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  1. /* zlib.h -- interface of the 'zlib' general purpose compression library
  2.   version 1.2.8, April 28th, 2013
  3.  
  4.   Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
  5.  
  6.   This software is provided 'as-is', without any express or implied
  7.   warranty.  In no event will the authors be held liable for any damages
  8.   arising from the use of this software.
  9.  
  10.   Permission is granted to anyone to use this software for any purpose,
  11.   including commercial applications, and to alter it and redistribute it
  12.   freely, subject to the following restrictions:
  13.  
  14.   1. The origin of this software must not be misrepresented; you must not
  15.      claim that you wrote the original software. If you use this software
  16.      in a product, an acknowledgment in the product documentation would be
  17.      appreciated but is not required.
  18.   2. Altered source versions must be plainly marked as such, and must not be
  19.      misrepresented as being the original software.
  20.   3. This notice may not be removed or altered from any source distribution.
  21.  
  22.   Jean-loup Gailly        Mark Adler
  23.   jloup@gzip.org          madler@alumni.caltech.edu
  24.  
  25.  
  26.   The data format used by the zlib library is described by RFCs (Request for
  27.   Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
  28.   (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
  29. */
  30.  
  31. #ifndef ZLIB_H
  32. #define ZLIB_H
  33.  
  34. #include "zconf.h"
  35.  
  36. #ifdef __cplusplus
  37. extern "C" {
  38. #endif
  39.  
  40. #define ZLIB_VERSION "1.2.8"
  41. #define ZLIB_VERNUM 0x1280
  42. #define ZLIB_VER_MAJOR 1
  43. #define ZLIB_VER_MINOR 2
  44. #define ZLIB_VER_REVISION 8
  45. #define ZLIB_VER_SUBREVISION 0
  46.  
  47. /*
  48.     The 'zlib' compression library provides in-memory compression and
  49.   decompression functions, including integrity checks of the uncompressed data.
  50.   This version of the library supports only one compression method (deflation)
  51.   but other algorithms will be added later and will have the same stream
  52.   interface.
  53.  
  54.     Compression can be done in a single step if the buffers are large enough,
  55.   or can be done by repeated calls of the compression function.  In the latter
  56.   case, the application must provide more input and/or consume the output
  57.   (providing more output space) before each call.
  58.  
  59.     The compressed data format used by default by the in-memory functions is
  60.   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
  61.   around a deflate stream, which is itself documented in RFC 1951.
  62.  
  63.     The library also supports reading and writing files in gzip (.gz) format
  64.   with an interface similar to that of stdio using the functions that start
  65.   with "gz".  The gzip format is different from the zlib format.  gzip is a
  66.   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
  67.  
  68.     This library can optionally read and write gzip streams in memory as well.
  69.  
  70.     The zlib format was designed to be compact and fast for use in memory
  71.   and on communications channels.  The gzip format was designed for single-
  72.   file compression on file systems, has a larger header than zlib to maintain
  73.   directory information, and uses a different, slower check method than zlib.
  74.  
  75.     The library does not install any signal handler.  The decoder checks
  76.   the consistency of the compressed data, so the library should never crash
  77.   even in case of corrupted input.
  78. */
  79.  
  80. typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
  81. typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
  82.  
  83. struct internal_state;
  84.  
  85. typedef struct z_stream_s {
  86.     z_const Bytef *next_in;     /* next input byte */
  87.     uInt     avail_in;  /* number of bytes available at next_in */
  88.     uLong    total_in;  /* total number of input bytes read so far */
  89.  
  90.     Bytef    *next_out; /* next output byte should be put there */
  91.     uInt     avail_out; /* remaining free space at next_out */
  92.     uLong    total_out; /* total number of bytes output so far */
  93.  
  94.     z_const char *msg;  /* last error message, NULL if no error */
  95.     struct internal_state FAR *state; /* not visible by applications */
  96.  
  97.     alloc_func zalloc;  /* used to allocate the internal state */
  98.     free_func  zfree;   /* used to free the internal state */
  99.     voidpf     opaque;  /* private data object passed to zalloc and zfree */
  100.  
  101.     int     data_type;  /* best guess about the data type: binary or text */
  102.     uLong   adler;      /* adler32 value of the uncompressed data */
  103.     uLong   reserved;   /* reserved for future use */
  104. } z_stream;
  105.  
  106. typedef z_stream FAR *z_streamp;
  107.  
  108. /*
  109.      gzip header information passed to and from zlib routines.  See RFC 1952
  110.   for more details on the meanings of these fields.
  111. */
  112. typedef struct gz_header_s {
  113.     int     text;       /* true if compressed data believed to be text */
  114.     uLong   time;       /* modification time */
  115.     int     xflags;     /* extra flags (not used when writing a gzip file) */
  116.     int     os;         /* operating system */
  117.     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
  118.     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
  119.     uInt    extra_max;  /* space at extra (only when reading header) */
  120.     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
  121.     uInt    name_max;   /* space at name (only when reading header) */
  122.     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
  123.     uInt    comm_max;   /* space at comment (only when reading header) */
  124.     int     hcrc;       /* true if there was or will be a header crc */
  125.     int     done;       /* true when done reading gzip header (not used
  126.                            when writing a gzip file) */
  127. } gz_header;
  128.  
  129. typedef gz_header FAR *gz_headerp;
  130.  
  131. /*
  132.      The application must update next_in and avail_in when avail_in has dropped
  133.    to zero.  It must update next_out and avail_out when avail_out has dropped
  134.    to zero.  The application must initialize zalloc, zfree and opaque before
  135.    calling the init function.  All other fields are set by the compression
  136.    library and must not be updated by the application.
  137.  
  138.      The opaque value provided by the application will be passed as the first
  139.    parameter for calls of zalloc and zfree.  This can be useful for custom
  140.    memory management.  The compression library attaches no meaning to the
  141.    opaque value.
  142.  
  143.      zalloc must return Z_NULL if there is not enough memory for the object.
  144.    If zlib is used in a multi-threaded application, zalloc and zfree must be
  145.    thread safe.
  146.  
  147.      On 16-bit systems, the functions zalloc and zfree must be able to allocate
  148.    exactly 65536 bytes, but will not be required to allocate more than this if
  149.    the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
  150.    returned by zalloc for objects of exactly 65536 bytes *must* have their
  151.    offset normalized to zero.  The default allocation function provided by this
  152.    library ensures this (see zutil.c).  To reduce memory requirements and avoid
  153.    any allocation of 64K objects, at the expense of compression ratio, compile
  154.    the library with -DMAX_WBITS=14 (see zconf.h).
  155.  
  156.      The fields total_in and total_out can be used for statistics or progress
  157.    reports.  After compression, total_in holds the total size of the
  158.    uncompressed data and may be saved for use in the decompressor (particularly
  159.    if the decompressor wants to decompress everything in a single step).
  160. */
  161.  
  162.                         /* constants */
  163.  
  164. #define Z_NO_FLUSH      0
  165. #define Z_PARTIAL_FLUSH 1
  166. #define Z_SYNC_FLUSH    2
  167. #define Z_FULL_FLUSH    3
  168. #define Z_FINISH        4
  169. #define Z_BLOCK         5
  170. #define Z_TREES         6
  171. /* Allowed flush values; see deflate() and inflate() below for details */
  172.  
  173. #define Z_OK            0
  174. #define Z_STREAM_END    1
  175. #define Z_NEED_DICT     2
  176. #define Z_ERRNO        (-1)
  177. #define Z_STREAM_ERROR (-2)
  178. #define Z_DATA_ERROR   (-3)
  179. #define Z_MEM_ERROR    (-4)
  180. #define Z_BUF_ERROR    (-5)
  181. #define Z_VERSION_ERROR (-6)
  182. /* Return codes for the compression/decompression functions. Negative values
  183.  * are errors, positive values are used for special but normal events.
  184.  */
  185.  
  186. #define Z_NO_COMPRESSION         0
  187. #define Z_BEST_SPEED             1
  188. #define Z_BEST_COMPRESSION       9
  189. #define Z_DEFAULT_COMPRESSION  (-1)
  190. /* compression levels */
  191.  
  192. #define Z_FILTERED            1
  193. #define Z_HUFFMAN_ONLY        2
  194. #define Z_RLE                 3
  195. #define Z_FIXED               4
  196. #define Z_DEFAULT_STRATEGY    0
  197. /* compression strategy; see deflateInit2() below for details */
  198.  
  199. #define Z_BINARY   0
  200. #define Z_TEXT     1
  201. #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
  202. #define Z_UNKNOWN  2
  203. /* Possible values of the data_type field (though see inflate()) */
  204.  
  205. #define Z_DEFLATED   8
  206. /* The deflate compression method (the only one supported in this version) */
  207.  
  208. #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
  209.  
  210. #define zlib_version zlibVersion()
  211. /* for compatibility with versions < 1.0.2 */
  212.  
  213.  
  214.                         /* basic functions */
  215.  
  216. ZEXTERN const char * ZEXPORT zlibVersion OF((void));
  217. /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
  218.    If the first character differs, the library code actually used is not
  219.    compatible with the zlib.h header file used by the application.  This check
  220.    is automatically made by deflateInit and inflateInit.
  221.  */
  222.  
  223. /*
  224. ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
  225.  
