tty_attach.c

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <signal.h>
#include <sys/poll.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <time.h>
#include <sys/types.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include "configure.h"


#define MAX_TTY 256
#define BUFFER_SIZE 4096
#define POLL_R_TIMEOUT 100
#define POLL_W_TIMEOUT 50

static char *tty_bus_path;
static char *devname;
static char *init_string;

static void usage(char *app)
{
	fprintf(stderr,"%s, Ver %s.%s.%s\n", basename(app), MAJORV, MINORV, SVNVERSION);
	fprintf(stderr,"Usage: %s [-h] [-s bus_path] tty_device\n", app);
	fprintf(stderr,"-h: shows this help\n");
	fprintf(stderr,"-s bus_path: uses bus_path as bus path name (default: /tmp/ttybus)\n");
	fprintf(stderr,"-i init_string: send init string to device\n");
	exit(2);
}

int tty_connect(char *path)
{
	struct sockaddr_un sun;
	int connect_fd = socket(PF_UNIX, SOCK_STREAM, 0);
	memset(&sun, 0, sizeof(struct sockaddr_un));
	sun.sun_family = AF_UNIX;
	strncpy(sun.sun_path, path, strlen(path));
	if(connect(connect_fd, (struct sockaddr *) &sun, sizeof(sun)) < 0){
		perror("Cannot connect to socket");
		exit(-1);
	}
	return connect_fd;
}

int main(int argc,char *argv[])
{

	int fd; 
	struct pollfd pfd[2];
	int pollret, r, w;
	char buffer[BUFFER_SIZE];
	int realdev;

	while (1) {
		int c;
		c = getopt (argc, argv, "hi:s:");
		if (c == -1)
			break;

		switch (c) {
			case 'h':
				usage(argv[0]); //implies exit
				break;

			case 's':
				tty_bus_path=strdup(optarg);
				break;
			case 'i':
				init_string = strdup(optarg);
				break;

			default:
				usage(argv[0]); //implies exit
		}
	} 
	if (optind != (argc -1))
		usage(argv[0]); //implies exit
	devname = strdup(argv[optind]);

	if (!tty_bus_path)
		tty_bus_path = strdup("/tmp/ttybus");
	
	fprintf(stderr,"Connecting to bus: %s\n", tty_bus_path);
	fd = tty_connect(tty_bus_path);


 	realdev = open(devname, O_RDWR);
	if (realdev < 0) {
		perror("opening device");
		exit(3);
		
	}
	if (init_string)
	{
		pfd[0].fd = realdev;
		pfd[0].events = POLLOUT;
		pollret = poll(&pfd[0], 1, 50);	
		if (pollret < 0) {
			fprintf(stderr, "Poll error: %s\n", strerror(errno));
			exit(1);
		}
		if(pfd[0].revents & POLLOUT) {
			write(realdev, init_string,strlen(init_string));
			write(realdev, "\n",1);
		} else {
			fprintf(stderr, "Device is busy, cannot send init string.\n");
		}
	}
	for (;;) {
		pfd[0].fd = realdev;
		pfd[0].events = POLLIN;
		pfd[1].fd = fd;
		pfd[1].events = POLLIN;
		pollret = poll(pfd, 2, 1000);
		if (pollret < 0) {
			fprintf(stderr, "Poll error: %s\n", strerror(errno));
			exit(1);
		}
		if (pollret == 0)
			continue;

		if ( (pfd[0].revents & POLLHUP || pfd[0].revents & POLLERR || pfd[0].revents &POLLNVAL) ||
			(pfd[1].revents & POLLHUP || pfd[1].revents & POLLERR || pfd[1].revents &POLLNVAL) )
			exit(1);
		if (pfd[0].revents & POLLIN) {
			r = read(realdev, buffer, BUFFER_SIZE);
			pfd[1].events = POLLOUT;
			pollret = poll(&pfd[1], 1, 50);	
			if (pollret < 0) {
				fprintf(stderr, "Poll error: %s\n", strerror(errno));
				exit(1);
			}
			if(pfd[1].revents & POLLOUT) {
				w = write(fd, buffer, r);
			}
		}
		if (pfd[1].revents & POLLIN) {
			r = read(fd, buffer, BUFFER_SIZE);
			pfd[0].fd = realdev;
			pfd[0].events = POLLOUT;
			pollret = poll(&pfd[0], 1, 50);	
			if (pollret < 0) {
				fprintf(stderr, "Poll error: %s\n", strerror(errno));
				exit(1);
			}
			if(pfd[0].revents & POLLOUT) {
				w = write(realdev, buffer, r);
			}
		}
	}		
}