/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */


                                        /* from S5R4 1.22 */

/*
 * Indirect driver for controlling tty.
 */
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/stream.h>
#include <sys/strsubr.h>
#include <sys/cred.h>
#include <sys/uio.h>
#include <sys/session.h>
#include <sys/ddi.h>
#include <sys/debug.h>
#include <sys/stat.h>
#include <sys/sunddi.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/modctl.h>
#include <sys/fs/snode.h>
#include <sys/file.h>

#define IS_STREAM(dev) (devopsp[getmajor(dev)]->devo_cb_ops->cb_str != NULL)

int syopen(dev_t *, int, int, cred_t *);
int syclose(dev_t, int, int, cred_t *);
int syread(dev_t, struct uio *, cred_t *);
int sywrite(dev_t, struct uio *, cred_t *);
int sypoll(dev_t, short, int, short *, struct pollhead **);
int syioctl(dev_t, int, intptr_t, int, cred_t *, int *);

static int sy_info(dev_info_t *, ddi_info_cmd_t, void *, void **);
static int sy_attach(dev_info_t *, ddi_attach_cmd_t);
static dev_info_t *sy_dip;              /* private copy of devinfo pointer */

struct cb_ops   sy_cb_ops = {

        syopen,                 /* open */
        syclose,                /* close */
        nodev,                  /* strategy */
        nodev,                  /* print */
        nodev,                  /* dump */
        syread,                 /* read */
        sywrite,                /* write */
        syioctl,                /* ioctl */
        nodev,                  /* devmap */
        nodev,                  /* mmap */
        nodev,                  /* segmap */
        sypoll,                 /* poll */
        ddi_prop_op,            /* cb_prop_op */
        0,                      /* streamtab  */
        D_NEW | D_MP            /* Driver compatibility flag */

};

struct dev_ops  sy_ops = {

        DEVO_REV,               /* devo_rev, */
        0,                      /* refcnt  */
        sy_info,                /* info */
        nulldev,                /* identify */
        nulldev,                /* probe */
        sy_attach,              /* attach */
        nodev,                  /* detach */
        nodev,                  /* reset */
        &sy_cb_ops,             /* driver operations */
        (struct bus_ops *)0,    /* bus operations */
        NULL,                   /* power */
        ddi_quiesce_not_needed,         /* quiesce */
};


extern int nodev(void);
extern int nulldev(void);
extern int dseekneg_flag;
extern struct mod_ops mod_driverops;
extern struct dev_ops sy_ops;

/*
 * Module linkage information for the kernel.
 */

static struct modldrv modldrv = {
        &mod_driverops, /* Type of module.  This one is a pseudo driver */
        "Indirect driver for tty 'sy'",
        &sy_ops,        /* driver ops */
};

static struct modlinkage modlinkage = {
        MODREV_1,
        &modldrv,
        NULL
};


int
_init(void)
{
        return (mod_install(&modlinkage));
}


int
_fini(void)
{
        return (mod_remove(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
        return (mod_info(&modlinkage, modinfop));
}

/* ARGSUSED */
static int
sy_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
        if (ddi_create_minor_node(devi, "tty", S_IFCHR,
            0, DDI_PSEUDO, 0) == DDI_FAILURE) {
                ddi_remove_minor_node(devi, NULL);
                return (-1);
        }
        sy_dip = devi;
        return (DDI_SUCCESS);
}

/* ARGSUSED */
static int
sy_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
{
        dev_t dev = (dev_t)arg;
        int error;

        switch (infocmd) {
        case DDI_INFO_DEVT2DEVINFO:
                if (sy_dip == NULL) {
                        *result = (void *)NULL;
                        error = DDI_FAILURE;
                } else {
                        *result = (void *) sy_dip;
                        error = DDI_SUCCESS;
                }
                break;
        case DDI_INFO_DEVT2INSTANCE:
                if (getminor(dev) != 0) {
                        *result = (void *)-1;
                        error = DDI_FAILURE;
                } else {
                        *result = (void *)0;
                        error = DDI_SUCCESS;
                }
                break;
        default:
                error = DDI_FAILURE;
        }
        return (error);
}


