#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/errno.h>

int main(void) {
    pid_t child = fork();
    int pipefd[2];
    int ret;
    struct sigaction sa;

    ret = pipe(pipefd);
    if (ret < 0) {
        perror("pipe");
        return 1;
    }

    sa.sa_handler = SIG_IGN;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sa.sa_restorer = NULL;

    ret = sigaction(SIGPIPE, &sa, NULL);
    if (ret < 0) {
        perror("sigaction");
        return 1;
    }

    if (child < 0) {
        /* error */
        perror("fork");
        return 1;
    } else if (child == 0) {
        /* child */
        close(pipefd[0]);
        dup2(pipefd[1], fileno(stdout));

        sleep(2);

        ret = printf("Hello world\n");
        if (ret < 0) {
            perror("printf");
        }
        fflush(stdout);
        errno = 0;

        ret = fflush(stdout);
        if (ret < 0) {
            perror("fflush");
        }

        if (ferror(stdout)) {
            perror("error writing to stdout");
            return 1;
        }
        return 0;
    } else {
        /* parent */
        close(pipefd[1]);
        close(pipefd[0]);
        waitpid(child, NULL, 0);
        return 0;
    }
}