[src/trunk]: src/sys/kern Handle absolute symlinks to the root.

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/076146cbef2d
branches:  trunk
changeset: 768278:076146cbef2d
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Aug 13 19:40:02 2011 +0000

description:
Handle absolute symlinks to the root.

Fixes panic on `ln -s / foo && cd foo' found by ober by trying to run
wine.

ok dholland

diffstat:

 sys/kern/vfs_lookup.c |  18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diffs (39 lines):

diff -r dd41b3f0a5f1 -r 076146cbef2d sys/kern/vfs_lookup.c
--- a/sys/kern/vfs_lookup.c     Sat Aug 13 19:23:34 2011 +0000
+++ b/sys/kern/vfs_lookup.c     Sat Aug 13 19:40:02 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_lookup.c,v 1.188 2011/08/10 05:42:32 dholland Exp $        */
+/*     $NetBSD: vfs_lookup.c,v 1.189 2011/08/13 19:40:02 riastradh Exp $       */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.188 2011/08/10 05:42:32 dholland Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.189 2011/08/13 19:40:02 riastradh Exp $");
 
 #include "opt_magiclinks.h"
 
@@ -1217,6 +1217,20 @@
                        /* namei_follow unlocks it (ugh) so rele, not put */
                        vrele(foundobj);
                        foundobj = NULL;
+
+                       /*
+                        * If we followed a symlink to `/' and there
+                        * are no more components after the symlink,
+                        * we're done with the loop and what we found
+                        * is the searchdir.
+                        */
+                       if (cnp->cn_nameptr[0] == '\0') {
+                               foundobj = searchdir;
+                               searchdir = NULL;
+                               cnp->cn_flags |= ISLASTCN;
+                               break;
+                       }
+
                        continue;
                }