From ce3619e619c99eeca253bc2a842d31451b57c378 Mon Sep 17 00:00:00 2001
From: Klaus Ethgen <Klaus@Ethgen.de>
Date: Sat, 27 Jul 2019 09:30:15 +0100
Subject: [PATCH] Compatibility function for lua > 5.1

---
 configure.ac | 29 ++++++++++++++++++-----------
 src/lua.c    | 27 +++++++++++++++++++++++----
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/configure.ac b/configure.ac
index 3fe49881..4e819436 100644
--- a/configure.ac
+++ b/configure.ac
@@ -518,22 +518,29 @@ AC_ARG_ENABLE([lua],
     [liblua=$enableval], [liblua=auto])
 
 if test "x${liblua}" != "xno"; then
-  PKG_CHECK_MODULES(LUA, lua5.1 >= 5.1,
+  PKG_CHECK_MODULES(LUA, lua5.3 >= 5.3,
     [
       HAVE_LUA=yes
       AC_DEFINE(HAVE_LUA, 1, [define to enable lua support])
     ],
     [
-      PKG_CHECK_MODULES(LUA, lua >= 5.1,
-	 [
-	   HAVE_LUA=yes
-	   AC_DEFINE(HAVE_LUA, 1, [define to enable lua support])
-	 ],
-	 [
-	    HAVE_LUA=no
-	    AC_MSG_WARN([$LUA_PKG_ERRORS])
-	 ])
-    ])
+     PKG_CHECK_MODULES(LUA, lua5.1 >= 5.1,
+       [
+	 HAVE_LUA=yes
+	 AC_DEFINE(HAVE_LUA, 1, [define to enable lua support])
+       ],
+       [
+	 PKG_CHECK_MODULES(LUA, lua >= 5.1,
+	    [
+	      HAVE_LUA=yes
+	      AC_DEFINE(HAVE_LUA, 1, [define to enable lua support])
+	    ],
+	    [
+	       HAVE_LUA=no
+	       AC_MSG_WARN([$LUA_PKG_ERRORS])
+	    ])
+       ])
+     ])
 else
   HAVE_LUA=disabled
 fi
diff --git a/src/lua.c b/src/lua.c
index eabbad0e..7859162a 100644
--- a/src/lua.c
+++ b/src/lua.c
@@ -41,6 +41,25 @@
 static lua_State *L; /** The LUA object needed for all operations (NOTE: That is
 		       * a upper-case variable to match the documentation!) */
 
+/* Taking that definition from lua 5.1 source */
+#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM >= 502
+int luaL_typerror(lua_State *L, int narg, const char *tname)
+{
+	const char *msg = lua_pushfstring(L, "%s expected, got %s", tname, luaL_typename(L, narg));
+	return luaL_argerror(L, narg, msg);
+}
+
+# define LUA_register_meta(L, meta) luaL_setfuncs(L, meta, 0);
+# define LUA_register_global(L, string, func) \
+	lua_newtable(L); \
+	luaL_setfuncs(L, func, 0); \
+	lua_pushvalue(L, -1); \
+	lua_setglobal(L, string)
+#else
+# define LUA_register_meta(L, meta) luaL_register(L, NULL, meta)
+# define LUA_register_global(L, string, func) luaL_register(L, string, func)
+#endif
+
 static FileData *lua_check_image(lua_State *L, int index)
 {
 	FileData **fd;
@@ -211,9 +230,9 @@ void lua_init(void)
 			{"get_marks", lua_image_get_marks},
 			{NULL, NULL}
 	};
-	luaL_register(L, "Image", image_methods);
+	LUA_register_global(L, "Image", image_methods);
 	luaL_newmetatable(L, "Image");
-	luaL_register(L, NULL, meta_methods);
+	LUA_register_meta(L, meta_methods);
 	lua_pushliteral(L, "__index");
 	lua_pushvalue(L, -3);
 	lua_settable(L, -3);
@@ -228,9 +247,9 @@ void lua_init(void)
 			{"get_datum", lua_exif_get_datum},
 			{NULL, NULL}
 	};
-	luaL_register(L, "Exif", exif_methods);
+	LUA_register_global(L, "Exif", exif_methods);
 	luaL_newmetatable(L, "Exif");
-	luaL_register(L, NULL, meta_methods);
+	LUA_register_meta(L, meta_methods);
 	lua_pushliteral(L, "__index");
 	lua_pushvalue(L, -3);
 	lua_settable(L, -3);
-- 
2.20.1