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35 * @(#)tty_tty.c 8.2 (Berkeley) 9/23/93
36 * $FreeBSD: src/sys/kern/tty_tty.c,v 1.30 1999/09/25 18:24:24 phk Exp $
40 * Indirect driver for controlling tty.
43 #include <sys/param.h>
44 #include <sys/systm.h>
46 #include <sys/device.h>
48 #include <sys/fcntl.h>
50 #include <sys/ttycom.h>
51 #include <sys/vnode.h>
52 #include <sys/kernel.h>
53 #include <sys/poll.h> /* XXX: poll args used in KQ filters */
54 #include <sys/event.h>
56 static d_open_t cttyopen;
57 static d_close_t cttyclose;
58 static d_read_t cttyread;
59 static d_write_t cttywrite;
60 static d_ioctl_t cttyioctl;
61 static d_kqfilter_t cttykqfilter;
63 static void cttyfilt_detach(struct knote *);
64 static int cttyfilt_read(struct knote *, long);
65 static int cttyfilt_write(struct knote *, long);
68 static struct dev_ops ctty_ops = {
75 .d_kqfilter = cttykqfilter
78 #define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
81 * This opens /dev/tty. Because multiple opens of /dev/tty only
82 * generate a single open to the actual tty, the file modes are
83 * locked to FREAD|FWRITE.
86 cttyopen(struct dev_open_args *ap)
88 struct proc *p = curproc;
94 if ((ttyvp = cttyvp(p)) == NULL)
96 if (ttyvp->v_flag & VCTTYISOPEN)
100 * Messy interlock, don't let the vnode go away while we try to
101 * lock it and check for race after we might have blocked.
104 vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
105 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) {
106 kprintf("Warning: cttyopen: race avoided\n");
111 vsetflags(ttyvp, VCTTYISOPEN);
112 error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL);
114 vclrflags(ttyvp, VCTTYISOPEN);
121 * This closes /dev/tty. Because multiple opens of /dev/tty only
122 * generate a single open to the actual tty, the file modes are
123 * locked to FREAD|FWRITE.
126 cttyclose(struct dev_close_args *ap)
128 struct proc *p = curproc;
135 * The tty may have been TIOCNOTTY'd, don't return an
136 * error on close. We just have nothing to do.
138 if ((ttyvp = cttyvp(p)) == NULL)
140 if (ttyvp->v_flag & VCTTYISOPEN) {
142 * Avoid a nasty race if we block while getting the lock.
145 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
150 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) {
151 kprintf("Warning: cttyclose: race avoided\n");
156 vclrflags(ttyvp, VCTTYISOPEN);
157 error = VOP_CLOSE(ttyvp, FREAD|FWRITE);
167 * Read from the controlling terminal (/dev/tty). The tty is refed as
168 * of the cttyvp(), but the ref can get ripped out from under us if
169 * the controlling terminal is revoked while we are blocked on the lock,
170 * so use vget() instead of vn_lock().
173 cttyread(struct dev_read_args *ap)
175 struct proc *p = curproc;
183 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
184 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
191 * Read from the controlling terminal (/dev/tty). The tty is refed as
192 * of the cttyvp(), but the ref can get ripped out from under us if
193 * the controlling terminal is revoked while we are blocked on the lock,
194 * so use vget() instead of vn_lock().
197 cttywrite(struct dev_write_args *ap)
199 struct proc *p = curproc;
207 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
208 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
216 cttyioctl(struct dev_ioctl_args *ap)
219 struct proc *p = curproc;
222 lwkt_gettoken(&proc_token);
225 lwkt_reltoken(&proc_token);
229 * Don't allow controlling tty to be set to the controlling tty
230 * (infinite recursion).
232 if (ap->a_cmd == TIOCSCTTY) {
233 lwkt_reltoken(&proc_token);
236 if (ap->a_cmd == TIOCNOTTY) {
237 if (!SESS_LEADER(p)) {
238 p->p_flag &= ~P_CONTROLT;
239 lwkt_reltoken(&proc_token);
242 lwkt_reltoken(&proc_token);
246 lwkt_reltoken(&proc_token);
248 return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag,
249 ap->a_cred, ap->a_sysmsg));
252 static struct filterops cttyfiltops_read =
253 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_read };
254 static struct filterops cttyfiltops_write =
255 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_write };
258 cttykqfilter(struct dev_kqfilter_args *ap)
260 cdev_t dev = ap->a_head.a_dev;
261 struct proc *p = curproc;
262 struct knote *kn = ap->a_kn;
269 return (VOP_KQFILTER(ttyvp, kn));
273 switch (kn->kn_filter) {
275 kn->kn_fop = &cttyfiltops_read;
276 kn->kn_hook = (caddr_t)dev;
279 kn->kn_fop = &cttyfiltops_write;
280 kn->kn_hook = (caddr_t)dev;
283 ap->a_result = EOPNOTSUPP;
291 cttyfilt_detach(struct knote *kn) {}
294 cttyfilt_read(struct knote *kn, long hint)
296 cdev_t dev = (cdev_t)kn->kn_hook;
298 if (seltrue(dev, POLLIN | POLLRDNORM))
305 cttyfilt_write(struct knote *kn, long hint)
307 cdev_t dev = (cdev_t)kn->kn_hook;
309 if (seltrue(dev, POLLOUT | POLLWRNORM))
316 ctty_drvinit(void *unused __unused)
318 make_dev(&ctty_ops, 0, 0, 0, 0666, "tty");
321 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)