2 for more information
1337    about the strategy parameter.)  'T' will request transparent writing or
1338    appending with no compression and not using the gzip format.
1339 
1340      "a" can be used instead of "w" to request that the gzip stream that will
1341    be written be appended to the file.  "+" will result in an error, since
1342    reading and writing to the same gzip file is not supported.  The addition of
1343    "x" when writing will create the file exclusively, which fails if the file
1344    already exists.  On systems that support it, the addition of "e" when
1345    reading or writing will set the flag to close the file on an execve() call.
1346 
1347      These functions, as well as gzip, will read and decode a sequence of gzip
1348    streams in a file.  The append function of gzopen() can be used to create
1349    such a file.  (Also see gzflush() for another way to do this.)  When
1350    appending, gzopen does not test whether the file begins with a gzip stream,
1351    nor does it look for the end of the gzip streams to begin appending.  gzopen
1352    will simply append a gzip stream to the existing file.
1353 
1354      gzopen can be used to read a file which is not in gzip format; in this
1355    case gzread will directly read from the file without decompression.  When
1356    reading, this will be detected automatically by looking for the magic two-
1357    byte gzip header.
1358 
1359      gzopen returns NULL if the file could not be opened, if there was
1360    insufficient memory to allocate the gzFile state, or if an invalid mode was
1361    specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1362    errno can be checked to determine if the reason gzopen failed was that the
1363    file could not be opened.
1364 */
1365 
1366 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1367 /*
1368      Associate a gzFile with the file descriptor fd.  File descriptors are
1369    obtained from calls like open, dup, creat, pipe or fileno (if the file has
1370    been previously opened with fopen).  The mode parameter is as in gzopen.
1371 
1372      The next call of gzclose on the returned gzFile will also close the file
1373    descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1374    fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1375    mode);.  The duplicated descriptor should be saved to avoid a leak, since
1376    gzdopen does not close fd if it fails.  If you are using fileno() to get the
1377    file descriptor from a FILE *, then you will have to use dup() to avoid
1378    double-close()ing the file descriptor.  Both gzclose() and fclose() will
1379    close the associated file descriptor, so they need to have different file
1380    descriptors.
1381 
1382      gzdopen returns NULL if there was insufficient memory to allocate the
1383    gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1384    provided, or '+' was provided), or if fd is -1.  The file descriptor is not
1385    used until the next gz* read, write, seek, or close operation, so gzdopen
1386    will not detect if fd is invalid (unless fd is -1).
1387 */
1388 
1389 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1390 /*
1391      Set the internal buffer size used by this library's functions for file to
1392    size.  The default buffer size is 8192 bytes.  This function must be called
1393    after gzopen() or gzdopen(), and before any other calls that read or write
1394    the file.  The buffer memory allocation is always deferred to the first read
1395    or write.  Three times that size in buffer space is allocated.  A larger
1396    buffer size of, for example, 64K or 128K bytes will noticeably increase the
1397    speed of decompression (reading).
1398 
1399      The new buffer size also affects the maximum length for gzprintf().
1400 
1401      gzbuffer() returns 0 on success, or -1 on failure, such as being called
1402    too late.
1403 */
1404 
1405 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1406 /*
1407      Dynamically update the compression level and strategy for file.  See the
1408    description of deflateInit2 for the meaning of these parameters. Previously
1409    provided data is flushed before applying the parameter changes.
1410 
1411      gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1412    opened for writing, Z_ERRNO if there is an error writing the flushed data,
1413    or Z_MEM_ERROR if there is a memory allocation error.
1414 */
1415 
1416 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1417 /*
1418      Read and decompress up to len uncompressed bytes from file into buf.  If
1419    the input file is not in gzip format, gzread copies the given number of
1420    bytes into the buffer directly from the file.
1421 
1422      After reaching the end of a gzip stream in the input, gzread will continue
1423    to read, looking for another gzip stream.  Any number of gzip streams may be
1424    concatenated in the input file, and will all be decompressed by gzread().
1425    If something other than a gzip stream is encountered after a gzip stream,
1426    that remaining trailing garbage is ignored (and no error is returned).
1427 
1428      gzread can be used to read a gzip file that is being concurrently written.
1429    Upon reaching the end of the input, gzread will return with the available
1430    data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1431    gzclearerr can be used to clear the end of file indicator in order to permit
1432    gzread to be tried again.  Z_OK indicates that a gzip stream was completed
1433    on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
1434    middle of a gzip stream.  Note that gzread does not return -1 in the event
1435    of an incomplete gzip stream.  This error is deferred until gzclose(), which
1436    will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1437    stream.  Alternatively, gzerror can be used before gzclose to detect this
1438    case.
