/*
  
 tty_talker sends command on serial port and prints response on stdout

 Robert Olsson  <robert@herjulf.se>  most code taken from:


 file is part of the minicom communications package,
 *		Copyright 1991-1995 Miquel van Smoorenburg.
 *
 *		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.

 and

 * Based on.... serial port tester
 * Doug Hughes - Auburn University College of Engineering
 * 9600 baud by default, settable via -19200 or -9600 flags
 * first non-baud argument is tty (e.g. /dev/term/a)
 * second argument is file name (e.g. /etc/hosts)
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <termio.h>
#include <sys/fcntl.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <signal.h>

#define VERSION "1.2 101021"
#define END_OF_FILE 26
#define CTRLD  4
#define P_LOCK "/var/lock"

char lockfile[128]; /* UUCP lock file of terminal */
char dial_tty[128];
char username[16];
int pid;
int retry = 6;


void usage(void)
{
  printf("\ntty_talk version %s\n", VERSION);
  
  printf("\ntty_talk sends command to terminal and waits for response\n\n");
  printf("tty_talk [-BAUDRATE] terminal command\n");
  printf(" Valid baudrates 4800, 9600 (Default), 19200, 38400 bps\n\n");
  exit(-1);
}

/*
 * Find out name to use for lockfile when locking tty.
 */

char *mbasename(char *s, char *res, int reslen)
{
  char *p;
  
  if (strncmp(s, "/dev/", 5) == 0) {
    /* In /dev */
    strncpy(res, s + 5, reslen - 1);
    res[reslen-1] = 0;
    for (p = res; *p; p++)
      if (*p == '/')
        *p = '_';
  } else {
    /* Outside of /dev. Do something sensible. */
    if ((p = strrchr(s, '/')) == NULL)
      p = s;
    else
      p++;
    strncpy(res, p, reslen - 1);
    res[reslen-1] = 0;
  }
  return res;
}

int lockfile_create(void)
{
  int fd, n;
  char buf[81];

  n = umask(022);
  /* Create lockfile compatible with UUCP-1.2  and minicom */
  if ((fd = open(lockfile, O_WRONLY | O_CREAT | O_EXCL, 0666)) < 0) {
    return 0;
  } else {
    snprintf(buf, sizeof(buf),  "%05d tty_talk %.20s\n", (int) getpid(), 
	     username);

    write(fd, buf, strlen(buf));
    close(fd);
  }
  umask(n);
  return 1;
}

void lockfile_remove(void)
{
  if (lockfile[0])
    unlink(lockfile);
}

int have_lock_dir(void)
{
 struct stat stt;
  char buf[128];

  if ( stat(P_LOCK, &stt) == 0) {

    snprintf(lockfile, sizeof(lockfile),
                       "%s/LCK..%s",
                       P_LOCK, mbasename(dial_tty, buf, sizeof(buf)));
  }
  else {
    printf("Lock directory %s does not exist\n", P_LOCK);
	exit(-1);
  }
  return 1;
}

int get_lock()
{
 struct stat stt;
  char buf[128];
  int fd, n = 0;

  have_lock_dir();

  if((fd = open(lockfile, O_RDONLY)) >= 0) {
    n = read(fd, buf, 127);
    close(fd);
    if (n > 0) {
      pid = -1;
      if (n == 4)
        /* Kermit-style lockfile. */
        pid = *(int *)buf;
      else {
        /* Ascii lockfile. */
        buf[n] = 0;
        sscanf(buf, "%d", &pid);
      }
      if (pid > 0 && kill((pid_t)pid, 0) < 0 &&
          errno == ESRCH) {
        printf("Lockfile is stale. Overriding it..\n");
        sleep(1);
        unlink(lockfile);
      } else
        n = 0;
    }
    if (n == 0) {
      if(retry == 1) /* Last retry */
	printf("Device %s is locked.\n", dial_tty);
      return 0;
    }
  }
  lockfile_create();
  return 1;
}

int main(int ac, char *av[]) 
{
	struct termios tp, old;
	int fd;
	char io[BUFSIZ];
	int res;
	long baud;
	int i, done, len, idx;

	if(ac == 1) 
	  usage();

	if (strcmp(av[1], "-4800") == 0) {
		baud = B4800;
		av++; ac--;
	} else if (strcmp(av[1], "-9600") == 0) {
		baud = B9600;
		av++; ac--;
	} else if (strcmp(av[1], "-19200") == 0) {
		baud = B19200;
		av++; ac--;
	} else if (strcmp(av[1], "-38400") == 0) {
		baud = B38400;
		av++; ac--;
	} else
		baud = B9600;

	if(ac < 3) 
	  usage();

	strncpy(dial_tty, av[1], sizeof(dial_tty));

	while (! get_lock()) {
	    if(--retry == 0)
	      exit(-1);
	    sleep(1);
	}

	if ((fd = open(av[1], O_RDWR | O_NOCTTY | O_NONBLOCK)) < 0) {
	  perror("bad terminal device, try another");
	  exit(-1);
	}
	
	fcntl(fd, F_GETFL);
	fcntl(fd, F_SETFL, O_RDWR);

	if (tcgetattr(fd, &tp) < 0) {
		perror("Couldn't get term attributes");
		exit(-1);
	}
	old = tp;

	/* 8 bits + baud rate + local control */
	tp.c_cflag = baud | CS8 | CLOCAL | CREAD;
	tp.c_oflag = 0; /* Raw Input */
	tp.c_lflag = 0; /* No conoical */

	/* ignore CR, ignore parity */
	tp.c_iflag = IGNBRK|IGNCR|IGNPAR;
	tp.c_lflag &= ~(ECHO  | ECHONL);

	tcflush(fd, TCIFLUSH);

	/* set output and input baud rates */

	cfsetospeed(&tp, baud);
	cfsetispeed(&tp, baud);

	if (tcsetattr(fd, TCSANOW, &tp) < 0) {
		perror("Couldn't set term attributes");
		goto error;
	}

	for(idx = 0, i = 2; i < ac; i++) {
	  len = strlen(av[i]);
	  strncpy(&io[idx], av[i], len);
	  idx += len;
	  io[idx++] = '\r';
	}
	
	res = write(fd, io, idx);

	if(res < 0 ) {
	  perror("write faild");
	  goto error;
	}
	
	done = 0;

	while (!done && (res = read(fd, io, BUFSIZ)) > 0)  {
	  int i;

	  for(i=0; !done && i < res; i++)  {
	    if(io[i] == END_OF_FILE) 
	      done = 1;
	    else  
	      printf("%c", io[i]);
	  }
	}
	if (tcsetattr(fd, TCSANOW, &old) < 0) {
		perror("Couldn't restore term attributes");
		exit(-1);
	}
	lockfile_remove();
	exit(0);
error:
	if (tcsetattr(fd, TCSANOW, &old) < 0) {
		perror("Couldn't restore term attributes");
	}
	exit(-1);
}