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514 lines
22 KiB
EmacsLisp
514 lines
22 KiB
EmacsLisp
;;; filenotify.el --- watch files for changes on disk -*- lexical-binding:t -*-
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;; Copyright (C) 2013-2022 Free Software Foundation, Inc.
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;; Author: Michael Albinus <michael.albinus@gmx.de>
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This package is an abstraction layer from the different low-level
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;; file notification packages `inotify', `kqueue', `gfilenotify' and
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;; `w32notify'.
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;;; Code:
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(require 'cl-lib)
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(eval-when-compile (require 'subr-x))
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(defvar file-notify-debug nil
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"Use for debug messages.")
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(defconst file-notify--library
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(cond
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((featurep 'inotify) 'inotify)
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((featurep 'kqueue) 'kqueue)
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((featurep 'gfilenotify) 'gfilenotify)
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((featurep 'w32notify) 'w32notify))
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"Non-nil when Emacs has been compiled with file notification support.
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The value is the name of the low-level file notification package
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to be used for local file systems. Remote file notifications
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could use another implementation.")
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(cl-defstruct (file-notify--watch
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(:constructor nil)
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(:constructor
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file-notify--watch-make (directory filename callback)))
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"The internal struct for bookkeeping watched files or directories.
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Used in `file-notify-descriptors'."
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;; Watched directory.
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directory
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;; Watched relative filename, nil if watching the directory.
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filename
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;; Function to propagate events to, or nil if watch is being removed.
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callback)
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(defun file-notify--watch-absolute-filename (watch)
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"Return the absolute filename observed by WATCH."
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(if (file-notify--watch-filename watch)
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(expand-file-name
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(file-notify--watch-filename watch)
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(file-notify--watch-directory watch))
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(file-notify--watch-directory watch)))
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(defvar file-notify-descriptors (make-hash-table :test 'equal)
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"Hash table for registered file notification descriptors.
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A key in this hash table is the descriptor as returned from
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`inotify', `kqueue', `gfilenotify', `w32notify' or a file name
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handler. The value in the hash table is a `file-notify--watch'
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struct.")
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(defun file-notify--rm-descriptor (descriptor)
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"Remove DESCRIPTOR from `file-notify-descriptors'.
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DESCRIPTOR should be an object returned by `file-notify-add-watch'.
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If it is registered in `file-notify-descriptors', a `stopped' event is sent."
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(when-let ((watch (gethash descriptor file-notify-descriptors)))
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(unwind-protect
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;; Send `stopped' event.
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(file-notify-handle-event
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(make-file-notify
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:-event `(,descriptor stopped
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,(file-notify--watch-absolute-filename watch))
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:-callback (file-notify--watch-callback watch)))
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;; Make sure this is the last time the callback was invoked.
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(setf (file-notify--watch-callback watch) nil)
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(remhash descriptor file-notify-descriptors))))
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(cl-defstruct (file-notify (:type list) :named)
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"A file system monitoring event, coming from the backends."
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-event -callback)
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;; This function is used by `inotify', `kqueue', `gfilenotify',
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;; `w32notify' and remote file system handlers. Usually, we call the
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;; argument `event' for such handlers. But in the following, `event'
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;; means a part of the argument only, so we call the argument `object'.
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;;;###autoload
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(defun file-notify-handle-event (object)
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"Handle a file system monitoring event, coming from backends.
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If OBJECT is a filewatch event, call its callback.
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Otherwise, signal a `file-notify-error'."
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(declare (completion ignore))
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(interactive "e")
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(when file-notify-debug
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(message "file-notify-handle-event %S" object))
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(if (file-notify-p object)
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(funcall (file-notify--callback object) (file-notify--event object))
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(signal 'file-notify-error
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(cons "Not a valid file-notify-event" object))))
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(cl-defstruct (file-notify--rename
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(:constructor nil)
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(:constructor
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file-notify--rename-make (watch desc from-file cookie)))
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watch desc from-file cookie)
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(defvar file-notify--pending-rename nil
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"A pending rename event awaiting the destination file name.
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It is nil or a `file-notify--rename' defstruct where the cookie can be nil.")
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(defun file-notify--expand-file-name (watch file)
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"Full file name of FILE reported for WATCH."
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(directory-file-name
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(expand-file-name file (file-notify--watch-directory watch))))
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(cl-defun file-notify--callback-inotify ((desc actions file
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&optional file1-or-cookie))
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"Notification callback for inotify."
