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[apple/xnu.git] / bsd / kern / sysv_msg.c
1 /*
2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * The contents of this file constitute Original Code as defined in and
7 * are subject to the Apple Public Source License Version 1.1 (the
8 * "License"). You may not use this file except in compliance with the
9 * License. Please obtain a copy of the License at
10 * http://www.apple.com/publicsource and read it before using this file.
11 *
12 * This Original Code and all software distributed under the License are
13 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
14 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17 * License for the specific language governing rights and limitations
18 * under the License.
19 *
20 * @APPLE_LICENSE_HEADER_END@
21 */
22 /*
23 * Implementation of SVID messages
24 *
25 * Author: Daniel Boulet
26 *
27 * Copyright 1993 Daniel Boulet and RTMX Inc.
28 *
29 * This system call was implemented by Daniel Boulet under contract from RTMX.
30 *
31 * Redistribution and use in source forms, with and without modification,
32 * are permitted provided that this entire comment appears intact.
33 *
34 * Redistribution in binary form may occur without any restrictions.
35 * Obviously, it would be nice if you gave credit where credit is due
36 * but requiring it would be too onerous.
37 *
38 * This software is provided ``AS IS'' without any warranties of any kind.
39 */
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/sysproto.h>
44 #include <sys/kernel.h>
45 #include <sys/proc.h>
46 #include <sys/msg.h>
47 #include <sys/sysent.h>
48
49 static void msginit __P((void *));
50 SYSINIT(sysv_msg, SI_SUB_SYSV_MSG, SI_ORDER_FIRST, msginit, NULL)
51
52 #define MSG_DEBUG
53 #undef MSG_DEBUG_OK
54
55 #ifndef _SYS_SYSPROTO_H_
56 struct msgctl_args;
57 int msgctl __P((struct proc *p, struct msgctl_args *uap));
58 struct msgget_args;
59 int msgget __P((struct proc *p, struct msgget_args *uap));
60 struct msgsnd_args;
61 int msgsnd __P((struct proc *p, struct msgsnd_args *uap));
62 struct msgrcv_args;
63 int msgrcv __P((struct proc *p, struct msgrcv_args *uap));
64 #endif
65 static void msg_freehdr __P((struct msg *msghdr));
66
67 /* XXX casting to (sy_call_t *) is bogus, as usual. */
68 static sy_call_t *msgcalls[] = {
69 (sy_call_t *)msgctl, (sy_call_t *)msgget,
70 (sy_call_t *)msgsnd, (sy_call_t *)msgrcv
71 };
72
73 static int nfree_msgmaps; /* # of free map entries */
74 static short free_msgmaps; /* head of linked list of free map entries */
75 static struct msg *free_msghdrs; /* list of free msg headers */
76 char *msgpool; /* MSGMAX byte long msg buffer pool */
77 struct msgmap *msgmaps; /* MSGSEG msgmap structures */
78 struct msg *msghdrs; /* MSGTQL msg headers */
79 struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */
80
81 void
82 msginit(dummy)
83 void *dummy;
84 {
85 register int i;
86
87 /*
88 * msginfo.msgssz should be a power of two for efficiency reasons.
89 * It is also pretty silly if msginfo.msgssz is less than 8
90 * or greater than about 256 so ...
