1 /*
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  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
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  24 
  25 /* zlib.h -- interface of the 'zlib' general purpose compression library
  26   version 1.3.1, January 22nd, 2024
  27 
  28   Copyright (C) 1995-2024 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 "1.3.1"
  65 #define ZLIB_VERNUM 0x1310
  66 #define ZLIB_VER_MAJOR 1
  67 #define ZLIB_VER_MINOR 3
  68 #define ZLIB_VER_REVISION 1
  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)(voidpf opaque, uInt items, uInt size);
 106 typedef void   (*free_func)(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(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(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.  total_in, total_out, adler, and msg are initialized.
 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(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 when the flush marker begins, in order to avoid
 348   repeated flush markers upon calling deflate() again when avail_out == 0.
 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(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(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.  total_in, total_out, adler, and
 411    msg are initialized.
 412 
 413      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
 414    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 415    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
 416    invalid, such as a null pointer to the structure.  msg is set to null if
 417    there is no error message.  inflateInit does not perform any decompression.
 418    Actual decompression will be done by inflate().  So next_in, and avail_in,
 419    next_out, and avail_out are unused and unchanged.  The current
 420    implementation of inflateInit() does not process any header information --
 421    that is deferred until inflate() is called.
 422 */
 423 
 424 
 425 ZEXTERN int ZEXPORT inflate(z_streamp strm, int flush);
 426 /*
 427     inflate decompresses as much data as possible, and stops when the input
 428   buffer becomes empty or the output buffer becomes full.  It may introduce
 429   some output latency (reading input without producing any output) except when
 430   forced to flush.
 431 
 432   The detailed semantics are as follows.  inflate performs one or both of the
 433   following actions:
 434 
 435   - Decompress more input starting at next_in and update next_in and avail_in
 436     accordingly.  If not all input can be processed (because there is not
 437     enough room in the output buffer), then next_in and avail_in are updated
 438     accordingly, and processing will resume at this point for the next call of
 439     inflate().
 440 
 441   - Generate more output starting at next_out and update next_out and avail_out
 442     accordingly.  inflate() provides as much output as possible, until there is
 443     no more input data or no more space in the output buffer (see below about
 444     the flush parameter).
 445 
 446     Before the call of inflate(), the application should ensure that at least
 447   one of the actions is possible, by providing more input and/or consuming more
 448   output, and updating the next_* and avail_* values accordingly.  If the
 449   caller of inflate() does not provide both available input and available
 450   output space, it is possible that there will be no progress made.  The
 451   application can consume the uncompressed output when it wants, for example
 452   when the output buffer is full (avail_out == 0), or after each call of
 453   inflate().  If inflate returns Z_OK and with zero avail_out, it must be
 454   called again after making room in the output buffer because there might be
 455   more output pending.
 456 
 457     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
 458   Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
 459   output as possible to the output buffer.  Z_BLOCK requests that inflate()
 460   stop if and when it gets to the next deflate block boundary.  When decoding
 461   the zlib or gzip format, this will cause inflate() to return immediately
 462   after the header and before the first block.  When doing a raw inflate,
 463   inflate() will go ahead and process the first block, and will return when it
 464   gets to the end of that block, or when it runs out of data.
 465 
 466     The Z_BLOCK option assists in appending to or combining deflate streams.
 467   To assist in this, on return inflate() always sets strm->data_type to the
 468   number of unused bits in the last byte taken from strm->next_in, plus 64 if
 469   inflate() is currently decoding the last block in the deflate stream, plus
 470   128 if inflate() returned immediately after decoding an end-of-block code or
 471   decoding the complete header up to just before the first byte of the deflate
 472   stream.  The end-of-block will not be indicated until all of the uncompressed
 473   data from that block has been written to strm->next_out.  The number of
 474   unused bits may in general be greater than seven, except when bit 7 of
 475   data_type is set, in which case the number of unused bits will be less than
 476   eight.  data_type is set as noted here every time inflate() returns for all
 477   flush options, and so can be used to determine the amount of currently
 478   consumed input in bits.
 479 
 480     The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
 481   end of each deflate block header is reached, before any actual data in that
 482   block is decoded.  This allows the caller to determine the length of the
 483   deflate block header for later use in random access within a deflate block.
 484   256 is added to the value of strm->data_type when inflate() returns
 485   immediately after reaching the end of the deflate block header.
 486 
 487     inflate() should normally be called until it returns Z_STREAM_END or an
 488   error.  However if all decompression is to be performed in a single step (a
 489   single call of inflate), the parameter flush should be set to Z_FINISH.  In
 490   this case all pending input is processed and all pending output is flushed;
 491   avail_out must be large enough to hold all of the uncompressed data for the
 492   operation to complete.  (The size of the uncompressed data may have been
 493   saved by the compressor for this purpose.)  The use of Z_FINISH is not
 494   required to perform an inflation in one step.  However it may be used to
 495   inform inflate that a faster approach can be used for the single inflate()
 496   call.  Z_FINISH also informs inflate to not maintain a sliding window if the
 497   stream completes, which reduces inflate's memory footprint.  If the stream
 498   does not complete, either because not all of the stream is provided or not
 499   enough output space is provided, then a sliding window will be allocated and
 500   inflate() can be called again to continue the operation as if Z_NO_FLUSH had
 501   been used.
 502 
 503      In this implementation, inflate() always flushes as much output as
 504   possible to the output buffer, and always uses the faster approach on the
 505   first call.  So the effects of the flush parameter in this implementation are
 506   on the return value of inflate() as noted below, when inflate() returns early
 507   when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
 508   memory for a sliding window when Z_FINISH is used.
 509 
 510      If a preset dictionary is needed after this call (see inflateSetDictionary
 511   below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
 512   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
 513   strm->adler to the Adler-32 checksum of all output produced so far (that is,
 514   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
 515   below.  At the end of the stream, inflate() checks that its computed Adler-32
 516   checksum is equal to that saved by the compressor and returns Z_STREAM_END
 517   only if the checksum is correct.
 518 
 519     inflate() can decompress and check either zlib-wrapped or gzip-wrapped
 520   deflate data.  The header type is detected automatically, if requested when
 521   initializing with inflateInit2().  Any information contained in the gzip
 522   header is not retained unless inflateGetHeader() is used.  When processing
 523   gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
 524   produced so far.  The CRC-32 is checked against the gzip trailer, as is the
 525   uncompressed length, modulo 2^32.
 526 
 527     inflate() returns Z_OK if some progress has been made (more input processed
 528   or more output produced), Z_STREAM_END if the end of the compressed data has
 529   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
 530   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
 531   corrupted (input stream not conforming to the zlib format or incorrect check
 532   value, in which case strm->msg points to a string with a more specific
 533   error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
 534   next_in or next_out was Z_NULL, or the state was inadvertently written over
 535   by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
 536   if no progress was possible or if there was not enough room in the output
 537   buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
 538   inflate() can be called again with more input and more output space to
 539   continue decompressing.  If Z_DATA_ERROR is returned, the application may
 540   then call inflateSync() to look for a good compression block if a partial
 541   recovery of the data is to be attempted.
 542 */
 543 
 544 
 545 ZEXTERN int ZEXPORT inflateEnd(z_streamp strm);
 546 /*
 547      All dynamically allocated data structures for this stream are freed.
 548    This function discards any unprocessed input and does not flush any pending
 549    output.
 550 
 551      inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
 552    was inconsistent.
 553 */
 554 
 555 
 556                         /* Advanced functions */
 557 
 558 /*
 559     The following functions are needed only in some special applications.
 560 */
 561 
 562 /*
 563 ZEXTERN int ZEXPORT deflateInit2(z_streamp strm,
 564                                  int level,
 565                                  int method,
 566                                  int windowBits,
 567                                  int memLevel,
 568                                  int strategy);
 569 
 570      This is another version of deflateInit with more compression options.  The
 571    fields zalloc, zfree and opaque must be initialized before by the caller.
 572 
 573      The method parameter is the compression method.  It must be Z_DEFLATED in
 574    this version of the library.
 575 
 576      The windowBits parameter is the base two logarithm of the window size
 577    (the size of the history buffer).  It should be in the range 8..15 for this
 578    version of the library.  Larger values of this parameter result in better
 579    compression at the expense of memory usage.  The default value is 15 if
 580    deflateInit is used instead.
 581 
 582      For the current implementation of deflate(), a windowBits value of 8 (a
 583    window size of 256 bytes) is not supported.  As a result, a request for 8
 584    will result in 9 (a 512-byte window).  In that case, providing 8 to
 585    inflateInit2() will result in an error when the zlib header with 9 is
 586    checked against the initialization of inflate().  The remedy is to not use 8
 587    with deflateInit2() with this initialization, or at least in that case use 9
 588    with inflateInit2().
