bug#21432: 25.0.50; file-notify-rm-watch (inotify) errors if watched dir is deleted

[Eli Zaretskii]

> From: Tassilo Horn <tsdh@gnu.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  21432@debbugs.gnu.org
> Date: Mon, 14 Sep 2015 08:08:20 +0200
> 
> Michael Albinus <michael.albinus@gmx.de> writes:
> 
> Hi Michael,
> 
> >>> So I think having a validation function is a good idea.
> >>
> >> Yes. I've started to write a prototype for inotify.c, will show when
> >> it works (slow progress, you know :-( )
> >
> > I've committed a patch to the trunk, adding `file-notify-valid-p' and
> > its native implementations in inotify.c and tramp.el. Comments
> > welcome.

I've added a w32 implementation in w32notify.c.

> I've added two tests, one for plain files and one for directories.  They
> are "green" right now but I think they should not.

I think you are testing this incorrectly.

> What seems wrong to me is that the descriptors stay valid even when the
> watched file or directory is deleted.  For files this might be ok
> (though maybe inotify-specific) because when I create a new file with
> the same name, the watch will trigger.
> 
> However, the current hehavior is certainly wrong for directories.  When
> I deleted the watched directory, the descriptor is still valid, but
> calling file-notify-rm-watch on it signals an error.

AFAIR, filenotify.el watches the parent directory of the
file/directory you asked it to watch.  So to see the invalid-p method
in action you need to remove the parent, not the directory itself.