Calling non exstent functions no longer crashes scripts.

This is so that future scripts will still work with old libraries,
and lets us add the "host can provide Lua API" feature soon.

Also some more comments.



SVN revision: 66961

legacy/edje/ChangeLog

@@ -271,3 +271,10 @@
 
 	* Unswallow object that are about to be swallowed if necessary.
 	* Add EDJE_ASPECT_PREFER_SOURCE.
+
+2011-11-07  David Seikel (onefang)
+
+	* Lua: Calling non exstent functions no longer crashes scripts.
+	   This is so that future scripts will still work with old libraries,
+	   and lets us add the "host can provide Lua API" feature soon.
+

legacy/edje/NEWS

@@ -13,6 +13,7 @@ Improvements:
     * check existence of group at compile time also.
     * reduce number of call to stat during edje_object_file_set.
     * unswallow object about to be swallowed if necessary.
+    * Lua scripts now more resilient against API changes.
 
 Changes since Edje 1.0.0:
 -------------------------

legacy/edje/src/examples/lua_script.edc

@@ -168,6 +168,14 @@ collections {
          print(D.text:text());
          D.text:show();
 
+	--// Put a few bogus API calls here to test the bogus API protection,
+	--// If the bogus API protection works, these should get ignored, but everything else runs smoothly.
+	--// Otherwise, the map is not done, the bubbles are not done, but the timers keep runinng.
+         bogus.failme(1, "two", D.rect);
+         temp = bogus.failme2();
+         D.text.bogus();
+         edje.bogus2();
+
          --// Fun with maps!
          D.map = edje.map(4);  --// 4 is the only supported map size at the moment.
          --// These all do the same thing.

legacy/edje/src/lib/edje_lua2.c

@@ -3724,25 +3724,80 @@ _elua_text_text(lua_State *L)                                   // Stack usage [
 
 
 //--------------------------------------------------------------------------//
+
+// A metatable and functions so that calling non existant API does not crash Lua scripts.
+
+static int _elua_bogan_nilfunc(lua_State *L);
+static int _elua_bogan_index(lua_State *L);
+
+static const struct luaL_reg _elua_bogan_funcs [] =
+{
+     {"nilfunc",         _elua_bogan_nilfunc}, // Just return a nil.
+     {"__index",         _elua_bogan_index},   // Return the above func.
+
+     {NULL, NULL} // end
+};
+
+static int
+_elua_bogan_nilfunc(lua_State *L)
+{
+   lua_getglobal(L, "nil");
+   return 1;
+}
+
+static int
+_elua_bogan_index(lua_State *L)
+{
+   const char *key;
+
+   key = lua_tostring(L, 2);
+   LE("%s does not exist!", key);
+   lua_pushcfunction(L, _elua_bogan_nilfunc);
+   return 1;
+}
+
+static void
+_elua_bogan_protect(lua_State *L)                    // Stack usage [-3, +3, m]
+{
+   lua_pushnil(L);                                   // Stack usage [-0, +1, -]
+   luaL_newmetatable(L, "bogan");                    // Stack usage [-0, +1, m]
+   luaL_register(L, 0, _elua_bogan_funcs);           // Stack usage [-1, +1, m]
+   lua_setmetatable(L, -2);                          // Stack usage [-1, +0, -]
+   lua_pop(L, 1);                                    // Stack usage [-1, +0, -]
+}
+
+//--------------------------------------------------------------------------//
+
 // Brain dead inheritance thingy, built for speed.  Kinda.  Part 1.
 static void
 _elua_add_functions(lua_State *L, const char *api, const luaL_Reg *funcs, const char *meta, const char *parent, const char *base)  // Stack usage [-3, +5, m]  if inheriting [-6, +11, em]
 {
+   // Create an api table, fill it full of the methods.
    luaL_register(L, api, funcs);              // Stack usage [-0, +1, m]
+   // Set the api metatable to the bogan metatable.
+   luaL_getmetatable(L, "bogan");             // Stack usage [-0, +1, -]
+   lua_setmetatable(L, -2);                   // Stack usage [-1, +0, -]
+   // Creat a meta metatable.
    luaL_newmetatable(L, meta);                // Stack usage [-0, +1, m]
+   // Put the gc functions in the metatable.
    luaL_register(L, 0, _elua_edje_gc_funcs);  // Stack usage [-1, +1, m]
+   // Create an __index entry in the metatable, make it point to the api table.
    lua_pushliteral(L, "__index");             // Stack usage [-0, +1, m]
    lua_pushvalue(L, -3);                      // Stack usage [-0, +1, -]
    lua_rawset(L, -3);                         // Stack usage [-2, +0, m]
+   // Later this metatable is used as the metatable for newly created objects of this class.
 
    if (base && parent)
      {
         // Inherit from base
         lua_getglobal(L, base);               // Stack usage [-0, +1, e]
+        // Create a new parent metatable.
         luaL_newmetatable(L, parent);         // Stack usage [-0, +1, m]
+        // Create an __index entry in the metatable, make it point to the base table.
         lua_pushliteral(L, "__index");        // Stack usage [-0, +1, m]
         lua_pushvalue(L, -3);                 // Stack usage [-0, +1, -]
         lua_rawset(L, -3);                    // Stack usage [-2, +0, m]
+        // Set the metatable for the api table to the parent metatable.
         lua_getglobal(L, api);                // Stack usage [-0, +1, e]
         luaL_getmetatable(L, parent);         // Stack usage [-0, +1, -]
         lua_setmetatable(L, -2);              // Stack usage [-1, +0, -]
@@ -3850,7 +3905,11 @@ _edje_lua2_script_init(Edje *ed)                                  // Stack usage
         lua_call(L, 1, 0);                                        // Stack usage [-2, +0, m]
      }
 
+   _elua_bogan_protect(L);                                        // Stack usage [+3, -3, m]
+
    luaL_register(L, _elua_edje_api, _elua_edje_funcs);            // Stack usage [-0, +1, m]
+   luaL_getmetatable(L, "bogan");                                 // Stack usage [-0, +1, -]
+   lua_setmetatable(L, -2);                                       // Stack usage [-1, +0, -]
    luaL_newmetatable(L, _elua_edje_meta);                         // Stack usage [-0, +1, m]
    luaL_register(L, 0, _elua_edje_gc_funcs);                      // Stack usage [-1, +1, m]