1/* $NetBSD: dir.h,v 1.27 2019/05/05 15:07:12 christos 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 * NUL byte (dp->d_namlen+1), rounded up to a 4 byte boundary. 113 * The UFS_NAMEPAD macro gives the number bytes of padding needed including 114 * the NUL terminating byte. 115 */ 116#define DIR_ROUNDUP 4 117#define UFS_NAMEROUNDUP(namlen) (((namlen) + DIR_ROUNDUP) & ~(DIR_ROUNDUP - 1)) 118#define UFS_NAMEPAD(namlen) (DIR_ROUNDUP - ((namlen) & (DIR_ROUNDUP - 1))) 119#define UFS_DIRECTSIZ(namlen) \ 120 ((sizeof(struct direct) - (FFS_MAXNAMLEN+1)) + UFS_NAMEROUNDUP(namlen)) 121 122#if (BYTE_ORDER == LITTLE_ENDIAN) 123#define UFS_DIRSIZ(oldfmt, dp, needswap) \ 124 (((oldfmt) && !(needswap)) ? \ 125 UFS_DIRECTSIZ((dp)->d_type) : UFS_DIRECTSIZ((dp)->d_namlen)) 126#else 127#define UFS_DIRSIZ(oldfmt, dp, needswap) \ 128 (((oldfmt) && (needswap)) ? \ 129 UFS_DIRECTSIZ((dp)->d_type) : UFS_DIRECTSIZ((dp)->d_namlen)) 130#endif 131 132/* 133 * UFS_OLDDIRFMT and UFS_NEWDIRFMT are code numbers for a directory 134 * format change that happened in ffs a long time ago. (Back in the 135 * 80s, if I'm not mistaken.) 136 * 137 * These code numbers do not appear on disk. They're generated from 138 * runtime logic that is cued by other things, which is why 139 * UFS_OLDDIRFMT is confusingly 1 and UFS_NEWDIRFMT is confusingly 0. 140 * 141 * Relatedly, the FFS_EI byte swapping logic for directories is a 142 * horrible mess. For example, to access the namlen field, one 143 * currently does the following: 144 * 145 * #if (BYTE_ORDER == LITTLE_ENDIAN) 146 * swap = (UFS_IPNEEDSWAP(VTOI(vp)) == 0); 147 * #else 148 * swap = (UFS_IPNEEDSWAP(VTOI(vp)) != 0); 149 * #endif 150 * return ((FSFMT(vp) && swap) ? dp->d_type : dp->d_namlen); 151 * 152 * UFS_IPNEEDSWAP() returns true if the volume is opposite-endian. This 153 * horrible "swap" logic is cutpasted all over everywhere but amounts 154 * to the following: 155 * 156 * running code volume lfs_dobyteswap "swap" 157 * ---------------------------------------------------------- 158 * LITTLE_ENDIAN LITTLE_ENDIAN false true 159 * LITTLE_ENDIAN BIG_ENDIAN true false 160 * BIG_ENDIAN LITTLE_ENDIAN true true 161 * BIG_ENDIAN BIG_ENDIAN false false 162 * 163 * which you'll note boils down to "volume is little-endian". 164 * 165 * Meanwhile, FSFMT(vp) yields UFS_OLDDIRFMT or UFS_NEWDIRFMT via 166 * perverted logic of its own. Since UFS_OLDDIRFMT is 1 (contrary to 167 * what one might expect approaching this cold) what this mess means 168 * is: on OLDDIRFMT volumes that are little-endian, we read the 169 * namlen value out of the type field. This is because on OLDDIRFMT 170 * volumes there is no d_type field, just a 16-bit d_namlen; so if 171 * the 16-bit d_namlen is little-endian, the useful part of it is 172 * in the first byte, which in the NEWDIRFMT structure is the d_type 173 * field. 174 */ 175 176#define UFS_OLDDIRFMT 1 177#define UFS_NEWDIRFMT 0 178 179/* 180 * Template for manipulating directories. Should use struct direct's, 181 * but the name field is FFS_MAXNAMLEN - 1, and this just won't do. 182 */ 183struct dirtemplate { 184 u_int32_t dot_ino; 185 int16_t dot_reclen; 186 u_int8_t dot_type; 187 u_int8_t dot_namlen; 188 char dot_name[4]; /* must be multiple of 4 */ 189 u_int32_t dotdot_ino; 190 int16_t dotdot_reclen; 191 u_int8_t dotdot_type; 192 u_int8_t dotdot_namlen; 193 char dotdot_name[4]; /* ditto */ 194}; 195 196/* 197 * This is the old format of directories, sans type element. 198 */ 199struct odirtemplate { 200 u_int32_t dot_ino; 201 int16_t dot_reclen; 202 u_int16_t dot_namlen; 203 char dot_name[4]; /* must be multiple of 4 */ 204 u_int32_t dotdot_ino; 205 int16_t dotdot_reclen; 206 u_int16_t dotdot_namlen; 207 char dotdot_name[4]; /* ditto */ 208}; 209#endif /* !_UFS_UFS_DIR_H_ */ 210