1439 
1440      gzread returns the number of uncompressed bytes actually read, less than
1441    len for end of file, or -1 for error.  If len is too large to fit in an int,
1442    then nothing is read, -1 is returned, and the error state is set to
1443    Z_STREAM_ERROR.
1444 */
1445 
1446 ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
1447                                      gzFile file));
1448 /*
1449      Read and decompress up to nitems items of size size from file into buf,
1450    otherwise operating as gzread() does.  This duplicates the interface of
1451    stdio's fread(), with size_t request and return types.  If the library
1452    defines size_t, then z_size_t is identical to size_t.  If not, then z_size_t
1453    is an unsigned integer type that can contain a pointer.
1454 
1455      gzfread() returns the number of full items read of size size, or zero if
1456    the end of the file was reached and a full item could not be read, or if
1457    there was an error.  gzerror() must be consulted if zero is returned in
1458    order to determine if there was an error.  If the multiplication of size and
1459    nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1460    is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1461 
1462      In the event that the end of file is reached and only a partial item is
1463    available at the end, i.e. the remaining uncompressed data length is not a
1464    multiple of size, then the final partial item is nevertheless read into buf
1465    and the end-of-file flag is set.  The length of the partial item read is not
1466    provided, but could be inferred from the result of gztell().  This behavior
1467    is the same as the behavior of fread() implementations in common libraries,
1468    but it prevents the direct use of gzfread() to read a concurrently written
1469    file, resetting and retrying on end-of-file, when size is not 1.
1470 */
1471 
1472 ZEXTERN int ZEXPORT gzwrite OF((gzFile file, voidpc buf, unsigned len));
1473 /*
1474      Compress and write the len uncompressed bytes at buf to file. gzwrite
1475    returns the number of uncompressed bytes written or 0 in case of error.
1476 */
1477 
1478 ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
1479                                       z_size_t nitems, gzFile file));
1480 /*
1481      Compress and write nitems items of size size from buf to file, duplicating
1482    the interface of stdio's fwrite(), with size_t request and return types.  If
1483    the library defines size_t, then z_size_t is identical to size_t.  If not,
1484    then z_size_t is an unsigned integer type that can contain a pointer.
1485 
1486      gzfwrite() returns the number of full items written of size size, or zero
1487    if there was an error.  If the multiplication of size and nitems overflows,
1488    i.e. the product does not fit in a z_size_t, then nothing is written, zero
1489    is returned, and the error state is set to Z_STREAM_ERROR.
1490 */
1491 
1492 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
1493 /*
1494      Convert, format, compress, and write the arguments (...) to file under
1495    control of the string format, as in fprintf.  gzprintf returns the number of
1496    uncompressed bytes actually written, or a negative zlib error code in case
1497    of error.  The number of uncompressed bytes written is limited to 8191, or
1498    one less than the buffer size given to gzbuffer().  The caller should assure
1499    that this limit is not exceeded.  If it is exceeded, then gzprintf() will
1500    return an error (0) with nothing written.  In this case, there may also be a
1501    buffer overflow with unpredictable consequences, which is possible only if
1502    zlib was compiled with the insecure functions sprintf() or vsprintf(),
1503    because the secure snprintf() or vsnprintf() functions were not available.
1504    This can be determined using zlibCompileFlags().
1505 */
1506 
1507 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1508 /*
1509      Compress and write the given null-terminated string s to file, excluding
1510    the terminating null character.
1511 
1512      gzputs returns the number of characters written, or -1 in case of error.
1513 */
1514 
1515 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1516 /*
1517      Read and decompress bytes from file into buf, until len-1 characters are
1518    read, or until a newline character is read and transferred to buf, or an
1519    end-of-file condition is encountered.  If any characters are read or if len
1520    is one, the string is terminated with a null character.  If no characters
1521    are read due to an end-of-file or len is less than one, then the buffer is
1522    left untouched.
1523 
1524      gzgets returns buf which is a null-terminated string, or it returns NULL
1525    for end-of-file or in case of error.  If there was an error, the contents at
1526    buf are indeterminate.
1527 */
1528 
1529 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1530 /*
1531      Compress and write c, converted to an unsigned char, into file.  gzputc
1532    returns the value that was written, or -1 in case of error.
1533 */
1534 
1535 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1536 /*
1537      Read and decompress one byte from file.  gzgetc returns this byte or -1
1538    in case of end of file or error.  This is implemented as a macro for speed.
1539    As such, it does not do all of the checking the other functions do.  I.e.
1540    it does not check to see if file is NULL, nor whether the structure file
1541    points to has been clobbered or not.
