FreeBSD/Linux Kernel Cross Reference
sys/contrib/zlib/zlib.h

     /* zlib.h -- interface of the 'zlib' general purpose compression library
       version 1.2.12, March 11th, 2022
     
       Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler
     
       This software is provided 'as-is', without any express or implied
       warranty.  In no event will the authors be held liable for any damages
       arising from the use of this software.
     
      Permission is granted to anyone to use this software for any purpose,
      including commercial applications, and to alter it and redistribute it
      freely, subject to the following restrictions:
    
      1. The origin of this software must not be misrepresented; you must not
         claim that you wrote the original software. If you use this software
         in a product, an acknowledgment in the product documentation would be
         appreciated but is not required.
      2. Altered source versions must be plainly marked as such, and must not be
         misrepresented as being the original software.
      3. This notice may not be removed or altered from any source distribution.
    
      Jean-loup Gailly        Mark Adler
      jloup@gzip.org          madler@alumni.caltech.edu
    
    
      The data format used by the zlib library is described by RFCs (Request for
      Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
      (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
    */
    
    #ifndef ZLIB_H
    #define ZLIB_H
    
    #include "zconf.h"
    
    #ifdef __cplusplus
    extern "C" {
    #endif
    
    #define ZLIB_VERSION "1.2.12"
    #define ZLIB_VERNUM 0x12c0
    #define ZLIB_VER_MAJOR 1
    #define ZLIB_VER_MINOR 2
    #define ZLIB_VER_REVISION 12
    #define ZLIB_VER_SUBREVISION 0
    
    /*
        The 'zlib' compression library provides in-memory compression and
      decompression functions, including integrity checks of the uncompressed data.
      This version of the library supports only one compression method (deflation)
      but other algorithms will be added later and will have the same stream
      interface.
    
        Compression can be done in a single step if the buffers are large enough,
      or can be done by repeated calls of the compression function.  In the latter
      case, the application must provide more input and/or consume the output
      (providing more output space) before each call.
    
        The compressed data format used by default by the in-memory functions is
      the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
      around a deflate stream, which is itself documented in RFC 1951.
    
        The library also supports reading and writing files in gzip (.gz) format
      with an interface similar to that of stdio using the functions that start
      with "gz".  The gzip format is different from the zlib format.  gzip is a
      gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
    
        This library can optionally read and write gzip and raw deflate streams in
      memory as well.
    
        The zlib format was designed to be compact and fast for use in memory
      and on communications channels.  The gzip format was designed for single-
      file compression on file systems, has a larger header than zlib to maintain
      directory information, and uses a different, slower check method than zlib.
    
        The library does not install any signal handler.  The decoder checks
      the consistency of the compressed data, so the library should never crash
      even in the case of corrupted input.
    */
    
    typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
    typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
    
    struct internal_state;
    
    typedef struct z_stream_s {
        z_const Bytef *next_in;     /* next input byte */
        uInt     avail_in;  /* number of bytes available at next_in */
        uLong    total_in;  /* total number of input bytes read so far */
    
        Bytef    *next_out; /* next output byte will go here */
        uInt     avail_out; /* remaining free space at next_out */
        uLong    total_out; /* total number of bytes output so far */
    
        z_const char *msg;  /* last error message, NULL if no error */
        struct internal_state FAR *state; /* not visible by applications */
    
        alloc_func zalloc;  /* used to allocate the internal state */
        free_func  zfree;   /* used to free the internal state */
       voidpf     opaque;  /* private data object passed to zalloc and zfree */
   
       int     data_type;  /* best guess about the data type: binary or text
                              for deflate, or the decoding state for inflate */
       uLong   adler;      /* Adler-32 or CRC-32 value of the uncompressed data */
       uLong   reserved;   /* reserved for future use */
   } z_stream;
   
   typedef z_stream FAR *z_streamp;
   
   /*
        gzip header information passed to and from zlib routines.  See RFC 1952
     for more details on the meanings of these fields.
   */
   typedef struct gz_header_s {
       int     text;       /* true if compressed data believed to be text */
       uLong   time;       /* modification time */
       int     xflags;     /* extra flags (not used when writing a gzip file) */
       int     os;         /* operating system */
       Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
       uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
       uInt    extra_max;  /* space at extra (only when reading header) */
       Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
       uInt    name_max;   /* space at name (only when reading header) */
       Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
       uInt    comm_max;   /* space at comment (only when reading header) */
       int     hcrc;       /* true if there was or will be a header crc */
       int     done;       /* true when done reading gzip header (not used
                              when writing a gzip file) */
   } gz_header;
   
   typedef gz_header FAR *gz_headerp;
   
   /*
        The application must update next_in and avail_in when avail_in has dropped
      to zero.  It must update next_out and avail_out when avail_out has dropped
      to zero.  The application must initialize zalloc, zfree and opaque before
      calling the init function.  All other fields are set by the compression
      library and must not be updated by the application.
   
        The opaque value provided by the application will be passed as the first
      parameter for calls of zalloc and zfree.  This can be useful for custom
      memory management.  The compression library attaches no meaning to the
      opaque value.
   
        zalloc must return Z_NULL if there is not enough memory for the object.
      If zlib is used in a multi-threaded application, zalloc and zfree must be
      thread safe.  In that case, zlib is thread-safe.  When zalloc and zfree are
      Z_NULL on entry to the initialization function, they are set to internal
      routines that use the standard library functions malloc() and free().
   
        On 16-bit systems, the functions zalloc and zfree must be able to allocate
      exactly 65536 bytes, but will not be required to allocate more than this if
      the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
      returned by zalloc for objects of exactly 65536 bytes *must* have their
      offset normalized to zero.  The default allocation function provided by this
      library ensures this (see zutil.c).  To reduce memory requirements and avoid
      any allocation of 64K objects, at the expense of compression ratio, compile
      the library with -DMAX_WBITS=14 (see zconf.h).
   
        The fields total_in and total_out can be used for statistics or progress
      reports.  After compression, total_in holds the total size of the
      uncompressed data and may be saved for use by the decompressor (particularly
      if the decompressor wants to decompress everything in a single step).
   */
   
                           /* constants */
   
   #define Z_NO_FLUSH      0
   #define Z_PARTIAL_FLUSH 1
   #define Z_SYNC_FLUSH    2
   #define Z_FULL_FLUSH    3
   #define Z_FINISH        4
   #define Z_BLOCK         5
   #define Z_TREES         6
   /* Allowed flush values; see deflate() and inflate() below for details */
   
   #define Z_OK            0
   #define Z_STREAM_END    1
   #define Z_NEED_DICT     2
   #define Z_ERRNO        (-1)
   #define Z_STREAM_ERROR (-2)
   #define Z_DATA_ERROR   (-3)
   #define Z_MEM_ERROR    (-4)
   #define Z_BUF_ERROR    (-5)
   #define Z_VERSION_ERROR (-6)
   /* Return codes for the compression/decompression functions. Negative values
    * are errors, positive values are used for special but normal events.
    */
   
   #define Z_NO_COMPRESSION         0
   #define Z_BEST_SPEED             1
   #define Z_BEST_COMPRESSION       9
   #define Z_DEFAULT_COMPRESSION  (-1)
   /* compression levels */
   
   #define Z_FILTERED            1
   #define Z_HUFFMAN_ONLY        2
   #define Z_RLE                 3
   #define Z_FIXED               4
   #define Z_DEFAULT_STRATEGY    0
   /* compression strategy; see deflateInit2() below for details */
   
   #define Z_BINARY   0
   #define Z_TEXT     1
   #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
   #define Z_UNKNOWN  2
   /* Possible values of the data_type field for deflate() */
   
   #define Z_DEFLATED   8
   /* The deflate compression method (the only one supported in this version) */
   
   #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
   
   #define zlib_version zlibVersion()
   /* for compatibility with versions < 1.0.2 */
   
   
                           /* basic functions */
   
   ZEXTERN const char * ZEXPORT zlibVersion OF((void));
   /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
      If the first character differs, the library code actually used is not
      compatible with the zlib.h header file used by the application.  This check
      is automatically made by deflateInit and inflateInit.
    */
   
   /*
   ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
   
        Initializes the internal stream state for compression.  The fields
      zalloc, zfree and opaque must be initialized before by the caller.  If
      zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
      allocation functions.
   
        The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
      1 gives best speed, 9 gives best compression, 0 gives no compression at all
      (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
      requests a default compromise between speed and compression (currently
      equivalent to level 6).
   
        deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
      memory, Z_STREAM_ERROR if level is not a valid compression level, or
      Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
      with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
      if there is no error message.  deflateInit does not perform any compression:
      this will be done by deflate().
   */
   
   
   ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
   /*
       deflate compresses as much data as possible, and stops when the input
     buffer becomes empty or the output buffer becomes full.  It may introduce
     some output latency (reading input without producing any output) except when
     forced to flush.
   
