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MountFS fixes #487

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MountFS fixes #487

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58 changes: 46 additions & 12 deletions fs/mountfs.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,10 @@
from .base import FS
from .memoryfs import MemoryFS
from .path import abspath
from .path import dirname
from .path import forcedir
from .path import normpath
from .path import recursepath
from .mode import validate_open_mode
from .mode import validate_openbin_mode

Expand All @@ -23,10 +25,10 @@
Any,
BinaryIO,
Collection,
Dict,
Iterator,
IO,
List,
MutableSequence,
Optional,
Text,
Tuple,
Expand Down Expand Up @@ -67,7 +69,7 @@ def __init__(self, auto_close=True):
super(MountFS, self).__init__()
self.auto_close = auto_close
self.default_fs = MemoryFS() # type: FS
self.mounts = [] # type: MutableSequence[Tuple[Text, FS]]
self.mounts = {} # type: Dict[Text, FS]
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I think the reason a list was in use here was to preserve ordering of mounted files. Sure, a dict is fine for newer Python versions but I'd think this would change behaviour on Python 2.7. I think using collections.OrderedDict would work instead (and we can drop that when we move the code to PyFilesystem3).


def __repr__(self):
# type: () -> str
Expand All @@ -85,19 +87,26 @@ def _delegate(self, path):
path (str): A path.

Returns:
(FS, str): a tuple of ``(<fs>, <path>)`` for a mounted filesystem,
or ``(None, None)`` if no filesystem is mounted on the
(FS, str): a tuple of ``(<fs>, <path>)`` for a mounted filesystem.
Raises ``ResourceNotFound`` if no filesystem is mounted on the
given ``path``.

"""
_path = forcedir(abspath(normpath(path)))
is_mounted = _path.startswith

for mount_path, fs in self.mounts:
if _path == "/":
return self.default_fs, path

for mount_path in self.mounts:
if is_mounted(mount_path):
return fs, _path[len(mount_path) :].rstrip("/")
return self.mounts[mount_path], _path[len(mount_path) :].rstrip("/")

for mount_path in self.mounts:
if mount_path.startswith(_path):
return self.default_fs, path

return self.default_fs, path
raise errors.ResourceNotFound(path)

def mount(self, path, fs):
# type: (Text, Union[FS, Text]) -> None
Expand All @@ -120,28 +129,53 @@ def mount(self, path, fs):
raise ValueError("Unable to mount self")
_path = forcedir(abspath(normpath(path)))

for mount_path, _ in self.mounts:
if _path == "/":
raise MountError("mount point can't be empty")

for mount_path in self.mounts:
if _path.startswith(mount_path):
raise MountError("mount point overlaps existing mount")

self.mounts.append((_path, fs))
self.mounts[_path] = fs
self.default_fs.makedirs(_path, recreate=True)

def unmount(self, path):
# type: (Text) -> None
"""Unmounts a previously-mounted FS.

Arguments:
path (str): A mount-path previously used with ``mount``.

"""
_path = forcedir(abspath(normpath(path)))
if _path not in self.mounts:
raise ValueError("not a current mount point")

if self.auto_close:
self.mounts[_path].close()
del self.mounts[_path]
self.default_fs.removedir(_path)
for parent in recursepath(dirname(_path.rstrip("/")), reverse=True):
if parent == "/" or not self.default_fs.isempty(parent):
break
else:
self.default_fs.removedir(parent)

def close(self):
# type: () -> None
# Explicitly closes children if requested
if self.auto_close:
for _path, fs in self.mounts:
for fs in self.mounts.values():
fs.close()
del self.mounts[:]
self.mounts.clear()
self.default_fs.close()
super(MountFS, self).close()

def desc(self, path):
# type: (Text) -> Text
fs, delegate_path = self._delegate(path)
if not self.exists(path):
raise errors.ResourceNotFound(path)
fs, delegate_path = self._delegate(path)
if fs is self.default_fs:
fs = self
return "{path} on {fs}".format(fs=fs, path=delegate_path)
Expand Down
88 changes: 77 additions & 11 deletions tests/test_mountfs.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

import unittest

from fs.errors import ResourceNotFound
from fs.mountfs import MountError, MountFS
from fs.memoryfs import MemoryFS
from fs.tempfs import TempFS
Expand All @@ -11,16 +12,6 @@
class TestMountFS(FSTestCases, unittest.TestCase):
"""Test OSFS implementation."""

def make_fs(self):
fs = MountFS()
mem_fs = MemoryFS()
fs.mount("/", mem_fs)
return fs


class TestMountFS2(FSTestCases, unittest.TestCase):
"""Test OSFS implementation."""

