1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
25 /* All Rights Reserved */
26
27 /*
28 * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
29 * Copyright 2021 Oxide Computer Company
30 */
31
32 /*
33 * PSEUDO-TERMINAL MANAGER DRIVER (PTM)
34 *
35 * The pseudo-terminal subsystem simulates a terminal connection, where the
36 * manager side represents the terminal and the subsidiary represents the user
37 * process's special device end point. The manager device is set up as a
38 * cloned device where its major device number is the major for the clone
39 * device and its minor device number is the major for the ptm driver. There
40 * are no nodes in the file system for manager devices. The manager pseudo
41 * driver is opened using the open(2) system call with /dev/ptmx as the device
42 * parameter. The clone open finds the next available minor device for the ptm
43 * major device.
44 *
45 * A manager device is available only if it and its corresponding subsidiary
46 * device are not already open. When the manager device is opened, the
47 * corresponding subsidiary device is automatically locked out. Only one open
48 * is allowed on a manager device. Multiple opens are allowed on the
49 * subsidiary device. After both the manager and subsidiary have been opened,
50 * the user has two file descriptors which are the end points of a full duplex
51 * connection composed of two streams which are automatically connected at the
52 * manager and subsidiary drivers. The user may then push modules onto either
53 * side of the stream pair.
54 *
55 * The manager and subsidiary drivers pass all messages to their adjacent
56 * queues. Only the M_FLUSH needs some processing. Because the read queue of
57 * one side is connected to the write queue of the other, the FLUSHR flag is
58 * changed to the FLUSHW flag and vice versa. When the manager device is
59 * closed an M_HANGUP message is sent to the subsidiary device which will
60 * render the device unusable. The process on the subsidiary side gets an EIO
61 * error when attempting to write on that stream but it will be able to read
62 * any data remaining on the stream head read queue. When all the data has
63 * been read, read() returns 0 indicating that the stream can no longer be
64 * used. On the last close of the subsidiary device, a 0-length message is
65 * sent to the manager device. When the application on the manager side issues
66 * a read() or getmsg() and 0 is returned, the user of the manager device
67 * decides whether to issue a close() that dismantles the pseudo-terminal
68 * subsystem. If the manager device is not closed, the pseudo-terminal
69 * subsystem will be available to another user to open the subsidiary device.
70 *
71 * If O_NONBLOCK or O_NDELAY is set, read on the manager side returns -1 with
72 * errno set to EAGAIN if no data is available, and write returns -1 with errno
73 * set to EAGAIN if there is internal flow control.
74 *
75 *
76 * IOCTLS
77 *
78 * ISPTM
79 * Determines whether the file descriptor is that of an open
80 * manager device. Return code of zero indicates that the file
81 * descriptor represents a manager device.
82 *
83 * UNLKPT
84 * Unlocks the manager and subsidiary devices. It returns 0 on
85 * success. On failure, the errno is set to EINVAL indicating that
86 * the manager device is not open.
87 *
88 * ZONEPT
89 * Sets the zone membership of the associated subsidiary device.
90 *
91 * GRPPT
92 * Sets the group owner of the associated subsidiary device.
93 *
94 *
95 * SYNCHRONIZATION
96 *
97 * All global data synchronization between ptm/pts is done via global ptms_lock
98 * mutex which is initialized at system boot time from ptms_initspace (called
99 * from space.c).
100 *
101 * Individual fields of pt_ttys structure (except ptm_rdq, pts_rdq and
102 * pt_nullmsg) are protected by pt_ttys.pt_lock mutex.
103 *
104 * PT_ENTER_READ/PT_ENTER_WRITE are reference counter based read-write locks
105 * which allow reader locks to be reacquired by the same thread (usual
106 * reader/writer locks can't be used for that purpose since it is illegal for a
107 * thread to acquire a lock it already holds, even as a reader). The sole
108 * purpose of these macros is to guarantee that the peer queue will not
109 * disappear (due to closing peer) while it is used. It is safe to use
110 * PT_ENTER_READ/PT_EXIT_READ brackets across calls like putq/putnext (since
111 * they are not real locks but reference counts).
