Handle AF_UNIX addresses according to PEP 383.

socket.connect(), etc., previously accepted read-only buffers, so
in order to accept bytearray pathnames, they now accept any
PyBUF_SIMPLE in addition to surrogateescape-encoded strings.

diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -979,7 +979,9 @@ makesockaddr(int sockfd, struct sockaddr
 			     len++)
 				;
 		}
-		return PyUnicode_FromStringAndSize(a->sun_path, len);
+		return PyUnicode_Decode(a->sun_path, len,
+					Py_FileSystemDefaultEncoding,
+					"surrogateescape");
 	}
 #endif /* AF_UNIX */
 
@@ -1149,29 +1151,48 @@ getsockaddrarg(PySocketSockObject *s, Py
 	case AF_UNIX:
 	{
 		struct sockaddr_un* addr;
-		char *path;
-		int len;
-		if (!PyArg_Parse(args, "s#", &path, &len))
-			return 0;
+		Py_buffer view;
+		int retval = 0;
+
+		/* PEP 383.  Not using PyUnicode_FSConverter since we
+		   need to allow embedded nulls on Linux, and previous
+		   versions accepted read-only buffers here. */
+		if (PyUnicode_Check(args)) {
+			args = PyUnicode_AsEncodedString(
+				args, Py_FileSystemDefaultEncoding,
+				"surrogateescape");
+			if (args == NULL)
+				return 0;
+		}
+		else
+			Py_INCREF(args);
+		if (!PyArg_Parse(args, "y*", &view))
+			goto unix_out;
 
 		addr = (struct sockaddr_un*)addr_ret;
 #ifdef linux
-		if (len > sizeof(addr->sun_path)) {
+		if (view.len > sizeof(addr->sun_path)) {
 #else
-		if (len >= sizeof(addr->sun_path)) {
+		if (view.len >= sizeof(addr->sun_path)) {
 #endif
 			PyErr_SetString(socket_error, "AF_UNIX path too long");
-			return 0;
+			goto unix_releasebuf;
 		}
 		addr->sun_family = s->sock_family;
-		memcpy(addr->sun_path, path, len);
-		memset(addr->sun_path + len, 0, sizeof(addr->sun_path) - len);
+		memcpy(addr->sun_path, view.buf, view.len);
+		memset(addr->sun_path + view.len, 0,
+		       sizeof(addr->sun_path) - view.len);
 #if defined(PYOS_OS2)
 		*len_ret = sizeof(*addr);
 #else
-		*len_ret = len + offsetof(struct sockaddr_un, sun_path);
-#endif
-		return 1;
+		*len_ret = view.len + offsetof(struct sockaddr_un, sun_path);
+#endif
+		retval = 1;
+	unix_releasebuf:
+		PyBuffer_Release(&view);
+	unix_out:
+		Py_DECREF(args);
+		return retval;
 	}
 #endif /* AF_UNIX */