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PlexKodiConnect/resources/lib/watchdog/observers/inotify_c.py

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# -*- coding: utf-8 -*-
#
# Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>
# Copyright 2012 Google, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import with_statement
import os
import errno
import struct
import threading
import ctypes
import ctypes.util
from functools import reduce
from ctypes import c_int, c_char_p, c_uint32
from ..utils import has_attribute
from ..utils import UnsupportedLibc
def _load_libc():
libc_path = None
try:
libc_path = ctypes.util.find_library('c')
except (OSError, IOError, RuntimeError):
# Note: find_library will on some platforms raise these undocumented
# errors, e.g.on android IOError "No usable temporary directory found"
# will be raised.
pass
if libc_path is not None:
return ctypes.CDLL(libc_path)
# Fallbacks
try:
return ctypes.CDLL('libc.so')
except (OSError, IOError):
return ctypes.CDLL('libc.so.6')
libc = _load_libc()
if not has_attribute(libc, 'inotify_init') or \
not has_attribute(libc, 'inotify_add_watch') or \
not has_attribute(libc, 'inotify_rm_watch'):
raise UnsupportedLibc("Unsupported libc version found: %s" % libc._name)
inotify_add_watch = ctypes.CFUNCTYPE(c_int, c_int, c_char_p, c_uint32, use_errno=True)(
("inotify_add_watch", libc))
inotify_rm_watch = ctypes.CFUNCTYPE(c_int, c_int, c_uint32, use_errno=True)(
("inotify_rm_watch", libc))
inotify_init = ctypes.CFUNCTYPE(c_int, use_errno=True)(
("inotify_init", libc))
class InotifyConstants(object):
# User-space events
IN_ACCESS = 0x00000001 # File was accessed.
IN_MODIFY = 0x00000002 # File was modified.
IN_ATTRIB = 0x00000004 # Meta-data changed.
IN_CLOSE_WRITE = 0x00000008 # Writable file was closed.
IN_CLOSE_NOWRITE = 0x00000010 # Unwritable file closed.
IN_OPEN = 0x00000020 # File was opened.
IN_MOVED_FROM = 0x00000040 # File was moved from X.
IN_MOVED_TO = 0x00000080 # File was moved to Y.
IN_CREATE = 0x00000100 # Subfile was created.
IN_DELETE = 0x00000200 # Subfile was deleted.
IN_DELETE_SELF = 0x00000400 # Self was deleted.
IN_MOVE_SELF = 0x00000800 # Self was moved.
# Helper user-space events.
IN_CLOSE = IN_CLOSE_WRITE | IN_CLOSE_NOWRITE # Close.
IN_MOVE = IN_MOVED_FROM | IN_MOVED_TO # Moves.
# Events sent by the kernel to a watch.
IN_UNMOUNT = 0x00002000 # Backing file system was unmounted.
IN_Q_OVERFLOW = 0x00004000 # Event queued overflowed.
IN_IGNORED = 0x00008000 # File was ignored.
# Special flags.
IN_ONLYDIR = 0x01000000 # Only watch the path if it's a directory.
IN_DONT_FOLLOW = 0x02000000 # Do not follow a symbolic link.
IN_EXCL_UNLINK = 0x04000000 # Exclude events on unlinked objects
IN_MASK_ADD = 0x20000000 # Add to the mask of an existing watch.
IN_ISDIR = 0x40000000 # Event occurred against directory.
IN_ONESHOT = 0x80000000 # Only send event once.
