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.\" $Id: dir.5,v 1.7 1997/02/22 13:25:58 peter Exp $ 34.\" 35.Dd April 19, 1994 36.Dt DIR 5 37.Os BSD 4.2 38.Sh NAME 39.Nm dir , 40.Nm dirent 41.Nd directory file format 42.Sh SYNOPSIS 43.Fd #include <sys/types.h> 44.Fd #include <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 dirent.h : 85.Bd -literal 86#ifndef _DIRENT_H_ 87#define _DIRENT_H_ 88 89/* 90* A directory entry has a struct dirent at the front of it, containing its 91* inode number, the length of the entry, and the length of the name 92* contained in the entry. These are followed by the name padded to a 4 93* byte boundary with null bytes. All names are guaranteed null terminated. 94* The maximum length of a name in a directory is MAXNAMLEN. 95*/ 96 97struct dirent { 98 u_long d_fileno; /* file number of entry */ 99 u_short d_reclen; /* length of this record */ 100 u_char d_type; /* file type, see below */ 101 u_char d_namlen; /* length of string in d_name */ 102#ifdef _POSIX_SOURCE 103 char d_name[255 + 1]; /* maximum name length */ 104#else 105#define MAXNAMLEN 255 106 char d_name[MAXNAMLEN + 1]; /* maximum name length */ 107#endif 108 109}; 110 111/* 112 * File types 113 */ 114#define DT_UNKNOWN 0 115#define DT_FIFO 1 116#define DT_CHR 2 117#define DT_DIR 4 118#define DT_BLK 6 119#define DT_REG 8 120#define DT_LKN 10 121#define DT_SOCK 12 122#define DT_WHT 14 123 124#ifdef _POSIX_SOURCE 125typedef void * DIR; 126#else 127 128#define d_ino d_fileno /* backward compatibility */ 129 130/* definitions for library routines operating on directories. */ 131#define DIRBLKSIZ 1024 132 133/* structure describing an open directory. */ 134typedef struct _dirdesc { 135 int dd_fd; /* file descriptor associated with directory */ 136 long dd_loc; /* offset in current buffer */ 137 long dd_size; /* amount of data returned by getdirentries */ 138 char *dd_buf; /* data buffer */ 139 int dd_len; /* size of data buffer */ 140 long dd_seek; /* magic cookie returned by getdirentries */ 141 long dd_rewind;/* magic cookie for rewinding */ 142} DIR; 143 144#define dirfd(dirp) ((dirp)->dd_fd) 145 146#ifndef NULL 147#define NULL 0 148#endif 149 150#endif /* _POSIX_SOURCE */ 151 152#ifndef KERNEL 153 154#include <sys/cdefs.h> 155 156#endif /* !KERNEL */ 157 158#endif /* !_DIRENT_H_ */ 159.Ed 160.Sh SEE ALSO 161.Xr fs 5 , 162.Xr inode 5 163.Sh HISTORY 164A 165.Nm 166file format appeared in 167.At v7 . 168