[apple/xnu.git] / bsd / man / man2 / getdirentries.2

.\"	$NetBSD: getdirentries.2,v 1.7 1995/10/12 15:40:50 jtc Exp $
.\"
.\" Copyright (c) 1989, 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.
.\"
.\"	@(#)getdirentries.2	8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt GETDIRENTRIES 2
.Os
.Sh NAME
.Nm getdirentries
.Nd "get directory entries in a filesystem independent format"
.Sh SYNOPSIS
.Fd #include <dirent.h>
.Fd #include <sys/types.h>
.Fd #include <sys/dirent.h>
.Ft int
.Fn getdirentries "int fd" "char *buf" "int nbytes" "long *basep"
.Sh DESCRIPTION
.Fn Getdirentries
reads directory entries from the directory
referenced by the file descriptor
.Fa fd
into the buffer pointed to by
.Fa buf ,
in a filesystem independent format.
Up to
.Fa nbytes
of data will be transferred.
.Fa Nbytes
must be greater than or equal to the
block size associated with the file,
see
.Xr stat 2 .
Some filesystems may not support
.Fn getdirentries
with buffers smaller than this size.
.Pp
The data in the buffer is a series of
.Em dirent
structures each containing the following entries:
.Bd -literal -offset indent
u_int32_t	d_fileno;             /* file number of entry */
u_int16_t	d_reclen;             /* length of this record */
u_int8_t	d_type;               /* file type, see below */
u_int8_t	d_namlen;             /* length of string in d_name */
char    	d_name[MAXNAMELEN + 1]; /* see below */
.Ed
.Pp
The
.Fa d_fileno
entry is a number which is unique for each
distinct file in the filesystem.
Files that are linked by hard links (see
.Xr link 2 )
have the same
.Fa d_fileno .
Users of 
.Fn getdirentries
should skip 
entries with 
.Fa d_fileno 
= 0, as such entries represent files which have been deleted but not yet removed from the directory entry.
The
.Fa d_reclen
entry is the length, in bytes, of the directory record.
The
.Fa d_name
entry contains a null terminated file name.
The
.Fa d_namlen
entry specifies the length of the file name excluding the null byte.
Thus the actual size of
.Fa d_name
may vary from 1 to
.Dv MAXNAMELEN
\&+ 1.
.Fa d_type
is a integer representing the type of the directory entry.  The following types are defined in 
.Aq sys/dirent.h :
.Bd -literal -offset indent
#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
.Pp
Entries may be separated by extra space.
The
.Fa d_reclen
entry may be used as an offset from the start of a
.Fa dirent
structure to the next structure, if any.
.Pp
The actual number of bytes transferred is returned.
The current position pointer associated with
.Fa fd
is set to point to the next block of entries.
The pointer may not advance by the number of bytes returned by
.Fn getdirentries .
A value of zero is returned when
the end of the directory has been reached.
.Pp
.Fn Getdirentries
writes the position of the block read into the location pointed to by
.Fa basep .
Alternatively, the current position pointer may be set and retrieved by
.Xr lseek 2 .
The current position pointer should only be set to a value returned by
.Xr lseek 2 ,
a value returned in the location pointed to by
.Fa basep ,
or zero.
.Sh NOTES
.Fn getdirentries
should rarely be used directly; instead,
.Xr opendir 3
and
.Xr readdir 3
should be used.
.Pp
As of Mac OS X 10.6,
.Fn getdirentries
is deprecated, and it is recommended that applications
use
.Xr readdir 3
rather than using
.Fn getdirentries
directly.  Due to limitations with the system call, 
.Fn getdirentries
will not work
with 64-bit inodes; in order to use
.Fn getdirentries ,
.Dv _DARWIN_NO_64_BIT_INODE
must be defined.
.Sh RETURN VALUES
If successful, the number of bytes actually transferred is returned.
Otherwise, -1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn Getdirentries
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa fd
is not a valid file descriptor open for reading.
.It Bq Er EFAULT
Either
.Fa buf
or
.Fa basep
point outside the allocated address space.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr lseek 2 ,
.Xr open 2 ,
.Xr opendir 3 ,
.Xr readdir 3
.Sh HISTORY
The
.Fn getdirentries
function first appeared in 4.4BSD.
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: getdirentries.2,v 1.7 1995/10/12 15:40:50 jtc Exp $
	2	.\"
	3	.\" Copyright (c) 1989, 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	.\" @(#)getdirentries.2 8.1 (Berkeley) 6/9/93
	35	.\"
	36	.Dd June 9, 1993
	37	.Dt GETDIRENTRIES 2
	38	.Os
	39	.Sh NAME
	40	.Nm getdirentries
	41	.Nd "get directory entries in a filesystem independent format"
	42	.Sh SYNOPSIS
b0d623f7	43	.Fd #include <dirent.h>
55e303ae A	44	.Fd #include <sys/types.h>
55e303ae A	45	.Fd #include <sys/dirent.h>
9bccf70c A	46	.Ft int
	47	.Fn getdirentries "int fd" "char buf" "int nbytes" "long basep"
	48	.Sh DESCRIPTION
	49	.Fn Getdirentries
	50	reads directory entries from the directory
	51	referenced by the file descriptor
	52	.Fa fd
	53	into the buffer pointed to by
	54	.Fa buf ,
	55	in a filesystem independent format.
