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zlib(3)                                                                zlib(3)


       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 con-
       sume 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 avail-
       able 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 files:

      (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:



       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 1.2.10

       Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler

       This software is provided 'as-is', without any express or implied  war-
       ranty.   In  no  event  will the authors be held liable for any damages
       arising from the use of this software.

       Permission is granted to anyone to use this software for  any  purpose,
       including  commercial applications, and to alter it and redistribute it
       freely, subject to the following restrictions:

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

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

       3. This notice may not be removed or altered from any source  distribu-

       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 Jan 2017                           zlib(3)

zlib 1.2.10 - Generated Sat Jan 7 12:47:46 CST 2017
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