10-1.c

《Linux应用开发技术详解》附书光盘中的例程。

#include <unistd.h>
#include <sys/types.h>

int main(void)
{
        int pipe1_fd[2], pipe2_fd[2];
        char * parent_talks[] = {"Hi, my baby", 
                                 "Can you tell daddy date and time?", 
                                 "Daddy have to leave here, bye!",
                                 NULL
                                };

        char * child_talks[] = {"Hi, daddy",
                                "Sure,",
                                "Bye!",
                                NULL
                               };

        char parent_buf[256], child_buf[256];
        char * parent_ptr, * child_ptr;
        int i,j, len;
        int child_status;
        time_t curtime;

        if(pipe(pipe1_fd)<0)
        {
                printf("pipe1 create error\n");
                return -1;
        }

        if(pipe(pipe2_fd)<0)
        {
                printf("pipe2 create error\n");
                return -1;
        }

        if(fork()==0)   //child
        {
                printf("\n");

                //pipe1_fd[0] is used to read, pipe2_fd[1] is used to write
                close(pipe1_fd[1]);
                close(pipe2_fd[0]);

                i = 0;
                child_ptr = child_talks[i];
                while(child_ptr != NULL)
                {
                        len = read(pipe1_fd[0], child_buf, 255);
                        child_buf[len] = '\0';
                        printf("Parent: %s\n", child_buf);
                        if (i == 1) {
                                time(&curtime);
                                len = sprintf(child_buf, "%s %s", child_ptr, ctime(&curtime)); 
                                child_buf[len-1] = '\0';
                                write(pipe2_fd[1], child_buf, strlen(child_buf));
                        }
                        else {
                                write(pipe2_fd[1], child_ptr, strlen(child_ptr));
                        }
                        child_ptr = child_talks[++i];
                }
                close(pipe1_fd[0]);
                close(pipe2_fd[1]);
                exit();
        }
        else {  //parent

                //pipe1_fd[1] is used to write, pipe2_fd[0] is used to read
                close(pipe1_fd[0]);
                close(pipe2_fd[1]);

                j = 0;
                parent_ptr = parent_talks[j];
                while (parent_ptr != NULL) {
                        write(pipe1_fd[1],parent_ptr,strlen(parent_ptr));
                        len = read(pipe2_fd[0],parent_buf,255);
                        parent_buf[len] = '\0';
                        printf("Child: %s\n", parent_buf);
                        parent_ptr = parent_talks[++j];
                }

        close(pipe1_fd[1]);
        close(pipe2_fd[0]);
        wait(&child_status);
        exit();
        }
}