vx32

zlib.h (66188B)

---

 /* zlib.h -- interface of the 'zlib' general purpose compression library
   version 1.2.3, July 18th, 2005
 
   Copyright (C) 1995-2005 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://www.ietf.org/rfc/rfc1950.txt
   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
 */
 
 #ifndef ZLIB_H
 #define ZLIB_H
 
 #include "zconf.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #define ZLIB_VERSION "1.2.3"
 #define ZLIB_VERNUM 0x1230
 
 /*
      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 (for example if an input file is mmap'ed), 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 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 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 {
     Bytef    *next_in;  /* next input byte */
     uInt     avail_in;  /* number of bytes available at next_in */
     uLong    total_in;  /* total nb of input bytes read so far */
 
     Bytef    *next_out; /* next output byte should be put there */
     uInt     avail_out; /* remaining free space at next_out */
     uLong    total_out; /* total nb of bytes output so far */
 
     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 */
     uLong   adler;      /* adler32 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.
 
    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 in 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 /* will be removed, use Z_SYNC_FLUSH instead */
 #define Z_SYNC_FLUSH    2
 #define Z_FULL_FLUSH    3
 #define Z_FINISH        4
 #define Z_BLOCK         5
 /* 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 (though see inflate()) */
 
 #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,
    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().
 
   - Provide 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 (in interactive applications).
     Some output may be provided even if flush is not set.
 
   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.
 
     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
   decide how much data to accumualte 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.
 
     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, 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 immediately after deflateInit if all the compression
   is to be done in a single step. In this case, avail_out must be at least
   the value returned by deflateBound (see below). If deflate does not return
   Z_STREAM_END, then it must be called again as described above.
 
     deflate() sets strm->adler to the adler32 checksum of all input read
   so far (that is, total_in bytes).
 
     deflate() may update strm->data_type if it can make a good guess about
   the input data type (Z_BINARY or Z_TEXT). 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 NULL), 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. If next_in is not Z_NULL and avail_in is large enough (the exact
    value depends on the compression method), inflateInit determines the
    compression method from the zlib header and allocates all data structures
    accordingly; otherwise the allocation will be deferred to the first call of
    inflate.  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.  msg is set to null if there is no error
    message. inflateInit does not perform any decompression apart from reading
    the zlib header if present: this will be done by inflate().  (So next_in and
    avail_in may be modified, but next_out and avail_out are unchanged.)
 */
 
 
 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), next_in is updated and processing
     will resume at this point for the next call of inflate().
 
   - Provide 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.
   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, or Z_BLOCK. 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.
   Also to assist in this, on return inflate() will set 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.
 
     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 the
   uncompressed data. (The size of the uncompressed data may have been saved
   by the compressor for this purpose.) The next operation on this stream must
   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
   is never required, but can be used to inform inflate that a faster approach
   may be used for the single inflate() call.
 
      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 only effect of the flush parameter in this implementation
   is on the return value of inflate(), as noted below, or when it returns early
   because Z_BLOCK is used.
 
      If a preset dictionary is needed after this call (see inflateSetDictionary
   below), inflate sets strm->adler to the adler32 checksum of the dictionary
   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
   strm->adler to the adler32 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 adler32
   checksum is equal to that saved by the compressor and returns Z_STREAM_END
   only if the checksum is correct.
 
     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
   deflate data.  The header type is detected automatically.  Any information
   contained in the gzip header is not retained, so applications that need that
   information should instead use raw inflate, see inflateInit2() below, or
   inflateBack() and perform their own processing of the gzip header and
   trailer.
 
     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), Z_STREAM_ERROR if the stream structure was inconsistent (for example
   if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
   Z_BUF_ERROR if no progress is 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 desired.
 */
 
 
 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, Z_STREAM_ERROR if the stream state
    was inconsistent. In the error case, msg may be set but then points to a
    static string (which must not be deallocated).
 */
 
                         /* 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 next_in, 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.
 
      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 an adler32 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 255 (unknown).  If a
    gzip stream is being written, strm->adler is a crc32 instead of an adler32.
 
