Listing 3. Sample EVIOCGID ioctl

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or 
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */


#include <stdlib.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <asm/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>

#include <linux/input.h>


int main (int argc, char **argv) {

  int fd = -1;
  struct input_id device_info;

  /* ioctl() requires a file descriptor, so we check we got one, and then open it */
  if (argc != 2) {
    fprintf(stderr, "usage: %s event-device - probably /dev/input/event0\n", argv[0]);
    exit(1);
  }
  if ((fd = open(argv[1], O_RDONLY)) < 0) {
    perror("evdev open");
    exit(1);
  }

  /* suck out some device information */
  if(ioctl(fd, EVIOCGID, &device_info)) {
      perror("evdev ioctl");
  }

  /* the EVIOCGID ioctl() returns input_devinfo
   * structure - see <linux/input.h> 
   * So we work through the various elements, displaying 
   * each of them 
   */
  printf("vendor 0x%04hx product 0x%04hx version 0x%04hx is on",
	 device_info.vendor, device_info.product, 
	 device_info.version);
  switch ( device_info.bustype)
      {
      case BUS_PCI :
	  printf(" a PCI bus\n");
	  break;
      case BUS_ISAPNP :
	  printf(" a Plug-n-pray ISA bus\n");
	  break;
      case BUS_USB :
	  printf(" a Universal Serial Bus\n");
	  break;
      case BUS_HIL :
	  printf(" some weird PA-RISC Bus\n");
	  break;
      case BUS_ISA :
	  printf(" a legacy ISA bus\n");
	  break;
      case BUS_I8042 :
	  printf(" an I8042 (or similar) controller\n");
                break;
      case BUS_XTKBD :
	  printf(" a IBM XT bus\n");
	  break;
      case BUS_RS232 :
	  printf(" a RS232 serial bus\n");
	  break;
      case BUS_GAMEPORT :
	  printf(" a gameport\n");
	  break;
      case BUS_PARPORT :
	  printf(" a parallel port\n");
	  break;
      case BUS_AMIGA :
	  printf(" an Amiga unique interface\n");
	  break;
      case BUS_ADB :
	  printf(" an Apple Desktop Bus\n");
	  break;
      case BUS_I2C :
	  printf(" a inter-integrated circuit bus\n");
	  break;
      case BUS_HOST :
	  printf(" a device on the main board\n");
	  break;
      default:
	  printf(" an unknown bus type: 0x%04hx\n", device_info.bustype);
      }

  close(fd);

  exit(0);
}