/*      $NetBSD: disksubr.c,v 1.34 2026/07/14 13:34:36 thorpej Exp $    */

/*
 * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)ufs_disksubr.c      7.16 (Berkeley) 5/4/91
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: disksubr.c,v 1.34 2026/07/14 13:34:36 thorpej Exp $");

#include "opt_mbr.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/disklabel.h>
#include <sys/disk.h>
#include <sys/syslog.h>

#include <sys/bswap.h>

int fat_types[] = { MBR_PTYPE_FAT12, MBR_PTYPE_FAT16S,
                    MBR_PTYPE_FAT16B, MBR_PTYPE_FAT32,
                    MBR_PTYPE_FAT32L, MBR_PTYPE_FAT16L,
                    -1 };

#define NO_MBR_SIGNATURE ((struct mbr_partition *) -1)

#ifdef BSDDISKLABEL_EI
void swap_endian_disklabel(struct disklabel *, struct disklabel *);
uint16_t dkcksum_re(struct disklabel *);
#endif
#ifdef COMPAT_MMEYE_OLDLABEL
void swap_mmeye_disklabel(struct disklabel *, struct disklabel *);
uint16_t dkcksum_mmeye(struct disklabel *);
#endif

static struct mbr_partition *mbr_findslice(struct mbr_partition *,
    struct buf *);

#ifdef BSDDISKLABEL_EI
void
swap_endian_disklabel(struct disklabel *nlp, struct disklabel *olp)
{
        int i;
#define SW16(X) nlp->X = bswap16(olp->X)
#define SW32(X) nlp->X = bswap32(olp->X)

        SW32(d_magic);
        SW16(d_type);
        SW16(d_subtype);

        /* no need to swap char strings */
        memcpy(nlp->d_typename, olp->d_typename, sizeof(nlp->d_typename));

        /* XXX What should we do for d_un (an union of char and pointers) ? */
        memcpy(nlp->d_packname, olp->d_packname, sizeof(nlp->d_packname));

        SW32(d_secsize);
        SW32(d_nsectors);
        SW32(d_ntracks);
        SW32(d_ncylinders);
        SW32(d_secpercyl);
        SW32(d_secperunit);

        SW16(d_sparespertrack);
        SW16(d_sparespercyl);

        SW32(d_acylinders);

        SW16(d_rpm);
        SW16(d_interleave);
        SW16(d_trackskew);              /* sector 0 skew, per track */
        SW16(d_cylskew);                /* sector 0 skew, per cylinder */
        SW32(d_headswitch);             /* head switch time, usec */
        SW32(d_trkseek);                /* track-to-track seek, usec */
        SW32(d_flags);                  /* generic flags */

        for (i = 0; i < NDDATA; i++)
                SW32(d_drivedata[i]);   /* drive-type specific information */

        for (i = 0; i < NSPARE; i++)
                SW32(d_spare[i]);       /* reserved for future use */

        SW32(d_magic2);                 /* the magic number (again) */
        SW16(d_checksum);               /* xor of data incl. partitions */

        /* filesystem and partition information: */
        SW16(d_npartitions);    /* number of partitions in following */
        SW32(d_bbsize);         /* size of boot area at sn0, bytes */
        SW32(d_sbsize);         /* max size of fs superblock, bytes */

        for (i = 0; i < MAXPARTITIONS; i++) {
                SW32(d_partitions[i].p_size);
                SW32(d_partitions[i].p_offset);
                SW32(d_partitions[i].p_fsize);
                /* p_fstype and p_frag is uint8_t, so no need to swap */
                nlp->d_partitions[i].p_fstype = olp->d_partitions[i].p_fstype;
                nlp->d_partitions[i].p_frag = olp->d_partitions[i].p_frag;
                SW16(d_partitions[i].p_cpg);
        }
#undef SW32
#undef SW16
}

uint16_t
dkcksum_re(struct disklabel *lp)
{
        uint16_t *start, *end;
        uint16_t sum = 0;

        start = (uint16_t *)lp;
        end = (uint16_t *)&lp->d_partitions[bswap16(lp->d_npartitions)];
        while (start < end)
                sum ^= *start++;
        return (sum);
}
#endif

