ptyfork.c

unix环境高级编程的源代码

#include    <sys/types.h>
#include    <termios.h>
#ifndef    TIOCGWINSZ
#include    <sys/ioctl.h>    /* 44BSD requires this too */
#endif
#include    "ourhdr.h"

pid_t
pty_fork(int *ptrfdm, char *slave_name,
         const struct termios *slave_termios,
         const struct winsize *slave_winsize)
{
    int        fdm, fds;
    pid_t    pid;
    char    pts_name[20];

    if ( (fdm = ptym_open(pts_name)) < 0)
        err_sys("can't open master pty: %s", pts_name);

    if (slave_name != NULL)
        strcpy(slave_name, pts_name);    /* return name of slave */

    if ( (pid = fork()) < 0)
        return(-1);

    else if (pid == 0) {        /* child */
        if (setsid() < 0)
            err_sys("setsid error");

                    /* SVR4 acquires controlling terminal on open() */
        if ( (fds = ptys_open(fdm, pts_name)) < 0)
            err_sys("can't open slave pty");
        close(fdm);        /* all done with master in child */

#if    defined(TIOCSCTTY) && !defined(CIBAUD)
                /* 44BSD way to acquire controlling terminal */
                /* !CIBAUD to avoid doing this under SunOS */
        if (ioctl(fds, TIOCSCTTY, (char *) 0) < 0)
            err_sys("TIOCSCTTY error");
#endif
                /* set slave's termios and window size */
        if (slave_termios != NULL) {
            if (tcsetattr(fds, TCSANOW, slave_termios) < 0)
                err_sys("tcsetattr error on slave pty");
        }
        if (slave_winsize != NULL) {
            if (ioctl(fds, TIOCSWINSZ, slave_winsize) < 0)
                err_sys("TIOCSWINSZ error on slave pty");
        }
                /* slave becomes stdin/stdout/stderr of child */
        if (dup2(fds, STDIN_FILENO) != STDIN_FILENO)
            err_sys("dup2 error to stdin");
        if (dup2(fds, STDOUT_FILENO) != STDOUT_FILENO)
            err_sys("dup2 error to stdout");
        if (dup2(fds, STDERR_FILENO) != STDERR_FILENO)
            err_sys("dup2 error to stderr");
        if (fds > STDERR_FILENO)
            close(fds);
        return(0);        /* child returns 0 just like fork() */

    } else {                    /* parent */
        *ptrfdm = fdm;    /* return fd of master */
        return(pid);    /* parent returns pid of child */
    }
}