Date: Fri, 8 Apr 2011 21:34:15 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: "freebsd-current@FreeBSD.org" <freebsd-current@freebsd.org> Subject: Fdisk formatting of disk having bs=1K fails Message-ID: <201104082134.15674.hselasky@c2i.net>
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Hi,
It appears that src/sbin/fdisk.c can only read the MBR of disks having a
blocksize different than 512 bytes. When writing a new MBR, the below check
fails. Can someone having knowledge into fdisk, fix this issue and MFC to 8-
stable? Also I'm curious about the #ifdef __ia64__ .
if ((mboot.bootinst_size = sb.st_size) % secsize != 0)
secsize = 1024;
sb.st_size = sizeof(/boot/mbr) = 512;
--HPS
My attempt to fix this issue:
--- fdisk.c (revision 220305)
+++ fdisk.c (local)
@@ -508,22 +508,29 @@
const char *fname;
int fdesc, n;
struct stat sb;
+ off_t align_size;
fname = b_flag ? b_flag : "/boot/mbr";
if ((fdesc = open(fname, O_RDONLY)) == -1 ||
fstat(fdesc, &sb) == -1)
err(1, "%s", fname);
- if ((mboot.bootinst_size = sb.st_size) % secsize != 0)
- errx(1, "%s: length must be a multiple of sector size",
fname);
+
+ align_size = (sb.st_size + secsize - 1);
+ align_size -= align_size % secsize;
+ if (align_size == 0)
+ errx(1, "%s: length must be non-zero", fname);
+ mboot.bootinst_size = align_size;
if (mboot.bootinst != NULL)
free(mboot.bootinst);
- if ((mboot.bootinst = malloc(mboot.bootinst_size = sb.st_size)) ==
NULL)
+ if ((mboot.bootinst = malloc(align_size)) == NULL)
errx(1, "%s: unable to allocate read buffer", fname);
- if ((n = read(fdesc, mboot.bootinst, mboot.bootinst_size)) == -1 ||
+ if ((n = read(fdesc, mboot.bootinst, sb.st_size)) == -1 ||
close(fdesc))
err(1, "%s", fname);
- if (n != mboot.bootinst_size)
+ if (n != sb.st_size)
errx(1, "%s: short read", fname);
+ if (align_size != n)
+ memset(mboot.bootinst + sb.st_size, 0, align_size -
sb.st_size);
#else
if (mboot.bootinst != NULL)
free(mboot.bootinst);
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