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