1.\" $NetBSD: pathconf.2,v 1.12 2002/02/08 01:28:20 ross 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 March 21, 1999 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.Fd #include \*[Lt]unistd.h\*[Gt] 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.Nm pathconf , 62the 63.Fa path 64argument is the name of a file or directory. 65For 66.Nm 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 \*[Lt]unistd.h\*[Gt] . 75.Pp 76The available values are as follows: 77.Pp 78.Bl -tag -width "123456" 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.It Li _PC_SYNC_IO 102Returns 1 of synchronized I/O is supported, otherwise 0. 103.It Li _PC_FILESIZEBITS 104If the maximum size file that could ever exist on the mounted file system is 105.Dv maxsize , 106then the returned value is 2 plus the floor of the base 2 logarithm of 107.Dv maxsize . 108.El 109.Sh RETURN VALUES 110If the call to 111.Nm pathconf 112or 113.Nm fpathconf 114is not successful, \-1 is returned and 115.Va errno 116is set appropriately. 117Otherwise, if the variable is associated with functionality that does 118not have a limit in the system, \-1 is returned and 119.Va errno 120is not modified. 121Otherwise, the current variable value is returned. 122.Sh ERRORS 123If any of the following conditions occur, the 124.Nm pathconf 125and 126.Nm fpathconf 127functions shall return -1 and set 128.Va errno 129to the corresponding value. 130.Bl -tag -width Er 131.It Bq Er EINVAL 132The value of the 133.Fa name 134argument is invalid. 135.It Bq Er EINVAL 136The implementation does not support an association of the variable 137name with the associated file. 138.El 139.Fn pathconf 140will fail if: 141.Bl -tag -width ENAMETOOLONGAA 142.It Bq Er ENOTDIR 143A component of the path prefix is not a directory. 144.It Bq Er ENAMETOOLONG 145A component of a pathname exceeded 255 characters, 146or an entire path name exceeded 1023 characters. 147.It Bq Er ENOENT 148The named file does not exist. 149.It Bq Er EACCES 150Search permission is denied for a component of the path prefix. 151.It Bq Er ELOOP 152Too many symbolic links were encountered in translating the pathname. 153.It Bq Er EIO 154An I/O error occurred while reading from or writing to the file system. 155.El 156.Pp 157.Bl -tag -width [EFAULT] 158.Fn fpathconf 159will fail if: 160.It Bq Er EBADF 161.Fa fd 162is not a valid open file descriptor. 163.It Bq Er EIO 164An I/O error occurred while reading from or writing to the file system. 165.El 166.Sh SEE ALSO 167.Xr sysctl 3 168.Sh STANDARDS 169The 170.Fn pathconf 171and 172.Fn fpathconf 173functions conform to 174.St -p1003.1-90 . 175.Sh HISTORY 176The 177.Nm pathconf 178and 179.Nm fpathconf 180functions first appeared in 181.Bx 4.4 . 182