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