From 6dc6ea419e8b467e00c3777a3dcf6ba4d9a4d511 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Diego=20Mart=C3=ADnez?= <kaeza@users.sf.net>
Date: Thu, 4 Feb 2016 09:58:44 -0300
Subject: [PATCH] builtin: Fix `print` crashing on nil "holes".

The engine implementation of `print` packs the varargs into a
table and passes the table directly to `table.concat`. If you
pass any value not supported by `table.concat` (particularly
`nil`), the server crashes. This is unexpected behavior, as
`print` is supposed to be able to work with anything.

This patch changes the implementation so it first converts
all arguments using `tostring`, which fixes the issue and
makes the custom `print` function compatible with the stock
Lua behavior.
---
 builtin/init.lua | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/builtin/init.lua b/builtin/init.lua
index b300446..6b27cf7 100644
--- a/builtin/init.lua
+++ b/builtin/init.lua
@@ -12,7 +12,11 @@ if core.print then
 	-- Override native print and use
 	-- terminal if that's turned on
 	function print(...)
-		core_print(table.concat({...}, "\t"))
+		local n, t = select("#", ...), { ... }
+		for i = 1, n do
+			t[i] = tostring(t[i])
+		end
+		core_print(table.concat(t, "\t"))
 	end
 	core.print = nil -- don't pollute our namespace
 end