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    1 /* zlib.h -- interface of the 'zlib' general purpose compression library
    2   version 1.2.5, April 19th, 2010
    3 
    4   Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
    5 
    6   This software is provided 'as-is', without any express or implied
    7   warranty.  In no event will the authors be held liable for any damages
    8   arising from the use of this software.
    9 
   10   Permission is granted to anyone to use this software for any purpose,
   11   including commercial applications, and to alter it and redistribute it
   12   freely, subject to the following restrictions:
   13 
   14   1. The origin of this software must not be misrepresented; you must not
   15      claim that you wrote the original software. If you use this software
   16      in a product, an acknowledgment in the product documentation would be
   17      appreciated but is not required.
   18   2. Altered source versions must be plainly marked as such, and must not be
   19      misrepresented as being the original software.
   20   3. This notice may not be removed or altered from any source distribution.
   21 
   22   Jean-loup Gailly        Mark Adler
   23   jloup@gzip.org          madler@alumni.caltech.edu
   24 
   25 
   26   The data format used by the zlib library is described by RFCs (Request for
   27   Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
   28   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
   29 */
   30 
   31 #ifndef ZLIB_H
   32 #define ZLIB_H
   33 
   34 #include "zconf.h"
   35 
   36 #ifdef __cplusplus
   37 extern "C" {
   38 #endif
   39 
   40 #define ZLIB_VERSION "1.2.5"
   41 #define ZLIB_VERNUM 0x1250
   42 #define ZLIB_VER_MAJOR 1
   43 #define ZLIB_VER_MINOR 2
   44 #define ZLIB_VER_REVISION 5
   45 #define ZLIB_VER_SUBREVISION 0
   46 
   47 /*
   48     The 'zlib' compression library provides in-memory compression and
   49   decompression functions, including integrity checks of the uncompressed data.
   50   This version of the library supports only one compression method (deflation)
   51   but other algorithms will be added later and will have the same stream
   52   interface.
   53 
   54     Compression can be done in a single step if the buffers are large enough,
   55   or can be done by repeated calls of the compression function.  In the latter
   56   case, the application must provide more input and/or consume the output
   57   (providing more output space) before each call.
   58 
   59     The compressed data format used by default by the in-memory functions is
   60   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
   61   around a deflate stream, which is itself documented in RFC 1951.
   62 
   63     The library also supports reading and writing files in gzip (.gz) format
   64   with an interface similar to that of stdio using the functions that start
   65   with "gz".  The gzip format is different from the zlib format.  gzip is a
   66   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
   67 
   68     This library can optionally read and write gzip streams in memory as well.
   69 
   70     The zlib format was designed to be compact and fast for use in memory
   71   and on communications channels.  The gzip format was designed for single-
   72   file compression on file systems, has a larger header than zlib to maintain
   73   directory information, and uses a different, slower check method than zlib.
   74 
   75     The library does not install any signal handler.  The decoder checks
   76   the consistency of the compressed data, so the library should never crash
   77   even in case of corrupted input.
   78 */
   79 
   80 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
   81 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
   82 
   83 struct internal_state;
   84 
   85 typedef struct z_stream_s {
   86     Bytef    *next_in;  /* next input byte */
   87     uInt     avail_in;  /* number of bytes available at next_in */
   88     uLong    total_in;  /* total nb of input bytes read so far */
   89 
   90     Bytef    *next_out; /* next output byte should be put there */
   91     uInt     avail_out; /* remaining free space at next_out */
   92     uLong    total_out; /* total nb of bytes output so far */
   93 
   94     char     *msg;      /* last error message, NULL if no error */
   95     struct internal_state FAR *state; /* not visible by applications */
   96 
   97     alloc_func zalloc;  /* used to allocate the internal state */
   98     free_func  zfree;   /* used to free the internal state */
   99     voidpf     opaque;  /* private data object passed to zalloc and zfree */
  100 
  101     int     data_type;  /* best guess about the data type: binary or text */
  102     uLong   adler;      /* adler32 value of the uncompressed data */
  103     uLong   reserved;   /* reserved for future use */
  104 } z_stream;
  105 
  106 typedef z_stream FAR *z_streamp;
  107 
  108 /*
  109      gzip header information passed to and from zlib routines.  See RFC 1952
  110   for more details on the meanings of these fields.
  111 */
  112 typedef struct gz_header_s {
  113     int     text;       /* true if compressed data believed to be text */
  114     uLong   time;       /* modification time */
  115     int     xflags;     /* extra flags (not used when writing a gzip file) */
  116     int     os;         /* operating system */
  117     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
  118     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
  119     uInt    extra_max;  /* space at extra (only when reading header) */
  120     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
  121     uInt    name_max;   /* space at name (only when reading header) */
  122     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
  123     uInt    comm_max;   /* space at comment (only when reading header) */
  124     int     hcrc;       /* true if there was or will be a header crc */
  125     int     done;       /* true when done reading gzip header (not used
  126                            when writing a gzip file) */
  127 } gz_header;
  128 
  129 typedef gz_header FAR *gz_headerp;
  130 
  131 /*
  132      The application must update next_in and avail_in when avail_in has dropped
  133    to zero.  It must update next_out and avail_out when avail_out has dropped
  134    to zero.  The application must initialize zalloc, zfree and opaque before
  135    calling the init function.  All other fields are set by the compression
  136    library and must not be updated by the application.
  137 
  138      The opaque value provided by the application will be passed as the first
  139    parameter for calls of zalloc and zfree.  This can be useful for custom
  140    memory management.  The compression library attaches no meaning to the
  141    opaque value.
  142 
  143      zalloc must return Z_NULL if there is not enough memory for the object.
  144    If zlib is used in a multi-threaded application, zalloc and zfree must be
  145    thread safe.
  146 
  147      On 16-bit systems, the functions zalloc and zfree must be able to allocate
  148    exactly 65536 bytes, but will not be required to allocate more than this if
  149    the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
  150    returned by zalloc for objects of exactly 65536 bytes *must* have their
  151    offset normalized to zero.  The default allocation function provided by this
  152    library ensures this (see zutil.c).  To reduce memory requirements and avoid
  153    any allocation of 64K objects, at the expense of compression ratio, compile
  154    the library with -DMAX_WBITS=14 (see zconf.h).
  155 
  156      The fields total_in and total_out can be used for statistics or progress
  157    reports.  After compression, total_in holds the total size of the
  158    uncompressed data and may be saved for use in the decompressor (particularly
  159    if the decompressor wants to decompress everything in a single step).
  160 */
  161 
  162                         /* constants */
  163 
  164 #define Z_NO_FLUSH      0
  165 #define Z_PARTIAL_FLUSH 1
  166 #define Z_SYNC_FLUSH    2
  167 #define Z_FULL_FLUSH    3
  168 #define Z_FINISH        4
  169 #define Z_BLOCK         5
  170 #define Z_TREES         6
  171 /* Allowed flush values; see deflate() and inflate() below for details */
  172 
  173 #define Z_OK            0
  174 #define Z_STREAM_END    1
  175 #define Z_NEED_DICT     2
  176 #define Z_ERRNO        (-1)
  177 #define Z_STREAM_ERROR (-2)
  178 #define Z_DATA_ERROR   (-3)
  179 #define Z_MEM_ERROR    (-4)
  180 #define Z_BUF_ERROR    (-5)
  181 #define Z_VERSION_ERROR (-6)
  182 /* Return codes for the compression/decompression functions. Negative values
  183  * are errors, positive values are used for special but normal events.