  226.      Initializes the internal stream state for compression.  The fields
  227.    zalloc, zfree and opaque must be initialized before by the caller.  If
  228.    zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
  229.    allocation functions.
  230.  
  231.      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
  232.    1 gives best speed, 9 gives best compression, 0 gives no compression at all
  233.    (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
  234.    requests a default compromise between speed and compression (currently
  235.    equivalent to level 6).
  236.  
  237.      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  238.    memory, Z_STREAM_ERROR if level is not a valid compression level, or
  239.    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
  240.    with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
  241.    if there is no error message.  deflateInit does not perform any compression:
  242.    this will be done by deflate().
  243. */
  244.  
  245.  
  246. ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
  247. /*
  248.     deflate compresses as much data as possible, and stops when the input
  249.   buffer becomes empty or the output buffer becomes full.  It may introduce
  250.   some output latency (reading input without producing any output) except when
  251.   forced to flush.
  252.  
  253.     The detailed semantics are as follows.  deflate performs one or both of the
  254.   following actions:
  255.  
  256.   - Compress more input starting at next_in and update next_in and avail_in
  257.     accordingly.  If not all input can be processed (because there is not
  258.     enough room in the output buffer), next_in and avail_in are updated and
  259.     processing will resume at this point for the next call of deflate().
  260.  
  261.   - Provide more output starting at next_out and update next_out and avail_out
  262.     accordingly.  This action is forced if the parameter flush is non zero.
  263.     Forcing flush frequently degrades the compression ratio, so this parameter
  264.     should be set only when necessary (in interactive applications).  Some
  265.     output may be provided even if flush is not set.
  266.  
  267.     Before the call of deflate(), the application should ensure that at least
  268.   one of the actions is possible, by providing more input and/or consuming more
  269.   output, and updating avail_in or avail_out accordingly; avail_out should
  270.   never be zero before the call.  The application can consume the compressed
  271.   output when it wants, for example when the output buffer is full (avail_out
  272.   == 0), or after each call of deflate().  If deflate returns Z_OK and with
  273.   zero avail_out, it must be called again after making room in the output
  274.   buffer because there might be more output pending.
  275.  
  276.     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
  277.   decide how much data to accumulate before producing output, in order to
  278.   maximize compression.
  279.  
  280.     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
  281.   flushed to the output buffer and the output is aligned on a byte boundary, so
  282.   that the decompressor can get all input data available so far.  (In
  283.   particular avail_in is zero after the call if enough output space has been
  284.   provided before the call.) Flushing may degrade compression for some
  285.   compression algorithms and so it should be used only when necessary.  This
  286.   completes the current deflate block and follows it with an empty stored block
  287.   that is three bits plus filler bits to the next byte, followed by four bytes
  288.   (00 00 ff ff).
  289.  
  290.     If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
  291.   output buffer, but the output is not aligned to a byte boundary.  All of the
  292.   input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
  293.   This completes the current deflate block and follows it with an empty fixed
  294.   codes block that is 10 bits long.  This assures that enough bytes are output
  295.   in order for the decompressor to finish the block before the empty fixed code
  296.   block.
  297.  
  298.     If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
  299.   for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
  300.   seven bits of the current block are held to be written as the next byte after
  301.   the next deflate block is completed.  In this case, the decompressor may not
  302.   be provided enough bits at this point in order to complete decompression of
  303.   the data provided so far to the compressor.  It may need to wait for the next
  304.   block to be emitted.  This is for advanced applications that need to control
  305.   the emission of deflate blocks.
  306.  
  307.     If flush is set to Z_FULL_FLUSH, all output is flushed as with
  308.   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
  309.   restart from this point if previous compressed data has been damaged or if
  310.   random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
  311.   compression.
  312.  
  313.     If deflate returns with avail_out == 0, this function must be called again
  314.   with the same value of the flush parameter and more output space (updated
  315.   avail_out), until the flush is complete (deflate returns with non-zero
  316.   avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
  317.   avail_out is greater than six to avoid repeated flush markers due to
  318.   avail_out == 0 on return.
  319.  
  320.     If the parameter flush is set to Z_FINISH, pending input is processed,
  321.   pending output is flushed and deflate returns with Z_STREAM_END if there was
  322.   enough output space; if deflate returns with Z_OK, this function must be
  323.   called again with Z_FINISH and more output space (updated avail_out) but no
  324.   more input data, until it returns with Z_STREAM_END or an error.  After
  325.   deflate has returned Z_STREAM_END, the only possible operations on the stream
  326.   are deflateReset or deflateEnd.
  327.  
  328.     Z_FINISH can be used immediately after deflateInit if all the compression
  329.   is to be done in a single step.  In this case, avail_out must be at least the
  330.   value returned by deflateBound (see below).  Then deflate is guaranteed to
  331.   return Z_STREAM_END.  If not enough output space is provided, deflate will
  332.   not return Z_STREAM_END, and it must be called again as described above.
  333.  
  334.     deflate() sets strm->adler to the adler32 checksum of all input read
  335.   so far (that is, total_in bytes).
  336.  
  337.     deflate() may update strm->data_type if it can make a good guess about
  338.   the input data type (Z_BINARY or Z_TEXT).  In doubt, the data is considered
  339.   binary.  This field is only for information purposes and does not affect the
  340.   compression algorithm in any manner.
  341.  
  342.     deflate() returns Z_OK if some progress has been made (more input
  343.   processed or more output produced), Z_STREAM_END if all input has been
  344.   consumed and all output has been produced (only when flush is set to
  345.   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
  346.   if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
  347.   (for example avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not
  348.   fatal, and deflate() can be called again with more input and more output
  349.   space to continue compressing.
  350. */
  351.  
  352.  
  353. ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
  354. /*
  355.      All dynamically allocated data structures for this stream are freed.
  356.    This function discards any unprocessed input and does not flush any pending
  357.    output.
  358.  
  359.      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
  360.    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
  361.    prematurely (some input or output was discarded).  In the error case, msg
  362.    may be set but then points to a static string (which must not be
  363.    deallocated).
  364. */
  365.  
  366.  
  367. /*
  368. ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
  369.  
  370.      Initializes the internal stream state for decompression.  The fields
  371.    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
  372.    the caller.  If next_in is not Z_NULL and avail_in is large enough (the
  373.    exact value depends on the compression method), inflateInit determines the
  374.    compression method from the zlib header and allocates all data structures
  375.    accordingly; otherwise the allocation will be deferred to the first call of
  376.    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
  377.    use default allocation functions.
  378.  
  379.      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  380.    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  381.    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  382.    invalid, such as a null pointer to the structure.  msg is set to null if
  383.    there is no error message.  inflateInit does not perform any decompression
  384.    apart from possibly reading the zlib header if present: actual decompression
  385.    will be done by inflate().  (So next_in and avail_in may be modified, but
  386.    next_out and avail_out are unused and unchanged.) The current implementation
  387.    of inflateInit() does not process any header information -- that is deferred
  388.    until inflate() is called.
  389. */
  390.  
  391.  
  392. ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
  393. /*
  394.     inflate decompresses as much data as possible, and stops when the input
  395.   buffer becomes empty or the output buffer becomes full.  It may introduce
  396.   some output latency (reading input without producing any output) except when
  397.   forced to flush.
  398.  
  399.   The detailed semantics are as follows.  inflate performs one or both of the
  400.   following actions:
  401.  
  402.   - Decompress more input starting at next_in and update next_in and avail_in
  403.     accordingly.  If not all input can be processed (because there is not
  404.     enough room in the output buffer), next_in is updated and processing will
  405.     resume at this point for the next call of inflate().
  406.  
  407.   - Provide more output starting at next_out and update next_out and avail_out
  408.     accordingly.  inflate() provides as much output as possible, until there is
  409.     no more input data or no more space in the output buffer (see below about
  410.     the flush parameter).
  411.  
  412.     Before the call of inflate(), the application should ensure that at least
  413.   one of the actions is possible, by providing more input and/or consuming more
  414.   output, and updating the next_* and avail_* values accordingly.  The
  415.   application can consume the uncompressed output when it wants, for example
  416.   when the output buffer is full (avail_out == 0), or after each call of
  417.   inflate().  If inflate returns Z_OK and with zero avail_out, it must be
  418.   called again after making room in the output buffer because there might be
  419.   more output pending.
  420.  
  421.     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
  422.   Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
  423.   output as possible to the output buffer.  Z_BLOCK requests that inflate()
  424.   stop if and when it gets to the next deflate block boundary.  When decoding
  425.   the zlib or gzip format, this will cause inflate() to return immediately
  426.   after the header and before the first block.  When doing a raw inflate,
  427.   inflate() will go ahead and process the first block, and will return when it
  428.   gets to the end of that block, or when it runs out of data.
  429.  
  430.     The Z_BLOCK option assists in appending to or combining deflate streams.
  431.   Also to assist in this, on return inflate() will set strm->data_type to the
  432.   number of unused bits in the last byte taken from strm->next_in, plus 64 if
  433.   inflate() is currently decoding the last block in the deflate stream, plus
  434.   128 if inflate() returned immediately after decoding an end-of-block code or
  435.   decoding the complete header up to just before the first byte of the deflate
  436.   stream.  The end-of-block will not be indicated until all of the uncompressed
  437.   data from that block has been written to strm->next_out.  The number of
  438.   unused bits may in general be greater than seven, except when bit 7 of
  439.   data_type is set, in which case the number of unused bits will be less than
  440.   eight.  data_type is set as noted here every time inflate() returns for all
  441.   flush options, and so can be used to determine the amount of currently
  442.   consumed input in bits.