def make_fs(self):
fs = MountFS()
mem_fs = MemoryFS()
Expand All @@ -35,21 +26,44 @@ def test_bad_mount(self):
mount_fs.mount("foo", 5)
with self.assertRaises(TypeError):
mount_fs.mount("foo", b"bar")
m1 = MemoryFS()
with self.assertRaises(MountError):
mount_fs.mount("", m1)
with self.assertRaises(MountError):
mount_fs.mount("/", m1)

def test_listdir(self):
mount_fs = MountFS()
self.assertEqual(mount_fs.listdir("/"), [])
m1 = MemoryFS()
m3 = MemoryFS()
m4 = TempFS()
m5 = MemoryFS()
mount_fs.mount("/m1", m1)
mount_fs.mount("/m2", "temp://")
mount_fs.mount("/m3", m3)
with self.assertRaises(MountError):
mount_fs.mount("/m3/foo", m4)
self.assertEqual(sorted(mount_fs.listdir("/")), ["m1", "m2", "m3"])
mount_fs.makedir("/m2/foo")
self.assertEqual(sorted(mount_fs.listdir("/m2")), ["foo"])
m3.makedir("foo")
self.assertEqual(sorted(mount_fs.listdir("/m3")), ["foo"])
mount_fs.mount("/subdir/m4", m4)
self.assertEqual(sorted(mount_fs.listdir("/")), ["m1", "m2", "m3", "subdir"])
self.assertEqual(mount_fs.listdir("/subdir"), ["m4"])
self.assertEqual(mount_fs.listdir("/subdir/m4"), [])
mount_fs.mount("/subdir/m5", m5)
self.assertEqual(sorted(mount_fs.listdir("/subdir")), ["m4", "m5"])
self.assertEqual(mount_fs.listdir("/subdir/m5"), [])
mount_fs.makedir("/subdir/m4/foo")
mount_fs.makedir("/subdir/m5/bar")
self.assertEqual(mount_fs.listdir("/subdir/m4"), ["foo"])
self.assertEqual(mount_fs.listdir("/subdir/m5"), ["bar"])
self.assertEqual(m4.listdir("/"), ["foo"])
self.assertEqual(m5.listdir("/"), ["bar"])
m5.removedir("/bar")
self.assertEqual(mount_fs.listdir("/subdir/m5"), [])

def test_auto_close(self):
"""Test MountFS auto close is working"""
Expand Down Expand Up @@ -85,8 +99,60 @@ def test_empty(self):
def test_mount_self(self):
mount_fs = MountFS()
with self.assertRaises(ValueError):
mount_fs.mount("/", mount_fs)
mount_fs.mount("/m1", mount_fs)

def test_desc(self):
mount_fs = MountFS()
mount_fs.desc("/")

def test_makedirs(self):
mount_fs = MountFS()
with self.assertRaises(ResourceNotFound):
mount_fs.makedir("empty")
m1 = MemoryFS()
m2 = MemoryFS()
with self.assertRaises(ResourceNotFound):
mount_fs.makedirs("/m1/foo/bar", recreate=True)
mount_fs.mount("/m1", m1)
mount_fs.makedirs("/m1/foo/bar", recreate=True)
self.assertEqual(m1.listdir("foo"), ["bar"])
with self.assertRaises(ResourceNotFound):
mount_fs.makedirs("/subdir/m2/bar/foo", recreate=True)
mount_fs.mount("/subdir/m2", m2)
mount_fs.makedirs("/subdir/m2/bar/foo", recreate=True)
self.assertEqual(m2.listdir("bar"), ["foo"])
with self.assertRaises(ResourceNotFound):
mount_fs.makedir("/subdir/m3", recreate=True)

def test_unmount(self):
mount_fs = MountFS()
m1 = MemoryFS()
m2 = MemoryFS()
m3 = MemoryFS()
m4 = MemoryFS()
mount_fs.mount("/m1", m1)
with self.assertRaises(ValueError):
mount_fs.unmount("/m2")
mount_fs.mount("/m2", m2)
self.assertEqual(sorted(mount_fs.listdir("/")), ["m1", "m2"])
mount_fs.unmount("/m1")
with self.assertRaises(ResourceNotFound):
mount_fs.listdir("/m1")
self.assertEqual(mount_fs.listdir("/"), ["m2"])
with self.assertRaises(ValueError):
mount_fs.unmount("/m1")
mount_fs.mount("/subdir/m3", m3)
with self.assertRaises(ValueError):
mount_fs.unmount("/subdir")
mount_fs.mount("/subdir/m4", m4)
self.assertEqual(sorted(mount_fs.listdir("/")), ["m2", "subdir"])
mount_fs.makedir("/subdir/m4/foo")
with self.assertRaises(ValueError):
mount_fs.unmount("/subdir/m4/foo")
mount_fs.unmount("/subdir/m4")
self.assertEqual(sorted(mount_fs.listdir("/")), ["m2", "subdir"])
self.assertEqual(mount_fs.listdir("/subdir"), ["m3"])
mount_fs.unmount("/subdir/m3")
self.assertEqual(mount_fs.listdir("/"), ["m2"])
with self.assertRaises(ResourceNotFound):
mount_fs.listdir("/subdir")