/* answerback.c version 0.1
 * Written by John Newbigin <jn@it.swin.edu.au>
 * GPL Version 2
 * Compile with 'gcc -Wall -o answerback answerback.c'
 * */
#include <stdio.h>
#include <unistd.h>
#include <termios.h>
#include <signal.h>
#include <string.h>
int main(int argc, char **argv)
{
  char *name = "ANSWERBACK";
  char code = 5;
  char buffer[16];
  int r;
  sigset_t sig, sigsave;
  struct termios term, termsave;
  FILE *fp;
  if(argc == 2)
  {
    name = argv[1];
  }
  if((fp = fopen(ctermid(NULL), "r+")) == NULL)
  {
    perror("open");
    return 0;
  }
  setbuf(fp, NULL);
  sigemptyset(&sig);
  sigaddset(&sig, SIGINT);
  sigaddset(&sig, SIGTSTP);
  sigprocmask(SIG_BLOCK, &sig, &sigsave);
  tcgetattr(fileno(fp), &termsave);
  term = termsave;
  term.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL | ICANON);
  term.c_cc[VMIN] = 0;
  term.c_cc[VTIME] = 10;
  tcsetattr(fileno(fp), TCSAFLUSH, &term);
  write(fileno(fp), &code, 1);
  memset(buffer, 0, sizeof(buffer));
  r = read(fileno(fp), buffer, sizeof(buffer) - 1);
  tcsetattr(fileno(fp), TCSAFLUSH, &termsave);
  sigprocmask(SIG_SETMASK, &sigsave, NULL);
  fclose(fp);
  if(r > 0)
  {
    printf("%s='%s'\n", name, buffer);
  }
  return 0;
}