  443.  
  444.     The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
  445.   end of each deflate block header is reached, before any actual data in that
  446.   block is decoded.  This allows the caller to determine the length of the
  447.   deflate block header for later use in random access within a deflate block.
  448.   256 is added to the value of strm->data_type when inflate() returns
  449.   immediately after reaching the end of the deflate block header.
  450.  
  451.     inflate() should normally be called until it returns Z_STREAM_END or an
  452.   error.  However if all decompression is to be performed in a single step (a
  453.   single call of inflate), the parameter flush should be set to Z_FINISH.  In
  454.   this case all pending input is processed and all pending output is flushed;
  455.   avail_out must be large enough to hold all of the uncompressed data for the
  456.   operation to complete.  (The size of the uncompressed data may have been
  457.   saved by the compressor for this purpose.) The use of Z_FINISH is not
  458.   required to perform an inflation in one step.  However it may be used to
  459.   inform inflate that a faster approach can be used for the single inflate()
  460.   call.  Z_FINISH also informs inflate to not maintain a sliding window if the
  461.   stream completes, which reduces inflate's memory footprint.  If the stream
  462.   does not complete, either because not all of the stream is provided or not
  463.   enough output space is provided, then a sliding window will be allocated and
  464.   inflate() can be called again to continue the operation as if Z_NO_FLUSH had
  465.   been used.
  466.  
  467.      In this implementation, inflate() always flushes as much output as
  468.   possible to the output buffer, and always uses the faster approach on the
  469.   first call.  So the effects of the flush parameter in this implementation are
  470.   on the return value of inflate() as noted below, when inflate() returns early
  471.   when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
  472.   memory for a sliding window when Z_FINISH is used.
  473.  
  474.      If a preset dictionary is needed after this call (see inflateSetDictionary
  475.   below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
  476.   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
  477.   strm->adler to the Adler-32 checksum of all output produced so far (that is,
  478.   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
  479.   below.  At the end of the stream, inflate() checks that its computed adler32
  480.   checksum is equal to that saved by the compressor and returns Z_STREAM_END
  481.   only if the checksum is correct.
  482.  
  483.     inflate() can decompress and check either zlib-wrapped or gzip-wrapped
  484.   deflate data.  The header type is detected automatically, if requested when
  485.   initializing with inflateInit2().  Any information contained in the gzip
  486.   header is not retained, so applications that need that information should
  487.   instead use raw inflate, see inflateInit2() below, or inflateBack() and
  488.   perform their own processing of the gzip header and trailer.  When processing
  489.   gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
  490.   producted so far.  The CRC-32 is checked against the gzip trailer.
  491.  
  492.     inflate() returns Z_OK if some progress has been made (more input processed
  493.   or more output produced), Z_STREAM_END if the end of the compressed data has
  494.   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
  495.   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
  496.   corrupted (input stream not conforming to the zlib format or incorrect check
  497.   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
  498.   next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
  499.   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
  500.   output buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
  501.   inflate() can be called again with more input and more output space to
  502.   continue decompressing.  If Z_DATA_ERROR is returned, the application may
  503.   then call inflateSync() to look for a good compression block if a partial
  504.   recovery of the data is desired.
  505. */
  506.  
  507.  
  508. ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
  509. /*
  510.      All dynamically allocated data structures for this stream are freed.
  511.    This function discards any unprocessed input and does not flush any pending
  512.    output.
  513.  
  514.      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
  515.    was inconsistent.  In the error case, msg may be set but then points to a
  516.    static string (which must not be deallocated).
  517. */
  518.  
  519.  
  520.                         /* Advanced functions */
  521.  
  522. /*
  523.     The following functions are needed only in some special applications.
  524. */
  525.  
  526. /*
  527. ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
  528.                                      int  level,
  529.                                      int  method,
  530.                                      int  windowBits,
  531.                                      int  memLevel,
  532.                                      int  strategy));
  533.  
  534.      This is another version of deflateInit with more compression options.  The
  535.    fields next_in, zalloc, zfree and opaque must be initialized before by the
  536.    caller.
  537.  
  538.      The method parameter is the compression method.  It must be Z_DEFLATED in
  539.    this version of the library.
  540.  
  541.      The windowBits parameter is the base two logarithm of the window size
  542.    (the size of the history buffer).  It should be in the range 8..15 for this
  543.    version of the library.  Larger values of this parameter result in better
  544.    compression at the expense of memory usage.  The default value is 15 if
  545.    deflateInit is used instead.
  546.  
  547.      windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
  548.    determines the window size.  deflate() will then generate raw deflate data
  549.    with no zlib header or trailer, and will not compute an adler32 check value.
  550.  
  551.      windowBits can also be greater than 15 for optional gzip encoding.  Add
  552.    16 to windowBits to write a simple gzip header and trailer around the
  553.    compressed data instead of a zlib wrapper.  The gzip header will have no
  554.    file name, no extra data, no comment, no modification time (set to zero), no
  555.    header crc, and the operating system will be set to 255 (unknown).  If a
  556.    gzip stream is being written, strm->adler is a crc32 instead of an adler32.
  557.  
  558.      The memLevel parameter specifies how much memory should be allocated
  559.    for the internal compression state.  memLevel=1 uses minimum memory but is
  560.    slow and reduces compression ratio; memLevel=9 uses maximum memory for
  561.    optimal speed.  The default value is 8.  See zconf.h for total memory usage
  562.    as a function of windowBits and memLevel.
  563.  
  564.      The strategy parameter is used to tune the compression algorithm.  Use the
  565.    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
  566.    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
  567.    string match), or Z_RLE to limit match distances to one (run-length
  568.    encoding).  Filtered data consists mostly of small values with a somewhat
  569.    random distribution.  In this case, the compression algorithm is tuned to
  570.    compress them better.  The effect of Z_FILTERED is to force more Huffman
  571.    coding and less string matching; it is somewhat intermediate between
  572.    Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
  573.    fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
  574.    strategy parameter only affects the compression ratio but not the
  575.    correctness of the compressed output even if it is not set appropriately.
  576.    Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
  577.    decoder for special applications.
  578.  
  579.      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  580.    memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
  581.    method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
  582.    incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
  583.    set to null if there is no error message.  deflateInit2 does not perform any
  584.    compression: this will be done by deflate().
  585. */
  586.  
  587. ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
  588.                                              const Bytef *dictionary,
  589.                                              uInt  dictLength));
  590. /*
  591.      Initializes the compression dictionary from the given byte sequence
  592.    without producing any compressed output.  When using the zlib format, this
  593.    function must be called immediately after deflateInit, deflateInit2 or
  594.    deflateReset, and before any call of deflate.  When doing raw deflate, this
  595.    function must be called either before any call of deflate, or immediately
  596.    after the completion of a deflate block, i.e. after all input has been
  597.    consumed and all output has been delivered when using any of the flush
  598.    options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
  599.    compressor and decompressor must use exactly the same dictionary (see
  600.    inflateSetDictionary).
  601.  
  602.      The dictionary should consist of strings (byte sequences) that are likely
  603.    to be encountered later in the data to be compressed, with the most commonly
  604.    used strings preferably put towards the end of the dictionary.  Using a
  605.    dictionary is most useful when the data to be compressed is short and can be
  606.    predicted with good accuracy; the data can then be compressed better than
  607.    with the default empty dictionary.
  608.  
  609.      Depending on the size of the compression data structures selected by
  610.    deflateInit or deflateInit2, a part of the dictionary may in effect be
  611.    discarded, for example if the dictionary is larger than the window size
  612.    provided in deflateInit or deflateInit2.  Thus the strings most likely to be
  613.    useful should be put at the end of the dictionary, not at the front.  In
  614.    addition, the current implementation of deflate will use at most the window
  615.    size minus 262 bytes of the provided dictionary.
  616.  
  617.      Upon return of this function, strm->adler is set to the adler32 value
  618.    of the dictionary; the decompressor may later use this value to determine
  619.    which dictionary has been used by the compressor.  (The adler32 value
  620.    applies to the whole dictionary even if only a subset of the dictionary is
  621.    actually used by the compressor.) If a raw deflate was requested, then the
  622.    adler32 value is not computed and strm->adler is not set.
  623.  
  624.      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
  625.    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
  626.    inconsistent (for example if deflate has already been called for this stream
  627.    or if not at a block boundary for raw deflate).  deflateSetDictionary does
  628.    not perform any compression: this will be done by deflate().
  629. */
  630.  
  631. ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
  632.                                     z_streamp source));
  633. /*
  634.      Sets the destination stream as a complete copy of the source stream.
  635.  
  636.      This function can be useful when several compression strategies will be
  637.    tried, for example when there are several ways of pre-processing the input
  638.    data with a filter.  The streams that will be discarded should then be freed
  639.    by calling deflateEnd.  Note that deflateCopy duplicates the internal
  640.    compression state which can be quite large, so this strategy is slow and can
  641.    consume lots of memory.
  642.  
