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 1.9 1998/02/24 02:39:00 bde 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 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/* 91 * The dirent structure defines the format of directory entries returned by 92 * the getdirentries(2) system call. 93 * 94 * A directory entry has a struct dirent at the front of it, containing its 95 * inode number, the length of the entry, and the length of the name 96 * contained in the entry. These are followed by the name padded to a 4 97 * byte boundary with null bytes. All names are guaranteed null terminated. 98 * The maximum length of a name in a directory is MAXNAMLEN. 99 */ 100 101struct dirent { 102 u_int32_t d_fileno; /* file number of entry */ 103 u_int16_t d_reclen; /* length of this record */ 104 u_int8_t d_type; /* file type, see below */ 105 u_int8_t d_namlen; /* length of string in d_name */ 106#ifdef _POSIX_SOURCE 107 char d_name[255 + 1]; /* name must be no longer than this */ 108#else 109#define MAXNAMLEN 255 110 char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */ 111#endif 112}; 113 114/* 115 * File types 116 */ 117#define DT_UNKNOWN 0 118#define DT_FIFO 1 119#define DT_CHR 2 120#define DT_DIR 4 121#define DT_BLK 6 122#define DT_REG 8 123#define DT_LNK 10 124#define DT_SOCK 12 125#define DT_WHT 14 126 127/* 128 * Convert between stat structure types and directory types. 129 */ 130#define IFTODT(mode) (((mode) & 0170000) >> 12) 131#define DTTOIF(dirtype) ((dirtype) << 12) 132 133/* 134 * The _GENERIC_DIRSIZ macro gives the minimum record length which will hold 135 * the directory entry. This requires the amount of space in struct direct 136 * without the d_name field, plus enough space for the name with a terminating 137 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary. 138 */ 139#define _GENERIC_DIRSIZ(dp) \ 140 ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3)) 141 142#ifdef KERNEL 143#define GENERIC_DIRSIZ(dp) _GENERIC_DIRSIZ(dp) 144#endif 145 146#endif /* !_SYS_DIRENT_H_ */ 147.Ed 148.Sh SEE ALSO 149.Xr fs 5 , 150.Xr inode 5 151.Sh BUGS 152The usage of the member d_type of struct dirent is unportable as it is FreeBSD-specific. 153It also may fail on certain filesystems, for example the cd9660 filesystem. 154.Sh HISTORY 155A 156.Nm 157file format appeared in 158.At v7 . 159