Index: kern/uipc_syscalls.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/uipc_syscalls.c,v
retrieving revision 1.146
diff -u -r1.146 uipc_syscalls.c
--- kern/uipc_syscalls.c	5 May 2003 20:33:37 -0000	1.146
+++ kern/uipc_syscalls.c	30 May 2003 04:58:44 -0000
@@ -1781,6 +1781,13 @@
 		error = EINVAL;
 		goto done;
 	}
+	if (!sowriteable(so)) {
+		error = EINVAL;
+#ifdef DIAGNOSTICS
+		printf("blah, no data available yet");
+#endif
+		goto done;
+	}
 	if ((so->so_state & SS_ISCONNECTED) == 0) {
 		error = ENOTCONN;
 		goto done;