       The detailed semantics are as follows.  deflate performs one or both of the
     following actions:
   
     - Compress more input starting at next_in and update next_in and avail_in
       accordingly.  If not all input can be processed (because there is not
       enough room in the output buffer), next_in and avail_in are updated and
       processing will resume at this point for the next call of deflate().
   
     - Generate more output starting at next_out and update next_out and avail_out
       accordingly.  This action is forced if the parameter flush is non zero.
       Forcing flush frequently degrades the compression ratio, so this parameter
       should be set only when necessary.  Some output may be provided even if
       flush is zero.
   
       Before the call of deflate(), the application should ensure that at least
     one of the actions is possible, by providing more input and/or consuming more
     output, and updating avail_in or avail_out accordingly; avail_out should
     never be zero before the call.  The application can consume the compressed
     output when it wants, for example when the output buffer is full (avail_out
     == 0), or after each call of deflate().  If deflate returns Z_OK and with
     zero avail_out, it must be called again after making room in the output
     buffer because there might be more output pending. See deflatePending(),
     which can be used if desired to determine whether or not there is more ouput
     in that case.
   
       Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
     decide how much data to accumulate before producing output, in order to
     maximize compression.
   
       If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
     flushed to the output buffer and the output is aligned on a byte boundary, so
     that the decompressor can get all input data available so far.  (In
     particular avail_in is zero after the call if enough output space has been
     provided before the call.) Flushing may degrade compression for some
     compression algorithms and so it should be used only when necessary.  This
     completes the current deflate block and follows it with an empty stored block
     that is three bits plus filler bits to the next byte, followed by four bytes
     (00 00 ff ff).
   
       If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
     output buffer, but the output is not aligned to a byte boundary.  All of the
     input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
     This completes the current deflate block and follows it with an empty fixed
     codes block that is 10 bits long.  This assures that enough bytes are output
     in order for the decompressor to finish the block before the empty fixed
     codes block.
   
       If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
     for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
     seven bits of the current block are held to be written as the next byte after
     the next deflate block is completed.  In this case, the decompressor may not
     be provided enough bits at this point in order to complete decompression of
     the data provided so far to the compressor.  It may need to wait for the next
     block to be emitted.  This is for advanced applications that need to control
     the emission of deflate blocks.
   
       If flush is set to Z_FULL_FLUSH, all output is flushed as with
     Z_SYNC_FLUSH, and the compression state is reset so that decompression can
     restart from this point if previous compressed data has been damaged or if
     random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
     compression.
   
       If deflate returns with avail_out == 0, this function must be called again
     with the same value of the flush parameter and more output space (updated
     avail_out), until the flush is complete (deflate returns with non-zero
     avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
     avail_out is greater than six to avoid repeated flush markers due to
     avail_out == 0 on return.
   
       If the parameter flush is set to Z_FINISH, pending input is processed,
     pending output is flushed and deflate returns with Z_STREAM_END if there was
     enough output space.  If deflate returns with Z_OK or Z_BUF_ERROR, this
     function must be called again with Z_FINISH and more output space (updated
     avail_out) but no more input data, until it returns with Z_STREAM_END or an
     error.  After deflate has returned Z_STREAM_END, the only possible operations
     on the stream are deflateReset or deflateEnd.
   
       Z_FINISH can be used in the first deflate call after deflateInit if all the
     compression is to be done in a single step.  In order to complete in one
     call, avail_out must be at least the value returned by deflateBound (see
     below).  Then deflate is guaranteed to return Z_STREAM_END.  If not enough
     output space is provided, deflate will not return Z_STREAM_END, and it must
     be called again as described above.
   
       deflate() sets strm->adler to the Adler-32 checksum of all input read
     so far (that is, total_in bytes).  If a gzip stream is being generated, then
     strm->adler will be the CRC-32 checksum of the input read so far.  (See
     deflateInit2 below.)
   
       deflate() may update strm->data_type if it can make a good guess about
     the input data type (Z_BINARY or Z_TEXT).  If in doubt, the data is
     considered binary.  This field is only for information purposes and does not
     affect the compression algorithm in any manner.
   
       deflate() returns Z_OK if some progress has been made (more input
     processed or more output produced), Z_STREAM_END if all input has been
     consumed and all output has been produced (only when flush is set to
     Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
     if next_in or next_out was Z_NULL or the state was inadvertently written over
     by the application), or Z_BUF_ERROR if no progress is possible (for example
     avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not fatal, and
     deflate() can be called again with more input and more output space to
     continue compressing.
   */
   
   
   ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
   /*
        All dynamically allocated data structures for this stream are freed.
      This function discards any unprocessed input and does not flush any pending
      output.
   
        deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
      stream state was inconsistent, Z_DATA_ERROR if the stream was freed
      prematurely (some input or output was discarded).  In the error case, msg
      may be set but then points to a static string (which must not be
      deallocated).
   */
   
   
   /*
   ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
   
        Initializes the internal stream state for decompression.  The fields
      next_in, avail_in, zalloc, zfree and opaque must be initialized before by
      the caller.  In the current version of inflate, the provided input is not
      read or consumed.  The allocation of a sliding window will be deferred to
      the first call of inflate (if the decompression does not complete on the
      first call).  If zalloc and zfree are set to Z_NULL, inflateInit updates
      them to use default allocation functions.
   
        inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
      memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
      version assumed by the caller, or Z_STREAM_ERROR if the parameters are
      invalid, such as a null pointer to the structure.  msg is set to null if
      there is no error message.  inflateInit does not perform any decompression.
      Actual decompression will be done by inflate().  So next_in, and avail_in,
      next_out, and avail_out are unused and unchanged.  The current
      implementation of inflateInit() does not process any header information --
      that is deferred until inflate() is called.
   */
   
   
   ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
   /*
       inflate decompresses as much data as possible, and stops when the input
     buffer becomes empty or the output buffer becomes full.  It may introduce
     some output latency (reading input without producing any output) except when
     forced to flush.
   
     The detailed semantics are as follows.  inflate performs one or both of the
     following actions:
   
     - Decompress more input starting at next_in and update next_in and avail_in
       accordingly.  If not all input can be processed (because there is not
       enough room in the output buffer), then next_in and avail_in are updated
       accordingly, and processing will resume at this point for the next call of
       inflate().
   
     - Generate more output starting at next_out and update next_out and avail_out
       accordingly.  inflate() provides as much output as possible, until there is
       no more input data or no more space in the output buffer (see below about
       the flush parameter).
   
       Before the call of inflate(), the application should ensure that at least
     one of the actions is possible, by providing more input and/or consuming more
     output, and updating the next_* and avail_* values accordingly.  If the
     caller of inflate() does not provide both available input and available
     output space, it is possible that there will be no progress made.  The
     application can consume the uncompressed output when it wants, for example
     when the output buffer is full (avail_out == 0), or after each call of
     inflate().  If inflate returns Z_OK and with zero avail_out, it must be
     called again after making room in the output buffer because there might be
     more output pending.
   
       The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
     Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
     output as possible to the output buffer.  Z_BLOCK requests that inflate()
     stop if and when it gets to the next deflate block boundary.  When decoding
     the zlib or gzip format, this will cause inflate() to return immediately
     after the header and before the first block.  When doing a raw inflate,
     inflate() will go ahead and process the first block, and will return when it
     gets to the end of that block, or when it runs out of data.
   
       The Z_BLOCK option assists in appending to or combining deflate streams.
     To assist in this, on return inflate() always sets strm->data_type to the
     number of unused bits in the last byte taken from strm->next_in, plus 64 if
     inflate() is currently decoding the last block in the deflate stream, plus
     128 if inflate() returned immediately after decoding an end-of-block code or
     decoding the complete header up to just before the first byte of the deflate
     stream.  The end-of-block will not be indicated until all of the uncompressed
     data from that block has been written to strm->next_out.  The number of
     unused bits may in general be greater than seven, except when bit 7 of
     data_type is set, in which case the number of unused bits will be less than
     eight.  data_type is set as noted here every time inflate() returns for all
     flush options, and so can be used to determine the amount of currently
     consumed input in bits.
   
