1/* $NetBSD: dir.h,v 1.25 2015/09/01 06:16:03 dholland Exp $ */
2
3/*
4 * Copyright (c) 1982, 1986, 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * @(#)dir.h 8.5 (Berkeley) 4/27/95
37 */
38
39#ifndef _UFS_UFS_DIR_H_
40#define _UFS_UFS_DIR_H_
41
42/*
43 * Theoretically, directories can be more than 2Gb in length; however, in
44 * practice this seems unlikely. So, we define the type doff_t as a 32-bit
45 * quantity to keep down the cost of doing lookup on a 32-bit machine.
46 */
47#define doff_t int32_t
48#define UFS_MAXDIRSIZE (0x7fffffff)
49
50/*
51 * A directory consists of some number of blocks of UFS_DIRBLKSIZ
52 * bytes, where UFS_DIRBLKSIZ is chosen such that it can be transferred
53 * to disk in a single atomic operation (e.g. 512 bytes on most machines).
54 *
55 * Each UFS_DIRBLKSIZ byte block contains some number of directory entry
56 * structures, which are of variable length. Each directory entry has
57 * a struct direct at the front of it, containing its inode number,
58 * the length of the entry, and the length of the name contained in
59 * the entry. These are followed by the name padded to a 4 byte boundary.
60 * All names are guaranteed null terminated.
61 * The maximum length of a name in a directory is FFS_MAXNAMLEN.
62 *
63 * The macro UFS_DIRSIZ(fmt, dp) gives the amount of space required to represent
64 * a directory entry. Free space in a directory is represented by
65 * entries which have dp->d_reclen > DIRSIZ(fmt, dp). All UFS_DIRBLKSIZ bytes
66 * in a directory block are claimed by the directory entries. This
67 * usually results in the last entry in a directory having a large
68 * dp->d_reclen. When entries are deleted from a directory, the
69 * space is returned to the previous entry in the same directory
70 * block by increasing its dp->d_reclen. If the first entry of
71 * a directory block is free, then its dp->d_ino is set to 0.
72 * Entries other than the first in a directory do not normally have
73 * dp->d_ino set to 0.
74 */
75#undef UFS_DIRBLKSIZ
76#define UFS_DIRBLKSIZ DEV_BSIZE
77#define FFS_MAXNAMLEN 255
78#define APPLEUFS_DIRBLKSIZ 1024
79
80#define d_ino d_fileno
81struct direct {
82 u_int32_t d_fileno; /* inode number of entry */
83 u_int16_t d_reclen; /* length of this record */
84 u_int8_t d_type; /* file type, see below */
85 u_int8_t d_namlen; /* length of string in d_name */
86 char d_name[FFS_MAXNAMLEN + 1];/* name with length <= FFS_MAXNAMLEN */
87};
88
89/*
90 * File types
91 */
92#define DT_UNKNOWN 0
93#define DT_FIFO 1
94#define DT_CHR 2
95#define DT_DIR 4
96#define DT_BLK 6
97#define DT_REG 8
98#define DT_LNK 10
99#define DT_SOCK 12
100#define DT_WHT 14
101
102/*
103 * Convert between stat structure types and directory types.
104 */
105#define IFTODT(mode) (((mode) & 0170000) >> 12)
106#define DTTOIF(dirtype) ((dirtype) << 12)
107
108/*
109 * The UFS_DIRSIZ macro gives the minimum record length which will hold
110 * the directory entry. This requires the amount of space in struct direct
111 * without the d_name field, plus enough space for the name with a terminating
112 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
113 */
114#define UFS_DIRECTSIZ(namlen) \
115 ((sizeof(struct direct) - (FFS_MAXNAMLEN+1)) + (((namlen)+1 + 3) &~ 3))
116
117#if (BYTE_ORDER == LITTLE_ENDIAN)
118#define UFS_DIRSIZ(oldfmt, dp, needswap) \
119 (((oldfmt) && !(needswap)) ? \
120 UFS_DIRECTSIZ((dp)->d_type) : UFS_DIRECTSIZ((dp)->d_namlen))
121#else
122#define UFS_DIRSIZ(oldfmt, dp, needswap) \
123 (((oldfmt) && (needswap)) ? \
124 UFS_DIRECTSIZ((dp)->d_type) : UFS_DIRECTSIZ((dp)->d_namlen))
125#endif
126
127/*
128 * UFS_OLDDIRFMT and UFS_NEWDIRFMT are code numbers for a directory
129 * format change that happened in ffs a long time ago. (Back in the
130 * 80s, if I'm not mistaken.)