112 *
113 * PT_ENTER_WRITE/PT_EXIT_WRITE brackets are used ONLY in manager/subsidiary
114 * open/close paths to modify ptm_rdq and pts_rdq fields. These fields should
115 * be set to appropriate queues *after* qprocson() is called during open (to
116 * prevent peer from accessing the queue with incomplete plumbing) and set to
117 * NULL before qprocsoff() is called during close.
118 *
119 * The pt_nullmsg field is only used in open/close routines and it is also
120 * protected by PT_ENTER_WRITE/PT_EXIT_WRITE brackets to avoid extra mutex
121 * holds.
122 *
123 *
124 * LOCK ORDERING
125 *
126 * If both ptms_lock and per-pty lock should be held, ptms_lock should always
127 * be entered first, followed by per-pty lock.
128 *
129 * See ptms.h, pts.c, and ptms_conf.c for more information.
130 */
131
132 #include <sys/types.h>
133 #include <sys/param.h>
134 #include <sys/file.h>
135 #include <sys/sysmacros.h>
136 #include <sys/stream.h>
137 #include <sys/stropts.h>
138 #include <sys/proc.h>
139 #include <sys/errno.h>
140 #include <sys/debug.h>
141 #include <sys/cmn_err.h>
142 #include <sys/ptms.h>
143 #include <sys/stat.h>
144 #include <sys/strsun.h>
145 #include <sys/systm.h>
146 #include <sys/modctl.h>
147 #include <sys/conf.h>
148 #include <sys/ddi.h>
149 #include <sys/sunddi.h>
150 #include <sys/zone.h>
151
152 #ifdef DEBUG
153 int ptm_debug = 0;
154 #define DBG(a) if (ptm_debug) cmn_err(CE_NOTE, a)
155 #else
156 #define DBG(a)
157 #endif
158
159 static int ptmopen(queue_t *, dev_t *, int, int, cred_t *);
160 static int ptmclose(queue_t *, int, cred_t *);
161 static int ptmwput(queue_t *, mblk_t *);
162 static int ptmrsrv(queue_t *);
163 static int ptmwsrv(queue_t *);
164
165 static struct module_info ptm_info = {
166 0xdead,
167 "ptm",
168 0,
169 512,
170 512,
171 128
172 };
173
174 static struct qinit ptmrint = {
175 NULL,
176 ptmrsrv,
177 ptmopen,
178 ptmclose,
179 NULL,
180 &ptm_info,
181 NULL
182 };
183
184 static struct qinit ptmwint = {
185 ptmwput,
186 ptmwsrv,
187 NULL,
188 NULL,
189 NULL,
190 &ptm_info,
191 NULL
192 };
193
194 static struct streamtab ptminfo = {
195 &ptmrint,
196 &ptmwint,
197 NULL,
198 NULL
199 };
200
201 static int ptm_attach(dev_info_t *, ddi_attach_cmd_t);
202 static int ptm_detach(dev_info_t *, ddi_detach_cmd_t);
203 static int ptm_devinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
204
205 static dev_info_t *ptm_dip; /* private devinfo pointer */
206
207 /*
208 * this will define (struct cb_ops cb_ptm_ops) and (struct dev_ops ptm_ops)
209 */
210 DDI_DEFINE_STREAM_OPS(ptm_ops, nulldev, nulldev, ptm_attach, ptm_detach,
211 nodev, ptm_devinfo, D_MP, &ptminfo, ddi_quiesce_not_supported);
212
213 /*
214 * Module linkage information for the kernel.
