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

.\"	$NetBSD: pathconf.2,v 1.2 1995/02/27 12:35:22 cgd Exp $
.\"
.\" Copyright (c) 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.
.\"
.\"	@(#)pathconf.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt PATHCONF 2
.Os BSD 4
.Sh NAME
.Nm fpathconf ,
.Nm pathconf
.Nd get configurable pathname variables
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft long
.Fo fpathconf
.Fa "int fildes"
.Fa "int name"
.Fc
.Ft long
.Fo pathconf
.Fa "const char *path"
.Fa "int name"
.Fc
.Sh DESCRIPTION
.Pp
The
.Fn pathconf
and
.Fn fpathconf
functions provides a method for applications to determine the current
value of a configurable system limit or option variable associated
with a pathname or file descriptor.
.Pp
For
.Nm pathconf ,
the
.Fa path
argument is the name of a file or directory.
For
.Nm fpathconf ,
the
.Fa fildes
argument is an open file descriptor.
The
.Fa name
argument specifies the system variable to be queried.
Symbolic constants for each name value are found in the include file
.Li <unistd.h> .
.Pp
The available values are as follows:
.Pp
.Bl -tag -width "123456"
.Pp
.It Li _PC_LINK_MAX
The maximum file link count.
.It Li _PC_MAX_CANON
The maximum number of bytes in terminal canonical input line.
.It Li _PC_MAX_INPUT
The minimum maximum number of bytes for which space is available in
a terminal input queue.
.It Li _PC_NAME_MAX
The maximum number of bytes in a file name.
.It Li _PC_PATH_MAX
The maximum number of bytes in a pathname.
.It Li _PC_PIPE_BUF
The maximum number of bytes which will be written atomically to a pipe.
.It Li _PC_CHOWN_RESTRICTED
Return 1 if appropriate privileges are required for the
.Xr chown 2
system call, otherwise 0.
.It Li _PC_NO_TRUNC
Return 1 if file names longer than KERN_NAME_MAX are truncated.
.It Li _PC_VDISABLE
Returns the terminal character disabling value.
.El
.Sh RETURN VALUES
If the call to
.Nm pathconf
or
.Nm fpathconf
is not successful, \-1 is returned and
.Va errno
is set appropriately.
Otherwise, if the variable is associated with functionality that does
not have a limit in the system, \-1 is returned and
.Va errno
is not modified.
Otherwise, the current variable value is returned.
.Sh ERRORS
If any of the following conditions occur, the
.Nm pathconf
and
.Nm fpathconf
functions shall return -1 and set
.Va errno
to the corresponding value.
.Bl -tag -width ENAMETOOLONGAA
.\" ===========
.It Bq Er EINVAL
The value of the
.Fa name
argument is invalid.
.\" ===========
.It Bq Er EINVAL
The implementation does not support an association of the variable
name with the associated file.
.El
.Pp
.Fn Pathconf
will fail if:
.Bl -tag -width ENAMETOOLONGAA
.\" ===========
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.\" ===========
.It Bq Er EIO
An I/O error occurs while reading from or writing to the file system.
.\" ===========
.It Bq Er ELOOP
Too many symbolic links are encountered in translating the pathname.
This is taken to be indicative of a looping symbolic link.
.\" ===========
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.\" ===========
.It Bq Er ENOENT
The named file does not exist.
.\" ===========
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.El
.Pp
.Bl -tag -width ENAMETOOLONGAA
.Fn Fpathconf
will fail if:
.\" ===========
.It Bq Er EBADF
.Fa fildes
is not a valid open file descriptor.
.\" ===========
.It Bq Er EIO
An I/O error occurs while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr sysctl 3
.Sh HISTORY
The
.Nm pathconf
and
.Nm fpathconf
functions first appeared in 4.4BSD.
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: pathconf.2,v 1.2 1995/02/27 12:35:22 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 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	.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt PATHCONF 2
	38	.Os BSD 4
	39	.Sh NAME
2d21ac55 A	40	.Nm fpathconf ,
2d21ac55 A	41	.Nm pathconf
9bccf70c A	42	.Nd get configurable pathname variables
	43	.Sh SYNOPSIS
	44	.Fd #include <unistd.h>
	45	.Ft long
2d21ac55 A	46	.Fo fpathconf
	47	.Fa "int fildes"
	48	.Fa "int name"
	49	.Fc
9bccf70c	50	.Ft long
2d21ac55 A	51	.Fo pathconf
	52	.Fa "const char *path"
	53	.Fa "int name"
	54	.Fc
9bccf70c A	55	.Sh DESCRIPTION
	56	.Pp
	57	The
	58	.Fn pathconf
	59	and
	60	.Fn fpathconf
	61	functions provides a method for applications to determine the current
	62	value of a configurable system limit or option variable associated
	63	with a pathname or file descriptor.
