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 81 struct 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 */ 178 struct 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 */ 194 struct 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