#ifdef COMPAT_MMEYE_OLDLABEL
void
swap_mmeye_disklabel(struct disklabel *nlp, struct disklabel *olp)
{
        int i;
        uint16_t *np, *op;

#if BYTE_ORDER == BIG_ENDIAN
#define SW16(X) nlp->X = bswap16(olp->X)
#define SW32(X) nlp->X = bswap32(olp->X)
#else
#define SW16(X) nlp->X = olp->X
#define SW32(X) nlp->X = olp->X
#endif

        SW32(d_magic);
        SW16(d_type);
        SW16(d_subtype);

        op = (uint16_t *)&olp->d_typename[0];
        np = (uint16_t *)&nlp->d_typename[0];
        for (i = 0; i < sizeof(olp->d_typename) / sizeof(uint16_t); i++)
                *np++ = bswap16(*op++);

        op = (uint16_t *)&olp->d_un.un_d_packname[0];
        np = (uint16_t *)&nlp->d_un.un_d_packname[0];
        for (i = 0; i < sizeof(olp->d_un) / sizeof(uint16_t); i++)
                *np++ = bswap16(*op++);

        SW32(d_secsize);
        SW32(d_nsectors);
        SW32(d_ntracks);
        SW32(d_ncylinders);
        SW32(d_secpercyl);
        SW32(d_secperunit);

        SW16(d_sparespertrack);
        SW16(d_sparespercyl);

        SW32(d_acylinders);

        SW16(d_rpm);
        SW16(d_interleave);
        SW16(d_trackskew);              /* sector 0 skew, per track */
        SW16(d_cylskew);                /* sector 0 skew, per cylinder */
        SW32(d_headswitch);             /* head switch time, usec */
        SW32(d_trkseek);                /* track-to-track seek, usec */
        SW32(d_flags);                  /* generic flags */

        for (i = 0; i < NDDATA; i++)
                SW32(d_drivedata[i]);   /* drive-type specific information */

        for (i = 0; i < NSPARE; i++)
                SW32(d_spare[i]);       /* reserved for future use */

        SW32(d_magic2);                 /* the magic number (again) */
        SW16(d_checksum);               /* xor of data incl. partitions */

        /* filesystem and partition information: */
        SW16(d_npartitions);    /* number of partitions in following */
        SW32(d_bbsize);         /* size of boot area at sn0, bytes */
        SW32(d_sbsize);         /* max size of fs superblock, bytes */

        for (i = 0; i < MAXPARTITIONS; i++) {
                SW32(d_partitions[i].p_size);
                SW32(d_partitions[i].p_offset);
                SW32(d_partitions[i].p_fsize);
                nlp->d_partitions[i].p_fstype = olp->d_partitions[i].p_fstype;
                nlp->d_partitions[i].p_frag = olp->d_partitions[i].p_frag;
                SW16(d_partitions[i].p_cpg);
        }
#undef SW32
#undef SW16
}

uint16_t
dkcksum_mmeye(struct disklabel *lp)
{
        struct disklabel tdl;
        int i, offset;
        uint16_t *start, *end, *fstype;
        uint16_t sum = 0;

        tdl = *lp;

        for (i = 0; i < MAXPARTITIONS; i++) {
                fstype = (uint16_t *)&tdl.d_partitions[i].p_fstype;
                *fstype = bswap16(*fstype);
        }

        offset = offsetof(struct disklabel,
            d_partitions[le16toh(lp->d_npartitions)]);
        start = (uint16_t *)&tdl;
        end = start + offset;

        while (start < end)
                sum ^= *start++;

#ifdef COMPAT_MMEYE_OLDLABEL_BROKEN
        if (sum != 0 &&
            tdl.d_checksum == 0) {
                printf("disklabel: mmeye oldlabel broken found\n");
                sum = 0;        /* XXXX */
        }
#endif

        return (sum);
}
#endif

/*
 * Scan MBR for  NetBSD partition.  Return NO_MBR_SIGNATURE if no MBR found
 * Otherwise, copy valid MBR partition-table into dp, and if a NetBSD
 * partition is found, return a pointer to it; else return  NULL.
 */
static struct mbr_partition *
mbr_findslice(struct mbr_partition *dp, struct buf *bp)
{
        struct mbr_partition *ourdp = NULL;
        uint16_t *mbrmagicp;
        int i;

