BSD 4_4_Lite1 release

[unix-history] / usr / src / sys / hp300 / stand / label.c

/*
* Copyright (c) 1992 University of Utah.
* Copyright (c) 1982, 1986, 1988, 1993
*      The Regents of the University of California.  All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 4. 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.
*
* from: Utah $Hdr: label.c 1.1 92/12/05$
*
*      @(#)label.c     8.1 (Berkeley) 6/10/93
*/

/*
* Derived from routines in ufs/ufs/ufs_disksubr.c.
*/

#include <sys/param.h>
#include <sys/disklabel.h>
#include <stand.att/saio.h>

/*
* Attempt to read a disk label from a device using the indicated stategy
* routine.  Returns NULL on success and an error string on failure.
*/
char *
readdisklabel(io, strat, lp)
       struct iob *io;
       int (*strat)();
       register struct disklabel *lp;
{
       struct iob liob;
       struct disklabel *dlp;
       char *msg = NULL;

       liob.i_adapt = io->i_adapt;
       liob.i_ctlr = io->i_ctlr;
       liob.i_unit = io->i_unit;
       liob.i_part = 2;
       liob.i_boff = 0;
       liob.i_cyloff = 0;
       liob.i_bn = LABELSECTOR;
       liob.i_ma = liob.i_buf;
       liob.i_cc = lp->d_secsize ? lp->d_secsize : DEV_BSIZE;
       if ((*strat)(&liob, F_READ) == -1)
               return ("I/O error");

       for (dlp = (struct disklabel *)liob.i_buf;
            dlp <= (struct disklabel *)(liob.i_buf+DEV_BSIZE-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))
                       msg = "disk label corrupted";
               else {
                       *lp = *dlp;
                       msg = NULL;
                       break;
               }
       }
       return (msg);
}

/*
* Compute checksum for disk label.
*/
dkcksum(lp)
       register struct disklabel *lp;
{
       register u_short *start, *end;
       register u_short sum = 0;

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