 589 
 590      windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
 591    determines the window size.  deflate() will then generate raw deflate data
 592    with no zlib header or trailer, and will not compute a check value.
 593 
 594      windowBits can also be greater than 15 for optional gzip encoding.  Add
 595    16 to windowBits to write a simple gzip header and trailer around the
 596    compressed data instead of a zlib wrapper.  The gzip header will have no
 597    file name, no extra data, no comment, no modification time (set to zero), no
 598    header crc, and the operating system will be set to the appropriate value,
 599    if the operating system was determined at compile time.  If a gzip stream is
 600    being written, strm->adler is a CRC-32 instead of an Adler-32.
 601 
 602      For raw deflate or gzip encoding, a request for a 256-byte window is
 603    rejected as invalid, since only the zlib header provides a means of
 604    transmitting the window size to the decompressor.
 605 
 606      The memLevel parameter specifies how much memory should be allocated
 607    for the internal compression state.  memLevel=1 uses minimum memory but is
 608    slow and reduces compression ratio; memLevel=9 uses maximum memory for
 609    optimal speed.  The default value is 8.  See zconf.h for total memory usage
 610    as a function of windowBits and memLevel.
 611 
 612      The strategy parameter is used to tune the compression algorithm.  Use the
 613    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
 614    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
 615    string match), or Z_RLE to limit match distances to one (run-length
 616    encoding).  Filtered data consists mostly of small values with a somewhat
 617    random distribution.  In this case, the compression algorithm is tuned to
 618    compress them better.  The effect of Z_FILTERED is to force more Huffman
 619    coding and less string matching; it is somewhat intermediate between
 620    Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
 621    fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
 622    strategy parameter only affects the compression ratio but not the
 623    correctness of the compressed output even if it is not set appropriately.
 624    Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
 625    decoder for special applications.
 626 
 627      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 628    memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
 629    method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
 630    incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
 631    set to null if there is no error message.  deflateInit2 does not perform any
 632    compression: this will be done by deflate().
 633 */
 634 
 635 ZEXTERN int ZEXPORT deflateSetDictionary(z_streamp strm,
 636                                          const Bytef *dictionary,
 637                                          uInt  dictLength);
 638 /*
 639      Initializes the compression dictionary from the given byte sequence
 640    without producing any compressed output.  When using the zlib format, this
 641    function must be called immediately after deflateInit, deflateInit2 or
 642    deflateReset, and before any call of deflate.  When doing raw deflate, this
 643    function must be called either before any call of deflate, or immediately
 644    after the completion of a deflate block, i.e. after all input has been
 645    consumed and all output has been delivered when using any of the flush
 646    options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
 647    compressor and decompressor must use exactly the same dictionary (see
 648    inflateSetDictionary).
 649 
 650      The dictionary should consist of strings (byte sequences) that are likely
 651    to be encountered later in the data to be compressed, with the most commonly
 652    used strings preferably put towards the end of the dictionary.  Using a
 653    dictionary is most useful when the data to be compressed is short and can be
 654    predicted with good accuracy; the data can then be compressed better than
 655    with the default empty dictionary.
 656 
 657      Depending on the size of the compression data structures selected by
 658    deflateInit or deflateInit2, a part of the dictionary may in effect be
 659    discarded, for example if the dictionary is larger than the window size
 660    provided in deflateInit or deflateInit2.  Thus the strings most likely to be
 661    useful should be put at the end of the dictionary, not at the front.  In
 662    addition, the current implementation of deflate will use at most the window
 663    size minus 262 bytes of the provided dictionary.
 664 
 665      Upon return of this function, strm->adler is set to the Adler-32 value
 666    of the dictionary; the decompressor may later use this value to determine
 667    which dictionary has been used by the compressor.  (The Adler-32 value
 668    applies to the whole dictionary even if only a subset of the dictionary is
 669    actually used by the compressor.) If a raw deflate was requested, then the
 670    Adler-32 value is not computed and strm->adler is not set.
 671 
 672      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
 673    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
 674    inconsistent (for example if deflate has already been called for this stream
 675    or if not at a block boundary for raw deflate).  deflateSetDictionary does
 676    not perform any compression: this will be done by deflate().
 677 */
 678 
 679 ZEXTERN int ZEXPORT deflateGetDictionary(z_streamp strm,
 680                                          Bytef *dictionary,
 681                                          uInt  *dictLength);
 682 /*
 683      Returns the sliding dictionary being maintained by deflate.  dictLength is
 684    set to the number of bytes in the dictionary, and that many bytes are copied
 685    to dictionary.  dictionary must have enough space, where 32768 bytes is
 686    always enough.  If deflateGetDictionary() is called with dictionary equal to
 687    Z_NULL, then only the dictionary length is returned, and nothing is copied.
 688    Similarly, if dictLength is Z_NULL, then it is not set.
 689 
 690      deflateGetDictionary() may return a length less than the window size, even
 691    when more than the window size in input has been provided. It may return up
 692    to 258 bytes less in that case, due to how zlib's implementation of deflate
 693    manages the sliding window and lookahead for matches, where matches can be
 694    up to 258 bytes long. If the application needs the last window-size bytes of
 695    input, then that would need to be saved by the application outside of zlib.
 696 
 697      deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
 698    stream state is inconsistent.
 699 */
 700 
 701 ZEXTERN int ZEXPORT deflateCopy(z_streamp dest,
 702                                 z_streamp source);
 703 /*
 704      Sets the destination stream as a complete copy of the source stream.
 705 
 706      This function can be useful when several compression strategies will be
 707    tried, for example when there are several ways of pre-processing the input
 708    data with a filter.  The streams that will be discarded should then be freed
 709    by calling deflateEnd.  Note that deflateCopy duplicates the internal
 710    compression state which can be quite large, so this strategy is slow and can
 711    consume lots of memory.
 712 
 713      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 714    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 715    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
 716    destination.
 717 */
 718 
 719 ZEXTERN int ZEXPORT deflateReset(z_streamp strm);
 720 /*
 721      This function is equivalent to deflateEnd followed by deflateInit, but
 722    does not free and reallocate the internal compression state.  The stream
 723    will leave the compression level and any other attributes that may have been
 724    set unchanged.  total_in, total_out, adler, and msg are initialized.
 725 
 726      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 727    stream state was inconsistent (such as zalloc or state being Z_NULL).
 728 */
 729 
 730 ZEXTERN int ZEXPORT deflateParams(z_streamp strm,
 731                                   int level,
 732                                   int strategy);
 733 /*
 734      Dynamically update the compression level and compression strategy.  The
 735    interpretation of level and strategy is as in deflateInit2().  This can be
 736    used to switch between compression and straight copy of the input data, or
 737    to switch to a different kind of input data requiring a different strategy.
 738    If the compression approach (which is a function of the level) or the
 739    strategy is changed, and if there have been any deflate() calls since the
 740    state was initialized or reset, then the input available so far is
 741    compressed with the old level and strategy using deflate(strm, Z_BLOCK).
 742    There are three approaches for the compression levels 0, 1..3, and 4..9
 743    respectively.  The new level and strategy will take effect at the next call
 744    of deflate().
 745 
 746      If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
 747    not have enough output space to complete, then the parameter change will not
 748    take effect.  In this case, deflateParams() can be called again with the
 749    same parameters and more output space to try again.
 750 
 751      In order to assure a change in the parameters on the first try, the
 752    deflate stream should be flushed using deflate() with Z_BLOCK or other flush
 753    request until strm.avail_out is not zero, before calling deflateParams().
 754    Then no more input data should be provided before the deflateParams() call.
 755    If this is done, the old level and strategy will be applied to the data
 756    compressed before deflateParams(), and the new level and strategy will be
 757    applied to the data compressed after deflateParams().
 758 
 759      deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
 760    state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
 761    there was not enough output space to complete the compression of the
 762    available input data before a change in the strategy or approach.  Note that
 763    in the case of a Z_BUF_ERROR, the parameters are not changed.  A return
 764    value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
 765    retried with more output space.
 766 */
 767 
 768 ZEXTERN int ZEXPORT deflateTune(z_streamp strm,
 769                                 int good_length,
 770                                 int max_lazy,
 771                                 int nice_length,
 772                                 int max_chain);
 773 /*
 774      Fine tune deflate's internal compression parameters.  This should only be
 775    used by someone who understands the algorithm used by zlib's deflate for
 776    searching for the best matching string, and even then only by the most
 777    fanatic optimizer trying to squeeze out the last compressed bit for their
 778    specific input data.  Read the deflate.c source code for the meaning of the
 779    max_lazy, good_length, nice_length, and max_chain parameters.
