driver.c

unix环境高级编程的源代码

#include    <sys/types.h>
#include    <signal.h>
#include    "ourhdr.h"

void
do_driver(char *driver)
{
    pid_t    child;
    int        pipe[2];

        /* create a stream pipe to communicate with the driver */
    if (s_pipe(pipe) < 0)
        err_sys("can't create stream pipe");

    if ( (child = fork()) < 0)
        err_sys("fork error");

    else if (child == 0) {            /* child */
        close(pipe[1]);

                /* stdin for driver */
        if (dup2(pipe[0], STDIN_FILENO) != STDIN_FILENO)
            err_sys("dup2 error to stdin");

                /* stdout for driver */
        if (dup2(pipe[0], STDOUT_FILENO) != STDOUT_FILENO)
            err_sys("dup2 error to stdout");
        close(pipe[0]);

                /* leave stderr for driver alone */

        execlp(driver, driver, (char *) 0);
        err_sys("execlp error for: %s", driver);
    }

    close(pipe[0]);        /* parent */

    if (dup2(pipe[1], STDIN_FILENO) != STDIN_FILENO)
        err_sys("dup2 error to stdin");

    if (dup2(pipe[1], STDOUT_FILENO) != STDOUT_FILENO)
        err_sys("dup2 error to stdout");
    close(pipe[1]);

    /* Parent returns, but with stdin and stdout connected
       to the driver. */
}