Function getFreeLoopDevice

tests/dmflakey/loopback.go:79–91

getFreeLoopDevice allocates or finds a free loop device for use. REF: https://man7.org/linux/man-pages/man4/loop.4.html

()

//
// REF: https://man7.org/linux/man-pages/man4/loop.4.html
func getFreeLoopDevice() (string, error) {
	control, err := os.OpenFile(loopControlDevice, os.O_RDWR, 0)
	if err != nil {
		return "", fmt.Errorf("failed to open %s: %w", loopControlDevice, err)
	}

	idx, err := unix.IoctlRetInt(int(control.Fd()), unix.LOOP_CTL_GET_FREE)
	control.Close()
	if err != nil {
		return "", fmt.Errorf("failed to get free loop device number: %w", err)
	}
	return fmt.Sprintf(loopDevicePattern, idx), nil
}