libusb0.py 文件源码

def _check(ret):
    if ret is None:
        errmsg = _lib.usb_strerror()
    else:
        if hasattr(ret, 'value'):
            ret = ret.value

        if ret < 0:
            errmsg = _lib.usb_strerror()
            # No error means that we need to get the error
            # message from the return code
            # Thanks to Nicholas Wheeler to point out the problem...
            # Also see issue #2860940
            if errmsg.lower() == 'no error':
                errmsg = os.strerror(-ret)
        else:
            return ret
    raise USBError(errmsg, ret)