From 4f49024326629f0ae9fb54fc97a50936a0a0e815 Mon Sep 17 00:00:00 2001
From: krw <krw@openbsd.org>
Date: Sun, 18 Jul 2021 21:40:13 +0000
Subject: [PATCH] Don't save the prt_scyl/prt_ecyl values, change them, use
 them and then restore them. Just change/use the saved values and skip the
 restoring.

Allows PRT_make() to add 'const' to its struct mbr parameter, and
thus allows MBR_make() to add 'const' to its struct mbr
parameter.

No intentional functional change.
---
 sbin/fdisk/mbr.c  |  4 ++--
 sbin/fdisk/mbr.h  |  4 ++--
 sbin/fdisk/part.c | 28 +++++++++-------------------
 sbin/fdisk/part.h |  4 ++--
 4 files changed, 15 insertions(+), 25 deletions(-)

diff --git a/sbin/fdisk/mbr.c b/sbin/fdisk/mbr.c
index 812b098d5b7..a13ccd6ae7d 100644
--- a/sbin/fdisk/mbr.c
+++ b/sbin/fdisk/mbr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mbr.c,v 1.88 2021/07/18 12:41:00 krw Exp $	*/
+/*	$OpenBSD: mbr.c,v 1.89 2021/07/18 21:40:13 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -170,7 +170,7 @@ MBR_parse(const struct dos_mbr *dos_mbr, const uint64_t lba_self,
 }
 
 void
-MBR_make(struct mbr *mbr, struct dos_mbr *dos_mbr)
+MBR_make(const struct mbr *mbr, struct dos_mbr *dos_mbr)
 {
 	struct dos_partition	dos_partition;
 	int			i;
diff --git a/sbin/fdisk/mbr.h b/sbin/fdisk/mbr.h
index d097e9c1d3b..bc58b4a2cdd 100644
--- a/sbin/fdisk/mbr.h
+++ b/sbin/fdisk/mbr.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mbr.h,v 1.36 2021/07/18 12:41:00 krw Exp $	*/
+/*	$OpenBSD: mbr.h,v 1.37 2021/07/18 21:40:13 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -32,7 +32,7 @@ extern struct mbr	initial_mbr;
 void		MBR_print(const struct mbr *, const char *);
 void		MBR_parse(const struct dos_mbr *, const uint64_t,
     const uint64_t, struct mbr *);
-void		MBR_make(struct mbr *, struct dos_mbr *);
+void		MBR_make(const struct mbr *, struct dos_mbr *);
 void		MBR_init(struct mbr *);
 void		MBR_init_GPT(struct mbr *);
 int		MBR_read(const uint64_t, const uint64_t, struct mbr *);
diff --git a/sbin/fdisk/part.c b/sbin/fdisk/part.c
index 14e8ba92f6d..c062cc003c6 100644
--- a/sbin/fdisk/part.c
+++ b/sbin/fdisk/part.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: part.c,v 1.99 2021/07/16 22:50:43 krw Exp $	*/
+/*	$OpenBSD: part.c,v 1.100 2021/07/18 21:40:13 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -275,20 +275,15 @@ check_chs(const struct prt *prt)
 }
 
 void
-PRT_make(struct prt *prt, const uint64_t lba_self, const uint64_t lba_firstembr,
+PRT_make(const struct prt *prt, const uint64_t lba_self, const uint64_t lba_firstembr,
     struct dos_partition *dp)
 {
 	uint64_t		off, t;
-	uint32_t		ecsave, scsave;
+	uint32_t		ecyl, scyl;
 
-	/* Save (and restore below) cylinder info we may fiddle with. */
-	scsave = prt->prt_scyl;
-	ecsave = prt->prt_ecyl;
+	scyl = (prt->prt_scyl > 1023) ? 1023 : prt->prt_scyl;
+	ecyl = (prt->prt_ecyl > 1023) ? 1023 : prt->prt_ecyl;
 
-	if ((prt->prt_scyl > 1023) || (prt->prt_ecyl > 1023)) {
-		prt->prt_scyl = (prt->prt_scyl > 1023)? 1023: prt->prt_scyl;
-		prt->prt_ecyl = (prt->prt_ecyl > 1023)? 1023: prt->prt_ecyl;
-	}
 	if ((prt->prt_id == DOSPTYP_EXTEND) || (prt->prt_id == DOSPTYP_EXTENDL))
 		off = lba_firstembr;
 	else
@@ -296,13 +291,11 @@ PRT_make(struct prt *prt, const uint64_t lba_self, const uint64_t lba_firstembr,
 
 	if (check_chs(prt) == 0) {
 		dp->dp_shd = prt->prt_shead & 0xFF;
-		dp->dp_ssect = (prt->prt_ssect & 0x3F) |
-		    ((prt->prt_scyl & 0x300) >> 2);
-		dp->dp_scyl = prt->prt_scyl & 0xFF;
+		dp->dp_ssect = (prt->prt_ssect & 0x3F) | ((scyl & 0x300) >> 2);
+		dp->dp_scyl = scyl & 0xFF;
 		dp->dp_ehd = prt->prt_ehead & 0xFF;
-		dp->dp_esect = (prt->prt_esect & 0x3F) |
-		    ((prt->prt_ecyl & 0x300) >> 2);
-		dp->dp_ecyl = prt->prt_ecyl & 0xFF;
+		dp->dp_esect = (prt->prt_esect & 0x3F) | ((ecyl & 0x300) >> 2);
+		dp->dp_ecyl = ecyl & 0xFF;
 	} else {
 		memset(dp, 0xFF, sizeof(*dp));
 	}
@@ -318,9 +311,6 @@ PRT_make(struct prt *prt, const uint64_t lba_self, const uint64_t lba_firstembr,
 	else
 		t = htole64(prt->prt_ns);
 	memcpy(&dp->dp_size, &t, sizeof(uint32_t));
-
-	prt->prt_scyl = scsave;
-	prt->prt_ecyl = ecsave;
 }
 
 void
diff --git a/sbin/fdisk/part.h b/sbin/fdisk/part.h
index 08cfa9240c5..71baa85a4a1 100644
--- a/sbin/fdisk/part.h
+++ b/sbin/fdisk/part.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: part.h,v 1.28 2021/07/13 15:03:34 krw Exp $	*/
+/*	$OpenBSD: part.h,v 1.29 2021/07/18 21:40:13 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -31,7 +31,7 @@ struct prt {
 void		 PRT_printall(void);
 void		 PRT_parse(const struct dos_partition *, const uint64_t,
     const uint64_t, struct prt *);
-void		 PRT_make(struct prt *,const uint64_t, const uint64_t,
+void		 PRT_make(const struct prt *,const uint64_t, const uint64_t,
     struct dos_partition *);
 void		 PRT_print(const int, const struct prt *, const char *);
 char		*PRT_uuid_to_typename(const struct uuid *);
-- 
2.20.1