# All user-space events.
IN_ALL_EVENTS = reduce(
lambda x, y: x | y, [
IN_ACCESS,
IN_MODIFY,
IN_ATTRIB,
IN_CLOSE_WRITE,
IN_CLOSE_NOWRITE,
IN_OPEN,
IN_MOVED_FROM,
IN_MOVED_TO,
IN_DELETE,
IN_CREATE,
IN_DELETE_SELF,
IN_MOVE_SELF,
])
# Flags for ``inotify_init1``
IN_CLOEXEC = 0x02000000
IN_NONBLOCK = 0x00004000
# Watchdog's API cares only about these events.
WATCHDOG_ALL_EVENTS = reduce(
lambda x, y: x | y, [
InotifyConstants.IN_MODIFY,
InotifyConstants.IN_ATTRIB,
InotifyConstants.IN_MOVED_FROM,
InotifyConstants.IN_MOVED_TO,
InotifyConstants.IN_CREATE,
InotifyConstants.IN_DELETE,
InotifyConstants.IN_DELETE_SELF,
InotifyConstants.IN_DONT_FOLLOW,
])
class inotify_event_struct(ctypes.Structure):
"""
Structure representation of the inotify_event structure
(used in buffer size calculations)::
struct inotify_event {
__s32 wd; /* watch descriptor */
__u32 mask; /* watch mask */
__u32 cookie; /* cookie to synchronize two events */
__u32 len; /* length (including nulls) of name */
char name[0]; /* stub for possible name */
};
"""
_fields_ = [('wd', c_int),
('mask', c_uint32),
('cookie', c_uint32),
('len', c_uint32),
('name', c_char_p)]
EVENT_SIZE = ctypes.sizeof(inotify_event_struct)
DEFAULT_NUM_EVENTS = 2048
DEFAULT_EVENT_BUFFER_SIZE = DEFAULT_NUM_EVENTS * (EVENT_SIZE + 16)
class Inotify(object):
"""
Linux inotify(7) API wrapper class.
:param path:
The directory path for which we want an inotify object.
:type path:
:class:`bytes`
:param recursive:
``True`` if subdirectories should be monitored; ``False`` otherwise.
"""
def __init__(self, path, recursive=False, event_mask=WATCHDOG_ALL_EVENTS):
# The file descriptor associated with the inotify instance.
inotify_fd = inotify_init()
if inotify_fd == -1:
Inotify._raise_error()
self._inotify_fd = inotify_fd
self._lock = threading.Lock()
# Stores the watch descriptor for a given path.
self._wd_for_path = dict()
self._path_for_wd = dict()
self._path = path
self._event_mask = event_mask
self._is_recursive = recursive
self._add_dir_watch(path, recursive, event_mask)
self._moved_from_events = dict()
@property
def event_mask(self):
"""The event mask for this inotify instance."""
return self._event_mask
@property
def path(self):
"""The path associated with the inotify instance."""
return self._path
@property
def is_recursive(self):
"""Whether we are watching directories recursively."""
return self._is_recursive
@property
def fd(self):
"""The file descriptor associated with the inotify instance."""
return self._inotify_fd
def clear_move_records(self):
"""Clear cached records of MOVED_FROM events"""
self._moved_from_events = dict()
def source_for_move(self, destination_event):
"""
The source path corresponding to the given MOVED_TO event.
If the source path is outside the monitored directories, None
is returned instead.
"""
if destination_event.cookie in self._moved_from_events:
return self._moved_from_events[destination_event.cookie].src_path
else:
return None
def remember_move_from_event(self, event):
"""
Save this event as the source event for future MOVED_TO events to
reference.
"""
self._moved_from_events[event.cookie] = event
def add_watch(self, path):
"""
Adds a watch for the given path.
:param path:
Path to begin monitoring.
"""
with self._lock:
self._add_watch(path, self._event_mask)
def remove_watch(self, path):
"""
Removes a watch for the given path.
:param path:
Path string for which the watch will be removed.
"""
with self._lock:
wd = self._wd_for_path.pop(path)
del self._path_for_wd[wd]
if inotify_rm_watch(self._inotify_fd, wd) == -1:
Inotify._raise_error()
def close(self):
"""
Closes the inotify instance and removes all associated watches.
"""
with self._lock:
if self._path in self._wd_for_path:
wd = self._wd_for_path[self._path]
inotify_rm_watch(self._inotify_fd, wd)
os.close(self._inotify_fd)
def read_events(self, event_buffer_size=DEFAULT_EVENT_BUFFER_SIZE):
"""
Reads events from inotify and yields them.
