USERLAND_IOCTL_MAGIC_LENGTH
char magic[USERLAND_IOCTL_MAGIC_LENGTH];
extern const char kUserlandFSIOCtlMagic[USERLAND_IOCTL_MAGIC_LENGTH];
USERLAND_IOCTL_MAGIC_LENGTH) == 0) {
const char kUserlandFSIOCtlMagic[USERLAND_IOCTL_MAGIC_LENGTH]