1 /* $NetBSD: ufs_bmap.c,v 1.14 2004/06/20 22:20:18 jmc Exp $ */
2 /* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */
3
4 /*-
5 * SPDX-License-Identifier: BSD-3-Clause
6 *
7 * Copyright (c) 1989, 1991, 1993
8 * The Regents of the University of California. All rights reserved.
9 * (c) UNIX System Laboratories, Inc.
10 * All or some portions of this file are derived from material licensed
11 * to the University of California by American Telephone and Telegraph
12 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
13 * the permission of UNIX System Laboratories, Inc.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 *
39 * @(#)ufs_bmap.c 8.8 (Berkeley) 8/11/95
40 */
41
42 #include <sys/cdefs.h>
43 __FBSDID("$FreeBSD: stable/12/usr.sbin/makefs/ffs/ufs_bmap.c 326025 2017-11-20 19:49:47Z pfg $");
44
45 #include <sys/param.h>
46 #include <sys/time.h>
47
48 #include <assert.h>
49 #include <errno.h>
50 #include <strings.h>
51
52 #include "makefs.h"
53
54 #include <ufs/ufs/dinode.h>
55 #include <ufs/ffs/fs.h>
56
57 #include "ffs/ufs_bswap.h"
58 #include "ffs/ufs_inode.h"
59 #include "ffs/ffs_extern.h"
60
61 /*
62 * Create an array of logical block number/offset pairs which represent the
63 * path of indirect blocks required to access a data block. The first "pair"
64 * contains the logical block number of the appropriate single, double or
65 * triple indirect block and the offset into the inode indirect block array.
66 * Note, the logical block number of the inode single/double/triple indirect
67 * block appears twice in the array, once with the offset into the i_ffs_ib and
68 * once with the offset into the page itself.
69 */
70 int
ufs_getlbns(struct inode * ip,daddr_t bn,struct indir * ap,int * nump)71 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
72 {
73 daddr_t metalbn, realbn;
74 int64_t blockcnt;
75 int lbc;
76 int i, numlevels, off;
77 u_long lognindir;
78
79 lognindir = ffs(NINDIR(ip->i_fs)) - 1;
80 if (nump)
81 *nump = 0;
82 numlevels = 0;
83 realbn = bn;
84 if ((long)bn < 0)
85 bn = -(long)bn;
86
87 assert (bn >= UFS_NDADDR);
88
89 /*
90 * Determine the number of levels of indirection. After this loop
91 * is done, blockcnt indicates the number of data blocks possible
92 * at the given level of indirection, and UFS_NIADDR - i is the number
93 * of levels of indirection needed to locate the requested block.
94 */
95
96 bn -= UFS_NDADDR;
97 for (lbc = 0, i = UFS_NIADDR;; i--, bn -= blockcnt) {
98 if (i == 0)
99 return (EFBIG);
100
101 lbc += lognindir;
102 blockcnt = (int64_t)1 << lbc;
103
104 if (bn < blockcnt)
105 break;
106 }
107
108 /* Calculate the address of the first meta-block. */
109 if (realbn >= 0)
110 metalbn = -(realbn - bn + UFS_NIADDR - i);
111 else
112 metalbn = -(-realbn - bn + UFS_NIADDR - i);
113
114 /*
115 * At each iteration, off is the offset into the bap array which is
116 * an array of disk addresses at the current level of indirection.
117 * The logical block number and the offset in that block are stored
118 * into the argument array.
119 */
120 ap->in_lbn = metalbn;
121 ap->in_off = off = UFS_NIADDR - i;
122 ap++;
123 for (++numlevels; i <= UFS_NIADDR; i++) {
124 /* If searching for a meta-data block, quit when found. */
125 if (metalbn == realbn)
126 break;
127
128 lbc -= lognindir;
129 blockcnt = (int64_t)1 << lbc;
130 off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
131
132 ++numlevels;
133 ap->in_lbn = metalbn;
134 ap->in_off = off;
135 ++ap;
136
137 metalbn -= -1 + (off << lbc);
138 }
139 if (nump)
140 *nump = numlevels;
141 return (0);
142 }
143