        /* Note: Magic number is little-endian. */
        mbrmagicp = (uint16_t *)((char *)bp->b_data + MBR_MAGIC_OFFSET);
        if (le16toh(*mbrmagicp) != MBR_MAGIC)
                return (NO_MBR_SIGNATURE);

        /* XXX how do we check veracity/bounds of this? */
        memcpy(dp, (char *)bp->b_data + MBR_PART_OFFSET,
                MBR_PART_COUNT * sizeof(*dp));

        /* look for NetBSD partition */
        for (i = 0; i < MBR_PART_COUNT; i++) {
                if (dp[i].mbrp_type == MBR_PTYPE_NETBSD) {
                        ourdp = &dp[i];
                        break;
                }
        }

        return (ourdp);
}


/*
 * Attempt to read a disk label from a device
 * using the indicated strategy routine.
 * The label must be partly set up before this:
 * secpercyl, secsize and anything required for a block i/o read
 * operation in the driver's strategy/start routines
 * must be filled in before calling us.
 *
 * If dos partition table requested, attempt to load it and
 * find disklabel inside a DOS partition. Also, if bad block
 * table needed, attempt to extract it as well. Return buffer
 * for use in signalling errors if requested.
 *
 * Returns null on success and an error string on failure.
 */
const char *
readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
    struct cpu_disklabel *osdep)
{
        struct mbr_partition *dp;
        struct partition *pp;
        struct buf *bp;
        struct disklabel *dlp;
        const char *msg = NULL;
        int dospartoff, cyl, i, *ip;

        /* minimal requirements for archetypal disk label */
        if (lp->d_secsize == 0)
                lp->d_secsize = DEV_BSIZE;
        if (lp->d_secperunit == 0)
                lp->d_secperunit = 0x1fffffff;
#if 0
        if (lp->d_ncylinders == 16383) {
                printf("disklabel: Disk > 8G ... readjusting chs %d/%d/%d to ",
                    lp->d_ncylinders, lp->d_ntracks, lp->d_nsectors);
                lp->d_ncylinders = lp->d_secperunit /  lp->d_ntracks / lp->d_nsectors;
                printf("%d/%d/%d\n",
                    lp->d_ncylinders, lp->d_ntracks, lp->d_nsectors);
        }
#endif
        lp->d_npartitions = RAW_PART + 1;
        for (i = 0; i < RAW_PART; i++) {
                lp->d_partitions[i].p_size = 0;
                lp->d_partitions[i].p_offset = 0;
        }
        if (lp->d_partitions[i].p_size == 0)
                lp->d_partitions[i].p_size = 0x1fffffff;
        lp->d_partitions[i].p_offset = 0;

        /* get a buffer and initialize it */
        bp = geteblk((int)lp->d_secsize);
        bp->b_dev = dev;

        /* do dos partitions in the process of getting disklabel? */
        dospartoff = 0;
        cyl = LABELSECTOR / lp->d_secpercyl;
        if (!osdep)
                goto nombrpart;
        dp = osdep->mbrparts;

        /* read master boot record */
        bp->b_blkno = MBR_BBSECTOR;
        bp->b_bcount = lp->d_secsize;
        bp->b_flags |= B_READ;
        bp->b_cylinder = MBR_BBSECTOR / lp->d_secpercyl;
        (*strat)(bp);

        /* if successful, wander through dos partition table */
        if (biowait(bp)) {
                msg = "dos partition I/O error";
                goto done;
        } else {
                struct mbr_partition *ourdp = NULL;

                ourdp = mbr_findslice(dp, bp);
                if (ourdp == NO_MBR_SIGNATURE)
                        goto nombrpart;

                for (i = 0; i < MBR_PART_COUNT; i++, dp++) {
                        /* Install in partition e, f, g, or h. */
                        pp = &lp->d_partitions[RAW_PART + 1 + i];
                        pp->p_offset = le32toh(dp->mbrp_start);
                        pp->p_size = le32toh(dp->mbrp_size);
                        for (ip = fat_types; *ip != -1; ip++) {
                                if (dp->mbrp_type == *ip)
                                        pp->p_fstype = FS_MSDOS;
                        }
                        if (dp->mbrp_type == MBR_PTYPE_LNXEXT2)
                                pp->p_fstype = FS_EX2FS;

