[apple/xnu.git] / bsd / man / man5 / dir.5

.\"	$NetBSD: dir.5,v 1.5 1995/03/28 17:30:20 jtc Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)dir.5	8.3 (Berkeley) 4/19/94
.\"
.Dd April 19, 1994
.Dt DIR 5
.Os BSD 4.2
.Sh NAME
.Nm dir ,
.Nm dirent
.Nd directory file format
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/dir.h>
.Sh DESCRIPTION
Directories provide a convenient hierarchical method of grouping
files while obscuring the underlying details of the storage medium.
A directory file is differentiated from a plain file
by a flag in its
.Xr inode 5
entry.
It consists of records (directory entries) each of which contains
information about a file and a pointer to the file itself.
Directory entries may contain other directories
as well as plain files; such nested directories are refered to as
subdirectories. 
A hierarchy of directories and files is formed in this manner
and is called a file system (or referred to as a file system tree).
.\" An entry in this tree,
.\" nested or not nested,
.\" is a pathname.
.Pp
Each directory file contains two special directory entries; one is a pointer
to the directory itself
called dot
.Ql \&.
and the other a pointer to its parent directory called dot-dot
.Ql \&.. .
Dot and dot-dot
are valid pathnames, however,
the system root directory
.Ql / ,
has no parent and dot-dot points to itself like dot.
.Pp
File system nodes are ordinary directory files on which has
been grafted a file system object, such as a physical disk or a
partitioned area of such a disk.
(See
.Xr mount 1
and
.Xr mount 8 . )
.Pp
The directory entry format is defined in the file
.Aq sys/dirent.h 
and further in the file
.Aq dirent.h .
When the macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is not defined (see
.Xr stat 2
for more information on this macro), the
.Fa dirent
structure is defined as:
.Bd -literal
/*** Excerpt from <sys/dirent.h> ***/
/*
 * The dirent structure defines the format of directory entries.
 *
 * A directory entry has a struct dirent at the front of it, containing its
 * inode number, the length of the entry, and the length of the name
 * contained in the entry.  These are followed by the name padded to a 4
 * byte boundary with null bytes.  All names are guaranteed null terminated.
 * The maximum length of a name in a directory is 255.
 */

struct dirent { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */
        ino_t      d_ino;                /* file number of entry */
        __uint16_t d_reclen;             /* length of this record */
        __uint8_t  d_type;               /* file type, see below */
        __uint8_t  d_namlen;             /* length of string in d_name */
        char    d_name[255 + 1];   /* name must be no longer than this */
};
.Ed
.Pp
However, when the macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is defined, the
.Fa dirent
structure is defined as:
.Bd -literal
/*
 * The dirent structure defines the format of directory entries.
 *
 * A directory entry has a struct dirent at the front of it, containing its
 * inode number, the length of the entry, and the length of the name
 * contained in the entry.  These are followed by the name padded to a 4
 * byte boundary with null bytes.  All names are guaranteed null terminated.
 * The maximum length of a name in a directory is 1023.
 */

struct dirent { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */
        ino_t      d_fileno;     /* file number of entry */
        __uint64_t d_seekoff;    /* seek offset (optional, used by servers) */
        __uint16_t d_reclen;     /* length of this record */
        __uint16_t d_namlen;     /* length of string in d_name */
        __uint8_t  d_type;       /* file type, see below */
        char    d_name[1024];    /* name must be no longer than this */
};
.Ed
.Pp
In addition:
.Bd -literal
/*
 * File types
 */
#define DT_UNKNOWN       0
#define DT_FIFO          1
#define DT_CHR           2
#define DT_DIR           4
#define DT_BLK           6
#define DT_REG           8
#define DT_LNK          10
#define DT_SOCK         12
#define DT_WHT          14

.Ed
-----------------------------------------
.Bd -literal
/*** Excerpt from <dirent.h> ***/

#define d_fileno        d_ino        /* backward compatibility */

/* definitions for library routines operating on directories. */
#define DIRBLKSIZ       1024

struct _telldir;                /* see telldir.h */

/* structure describing an open directory. */
typedef struct _dirdesc {
        int     __dd_fd;      /* file descriptor associated with directory */
        long    __dd_loc;     /* offset in current buffer */
        long    __dd_size;    /* amount of data returned by getdirentries */
        char    *__dd_buf;    /* data buffer */
        int     __dd_len;     /* size of data buffer */
        long    __dd_seek;    /* magic cookie returned by getdirentries */
        long    __dd_rewind;  /* magic cookie for rewinding */
        int     __dd_flags;   /* flags for readdir */
        pthread_mutex_t __dd_lock; /* for thread locking */
        struct _telldir *__dd_td; /* telldir position recording */
} DIR;

