/*      $NetBSD: disksubr.c,v 1.23 2026/07/14 13:34:35 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: disksubr.c,v 1.23 2026/07/14 13:34:35 thorpej Exp $");

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

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

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

/* 
 * 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;
        u_int16_t *mbrmagicp;
        int i;

        /* Note: Magic number is little-endian. */
        mbrmagicp = (u_int16_t *)((char*)bp->b_data + MBR_MAGIC_OFFSET);
        if (*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;

        /* 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->dosparts;

        /* 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 = dp->mbrp_start;
                        pp->p_size = dp->mbrp_size;
                        if (dp->mbrp_type == MBR_PTYPE_LNXEXT2)
                                pp->p_fstype = FS_EX2FS;

                        if (dp->mbrp_type == MBR_PTYPE_LNXSWAP)
                                pp->p_fstype = FS_SWAP;

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

                                /* update disklabel with details */
                                lp->d_partitions[2].p_size =
                                    dp->mbrp_size;
                                lp->d_partitions[2].p_offset = 
                                    dp->mbrp_start;
                        }
                }
                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) {
                        if (msg == NULL)
                                msg = "no disk label";
                } else if (dlp->d_npartitions > MAXPARTITIONS ||
                           dkcksum(dlp) != 0)
                        msg = "disk label corrupted";
                else {
                        *lp = *dlp;
                        msg = NULL;
                        break;
                }
        }

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->dosparts;

        /* 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 = ourdp->mbrp_start;
                        cyl = MBR_PCYL(ourdp->mbrp_scyl, ourdp->mbrp_ssect);
                }
        }

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 ((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 &&
                    dkcksum(dlp) == 0) {
                        *dlp = *lp;
                        bp->b_oflags &= ~(BO_DONE);
                        bp->b_flags &= ~(B_READ);
                        bp->b_flags |= B_WRITE;
                        (*strat)(bp);
                        error = biowait(bp);
                        goto done;
                }
        }
        error = ESRCH;

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