static int parse_dos_extended(blkid_probe pr, blkid_parttable tab, uint32_t ex_start, uint32_t ex_size, int ssf) { blkid_partlist ls = blkid_probe_get_partlist(pr); uint32_t cur_start = ex_start, cur_size = ex_size; unsigned char *data; int ct_nodata = 0; /* count ext.partitions without data partitions */ int i; while (1) { struct dos_partition *p, *p0; uint32_t start, size; if (++ct_nodata > 100) return 0; data = blkid_probe_get_sector(pr, cur_start); if (!data) goto leave; /* malformed partition? */ if (!is_valid_mbr_signature(data)) goto leave; p0 = (struct dos_partition *) (data + BLKID_MSDOS_PT_OFFSET); /* Usually, the first entry is the real data partition, * the 2nd entry is the next extended partition, or empty, * and the 3rd and 4th entries are unused. * However, DRDOS sometimes has the extended partition as * the first entry (when the data partition is empty), * and OS/2 seems to use all four entries. * -- Linux kernel fs/partitions/dos.c * * See also http://en.wikipedia.org/wiki/Extended_boot_record */ /* Parse data partition */ for (p = p0, i = 0; i < 4; i++, p++) { uint32_t abs_start; blkid_partition par; /* the start is relative to the parental ext.partition */ start = dos_partition_start(p) * ssf; size = dos_partition_size(p) * ssf; abs_start = cur_start + start; /* absolute start */ if (!size || is_extended(p)) continue; if (i >= 2) { /* extra checks to detect real data on * 3rd and 4th entries */ if (start + size > cur_size) continue; if (abs_start < ex_start) continue; if (abs_start + size > ex_start + ex_size) continue; } par = blkid_partlist_add_partition(ls, tab, abs_start, size); if (!par) goto err; blkid_partition_set_type(par, p->sys_type); blkid_partition_set_flags(par, p->boot_ind); ct_nodata = 0; } /* The first nested ext.partition should be a link to the next * logical partition. Everything other (recursive ext.partitions) * is junk. */ for (p = p0, i = 0; i < 4; i++, p++) { start = dos_partition_start(p) * ssf; size = dos_partition_size(p) * ssf; if (size && is_extended(p)) break; } if (i == 4) goto leave; cur_start = ex_start + start; cur_size = size; } leave: return 0; err: return -1; }
static int parse_dos_extended(blkid_probe pr, blkid_parttable tab, uint32_t ex_start, uint32_t ex_size, int ssf) { blkid_partlist ls = blkid_probe_get_partlist(pr); uint32_t cur_start = ex_start, cur_size = ex_size; unsigned char *data; int ct_nodata = 0; /* count ext.partitions without data partitions */ int i; DBG(LOWPROBE, ul_debug("parse EBR [start=%d, size=%d]", ex_start/ssf, ex_size/ssf)); if (ex_start == 0) { DBG(LOWPROBE, ul_debug("Bad offset in primary extended partition -- ignore")); return 0; } while (1) { struct dos_partition *p, *p0; uint32_t start, size; if (++ct_nodata > 100) return BLKID_PROBE_OK; data = blkid_probe_get_sector(pr, cur_start); if (!data) { if (errno) return -errno; goto leave; /* malformed partition? */ } if (!mbr_is_valid_magic(data)) goto leave; p0 = mbr_get_partition(data, 0); /* Usually, the first entry is the real data partition, * the 2nd entry is the next extended partition, or empty, * and the 3rd and 4th entries are unused. * However, DRDOS sometimes has the extended partition as * the first entry (when the data partition is empty), * and OS/2 seems to use all four entries. * -- Linux kernel fs/partitions/dos.c * * See also http://en.wikipedia.org/wiki/Extended_boot_record */ /* Parse data partition */ for (p = p0, i = 0; i < 4; i++, p++) { uint32_t abs_start; blkid_partition par; /* the start is relative to the parental ext.partition */ start = dos_partition_get_start(p) * ssf; size = dos_partition_get_size(p) * ssf; abs_start = cur_start + start; /* absolute start */ if (!size || is_extended(p)) continue; if (i >= 2) { /* extra checks to detect real data on * 3rd and 4th entries */ if (start + size > cur_size) continue; if (abs_start < ex_start) continue; if (abs_start + size > ex_start + ex_size) continue; } /* Avoid recursive non-empty links, see ct_nodata counter */ if (blkid_partlist_get_partition_by_start(ls, abs_start)) { DBG(LOWPROBE, ul_debug("#%d: EBR duplicate data partition [abs start=%u] -- ignore", i + 1, abs_start)); continue; } par = blkid_partlist_add_partition(ls, tab, abs_start, size); if (!par) return -ENOMEM; blkid_partition_set_type(par, p->sys_ind); blkid_partition_set_flags(par, p->boot_ind); blkid_partition_gen_uuid(par); ct_nodata = 0; } /* The first nested ext.partition should be a link to the next * logical partition. Everything other (recursive ext.partitions) * is junk. */ for (p = p0, i = 0; i < 4; i++, p++) { start = dos_partition_get_start(p) * ssf; size = dos_partition_get_size(p) * ssf; if (size && is_extended(p)) { if (start == 0) DBG(LOWPROBE, ul_debug("#%d: EBR link offset is zero -- ignore", i + 1)); else break; } } if (i == 4) goto leave; cur_start = ex_start + start; cur_size = size; } leave: return BLKID_PROBE_OK; }