~azzar1/unity/add-show-desktop-key

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# IVLE - Informatics Virtual Learning Environment
# Copyright (C) 2007-2008 The University of Melbourne
#
# 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 program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

# Module: cgirequest
# Author: Matt Giuca
# Date:   5/2/2007

# Presents a CGIRequest class which creates an object compatible with IVLE
# Request objects (the same interface exposed by www.dispatch.request) from a
# CGI script.
# This allows CGI scripts to create request objects and then pass them to
# normal IVLE handlers.

import sys
import os
import os.path
import cgi
import urllib
import traceback

import ivle.conf
import ivle.util

# Utility functions

def _http_headers_in_from_cgi():
    """Returns a dictionary of HTTP headers and their values, reading from the
    CGI environment."""
    d = {}
    for k in os.environ.keys():
        if k.startswith("HTTP_"):
            # Change the case - underscores become - and each word is
            # capitalised
            varname = '-'.join(map(lambda x: x[0:1] + x[1:].lower(),
                                k[5:].split('_')))
            d[varname] = os.environ[k]
    return d

class CGIRequest:
    """An IVLE request object, built from a CGI script. This is presented to
    the IVLE apps as a way of interacting with the CGI server.
    See dispatch.request for a full interface specification.
    """

    # COPIED from dispatch/request.py
    # Special code for an OK response.
    # Do not use HTTP_OK; for some reason Apache produces an "OK" error
    # message if you do that.
    OK  = 0

    # HTTP status codes

    HTTP_CONTINUE                     = 100
    HTTP_SWITCHING_PROTOCOLS          = 101
    HTTP_PROCESSING                   = 102
    HTTP_OK                           = 200
    HTTP_CREATED                      = 201
    HTTP_ACCEPTED                     = 202
    HTTP_NON_AUTHORITATIVE            = 203
    HTTP_NO_CONTENT                   = 204
    HTTP_RESET_CONTENT                = 205
    HTTP_PARTIAL_CONTENT              = 206
    HTTP_MULTI_STATUS                 = 207
    HTTP_MULTIPLE_CHOICES             = 300
    HTTP_MOVED_PERMANENTLY            = 301
    HTTP_MOVED_TEMPORARILY            = 302
    HTTP_SEE_OTHER                    = 303
    HTTP_NOT_MODIFIED                 = 304
    HTTP_USE_PROXY                    = 305
    HTTP_TEMPORARY_REDIRECT           = 307
    HTTP_BAD_REQUEST                  = 400
    HTTP_UNAUTHORIZED                 = 401
    HTTP_PAYMENT_REQUIRED             = 402
    HTTP_FORBIDDEN                    = 403
    HTTP_NOT_FOUND                    = 404
    HTTP_METHOD_NOT_ALLOWED           = 405
    HTTP_NOT_ACCEPTABLE               = 406
    HTTP_PROXY_AUTHENTICATION_REQUIRED= 407
    HTTP_REQUEST_TIME_OUT             = 408
    HTTP_CONFLICT                     = 409
    HTTP_GONE                         = 410
    HTTP_LENGTH_REQUIRED              = 411
    HTTP_PRECONDITION_FAILED          = 412
    HTTP_REQUEST_ENTITY_TOO_LARGE     = 413
    HTTP_REQUEST_URI_TOO_LARGE        = 414
    HTTP_UNSUPPORTED_MEDIA_TYPE       = 415
    HTTP_RANGE_NOT_SATISFIABLE        = 416
    HTTP_EXPECTATION_FAILED           = 417
    HTTP_UNPROCESSABLE_ENTITY         = 422
    HTTP_LOCKED                       = 423
    HTTP_FAILED_DEPENDENCY            = 424
    HTTP_INTERNAL_SERVER_ERROR        = 500
    HTTP_NOT_IMPLEMENTED              = 501
    HTTP_BAD_GATEWAY                  = 502
    HTTP_SERVICE_UNAVAILABLE          = 503
    HTTP_GATEWAY_TIME_OUT             = 504
    HTTP_VERSION_NOT_SUPPORTED        = 505
    HTTP_VARIANT_ALSO_VARIES          = 506
    HTTP_INSUFFICIENT_STORAGE         = 507
    HTTP_NOT_EXTENDED                 = 510

    def __init__(self):
        """Builds an CGI Request object from the current CGI environment.
        This results in an object with all of the necessary methods and
        additional fields.
        """
        self.headers_written = False

        if ('SERVER_NAME' not in os.environ or
            'REQUEST_METHOD' not in os.environ or
            'SCRIPT_NAME' not in os.environ or
            'PATH_INFO' not in os.environ):
            raise Exception("No CGI environment found")

        # Determine if the browser used the public host name to make the
        # request (in which case we are in "public mode")
        if os.environ['SERVER_NAME'] == ivle.conf.public_host:
            self.publicmode = True
        else:
            self.publicmode = False

