BSD 4_4_Lite2 release

[unix-history] / usr / src / sys / isofs / cd9660 / cd9660_bmap.c

/*-
* Copyright (c) 1994
*      The Regents of the University of California.  All rights reserved.
*
* This code is derived from software contributed to Berkeley
* by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
* Support code is derived from software contributed to Berkeley
* by Atsushi Murai (amurai@spec.co.jp).
*
* 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.
*
*      @(#)cd9660_bmap.c       8.4 (Berkeley) 12/5/94
*/

#include <sys/param.h>
#include <sys/namei.h>
#include <sys/buf.h>
#include <sys/file.h>
#include <sys/vnode.h>
#include <sys/mount.h>

#include <isofs/cd9660/iso.h>
#include <isofs/cd9660/cd9660_node.h>

/*
* Bmap converts a the logical block number of a file to its physical block
* number on the disk. The conversion is done by using the logical block
* number to index into the data block (extent) for the file.
*/
int
cd9660_bmap(ap)
       struct vop_bmap_args /* {
               struct vnode *a_vp;
               daddr_t  a_bn;
               struct vnode **a_vpp;
               daddr_t *a_bnp;
               int *a_runp;
       } */ *ap;
{
       struct iso_node *ip = VTOI(ap->a_vp);
       daddr_t lblkno = ap->a_bn;
       int bshift;

       /*
        * Check for underlying vnode requests and ensure that logical
        * to physical mapping is requested.
        */
       if (ap->a_vpp != NULL)
               *ap->a_vpp = ip->i_devvp;
       if (ap->a_bnp == NULL)
               return (0);

       /*
        * Compute the requested block number
        */
       bshift = ip->i_mnt->im_bshift;
       *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);

       /*
        * Determine maximum number of readahead blocks following the
        * requested block.
        */
       if (ap->a_runp) {
               int nblk;

               nblk = (ip->i_size >> bshift) - (lblkno + 1);
               if (nblk <= 0)
                       *ap->a_runp = 0;
               else if (nblk >= (MAXBSIZE >> bshift))
                       *ap->a_runp = (MAXBSIZE >> bshift) - 1;
               else
                       *ap->a_runp = nblk;
       }

       return (0);
}