Function findloader

3rd/lua-5.4.3/src/loadlib.c:624–654

static void findloader (lua_State *L, const char *name) {
  int i;
  luaL_Buffer msg;  /* to build error message */
  /* push 'package.searchers' to index 3 in the stack */
  if (l_unlikely(lua_getfield(L, lua_upvalueindex(1), "searchers")
                 != LUA_TTABLE))
    luaL_error(L, "'package.searchers' must be a table");
  luaL_buffinit(L, &msg);
  /*  iterate over available searchers to find a loader */
  for (i = 1; ; i++) {
    luaL_addstring(&msg, "\n\t");  /* error-message prefix */
    if (l_unlikely(lua_rawgeti(L, 3, i) == LUA_TNIL)) {  /* no more searchers? */
      lua_pop(L, 1);  /* remove nil */
      luaL_buffsub(&msg, 2);  /* remove prefix */
      luaL_pushresult(&msg);  /* create error message */
      luaL_error(L, "module '%s' not found:%s", name, lua_tostring(L, -1));
    }
    lua_pushstring(L, name);
    lua_call(L, 1, 2);  /* call it */
    if (lua_isfunction(L, -2))  /* did it find a loader? */
      return;  /* module loader found */
    else if (lua_isstring(L, -2)) {  /* searcher returned error message? */
      lua_pop(L, 1);  /* remove extra return */
      luaL_addvalue(&msg);  /* concatenate error message */
    }
    else {  /* no error message */
      lua_pop(L, 2);  /* remove both returns */
      luaL_buffsub(&msg, 2);  /* remove prefix */
    }
  }
}


static int ll_require (lua_State *L) {