  643.      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  644.    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  645.    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
  646.    destination.
  647. */
  648.  
  649. ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
  650. /*
  651.      This function is equivalent to deflateEnd followed by deflateInit,
  652.    but does not free and reallocate all the internal compression state.  The
  653.    stream will keep the same compression level and any other attributes that
  654.    may have been set by deflateInit2.
  655.  
  656.      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  657.    stream state was inconsistent (such as zalloc or state being Z_NULL).
  658. */
  659.  
  660. ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
  661.                                       int level,
  662.                                       int strategy));
  663. /*
  664.      Dynamically update the compression level and compression strategy.  The
  665.    interpretation of level and strategy is as in deflateInit2.  This can be
  666.    used to switch between compression and straight copy of the input data, or
  667.    to switch to a different kind of input data requiring a different strategy.
  668.    If the compression level is changed, the input available so far is
  669.    compressed with the old level (and may be flushed); the new level will take
  670.    effect only at the next call of deflate().
  671.  
  672.      Before the call of deflateParams, the stream state must be set as for
  673.    a call of deflate(), since the currently available input may have to be
  674.    compressed and flushed.  In particular, strm->avail_out must be non-zero.
  675.  
  676.      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
  677.    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
  678.    strm->avail_out was zero.
  679. */
  680.  
  681. ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
  682.                                     int good_length,
  683.                                     int max_lazy,
  684.                                     int nice_length,
  685.                                     int max_chain));
  686. /*
  687.      Fine tune deflate's internal compression parameters.  This should only be
  688.    used by someone who understands the algorithm used by zlib's deflate for
  689.    searching for the best matching string, and even then only by the most
  690.    fanatic optimizer trying to squeeze out the last compressed bit for their
  691.    specific input data.  Read the deflate.c source code for the meaning of the
  692.    max_lazy, good_length, nice_length, and max_chain parameters.
  693.  
  694.      deflateTune() can be called after deflateInit() or deflateInit2(), and
  695.    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
  696.  */
  697.  
  698. ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
  699.                                        uLong sourceLen));
  700. /*
  701.      deflateBound() returns an upper bound on the compressed size after
  702.    deflation of sourceLen bytes.  It must be called after deflateInit() or
  703.    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
  704.    to allocate an output buffer for deflation in a single pass, and so would be
  705.    called before deflate().  If that first deflate() call is provided the
  706.    sourceLen input bytes, an output buffer allocated to the size returned by
  707.    deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
  708.    to return Z_STREAM_END.  Note that it is possible for the compressed size to
  709.    be larger than the value returned by deflateBound() if flush options other
  710.    than Z_FINISH or Z_NO_FLUSH are used.
  711. */
  712.  
  713. ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
  714.                                        unsigned *pending,
  715.                                        int *bits));
  716. /*
  717.      deflatePending() returns the number of bytes and bits of output that have
  718.    been generated, but not yet provided in the available output.  The bytes not
  719.    provided would be due to the available output space having being consumed.
  720.    The number of bits of output not provided are between 0 and 7, where they
  721.    await more bits to join them in order to fill out a full byte.  If pending
  722.    or bits are Z_NULL, then those values are not set.
  723.  
  724.      deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
  725.    stream state was inconsistent.
  726.  */
  727.  
  728. ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
  729.                                      int bits,
  730.                                      int value));
  731. /*
  732.      deflatePrime() inserts bits in the deflate output stream.  The intent
  733.    is that this function is used to start off the deflate output with the bits
  734.    leftover from a previous deflate stream when appending to it.  As such, this
  735.    function can only be used for raw deflate, and must be used before the first
  736.    deflate() call after a deflateInit2() or deflateReset().  bits must be less
  737.    than or equal to 16, and that many of the least significant bits of value
  738.    will be inserted in the output.
  739.  
  740.      deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
  741.    room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
  742.    source stream state was inconsistent.
  743. */
  744.  
  745. ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
  746.                                          gz_headerp head));
  747. /*
  748.      deflateSetHeader() provides gzip header information for when a gzip
  749.    stream is requested by deflateInit2().  deflateSetHeader() may be called
  750.    after deflateInit2() or deflateReset() and before the first call of
  751.    deflate().  The text, time, os, extra field, name, and comment information
  752.    in the provided gz_header structure are written to the gzip header (xflag is
  753.    ignored -- the extra flags are set according to the compression level).  The
  754.    caller must assure that, if not Z_NULL, name and comment are terminated with
  755.    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
  756.    available there.  If hcrc is true, a gzip header crc is included.  Note that
  757.    the current versions of the command-line version of gzip (up through version
  758.    1.3.x) do not support header crc's, and will report that it is a "multi-part
  759.    gzip file" and give up.
  760.  
  761.      If deflateSetHeader is not used, the default gzip header has text false,
  762.    the time set to zero, and os set to 255, with no extra, name, or comment
  763.    fields.  The gzip header is returned to the default state by deflateReset().
  764.  
  765.      deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
  766.    stream state was inconsistent.
  767. */
  768.  
  769. /*
  770. ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
  771.                                      int  windowBits));
  772.  
  773.      This is another version of inflateInit with an extra parameter.  The
  774.    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
  775.    before by the caller.
  776.  
  777.      The windowBits parameter is the base two logarithm of the maximum window
  778.    size (the size of the history buffer).  It should be in the range 8..15 for
  779.    this version of the library.  The default value is 15 if inflateInit is used
  780.    instead.  windowBits must be greater than or equal to the windowBits value
  781.    provided to deflateInit2() while compressing, or it must be equal to 15 if
  782.    deflateInit2() was not used.  If a compressed stream with a larger window
  783.    size is given as input, inflate() will return with the error code
  784.    Z_DATA_ERROR instead of trying to allocate a larger window.
  785.  
  786.      windowBits can also be zero to request that inflate use the window size in
  787.    the zlib header of the compressed stream.
  788.  
  789.      windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
  790.    determines the window size.  inflate() will then process raw deflate data,
  791.    not looking for a zlib or gzip header, not generating a check value, and not
  792.    looking for any check values for comparison at the end of the stream.  This
  793.    is for use with other formats that use the deflate compressed data format
  794.    such as zip.  Those formats provide their own check values.  If a custom
  795.    format is developed using the raw deflate format for compressed data, it is
  796.    recommended that a check value such as an adler32 or a crc32 be applied to
  797.    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
  798.    most applications, the zlib format should be used as is.  Note that comments
  799.    above on the use in deflateInit2() applies to the magnitude of windowBits.
  800.  
  801.      windowBits can also be greater than 15 for optional gzip decoding.  Add
  802.    32 to windowBits to enable zlib and gzip decoding with automatic header
  803.    detection, or add 16 to decode only the gzip format (the zlib format will
  804.    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
  805.    crc32 instead of an adler32.
  806.  
  807.      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  808.    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  809.    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  810.    invalid, such as a null pointer to the structure.  msg is set to null if
  811.    there is no error message.  inflateInit2 does not perform any decompression
  812.    apart from possibly reading the zlib header if present: actual decompression
  813.    will be done by inflate().  (So next_in and avail_in may be modified, but
  814.    next_out and avail_out are unused and unchanged.) The current implementation
  815.    of inflateInit2() does not process any header information -- that is
  816.    deferred until inflate() is called.
  817. */
  818.  
  819. ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
  820.                                              const Bytef *dictionary,
  821.                                              uInt  dictLength));
  822. /*
  823.      Initializes the decompression dictionary from the given uncompressed byte
  824.    sequence.  This function must be called immediately after a call of inflate,
  825.    if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
  826.    can be determined from the adler32 value returned by that call of inflate.
  827.    The compressor and decompressor must use exactly the same dictionary (see
  828.    deflateSetDictionary).  For raw inflate, this function can be called at any
  829.    time to set the dictionary.  If the provided dictionary is smaller than the
  830.    window and there is already data in the window, then the provided dictionary
  831.    will amend what's there.  The application must insure that the dictionary
  832.    that was used for compression is provided.
  833.  
  834.      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
  835.    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
  836.    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
  837.    expected one (incorrect adler32 value).  inflateSetDictionary does not
  838.    perform any decompression: this will be done by subsequent calls of
  839.    inflate().
  840. */
  841.  
  842. ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
  843.                                              Bytef *dictionary,
  844.                                              uInt  *dictLength));
  845. /*
  846.      Returns the sliding dictionary being maintained by inflate.  dictLength is
  847.    set to the number of bytes in the dictionary, and that many bytes are copied
  848.    to dictionary.  dictionary must have enough space, where 32768 bytes is
  849.    always enough.  If inflateGetDictionary() is called with dictionary equal to
  850.    Z_NULL, then only the dictionary length is returned, and nothing is copied.
  851.    Similary, if dictLength is Z_NULL, then it is not set.
  852.  
  853.      inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
  854.    stream state is inconsistent.
  855. */
  856.  
  857. ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
  858. /*
  859.      Skips invalid compressed data until a possible full flush point (see above
  860.    for the description of deflate with Z_FULL_FLUSH) can be found, or until all
  861.    available input is skipped.  No output is provided.
  862.  
  863.      inflateSync searches for a 00 00 FF FF pattern in the compressed data.
  864.    All full flush points have this pattern, but not all occurrences of this
  865.    pattern are full flush points.
  866.  