131 *
132 * These code numbers do not appear on disk. They're generated from
133 * runtime logic that is cued by other things, which is why
134 * UFS_OLDDIRFMT is confusingly 1 and UFS_NEWDIRFMT is confusingly 0.
135 *
136 * Relatedly, the FFS_EI byte swapping logic for directories is a
137 * horrible mess. For example, to access the namlen field, one
138 * currently does the following:
139 *
140 * #if (BYTE_ORDER == LITTLE_ENDIAN)
141 * swap = (UFS_IPNEEDSWAP(VTOI(vp)) == 0);
142 * #else
143 * swap = (UFS_IPNEEDSWAP(VTOI(vp)) != 0);
144 * #endif
145 * return ((FSFMT(vp) && swap) ? dp->d_type : dp->d_namlen);
146 *
147 * UFS_IPNEEDSWAP() returns true if the volume is opposite-endian. This
148 * horrible "swap" logic is cutpasted all over everywhere but amounts
149 * to the following:
150 *
151 * running code volume lfs_dobyteswap "swap"
152 * ----------------------------------------------------------
153 * LITTLE_ENDIAN LITTLE_ENDIAN false true
154 * LITTLE_ENDIAN BIG_ENDIAN true false
155 * BIG_ENDIAN LITTLE_ENDIAN true true
156 * BIG_ENDIAN BIG_ENDIAN false false
157 *
158 * which you'll note boils down to "volume is little-endian".
159 *
160 * Meanwhile, FSFMT(vp) yields UFS_OLDDIRFMT or UFS_NEWDIRFMT via
161 * perverted logic of its own. Since UFS_OLDDIRFMT is 1 (contrary to
162 * what one might expect approaching this cold) what this mess means
163 * is: on OLDDIRFMT volumes that are little-endian, we read the
164 * namlen value out of the type field. This is because on OLDDIRFMT
165 * volumes there is no d_type field, just a 16-bit d_namlen; so if
166 * the 16-bit d_namlen is little-endian, the useful part of it is
167 * in the first byte, which in the NEWDIRFMT structure is the d_type
168 * field.
169 */
170
171#define UFS_OLDDIRFMT 1
172#define UFS_NEWDIRFMT 0
173
174/*
175 * Template for manipulating directories. Should use struct direct's,
176 * but the name field is FFS_MAXNAMLEN - 1, and this just won't do.
177 */
178struct dirtemplate {
179 u_int32_t dot_ino;
180 int16_t dot_reclen;
181 u_int8_t dot_type;
182 u_int8_t dot_namlen;
183 char dot_name[4]; /* must be multiple of 4 */
184 u_int32_t dotdot_ino;
185 int16_t dotdot_reclen;
186 u_int8_t dotdot_type;
187 u_int8_t dotdot_namlen;
188 char dotdot_name[4]; /* ditto */
189};
190
191/*
192 * This is the old format of directories, sans type element.
193 */
194struct odirtemplate {
195 u_int32_t dot_ino;
196 int16_t dot_reclen;
197 u_int16_t dot_namlen;
198 char dot_name[4]; /* must be multiple of 4 */
199 u_int32_t dotdot_ino;
200 int16_t dotdot_reclen;
201 u_int16_t dotdot_namlen;
202 char dotdot_name[4]; /* ditto */
203};
204#endif /* !_UFS_UFS_DIR_H_ */
205