        # Inherit values for the input members
        self.method = os.environ['REQUEST_METHOD']
        self.uri = os.environ['SCRIPT_NAME'] + os.environ['PATH_INFO']
        # Split the given path into the app (top-level dir) and sub-path
        # (after first stripping away the root directory)
        if self.publicmode:
            self.app = None
            (_, self.path) = (ivle.util.split_path(self.uri))
        else:
            (self.app, self.path) = (ivle.util.split_path(self.uri))
        self.user = None
        self.hostname = os.environ['SERVER_NAME']
        self.headers_in = _http_headers_in_from_cgi()
        self.headers_out = {}

        # Default values for the output members
        self.status = CGIRequest.HTTP_OK
        self.content_type = None        # Use Apache's default
        self.location = None
        self.styles = []
        self.scripts = []
        self.got_common_vars = False


    def install_error_handler(self):
        '''Install our exception handler as the default.'''
        sys.excepthook = self.handle_unknown_exception

    def __writeheaders(self):
        """Writes out the HTTP and HTML headers before any real data is
        written."""
        self.headers_written = True
        if 'Content-Type' in self.headers_out:
            self.content_type = self.headers_out['Content-Type']
        if 'Location' in self.headers_out:
            self.location = self.headers_out['Location']

        # CGI allows for four response types: Document, Local Redirect, Client
        # Redirect, and Client Redirect w/ Document
        # XXX We do not allow Local Redirect
        if self.location != None:
            # This is a Client Redirect
            print "Location: %s" % self.location
            if self.content_type == None:
                # Just redirect
                return
            # Else: This is a Client Redirect with Document
            print "Status: %d" % self.status
            print "Content-Type: %s" % self.content_type
        else:
            # This is a Document response
            print "Content-Type: %s" % self.content_type
            print "Status: %d" % self.status

        # Print the other headers
        for k,v in self.headers_out.items():
            if k != 'Content-Type' and k != 'Location':
                print "%s: %s" % (k, v)

        # Print a blank line to signal the start of output
        print

    def ensure_headers_written(self):
        """Writes out the HTTP and HTML headers if they haven't already been
        written."""
        if not self.headers_written:
            self.__writeheaders()

    def write(self, string, flush=1):
        """Writes string directly to the client, then flushes the buffer,
        unless flush is 0."""

        if not self.headers_written:
            self.__writeheaders()
        if isinstance(string, unicode):
            # Encode unicode strings as UTF-8
            # (Otherwise cannot handle being written to a bytestream)
            sys.stdout.write(string.encode('utf8'))
        else:
            # 8-bit clean strings just get written directly.
            # This includes binary strings.
            sys.stdout.write(string)

    def flush(self):
        """Flushes the output buffer."""
        sys.stdout.flush()

    def sendfile(self, filename):
        """Sends the named file directly to the client."""
        if not self.headers_written:
            self.__writeheaders()
        f = open(filename)
        buf = f.read(1024)
        while len(buf) > 0:
            sys.stdout.write(buf)
            sys.stdout.flush()
            buf = f.read(1024)
        f.close()

    def read(self, len=None):
        """Reads at most len bytes directly from the client. (See mod_python
        Request.read)."""
        if len is None:
            return sys.stdin.read()
        else:
            return sys.stdin.read(len)

    def handle_unknown_exception(self, exc_type, exc_value, exc_tb):
        if exc_type is ivle.util.IVLEError:
            self.headers_out['X-IVLE-Error-Code'] = exc_value.httpcode

        self.headers_out['X-IVLE-Error-Type'] = exc_type.__name__

        try:
            self.headers_out['X-IVLE-Error-Message'] = exc_value.message
        except AttributeError:
            pass

        self.headers_out['X-IVLE-Error-Info'] = urllib.quote(''.join(
              traceback.format_exception(exc_type, exc_value, exc_tb)))
        self.status = 500
        self.ensure_headers_written()
        self.write('An internal IVLE error has occurred.')
        self.flush()
        sys.exit(self.status)

    def throw_redirect(self, location):
        """Writes out an HTTP redirect to the specified URL. Exits the
        process, so any code following this call will not be executed.

        httpcode: An HTTP response status code. Pass a constant from the
        Request class.
        """
        self.status = CGIRequest.HTTP_MOVED_TEMPORARILY
        self.location = location
        self.ensure_headers_written()
        self.flush()
        sys.exit(self.status)

    def get_session(self):
        """Returns a mod_python Session object for this request.
        Note that this is dependent on mod_python and may need to change
        interface if porting away from mod_python."""
        # Cache the session object
        if not hasattr(self, 'session'):
            #self.session = Session.FileSession(self.apache_req)
            self.session = None
            # FIXME: How to get session?
        return self.session

    def get_fieldstorage(self):
        """Returns a mod_python FieldStorage object for this request.
        Note that this is dependent on mod_python and may need to change
        interface if porting away from mod_python."""
        # Cache the fieldstorage object
        if not hasattr(self, 'fields'):
            self.fields = cgi.FieldStorage()
        return self.fields

    def get_cgi_environ(self):
        """Returns the CGI environment emulation for this request. (Calls
        add_common_vars). The environment is returned as a mapping
        compatible with os.environ."""
        return os.environ