"""
# HACK: We need to traverse the directory path
# recursively and simulate events for newly
# created subdirectories/files. This will handle
# mkdir -p foobar/blah/bar; touch foobar/afile
def _recursive_simulate(src_path):
events = []
for root, dirnames, filenames in os.walk(src_path):
for dirname in dirnames:
try:
full_path = os.path.join(root, dirname)
wd_dir = self._add_watch(full_path, self._event_mask)
e = InotifyEvent(
wd_dir, InotifyConstants.IN_CREATE | InotifyConstants.IN_ISDIR, 0, dirname, full_path)
events.append(e)
except OSError:
pass
for filename in filenames:
full_path = os.path.join(root, filename)
wd_parent_dir = self._wd_for_path[os.path.dirname(full_path)]
e = InotifyEvent(
wd_parent_dir, InotifyConstants.IN_CREATE, 0, filename, full_path)
events.append(e)
return events
event_buffer = None
while True:
try:
event_buffer = os.read(self._inotify_fd, event_buffer_size)
except OSError as e:
if e.errno == errno.EINTR:
continue
break
with self._lock:
event_list = []
for wd, mask, cookie, name in Inotify._parse_event_buffer(event_buffer):
if wd == -1:
continue
wd_path = self._path_for_wd[wd]
src_path = os.path.join(wd_path, name) if name else wd_path #avoid trailing slash
inotify_event = InotifyEvent(wd, mask, cookie, name, src_path)
if inotify_event.is_moved_from:
self.remember_move_from_event(inotify_event)
elif inotify_event.is_moved_to:
move_src_path = self.source_for_move(inotify_event)
if move_src_path in self._wd_for_path:
moved_wd = self._wd_for_path[move_src_path]
del self._wd_for_path[move_src_path]
self._wd_for_path[inotify_event.src_path] = moved_wd
self._path_for_wd[moved_wd] = inotify_event.src_path
src_path = os.path.join(wd_path, name)
inotify_event = InotifyEvent(wd, mask, cookie, name, src_path)
if inotify_event.is_ignored:
# Clean up book-keeping for deleted watches.
path = self._path_for_wd.pop(wd)
if self._wd_for_path[path] == wd:
del self._wd_for_path[path]
continue
event_list.append(inotify_event)
if (self.is_recursive and inotify_event.is_directory and
inotify_event.is_create):
# TODO: When a directory from another part of the
# filesystem is moved into a watched directory, this
# will not generate events for the directory tree.
# We need to coalesce IN_MOVED_TO events and those
# IN_MOVED_TO events which don't pair up with
# IN_MOVED_FROM events should be marked IN_CREATE
# instead relative to this directory.
try:
self._add_watch(src_path, self._event_mask)
except OSError:
continue
event_list.extend(_recursive_simulate(src_path))
return event_list
# Non-synchronized methods.
def _add_dir_watch(self, path, recursive, mask):
"""
Adds a watch (optionally recursively) for the given directory path
to monitor events specified by the mask.
:param path:
Path to monitor
:param recursive:
``True`` to monitor recursively.
:param mask:
Event bit mask.
"""
if not os.path.isdir(path):
raise OSError('Path is not a directory')
self._add_watch(path, mask)
if recursive:
for root, dirnames, _ in os.walk(path):
for dirname in dirnames:
full_path = os.path.join(root, dirname)
if os.path.islink(full_path):
continue
self._add_watch(full_path, mask)
def _add_watch(self, path, mask):
"""
Adds a watch for the given path to monitor events specified by the
mask.
:param path:
Path to monitor
:param mask:
Event bit mask.
"""
wd = inotify_add_watch(self._inotify_fd, path, mask)
if wd == -1:
Inotify._raise_error()
self._wd_for_path[path] = wd
self._path_for_wd[wd] = path
return wd
@staticmethod
def _raise_error():
"""
Raises errors for inotify failures.
