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package gioctl
import "syscall"
const (
typeBits = 8
numberBits = 8
sizeBits = 14
directionBits = 2
typeMask = (1 << typeBits) - 1
numberMask = (1 << numberBits) - 1
sizeMask = (1 << sizeBits) - 1
directionMask = (1 << directionBits) - 1
directionNone = 0
directionWrite = 1
directionRead = 2
numberShift = 0
typeShift = numberShift + numberBits
sizeShift = typeShift + typeBits
directionShift = sizeShift + sizeBits
)
func ioc(dir, t, nr, size uintptr) uintptr {
return (dir << directionShift) | (t << typeShift) | (nr << numberShift) | (size << sizeShift)
}
// Io used for a simple ioctl that sends nothing but the type and number, and receives back nothing but an (integer) retval.
func Io(t, nr uintptr) uintptr {
return ioc(directionNone, t, nr, 0)
}
// IoR used for an ioctl that reads data from the device driver. The driver will be allowed to return sizeof(data_type) bytes to the user.
func IoR(t, nr, size uintptr) uintptr {
return ioc(directionRead, t, nr, size)
}
// IoW used for an ioctl that writes data to the device driver.
func IoW(t, nr, size uintptr) uintptr {
return ioc(directionWrite, t, nr, size)
}
// IoRW a combination of IoR and IoW. That is, data is both written to the driver and then read back from the driver by the client.
func IoRW(t, nr, size uintptr) uintptr {
return ioc(directionRead|directionWrite, t, nr, size)
}
// Ioctl simplified ioct call
func Ioctl(fd, op, arg uintptr) error {
_, _, ep := syscall.Syscall(syscall.SYS_IOCTL, fd, op, arg)
if ep != 0 {
return syscall.Errno(ep)
}
return nil
}
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