// input-kbd-rpt.c
// Utility to set the keyboard auto-repeat parameters for a USB keyboard that's using the 
// Linux input system.
// By Phil Endecott, 2007.
// I hereby place this code in the public domain.
// You can get the latest version of this code from
//   http://svn.chezphil.org/utils/trunk/input-kbd-rpt.c
//
// It's very odd that there doesn't already seem to be a utility to do this.  As far as I can 
// see, the kbdrate program is not for USB devices, and the input-utils package doesn't have 
// control for the auto-repeat rate.  Maybe there is a program out there somewhere.  I spent a 
// long time looking and decided eventually that it would be quicker to write my own, since 
// all you have to do is one ioctl.
//
// It seems that the ability to change the repeat rate using an ioctl has not existed forever.  
// You might like to grep for EVIOCSREP in your /usr/include/linux/input.h before going much 
// further.  Specifically, it's not present in 2.6.13 but it is present in 2.6.18.
//
// Compile this program like this:
// gcc --std=c99 -Os -o input-kbd-rpt input-kdb-rpt.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/input.h>
#include <string.h>


static void usage(void)
{
  fprintf(stderr,"Usage: input-kdb-rpt /dev/input/event<n>                          - get\n");
  fprintf(stderr,"       input-kdb-rpt /dev/input/event<n> <delay/ms> <interval/ms> - set\n");
  fprintf(stderr,"       input-kdb-rpt /dev/input/event<n> off      - disable auto-repeat\n");
}


int main(int argc, char* argv[])
{
  if (argc>4 || argc<2) {
    usage();
    exit(1);
  }

  if (geteuid()!=0) {
    fprintf(stderr,"Warning: you probably need to be root to run this.  Trying anyway...\n");
  }

  char* fn = argv[1];
  int fd = open(fn,O_RDWR);
  if (fd==-1) {
    perror("open()");
    exit(1);
  }

  if (argc==2) {

    int ioctl_params[2];
    int rc = ioctl(fd,EVIOCGREP,ioctl_params);
    if (rc==-1) {
      perror("ioctl(EVIOCGREP)");
      exit(1);
    }
    int delay = ioctl_params[0];
    int interval = ioctl_params[1];

    fprintf(stdout,"delay = %d ms, interval = %d ms\n", delay, interval);

  } else {

    int delay, interval;

    if (argc==3) {
      if (strcmp(argv[2],"off")==0) {
        delay = interval = 0;
      } else {
        usage();
        exit(1);
      }

    } else {

      char* delay_str = argv[2];
      char* interval_str = argv[3];
  
      char* endptr;
      delay = strtol(delay_str,&endptr,10);
      if (*delay_str==0 || *endptr!=0) {
        fprintf(stderr,"Error: %s is not a number\n",delay_str);
        exit(1);
      }
  
      interval = strtol(interval_str,&endptr,10);
      if (*interval_str==0 || *endptr!=0) {
        fprintf(stderr,"Error: %s is not a number\n",interval_str);
        exit(1);
      }
    }
  
    int ioctl_params[2];
    ioctl_params[0] = delay;
    ioctl_params[1] = interval;
    int rc = ioctl(fd,EVIOCSREP,ioctl_params);
    if (rc==-1) {
      perror("ioctl(EVIOCSREP)");
      exit(1);
    }

  }

  exit(0);
}