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31 * @(#)tty_tty.c 8.2 (Berkeley) 9/23/93
32 * $FreeBSD: src/sys/kern/tty_tty.c,v 1.30 1999/09/25 18:24:24 phk Exp $
36 * Indirect driver for controlling tty.
39 #include <sys/param.h>
40 #include <sys/systm.h>
42 #include <sys/device.h>
44 #include <sys/fcntl.h>
46 #include <sys/ttycom.h>
47 #include <sys/vnode.h>
48 #include <sys/kernel.h>
49 #include <sys/poll.h> /* XXX: poll args used in KQ filters */
50 #include <sys/event.h>
52 static d_open_t cttyopen;
53 static d_close_t cttyclose;
54 static d_read_t cttyread;
55 static d_write_t cttywrite;
56 static d_ioctl_t cttyioctl;
57 static d_kqfilter_t cttykqfilter;
59 static void cttyfilt_detach(struct knote *);
60 static int cttyfilt_read(struct knote *, long);
61 static int cttyfilt_write(struct knote *, long);
64 static struct dev_ops ctty_ops = {
71 .d_kqfilter = cttykqfilter
74 #define cttyvp(p) (((p)->p_flags & P_CONTROLT) ? \
75 (p)->p_session->s_ttyvp : NULL)
78 * This opens /dev/tty. Because multiple opens of /dev/tty only
79 * generate a single open to the actual tty, the file modes are
80 * locked to FREAD|FWRITE.
83 cttyopen(struct dev_open_args *ap)
85 struct proc *p = curproc;
91 if ((ttyvp = cttyvp(p)) == NULL)
93 if (ttyvp->v_flag & VCTTYISOPEN)
97 * Messy interlock, don't let the vnode go away while we try to
98 * lock it and check for race after we might have blocked.
101 vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
102 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) {
103 kprintf("Warning: cttyopen: race avoided\n");
108 vsetflags(ttyvp, VCTTYISOPEN);
109 error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL);
111 vclrflags(ttyvp, VCTTYISOPEN);
118 * This closes /dev/tty. Because multiple opens of /dev/tty only
119 * generate a single open to the actual tty, the file modes are
120 * locked to FREAD|FWRITE.
123 cttyclose(struct dev_close_args *ap)
125 struct proc *p = curproc;
132 * The tty may have been TIOCNOTTY'd, don't return an
133 * error on close. We just have nothing to do.
135 if ((ttyvp = cttyvp(p)) == NULL)
137 if (ttyvp->v_flag & VCTTYISOPEN) {
139 * Avoid a nasty race if we block while getting the lock.
142 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
147 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) {
148 kprintf("Warning: cttyclose: race avoided\n");
153 vclrflags(ttyvp, VCTTYISOPEN);
154 error = VOP_CLOSE(ttyvp, FREAD|FWRITE);
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().
170 cttyread(struct dev_read_args *ap)
172 struct proc *p = curproc;
180 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
181 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
188 * Read from the controlling terminal (/dev/tty). The tty is refed as
189 * of the cttyvp(), but the ref can get ripped out from under us if
190 * the controlling terminal is revoked while we are blocked on the lock,
191 * so use vget() instead of vn_lock().
194 cttywrite(struct dev_write_args *ap)
196 struct proc *p = curproc;
204 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
205 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
213 cttyioctl(struct dev_ioctl_args *ap)
216 struct proc *p = curproc;
219 lwkt_gettoken(&p->p_token);
220 lwkt_gettoken(&proc_token);
223 lwkt_reltoken(&proc_token);
224 lwkt_reltoken(&p->p_token);
228 * Don't allow controlling tty to be set to the controlling tty
229 * (infinite recursion).
231 if (ap->a_cmd == TIOCSCTTY) {
232 lwkt_reltoken(&proc_token);
233 lwkt_reltoken(&p->p_token);
236 if (ap->a_cmd == TIOCNOTTY) {
237 if (!SESS_LEADER(p)) {
238 p->p_flags &= ~P_CONTROLT;
239 lwkt_reltoken(&proc_token);
240 lwkt_reltoken(&p->p_token);
243 lwkt_reltoken(&proc_token);
244 lwkt_reltoken(&p->p_token);
248 lwkt_reltoken(&proc_token);
249 lwkt_reltoken(&p->p_token);
251 return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag,
252 ap->a_cred, ap->a_sysmsg));
255 static struct filterops cttyfiltops_read =
256 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_read };
257 static struct filterops cttyfiltops_write =
258 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_write };
261 cttykqfilter(struct dev_kqfilter_args *ap)
263 cdev_t dev = ap->a_head.a_dev;
264 struct proc *p = curproc;
265 struct knote *kn = ap->a_kn;
272 return (VOP_KQFILTER(ttyvp, kn));
276 switch (kn->kn_filter) {
278 kn->kn_fop = &cttyfiltops_read;
279 kn->kn_hook = (caddr_t)dev;
282 kn->kn_fop = &cttyfiltops_write;
283 kn->kn_hook = (caddr_t)dev;
286 ap->a_result = EOPNOTSUPP;
294 cttyfilt_detach(struct knote *kn) {}
297 cttyfilt_read(struct knote *kn, long hint)
299 cdev_t dev = (cdev_t)kn->kn_hook;
301 if (seltrue(dev, POLLIN | POLLRDNORM))
308 cttyfilt_write(struct knote *kn, long hint)
310 cdev_t dev = (cdev_t)kn->kn_hook;
312 if (seltrue(dev, POLLOUT | POLLWRNORM))
319 ctty_drvinit(void *unused __unused)
321 make_dev(&ctty_ops, 0, 0, 0, 0666, "tty");
324 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)