From e60683a0d553b6488c564863f4e48954944fb0f8 Mon Sep 17 00:00:00 2001 From: bigbiff bigbiff Date: Fri, 22 Feb 2013 20:55:50 -0500 Subject: use libblkid to get filesystem type we can now use libblkid to detect exfat --- libblkid/dos.c | 297 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 297 insertions(+) create mode 100644 libblkid/dos.c (limited to 'libblkid/dos.c') diff --git a/libblkid/dos.c b/libblkid/dos.c new file mode 100644 index 000000000..58877691d --- /dev/null +++ b/libblkid/dos.c @@ -0,0 +1,297 @@ +/* + * MS-DOS partition parsing code + * + * Copyright (C) 2009 Karel Zak + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + * + * Inspired by fdisk, partx, Linux kernel and libparted. + */ +#include +#include +#include +#include + +#include "partitions.h" +#include "dos.h" +#include "aix.h" + +/* see superblocks/vfat.c */ +extern int blkid_probe_is_vfat(blkid_probe pr); + +static const struct dos_subtypes { + unsigned char type; + const struct blkid_idinfo *id; +} dos_nested[] = { + { BLKID_FREEBSD_PARTITION, &bsd_pt_idinfo }, + { BLKID_NETBSD_PARTITION, &bsd_pt_idinfo }, + { BLKID_OPENBSD_PARTITION, &bsd_pt_idinfo }, + { BLKID_UNIXWARE_PARTITION, &unixware_pt_idinfo }, + { BLKID_SOLARIS_X86_PARTITION, &solaris_x86_pt_idinfo }, + { BLKID_MINIX_PARTITION, &minix_pt_idinfo } +}; + +static inline int is_extended(struct dos_partition *p) +{ + return (p->sys_type == BLKID_DOS_EXTENDED_PARTITION || + p->sys_type == BLKID_W95_EXTENDED_PARTITION || + p->sys_type == BLKID_LINUX_EXTENDED_PARTITION); +} + +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 probe_dos_pt(blkid_probe pr, + const struct blkid_idmag *mag __attribute__((__unused__))) +{ + int i; + int ssf; + blkid_parttable tab = NULL; + blkid_partlist ls; + struct dos_partition *p0, *p; + unsigned char *data; + uint32_t start, size, id; + + data = blkid_probe_get_sector(pr, 0); + if (!data) + goto nothing; + + /* ignore disks with AIX magic number -- for more details see aix.c */ + if (memcmp(data, BLKID_AIX_MAGIC_STRING, BLKID_AIX_MAGIC_STRLEN) == 0) + goto nothing; + + /* + * Now that the 55aa signature is present, this is probably + * either the boot sector of a FAT filesystem or a DOS-type + * partition table. + */ + if (blkid_probe_is_vfat(pr)) { + DBG(DEBUG_LOWPROBE, printf("probably FAT -- ignore\n")); + goto nothing; + } + + p0 = (struct dos_partition *) (data + BLKID_MSDOS_PT_OFFSET); + + /* + * Reject PT where boot indicator is not 0 or 0x80. + */ + for (p = p0, i = 0; i < 4; i++, p++) + if (p->boot_ind != 0 && p->boot_ind != 0x80) { + DBG(DEBUG_LOWPROBE, printf("missing boot indicator -- ignore\n")); + goto nothing; + } + + /* + * GPT uses valid MBR + */ + for (p = p0, i = 0; i < 4; i++, p++) { + if (p->sys_type == BLKID_GPT_PARTITION) { + DBG(DEBUG_LOWPROBE, printf("probably GPT -- ignore\n")); + goto nothing; + } + } + + blkid_probe_use_wiper(pr, BLKID_MSDOS_PT_OFFSET, + 512 - BLKID_MSDOS_PT_OFFSET); + + /* + * Well, all checks pass, it's MS-DOS partiton table + */ + if (blkid_partitions_need_typeonly(pr)) + /* caller does not ask for details about partitions */ + return 0; + + ls = blkid_probe_get_partlist(pr); + + /* sector size factor (the start and size are in the real sectors, but + * we need to convert all sizes to 512 logical sectors + */ + ssf = blkid_probe_get_sectorsize(pr) / 512; + + /* allocate a new partition table */ + tab = blkid_partlist_new_parttable(ls, "dos", BLKID_MSDOS_PT_OFFSET); + if (!tab) + goto err; + + id = dos_parttable_id(data); + if (id) { + char buf[37]; + + snprintf(buf, sizeof(buf), "0x%08x", id); + blkid_parttable_set_id(tab, (unsigned char *) buf); + } + + + /* Parse primary partitions */ + for (p = p0, i = 0; i < 4; i++, p++) { + blkid_partition par; + + start = dos_partition_start(p) * ssf; + size = dos_partition_size(p) * ssf; + + if (!size) { + /* Linux kernel ignores empty partitions, but partno for + * the empty primary partitions is not reused */ + blkid_partlist_increment_partno(ls); + continue; + } + par = blkid_partlist_add_partition(ls, tab, start, size); + if (!par) + goto err; + + blkid_partition_set_type(par, p->sys_type); + blkid_partition_set_flags(par, p->boot_ind); + } + + /* Linux uses partition numbers greater than 4 + * for all logical partition and all nested partition tables (bsd, ..) + */ + blkid_partlist_set_partno(ls, 5); + + /* Parse logical partitions */ + for (p = p0, i = 0; i < 4; i++, p++) { + start = dos_partition_start(p) * ssf; + size = dos_partition_size(p) * ssf; + + if (!size) + continue; + if (is_extended(p) && + parse_dos_extended(pr, tab, start, size, ssf) == -1) + goto err; + } + + /* Parse subtypes (nested partitions) on large disks */ + if (!blkid_probe_is_tiny(pr)) { + for (p = p0, i = 0; i < 4; i++, p++) { + size_t n; + + if (!dos_partition_size(p) || is_extended(p)) + continue; + + for (n = 0; n < ARRAY_SIZE(dos_nested); n++) { + if (dos_nested[n].type != p->sys_type) + continue; + + if (blkid_partitions_do_subprobe(pr, + blkid_partlist_get_partition(ls, i), + dos_nested[n].id) == -1) + goto err; + break; + } + } + } + return 0; + +nothing: + return 1; +err: + return -1; +} + + +const struct blkid_idinfo dos_pt_idinfo = +{ + .name = "dos", + .probefunc = probe_dos_pt, + .magics = + { + /* DOS master boot sector: + * + * 0 | Code Area + * 440 | Optional Disk signature + * 446 | Partition table + * 510 | 0x55 + * 511 | 0xAA + */ + { .magic = "\x55\xAA", .len = 2, .sboff = 510 }, + { NULL } + } +}; + -- cgit v1.2.3