  184  */
  185 
  186 #define Z_NO_COMPRESSION         0
  187 #define Z_BEST_SPEED             1
  188 #define Z_BEST_COMPRESSION       9
  189 #define Z_DEFAULT_COMPRESSION  (-1)
  190 /* compression levels */
  191 
  192 #define Z_FILTERED            1
  193 #define Z_HUFFMAN_ONLY        2
  194 #define Z_RLE                 3
  195 #define Z_FIXED               4
  196 #define Z_DEFAULT_STRATEGY    0
  197 /* compression strategy; see deflateInit2() below for details */
  198 
  199 #define Z_BINARY   0
  200 #define Z_TEXT     1
  201 #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
  202 #define Z_UNKNOWN  2
  203 /* Possible values of the data_type field (though see inflate()) */
  204 
  205 #define Z_DEFLATED   8
  206 /* The deflate compression method (the only one supported in this version) */
  207 
  208 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
  209 
  210 #define zlib_version zlibVersion()
  211 /* for compatibility with versions < 1.0.2 */
  212 
  213 
  214                         /* basic functions */
  215 
  216 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
  217 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
  218    If the first character differs, the library code actually used is not
  219    compatible with the zlib.h header file used by the application.  This check
  220    is automatically made by deflateInit and inflateInit.
  221  */
  222 
  223 /*
  224 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
  225 
  226      Initializes the internal stream state for compression.  The fields
  227    zalloc, zfree and opaque must be initialized before by the caller.  If
  228    zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
  229    allocation functions.
  230 
  231      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
  232    1 gives best speed, 9 gives best compression, 0 gives no compression at all
  233    (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
  234    requests a default compromise between speed and compression (currently
  235    equivalent to level 6).
  236 
  237      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  238    memory, Z_STREAM_ERROR if level is not a valid compression level, or
  239    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
  240    with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
  241    if there is no error message.  deflateInit does not perform any compression:
  242    this will be done by deflate().
  243 */
  244 
  245 
  246 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
  247 /*
  248     deflate compresses as much data as possible, and stops when the input
  249   buffer becomes empty or the output buffer becomes full.  It may introduce
  250   some output latency (reading input without producing any output) except when
  251   forced to flush.
  252 
  253     The detailed semantics are as follows.  deflate performs one or both of the
  254   following actions:
  255 
  256   - Compress more input starting at next_in and update next_in and avail_in
  257     accordingly.  If not all input can be processed (because there is not
  258     enough room in the output buffer), next_in and avail_in are updated and
  259     processing will resume at this point for the next call of deflate().
  260 
  261   - Provide more output starting at next_out and update next_out and avail_out
  262     accordingly.  This action is forced if the parameter flush is non zero.
  263     Forcing flush frequently degrades the compression ratio, so this parameter
  264     should be set only when necessary (in interactive applications).  Some
  265     output may be provided even if flush is not set.
  266 
  267     Before the call of deflate(), the application should ensure that at least
  268   one of the actions is possible, by providing more input and/or consuming more
  269   output, and updating avail_in or avail_out accordingly; avail_out should
  270   never be zero before the call.  The application can consume the compressed
  271   output when it wants, for example when the output buffer is full (avail_out
  272   == 0), or after each call of deflate().  If deflate returns Z_OK and with
  273   zero avail_out, it must be called again after making room in the output
  274   buffer because there might be more output pending.
  275 
  276     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
  277   decide how much data to accumulate before producing output, in order to
  278   maximize compression.
  279 
  280     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
  281   flushed to the output buffer and the output is aligned on a byte boundary, so
  282   that the decompressor can get all input data available so far.  (In
  283   particular avail_in is zero after the call if enough output space has been
  284   provided before the call.) Flushing may degrade compression for some
  285   compression algorithms and so it should be used only when necessary.  This
  286   completes the current deflate block and follows it with an empty stored block
  287   that is three bits plus filler bits to the next byte, followed by four bytes
  288   (00 00 ff ff).
  289 
  290     If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
  291   output buffer, but the output is not aligned to a byte boundary.  All of the
  292   input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
  293   This completes the current deflate block and follows it with an empty fixed
  294   codes block that is 10 bits long.  This assures that enough bytes are output
  295   in order for the decompressor to finish the block before the empty fixed code
  296   block.
  297 
  298     If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
  299   for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
  300   seven bits of the current block are held to be written as the next byte after
  301   the next deflate block is completed.  In this case, the decompressor may not
  302   be provided enough bits at this point in order to complete decompression of
  303   the data provided so far to the compressor.  It may need to wait for the next
  304   block to be emitted.  This is for advanced applications that need to control
  305   the emission of deflate blocks.
  306 
  307     If flush is set to Z_FULL_FLUSH, all output is flushed as with
  308   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
  309   restart from this point if previous compressed data has been damaged or if
  310   random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
  311   compression.
  312 
  313     If deflate returns with avail_out == 0, this function must be called again
  314   with the same value of the flush parameter and more output space (updated
  315   avail_out), until the flush is complete (deflate returns with non-zero
  316   avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
  317   avail_out is greater than six to avoid repeated flush markers due to
  318   avail_out == 0 on return.
  319 
  320     If the parameter flush is set to Z_FINISH, pending input is processed,
  321   pending output is flushed and deflate returns with Z_STREAM_END if there was
  322   enough output space; if deflate returns with Z_OK, this function must be
  323   called again with Z_FINISH and more output space (updated avail_out) but no
  324   more input data, until it returns with Z_STREAM_END or an error.  After
  325   deflate has returned Z_STREAM_END, the only possible operations on the stream
  326   are deflateReset or deflateEnd.
  327 
  328     Z_FINISH can be used immediately after deflateInit if all the compression
  329   is to be done in a single step.  In this case, avail_out must be at least the
  330   value returned by deflateBound (see below).  If deflate does not return
  331   Z_STREAM_END, then it must be called again as described above.
  332 
  333     deflate() sets strm->adler to the adler32 checksum of all input read
  334   so far (that is, total_in bytes).
  335 
  336     deflate() may update strm->data_type if it can make a good guess about
  337   the input data type (Z_BINARY or Z_TEXT).  In doubt, the data is considered
  338   binary.  This field is only for information purposes and does not affect the
  339   compression algorithm in any manner.
  340 
  341     deflate() returns Z_OK if some progress has been made (more input
  342   processed or more output produced), Z_STREAM_END if all input has been
  343   consumed and all output has been produced (only when flush is set to
  344   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
  345   if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
  346   (for example avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not
  347   fatal, and deflate() can be called again with more input and more output
  348   space to continue compressing.
  349 */
  350 
  351 
  352 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
  353 /*
  354      All dynamically allocated data structures for this stream are freed.
  355    This function discards any unprocessed input and does not flush any pending
  356    output.
  357 
  358      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
  359    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
  360    prematurely (some input or output was discarded).  In the error case, msg
  361    may be set but then points to a static string (which must not be
  362    deallocated).
  363 */
  364 
  365 
  366 /*
  367 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
  368 
  369      Initializes the internal stream state for decompression.  The fields
  370    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
  371    the caller.  If next_in is not Z_NULL and avail_in is large enough (the
  372    exact value depends on the compression method), inflateInit determines the
  373    compression method from the zlib header and allocates all data structures
  374    accordingly; otherwise the allocation will be deferred to the first call of
  375    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
  376    use default allocation functions.
  377 
  378      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  379    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  380    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  381    invalid, such as a null pointer to the structure.  msg is set to null if
  382    there is no error message.  inflateInit does not perform any decompression
  383    apart from possibly reading the zlib header if present: actual decompression
  384    will be done by inflate().  (So next_in and avail_in may be modified, but
  385    next_out and avail_out are unused and unchanged.) The current implementation
  386    of inflateInit() does not process any header information -- that is deferred
  387    until inflate() is called.
  388 */
  389 
  390 
  391 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
  392 /*
  393     inflate decompresses as much data as possible, and stops when the input
  394   buffer becomes empty or the output buffer becomes full.  It may introduce
  395   some output latency (reading input without producing any output) except when
  396   forced to flush.
  397 
  398   The detailed semantics are as follows.  inflate performs one or both of the
  399   following actions:
  400 
  401   - Decompress more input starting at next_in and update next_in and avail_in
  402     accordingly.  If not all input can be processed (because there is not
  403     enough room in the output buffer), next_in is updated and processing will
  404     resume at this point for the next call of inflate().
