msdos.c

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/*
 *  fs/partitions/msdos.c
 *
 *  Code extracted from drivers/block/genhd.c
 *  Copyright (C) 1991-1998  Linus Torvalds
 *
 *  Thanks to Branko Lankester, [email protected], 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/msdos_fs.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)

static inline sector_t nr_sects(struct partition *p)
{
    return (sector_t)get_unaligned_le32(&p->nr_sects);
}

static inline sector_t start_sect(struct partition *p)
{
    return (sector_t)get_unaligned_le32(&p->start_sect);
}

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);
}

/* Value is EBCDIC 'IBMA' */
#define AIX_LABEL_MAGIC1    0xC9
#define AIX_LABEL_MAGIC2    0xC2
#define AIX_LABEL_MAGIC3    0xD4
#define AIX_LABEL_MAGIC4    0xC1
static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
{
    struct partition *pt = (struct partition *) (p + 0x1be);
    Sector sect;
    unsigned char *d;
    int slot, ret = 0;

    if (!(p[0] == AIX_LABEL_MAGIC1 &&
        p[1] == AIX_LABEL_MAGIC2 &&
        p[2] == AIX_LABEL_MAGIC3 &&
        p[3] == AIX_LABEL_MAGIC4))
        return 0;
    /* Assume the partition table is valid if Linux partitions exists */
    for (slot = 1; slot <= 4; slot++, pt++) {
        if (pt->sys_ind == LINUX_SWAP_PARTITION ||
            pt->sys_ind == LINUX_RAID_PARTITION ||
            pt->sys_ind == LINUX_DATA_PARTITION ||
            pt->sys_ind == LINUX_LVM_PARTITION ||
            is_extended_partition(pt))
            return 0;
    }
    d = read_part_sector(state, 7, &sect);
    if (d) {
        if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M')
            ret = 1;
        put_dev_sector(sect);
    };
    return ret;
}

/*
 * 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,
               sector_t first_sector, sector_t first_size)
{
    struct partition *p;
    Sector sect;
    unsigned char *data;
    sector_t this_sector, this_size;
    sector_t sector_size = bdev_logical_block_size(state->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_part_sector(state, this_sector, &sect);
        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++) {
            sector_t offs, size, next;
            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 = ADDPART_FLAG_RAID;
            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);
}

/* [email protected]: 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,
                  sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_SOLARIS_X86_PARTITION
    Sector sect;
    struct solaris_x86_vtoc *v;
    int i;
    short max_nparts;

    v = read_part_sector(state, offset + 1, &sect);
    if (!v)
        return;
    if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
        put_dev_sector(sect);
        return;
    }
    {
        char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];

        snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);
    }
    if (le32_to_cpu(v->v_version) != 1) {
        char tmp[64];

        snprintf(tmp, sizeof(tmp), "  cannot handle version %d vtoc>\n",
             le32_to_cpu(v->v_version));
        strlcat(state->pp_buf, tmp, PAGE_SIZE);
        put_dev_sector(sect);
        return;
    }
    /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
    max_nparts = le16_to_cpu (v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
    for (i=0; i<max_nparts && state->next<state->limit; i++) {
        struct solaris_x86_slice *s = &v->v_slice[i];
        char tmp[3 + 10 + 1 + 1];

        if (s->s_size == 0)
            continue;
        snprintf(tmp, sizeof(tmp), " [s%d]", i);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);
        /* 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);
    strlcat(state->pp_buf, " >\n", PAGE_SIZE);
#endif
}

#if defined(CONFIG_BSD_DISKLABEL)
/* 
 * Create devices for BSD partitions listed in a disklabel, under a
 * dos-like partition. See parse_extended() for more information.
 */
static void parse_bsd(struct parsed_partitions *state,
              sector_t offset, sector_t size, int origin, char *flavour,
              int max_partitions)
{
    Sector sect;
    struct bsd_disklabel *l;
    struct bsd_partition *p;
    char tmp[64];

    l = read_part_sector(state, offset + 1, &sect);
    if (!l)
        return;
    if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
        put_dev_sector(sect);
        return;
    }

    snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
    strlcat(state->pp_buf, tmp, PAGE_SIZE);

