CasperSecurity
# -*- Mode: Python -*-
# $Id: filesys.py,v 1.9 2003/12/24 16:10:56 akuchling Exp $
# Author: Sam Rushing <rushing@nightmare.com>
#
# Generic filesystem interface.
#
# We want to provide a complete wrapper around any and all
# filesystem operations.
# this class is really just for documentation,
# identifying the API for a filesystem object.
# opening files for reading, and listing directories, should
# return a producer.
from supervisor.compat import long
class abstract_filesystem:
def __init__ (self):
pass
def current_directory (self):
"""Return a string representing the current directory."""
pass
def listdir (self, path, long=0):
"""Return a listing of the directory at 'path' The empty string
indicates the current directory. If 'long' is set, instead
return a list of (name, stat_info) tuples
"""
pass
def open (self, path, mode):
"""Return an open file object"""
pass
def stat (self, path):
"""Return the equivalent of os.stat() on the given path."""
pass
def isdir (self, path):
"""Does the path represent a directory?"""
pass
def isfile (self, path):
"""Does the path represent a plain file?"""
pass
def cwd (self, path):
"""Change the working directory."""
pass
def cdup (self):
"""Change to the parent of the current directory."""
pass
def longify (self, path):
"""Return a 'long' representation of the filename
[for the output of the LIST command]"""
pass
# standard wrapper around a unix-like filesystem, with a 'false root'
# capability.
# security considerations: can symbolic links be used to 'escape' the
# root? should we allow it? if not, then we could scan the
# filesystem on startup, but that would not help if they were added
# later. We will probably need to check for symlinks in the cwd method.
# what to do if wd is an invalid directory?
import os
import stat
import re
def safe_stat (path):
try:
return path, os.stat (path)
except:
return None
class os_filesystem:
path_module = os.path
# set this to zero if you want to disable pathname globbing.
# [we currently don't glob, anyway]
do_globbing = 1
def __init__ (self, root, wd='/'):
self.root = root
self.wd = wd
def current_directory (self):
return self.wd
def isfile (self, path):
p = self.normalize (self.path_module.join (self.wd, path))
return self.path_module.isfile (self.translate(p))
def isdir (self, path):
p = self.normalize (self.path_module.join (self.wd, path))
return self.path_module.isdir (self.translate(p))
def cwd (self, path):
p = self.normalize (self.path_module.join (self.wd, path))
translated_path = self.translate(p)
if not self.path_module.isdir (translated_path):
return 0
else:
old_dir = os.getcwd()
# temporarily change to that directory, in order
# to see if we have permission to do so.
can = 0
try:
try:
os.chdir (translated_path)
can = 1
self.wd = p
except:
pass
finally:
if can:
os.chdir (old_dir)
return can
def cdup (self):
return self.cwd ('..')
def listdir (self, path, long=0):
p = self.translate (path)
# I think we should glob, but limit it to the current
# directory only.
ld = os.listdir (p)
if not long:
return list_producer (ld, None)
else:
old_dir = os.getcwd()
try:
os.chdir (p)
# if os.stat fails we ignore that file.
result = [_f for _f in map (safe_stat, ld) if _f]
finally:
os.chdir (old_dir)
return list_producer (result, self.longify)
# TODO: implement a cache w/timeout for stat()
def stat (self, path):
p = self.translate (path)
return os.stat (p)
def open (self, path, mode):
p = self.translate (path)
return open (p, mode)
def unlink (self, path):
p = self.translate (path)
return os.unlink (p)
def mkdir (self, path):
p = self.translate (path)
return os.mkdir (p)
def rmdir (self, path):
p = self.translate (path)
return os.rmdir (p)
def rename(self, src, dst):
return os.rename(self.translate(src),self.translate(dst))
# utility methods
def normalize (self, path):
# watch for the ever-sneaky '/+' path element
path = re.sub('/+', '/', path)
p = self.path_module.normpath (path)
# remove 'dangling' cdup's.
if len(p) > 2 and p[:3] == '/..':
p = '/'
return p
def translate (self, path):
