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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_flags & P_CONTROLT) ? \
79 (p)->p_session->s_ttyvp : NULL)
82 * This opens /dev/tty. Because multiple opens of /dev/tty only
83 * generate a single open to the actual tty, the file modes are
84 * locked to FREAD|FWRITE.
87 cttyopen(struct dev_open_args *ap)
89 struct proc *p = curproc;
95 if ((ttyvp = cttyvp(p)) == NULL)
97 if (ttyvp->v_flag & VCTTYISOPEN)
101 * Messy interlock, don't let the vnode go away while we try to
102 * lock it and check for race after we might have blocked.
105 vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
106 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) {
107 kprintf("Warning: cttyopen: race avoided\n");
112 vsetflags(ttyvp, VCTTYISOPEN);
113 error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL);
115 vclrflags(ttyvp, VCTTYISOPEN);
122 * This closes /dev/tty. Because multiple opens of /dev/tty only
123 * generate a single open to the actual tty, the file modes are
124 * locked to FREAD|FWRITE.
127 cttyclose(struct dev_close_args *ap)
129 struct proc *p = curproc;
136 * The tty may have been TIOCNOTTY'd, don't return an
137 * error on close. We just have nothing to do.
139 if ((ttyvp = cttyvp(p)) == NULL)
141 if (ttyvp->v_flag & VCTTYISOPEN) {
143 * Avoid a nasty race if we block while getting the lock.
146 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
151 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) {
152 kprintf("Warning: cttyclose: race avoided\n");
157 vclrflags(ttyvp, VCTTYISOPEN);
158 error = VOP_CLOSE(ttyvp, FREAD|FWRITE);
168 * Read from the controlling terminal (/dev/tty). The tty is refed as
169 * of the cttyvp(), but the ref can get ripped out from under us if
170 * the controlling terminal is revoked while we are blocked on the lock,
171 * so use vget() instead of vn_lock().
174 cttyread(struct dev_read_args *ap)
176 struct proc *p = curproc;
184 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
185 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
192 * Read from the controlling terminal (/dev/tty). The tty is refed as
193 * of the cttyvp(), but the ref can get ripped out from under us if
194 * the controlling terminal is revoked while we are blocked on the lock,
195 * so use vget() instead of vn_lock().
198 cttywrite(struct dev_write_args *ap)
200 struct proc *p = curproc;
208 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
209 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
217 cttyioctl(struct dev_ioctl_args *ap)
220 struct proc *p = curproc;
223 lwkt_gettoken(&p->p_token);
224 lwkt_gettoken(&proc_token);
227 lwkt_reltoken(&proc_token);
228 lwkt_reltoken(&p->p_token);
232 * Don't allow controlling tty to be set to the controlling tty
233 * (infinite recursion).
235 if (ap->a_cmd == TIOCSCTTY) {
236 lwkt_reltoken(&proc_token);
237 lwkt_reltoken(&p->p_token);
240 if (ap->a_cmd == TIOCNOTTY) {
241 if (!SESS_LEADER(p)) {
242 p->p_flags &= ~P_CONTROLT;
243 lwkt_reltoken(&proc_token);
244 lwkt_reltoken(&p->p_token);
247 lwkt_reltoken(&proc_token);
248 lwkt_reltoken(&p->p_token);
252 lwkt_reltoken(&proc_token);
253 lwkt_reltoken(&p->p_token);
255 return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag,
256 ap->a_cred, ap->a_sysmsg));
259 static struct filterops cttyfiltops_read =
260 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_read };
261 static struct filterops cttyfiltops_write =
262 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_write };
265 cttykqfilter(struct dev_kqfilter_args *ap)
267 cdev_t dev = ap->a_head.a_dev;
268 struct proc *p = curproc;
269 struct knote *kn = ap->a_kn;
276 return (VOP_KQFILTER(ttyvp, kn));
280 switch (kn->kn_filter) {
282 kn->kn_fop = &cttyfiltops_read;
283 kn->kn_hook = (caddr_t)dev;
286 kn->kn_fop = &cttyfiltops_write;
287 kn->kn_hook = (caddr_t)dev;
290 ap->a_result = EOPNOTSUPP;
298 cttyfilt_detach(struct knote *kn) {}
301 cttyfilt_read(struct knote *kn, long hint)
303 cdev_t dev = (cdev_t)kn->kn_hook;
305 if (seltrue(dev, POLLIN | POLLRDNORM))
312 cttyfilt_write(struct knote *kn, long hint)
314 cdev_t dev = (cdev_t)kn->kn_hook;
316 if (seltrue(dev, POLLOUT | POLLWRNORM))
323 ctty_drvinit(void *unused __unused)
325 make_dev(&ctty_ops, 0, 0, 0, 0666, "tty");
328 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)