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(file-notify--handle-event
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desc
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(delq nil (mapcar (lambda (action)
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(cond
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((eq action 'create) 'created)
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((eq action 'modify) 'changed)
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((eq action 'attrib) 'attribute-changed)
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((memq action '(delete delete-self move-self)) 'deleted)
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((eq action 'moved-from) 'renamed-from)
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((eq action 'moved-to) 'renamed-to)
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((eq action 'ignored) 'stopped)))
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actions))
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file file1-or-cookie))
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(cl-defun file-notify--callback-kqueue ((desc actions file
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&optional file1-or-cookie))
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"Notification callback for kqueue."
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(file-notify--handle-event
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desc
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(delq nil (mapcar (lambda (action)
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(cond
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((eq action 'create) 'created)
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((eq action 'write) 'changed)
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((memq action '(attrib link)) 'attribute-changed)
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((eq action 'delete) 'deleted)
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((eq action 'rename) 'renamed)))
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actions))
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file file1-or-cookie))
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(cl-defun file-notify--callback-w32notify ((desc actions file
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&optional file1-or-cookie))
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"Notification callback for w32notify."
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(let ((action (pcase actions
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('added 'created)
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('modified 'changed)
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('removed 'deleted)
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('renamed-from 'renamed-from)
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('renamed-to 'renamed-to))))
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(when action
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(file-notify--handle-event desc (list action) file file1-or-cookie))))
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(cl-defun file-notify--callback-gfilenotify ((desc actions file
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&optional file1-or-cookie))
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"Notification callback for gfilenotify."
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(file-notify--handle-event
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desc
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(delq nil (mapcar (lambda (action)
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(cond
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((memq action
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'(created changed attribute-changed deleted))
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action)
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((eq action 'moved) 'renamed)))
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(if (consp actions) actions (list actions))))
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file file1-or-cookie))
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(cl-defun file-notify-callback ((desc actions file &optional file1-or-cookie))
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"Notification callback for file name handlers."
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(file-notify--handle-event
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desc
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;; File name handlers use gfilenotify or inotify actions.
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(delq nil (mapcar
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(lambda (action)
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(cond
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;; gfilenotify actions:
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((memq action '(created changed attribute-changed deleted))
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action)
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((eq action 'moved) 'renamed)
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;; inotify actions:
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((eq action 'create) 'created)
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((eq action 'modify) 'changed)
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((eq action 'attrib) 'attribute-changed)
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((memq action '(delete delete-self move-self)) 'deleted)
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((eq action 'moved-from) 'renamed-from)
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((eq action 'moved-to) 'renamed-to)
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((eq action 'ignored) 'stopped)))
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(if (consp actions) actions (list actions))))
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file file1-or-cookie))
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(defun file-notify--call-handler (watch desc action file file1)
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"Call the handler of WATCH with the arguments DESC, ACTION, FILE and FILE1."
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(when (or
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;; If there is no relative file name for that
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;; watch, we watch the whole directory.
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(null (file-notify--watch-filename watch))
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;; File matches.
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(string-equal
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(file-notify--watch-filename watch)
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(file-name-nondirectory file))
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;; Directory matches.
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;; FIXME: What purpose would this condition serve?
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;; Doesn't it just slip through events for files
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;; having the same name as the last component of the
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;; directory of the file that we are really watching?
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;;(string-equal
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;; (file-name-nondirectory file)
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;; (file-name-nondirectory (file-notify--watch-directory watch)))
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;; File1 matches.
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(and (stringp file1)
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(string-equal (file-notify--watch-filename watch)
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(file-name-nondirectory file1))))
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(when file-notify-debug
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(message
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"file-notify-callback %S %S %S %S %S %S %S"
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desc action file file1 watch
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(file-notify--watch-absolute-filename watch)
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(file-notify--watch-directory watch)))
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(funcall (file-notify--watch-callback watch)
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(if file1
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(list desc action file file1)
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(list desc action file)))))
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(defun file-notify--handle-event (desc actions file file1-or-cookie)
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"Handle an event returned from file notification.
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DESC is the back-end descriptor. ACTIONS is a list of:
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`created'
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`changed'
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`attribute-changed'
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`deleted'
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`renamed' -- FILE is old name, FILE1-OR-COOKIE is new name or nil
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`renamed-from' -- FILE is old name, FILE1-OR-COOKIE is cookie or nil
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`renamed-to' -- FILE is new name, FILE1-OR-COOKIE is cookie or nil
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`stopped' -- no more events after this should be sent"
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(let* ((watch (gethash desc file-notify-descriptors))
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(file (and watch (file-notify--expand-file-name watch file))))
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(when watch
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(while actions
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(let ((action (pop actions)))
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;; We only handle {renamed,moved}-{from,to} pairs when these
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;; arrive in order without anything else in-between.
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;; If there is a pending rename that does not match this event,
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;; then send the former as a deletion (since we don't know the
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;; rename destination).