/* ARGSUSED */
int
syopen(dev_t *devp, int flag, int otyp, struct cred *cr)
{
        dev_t   ttyd;
        vnode_t *ttyvp;
        sess_t  *sp;
        int     error;

        if ((sp = tty_hold()) == NULL)
                return (EINTR);

        if (sp->s_dev == NODEV) {
                tty_rele(sp);
                return (ENXIO);
        }

        ttyd = sp->s_dev;
        ttyvp = sp->s_vp;

        /*
         * Open the control terminal. The control terminal may be
         * opened multiple times and it is closed in freectty().
         * The multi-open, single-clone means that no cloning
         * can happen via this open, hence the assertion.
         */
        error = VOP_OPEN(&ttyvp, FNOCTTY | flag, cr, NULL);
        if (error == 0) {
                struct snode *csp;

                /*
                 * XXX: This driver binds a single minor number to the
                 * current controlling tty of the process issueing the
                 * open / close.  If we implement a traditional close
                 * for this driver then specfs will only invoke this driver
                 * on the last close of our one minor number - which is not
                 * what we want.  Since we already get the open / close
                 * semantic that we want from makectty and freectty, we reach
                 * back into the common snode and decrease the open count so
                 * that the specfs filtering of all but the last close
                 * does not get in our way.  To clean this up, a new cb_flag
                 * that causes specfs to call the driver on each close
                 * should be considered.
                 */
                ASSERT(ttyd == ttyvp->v_rdev);
                ASSERT(vn_matchops(ttyvp, spec_getvnodeops()));
                csp = VTOS(VTOS(ttyvp)->s_commonvp);
                mutex_enter(&csp->s_lock);
                ASSERT(csp->s_count > 1);
                csp->s_count--;
                mutex_exit(&csp->s_lock);
        }

        tty_rele(sp);
        return (error);
}

/* ARGSUSED */
int
syclose(dev_t dev, int flag, int otyp, struct cred *cr)
{
        return (0);
}

/* ARGSUSED */
int
syread(dev_t dev, struct uio *uiop, struct cred *cr)
{
        sess_t  *sp;
        int     error;

        if ((sp = tty_hold()) == NULL)
                return (EINTR);

        if (sp->s_dev == NODEV) {
                tty_rele(sp);
                return (ENXIO);
        }

        error = VOP_READ(sp->s_vp, uiop, 0, cr, NULL);

        tty_rele(sp);
        return (error);
}

/* ARGSUSED */
int
sywrite(dev_t dev, struct uio *uiop, struct cred *cr)
{
        sess_t  *sp;
        int     error;

        if ((sp = tty_hold()) == NULL)
                return (EINTR);

        if (sp->s_dev == NODEV) {
                tty_rele(sp);
                return (ENXIO);
        }

        error = VOP_WRITE(sp->s_vp, uiop, 0, cr, NULL);

        tty_rele(sp);
        return (error);
}


/* ARGSUSED */
int
syioctl(dev_t dev, int cmd, intptr_t arg, int mode, struct cred *cr,
    int *rvalp)
{
        sess_t  *sp;
        int     error;

        if (cmd == TIOCNOTTY) {
                /*
                 * we can't allow this ioctl.  the reason is that it
                 * attempts to remove the ctty for a session.  to do
                 * this the ctty can't be in use  but we grab a hold on
                 * the current ctty (via tty_hold) to perform this ioctl.
                 * if we were to allow this ioctl to pass through we
                 * would deadlock with ourselves.
                 */
                return (EINVAL);
        }

        if ((sp = tty_hold()) == NULL)
                return (EINTR);

        if (sp->s_dev == NODEV) {
                tty_rele(sp);
                return (ENXIO);
        }

        error = VOP_IOCTL(sp->s_vp, cmd, arg, mode, cr, rvalp, NULL);

        tty_rele(sp);
        return (error);
}



/* ARGSUSED */
int
sypoll(dev_t dev, short events, int anyyet, short *reventsp,
    struct pollhead **phpp)
{
        sess_t  *sp;
        int     error;

        if ((sp = tty_hold()) == NULL)
                return (EINTR);

        if (sp->s_dev == NODEV) {
                tty_rele(sp);
                return (ENXIO);
        }

        error = VOP_POLL(sp->s_vp, events, anyyet, reventsp, phpp, NULL);

        tty_rele(sp);
        return (error);
}