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.\" 34.Dd June 4, 1993 35.Dt PATHCONF 2 36.Os BSD 4 37.Sh NAME 38.Nm pathconf , 39.Nm fpathconf 40.Nd get configurable pathname variables 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Ft long 44.Fn pathconf "const char *path" "int name" 45.Ft long 46.Fn fpathconf "int fd" "int name" 47.Sh DESCRIPTION 48.Pp 49The 50.Fn pathconf 51and 52.Fn fpathconf 53functions provides a method for applications to determine the current 54value of a configurable system limit or option variable associated 55with a pathname or file descriptor. 56.Pp 57For 58.Nm pathconf , 59the 60.Fa path 61argument is the name of a file or directory. 62For 63.Nm fpathconf , 64the 65.Fa fd 66argument is an open file descriptor. 67The 68.Fa name 69argument specifies the system variable to be queried. 70Symbolic constants for each name value are found in the include file 71.Li <unistd.h> . 72.Pp 73The available values are as follows: 74.Pp 75.Bl -tag -width "123456" 76.Pp 77.It Li _PC_LINK_MAX 78The maximum file link count. 79.It Li _PC_MAX_CANON 80The maximum number of bytes in terminal canonical input line. 81.It Li _PC_MAX_INPUT 82The minimum maximum number of bytes for which space is available in 83a terminal input queue. 84.It Li _PC_NAME_MAX 85The maximum number of bytes in a file name. 86.It Li _PC_PATH_MAX 87The maximum number of bytes in a pathname. 88.It Li _PC_PIPE_BUF 89The maximum number of bytes which will be written atomically to a pipe. 90.It Li _PC_CHOWN_RESTRICTED 91Return 1 if appropriate privileges are required for the 92.Xr chown 2 93system call, otherwise 0. 94.It Li _PC_NO_TRUNC 95Return 1 if file names longer than KERN_NAME_MAX are truncated. 96.It Li _PC_VDISABLE 97Returns the terminal character disabling value. 98.El 99.Sh RETURN VALUES 100If the call to 101.Nm pathconf 102or 103.Nm fpathconf 104is not successful, \-1 is returned and 105.Va errno 106is set appropriately. 107Otherwise, if the variable is associated with functionality that does 108not have a limit in the system, \-1 is returned and 109.Va errno 110is not modified. 111Otherwise, the current variable value is returned. 112.Sh ERRORS 113If any of the following conditions occur, the 114.Nm pathconf 115and 116.Nm fpathconf 117functions shall return -1 and set 118.Va errno 119to the corresponding value. 120.Bl -tag -width Er 121.It Bq Er EINVAL 122The value of the 123.Fa name 124argument is invalid. 125.It Bq Er EINVAL 126The implementation does not support an association of the variable 127name with the associated file. 128.El 129.Fn Pathconf 130will fail if: 131.Bl -tag -width ENAMETOOLONGAA 132.It Bq Er ENOTDIR 133A component of the path prefix is not a directory. 134.It Bq Er ENAMETOOLONG 135A component of a pathname exceeded 255 characters, 136or an entire path name exceeded 1023 characters. 137.It Bq Er ENOENT 138The named file does not exist. 139.It Bq Er EACCES 140Search permission is denied for a component of the path prefix. 141.It Bq Er ELOOP 142Too many symbolic links were encountered in translating the pathname. 143.It Bq Er EIO 144An I/O error occurred while reading from or writing to the file system. 145.El 146.Pp 147.Bl -tag -width [EFAULT] 148.Fn Fpathconf 149will fail if: 150.It Bq Er EBADF 151.Fa fd 152is not a valid open file descriptor. 153.It Bq Er EIO 154An I/O error occurred while reading from or writing to the file system. 155.El 156.Sh SEE ALSO 157.Xr sysctl 3 158.Sh HISTORY 159The 160.Nm pathconf 161and 162.Nm fpathconf 163functions first appeared in 4.4BSD. 164