1/*  Part of SWI-Prolog
   2
   3    Author:        Jan Wielemaker
   4    E-mail:        J.Wielemaker@vu.nl
   5    WWW:           http://www.swi-prolog.org
   6    Copyright (c)  2006-2016, University of Amsterdam
   7                              VU University Amsterdam
   8    All rights reserved.
   9
  10    Redistribution and use in source and binary forms, with or without
  11    modification, are permitted provided that the following conditions
  12    are met:
  13
  14    1. Redistributions of source code must retain the above copyright
  15       notice, this list of conditions and the following disclaimer.
  16
  17    2. Redistributions in binary form must reproduce the above copyright
  18       notice, this list of conditions and the following disclaimer in
  19       the documentation and/or other materials provided with the
  20       distribution.
  21
  22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33    POSSIBILITY OF SUCH DAMAGE.
  34*/
  35
  36:- module(zlib,
  37          [ zopen/3,                    % +Stream, -ZStream, +Option
  38            gzopen/3,                   % +File, +Mode, -Stream
  39            gzopen/4                    % +File, +Mode, -Stream, +Options
  40          ]).
  41:- use_module(library(shlib)).
  42:- use_module(library(error)).
  43:- use_module(library(apply)).
  44:- use_module(library(option)).
  45
  46:- predicate_options(zopen/3, 3,
  47                     [ format(oneof([gzip,deflate])),
  48                       multi_part(boolean),
  49                       close_parent(boolean),
  50                       level(between(0,9))
  51                     ]).
  52:- predicate_options(gzopen/4, 4,
  53                     [ pass_to(zopen/3, 3),
  54                       pass_to(system:open/4, 4)
  55                     ]).
  56
  57/** <module> Zlib wrapper for SWI-Prolog
  58
  59Read/write compressed data based on the zlib library.
  60
  61@author Jan Wielemaker
  62@see    http://www.zlib.net/
  63@see    http://www.swi-prolog.org/packages/zlib.html
  64*/
  65
  66:- use_foreign_library(foreign(zlib4pl)).
  67:- public zdebug/1.                     % Set debug level
  68
  69%!  gzopen(+File, +Mode, -Stream) is det.
  70%!  gzopen(+File, +Mode, -Stream, +Options) is det.
  71%
  72%   Open a file compatible with the  gzip   program.  Note that if a
  73%   file is opened in =append= mode,  a   second  gzip image will be
  74%   added to the end of the file.   The gzip standard defines that a
  75%   file can hold multiple  gzip  images   and  inflating  the  file
  76%   results in a concatenated stream of all inflated images.
  77%
  78%   Options are passed to open/4  and   zopen/3.  Default  format is
  79%   =gzip=.
  80
  81gzopen(File, Mode, Stream) :-
  82    gzopen(File, Mode, Stream, []).
  83
  84gzopen(File, Mode, Stream, Options) :-
  85    must_be(oneof([read,write,append]), Mode),
  86    partition(zoption, Options, ZOptions0, OpenOptions),
  87    merge_options(ZOptions0,
  88                  [ format(gzip),
  89                    close_parent(true)
  90                  ], ZOptions),
  91    open(File, Mode, Stream0, OpenOptions),
  92    zopen(Stream0, Stream, ZOptions),
  93    set_stream(Stream, file_name(File)),
  94    (   option(alias(Alias), ZOptions)
  95    ->  set_stream(Stream, alias(Alias))
  96    ;   true
  97    ).
  98
  99
 100zoption(format(_)).
 101zoption(multi_part(_)).
 102zoption(level(_)).
 103zoption(alias(_)).
 104
 105%!  http:encoding_filter(+Encoding, +In0, -In) is semidet.
 106%
 107%   Act as plugin for library(http/http_open) for processing content
 108%   with =|Content-encoding: gzip|=
 109
 110http:encoding_filter(gzip, In0, In) :-
 111    zopen(In0, In,
 112          [ close_parent(true)
 113          ]).