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