/*      $NetBSD: disksubr.c,v 1.20 2026/07/14 13:34:34 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 1.20 2026/07/14 13:34:34 thorpej Exp $");

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

/*
 * 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 buf *bp;
        struct disklabel *dlp;
        const char *msg = NULL;

        /* 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;
        lp->d_npartitions = RAW_PART + 1;
        if (lp->d_partitions[RAW_PART].p_size == 0)
                lp->d_partitions[RAW_PART].p_size = lp->d_secperunit;
        lp->d_partitions[RAW_PART].p_offset = 0;

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

        /* next, dig out disk label */
        bp->b_dev = dev;
        bp->b_blkno = LABELSECTOR;
        bp->b_cylinder = 0;
        bp->b_bcount = lp->d_secsize;
        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, BC_INVAL);
        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 buf *bp;
        struct disklabel *dlp;
        int error;

#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

        /* get a buffer and initialize it */
        bp = geteblk((int)lp->d_secsize);
        bp->b_dev = dev;
        bp->b_blkno = LABELSECTOR;
        bp->b_cylinder = 0;
        bp->b_bcount = lp->d_secsize;
        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_cflags = BC_BUSY;
                        bp->b_flags = B_WRITE;
                        CLR(bp->b_oflags, BO_DONE);
                        (*strat)(bp);
                        error = biowait(bp);
                        goto done;
                }
        }
        error = ESRCH;

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