  405 
  406   - Provide more output starting at next_out and update next_out and avail_out
  407     accordingly.  inflate() provides as much output as possible, until there is
  408     no more input data or no more space in the output buffer (see below about
  409     the flush parameter).
  410 
  411     Before the call of inflate(), the application should ensure that at least
  412   one of the actions is possible, by providing more input and/or consuming more
  413   output, and updating the next_* and avail_* values accordingly.  The
  414   application can consume the uncompressed output when it wants, for example
  415   when the output buffer is full (avail_out == 0), or after each call of
  416   inflate().  If inflate returns Z_OK and with zero avail_out, it must be
  417   called again after making room in the output buffer because there might be
  418   more output pending.
  419 
  420     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
  421   Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
  422   output as possible to the output buffer.  Z_BLOCK requests that inflate()
  423   stop if and when it gets to the next deflate block boundary.  When decoding
  424   the zlib or gzip format, this will cause inflate() to return immediately
  425   after the header and before the first block.  When doing a raw inflate,
  426   inflate() will go ahead and process the first block, and will return when it
  427   gets to the end of that block, or when it runs out of data.
  428 
  429     The Z_BLOCK option assists in appending to or combining deflate streams.
  430   Also to assist in this, on return inflate() will set strm->data_type to the
  431   number of unused bits in the last byte taken from strm->next_in, plus 64 if
  432   inflate() is currently decoding the last block in the deflate stream, plus
  433   128 if inflate() returned immediately after decoding an end-of-block code or
  434   decoding the complete header up to just before the first byte of the deflate
  435   stream.  The end-of-block will not be indicated until all of the uncompressed
  436   data from that block has been written to strm->next_out.  The number of
  437   unused bits may in general be greater than seven, except when bit 7 of
  438   data_type is set, in which case the number of unused bits will be less than
  439   eight.  data_type is set as noted here every time inflate() returns for all
  440   flush options, and so can be used to determine the amount of currently
  441   consumed input in bits.
  442 
  443     The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
  444   end of each deflate block header is reached, before any actual data in that
  445   block is decoded.  This allows the caller to determine the length of the
  446   deflate block header for later use in random access within a deflate block.
  447   256 is added to the value of strm->data_type when inflate() returns
  448   immediately after reaching the end of the deflate block header.
  449 
  450     inflate() should normally be called until it returns Z_STREAM_END or an
  451   error.  However if all decompression is to be performed in a single step (a
  452   single call of inflate), the parameter flush should be set to Z_FINISH.  In
  453   this case all pending input is processed and all pending output is flushed;
  454   avail_out must be large enough to hold all the uncompressed data.  (The size
  455   of the uncompressed data may have been saved by the compressor for this
  456   purpose.) The next operation on this stream must be inflateEnd to deallocate
  457   the decompression state.  The use of Z_FINISH is never required, but can be
  458   used to inform inflate that a faster approach may be used for the single
  459   inflate() call.
  460 
  461      In this implementation, inflate() always flushes as much output as
  462   possible to the output buffer, and always uses the faster approach on the
  463   first call.  So the only effect of the flush parameter in this implementation
  464   is on the return value of inflate(), as noted below, or when it returns early
  465   because Z_BLOCK or Z_TREES is used.
  466 
  467      If a preset dictionary is needed after this call (see inflateSetDictionary
  468   below), inflate sets strm->adler to the adler32 checksum of the dictionary
  469   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
  470   strm->adler to the adler32 checksum of all output produced so far (that is,
  471   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
  472   below.  At the end of the stream, inflate() checks that its computed adler32
  473   checksum is equal to that saved by the compressor and returns Z_STREAM_END
  474   only if the checksum is correct.
  475 
  476     inflate() can decompress and check either zlib-wrapped or gzip-wrapped
  477   deflate data.  The header type is detected automatically, if requested when
  478   initializing with inflateInit2().  Any information contained in the gzip
  479   header is not retained, so applications that need that information should
  480   instead use raw inflate, see inflateInit2() below, or inflateBack() and
  481   perform their own processing of the gzip header and trailer.
  482 
  483     inflate() returns Z_OK if some progress has been made (more input processed
  484   or more output produced), Z_STREAM_END if the end of the compressed data has
  485   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
  486   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
  487   corrupted (input stream not conforming to the zlib format or incorrect check
  488   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
  489   next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
  490   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
  491   output buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
  492   inflate() can be called again with more input and more output space to
  493   continue decompressing.  If Z_DATA_ERROR is returned, the application may
  494   then call inflateSync() to look for a good compression block if a partial
  495   recovery of the data is desired.
  496 */
  497 
  498 
  499 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
  500 /*
  501      All dynamically allocated data structures for this stream are freed.
  502    This function discards any unprocessed input and does not flush any pending
  503    output.
  504 
  505      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
  506    was inconsistent.  In the error case, msg may be set but then points to a
  507    static string (which must not be deallocated).
  508 */
  509 
  510 
  511                         /* Advanced functions */
  512 
  513 /*
  514     The following functions are needed only in some special applications.
  515 */
  516 
  517 /*
  518 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
  519                                      int  level,
  520                                      int  method,
  521                                      int  windowBits,
  522                                      int  memLevel,
  523                                      int  strategy));
  524 
  525      This is another version of deflateInit with more compression options.  The
  526    fields next_in, zalloc, zfree and opaque must be initialized before by the
  527    caller.
  528 
  529      The method parameter is the compression method.  It must be Z_DEFLATED in
  530    this version of the library.
  531 
  532      The windowBits parameter is the base two logarithm of the window size
  533    (the size of the history buffer).  It should be in the range 8..15 for this
  534    version of the library.  Larger values of this parameter result in better
  535    compression at the expense of memory usage.  The default value is 15 if
  536    deflateInit is used instead.
  537 
  538      windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
  539    determines the window size.  deflate() will then generate raw deflate data
  540    with no zlib header or trailer, and will not compute an adler32 check value.
  541 
  542      windowBits can also be greater than 15 for optional gzip encoding.  Add
  543    16 to windowBits to write a simple gzip header and trailer around the
  544    compressed data instead of a zlib wrapper.  The gzip header will have no
  545    file name, no extra data, no comment, no modification time (set to zero), no
  546    header crc, and the operating system will be set to 255 (unknown).  If a
  547    gzip stream is being written, strm->adler is a crc32 instead of an adler32.
  548 
  549      The memLevel parameter specifies how much memory should be allocated
  550    for the internal compression state.  memLevel=1 uses minimum memory but is
  551    slow and reduces compression ratio; memLevel=9 uses maximum memory for
  552    optimal speed.  The default value is 8.  See zconf.h for total memory usage
  553    as a function of windowBits and memLevel.
  554 
  555      The strategy parameter is used to tune the compression algorithm.  Use the
  556    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
  557    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
  558    string match), or Z_RLE to limit match distances to one (run-length
  559    encoding).  Filtered data consists mostly of small values with a somewhat
  560    random distribution.  In this case, the compression algorithm is tuned to
  561    compress them better.  The effect of Z_FILTERED is to force more Huffman
  562    coding and less string matching; it is somewhat intermediate between
  563    Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
  564    fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
  565    strategy parameter only affects the compression ratio but not the
  566    correctness of the compressed output even if it is not set appropriately.
  567    Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
  568    decoder for special applications.
  569 
  570      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  571    memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
  572    method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
  573    incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
  574    set to null if there is no error message.  deflateInit2 does not perform any
  575    compression: this will be done by deflate().
  576 */
  577 
  578 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
  579                                              const Bytef *dictionary,
  580                                              uInt  dictLength));
  581 /*
  582      Initializes the compression dictionary from the given byte sequence
  583    without producing any compressed output.  This function must be called
  584    immediately after deflateInit, deflateInit2 or deflateReset, before any call
  585    of deflate.  The compressor and decompressor must use exactly the same
  586    dictionary (see inflateSetDictionary).
