/* $NetBSD: disksubr.c,v 1.44 2026/07/14 13:34:33 thorpej Exp $ */

/*
 * Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Authors: Keith Bostic, Chris G. Demetriou
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

#include <sys/cdefs.h>                  /* RCS ID & Copyright macro defns */

__KERNEL_RCSID(0, "$NetBSD: disksubr.c,v 1.44 2026/07/14 13:34:33 thorpej Exp $");

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

#include <machine/cpu.h>
#include <machine/autoconf.h>

extern device_t bootdv;

/*
 * 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;

        /* 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;

        /* obtain buffer to probe drive with */
        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 read error";
                goto done;
        }

        dlp = (struct disklabel *)((char *)bp->b_data + LABELOFFSET);
        if (dlp->d_magic == DISKMAGIC) {
                if (dkcksum(dlp))
                        msg = "NetBSD disk label corrupted";
                else
                        *lp = *dlp;
        } else
                msg = "no disk label";

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 careful.
 */
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 */

        /*
         * The Alpha requires that the boot block be checksummed.
         * The first 63 8-bit quantites are summed into the 64th.
         */
        {
                int i;
                u_long *dp, sum;

                dp = (u_long *)bp->b_data;
                sum = 0;
                for (i = 0; i < 63; i++)
                        sum += dp[i];
                dp[63] = sum;
        }

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

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