/* Add a new watch to watch-descriptor WD watching FILENAME and using
CALLBACK. Returns a cons (DESCRIPTOR . ID) uniquely identifying the
new watch. */
static Lisp_Object
add_watch (int wd, Lisp_Object filename,
Lisp_Object aspect, Lisp_Object callback)
{
Lisp_Object descriptor = INTEGER_TO_CONS (wd);
Lisp_Object tail = assoc_no_quit (descriptor, watch_list);
Lisp_Object watch, watch_id;
uint32_t imask = aspect_to_inotifymask (aspect);
Lisp_Object mask = INTEGER_TO_CONS (imask);
EMACS_INT id = 0;
if (NILP (tail))
{
tail = list1 (descriptor);
watch_list = Fcons (tail, watch_list);
}
else
{
/* Assign a watch ID that is not already in use, by looking
for a gap in the existing sorted list. */
for (; ! NILP (XCDR (tail)); tail = XCDR (tail), id++)
if (!EQ (XCAR (XCAR (XCDR (tail))), make_number (id)))
break;
if (MOST_POSITIVE_FIXNUM < id)
emacs_abort ();
}
/* Insert the newly-assigned ID into the previously-discovered gap,
which is possibly at the end of the list. Inserting it there
keeps the list sorted. */
watch_id = make_number (id);
watch = list4 (watch_id, filename, callback, mask);
XSETCDR (tail, Fcons (watch, XCDR (tail)));
return Fcons (descriptor, watch_id);
}
See inotify(7) and inotify_add_watch(2) for further information. The
inotify fd is managed internally and there is no corresponding
inotify_init. Use `inotify-rm-watch' to remove a watch.
The following inotify bit-masks cannot be used because descriptors are
shared across different callers.
IN_EXCL_UNLINK
IN_MASK_ADD
IN_ONESHOT */)
(Lisp_Object filename, Lisp_Object aspect, Lisp_Object callback)
{
Lisp_Object encoded_file_name;
int wd = -1;
uint32_t imask = aspect_to_inotifymask (aspect);
uint32_t mask = imask | IN_MASK_ADD | IN_EXCL_UNLINK;
CHECK_STRING (filename);
if (inotifyfd < 0)
{
inotifyfd = inotify_init1 (IN_NONBLOCK | IN_CLOEXEC);
if (inotifyfd < 0)
report_file_notify_error ("File watching is not available", Qnil);
watch_list = Qnil;
add_read_fd (inotifyfd, &inotify_callback, NULL);
}
encoded_file_name = ENCODE_FILE (filename);
wd = inotify_add_watch (inotifyfd, SSDATA (encoded_file_name), mask);