  587 
  588      The dictionary should consist of strings (byte sequences) that are likely
  589    to be encountered later in the data to be compressed, with the most commonly
  590    used strings preferably put towards the end of the dictionary.  Using a
  591    dictionary is most useful when the data to be compressed is short and can be
  592    predicted with good accuracy; the data can then be compressed better than
  593    with the default empty dictionary.
  594 
  595      Depending on the size of the compression data structures selected by
  596    deflateInit or deflateInit2, a part of the dictionary may in effect be
  597    discarded, for example if the dictionary is larger than the window size
  598    provided in deflateInit or deflateInit2.  Thus the strings most likely to be
  599    useful should be put at the end of the dictionary, not at the front.  In
  600    addition, the current implementation of deflate will use at most the window
  601    size minus 262 bytes of the provided dictionary.
  602 
  603      Upon return of this function, strm->adler is set to the adler32 value
  604    of the dictionary; the decompressor may later use this value to determine
  605    which dictionary has been used by the compressor.  (The adler32 value
  606    applies to the whole dictionary even if only a subset of the dictionary is
  607    actually used by the compressor.) If a raw deflate was requested, then the
  608    adler32 value is not computed and strm->adler is not set.
  609 
  610      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
  611    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
  612    inconsistent (for example if deflate has already been called for this stream
  613    or if the compression method is bsort).  deflateSetDictionary does not
  614    perform any compression: this will be done by deflate().
  615 */
  616 
  617 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
  618                                     z_streamp source));
  619 /*
  620      Sets the destination stream as a complete copy of the source stream.
  621 
  622      This function can be useful when several compression strategies will be
  623    tried, for example when there are several ways of pre-processing the input
  624    data with a filter.  The streams that will be discarded should then be freed
  625    by calling deflateEnd.  Note that deflateCopy duplicates the internal
  626    compression state which can be quite large, so this strategy is slow and can
  627    consume lots of memory.
  628 
  629      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  630    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  631    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
  632    destination.
  633 */
  634 
  635 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
  636 /*
  637      This function is equivalent to deflateEnd followed by deflateInit,
  638    but does not free and reallocate all the internal compression state.  The
  639    stream will keep the same compression level and any other attributes that
  640    may have been set by deflateInit2.
  641 
  642      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  643    stream state was inconsistent (such as zalloc or state being Z_NULL).
  644 */
  645 
  646 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
  647                                       int level,
  648                                       int strategy));
  649 /*
  650      Dynamically update the compression level and compression strategy.  The
  651    interpretation of level and strategy is as in deflateInit2.  This can be
  652    used to switch between compression and straight copy of the input data, or
  653    to switch to a different kind of input data requiring a different strategy.
  654    If the compression level is changed, the input available so far is
  655    compressed with the old level (and may be flushed); the new level will take
  656    effect only at the next call of deflate().
  657 
  658      Before the call of deflateParams, the stream state must be set as for
  659    a call of deflate(), since the currently available input may have to be
  660    compressed and flushed.  In particular, strm->avail_out must be non-zero.
  661 
  662      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
  663    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
  664    strm->avail_out was zero.
  665 */
  666 
  667 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
  668                                     int good_length,
  669                                     int max_lazy,
  670                                     int nice_length,
  671                                     int max_chain));
  672 /*
  673      Fine tune deflate's internal compression parameters.  This should only be
  674    used by someone who understands the algorithm used by zlib's deflate for
  675    searching for the best matching string, and even then only by the most
  676    fanatic optimizer trying to squeeze out the last compressed bit for their
  677    specific input data.  Read the deflate.c source code for the meaning of the
  678    max_lazy, good_length, nice_length, and max_chain parameters.
  679 
  680      deflateTune() can be called after deflateInit() or deflateInit2(), and
  681    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
  682  */
  683 
  684 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
  685                                        uLong sourceLen));
  686 /*
  687      deflateBound() returns an upper bound on the compressed size after
  688    deflation of sourceLen bytes.  It must be called after deflateInit() or
  689    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
  690    to allocate an output buffer for deflation in a single pass, and so would be
  691    called before deflate().
  692 */
  693 
  694 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
  695                                      int bits,
  696                                      int value));
  697 /*
  698      deflatePrime() inserts bits in the deflate output stream.  The intent
  699    is that this function is used to start off the deflate output with the bits
  700    leftover from a previous deflate stream when appending to it.  As such, this
  701    function can only be used for raw deflate, and must be used before the first
  702    deflate() call after a deflateInit2() or deflateReset().  bits must be less
  703    than or equal to 16, and that many of the least significant bits of value
  704    will be inserted in the output.
  705 
  706      deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
  707    stream state was inconsistent.
  708 */
  709 
  710 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
  711                                          gz_headerp head));
  712 /*
  713      deflateSetHeader() provides gzip header information for when a gzip
  714    stream is requested by deflateInit2().  deflateSetHeader() may be called
  715    after deflateInit2() or deflateReset() and before the first call of
  716    deflate().  The text, time, os, extra field, name, and comment information
  717    in the provided gz_header structure are written to the gzip header (xflag is
  718    ignored -- the extra flags are set according to the compression level).  The
  719    caller must assure that, if not Z_NULL, name and comment are terminated with
  720    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
  721    available there.  If hcrc is true, a gzip header crc is included.  Note that
  722    the current versions of the command-line version of gzip (up through version
  723    1.3.x) do not support header crc's, and will report that it is a "multi-part
  724    gzip file" and give up.
  725 
  726      If deflateSetHeader is not used, the default gzip header has text false,
  727    the time set to zero, and os set to 255, with no extra, name, or comment
  728    fields.  The gzip header is returned to the default state by deflateReset().
  729 
  730      deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
  731    stream state was inconsistent.
  732 */
  733 
  734 /*
  735 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
  736                                      int  windowBits));
  737 
  738      This is another version of inflateInit with an extra parameter.  The
  739    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
  740    before by the caller.
  741 
  742      The windowBits parameter is the base two logarithm of the maximum window
  743    size (the size of the history buffer).  It should be in the range 8..15 for
  744    this version of the library.  The default value is 15 if inflateInit is used
  745    instead.  windowBits must be greater than or equal to the windowBits value
  746    provided to deflateInit2() while compressing, or it must be equal to 15 if
  747    deflateInit2() was not used.  If a compressed stream with a larger window
  748    size is given as input, inflate() will return with the error code
  749    Z_DATA_ERROR instead of trying to allocate a larger window.
  750 
  751      windowBits can also be zero to request that inflate use the window size in
  752    the zlib header of the compressed stream.
  753 
  754      windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
  755    determines the window size.  inflate() will then process raw deflate data,
  756    not looking for a zlib or gzip header, not generating a check value, and not
  757    looking for any check values for comparison at the end of the stream.  This
  758    is for use with other formats that use the deflate compressed data format
  759    such as zip.  Those formats provide their own check values.  If a custom
  760    format is developed using the raw deflate format for compressed data, it is
  761    recommended that a check value such as an adler32 or a crc32 be applied to
  762    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
  763    most applications, the zlib format should be used as is.  Note that comments
  764    above on the use in deflateInit2() applies to the magnitude of windowBits.
  765 
  766      windowBits can also be greater than 15 for optional gzip decoding.  Add
  767    32 to windowBits to enable zlib and gzip decoding with automatic header
  768    detection, or add 16 to decode only the gzip format (the zlib format will
  769    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
  770    crc32 instead of an adler32.
  771 
  772      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  773    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  774    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  775    invalid, such as a null pointer to the structure.  msg is set to null if
  776    there is no error message.  inflateInit2 does not perform any decompression
  777    apart from possibly reading the zlib header if present: actual decompression
  778    will be done by inflate().  (So next_in and avail_in may be modified, but
  779    next_out and avail_out are unused and unchanged.) The current implementation
  780    of inflateInit2() does not process any header information -- that is
  781    deferred until inflate() is called.
