1.\" $NetBSD: pathconf.2,v 1.15 2003/08/07 16:44:03 agc 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. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93 31.\" 32.Dd March 21, 1999 33.Dt PATHCONF 2 34.Os 35.Sh NAME 36.Nm pathconf , 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 fpathconf "int fd" "int name" 47.Sh DESCRIPTION 48The 49.Fn pathconf 50and 51.Fn fpathconf 52functions provides a method for applications to determine the current 53value of a configurable system limit or option variable associated 54with a pathname or file descriptor. 55.Pp 56For 57.Nm pathconf , 58the 59.Fa path 60argument is the name of a file or directory. 61For 62.Nm fpathconf , 63the 64.Fa fd 65argument is an open file descriptor. 66The 67.Fa name 68argument specifies the system variable to be queried. 69Symbolic constants for each name value are found in the include file 70.Li \*[Lt]unistd.h\*[Gt] . 71.Pp 72The available values are as follows: 73.Pp 74.Bl -tag -width "123456" 75.Pp 76.It Li _PC_LINK_MAX 77The maximum file link count. 78.It Li _PC_MAX_CANON 79The maximum number of bytes in terminal canonical input line. 80.It Li _PC_MAX_INPUT 81The minimum maximum number of bytes for which space is available in 82a terminal input queue. 83.It Li _PC_NAME_MAX 84The maximum number of bytes in a file name. 85.It Li _PC_PATH_MAX 86The maximum number of bytes in a pathname. 87.It Li _PC_PIPE_BUF 88The maximum number of bytes which will be written atomically to a pipe. 89.It Li _PC_CHOWN_RESTRICTED 90Return 1 if appropriate privileges are required for the 91.Xr chown 2 92system call, otherwise 0. 93.It Li _PC_NO_TRUNC 94Return 1 if file names longer than KERN_NAME_MAX are truncated. 95.It Li _PC_VDISABLE 96Returns the terminal character disabling value. 97.It Li _PC_SYNC_IO 98Returns 1 of synchronized I/O is supported, otherwise 0. 99.It Li _PC_FILESIZEBITS 100If the maximum size file that could ever exist on the mounted file system is 101.Dv maxsize , 102then the returned value is 2 plus the floor of the base 2 logarithm of 103.Dv maxsize . 104.El 105.Sh RETURN VALUES 106If the call to 107.Nm pathconf 108or 109.Nm fpathconf 110is not successful, \-1 is returned and 111.Va errno 112is set appropriately. 113Otherwise, if the variable is associated with functionality that does 114not have a limit in the system, \-1 is returned and 115.Va errno 116is not modified. 117Otherwise, the current variable value is returned. 118.Sh ERRORS 119If any of the following conditions occur, the 120.Nm pathconf 121and 122.Nm fpathconf 123functions shall return -1 and set 124.Va errno 125to the corresponding value. 126.Bl -tag -width Er 127.It Bq Er EINVAL 128The value of the 129.Fa name 130argument is invalid. 131.It Bq Er EINVAL 132The implementation does not support an association of the variable 133name with the associated file. 134.El 135.Fn pathconf 136will fail if: 137.Bl -tag -width ENAMETOOLONGAA 138.It Bq Er ENOTDIR 139A component of the path prefix is not a directory. 140.It Bq Er ENAMETOOLONG 141A component of a pathname exceeded 255 characters, 142or an entire path name exceeded 1023 characters. 143.It Bq Er ENOENT 144The named file does not exist. 145.It Bq Er EACCES 146Search permission is denied for a component of the path prefix. 147.It Bq Er ELOOP 148Too many symbolic links were encountered in translating the pathname. 149.It Bq Er EIO 150An I/O error occurred while reading from or writing to the file system. 151.El 152.Pp 153.Bl -tag -width [EFAULT] 154.Fn fpathconf 155will fail if: 156.It Bq Er EBADF 157.Fa fd 158is not a valid open file descriptor. 159.It Bq Er EIO 160An I/O error occurred while reading from or writing to the file system. 161.El 162.Sh SEE ALSO 163.Xr sysctl 3 164.Sh STANDARDS 165The 166.Fn pathconf 167and 168.Fn fpathconf 169functions conform to 170.St -p1003.1-90 . 171.Sh HISTORY 172The 173.Nm pathconf 174and 175.Nm fpathconf 176functions first appeared in 177.Bx 4.4 . 178