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)  2009-2014, VU University, Amsterdam
   7    All rights reserved.
   8
   9    Redistribution and use in source and binary forms, with or without
  10    modification, are permitted provided that the following conditions
  11    are met:
  12
  13    1. Redistributions of source code must retain the above copyright
  14       notice, this list of conditions and the following disclaimer.
  15
  16    2. Redistributions in binary form must reproduce the above copyright
  17       notice, this list of conditions and the following disclaimer in
  18       the documentation and/or other materials provided with the
  19       distribution.
  20
  21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  32    POSSIBILITY OF SUCH DAMAGE.
  33*/
  34
  35:- module(http_server_files,
  36          [ serve_files_in_directory/2  % +Alias, +HTTPRequest
  37          ]).
  38:- use_module(library(http/http_path)).
  39:- use_module(library(http/http_dispatch)).
  40
  41/** <module> Serve files needed by modules from the server
  42
  43This module provides an infrastructure   for serving resource-files such
  44as icons, JavaScript, CSS files, etc.   The default configuration serves
  45the    HTTP    locations    =icons=,     =css=      and     =js=    (see
  46http_absolute_location/3)
  47
  48The location for these services  can  be   changed  by  adding rules for
  49http:location/3.  Directories  providing  additional    or   alternative
  50resources can be achieved by adding rules for user:file_search_path/2.
  51*/
  52
  53:- multifile
  54    http:location/3.                % Alias, Expansion, Options
  55:- dynamic
  56    http:location/3.                % Alias, Expansion, Options
  57
  58http:location(icons, root(icons), [ priority(-100) ]).
  59http:location(css,   root(css),   [ priority(-100) ]).
  60http:location(js,    root(js),    [ priority(-100) ]).
  61
  62:- multifile
  63    user:file_search_path/2.
  64:- dynamic
  65    user:file_search_path/2.
  66
  67user:file_search_path(icons, library('http/web/icons')).
  68user:file_search_path(css,   library('http/web/css')).
  69user:file_search_path(js,    library('http/web/js')).
  70
  71:- http_handler(icons(.), serve_files_in_directory(icons),
  72                [prefix, priority(-100)]).
  73:- http_handler(css(.),   serve_files_in_directory(css),
  74                [prefix, priority(-100)]).
  75:- http_handler(js(.),    serve_files_in_directory(js),
  76                [prefix, priority(-100)]).
  77
  78%!  serve_files_in_directory(+Alias, +Request)
  79%
  80%   Serve files from the directory  Alias   from  the path-info from
  81%   Request.    This    predicate    is     used    together    with
  82%   file_search_path/2. Note that multiple  clauses   for  the  same
  83%   file_search_path alias can be used to merge files from different
  84%   physical locations onto the same HTTP   directory. Note that the
  85%   handler must be declared  as  =prefix=.   Below  is  an  example
  86%   serving images from  http://<host>/img/...   from  the directory
  87%   =http/web/icons=.
  88%
  89%       ==
  90%       http:location(img, root(img), []).
  91%       user:file_search_path(icons, library('http/web/icons')).
  92%
  93%       :- http_handler(img(.), serve_files_in_directory(icons), [prefix]).
  94%       ==
  95%
  96%   This predicate calls http_404/2 if the   physical file cannot be
  97%   located. If the requested  path-name   is  unsafe  (i.e., points
  98%   outside  the  hierarchy  defines    by   the  file_search_path/2
  99%   declaration), this handlers returns a _403 Forbidden_ page.
 100%
 101%   @see http_reply_file/3
 102
 103serve_files_in_directory(Alias, Request) :-
 104    memberchk(path_info(PathInfo), Request),
 105    !,
 106    Term =.. [Alias,PathInfo],
 107    (   catch(http_safe_file(Term, []),
 108              error(permission_error(read, file, _), _),
 109              fail)
 110    ->  (   absolute_file_name(Term, Path,
 111                               [ access(read),
 112                                 file_errors(fail)
 113                               ])
 114        ->  http_reply_file(Path,
 115                            [ unsafe(true),
 116                              static_gzip(true)
 117                            ], Request)
 118        ;   http_404([], Request)
 119        )
 120    ;   memberchk(path(Path), Request),
 121        throw(http_reply(forbidden(Path)))
 122    ).
 123serve_files_in_directory(_Alias, Request) :-
 124    memberchk(path(Path), Request),
 125    throw(http_reply(forbidden(Path))).