1.\" $NetBSD: dir.5,v 1.5 1995/03/28 17:30:20 jtc Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)dir.5 8.3 (Berkeley) 4/19/94 35.\" 36.Dd April 19, 1994 37.Dt DIR 5 38.Os BSD 4.2 39.Sh NAME 40.Nm dir , 41.Nm dirent 42.Nd directory file format 43.Sh SYNOPSIS 44.Fd #include <sys/types.h> 45.Fd #include <sys/dir.h> 46.Sh DESCRIPTION 47Directories provide a convenient hierarchical method of grouping 48files while obscuring the underlying details of the storage medium. 49A directory file is differentiated from a plain file 50by a flag in its 51.Xr inode 5 52entry. 53It consists of records (directory entries) each of which contains 54information about a file and a pointer to the file itself. 55Directory entries may contain other directories 56as well as plain files; such nested directories are refered to as 57subdirectories. 58A hierarchy of directories and files is formed in this manner 59and is called a file system (or referred to as a file system tree). 60.\" An entry in this tree, 61.\" nested or not nested, 62.\" is a pathname. 63.Pp 64Each directory file contains two special directory entries; one is a pointer 65to the directory itself 66called dot 67.Ql \&. 68and the other a pointer to its parent directory called dot-dot 69.Ql \&.. . 70Dot and dot-dot 71are valid pathnames, however, 72the system root directory 73.Ql / , 74has no parent and dot-dot points to itself like dot. 75.Pp 76File system nodes are ordinary directory files on which has 77been grafted a file system object, such as a physical disk or a 78partitioned area of such a disk. 79(See 80.Xr mount 1 81and 82.Xr mount 8 . ) 83.Pp 84The directory entry format is defined in the file 85.Aq sys/dirent.h 86and further in the file 87.Aq dirent.h . 88When the macro 89.Dv _DARWIN_FEATURE_64_BIT_INODE 90is not defined (see 91.Xr stat 2 92for more information on this macro), the 93.Fa dirent 94structure is defined as: 95.Bd -literal 96/*** Excerpt from <sys/dirent.h> ***/ 97/* 98 * The dirent structure defines the format of directory entries. 99 * 100 * A directory entry has a struct dirent at the front of it, containing its 101 * inode number, the length of the entry, and the length of the name 102 * contained in the entry. These are followed by the name padded to a 4 103 * byte boundary with null bytes. All names are guaranteed null terminated. 104 * The maximum length of a name in a directory is 255. 105 */ 106 107struct dirent { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */ 108 ino_t d_ino; /* file number of entry */ 109 __uint16_t d_reclen; /* length of this record */ 110 __uint8_t d_type; /* file type, see below */ 111 __uint8_t d_namlen; /* length of string in d_name */ 112 char d_name[255 + 1]; /* name must be no longer than this */ 113}; 114.Ed 115.Pp 116However, when the macro 117.Dv _DARWIN_FEATURE_64_BIT_INODE 118is defined, the 119.Fa dirent 120structure is defined as: 121.Bd -literal 122/* 123 * The dirent structure defines the format of directory entries. 124 * 125 * A directory entry has a struct dirent at the front of it, containing its 126 * inode number, the length of the entry, and the length of the name 127 * contained in the entry. These are followed by the name padded to a 4 128 * byte boundary with null bytes. All names are guaranteed null terminated. 129 * The maximum length of a name in a directory is 1023. 130 */ 131 132struct dirent { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */ 133 ino_t d_fileno; /* file number of entry */ 134 __uint64_t d_seekoff; /* seek offset (optional, used by servers) */ 135 __uint16_t d_reclen; /* length of this record */ 136 __uint16_t d_namlen; /* length of string in d_name */ 137 __uint8_t d_type; /* file type, see below */ 138 char d_name[1024]; /* name must be no longer than this */ 139}; 140.Ed 141.Pp 142In addition: 143.Bd -literal 144/* 145 * File types 146 */ 147#define DT_UNKNOWN 0 148#define DT_FIFO 1 149#define DT_CHR 2 150#define DT_DIR 4 151#define DT_BLK 6 152#define DT_REG 8 153#define DT_LNK 10 154#define DT_SOCK 12 155#define DT_WHT 14 156 157.Ed 158----------------------------------------- 159.Bd -literal 160/*** Excerpt from <dirent.h> ***/ 161 162#define d_fileno d_ino /* backward compatibility */ 163 164/* definitions for library routines operating on directories. */ 165#define DIRBLKSIZ 1024 166 167struct _telldir; /* see telldir.h */ 168 169/* structure describing an open directory. */ 170typedef struct _dirdesc { 171 int __dd_fd; /* file descriptor associated with directory */ 172 long __dd_loc; /* offset in current buffer */ 173 long __dd_size; /* amount of data returned by getdirentries */ 174 char *__dd_buf; /* data buffer */ 175 int __dd_len; /* size of data buffer */ 176 long __dd_seek; /* magic cookie returned by getdirentries */ 177 long __dd_rewind; /* magic cookie for rewinding */ 178 int __dd_flags; /* flags for readdir */ 179 pthread_mutex_t __dd_lock; /* for thread locking */ 180 struct _telldir *__dd_td; /* telldir position recording */ 181} DIR; 182 183#define dirfd(dirp) ((dirp)->dd_fd) 184 185/* flags for opendir2 */ 186#define DTF_HIDEW 0x0001 /* hide whiteout entries */ 187#define DTF_NODUP 0x0002 /* don't return duplicate names */ 188#define DTF_REWIND 0x0004 /* rewind after reading union stack */ 189#define __DTF_READALL 0x0008 /* everything has been read */ 190.Ed 191.Sh SEE ALSO 192.Xr fs 5 , 193.Xr inode 5 194.Sh HISTORY 195A 196.Nm 197file format appeared in 198.At v7 . 199