  867.      inflateSync returns Z_OK if a possible full flush point has been found,
  868.    Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
  869.    has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
  870.    In the success case, the application may save the current current value of
  871.    total_in which indicates where valid compressed data was found.  In the
  872.    error case, the application may repeatedly call inflateSync, providing more
  873.    input each time, until success or end of the input data.
  874. */
  875.  
  876. ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
  877.                                     z_streamp source));
  878. /*
  879.      Sets the destination stream as a complete copy of the source stream.
  880.  
  881.      This function can be useful when randomly accessing a large stream.  The
  882.    first pass through the stream can periodically record the inflate state,
  883.    allowing restarting inflate at those points when randomly accessing the
  884.    stream.
  885.  
  886.      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  887.    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  888.    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
  889.    destination.
  890. */
  891.  
  892. ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
  893. /*
  894.      This function is equivalent to inflateEnd followed by inflateInit,
  895.    but does not free and reallocate all the internal decompression state.  The
  896.    stream will keep attributes that may have been set by inflateInit2.
  897.  
  898.      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  899.    stream state was inconsistent (such as zalloc or state being Z_NULL).
  900. */
  901.  
  902. ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
  903.                                       int windowBits));
  904. /*
  905.      This function is the same as inflateReset, but it also permits changing
  906.    the wrap and window size requests.  The windowBits parameter is interpreted
  907.    the same as it is for inflateInit2.
  908.  
  909.      inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
  910.    stream state was inconsistent (such as zalloc or state being Z_NULL), or if
  911.    the windowBits parameter is invalid.
  912. */
  913.  
  914. ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
  915.                                      int bits,
  916.                                      int value));
  917. /*
  918.      This function inserts bits in the inflate input stream.  The intent is
  919.    that this function is used to start inflating at a bit position in the
  920.    middle of a byte.  The provided bits will be used before any bytes are used
  921.    from next_in.  This function should only be used with raw inflate, and
  922.    should be used before the first inflate() call after inflateInit2() or
  923.    inflateReset().  bits must be less than or equal to 16, and that many of the
  924.    least significant bits of value will be inserted in the input.
  925.  
  926.      If bits is negative, then the input stream bit buffer is emptied.  Then
  927.    inflatePrime() can be called again to put bits in the buffer.  This is used
  928.    to clear out bits leftover after feeding inflate a block description prior
  929.    to feeding inflate codes.
  930.  
  931.      inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
  932.    stream state was inconsistent.
  933. */
  934.  
  935. ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
  936. /*
  937.      This function returns two values, one in the lower 16 bits of the return
  938.    value, and the other in the remaining upper bits, obtained by shifting the
  939.    return value down 16 bits.  If the upper value is -1 and the lower value is
  940.    zero, then inflate() is currently decoding information outside of a block.
  941.    If the upper value is -1 and the lower value is non-zero, then inflate is in
  942.    the middle of a stored block, with the lower value equaling the number of
  943.    bytes from the input remaining to copy.  If the upper value is not -1, then
  944.    it is the number of bits back from the current bit position in the input of
  945.    the code (literal or length/distance pair) currently being processed.  In
  946.    that case the lower value is the number of bytes already emitted for that
  947.    code.
  948.  
  949.      A code is being processed if inflate is waiting for more input to complete
  950.    decoding of the code, or if it has completed decoding but is waiting for
  951.    more output space to write the literal or match data.
  952.  
  953.      inflateMark() is used to mark locations in the input data for random
  954.    access, which may be at bit positions, and to note those cases where the
  955.    output of a code may span boundaries of random access blocks.  The current
  956.    location in the input stream can be determined from avail_in and data_type
  957.    as noted in the description for the Z_BLOCK flush parameter for inflate.
  958.  
  959.      inflateMark returns the value noted above or -1 << 16 if the provided
  960.    source stream state was inconsistent.
  961. */
  962.  
  963. ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
  964.                                          gz_headerp head));
  965. /*
  966.      inflateGetHeader() requests that gzip header information be stored in the
  967.    provided gz_header structure.  inflateGetHeader() may be called after
  968.    inflateInit2() or inflateReset(), and before the first call of inflate().
  969.    As inflate() processes the gzip stream, head->done is zero until the header
  970.    is completed, at which time head->done is set to one.  If a zlib stream is
  971.    being decoded, then head->done is set to -1 to indicate that there will be
  972.    no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
  973.    used to force inflate() to return immediately after header processing is
  974.    complete and before any actual data is decompressed.
  975.  
  976.      The text, time, xflags, and os fields are filled in with the gzip header
  977.    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
  978.    was valid if done is set to one.) If extra is not Z_NULL, then extra_max
  979.    contains the maximum number of bytes to write to extra.  Once done is true,
  980.    extra_len contains the actual extra field length, and extra contains the
  981.    extra field, or that field truncated if extra_max is less than extra_len.
  982.    If name is not Z_NULL, then up to name_max characters are written there,
  983.    terminated with a zero unless the length is greater than name_max.  If
  984.    comment is not Z_NULL, then up to comm_max characters are written there,
  985.    terminated with a zero unless the length is greater than comm_max.  When any
  986.    of extra, name, or comment are not Z_NULL and the respective field is not
  987.    present in the header, then that field is set to Z_NULL to signal its
  988.    absence.  This allows the use of deflateSetHeader() with the returned
  989.    structure to duplicate the header.  However if those fields are set to
  990.    allocated memory, then the application will need to save those pointers
  991.    elsewhere so that they can be eventually freed.
  992.  
  993.      If inflateGetHeader is not used, then the header information is simply
  994.    discarded.  The header is always checked for validity, including the header
  995.    CRC if present.  inflateReset() will reset the process to discard the header
  996.    information.  The application would need to call inflateGetHeader() again to
  997.    retrieve the header from the next gzip stream.
  998.  
  999.      inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
  1000.    stream state was inconsistent.
  1001. */
  1002.  
  1003. /*
  1004. ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
  1005.                                         unsigned char FAR *window));
  1006.  
  1007.      Initialize the internal stream state for decompression using inflateBack()
  1008.    calls.  The fields zalloc, zfree and opaque in strm must be initialized
  1009.    before the call.  If zalloc and zfree are Z_NULL, then the default library-
  1010.    derived memory allocation routines are used.  windowBits is the base two
  1011.    logarithm of the window size, in the range 8..15.  window is a caller
  1012.    supplied buffer of that size.  Except for special applications where it is
  1013.    assured that deflate was used with small window sizes, windowBits must be 15
  1014.    and a 32K byte window must be supplied to be able to decompress general
  1015.    deflate streams.
  1016.  
  1017.      See inflateBack() for the usage of these routines.
  1018.  
  1019.      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
  1020.    the parameters are invalid, Z_MEM_ERROR if the internal state could not be
  1021.    allocated, or Z_VERSION_ERROR if the version of the library does not match
  1022.    the version of the header file.
  1023. */
  1024.  
  1025. typedef unsigned (*in_func) OF((void FAR *,
  1026.                                 z_const unsigned char FAR * FAR *));
  1027. typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
  1028.  
  1029. ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
  1030.                                     in_func in, void FAR *in_desc,
  1031.                                     out_func out, void FAR *out_desc));
  1032. /*
  1033.      inflateBack() does a raw inflate with a single call using a call-back
  1034.    interface for input and output.  This is potentially more efficient than
  1035.    inflate() for file i/o applications, in that it avoids copying between the
  1036.    output and the sliding window by simply making the window itself the output
  1037.    buffer.  inflate() can be faster on modern CPUs when used with large
  1038.    buffers.  inflateBack() trusts the application to not change the output
  1039.    buffer passed by the output function, at least until inflateBack() returns.
  1040.  
  1041.      inflateBackInit() must be called first to allocate the internal state
  1042.    and to initialize the state with the user-provided window buffer.
  1043.    inflateBack() may then be used multiple times to inflate a complete, raw
  1044.    deflate stream with each call.  inflateBackEnd() is then called to free the
  1045.    allocated state.
  1046.  
  1047.      A raw deflate stream is one with no zlib or gzip header or trailer.
  1048.    This routine would normally be used in a utility that reads zip or gzip
  1049.    files and writes out uncompressed files.  The utility would decode the
  1050.    header and process the trailer on its own, hence this routine expects only
  1051.    the raw deflate stream to decompress.  This is different from the normal
  1052.    behavior of inflate(), which expects either a zlib or gzip header and
  1053.    trailer around the deflate stream.
  1054.  
  1055.      inflateBack() uses two subroutines supplied by the caller that are then
  1056.    called by inflateBack() for input and output.  inflateBack() calls those
  1057.    routines until it reads a complete deflate stream and writes out all of the
  1058.    uncompressed data, or until it encounters an error.  The function's
  1059.    parameters and return types are defined above in the in_func and out_func
  1060.    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
  1061.    number of bytes of provided input, and a pointer to that input in buf.  If
  1062.    there is no input available, in() must return zero--buf is ignored in that
  1063.    case--and inflateBack() will return a buffer error.  inflateBack() will call
  1064.    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
  1065.    should return zero on success, or non-zero on failure.  If out() returns
  1066.    non-zero, inflateBack() will return with an error.  Neither in() nor out()
  1067.    are permitted to change the contents of the window provided to
  1068.    inflateBackInit(), which is also the buffer that out() uses to write from.
