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, 5 insertions, 1 deletions

diff --git a/lib/kernel/src/inet_int.hrl b/lib/kernel/src/inet_int.hrl
index e7c6cf8ae2..0a2201298a 100644
--- a/lib/kernel/src/inet_int.hrl
+++ b/lib/kernel/src/inet_int.hrl
@@ -29,6 +29,7 @@
 -define(INET_AF_INET6,        2).
 -define(INET_AF_ANY,          3). % Fake for ANY in any address family
 -define(INET_AF_LOOPBACK,     4). % Fake for LOOPBACK in any address family
+-define(INET_AF_LOCAL,        5). % For Unix Domain address family
 
 %% type codes to open and gettype - INET_REQ_GETTYPE
 -define(INET_TYPE_STREAM,     1).
@@ -378,7 +379,8 @@
 	{ 
 	  ifaddr = any,     %% bind to interface address
 	  port   = 0,       %% bind to port (default is dynamic port)
-	  fd      = -1,     %% fd >= 0 => already bound
+	  fd     = -1,      %% fd >= 0 => already bound
+	  family = inet,    %% address family
 	  opts   = []       %% [{active,true}] added in inet:connect_options
 	 }).
 
@@ -388,6 +390,7 @@
 	  port   = 0,                %% bind to port (default is dynamic port)
 	  backlog = ?LISTEN_BACKLOG, %% backlog
 	  fd      = -1,              %% %% fd >= 0 => already bound
+	  family = inet,             %% address family
 	  opts   = []                %% [{active,true}] added in 
 	                             %% inet:listen_options
 	 }).
@@ -397,6 +400,7 @@
 	  ifaddr = any,
 	  port   = 0,
 	  fd     = -1,
+	  family = inet,
 	  opts   = [{active,true}]
 	 }).