[src/trunk]: src/sys/arch/i386/stand/lib avoid pointer aliasing problems.

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

details:   https://anonhg.NetBSD.org/src/rev/52a615ffb7b4
branches:  trunk
changeset: 791021:52a615ffb7b4
user:      christos <christos%NetBSD.org@localhost>
date:      Thu Oct 31 20:31:04 2013 +0000

description:
avoid pointer aliasing problems.

diffstat:

 sys/arch/i386/stand/lib/biosdisk.c |  11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diffs (46 lines):

diff -r f6ba577abc00 -r 52a615ffb7b4 sys/arch/i386/stand/lib/biosdisk.c
--- a/sys/arch/i386/stand/lib/biosdisk.c        Thu Oct 31 17:28:10 2013 +0000
+++ b/sys/arch/i386/stand/lib/biosdisk.c        Thu Oct 31 20:31:04 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: biosdisk.c,v 1.42 2012/07/03 15:24:37 tsutsui Exp $    */
+/*     $NetBSD: biosdisk.c,v 1.43 2013/10/31 20:31:04 christos Exp $   */
 
 /*
  * Copyright (c) 1996, 1998
@@ -118,6 +118,8 @@
 static struct btinfo_bootwedge bi_wedge;
 #endif
 
+#define MBR_PARTS(buf) ((char *)(buf) + offsetof(struct mbr_sector, mbr_parts))
+
 #define        RF_PROTECTED_SECTORS    64      /* XXX refer to <.../rf_optnames.h> */
 
 int
@@ -231,7 +233,7 @@
                return EIO;
        }
 
-       gpth = *(const struct gpt_hdr *)d->buf;
+       memcpy(&gpth, d->buf, sizeof(gpth));
 
        if (memcmp(GPT_HDR_SIG, gpth.hdr_sig, sizeof(gpth.hdr_sig)))
                return -1;
@@ -423,7 +425,7 @@
        if ((uint8_t)d->buf[510] != 0x55 || (uint8_t)d->buf[511] != 0xAA) {
                return -1;
        }
-       memcpy(&mbr, ((struct mbr_sector *)d->buf)->mbr_parts, sizeof(mbr));
+       memcpy(&mbr, MBR_PARTS(d->buf), sizeof(mbr));
        for (i = 0; i < MBR_PART_COUNT; i++) {
                typ = mbr[i].mbrp_type;
                if (typ == 0)
@@ -478,8 +480,7 @@
 #endif
                        return EIO;
                }
-               memcpy(&mbr, ((struct mbr_sector *)d->buf)->mbr_parts,
-                      sizeof(mbr));
+               memcpy(&mbr, MBR_PARTS(d->buf), sizeof(mbr));
                /* Look for NetBSD partition ID */
                for (i = 0; i < MBR_PART_COUNT; i++) {
                        typ = mbr[i].mbrp_type;