[unix-history] / usr / src / sys / stand.att / bmap.c

/*-
* Copyright (c) 1982, 1988 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.proprietary.c%
*
*      @(#)bmap.c      7.4 (Berkeley) %G%
*/

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

#define NBUFS   4
static char     b[NBUFS][MAXBSIZE];
static daddr_t  blknos[NBUFS];

daddr_t
bmap(io, bn)
       register struct iob *io;
       daddr_t bn;
{
       register struct dinode *ip;
       int i, j, sh;
       daddr_t nb, *bap;

       ip = &io->i_ino;
       if (bn < 0) {
               printf("bn negative\n");
               return ((daddr_t)0);
       }

       /* The first NDADDR blocks are direct blocks. */
       if(bn < NDADDR) {
               nb = ip->di_db[bn];
               return (nb);
       }

       /* Determine the number of levels of indirection. */
       sh = 1;
       bn -= NDADDR;
       for (j = NIADDR; j > 0; j--) {
               sh *= NINDIR(&io->i_fs);
               if (bn < sh)
                       break;
               bn -= sh;
       }
       if (j == 0) {
               printf("bn ovf %ld\n", bn);
               return ((daddr_t)0);
       }

       /* Get the first indirect block address. */
       nb = ip->di_ib[NIADDR - j];
       if (nb == 0) {
               printf("bn void %ld\n",bn);
               return ((daddr_t)0);
       }

       /* Get the indirect blocks. */
       for (; j <= NIADDR; j++) {
               if (blknos[j] != nb) {
                       io->i_bn = fsbtodb(&io->i_fs, nb) + io->i_boff;
                       io->i_ma = b[j];
                       io->i_cc = io->i_fs.fs_bsize;
                       if (devread(io) != io->i_fs.fs_bsize) {
                               if (io->i_error)
                                       errno = io->i_error;
                               printf("bn %ld: read error\n", io->i_bn);
                               return ((daddr_t)0);
                       }
                       blknos[j] = nb;
               }
               bap = (daddr_t *)b[j];
               sh /= NINDIR(&io->i_fs);
               i = (bn / sh) % NINDIR(&io->i_fs);
               nb = bap[i];
               if(nb == 0) {
                       printf("bn void %ld\n",bn);
                       return ((daddr_t)0);
               }
       }
       return (nb);
}