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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 1.19 2007/07/03 17:22:14 dillon Exp $
39 * Indirect driver for controlling tty.
42 #include <sys/param.h>
43 #include <sys/systm.h>
45 #include <sys/device.h>
47 #include <sys/fcntl.h>
49 #include <sys/ttycom.h>
50 #include <sys/vnode.h>
51 #include <sys/kernel.h>
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;
61 /* Don't make this static, since fdesc_vnops uses it. */
62 struct dev_ops ctty_ops = {
63 { "ctty", CDEV_MAJOR, D_TTY },
72 #define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
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.
80 cttyopen(struct dev_open_args *ap)
82 struct proc *p = curproc;
88 if ((ttyvp = cttyvp(p)) == NULL)
90 if (ttyvp->v_flag & VCTTYISOPEN)
94 * Messy interlock, don't let the vnode go away while we try to
95 * lock it and check for race after we might have blocked.
98 vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
99 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) {
100 kprintf("Warning: cttyopen: race avoided\n");
105 vsetflags(ttyvp, VCTTYISOPEN);
106 error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL);
108 vclrflags(ttyvp, VCTTYISOPEN);
115 * This closes /dev/tty. Because multiple opens of /dev/tty only
116 * generate a single open to the actual tty, the file modes are
117 * locked to FREAD|FWRITE.
120 cttyclose(struct dev_close_args *ap)
122 struct proc *p = curproc;
129 * The tty may have been TIOCNOTTY'd, don't return an
130 * error on close. We just have nothing to do.
132 if ((ttyvp = cttyvp(p)) == NULL)
134 if (ttyvp->v_flag & VCTTYISOPEN) {
136 * Avoid a nasty race if we block while getting the lock.
139 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
144 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) {
145 kprintf("Warning: cttyclose: race avoided\n");
150 vclrflags(ttyvp, VCTTYISOPEN);
151 error = VOP_CLOSE(ttyvp, FREAD|FWRITE);
161 * Read from the controlling terminal (/dev/tty). The tty is refed as
162 * of the cttyvp(), but the ref can get ripped out from under us if
163 * the controlling terminal is revoked while we are blocked on the lock,
164 * so use vget() instead of vn_lock().
167 cttyread(struct dev_read_args *ap)
169 struct proc *p = curproc;
177 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
178 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
185 * Read from the controlling terminal (/dev/tty). The tty is refed as
186 * of the cttyvp(), but the ref can get ripped out from under us if
187 * the controlling terminal is revoked while we are blocked on the lock,
188 * so use vget() instead of vn_lock().
191 cttywrite(struct dev_write_args *ap)
193 struct proc *p = curproc;
201 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
202 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
210 cttyioctl(struct dev_ioctl_args *ap)
213 struct proc *p = curproc;
220 * Don't allow controlling tty to be set to the controlling tty
221 * (infinite recursion).
223 if (ap->a_cmd == TIOCSCTTY)
225 if (ap->a_cmd == TIOCNOTTY) {
226 if (!SESS_LEADER(p)) {
227 p->p_flag &= ~P_CONTROLT;
233 return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag, ap->a_cred));
238 cttypoll(struct dev_poll_args *ap)
240 cdev_t dev = ap->a_head.a_dev;
242 struct proc *p = curproc;
247 * try operation to get EOF/failure
250 ap->a_events = seltrue(dev, ap->a_events);
252 ap->a_events = VOP_POLL(ttyvp, ap->a_events, p->p_ucred);
257 ctty_drvinit(void *unused __unused)
259 dev_ops_add(&ctty_ops, 0, 0);
260 make_dev(&ctty_ops, 0, 0, 0, 0666, "tty");
263 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)