1.\" $OpenBSD: if_get.9,v 1.3 2021/01/18 09:55:43 mvs 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: January 18 2021 $ 18.Dt IF_GET 9 19.Os 20.Sh NAME 21.Nm if_get , 22.Nm if_unit , 23.Nm if_put 24.Nd get an interface pointer from an interface index 25.Sh SYNOPSIS 26.In net/if.h 27.Ft struct ifnet * 28.Fn if_get "unsigned int ifidx" 29.Ft struct ifnet * 30.Fn if_unit "const char *name" 31.Ft void 32.Fn if_put "struct ifnet *ifp" 33.Sh DESCRIPTION 34The 35.Fn if_get 36function returns a pointer to the interface descriptor corresponding to the 37unique index 38.Fa ifidx . 39This descriptor is guaranteed to be valid until 40.Fn if_put 41is called on the returned pointer. 42.Pp 43The index value 44.Dv 0 45is never associated with an interface descriptor and can be used to determine if 46an interface index is valid or not. 47.Pp 48The 49.Fn if_unit 50function returns a pointer to the interface descriptor corresponding to the 51unique name 52.Fa name . 53This descriptor is guaranteed to be valid until 54.Fn if_put 55is called on the returned pointer. 56.Pp 57The 58.Fn if_put 59function releases a reference on the interface descriptor pointed by 60.Fa ifp . 61If 62.Fa ifp 63is a 64.Dv NULL 65pointer, no action occurs. 66.Sh CONTEXT 67.Fn if_get , 68.Fn if_unit 69and 70.Fn if_put 71can be called during autoconf, from process context, or from interrupt context. 72.Sh RETURN VALUES 73.Fn if_get 74returns a pointer to an interface descriptor if the index is valid, otherwise 75.Dv NULL . 76.Pp 77.Fn if_unit 78returns a pointer to an interface descriptor if the interface with present 79name exists, otherwise 80.Dv NULL . 81