       The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
     end of each deflate block header is reached, before any actual data in that
     block is decoded.  This allows the caller to determine the length of the
     deflate block header for later use in random access within a deflate block.
     256 is added to the value of strm->data_type when inflate() returns
     immediately after reaching the end of the deflate block header.
   
       inflate() should normally be called until it returns Z_STREAM_END or an
     error.  However if all decompression is to be performed in a single step (a
     single call of inflate), the parameter flush should be set to Z_FINISH.  In
     this case all pending input is processed and all pending output is flushed;
     avail_out must be large enough to hold all of the uncompressed data for the
     operation to complete.  (The size of the uncompressed data may have been
     saved by the compressor for this purpose.)  The use of Z_FINISH is not
     required to perform an inflation in one step.  However it may be used to
     inform inflate that a faster approach can be used for the single inflate()
     call.  Z_FINISH also informs inflate to not maintain a sliding window if the
     stream completes, which reduces inflate's memory footprint.  If the stream
     does not complete, either because not all of the stream is provided or not
     enough output space is provided, then a sliding window will be allocated and
     inflate() can be called again to continue the operation as if Z_NO_FLUSH had
     been used.
   
        In this implementation, inflate() always flushes as much output as
     possible to the output buffer, and always uses the faster approach on the
     first call.  So the effects of the flush parameter in this implementation are
     on the return value of inflate() as noted below, when inflate() returns early
     when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
     memory for a sliding window when Z_FINISH is used.
   
        If a preset dictionary is needed after this call (see inflateSetDictionary
     below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
     chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
     strm->adler to the Adler-32 checksum of all output produced so far (that is,
     total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
     below.  At the end of the stream, inflate() checks that its computed Adler-32
     checksum is equal to that saved by the compressor and returns Z_STREAM_END
     only if the checksum is correct.
   
       inflate() can decompress and check either zlib-wrapped or gzip-wrapped
     deflate data.  The header type is detected automatically, if requested when
     initializing with inflateInit2().  Any information contained in the gzip
     header is not retained unless inflateGetHeader() is used.  When processing
     gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
     produced so far.  The CRC-32 is checked against the gzip trailer, as is the
     uncompressed length, modulo 2^32.
   
       inflate() returns Z_OK if some progress has been made (more input processed
     or more output produced), Z_STREAM_END if the end of the compressed data has
     been reached and all uncompressed output has been produced, Z_NEED_DICT if a
     preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
     corrupted (input stream not conforming to the zlib format or incorrect check
     value, in which case strm->msg points to a string with a more specific
     error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
     next_in or next_out was Z_NULL, or the state was inadvertently written over
     by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
     if no progress was possible or if there was not enough room in the output
     buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
     inflate() can be called again with more input and more output space to
     continue decompressing.  If Z_DATA_ERROR is returned, the application may
     then call inflateSync() to look for a good compression block if a partial
     recovery of the data is to be attempted.
   */
   
   
   ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
   /*
        All dynamically allocated data structures for this stream are freed.
      This function discards any unprocessed input and does not flush any pending
      output.
   
        inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
      was inconsistent.
   */
   
   
                           /* Advanced functions */
   
   /*
       The following functions are needed only in some special applications.
   */
   
   /*
   ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
                                        int  level,
                                        int  method,
                                        int  windowBits,
                                        int  memLevel,
                                        int  strategy));
   
        This is another version of deflateInit with more compression options.  The
      fields zalloc, zfree and opaque must be initialized before by the caller.
   
        The method parameter is the compression method.  It must be Z_DEFLATED in
      this version of the library.
   
        The windowBits parameter is the base two logarithm of the window size
      (the size of the history buffer).  It should be in the range 8..15 for this
      version of the library.  Larger values of this parameter result in better
      compression at the expense of memory usage.  The default value is 15 if
      deflateInit is used instead.
   
        For the current implementation of deflate(), a windowBits value of 8 (a
      window size of 256 bytes) is not supported.  As a result, a request for 8
      will result in 9 (a 512-byte window).  In that case, providing 8 to
      inflateInit2() will result in an error when the zlib header with 9 is
      checked against the initialization of inflate().  The remedy is to not use 8
      with deflateInit2() with this initialization, or at least in that case use 9
      with inflateInit2().
   
        windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
      determines the window size.  deflate() will then generate raw deflate data
      with no zlib header or trailer, and will not compute a check value.
   
        windowBits can also be greater than 15 for optional gzip encoding.  Add
      16 to windowBits to write a simple gzip header and trailer around the
      compressed data instead of a zlib wrapper.  The gzip header will have no
      file name, no extra data, no comment, no modification time (set to zero), no
      header crc, and the operating system will be set to the appropriate value,
      if the operating system was determined at compile time.  If a gzip stream is
      being written, strm->adler is a CRC-32 instead of an Adler-32.
   
        For raw deflate or gzip encoding, a request for a 256-byte window is
      rejected as invalid, since only the zlib header provides a means of
      transmitting the window size to the decompressor.
   
        The memLevel parameter specifies how much memory should be allocated
      for the internal compression state.  memLevel=1 uses minimum memory but is
      slow and reduces compression ratio; memLevel=9 uses maximum memory for
      optimal speed.  The default value is 8.  See zconf.h for total memory usage
      as a function of windowBits and memLevel.
   
        The strategy parameter is used to tune the compression algorithm.  Use the
      value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
      filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
      string match), or Z_RLE to limit match distances to one (run-length
      encoding).  Filtered data consists mostly of small values with a somewhat
      random distribution.  In this case, the compression algorithm is tuned to
      compress them better.  The effect of Z_FILTERED is to force more Huffman
      coding and less string matching; it is somewhat intermediate between
      Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
      fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
      strategy parameter only affects the compression ratio but not the
      correctness of the compressed output even if it is not set appropriately.
      Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
      decoder for special applications.
   
        deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
      memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
      method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
      incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
      set to null if there is no error message.  deflateInit2 does not perform any
      compression: this will be done by deflate().
   */
   
   ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
                                                const Bytef *dictionary,
                                                uInt  dictLength));
   /*
        Initializes the compression dictionary from the given byte sequence
      without producing any compressed output.  When using the zlib format, this
      function must be called immediately after deflateInit, deflateInit2 or
      deflateReset, and before any call of deflate.  When doing raw deflate, this
      function must be called either before any call of deflate, or immediately
      after the completion of a deflate block, i.e. after all input has been
      consumed and all output has been delivered when using any of the flush
      options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
      compressor and decompressor must use exactly the same dictionary (see
      inflateSetDictionary).
   
        The dictionary should consist of strings (byte sequences) that are likely
      to be encountered later in the data to be compressed, with the most commonly
      used strings preferably put towards the end of the dictionary.  Using a
      dictionary is most useful when the data to be compressed is short and can be
      predicted with good accuracy; the data can then be compressed better than
      with the default empty dictionary.
   
        Depending on the size of the compression data structures selected by
      deflateInit or deflateInit2, a part of the dictionary may in effect be
      discarded, for example if the dictionary is larger than the window size
      provided in deflateInit or deflateInit2.  Thus the strings most likely to be
      useful should be put at the end of the dictionary, not at the front.  In
      addition, the current implementation of deflate will use at most the window
      size minus 262 bytes of the provided dictionary.
   
        Upon return of this function, strm->adler is set to the Adler-32 value
      of the dictionary; the decompressor may later use this value to determine
      which dictionary has been used by the compressor.  (The Adler-32 value
      applies to the whole dictionary even if only a subset of the dictionary is
      actually used by the compressor.) If a raw deflate was requested, then the
      Adler-32 value is not computed and strm->adler is not set.
   
        deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
      parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
      inconsistent (for example if deflate has already been called for this stream
      or if not at a block boundary for raw deflate).  deflateSetDictionary does
      not perform any compression: this will be done by deflate().
   */
   
   ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
                                                Bytef *dictionary,
                                                uInt  *dictLength));
   /*
        Returns the sliding dictionary being maintained by deflate.  dictLength is
      set to the number of bytes in the dictionary, and that many bytes are copied
      to dictionary.  dictionary must have enough space, where 32768 bytes is
      always enough.  If deflateGetDictionary() is called with dictionary equal to
      Z_NULL, then only the dictionary length is returned, and nothing is copied.
      Similary, if dictLength is Z_NULL, then it is not set.
   
        deflateGetDictionary() may return a length less than the window size, even
      when more than the window size in input has been provided. It may return up
      to 258 bytes less in that case, due to how zlib's implementation of deflate
      manages the sliding window and lookahead for matches, where matches can be
      up to 258 bytes long. If the application needs the last window-size bytes of
      input, then that would need to be saved by the application outside of zlib.
   
        deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
      stream state is inconsistent.
   */
   
   ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
                                       z_streamp source));
   /*
        Sets the destination stream as a complete copy of the source stream.
   
