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yap-6.3/packages/http/http_pwp.pl

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2010-06-23 11:52:34 +01:00
/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@cs.vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 2009, VU University, Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(http_pwp,
[ reply_pwp_page/3, % :File, +Options, +Request
pwp_handler/2 % +Options, +Request
]).
:- use_module(library(http/http_dispatch)).
:- use_module(library(sgml)).
:- use_module(library(sgml_write)).
:- use_module(library(option)).
:- use_module(library(error)).
:- use_module(library(lists)).
:- use_module(library(pwp)).
/** <module> Serve PWP pages through the HTTP server
This module provides convience predicates to include PWP (Prolog
Well-formed Pages) in a Prolog web-server. It provides the following
predicates:
* pwp_handler/2
This is a complete web-server aimed at serving static pages, some
of which include PWP. This API is intended to allow for programming
the web-server from a hierarchy of pwp files, prolog files and static
web-pages.
* reply_pwp_page/3
Return a single PWP page that is executed in the context of the calling
module. This API is intended for individual pages that include so much
text that generating from Prolog is undesirable.
@tbd Support elements in the HTML header that allow controlling the
page, such as setting the CGI-header, authorization, etc.
@tbd Allow external styling. Pass through reply_html_page/2? Allow
filtering the DOM before/after PWP?
*/
%% pwp_handler(+Options, +Request)
%
% Handle PWP files. This predicate is defined to create a simple
% HTTP server from a hierarchy of PWP, HTML and other files. The
% interface is kept compatible with the
% library(http/http_dispatch). In the typical usage scenario, one
% needs to define an http location and a file-search path that is
% used as the root of the server. E.g., the following declarations
% create a self-contained web-server for files in =|/web/pwp/|=.
%
% ==
% user:file_search_path(pwp, '/web/pwp').
%
% :- http_handler(root(.), pwp_handler([path_alias(pwp)]), [prefix]).
% ==
%
% Options include:
%
% * path_alias(+Alias)
% Search for PWP files as Alias(Path). See absolute_file_name/3.
% * index(+Index)
% Name of the directory index (pwp) file. This option may
% appear multiple times. If no such option is provided,
% pwp_handler/2 looks for =|index.pwp|=.
% * view(+Boolean)
% If =true= (default is =false=), allow for ?view=source to serve
% PWP file as source.
% * index_hook(:Hook)
% If a directory has no index-file, pwp_handler/2 calls
% Hook(PhysicalDir, Options, Request). If this semidet
% predicate succeeds, the request is considered handled.
% * hide_extensions(+List)
% Hide files of the given extensions. The default is to
% hide .pl files.
%
% @see reply_pwp_page/3
% @error permission_error(index, http_location, Location) is
% raised if the handler resolves to a directory that has no
% index.
:- meta_predicate
pwp_handler(:, +).
pwp_handler(QOptions, Request) :-
meta_options(is_meta, QOptions, Options),
( memberchk(path_info(Spec), Request)
-> true
; Spec = '.'
),
( option(path_alias(Alias), Options)
-> Term =.. [Alias,Spec]
; Term = Spec
),
http_safe_file(Term, Options),
absolute_file_name(Term, Path, [access(read)]),
( exists_directory(Path)
-> ensure_slash(Path, Dir),
( ( member(index(Index), Options)
*-> true
; Index = 'index.pwp'
),
atom_concat(Dir, Index, File),
access_file(File, read)
-> true
; option(index_hook(Hook), Options),
call(Hook, Path, Options, Request)
-> true
; memberchk(path(Location), Request),
permission_error(index, http_location, Location)
)
; File = Path
),
server_file(File, Request, Options).
is_meta(index_hook).
server_file(File, _, _) :- % index-hook did the work
var(File), !.
server_file(File, Request, Options) :-
file_name_extension(_, pwp, File), !,
( option(view(true), Options),
memberchk(search(Query), Request),
memberchk(view=source, Query)
-> http_reply_file(File, [ mime_type(text/plain),
unsafe(true)
], Request)
; merge_options(Options,
[ pwp_module(true)
], Opts),
reply_pwp_page(File, [unsafe(true)|Opts], Request)
).
