Ausgabe der neuen DB Einträge

venv/lib/python3.9/site-packages/twisted/python/_inotify.py

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+# -*- test-case-name: twisted.internet.test.test_inotify -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Very low-level ctypes-based interface to Linux inotify(7).
+
+ctypes and a version of libc which supports inotify system calls are
+required.
+"""
+
+import ctypes
+import ctypes.util
+
+
+
+class INotifyError(Exception):
+    """
+    Unify all the possible exceptions that can be raised by the INotify API.
+    """
+
+
+
+def init():
+    """
+    Create an inotify instance and return the associated file descriptor.
+    """
+    fd = libc.inotify_init()
+    if fd < 0:
+        raise INotifyError("INotify initialization error.")
+    return fd
+
+
+
+def add(fd, path, mask):
+    """
+    Add a watch for the given path to the inotify file descriptor, and return
+    the watch descriptor.
+
+    @param fd: The file descriptor returned by C{libc.inotify_init}.
+    @type fd: L{int}
+
+    @param path: The path to watch via inotify.
+    @type path: L{twisted.python.filepath.FilePath}
+
+    @param mask: Bitmask specifying the events that inotify should monitor.
+    @type mask: L{int}
+    """
+    wd = libc.inotify_add_watch(fd, path.asBytesMode().path, mask)
+    if wd < 0:
+        raise INotifyError("Failed to add watch on '%r' - (%r)" % (path, wd))
+    return wd
+
+
+
+def remove(fd, wd):
+    """
+    Remove the given watch descriptor from the inotify file descriptor.
+    """
+    # When inotify_rm_watch returns -1 there's an error:
+    # The errno for this call can be either one of the following:
+    #  EBADF: fd is not a valid file descriptor.
+    #  EINVAL: The watch descriptor wd is not valid; or fd is
+    #          not an inotify file descriptor.
+    #
+    # if we can't access the errno here we cannot even raise
+    # an exception and we need to ignore the problem, one of
+    # the most common cases is when you remove a directory from
+    # the filesystem and that directory is observed. When inotify
+    # tries to call inotify_rm_watch with a non existing directory
+    # either of the 2 errors might come up because the files inside
+    # it might have events generated way before they were handled.
+    # Unfortunately only ctypes in Python 2.6 supports accessing errno:
+    #  http://bugs.python.org/issue1798 and in order to solve
+    # the problem for previous versions we need to introduce
+    # code that is quite complex:
+    #  http://stackoverflow.com/questions/661017/access-to-errno-from-python
+    #
+    # See #4310 for future resolution of this issue.
+    libc.inotify_rm_watch(fd, wd)
+
+
+
+def initializeModule(libc):
+    """
+    Initialize the module, checking if the expected APIs exist and setting the
+    argtypes and restype for C{inotify_init}, C{inotify_add_watch}, and
+    C{inotify_rm_watch}.
+    """
+    for function in ("inotify_add_watch", "inotify_init", "inotify_rm_watch"):
+        if getattr(libc, function, None) is None:
+            raise ImportError("libc6 2.4 or higher needed")
+    libc.inotify_init.argtypes = []
+    libc.inotify_init.restype = ctypes.c_int
+
+    libc.inotify_rm_watch.argtypes = [
+        ctypes.c_int, ctypes.c_int]
+    libc.inotify_rm_watch.restype = ctypes.c_int
+
+    libc.inotify_add_watch.argtypes = [
+        ctypes.c_int, ctypes.c_char_p, ctypes.c_uint32]
+    libc.inotify_add_watch.restype = ctypes.c_int
+
+
+
+name = ctypes.util.find_library('c')
+if not name:
+    raise ImportError("Can't find C library.")
+libc = ctypes.cdll.LoadLibrary(name)
+initializeModule(libc)