Execution of C program freezes when i create two pipes?

Question

I am trying to create a two way communication between processes (Parent <---> Child). I writted this code:

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <unistd.h>

int main(){
    printf("Program started.");
    int p1[2]; // CHILD => PARENT
    int p2[2]; // PARENT => CHILD

    if (pipe(p1) < 0) {return -1;}
    if (pipe(p2) < 0) {return -1;}

    int pid = fork();
    if (pid == -1) {return -2;}
    if (pid == 0)
    {//child process
        close(p1[0]);
        close(p2[1]);

        int x;
        if (read(p2[0], &x, sizeof(x)) == -1) {return 3;}
        printf("Recieved %d\n", x);
        x *= x;
        if (write(p1[1], &x, sizeof(x)) == -1) {return 4;}
        printf("Wrote %d\n", x);

        close(p1[1]);
        close(p2[0]);
    }
    else
    {//parent process
        close(p1[1]);
        close(p2[0]);

        int y = 7;
        if (write(p2[1], &y, sizeof(y) == -1)) {return 5;}
        if (read(p1[0], &y, sizeof(y)) == -1) {return 6;}
        printf("Result is %d\n", y);

        close(p1[0]);
        close(p2[1]);

        wait(NULL);
    }
    return 0; 
}

This code compiles successfully with gcc on Linux Ubuntu. When i try to run the compiled file, it freezes. The thing that bothers me is that not even the first printf line is executed:

if i comment out either of those two lines, code compiles and executes successfully:

if (pipe(p1) < 0) {return -1;}
if (pipe(p2) < 0) {return -1;}

(The number is not send successfully between the processes becouse there is only one pipe created, but it runs successfully)

What is the problem, and what am i doing wrong? Thanks in advance!

Answer 1

You misplaced a ) here:

        if (write(p2[1], &y, sizeof(y) == -1)) {return 5;}

sizeof(y) == -1 evaluates to 0. so you end up with write( ... , ... , 0) so you write nothing.