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(when file-notify--pending-rename
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(unless (and (equal (file-notify--rename-cookie
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file-notify--pending-rename)
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file1-or-cookie)
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(eq action 'renamed-to))
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(let ((callback (file-notify--watch-callback
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(file-notify--rename-watch
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file-notify--pending-rename))))
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(when callback
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(funcall callback (list (file-notify--rename-desc
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file-notify--pending-rename)
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'deleted
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(file-notify--rename-from-file
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file-notify--pending-rename))))
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(setq file-notify--pending-rename nil))))
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(let ((file1 nil))
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(cond
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((eq action 'renamed)
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;; A `renamed' event may not have a destination name;
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;; if none, treat it as a deletion.
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(if file1-or-cookie
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(setq file1
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(file-notify--expand-file-name watch file1-or-cookie))
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(setq action 'deleted)))
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((eq action 'stopped)
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(file-notify-rm-watch desc)
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(setq actions nil
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action nil))
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;; Make the event pending.
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((eq action 'renamed-from)
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(setq file-notify--pending-rename
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(file-notify--rename-make watch desc file file1-or-cookie)
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action nil))
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;; Look for pending event.
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((eq action 'renamed-to)
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(if file-notify--pending-rename
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(let ((callback (file-notify--watch-callback
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(file-notify--rename-watch
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file-notify--pending-rename)))
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(pending-desc (file-notify--rename-desc
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file-notify--pending-rename))
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(from-file (file-notify--rename-from-file
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file-notify--pending-rename)))
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(setq file1 file
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file from-file)
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;; If the source is handled by another watch, we
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;; must fire the rename event there as well.
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(when (and (not (equal desc pending-desc))
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callback)
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(funcall callback
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(list pending-desc 'renamed file file1)))
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(setq file-notify--pending-rename nil
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action 'renamed))
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(setq action 'created))))
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(when action
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(file-notify--call-handler watch desc action file file1))
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;; Send `stopped' event.
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(when (and (memq action '(deleted renamed))
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;; Not when a file is backed up.
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(not (and (stringp file1) (backup-file-name-p file1)))
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;; Watched file or directory is concerned.
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(string-equal
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file (file-notify--watch-absolute-filename watch)))
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(file-notify-rm-watch desc))))))))
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(declare-function inotify-add-watch "inotify.c" (file flags callback))
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(declare-function kqueue-add-watch "kqueue.c" (file flags callback))
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(declare-function w32notify-add-watch "w32notify.c" (file flags callback))
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(declare-function gfile-add-watch "gfilenotify.c" (file flags callback))
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(defun file-notify--add-watch-inotify (_file dir flags)
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"Add a watch for FILE in DIR with FLAGS, using inotify."
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(inotify-add-watch dir
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(append
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(and (memq 'change flags)
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'(create delete delete-self modify move-self move))
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(and (memq 'attribute-change flags)
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'(attrib)))
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#'file-notify--callback-inotify))
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(defun file-notify--add-watch-kqueue (file _dir flags)
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"Add a watch for FILE in DIR with FLAGS, using kqueue."
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;; kqueue does not report changes to file contents when watching
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;; directories, so we watch each file directly.
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(kqueue-add-watch file
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(append
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(and (memq 'change flags)
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'(create delete write extend rename))
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(and (memq 'attribute-change flags)
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'(attrib)))
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#'file-notify--callback-kqueue))
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(defun file-notify--add-watch-w32notify (_file dir flags)
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"Add a watch for FILE in DIR with FLAGS, using w32notify."
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(w32notify-add-watch dir
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(append
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(and (memq 'change flags)
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'(file-name directory-name size last-write-time))
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(and (memq 'attribute-change flags)
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'(attributes)))
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#'file-notify--callback-w32notify))
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(defun file-notify--add-watch-gfilenotify (_file dir flags)
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"Add a watch for FILE in DIR with FLAGS, using gfilenotify."
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(gfile-add-watch dir
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(append '(watch-mounts send-moved) flags)
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#'file-notify--callback-gfilenotify))
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(defun file-notify-add-watch (file flags callback)
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"Add a watch for filesystem events pertaining to FILE.
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This arranges for filesystem events pertaining to FILE to be reported
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to Emacs. Use `file-notify-rm-watch' to cancel the watch.
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The returned value is a descriptor for the added watch. If the
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file cannot be watched for some reason, this function signals a
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`file-notify-error' error.
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FLAGS is a list of conditions to set what will be watched for. It can
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include the following symbols:
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`change' -- watch for file changes
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`attribute-change' -- watch for file attributes changes, like
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permissions or modification time
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If FILE is a directory, `change' watches for file creation or
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deletion in that directory. Some of the file notification
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backends report also file changes. This does not work
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recursively.
