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 55functions provides 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 KERN_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.Ar path . 110.It Li _PC_FILESIZEBITS 111Number of bits needed to represented the maximum file size. 112.It Li _PC_REC_INCR_XFER_SIZE 113Recommended increment for file transfer sizes between 114.Dv _PC_REC_MIN_XFER_SIZE 115and 116.Dv _PC_REC_MAX_XFER_SIZE . 117.It Li _PC_REC_MAX_XFER_SIZE 118Maximum recommended file transfer size. 119.It Li _PC_REC_MIN_XFER_SIZE 120Minimum recommended file transfer size. 121.It Li _PC_REC_XFER_ALIGN 122Recommended file transfer buffer alignment. 123.It Li _PC_SYMLINK_MAX 124Maximum number of bytes in a symbolic link. 125.It Li _PC_ACL_EXTENDED 126Returns 1 if an Access Control List (ACL) can be set on the specified 127file, otherwise 0. 128.It Li _PC_ACL_PATH_MAX 129Maximum number of ACL entries per file. 130.It Li _PC_CAP_PRESENT 131Returns 1 if a capability state can be set on the specified file, 132otherwise 0. 133.It Li _PC_INF_PRESENT 134Returns 1 if an information label can be set on the specified file, 135otherwise 0. 136.It Li _PC_MAC_PRESENT 137Returns 1 if a Mandatory Access Control (MAC) label can be set on the 138specified file, otherwise 0. 139.El 140.Sh RETURN VALUES 141If the call to 142.Fn pathconf 143or 144.Fn fpathconf 145is not successful, \-1 is returned and 146.Va errno 147is set appropriately. 148Otherwise, if the variable is associated with functionality that does 149not have a limit in the system, \-1 is returned and 150.Va errno 151is not modified. 152Otherwise, the current variable value is returned. 153.Sh ERRORS 154If any of the following conditions occur, the 155.Fn pathconf 156and 157.Fn fpathconf 158functions shall return -1 and set 159.Va errno 160to the corresponding value. 161.Bl -tag -width Er 162.It Bq Er EINVAL 163The value of the 164.Fa name 165argument is invalid. 166.It Bq Er EINVAL 167The implementation does not support an association of the variable 168name with the associated file. 169.El 170.Pp 171.Fn Pathconf 172will fail if: 173.Bl -tag -width Er 174.It Bq Er ENOTDIR 175A component of the path prefix is not a directory. 176.It Bq Er ENAMETOOLONG 177A component of a pathname exceeded 255 characters, 178or an entire path name exceeded 1023 characters. 179.It Bq Er ENOENT 180The named file does not exist. 181.It Bq Er EACCES 182Search permission is denied for a component of the path prefix. 183.It Bq Er ELOOP 184Too many symbolic links were encountered in translating the pathname. 185.It Bq Er EIO 186An I/O error occurred while reading from or writing to the file system. 187.El 188.Pp 189.Bl -tag -width Er 190.Fn Fpathconf 191will fail if: 192.It Bq Er EBADF 193.Fa fd 194is not a valid open file descriptor. 195.It Bq Er EIO 196An I/O error occurred while reading from or writing to the file system. 197.El 198.Sh SEE ALSO 199.Xr sysctl 3 200.Sh HISTORY 201The 202.Fn pathconf 203and 204.Fn fpathconf 205functions first appeared in 206.Bx 4.4 . 207