1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)dir.5 8.3 (Berkeley) 4/19/94 33.\" $FreeBSD: src/share/man/man5/dir.5,v 1.12.2.5 2001/12/17 11:30:13 ru Exp $ 34.\" $DragonFly: src/share/man/man5/dir.5,v 1.2 2003/06/17 04:37:00 dillon Exp $ 35.\" 36.Dd April 19, 1994 37.Dt DIR 5 38.Os 39.Sh NAME 40.Nm dir , 41.Nm dirent 42.Nd directory file format 43.Sh SYNOPSIS 44.In dirent.h 45.Sh DESCRIPTION 46Directories provide a convenient hierarchical method of grouping 47files while obscuring the underlying details of the storage medium. 48A directory file is differentiated from a plain file 49by a flag in its 50.Xr inode 5 51entry. 52It consists of records (directory entries) each of which contains 53information about a file and a pointer to the file itself. 54Directory entries may contain other directories 55as well as plain files; such nested directories are referred to as 56subdirectories. 57A hierarchy of directories and files is formed in this manner 58and is called a file system (or referred to as a file system tree). 59.\" An entry in this tree, 60.\" nested or not nested, 61.\" is a pathname. 62.Pp 63Each directory file contains two special directory entries; one is a pointer 64to the directory itself 65called dot 66.Ql .\& 67and the other a pointer to its parent directory called dot-dot 68.Ql \&.. . 69Dot and dot-dot 70are valid pathnames, however, 71the system root directory 72.Ql / , 73has no parent and dot-dot points to itself like dot. 74.Pp 75File system nodes are ordinary directory files on which has 76been grafted a file system object, such as a physical disk or a 77partitioned area of such a disk. 78(See 79.Xr mount 2 80and 81.Xr mount 8 . ) 82.Pp 83The directory entry format is defined in the file 84.Aq sys/dirent.h 85(which should not be included directly by applications): 86.Bd -literal 87#ifndef _SYS_DIRENT_H_ 88#define _SYS_DIRENT_H_ 89 90#include <machine/ansi.h> 91 92/* 93 * The dirent structure defines the format of directory entries returned by 94 * the getdirentries(2) system call. 95 * 96 * A directory entry has a struct dirent at the front of it, containing its 97 * inode number, the length of the entry, and the length of the name 98 * contained in the entry. These are followed by the name padded to a 4 99 * byte boundary with null bytes. All names are guaranteed null terminated. 100 * The maximum length of a name in a directory is MAXNAMLEN. 101 */ 102 103struct dirent { 104 __uint32_t d_fileno; /* file number of entry */ 105 __uint16_t d_reclen; /* length of this record */ 106 __uint8_t d_type; /* file type, see below */ 107 __uint8_t d_namlen; /* length of string in d_name */ 108#ifdef _POSIX_SOURCE 109 char d_name[255 + 1]; /* name must be no longer than this */ 110#else 111#define MAXNAMLEN 255 112 char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */ 113#endif 114}; 115 116/* 117 * File types 118 */ 119#define DT_UNKNOWN 0 120#define DT_FIFO 1 121#define DT_CHR 2 122#define DT_DIR 4 123#define DT_BLK 6 124#define DT_REG 8 125#define DT_LNK 10 126#define DT_SOCK 12 127#define DT_WHT 14 128 129/* 130 * Convert between stat structure types and directory types. 131 */ 132#define IFTODT(mode) (((mode) & 0170000) >> 12) 133#define DTTOIF(dirtype) ((dirtype) << 12) 134 135/* 136 * The _GENERIC_DIRSIZ macro gives the minimum record length which will hold 137 * the directory entry. This requires the amount of space in struct direct 138 * without the d_name field, plus enough space for the name with a terminating 139 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary. 140 */ 141#define _GENERIC_DIRSIZ(dp) \ 142 ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3)) 143 144#ifdef _KERNEL 145#define GENERIC_DIRSIZ(dp) _GENERIC_DIRSIZ(dp) 146#endif 147 148#endif /* !_SYS_DIRENT_H_ */ 149.Ed 150.Sh SEE ALSO 151.Xr fs 5 , 152.Xr inode 5 153.Sh BUGS 154The usage of the member d_type of struct dirent is unportable as it is 155.Fx Ns -specific . 156It also may fail on certain filesystems, for example the cd9660 filesystem. 157.Sh HISTORY 158A 159.Nm 160file format appeared in 161.At v7 . 162