        This function can be useful when several compression strategies will be
      tried, for example when there are several ways of pre-processing the input
      data with a filter.  The streams that will be discarded should then be freed
      by calling deflateEnd.  Note that deflateCopy duplicates the internal
      compression state which can be quite large, so this strategy is slow and can
      consume lots of memory.
   
        deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
      (such as zalloc being Z_NULL).  msg is left unchanged in both source and
      destination.
   */
   
   ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
   /*
        This function is equivalent to deflateEnd followed by deflateInit, but
      does not free and reallocate the internal compression state.  The stream
      will leave the compression level and any other attributes that may have been
      set unchanged.
   
        deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent (such as zalloc or state being Z_NULL).
   */
   
   ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
                                         int level,
                                         int strategy));
   /*
        Dynamically update the compression level and compression strategy.  The
      interpretation of level and strategy is as in deflateInit2().  This can be
      used to switch between compression and straight copy of the input data, or
      to switch to a different kind of input data requiring a different strategy.
      If the compression approach (which is a function of the level) or the
      strategy is changed, and if there have been any deflate() calls since the
      state was initialized or reset, then the input available so far is
      compressed with the old level and strategy using deflate(strm, Z_BLOCK).
      There are three approaches for the compression levels 0, 1..3, and 4..9
      respectively.  The new level and strategy will take effect at the next call
      of deflate().
   
        If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
      not have enough output space to complete, then the parameter change will not
      take effect.  In this case, deflateParams() can be called again with the
      same parameters and more output space to try again.
   
        In order to assure a change in the parameters on the first try, the
      deflate stream should be flushed using deflate() with Z_BLOCK or other flush
      request until strm.avail_out is not zero, before calling deflateParams().
      Then no more input data should be provided before the deflateParams() call.
      If this is done, the old level and strategy will be applied to the data
      compressed before deflateParams(), and the new level and strategy will be
      applied to the the data compressed after deflateParams().
   
        deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
      state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
      there was not enough output space to complete the compression of the
      available input data before a change in the strategy or approach.  Note that
      in the case of a Z_BUF_ERROR, the parameters are not changed.  A return
      value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
      retried with more output space.
   */
   
   ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
                                       int good_length,
                                       int max_lazy,
                                       int nice_length,
                                       int max_chain));
   /*
        Fine tune deflate's internal compression parameters.  This should only be
      used by someone who understands the algorithm used by zlib's deflate for
      searching for the best matching string, and even then only by the most
      fanatic optimizer trying to squeeze out the last compressed bit for their
      specific input data.  Read the deflate.c source code for the meaning of the
      max_lazy, good_length, nice_length, and max_chain parameters.
   
        deflateTune() can be called after deflateInit() or deflateInit2(), and
      returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
    */
   
   ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
                                          uLong sourceLen));
   /*
        deflateBound() returns an upper bound on the compressed size after
      deflation of sourceLen bytes.  It must be called after deflateInit() or
      deflateInit2(), and after deflateSetHeader(), if used.  This would be used
      to allocate an output buffer for deflation in a single pass, and so would be
      called before deflate().  If that first deflate() call is provided the
      sourceLen input bytes, an output buffer allocated to the size returned by
      deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
      to return Z_STREAM_END.  Note that it is possible for the compressed size to
      be larger than the value returned by deflateBound() if flush options other
      than Z_FINISH or Z_NO_FLUSH are used.
   */
   
   ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
                                          unsigned *pending,
                                          int *bits));
   /*
        deflatePending() returns the number of bytes and bits of output that have
      been generated, but not yet provided in the available output.  The bytes not
      provided would be due to the available output space having being consumed.
      The number of bits of output not provided are between 0 and 7, where they
      await more bits to join them in order to fill out a full byte.  If pending
      or bits are Z_NULL, then those values are not set.
   
        deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent.
    */
   
   ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
                                        int bits,
                                        int value));
   /*
        deflatePrime() inserts bits in the deflate output stream.  The intent
      is that this function is used to start off the deflate output with the bits
      leftover from a previous deflate stream when appending to it.  As such, this
      function can only be used for raw deflate, and must be used before the first
      deflate() call after a deflateInit2() or deflateReset().  bits must be less
      than or equal to 16, and that many of the least significant bits of value
      will be inserted in the output.
   
        deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
      room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
      source stream state was inconsistent.
   */
   
   ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
                                            gz_headerp head));
   /*
        deflateSetHeader() provides gzip header information for when a gzip
      stream is requested by deflateInit2().  deflateSetHeader() may be called
      after deflateInit2() or deflateReset() and before the first call of
      deflate().  The text, time, os, extra field, name, and comment information
      in the provided gz_header structure are written to the gzip header (xflag is
      ignored -- the extra flags are set according to the compression level).  The
      caller must assure that, if not Z_NULL, name and comment are terminated with
      a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
      available there.  If hcrc is true, a gzip header crc is included.  Note that
      the current versions of the command-line version of gzip (up through version
      1.3.x) do not support header crc's, and will report that it is a "multi-part
      gzip file" and give up.
   
        If deflateSetHeader is not used, the default gzip header has text false,
      the time set to zero, and os set to 255, with no extra, name, or comment
      fields.  The gzip header is returned to the default state by deflateReset().
   
        deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent.
   */
   
   /*
   ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
                                        int  windowBits));
   
        This is another version of inflateInit with an extra parameter.  The
      fields next_in, avail_in, zalloc, zfree and opaque must be initialized
      before by the caller.
   
        The windowBits parameter is the base two logarithm of the maximum window
      size (the size of the history buffer).  It should be in the range 8..15 for
      this version of the library.  The default value is 15 if inflateInit is used
      instead.  windowBits must be greater than or equal to the windowBits value
      provided to deflateInit2() while compressing, or it must be equal to 15 if
      deflateInit2() was not used.  If a compressed stream with a larger window
      size is given as input, inflate() will return with the error code
      Z_DATA_ERROR instead of trying to allocate a larger window.
   
        windowBits can also be zero to request that inflate use the window size in
      the zlib header of the compressed stream.
   
        windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
      determines the window size.  inflate() will then process raw deflate data,
      not looking for a zlib or gzip header, not generating a check value, and not
      looking for any check values for comparison at the end of the stream.  This
      is for use with other formats that use the deflate compressed data format
      such as zip.  Those formats provide their own check values.  If a custom
      format is developed using the raw deflate format for compressed data, it is
      recommended that a check value such as an Adler-32 or a CRC-32 be applied to
      the uncompressed data as is done in the zlib, gzip, and zip formats.  For
      most applications, the zlib format should be used as is.  Note that comments
      above on the use in deflateInit2() applies to the magnitude of windowBits.
   
        windowBits can also be greater than 15 for optional gzip decoding.  Add
      32 to windowBits to enable zlib and gzip decoding with automatic header
      detection, or add 16 to decode only the gzip format (the zlib format will
      return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
      CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
      below), inflate() will *not* automatically decode concatenated gzip members.
      inflate() will return Z_STREAM_END at the end of the gzip member.  The state
      would need to be reset to continue decoding a subsequent gzip member.  This
      *must* be done if there is more data after a gzip member, in order for the
      decompression to be compliant with the gzip standard (RFC 1952).
   
        inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
      memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
      version assumed by the caller, or Z_STREAM_ERROR if the parameters are
      invalid, such as a null pointer to the structure.  msg is set to null if
      there is no error message.  inflateInit2 does not perform any decompression
      apart from possibly reading the zlib header if present: actual decompression
      will be done by inflate().  (So next_in and avail_in may be modified, but
      next_out and avail_out are unused and unchanged.) The current implementation
      of inflateInit2() does not process any header information -- that is
      deferred until inflate() is called.
   */
   
   ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
                                                const Bytef *dictionary,
                                                uInt  dictLength));
   /*
        Initializes the decompression dictionary from the given uncompressed byte
      sequence.  This function must be called immediately after a call of inflate,
      if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
      can be determined from the Adler-32 value returned by that call of inflate.
      The compressor and decompressor must use exactly the same dictionary (see
      deflateSetDictionary).  For raw inflate, this function can be called at any
      time to set the dictionary.  If the provided dictionary is smaller than the
      window and there is already data in the window, then the provided dictionary
      will amend what's there.  The application must insure that the dictionary
      that was used for compression is provided.
   
        inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
      parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
      inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
      expected one (incorrect Adler-32 value).  inflateSetDictionary does not
      perform any decompression: this will be done by subsequent calls of
      inflate().
   */
   
   ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
                                                Bytef *dictionary,
                                                uInt  *dictLength));
   /*
        Returns the sliding dictionary being maintained by inflate.  dictLength is
      set to the number of bytes in the dictionary, and that many bytes are copied
      to dictionary.  dictionary must have enough space, where 32768 bytes is
      always enough.  If inflateGetDictionary() is called with dictionary equal to
      Z_NULL, then only the dictionary length is returned, and nothing is copied.
      Similary, if dictLength is Z_NULL, then it is not set.
   
        inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
      stream state is inconsistent.
   */
   
   ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
   /*
        Skips invalid compressed data until a possible full flush point (see above
      for the description of deflate with Z_FULL_FLUSH) can be found, or until all
      available input is skipped.  No output is provided.
   
        inflateSync searches for a 00 00 FF FF pattern in the compressed data.
      All full flush points have this pattern, but not all occurrences of this
      pattern are full flush points.
   
        inflateSync returns Z_OK if a possible full flush point has been found,
      Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
      has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
      In the success case, the application may save the current current value of
      total_in which indicates where valid compressed data was found.  In the
      error case, the application may repeatedly call inflateSync, providing more
      input each time, until success or end of the input data.
   */
   
   ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
                                       z_streamp source));
   /*
        Sets the destination stream as a complete copy of the source stream.
   