 780 
 781      deflateTune() can be called after deflateInit() or deflateInit2(), and
 782    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
 783  */
 784 
 785 ZEXTERN uLong ZEXPORT deflateBound(z_streamp strm,
 786                                    uLong sourceLen);
 787 /*
 788      deflateBound() returns an upper bound on the compressed size after
 789    deflation of sourceLen bytes.  It must be called after deflateInit() or
 790    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
 791    to allocate an output buffer for deflation in a single pass, and so would be
 792    called before deflate().  If that first deflate() call is provided the
 793    sourceLen input bytes, an output buffer allocated to the size returned by
 794    deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
 795    to return Z_STREAM_END.  Note that it is possible for the compressed size to
 796    be larger than the value returned by deflateBound() if flush options other
 797    than Z_FINISH or Z_NO_FLUSH are used.
 798 */
 799 
 800 ZEXTERN int ZEXPORT deflatePending(z_streamp strm,
 801                                    unsigned *pending,
 802                                    int *bits);
 803 /*
 804      deflatePending() returns the number of bytes and bits of output that have
 805    been generated, but not yet provided in the available output.  The bytes not
 806    provided would be due to the available output space having being consumed.
 807    The number of bits of output not provided are between 0 and 7, where they
 808    await more bits to join them in order to fill out a full byte.  If pending
 809    or bits are Z_NULL, then those values are not set.
 810 
 811      deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
 812    stream state was inconsistent.
 813  */
 814 
 815 ZEXTERN int ZEXPORT deflatePrime(z_streamp strm,
 816                                  int bits,
 817                                  int value);
 818 /*
 819      deflatePrime() inserts bits in the deflate output stream.  The intent
 820    is that this function is used to start off the deflate output with the bits
 821    leftover from a previous deflate stream when appending to it.  As such, this
 822    function can only be used for raw deflate, and must be used before the first
 823    deflate() call after a deflateInit2() or deflateReset().  bits must be less
 824    than or equal to 16, and that many of the least significant bits of value
 825    will be inserted in the output.
 826 
 827      deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
 828    room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
 829    source stream state was inconsistent.
 830 */
 831 
 832 ZEXTERN int ZEXPORT deflateSetHeader(z_streamp strm,
 833                                      gz_headerp head);
 834 /*
 835      deflateSetHeader() provides gzip header information for when a gzip
 836    stream is requested by deflateInit2().  deflateSetHeader() may be called
 837    after deflateInit2() or deflateReset() and before the first call of
 838    deflate().  The text, time, os, extra field, name, and comment information
 839    in the provided gz_header structure are written to the gzip header (xflag is
 840    ignored -- the extra flags are set according to the compression level).  The
 841    caller must assure that, if not Z_NULL, name and comment are terminated with
 842    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
 843    available there.  If hcrc is true, a gzip header crc is included.  Note that
 844    the current versions of the command-line version of gzip (up through version
 845    1.3.x) do not support header crc's, and will report that it is a "multi-part
 846    gzip file" and give up.
 847 
 848      If deflateSetHeader is not used, the default gzip header has text false,
 849    the time set to zero, and os set to the current operating system, with no
 850    extra, name, or comment fields.  The gzip header is returned to the default
 851    state by deflateReset().
 852 
 853      deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
 854    stream state was inconsistent.
 855 */
 856 
 857 /*
 858 ZEXTERN int ZEXPORT inflateInit2(z_streamp strm,
 859                                  int windowBits);
 860 
 861      This is another version of inflateInit with an extra parameter.  The
 862    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
 863    before by the caller.
 864 
 865      The windowBits parameter is the base two logarithm of the maximum window
 866    size (the size of the history buffer).  It should be in the range 8..15 for
 867    this version of the library.  The default value is 15 if inflateInit is used
 868    instead.  windowBits must be greater than or equal to the windowBits value
 869    provided to deflateInit2() while compressing, or it must be equal to 15 if
 870    deflateInit2() was not used.  If a compressed stream with a larger window
 871    size is given as input, inflate() will return with the error code
 872    Z_DATA_ERROR instead of trying to allocate a larger window.
 873 
 874      windowBits can also be zero to request that inflate use the window size in
 875    the zlib header of the compressed stream.
 876 
 877      windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
 878    determines the window size.  inflate() will then process raw deflate data,
 879    not looking for a zlib or gzip header, not generating a check value, and not
 880    looking for any check values for comparison at the end of the stream.  This
 881    is for use with other formats that use the deflate compressed data format
 882    such as zip.  Those formats provide their own check values.  If a custom
 883    format is developed using the raw deflate format for compressed data, it is
 884    recommended that a check value such as an Adler-32 or a CRC-32 be applied to
 885    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
 886    most applications, the zlib format should be used as is.  Note that comments
 887    above on the use in deflateInit2() applies to the magnitude of windowBits.
 888 
 889      windowBits can also be greater than 15 for optional gzip decoding.  Add
 890    32 to windowBits to enable zlib and gzip decoding with automatic header
 891    detection, or add 16 to decode only the gzip format (the zlib format will
 892    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
 893    CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
 894    below), inflate() will *not* automatically decode concatenated gzip members.
 895    inflate() will return Z_STREAM_END at the end of the gzip member.  The state
 896    would need to be reset to continue decoding a subsequent gzip member.  This
 897    *must* be done if there is more data after a gzip member, in order for the
 898    decompression to be compliant with the gzip standard (RFC 1952).
 899 
 900      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 901    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
 902    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
 903    invalid, such as a null pointer to the structure.  msg is set to null if
 904    there is no error message.  inflateInit2 does not perform any decompression
 905    apart from possibly reading the zlib header if present: actual decompression
 906    will be done by inflate().  (So next_in and avail_in may be modified, but
 907    next_out and avail_out are unused and unchanged.) The current implementation
 908    of inflateInit2() does not process any header information -- that is
 909    deferred until inflate() is called.
 910 */
 911 
 912 ZEXTERN int ZEXPORT inflateSetDictionary(z_streamp strm,
 913                                          const Bytef *dictionary,
 914                                          uInt  dictLength);
 915 /*
 916      Initializes the decompression dictionary from the given uncompressed byte
 917    sequence.  This function must be called immediately after a call of inflate,
 918    if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
 919    can be determined from the Adler-32 value returned by that call of inflate.
 920    The compressor and decompressor must use exactly the same dictionary (see
 921    deflateSetDictionary).  For raw inflate, this function can be called at any
 922    time to set the dictionary.  If the provided dictionary is smaller than the
 923    window and there is already data in the window, then the provided dictionary
 924    will amend what's there.  The application must insure that the dictionary
 925    that was used for compression is provided.
 926 
 927      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
 928    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
 929    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
 930    expected one (incorrect Adler-32 value).  inflateSetDictionary does not
 931    perform any decompression: this will be done by subsequent calls of
 932    inflate().
 933 */
 934 
 935 ZEXTERN int ZEXPORT inflateGetDictionary(z_streamp strm,
 936                                          Bytef *dictionary,
 937                                          uInt  *dictLength);
 938 /*
 939      Returns the sliding dictionary being maintained by inflate.  dictLength is
 940    set to the number of bytes in the dictionary, and that many bytes are copied
 941    to dictionary.  dictionary must have enough space, where 32768 bytes is
 942    always enough.  If inflateGetDictionary() is called with dictionary equal to
 943    Z_NULL, then only the dictionary length is returned, and nothing is copied.
 944    Similarly, if dictLength is Z_NULL, then it is not set.
 945 
 946      inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
 947    stream state is inconsistent.
 948 */
 949 
 950 ZEXTERN int ZEXPORT inflateSync(z_streamp strm);
 951 /*
 952      Skips invalid compressed data until a possible full flush point (see above
 953    for the description of deflate with Z_FULL_FLUSH) can be found, or until all
 954    available input is skipped.  No output is provided.
 955 
 956      inflateSync searches for a 00 00 FF FF pattern in the compressed data.
 957    All full flush points have this pattern, but not all occurrences of this
 958    pattern are full flush points.
 959 
 960      inflateSync returns Z_OK if a possible full flush point has been found,
 961    Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
 962    has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
 963    In the success case, the application may save the current value of total_in
 964    which indicates where valid compressed data was found.  In the error case,
 965    the application may repeatedly call inflateSync, providing more input each
 966    time, until success or end of the input data.
 967 */
 968 
 969 ZEXTERN int ZEXPORT inflateCopy(z_streamp dest,
 970                                 z_streamp source);
 971 /*
 972      Sets the destination stream as a complete copy of the source stream.
 973 
 974      This function can be useful when randomly accessing a large stream.  The
 975    first pass through the stream can periodically record the inflate state,
 976    allowing restarting inflate at those points when randomly accessing the
 977    stream.