  782 */
  783 
  784 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
  785                                              const Bytef *dictionary,
  786                                              uInt  dictLength));
  787 /*
  788      Initializes the decompression dictionary from the given uncompressed byte
  789    sequence.  This function must be called immediately after a call of inflate,
  790    if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
  791    can be determined from the adler32 value returned by that call of inflate.
  792    The compressor and decompressor must use exactly the same dictionary (see
  793    deflateSetDictionary).  For raw inflate, this function can be called
  794    immediately after inflateInit2() or inflateReset() and before any call of
  795    inflate() to set the dictionary.  The application must insure that the
  796    dictionary that was used for compression is provided.
  797 
  798      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
  799    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
  800    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
  801    expected one (incorrect adler32 value).  inflateSetDictionary does not
  802    perform any decompression: this will be done by subsequent calls of
  803    inflate().
  804 */
  805 
  806 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
  807 /*
  808      Skips invalid compressed data until a full flush point (see above the
  809    description of deflate with Z_FULL_FLUSH) can be found, or until all
  810    available input is skipped.  No output is provided.
  811 
  812      inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
  813    if no more input was provided, Z_DATA_ERROR if no flush point has been
  814    found, or Z_STREAM_ERROR if the stream structure was inconsistent.  In the
  815    success case, the application may save the current current value of total_in
  816    which indicates where valid compressed data was found.  In the error case,
  817    the application may repeatedly call inflateSync, providing more input each
  818    time, until success or end of the input data.
  819 */
  820 
  821 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
  822                                     z_streamp source));
  823 /*
  824      Sets the destination stream as a complete copy of the source stream.
  825 
  826      This function can be useful when randomly accessing a large stream.  The
  827    first pass through the stream can periodically record the inflate state,
  828    allowing restarting inflate at those points when randomly accessing the
  829    stream.
  830 
  831      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  832    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  833    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
  834    destination.
  835 */
  836 
  837 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
  838 /*
  839      This function is equivalent to inflateEnd followed by inflateInit,
  840    but does not free and reallocate all the internal decompression state.  The
  841    stream will keep attributes that may have been set by inflateInit2.
  842 
  843      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  844    stream state was inconsistent (such as zalloc or state being Z_NULL).
  845 */
  846 
  847 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
  848                                       int windowBits));
  849 /*
  850      This function is the same as inflateReset, but it also permits changing
  851    the wrap and window size requests.  The windowBits parameter is interpreted
  852    the same as it is for inflateInit2.
  853 
  854      inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
  855    stream state was inconsistent (such as zalloc or state being Z_NULL), or if
  856    the windowBits parameter is invalid.
  857 */
  858 
  859 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
  860                                      int bits,
  861                                      int value));
  862 /*
  863      This function inserts bits in the inflate input stream.  The intent is
  864    that this function is used to start inflating at a bit position in the
  865    middle of a byte.  The provided bits will be used before any bytes are used
  866    from next_in.  This function should only be used with raw inflate, and
  867    should be used before the first inflate() call after inflateInit2() or
  868    inflateReset().  bits must be less than or equal to 16, and that many of the
  869    least significant bits of value will be inserted in the input.
  870 
  871      If bits is negative, then the input stream bit buffer is emptied.  Then
  872    inflatePrime() can be called again to put bits in the buffer.  This is used
  873    to clear out bits leftover after feeding inflate a block description prior
  874    to feeding inflate codes.
  875 
  876      inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
  877    stream state was inconsistent.
  878 */
  879 
  880 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
  881 /*
  882      This function returns two values, one in the lower 16 bits of the return
  883    value, and the other in the remaining upper bits, obtained by shifting the
  884    return value down 16 bits.  If the upper value is -1 and the lower value is
  885    zero, then inflate() is currently decoding information outside of a block.
  886    If the upper value is -1 and the lower value is non-zero, then inflate is in
  887    the middle of a stored block, with the lower value equaling the number of
  888    bytes from the input remaining to copy.  If the upper value is not -1, then
  889    it is the number of bits back from the current bit position in the input of
  890    the code (literal or length/distance pair) currently being processed.  In
  891    that case the lower value is the number of bytes already emitted for that
  892    code.
  893 
  894      A code is being processed if inflate is waiting for more input to complete
  895    decoding of the code, or if it has completed decoding but is waiting for
  896    more output space to write the literal or match data.
  897 
  898      inflateMark() is used to mark locations in the input data for random
  899    access, which may be at bit positions, and to note those cases where the
  900    output of a code may span boundaries of random access blocks.  The current
  901    location in the input stream can be determined from avail_in and data_type
  902    as noted in the description for the Z_BLOCK flush parameter for inflate.
  903 
  904      inflateMark returns the value noted above or -1 << 16 if the provided
  905    source stream state was inconsistent.
  906 */
  907 
  908 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
  909                                          gz_headerp head));
  910 /*
  911      inflateGetHeader() requests that gzip header information be stored in the
  912    provided gz_header structure.  inflateGetHeader() may be called after
  913    inflateInit2() or inflateReset(), and before the first call of inflate().
  914    As inflate() processes the gzip stream, head->done is zero until the header
  915    is completed, at which time head->done is set to one.  If a zlib stream is
  916    being decoded, then head->done is set to -1 to indicate that there will be
  917    no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
  918    used to force inflate() to return immediately after header processing is
  919    complete and before any actual data is decompressed.
  920 
  921      The text, time, xflags, and os fields are filled in with the gzip header
  922    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
  923    was valid if done is set to one.) If extra is not Z_NULL, then extra_max
  924    contains the maximum number of bytes to write to extra.  Once done is true,
  925    extra_len contains the actual extra field length, and extra contains the
  926    extra field, or that field truncated if extra_max is less than extra_len.
  927    If name is not Z_NULL, then up to name_max characters are written there,
  928    terminated with a zero unless the length is greater than name_max.  If
  929    comment is not Z_NULL, then up to comm_max characters are written there,
  930    terminated with a zero unless the length is greater than comm_max.  When any
  931    of extra, name, or comment are not Z_NULL and the respective field is not
  932    present in the header, then that field is set to Z_NULL to signal its
  933    absence.  This allows the use of deflateSetHeader() with the returned
  934    structure to duplicate the header.  However if those fields are set to
  935    allocated memory, then the application will need to save those pointers
  936    elsewhere so that they can be eventually freed.
  937 
  938      If inflateGetHeader is not used, then the header information is simply
  939    discarded.  The header is always checked for validity, including the header
  940    CRC if present.  inflateReset() will reset the process to discard the header
  941    information.  The application would need to call inflateGetHeader() again to
  942    retrieve the header from the next gzip stream.
  943 
  944      inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
  945    stream state was inconsistent.
  946 */
  947 
  948 /*
  949 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
  950                                         unsigned char FAR *window));
  951 
  952      Initialize the internal stream state for decompression using inflateBack()
  953    calls.  The fields zalloc, zfree and opaque in strm must be initialized
  954    before the call.  If zalloc and zfree are Z_NULL, then the default library-
  955    derived memory allocation routines are used.  windowBits is the base two
  956    logarithm of the window size, in the range 8..15.  window is a caller
  957    supplied buffer of that size.  Except for special applications where it is
  958    assured that deflate was used with small window sizes, windowBits must be 15
  959    and a 32K byte window must be supplied to be able to decompress general
  960    deflate streams.
  961 
  962      See inflateBack() for the usage of these routines.
  963 
  964      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
  965    the paramaters are invalid, Z_MEM_ERROR if the internal state could not be
  966    allocated, or Z_VERSION_ERROR if the version of the library does not match
  967    the version of the header file.
  968 */
  969 
  970 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
  971 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
  972 
  973 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
  974                                     in_func in, void FAR *in_desc,
  975                                     out_func out, void FAR *out_desc));
  976 /*
  977      inflateBack() does a raw inflate with a single call using a call-back
  978    interface for input and output.  This is more efficient than inflate() for
  979    file i/o applications in that it avoids copying between the output and the
  980    sliding window by simply making the window itself the output buffer.  This
  981    function trusts the application to not change the output buffer passed by
  982    the output function, at least until inflateBack() returns.
