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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)devname.3 8.2 (Berkeley) 4/29/95 29.\" $FreeBSD$ 30.\" 31.Dd February 22, 2005 32.Dt DEVNAME 3 33.Os 34.Sh NAME 35.Nm devname 36.Nd "get device name" 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In sys/stat.h 41.In stdlib.h 42.Ft char * 43.Fn devname "dev_t dev" "mode_t type" 44.Ft char * 45.Fn devname_r "dev_t dev" "mode_t type" "char *buf" "int len" 46.Ft char * 47.Fn fdevname "int fd" 48.Ft char * 49.Fn fdevname_r "int fd" "char *buf" "int len" 50.Sh DESCRIPTION 51The 52.Fn devname 53function returns a pointer to the name of the block or character 54device in 55.Pa /dev 56with a device number of 57.Fa dev , 58and a file type matching the one encoded in 59.Fa type 60which must be one of 61.Dv S_IFBLK 62or 63.Dv S_IFCHR . 64To find the right name, 65.Fn devname 66asks the kernel via the 67.Va kern.devname 68sysctl. 69If it is unable to come up with a suitable name, 70it will format the information encapsulated in 71.Fa dev 72and 73.Fa type 74in a human-readable format. 75.Pp 76The 77.Fn fdevname 78and 79.Fn fdevname_r 80function obtains the device name directly from a file descriptor 81pointing to a character device. 82If it is unable to come up with a suitable name, these functions will 83return a NULL pointer. 84.Pp 85.Fn devname 86and 87.Fn fdevname 88return the name stored in a static buffer which will be overwritten 89on subsequent calls. 90.Fn devname_r 91and 92.Fn fdevname_r 93take a buffer and length as argument to avoid this problem. 94.Sh EXAMPLES 95.Bd -literal -compact 96int fd; 97struct stat buf; 98char *name; 99 100 fd = open("/dev/tun"); 101 fstat(fd, &buf); 102 printf("devname is /dev/%s\en", devname(buf.st_rdev, S_IFCHR)); 103 printf("fdevname is /dev/%s\en", fdevname(fd)); 104.Ed 105.Sh SEE ALSO 106.Xr stat 2 107.Sh HISTORY 108The 109.Fn devname 110function appeared in 111.Bx 4.4 . 112The 113.Fn fdevname 114function appeared in 115.Fx 8.0 . 116