if_nametoindex.3: New page documenting if_nametoindex(3) and if_indextoname(3)

References:
    RFC 3542

    POSIX Man Page Set
        http://www.unix.com/man-page/POSIX/3posix/if_indextoname
        http://www.unix.com/man-page/POSIX/3posix/if_nametoindex

    OS X Developer Tools Manual Page
        http://developer.apple.com/library/mac/#documentation/Darwin/Reference/Manpages/man3/if_nameindex.3.html

    Source: sysdeps/unix/sysv/linux/{if_index.c,ifaddrs.c}

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

1 files changed, 88 insertions, 0 deletions

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+.\" Copyright (c) 2012 YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+.\"
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of
+.\" this manual under the conditions for verbatim copying, provided that
+.\" the entire resulting derived work is distributed under the terms of
+.\" a permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date.  The author(s) assume.
+.\" no responsibility for errors or omissions, or for damages resulting.
+.\" from the use of the information contained herein.  The author(s) may.
+.\" not have taken the same level of care in the production of this.
+.\" manual, which is licensed free of charge, as they might when working.
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\"
+.TH IF_NAMETOINDEX 3 2012-11-16 "GNU" "Linux Programmer's Manual"
+.SH NAME
+if_nametoindex, if_indextoname \- mappings between network interface names and indexes
+.SH SYNOPSIS
+.nf
+.B #include <net/if.h>
+.sp
+.BI "unsigned int if_nametoindex(const char *" "ifname" );
+.BI "char *if_indextoname(unsigned int ifindex, char *" "ifname);
+.fi
+.SH DESCRIPTION
+The
+.BR if_nametoindex ()
+function returns the index of the network interface
+corresponding to the name
+.IR ifname .
+
+The
+.BR if_indextoname ()
+function returns the name of the network interface
+corresponding to the interface index
+.IR ifindex .
+The name is placed in the buffer pointed to by
+.IR ifname .
+The buffer must be of at least
+.B IF_NAMESIZE
+bytes.
+
+.SH RETURN VALUE
+On success,
+.BR if_nametoindex ()
+returns the index number of the network interface;
+On error, 0 is returned and
+.I errno
+is set appropriately.
+
+On success,
+.BR if_indextoname ()
+returns
+.IR ifname ;
+On error, NULL pointer is returned and
+.I errno
+is set appropriately.
+.SH ERRORS
+.BR if_indextoname ()
+may fail and set
+.I errno
+if:
+.TP
+.B ENXIO
+No interface found for the index.
+.PP
+.BR if_nametoindex ()
+and
+.BR if_indextoname ()
+may also fail for any of the errors specified for
+.BR socket (2),
+.BR ioctl (2).
+.SH CONFORMING TO
+RFC\ 3493, POSIX.1-2001.
+
+This function first appeared in BSDi.
+.SH SEE ALSO
+.BR getifaddrs (3),
+.BR if_nameindex (3),
+.BR ifconfig (8)