[src/trunk]: src/usr.sbin/installboot/arch don't complain if the mbr was all ...

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

details:   https://anonhg.NetBSD.org/src/rev/208f36dfb293
branches:  trunk
changeset: 355182:208f36dfb293
user:      christos <christos%NetBSD.org@localhost>
date:      Mon Jul 17 18:43:45 2017 +0000

description:
don't complain if the mbr was all 0's.

diffstat:

 usr.sbin/installboot/arch/landisk.c |  20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)

diffs (42 lines):

diff -r 116a7d959f9d -r 208f36dfb293 usr.sbin/installboot/arch/landisk.c
--- a/usr.sbin/installboot/arch/landisk.c       Mon Jul 17 14:36:13 2017 +0000
+++ b/usr.sbin/installboot/arch/landisk.c       Mon Jul 17 18:43:45 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: landisk.c,v 1.6 2013/10/19 17:08:15 christos Exp $     */
+/*     $NetBSD: landisk.c,v 1.7 2017/07/17 18:43:45 christos Exp $     */
 
 /*-
  * Copyright (c) 2003 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
 
 #include <sys/cdefs.h>
 #if !defined(__lint)
-__RCSID("$NetBSD: landisk.c,v 1.6 2013/10/19 17:08:15 christos Exp $");
+__RCSID("$NetBSD: landisk.c,v 1.7 2017/07/17 18:43:45 christos Exp $");
 #endif /* !__lint */
 
 #include <sys/param.h>
@@ -100,12 +100,18 @@
                goto done;
        }
        if (mbr.mbr_magic != le16toh(MBR_MAGIC)) {
-               if (params->flags & IB_VERBOSE) {
-                       printf(
-                   "Ignoring MBR with invalid magic in sector 0 of `%s'\n",
-                           params->filesystem);
+               const char *p = (const char *)&mbr;
+               const char *e = p + sizeof(mbr);
+               while (p < e && !*p)
+                       p++;
+               if (p != e) {
+                       if (params->flags & IB_VERBOSE) {
+                               printf(
+                       "Ignoring MBR with invalid magic in sector 0 of `%s'\n",
+                                   params->filesystem);
+                       }
+                       memset(&mbr, 0, sizeof(mbr));
                }
-               memset(&mbr, 0, sizeof(mbr));
        }
 
        /*