console based chat application in c - c

Question

i created this application in which two processes communicate. everything is well
but i want that when the user press esc the process ends automatically.
s*econdly it is getting only one line from user. at a time in one process*. and before entering second line we have to add a line to the other process also.
here is the code for process 1(i called server)
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/errno.h>
extern int errno;
#define FIFO1 "/tmp/fifo.1"
#define FIFO3 "/tmp/fifo.3"
#define PERMS 0666
#define MESSAGE1 "client Says:"
main()
{
char buff[BUFSIZ];
int readfd, writefd;
int n, size;
if ((mknod (FIFO1, S_IFIFO | PERMS, 0) < 0) && (errno != EEXIST)) {
perror ("mknod FIFO1");
exit(1);
}
if (mkfifo(FIFO3, PERMS) < 0 && (errno != EEXIST)) {
unlink (FIFO1);
perror("mknod FIFO3");
exit(1);
}
if ((readfd = open(FIFO1, 0)) < 0) {
perror ("open FIFO1");
exit(1);
}
if ((writefd = open(FIFO3, 1)) < 0) {
perror ("open FIFO3");
exit(1);
}
///////////////////////////////////////////////////////////////////////////////////////////////////////
loop:
while(1)
{
if ((n = read(readfd, buff, 100)) < 0) {
perror ("server read"); exit (1);
}
write(1,MESSAGE1,strlen(MESSAGE1));
if (write(1, buff, n) != n) {
perror ("client write2"); exit(1);
}
/////////////////////////////////////////////////////////////////////////////////////////////
while(1)
{
printf("server says:");
//strcpy(buff,"I say:");
fgets(buff,100,stdin);
n=strlen(buff) + 1;
if (write(writefd, buff,n) < n) {
perror("server write1"); exit (1);
}
goto loop;
}
}//end of first for
close (readfd); close (writefd);
}
the second process (i called client)
#include <stdio.h>
#include <string.h>
#include<stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/errno.h>
extern int errno;
#define FIFO1 "/tmp/fifo.1"
#define FIFO3 "/tmp/fifo.3"
#define PERMS 0666
#define MESSAGE1 "server Says:"
main()
{
char buff[BUFSIZ];
char buf[]="logout";
int readfd, writefd, n, size;
if ((writefd = open(FIFO1, 1)) < 0) {
perror ("client open FIFO1"); exit(1);
}
if ((readfd = open(FIFO3, 0)) < 0) {
perror ("client open FIFO3"); exit(1);
}
///////////////////////////////////////////////////////////
loop:
while(1)
{
printf("client says:");
fgets(buff,100,stdin);
n=strlen(buff) + 1;
if (write(writefd, buff,n) < n)
{
perror("server write1"); exit (1);
}
////////////////////////////////////////////
while(1)
{
if ((n = read(readfd, buff, 100)) < 0)
{
perror ("client read"); exit(1);
}
write(1,MESSAGE1,strlen(MESSAGE1));
if (write(1, buff, n) != n)
{
perror ("client write2"); exit(1);
}
goto loop;
}
}//end of first for
close(readfd); close(writefd);
/* Remove FIFOs now that we are done using them */
if (unlink (FIFO1) < 0) {
perror("client unlink FIFO1");
exit(1);
}
if (unlink (FIFO3) < 0) {
perror("client unlink FIFO3");
exit(1);
}
exit(0);
}

Answer 1

If I understand you correctly, you want the two programs to be non blocking, i.e. they should be able to read from either the user or from the pipe.
If that is the case then I suggest you look into the select system call. It can be used to poll for input from arbitrary file descriptors.
You could do something like the following pseudo-code:
while (1)
{
/* Poll for input */
select(...);
if (is_pipe_readable())
read_from_pipe_and_print_to_stdout();
else if (is_stdin_readable())
read_from_stdin_and_write_to_pipe();
}
Note that a file descriptor becomes readable when it's been closed. So if the write-end of a pipe is closed, the read-end becomes readable, with read returning zero.