Pseudo terminal

Question

I'm sending this e-mail because I have had a
problem with SUNOS and I am not able to solve it.
Neither are my collegues.
I wrote a program that uses pseudo terminals
to execute and send data to a second program.
The parent program opens the master side, fork
and start sending data to the child and reading
from it too.
The child
opens its side, receive data and eventualy send
the results back to the parent.
Finished the child, the parent closes the master.
The program is based on that implementation
presented by Stevens in his book "Advanced Prog.
in the Unix Environment".
It works fine the first time. But if this process
is repeated several times the data sent to the
child is not received. As a consequence, the
program never ends because it keeps waiting for
the data.
I have attached to this e-mail 2 programs. The
first is identifier.c, a very simple program that
reads a string from the stdio and simply says
whether or it is a valid identifier.
The second is playinput.c . It is a very simple
version of my program. It launchs identifier
and send the string "abcd\n\r" to it. Then reads
the result and shows it on the stdout.
This is repeated 1000 times. In older versions
of the SUNOS (5.5.1) it works many times (400
or even 900 times) and then get stuck due to the
problem I described above. In SUNOS 5.7 the
thing is even worst. It work a couple of times
(around 5 times) and then get stuck.
I beleive this is a bug because I understand that
there is no nondeterministic factors that should
make the program work for a while and then stop
working.
Marcio Delamaro, Dr.
/* *********** Identifier.c *********************/
#include <stdio.h>
main ()
char achar;
int length, valid_id;
length = 0;
valid_id = 1;
printf ("Input a Possible Silly-Pascal identifier\n");
printf ("followed by a return: ");
achar = fgetc (stdin);
valid_id = valid_s(achar);
if (valid_id)
length = 1;
achar = fgetc (stdin);
while (achar != '\n') {
if (!(valid_f(achar)))
valid_id = 0;
length++;
achar = fgetc (stdin);
if (valid_id && (length >= 1) && (length <= 6) )
printf ("Valid\n");
else printf ("Invalid\n");
int valid_s(char ch)
if (((ch >= 'A') && (ch <= 'Z')) || ((ch >= 'a') && (ch <= 'z')))
return (1);
else return (0);
int valid_f(char ch)
if (((ch >= 'A') && (ch <= 'Z')) || ((ch >= 'a') && (ch <= 'z')) || ((ch >= '0') && (ch <= '9')))
return (1);
else return (0);
/************** playinput.c *********************/
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/times.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <unistd.h>
#include <poll.h>
#include <stropts.h>
#include <sys/filio.h>
#include <stdio.h>
#include <errno.h>
extern char slave_name[20];
char buff[1024];
pid_t
pty_fork(int *ptrfdm)
int fdm, fds, k;
pid_t pid;
char pts_name[20];
if ( (fdm = ptym_open(pts_name)) < 0)
msg("can't open master pty");
exit(-1);
if ( (pid = fork()) < 0)
msg("Can not fork");
exit(-1);
else if (pid == 0) {            /* child */
if (setsid() < 0)
msg("setsid error");
exit(1);
/* SVR4 acquires controlling terminal on open() */
if ( (fds = ptys_open(fdm, pts_name)) < 0)
printf

Answer 1

sarah31: Thanks for the tip, unfortunately it didn't work. Now I get a "bad line X in fstab" at startup, where X is the line I added. But that line, as I understand it, mounts devfs, but devfs has always mounted (my /dev-folder is not empty, and I do get sound even when logging in as normal user).
The exact error message given by Konsole is: "Unable to open a suitable terminal device".
Here's what I've tried so far:
Added something like this in my /etc/devfsd.conf:
REGISTER ^pts/.* PERMISSIONS root.users=rwxrwxrwx
REGISTER ^pts/.* PERMISSIONS root.users=0660
REGISTER * PERMISSIONS root.users=rwxrwxrwx
Added this in fstab:
none /dev/pts devfs defaults 0 0
Any advice would be greatly appreciated (please try to keep it relatively explicit though
Erik