From: Karel Zak <kzak@redhat.com>
Date: Thu, 26 Feb 2009 13:23:06 +0000 (+0100)
Subject: partx: convert hard sector size to 512-byte sectors
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=176303e08d7f1a7ab1211e0b4f3292d2a4648a07;p=util-linux

partx: convert hard sector size to 512-byte sectors

The msdos PT depends on a sector size (BLKSSZGET), but partx(8) counts
internally with 512-byte sectors only. The dos.c has to convert start
and size to 512-byte sectors.

sysfs (kernel uses 512-byte sectors only):

  # cat /sys/block/sdb/sdb1/{start,size}
  256
  16128

(note that 16128 * 512 = 8257536; 8Mb)

old version:

  # partx /dev/sdb
  1:        32-     2047 (     2016 sectors,      1 MB)
                                                  ^^^^
start, end and sectors are correct, but in 4KiB sectors
The size in MB is completely wrong.

new version:

  # partx -l /dev/sdb
  1:       256-    16383 (    16128 sectors,      8 MB)

start, end and sectors are converted to 512-byte sectors. The size in
MB is correct now.

Note that this change is important, because "partx -a" counts the size
of a new partition in 512-byte sectors for all PT formats (sun, gpt, ...).

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/partx/Makefile.am b/partx/Makefile.am
index 798cfea7..5fc5db6c 100644
--- a/partx/Makefile.am
+++ b/partx/Makefile.am
@@ -4,7 +4,11 @@ if BUILD_PARTX
 
 usrsbinexec_PROGRAMS = addpart delpart partx
 partx_SOURCES = bsd.c dos.c partx.c solaris.c unixware.c gpt.c crc32.c \
-		efi.h gpt.h crc32.h partx.h dos.h
+		efi.h gpt.h crc32.h partx.h dos.h ../lib/blkdev.c
+
+if LINUX
+partx_SOURCES += ../lib/linux_version.c
+endif
 
 dist_man_MANS = addpart.8 delpart.8 partx.8
 
diff --git a/partx/dos.c b/partx/dos.c
index c4fb28a9..ebc4ce0a 100644
--- a/partx/dos.c
+++ b/partx/dos.c
@@ -1,4 +1,7 @@
 #include <stdio.h>
+
+#include "blkdev.h"
+
 #include "partx.h"
 #include "dos.h"
 
@@ -25,7 +28,7 @@ partition_size(struct partition *p) {
 
 static int
 read_extended_partition(int fd, struct partition *ep,
-			struct slice *sp, int ns)
+			struct slice *sp, int ns, int ssf)
 {
 	struct partition *p;
 	unsigned long start, here;
@@ -54,8 +57,8 @@ read_extended_partition(int fd, struct partition *ep,
 			if (partition_size(p) == 0 || is_extended(p->sys_type))
 				continue;
 			if (n < ns) {
-				sp[n].start = here + partition_start(p);
-				sp[n].size = partition_size(p);
+				sp[n].start = (here + partition_start(p)) * ssf;
+				sp[n].size = partition_size(p) * ssf;
 				n++;
 			} else {
 				fprintf(stderr,
@@ -89,6 +92,7 @@ read_dos_pt(int fd, struct slice all, struct slice *sp, int ns) {
 	unsigned long offset = all.start;
 	int i, n=0;
 	unsigned char *bp;
+	int ssf;
 
 	bp = getblock(fd, offset);
 	if (bp == NULL)
@@ -97,6 +101,13 @@ read_dos_pt(int fd, struct slice all, struct slice *sp, int ns) {
 	if (bp[510] != 0x55 || bp[511] != 0xaa)
 		return -1;
 
+	/* msdos PT depends sector size... */
+	if (blkdev_get_sector_size(fd, &ssf) != 0)
+		ssf = DEFAULT_SECTOR_SIZE;
+
+	/* ... but partx counts everything in 512-byte sectors */
+	ssf /= 512;
+
 	p = (struct partition *) (bp + 0x1be);
 	for (i=0; i<4; i++) {
 		if (is_gpt(p->sys_type))
@@ -107,8 +118,8 @@ read_dos_pt(int fd, struct slice all, struct slice *sp, int ns) {
 	for (i=0; i<4; i++) {
 		/* always add, even if zero length */
 		if (n < ns) {
-			sp[n].start = partition_start(p);
-			sp[n].size = partition_size(p);
+			sp[n].start = partition_start(p) * ssf;
+			sp[n].size = partition_size(p) * ssf;
 			n++;
 		} else {
 			fprintf(stderr,
@@ -120,7 +131,7 @@ read_dos_pt(int fd, struct slice all, struct slice *sp, int ns) {
 	p = (struct partition *) (bp + 0x1be);
 	for (i=0; i<4; i++) {
 		if (is_extended(p->sys_type))
-			n += read_extended_partition(fd, p, sp+n, ns-n);
+			n += read_extended_partition(fd, p, sp+n, ns-n, ssf);
 		p++;
 	}
 	return n;
diff --git a/partx/partx.8 b/partx/partx.8
index 61ece52f..23a247f3 100644
--- a/partx/partx.8
+++ b/partx/partx.8
@@ -29,7 +29,7 @@ add specified partitions or read disk and add all partitions
 delete specified or all partitions
 .TP
 .B \-l
-list partitions
+list partitions. Note that the all numbers are in 512-byte sectors.
 .TP
 .BI --type " TYPE"
 Specify the partition type -- dos, bsd, solaris, unixware or gpt.