215 */
216
217 static struct modldrv modldrv = {
218 &mod_driverops,
219 "Pseudo-Terminal Manager Driver",
220 &ptm_ops,
221 };
222
223 static struct modlinkage modlinkage = {
224 MODREV_1,
225 &modldrv,
226 NULL
227 };
228
229 int
_init(void)230 _init(void)
231 {
232 int rc;
233
234 if ((rc = mod_install(&modlinkage)) == 0)
235 ptms_init();
236 return (rc);
237 }
238
239 int
_fini(void)240 _fini(void)
241 {
242 return (mod_remove(&modlinkage));
243 }
244
245 int
_info(struct modinfo * modinfop)246 _info(struct modinfo *modinfop)
247 {
248 return (mod_info(&modlinkage, modinfop));
249 }
250
251 static int
ptm_attach(dev_info_t * devi,ddi_attach_cmd_t cmd)252 ptm_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
253 {
254 if (cmd != DDI_ATTACH)
255 return (DDI_FAILURE);
256
257 if (ddi_create_minor_node(devi, "ptmajor", S_IFCHR,
258 0, DDI_PSEUDO, 0) == DDI_FAILURE) {
259 ddi_remove_minor_node(devi, NULL);
260 return (DDI_FAILURE);
261 }
262 if (ddi_create_minor_node(devi, "ptmx", S_IFCHR,
263 0, DDI_PSEUDO, CLONE_DEV) == DDI_FAILURE) {
264 ddi_remove_minor_node(devi, NULL);
265 return (DDI_FAILURE);
266 }
267 ptm_dip = devi;
268
269 return (DDI_SUCCESS);
270 }
271
272 static int
ptm_detach(dev_info_t * devi,ddi_detach_cmd_t cmd)273 ptm_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
274 {
275 if (cmd != DDI_DETACH)
276 return (DDI_FAILURE);
277
278 ddi_remove_minor_node(devi, NULL);
279 return (DDI_SUCCESS);
280 }
281
282 static int
ptm_devinfo(dev_info_t * dip,ddi_info_cmd_t infocmd,void * arg,void ** result)283 ptm_devinfo(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg,
284 void **result)
285 {
286 int error;
287
288 switch (infocmd) {
289 case DDI_INFO_DEVT2DEVINFO:
290 if (ptm_dip == NULL) {
291 error = DDI_FAILURE;
292 } else {
293 *result = (void *)ptm_dip;
294 error = DDI_SUCCESS;
295 }
296 break;
297 case DDI_INFO_DEVT2INSTANCE:
298 *result = (void *)0;
299 error = DDI_SUCCESS;
300 break;
301 default:
302 error = DDI_FAILURE;
303 }
304 return (error);
305 }
306
307
308 /*
309 * Open a minor of the manager device. Store the write queue pointer and set
310 * the pt_state field to (PTMOPEN | PTLOCK).
311 * This code will work properly with both clone opens and direct opens of the
312 * manager device.
313 */
314 static int
ptmopen(queue_t * rqp,dev_t * devp,int oflag,int sflag,cred_t * credp)315 ptmopen(
316 queue_t *rqp, /* pointer to the read side queue */
317 dev_t *devp, /* pointer to stream tail's dev */
318 int oflag, /* the user open(2) supplied flags */
319 int sflag, /* open state flag */
320 cred_t *credp) /* credentials */
321 {
322 struct pt_ttys *ptmp;
323 mblk_t *mop; /* ptr to a setopts message block */
324 struct stroptions *sop;
325 minor_t dminor = getminor(*devp);
326
327 /* Allow reopen */
328 if (rqp->q_ptr != NULL)
329 return (0);
330
331 if (sflag & MODOPEN)
332 return (ENXIO);
333
334 if (!(sflag & CLONEOPEN) && dminor != 0) {
335 /*
336 * This is a direct open to specific manager device through an
337 * artificially created entry with specific minor in
338 * /dev/directory. Such behavior is not supported.
339 */
340 return (ENXIO);
341 }
342
343 /*
344 * The manager open requires that the subsidiary be attached before it
345 * returns so that attempts to open the subsidiary will succeeed
346 */
347 if (ptms_attach_subsidiary() != 0) {
348 return (ENXIO);
349 }
350
351 mop = allocb(sizeof (struct stroptions), BPRI_MED);
352 if (mop == NULL) {
353 DDBG("ptmopen(): mop allocation failed\n", 0);
354 return (ENOMEM);
355 }
356
357 if ((ptmp = pt_ttys_alloc()) == NULL) {
358 DDBG("ptmopen(): pty allocation failed\n", 0);
359 freemsg(mop);
360 return (ENOMEM);
361 }
362
363 dminor = ptmp->pt_minor;
364
365 DDBGP("ptmopen(): allocated ptmp %p\n", (uintptr_t)ptmp);
366 DDBG("ptmopen(): allocated minor %d\n", dminor);
367
368 WR(rqp)->q_ptr = rqp->q_ptr = ptmp;
369
370 qprocson(rqp);
371
372 /* Allow subsidiary to send messages to manager */
373 PT_ENTER_WRITE(ptmp);
374 ptmp->ptm_rdq = rqp;
375 PT_EXIT_WRITE(ptmp);
376
377 /*
378 * set up hi/lo water marks on stream head read queue
379 * and add controlling tty if not set
380 */
381 mop->b_datap->db_type = M_SETOPTS;
382 mop->b_wptr += sizeof (struct stroptions);
383 sop = (struct stroptions *)mop->b_rptr;
384 if (oflag & FNOCTTY)
385 sop->so_flags = SO_HIWAT | SO_LOWAT;
386 else
387 sop->so_flags = SO_HIWAT | SO_LOWAT | SO_ISTTY;
388 sop->so_hiwat = _TTY_BUFSIZ;
389 sop->so_lowat = 256;
390 putnext(rqp, mop);
391
392 /*
393 * The input, devp, is a major device number, the output is put
394 * into the same parm as a major,minor pair.
