相关疑难解决方法(0)

我正在用C开发一个应用程序.父子进程通过管道进行通信.在写入管道之前,父进程执行另一个语句.在示例代码中,我使用sleep(10)来延迟.在子进程中,它应该从管道中读取数据.但是在子进程的管道读取端没有读取数据.

int main()
{
    int pid;
    FILE *fp;
    fp = fopen("test.txt","w");
    char *buff;
    int fd[2];
    int count = 0 ;
    pipe(fd);
    pid = fork();
    if(pid == 0)
    {
        close(fd[1]);
        ioctl(fd[0], FIONREAD, &count);
        fprintf(fp,"Value of count: %d ",count);
        buff = malloc(count);
        fprintf(fp,"\n TIME before read: %s",__TIME__);
        read(fd[0], buff, count);
        fprintf(fp,"\nbuffer: %s\n TIME after read %s", buff, __TIME__);
    }
    else{
        close(fd[0]);
        sleep(10);    //delay caused by application specific code replaced with sleep
        write(fd[1],"THIS is it",10);
    }
    fclose(fp);
    return 0;
}

如何使子进程等到数据写入另一端？