  983 
  984      inflateBackInit() must be called first to allocate the internal state
  985    and to initialize the state with the user-provided window buffer.
  986    inflateBack() may then be used multiple times to inflate a complete, raw
  987    deflate stream with each call.  inflateBackEnd() is then called to free the
  988    allocated state.
  989 
  990      A raw deflate stream is one with no zlib or gzip header or trailer.
  991    This routine would normally be used in a utility that reads zip or gzip
  992    files and writes out uncompressed files.  The utility would decode the
  993    header and process the trailer on its own, hence this routine expects only
  994    the raw deflate stream to decompress.  This is different from the normal
  995    behavior of inflate(), which expects either a zlib or gzip header and
  996    trailer around the deflate stream.
  997 
  998      inflateBack() uses two subroutines supplied by the caller that are then
  999    called by inflateBack() for input and output.  inflateBack() calls those
 1000    routines until it reads a complete deflate stream and writes out all of the
 1001    uncompressed data, or until it encounters an error.  The function's
 1002    parameters and return types are defined above in the in_func and out_func
 1003    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
 1004    number of bytes of provided input, and a pointer to that input in buf.  If
 1005    there is no input available, in() must return zero--buf is ignored in that
 1006    case--and inflateBack() will return a buffer error.  inflateBack() will call
 1007    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
 1008    should return zero on success, or non-zero on failure.  If out() returns
 1009    non-zero, inflateBack() will return with an error.  Neither in() nor out()
 1010    are permitted to change the contents of the window provided to
 1011    inflateBackInit(), which is also the buffer that out() uses to write from.
 1012    The length written by out() will be at most the window size.  Any non-zero
 1013    amount of input may be provided by in().
 1014 
 1015      For convenience, inflateBack() can be provided input on the first call by
 1016    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
 1017    in() will be called.  Therefore strm->next_in must be initialized before
 1018    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
 1019    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
 1020    must also be initialized, and then if strm->avail_in is not zero, input will
 1021    initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
 1022 
 1023      The in_desc and out_desc parameters of inflateBack() is passed as the
 1024    first parameter of in() and out() respectively when they are called.  These
 1025    descriptors can be optionally used to pass any information that the caller-
 1026    supplied in() and out() functions need to do their job.
 1027 
 1028      On return, inflateBack() will set strm->next_in and strm->avail_in to
 1029    pass back any unused input that was provided by the last in() call.  The
 1030    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
 1031    if in() or out() returned an error, Z_DATA_ERROR if there was a format error
 1032    in the deflate stream (in which case strm->msg is set to indicate the nature
 1033    of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
 1034    In the case of Z_BUF_ERROR, an input or output error can be distinguished
 1035    using strm->next_in which will be Z_NULL only if in() returned an error.  If
 1036    strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
 1037    non-zero.  (in() will always be called before out(), so strm->next_in is
 1038    assured to be defined if out() returns non-zero.) Note that inflateBack()
 1039    cannot return Z_OK.
 1040 */
 1041 
 1042 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
 1043 /*
 1044      All memory allocated by inflateBackInit() is freed.
 1045 
 1046      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
 1047    state was inconsistent.
 1048 */
 1049 
 1050 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
 1051 /* Return flags indicating compile-time options.
 1052 
 1053     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
 1054      1.0: size of uInt
 1055      3.2: size of uLong
 1056      5.4: size of voidpf (pointer)
 1057      7.6: size of z_off_t
 1058 
 1059     Compiler, assembler, and debug options:
 1060      8: DEBUG
 1061      9: ASMV or ASMINF -- use ASM code
 1062      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
 1063      11: 0 (reserved)
 1064 
 1065     One-time table building (smaller code, but not thread-safe if true):
 1066      12: BUILDFIXED -- build static block decoding tables when needed
 1067      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
 1068      14,15: 0 (reserved)
 1069 
 1070     Library content (indicates missing functionality):
 1071      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
 1072                           deflate code when not needed)
 1073      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
 1074                     and decode gzip streams (to avoid linking crc code)
 1075      18-19: 0 (reserved)
 1076 
 1077     Operation variations (changes in library functionality):
 1078      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
 1079      21: FASTEST -- deflate algorithm with only one, lowest compression level
 1080      22,23: 0 (reserved)
 1081 
 1082     The sprintf variant used by gzprintf (zero is best):
 1083      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
 1084      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
 1085      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
 1086 
 1087     Remainder:
 1088      27-31: 0 (reserved)
 1089  */
 1090 
 1091 
 1092                         /* utility functions */
 1093 
 1094 /*
 1095      The following utility functions are implemented on top of the basic
 1096    stream-oriented functions.  To simplify the interface, some default options
 1097    are assumed (compression level and memory usage, standard memory allocation
 1098    functions).  The source code of these utility functions can be modified if
 1099    you need special options.
 1100 */
 1101 
 1102 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
 1103                                  const Bytef *source, uLong sourceLen));
 1104 /*
 1105      Compresses the source buffer into the destination buffer.  sourceLen is
 1106    the byte length of the source buffer.  Upon entry, destLen is the total size
 1107    of the destination buffer, which must be at least the value returned by
 1108    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
 1109    compressed buffer.
 1110 
 1111      compress returns Z_OK if success, Z_MEM_ERROR if there was not
 1112    enough memory, Z_BUF_ERROR if there was not enough room in the output
 1113    buffer.
 1114 */
 1115 
 1116 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
 1117                                   const Bytef *source, uLong sourceLen,
 1118                                   int level));
 1119 /*
 1120      Compresses the source buffer into the destination buffer.  The level
 1121    parameter has the same meaning as in deflateInit.  sourceLen is the byte
 1122    length of the source buffer.  Upon entry, destLen is the total size of the
 1123    destination buffer, which must be at least the value returned by
 1124    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
 1125    compressed buffer.
 1126 
 1127      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 1128    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
 1129    Z_STREAM_ERROR if the level parameter is invalid.
 1130 */
 1131 
 1132 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
 1133 /*
 1134      compressBound() returns an upper bound on the compressed size after
 1135    compress() or compress2() on sourceLen bytes.  It would be used before a
 1136    compress() or compress2() call to allocate the destination buffer.
 1137 */
 1138 
 1139 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
 1140                                    const Bytef *source, uLong sourceLen));
 1141 /*
 1142      Decompresses the source buffer into the destination buffer.  sourceLen is
 1143    the byte length of the source buffer.  Upon entry, destLen is the total size
 1144    of the destination buffer, which must be large enough to hold the entire
 1145    uncompressed data.  (The size of the uncompressed data must have been saved
 1146    previously by the compressor and transmitted to the decompressor by some
 1147    mechanism outside the scope of this compression library.) Upon exit, destLen
 1148    is the actual size of the uncompressed buffer.
 1149 
 1150      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
 1151    enough memory, Z_BUF_ERROR if there was not enough room in the output
 1152    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
 1153 */
 1154 
 1155 
 1156                         /* gzip file access functions */
 1157 
 1158 /*
 1159      This library supports reading and writing files in gzip (.gz) format with
 1160    an interface similar to that of stdio, using the functions that start with
 1161    "gz".  The gzip format is different from the zlib format.  gzip is a gzip
 1162    wrapper, documented in RFC 1952, wrapped around a deflate stream.
 1163 */
 1164 
 1165 typedef voidp gzFile;       /* opaque gzip file descriptor */
 1166 
 1167 /*
 1168 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
 1169 
 1170      Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
 1171    in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
 1172    a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
 1173    compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
 1174    for fixed code compression as in "wb9F".  (See the description of
 1175    deflateInit2 for more information about the strategy parameter.) Also "a"
 1176    can be used instead of "w" to request that the gzip stream that will be
 1177    written be appended to the file.  "+" will result in an error, since reading
 1178    and writing to the same gzip file is not supported.
