1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2003 Poul-Henning Kamp. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/eventhandler.h> 32 #include <sys/conf.h> 33 #include <sys/kernel.h> 34 #include <sys/proc.h> 35 #include <sys/sx.h> 36 #include <sys/vnode.h> 37 38 #include <fs/devfs/devfs.h> 39 #include <fs/devfs/devfs_int.h> 40 41 static d_open_t cttyopen; 42 43 static struct cdevsw ctty_cdevsw = { 44 .d_version = D_VERSION, 45 .d_open = cttyopen, 46 .d_name = "ctty", 47 }; 48 49 static struct cdev *ctty; 50 51 static int 52 cttyopen(struct cdev *dev, int flag, int mode, struct thread *td) 53 { 54 55 return (ENXIO); 56 } 57 58 static void 59 ctty_clone(void *arg, struct ucred *cred, char *name, int namelen, 60 struct cdev **dev) 61 { 62 struct proc *p; 63 64 if (*dev != NULL) 65 return; 66 if (strcmp(name, "tty")) 67 return; 68 p = curproc; 69 sx_slock(&proctree_lock); 70 dev_lock(); 71 if (!(p->p_flag & P_CONTROLT)) 72 *dev = ctty; 73 else if (p->p_session->s_ttyvp == NULL) 74 *dev = ctty; 75 else if (p->p_session->s_ttyvp->v_type == VBAD || 76 p->p_session->s_ttyvp->v_rdev == NULL) { 77 /* e.g. s_ttyvp was revoked */ 78 *dev = ctty; 79 } else 80 *dev = p->p_session->s_ttyvp->v_rdev; 81 dev_refl(*dev); 82 dev_unlock(); 83 sx_sunlock(&proctree_lock); 84 } 85 86 static void 87 ctty_drvinit(void *unused) 88 { 89 90 EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000); 91 ctty = make_dev_credf(MAKEDEV_ETERNAL, &ctty_cdevsw, 0, NULL, UID_ROOT, 92 GID_WHEEL, 0666, "ctty"); 93 } 94 95 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL); 96