server_file(File, Request, Options) :-
option(hide_extensions(Exts), Options, [pl]),
file_name_extension(_, Ext, File),
( memberchk(Ext, Exts)
-> memberchk(path(Location), Request),
permission_error(read, http_location, Location)
; http_reply_file(File, [unsafe(true)|Options], Request)
).
ensure_slash(Path, Dir) :-
( sub_atom(Path, _, _, 0, /)
-> Dir = Path
; atom_concat(Path, /, Dir)
).
%% reply_pwp_page(:File, +Options, +Request)
%
% Reply a PWP file. This interface is provided to server
% individual locations from PWP files. Using a PWP file rather
% than generating the page from Prolog may be desirable because
% the page contains a lot of text (which is cumbersome to generate
% from Prolog) or because the maintainer is not familiar with
% Prolog.
%
% Options supported are:
%
% * mime_type(+Type)
% Serve the file using the given mime-type. Default is
% text/html.
% * unsafe(+Boolean)
% Passed to http_safe_file/2 to check for unsafe paths.
% * pwp_module(+Boolean)
% If =true=, (default =false=), process the PWP file in
% a module constructed from its canonical absolute path.
% Otherwise, the PWP file is processed in the calling
% module.
%
% Initial context:
%
% * SCRIPT_NAME
% Virtual path of the script.
% * SCRIPT_DIRECTORY
% Physical directory where the script lives
% * QUERY
% Var=Value list representing the query-parameters
% * REMOTE_USER
% If access has been authenticated, this is the authenticated
% user.
% * REQUEST_METHOD
% One of =get=, =post=, =put= or =head=
% * CONTENT_TYPE
% Content-type provided with HTTP POST and PUT requests
% * CONTENT_LENGTH
% Content-length provided with HTTP POST and PUT requests
%
% While processing the script, the file-search-path pwp includes
% the current location of the script. I.e., the following will
% find myprolog in the same directory as where the PWP file
% resides.
%
% ==
% pwp:ask="ensure_loaded(pwp(myprolog))"
% ==
%
% @tbd complete the initial context, as far as possible from CGI
% variables. See http://hoohoo.ncsa.illinois.edu/docs/cgi/env.html
% @see pwp_handler/2.
:- meta_predicate
reply_pwp_page(:, +, +).
reply_pwp_page(M:File, Options, Request) :-
http_safe_file(File, Options),
absolute_file_name(File, Path,
[ access(read)
]),
memberchk(method(Method), Request),
file_directory_name(Path, Dir),
load_xml_file(Path, Contents),
findall(C, pwp_context(Request, C), Context),
( option(pwp_module(true), Options)
-> PWP_M = Path
; PWP_M = M
),
setup_call_cleanup(asserta(script_dir(Dir), Ref),
pwp_xml(PWP_M:Contents, Transformed,
[ 'REQUEST_METHOD' = Method,
'SCRIPT_DIRECTORY' = Dir
| Context
]),
erase(Ref)),
option(mime_type(Type), Options, text/html),
format('Content-type: ~w~n~n', [Type]),
xml_write(current_output, Transformed, []).
pwp_context(Request, 'REMOTE_USER' = User) :-
memberchk(user(User), Request).
pwp_context(Request, 'QUERY' = Query) :-
memberchk(search(Query), Request).
pwp_context(Request, 'SCRIPT_NAME' = Path) :-
memberchk(path(Path), Request).
pwp_context(Request, 'CONTENT_TYPE' = ContentType) :-
memberchk(content_type(ContentType), Request).
pwp_context(Request, 'CONTENT_LENGTH' = Length) :-
memberchk(content_length(Length), Request).
:- multifile user:file_search_path/2.
:- dynamic user:file_search_path/2.
:- thread_local script_dir/1.
user:file_search_path(pwp, ScriptDir) :-
script_dir(ScriptDir).