From 431b096f5158d193fb4c2bf43590bb51b3e66240 Mon Sep 17 00:00:00 2001
From: Thomas Goyne <plorkyeran@aegisub.org>
Date: Mon, 28 Apr 2014 14:19:16 -0700
Subject: [PATCH] Fix loading modules with UTF-8 BOMs

Ensure MoonScript gets loaded before we install our package loader to
avoid having its package loader used over ours.
---
 libaegisub/include/libaegisub/lua/script_reader.h |  2 +-
 libaegisub/lua/script_reader.cpp                  | 14 +++++++++++---
 src/auto4_lua.cpp                                 |  6 +++++-
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/libaegisub/include/libaegisub/lua/script_reader.h b/libaegisub/include/libaegisub/lua/script_reader.h
index f9ee6f371..9c9de1300 100644
--- a/libaegisub/include/libaegisub/lua/script_reader.h
+++ b/libaegisub/include/libaegisub/lua/script_reader.h
@@ -25,5 +25,5 @@ namespace agi { namespace lua {
 	bool LoadFile(lua_State *L, agi::fs::path const& filename);
 	/// Install our module loader and add include_path to the module search
 	/// path of the given lua state
-	void Install(lua_State *L, std::vector<fs::path> const& include_path);
+	bool Install(lua_State *L, std::vector<fs::path> const& include_path);
 } }
diff --git a/libaegisub/lua/script_reader.cpp b/libaegisub/lua/script_reader.cpp
index 53c4f13be..7e49909a7 100644
--- a/libaegisub/lua/script_reader.cpp
+++ b/libaegisub/lua/script_reader.cpp
@@ -50,8 +50,7 @@ namespace agi { namespace lua {
 		// We have a MoonScript file, so we need to load it with that
 		// It might be nice to have a dedicated lua state for compiling
 		// MoonScript to Lua
-		if (luaL_dostring(L, "return require('moonscript').loadstring"))
-			return false; // Leaves error message on stack
+		lua_getfield(L, LUA_REGISTRYINDEX, "moonscript");
 
 		// Save the text we'll be loading for the line number rewriting in the
 		// error handling
@@ -117,7 +116,7 @@ namespace agi { namespace lua {
 		return lua_gettop(L) - pretop;
 	}
 
-	void Install(lua_State *L, std::vector<fs::path> const& include_path) {
+	bool Install(lua_State *L, std::vector<fs::path> const& include_path) {
 		// set the module load path to include_path
 		lua_getglobal(L, "package");
 		push_value(L, "path");
@@ -137,10 +136,19 @@ namespace agi { namespace lua {
 
 		lua_settable(L, -3);
 
+		luaL_loadstring(L, "return require('moonscript').loadstring");
+		if (lua_pcall(L, 0, 1, 0)) {
+			lua_remove(L, -2); // remove package.path table
+			return false; // leave error message
+		}
+		lua_setfield(L, LUA_REGISTRYINDEX, "moonscript");
+
 		// Replace the default lua module loader with our unicode compatible one
 		lua_getfield(L, -1, "loaders");
 		push_value(L, exception_wrapper<module_loader>);
 		lua_rawseti(L, -2, 2);
 		lua_pop(L, 2);
+
+		return true;
 	}
 } }
diff --git a/src/auto4_lua.cpp b/src/auto4_lua.cpp
index 0a1bdf690..0116b933c 100644
--- a/src/auto4_lua.cpp
+++ b/src/auto4_lua.cpp
@@ -397,7 +397,11 @@ namespace {
 
 		// Replace the default lua module loader with our unicode compatible
 		// one and set the module search path
-		Install(L, include_path);
+		if (!Install(L, include_path)) {
+			description = get_string_or_default(L, 1);
+			lua_pop(L, 1);
+			return;
+		}
 		stackcheck.check_stack(0);
 
 		// prepare stuff in the registry