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# Copyright (C) 2007-2008 The University of Melbourne
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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# App: File Service (AJAX server)
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# This application is an AJAX service. Receives file handling instructions as
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# requests. Performs actions on the student's workspace, and returns directory
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# This rather large documentation explains the request and response to the
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# file service app (it should probably be taken to a separate document).
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# This is not intended to be accessed directly by the user. It is targeted by
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# AJAX calls in applications such as browser and editor.
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# Application usage: The input to the application is determined by the fields
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# passed in as HTTP variables (either in the URL or message body). Also, in
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# keeping with REST, actions only take effect if this is a POST request as
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# opposed to a GET request (although a GET request is still allowed to just
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# get a listing or file dump). Also, the "path" (the part of the URL
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# after "fileservice" and before the GET variables) is taken into account.
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# Aside from the side-effects to the server (note: side-effects are only
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# possible for POST requests), the response takes two parts. The response
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# header contains information about success or failure of the operation. The
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# response body may contain the requested file.
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# Fileservice has two separate roles: First, an action is performed. This may
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# be a copy, write, or svn up operation. Then, either a directory listing or
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# file contents are returned.
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# This listing/contents may be completely separate from the action,
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# but they are performed together because the client will usually want to
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# perform some action, then update its display as a result of the action.
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# The special "return" variable can be "listing" or "contents" - listing is
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# the default if unspecified. If "listing", it will return a directory listing
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# of the file specified. If the file is not a directory, it just returns a
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# single "." object, with details about the file.
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# If "contents", it will return the contents of the file specified. If the
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# file is a directory, it will simply return the listing again.
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# GET requests will have all variables other than "return" ignored, and the
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# only behaviour will be to generate the directory or file listing. POST
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# requests will result in an action if one is specified. If the action is
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# UNSUCCESSFUL, returns the header "X-IVLE-Action-Error: <errormessage>".
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# Successful actions succeed silently. Note that the action does not affect
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# the HTTP response code (it may be 200 even upon failure).
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# The path (req.path) controls which file or directory will be
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# returned. If it is a file, returns the header "X-IVLE-Return: File" and
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# status 200 OK. The response body is either a verbatim dump of the file
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# specified, or a single-file directory listing, as described above.
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# The Content-Type will probably be text/plain but should not be relied upon.
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# If it is a directory, returns the header "X-IVLE-Return: Dir" and status
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# 200 OK. The response body is a JSON directory listing (see below). The
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# Content-Type cannot be relied upon. If the file is not found or there is
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# some other read error, returns no X-IVLE-Return header, a 400-level
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# response status. (404 File Not Found, 403 Forbidden, etc), and a header
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# "X-IVLE-Return-Error: <errormessage>".
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# See action.py for a full description of the actions.
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# See listing.py for a full description of the output format of the directory
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from ivle import (util, studpath)
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import action, listing
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# application/json is the "best" content type but is not good for
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# debugging because Firefox just tries to download it
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mime_dirlisting = "text/html"
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#mime_dirlisting = "application/json"
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"""Handler for the File Services application."""
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# Make sure the logged in user has permission to see this file
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# FIXME: Still need to authorize subpaths in actions
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#studpath.authorize(req)
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# Set request attributes
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req.write_html_head_foot = False # No HTML
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# We really, really don't want the responses to be cached.
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req.headers_out['Cache-Control'] = 'no-store, must-revalidate'
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# Get all the arguments, if POST.
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# Ignore arguments if not POST, since we aren't allowed to cause
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# side-effects on the server.
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fields = req.get_fieldstorage()
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if req.method == 'POST':
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act = fields.getfirst('action')
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action.handle_action(req, act, fields)
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except action.ActionError, message:
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req.headers_out['X-IVLE-Action-Error'] = \
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urllib.quote(str(message))
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return_type = fields.getfirst('return')
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listing.handle_return(req, return_type == "contents")