      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 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 a parameter is invalid (such as an invalid
    method). 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. This function must be called
    immediately after deflateInit, deflateInit2 or deflateReset, before any
    call of deflate. 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 in
    deflate or deflate2. 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 adler32 value
    of the dictionary; the decompressor may later use this value to determine
    which dictionary has been used by the compressor. (The adler32 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
    adler32 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 (such as NULL dictionary) or the stream state is
    inconsistent (for example if deflate has already been called for this stream
    or if the compression method is bsort). deflateSetDictionary does not
    perform any compression: this will be done by deflate().
 */
 
 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 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 all the internal compression state.
    The stream will keep the same compression level and any other attributes
    that may have been set by deflateInit2.
 
       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
    stream state was inconsistent (such as zalloc or state being 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 level is changed, the input available so far
    is compressed with the old level (and may be flushed); the new level will
    take effect only at the next call of deflate().
 
      Before the call of deflateParams, the stream state must be set as for
    a call of deflate(), since the currently available input may have to
    be compressed and flushed. In particular, strm->avail_out must be non-zero.
 
      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
    if strm->avail_out was zero.
 */
 
 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().  This would be used to allocate an output buffer
    for deflation in a single pass, and so would be called before deflate().
 */
 
 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, 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 -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 adler32 or a crc32 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 crc32 instead of an adler32.
 
      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
    memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
    is set to null if there is no error message.  inflateInit2 does not perform
    any decompression apart from reading the zlib header if present: this will
    be done by inflate(). (So next_in and avail_in may be modified, but next_out
    and avail_out are unchanged.)
 */
 
 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 adler32 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
    immediately after inflateInit2() or inflateReset() and before any call of
    inflate() to set the dictionary.  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 (such as NULL dictionary) or the stream state is
    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
    expected one (incorrect adler32 value). inflateSetDictionary does not
    perform any decompression: this will be done by subsequent calls of
    inflate().
 */
 
 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
 /*
     Skips invalid compressed data until a full flush point (see above the
   description of deflate with Z_FULL_FLUSH) can be found, or until all
   available input is skipped. No output is provided.
 
     inflateSync returns Z_OK if a 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 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 all 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 NULL).
 */
 
 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.
 
       inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the 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 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 paramaters 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 *, 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 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.  This
    function 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
    normal behavior of inflate(), which expects either a zlib or gzip 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 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: 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)
  */
 
 
                         /* 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 easily 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 buffer.
      This function can be used to compress a whole file at once if the
    input file is mmap'ed.
      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 buffer.
 
      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 compressed buffer.
      This function can be used to decompress a whole file at once if the
    input file is mmap'ed.
 
      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.
 */
 
 
 typedef voidp gzFile;
 
 ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
 /*
      Opens a gzip (.gz) file for reading or 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", or 'R' for run-length encoding
    as in "wb1R". (See the description of deflateInit2 for more information
    about the strategy parameter.)
 
      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.
 
      gzopen returns NULL if the file could not be opened or if there was
    insufficient memory to allocate the (de)compression state; errno
    can be checked to distinguish the two cases (if errno is zero, the
    zlib error is Z_MEM_ERROR).  */
 
 ZEXTERN gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
 /*
      gzdopen() associates a gzFile with the file descriptor fd.  File
    descriptors are obtained from calls like open, dup, creat, pipe or
    fileno (in 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 gzdopen(dup(fd), mode).
      gzdopen returns NULL if there was insufficient memory to allocate
    the (de)compression state.
 */
 
 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
 /*
      Dynamically update the compression level or strategy. See the description
    of deflateInit2 for the meaning of these parameters.
      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
    opened for writing.
 */
 
 ZEXTERN int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
 /*
      Reads the given number of uncompressed bytes from the compressed file.
    If the input file was not in gzip format, gzread copies the given number
    of bytes into the buffer.
      gzread returns the number of uncompressed bytes actually read (0 for
    end of file, -1 for error). */
 