1542 */
1543 
1544 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1545 /*
1546      Push c back onto the stream for file to be read as the first character on
1547    the next read.  At least one character of push-back is always allowed.
1548    gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
1549    fail if c is -1, and may fail if a character has been pushed but not read
1550    yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
1551    output buffer size of pushed characters is allowed.  (See gzbuffer above.)
1552    The pushed character will be discarded if the stream is repositioned with
1553    gzseek() or gzrewind().
1554 */
1555 
1556 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1557 /*
1558      Flush all pending output to file.  The parameter flush is as in the
1559    deflate() function.  The return value is the zlib error number (see function
1560    gzerror below).  gzflush is only permitted when writing.
1561 
1562      If the flush parameter is Z_FINISH, the remaining data is written and the
1563    gzip stream is completed in the output.  If gzwrite() is called again, a new
1564    gzip stream will be started in the output.  gzread() is able to read such
1565    concatenated gzip streams.
1566 
1567      gzflush should be called only when strictly necessary because it will
1568    degrade compression if called too often.
1569 */
1570 
1571 /*
1572 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1573                                    z_off_t offset, int whence));
1574 
1575      Set the starting position to offset relative to whence for the next gzread
1576    or gzwrite on file.  The offset represents a number of bytes in the
1577    uncompressed data stream.  The whence parameter is defined as in lseek(2);
1578    the value SEEK_END is not supported.
1579 
1580      If the file is opened for reading, this function is emulated but can be
1581    extremely slow.  If the file is opened for writing, only forward seeks are
1582    supported; gzseek then compresses a sequence of zeroes up to the new
1583    starting position.
1584 
1585      gzseek returns the resulting offset location as measured in bytes from
1586    the beginning of the uncompressed stream, or -1 in case of error, in
1587    particular if the file is opened for writing and the new starting position
1588    would be before the current position.
1589 */
1590 
1591 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
1592 /*
1593      Rewind file. This function is supported only for reading.
1594 
1595      gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
1596 */
1597 
1598 /*
1599 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
1600 
1601      Return the starting position for the next gzread or gzwrite on file.
1602    This position represents a number of bytes in the uncompressed data stream,
1603    and is zero when starting, even if appending or reading a gzip stream from
1604    the middle of a file using gzdopen().
1605 
1606      gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1607 */
1608 
1609 /*
1610 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1611 
1612      Return the current compressed (actual) read or write offset of file.  This
1613    offset includes the count of bytes that precede the gzip stream, for example
1614    when appending or when using gzdopen() for reading.  When reading, the
1615    offset does not include as yet unused buffered input.  This information can
1616    be used for a progress indicator.  On error, gzoffset() returns -1.
1617 */
1618 
1619 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1620 /*
1621      Return true (1) if the end-of-file indicator for file has been set while
1622    reading, false (0) otherwise.  Note that the end-of-file indicator is set
1623    only if the read tried to go past the end of the input, but came up short.
1624    Therefore, just like feof(), gzeof() may return false even if there is no
1625    more data to read, in the event that the last read request was for the exact
1626    number of bytes remaining in the input file.  This will happen if the input
1627    file size is an exact multiple of the buffer size.
1628 
1629      If gzeof() returns true, then the read functions will return no more data,
1630    unless the end-of-file indicator is reset by gzclearerr() and the input file
1631    has grown since the previous end of file was detected.
1632 */
1633 
1634 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1635 /*
1636      Return true (1) if file is being copied directly while reading, or false
1637    (0) if file is a gzip stream being decompressed.
1638 
1639      If the input file is empty, gzdirect() will return true, since the input
1640    does not contain a gzip stream.
1641 
1642      If gzdirect() is used immediately after gzopen() or gzdopen() it will
1643    cause buffers to be allocated to allow reading the file to determine if it
1644    is a gzip file.  Therefore if gzbuffer() is used, it should be called before
1645    gzdirect().
1646 
1647      When writing, gzdirect() returns true (1) if transparent writing was
1648    requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
1649    gzdirect() is not needed when writing.  Transparent writing must be
1650    explicitly requested, so the application already knows the answer.  When
1651    linking statically, using gzdirect() will include all of the zlib code for
1652    gzip file reading and decompression, which may not be desired.)
1653 */
1654 
1655 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
1656 /*
1657      Flush all pending output for file, if necessary, close file and
1658    deallocate the (de)compression state.  Note that once file is closed, you
1659    cannot call gzerror with file, since its structures have been deallocated.
1660    gzclose must not be called more than once on the same file, just as free
1661    must not be called more than once on the same allocation.