        This function can be useful when randomly accessing a large stream.  The
      first pass through the stream can periodically record the inflate state,
      allowing restarting inflate at those points when randomly accessing the
      stream.
   
        inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
      (such as zalloc being Z_NULL).  msg is left unchanged in both source and
      destination.
   */
   
   ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
   /*
        This function is equivalent to inflateEnd followed by inflateInit,
      but does not free and reallocate the internal decompression state.  The
      stream will keep attributes that may have been set by inflateInit2.
   
        inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent (such as zalloc or state being Z_NULL).
   */
   
   ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
                                         int windowBits));
   /*
        This function is the same as inflateReset, but it also permits changing
      the wrap and window size requests.  The windowBits parameter is interpreted
      the same as it is for inflateInit2.  If the window size is changed, then the
      memory allocated for the window is freed, and the window will be reallocated
      by inflate() if needed.
   
        inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent (such as zalloc or state being Z_NULL), or if
      the windowBits parameter is invalid.
   */
   
   ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
                                        int bits,
                                        int value));
   /*
        This function inserts bits in the inflate input stream.  The intent is
      that this function is used to start inflating at a bit position in the
      middle of a byte.  The provided bits will be used before any bytes are used
      from next_in.  This function should only be used with raw inflate, and
      should be used before the first inflate() call after inflateInit2() or
      inflateReset().  bits must be less than or equal to 16, and that many of the
      least significant bits of value will be inserted in the input.
   
        If bits is negative, then the input stream bit buffer is emptied.  Then
      inflatePrime() can be called again to put bits in the buffer.  This is used
      to clear out bits leftover after feeding inflate a block description prior
      to feeding inflate codes.
   
       inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
     stream state was inconsistent.
  */
  
  ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
  /*
       This function returns two values, one in the lower 16 bits of the return
     value, and the other in the remaining upper bits, obtained by shifting the
     return value down 16 bits.  If the upper value is -1 and the lower value is
     zero, then inflate() is currently decoding information outside of a block.
     If the upper value is -1 and the lower value is non-zero, then inflate is in
     the middle of a stored block, with the lower value equaling the number of
     bytes from the input remaining to copy.  If the upper value is not -1, then
     it is the number of bits back from the current bit position in the input of
     the code (literal or length/distance pair) currently being processed.  In
     that case the lower value is the number of bytes already emitted for that
     code.
  
       A code is being processed if inflate is waiting for more input to complete
     decoding of the code, or if it has completed decoding but is waiting for
     more output space to write the literal or match data.
  
       inflateMark() is used to mark locations in the input data for random
     access, which may be at bit positions, and to note those cases where the
     output of a code may span boundaries of random access blocks.  The current
     location in the input stream can be determined from avail_in and data_type
     as noted in the description for the Z_BLOCK flush parameter for inflate.
  
       inflateMark returns the value noted above, or -65536 if the provided
     source stream state was inconsistent.
  */
  
  ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
                                           gz_headerp head));
  /*
       inflateGetHeader() requests that gzip header information be stored in the
     provided gz_header structure.  inflateGetHeader() may be called after
     inflateInit2() or inflateReset(), and before the first call of inflate().
     As inflate() processes the gzip stream, head->done is zero until the header
     is completed, at which time head->done is set to one.  If a zlib stream is
     being decoded, then head->done is set to -1 to indicate that there will be
     no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
     used to force inflate() to return immediately after header processing is
     complete and before any actual data is decompressed.
  
       The text, time, xflags, and os fields are filled in with the gzip header
     contents.  hcrc is set to true if there is a header CRC.  (The header CRC
     was valid if done is set to one.) If extra is not Z_NULL, then extra_max
     contains the maximum number of bytes to write to extra.  Once done is true,
     extra_len contains the actual extra field length, and extra contains the
     extra field, or that field truncated if extra_max is less than extra_len.
     If name is not Z_NULL, then up to name_max characters are written there,
     terminated with a zero unless the length is greater than name_max.  If
     comment is not Z_NULL, then up to comm_max characters are written there,
     terminated with a zero unless the length is greater than comm_max.  When any
     of extra, name, or comment are not Z_NULL and the respective field is not
     present in the header, then that field is set to Z_NULL to signal its
     absence.  This allows the use of deflateSetHeader() with the returned
     structure to duplicate the header.  However if those fields are set to
     allocated memory, then the application will need to save those pointers
     elsewhere so that they can be eventually freed.
  
       If inflateGetHeader is not used, then the header information is simply
     discarded.  The header is always checked for validity, including the header
     CRC if present.  inflateReset() will reset the process to discard the header
     information.  The application would need to call inflateGetHeader() again to
     retrieve the header from the next gzip stream.
  
       inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
     stream state was inconsistent.
  */
  
  /*
  ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
                                          unsigned char FAR *window));
  
       Initialize the internal stream state for decompression using inflateBack()
     calls.  The fields zalloc, zfree and opaque in strm must be initialized
     before the call.  If zalloc and zfree are Z_NULL, then the default library-
     derived memory allocation routines are used.  windowBits is the base two
     logarithm of the window size, in the range 8..15.  window is a caller
     supplied buffer of that size.  Except for special applications where it is
     assured that deflate was used with small window sizes, windowBits must be 15
     and a 32K byte window must be supplied to be able to decompress general
     deflate streams.
  
       See inflateBack() for the usage of these routines.
  
       inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
     the parameters are invalid, Z_MEM_ERROR if the internal state could not be
     allocated, or Z_VERSION_ERROR if the version of the library does not match
     the version of the header file.
  */
  
  typedef unsigned (*in_func) OF((void FAR *,
                                  z_const unsigned char FAR * FAR *));
  typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
  
  ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
                                      in_func in, void FAR *in_desc,
                                      out_func out, void FAR *out_desc));
  /*
       inflateBack() does a raw inflate with a single call using a call-back
     interface for input and output.  This is potentially more efficient than
     inflate() for file i/o applications, in that it avoids copying between the
     output and the sliding window by simply making the window itself the output
     buffer.  inflate() can be faster on modern CPUs when used with large
     buffers.  inflateBack() trusts the application to not change the output
     buffer passed by the output function, at least until inflateBack() returns.
  
       inflateBackInit() must be called first to allocate the internal state
     and to initialize the state with the user-provided window buffer.
     inflateBack() may then be used multiple times to inflate a complete, raw
     deflate stream with each call.  inflateBackEnd() is then called to free the
     allocated state.
  
       A raw deflate stream is one with no zlib or gzip header or trailer.
     This routine would normally be used in a utility that reads zip or gzip
     files and writes out uncompressed files.  The utility would decode the
     header and process the trailer on its own, hence this routine expects only
     the raw deflate stream to decompress.  This is different from the default
     behavior of inflate(), which expects a zlib header and trailer around the
     deflate stream.
  
       inflateBack() uses two subroutines supplied by the caller that are then
     called by inflateBack() for input and output.  inflateBack() calls those
     routines until it reads a complete deflate stream and writes out all of the
     uncompressed data, or until it encounters an error.  The function's
     parameters and return types are defined above in the in_func and out_func
     typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
     number of bytes of provided input, and a pointer to that input in buf.  If
     there is no input available, in() must return zero -- buf is ignored in that
     case -- and inflateBack() will return a buffer error.  inflateBack() will
     call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
     out() should return zero on success, or non-zero on failure.  If out()
     returns non-zero, inflateBack() will return with an error.  Neither in() nor
     out() are permitted to change the contents of the window provided to
     inflateBackInit(), which is also the buffer that out() uses to write from.
     The length written by out() will be at most the window size.  Any non-zero
     amount of input may be provided by in().
  