"""
err = ctypes.get_errno()
if err == errno.ENOSPC:
raise OSError("inotify watch limit reached")
elif err == errno.EMFILE:
raise OSError("inotify instance limit reached")
else:
raise OSError(os.strerror(err))
@staticmethod
def _parse_event_buffer(event_buffer):
"""
Parses an event buffer of ``inotify_event`` structs returned by
inotify::
struct inotify_event {
__s32 wd; /* watch descriptor */
__u32 mask; /* watch mask */
__u32 cookie; /* cookie to synchronize two events */
__u32 len; /* length (including nulls) of name */
char name[0]; /* stub for possible name */
};
The ``cookie`` member of this struct is used to pair two related
events, for example, it pairs an IN_MOVED_FROM event with an
IN_MOVED_TO event.
"""
i = 0
while i + 16 <= len(event_buffer):
wd, mask, cookie, length = struct.unpack_from('iIII', event_buffer, i)
name = event_buffer[i + 16:i + 16 + length].rstrip(b'\0')
i += 16 + length
yield wd, mask, cookie, name
class InotifyEvent(object):
"""
Inotify event struct wrapper.
:param wd:
Watch descriptor
:param mask:
Event mask
:param cookie:
Event cookie
:param name:
Event name.
:param src_path:
Event source path
"""
def __init__(self, wd, mask, cookie, name, src_path):
self._wd = wd
self._mask = mask
self._cookie = cookie
self._name = name
self._src_path = src_path
@property
def src_path(self):
return self._src_path
@property
def wd(self):
return self._wd
@property
def mask(self):
return self._mask
@property
def cookie(self):
return self._cookie
@property
def name(self):
return self._name
@property
def is_modify(self):
return self._mask & InotifyConstants.IN_MODIFY > 0
@property
def is_close_write(self):
return self._mask & InotifyConstants.IN_CLOSE_WRITE > 0
@property
def is_close_nowrite(self):
return self._mask & InotifyConstants.IN_CLOSE_NOWRITE > 0
@property
def is_access(self):
return self._mask & InotifyConstants.IN_ACCESS > 0
@property
def is_delete(self):
return self._mask & InotifyConstants.IN_DELETE > 0
@property
def is_delete_self(self):
return self._mask & InotifyConstants.IN_DELETE_SELF > 0
@property
def is_create(self):
return self._mask & InotifyConstants.IN_CREATE > 0
@property
def is_moved_from(self):
return self._mask & InotifyConstants.IN_MOVED_FROM > 0
@property
def is_moved_to(self):
return self._mask & InotifyConstants.IN_MOVED_TO > 0
@property
def is_move(self):
return self._mask & InotifyConstants.IN_MOVE > 0
@property
def is_move_self(self):
return self._mask & InotifyConstants.IN_MOVE_SELF > 0
@property
def is_attrib(self):
return self._mask & InotifyConstants.IN_ATTRIB > 0
@property
def is_ignored(self):
return self._mask & InotifyConstants.IN_IGNORED > 0
@property
def is_directory(self):
# It looks like the kernel does not provide this information for
# IN_DELETE_SELF and IN_MOVE_SELF. In this case, assume it's a dir.
# See also: https://github.com/seb-m/pyinotify/blob/2c7e8f8/python2/pyinotify.py#L897
return (self.is_delete_self or self.is_move_self or
self._mask & InotifyConstants.IN_ISDIR > 0)
@property
def key(self):
return self._src_path, self._wd, self._mask, self._cookie, self._name
def __eq__(self, inotify_event):
return self.key == inotify_event.key
def __ne__(self, inotify_event):
return self.key == inotify_event.key
def __hash__(self):
return hash(self.key)
@staticmethod
def _get_mask_string(mask):
masks = []
for c in dir(InotifyConstants):
if c.startswith('IN_') and c not in ['IN_ALL_EVENTS', 'IN_CLOSE', 'IN_MOVE']:
c_val = getattr(InotifyConstants, c)
if mask & c_val:
masks.append(c)
mask_string = '|'.join(masks)
return mask_string
def __repr__(self):
mask_string = self._get_mask_string(self.mask)
s = "<InotifyEvent: src_path=%s, wd=%d, mask=%s, cookie=%d, name=%s>"
return s % (self.src_path, self.wd, mask_string, self.cookie, self.name)
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