From 64a318a9f1e703bd76f9cec2c28a8ce3d6669e72 Mon Sep 17 00:00:00 2001
From: Cloud Wu <cloudwu@gmail.com>
Date: Sat, 19 Aug 2017 10:20:05 +0800
Subject: [PATCH] see issue #715

---
 lualib-src/lua-socket.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lualib-src/lua-socket.c b/lualib-src/lua-socket.c
index c39f85dd..a1ef0295 100644
--- a/lualib-src/lua-socket.c
+++ b/lualib-src/lua-socket.c
@@ -257,6 +257,9 @@ static int
 lclearbuffer(lua_State *L) {
 	struct socket_buffer * sb = lua_touserdata(L, 1);
 	if (sb == NULL) {
+		if (lua_isnil(L, 1)) {
+			return 0;
+		}
 		return luaL_error(L, "Need buffer object at param 1");
 	}
 	luaL_checktype(L,2,LUA_TTABLE);