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Cope with empty msdos partition tables.

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This commit is contained in:
Alasdair Kergon 2004-12-21 16:10:25 +00:00
parent 158fe3d365
commit 9ec484617a
2 changed files with 45 additions and 5 deletions
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1
WHATS_NEW
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@ -1,5 +1,6 @@
Version 2.00.32 -
====================================
Cope with empty msdos partition tables.
Version 2.00.31 - 12th December 2004
====================================

49
lib/device/device.c
View File

@ -20,8 +20,24 @@
#include "filter.h"
#include "xlate.h"
/* See linux/genhd.h and fs/partitions/msdos */
#define PART_MAGIC 0xAA55
#define PART_OFFSET UINT64_C(510)
#define PART_MAGIC_OFFSET UINT64_C(0x1FE)
#define PART_OFFSET UINT64_C(0x1BE)
struct partition {
uint8_t boot_ind;
uint8_t head;
uint8_t sector;
uint8_t cyl;
uint8_t sys_ind; /* partition type */
uint8_t end_head;
uint8_t end_sector;
uint8_t end_cyl;
uint32_t start_sect;
uint32_t nr_sects;
} __attribute__((packed));
static int _is_partitionable(struct device *dev)
{
@ -36,17 +52,40 @@ static int _is_partitionable(struct device *dev)
static int _has_partition_table(struct device *dev)
{
int ret = 0;
uint16_t part_magic;
unsigned p;
uint8_t buf[SECTOR_SIZE];
uint16_t *part_magic;
struct partition *part;
if (!dev_open(dev)) {
stack;
return -1;
}
if (dev_read(dev, PART_OFFSET, sizeof(part_magic), &part_magic) &&
(part_magic == xlate16(PART_MAGIC)))
ret = 1;
if (!dev_read(dev, 0, sizeof(buf), &buf)) {
stack;
goto out;
}
/* FIXME Check for other types of partition table too */
/* Check for msdos partition table */
part_magic = (uint16_t *)(buf + PART_MAGIC_OFFSET);
if ((*part_magic == xlate16(PART_MAGIC))) {
part = (struct partition *) (buf + PART_OFFSET);
for (p = 0; p < 4; p++, part++) {
/* Table is invalid if boot indicator not 0 or 0x80 */
if ((part->boot_ind & 0x7f)) {
ret = 0;
break;
}
/* Must have at least one non-empty partition */
if (part->nr_sects)
ret = 1;
}
}
out:
if (!dev_close(dev))
stack;