Hi,
I noticed that it was undocumented how inotify_add_watch(2) behaves if
IN_ONLYDIR is specified and the target is not a directory.
To discover this, I took the example code in inotify(7) and modified it
to include the IN_ONLYDIR flag. Running the code against an ordinary
file, I saw the following output:
paul@sparkplug:~/git/dCache
(development/frontend-inotify-namespace)$ ./inotify-test README
Press ENTER key to terminate.
Cannot watch 'README'
inotify_add_watch: Not a directory
paul@sparkplug:~/git/dCache (development/frontend-inotify-namespace)$
My machine is "Debian GNU/Linux 9.4 (stretch)". I imagine (but haven't
tested) that the same errno is used on other distros.
I've included a patch that adds ENOTDIR as an additional error in the
inotify_add_watch(2) man page.
I'm undecided whether or not the section in inotify(7) describing
IN_ONLYDIR should also be updated to describe how non-directory targets
are handled.
Cheers,
Paul.
diff --git a/man2/inotify_add_watch.2 b/man2/inotify_add_watch.2
index 5bb7c94a7..e9ba038eb 100644
--- a/man2/inotify_add_watch.2
+++ b/man2/inotify_add_watch.2
@@ -113,6 +113,14 @@ Insufficient kernel memory was available.
.B ENOSPC
The user limit on the total number of inotify watches was reached or the
kernel failed to allocate a needed resource.
+.TP
+.B ENOTDIR
+.I mask
+contains
+.B IN_ONLYDIR
+and
+.I pathname
+is not a directory.
.SH VERSIONS
Inotify was merged into the 2.6.13 Linux kernel.
.SH CONFORMING TO
