posix: add package

core/sys/posix/net_if.odin

@@ -0,0 +1,60 @@
+package posix
+
+import "core:c"
+
+when ODIN_OS == .Darwin {
+	foreign import lib "system:System.framework"
+} else {
+	foreign import lib "system:c"
+}
+
+// net/if.h - sockets local interfaces
+
+foreign lib {
+	/*
+	Retrieve an array of name indexes. Where the last one has an index of 0 and name of nil.
+
+	Returns: nil (setting errno) on failure, an array that should be freed with if_freenameindex otherwise
+
+	[[ More; https://pubs.opengroup.org/onlinepubs/9699919799/functions/if_nameindex.html ]]
+	*/
+	if_nameindex :: proc() -> [^]if_nameindex_t ---
+
+	/*
+	Returns the interface index matching the name or zero.
+
+	[[ More; https://pubs.opengroup.org/onlinepubs/9699919799/functions/if_nametoindex.html ]]
+	*/
+	if_nametoindex :: proc(name: cstring) -> c.uint ---
+
+	/*
+	Returns the name corresponding to the index.
+
+	ifname should be at least IF_NAMESIZE bytes in size.
+
+	[[ More; https://pubs.opengroup.org/onlinepubs/9699919799/functions/if_indextoname.html ]]
+	*/
+	if_indextoname :: proc(ifindex: c.uint, ifname: [^]byte) -> cstring ---
+
+	/*
+	Frees memory allocated by if_nameindex.
+
+	[[ More; https://pubs.opengroup.org/onlinepubs/9699919799/functions/if_freenameindex.html ]]
+	*/
+	if_freenameindex :: proc(ptr: ^if_nameindex_t) ---
+}
+
+when ODIN_OS == .Darwin || ODIN_OS == .FreeBSD || ODIN_OS == .NetBSD || ODIN_OS == .OpenBSD {
+
+	// NOTE: `_t` suffix added due to name conflict.
+
+	if_nameindex_t :: struct {
+		if_index: c.uint,  /* [PSX] 1, 2, ... */
+		if_name:  cstring, /* [PSX] null terminated name: "le0", ... */
+	}
+
+	IF_NAMESIZE :: 16
+
+} else {
+	#panic("posix is unimplemented for the current target")
+}