PseudoTerminal C - How To - c

Question

I am currently trying to make an application that will receive information from a client and send it to be executed in a server. For that I need to use PseudoTerminals.
I followed the example from a book and I ended up with this code
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
int ptyMasterOpen(char *slavName, size_t snLen)
{
int masterFd, savedErrno;
char *p;
masterFd = posix_openpt(O_RDWR | O_NOCTTY);
printf("Master: %d \n", masterFd);
if(masterFd == -1)
return -1;
if(grantpt(masterFd) == -1 || unlockpt(masterFd) == -1)
{
savedErrno = errno;
close(masterFd);
errno = savedErrno;
return -1;
}
p = ptsname(masterFd); /*Get the name of the of the slave*/
if(p == NULL)
{
savedErrno = errno;
close(masterFd);
errno = savedErrno;
return -1;
}
printf("Slave: %s \n", p);
//*
if(strlen(p) < snLen)
{
strncpy(slavName, p, snLen);
}
else
{
close(masterFd);
errno = EOVERFLOW;
return -1;
}
//*/
return masterFd;
}
pid_t ptyFork(int *masterFd, char *slavName, size_t snLen)
{
int mfd, slaveFd, saveErrno;
pid_t childPid;
char slname[MAX_SNAME];
char cIn[100], cOut[100];
int out = -1, in = -1;
mfd = ptyMasterOpen(slname, MAX_SNAME);
if(mfd == -1)
return -1;
if(slavName != NULL)
{
if(strlen(slname) < snLen)
{
strncpy(slavName, slname, snLen);
}
else
{
close(mfd);
errno = EOVERFLOW;
return -1;
}
}
childPid = fork();
if(childPid == -1)
{
saveErrno = errno;
close(mfd);
errno = saveErrno;
return -1;
}
if(childPid != 0)
{
*masterFd = mfd;
return childPid;
}
close(mfd);
slaveFd = open(slname, O_RDWR);
if(slaveFd != -1)
{
sprintf(cOut, "/tmp/out%d", slaveFd);
sprintf(cIn, "/tmp/in%d", slaveFd);
mkfifo(cOut, S_IRUSR|S_IWUSR);
out = open(cOut, O_RDWR|O_TRUNC|O_NONBLOCK);
mkfifo(cIn, S_IRUSR|S_IWUSR);
in = open(cIn, O_RDONLY|O_TRUNC);dup2(out, STDERR_FILENO);
dup2(out, STDOUT_FILENO);
dup2(in, STDIN_FILENO);
}
else
{
printf("Problem with slave\n\r");
fflush(stdout);
}
//*
if(dup2(slaveFd, STDIN_FILENO) != STDIN_FILENO || dup2(slaveFd, STDERR_FILENO) != STDERR_FILENO || dup2(slaveFd, STDOUT_FILENO) != STDOUT_FILENO)
{
printf("Error on duplicating Files");
close(slaveFd);
exit(0);
}
else
{
dup2(out, STDERR_FILENO);
dup2(out, STDOUT_FILENO);
dup2(in, STDIN_FILENO);
}
//*/
return slaveFd;
}
The problem is:
sprintf(cOut, "/tmp/out%d", childPid);
sprintf(cIn, "/tmp/in%d", childPid);
always return 0 even when I print them in main and they are values like 952...
also using echo "ls" > "/tmp/inxx" and cat /tmp/outxx does nothing.
I believe the problem is when the fork is done, the variables lose their values or something, because, it prints the error messages now, without the while(1) on main
int main(int argc, const char * argv[])
{
// insert code here...
int masterFd;
pid_t slaveFd;
char slavName[MAX_SNAME];
slaveFd = ptyFork(&masterFd, slavName, MAX_SNAME);
//close(masterFd);
//while(1);
return 0;
}
Can anyone help?
Thanks