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

# 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: util

# Author: Matt Giuca

# Date: 12/12/2007

# Contains common utility functions.

# Also initialises mime types library. You must import util before using

# Python's builtin mimetypes module to make sure local settings are applied.

import os

import mimetypes

import datetime

import ivle.conf

import ivle.conf.mimetypes

class IVLEError(Exception):

    """

    This is the "standard" exception class for IVLE errors.

    It is the ONLY exception which should propagate to the top - it will then

    be displayed to the user as an HTTP error with the given code.

    All other exceptions are considered IVLE bugs and should not occur

    (they will display a traceback).

    This error should not be raised directly. Call req.throw_error.

    """

    def __init__(self, httpcode, message=None):

        self.httpcode = httpcode

        self.message = message

        self.args = (httpcode, message)

class IVLEJailError(Exception):

    """

    This exception indicates an error that occurred inside an IVLE CGI script

    inside the jail. It should never be raised directly - only by the 

    interpreter.

    Information will be retrieved from it, and then treated as a normal

    error.

    """

    def __init__(self, type_str, message, info):

        self.type_str = type_str

        self.message = message

        self.info = info

class FakeObject(object):

    """ A representation of an object that can't be Pickled """

    def __init__(self, type, name, attrib={}):

        self.type = type

        self.name = name

        self.attrib = attrib

    def __repr__(self):

        return "<Fake %s %s>"%(self.type, self.name)

def make_path(path):

    """Given a path relative to the IVLE root, makes the path relative to the

    site root using ivle.conf.root_dir. This path can be used in URLs sent to

    the client."""

    return os.path.join(ivle.conf.root_dir, path)

def make_local_path(path):

    """Given a path relative to the IVLE root, on the local file system, makes

    the path relative to the root using ivle.conf.share_path. This path can

    be used in reading files from the local file system."""

    return os.path.join(ivle.conf.share_path, 'www', path)

def unmake_path(path):

    """Given a path relative to the site root, makes the path relative to the

    IVLE root by removing ivle.conf.root_dir if it appears at the beginning. If

    it does not appear at the beginning, returns path unchanged. Also

    normalises the path."""

    path = os.path.normpath(path)

    root = os.path.normpath(ivle.conf.root_dir)

    if path.startswith(root):

        path = path[len(root):]

        # Take out the slash as well

        if len(path) > 0 and path[0] == os.sep:

            path = path[1:]

    return path

def split_path(path):

    """Given a path, returns a tuple consisting of the top-level directory in

    the path, and the rest of the path. Note that both items in the tuple will

    NOT begin with a slash, regardless of whether the original path did. Also

    normalises the path.

    Always returns a pair of strings, except for one special case, in which

    the path is completely empty (or just a single slash). In this case the

    return value will be (None, ''). But still always returns a pair.

    Examples:

    >>> split_path("")

    (None, '')

    >>> split_path("/")

    (None, '')

    >>> split_path("home")

    ('home', '')

    >>> split_path("home/docs/files")

    ('home', 'docs/files')

    >>> split_path("//home/docs/files")

    ('', 'home/docs/files')

    """

    path = os.path.normpath(path)

    # Ignore the opening slash

    if path.startswith(os.sep):

        path = path[len(os.sep):]

    if path == '' or path == '.':

        return (None, '')

    splitpath = path.split(os.sep, 1)

    if len(splitpath) == 1:

        return (splitpath[0], '')

    else:

        return tuple(splitpath)

def open_exercise_file(exercisename):

    """Given an exercise name, opens the corresponding XML file for reading.

    Returns None if the exercise file was not found.

    (For tutorials / worksheets).

    """

    # First normalise the path

    exercisename = os.path.normpath(exercisename)

    # Now if it begins with ".." or separator, then it's illegal

    if exercisename.startswith("..") or exercisename.startswith(os.sep):

        exercisefile = None

    else:

        exercisefile = os.path.join(ivle.conf.exercises_base, exercisename)

    try:

        return open(exercisefile)

    except (TypeError, IOError):    # TypeError if exercisefile == None

        return None

# Initialise mime types library

mimetypes.init()

for (ext, mimetype) in ivle.conf.mimetypes.additional_mime_types.items():

    mimetypes.add_type(mimetype, ext)

def nice_filetype(filename):

    """Given a filename or basename, returns a "friendly" name for that

    file's type.

    eg. nice_mimetype("file.py") == "Python source code".

        nice_filetype("file.bzg") == "BZG file".

        nice_filetype("directory/") == "Directory".

