diff options
Diffstat (limited to 'fs/partitions/msdos.c')
| -rw-r--r-- | fs/partitions/msdos.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/fs/partitions/msdos.c b/fs/partitions/msdos.c new file mode 100644 index 00000000000..17ee1b4ff08 --- /dev/null +++ b/fs/partitions/msdos.c @@ -0,0 +1,479 @@ +/* + * fs/partitions/msdos.c + * + * Code extracted from drivers/block/genhd.c + * Copyright (C) 1991-1998 Linus Torvalds + * + * Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug + * in the early extended-partition checks and added DM partitions + * + * Support for DiskManager v6.0x added by Mark Lord, + * with information provided by OnTrack. This now works for linux fdisk + * and LILO, as well as loadlin and bootln. Note that disks other than + * /dev/hda *must* have a "DOS" type 0x51 partition in the first slot (hda1). + * + * More flexible handling of extended partitions - aeb, 950831 + * + * Check partition table on IDE disks for common CHS translations + * + * Re-organised Feb 1998 Russell King + */ + +#include <linux/config.h> + +#include "check.h" +#include "msdos.h" +#include "efi.h" + +/* + * Many architectures don't like unaligned accesses, while + * the nr_sects and start_sect partition table entries are + * at a 2 (mod 4) address. + */ +#include <asm/unaligned.h> + +#define SYS_IND(p) (get_unaligned(&p->sys_ind)) +#define NR_SECTS(p) ({ __typeof__(p->nr_sects) __a = \ + get_unaligned(&p->nr_sects); \ + le32_to_cpu(__a); \ + }) + +#define START_SECT(p) ({ __typeof__(p->start_sect) __a = \ + get_unaligned(&p->start_sect); \ + le32_to_cpu(__a); \ + }) + +static inline int is_extended_partition(struct partition *p) +{ + return (SYS_IND(p) == DOS_EXTENDED_PARTITION || + SYS_IND(p) == WIN98_EXTENDED_PARTITION || + SYS_IND(p) == LINUX_EXTENDED_PARTITION); +} + +#define MSDOS_LABEL_MAGIC1 0x55 +#define MSDOS_LABEL_MAGIC2 0xAA + +static inline int +msdos_magic_present(unsigned char *p) +{ + return (p[0] == MSDOS_LABEL_MAGIC1 && p[1] == MSDOS_LABEL_MAGIC2); +} + +/* + * Create devices for each logical partition in an extended partition. + * The logical partitions form a linked list, with each entry being + * a partition table with two entries. The first entry + * is the real data partition (with a start relative to the partition + * table start). The second is a pointer to the next logical partition + * (with a start relative to the entire extended partition). + * We do not create a Linux partition for the partition tables, but + * only for the actual data partitions. + */ + +static void +parse_extended(struct parsed_partitions *state, struct block_device *bdev, + u32 first_sector, u32 first_size) +{ + struct partition *p; + Sector sect; + unsigned char *data; + u32 this_sector, this_size; + int sector_size = bdev_hardsect_size(bdev) / 512; + int loopct = 0; /* number of links followed + without finding a data partition */ + int i; + + this_sector = first_sector; + this_size = first_size; + + while (1) { + if (++loopct > 100) + return; + if (state->next == state->limit) + return; + data = read_dev_sector(bdev, this_sector, §); + if (!data) + return; + + if (!msdos_magic_present(data + 510)) + goto done; + + p = (struct partition *) (data + 0x1be); + + /* + * 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. + */ + + /* + * First process the data partition(s) + */ + for (i=0; i<4; i++, p++) { + u32 offs, size, next; + + if (SYS_IND(p) == 0) + continue; + if (!NR_SECTS(p) || is_extended_partition(p)) + continue; + + /* Check the 3rd and 4th entries - + these sometimes contain random garbage */ + offs = START_SECT(p)*sector_size; + size = NR_SECTS(p)*sector_size; + next = this_sector + offs; + if (i >= 2) { + if (offs + size > this_size) + continue; + if (next < first_sector) + continue; + if (next + size > first_sector + first_size) + continue; + } + + put_partition(state, state->next, next, size); + if (SYS_IND(p) == LINUX_RAID_PARTITION) + state->parts[state->next].flags = 1; + loopct = 0; + if (++state->next == state->limit) + goto done; + } + /* + * Next, process the (first) extended partition, if present. + * (So far, there seems to be no reason to make + * parse_extended() recursive and allow a tree + * of extended partitions.) + * It should be a link to the next logical partition. + */ + p -= 4; + for (i=0; i<4; i++, p++) + if (NR_SECTS(p) && is_extended_partition(p)) + break; + if (i == 4) + goto done; /* nothing left to do */ + + this_sector = first_sector + START_SECT(p) * sector_size; + this_size = NR_SECTS(p) * sector_size; + put_dev_sector(sect); + } +done: + put_dev_sector(sect); +} + +/* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also + indicates linux swap. Be careful before believing this is Solaris. */ + +static void +parse_solaris_x86(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin) +{ +#ifdef CONFIG_SOLARIS_X86_PARTITION + Sector sect; + struct solaris_x86_vtoc *v; + int i; + + v = (struct solaris_x86_vtoc *)read_dev_sector(bdev, offset+1, §); + if (!v) + return; + if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) { + put_dev_sector(sect); + return; + } + printk(" %s%d: <solaris:", state->name, origin); + if (le32_to_cpu(v->v_version) != 1) { + printk(" cannot handle version %d vtoc>\n", + le32_to_cpu(v->v_version)); + put_dev_sector(sect); + return; + } + for (i=0; i<SOLARIS_X86_NUMSLICE && state->next<state->limit; i++) { + struct solaris_x86_slice *s = &v->v_slice[i]; + if (s->s_size == 0) + continue; + printk(" [s%d]", i); + /* solaris partitions are relative to current MS-DOS + * one; must add the offset of the current partition */ + put_partition(state, state->next++, + le32_to_cpu(s->s_start)+offset, + le32_to_cpu(s->s_size)); + } + put_dev_sector(sect); + printk(" >\n"); +#endif +} + +#if defined(CONFIG_BSD_DISKLABEL) || defined(CONFIG_NEC98_PARTITION) +/* + * Create devices for BSD partitions listed in a disklabel, under a + * dos-like partition. See parse_extended() for more information. + */ +void +parse_bsd(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin, char *flavour, + int max_partitions) +{ + Sector sect; + struct bsd_disklabel *l; + struct bsd_partition *p; + + l = (struct bsd_disklabel *)read_dev_sector(bdev, offset+1, §); + if (!l) + return; + if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) { + put_dev_sector(sect); + return; + } + printk(" %s%d: <%s:", state->name, origin, flavour); + + if (le16_to_cpu(l->d_npartitions) < max_partitions) + max_partitions = le16_to_cpu(l->d_npartitions); + for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) { + u32 bsd_start, bsd_size; + + if (state->next == state->limit) + break; + if (p->p_fstype == BSD_FS_UNUSED) + continue; + bsd_start = le32_to_cpu(p->p_offset); + bsd_size = le32_to_cpu(p->p_size); + if (offset == bsd_start && size == bsd_size) + /* full parent partition, we have it already */ + continue; + if (offset > bsd_start || offset+size < bsd_start+bsd_size) { + printk("bad subpartition - ignored\n"); + continue; + } + put_partition(state, state->next++, bsd_start, bsd_size); + } + put_dev_sector(sect); + if (le16_to_cpu(l->d_npartitions) > max_partitions) + printk(" (ignored %d more)", + le16_to_cpu(l->d_npartitions) - max_partitions); + printk(" >\n"); +} +#endif + +static void +parse_freebsd(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin) +{ +#ifdef CONFIG_BSD_DISKLABEL + parse_bsd(state, bdev, offset, size, origin, + "bsd", BSD_MAXPARTITIONS); +#endif +} + +static void +parse_netbsd(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin) +{ +#ifdef CONFIG_BSD_DISKLABEL + parse_bsd(state, bdev, offset, size, origin, + "netbsd", BSD_MAXPARTITIONS); +#endif +} + +static void +parse_openbsd(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin) +{ +#ifdef CONFIG_BSD_DISKLABEL + parse_bsd(state, bdev, offset, size, origin, + "openbsd", OPENBSD_MAXPARTITIONS); +#endif +} + +/* + * Create devices for Unixware partitions listed in a disklabel, under a + * dos-like partition. See parse_extended() for more information. + */ +static void +parse_unixware(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin) +{ +#ifdef CONFIG_UNIXWARE_DISKLABEL + Sector sect; + struct unixware_disklabel *l; + struct unixware_slice *p; + + l = (struct unixware_disklabel *)read_dev_sector(bdev, offset+29, §); + if (!l) + return; + if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC || + le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) { + put_dev_sector(sect); + return; + } + printk(" %s%d: <unixware:", state->name, origin); + p = &l->vtoc.v_slice[1]; + /* I omit the 0th slice as it is the same as whole disk. */ + while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) { + if (state->next == state->limit) + break; + + if (p->s_label != UNIXWARE_FS_UNUSED) + put_partition(state, state->next++, + START_SECT(p), NR_SECTS(p)); + p++; + } + put_dev_sector(sect); + printk(" >\n"); +#endif +} + +/* + * Minix 2.0.0/2.0.2 subpartition support. + * Anand Krishnamurthy <anandk@wiproge.med.ge.com> + * Rajeev V. Pillai <rajeevvp@yahoo.com> + */ +static void +parse_minix(struct parsed_partitions *state, struct block_device *bdev, + u32 offset, u32 size, int origin) +{ +#ifdef CONFIG_MINIX_SUBPARTITION + Sector sect; + unsigned char *data; + struct partition *p; + int i; + + data = read_dev_sector(bdev, offset, §); + if (!data) + return; + + p = (struct partition *)(data + 0x1be); + + /* The first sector of a Minix partition can have either + * a secondary MBR describing its subpartitions, or + * the normal boot sector. */ + if (msdos_magic_present (data + 510) && + SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */ + + printk(" %s%d: <minix:", state->name, origin); + for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) { + if (state->next == state->limit) + break; + /* add each partition in use */ + if (SYS_IND(p) == MINIX_PARTITION) + put_partition(state, state->next++, + START_SECT(p), NR_SECTS(p)); + } + printk(" >\n"); + } + put_dev_sector(sect); +#endif /* CONFIG_MINIX_SUBPARTITION */ +} + +static struct { + unsigned char id; + void (*parse)(struct parsed_partitions *, struct block_device *, + u32, u32, int); +} subtypes[] = { + {FREEBSD_PARTITION, parse_freebsd}, + {NETBSD_PARTITION, parse_netbsd}, + {OPENBSD_PARTITION, parse_openbsd}, + {MINIX_PARTITION, parse_minix}, + {UNIXWARE_PARTITION, parse_unixware}, + {SOLARIS_X86_PARTITION, parse_solaris_x86}, + {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86}, + {0, NULL}, +}; + +int msdos_partition(struct parsed_partitions *state, struct block_device *bdev) +{ + int sector_size = bdev_hardsect_size(bdev) / 512; + Sector sect; + unsigned char *data; + struct partition *p; + int slot; + + data = read_dev_sector(bdev, 0, §); + if (!data) + return -1; + if (!msdos_magic_present(data + 510)) { + put_dev_sector(sect); + return 0; + } + + /* + * Now that the 55aa signature is present, this is probably + * either the boot sector of a FAT filesystem or a DOS-type + * partition table. Reject this in case the boot indicator + * is not 0 or 0x80. + */ + p = (struct partition *) (data + 0x1be); + for (slot = 1; slot <= 4; slot++, p++) { + if (p->boot_ind != 0 && p->boot_ind != 0x80) { + put_dev_sector(sect); + return 0; + } + } + +#ifdef CONFIG_EFI_PARTITION + p = (struct partition *) (data + 0x1be); + for (slot = 1 ; slot <= 4 ; slot++, p++) { + /* If this is an EFI GPT disk, msdos should ignore it. */ + if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) { + put_dev_sector(sect); + return 0; + } + } +#endif + p = (struct partition *) (data + 0x1be); + + /* + * Look for partitions in two passes: + * First find the primary and DOS-type extended partitions. + * On the second pass look inside *BSD, Unixware and Solaris partitions. + */ + + state->next = 5; + for (slot = 1 ; slot <= 4 ; slot++, p++) { + u32 start = START_SECT(p)*sector_size; + u32 size = NR_SECTS(p)*sector_size; + if (SYS_IND(p) == 0) + continue; + if (!size) + continue; + if (is_extended_partition(p)) { + /* prevent someone doing mkfs or mkswap on an + extended partition, but leave room for LILO */ + put_partition(state, slot, start, size == 1 ? 1 : 2); + printk(" <"); + parse_extended(state, bdev, start, size); + printk(" >"); + continue; + } + put_partition(state, slot, start, size); + if (SYS_IND(p) == LINUX_RAID_PARTITION) + state->parts[slot].flags = 1; + if (SYS_IND(p) == DM6_PARTITION) + printk("[DM]"); + if (SYS_IND(p) == EZD_PARTITION) + printk("[EZD]"); + } + + printk("\n"); + + /* second pass - output for each on a separate line */ + p = (struct partition *) (0x1be + data); + for (slot = 1 ; slot <= 4 ; slot++, p++) { + unsigned char id = SYS_IND(p); + int n; + + if (!NR_SECTS(p)) + continue; + + for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++) + ; + + if (!subtypes[n].parse) + continue; + subtypes[n].parse(state, bdev, START_SECT(p)*sector_size, + NR_SECTS(p)*sector_size, slot); + } + put_dev_sector(sect); + return 1; +} |