1662 
1663      gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1664    file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1665    last read ended in the middle of a gzip stream, or Z_OK on success.
1666 */
1667 
1668 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1669 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1670 /*
1671      Same as gzclose(), but gzclose_r() is only for use when reading, and
1672    gzclose_w() is only for use when writing or appending.  The advantage to
1673    using these instead of gzclose() is that they avoid linking in zlib
1674    compression or decompression code that is not used when only reading or only
1675    writing respectively.  If gzclose() is used, then both compression and
1676    decompression code will be included the application when linking to a static
1677    zlib library.
1678 */
1679 
1680 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1681 /*
1682      Return the error message for the last error which occurred on file.
1683    errnum is set to zlib error number.  If an error occurred in the file system
1684    and not in the compression library, errnum is set to Z_ERRNO and the
1685    application may consult errno to get the exact error code.
1686 
1687      The application must not modify the returned string.  Future calls to
1688    this function may invalidate the previously returned string.  If file is
1689    closed, then the string previously returned by gzerror will no longer be
1690    available.
1691 
1692      gzerror() should be used to distinguish errors from end-of-file for those
1693    functions above that do not distinguish those cases in their return values.
1694 */
1695 
1696 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1697 /*
1698      Clear the error and end-of-file flags for file.  This is analogous to the
1699    clearerr() function in stdio.  This is useful for continuing to read a gzip
1700    file that is being written concurrently.
1701 */
1702 
1703 #endif /* !Z_SOLO */
1704 
1705                         /* checksum functions */
1706 
1707 /*
1708      These functions are not related to compression but are exported
1709    anyway because they might be useful in applications using the compression
1710    library.
1711 */
1712 
1713 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1714 /*
1715      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1716    return the updated checksum. An Adler-32 value is in the range of a 32-bit
1717    unsigned integer. If buf is Z_NULL, this function returns the required
1718    initial value for the checksum.
1719 
1720      An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1721    much faster.
1722 
1723    Usage example:
1724 
1725      uLong adler = adler32(0L, Z_NULL, 0);
1726 
1727      while (read_buffer(buffer, length) != EOF) {
1728        adler = adler32(adler, buffer, length);
1729      }
1730      if (adler != original_adler) error();
1731 */
1732 
1733 ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
1734                                     z_size_t len));
1735 /*
1736      Same as adler32(), but with a size_t length.
1737 */
1738 
1739 /*
1740 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1741                                           z_off_t len2));
1742 
1743      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
1744    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1745    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
1746    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
1747    that the z_off_t type (like off_t) is a signed integer.  If len2 is
1748    negative, the result has no meaning or utility.
1749 */
1750 
1751 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1752 /*
1753      Update a running CRC-32 with the bytes buf[0..len-1] and return the
1754    updated CRC-32. A CRC-32 value is in the range of a 32-bit unsigned integer.
1755    If buf is Z_NULL, this function returns the required initial value for the
1756    crc. Pre- and post-conditioning (one's complement) is performed within this
1757    function so it shouldn't be done by the application.
1758 
1759    Usage example:
1760 
1761      uLong crc = crc32(0L, Z_NULL, 0);
1762 
1763      while (read_buffer(buffer, length) != EOF) {
1764        crc = crc32(crc, buffer, length);
1765      }
1766      if (crc != original_crc) error();
1767 */
1768 
1769 ZEXTERN uLong ZEXPORT crc32_z OF((uLong crc, const Bytef *buf,
1770                                   z_size_t len));
1771 /*
1772      Same as crc32(), but with a size_t length.
1773 */
1774 
1775 /*
1776 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1777 
1778      Combine two CRC-32 check values into one.  For two sequences of bytes,
1779    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1780    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
1781    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1782    len2.
1783 */
1784 
1785 /*
1786 ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t len2));
1787 
1788      Return the operator corresponding to length len2, to be used with
1789    crc32_combine_op().
1790 */
1791 
1792 ZEXTERN uLong ZEXPORT crc32_combine_op OF((uLong crc1, uLong crc2, uLong op));
1793 /*
1794      Give the same result as crc32_combine(), using op in place of len2. op is
1795    is generated from len2 by crc32_combine_gen(). This will be faster than
1796    crc32_combine() if the generated op is used more than once.
