sys/kern/tty_tty.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)tty_tty.c   8.2 (Berkeley) 9/23/93
  34  * $FreeBSD: src/sys/kern/tty_tty.c,v 1.30 1999/09/25 18:24:24 phk Exp $
  35  * $DragonFly: src/sys/kern/tty_tty.c,v 1.18 2006/09/10 01:26:39 dillon Exp $
  36  */
  37
  38 /*
  39  * Indirect driver for controlling tty.
  40  */
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/conf.h>
  45 #include <sys/device.h>
  46 #include <sys/lock.h>
  47 #include <sys/fcntl.h>
  48 #include <sys/proc.h>
  49 #include <sys/ttycom.h>
  50 #include <sys/vnode.h>
  51 #include <sys/kernel.h>
  52
  53 static  d_open_t        cttyopen;
  54 static  d_close_t       cttyclose;
  55 static  d_read_t        cttyread;
  56 static  d_write_t       cttywrite;
  57 static  d_ioctl_t       cttyioctl;
  58 static  d_poll_t        cttypoll;
  59
  60 #define CDEV_MAJOR      1
  61 /* Don't make this static, since fdesc_vnops uses it. */
  62 struct dev_ops ctty_ops = {
  63         { "ctty", CDEV_MAJOR, D_TTY },
  64         .d_open =       cttyopen,
  65         .d_close =      cttyclose,
  66         .d_read =       cttyread,
  67         .d_write =      cttywrite,
  68         .d_ioctl =      cttyioctl,
  69         .d_poll =       cttypoll,
  70 };
  71
  72 #define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
  73
  74 /*
  75  * This opens /dev/tty.  Because multiple opens of /dev/tty only
  76  * generate a single open to the actual tty, the file modes are
  77  * locked to FREAD|FWRITE.
  78  */
  79 static  int
  80 cttyopen(struct dev_open_args *ap)
  81 {
  82         struct proc *p = curproc;
  83         struct vnode *ttyvp;
  84         int error;
  85
  86         KKASSERT(p);
  87         ttyvp = cttyvp(p);
  88         if (ttyvp) {
  89                 if (ttyvp->v_flag & VCTTYISOPEN) {
  90                         error = 0;
  91                 } else {
  92                         vsetflags(ttyvp, VCTTYISOPEN);
  93                         vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
  94                         error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL);
  95                         if (error)
  96                                 vclrflags(ttyvp, VCTTYISOPEN);
  97                         vn_unlock(ttyvp);
  98                 }
  99         } else {
 100                 error = ENXIO;
 101         }
 102         return (error);
 103 }
 104
 105 /*
 106  * This closes /dev/tty.  Because multiple opens of /dev/tty only
 107  * generate a single open to the actual tty, the file modes are
 108  * locked to FREAD|FWRITE.
 109  */
 110 static int
 111 cttyclose(struct dev_close_args *ap)
 112 {
 113         struct proc *p = curproc;
 114         struct vnode *ttyvp;
 115         int error;
 116
 117         KKASSERT(p);
 118         ttyvp = cttyvp(p);
 119         if (ttyvp == NULL) {
 120                 /*
 121                  * The tty may have been TIOCNOTTY'd, don't return an
 122                  * error on close.  We just have nothing to do.
 123                  */
 124                 /* error = EIO; */
 125                 error = 0;
 126         } else if (ttyvp->v_flag & VCTTYISOPEN) {
 127                 vclrflags(ttyvp, VCTTYISOPEN);
 128                 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
 129                 if (error == 0) {
 130                         error = VOP_CLOSE(ttyvp, FREAD|FWRITE);
 131                         vn_unlock(ttyvp);
 132                 }
 133         } else {
 134                 error = 0;
 135         }
 136         return(error);
 137 }
 138
 139 /*
 140  * Read from the controlling terminal (/dev/tty).  The tty is refed as
 141  * of the cttyvp(), but the ref can get ripped out from under us if
 142  * the controlling terminal is revoked while we are blocked on the lock,
 143  * so use vget() instead of vn_lock().
 144  */
 145 static  int
 146 cttyread(struct dev_read_args *ap)
 147 {
 148         struct proc *p = curproc;
 149         struct vnode *ttyvp;
 150         int error;
 151
 152         KKASSERT(p);
 153         ttyvp = cttyvp(p);
 154         if (ttyvp == NULL)
 155                 return (EIO);
 156         if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
 157                 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
 158                 vput(ttyvp);
 159         }
 160         return (error);
 161 }
 162
 163 /*
 164  * Read from the controlling terminal (/dev/tty).  The tty is refed as
 165  * of the cttyvp(), but the ref can get ripped out from under us if
 166  * the controlling terminal is revoked while we are blocked on the lock,
 167  * so use vget() instead of vn_lock().
 168  */
 169 static  int
 170 cttywrite(struct dev_write_args *ap)
 171 {
 172         struct proc *p = curproc;
 173         struct vnode *ttyvp;
 174         int error;
 175
 176         KKASSERT(p);
 177         ttyvp = cttyvp(p);
 178         if (ttyvp == NULL)
 179                 return (EIO);
 180         if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
 181                 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
 182                 vput(ttyvp);
 183         }
 184         return (error);
 185 }
 186
 187 /*ARGSUSED*/
 188 static  int
 189 cttyioctl(struct dev_ioctl_args *ap)
 190 {
 191         struct vnode *ttyvp;
 192         struct proc *p = curproc;
 193
 194         KKASSERT(p);
 195         ttyvp = cttyvp(p);
 196         if (ttyvp == NULL)
 197                 return (EIO);
 198         /*
 199          * Don't allow controlling tty to be set to the controlling tty
 200          * (infinite recursion).
 201          */
 202         if (ap->a_cmd == TIOCSCTTY)
 203                 return EINVAL;
 204         if (ap->a_cmd == TIOCNOTTY) {
 205                 if (!SESS_LEADER(p)) {
 206                         p->p_flag &= ~P_CONTROLT;
 207                         return (0);
 208                 } else {
 209                         return (EINVAL);
 210                 }
 211         }
 212         return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag, ap->a_cred));
 213 }
 214
 215 /*ARGSUSED*/
 216 static  int
 217 cttypoll(struct dev_poll_args *ap)
 218 {
 219         cdev_t dev = ap->a_head.a_dev;
 220         struct vnode *ttyvp;
 221         struct proc *p = curproc;
 222
 223         KKASSERT(p);
 224         ttyvp = cttyvp(p);
 225         /*
 226          * try operation to get EOF/failure
 227          */
 228         if (ttyvp == NULL)
 229                 ap->a_events = seltrue(dev, ap->a_events);
 230         else
 231                 ap->a_events = VOP_POLL(ttyvp, ap->a_events, p->p_ucred);
 232         return(0);
 233 }
 234
 235 static void
 236 ctty_drvinit(void *unused __unused)
 237 {
 238         dev_ops_add(&ctty_ops, 0, 0);
 239         make_dev(&ctty_ops, 0, 0, 0, 0666, "tty");
 240 }
 241
 242 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)