#if 0
set -x
gcc -W -Wall -O6 -s -o `basename $0 .c` $0 $*
exit $?
#endif

#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <assert.h>
#include <sysexits.h>
#include <syslog.h>
#include <time.h>

enum states { unknown, sleeping, standby, active };
const char *state_names[] =
  { "unknown", "sleeping", "standby", "active/idle" };

#ifndef HDIO_DRIVE_CMD
#define HDIO_DRIVE_CMD 0x031f
#endif
#ifndef WIN_CHECKPOWERMODE1
#define WIN_CHECKPOWERMODE1 0xE5
#endif
#ifndef WIN_CHECKPOWERMODE2
#define WIN_CHECKPOWERMODE2 0x98
#endif

enum states
get_state (int fd)
{
  unsigned char args[4] = {WIN_CHECKPOWERMODE1,0,0,0};
  enum states state;
  if (ioctl(fd, HDIO_DRIVE_CMD, &args)
      && (args[0] = WIN_CHECKPOWERMODE2) /* try again with 0x98 */
      && ioctl(fd, HDIO_DRIVE_CMD, &args)) {
    if (errno != EIO || args[0] != 0 || args[1] != 0)
      state = unknown;
    else
      state = sleeping;
  } else {
    state = (args[2] == 255) ? active : standby;
  }
  return state;
}

int
main (int argc, char **argv)
{
  int *fds;
  enum states *st;
  char *buf, *tmpbuf;
  size_t buf_len = 10000; /* Just the initial buf len. */
  size_t tmpbuf_len = 100;
  int numfd = argc-1;
  int fd;
  const char *prog;

  if ((prog = strrchr (argv[0], '/')))
    prog++;
  else
    prog = argv[0];
  openlog (prog, LOG_PID, LOG_USER);
  if (numfd <= 0) {
    fprintf (stderr, "Usage: %s /dev/hda /dev/hdb ..\n", prog);
    fprintf (stderr, "The first device is assumed to be syslog device\n"
	     "and syslog is only written if that drive is spinning.\n");
    exit (EX_USAGE);
  }
  fds = (int *)malloc (sizeof (int) * numfd);
  assert (fds);
  st = (enum states *)malloc (sizeof (enum states) * numfd);
  assert (st);
  buf = (char *)malloc(buf_len);
  assert (buf);
  buf[0] = '\0';
  for (fd = 0; fd < numfd; fd++) {
    st[fd] = unknown;
    fds[fd] = open (argv [1+fd], O_RDONLY|O_NONBLOCK);
    if (0 > fds[fd]) {
      perror (argv [1+fd]);
      exit (EX_IOERR);
    }
    if (strlen (argv [1+fd]) > tmpbuf_len)
      tmpbuf_len = strlen (argv [1+fd]);
  }
  tmpbuf_len += 100; /* Enough for the sprintf below. */
  tmpbuf = (char *)malloc(tmpbuf_len);
  assert (tmpbuf);
  for (;;) {
    for (fd = 0; fd < numfd; fd++) {
      enum states newst = get_state (fds[fd]);
      if (newst != st[fd]) {
	struct tm *t;
	time_t now;
	time (&now);
	t = localtime (&now);
	sprintf (tmpbuf, "%d-%02d-%02d %02d:%02d:%02d %s: "
		 "old state: %s, new state: %s.\n",
		 t->tm_year+1900, t->tm_mon+1, t->tm_mday,
		 t->tm_hour, t->tm_min, t->tm_sec,
		 argv[1+fd], state_names[st[fd]], state_names[newst]);
	if (buf_len < strlen (buf) + strlen (tmpbuf)) {
	  buf_len = strlen (buf) + strlen (tmpbuf);
	  buf = (char *)realloc (buf, buf_len);
	}
	strcat (buf, tmpbuf);
	st[fd] = newst;
      }
    }
    if (buf[0] && active == st[0]) {
      char *s = buf;
      char *t;
      while ((t = strtok (s, "\n"))) {
	syslog (LOG_INFO, "%s", t);
	s = NULL;
      }
      buf[0] = '\0';
    }
    sleep (1);
  }
  /* not reached */
  return 0;
}