usr/src/sys.386bsd/i386/stand/bmap.c

/*
 * Copyright (c) 1982, 1986, 1989 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. 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.
 *
 *      derived from: @(#)ufs_bmap.c    7.13 (Berkeley) 5/8/91
 */

#include "param.h"
#include "dinode.h"
#include "fs.h"
#include "errno.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 array of block pointers described by the dinode.
 */
extern struct fs *fs;
extern int bdev;

static daddr_t bap[2*1024];
static daddr_t bnobap;

bmap(dip, bn, bnp)
        register struct dinode *dip;
        register daddr_t bn;
        daddr_t *bnp;
{
        register daddr_t nb;
        int i, j, sh;
        int error;

/*fprintf(stderr, "bmap %d ", bn);*/
        if (bn < 0)
                return (EFBIG);

        /*
         * The first NDADDR blocks are direct blocks
         */
        if (bn < NDADDR) {
                nb = dip->di_db[bn];
                if (nb == 0) {
                        *bnp = (daddr_t)-1;
/*fprintf(stderr, "%d\n", *bnp);*/
                        return (0);
                }
                *bnp = fsbtodb(fs, nb);
/*fprintf(stderr, "%d\n", *bnp);*/
                return (0);
        }
        /*
         * Determine the number of levels of indirection.
         */
        sh = 1;
        bn -= NDADDR;
        for (j = NIADDR; j > 0; j--) {
                sh *= NINDIR(fs);
                if (bn < sh)
                        break;
                bn -= sh;
        }
        if (j == 0)
                return (EFBIG);
        /*
         * Fetch through the indirect blocks.
         */
        nb = dip->di_ib[NIADDR - j];
        if (nb == 0) {
                *bnp = (daddr_t)-1;
/*fprintf(stderr, "%d\n", *bnp);*/
                return (0);
        }
        for (; j <= NIADDR; j++) {
                daddr_t bno = fsbtodb(fs, nb);

                if (bnobap != bno &&
(error = bread(bdev, bno, &bap,
                        (int)fs->fs_bsize))) {
                        return (error);
                }
                bnobap = bno;
                sh /= NINDIR(fs);
                i = (bn / sh) % NINDIR(fs);
                nb = bap[i];
                if (nb == 0) {
                        *bnp = (daddr_t)-1;
/*fprintf(stderr, "%d\n", *bnp);*/
                        return (0);
                }
        }
        *bnp = fsbtodb(fs, nb);
/*fprintf(stderr, "%d\n", *bnp);*/
        return (0);
}