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#include <stdio.h>
#include "blkdev.h"
#include "partx.h"
#include "dos.h"
static int
is_extended(int type) {
return (type == 5 || type == 0xf || type == 0x85);
}
/* assemble badly aligned little endian integer */
static inline unsigned int
assemble4le(unsigned char *p) {
return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
}
static inline unsigned int
partition_start(struct partition *p) {
return assemble4le(&(p->start_sect[0]));
}
static inline unsigned int
partition_size(struct partition *p) {
return assemble4le(&(p->nr_sects[0]));
}
static int
read_extended_partition(int fd, struct partition *ep,
struct slice *sp, int ns, int ssf)
{
struct partition *p;
unsigned long start, here;
unsigned char *bp;
int loopct = 0;
int moretodo = 1;
int i, n=0;
here = start = partition_start(ep);;
while (moretodo) {
moretodo = 0;
if (++loopct > 100)
return n;
bp = getblock(fd, here * ssf); /* in 512 blocks */
if (bp == NULL)
return n;
if (bp[510] != 0x55 || bp[511] != 0xaa)
return n;
p = (struct partition *) (bp + 0x1be);
for (i=0; i<2; i++, p++) {
if (partition_size(p) == 0 || is_extended(p->sys_type))
continue;
if (n < ns) {
sp[n].start = (here + partition_start(p)) * ssf;
sp[n].size = partition_size(p) * ssf;
n++;
} else {
fprintf(stderr,
"dos_extd_partition: too many slices\n");
return n;
}
loopct = 0;
}
p -= 2;
for (i=0; i<2; i++, p++) {
if (partition_size(p) != 0 &&
is_extended(p->sys_type)) {
here = start + partition_start(p);
moretodo = 1;
break;
}
}
}
return n;
}
static int
is_gpt(int type) {
return (type == 0xEE);
}
int
read_dos_pt(int fd, struct slice all, struct slice *sp, int ns) {
struct partition *p;
unsigned long offset = all.start;
int i, n=0;
unsigned char *bp;
int ssf;
bp = getblock(fd, offset);
if (bp == NULL)
return -1;
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))
return 0;
p++;
}
p = (struct partition *) (bp + 0x1be);
for (i=0; i<4; i++) {
/* always add, even if zero length */
if (n < ns) {
sp[n].start = partition_start(p) * ssf;
sp[n].size = partition_size(p) * ssf;
n++;
} else {
fprintf(stderr,
"dos_partition: too many slices\n");
break;
}
p++;
}
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, ssf);
p++;
}
return n;
}
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