395 */
396 *devp = makedevice(getmajor(*devp), dminor);
397
398 return (0);
399 }
400
401
402 /*
403 * Find the address to private data identifying the subsidiary's write queue.
404 * Send a hang-up message up the subsidiary's read queue to designate the
405 * manager/subsidiary pair is tearing down. Uattach the manager and subsidiary
406 * by nulling out the write queue fields in the private data structure.
407 * Finally, unlock the manager/subsidiary pair and mark the manager as closed.
408 */
409 static int
ptmclose(queue_t * rqp,int flag,cred_t * credp)410 ptmclose(queue_t *rqp, int flag, cred_t *credp)
411 {
412 struct pt_ttys *ptmp;
413 queue_t *pts_rdq;
414
415 ASSERT(rqp->q_ptr);
416
417 ptmp = (struct pt_ttys *)rqp->q_ptr;
418 PT_ENTER_READ(ptmp);
419 if (ptmp->pts_rdq) {
420 pts_rdq = ptmp->pts_rdq;
421 if (pts_rdq->q_next) {
422 DBG(("send hangup message to subsidiary\n"));
423 (void) putnextctl(pts_rdq, M_HANGUP);
424 }
425 }
426 PT_EXIT_READ(ptmp);
427 /*
428 * ptm_rdq should be cleared before call to qprocsoff() to prevent pts
429 * write procedure to attempt using ptm_rdq after qprocsoff.
430 */
431 PT_ENTER_WRITE(ptmp);
432 ptmp->ptm_rdq = NULL;
433 freemsg(ptmp->pt_nullmsg);
434 ptmp->pt_nullmsg = NULL;
435 /*
436 * qenable subsidiary side write queue so that it can flush
437 * its messages as manager's read queue is going away
438 */
439 if (ptmp->pts_rdq)
440 qenable(WR(ptmp->pts_rdq));
441 PT_EXIT_WRITE(ptmp);
442
443 qprocsoff(rqp);
444
445 /* Finish the close */
446 rqp->q_ptr = NULL;
447 WR(rqp)->q_ptr = NULL;
448
449 ptms_close(ptmp, PTMOPEN | PTLOCK);
450
451 return (0);
452 }
453
454 /*
455 * The wput procedure will only handle ioctl and flush messages.
456 */
457 static int
ptmwput(queue_t * qp,mblk_t * mp)458 ptmwput(queue_t *qp, mblk_t *mp)
459 {
460 struct pt_ttys *ptmp;
461 struct iocblk *iocp;
462
463 DBG(("entering ptmwput\n"));
464 ASSERT(qp->q_ptr);
465
466 ptmp = (struct pt_ttys *)qp->q_ptr;
467 PT_ENTER_READ(ptmp);
468
469 switch (mp->b_datap->db_type) {
470 /*
471 * If this is a write queue request, flush manager's write queue and
472 * send FLUSHR up subsidiary side. If it is a read queue request,
473 * convert to FLUSHW and putnext().
474 */
475 case M_FLUSH:
476 {
477 unsigned char flush_flg = 0;
478
479 DBG(("ptm got flush request\n"));
480 if (*mp->b_rptr & FLUSHW) {
481 DBG(("got FLUSHW, flush ptm write Q\n"));
482 if (*mp->b_rptr & FLUSHBAND) {
483 /*
484 * if it is a FLUSHBAND, do flushband.