       For convenience, inflateBack() can be provided input on the first call by
     setting strm->next_in and strm->avail_in.  If that input is exhausted, then
     in() will be called.  Therefore strm->next_in must be initialized before
     calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
     immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
     must also be initialized, and then if strm->avail_in is not zero, input will
     initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
  
       The in_desc and out_desc parameters of inflateBack() is passed as the
     first parameter of in() and out() respectively when they are called.  These
     descriptors can be optionally used to pass any information that the caller-
     supplied in() and out() functions need to do their job.
  
       On return, inflateBack() will set strm->next_in and strm->avail_in to
     pass back any unused input that was provided by the last in() call.  The
     return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
     if in() or out() returned an error, Z_DATA_ERROR if there was a format error
     in the deflate stream (in which case strm->msg is set to indicate the nature
     of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
     In the case of Z_BUF_ERROR, an input or output error can be distinguished
     using strm->next_in which will be Z_NULL only if in() returned an error.  If
     strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
     non-zero.  (in() will always be called before out(), so strm->next_in is
     assured to be defined if out() returns non-zero.)  Note that inflateBack()
     cannot return Z_OK.
  */
  
  ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
  /*
       All memory allocated by inflateBackInit() is freed.
  
       inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
     state was inconsistent.
  */
  
  ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
  /* Return flags indicating compile-time options.
  
      Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
       1.0: size of uInt
       3.2: size of uLong
       5.4: size of voidpf (pointer)
       7.6: size of z_off_t
  
      Compiler, assembler, and debug options:
       8: ZLIB_DEBUG
       9: ASMV or ASMINF -- use ASM code
       10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
       11: 0 (reserved)
  
      One-time table building (smaller code, but not thread-safe if true):
       12: BUILDFIXED -- build static block decoding tables when needed
       13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
       14,15: 0 (reserved)
  
      Library content (indicates missing functionality):
       16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
                            deflate code when not needed)
       17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
                      and decode gzip streams (to avoid linking crc code)
       18-19: 0 (reserved)
  
      Operation variations (changes in library functionality):
       20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
       21: FASTEST -- deflate algorithm with only one, lowest compression level
       22,23: 0 (reserved)
  
      The sprintf variant used by gzprintf (zero is best):
       24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
       25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
       26: 0 = returns value, 1 = void -- 1 means inferred string length returned
  
      Remainder:
       27-31: 0 (reserved)
   */
  
  #if !defined(Z_SOLO) || defined(_KERNEL)
  
                          /* utility functions */
  
  /*
       The following utility functions are implemented on top of the basic
     stream-oriented functions.  To simplify the interface, some default options
     are assumed (compression level and memory usage, standard memory allocation
     functions).  The source code of these utility functions can be modified if
     you need special options.
  */
  
  ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
                                   const Bytef *source, uLong sourceLen));
  /*
       Compresses the source buffer into the destination buffer.  sourceLen is
     the byte length of the source buffer.  Upon entry, destLen is the total size
     of the destination buffer, which must be at least the value returned by
     compressBound(sourceLen).  Upon exit, destLen is the actual size of the
     compressed data.  compress() is equivalent to compress2() with a level
     parameter of Z_DEFAULT_COMPRESSION.
  
       compress returns Z_OK if success, Z_MEM_ERROR if there was not
     enough memory, Z_BUF_ERROR if there was not enough room in the output
     buffer.
  */
  
  ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
                                    const Bytef *source, uLong sourceLen,
                                    int level));
  /*
       Compresses the source buffer into the destination buffer.  The level
     parameter has the same meaning as in deflateInit.  sourceLen is the byte
     length of the source buffer.  Upon entry, destLen is the total size of the
     destination buffer, which must be at least the value returned by
     compressBound(sourceLen).  Upon exit, destLen is the actual size of the
     compressed data.
  
       compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
     memory, Z_BUF_ERROR if there was not enough room in the output buffer,
     Z_STREAM_ERROR if the level parameter is invalid.
  */
  
  ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
  /*
       compressBound() returns an upper bound on the compressed size after
     compress() or compress2() on sourceLen bytes.  It would be used before a
     compress() or compress2() call to allocate the destination buffer.
  */
  
  ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
                                     const Bytef *source, uLong sourceLen));
  /*
       Decompresses the source buffer into the destination buffer.  sourceLen is
     the byte length of the source buffer.  Upon entry, destLen is the total size
     of the destination buffer, which must be large enough to hold the entire
     uncompressed data.  (The size of the uncompressed data must have been saved
     previously by the compressor and transmitted to the decompressor by some
     mechanism outside the scope of this compression library.) Upon exit, destLen
     is the actual size of the uncompressed data.
  
       uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
     enough memory, Z_BUF_ERROR if there was not enough room in the output
     buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
     the case where there is not enough room, uncompress() will fill the output
     buffer with the uncompressed data up to that point.
  */
  
  ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest,   uLongf *destLen,
                                      const Bytef *source, uLong *sourceLen));
  /*
       Same as uncompress, except that sourceLen is a pointer, where the
     length of the source is *sourceLen.  On return, *sourceLen is the number of
     source bytes consumed.
  */
  #endif /* !Z_SOLO || _KERNEL */
  
  #ifndef Z_SOLO
  
                          /* gzip file access functions */
  
  /*
       This library supports reading and writing files in gzip (.gz) format with
     an interface similar to that of stdio, using the functions that start with
     "gz".  The gzip format is different from the zlib format.  gzip is a gzip
     wrapper, documented in RFC 1952, wrapped around a deflate stream.
  */
  
  typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
  
  /*
  ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
  
       Open the gzip (.gz) file at path for reading and decompressing, or
     compressing and writing.  The mode parameter is as in fopen ("rb" or "wb")
     but can also include a compression level ("wb9") or a strategy: 'f' for
     filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
     'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
     as in "wb9F".  (See the description of deflateInit2 for more information
     about the strategy parameter.)  'T' will request transparent writing or
     appending with no compression and not using the gzip format.
  
       "a" can be used instead of "w" to request that the gzip stream that will
     be written be appended to the file.  "+" will result in an error, since
     reading and writing to the same gzip file is not supported.  The addition of
     "x" when writing will create the file exclusively, which fails if the file
     already exists.  On systems that support it, the addition of "e" when
     reading or writing will set the flag to close the file on an execve() call.
  
       These functions, as well as gzip, will read and decode a sequence of gzip
     streams in a file.  The append function of gzopen() can be used to create
     such a file.  (Also see gzflush() for another way to do this.)  When
     appending, gzopen does not test whether the file begins with a gzip stream,
     nor does it look for the end of the gzip streams to begin appending.  gzopen
     will simply append a gzip stream to the existing file.
  
       gzopen can be used to read a file which is not in gzip format; in this
     case gzread will directly read from the file without decompression.  When
     reading, this will be detected automatically by looking for the magic two-
     byte gzip header.
  
       gzopen returns NULL if the file could not be opened, if there was
     insufficient memory to allocate the gzFile state, or if an invalid mode was
     specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
     errno can be checked to determine if the reason gzopen failed was that the
     file could not be opened.
  */
  
  ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
  /*
       Associate a gzFile with the file descriptor fd.  File descriptors are
     obtained from calls like open, dup, creat, pipe or fileno (if the file has
     been previously opened with fopen).  The mode parameter is as in gzopen.
  
       The next call of gzclose on the returned gzFile will also close the file
     descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
     fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
     mode);.  The duplicated descriptor should be saved to avoid a leak, since
     gzdopen does not close fd if it fails.  If you are using fileno() to get the
     file descriptor from a FILE *, then you will have to use dup() to avoid
     double-close()ing the file descriptor.  Both gzclose() and fclose() will
     close the associated file descriptor, so they need to have different file
     descriptors.
  
       gzdopen returns NULL if there was insufficient memory to allocate the
     gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
     provided, or '+' was provided), or if fd is -1.  The file descriptor is not
     used until the next gz* read, write, seek, or close operation, so gzdopen
     will not detect if fd is invalid (unless fd is -1).
  */
  
  ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
  /*
       Set the internal buffer size used by this library's functions for file to
     size.  The default buffer size is 8192 bytes.  This function must be called
     after gzopen() or gzdopen(), and before any other calls that read or write
     the file.  The buffer memory allocation is always deferred to the first read
     or write.  Three times that size in buffer space is allocated.  A larger
     buffer size of, for example, 64K or 128K bytes will noticeably increase the
     speed of decompression (reading).
  