  1069.    The length written by out() will be at most the window size.  Any non-zero
  1070.    amount of input may be provided by in().
  1071.  
  1072.      For convenience, inflateBack() can be provided input on the first call by
  1073.    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
  1074.    in() will be called.  Therefore strm->next_in must be initialized before
  1075.    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
  1076.    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
  1077.    must also be initialized, and then if strm->avail_in is not zero, input will
  1078.    initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
  1079.  
  1080.      The in_desc and out_desc parameters of inflateBack() is passed as the
  1081.    first parameter of in() and out() respectively when they are called.  These
  1082.    descriptors can be optionally used to pass any information that the caller-
  1083.    supplied in() and out() functions need to do their job.
  1084.  
  1085.      On return, inflateBack() will set strm->next_in and strm->avail_in to
  1086.    pass back any unused input that was provided by the last in() call.  The
  1087.    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
  1088.    if in() or out() returned an error, Z_DATA_ERROR if there was a format error
  1089.    in the deflate stream (in which case strm->msg is set to indicate the nature
  1090.    of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
  1091.    In the case of Z_BUF_ERROR, an input or output error can be distinguished
  1092.    using strm->next_in which will be Z_NULL only if in() returned an error.  If
  1093.    strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
  1094.    non-zero.  (in() will always be called before out(), so strm->next_in is
  1095.    assured to be defined if out() returns non-zero.) Note that inflateBack()
  1096.    cannot return Z_OK.
  1097. */
  1098.  
  1099. ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
  1100. /*
  1101.      All memory allocated by inflateBackInit() is freed.
  1102.  
  1103.      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
  1104.    state was inconsistent.
  1105. */
  1106.  
  1107. ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
  1108. /* Return flags indicating compile-time options.
  1109.  
  1110.     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
  1111.      1.0: size of uInt
  1112.      3.2: size of uLong
  1113.      5.4: size of voidpf (pointer)
  1114.      7.6: size of z_off_t
  1115.  
  1116.     Compiler, assembler, and debug options:
  1117.      8: DEBUG
  1118.      9: ASMV or ASMINF -- use ASM code
  1119.      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
  1120.      11: 0 (reserved)
  1121.  
  1122.     One-time table building (smaller code, but not thread-safe if true):
  1123.      12: BUILDFIXED -- build static block decoding tables when needed
  1124.      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
  1125.      14,15: 0 (reserved)
  1126.  
  1127.     Library content (indicates missing functionality):
  1128.      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
  1129.                           deflate code when not needed)
  1130.      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
  1131.                     and decode gzip streams (to avoid linking crc code)
  1132.      18-19: 0 (reserved)
  1133.  
  1134.     Operation variations (changes in library functionality):
  1135.      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
  1136.      21: FASTEST -- deflate algorithm with only one, lowest compression level
  1137.      22,23: 0 (reserved)
  1138.  
  1139.     The sprintf variant used by gzprintf (zero is best):
  1140.      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
  1141.      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
  1142.      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
  1143.  
  1144.     Remainder:
  1145.      27-31: 0 (reserved)
  1146.  */
  1147.  
  1148. #ifndef Z_SOLO
  1149.  
  1150.                         /* utility functions */
  1151.  
  1152. /*
  1153.      The following utility functions are implemented on top of the basic
  1154.    stream-oriented functions.  To simplify the interface, some default options
  1155.    are assumed (compression level and memory usage, standard memory allocation
  1156.    functions).  The source code of these utility functions can be modified if
  1157.    you need special options.
  1158. */
  1159.  
  1160. ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
  1161.                                  const Bytef *source, uLong sourceLen));
  1162. /*
  1163.      Compresses the source buffer into the destination buffer.  sourceLen is
  1164.    the byte length of the source buffer.  Upon entry, destLen is the total size
  1165.    of the destination buffer, which must be at least the value returned by
  1166.    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
  1167.    compressed buffer.
  1168.  
  1169.      compress returns Z_OK if success, Z_MEM_ERROR if there was not
  1170.    enough memory, Z_BUF_ERROR if there was not enough room in the output
  1171.    buffer.
  1172. */
  1173.  
  1174. ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
  1175.                                   const Bytef *source, uLong sourceLen,
  1176.                                   int level));
  1177. /*
  1178.      Compresses the source buffer into the destination buffer.  The level
  1179.    parameter has the same meaning as in deflateInit.  sourceLen is the byte
  1180.    length of the source buffer.  Upon entry, destLen is the total size of the
  1181.    destination buffer, which must be at least the value returned by
  1182.    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
  1183.    compressed buffer.
  1184.  
  1185.      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  1186.    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
  1187.    Z_STREAM_ERROR if the level parameter is invalid.
  1188. */
  1189.  
  1190. ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
  1191. /*
  1192.      compressBound() returns an upper bound on the compressed size after
  1193.    compress() or compress2() on sourceLen bytes.  It would be used before a
  1194.    compress() or compress2() call to allocate the destination buffer.
  1195. */
  1196.  
  1197. ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
  1198.                                    const Bytef *source, uLong sourceLen));
  1199. /*
  1200.      Decompresses the source buffer into the destination buffer.  sourceLen is
  1201.    the byte length of the source buffer.  Upon entry, destLen is the total size
  1202.    of the destination buffer, which must be large enough to hold the entire
  1203.    uncompressed data.  (The size of the uncompressed data must have been saved
  1204.    previously by the compressor and transmitted to the decompressor by some
  1205.    mechanism outside the scope of this compression library.) Upon exit, destLen
  1206.    is the actual size of the uncompressed buffer.
  1207.  
  1208.      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
  1209.    enough memory, Z_BUF_ERROR if there was not enough room in the output
  1210.    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
  1211.    the case where there is not enough room, uncompress() will fill the output
  1212.    buffer with the uncompressed data up to that point.
  1213. */
  1214.  
  1215.                         /* gzip file access functions */
  1216.  
  1217. /*
  1218.      This library supports reading and writing files in gzip (.gz) format with
  1219.    an interface similar to that of stdio, using the functions that start with
  1220.    "gz".  The gzip format is different from the zlib format.  gzip is a gzip
  1221.    wrapper, documented in RFC 1952, wrapped around a deflate stream.
  1222. */
  1223.  
  1224. typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
  1225.  
  1226. /*
  1227. ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
  1228.  
  1229.      Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
  1230.    in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
  1231.    a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
  1232.    compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
  1233.    for fixed code compression as in "wb9F".  (See the description of
  1234.    deflateInit2 for more information about the strategy parameter.)  'T' will
  1235.    request transparent writing or appending with no compression and not using
  1236.    the gzip format.
  1237.  
  1238.      "a" can be used instead of "w" to request that the gzip stream that will
  1239.    be written be appended to the file.  "+" will result in an error, since
  1240.    reading and writing to the same gzip file is not supported.  The addition of
  1241.    "x" when writing will create the file exclusively, which fails if the file
  1242.    already exists.  On systems that support it, the addition of "e" when
  1243.    reading or writing will set the flag to close the file on an execve() call.
  1244.  
  1245.      These functions, as well as gzip, will read and decode a sequence of gzip
  1246.    streams in a file.  The append function of gzopen() can be used to create
  1247.    such a file.  (Also see gzflush() for another way to do this.)  When
  1248.    appending, gzopen does not test whether the file begins with a gzip stream,
  1249.    nor does it look for the end of the gzip streams to begin appending.  gzopen
  1250.    will simply append a gzip stream to the existing file.
  1251.  
  1252.      gzopen can be used to read a file which is not in gzip format; in this
  1253.    case gzread will directly read from the file without decompression.  When
  1254.    reading, this will be detected automatically by looking for the magic two-
  1255.    byte gzip header.
  1256.  
  1257.      gzopen returns NULL if the file could not be opened, if there was
  1258.    insufficient memory to allocate the gzFile state, or if an invalid mode was
  1259.    specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
  1260.    errno can be checked to determine if the reason gzopen failed was that the
  1261.    file could not be opened.
  1262. */
  1263.  
  1264. ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
  1265. /*
  1266.      gzdopen associates a gzFile with the file descriptor fd.  File descriptors
  1267.    are obtained from calls like open, dup, creat, pipe or fileno (if the file
  1268.    has been previously opened with fopen).  The mode parameter is as in gzopen.
  1269.  
  1270.      The next call of gzclose on the returned gzFile will also close the file
  1271.    descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
  1272.    fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
  1273.    mode);.  The duplicated descriptor should be saved to avoid a leak, since
  1274.    gzdopen does not close fd if it fails.  If you are using fileno() to get the
  1275.    file descriptor from a FILE *, then you will have to use dup() to avoid
  1276.    double-close()ing the file descriptor.  Both gzclose() and fclose() will
  1277.    close the associated file descriptor, so they need to have different file
  1278.    descriptors.
  1279.  
  1280.      gzdopen returns NULL if there was insufficient memory to allocate the
  1281.    gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
  1282.    provided, or '+' was provided), or if fd is -1.  The file descriptor is not
  1283.    used until the next gz* read, write, seek, or close operation, so gzdopen
  1284.    will not detect if fd is invalid (unless fd is -1).
  1285. */
  1286.  
