/* $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.
 */

#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>

/*
 * Attempt to read a disk label from a device
 * using the indicated strategy routine.
 * The label must be partly set up before this:
 * secpercyl and anything required in the strategy routine
 * (e.g., sector size) must be filled in before calling us.
 * 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 *clp)
{
        struct buf *bp;
        struct disklabel *dlp;
        const char *msg = NULL;
        uint32_t secperunit;

        /* 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;

        secperunit = lp->d_secperunit;

        /* obtain buffer to probe drive with */
        bp = geteblk((int)lp->d_secsize);
        bp->b_dev = dev;

        /* Next, dig out disk label.  If successful, locate disk
         * label within block and validate.
         */
        if (disk_read_sectors(strat, lp, bp, LABELSECTOR, 1) != 0) {
                msg = "disk label read 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;
                }
        }

        if (msg == NULL) {
                msg = convertdisklabel(lp, strat, bp, secperunit);
        }

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

/*
 * Write disk label back to device after modification.
 * this means write out the Rigid disk blocks to represent the 
 * label.  Hope the user was carefull.
 */
int
writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
    struct cpu_disklabel *clp)
{
        struct buf *bp;
        struct disklabel *dlp;
        int error = 0;

        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;           /* get current label */
        (*strat)(bp);
        if ((error = biowait(bp)) != 0)
                goto done;

        dlp = (struct disklabel *)((char *)bp->b_data + LABELOFFSET);
        *dlp = *lp;     /* struct assignment */

        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);
}