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.\" $FreeBSD$ 34.\" 35.Dd November 4, 2002 36.Dt PATHCONF 2 37.Os 38.Sh NAME 39.Nm pathconf , 40.Nm fpathconf 41.Nd get configurable pathname variables 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In unistd.h 46.Ft long 47.Fn pathconf "const char *path" "int name" 48.Ft long 49.Fn fpathconf "int fd" "int name" 50.Sh DESCRIPTION 51The 52.Fn pathconf 53and 54.Fn fpathconf 55system calls 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 , 61the 62.Fa path 63argument is the name of a file or directory. 64For 65.Fn fpathconf , 66the 67.Fa fd 68argument is an open file descriptor. 69The 70.Fa name 71argument specifies the system variable to be queried. 72Symbolic constants for each name value are found in the include file 73.Li <unistd.h> . 74.Pp 75The available values are as follows: 76.Pp 77.Bl -tag -width 6n 78.Pp 79.It Li _PC_LINK_MAX 80The maximum file link count. 81.It Li _PC_MAX_CANON 82The maximum number of bytes in terminal canonical input line. 83.It Li _PC_MAX_INPUT 84The minimum maximum number of bytes for which space is available in 85a terminal input queue. 86.It Li _PC_NAME_MAX 87The maximum number of bytes in a file name. 88.It Li _PC_PATH_MAX 89The maximum number of bytes in a pathname. 90.It Li _PC_PIPE_BUF 91The maximum number of bytes which will be written atomically to a pipe. 92.It Li _PC_CHOWN_RESTRICTED 93Return 1 if appropriate privileges are required for the 94.Xr chown 2 95system call, otherwise 0. 96.It Li _PC_NO_TRUNC 97Return 1 if file names longer than _POSIX_NAME_MAX are truncated. 98.It Li _PC_VDISABLE 99Returns the terminal character disabling value. 100.It Li _PC_ASYNC_IO 101Return 1 if asynchronous I/O is supported, otherwise 0. 102.It Li _PC_PRIO_IO 103Returns 1 if prioritised I/O is supported for this file, 104otherwise 0. 105.It Li _PC_SYNC_IO 106Returns 1 if synchronised I/O is supported for this file, otherwise 0. 107.It Li _PC_ALLOC_SIZE_MIN 108Minimum number of bytes of storage allocated for any portion of a file. 109.It Li _PC_FILESIZEBITS 110Number of bits needed to represent the maximum file size. 111.It Li _PC_REC_INCR_XFER_SIZE 112Recommended increment for file transfer sizes between 113.Dv _PC_REC_MIN_XFER_SIZE 114and 115.Dv _PC_REC_MAX_XFER_SIZE . 116.It Li _PC_REC_MAX_XFER_SIZE 117Maximum recommended file transfer size. 118.It Li _PC_REC_MIN_XFER_SIZE 119Minimum recommended file transfer size. 120.It Li _PC_REC_XFER_ALIGN 121Recommended file transfer buffer alignment. 122.It Li _PC_SYMLINK_MAX 123Maximum number of bytes in a symbolic link. 124.It Li _PC_ACL_EXTENDED 125Returns 1 if an Access Control List (ACL) can be set on the specified 126file, otherwise 0. 127.It Li _PC_ACL_PATH_MAX 128Maximum number of ACL entries per file. 129.It Li _PC_CAP_PRESENT 130Returns 1 if a capability state can be set on the specified file, 131otherwise 0. 132.It Li _PC_INF_PRESENT 133Returns 1 if an information label can be set on the specified file, 134otherwise 0. 135.It Li _PC_MAC_PRESENT 136Returns 1 if a Mandatory Access Control (MAC) label can be set on the 137specified file, otherwise 0. 138.El 139.Sh RETURN VALUES 140If the call to 141.Fn pathconf 142or 143.Fn fpathconf 144is not successful, \-1 is returned and 145.Va errno 146is set appropriately. 147Otherwise, if the variable is associated with functionality that does 148not have a limit in the system, \-1 is returned and 149.Va errno 150is not modified. 151Otherwise, the current variable value is returned. 152.Sh ERRORS 153If any of the following conditions occur, the 154.Fn pathconf 155and 156.Fn fpathconf 157system calls shall return -1 and set 158.Va errno 159to the corresponding value. 160.Bl -tag -width Er 161.It Bq Er EINVAL 162The value of the 163.Fa name 164argument is invalid. 165.It Bq Er EINVAL 166The implementation does not support an association of the variable 167name with the associated file. 168.El 169.Pp 170The 171.Fn pathconf 172system call 173will fail if: 174.Bl -tag -width Er 175.It Bq Er ENOTDIR 176A component of the path prefix is not a directory. 177.It Bq Er ENAMETOOLONG 178A component of a pathname exceeded 255 characters, 179or an entire path name exceeded 1023 characters. 180.It Bq Er ENOENT 181The named file does not exist. 182.It Bq Er EACCES 183Search permission is denied for a component of the path prefix. 184.It Bq Er ELOOP 185Too many symbolic links were encountered in translating the pathname. 186.It Bq Er EIO 187An I/O error occurred while reading from or writing to the file system. 188.El 189.Pp 190.Bl -tag -width Er 191The 192.Fn fpathconf 193system call 194will fail if: 195.It Bq Er EBADF 196The 197.Fa fd 198argument 199is not a valid open file descriptor. 200.It Bq Er EIO 201An I/O error occurred while reading from or writing to the file system. 202.El 203.Sh SEE ALSO 204.Xr sysctl 3 205.Sh HISTORY 206The 207.Fn pathconf 208and 209.Fn fpathconf 210system calls first appeared in 211.Bx 4.4 . 212