lockf: Invalid argument on pipe

[Kostik Belousov]

On Mon, Mar 09, 2009 at 11:35:58PM +0000, Robert Watson wrote:
> 
> On Mon, 9 Mar 2009, Timothy Redaelli wrote:
> 
> >Why can't I do a lockf on a file descriptor that does not point a real 
> >file (such as stderr, stdout, or a character device)?
> >
> >Since it works under NetBSD, Linux, Solaris. For portability between 
> >systems I hope I can do it under FreeBSD.
> >
> >The following code is simple, but It reproduce the problem. Under 
> >non-FreeBSD systems, It will block before the puts. Instead under FreeBSD 
> >the lockf calls return error and, so, the lock does not works.
> 
> Could you file a PR for this, with pretty much this e-mail and sample code 
> included?  There's no real reason not for it to work other than that it is 
> likely not implemented for devfs; that should be easy to fix it but opening 
> a PR will help us keep track of the fact that it wants to be fixed.
> 
> thanks,
> 
> Robert N M Watson
> Computer Laboratory
> University of Cambridge
> 
> >
> >Any suggest?
> >
> ><snip>
> >#include <stdio.h>
> >#include <unistd.h>
> >#include <stdlib.h>
> >#include <string.h>
> >
> >int main(int argc, char *argv[]) {
> >       char tmp[256];
> >
> >       if (lockf(2, F_LOCK, 0) == -1)
> >               perror("lock");
> >       snprintf (tmp, 256, "%s XXX", argv[0]);
> >       if (!argv[1] || strcmp(argv[1], "XXX"))
> >               system(tmp);
> >       puts("You should see it only after ctrl+c");
> >       return EXIT_SUCCESS;
> >}
> ><end snip>

It is explicitely disabled in devfs code. The following patch works
for me.

diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 1087452..b890da7 100644
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -452,14 +452,6 @@ devfs_access(struct vop_access_args *ap)
 
 /* ARGSUSED */
 static int
-devfs_advlock(struct vop_advlock_args *ap)
-{
-
-	return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
-}
-
-/* ARGSUSED */
-static int
 devfs_close(struct vop_close_args *ap)
 {
 	struct vnode *vp = ap->a_vp, *oldvp;
@@ -1552,7 +1544,6 @@ static struct vop_vector devfs_specops = {
 	.vop_default =		&default_vnodeops,
 
 	.vop_access =		devfs_access,
-	.vop_advlock =		devfs_advlock,
 	.vop_bmap =		VOP_PANIC,
 	.vop_close =		devfs_close,
 	.vop_create =		VOP_PANIC,
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