    """

    if filename[-1] == os.sep:

        return "Directory"

    else:

        try:

            return ivle.conf.mimetypes.nice_mimetypes[

                mimetypes.guess_type(filename)[0]]

        except KeyError:

            filename = os.path.basename(filename)

            try:

                return filename[filename.rindex('.')+1:].upper() + " file"

            except ValueError:

                return "File"

def send_terms_of_service(req):

    """

    Sends the Terms of Service document to the req object.

    This consults conf to find out where the TOS is located on disk, and sends

    that. If it isn't found, it sends a generic message explaining to admins

    how to create a real one.

    """

    try:

        req.sendfile(ivle.conf.tos_path)

    except IOError:

        req.write(

"""<h1>Terms of Service</h1>

<p><b>*** SAMPLE ONLY ***</b></p>

<p>This is the text of the IVLE Terms of Service.</p>

<p>The administrator should create a license file with an appropriate

"Terms of Service" license for your organisation.</p>

<h2>Instructions for Administrators</h2>

<p>You are seeing this message because you have not configured a Terms of

Service document.</p>

<p>When you configured IVLE, you specified a path to the Terms of Service

document (this is found in <b><tt>ivle/conf/conf.py</tt></b> under

"<tt>tos_path</tt>").</p>

<p>Create a file at this location; an HTML file with the appropriately-worded

license.</p>

<p>This should be a normal XHTML file, except it should not contain

<tt>html</tt>, <tt>head</tt> or <tt>body</tt> elements - it should

just be the contents of a body element (IVLE will wrap it accordingly).</p>

<p>This will automatically be used as the license text instead of this

placeholder text.</p>

""")

def parse_iso8601(str):

    """Parses ISO8601 string into a datetime object."""

    # FIXME: Terrific hack that means we only accept the format that is 

    # produced by json.js module when it encodes date objects.

    return datetime.datetime.strptime(str, "%Y-%m-%dT%H:%M:%SZ")

def incomplete_utf8_sequence(byteseq):

    """

    str -> int

    Given a UTF-8-encoded byte sequence (str), returns the number of bytes at

    the end of the string which comprise an incomplete UTF-8 character

    sequence.

    If the string is empty or ends with a complete character OR INVALID

    sequence, returns 0.

    Otherwise, returns 1-3 indicating the number of bytes in the final

    incomplete (but valid) character sequence.

    Does not check any bytes before the final sequence for correctness.

    >>> incomplete_utf8_sequence("")

    0

    >>> incomplete_utf8_sequence("xy")

    0

    >>> incomplete_utf8_sequence("xy\xc3\xbc")

    0

    >>> incomplete_utf8_sequence("\xc3")

    1

    >>> incomplete_utf8_sequence("\xbc\xc3")

    1

    >>> incomplete_utf8_sequence("xy\xbc\xc3")

    1

    >>> incomplete_utf8_sequence("xy\xe0\xa0")

    2

    >>> incomplete_utf8_sequence("xy\xf4")

    1

    >>> incomplete_utf8_sequence("xy\xf4\x8f")

    2

    >>> incomplete_utf8_sequence("xy\xf4\x8f\xa0")

    3

    """

    count = 0

    expect = None

    for b in byteseq[::-1]:

        b = ord(b)

        count += 1

        if b & 0x80 == 0x0:

            # 0xxxxxxx (single-byte character)

            expect = 1

            break

        elif b & 0xc0 == 0x80:

            # 10xxxxxx (subsequent byte)

            pass

        elif b & 0xe0 == 0xc0:

            # 110xxxxx (start of 2-byte sequence)

            expect = 2

            break

        elif b & 0xf0 == 0xe0:

            # 1110xxxx (start of 3-byte sequence)

            expect = 3

            break

        elif b & 0xf8 == 0xf0:

            # 11110xxx (start of 4-byte sequence)

            expect = 4

            break

        else:

            # Invalid byte

            return 0

        if count >= 4:

            # Seen too many "subsequent bytes", invalid

            return 0

    if expect is None:

        # We never saw a "first byte", invalid

        return 0

    # We now know expect and count

    if count >= expect:

        # Complete, or we saw an invalid sequence

        return 0

    elif count < expect:

        # Incomplete

        return count

def object_to_dict(attrnames, obj):

    """

    Convert an object into a dictionary. This takes a shallow copy of the

    object.

    attrnames: Set (or iterable) of names of attributes to be copied into the

        dictionary. (We don't auto-lookup, because this function needs to be

        used on magical objects).

    """

    return dict((k, getattr(obj, k))

        for k in attrnames if not k.startswith('_'))