                        if (dp->mbrp_type == MBR_PTYPE_NTFS)
                                pp->p_fstype = FS_NTFS;

                        /* is this ours? */
                        if (dp == ourdp) {
                                /* need sector address for SCSI/IDE,
                                   cylinder for ESDI/ST506/RLL */
                                dospartoff = le32toh(dp->mbrp_start);
                                cyl = MBR_PCYL(dp->mbrp_scyl, dp->mbrp_ssect);

                                /* update disklabel with details */
                                lp->d_partitions[2].p_size =
                                    le32toh(dp->mbrp_size);
                                lp->d_partitions[2].p_offset =
                                    le32toh(dp->mbrp_start);
#if 0
                                if (lp->d_ntracks != dp->mbrp_ehd + 1 ||
                                    lp->d_nsectors != MBR_PSECT(dp->mbrp_esect)) {
                                        printf("disklabel: BIOS sees chs %d/%d/%d as ",
                                            lp->d_ncylinders, lp->d_ntracks,
                                            lp->d_nsectors);
                                        lp->d_ntracks = dp->mbrp_ehd + 1;
                                        lp->d_nsectors = MBR_PSECT(dp->mbrp_esect);
                                        lp->d_secpercyl = lp->d_ntracks * lp->d_nsectors;
                                        lp->d_ncylinders = lp->d_secperunit / lp->d_secpercyl;
                                        if (! lp->d_ncylinders)
                                                lp->d_ncylinders = 1;
                                        printf("%d/%d/%d\n",
                                            lp->d_ncylinders, lp->d_ntracks,
                                            lp->d_nsectors);
                                }
#endif
                        }
                }
                lp->d_npartitions = RAW_PART + 1 + i;
        }

 nombrpart:
        /* next, dig out disk label */
        bp->b_blkno = dospartoff + LABELSECTOR;
        bp->b_cylinder = cyl;
        bp->b_bcount = lp->d_secsize;
        bp->b_oflags &= ~(BO_DONE);
        bp->b_flags |= B_READ;
        (*strat)(bp);

        /* if successful, locate disk label within block and validate */
        if (biowait(bp)) {
                msg = "disk label I/O error";
                goto done;
        }
        for (dlp = (struct disklabel *)bp->b_data;
            dlp <= (struct disklabel *)((char *)bp->b_data + lp->d_secsize -
                sizeof(*dlp));
            dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
                if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC) {
                        /* disklabel is written in host's endian */
                        if (dlp->d_npartitions > MAXPARTITIONS ||
                            dkcksum(dlp) != 0)
                                msg = "disk label corrupted";
                        else {
                                *lp = *dlp;
                                msg = NULL;
                                break;
                        }
                }
#ifdef BSDDISKLABEL_EI
                if (bswap32(dlp->d_magic) == DISKMAGIC &&
                    bswap32(dlp->d_magic2) == DISKMAGIC) {
                        /* disklabel is written in reversed endian */
                        if (bswap16(dlp->d_npartitions) > MAXPARTITIONS ||
                            dkcksum_re(dlp) != 0)
                                msg = "disk label corrupted";
                        else {
                                swap_endian_disklabel(lp, dlp);
                                /* recalculate cksum in host's endian */
                                lp->d_checksum = 0;
                                lp->d_checksum = dkcksum(lp);

                                msg = NULL;
                                break;
                        }
                }
#endif
#ifdef COMPAT_MMEYE_OLDLABEL
                if (le32toh(dlp->d_magic) == DISKMAGIC &&
                    le32toh(dlp->d_magic2) == DISKMAGIC) {
                        if (le16toh(dlp->d_npartitions) > MAXPARTITIONS ||
                            dkcksum_mmeye(dlp) != 0)
                                msg = "disk label corrupted";
                        else {
                                /* disklabel is written in old mmeye's way */
                                swap_mmeye_disklabel(lp, dlp);
                                /* recalculate cksum in host's endian */
                                lp->d_checksum = 0;
                                lp->d_checksum = dkcksum(lp);