485 */
486 flushband(qp, *(mp->b_rptr + 1),
487 FLUSHDATA);
488 } else {
489 flushq(qp, FLUSHDATA);
490 }
491 flush_flg = (*mp->b_rptr & ~FLUSHW) | FLUSHR;
492 }
493 if (*mp->b_rptr & FLUSHR) {
494 DBG(("got FLUSHR, set FLUSHW\n"));
495 flush_flg |= (*mp->b_rptr & ~FLUSHR) | FLUSHW;
496 }
497 if (flush_flg != 0 && ptmp->pts_rdq &&
498 !(ptmp->pt_state & PTLOCK)) {
499 DBG(("putnext to pts\n"));
500 *mp->b_rptr = flush_flg;
501 putnext(ptmp->pts_rdq, mp);
502 } else {
503 freemsg(mp);
504 }
505 break;
506 }
507
508 case M_IOCTL:
509 iocp = (struct iocblk *)mp->b_rptr;
510 switch (iocp->ioc_cmd) {
511 default:
512 if ((ptmp->pt_state & PTLOCK) ||
513 (ptmp->pts_rdq == NULL)) {
514 DBG(("got M_IOCTL but no subsidiary\n"));
515 miocnak(qp, mp, 0, EINVAL);
516 PT_EXIT_READ(ptmp);
517 return (0);
518 }
519 (void) putq(qp, mp);
520 break;
521 case UNLKPT:
522 mutex_enter(&ptmp->pt_lock);
523 ptmp->pt_state &= ~PTLOCK;
524 mutex_exit(&ptmp->pt_lock);
525 /*FALLTHROUGH*/
526 case ISPTM:
527 DBG(("ack the UNLKPT/ISPTM\n"));
528 miocack(qp, mp, 0, 0);
529 break;
530 case PTSSTTY:
531 mutex_enter(&ptmp->pt_lock);
532 ptmp->pt_state |= PTSTTY;
533 mutex_exit(&ptmp->pt_lock);
534 DBG(("ack PTSSTTY\n"));
535 miocack(qp, mp, 0, 0);
536 break;
537 case ZONEPT:
538 {
539 zoneid_t z;
540 int error;
541
542 if ((error = drv_priv(iocp->ioc_cr)) != 0) {
543 miocnak(qp, mp, 0, error);
544 break;
545 }
546 if ((error = miocpullup(mp, sizeof (zoneid_t))) != 0) {
547 miocnak(qp, mp, 0, error);
548 break;
549 }
550 z = *((zoneid_t *)mp->b_cont->b_rptr);
551 if (z < MIN_ZONEID || z > MAX_ZONEID) {
552 miocnak(qp, mp, 0, EINVAL);
553 break;
554 }
555
556 mutex_enter(&ptmp->pt_lock);
557 ptmp->pt_zoneid = z;
558 mutex_exit(&ptmp->pt_lock);
559 miocack(qp, mp, 0, 0);
560 break;
561 }
562 case OWNERPT:
563 {
564 pt_own_t *ptop;
565 int error;
566 zone_t *zone;
567
568 if ((error = miocpullup(mp, sizeof (pt_own_t))) != 0) {
569 miocnak(qp, mp, 0, error);
570 break;
571 }
572
573 zone = zone_find_by_id(ptmp->pt_zoneid);
574 ptop = (pt_own_t *)mp->b_cont->b_rptr;
575
576 if (!VALID_UID(ptop->pto_ruid, zone) ||
577 !VALID_GID(ptop->pto_rgid, zone)) {
578 zone_rele(zone);
579 miocnak(qp, mp, 0, EINVAL);
580 break;
581 }
582 zone_rele(zone);
583 mutex_enter(&ptmp->pt_lock);
584 ptmp->pt_ruid = ptop->pto_ruid;
585 ptmp->pt_rgid = ptop->pto_rgid;
586 mutex_exit(&ptmp->pt_lock);
587 miocack(qp, mp, 0, 0);
588 break;
589 }
590 }
591 break;
592
593 case M_READ:
594 /* Caused by ldterm - can not pass to subsidiary */
595 freemsg(mp);
596 break;
597
598 /*
599 * Send other messages to the subsidiary:
600 */
601 default:
602 if ((ptmp->pt_state & PTLOCK) || (ptmp->pts_rdq == NULL)) {
603 DBG(("got msg. but no subsidiary\n"));
604 mp = mexchange(NULL, mp, 2, M_ERROR, -1);
605 if (mp != NULL) {
606 mp->b_rptr[0] = NOERROR;
607 mp->b_rptr[1] = EINVAL;
608 qreply(qp, mp);
609 }
610 PT_EXIT_READ(ptmp);
611 return (0);
612 }
613 DBG(("put msg on manager's write queue\n"));
614 (void) putq(qp, mp);
615 break;
616 }
617 DBG(("return from ptmwput()\n"));
618 PT_EXIT_READ(ptmp);
619 return (0);
620 }
621
622
623 /*
624 * Enable the write side of the subsidiary. This triggers the subsidiary to
625 * send any messages queued on its write side to the read side of this manager.
