1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/sys/pathconf.2,v 1.4.2.6 2001/12/14 18:34:01 ru Exp $ 30.\" 31.Dd April 13, 2013 32.Dt PATHCONF 2 33.Os 34.Sh NAME 35.Nm pathconf , 36.Nm lpathconf , 37.Nm fpathconf 38.Nd get configurable pathname variables 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In unistd.h 43.Ft long 44.Fn pathconf "const char *path" "int name" 45.Ft long 46.Fn lpathconf "const char *path" "int name" 47.Ft long 48.Fn fpathconf "int fd" "int name" 49.Sh DESCRIPTION 50The 51.Fn pathconf , 52.Fn lpathconf 53and 54.Fn fpathconf 55functions provide 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.Fn pathconf 61and 62.Fn lpathconf , 63the 64.Fa path 65argument is the name of a file or directory. 66For 67.Fn fpathconf , 68the 69.Fa fd 70argument is an open file descriptor. 71The 72.Fa name 73argument specifies the system variable to be queried. 74Symbolic constants for each name value are found in the include file 75.In unistd.h . 76.Pp 77The 78.Fn lpathconf 79system call is like 80.Fn pathconf 81except in the case where the named file is a symbolic link, 82in which case 83.Fn lpathconf 84returns information about the link, 85while 86.Fn pathconf 87returns information about the file the link references. 88.Pp 89The available values are as follows: 90.Bl -tag -width ".Dv _PC_CHOWN_RESTRICTED" 91.It Dv _PC_LINK_MAX 92The maximum file link count. 93.It Dv _PC_MAX_CANON 94The maximum number of bytes in terminal canonical input line. 95.It Dv _PC_MAX_INPUT 96The minimum maximum number of bytes for which space is available in 97a terminal input queue. 98.It Dv _PC_NAME_MAX 99The maximum number of bytes in a file name. 100.It Dv _PC_PATH_MAX 101The maximum number of bytes in a pathname. 102.It Dv _PC_PIPE_BUF 103The maximum number of bytes which will be written atomically to a pipe. 104.It Dv _PC_CHOWN_RESTRICTED 105Return 1 if appropriate privileges are required for the 106.Xr chown 2 107system call, otherwise 0. 108.It Dv _PC_NO_TRUNC 109Return 1 if file names longer than KERN_NAME_MAX are truncated. 110.It Dv _PC_VDISABLE 111Returns the terminal character disabling value. 112.El 113.Sh RETURN VALUES 114If the call to 115.Fn pathconf 116or 117.Fn fpathconf 118is not successful, \-1 is returned and 119.Va errno 120is set appropriately. 121Otherwise, if the variable is associated with functionality that does 122not have a limit in the system, \-1 is returned and 123.Va errno 124is not modified. 125Otherwise, the current variable value is returned. 126.Sh ERRORS 127If any of the following conditions occur, the 128.Fn pathconf , 129.Fn lpathconf 130and 131.Fn fpathconf 132functions shall return -1 and set 133.Va errno 134to the corresponding value. 135.Bl -tag -width Er 136.It Bq Er EINVAL 137The value of the 138.Fa name 139argument is invalid. 140.It Bq Er EINVAL 141The implementation does not support an association of the variable 142name with the associated file. 143.El 144.Pp 145.Fn Pathconf 146and 147.Fn lpathconf 148will fail if: 149.Bl -tag -width Er 150.It Bq Er ENOTDIR 151A component of the path prefix is not a directory. 152.It Bq Er ENAMETOOLONG 153A component of a pathname exceeded 255 characters, 154or an entire path name exceeded 1023 characters. 155.It Bq Er ENOENT 156The named file does not exist. 157.It Bq Er EACCES 158Search permission is denied for a component of the path prefix. 159.It Bq Er ELOOP 160Too many symbolic links were encountered in translating the pathname. 161.It Bq Er EIO 162An I/O error occurred while reading from or writing to the file system. 163.El 164.Pp 165.Fn Fpathconf 166will fail if: 167.Bl -tag -width Er 168.It Bq Er EBADF 169.Fa fd 170is not a valid open file descriptor. 171.It Bq Er EIO 172An I/O error occurred while reading from or writing to the file system. 173.El 174.Sh SEE ALSO 175.Xr sysctl 3 176.Sh HISTORY 177The 178.Fn pathconf 179and 180.Fn fpathconf 181functions first appeared in 182.Bx 4.4 . 183The 184.Fn lpathconf 185system call first appeared in 186.Dx 3.5 . 187