[src/trunk]: src/sys/net/npf nbuf_advfetch: fix bug and change behaviour on e...

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

details:   https://anonhg.NetBSD.org/src/rev/749fe9efb8bf
branches:  trunk
changeset: 757918:749fe9efb8bf
user:      rmind <rmind%NetBSD.org@localhost>
date:      Sun Oct 03 19:30:22 2010 +0000

description:
nbuf_advfetch: fix bug and change behaviour on error case.

diffstat:

 sys/net/npf/npf_mbuf.c |  20 ++++++++++++++------
 1 files changed, 14 insertions(+), 6 deletions(-)

diffs (48 lines):

diff -r 2c626e1130fb -r 749fe9efb8bf sys/net/npf/npf_mbuf.c
--- a/sys/net/npf/npf_mbuf.c    Sun Oct 03 08:21:27 2010 +0000
+++ b/sys/net/npf/npf_mbuf.c    Sun Oct 03 19:30:22 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: npf_mbuf.c,v 1.3 2010/09/25 00:25:31 rmind Exp $       */
+/*     $NetBSD: npf_mbuf.c,v 1.4 2010/10/03 19:30:22 rmind Exp $       */
 
 /*-
  * Copyright (c) 2009-2010 The NetBSD Foundation, Inc.
@@ -38,7 +38,7 @@
 
 #ifdef _KERNEL
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: npf_mbuf.c,v 1.3 2010/09/25 00:25:31 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: npf_mbuf.c,v 1.4 2010/10/03 19:30:22 rmind Exp $");
 #endif
 
 #include <sys/param.h>
@@ -189,17 +189,25 @@
 
 /*
  * nbuf_advfetch: advance and fetch the datum.
- * WARNING: Values of nbuf and n_ptr are undefined on error.
  */
 int
 nbuf_advfetch(nbuf_t **nbuf, void **n_ptr, u_int n, size_t len, void *buf)
 {
+       nbuf_t *orig_nbuf = *nbuf;
+       void *orig_nptr = *n_ptr;
+       int error;
 
        *n_ptr = nbuf_advance(nbuf, *n_ptr, n);
-       if (__predict_false(*n_ptr == NULL)) {
-               return EINVAL;
+       if (__predict_false(*n_ptr != NULL)) {
+               error = nbuf_fetch_datum(*nbuf, *n_ptr, len, buf);
+       } else {
+               error = EINVAL;
        }
-       return nbuf_fetch_datum(*nbuf, n_ptr, len, buf);
+       if (__predict_false(error)) {
+               *nbuf = orig_nbuf;
+               *n_ptr = orig_nptr;
+       }
+       return error;
 }
 
 /*