/*      $OpenBSD: ufs_bmap.c,v 1.7 2021/10/06 00:40:41 deraadt Exp $    */
/*      $NetBSD: ufs_bmap.c,v 1.18 2013/06/19 17:51:27 dholland Exp $   */
/* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */

/*
 * Copyright (c) 1989, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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. 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.
 *
 *      @(#)ufs_bmap.c  8.8 (Berkeley) 8/11/95
 */

#include <sys/time.h>

#include <assert.h>
#include <errno.h>
#include <strings.h>

#include "makefs.h"

#include <ufs/ufs/dinode.h>
#include <ufs/ffs/fs.h>

#include "ffs/ufs_inode.h"
#include "ffs/ffs_extern.h"

/*
 * Create an array of logical block number/offset pairs which represent the
 * path of indirect blocks required to access a data block.  The first "pair"
 * contains the logical block number of the appropriate single, double or
 * triple indirect block and the offset into the inode indirect block array.
 * Note, the logical block number of the inode single/double/triple indirect
 * block appears twice in the array, once with the offset into the i_ffs_ib and
 * once with the offset into the page itself.
 */
int
ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
{
        daddr_t metalbn, realbn;
        int64_t blockcnt;
        int lbc;
        int i, numlevels, off;
        u_long lognindir;

        lognindir = ffs(NINDIR(ip->i_fs)) - 1;
        if (nump)
                *nump = 0;
        numlevels = 0;
        realbn = bn;
        if ((long)bn < 0)
                bn = -(long)bn;

        assert (bn >= NDADDR);

        /*
         * Determine the number of levels of indirection.  After this loop
         * is done, blockcnt indicates the number of data blocks possible
         * at the given level of indirection, and NIADDR - i is the number
         * of levels of indirection needed to locate the requested block.
         */

        bn -= NDADDR;
        for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) {
                if (i == 0)
                        return (EFBIG);

                lbc += lognindir;
                blockcnt = (int64_t)1 << lbc;

                if (bn < blockcnt)
                        break;
        }

        /* Calculate the address of the first meta-block. */
        metalbn = -((realbn >= 0 ? realbn : -realbn) - bn + NIADDR - i);

        /*
         * At each iteration, off is the offset into the bap array which is
         * an array of disk addresses at the current level of indirection.
         * The logical block number and the offset in that block are stored
         * into the argument array.
         */
        ap->in_lbn = metalbn;
        ap->in_off = off = NIADDR - i;
        ap->in_exists = 0;
        ap++;
        for (++numlevels; i <= NIADDR; i++) {
                /* If searching for a meta-data block, quit when found. */
                if (metalbn == realbn)
                        break;

                lbc -= lognindir;
                blockcnt = (int64_t)1 << lbc;
                off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);

                ++numlevels;
                ap->in_lbn = metalbn;
                ap->in_off = off;
                ap->in_exists = 0;
                ++ap;

                metalbn -= -1 + (off << lbc);
        }
        if (nump)
                *nump = numlevels;
        return (0);
}