Support filesystem notification through inotify on GNU/Linux.

 configure.ac (inotify): New option.
 (HAVE_INOTIFY): Test for inotify.

 src/termhooks.h (enum event_kind) [HAVE_INOTIFY]: Add
 FILE_NOTIFY_EVENT.
 src/lisp.h (syms_of_inotify) [HAVE_INOTIFY]: Add prototype.
 src/keyboard.c (Qfile_inotify) [HAVE_INOTIFY]: New variable.
 (syms_of_keyboard): DEFSYM it.
 (kbd_buffer_get_event) [HAVE_INOTIFY]: Generate FILE_NOTIFY_EVENT.
 (make_lispy_event): Support FILE_NOTIFY_EVENT by generating
 Qfile_inotify events.
 (keys_of_keyboard) [HAVE_INOTIFY]: Bind file-inotify events in
 special-event-map to inotify-handle-event.
 src/emacs.c (main) [HAVE_INOTIFY]: Call syms_of_inotify.
 src/Makefile.in (base_obj): Add inotify.o.
 src/inotify.c: New file.

 lisp/subr.el (inotify-event-p, inotify-handle-event): New functions.

 test/automated/inotify-test.el: New test.

2 files changed, 24 insertions, 0 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 787bfb7563b..1e65aa3a089 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2012-12-10  Rüdiger Sonderfeld  <ruediger@c-plusplus.de>
+
+        * subr.el (inotify-event-p, inotify-handle-event): New functions.
+
 2012-12-10  Dani Moncayo <dmoncayo@gmail.com>
 
         * simple.el (just-one-space): Doc fix.
diff --git a/lisp/subr.el b/lisp/subr.el
index e08277370a9..4f2e8f22bfe 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -4323,6 +4323,26 @@ convenience wrapper around `make-progress-reporter' and friends.
        nil ,@(cdr (cdr spec)))))
 
 
+;;;; Support for watching filesystem events.
+
+(defun inotify-event-p (event)
+  "Check if EVENT is an inotify event."
+  (and (listp event)
+       (>= (length event) 3)
+       (eq (car event) 'file-inotify)))
+
+;;;###autoload
+(defun inotify-handle-event (event)
+  "Handle file system monitoring event.
+If EVENT is a filewatch event then the callback is called.  If EVENT is
+not a filewatch event then a `filewatch-error' is signaled."
+  (interactive "e")
+  (unless (inotify-event-p event)
+    (signal 'filewatch-error (cons "Not a valid inotify event" event)))
+
+  (funcall (nth 2 event) (nth 1 event)))
+
+
 ;;;; Comparing version strings.
 
 (defconst version-separator "."