Check fastboot oem command line length

{

    Action *a;

    va_list ap;

    size_t cmdsize;

    a = calloc(1, sizeof(Action));

    if (a == 0) die("out of memory");

    va_start(ap, fmt);

    vsprintf(a->cmd, fmt, ap);

    cmdsize = vsnprintf(a->cmd, sizeof(a->cmd), fmt, ap);

    va_end(ap);

    if (cmdsize >= sizeof(a->cmd)) {

        free(a);

        die("Command length (%d) exceeds maximum size (%d)", cmdsize, sizeof(a->cmd));

    }

    if (action_last) {

        action_last->next = a;

    } else {