Operating System Pipe Testing Demo

new8.c

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

int main(int argc, char *argv[])
{
    int fd[2];
    char buffer[80];
    
    pipe(fd);
    char str1[80];
    char str2[80];
    int pid1, pid2, I;
    while ( ( pid1 = fork() ) == -1 );
    if (pid1 == 0)
    {
        if (lockf(fd[1], F_TLOCK, 0) == -1)
        {
            perror(argv[0]);
            exit(1);
        }
        lockf(fd[1], F_LOCK, 0);
        printf("Child 1 Input String 1\n");
        scanf("%s", str1);
        write(fd[1], str1, sizeof(str1));
        lockf(fd[1], F_ULOCK, 0);
        return 0;
    }
    else {
        while ( ( pid2 = fork() ) == -1 );
        if (pid2 == 0)
        {
            if (lockf(fd[1], F_TLOCK, 0) == -1)
            {
                perror(argv[0]);
                exit(1);
            }
            lockf(fd[1], F_LOCK, 0);
            printf("Child 2 Input String 2\n");
            scanf("%s", str2);
            write(fd[1], str2, sizeof(str2));
            lockf(fd[1], F_ULOCK, 0);
            return 0;
        }
        else
        {
            if (waitpid(pid1, NULL, 0) == pid1)
            {
                read(fd[0], buffer, 80);
                for (int i = 0; i < sizeof(str1); i++)
                    buffer[i] = toupper(buffer[i]);
                printf("Parent == Child 1: %s\n", buffer);
            }
            else
                printf("Waitpid 1 Error!");
            if (waitpid(pid2, NULL, 0) == pid2)
            {
                read(fd[0], buffer, 80);
                for (int i = 0; i < sizeof(str2); i++)
                    buffer[i] = tolower(buffer[i]);
                printf("Parent == Child 2: %s\n", buffer);
            }
            else
                printf("Waitpid 2 Error!");
        }
    }
}