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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 sys
import stat
class IVLEError(Exception):
"""Legacy general IVLE exception.
This is the old "standard" exception class for IVLE errors. It is only
used in fileservice, and should not be used in any new code.
"""
message = None
def __init__(self, httpcode, message=None):
self.httpcode = httpcode
self.message = message
self.args = (httpcode, message)
class IVLEJailError(Exception):
"""Exception proxying an in-jail error.
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 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 relpath(path, start=os.path.curdir):
"""Return a relative version of a path.
XXX Backported from Python 2.6 posixpath.py.
"""
if not path:
raise ValueError("no path specified")
start_list = os.path.abspath(start).split(os.path.sep)
path_list = os.path.abspath(path).split(os.path.sep)
# Work out how much of the filepath is shared by start and path.
i = len(os.path.commonprefix([start_list, path_list]))
rel_list = [os.path.pardir] * (len(start_list)-i) + path_list[i:]
if not rel_list:
return os.path.curdir
return os.path.join(*rel_list)
def incomplete_utf8_sequence(byteseq):
"""Calculate the completeness of a UTF-8 encoded string.
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 safe_rmtree(path, ignore_errors=False, onerror=None):
"""Recursively delete a directory tree.
Copied from shutil.rmtree from Python 2.6, which does not follow symbolic
links (it is otherwise unsafe to call as root on untrusted directories; do
not use shutil.rmtree in this case, as you may be running Python 2.5).
If ignore_errors is set, errors are ignored; otherwise, if onerror
is set, it is called to handle the error with arguments (func,
path, exc_info) where func is os.listdir, os.remove, or os.rmdir;
path is the argument to that function that caused it to fail; and
exc_info is a tuple returned by sys.exc_info(). If ignore_errors
is false and onerror is None, an exception is raised.
"""
if ignore_errors:
def onerror(*args):
pass
elif onerror is None:
def onerror(*args):
raise
try:
if os.path.islink(path):
# symlinks to directories are forbidden, see bug #1669
raise OSError("Cannot call safe_rmtree on a symbolic link")
except OSError:
onerror(os.path.islink, path, sys.exc_info())
# can't continue even if onerror hook returns
return
names = []
try:
names = os.listdir(path)
except os.error, err:
onerror(os.listdir, path, sys.exc_info())
for name in names:
fullname = os.path.join(path, name)
try:
mode = os.lstat(fullname).st_mode
except os.error:
mode = 0
if stat.S_ISDIR(mode):
safe_rmtree(fullname, ignore_errors, onerror)
else:
try:
os.remove(fullname)
except os.error, err:
onerror(os.remove, fullname, sys.exc_info())
try:
os.rmdir(path)
except os.error:
onerror(os.rmdir, path, sys.exc_info())
def format_submission_principal(user, principal):
"""Render a list of users to fit in the offering project listing.
Given a user and a list of submitters, returns 'solo' if the
only submitter is the user, or a string of the form
'with A, B and C' if there are any other submitters.
If submitters is None, we assume that the list of members could
not be determined, so we just return 'group'.
"""
if principal is None:
return 'group'
if principal is user:
return 'solo'
display_names = sorted(
member.display_name for member in principal.members
if member is not user)
if len(display_names) == 0:
return 'solo (%s)' % principal.name
elif len(display_names) == 1:
return 'with %s (%s)' % (display_names[0], principal.name)
elif len(display_names) > 5:
return 'with %d others (%s)' % (len(display_names), principal.name)
else:
return 'with %s and %s (%s)' % (', '.join(display_names[:-1]),
display_names[-1], principal.name)
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