pipe01

/* pipe02.c */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <limits.h>

int main (void)
{
    int fd[2];
    int fdin;
    char read_pipe_buf[PIPE_BUF];
    char read_file_buf[PIPE_BUF];
    pid_t pid;
    int read_pipe_len;
    int read_file_len;

    /* creat a pipe */
    if ((pipe(fd)) < 0){
        perror("pipe error");
        exit(1);
    }

    pid = fork();
    if (pid < 0){
        perror("fork error");
        exit(1);
    }

    /* child */
    if (0 == pid){
        close(fd[1]); /* close wite pipe */
        while((read_pipe_len = read(fd[0], read_pipe_buf, PIPE_BUF)) > 0){
            read_pipe_buf[read_pipe_len] = '\0';
            printf("read %d bytes\n", read_pipe_len);
            printf("%s\n", read_pipe_buf);
        }
        close(fd[0]);
    }


    /* parent */
    if (pid > 0){
        close(fd[0]);
        fdin = open("pipe01.c", O_RDONLY);
        if (fdin < 0){
            perror("open error");
            exit(1);
        }
    }

    read_file_len = read(fdin, read_file_buf, PIPE_BUF);
    if (read_file_len > 0){
        write(fd[1], read_file_buf, read_file_len);
    }

    close(fdin);
    close(fd[1]);

    waitpid(pid, NULL, 0); /* wait for child */
    exit(0);
}