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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: util
# Author: Matt Giuca
# Date: 12/12/2007
# Contains common utility functions.
import os
import datetime
import ivle.conf
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 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 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('_'))
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