  1287. ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
  1288. /*
  1289.      Set the internal buffer size used by this library's functions.  The
  1290.    default buffer size is 8192 bytes.  This function must be called after
  1291.    gzopen() or gzdopen(), and before any other calls that read or write the
  1292.    file.  The buffer memory allocation is always deferred to the first read or
  1293.    write.  Two buffers are allocated, either both of the specified size when
  1294.    writing, or one of the specified size and the other twice that size when
  1295.    reading.  A larger buffer size of, for example, 64K or 128K bytes will
  1296.    noticeably increase the speed of decompression (reading).
  1297.  
  1298.      The new buffer size also affects the maximum length for gzprintf().
  1299.  
  1300.      gzbuffer() returns 0 on success, or -1 on failure, such as being called
  1301.    too late.
  1302. */
  1303.  
  1304. ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
  1305. /*
  1306.      Dynamically update the compression level or strategy.  See the description
  1307.    of deflateInit2 for the meaning of these parameters.
  1308.  
  1309.      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
  1310.    opened for writing.
  1311. */
  1312.  
  1313. ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
  1314. /*
  1315.      Reads the given number of uncompressed bytes from the compressed file.  If
  1316.    the input file is not in gzip format, gzread copies the given number of
  1317.    bytes into the buffer directly from the file.
  1318.  
  1319.      After reaching the end of a gzip stream in the input, gzread will continue
  1320.    to read, looking for another gzip stream.  Any number of gzip streams may be
  1321.    concatenated in the input file, and will all be decompressed by gzread().
  1322.    If something other than a gzip stream is encountered after a gzip stream,
  1323.    that remaining trailing garbage is ignored (and no error is returned).
  1324.  
  1325.      gzread can be used to read a gzip file that is being concurrently written.
  1326.    Upon reaching the end of the input, gzread will return with the available
  1327.    data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
  1328.    gzclearerr can be used to clear the end of file indicator in order to permit
  1329.    gzread to be tried again.  Z_OK indicates that a gzip stream was completed
  1330.    on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
  1331.    middle of a gzip stream.  Note that gzread does not return -1 in the event
  1332.    of an incomplete gzip stream.  This error is deferred until gzclose(), which
  1333.    will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
  1334.    stream.  Alternatively, gzerror can be used before gzclose to detect this
  1335.    case.
  1336.  
  1337.      gzread returns the number of uncompressed bytes actually read, less than
  1338.    len for end of file, or -1 for error.
  1339. */
  1340.  
  1341. ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
  1342.                                 voidpc buf, unsigned len));
  1343. /*
  1344.      Writes the given number of uncompressed bytes into the compressed file.
  1345.    gzwrite returns the number of uncompressed bytes written or 0 in case of
  1346.    error.
  1347. */
  1348.  
  1349. ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
  1350. /*
  1351.      Converts, formats, and writes the arguments to the compressed file under
  1352.    control of the format string, as in fprintf.  gzprintf returns the number of
  1353.    uncompressed bytes actually written, or 0 in case of error.  The number of
  1354.    uncompressed bytes written is limited to 8191, or one less than the buffer
  1355.    size given to gzbuffer().  The caller should assure that this limit is not
  1356.    exceeded.  If it is exceeded, then gzprintf() will return an error (0) with
  1357.    nothing written.  In this case, there may also be a buffer overflow with
  1358.    unpredictable consequences, which is possible only if zlib was compiled with
  1359.    the insecure functions sprintf() or vsprintf() because the secure snprintf()
  1360.    or vsnprintf() functions were not available.  This can be determined using
  1361.    zlibCompileFlags().
  1362. */
  1363.  
  1364. ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
  1365. /*
  1366.      Writes the given null-terminated string to the compressed file, excluding
  1367.    the terminating null character.
  1368.  
  1369.      gzputs returns the number of characters written, or -1 in case of error.
  1370. */
  1371.  
  1372. ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
  1373. /*
  1374.      Reads bytes from the compressed file until len-1 characters are read, or a
  1375.    newline character is read and transferred to buf, or an end-of-file
  1376.    condition is encountered.  If any characters are read or if len == 1, the
  1377.    string is terminated with a null character.  If no characters are read due
  1378.    to an end-of-file or len < 1, then the buffer is left untouched.
  1379.  
  1380.      gzgets returns buf which is a null-terminated string, or it returns NULL
  1381.    for end-of-file or in case of error.  If there was an error, the contents at
  1382.    buf are indeterminate.
  1383. */
  1384.  
  1385. ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
  1386. /*
  1387.      Writes c, converted to an unsigned char, into the compressed file.  gzputc
  1388.    returns the value that was written, or -1 in case of error.
  1389. */
  1390.  
  1391. ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
  1392. /*
  1393.      Reads one byte from the compressed file.  gzgetc returns this byte or -1
  1394.    in case of end of file or error.  This is implemented as a macro for speed.
  1395.    As such, it does not do all of the checking the other functions do.  I.e.
  1396.    it does not check to see if file is NULL, nor whether the structure file
  1397.    points to has been clobbered or not.
  1398. */
  1399.  
  1400. ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
  1401. /*
  1402.      Push one character back onto the stream to be read as the first character
  1403.    on the next read.  At least one character of push-back is allowed.
  1404.    gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
  1405.    fail if c is -1, and may fail if a character has been pushed but not read
  1406.    yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
  1407.    output buffer size of pushed characters is allowed.  (See gzbuffer above.)
  1408.    The pushed character will be discarded if the stream is repositioned with
  1409.    gzseek() or gzrewind().
  1410. */
  1411.  
  1412. ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
  1413. /*
  1414.      Flushes all pending output into the compressed file.  The parameter flush
  1415.    is as in the deflate() function.  The return value is the zlib error number
  1416.    (see function gzerror below).  gzflush is only permitted when writing.
  1417.  
  1418.      If the flush parameter is Z_FINISH, the remaining data is written and the
  1419.    gzip stream is completed in the output.  If gzwrite() is called again, a new
  1420.    gzip stream will be started in the output.  gzread() is able to read such
  1421.    concatented gzip streams.
  1422.  
  1423.      gzflush should be called only when strictly necessary because it will
  1424.    degrade compression if called too often.
  1425. */
  1426.  
  1427. /*
  1428. ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
  1429.                                    z_off_t offset, int whence));
  1430.  
  1431.      Sets the starting position for the next gzread or gzwrite on the given
  1432.    compressed file.  The offset represents a number of bytes in the
  1433.    uncompressed data stream.  The whence parameter is defined as in lseek(2);
  1434.    the value SEEK_END is not supported.
  1435.  
  1436.      If the file is opened for reading, this function is emulated but can be
  1437.    extremely slow.  If the file is opened for writing, only forward seeks are
  1438.    supported; gzseek then compresses a sequence of zeroes up to the new
  1439.    starting position.
  1440.  
  1441.      gzseek returns the resulting offset location as measured in bytes from
  1442.    the beginning of the uncompressed stream, or -1 in case of error, in
  1443.    particular if the file is opened for writing and the new starting position
  1444.    would be before the current position.
  1445. */
  1446.  
  1447. ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
  1448. /*
  1449.      Rewinds the given file. This function is supported only for reading.
  1450.  
  1451.      gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
  1452. */
  1453.  
  1454. /*
  1455. ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
  1456.  
  1457.      Returns the starting position for the next gzread or gzwrite on the given
  1458.    compressed file.  This position represents a number of bytes in the
  1459.    uncompressed data stream, and is zero when starting, even if appending or
  1460.    reading a gzip stream from the middle of a file using gzdopen().
  1461.  
  1462.      gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
  1463. */
  1464.  
  1465. /*
  1466. ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
  1467.  
  1468.      Returns the current offset in the file being read or written.  This offset
  1469.    includes the count of bytes that precede the gzip stream, for example when
  1470.    appending or when using gzdopen() for reading.  When reading, the offset
  1471.    does not include as yet unused buffered input.  This information can be used
  1472.    for a progress indicator.  On error, gzoffset() returns -1.
  1473. */
  1474.  
  1475. ZEXTERN int ZEXPORT gzeof OF((gzFile file));
  1476. /*
  1477.      Returns true (1) if the end-of-file indicator has been set while reading,
  1478.    false (0) otherwise.  Note that the end-of-file indicator is set only if the
  1479.    read tried to go past the end of the input, but came up short.  Therefore,
  1480.    just like feof(), gzeof() may return false even if there is no more data to
  1481.    read, in the event that the last read request was for the exact number of
  1482.    bytes remaining in the input file.  This will happen if the input file size
  1483.    is an exact multiple of the buffer size.
  1484.  
  1485.      If gzeof() returns true, then the read functions will return no more data,
  1486.    unless the end-of-file indicator is reset by gzclearerr() and the input file
  1487.    has grown since the previous end of file was detected.
  1488. */
  1489.  
  1490. ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
  1491. /*
  1492.      Returns true (1) if file is being copied directly while reading, or false
  1493.    (0) if file is a gzip stream being decompressed.
  1494.  
  1495.      If the input file is empty, gzdirect() will return true, since the input
  1496.    does not contain a gzip stream.
  1497.  
  1498.      If gzdirect() is used immediately after gzopen() or gzdopen() it will
  1499.    cause buffers to be allocated to allow reading the file to determine if it
  1500.    is a gzip file.  Therefore if gzbuffer() is used, it should be called before
  1501.    gzdirect().