	56	Up to
	57	.Fa nbytes
	58	of data will be transferred.
	59	.Fa Nbytes
	60	must be greater than or equal to the
	61	block size associated with the file,
	62	see
	63	.Xr stat 2 .
	64	Some filesystems may not support
	65	.Fn getdirentries
	66	with buffers smaller than this size.
	67	.Pp
	68	The data in the buffer is a series of
	69	.Em dirent
	70	structures each containing the following entries:
	71	.Bd -literal -offset indent
55e303ae A	72	u_int32_t d_fileno; /* file number of entry */
	73	u_int16_t d_reclen; /* length of this record */
	74	u_int8_t d_type; /* file type, see below */
	75	u_int8_t d_namlen; /* length of string in d_name */
9bccf70c A	76	char d_name[MAXNAMELEN + 1]; /* see below */
	77	.Ed
	78	.Pp
	79	The
	80	.Fa d_fileno
	81	entry is a number which is unique for each
	82	distinct file in the filesystem.
	83	Files that are linked by hard links (see
	84	.Xr link 2 )
	85	have the same
	86	.Fa d_fileno .
55e303ae A	87	Users of
	88	.Fn getdirentries
	89	should skip
	90	entries with
	91	.Fa d_fileno
	92	= 0, as such entries represent files which have been deleted but not yet removed from the directory entry.
9bccf70c A	93	The
	94	.Fa d_reclen
	95	entry is the length, in bytes, of the directory record.
	96	The
	97	.Fa d_name
	98	entry contains a null terminated file name.
	99	The
	100	.Fa d_namlen
	101	entry specifies the length of the file name excluding the null byte.
	102	Thus the actual size of
	103	.Fa d_name
	104	may vary from 1 to
	105	.Dv MAXNAMELEN
	106	\&+ 1.
55e303ae A	107	.Fa d_type
	108	is a integer representing the type of the directory entry. The following types are defined in
	109	.Aq sys/dirent.h :
	110	.Bd -literal -offset indent
	111	#define DT_UNKNOWN 0
	112	#define DT_FIFO 1
	113	#define DT_CHR 2
	114	#define DT_DIR 4
	115	#define DT_BLK 6
	116	#define DT_REG 8
	117	#define DT_LNK 10
	118	#define DT_SOCK 12
	119	#define DT_WHT 14
	120	.Ed
9bccf70c A	121	.Pp
	122	Entries may be separated by extra space.
	123	The
	124	.Fa d_reclen
	125	entry may be used as an offset from the start of a
	126	.Fa dirent
	127	structure to the next structure, if any.
	128	.Pp
	129	The actual number of bytes transferred is returned.
	130	The current position pointer associated with
	131	.Fa fd
	132	is set to point to the next block of entries.
	133	The pointer may not advance by the number of bytes returned by
	134	.Fn getdirentries .
	135	A value of zero is returned when
	136	the end of the directory has been reached.
	137	.Pp
	138	.Fn Getdirentries
	139	writes the position of the block read into the location pointed to by
	140	.Fa basep .
	141	Alternatively, the current position pointer may be set and retrieved by
	142	.Xr lseek 2 .
	143	The current position pointer should only be set to a value returned by
	144	.Xr lseek 2 ,
	145	a value returned in the location pointed to by
	146	.Fa basep ,
	147	or zero.
b0d623f7 A	148	.Sh NOTES
	149	.Fn getdirentries
	150	should rarely be used directly; instead,
	151	.Xr opendir 3
	152	and
	153	.Xr readdir 3
	154	should be used.
	155	.Pp
	156	As of Mac OS X 10.6,
	157	.Fn getdirentries
	158	is deprecated, and it is recommended that applications
	159	use
	160	.Xr readdir 3
	161	rather than using
	162	.Fn getdirentries
	163	directly. Due to limitations with the system call,
	164	.Fn getdirentries
	165	will not work
	166	with 64-bit inodes; in order to use
	167	.Fn getdirentries ,
	168	.Dv _DARWIN_NO_64_BIT_INODE
	169	must be defined.
9bccf70c A	170	.Sh RETURN VALUES
	171	If successful, the number of bytes actually transferred is returned.
	172	Otherwise, -1 is returned and the global variable
	173	.Va errno
	174	is set to indicate the error.
	175	.Sh ERRORS
	176	.Fn Getdirentries
	177	will fail if:
	178	.Bl -tag -width Er
	179	.It Bq Er EBADF
	180	.Fa fd
	181	is not a valid file descriptor open for reading.
	182	.It Bq Er EFAULT
	183	Either
	184	.Fa buf
	185	or
	186	.Fa basep
	187	point outside the allocated address space.
	188	.It Bq Er EIO
	189	An
	190	.Tn I/O
	191	error occurred while reading from or writing to the file system.
	192	.El
	193	.Sh SEE ALSO
2d21ac55	194	.Xr lseek 2 ,
b0d623f7 A	195	.Xr open 2 ,
	196	.Xr opendir 3 ,
	197	.Xr readdir 3
9bccf70c A	198	.Sh HISTORY
	199	The
	200	.Fn getdirentries
	201	function first appeared in 4.4BSD.