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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/pathconf.2,v 1.4.2.6 2001/12/14 18:34:01 ru Exp $ 34.\" $DragonFly: src/lib/libc/sys/pathconf.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd June 4, 1993 37.Dt PATHCONF 2 38.Os 39.Sh NAME 40.Nm pathconf , 41.Nm fpathconf 42.Nd get configurable pathname variables 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In unistd.h 47.Ft long 48.Fn pathconf "const char *path" "int name" 49.Ft long 50.Fn fpathconf "int fd" "int name" 51.Sh DESCRIPTION 52The 53.Fn pathconf 54and 55.Fn fpathconf 56functions provides a method for applications to determine the current 57value of a configurable system limit or option variable associated 58with a pathname or file descriptor. 59.Pp 60For 61.Fn pathconf , 62the 63.Fa path 64argument is the name of a file or directory. 65For 66.Fn fpathconf , 67the 68.Fa fd 69argument is an open file descriptor. 70The 71.Fa name 72argument specifies the system variable to be queried. 73Symbolic constants for each name value are found in the include file 74.Li <unistd.h> . 75.Pp 76The available values are as follows: 77.Pp 78.Bl -tag -width 6n 79.Pp 80.It Li _PC_LINK_MAX 81The maximum file link count. 82.It Li _PC_MAX_CANON 83The maximum number of bytes in terminal canonical input line. 84.It Li _PC_MAX_INPUT 85The minimum maximum number of bytes for which space is available in 86a terminal input queue. 87.It Li _PC_NAME_MAX 88The maximum number of bytes in a file name. 89.It Li _PC_PATH_MAX 90The maximum number of bytes in a pathname. 91.It Li _PC_PIPE_BUF 92The maximum number of bytes which will be written atomically to a pipe. 93.It Li _PC_CHOWN_RESTRICTED 94Return 1 if appropriate privileges are required for the 95.Xr chown 2 96system call, otherwise 0. 97.It Li _PC_NO_TRUNC 98Return 1 if file names longer than KERN_NAME_MAX are truncated. 99.It Li _PC_VDISABLE 100Returns the terminal character disabling value. 101.El 102.Sh RETURN VALUES 103If the call to 104.Fn pathconf 105or 106.Fn fpathconf 107is not successful, \-1 is returned and 108.Va errno 109is set appropriately. 110Otherwise, if the variable is associated with functionality that does 111not have a limit in the system, \-1 is returned and 112.Va errno 113is not modified. 114Otherwise, the current variable value is returned. 115.Sh ERRORS 116If any of the following conditions occur, the 117.Fn pathconf 118and 119.Fn fpathconf 120functions shall return -1 and set 121.Va errno 122to the corresponding value. 123.Bl -tag -width Er 124.It Bq Er EINVAL 125The value of the 126.Fa name 127argument is invalid. 128.It Bq Er EINVAL 129The implementation does not support an association of the variable 130name with the associated file. 131.El 132.Pp 133.Fn Pathconf 134will fail if: 135.Bl -tag -width Er 136.It Bq Er ENOTDIR 137A component of the path prefix is not a directory. 138.It Bq Er ENAMETOOLONG 139A component of a pathname exceeded 255 characters, 140or an entire path name exceeded 1023 characters. 141.It Bq Er ENOENT 142The named file does not exist. 143.It Bq Er EACCES 144Search permission is denied for a component of the path prefix. 145.It Bq Er ELOOP 146Too many symbolic links were encountered in translating the pathname. 147.It Bq Er EIO 148An I/O error occurred while reading from or writing to the file system. 149.El 150.Pp 151.Bl -tag -width Er 152.Fn Fpathconf 153will fail if: 154.It Bq Er EBADF 155.Fa fd 156is not a valid open file descriptor. 157.It Bq Er EIO 158An I/O error occurred while reading from or writing to the file system. 159.El 160.Sh SEE ALSO 161.Xr sysctl 3 162.Sh HISTORY 163The 164.Fn pathconf 165and 166.Fn fpathconf 167functions first appeared in 168.Bx 4.4 . 169