 978 
 979      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
 980    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
 981    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
 982    destination.
 983 */
 984 
 985 ZEXTERN int ZEXPORT inflateReset(z_streamp strm);
 986 /*
 987      This function is equivalent to inflateEnd followed by inflateInit,
 988    but does not free and reallocate the internal decompression state.  The
 989    stream will keep attributes that may have been set by inflateInit2.
 990    total_in, total_out, adler, and msg are initialized.
 991 
 992      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
 993    stream state was inconsistent (such as zalloc or state being Z_NULL).
 994 */
 995 
 996 ZEXTERN int ZEXPORT inflateReset2(z_streamp strm,
 997                                   int windowBits);
 998 /*
 999      This function is the same as inflateReset, but it also permits changing
1000    the wrap and window size requests.  The windowBits parameter is interpreted
1001    the same as it is for inflateInit2.  If the window size is changed, then the
1002    memory allocated for the window is freed, and the window will be reallocated
1003    by inflate() if needed.
1004 
1005      inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
1006    stream state was inconsistent (such as zalloc or state being Z_NULL), or if
1007    the windowBits parameter is invalid.
1008 */
1009 
1010 ZEXTERN int ZEXPORT inflatePrime(z_streamp strm,
1011                                  int bits,
1012                                  int value);
1013 /*
1014      This function inserts bits in the inflate input stream.  The intent is
1015    that this function is used to start inflating at a bit position in the
1016    middle of a byte.  The provided bits will be used before any bytes are used
1017    from next_in.  This function should only be used with raw inflate, and
1018    should be used before the first inflate() call after inflateInit2() or
1019    inflateReset().  bits must be less than or equal to 16, and that many of the
1020    least significant bits of value will be inserted in the input.
1021 
1022      If bits is negative, then the input stream bit buffer is emptied.  Then
1023    inflatePrime() can be called again to put bits in the buffer.  This is used
1024    to clear out bits leftover after feeding inflate a block description prior
1025    to feeding inflate codes.
1026 
1027      inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1028    stream state was inconsistent.
1029 */
1030 
1031 ZEXTERN long ZEXPORT inflateMark(z_streamp strm);
1032 /*
1033      This function returns two values, one in the lower 16 bits of the return
1034    value, and the other in the remaining upper bits, obtained by shifting the
1035    return value down 16 bits.  If the upper value is -1 and the lower value is
1036    zero, then inflate() is currently decoding information outside of a block.
1037    If the upper value is -1 and the lower value is non-zero, then inflate is in
1038    the middle of a stored block, with the lower value equaling the number of
1039    bytes from the input remaining to copy.  If the upper value is not -1, then
1040    it is the number of bits back from the current bit position in the input of
1041    the code (literal or length/distance pair) currently being processed.  In
1042    that case the lower value is the number of bytes already emitted for that
1043    code.
1044 
1045      A code is being processed if inflate is waiting for more input to complete
1046    decoding of the code, or if it has completed decoding but is waiting for
1047    more output space to write the literal or match data.
1048 
1049      inflateMark() is used to mark locations in the input data for random
1050    access, which may be at bit positions, and to note those cases where the
1051    output of a code may span boundaries of random access blocks.  The current
1052    location in the input stream can be determined from avail_in and data_type
1053    as noted in the description for the Z_BLOCK flush parameter for inflate.
1054 
1055      inflateMark returns the value noted above, or -65536 if the provided
1056    source stream state was inconsistent.
1057 */
1058 
1059 ZEXTERN int ZEXPORT inflateGetHeader(z_streamp strm,
1060                                      gz_headerp head);
1061 /*
1062      inflateGetHeader() requests that gzip header information be stored in the
1063    provided gz_header structure.  inflateGetHeader() may be called after
1064    inflateInit2() or inflateReset(), and before the first call of inflate().
1065    As inflate() processes the gzip stream, head->done is zero until the header
1066    is completed, at which time head->done is set to one.  If a zlib stream is
1067    being decoded, then head->done is set to -1 to indicate that there will be
1068    no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
1069    used to force inflate() to return immediately after header processing is
1070    complete and before any actual data is decompressed.
1071 
1072      The text, time, xflags, and os fields are filled in with the gzip header
1073    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
1074    was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1075    contains the maximum number of bytes to write to extra.  Once done is true,
1076    extra_len contains the actual extra field length, and extra contains the
1077    extra field, or that field truncated if extra_max is less than extra_len.
1078    If name is not Z_NULL, then up to name_max characters are written there,
1079    terminated with a zero unless the length is greater than name_max.  If
1080    comment is not Z_NULL, then up to comm_max characters are written there,
1081    terminated with a zero unless the length is greater than comm_max.  When any
1082    of extra, name, or comment are not Z_NULL and the respective field is not
1083    present in the header, then that field is set to Z_NULL to signal its
1084    absence.  This allows the use of deflateSetHeader() with the returned
1085    structure to duplicate the header.  However if those fields are set to
1086    allocated memory, then the application will need to save those pointers
1087    elsewhere so that they can be eventually freed.
1088 
1089      If inflateGetHeader is not used, then the header information is simply
1090    discarded.  The header is always checked for validity, including the header
1091    CRC if present.  inflateReset() will reset the process to discard the header
1092    information.  The application would need to call inflateGetHeader() again to
1093    retrieve the header from the next gzip stream.
1094 
1095      inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1096    stream state was inconsistent.
1097 */
1098 
1099 /*
1100 ZEXTERN int ZEXPORT inflateBackInit(z_streamp strm, int windowBits,
1101                                     unsigned char FAR *window);
1102 
1103      Initialize the internal stream state for decompression using inflateBack()
1104    calls.  The fields zalloc, zfree and opaque in strm must be initialized
1105    before the call.  If zalloc and zfree are Z_NULL, then the default library-
1106    derived memory allocation routines are used.  windowBits is the base two
1107    logarithm of the window size, in the range 8..15.  window is a caller
1108    supplied buffer of that size.  Except for special applications where it is
1109    assured that deflate was used with small window sizes, windowBits must be 15
1110    and a 32K byte window must be supplied to be able to decompress general
1111    deflate streams.
1112 
1113      See inflateBack() for the usage of these routines.
1114 
1115      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1116    the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1117    allocated, or Z_VERSION_ERROR if the version of the library does not match
1118    the version of the header file.
1119 */
1120 
1121 typedef unsigned (*in_func)(void FAR *,
1122                             z_const unsigned char FAR * FAR *);
1123 typedef int (*out_func)(void FAR *, unsigned char FAR *, unsigned);
1124 
1125 ZEXTERN int ZEXPORT inflateBack(z_streamp strm,
1126                                 in_func in, void FAR *in_desc,
1127                                 out_func out, void FAR *out_desc);
1128 /*
1129      inflateBack() does a raw inflate with a single call using a call-back
1130    interface for input and output.  This is potentially more efficient than
1131    inflate() for file i/o applications, in that it avoids copying between the
1132    output and the sliding window by simply making the window itself the output
1133    buffer.  inflate() can be faster on modern CPUs when used with large
1134    buffers.  inflateBack() trusts the application to not change the output
1135    buffer passed by the output function, at least until inflateBack() returns.
1136 
1137      inflateBackInit() must be called first to allocate the internal state
1138    and to initialize the state with the user-provided window buffer.
1139    inflateBack() may then be used multiple times to inflate a complete, raw
1140    deflate stream with each call.  inflateBackEnd() is then called to free the
1141    allocated state.
1142 
1143      A raw deflate stream is one with no zlib or gzip header or trailer.
1144    This routine would normally be used in a utility that reads zip or gzip
1145    files and writes out uncompressed files.  The utility would decode the
1146    header and process the trailer on its own, hence this routine expects only
1147    the raw deflate stream to decompress.  This is different from the default
1148    behavior of inflate(), which expects a zlib header and trailer around the
1149    deflate stream.
1150 
1151      inflateBack() uses two subroutines supplied by the caller that are then
1152    called by inflateBack() for input and output.  inflateBack() calls those
1153    routines until it reads a complete deflate stream and writes out all of the
1154    uncompressed data, or until it encounters an error.  The function's
1155    parameters and return types are defined above in the in_func and out_func
1156    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
1157    number of bytes of provided input, and a pointer to that input in buf.  If
1158    there is no input available, in() must return zero -- buf is ignored in that
1159    case -- and inflateBack() will return a buffer error.  inflateBack() will
1160    call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
1161    out() should return zero on success, or non-zero on failure.  If out()
1162    returns non-zero, inflateBack() will return with an error.  Neither in() nor
1163    out() are permitted to change the contents of the window provided to
1164    inflateBackInit(), which is also the buffer that out() uses to write from.