  1502.  
  1503.      When writing, gzdirect() returns true (1) if transparent writing was
  1504.    requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
  1505.    gzdirect() is not needed when writing.  Transparent writing must be
  1506.    explicitly requested, so the application already knows the answer.  When
  1507.    linking statically, using gzdirect() will include all of the zlib code for
  1508.    gzip file reading and decompression, which may not be desired.)
  1509. */
  1510.  
  1511. ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
  1512. /*
  1513.      Flushes all pending output if necessary, closes the compressed file and
  1514.    deallocates the (de)compression state.  Note that once file is closed, you
  1515.    cannot call gzerror with file, since its structures have been deallocated.
  1516.    gzclose must not be called more than once on the same file, just as free
  1517.    must not be called more than once on the same allocation.
  1518.  
  1519.      gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
  1520.    file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
  1521.    last read ended in the middle of a gzip stream, or Z_OK on success.
  1522. */
  1523.  
  1524. ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
  1525. ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
  1526. /*
  1527.      Same as gzclose(), but gzclose_r() is only for use when reading, and
  1528.    gzclose_w() is only for use when writing or appending.  The advantage to
  1529.    using these instead of gzclose() is that they avoid linking in zlib
  1530.    compression or decompression code that is not used when only reading or only
  1531.    writing respectively.  If gzclose() is used, then both compression and
  1532.    decompression code will be included the application when linking to a static
  1533.    zlib library.
  1534. */
  1535.  
  1536. ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
  1537. /*
  1538.      Returns the error message for the last error which occurred on the given
  1539.    compressed file.  errnum is set to zlib error number.  If an error occurred
  1540.    in the file system and not in the compression library, errnum is set to
  1541.    Z_ERRNO and the application may consult errno to get the exact error code.
  1542.  
  1543.      The application must not modify the returned string.  Future calls to
  1544.    this function may invalidate the previously returned string.  If file is
  1545.    closed, then the string previously returned by gzerror will no longer be
  1546.    available.
  1547.  
  1548.      gzerror() should be used to distinguish errors from end-of-file for those
  1549.    functions above that do not distinguish those cases in their return values.
  1550. */
  1551.  
  1552. ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
  1553. /*
  1554.      Clears the error and end-of-file flags for file.  This is analogous to the
  1555.    clearerr() function in stdio.  This is useful for continuing to read a gzip
  1556.    file that is being written concurrently.
  1557. */
  1558.  
  1559. #endif /* !Z_SOLO */
  1560.  
  1561.                         /* checksum functions */
  1562.  
  1563. /*
  1564.      These functions are not related to compression but are exported
  1565.    anyway because they might be useful in applications using the compression
  1566.    library.
  1567. */
  1568.  
  1569. ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
  1570. /*
  1571.      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
  1572.    return the updated checksum.  If buf is Z_NULL, this function returns the
  1573.    required initial value for the checksum.
  1574.  
  1575.      An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
  1576.    much faster.
  1577.  
  1578.    Usage example:
  1579.  
  1580.      uLong adler = adler32(0L, Z_NULL, 0);
  1581.  
  1582.      while (read_buffer(buffer, length) != EOF) {
  1583.        adler = adler32(adler, buffer, length);
  1584.      }
  1585.      if (adler != original_adler) error();
  1586. */
  1587.  
  1588. /*
  1589. ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
  1590.                                           z_off_t len2));
  1591.  
  1592.      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
  1593.    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
  1594.    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
  1595.    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
  1596.    that the z_off_t type (like off_t) is a signed integer.  If len2 is
  1597.    negative, the result has no meaning or utility.
  1598. */
  1599.  
  1600. ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
  1601. /*
  1602.      Update a running CRC-32 with the bytes buf[0..len-1] and return the
  1603.    updated CRC-32.  If buf is Z_NULL, this function returns the required
  1604.    initial value for the crc.  Pre- and post-conditioning (one's complement) is
  1605.    performed within this function so it shouldn't be done by the application.
  1606.  
  1607.    Usage example:
  1608.  
  1609.      uLong crc = crc32(0L, Z_NULL, 0);
  1610.  
  1611.      while (read_buffer(buffer, length) != EOF) {
  1612.        crc = crc32(crc, buffer, length);
  1613.      }
  1614.      if (crc != original_crc) error();
  1615. */
  1616.  
  1617. /*
  1618. ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
  1619.  
  1620.      Combine two CRC-32 check values into one.  For two sequences of bytes,
  1621.    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
  1622.    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
  1623.    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
  1624.    len2.
  1625. */
  1626.  
  1627.  
  1628.                         /* various hacks, don't look :) */
  1629.  
  1630. /* deflateInit and inflateInit are macros to allow checking the zlib version
  1631.  * and the compiler's view of z_stream:
  1632.  */
  1633. ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
  1634.                                      const char *version, int stream_size));
  1635. ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
  1636.                                      const char *version, int stream_size));
  1637. ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
  1638.                                       int windowBits, int memLevel,
  1639.                                       int strategy, const char *version,
  1640.                                       int stream_size));
  1641. ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
  1642.                                       const char *version, int stream_size));
  1643. ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
  1644.                                          unsigned char FAR *window,
  1645.                                          const char *version,
  1646.                                          int stream_size));
  1647. #define deflateInit(strm, level) \
  1648.         deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
  1649. #define inflateInit(strm) \
  1650.         inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
  1651. #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
  1652.         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
  1653.                       (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
  1654. #define inflateInit2(strm, windowBits) \
  1655.         inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
  1656.                       (int)sizeof(z_stream))
  1657. #define inflateBackInit(strm, windowBits, window) \
  1658.         inflateBackInit_((strm), (windowBits), (window), \
  1659.                       ZLIB_VERSION, (int)sizeof(z_stream))
  1660.  
  1661. #ifndef Z_SOLO
  1662.  
  1663. /* gzgetc() macro and its supporting function and exposed data structure.  Note
  1664.  * that the real internal state is much larger than the exposed structure.
  1665.  * This abbreviated structure exposes just enough for the gzgetc() macro.  The
  1666.  * user should not mess with these exposed elements, since their names or
  1667.  * behavior could change in the future, perhaps even capriciously.  They can
  1668.  * only be used by the gzgetc() macro.  You have been warned.
  1669.  */
  1670. struct gzFile_s {
  1671.     unsigned have;
  1672.     unsigned char *next;
  1673.     z_off64_t pos;
  1674. };
  1675. ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
  1676. #ifdef Z_PREFIX_SET
  1677. #  undef z_gzgetc
  1678. #  define z_gzgetc(g) \
  1679.           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
  1680. #else
  1681. #  define gzgetc(g) \
  1682.           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g))
  1683. #endif
  1684.  
  1685. /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
  1686.  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
  1687.  * both are true, the application gets the *64 functions, and the regular
  1688.  * functions are changed to 64 bits) -- in case these are set on systems
  1689.  * without large file support, _LFS64_LARGEFILE must also be true
  1690.  */
  1691. #ifdef Z_LARGE64
  1692.    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
  1693.    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
  1694.    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
  1695.    ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
  1696.    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
  1697.    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
  1698. #endif
  1699.  
  1700. #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
  1701. #  ifdef Z_PREFIX_SET
  1702. #    define z_gzopen z_gzopen64
  1703. #    define z_gzseek z_gzseek64
  1704. #    define z_gztell z_gztell64
  1705. #    define z_gzoffset z_gzoffset64
  1706. #    define z_adler32_combine z_adler32_combine64
  1707. #    define z_crc32_combine z_crc32_combine64
  1708. #  else
  1709. #    define gzopen gzopen64
  1710. #    define gzseek gzseek64
  1711. #    define gztell gztell64
  1712. #    define gzoffset gzoffset64
  1713. #    define adler32_combine adler32_combine64
  1714. #    define crc32_combine crc32_combine64
  1715. #  endif
  1716. #  ifndef Z_LARGE64
  1717.      ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
  1718.      ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
  1719.      ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
  1720.      ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
  1721.      ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
  1722.      ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
  1723. #  endif
  1724. #else
  1725.    ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
  1726.    ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
  1727.    ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
  1728.    ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
  1729.    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
  1730.    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
  1731. #endif
  1732.  
  1733. #else /* Z_SOLO */
  1734.  
  1735.    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
  1736.    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
  1737.  
  1738. #endif /* !Z_SOLO */
  1739.  
  1740. /* hack for buggy compilers */
  1741. #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
  1742.     struct internal_state {int dummy;};
  1743. #endif
  1744.  
  1745. /* undocumented functions */
  1746. ZEXTERN const char   * ZEXPORT zError           OF((int));
  1747. ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
  1748. ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
  1749. ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
  1750. ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
  1751. ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
  1752. #if defined(_WIN32) && !defined(Z_SOLO)
  1753. ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
  1754.                                             const char *mode));
  1755. #endif
  1756. #if defined(STDC) || defined(Z_HAVE_STDARG_H)
  1757. #  ifndef Z_SOLO
  1758. ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
  1759.                                                   const char *format,
  1760.                                                   va_list va));
  1761. #  endif
  1762. #endif
  1763.  
  1764. #ifdef __cplusplus
  1765. }
  1766. #endif
  1767.  
  1768. #endif /* ZLIB_H */
  1769.