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 ZLIB(3)                                                             ZLIB(3)
                                 18 Aug 2023

      zlib - compression/decompression library

      [see zlib.h for full description]

      The zlib library is a general purpose data compression library.  The
      code is thread safe, assuming that the standard library functions used
      are thread safe, such as memory allocation routines.  It provides in-
      memory compression and decompression functions, including integrity
      checks of the uncompressed data.  This version of the library supports
      only one compression method (deflation) but other algorithms may be
      added later with the same stream interface.  Compression can be done
      in a single step if the buffers are large enough or can be done by
      repeated calls of the compression function.  In the latter case, the
      application must provide more input and/or consume the output
      (providing more output space) before each call.  The library also
      supports reading and writing files in gzip(1) (.gz) format with an
      interface similar to that of stdio.  The library does not install any
      signal handler.  The decoder checks the consistency of the compressed
      data, so the library should never crash even in the case of corrupted
      input.  All functions of the compression library are documented in the
      file zlib.h.  The distribution source includes examples of use of the
      library in the files test/example.c and test/minigzip.c, as well as
      other examples in the examples/ directory.  Changes to this version
      are documented in the file ChangeLog that accompanies the source.
      zlib is built in to many languages and operating systems, including
      but not limited to Java, Python, .NET, PHP, Perl, Ruby, Swift, and Go.
      An experimental package to read and write files in the .zip format,
      written on top of zlib by Gilles Vollant (, is
      available at:

  and also in the
           contrib/minizip directory of the main zlib source distribution.

      The zlib web site can be found at:

  The data format used by the zlib library is
           described by RFC (Request for Comments) 1950 to 1952 in the

  (for the zlib header and
           trailer format)
  (for the deflate compressed
           data format)
  (for the gzip header and
           trailer format) Mark Nelson wrote an article about zlib for the
           Jan. 1997 issue of  Dr. Dobb's Journal; a copy of the article is
           available at:

                                    - 1 -       Formatted:  December 6, 2023

 ZLIB(3)                                                             ZLIB(3)
                                 18 Aug 2023


      Before reporting a problem, please check the zlib web site to verify
      that you have the latest version of zlib; otherwise, obtain the latest
      version and see if the problem still exists.  Please read the zlib FAQ

  before asking for help.  Send
           questions and/or comments to, or (for the Windows
           DLL version) to Gilles Vollant (

      Version 1.3 Copyright (C) 1995-2023 Jean-loup Gailly and Mark Adler
      This software is provided 'as-is', without any express or implied
      warranty.  In no event will the authors be held liable for any damages
      arising from the use of this software.  Permission is granted to
      anyone to use this software for any purpose, including commercial
      applications, and to alter it and redistribute it freely, subject to
      the following restrictions:

         The origin of this software must not be misrepresented; you must
         not claim that you wrote the original software. If you use this
         software in a product, an acknowledgment in the product
         documentation would be appreciated but is not required.

         Altered source versions must be plainly marked as such, and must
         not be misrepresented as being the original software.

         This notice may not be removed or altered from any source
         distribution.  Jean-loup Gailly        Mark Adler The deflate
         format used by zlib was defined by Phil Katz.  The deflate and zlib
         specifications were written by L. Peter Deutsch.  Thanks to all the
         people who reported problems and suggested various improvements in
         zlib; who are too numerous to cite here.  UNIX manual page by R. P.
         C. Rodgers, U.S. National Library of Medicine

                                    - 2 -       Formatted:  December 6, 2023