 ZEXTERN int ZEXPORT    gzwrite OF((gzFile file,
                                    voidpc buf, unsigned len));
 /*
      Writes the given number of uncompressed bytes into the compressed file.
    gzwrite returns the number of uncompressed bytes actually written
    (0 in case of error).
 */
 
 ZEXTERN int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
 /*
      Converts, formats, and writes the args to the compressed file under
    control of the format string, as in fprintf. gzprintf returns the number of
    uncompressed bytes actually written (0 in case of error).  The number of
    uncompressed bytes written is limited to 4095. The caller should assure that
    this limit is not exceeded. If it is exceeded, then gzprintf() will return
    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.
 */
 
 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
 /*
       Writes the given null-terminated string to the compressed 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));
 /*
       Reads bytes from the compressed file until len-1 characters are read, or
    a newline character is read and transferred to buf, or an end-of-file
    condition is encountered.  The string is then terminated with a null
    character.
       gzgets returns buf, or Z_NULL in case of error.
 */
 
 ZEXTERN int ZEXPORT    gzputc OF((gzFile file, int c));
 /*
       Writes c, converted to an unsigned char, into the compressed file.
    gzputc returns the value that was written, or -1 in case of error.
 */
 
 ZEXTERN int ZEXPORT    gzgetc OF((gzFile file));
 /*
       Reads one byte from the compressed file. gzgetc returns this byte
    or -1 in case of end of file or error.
 */
 
 ZEXTERN int ZEXPORT    gzungetc OF((int c, gzFile file));
 /*
       Push one character back onto the stream to be read again later.
    Only one character of push-back is allowed.  gzungetc() returns the
    character pushed, or -1 on failure.  gzungetc() will fail if a
    character has been pushed but not read yet, or if c is -1. The pushed
    character will be discarded if the stream is repositioned with gzseek()
    or gzrewind().
 */
 
 ZEXTERN int ZEXPORT    gzflush OF((gzFile file, int flush));
 /*
      Flushes all pending output into the compressed file. The parameter
    flush is as in the deflate() function. The return value is the zlib
    error number (see function gzerror below). gzflush returns Z_OK if
    the flush parameter is Z_FINISH and all output could be flushed.
      gzflush should be called only when strictly necessary because it can
    degrade compression.
 */
 
 ZEXTERN z_off_t ZEXPORT    gzseek OF((gzFile file,
                                       z_off_t offset, int whence));
 /*
       Sets the starting position for the next gzread or gzwrite on the
    given compressed 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));
 /*
      Rewinds the given 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));
 /*
      Returns the starting position for the next gzread or gzwrite on the
    given compressed file. This position represents a number of bytes in the
    uncompressed data stream.
 
    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
 */
 
 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
 /*
      Returns 1 when EOF has previously been detected reading the given
    input stream, otherwise zero.
 */
 
 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
 /*
      Returns 1 if file is being read directly without decompression, otherwise
    zero.
 */
 
 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
 /*
      Flushes all pending output if necessary, closes the compressed file
    and deallocates all the (de)compression state. The return value is the zlib
    error number (see function gzerror below).
 */
 
 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
 /*
      Returns the error message for the last error which occurred on the
    given compressed 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.
 */
 
 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
 /*
      Clears 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.
 */
 
                         /* 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. If buf is NULL, this function returns
    the required initial value for the checksum.
    An Adler-32 checksum is almost as reliable as a CRC32 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_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.
 */
 
 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. If buf is NULL, this function returns the required initial
    value for the 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_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.
 */
 
 
                         /* 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));
 #define deflateInit(strm, level) \
         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
 #define inflateInit(strm) \
         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
 #define inflateInit2(strm, windowBits) \
         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
 #define inflateBackInit(strm, windowBits, window) \
         inflateBackInit_((strm), (windowBits), (window), \
         ZLIB_VERSION, sizeof(z_stream))
 
 
 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
     struct internal_state {int dummy;}; /* hack for buggy compilers */
 #endif
 
 ZEXTERN const char   * ZEXPORT zError           OF((int));
 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp z));
 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* ZLIB_H */