1 files changed, 46 insertions, 39 deletions

diff --git a/sbin/fdisk/mbr.c b/sbin/fdisk/mbr.c
index 3793e6a4d75..f96b34d9348 100644
--- a/sbin/fdisk/mbr.c
+++ b/sbin/fdisk/mbr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mbr.c,v 1.102 2021/10/29 18:38:19 krw Exp $	*/
+/*	$OpenBSD: mbr.c,v 1.103 2021/11/08 22:47:47 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -42,6 +42,7 @@ void
 MBR_init(struct mbr *mbr)
 {
 	struct dos_partition	dp;
+	struct prt		bootprt, obsdprt;
 	uint64_t		adj;
 	daddr_t			daddr;
 
@@ -57,70 +58,76 @@ MBR_init(struct mbr *mbr)
 		return;
 	}
 
-	memset(mbr, 0, sizeof(*mbr));
-	memcpy(mbr->mbr_code, default_dmbr.dmbr_boot, sizeof(mbr->mbr_code));
+	memset(&obsdprt, 0, sizeof(obsdprt));
+	memset(&bootprt, 0, sizeof(bootprt));
+
 	memcpy(&dp, &default_dmbr.dmbr_parts[0], sizeof(dp));
-	PRT_parse(&dp, 0, 0, &mbr->mbr_prt[0]);
+	PRT_parse(&dp, 0, 0, &bootprt);
 
-	if (mbr->mbr_prt[0].prt_flag != DOSACTIVE)
-		mbr->mbr_prt[3].prt_flag = DOSACTIVE;
-	mbr->mbr_signature = DOSMBR_SIGNATURE;
+	if (bootprt.prt_flag != DOSACTIVE)
+		obsdprt.prt_flag = DOSACTIVE;
 
 	/* Use whole disk. Reserve first track, or first cyl, if possible. */
-	mbr->mbr_prt[3].prt_id = DOSPTYP_OPENBSD;
+	obsdprt.prt_id = DOSPTYP_OPENBSD;
 	if (disk.dk_heads > 1)
-		mbr->mbr_prt[3].prt_shead = 1;
+		obsdprt.prt_shead = 1;
 	else
-		mbr->mbr_prt[3].prt_shead = 0;
+		obsdprt.prt_shead = 0;
 	if (disk.dk_heads < 2 && disk.dk_cylinders > 1)
-		mbr->mbr_prt[3].prt_scyl = 1;
+		obsdprt.prt_scyl = 1;
 	else
-		mbr->mbr_prt[3].prt_scyl = 0;
-	mbr->mbr_prt[3].prt_ssect = 1;
+		obsdprt.prt_scyl = 0;
+	obsdprt.prt_ssect = 1;
 
 	/* Go right to the end */
-	mbr->mbr_prt[3].prt_ecyl = disk.dk_cylinders - 1;
-	mbr->mbr_prt[3].prt_ehead = disk.dk_heads - 1;
-	mbr->mbr_prt[3].prt_esect = disk.dk_sectors;
+	obsdprt.prt_ecyl = disk.dk_cylinders - 1;
+	obsdprt.prt_ehead = disk.dk_heads - 1;
+	obsdprt.prt_esect = disk.dk_sectors;
 
 	/* Fix up start/length fields */
-	PRT_fix_BN(&mbr->mbr_prt[3], 3);
+	PRT_fix_BN(&obsdprt, 3);
 
 #if defined(__powerpc__) || defined(__mips__)
 	/* Now fix up for the MS-DOS boot partition on PowerPC/MIPS. */
-	mbr->mbr_prt[0].prt_flag = DOSACTIVE;	/* Boot from dos part */
-	mbr->mbr_prt[3].prt_flag = 0;
-	mbr->mbr_prt[3].prt_ns += mbr->mbr_prt[3].prt_bs;
-	mbr->mbr_prt[3].prt_bs = mbr->mbr_prt[0].prt_bs + mbr->mbr_prt[0].prt_ns;
-	mbr->mbr_prt[3].prt_ns -= mbr->mbr_prt[3].prt_bs;
-	PRT_fix_CHS(&mbr->mbr_prt[3]);
-	if ((mbr->mbr_prt[3].prt_shead != 1) || (mbr->mbr_prt[3].prt_ssect != 1)) {
+	bootprt.prt_flag = DOSACTIVE;	/* Boot from dos part */
+	bootprt.prt_flag = 0;
+	obsdprt.prt_ns += obsdprt.prt_bs;
+	obsdprt.prt_bs = bootprt.prt_bs + bootptr.prt_ns;
+	obsdprt.prt_ns -= obsdprt.prt_bs;
+	PRT_fix_CHS(&obsdprt);
+	if ((obsdprt.prt_shead != 1) || (obsdprt.prt_ssect != 1)) {
 		/* align the partition on a cylinder boundary */
-		mbr->mbr_prt[3].prt_shead = 0;
-		mbr->mbr_prt[3].prt_ssect = 1;
-		mbr->mbr_prt[3].prt_scyl += 1;
+		obsdprt.prt_shead = 0;
+		obsdprt.prt_ssect = 1;
+		obsdprt.prt_scyl += 1;
 	}
 	/* Fix up start/length fields */
-	PRT_fix_BN(&mbr->mbr_prt[3], 3);
+	PRT_fix_BN(&obsdprt, 3);
 #else
 	if (disk.dk_bootprt.prt_ns > 0) {
-		mbr->mbr_prt[0] = disk.dk_bootprt;
-		PRT_fix_CHS(&mbr->mbr_prt[0]);
-		mbr->mbr_prt[3].prt_ns += mbr->mbr_prt[3].prt_bs;
-		mbr->mbr_prt[3].prt_bs = mbr->mbr_prt[0].prt_bs + mbr->mbr_prt[0].prt_ns;
-		mbr->mbr_prt[3].prt_ns -= mbr->mbr_prt[3].prt_bs;
-		PRT_fix_CHS(&mbr->mbr_prt[3]);
+		bootprt = disk.dk_bootprt;
+		PRT_fix_CHS(&bootprt);
+		obsdprt.prt_ns += obsdprt.prt_bs;
+		obsdprt.prt_bs = bootprt.prt_bs + bootprt.prt_ns;
+		obsdprt.prt_ns -= obsdprt.prt_bs;
+		PRT_fix_CHS(&obsdprt);
 	}
 #endif
 
 	/* Start OpenBSD MBR partition on a power of 2 block number. */
 	daddr = 1;
-	while (daddr < DL_SECTOBLK(&dl, mbr->mbr_prt[3].prt_bs))
+	while (daddr < DL_SECTOBLK(&dl, obsdprt.prt_bs))
 		daddr *= 2;
-	adj = DL_BLKTOSEC(&dl, daddr) - mbr->mbr_prt[3].prt_bs;
-	mbr->mbr_prt[3].prt_bs += adj;
-	mbr->mbr_prt[3].prt_ns -= adj;
-	PRT_fix_CHS(&mbr->mbr_prt[3]);
+	adj = DL_BLKTOSEC(&dl, daddr) - obsdprt.prt_bs;
+	obsdprt.prt_bs += adj;
+	obsdprt.prt_ns -= adj;
+	PRT_fix_CHS(&obsdprt);
+
+	memset(mbr, 0, sizeof(*mbr));
+	memcpy(mbr->mbr_code, default_dmbr.dmbr_boot, sizeof(mbr->mbr_code));
+	mbr->mbr_prt[0] = bootprt;
+	mbr->mbr_prt[3] = obsdprt;
+	mbr->mbr_signature = DOSMBR_SIGNATURE;
 }
 
 void