1797 */
1798 
1799 
1800                         /* various hacks, don't look :) */
1801 
1802 /* deflateInit and inflateInit are macros to allow checking the zlib version
1803  * and the compiler's view of z_stream:
1804  */
1805 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1806                                      const char *version, int stream_size));
1807 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1808                                      const char *version, int stream_size));
1809 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
1810                                       int windowBits, int memLevel,
1811                                       int strategy, const char *version,
1812                                       int stream_size));
1813 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
1814                                       const char *version, int stream_size));
1815 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1816                                          unsigned char FAR *window,
1817                                          const char *version,
1818                                          int stream_size));
1819 #ifdef Z_PREFIX_SET
1820 #  define z_deflateInit(strm, level) \
1821           deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1822 #  define z_inflateInit(strm) \
1823           inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1824 #  define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1825           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1826                         (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1827 #  define z_inflateInit2(strm, windowBits) \
1828           inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1829                         (int)sizeof(z_stream))
1830 #  define z_inflateBackInit(strm, windowBits, window) \
1831           inflateBackInit_((strm), (windowBits), (window), \
1832                            ZLIB_VERSION, (int)sizeof(z_stream))
1833 #else
1834 #  define deflateInit(strm, level) \
1835           deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1836 #  define inflateInit(strm) \
1837           inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1838 #  define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1839           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1840                         (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1841 #  define inflateInit2(strm, windowBits) \
1842           inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1843                         (int)sizeof(z_stream))
1844 #  define inflateBackInit(strm, windowBits, window) \
1845           inflateBackInit_((strm), (windowBits), (window), \
1846                            ZLIB_VERSION, (int)sizeof(z_stream))
1847 #endif
1848 
1849 #ifndef Z_SOLO
1850 
1851 /* gzgetc() macro and its supporting function and exposed data structure.  Note
1852  * that the real internal state is much larger than the exposed structure.
1853  * This abbreviated structure exposes just enough for the gzgetc() macro.  The
1854  * user should not mess with these exposed elements, since their names or
1855  * behavior could change in the future, perhaps even capriciously.  They can
1856  * only be used by the gzgetc() macro.  You have been warned.
1857  */
1858 struct gzFile_s {
1859     unsigned have;
1860     unsigned char *next;
1861     z_off64_t pos;
1862 };
1863 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
1864 #ifdef Z_PREFIX_SET
1865 #  undef z_gzgetc
1866 #  define z_gzgetc(g) \
1867           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1868 #else
1869 #  define gzgetc(g) \
1870           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1871 #endif
1872 
1873 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1874  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1875  * both are true, the application gets the *64 functions, and the regular
1876  * functions are changed to 64 bits) -- in case these are set on systems
1877  * without large file support, _LFS64_LARGEFILE must also be true
1878  */
1879 #ifdef Z_LARGE64
1880    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1881    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1882    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1883    ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1884    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1885    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1886    ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off64_t));
1887 #endif
1888 
1889 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1890 #  ifdef Z_PREFIX_SET
1891 #    define z_gzopen z_gzopen64
1892 #    define z_gzseek z_gzseek64
1893 #    define z_gztell z_gztell64
1894 #    define z_gzoffset z_gzoffset64
1895 #    define z_adler32_combine z_adler32_combine64
1896 #    define z_crc32_combine z_crc32_combine64
1897 #    define z_crc32_combine_gen z_crc32_combine_gen64
1898 #  else
1899 #    define gzopen gzopen64
1900 #    define gzseek gzseek64
1901 #    define gztell gztell64
1902 #    define gzoffset gzoffset64
1903 #    define adler32_combine adler32_combine64
1904 #    define crc32_combine crc32_combine64
1905 #    define crc32_combine_gen crc32_combine_gen64
1906 #  endif
1907 #  ifndef Z_LARGE64
1908      ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1909      ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1910      ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1911      ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1912      ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1913      ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1914      ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off_t));
1915 #  endif
1916 #else
1917    ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1918    ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1919    ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1920    ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1921    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1922    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1923    ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t));
1924 #endif
1925 
1926 #else /* Z_SOLO */
1927 
1928    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1929    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1930    ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t));
1931 
1932 #endif /* !Z_SOLO */
1933 
1934 /* undocumented functions */
1935 ZEXTERN const char   * ZEXPORT zError           OF((int));
1936 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
1937 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
1938 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
1939 ZEXTERN int            ZEXPORT inflateValidate OF((z_streamp, int));
1940 ZEXTERN unsigned long  ZEXPORT inflateCodesUsed OF((z_streamp));
1941 ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
1942 ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
1943 #if defined(_WIN32) && !defined(Z_SOLO)
1944 ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
1945                                             const char *mode));
1946 #endif
1947 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1948 #  ifndef Z_SOLO
1949 ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
1950                                                   const char *format,
1951                                                   va_list va));
1952 #  endif
1953 #endif
1954 
1955 #ifdef __cplusplus
1956 }
1957 #endif
1958 
1959 #endif /* ZLIB_H */