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"""
fs.wrapfs.readonlyfs
====================
An FS wrapper class for blocking operations that would modify the FS.
"""
from fs.base import NoDefaultMeta
from fs.wrapfs import WrapFS
from fs.errors import UnsupportedError, NoSysPathError
class ReadOnlyFS(WrapFS):
""" Makes a FS object read only. Any operation that could potentially modify
the underlying file system will throw an UnsupportedError
Note that this isn't a secure sandbox, untrusted code could work around the
read-only restrictions by getting the base class. Its main purpose is to
provide a degree of safety if you want to protect an FS object from
accidental modification.
"""
def getmeta(self, meta_name, default=NoDefaultMeta):
if meta_name == 'read_only':
return True
return self.wrapped_fs.getmeta(meta_name, default)
def hasmeta(self, meta_name):
if meta_name == 'read_only':
return True
return self.wrapped_fs.hasmeta(meta_name)
def getsyspath(self, path, allow_none=False):
""" Doesn't technically modify the filesystem but could be used to work
around read-only restrictions. """
if allow_none:
return None
raise NoSysPathError(path)
def open(self, path, mode='r', **kwargs):
""" Only permit read access """
if 'w' in mode or 'a' in mode or '+' in mode:
raise UnsupportedError('write')
return super(ReadOnlyFS, self).open(path, mode, **kwargs)
def _no_can_do(self, *args, **kwargs):
""" Replacement method for methods that can modify the file system """
raise UnsupportedError('write')
move = _no_can_do
movedir = _no_can_do
copy = _no_can_do
copydir = _no_can_do
makedir = _no_can_do
rename = _no_can_do
setxattr = _no_can_do
delxattr = _no_can_do
remove = _no_can_do
removedir = _no_can_do
settimes = _no_can_do
setcontents = _no_can_do
createfile = _no_can_do
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