usr/src/sys/kern/tty_tty.c

/*-
 * Copyright (c) 1982, 1986, 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)tty_tty.c   7.22 (Berkeley) %G%
 */

/*
 * Indirect driver for controlling tty.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/vnode.h>
#include <sys/file.h>

#define cttyvp(p) ((p)->p_flag&SCTTY ? (p)->p_session->s_ttyvp : NULL)

/*ARGSUSED*/
cttyopen(dev, flag, mode, p)
        dev_t dev;
        int flag, mode;
        struct proc *p;
{
        struct vnode *ttyvp = cttyvp(p);
        int error;

        if (ttyvp == NULL)
                return (ENXIO);
        VOP_LOCK(ttyvp);
#ifdef PARANOID
        /*
         * Since group is tty and mode is 620 on most terminal lines
         * and since sessions protect terminals from processes outside
         * your session, this check is probably no longer necessary.
         * Since it inhibits setuid root programs that later switch
         * to another user from accessing /dev/tty, we have decided
         * to delete this test. (mckusick 5/93)
         */
        error = VOP_ACCESS(ttyvp,
          (flag&FREAD ? VREAD : 0) | (flag&FWRITE ? VWRITE : 0), p->p_ucred, p);
        if (!error)
#endif /* PARANOID */
                error = VOP_OPEN(ttyvp, flag, NOCRED, p);
        VOP_UNLOCK(ttyvp);
        return (error);
}

/*ARGSUSED*/
cttyread(dev, uio, flag)
        dev_t dev;
        struct uio *uio;
        int flag;
{
        register struct vnode *ttyvp = cttyvp(uio->uio_procp);
        int error;

        if (ttyvp == NULL)
                return (EIO);
        VOP_LOCK(ttyvp);
        error = VOP_READ(ttyvp, uio, flag, NOCRED);
        VOP_UNLOCK(ttyvp);
        return (error);
}

/*ARGSUSED*/
cttywrite(dev, uio, flag)
        dev_t dev;
        struct uio *uio;
        int flag;
{
        register struct vnode *ttyvp = cttyvp(uio->uio_procp);
        int error;

        if (ttyvp == NULL)
                return (EIO);
        VOP_LOCK(ttyvp);
        error = VOP_WRITE(ttyvp, uio, flag, NOCRED);
        VOP_UNLOCK(ttyvp);
        return (error);
}

/*ARGSUSED*/
cttyioctl(dev, cmd, addr, flag, p)
        dev_t dev;
        int cmd;
        caddr_t addr;
        int flag;
        struct proc *p;
{
        struct vnode *ttyvp = cttyvp(p);

        if (ttyvp == NULL)
                return (EIO);
        if (cmd == TIOCNOTTY) {
                if (!SESS_LEADER(p)) {
                        p->p_flag &= ~SCTTY;
                        return (0);
                } else
                        return (EINVAL);
        }
        return (VOP_IOCTL(ttyvp, cmd, addr, flag, NOCRED, p));
}

/*ARGSUSED*/
cttyselect(dev, flag, p)
        dev_t dev;
        int flag;
        struct proc *p;
{
        struct vnode *ttyvp = cttyvp(p);

        if (ttyvp == NULL)
                return (1);     /* try operation to get EOF/failure */
        return (VOP_SELECT(ttyvp, flag, FREAD|FWRITE, NOCRED, p));
}