relibc/include/bits/sys/ioctl.h

// Shamelessly copy-pasted from musl

#define _IOC(a,b,c,d) ( ((a)<<30) | ((b)<<8) | (c) | ((d)<<16) )
#define _IOC_NONE  0U
#define _IOC_WRITE 1U
#define _IOC_READ  2U

#define _IO(a,b) _IOC(_IOC_NONE,(a),(b),0)
#define _IOW(a,b,c) _IOC(_IOC_WRITE,(a),(b),sizeof(c))
#define _IOR(a,b,c) _IOC(_IOC_READ,(a),(b),sizeof(c))
#define _IOWR(a,b,c) _IOC(_IOC_READ|_IOC_WRITE,(a),(b),sizeof(c))