1165    The length written by out() will be at most the window size.  Any non-zero
1166    amount of input may be provided by in().
1167 
1168      For convenience, inflateBack() can be provided input on the first call by
1169    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
1170    in() will be called.  Therefore strm->next_in must be initialized before
1171    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
1172    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
1173    must also be initialized, and then if strm->avail_in is not zero, input will
1174    initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
1175 
1176      The in_desc and out_desc parameters of inflateBack() is passed as the
1177    first parameter of in() and out() respectively when they are called.  These
1178    descriptors can be optionally used to pass any information that the caller-
1179    supplied in() and out() functions need to do their job.
1180 
1181      On return, inflateBack() will set strm->next_in and strm->avail_in to
1182    pass back any unused input that was provided by the last in() call.  The
1183    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1184    if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1185    in the deflate stream (in which case strm->msg is set to indicate the nature
1186    of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1187    In the case of Z_BUF_ERROR, an input or output error can be distinguished
1188    using strm->next_in which will be Z_NULL only if in() returned an error.  If
1189    strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1190    non-zero.  (in() will always be called before out(), so strm->next_in is
1191    assured to be defined if out() returns non-zero.)  Note that inflateBack()
1192    cannot return Z_OK.
1193 */
1194 
1195 ZEXTERN int ZEXPORT inflateBackEnd(z_streamp strm);
1196 /*
1197      All memory allocated by inflateBackInit() is freed.
1198 
1199      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1200    state was inconsistent.
1201 */
1202 
1203 ZEXTERN uLong ZEXPORT zlibCompileFlags(void);
1204 /* Return flags indicating compile-time options.
1205 
1206     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1207      1.0: size of uInt
1208      3.2: size of uLong
1209      5.4: size of voidpf (pointer)
1210      7.6: size of z_off_t
1211 
1212     Compiler, assembler, and debug options:
1213      8: ZLIB_DEBUG
1214      9: ASMV or ASMINF -- use ASM code
1215      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1216      11: 0 (reserved)
1217 
1218     One-time table building (smaller code, but not thread-safe if true):
1219      12: BUILDFIXED -- build static block decoding tables when needed
1220      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1221      14,15: 0 (reserved)
1222 
1223     Library content (indicates missing functionality):
1224      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1225                           deflate code when not needed)
1226      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1227                     and decode gzip streams (to avoid linking crc code)
1228      18-19: 0 (reserved)
1229 
1230     Operation variations (changes in library functionality):
1231      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1232      21: FASTEST -- deflate algorithm with only one, lowest compression level
1233      22,23: 0 (reserved)
1234 
1235     The sprintf variant used by gzprintf (zero is best):
1236      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1237      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1238      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1239 
1240     Remainder:
1241      27-31: 0 (reserved)
1242  */
1243 
1244 #ifndef Z_SOLO
1245 
1246                         /* utility functions */
1247 
1248 /*
1249      The following utility functions are implemented on top of the basic
1250    stream-oriented functions.  To simplify the interface, some default options
1251    are assumed (compression level and memory usage, standard memory allocation
1252    functions).  The source code of these utility functions can be modified if
1253    you need special options.
1254 */
1255 
1256 ZEXTERN int ZEXPORT compress(Bytef *dest,   uLongf *destLen,
1257                              const Bytef *source, uLong sourceLen);
1258 /*
1259      Compresses the source buffer into the destination buffer.  sourceLen is
1260    the byte length of the source buffer.  Upon entry, destLen is the total size
1261    of the destination buffer, which must be at least the value returned by
1262    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1263    compressed data.  compress() is equivalent to compress2() with a level
1264    parameter of Z_DEFAULT_COMPRESSION.
1265 
1266      compress returns Z_OK if success, Z_MEM_ERROR if there was not
1267    enough memory, Z_BUF_ERROR if there was not enough room in the output
1268    buffer.
1269 */
1270 
1271 ZEXTERN int ZEXPORT compress2(Bytef *dest,   uLongf *destLen,
1272                               const Bytef *source, uLong sourceLen,
1273                               int level);
1274 /*
1275      Compresses the source buffer into the destination buffer.  The level
1276    parameter has the same meaning as in deflateInit.  sourceLen is the byte
1277    length of the source buffer.  Upon entry, destLen is the total size of the
1278    destination buffer, which must be at least the value returned by
1279    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
1280    compressed data.
1281 
1282      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1283    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1284    Z_STREAM_ERROR if the level parameter is invalid.
1285 */
1286 
1287 ZEXTERN uLong ZEXPORT compressBound(uLong sourceLen);
1288 /*
1289      compressBound() returns an upper bound on the compressed size after
1290    compress() or compress2() on sourceLen bytes.  It would be used before a
1291    compress() or compress2() call to allocate the destination buffer.
1292 */
1293 
1294 ZEXTERN int ZEXPORT uncompress(Bytef *dest,   uLongf *destLen,
1295                                const Bytef *source, uLong sourceLen);
1296 /*
1297      Decompresses the source buffer into the destination buffer.  sourceLen is
1298    the byte length of the source buffer.  Upon entry, destLen is the total size
1299    of the destination buffer, which must be large enough to hold the entire
1300    uncompressed data.  (The size of the uncompressed data must have been saved
1301    previously by the compressor and transmitted to the decompressor by some
1302    mechanism outside the scope of this compression library.) Upon exit, destLen
1303    is the actual size of the uncompressed data.
1304 
1305      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1306    enough memory, Z_BUF_ERROR if there was not enough room in the output
1307    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
1308    the case where there is not enough room, uncompress() will fill the output
1309    buffer with the uncompressed data up to that point.
1310 */
1311 
1312 ZEXTERN int ZEXPORT uncompress2(Bytef *dest,   uLongf *destLen,
1313                                 const Bytef *source, uLong *sourceLen);
1314 /*
1315      Same as uncompress, except that sourceLen is a pointer, where the
1316    length of the source is *sourceLen.  On return, *sourceLen is the number of
1317    source bytes consumed.
1318 */
1319 
1320                         /* gzip file access functions */
1321 
1322 /*
1323      This library supports reading and writing files in gzip (.gz) format with
1324    an interface similar to that of stdio, using the functions that start with
1325    "gz".  The gzip format is different from the zlib format.  gzip is a gzip
1326    wrapper, documented in RFC 1952, wrapped around a deflate stream.
1327 */
1328 
1329 typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
1330 
1331 /*
1332 ZEXTERN gzFile ZEXPORT gzopen(const char *path, const char *mode);
1333 
1334      Open the gzip (.gz) file at path for reading and decompressing, or
1335    compressing and writing.  The mode parameter is as in fopen ("rb" or "wb")
1336    but can also include a compression level ("wb9") or a strategy: 'f' for
1337    filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
1338    'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
1339    as in "wb9F".  (See the description of deflateInit2 for more information
1340    about the strategy parameter.)  'T' will request transparent writing or
1341    appending with no compression and not using the gzip format.
1342 
1343      "a" can be used instead of "w" to request that the gzip stream that will
1344    be written be appended to the file.  "+" will result in an error, since
1345    reading and writing to the same gzip file is not supported.  The addition of
1346    "x" when writing will create the file exclusively, which fails if the file
1347    already exists.  On systems that support it, the addition of "e" when
1348    reading or writing will set the flag to close the file on an execve() call.
1349 
1350      These functions, as well as gzip, will read and decode a sequence of gzip
1351    streams in a file.  The append function of gzopen() can be used to create
1352    such a file.  (Also see gzflush() for another way to do this.)  When
1353    appending, gzopen does not test whether the file begins with a gzip stream,
1354    nor does it look for the end of the gzip streams to begin appending.  gzopen
1355    will simply append a gzip stream to the existing file.
1356 
1357      gzopen can be used to read a file which is not in gzip format; in this
1358    case gzread will directly read from the file without decompression.  When
1359    reading, this will be detected automatically by looking for the magic two-
1360    byte gzip header.
1361 
1362      gzopen returns NULL if the file could not be opened, if there was
1363    insufficient memory to allocate the gzFile state, or if an invalid mode was
1364    specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1365    errno can be checked to determine if the reason gzopen failed was that the
1366    file could not be opened.
1367 */
1368 
1369 ZEXTERN gzFile ZEXPORT gzdopen(int fd, const char *mode);
1370 /*
1371      Associate a gzFile with the file descriptor fd.  File descriptors are
1372    obtained from calls like open, dup, creat, pipe or fileno (if the file has
1373    been previously opened with fopen).  The mode parameter is as in gzopen.