# we need to join together three separate
# path components, and do it safely.
# <real_root>/<current_directory>/<path>
# use the operating system's path separator.
path = os.sep.join(path.split('/'))
p = self.normalize (self.path_module.join (self.wd, path))
p = self.normalize (self.path_module.join (self.root, p[1:]))
return p
def longify (self, path_stat_info_tuple):
(path, stat_info) = path_stat_info_tuple
return unix_longify (path, stat_info)
def __repr__ (self):
return '<unix-style fs root:%s wd:%s>' % (
self.root,
self.wd
)
if os.name == 'posix':
class unix_filesystem (os_filesystem):
pass
class schizophrenic_unix_filesystem (os_filesystem):
PROCESS_UID = os.getuid()
PROCESS_EUID = os.geteuid()
PROCESS_GID = os.getgid()
PROCESS_EGID = os.getegid()
def __init__ (self, root, wd='/', persona=(None, None)):
os_filesystem.__init__ (self, root, wd)
self.persona = persona
def become_persona (self):
if self.persona != (None, None):
uid, gid = self.persona
# the order of these is important!
os.setegid (gid)
os.seteuid (uid)
def become_nobody (self):
if self.persona != (None, None):
os.seteuid (self.PROCESS_UID)
os.setegid (self.PROCESS_GID)
# cwd, cdup, open, listdir
def cwd (self, path):
try:
self.become_persona()
return os_filesystem.cwd (self, path)
finally:
self.become_nobody()
def cdup (self):
try:
self.become_persona()
return os_filesystem.cdup (self)
finally:
self.become_nobody()
def open (self, filename, mode):
try:
self.become_persona()
return os_filesystem.open (self, filename, mode)
finally:
self.become_nobody()
def listdir (self, path, long=0):
try:
self.become_persona()
return os_filesystem.listdir (self, path, long)
finally:
self.become_nobody()
# For the 'real' root, we could obtain a list of drives, and then
# use that. Doesn't win32 provide such a 'real' filesystem?
# [yes, I think something like this "\\.\c\windows"]
class msdos_filesystem (os_filesystem):
def longify (self, path_stat_info_tuple):
(path, stat_info) = path_stat_info_tuple
return msdos_longify (path, stat_info)
# A merged filesystem will let you plug other filesystems together.
# We really need the equivalent of a 'mount' capability - this seems
# to be the most general idea. So you'd use a 'mount' method to place
# another filesystem somewhere in the hierarchy.
# Note: this is most likely how I will handle ~user directories
# with the http server.
class merged_filesystem:
def __init__ (self, *fsys):
pass
# this matches the output of NT's ftp server (when in
# MSDOS mode) exactly.
def msdos_longify (file, stat_info):
if stat.S_ISDIR (stat_info[stat.ST_MODE]):
dir = '<DIR>'
else:
dir = ' '
date = msdos_date (stat_info[stat.ST_MTIME])
return '%s %s %8d %s' % (
date,
dir,
stat_info[stat.ST_SIZE],
file
)
def msdos_date (t):
try:
info = time.gmtime (t)
except:
info = time.gmtime (0)
# year, month, day, hour, minute, second, ...
hour = info[3]
if hour > 11:
merid = 'PM'
hour -= 12
else:
merid = 'AM'
return '%02d-%02d-%02d %02d:%02d%s' % (
info[1],
info[2],
info[0]%100,
hour,
info[4],
merid
)
months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
mode_table = {
'0':'---',
'1':'--x',
'2':'-w-',
'3':'-wx',
'4':'r--',
'5':'r-x',
'6':'rw-',
'7':'rwx'
}
import time
def unix_longify (file, stat_info):
# for now, only pay attention to the lower bits
mode = ('%o' % stat_info[stat.ST_MODE])[-3:]
mode = ''.join([mode_table[x] for x in mode])
if stat.S_ISDIR (stat_info[stat.ST_MODE]):
dirchar = 'd'
else:
dirchar = '-'
date = ls_date (long(time.time()), stat_info[stat.ST_MTIME])
return '%s%s %3d %-8d %-8d %8d %s %s' % (
dirchar,
mode,
stat_info[stat.ST_NLINK],
stat_info[stat.ST_UID],
stat_info[stat.ST_GID],
stat_info[stat.ST_SIZE],
date,
file
)
# Emulate the unix 'ls' command's date field.
# it has two formats - if the date is more than 180
# days in the past, then it's like this:
# Oct 19 1995
# otherwise, it looks like this:
# Oct 19 17:33
def ls_date (now, t):
try:
info = time.gmtime (t)
except:
info = time.gmtime (0)
# 15,600,000 == 86,400 * 180
if (now - t) > 15600000:
return '%s %2d %d' % (
months[info[1]-1],
info[2],
info[0]
)
else:
return '%s %2d %02d:%02d' % (
months[info[1]-1],
info[2],
info[3],
info[4]
)
# ===========================================================================
# Producers
# ===========================================================================
class list_producer:
def __init__ (self, list, func=None):
self.list = list
self.func = func
# this should do a pushd/popd
def more (self):
if not self.list:
return ''
else:
# do a few at a time
bunch = self.list[:50]
if self.func is not None:
bunch = map (self.func, bunch)
self.list = self.list[50:]
return '\r\n'.join(bunch) + '\r\n'