       The new buffer size also affects the maximum length for gzprintf().
  
       gzbuffer() returns 0 on success, or -1 on failure, such as being called
     too late.
  */
  
  ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
  /*
       Dynamically update the compression level and strategy for file.  See the
     description of deflateInit2 for the meaning of these parameters. Previously
     provided data is flushed before applying the parameter changes.
  
       gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
     opened for writing, Z_ERRNO if there is an error writing the flushed data,
     or Z_MEM_ERROR if there is a memory allocation error.
  */
  
  ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
  /*
       Read and decompress up to len uncompressed bytes from file into buf.  If
     the input file is not in gzip format, gzread copies the given number of
     bytes into the buffer directly from the file.
  
       After reaching the end of a gzip stream in the input, gzread will continue
     to read, looking for another gzip stream.  Any number of gzip streams may be
     concatenated in the input file, and will all be decompressed by gzread().
     If something other than a gzip stream is encountered after a gzip stream,
     that remaining trailing garbage is ignored (and no error is returned).
  
       gzread can be used to read a gzip file that is being concurrently written.
     Upon reaching the end of the input, gzread will return with the available
     data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
     gzclearerr can be used to clear the end of file indicator in order to permit
     gzread to be tried again.  Z_OK indicates that a gzip stream was completed
     on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
     middle of a gzip stream.  Note that gzread does not return -1 in the event
     of an incomplete gzip stream.  This error is deferred until gzclose(), which
     will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
     stream.  Alternatively, gzerror can be used before gzclose to detect this
     case.
  
       gzread returns the number of uncompressed bytes actually read, less than
     len for end of file, or -1 for error.  If len is too large to fit in an int,
     then nothing is read, -1 is returned, and the error state is set to
     Z_STREAM_ERROR.
  */
  
  ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
                                       gzFile file));
  /*
       Read and decompress up to nitems items of size size from file into buf,
     otherwise operating as gzread() does.  This duplicates the interface of
     stdio's fread(), with size_t request and return types.  If the library
     defines size_t, then z_size_t is identical to size_t.  If not, then z_size_t
     is an unsigned integer type that can contain a pointer.
  
       gzfread() returns the number of full items read of size size, or zero if
     the end of the file was reached and a full item could not be read, or if
     there was an error.  gzerror() must be consulted if zero is returned in
     order to determine if there was an error.  If the multiplication of size and
     nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
     is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
  
       In the event that the end of file is reached and only a partial item is
     available at the end, i.e. the remaining uncompressed data length is not a
     multiple of size, then the final partial item is nevetheless read into buf
     and the end-of-file flag is set.  The length of the partial item read is not
     provided, but could be inferred from the result of gztell().  This behavior
     is the same as the behavior of fread() implementations in common libraries,
     but it prevents the direct use of gzfread() to read a concurrently written
     file, reseting and retrying on end-of-file, when size is not 1.
  */
  
  ZEXTERN int ZEXPORT gzwrite OF((gzFile file, voidpc buf, unsigned len));
  /*
       Compress and write the len uncompressed bytes at buf to file. gzwrite
     returns the number of uncompressed bytes written or 0 in case of error.
  */
  
  ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
                                        z_size_t nitems, gzFile file));
  /*
       Compress and write nitems items of size size from buf to file, duplicating
     the interface of stdio's fwrite(), with size_t request and return types.  If
     the library defines size_t, then z_size_t is identical to size_t.  If not,
     then z_size_t is an unsigned integer type that can contain a pointer.
  
       gzfwrite() returns the number of full items written of size size, or zero
     if there was an error.  If the multiplication of size and nitems overflows,
     i.e. the product does not fit in a z_size_t, then nothing is written, zero
     is returned, and the error state is set to Z_STREAM_ERROR.
  */
  
  ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
  /*
       Convert, format, compress, and write the arguments (...) to file under
     control of the string format, as in fprintf.  gzprintf returns the number of
     uncompressed bytes actually written, or a negative zlib error code in case
     of error.  The number of uncompressed bytes written is limited to 8191, or
     one less than the buffer size given to gzbuffer().  The caller should assure
     that this limit is not exceeded.  If it is exceeded, then gzprintf() will
     return an error (0) with nothing written.  In this case, there may also be a
     buffer overflow with unpredictable consequences, which is possible only if
     zlib was compiled with the insecure functions sprintf() or vsprintf(),
     because the secure snprintf() or vsnprintf() functions were not available.
     This can be determined using zlibCompileFlags().
  */
  
  ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
  /*
       Compress and write the given null-terminated string s to file, excluding
     the terminating null character.
  
       gzputs returns the number of characters written, or -1 in case of error.
  */
  
  ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
  /*
       Read and decompress bytes from file into buf, until len-1 characters are
     read, or until a newline character is read and transferred to buf, or an
     end-of-file condition is encountered.  If any characters are read or if len
     is one, the string is terminated with a null character.  If no characters
     are read due to an end-of-file or len is less than one, then the buffer is
     left untouched.
  
       gzgets returns buf which is a null-terminated string, or it returns NULL
     for end-of-file or in case of error.  If there was an error, the contents at
     buf are indeterminate.
  */
  
  ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
  /*
       Compress and write c, converted to an unsigned char, into file.  gzputc
     returns the value that was written, or -1 in case of error.
  */
  
  ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
  /*
       Read and decompress one byte from file.  gzgetc returns this byte or -1
     in case of end of file or error.  This is implemented as a macro for speed.
     As such, it does not do all of the checking the other functions do.  I.e.
     it does not check to see if file is NULL, nor whether the structure file
     points to has been clobbered or not.
  */
  
  ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
  /*
       Push c back onto the stream for file to be read as the first character on
     the next read.  At least one character of push-back is always allowed.
     gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
     fail if c is -1, and may fail if a character has been pushed but not read
     yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
     output buffer size of pushed characters is allowed.  (See gzbuffer above.)
     The pushed character will be discarded if the stream is repositioned with
     gzseek() or gzrewind().
  */
  
  ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
  /*
       Flush all pending output to file.  The parameter flush is as in the
     deflate() function.  The return value is the zlib error number (see function
     gzerror below).  gzflush is only permitted when writing.
  
       If the flush parameter is Z_FINISH, the remaining data is written and the
     gzip stream is completed in the output.  If gzwrite() is called again, a new
     gzip stream will be started in the output.  gzread() is able to read such
     concatenated gzip streams.
  
       gzflush should be called only when strictly necessary because it will
     degrade compression if called too often.
  */
  
  /*
  ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
                                     z_off_t offset, int whence));
  
       Set the starting position to offset relative to whence for the next gzread
     or gzwrite on file.  The offset represents a number of bytes in the
     uncompressed data stream.  The whence parameter is defined as in lseek(2);
     the value SEEK_END is not supported.
  
       If the file is opened for reading, this function is emulated but can be
     extremely slow.  If the file is opened for writing, only forward seeks are
     supported; gzseek then compresses a sequence of zeroes up to the new
     starting position.
  
       gzseek returns the resulting offset location as measured in bytes from
     the beginning of the uncompressed stream, or -1 in case of error, in
     particular if the file is opened for writing and the new starting position
     would be before the current position.
  */
  
  ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
  /*
       Rewind file. This function is supported only for reading.
  
       gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
  */
  
  /*
  ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
  
       Return the starting position for the next gzread or gzwrite on file.
     This position represents a number of bytes in the uncompressed data stream,
     and is zero when starting, even if appending or reading a gzip stream from
     the middle of a file using gzdopen().
  
       gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
  */
  
  /*
  ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
  
       Return the current compressed (actual) read or write offset of file.  This
     offset includes the count of bytes that precede the gzip stream, for example
     when appending or when using gzdopen() for reading.  When reading, the
     offset does not include as yet unused buffered input.  This information can
     be used for a progress indicator.  On error, gzoffset() returns -1.
  */
  
  ZEXTERN int ZEXPORT gzeof OF((gzFile file));
  /*
       Return true (1) if the end-of-file indicator for file has been set while
     reading, false (0) otherwise.  Note that the end-of-file indicator is set
     only if the read tried to go past the end of the input, but came up short.
     Therefore, just like feof(), gzeof() may return false even if there is no
     more data to read, in the event that the last read request was for the exact
     number of bytes remaining in the input file.  This will happen if the input
     file size is an exact multiple of the buffer size.
  
       If gzeof() returns true, then the read functions will return no more data,
     unless the end-of-file indicator is reset by gzclearerr() and the input file
     has grown since the previous end of file was detected.
  */
  
  ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
  /*
       Return true (1) if file is being copied directly while reading, or false
     (0) if file is a gzip stream being decompressed.
  
       If the input file is empty, gzdirect() will return true, since the input
     does not contain a gzip stream.
  