1374 
1375      The next call of gzclose on the returned gzFile will also close the file
1376    descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1377    fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1378    mode);.  The duplicated descriptor should be saved to avoid a leak, since
1379    gzdopen does not close fd if it fails.  If you are using fileno() to get the
1380    file descriptor from a FILE *, then you will have to use dup() to avoid
1381    double-close()ing the file descriptor.  Both gzclose() and fclose() will
1382    close the associated file descriptor, so they need to have different file
1383    descriptors.
1384 
1385      gzdopen returns NULL if there was insufficient memory to allocate the
1386    gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1387    provided, or '+' was provided), or if fd is -1.  The file descriptor is not
1388    used until the next gz* read, write, seek, or close operation, so gzdopen
1389    will not detect if fd is invalid (unless fd is -1).
1390 */
1391 
1392 ZEXTERN int ZEXPORT gzbuffer(gzFile file, unsigned size);
1393 /*
1394      Set the internal buffer size used by this library's functions for file to
1395    size.  The default buffer size is 8192 bytes.  This function must be called
1396    after gzopen() or gzdopen(), and before any other calls that read or write
1397    the file.  The buffer memory allocation is always deferred to the first read
1398    or write.  Three times that size in buffer space is allocated.  A larger
1399    buffer size of, for example, 64K or 128K bytes will noticeably increase the
1400    speed of decompression (reading).
1401 
1402      The new buffer size also affects the maximum length for gzprintf().
1403 
1404      gzbuffer() returns 0 on success, or -1 on failure, such as being called
1405    too late.
1406 */
1407 
1408 ZEXTERN int ZEXPORT gzsetparams(gzFile file, int level, int strategy);
1409 /*
1410      Dynamically update the compression level and strategy for file.  See the
1411    description of deflateInit2 for the meaning of these parameters. Previously
1412    provided data is flushed before applying the parameter changes.
1413 
1414      gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1415    opened for writing, Z_ERRNO if there is an error writing the flushed data,
1416    or Z_MEM_ERROR if there is a memory allocation error.
1417 */
1418 
1419 ZEXTERN int ZEXPORT gzread(gzFile file, voidp buf, unsigned len);
1420 /*
1421      Read and decompress up to len uncompressed bytes from file into buf.  If
1422    the input file is not in gzip format, gzread copies the given number of
1423    bytes into the buffer directly from the file.
1424 
1425      After reaching the end of a gzip stream in the input, gzread will continue
1426    to read, looking for another gzip stream.  Any number of gzip streams may be
1427    concatenated in the input file, and will all be decompressed by gzread().
1428    If something other than a gzip stream is encountered after a gzip stream,
1429    that remaining trailing garbage is ignored (and no error is returned).
1430 
1431      gzread can be used to read a gzip file that is being concurrently written.
1432    Upon reaching the end of the input, gzread will return with the available
1433    data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1434    gzclearerr can be used to clear the end of file indicator in order to permit
1435    gzread to be tried again.  Z_OK indicates that a gzip stream was completed
1436    on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
1437    middle of a gzip stream.  Note that gzread does not return -1 in the event
1438    of an incomplete gzip stream.  This error is deferred until gzclose(), which
1439    will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1440    stream.  Alternatively, gzerror can be used before gzclose to detect this
1441    case.
1442 
1443      gzread returns the number of uncompressed bytes actually read, less than
1444    len for end of file, or -1 for error.  If len is too large to fit in an int,
1445    then nothing is read, -1 is returned, and the error state is set to
1446    Z_STREAM_ERROR.
1447 */
1448 
1449 ZEXTERN z_size_t ZEXPORT gzfread(voidp buf, z_size_t size, z_size_t nitems,
1450                                  gzFile file);
1451 /*
1452      Read and decompress up to nitems items of size size from file into buf,
1453    otherwise operating as gzread() does.  This duplicates the interface of
1454    stdio's fread(), with size_t request and return types.  If the library
1455    defines size_t, then z_size_t is identical to size_t.  If not, then z_size_t
1456    is an unsigned integer type that can contain a pointer.
1457 
1458      gzfread() returns the number of full items read of size size, or zero if
1459    the end of the file was reached and a full item could not be read, or if
1460    there was an error.  gzerror() must be consulted if zero is returned in
1461    order to determine if there was an error.  If the multiplication of size and
1462    nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1463    is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1464 
1465      In the event that the end of file is reached and only a partial item is
1466    available at the end, i.e. the remaining uncompressed data length is not a
1467    multiple of size, then the final partial item is nevertheless read into buf
1468    and the end-of-file flag is set.  The length of the partial item read is not
1469    provided, but could be inferred from the result of gztell().  This behavior
1470    is the same as the behavior of fread() implementations in common libraries,
1471    but it prevents the direct use of gzfread() to read a concurrently written
1472    file, resetting and retrying on end-of-file, when size is not 1.
1473 */
1474 
1475 ZEXTERN int ZEXPORT gzwrite(gzFile file, voidpc buf, unsigned len);
1476 /*
1477      Compress and write the len uncompressed bytes at buf to file. gzwrite
1478    returns the number of uncompressed bytes written or 0 in case of error.
1479 */
1480 
1481 ZEXTERN z_size_t ZEXPORT gzfwrite(voidpc buf, z_size_t size,
1482                                   z_size_t nitems, gzFile file);
1483 /*
1484      Compress and write nitems items of size size from buf to file, duplicating
1485    the interface of stdio's fwrite(), with size_t request and return types.  If
1486    the library defines size_t, then z_size_t is identical to size_t.  If not,
1487    then z_size_t is an unsigned integer type that can contain a pointer.
1488 
1489      gzfwrite() returns the number of full items written of size size, or zero
1490    if there was an error.  If the multiplication of size and nitems overflows,
1491    i.e. the product does not fit in a z_size_t, then nothing is written, zero
1492    is returned, and the error state is set to Z_STREAM_ERROR.
1493 */
1494 
1495 ZEXTERN int ZEXPORTVA gzprintf(gzFile file, const char *format, ...);
1496 /*
1497      Convert, format, compress, and write the arguments (...) to file under
1498    control of the string format, as in fprintf.  gzprintf returns the number of
1499    uncompressed bytes actually written, or a negative zlib error code in case
1500    of error.  The number of uncompressed bytes written is limited to 8191, or
1501    one less than the buffer size given to gzbuffer().  The caller should assure
1502    that this limit is not exceeded.  If it is exceeded, then gzprintf() will
1503    return an error (0) with nothing written.  In this case, there may also be a
1504    buffer overflow with unpredictable consequences, which is possible only if
1505    zlib was compiled with the insecure functions sprintf() or vsprintf(),
1506    because the secure snprintf() or vsnprintf() functions were not available.
1507    This can be determined using zlibCompileFlags().
1508 */
1509 
1510 ZEXTERN int ZEXPORT gzputs(gzFile file, const char *s);
1511 /*
1512      Compress and write the given null-terminated string s to file, excluding
1513    the terminating null character.
1514 
1515      gzputs returns the number of characters written, or -1 in case of error.
1516 */
1517 
1518 ZEXTERN char * ZEXPORT gzgets(gzFile file, char *buf, int len);
1519 /*
1520      Read and decompress bytes from file into buf, until len-1 characters are
1521    read, or until a newline character is read and transferred to buf, or an
1522    end-of-file condition is encountered.  If any characters are read or if len
1523    is one, the string is terminated with a null character.  If no characters
1524    are read due to an end-of-file or len is less than one, then the buffer is
1525    left untouched.
1526 
1527      gzgets returns buf which is a null-terminated string, or it returns NULL
1528    for end-of-file or in case of error.  If there was an error, the contents at
1529    buf are indeterminate.
1530 */
1531 
1532 ZEXTERN int ZEXPORT gzputc(gzFile file, int c);
1533 /*
1534      Compress and write c, converted to an unsigned char, into file.  gzputc
1535    returns the value that was written, or -1 in case of error.
1536 */
1537 
1538 ZEXTERN int ZEXPORT gzgetc(gzFile file);
1539 /*
1540      Read and decompress one byte from file.  gzgetc returns this byte or -1
1541    in case of end of file or error.  This is implemented as a macro for speed.
1542    As such, it does not do all of the checking the other functions do.  I.e.
1543    it does not check to see if file is NULL, nor whether the structure file
1544    points to has been clobbered or not.
1545 */
1546 
1547 ZEXTERN int ZEXPORT gzungetc(int c, gzFile file);
1548 /*
1549      Push c back onto the stream for file to be read as the first character on
1550    the next read.  At least one character of push-back is always allowed.
