freebsd-dev/lib/libc/gen/devname.3

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.\" Copyright (c) 1993
.\" The Regents of the University of California. All rights reserved.
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.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
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.\" @(#)devname.3 8.2 (Berkeley) 4/29/95
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.\" $FreeBSD$
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.\"
.Dd February 22, 2005
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.Dt DEVNAME 3
.Os
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.Sh NAME
.Nm devname
.Nd "get device name"
.Sh LIBRARY
.Lb libc
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.Sh SYNOPSIS
.In sys/stat.h
.In stdlib.h
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.Ft char *
.Fn devname "dev_t dev" "mode_t type"
.Ft char *
.Fn devname_r "dev_t dev" "mode_t type" "char *buf" "int len"
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.Sh DESCRIPTION
The
.Fn devname
function returns a pointer to the name of the block or character
device in
.Pa /dev
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with a device number of
.Fa dev ,
and a file type matching the one encoded in
.Fa type
which must be one of
.Dv S_IFBLK
or
.Dv S_IFCHR .
To find the right name,
.Fn devname
asks the kernel via the
.Va kern.devname
sysctl.
If it is unable to come up with a suitable name,
it will format the information encapsulated in
.Fa dev
and
.Fa type
in a human-readable format.
.Pp
.Fn devname
returns the name stored in a static buffer which will be overwritten
on subsequent calls.
.Fn devname_r
takes a buffer and length as argument to avoid this problem.
.Sh EXAMPLES
.Bd -literal -compact
int fd;
struct stat buf;
char *name;
fd = open("/dev/tun");
fstat(fd, &buf);
printf("devname is /dev/%s\en", devname(buf.st_rdev, S_IFCHR));
.Ed
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.Sh SEE ALSO
.Xr stat 2
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.Sh HISTORY
The
.Fn devname
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function appeared in
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.Bx 4.4 .