Linux Pipe replace stdio - issues with MPI - c++

Question

This question is the next step after resolving the issue discussed in:
Piping for input/output
I use pipes to pass a string via stdin to an external program called GULP, and receive the stdout of GULP as input for my program. This works fine on one processor, but on two or more processors there's a problem (let's say it's just 2 cores). The program GULP uses a temporary file and it seems that the two processors launch GULP simultaneously and then GULP tries to perform multiple operations on the same file at the same time (maybe simultaneous writes). GULP reports "error opening file".
I am testing this code on a laptop with multiple cores running Ubuntu, but the code is intended for a distributed-memory HPC (I'm using OpenMPI). Assume for the sake of this discussion that I cannot modify GULP.
I'm hoping that there's some straightforward way to get GULP to create two independent temporary files and continue functioning as normal. Am I asking for too much?
Hopefully this pseudo code will help (assume 2 processors):
int main()
{
MPI_Init(&argc,&argv);
MPI_Comm_rank(…);
MPI_Comm_size(…);
int loopmin, loopmax;//distributes the loop among each processor
for (int i = loopmin; i < loopmax; i++)
{
Launch_GULP(…);//launches external program
}
return 0;
}
Launch_GULP(…)
{
int fd_p2c[2], fd_c2p[2];
pipe(fd_p2c);
pipe(fd_c2p);
childpid = fork();
//the rest follows as in accepted answer in above link
//so i'll highlight the interesting stuff
if (childpid < 0)
{
perror("bad");
exit(-1);
}
else if (childpid == 0)
{
//call dup2, etc
execl( …call the program… );
}
else
{
//the interesting stuff
close(fd_p2c[0]);
close(fd_c2p[1]);
write(fd_p2c[1],…);
close(fd_p2c[1]);
while(1)
{
bytes_read = read(fd_c2p[0],…);//read GULP output
if (bytes_read <= 0)
break;
//pass info to read buffer & append null terminator
}
close(fd_c2p[0]);
if(kill(childpid,SIGTERM) != 0)
{
perror("Failed to kill child… tragic");
exit(1);
}
waitpid(childpid, NULL, 0);
}
//end piping… GULP has reported an error via stdout
//that error is stored in the buffer string
//consequently an error is triggered in my code and the program exits
}