 1179 
 1180      gzopen can be used to read a file which is not in gzip format; in this
 1181    case gzread will directly read from the file without decompression.
 1182 
 1183      gzopen returns NULL if the file could not be opened, if there was
 1184    insufficient memory to allocate the gzFile state, or if an invalid mode was
 1185    specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
 1186    errno can be checked to determine if the reason gzopen failed was that the
 1187    file could not be opened.
 1188 */
 1189 
 1190 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
 1191 /*
 1192      gzdopen associates a gzFile with the file descriptor fd.  File descriptors
 1193    are obtained from calls like open, dup, creat, pipe or fileno (if the file
 1194    has been previously opened with fopen).  The mode parameter is as in gzopen.
 1195 
 1196      The next call of gzclose on the returned gzFile will also close the file
 1197    descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
 1198    fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
 1199    mode);.  The duplicated descriptor should be saved to avoid a leak, since
 1200    gzdopen does not close fd if it fails.
 1201 
 1202      gzdopen returns NULL if there was insufficient memory to allocate the
 1203    gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
 1204    provided, or '+' was provided), or if fd is -1.  The file descriptor is not
 1205    used until the next gz* read, write, seek, or close operation, so gzdopen
 1206    will not detect if fd is invalid (unless fd is -1).
 1207 */
 1208 
 1209 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
 1210 /*
 1211      Set the internal buffer size used by this library's functions.  The
 1212    default buffer size is 8192 bytes.  This function must be called after
 1213    gzopen() or gzdopen(), and before any other calls that read or write the
 1214    file.  The buffer memory allocation is always deferred to the first read or
 1215    write.  Two buffers are allocated, either both of the specified size when
 1216    writing, or one of the specified size and the other twice that size when
 1217    reading.  A larger buffer size of, for example, 64K or 128K bytes will
 1218    noticeably increase the speed of decompression (reading).
 1219 
 1220      The new buffer size also affects the maximum length for gzprintf().
 1221 
 1222      gzbuffer() returns 0 on success, or -1 on failure, such as being called
 1223    too late.
 1224 */
 1225 
 1226 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
 1227 /*
 1228      Dynamically update the compression level or strategy.  See the description
 1229    of deflateInit2 for the meaning of these parameters.
 1230 
 1231      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
 1232    opened for writing.
 1233 */
 1234 
 1235 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
 1236 /*
 1237      Reads the given number of uncompressed bytes from the compressed file.  If
 1238    the input file was not in gzip format, gzread copies the given number of
 1239    bytes into the buffer.
 1240 
 1241      After reaching the end of a gzip stream in the input, gzread will continue
 1242    to read, looking for another gzip stream, or failing that, reading the rest
 1243    of the input file directly without decompression.  The entire input file
 1244    will be read if gzread is called until it returns less than the requested
 1245    len.
 1246 
 1247      gzread returns the number of uncompressed bytes actually read, less than
 1248    len for end of file, or -1 for error.
 1249 */
 1250 
 1251 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
 1252                                 voidpc buf, unsigned len));
 1253 /*
 1254      Writes the given number of uncompressed bytes into the compressed file.
 1255    gzwrite returns the number of uncompressed bytes written or 0 in case of
 1256    error.
 1257 */
 1258 
 1259 ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
 1260 /*
 1261      Converts, formats, and writes the arguments to the compressed file under
 1262    control of the format string, as in fprintf.  gzprintf returns the number of
 1263    uncompressed bytes actually written, or 0 in case of error.  The number of
 1264    uncompressed bytes written is limited to 8191, or one less than the buffer
 1265    size given to gzbuffer().  The caller should assure that this limit is not
 1266    exceeded.  If it is exceeded, then gzprintf() will return an error (0) with
 1267    nothing written.  In this case, there may also be a buffer overflow with
 1268    unpredictable consequences, which is possible only if zlib was compiled with
 1269    the insecure functions sprintf() or vsprintf() because the secure snprintf()
 1270    or vsnprintf() functions were not available.  This can be determined using
 1271    zlibCompileFlags().
 1272 */
 1273 
 1274 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
 1275 /*
 1276      Writes the given null-terminated string to the compressed file, excluding
 1277    the terminating null character.
 1278 
 1279      gzputs returns the number of characters written, or -1 in case of error.
 1280 */
 1281 
 1282 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
 1283 /*
 1284      Reads bytes from the compressed file until len-1 characters are read, or a
 1285    newline character is read and transferred to buf, or an end-of-file
 1286    condition is encountered.  If any characters are read or if len == 1, the
 1287    string is terminated with a null character.  If no characters are read due
 1288    to an end-of-file or len < 1, then the buffer is left untouched.
 1289 
 1290      gzgets returns buf which is a null-terminated string, or it returns NULL
 1291    for end-of-file or in case of error.  If there was an error, the contents at
 1292    buf are indeterminate.
 1293 */
 1294 
 1295 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
 1296 /*
 1297      Writes c, converted to an unsigned char, into the compressed file.  gzputc
 1298    returns the value that was written, or -1 in case of error.
 1299 */
 1300 
 1301 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
 1302 /*
 1303      Reads one byte from the compressed file.  gzgetc returns this byte or -1
 1304    in case of end of file or error.
 1305 */
 1306 
 1307 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
 1308 /*
 1309      Push one character back onto the stream to be read as the first character
 1310    on the next read.  At least one character of push-back is allowed.
 1311    gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
 1312    fail if c is -1, and may fail if a character has been pushed but not read
 1313    yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
 1314    output buffer size of pushed characters is allowed.  (See gzbuffer above.)
 1315    The pushed character will be discarded if the stream is repositioned with
 1316    gzseek() or gzrewind().
 1317 */
 1318 
 1319 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
 1320 /*
 1321      Flushes all pending output into the compressed file.  The parameter flush
 1322    is as in the deflate() function.  The return value is the zlib error number
 1323    (see function gzerror below).  gzflush is only permitted when writing.
 1324 
 1325      If the flush parameter is Z_FINISH, the remaining data is written and the
 1326    gzip stream is completed in the output.  If gzwrite() is called again, a new
 1327    gzip stream will be started in the output.  gzread() is able to read such
 1328    concatented gzip streams.
 1329 
 1330      gzflush should be called only when strictly necessary because it will
 1331    degrade compression if called too often.
 1332 */
 1333 
 1334 /*
 1335 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
 1336                                    z_off_t offset, int whence));
 1337 
 1338      Sets the starting position for the next gzread or gzwrite on the given
 1339    compressed file.  The offset represents a number of bytes in the
 1340    uncompressed data stream.  The whence parameter is defined as in lseek(2);
 1341    the value SEEK_END is not supported.
 1342 
 1343      If the file is opened for reading, this function is emulated but can be
 1344    extremely slow.  If the file is opened for writing, only forward seeks are
 1345    supported; gzseek then compresses a sequence of zeroes up to the new
 1346    starting position.
 1347 
 1348      gzseek returns the resulting offset location as measured in bytes from
 1349    the beginning of the uncompressed stream, or -1 in case of error, in
 1350    particular if the file is opened for writing and the new starting position
 1351    would be before the current position.
 1352 */
 1353 
 1354 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
 1355 /*
 1356      Rewinds the given file. This function is supported only for reading.
 1357 
 1358      gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
 1359 */
 1360 
 1361 /*
 1362 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
 1363 
 1364      Returns the starting position for the next gzread or gzwrite on the given
 1365    compressed file.  This position represents a number of bytes in the
 1366    uncompressed data stream, and is zero when starting, even if appending or
 1367    reading a gzip stream from the middle of a file using gzdopen().
 1368 
 1369      gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
 1370 */
 1371 
 1372 /*
 1373 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
 1374 
 1375      Returns the current offset in the file being read or written.  This offset
 1376    includes the count of bytes that precede the gzip stream, for example when
 1377    appending or when using gzdopen() for reading.  When reading, the offset
 1378    does not include as yet unused buffered input.  This information can be used
 1379    for a progress indicator.  On error, gzoffset() returns -1.
