Assign externally open fd to gen_tcp (UDS support)

When a AF_LOCAL file descriptor is created externally (e.g. Unix
Domain Socket) and passed to `gen_tcp:listen(0, [{fd, FD}])`, the
implementation incorrectly assigned the address family to be equal
to `inet`, which in the inet_drv driver translated to AF_INET instead
of AF_LOCAL (or AF_UNIX), and an `einval` error code was returned.
This patch fixes this problem such that the file descriptors of the
`local` address family are supported in the inet:fdopen/5,
gen_tcp:connect/3, gen_tcp:listen/2, gen_udp:open/2 calls

1 files changed, 6 insertions, 2 deletions

diff --git a/lib/kernel/src/inet_udp.erl b/lib/kernel/src/inet_udp.erl
index 5b2e5120c9..74b2874d5b 100644
--- a/lib/kernel/src/inet_udp.erl
+++ b/lib/kernel/src/inet_udp.erl
@@ -52,8 +52,9 @@ open(Port, Opts) ->
 	{ok, #udp_opts{fd=Fd,
 		       ifaddr=BAddr={A,B,C,D},
 		       port=BPort,
+		       family=Family,
 		       opts=SockOpts}} when ?ip(A,B,C,D), ?port(BPort) ->
-	    inet:open(Fd,BAddr,BPort,SockOpts,udp,inet,dgram,?MODULE);
+	    inet:open(Fd,BAddr,BPort,SockOpts,udp,Family,dgram,?MODULE);
 	{ok, _} -> exit(badarg)
     end.
 
@@ -92,9 +93,12 @@ controlling_process(Socket, NewOwner) ->
 %% Create a port/socket from a file descriptor 
 %%
 fdopen(Fd, Opts) ->
+    fdopen(Fd, inet:getfamily(Opts), Opts).
+
+fdopen(Fd, Family, Opts) ->
     inet:fdopen(Fd, 
 		optuniquify([{recbuf, ?RECBUF} | Opts]), 
-		udp, inet, dgram, ?MODULE).
+		udp, Family, dgram, ?MODULE).
 
 
 %% Remove all duplicate options from an option list.