626 */
627 static int
ptmrsrv(queue_t * qp)628 ptmrsrv(queue_t *qp)
629 {
630 struct pt_ttys *ptmp;
631
632 DBG(("entering ptmrsrv\n"));
633 ASSERT(qp->q_ptr);
634
635 ptmp = (struct pt_ttys *)qp->q_ptr;
636 PT_ENTER_READ(ptmp);
637 if (ptmp->pts_rdq) {
638 qenable(WR(ptmp->pts_rdq));
639 }
640 PT_EXIT_READ(ptmp);
641 DBG(("leaving ptmrsrv\n"));
642 return (0);
643 }
644
645
646 /*
647 * If there are messages on this queue that can be sent to subsidiary, send
648 * them via putnext(). Otherwise, if queued messages cannot be sent, leave
649 * them on this queue. If priority messages on this queue, send them to the
650 * subsidiary no matter what.
651 */
652 static int
ptmwsrv(queue_t * qp)653 ptmwsrv(queue_t *qp)
654 {
655 struct pt_ttys *ptmp;
656 mblk_t *mp;
657
658 DBG(("entering ptmwsrv\n"));
659 ASSERT(qp->q_ptr);
660
661 ptmp = (struct pt_ttys *)qp->q_ptr;
662
663 if ((mp = getq(qp)) == NULL) {
664 /* If there are no messages there's nothing to do. */
665 DBG(("leaving ptmwsrv (no messages)\n"));
666 return (0);
667 }
668
669 PT_ENTER_READ(ptmp);
670 if ((ptmp->pt_state & PTLOCK) || (ptmp->pts_rdq == NULL)) {
671 DBG(("in manager write srv proc but no subsidiary\n"));
672 /*
673 * Free messages on the write queue and send
674 * NAK for any M_IOCTL type messages to wakeup
675 * the user process waiting for ACK/NAK from
676 * the ioctl invocation
677 */
678 do {
679 if (mp->b_datap->db_type == M_IOCTL)
680 miocnak(qp, mp, 0, EINVAL);
681 else
682 freemsg(mp);
683 } while ((mp = getq(qp)) != NULL);
684 flushq(qp, FLUSHALL);
685
686 mp = mexchange(NULL, NULL, 2, M_ERROR, -1);
687 if (mp != NULL) {
688 mp->b_rptr[0] = NOERROR;
689 mp->b_rptr[1] = EINVAL;
690 qreply(qp, mp);
691 }
692 PT_EXIT_READ(ptmp);
693 return (0);
694 }
695 /*
696 * While there are messages on this write queue...
697 */
698 do {
699 /*
700 * If this is not a control message, and we cannot put messages
701 * on the subsidiary's read queue, put it back on this queue.
702 */
703 if (mp->b_datap->db_type <= QPCTL &&
704 !bcanputnext(ptmp->pts_rdq, mp->b_band)) {
705 DBG(("put msg. back on queue\n"));
706 (void) putbq(qp, mp);
707 break;
708 }
709 /*
710 * Otherwise send the message up subsidiary's stream
711 */
712 DBG(("send message to subsidiary\n"));
713 putnext(ptmp->pts_rdq, mp);
714 } while ((mp = getq(qp)) != NULL);
715 DBG(("leaving ptmwsrv\n"));
716 PT_EXIT_READ(ptmp);
717 return (0);
718 }
719