	64	.Pp
	65	For
	66	.Nm pathconf ,
	67	the
	68	.Fa path
	69	argument is the name of a file or directory.
	70	For
	71	.Nm fpathconf ,
	72	the
2d21ac55	73	.Fa fildes
9bccf70c A	74	argument is an open file descriptor.
	75	The
	76	.Fa name
	77	argument specifies the system variable to be queried.
	78	Symbolic constants for each name value are found in the include file
	79	.Li <unistd.h> .
	80	.Pp
	81	The available values are as follows:
	82	.Pp
	83	.Bl -tag -width "123456"
	84	.Pp
	85	.It Li _PC_LINK_MAX
	86	The maximum file link count.
	87	.It Li _PC_MAX_CANON
	88	The maximum number of bytes in terminal canonical input line.
	89	.It Li _PC_MAX_INPUT
	90	The minimum maximum number of bytes for which space is available in
	91	a terminal input queue.
	92	.It Li _PC_NAME_MAX
	93	The maximum number of bytes in a file name.
	94	.It Li _PC_PATH_MAX
	95	The maximum number of bytes in a pathname.
	96	.It Li _PC_PIPE_BUF
	97	The maximum number of bytes which will be written atomically to a pipe.
	98	.It Li _PC_CHOWN_RESTRICTED
	99	Return 1 if appropriate privileges are required for the
	100	.Xr chown 2
	101	system call, otherwise 0.
	102	.It Li _PC_NO_TRUNC
	103	Return 1 if file names longer than KERN_NAME_MAX are truncated.
	104	.It Li _PC_VDISABLE
	105	Returns the terminal character disabling value.
	106	.El
	107	.Sh RETURN VALUES
	108	If the call to
	109	.Nm pathconf
	110	or
	111	.Nm fpathconf
	112	is not successful, \-1 is returned and
	113	.Va errno
	114	is set appropriately.
	115	Otherwise, if the variable is associated with functionality that does
	116	not have a limit in the system, \-1 is returned and
	117	.Va errno
	118	is not modified.
	119	Otherwise, the current variable value is returned.
	120	.Sh ERRORS
	121	If any of the following conditions occur, the
	122	.Nm pathconf
	123	and
	124	.Nm fpathconf
	125	functions shall return -1 and set
	126	.Va errno
	127	to the corresponding value.
2d21ac55 A	128	.Bl -tag -width ENAMETOOLONGAA
2d21ac55 A	129	.\" ===========
9bccf70c A	130	.It Bq Er EINVAL
	131	The value of the
	132	.Fa name
	133	argument is invalid.
2d21ac55	134	.\" ===========
9bccf70c A	135	.It Bq Er EINVAL
	136	The implementation does not support an association of the variable
	137	name with the associated file.
	138	.El
2d21ac55	139	.Pp
9bccf70c A	140	.Fn Pathconf
	141	will fail if:
	142	.Bl -tag -width ENAMETOOLONGAA
2d21ac55 A	143	.\" ===========
	144	.It Bq Er EACCES
	145	Search permission is denied for a component of the path prefix.
	146	.\" ===========
	147	.It Bq Er EIO
	148	An I/O error occurs while reading from or writing to the file system.
	149	.\" ===========
	150	.It Bq Er ELOOP
	151	Too many symbolic links are encountered in translating the pathname.
	152	This is taken to be indicative of a looping symbolic link.
	153	.\" ===========
9bccf70c A	154	.It Bq Er ENAMETOOLONG
	155	A component of a pathname exceeded 255 characters,
	156	or an entire path name exceeded 1023 characters.
2d21ac55	157	.\" ===========
9bccf70c A	158	.It Bq Er ENOENT
9bccf70c A	159	The named file does not exist.
2d21ac55 A	160	.\" ===========
	161	.It Bq Er ENOTDIR
	162	A component of the path prefix is not a directory.
9bccf70c A	163	.El
9bccf70c A	164	.Pp
2d21ac55	165	.Bl -tag -width ENAMETOOLONGAA
9bccf70c A	166	.Fn Fpathconf
9bccf70c A	167	will fail if:
2d21ac55	168	.\" ===========
9bccf70c	169	.It Bq Er EBADF
2d21ac55	170	.Fa fildes
9bccf70c	171	is not a valid open file descriptor.
2d21ac55	172	.\" ===========
9bccf70c	173	.It Bq Er EIO
2d21ac55	174	An I/O error occurs while reading from or writing to the file system.
9bccf70c A	175	.El
	176	.Sh SEE ALSO
	177	.Xr sysctl 3
	178	.Sh HISTORY
	179	The
	180	.Nm pathconf
	181	and
	182	.Nm fpathconf
	183	functions first appeared in 4.4BSD.