1551    gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
1552    fail if c is -1, and may fail if a character has been pushed but not read
1553    yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
1554    output buffer size of pushed characters is allowed.  (See gzbuffer above.)
1555    The pushed character will be discarded if the stream is repositioned with
1556    gzseek() or gzrewind().
1557 */
1558 
1559 ZEXTERN int ZEXPORT gzflush(gzFile file, int flush);
1560 /*
1561      Flush all pending output to file.  The parameter flush is as in the
1562    deflate() function.  The return value is the zlib error number (see function
1563    gzerror below).  gzflush is only permitted when writing.
1564 
1565      If the flush parameter is Z_FINISH, the remaining data is written and the
1566    gzip stream is completed in the output.  If gzwrite() is called again, a new
1567    gzip stream will be started in the output.  gzread() is able to read such
1568    concatenated gzip streams.
1569 
1570      gzflush should be called only when strictly necessary because it will
1571    degrade compression if called too often.
1572 */
1573 
1574 /*
1575 ZEXTERN z_off_t ZEXPORT gzseek(gzFile file,
1576                                z_off_t offset, int whence);
1577 
1578      Set the starting position to offset relative to whence for the next gzread
1579    or gzwrite on file.  The offset represents a number of bytes in the
1580    uncompressed data stream.  The whence parameter is defined as in lseek(2);
1581    the value SEEK_END is not supported.
1582 
1583      If the file is opened for reading, this function is emulated but can be
1584    extremely slow.  If the file is opened for writing, only forward seeks are
1585    supported; gzseek then compresses a sequence of zeroes up to the new
1586    starting position.
1587 
1588      gzseek returns the resulting offset location as measured in bytes from
1589    the beginning of the uncompressed stream, or -1 in case of error, in
1590    particular if the file is opened for writing and the new starting position
1591    would be before the current position.
1592 */
1593 
1594 ZEXTERN int ZEXPORT    gzrewind(gzFile file);
1595 /*
1596      Rewind file. This function is supported only for reading.
1597 
1598      gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
1599 */
1600 
1601 /*
1602 ZEXTERN z_off_t ZEXPORT    gztell(gzFile file);
1603 
1604      Return the starting position for the next gzread or gzwrite on file.
1605    This position represents a number of bytes in the uncompressed data stream,
1606    and is zero when starting, even if appending or reading a gzip stream from
1607    the middle of a file using gzdopen().
1608 
1609      gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1610 */
1611 
1612 /*
1613 ZEXTERN z_off_t ZEXPORT gzoffset(gzFile file);
1614 
1615      Return the current compressed (actual) read or write offset of file.  This
1616    offset includes the count of bytes that precede the gzip stream, for example
1617    when appending or when using gzdopen() for reading.  When reading, the
1618    offset does not include as yet unused buffered input.  This information can
1619    be used for a progress indicator.  On error, gzoffset() returns -1.
1620 */
1621 
1622 ZEXTERN int ZEXPORT gzeof(gzFile file);
1623 /*
1624      Return true (1) if the end-of-file indicator for file has been set while
1625    reading, false (0) otherwise.  Note that the end-of-file indicator is set
1626    only if the read tried to go past the end of the input, but came up short.
1627    Therefore, just like feof(), gzeof() may return false even if there is no
1628    more data to read, in the event that the last read request was for the exact
1629    number of bytes remaining in the input file.  This will happen if the input
1630    file size is an exact multiple of the buffer size.
1631 
1632      If gzeof() returns true, then the read functions will return no more data,
1633    unless the end-of-file indicator is reset by gzclearerr() and the input file
1634    has grown since the previous end of file was detected.
1635 */
1636 
1637 ZEXTERN int ZEXPORT gzdirect(gzFile file);
1638 /*
1639      Return true (1) if file is being copied directly while reading, or false
1640    (0) if file is a gzip stream being decompressed.
1641 
1642      If the input file is empty, gzdirect() will return true, since the input
1643    does not contain a gzip stream.
1644 
1645      If gzdirect() is used immediately after gzopen() or gzdopen() it will
1646    cause buffers to be allocated to allow reading the file to determine if it
1647    is a gzip file.  Therefore if gzbuffer() is used, it should be called before
1648    gzdirect().
1649 
1650      When writing, gzdirect() returns true (1) if transparent writing was
1651    requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
1652    gzdirect() is not needed when writing.  Transparent writing must be
1653    explicitly requested, so the application already knows the answer.  When
1654    linking statically, using gzdirect() will include all of the zlib code for
1655    gzip file reading and decompression, which may not be desired.)
1656 */
1657 
1658 ZEXTERN int ZEXPORT    gzclose(gzFile file);
1659 /*
1660      Flush all pending output for file, if necessary, close file and
1661    deallocate the (de)compression state.  Note that once file is closed, you
1662    cannot call gzerror with file, since its structures have been deallocated.
1663    gzclose must not be called more than once on the same file, just as free
1664    must not be called more than once on the same allocation.
1665 
1666      gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1667    file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1668    last read ended in the middle of a gzip stream, or Z_OK on success.
1669 */
1670 
1671 ZEXTERN int ZEXPORT gzclose_r(gzFile file);
1672 ZEXTERN int ZEXPORT gzclose_w(gzFile file);
1673 /*
1674      Same as gzclose(), but gzclose_r() is only for use when reading, and
1675    gzclose_w() is only for use when writing or appending.  The advantage to
1676    using these instead of gzclose() is that they avoid linking in zlib
1677    compression or decompression code that is not used when only reading or only
1678    writing respectively.  If gzclose() is used, then both compression and
1679    decompression code will be included the application when linking to a static
1680    zlib library.
1681 */
1682 
1683 ZEXTERN const char * ZEXPORT gzerror(gzFile file, int *errnum);
1684 /*
1685      Return the error message for the last error which occurred on file.
1686    errnum is set to zlib error number.  If an error occurred in the file system
1687    and not in the compression library, errnum is set to Z_ERRNO and the
1688    application may consult errno to get the exact error code.
1689 
1690      The application must not modify the returned string.  Future calls to
1691    this function may invalidate the previously returned string.  If file is
1692    closed, then the string previously returned by gzerror will no longer be
1693    available.
1694 
1695      gzerror() should be used to distinguish errors from end-of-file for those
1696    functions above that do not distinguish those cases in their return values.
1697 */
1698 
1699 ZEXTERN void ZEXPORT gzclearerr(gzFile file);
1700 /*
1701      Clear the error and end-of-file flags for file.  This is analogous to the
1702    clearerr() function in stdio.  This is useful for continuing to read a gzip
1703    file that is being written concurrently.
1704 */
1705 
1706 #endif /* !Z_SOLO */
1707 
1708                         /* checksum functions */
1709 
1710 /*
1711      These functions are not related to compression but are exported
1712    anyway because they might be useful in applications using the compression
1713    library.
1714 */
1715 
1716 ZEXTERN uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len);
1717 /*
1718      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1719    return the updated checksum. An Adler-32 value is in the range of a 32-bit
1720    unsigned integer. If buf is Z_NULL, this function returns the required
1721    initial value for the checksum.
1722 
1723      An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1724    much faster.
1725 
1726    Usage example:
1727 
1728      uLong adler = adler32(0L, Z_NULL, 0);
1729 
1730      while (read_buffer(buffer, length) != EOF) {
1731        adler = adler32(adler, buffer, length);
1732      }
1733      if (adler != original_adler) error();
1734 */
1735 
1736 ZEXTERN uLong ZEXPORT adler32_z(uLong adler, const Bytef *buf,
1737                                 z_size_t len);
1738 /*
1739      Same as adler32(), but with a size_t length.
1740 */
1741 
1742 /*
1743 ZEXTERN uLong ZEXPORT adler32_combine(uLong adler1, uLong adler2,
1744                                       z_off_t len2);
1745 
1746      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
1747    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1748    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
1749    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
1750    that the z_off_t type (like off_t) is a signed integer.  If len2 is
1751    negative, the result has no meaning or utility.
1752 */
1753 
1754 ZEXTERN uLong ZEXPORT crc32(uLong crc, const Bytef *buf, uInt len);
1755 /*
1756      Update a running CRC-32 with the bytes buf[0..len-1] and return the
1757    updated CRC-32. A CRC-32 value is in the range of a 32-bit unsigned integer.
1758    If buf is Z_NULL, this function returns the required initial value for the
1759    crc. Pre- and post-conditioning (one's complement) is performed within this
1760    function so it shouldn't be done by the application.