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When any event happens, Emacs will call the CALLBACK function passing
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it a single argument EVENT, which is of the form
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(DESCRIPTOR ACTION FILE [FILE1])
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DESCRIPTOR is the same object as the one returned by this function.
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ACTION is the description of the event. It could be any one of the
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following:
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`created' -- FILE was created
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`deleted' -- FILE was deleted
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`changed' -- FILE has changed
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`renamed' -- FILE has been renamed to FILE1
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`attribute-changed' -- a FILE attribute was changed
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`stopped' -- watching FILE has been stopped
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FILE is the name of the file whose event is being reported."
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;; Check arguments.
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(unless (stringp file)
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(signal 'wrong-type-argument `(,file)))
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(setq file (expand-file-name file))
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(unless (and (consp flags)
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(null (delq 'change (delq 'attribute-change (copy-tree flags)))))
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(signal 'wrong-type-argument `(,flags)))
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(unless (functionp callback)
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(signal 'wrong-type-argument `(,callback)))
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(let ((handler (find-file-name-handler file 'file-notify-add-watch))
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(dir (directory-file-name
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(if (file-directory-p file)
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file
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(file-name-directory file)))))
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(unless (file-directory-p dir)
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(signal 'file-notify-error `("Directory does not exist" ,dir)))
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(let ((desc
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(if handler
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(funcall handler 'file-notify-add-watch dir flags callback)
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(funcall
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(pcase file-notify--library
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('inotify #'file-notify--add-watch-inotify)
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('kqueue #'file-notify--add-watch-kqueue)
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('w32notify #'file-notify--add-watch-w32notify)
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('gfilenotify #'file-notify--add-watch-gfilenotify)
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(_ (signal 'file-notify-error
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'("No file notification package available"))))
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file dir flags))))
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;; Modify `file-notify-descriptors'.
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(let ((watch (file-notify--watch-make
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;; We do not want to enter quoted file names into the hash.
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(file-name-unquote dir)
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(unless (file-directory-p file)
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(file-name-nondirectory file))
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callback)))
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(puthash desc watch file-notify-descriptors))
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;; Return descriptor.
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desc)))
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(defun file-notify-rm-watch (descriptor)
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"Remove an existing watch specified by its DESCRIPTOR.
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DESCRIPTOR should be an object returned by `file-notify-add-watch'."
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(when-let* ((watch (gethash descriptor file-notify-descriptors)))
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;; If we are called from a `stopped' event, do nothing.
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(when (file-notify--watch-callback watch)
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(let ((handler (find-file-name-handler
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(file-notify--watch-directory watch)
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'file-notify-rm-watch)))
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(condition-case nil
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(if handler
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;; A file name handler could exist even if there is no
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;; local file notification support.
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(funcall handler 'file-notify-rm-watch descriptor)
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(funcall
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(cond
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((eq file-notify--library 'inotify) 'inotify-rm-watch)
|
|
((eq file-notify--library 'kqueue) 'kqueue-rm-watch)
|
|
((eq file-notify--library 'gfilenotify) 'gfile-rm-watch)
|
|
((eq file-notify--library 'w32notify) 'w32notify-rm-watch))
|
|
descriptor))
|
|
(file-notify-error nil)))
|
|
;; Modify `file-notify-descriptors' and send a `stopped' event.
|
|
(file-notify--rm-descriptor descriptor))))
|
|
|
|
(defun file-notify-valid-p (descriptor)
|
|
"Check a watch specified by its DESCRIPTOR.
|
|
DESCRIPTOR should be an object returned by `file-notify-add-watch'."
|
|
(when-let* ((watch (gethash descriptor file-notify-descriptors)))
|
|
(let ((handler (find-file-name-handler
|
|
(file-notify--watch-directory watch)
|
|
'file-notify-valid-p)))
|
|
(and (if handler
|
|
;; A file name handler could exist even if there is no
|
|
;; local file notification support.
|
|
(funcall handler 'file-notify-valid-p descriptor)
|
|
(funcall
|
|
(cond
|
|
((eq file-notify--library 'inotify) 'inotify-valid-p)
|
|
((eq file-notify--library 'kqueue) 'kqueue-valid-p)
|
|
((eq file-notify--library 'gfilenotify) 'gfile-valid-p)
|
|
((eq file-notify--library 'w32notify) 'w32notify-valid-p))
|
|
descriptor))
|
|
t))))
|
|
|
|
;; TODO:
|
|
|
|
;; * Watching a file in an already watched directory.
|
|
;; If the file is created and *then* a watch is added to that file, the
|
|
;; watch might receive events which occurred prior to it being created,
|
|
;; due to the way events are propagated during idle time. Note: This
|
|
;; may be perfectly acceptable.
|
|
|
|
(provide 'filenotify)
|
|
|
|
;;; filenotify.el ends here
|