/*
 * force.c - v1.3 - by Brendan Kehoe (brendan@cs.widener.edu)
 *
 *  v1.0 - 10/15/90 - force execution of a command on the user's command line
 *  v1.1 - 11/19/90 - allow a pseudo-interactive session, of sorts
 *  v1.2 - 11/20/90 - made the thing error check itself into oblivion
 *  v1.3 -  7/16/91 - Ported to SGI by Dan Watts
 *
 * Usage: force [ -n ] [ -l /dev/ttyxx ]
 *       -n              - use this if you don't want the command to echo
 *       -l /dev/ttyxx   - the line to hit; use the full name (e.g. /dev/ttyp0)
 *
 *  Compiles under SGI Irix, SunOS 4.1, Ultrix 3.1D, and Ultrix 4.1. No
 *   promises are made for other OS's or systems.
 *
 *  It won't work under System V Release anything until an alternative
 *  to the TIOCSTI ioctl comes around. (Or you use SVR4, I'm told.)
 *
 * (Yes, this requires you be root to use it.)
 *
 * To use it, just type whatever at the Force> prompt, and when you
 * hit return, that line will get sent onto the user's input queue,
 * so it's like they typed it.  Use Control-V to quote control characters
 * like Control-C.  Type -X- on an empty line to quit out.
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>		/* for stat(2) */
#include <sys/stat.h>		/* for stat(2) */
#include <fcntl.h>
#ifdef sgi
#include <sys/termio.h>
#define termios	termio
#define TCGETS		TCGETA
#define TCSETS		TCSETA
#else
#include <sys/termios.h>
#endif

#ifdef ultrix
#include <sys/ioctl.h>
#define	TCGETS	TCGETP
#define	TCSETS	TCSANOW
#endif /* ultrix */

void push (), devchk ();

extern char *optarg;
extern int optind;
short no_echo = 0;

#define	USAGE	    "usage: %s [-n] [-l /dev/ttyxx]\n",*argv
#define COMMAND_LIM 100

int
main (argc, argv)
     int argc;
     char **argv;
{
  int f, cnt;
  short true = 1, no_cmd = 0;
  char *device, *buf, *trail, chr;

  if (argc > 4)
    {
      fprintf (stderr, USAGE);
      exit (1);
    }

  if ((device = (char *) malloc (40)) == (char *) NULL)
    {
      perror ("malloc 1");
      exit (1);
    }

  if ((buf = (char *) malloc (COMMAND_LIM)) == (char *) NULL)
    {
      perror ("malloc 1a");
      exit (1);
    }

  while ((chr = getopt (argc, argv, "nl:")) != -1)
    switch (chr)
      {
      case 'n':
	no_echo = 1;
	break;
      case 'l':
	(void) devchk (optarg, *argv);
	device = optarg;
	break;
      default:
	fprintf (stderr, USAGE);
	exit (1);
      }

  if (strlen (device) < 2)
    {
      printf ("Device [form: /dev/pts/x]: ");
      fflush (stdout);
      fgets (device, 39, stdin);
      /* cut off the trailing return that fgets leaves on */
      if ((*device)
	  && (*(trail = (char *) (device + strlen (device) - 1)) == '\n'))
	*trail = '\0';
      if (strlen (device) > 5)
	(void) devchk (device, *argv);
      else
	{
	  fprintf (stderr, "%s: give full name [e.g. /dev/pts/0].\n", *argv);
	  exit (1);
	}
    }

  printf ("Terminate with '-X-' on a line by itself.\n");
  while (true)
    {
      no_cmd = cnt = 0;
      chr = *buf = '\0';
      printf ("Force> ");
      rewind (stdin);
      while (((chr = getchar ()) != '\n')
	     && (chr != EOF)
	     && (cnt < COMMAND_LIM))
	*(buf + cnt++) = chr;
      if (cnt == COMMAND_LIM)
	{
	  printf ("Limit of %d characters per command line.\n", COMMAND_LIM);
	  no_cmd = 1;
	}
      if (chr == EOF)
	{
	  putc ('\n', stdout);
	  exit (0);
	}
      if (!no_cmd)
	{
	  *(buf + cnt) = '\0';
	  if (!strcmp (buf, "-X-"))
	    true = 0;
	  else if ((*buf != '\n') && (*buf != '\0'))
	    {
	      if ((f = open (device, O_NDELAY | O_RDWR)) < 0)
		{
		  perror ("open");
		  exit (1);
		}
	      push (f, buf);
	      close (f);
	    }
	}
    }
}

void
push (f, s)
     int f;
     char *s;
{
  register int i;
  char ret = '\n';
  struct termios termios;

  if (no_echo)
    {
      if (ioctl (f, TCGETS, &termios) < 0)
	{
	  perror ("ioctl 1");
	  exit (1);
	}
      termios.c_lflag &= ~ECHO;
      if (ioctl (f, TCSETS, &termios) < 0)
	{
	  perror ("ioctl 2");
	  exit (1);
	}
    }

  if (ioctl (f, TCFLSH, 0) < 0)
    {				/* flush the input queue */
      perror ("ioctl 3");
      exit (1);
    }

  for (i = 0; i < strlen (s); i++)	/* give 'em the command */
    ioctl (f, TIOCSTI, s + i);
  ioctl (f, TIOCSTI, &ret);	/* including a return */

  if (no_echo)
    {
      ioctl (f, TCGETS, &termios);
      termios.c_lflag |= ECHO;
      ioctl (f, TCSETS, &termios);

      ioctl (f, TCFLSH, 1);	/* flush the output queue */
    }
}

void
devchk (device, prg)
     char *device, *prg;
{
  struct stat sb;

  if (strncmp (device, "/dev/pts/", 9) && strncmp (device, "/dev/co", 7))
    {
      fprintf (stderr, "%s: give full name [e.g. /dev/ttyp0].\n", prg);
      exit (1);
    }
  if (!strcmp (device, ttyname (0)))
    {
      fprintf (stderr, "%s: you can't force yourself, you masochist.\n",
	       prg);
      exit (1);
    }
  if (strlen (device) > 40)
    {
      fprintf (stderr, "%s: terminal name too long.\n", prg);
      exit (1);
    }

  /*
   * there's probably a cleaner way to do this (not having the struct down
   * here at all); I considered using alloca, then decided not to. I'm open
   * to suggestions. - BK 11/20
   */
  if (stat (device, (struct stat *) & sb) < 0)
    {
      perror (prg);
      exit (1);
    }
}