                                msg = NULL;
                                break;
                        }
                }
#endif
                if (msg == NULL)
                        msg = "no disk label";
        }

 done:
        brelse(bp, 0);
        return (msg);
}

/*
 * Write disk label back to device after modification.
 */
int
writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
    struct cpu_disklabel *osdep)
{
        struct mbr_partition *dp;
        struct buf *bp;
        struct disklabel *dlp;
        int error, dospartoff, cyl;

        /* get a buffer and initialize it */
        bp = geteblk((int)lp->d_secsize);
        bp->b_dev = dev;

        /* do dos partitions in the process of getting disklabel? */
        dospartoff = 0;
        cyl = LABELSECTOR / lp->d_secpercyl;
        if (!osdep)
                goto nombrpart;
        dp = osdep->mbrparts;

        /* read master boot record */
        bp->b_blkno = MBR_BBSECTOR;
        bp->b_bcount = lp->d_secsize;
        bp->b_flags |= B_READ;
        bp->b_cylinder = MBR_BBSECTOR / lp->d_secpercyl;
        (*strat)(bp);

        if ((error = biowait(bp)) == 0) {
                struct mbr_partition *ourdp = NULL;

                ourdp = mbr_findslice(dp, bp);
                if (ourdp ==  NO_MBR_SIGNATURE)
                        goto nombrpart;

                if (ourdp) {
                        /* need sector address for SCSI/IDE,
                           cylinder for ESDI/ST506/RLL */
                        dospartoff = le32toh(ourdp->mbrp_start);
                        cyl = MBR_PCYL(ourdp->mbrp_scyl, ourdp->mbrp_ssect);
                }
        }

 nombrpart:
#ifdef maybe
        /* disklabel in appropriate location? */
        if (lp->d_partitions[2].p_offset != 0
            && lp->d_partitions[2].p_offset != dospartoff) {
                error = EXDEV;
                goto done;
        }
#endif

        /* next, dig out disk label */
        bp->b_blkno = dospartoff + LABELSECTOR;
        bp->b_cylinder = cyl;
        bp->b_bcount = lp->d_secsize;
        bp->b_oflags &= ~(BO_DONE);
        bp->b_flags |= B_READ;
        (*strat)(bp);

        /* if successful, locate disk label within block and validate */
        if ((error = biowait(bp)) != 0)
                goto done;
        for (dlp = (struct disklabel *)bp->b_data;
            dlp <= (struct disklabel *)((char *)bp->b_data + lp->d_secsize -
                sizeof(*dlp));
            dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
                if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
                    dlp->d_npartitions <= MAXPARTITIONS &&
                    dkcksum(dlp) == 0) {
                        /* found disklabel in host's endian */
                        *dlp = *lp;
                        goto found;
#ifdef BSDDISKLABEL_EI
                } else if (bswap32(dlp->d_magic) == DISKMAGIC &&
                    bswap32(dlp->d_magic2) == DISKMAGIC &&
                    bswap16(dlp->d_npartitions) <= MAXPARTITIONS &&
                    dkcksum_re(dlp) == 0) {
                        /* found disklabel in the opposite endian */
                        swap_endian_disklabel(dlp, lp);
                        /* recalculate cksum in reversed endian */
                        dlp->d_checksum = 0;
                        dlp->d_checksum = dkcksum_re(dlp);
                        goto found;
#endif
#ifdef COMPAT_MMEYE_OLDLABEL
                } else if (le32toh(dlp->d_magic) == DISKMAGIC &&
                    le32toh(dlp->d_magic2) == DISKMAGIC &&
                    le16toh(dlp->d_npartitions) <= MAXPARTITIONS &&
                    dkcksum_mmeye(dlp) == 0) {
                        /* found disklabel by old mmeye's rule */
                        swap_mmeye_disklabel(dlp, lp);
                        /* recalculate cksum for it */
                        dlp->d_checksum = 0;
                        dlp->d_checksum = dkcksum_mmeye(dlp);
                        goto found;
#endif
                }
        }
        /* No valid disklabel found on disk */
        error = ESRCH;
        goto done;

 found:
        bp->b_oflags &= ~(BO_DONE);
        bp->b_flags &= ~(B_READ);
        bp->b_flags |= B_WRITE;
        (*strat)(bp);
        error = biowait(bp);

 done:
        brelse(bp, 0);
        return (error);
}