IOC_DIRMASK

ioctl_id

Constant IOC_DIRMASK 

Source 
pub const IOC_DIRMASK: IoctlId = _; // 3u64
Expand description

Bitmask for valid ioctl(2) direction values.

This is applied to the unshifted direction value.

Reference: include/uapi/asm-generic/ioctl.h