Don't zap disklabel (and next 6 blocks) when installing boot block on

4k-sector disk drives.

Noted and fix tested by David Vasek via misc@

tweaks & ok jsing@

diff --git a/usr.sbin/installboot/i386_installboot.c b/usr.sbin/installboot/i386_installboot.c
index 2a0d188..fff1685 100644 (file)
--- a/usr.sbin/installboot/i386_installboot.c
+++ b/usr.sbin/installboot/i386_installboot.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: i386_installboot.c,v 1.1 2014/01/19 02:58:50 jsing Exp $      */
+/*     $OpenBSD: i386_installboot.c,v 1.2 2014/04/27 13:41:50 krw Exp $        */
 /*     $NetBSD: installboot.c,v 1.5 1995/11/17 23:23:50 gwr Exp $ */
 
 /*
@@ -190,9 +190,13 @@ write_bootblocks(int devfd, char *dev, struct disklabel *dl)
 
        if (!nowrite) {
                if (lseek(devfd, (off_t)start * dl->d_secsize, SEEK_SET) < 0)
-                       err(1, "seek bootstrap");
+                       err(1, "seek boot sector");
                secbuf = calloc(1, dl->d_secsize);
+               if (read(devfd, secbuf, dl->d_secsize) != dl->d_secsize)
+                       err(1, "read boot sector");
                bcopy(blkstore, secbuf, blksize);
+               if (lseek(devfd, (off_t)start * dl->d_secsize, SEEK_SET) < 0)
+                       err(1, "seek bootstrap");
                if (write(devfd, secbuf, dl->d_secsize) != dl->d_secsize)
                        err(1, "write bootstrap");
                free(secbuf);