Including ioctl codes in userspace program

Question

Is there is a common practice for userspace programs to include ioctl codes used in a kernel module.

mydev.h:

#ifndef MYDEV_H
#define MYDEV_H

#define <linux/ioctl.h>

#define MYDEV_IOC_MAGIC 'C'

#define MYDEV_IOC_FOO   _IO(MYDEV_IOC_MAGIC, 0)
#define MYDEV_IOC_BAR   _IOW(MYDEV_IOC_MAGIC, 1, int)

#endif

I typically put my ioctl codes in a header which I include in my kernel module code. I considered just including this header in my userspace applications, but I realized that the linux/ioctl.h file path may not exist on most systems (e.g. systems with no exported kernel headers).

The solution seems to be to change the include line to: #include <sys/ioctl.h>; but then I couldn't use this header for my kernel module.

Is there a better solution to this problem, or is it common to have two separate but nearly identical header files?

Answer 1

You could leverage the _KERNEL_ macro.

#ifdef __KERNEL__
#include <linux/ioctl.h>
#else
#include <sys/ioctl.h>
#endif

You may have to abstract the actual ioctl values too, but you get the idea.