/* Wait for login on virtual machine console.
 * $Id: waitlogin.c,v 1.1 2007/05/17 10:54:29 rjones Exp $
 *
 * Usage: waitlogin /dev/pts/NN
 * Get the device by doing virsh dumpxml name | grep console
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <signal.h>

static sig_atomic_t sigalrm_counter = 0;

static void
sigalrm (int sig)
{
  sigalrm_counter ++;
}

int
main (int argc, char *argv[])
{
  FILE *fp;
  char buffer[256];
  int len;
  struct sigaction sa;

  if (argc != 2) {
    fprintf (stderr, "%s /dev/pts/NN\n", argv[0]);
    exit (1);
  }

  fp = fopen (argv[1], "r+");
  if (fp == NULL) {
    perror (argv[1]);
    exit (1);
  }

  memset (&sa, 0, sizeof sa);
  sa.sa_handler = sigalrm;
  sigaction (SIGALRM, &sa, NULL);

  while (1) {
    sigalrm_counter = 0;
    alarm (10);
    len = fread (buffer, 1, sizeof buffer - 1, fp);
    if (len == 0) {
      /* Error.  If it's an alarm timeout, send a return keypress. */
      if (sigalrm_counter > 0) {
        fputc ('\n', fp);
      } else if (feof (fp)) {
        fprintf (stderr, "Device %s closed unexpectedly.\n", argv[1]);
        exit (1);
      } else {
        perror (argv[1]);
        exit (1);
      }
    } else {
      buffer[len] = '\0';
      /* Line read.  See if it contains 'login: '. */
      if (strstr (buffer, "login: ") != NULL)
	break;
    }
  }

  exit (0);
}