    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++) {
        sector_t 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) {
            strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
            continue;
        }
        put_partition(state, state->next++, bsd_start, bsd_size);
    }
    put_dev_sector(sect);
    if (le16_to_cpu(l->d_npartitions) > max_partitions) {
        snprintf(tmp, sizeof(tmp), " (ignored %d more)",
             le16_to_cpu(l->d_npartitions) - max_partitions);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);
    }
    strlcat(state->pp_buf, " >\n", PAGE_SIZE);
}
#endif

static void parse_freebsd(struct parsed_partitions *state,
              sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
    parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS);
#endif
}

static void parse_netbsd(struct parsed_partitions *state,
             sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
    parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS);
#endif
}

static void parse_openbsd(struct parsed_partitions *state,
              sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
    parse_bsd(state, 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,
               sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_UNIXWARE_DISKLABEL
    Sector sect;
    struct unixware_disklabel *l;
    struct unixware_slice *p;

    l = read_part_sector(state, offset + 29, &sect);
    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;
    }
    {
        char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];

        snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);
    }
    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++,
                      le32_to_cpu(p->start_sect),
                      le32_to_cpu(p->nr_sects));
        p++;
    }
    put_dev_sector(sect);
    strlcat(state->pp_buf, " >\n", PAGE_SIZE);
#endif
}

/*
 * Minix 2.0.0/2.0.2 subpartition support.
 * Anand Krishnamurthy <[email protected]>
 * Rajeev V. Pillai    <[email protected]>
 */
static void parse_minix(struct parsed_partitions *state,
            sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_MINIX_SUBPARTITION
    Sector sect;
    unsigned char *data;
    struct partition *p;
    int i;

    data = read_part_sector(state, offset, &sect);
    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 */
        char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];

        snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);
        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));
        }
        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
    }
    put_dev_sector(sect);
#endif /* CONFIG_MINIX_SUBPARTITION */
}

static struct {
    unsigned char id;
    void (*parse)(struct parsed_partitions *, sector_t, sector_t, 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)
{
    sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
    Sector sect;
    unsigned char *data;
    struct partition *p;
    struct fat_boot_sector *fb;
    int slot;

    data = read_part_sector(state, 0, &sect);
    if (!data)
        return -1;
    if (!msdos_magic_present(data + 510)) {
        put_dev_sector(sect);
        return 0;
    }

    if (aix_magic_present(state, data)) {
        put_dev_sector(sect);
        strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
        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) {
            /*
             * Even without a valid boot inidicator value
             * its still possible this is valid FAT filesystem
             * without a partition table.
             */
            fb = (struct fat_boot_sector *) data;
            if (slot == 1 && fb->reserved && fb->fats
                && fat_valid_media(fb->media)) {
                strlcat(state->pp_buf, "\n", PAGE_SIZE);
                put_dev_sector(sect);
                return 1;
            } else {
                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++) {
        sector_t start = start_sect(p)*sector_size;
        sector_t size = nr_sects(p)*sector_size;
        if (!size)
            continue;
        if (is_extended_partition(p)) {
            /*
             * prevent someone doing mkfs or mkswap on an
             * extended partition, but leave room for LILO
             * FIXME: this uses one logical sector for > 512b
             * sector, although it may not be enough/proper.
             */
            sector_t n = 2;
            n = min(size, max(sector_size, n));
            put_partition(state, slot, start, n);

            strlcat(state->pp_buf, " <", PAGE_SIZE);
            parse_extended(state, start, size);
            strlcat(state->pp_buf, " >", PAGE_SIZE);
            continue;
        }
        put_partition(state, slot, start, size);
        if (SYS_IND(p) == LINUX_RAID_PARTITION)
            state->parts[slot].flags = ADDPART_FLAG_RAID;
        if (SYS_IND(p) == DM6_PARTITION)
            strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
        if (SYS_IND(p) == EZD_PARTITION)
            strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
    }

    strlcat(state->pp_buf, "\n", PAGE_SIZE);

    /* 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, start_sect(p) * sector_size,
                  nr_sects(p) * sector_size, slot);
    }
    put_dev_sector(sect);
    return 1;
}