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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 1.3 2003/11/09 02:34:03 dillon Exp $
42 .Nd directory file format
46 Directories provide a convenient hierarchical method of grouping
47 files while obscuring the underlying details of the storage medium.
48 A directory file is differentiated from a plain file
52 It consists of records (directory entries) each of which contains
53 information about a file and a pointer to the file itself.
54 Directory entries may contain other directories
55 as well as plain files; such nested directories are referred to as
57 A hierarchy of directories and files is formed in this manner
58 and is called a file system (or referred to as a file system tree).
59 .\" An entry in this tree,
60 .\" nested or not nested,
63 Each directory file contains two special directory entries; one is a pointer
64 to the directory itself
67 and the other a pointer to its parent directory called dot-dot
70 are valid pathnames, however,
71 the system root directory
73 has no parent and dot-dot points to itself like dot.
75 File system nodes are ordinary directory files on which has
76 been grafted a file system object, such as a physical disk or a
77 partitioned area of such a disk.
83 The directory entry format is defined in the file
85 (which should not be included directly by applications):
87 #ifndef _SYS_DIRENT_H_
88 #define _SYS_DIRENT_H_
90 #include <machine/stdint.h>
93 * The dirent structure defines the format of directory entries returned by
94 * the getdirentries(2) system call.
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.
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 */
109 char d_name[255 + 1]; /* name must be no longer than this */
111 #define MAXNAMLEN 255
112 char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */
130 * Convert between stat structure types and directory types.
132 #define IFTODT(mode) (((mode) & 0170000) >> 12)
133 #define DTTOIF(dirtype) ((dirtype) << 12)
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.
141 #define _GENERIC_DIRSIZ(dp) \
142 ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
145 #define GENERIC_DIRSIZ(dp) _GENERIC_DIRSIZ(dp)
148 #endif /* !_SYS_DIRENT_H_ */
154 The usage of the member d_type of struct dirent is unportable as it is
156 It also may fail on certain filesystems, for example the cd9660 filesystem.
160 file format appeared in