1.\" $NetBSD: pathconf.2,v 1.4 1997/07/14 23:20:08 kleink 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 51The 52.Fn pathconf 53and 54.Fn fpathconf 55functions provides a method for applications to determine the current 56value of a configurable system limit or option variable associated 57with a pathname or file descriptor. 58.Pp 59For 60.Nm pathconf , 61the 62.Fa path 63argument is the name of a file or directory. 64For 65.Nm fpathconf , 66the 67.Fa fd 68argument is an open file descriptor. 69The 70.Fa name 71argument specifies the system variable to be queried. 72Symbolic constants for each name value are found in the include file 73.Li <unistd.h> . 74.Pp 75The available values are as follows: 76.Pp 77.Bl -tag -width "123456" 78.Pp 79.It Li _PC_LINK_MAX 80The maximum file link count. 81.It Li _PC_MAX_CANON 82The maximum number of bytes in terminal canonical input line. 83.It Li _PC_MAX_INPUT 84The minimum maximum number of bytes for which space is available in 85a terminal input queue. 86.It Li _PC_NAME_MAX 87The maximum number of bytes in a file name. 88.It Li _PC_PATH_MAX 89The maximum number of bytes in a pathname. 90.It Li _PC_PIPE_BUF 91The maximum number of bytes which will be written atomically to a pipe. 92.It Li _PC_CHOWN_RESTRICTED 93Return 1 if appropriate privileges are required for the 94.Xr chown 2 95system call, otherwise 0. 96.It Li _PC_NO_TRUNC 97Return 1 if file names longer than KERN_NAME_MAX are truncated. 98.It Li _PC_VDISABLE 99Returns the terminal character disabling value. 100.El 101.Sh RETURN VALUES 102If the call to 103.Nm pathconf 104or 105.Nm fpathconf 106is not successful, \-1 is returned and 107.Va errno 108is set appropriately. 109Otherwise, if the variable is associated with functionality that does 110not have a limit in the system, \-1 is returned and 111.Va errno 112is not modified. 113Otherwise, the current variable value is returned. 114.Sh ERRORS 115If any of the following conditions occur, the 116.Nm pathconf 117and 118.Nm fpathconf 119functions shall return -1 and set 120.Va errno 121to the corresponding value. 122.Bl -tag -width Er 123.It Bq Er EINVAL 124The value of the 125.Fa name 126argument is invalid. 127.It Bq Er EINVAL 128The implementation does not support an association of the variable 129name with the associated file. 130.El 131.Fn Pathconf 132will fail if: 133.Bl -tag -width ENAMETOOLONGAA 134.It Bq Er ENOTDIR 135A component of the path prefix is not a directory. 136.It Bq Er ENAMETOOLONG 137A component of a pathname exceeded 255 characters, 138or an entire path name exceeded 1023 characters. 139.It Bq Er ENOENT 140The named file does not exist. 141.It Bq Er EACCES 142Search permission is denied for a component of the path prefix. 143.It Bq Er ELOOP 144Too many symbolic links were encountered in translating the pathname. 145.It Bq Er EIO 146An 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 151will fail if: 152.It Bq Er EBADF 153.Fa fd 154is not a valid open file descriptor. 155.It Bq Er EIO 156An 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 STANDARDS 161The 162.Fn pathconf 163and 164.Fn fpathconf 165functions conform to 166.St -p1003.1-90 . 167.Sh HISTORY 168The 169.Nm pathconf 170and 171.Nm fpathconf 172functions first appeared in 4.4BSD. 173