1.\" $OpenBSD: if_get.9,v 1.2 2015/12/08 18:35:51 jmc Exp $ 2.\" 3.\" Copyright (c) 2015 Martin Pieuchot 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: December 8 2015 $ 18.Dt IF_GET 9 19.Os 20.Sh NAME 21.Nm if_get , 22.Nm if_put 23.Nd get an interface pointer from an interface index 24.Sh SYNOPSIS 25.In net/if.h 26.Ft struct ifnet * 27.Fn if_get "unsigned int ifidx" 28.Ft void 29.Fn if_put "struct ifnet *ifp" 30.Sh DESCRIPTION 31The 32.Fn if_get 33function returns a pointer to the interface descriptor corresponding to the 34unique index 35.Fa ifidx . 36This descriptor is guaranteed to be valid until 37.Fn if_put 38is called on the returned pointer. 39.Pp 40The index value 41.Dv 0 42is never associated with an interface descriptor and can be used to determine if 43an interface index is valid or not. 44.Pp 45The 46.Fn if_put 47function releases a reference on the interface descriptor pointed by 48.Fa ifp . 49If 50.Fa ifp 51is a 52.Dv NULL 53pointer, no action occurs. 54.Sh CONTEXT 55.Fn if_get , 56and 57.Fn if_put 58can be called during autoconf, from process context, or from interrupt context. 59.Sh RETURN VALUES 60.Fn if_get 61returns a pointer to an interface descriptor if the index is valid, otherwise 62.Dv NULL . 63