Function setprogdir

3rd/lua-5.4.3/src/loadlib.c:177–189

** Replace in the path (on the top of the stack) any occurrence ** of LUA_EXEC_DIR with the executable's path. */

** of LUA_EXEC_DIR with the executable's path.
*/
static void setprogdir (lua_State *L) {
  char buff[MAX_PATH + 1];
  char *lb;
  DWORD nsize = sizeof(buff)/sizeof(char);
  DWORD n = GetModuleFileNameA(NULL, buff, nsize);  /* get exec. name */
  if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
    luaL_error(L, "unable to get ModuleFileName");
  else {
    *lb = '\0';  /* cut name on the last '\\' to get the path */
    luaL_gsub(L, lua_tostring(L, -1), LUA_EXEC_DIR, buff);
    lua_remove(L, -2);  /* remove original string */
  }
}