ioctl_test.c

#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#define MY_MACIG 'G'
#define READ_IOCTL _IOR(MY_MACIG, 0, int)
//#define WRITE_IOCTL _IOW(MY_MACIG, 1, int)

/* attribute structures */
struct ioctl_test_t {
  char field1;
  char field2;
} testStruct;

#define IOCTL_TEST _IOW(0, 6, struct ioctl_test_t)

int main(){
  char buf[200];
	int fd = -1;
	if ((fd = open("/proc/ioctl_test", O_RDWR)) < 0) {
		perror("open");
		return -1;
	}
	testStruct.field1 = 1; //1 char in my first initial
	testStruct.field2 = 'K';
	printf("size of testStruct.field1 = %d\n", sizeof(testStruct.field1));
	printf("size of testStruct.field2 = %d\n", sizeof(testStruct.field2));
	if(ioctl(fd, IOCTL_TEST, &testStruct ) < 0)
		perror("first ioctl");
	close(fd);
	//if(ioctl(fd, READ_IOCTL, buf) < 0)
	//perror("second ioctl");

	//printf("message: %s\n", buf);
	return 0;

}