[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 pathconf ,
.Nm fpathconf
.Nd get configurable pathname variables
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft long
.Fn pathconf "const char *path" "int name"
.Ft long
.Fn fpathconf "int fd" "int name"
.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 fd
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 Er
.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
.Fn Pathconf
will fail if:
.Bl -tag -width ENAMETOOLONGAA
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.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 EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.El
.Pp
.Bl -tag -width [EFAULT]
.Fn Fpathconf
will fail if:
.It Bq Er EBADF
.Fa fd
is not a valid open file descriptor.
.It Bq Er EIO
An I/O error occurred 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
	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.