/*
 * Dinko Korunic 'kreator', 2002.
 * Uptime hack LKM
 *
 * Copyright (C) 2002  Dinko Korunic
 *
 * 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
 *
 * Usage:
 *  insmod uptime_hack uptime=seconds
 *  
 * Example:
 *  vampirella# uptime
 *   21:55:46 up  1:03,  3 users,  load average: 0.07, 0.02, 0.00
 *  vampirella# insmod uptime_hack.o uptime=10000000
 *  uptime_hack 1.0 initialised
 *  vampirella# uptime
 *   21:55:56 up 115 days, 17:46,  3 users,  load average: 0.06, 0.02, 0.00
 *  vampirella# rmmod uptime_hack
 *  vampirella# uptime
 *   21:56:04 up  1:03,  3 users,  load average: 0.05, 0.02, 0.00
 *
 * Credits:
 *  Big thanks goes to Matija Nalis for the original idea - as well as
 *  numerous trolls on hr.comp.os.linux for showing us their uptime.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/proc_fs.h>

#define MODULE_VERSION "1.3"
#define MODULE_NAME "uptime_hack"

static long unsigned myuptime = 0;
static long unsigned myidle = 0;
static long unsigned uptime = 0;
static long unsigned startjiffies = 0;

MODULE_PARM(uptime, "l");

static int proc_calc_metrics(char *page, char **start, off_t off, int
    count, int *eof, int len)
{
  if (len <= off + count)
    *eof = 1;
  *start = page + off;
  len -= off;
  if (len > count)
    len = count;
  if (len < 0)
    len = 0;
  return len;
}

static int uptime_read(char *page, char **start, off_t off, int count, int
    *eof, void *data)
{
  int len;

  if (!uptime)
    myuptime = jiffies;
  else
    myuptime = uptime * HZ + jiffies - startjiffies;

#if HZ != 100
  len = sprintf(page,"%lu.%02lu %lu.%02lu\n", myuptime / HZ, (((myuptime %
            HZ) * 100) / HZ) % 100, myidle / HZ, (((myidle % HZ) * 100) /
          HZ) % 100);
#else 
  len = sprintf(page,"%lu.%02lu %lu.%02lu\n", myuptime / HZ, myuptime %
      HZ, myidle / HZ, myidle % HZ);
#endif
  return proc_calc_metrics(page, start, off, count, eof, len);
}

int init_module()
{
  startjiffies = jiffies;
/*
 * unfortunately, no init_tasks[] for modules :(
  myidle = init_tasks[0]->times.tms_utime +
    init_tasks[0]->times.tms_stime;
 */
  create_proc_read_entry("uptime", 0, NULL, uptime_read, NULL);
  printk(KERN_INFO "%s %s initialised\n", MODULE_NAME, MODULE_VERSION);
  return 0;
}

void cleanup_module()
{
  remove_proc_entry("uptime", NULL);
}  

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dinko Korunic");
MODULE_DESCRIPTION("procfs uptime hack");