#define dirfd(dirp)     ((dirp)->dd_fd)

/* flags for opendir2 */
#define DTF_HIDEW       0x0001  /* hide whiteout entries */
#define DTF_NODUP       0x0002  /* don't return duplicate names */
#define DTF_REWIND      0x0004  /* rewind after reading union stack */
#define __DTF_READALL   0x0008  /* everything has been read */
.Ed
.Sh SEE ALSO
.Xr fs 5 ,
.Xr inode 5
.Sh HISTORY
A
.Nm
file format appeared in
.At v7 .
Commit	Line	Data
9bccf70c A	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
	47	Directories provide a convenient hierarchical method of grouping
	48	files while obscuring the underlying details of the storage medium.
	49	A directory file is differentiated from a plain file
	50	by a flag in its
	51	.Xr inode 5
	52	entry.
	53	It consists of records (directory entries) each of which contains
	54	information about a file and a pointer to the file itself.
	55	Directory entries may contain other directories
	56	as well as plain files; such nested directories are refered to as
	57	subdirectories.
	58	A hierarchy of directories and files is formed in this manner
	59	and 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
	64	Each directory file contains two special directory entries; one is a pointer
65	to the directory itself
66	called dot
67	.Ql \&.
68	and the other a pointer to its parent directory called dot-dot
69	.Ql \&.. .
70	Dot and dot-dot
71	are valid pathnames, however,
72	the system root directory
73	.Ql / ,
74	has no parent and dot-dot points to itself like dot.
75	.Pp
76	File system nodes are ordinary directory files on which has
77	been grafted a file system object, such as a physical disk or a
78	partitioned area of such a disk.
79	(See
80	.Xr mount 1
81	and
82	.Xr mount 8 . )
83	.Pp
84	The directory entry format is defined in the file
55e303ae A	85	.Aq sys/dirent.h
55e303ae A	86	and further in the file
b0d623f7 A	87	.Aq dirent.h .
	88	When the macro
	89	.Dv _DARWIN_FEATURE_64_BIT_INODE
6d2010ae A	90	is not defined (see
	91	.Xr stat 2
	92	for more information on this macro), the
b0d623f7 A	93	.Fa dirent
b0d623f7 A	94	structure is defined as:
9bccf70c	95	.Bd -literal
55e303ae	96	/* Excerpt from <sys/dirent.h> */
9bccf70c	97	/*
593a1d5f	98	* The dirent structure defines the format of directory entries.
55e303ae A	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.
b0d623f7	104	* The maximum length of a name in a directory is 255.
55e303ae A	105	*/
55e303ae A	106
b0d623f7 A	107	struct 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 */
9bccf70c	113	};
b0d623f7 A	114	.Ed
	115	.Pp
	116	However, when the macro
	117	.Dv _DARWIN_FEATURE_64_BIT_INODE
	118	is defined, the
b0d623f7	119	.Fa dirent
6d2010ae	120	structure is defined as:
b0d623f7 A	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	*/
9bccf70c	131
b0d623f7 A	132	struct dirent { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */
b0d623f7 A	133	ino_t d_fileno; /* file number of entry */
fe8ab488	134	__uint64_t d_seekoff; /* seek offset (optional, used by servers) */
b0d623f7 A	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
	142	In addition:
	143	.Bd -literal
55e303ae A	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
55e303ae A	157	.Ed
	158	-----------------------------------------
	159	.Bd -literal
	160	/* Excerpt from <dirent.h> */
	161
b0d623f7	162	#define d_fileno d_ino /* backward compatibility */
55e303ae	163
9bccf70c	164	/* definitions for library routines operating on directories. */
55e303ae A	165	#define DIRBLKSIZ 1024
	166
	167	struct _telldir; /* see telldir.h */
9bccf70c A	168
9bccf70c A	169	/* structure describing an open directory. */
b0d623f7 A	170	typedef 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 */
593a1d5f A	179	pthread_mutex_t __dd_lock; /* for thread locking */
593a1d5f A	180	struct _telldir __dd_td; / telldir position recording */
9bccf70c A	181	} DIR;
9bccf70c A	182
b0d623f7	183	#define dirfd(dirp) ((dirp)->dd_fd)
9bccf70c	184
55e303ae A	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 */
9bccf70c A	190	.Ed
	191	.Sh SEE ALSO
	192	.Xr fs 5 ,
	193	.Xr inode 5
	194	.Sh HISTORY
	195	A
	196	.Nm
	197	file format appeared in
	198	.At v7 .