 1380 */
 1381 
 1382 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
 1383 /*
 1384      Returns true (1) if the end-of-file indicator has been set while reading,
 1385    false (0) otherwise.  Note that the end-of-file indicator is set only if the
 1386    read tried to go past the end of the input, but came up short.  Therefore,
 1387    just like feof(), gzeof() may return false even if there is no more data to
 1388    read, in the event that the last read request was for the exact number of
 1389    bytes remaining in the input file.  This will happen if the input file size
 1390    is an exact multiple of the buffer size.
 1391 
 1392      If gzeof() returns true, then the read functions will return no more data,
 1393    unless the end-of-file indicator is reset by gzclearerr() and the input file
 1394    has grown since the previous end of file was detected.
 1395 */
 1396 
 1397 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
 1398 /*
 1399      Returns true (1) if file is being copied directly while reading, or false
 1400    (0) if file is a gzip stream being decompressed.  This state can change from
 1401    false to true while reading the input file if the end of a gzip stream is
 1402    reached, but is followed by data that is not another gzip stream.
 1403 
 1404      If the input file is empty, gzdirect() will return true, since the input
 1405    does not contain a gzip stream.
 1406 
 1407      If gzdirect() is used immediately after gzopen() or gzdopen() it will
 1408    cause buffers to be allocated to allow reading the file to determine if it
 1409    is a gzip file.  Therefore if gzbuffer() is used, it should be called before
 1410    gzdirect().
 1411 */
 1412 
 1413 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
 1414 /*
 1415      Flushes all pending output if necessary, closes the compressed file and
 1416    deallocates the (de)compression state.  Note that once file is closed, you
 1417    cannot call gzerror with file, since its structures have been deallocated.
 1418    gzclose must not be called more than once on the same file, just as free
 1419    must not be called more than once on the same allocation.
 1420 
 1421      gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
 1422    file operation error, or Z_OK on success.
 1423 */
 1424 
 1425 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
 1426 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
 1427 /*
 1428      Same as gzclose(), but gzclose_r() is only for use when reading, and
 1429    gzclose_w() is only for use when writing or appending.  The advantage to
 1430    using these instead of gzclose() is that they avoid linking in zlib
 1431    compression or decompression code that is not used when only reading or only
 1432    writing respectively.  If gzclose() is used, then both compression and
 1433    decompression code will be included the application when linking to a static
 1434    zlib library.
 1435 */
 1436 
 1437 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
 1438 /*
 1439      Returns the error message for the last error which occurred on the given
 1440    compressed file.  errnum is set to zlib error number.  If an error occurred
 1441    in the file system and not in the compression library, errnum is set to
 1442    Z_ERRNO and the application may consult errno to get the exact error code.
 1443 
 1444      The application must not modify the returned string.  Future calls to
 1445    this function may invalidate the previously returned string.  If file is
 1446    closed, then the string previously returned by gzerror will no longer be
 1447    available.
 1448 
 1449      gzerror() should be used to distinguish errors from end-of-file for those
 1450    functions above that do not distinguish those cases in their return values.
 1451 */
 1452 
 1453 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
 1454 /*
 1455      Clears the error and end-of-file flags for file.  This is analogous to the
 1456    clearerr() function in stdio.  This is useful for continuing to read a gzip
 1457    file that is being written concurrently.
 1458 */
 1459 
 1460 
 1461                         /* checksum functions */
 1462 
 1463 /*
 1464      These functions are not related to compression but are exported
 1465    anyway because they might be useful in applications using the compression
 1466    library.
 1467 */
 1468 
 1469 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
 1470 /*
 1471      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
 1472    return the updated checksum.  If buf is Z_NULL, this function returns the
 1473    required initial value for the checksum.
 1474 
 1475      An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
 1476    much faster.
 1477 
 1478    Usage example:
 1479 
 1480      uLong adler = adler32(0L, Z_NULL, 0);
 1481 
 1482      while (read_buffer(buffer, length) != EOF) {
 1483        adler = adler32(adler, buffer, length);
 1484      }
 1485      if (adler != original_adler) error();
 1486 */
 1487 
 1488 /*
 1489 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
 1490                                           z_off_t len2));
 1491 
 1492      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
 1493    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
 1494    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
 1495    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
 1496 */
 1497 
 1498 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
 1499 /*
 1500      Update a running CRC-32 with the bytes buf[0..len-1] and return the
 1501    updated CRC-32.  If buf is Z_NULL, this function returns the required
 1502    initial value for the for the crc.  Pre- and post-conditioning (one's
 1503    complement) is performed within this function so it shouldn't be done by the
 1504    application.
 1505 
 1506    Usage example:
 1507 
 1508      uLong crc = crc32(0L, Z_NULL, 0);
 1509 
 1510      while (read_buffer(buffer, length) != EOF) {
 1511        crc = crc32(crc, buffer, length);
 1512      }
 1513      if (crc != original_crc) error();
 1514 */
 1515 
 1516 /*
 1517 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
 1518 
 1519      Combine two CRC-32 check values into one.  For two sequences of bytes,
 1520    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
 1521    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
 1522    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
 1523    len2.
 1524 */
 1525 
 1526 
 1527                         /* various hacks, don't look :) */
 1528 
 1529 /* deflateInit and inflateInit are macros to allow checking the zlib version
 1530  * and the compiler's view of z_stream:
 1531  */
 1532 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
 1533                                      const char *version, int stream_size));
 1534 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
 1535                                      const char *version, int stream_size));
 1536 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
 1537                                       int windowBits, int memLevel,
 1538                                       int strategy, const char *version,
 1539                                       int stream_size));
 1540 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
 1541                                       const char *version, int stream_size));
 1542 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
 1543                                          unsigned char FAR *window,
 1544                                          const char *version,
 1545                                          int stream_size));
 1546 #define deflateInit(strm, level) \
 1547         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
 1548 #define inflateInit(strm) \
 1549         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
 1550 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
 1551         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
 1552                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
 1553 #define inflateInit2(strm, windowBits) \
 1554         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
 1555 #define inflateBackInit(strm, windowBits, window) \
 1556         inflateBackInit_((strm), (windowBits), (window), \
 1557                                             ZLIB_VERSION, sizeof(z_stream))
 1558 
 1559 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
 1560  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
 1561  * both are true, the application gets the *64 functions, and the regular
 1562  * functions are changed to 64 bits) -- in case these are set on systems
 1563  * without large file support, _LFS64_LARGEFILE must also be true
 1564  */
 1565 #if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
 1566    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
 1567    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
 1568    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
 1569    ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
 1570    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
 1571    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
 1572 #endif
 1573 
 1574 #if !defined(ZLIB_INTERNAL) && _FILE_OFFSET_BITS-0 == 64 && _LFS64_LARGEFILE-0
 1575 #  define gzopen gzopen64
 1576 #  define gzseek gzseek64
 1577 #  define gztell gztell64
 1578 #  define gzoffset gzoffset64
 1579 #  define adler32_combine adler32_combine64
 1580 #  define crc32_combine crc32_combine64
 1581 #  ifdef _LARGEFILE64_SOURCE
 1582      ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
 1583      ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
 1584      ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
 1585      ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
 1586      ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
 1587      ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
 1588 #  endif
 1589 #else
 1590    ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
 1591    ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
 1592    ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
 1593    ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
 1594    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
 1595    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
 1596 #endif
 1597 
 1598 /* hack for buggy compilers */
 1599 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
 1600     struct internal_state {int dummy;};
 1601 #endif
 1602 
 1603 /* undocumented functions */
 1604 ZEXTERN const char   * ZEXPORT zError           OF((int));
 1605 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
 1606 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
 1607 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
 1608 
 1609 #ifdef __cplusplus
 1610 }
 1611 #endif
 1612 
 1613 #endif /* ZLIB_H */