1761 
1762    Usage example:
1763 
1764      uLong crc = crc32(0L, Z_NULL, 0);
1765 
1766      while (read_buffer(buffer, length) != EOF) {
1767        crc = crc32(crc, buffer, length);
1768      }
1769      if (crc != original_crc) error();
1770 */
1771 
1772 ZEXTERN uLong ZEXPORT crc32_z(uLong crc, const Bytef *buf,
1773                               z_size_t len);
1774 /*
1775      Same as crc32(), but with a size_t length.
1776 */
1777 
1778 /*
1779 ZEXTERN uLong ZEXPORT crc32_combine(uLong crc1, uLong crc2, z_off_t len2);
1780 
1781      Combine two CRC-32 check values into one.  For two sequences of bytes,
1782    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1783    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
1784    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1785    len2. len2 must be non-negative.
1786 */
1787 
1788 /*
1789 ZEXTERN uLong ZEXPORT crc32_combine_gen(z_off_t len2);
1790 
1791      Return the operator corresponding to length len2, to be used with
1792    crc32_combine_op(). len2 must be non-negative.
1793 */
1794 
1795 ZEXTERN uLong ZEXPORT crc32_combine_op(uLong crc1, uLong crc2, uLong op);
1796 /*
1797      Give the same result as crc32_combine(), using op in place of len2. op is
1798    is generated from len2 by crc32_combine_gen(). This will be faster than
1799    crc32_combine() if the generated op is used more than once.
1800 */
1801 
1802 
1803                         /* various hacks, don't look :) */
1804 
1805 /* deflateInit and inflateInit are macros to allow checking the zlib version
1806  * and the compiler's view of z_stream:
1807  */
1808 ZEXTERN int ZEXPORT deflateInit_(z_streamp strm, int level,
1809                                  const char *version, int stream_size);
1810 ZEXTERN int ZEXPORT inflateInit_(z_streamp strm,
1811                                  const char *version, int stream_size);
1812 ZEXTERN int ZEXPORT deflateInit2_(z_streamp strm, int  level, int  method,
1813                                   int windowBits, int memLevel,
1814                                   int strategy, const char *version,
1815                                   int stream_size);
1816 ZEXTERN int ZEXPORT inflateInit2_(z_streamp strm, int  windowBits,
1817                                   const char *version, int stream_size);
1818 ZEXTERN int ZEXPORT inflateBackInit_(z_streamp strm, int windowBits,
1819                                      unsigned char FAR *window,
1820                                      const char *version,
1821                                      int stream_size);
1822 #ifdef Z_PREFIX_SET
1823 #  define z_deflateInit(strm, level) \
1824           deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1825 #  define z_inflateInit(strm) \
1826           inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1827 #  define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1828           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1829                         (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1830 #  define z_inflateInit2(strm, windowBits) \
1831           inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1832                         (int)sizeof(z_stream))
1833 #  define z_inflateBackInit(strm, windowBits, window) \
1834           inflateBackInit_((strm), (windowBits), (window), \
1835                            ZLIB_VERSION, (int)sizeof(z_stream))
1836 #else
1837 #  define deflateInit(strm, level) \
1838           deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
1839 #  define inflateInit(strm) \
1840           inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
1841 #  define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1842           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1843                         (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
1844 #  define inflateInit2(strm, windowBits) \
1845           inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
1846                         (int)sizeof(z_stream))
1847 #  define inflateBackInit(strm, windowBits, window) \
1848           inflateBackInit_((strm), (windowBits), (window), \
1849                            ZLIB_VERSION, (int)sizeof(z_stream))
1850 #endif
1851 
1852 #ifndef Z_SOLO
1853 
1854 /* gzgetc() macro and its supporting function and exposed data structure.  Note
1855  * that the real internal state is much larger than the exposed structure.
1856  * This abbreviated structure exposes just enough for the gzgetc() macro.  The
1857  * user should not mess with these exposed elements, since their names or
1858  * behavior could change in the future, perhaps even capriciously.  They can
1859  * only be used by the gzgetc() macro.  You have been warned.
1860  */
1861 struct gzFile_s {
1862     unsigned have;
1863     unsigned char *next;
1864     z_off64_t pos;
1865 };
1866 ZEXTERN int ZEXPORT gzgetc_(gzFile file);       /* backward compatibility */
1867 #ifdef Z_PREFIX_SET
1868 #  undef z_gzgetc
1869 #  define z_gzgetc(g) \
1870           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1871 #else
1872 #  define gzgetc(g) \
1873           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
1874 #endif
1875 
1876 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1877  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1878  * both are true, the application gets the *64 functions, and the regular
1879  * functions are changed to 64 bits) -- in case these are set on systems
1880  * without large file support, _LFS64_LARGEFILE must also be true
1881  */
1882 #ifdef Z_LARGE64
1883    ZEXTERN gzFile ZEXPORT gzopen64(const char *, const char *);
1884    ZEXTERN z_off64_t ZEXPORT gzseek64(gzFile, z_off64_t, int);
1885    ZEXTERN z_off64_t ZEXPORT gztell64(gzFile);
1886    ZEXTERN z_off64_t ZEXPORT gzoffset64(gzFile);
1887    ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off64_t);
1888    ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off64_t);
1889    ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off64_t);
1890 #endif
1891 
1892 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
1893 #  ifdef Z_PREFIX_SET
1894 #    define z_gzopen z_gzopen64
1895 #    define z_gzseek z_gzseek64
1896 #    define z_gztell z_gztell64
1897 #    define z_gzoffset z_gzoffset64
1898 #    define z_adler32_combine z_adler32_combine64
1899 #    define z_crc32_combine z_crc32_combine64
1900 #    define z_crc32_combine_gen z_crc32_combine_gen64
1901 #  else
1902 #    define gzopen gzopen64
1903 #    define gzseek gzseek64
1904 #    define gztell gztell64
1905 #    define gzoffset gzoffset64
1906 #    define adler32_combine adler32_combine64
1907 #    define crc32_combine crc32_combine64
1908 #    define crc32_combine_gen crc32_combine_gen64
1909 #  endif
1910 #  ifndef Z_LARGE64
1911      ZEXTERN gzFile ZEXPORT gzopen64(const char *, const char *);
1912      ZEXTERN z_off_t ZEXPORT gzseek64(gzFile, z_off_t, int);
1913      ZEXTERN z_off_t ZEXPORT gztell64(gzFile);
1914      ZEXTERN z_off_t ZEXPORT gzoffset64(gzFile);
1915      ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off_t);
1916      ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off_t);
1917      ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off_t);
1918 #  endif
1919 #else
1920    ZEXTERN gzFile ZEXPORT gzopen(const char *, const char *);
1921    ZEXTERN z_off_t ZEXPORT gzseek(gzFile, z_off_t, int);
1922    ZEXTERN z_off_t ZEXPORT gztell(gzFile);
1923    ZEXTERN z_off_t ZEXPORT gzoffset(gzFile);
1924    ZEXTERN uLong ZEXPORT adler32_combine(uLong, uLong, z_off_t);
1925    ZEXTERN uLong ZEXPORT crc32_combine(uLong, uLong, z_off_t);
1926    ZEXTERN uLong ZEXPORT crc32_combine_gen(z_off_t);
1927 #endif
1928 
1929 #else /* Z_SOLO */
1930 
1931    ZEXTERN uLong ZEXPORT adler32_combine(uLong, uLong, z_off_t);
1932    ZEXTERN uLong ZEXPORT crc32_combine(uLong, uLong, z_off_t);
1933    ZEXTERN uLong ZEXPORT crc32_combine_gen(z_off_t);
1934 
1935 #endif /* !Z_SOLO */
1936 
1937 /* undocumented functions */
1938 ZEXTERN const char   * ZEXPORT zError(int);
1939 ZEXTERN int            ZEXPORT inflateSyncPoint(z_streamp);
1940 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table(void);
1941 ZEXTERN int            ZEXPORT inflateUndermine(z_streamp, int);
1942 ZEXTERN int            ZEXPORT inflateValidate(z_streamp, int);
1943 ZEXTERN unsigned long  ZEXPORT inflateCodesUsed(z_streamp);
1944 ZEXTERN int            ZEXPORT inflateResetKeep(z_streamp);
1945 ZEXTERN int            ZEXPORT deflateResetKeep(z_streamp);
1946 #if defined(_WIN32) && !defined(Z_SOLO)
1947 ZEXTERN gzFile         ZEXPORT gzopen_w(const wchar_t *path,
1948                                         const char *mode);
1949 #endif
1950 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
1951 #  ifndef Z_SOLO
1952 ZEXTERN int            ZEXPORTVA gzvprintf(gzFile file,
1953                                            const char *format,
1954                                            va_list va);
1955 #  endif
1956 #endif
1957 
1958 #ifdef __cplusplus
1959 }
1960 #endif
1961 
1962 #endif /* ZLIB_H */