lua: use require() to pull built-in modules

It is planned to allow to overload a built-in module by an external one.
The implementation assumes storing of the built-in modules in a table
that is different from `package.loaded`. It means that accessing a
module as `package.loaded[<module_name>]` may fail.

However we still have a guarantee that a registered module is accessible
using `require()`. Use it for accessing built-in modules from our code.

Notes on different modules:

* `console`

  Reorder the print/log callbacks to place the print callback first. If
  something is going very wrong (say, someone removes the internal.print
  module), things will be consistent: both callback will not be set.

* `session`

  `box` is accessible as `require('box')` and as `_G.box`. Use the
  latter.

src/lua/serializer.c and src/lua/digest.c also access `package.loaded`
directly. I left them out of scope here, it requires a bit more in-depth
look.

Part of tarantool#7774

NO_DOC=user visible behavior is unchanged, pure refactoring change
NO_TEST=see NO_DOC
NO_CHANGELOG=see NO_DOC

Author: Totktonada

src/box/lua/console.c

@@ -421,18 +421,19 @@ luaT_console_setup_write_cb(struct lua_State *L)
 	if (!console_hide_show_prompt_is_enabled())
 		return;
 
-	say_set_stderr_callback(console_hide_prompt, console_show_prompt);
-
-	lua_getfield(L, LUA_GLOBALSINDEX, "package");
-	lua_getfield(L, -1, "loaded");
-	lua_getfield(L, -1, "internal.print");
+	lua_getfield(L, LUA_GLOBALSINDEX, "require");
+	lua_pushstring(L, "internal.print");
+	if (luaT_call(L, 1, 1) != 0)
+		return;
 
 	lua_rawgeti(L, LUA_REGISTRYINDEX, console_hide_prompt_ref);
 	lua_setfield(L, -2, "before_cb");
 	lua_rawgeti(L, LUA_REGISTRYINDEX, console_show_prompt_ref);
 	lua_setfield(L, -2, "after_cb");
 
-	lua_pop(L, 3);
+	lua_pop(L, 1);
+
+	say_set_stderr_callback(console_hide_prompt, console_show_prompt);
 }
 
 static void
@@ -441,18 +442,19 @@ luaT_console_cleanup_write_cb(struct lua_State *L)
 	if (!console_hide_show_prompt_is_enabled())
 		return;
 
-	say_set_stderr_callback(NULL, NULL);
-
-	lua_getfield(L, LUA_GLOBALSINDEX, "package");
-	lua_getfield(L, -1, "loaded");
-	lua_getfield(L, -1, "internal.print");
+	lua_getfield(L, LUA_GLOBALSINDEX, "require");
+	lua_pushstring(L, "internal.print");
+	if (luaT_call(L, 1, 1) != 0)
+		return;
 
 	lua_pushnil(L);
 	lua_setfield(L, -2, "before_cb");
 	lua_pushnil(L);
 	lua_setfield(L, -2, "after_cb");
 
-	lua_pop(L, 3);
+	lua_pop(L, 1);
+
+	say_set_stderr_callback(NULL, NULL);
 }
 
 /* }}} Show/hide prompt */

src/box/lua/session.c

@@ -509,10 +509,7 @@ session_storage_cleanup(int sid)
 	int top = lua_gettop(L);
 
 	if (ref == LUA_REFNIL) {
-		lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
-		if (!lua_istable(L, -1))
-			goto exit;
-		lua_getfield(L, -1, "box");
+		lua_getfield(L, LUA_GLOBALSINDEX, "box");
 		if (!lua_istable(L, -1))
 			goto exit;
 		lua_getfield(L, -1, "session");

src/lua/init.c

@@ -977,9 +977,10 @@ run_script_f(va_list ap)
 	 * Execute scripts or modules pointed by TT_PRELOAD
 	 * environment variable.
 	 */
-	lua_getfield(L, LUA_GLOBALSINDEX, "package");
-	lua_getfield(L, -1, "loaded");
-	lua_getfield(L, -1, "tarantool");
+	lua_getfield(L, LUA_GLOBALSINDEX, "require");
+	lua_pushstring(L, "tarantool");
+	if (luaT_call(L, 1, 1) != 0)
+		goto error;
 	lua_getfield(L, -1, "_internal");
 	lua_getfield(L, -1, "run_preload");
 	if (luaT_call(L, 0, 0) != 0)
@@ -1057,12 +1058,13 @@ run_script_f(va_list ap)
 	if (interactive) {
 		say_crit("%s %s\ntype 'help' for interactive help",
 			 tarantool_package(), tarantool_version());
-		/* get console.start from package.loaded */
-		lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
-		lua_getfield(L, -1, "console");
+		/* get console.start */
+		lua_getfield(L, LUA_GLOBALSINDEX, "require");
+		lua_pushstring(L, "console");
+		if (luaT_call(L, 1, 1) != 0)
+			goto error;
 		lua_getfield(L, -1, "start");
-		lua_remove(L, -2); /* remove package.loaded.console */
-		lua_remove(L, -2); /* remove package.loaded */
+		lua_remove(L, -2); /* remove console */
 		start_loop = false;
 		if (lua_main(L, argc, argv) != 0)
 			goto error;