       If gzdirect() is used immediately after gzopen() or gzdopen() it will
     cause buffers to be allocated to allow reading the file to determine if it
     is a gzip file.  Therefore if gzbuffer() is used, it should be called before
     gzdirect().
  
       When writing, gzdirect() returns true (1) if transparent writing was
     requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
     gzdirect() is not needed when writing.  Transparent writing must be
     explicitly requested, so the application already knows the answer.  When
     linking statically, using gzdirect() will include all of the zlib code for
     gzip file reading and decompression, which may not be desired.)
  */
  
  ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
  /*
       Flush all pending output for file, if necessary, close file and
     deallocate the (de)compression state.  Note that once file is closed, you
     cannot call gzerror with file, since its structures have been deallocated.
     gzclose must not be called more than once on the same file, just as free
     must not be called more than once on the same allocation.
  
       gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
     file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
     last read ended in the middle of a gzip stream, or Z_OK on success.
  */
  
  ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
  ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
  /*
       Same as gzclose(), but gzclose_r() is only for use when reading, and
     gzclose_w() is only for use when writing or appending.  The advantage to
     using these instead of gzclose() is that they avoid linking in zlib
     compression or decompression code that is not used when only reading or only
     writing respectively.  If gzclose() is used, then both compression and
     decompression code will be included the application when linking to a static
     zlib library.
  */
  
  ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
  /*
       Return the error message for the last error which occurred on file.
     errnum is set to zlib error number.  If an error occurred in the file system
     and not in the compression library, errnum is set to Z_ERRNO and the
     application may consult errno to get the exact error code.
  
       The application must not modify the returned string.  Future calls to
     this function may invalidate the previously returned string.  If file is
     closed, then the string previously returned by gzerror will no longer be
     available.
  
       gzerror() should be used to distinguish errors from end-of-file for those
     functions above that do not distinguish those cases in their return values.
  */
  
  ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
  /*
       Clear the error and end-of-file flags for file.  This is analogous to the
     clearerr() function in stdio.  This is useful for continuing to read a gzip
     file that is being written concurrently.
  */
  
  #endif /* !Z_SOLO */
  
                          /* checksum functions */
  
  /*
       These functions are not related to compression but are exported
     anyway because they might be useful in applications using the compression
     library.
  */
  
  ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
  /*
       Update a running Adler-32 checksum with the bytes buf[0..len-1] and
     return the updated checksum. An Adler-32 value is in the range of a 32-bit
     unsigned integer. If buf is Z_NULL, this function returns the required
     initial value for the checksum.
  
       An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
     much faster.
  
     Usage example:
  
       uLong adler = adler32(0L, Z_NULL, 0);
  
       while (read_buffer(buffer, length) != EOF) {
         adler = adler32(adler, buffer, length);
       }
       if (adler != original_adler) error();
  */
  
  ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
                                      z_size_t len));
  /*
       Same as adler32(), but with a size_t length.
  */
  
  /*
  ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
                                            z_off_t len2));
  
       Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
     and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
     each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
     seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
     that the z_off_t type (like off_t) is a signed integer.  If len2 is
     negative, the result has no meaning or utility.
  */
  
  ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
  /*
       Update a running CRC-32 with the bytes buf[0..len-1] and return the
     updated CRC-32. A CRC-32 value is in the range of a 32-bit unsigned integer.
     If buf is Z_NULL, this function returns the required initial value for the
     crc. Pre- and post-conditioning (one's complement) is performed within this
     function so it shouldn't be done by the application.
  
     Usage example:
  
       uLong crc = crc32(0L, Z_NULL, 0);
  
       while (read_buffer(buffer, length) != EOF) {
         crc = crc32(crc, buffer, length);
       }
       if (crc != original_crc) error();
  */
  
  ZEXTERN uLong ZEXPORT crc32_z OF((uLong crc, const Bytef *buf,
                                    z_size_t len));
  /*
       Same as crc32(), but with a size_t length.
  */
  
  /*
  ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
  
       Combine two CRC-32 check values into one.  For two sequences of bytes,
     seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
     calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
     check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
     len2.
  */
  
  /*
  ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t len2));
  
       Return the operator corresponding to length len2, to be used with
     crc32_combine_op().
  */
  
  ZEXTERN uLong ZEXPORT crc32_combine_op OF((uLong crc1, uLong crc2, uLong op));
  /*
       Give the same result as crc32_combine(), using op in place of len2. op is
     is generated from len2 by crc32_combine_gen(). This will be faster than
     crc32_combine() if the generated op is used more than once.
  */
  
  
  ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off64_t));
  
                          /* various hacks, don't look :) */
  
  /* deflateInit and inflateInit are macros to allow checking the zlib version
   * and the compiler's view of z_stream:
   */
  ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
                                       const char *version, int stream_size));
  ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
                                       const char *version, int stream_size));
  ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
                                        int windowBits, int memLevel,
                                        int strategy, const char *version,
                                        int stream_size));
  ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
                                        const char *version, int stream_size));
  ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
                                           unsigned char FAR *window,
                                           const char *version,
                                           int stream_size));
  #ifdef Z_PREFIX_SET
  #  define z_deflateInit(strm, level) \
            deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
  #  define z_inflateInit(strm) \
            inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
  #  define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
            deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
                          (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
  #  define z_inflateInit2(strm, windowBits) \
            inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
                          (int)sizeof(z_stream))
  #  define z_inflateBackInit(strm, windowBits, window) \
            inflateBackInit_((strm), (windowBits), (window), \
                             ZLIB_VERSION, (int)sizeof(z_stream))
  #else
  #  define deflateInit(strm, level) \
            deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
  #  define inflateInit(strm) \
            inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
  #  define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
            deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
                          (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
  #  define inflateInit2(strm, windowBits) \
            inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
                          (int)sizeof(z_stream))
  #  define inflateBackInit(strm, windowBits, window) \
            inflateBackInit_((strm), (windowBits), (window), \
                             ZLIB_VERSION, (int)sizeof(z_stream))
  #endif
  
  #ifndef Z_SOLO
  
  /* gzgetc() macro and its supporting function and exposed data structure.  Note
   * that the real internal state is much larger than the exposed structure.
   * This abbreviated structure exposes just enough for the gzgetc() macro.  The
   * user should not mess with these exposed elements, since their names or
   * behavior could change in the future, perhaps even capriciously.  They can
   * only be used by the gzgetc() macro.  You have been warned.
   */
  struct gzFile_s {
      unsigned have;
      unsigned char *next;
      z_off64_t pos;
  };
  ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
  #ifdef Z_PREFIX_SET
  #  undef z_gzgetc
  #  define z_gzgetc(g) \
            ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
  #else
  #  define gzgetc(g) \
            ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
  #endif
  
  /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
   * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
   * both are true, the application gets the *64 functions, and the regular
   * functions are changed to 64 bits) -- in case these are set on systems
   * without large file support, _LFS64_LARGEFILE must also be true
   */
  #ifdef Z_LARGE64
     ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
     ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
     ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
     ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
     ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
     ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
  #endif
  
  #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
  #  ifdef Z_PREFIX_SET
  #    define z_gzopen z_gzopen64
  #    define z_gzseek z_gzseek64
  #    define z_gztell z_gztell64
  #    define z_gzoffset z_gzoffset64
  #    define z_adler32_combine z_adler32_combine64
  #    define z_crc32_combine z_crc32_combine64
  #    define z_crc32_combine_gen z_crc32_combine_gen64
  #  else
  #    define gzopen gzopen64
  #    define gzseek gzseek64
  #    define gztell gztell64
  #    define gzoffset gzoffset64
  #    define adler32_combine adler32_combine64
  #    define crc32_combine crc32_combine64
  #    define crc32_combine_gen crc32_combine_gen64
  #  endif
  #  ifndef Z_LARGE64
       ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
       ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
       ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
       ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
       ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
       ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
  #  endif
  #else
     ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
     ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
     ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
     ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
     ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t));
  #endif
  
  #else /* Z_SOLO */
  
     ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine_gen OF((z_off_t));
  
  #endif /* !Z_SOLO */
  
  /* undocumented functions */
  ZEXTERN const char   * ZEXPORT zError           OF((int));
  ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
  ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
  ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
  ZEXTERN int            ZEXPORT inflateValidate OF((z_streamp, int));
  ZEXTERN unsigned long  ZEXPORT inflateCodesUsed OF ((z_streamp));
  ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
  ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
  #if defined(_WIN32) && !defined(Z_SOLO)
  ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
                                              const char *mode));
  #endif
  #if defined(STDC) || defined(Z_HAVE_STDARG_H)
  #  ifndef Z_SOLO
  ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
                                                    const char *format,
                                                    va_list va));
  #  endif
  #endif
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* ZLIB_H */

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