91 */
92
93 i = 8;
94 while (i < 1024 && i != msginfo.msgssz)
95 i <<= 1;
96 if (i != msginfo.msgssz) {
97 printf("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz,
98 msginfo.msgssz);
99 panic("msginfo.msgssz not a small power of 2");
100 }
101
102 if (msginfo.msgseg > 32767) {
103 printf("msginfo.msgseg=%d\n", msginfo.msgseg);
104 panic("msginfo.msgseg > 32767");
105 }
106
107 if (msgmaps == NULL)
108 panic("msgmaps is NULL");
109
110 for (i = 0; i < msginfo.msgseg; i++) {
111 if (i > 0)
112 msgmaps[i-1].next = i;
113 msgmaps[i].next = -1; /* implies entry is available */
114 }
115 free_msgmaps = 0;
116 nfree_msgmaps = msginfo.msgseg;
117
118 if (msghdrs == NULL)
119 panic("msghdrs is NULL");
120
121 for (i = 0; i < msginfo.msgtql; i++) {
122 msghdrs[i].msg_type = 0;
123 if (i > 0)
124 msghdrs[i-1].msg_next = &msghdrs[i];
125 msghdrs[i].msg_next = NULL;
126 }
127 free_msghdrs = &msghdrs[0];
128
129 if (msqids == NULL)
130 panic("msqids is NULL");
131
132 for (i = 0; i < msginfo.msgmni; i++) {
133 msqids[i].msg_qbytes = 0; /* implies entry is available */
134 msqids[i].msg_perm.seq = 0; /* reset to a known value */
135 }
136 }
137
138 /*
139 * Entry point for all MSG calls
140 */
141 int
142 msgsys(p, uap)
143 struct proc *p;
144 /* XXX actually varargs. */
145 struct msgsys_args /* {
146 u_int which;
147 int a2;
148 int a3;
149 int a4;
150 int a5;
151 int a6;
152 } */ *uap;
153 {
154
155 if (uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0]))
156 return (EINVAL);
157 return ((*msgcalls[uap->which])(p, &uap->a2));
158 }
159
160 static void
161 msg_freehdr(msghdr)
162 struct msg *msghdr;
163 {
164 while (msghdr->msg_ts > 0) {
165 short next;
166 if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg)
167 panic("msghdr->msg_spot out of range");
168 next = msgmaps[msghdr->msg_spot].next;
169 msgmaps[msghdr->msg_spot].next = free_msgmaps;
170 free_msgmaps = msghdr->msg_spot;
171 nfree_msgmaps++;
172 msghdr->msg_spot = next;
173 if (msghdr->msg_ts >= msginfo.msgssz)
174 msghdr->msg_ts -= msginfo.msgssz;
175 else
176 msghdr->msg_ts = 0;
177 }
178 if (msghdr->msg_spot != -1)
179 panic("msghdr->msg_spot != -1");
180 msghdr->msg_next = free_msghdrs;
181 free_msghdrs = msghdr;
182 }
183
184 #ifndef _SYS_SYSPROTO_H_
185 struct msgctl_args {
186 int msqid;
187 int cmd;
188 struct msqid_ds *buf;
189 };
190 #endif
191
192 int
193 msgctl(p, uap)
194 struct proc *p;
195 register struct msgctl_args *uap;
196 {
197 int msqid = uap->msqid;
198 int cmd = uap->cmd;
199 struct msqid_ds *user_msqptr = uap->buf;
200 struct ucred *cred = p->p_ucred;
201 int rval, eval;
202 struct msqid_ds msqbuf;
203 register struct msqid_ds *msqptr;
204
205 #ifdef MSG_DEBUG_OK
206 printf("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr);
207 #endif
208
209 msqid = IPCID_TO_IX(msqid);
210
211 if (msqid < 0 || msqid >= msginfo.msgmni) {
212 #ifdef MSG_DEBUG_OK
213 printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
214 msginfo.msgmni);
215 #endif
216 return(EINVAL);
217 }
218
219 msqptr = &msqids[msqid];
220
221 if (msqptr->msg_qbytes == 0) {
222 #ifdef MSG_DEBUG_OK
223 printf("no such msqid\n");
224 #endif
225 return(EINVAL);
226 }
227 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
228 #ifdef MSG_DEBUG_OK
229 printf("wrong sequence number\n");
230 #endif
231 return(EINVAL);
232 }
233
234 eval = 0;
235 rval = 0;
236
237 switch (cmd) {
238
239 case IPC_RMID:
240 {
241 struct msg *msghdr;
242 if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M)))
243 return(eval);
244 /* Free the message headers */
245 msghdr = msqptr->msg_first;
246 while (msghdr != NULL) {
247 struct msg *msghdr_tmp;
248
249 /* Free the segments of each message */
250 msqptr->msg_cbytes -= msghdr->msg_ts;
251 msqptr->msg_qnum--;
252 msghdr_tmp = msghdr;
253 msghdr = msghdr->msg_next;
254 msg_freehdr(msghdr_tmp);
255 }
256
257 if (msqptr->msg_cbytes != 0)
258 panic("msg_cbytes is messed up");
259 if (msqptr->msg_qnum != 0)
260 panic("msg_qnum is messed up");
261
262 msqptr->msg_qbytes = 0; /* Mark it as free */
263
264 wakeup((caddr_t)msqptr);
265 }
266
267 break;
268
269 case IPC_SET:
270 if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M)))
271 return(eval);
272 if ((eval = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0)
273 return(eval);
274 if (msqbuf.msg_qbytes > msqptr->msg_qbytes) {
275 eval = suser(cred, &p->p_acflag);
276 if (eval)
277 return(eval);
278 }
279 if (msqbuf.msg_qbytes > msginfo.msgmnb) {
280 #ifdef MSG_DEBUG_OK
281 printf("can't increase msg_qbytes beyond %d (truncating)\n",
282 msginfo.msgmnb);
283 #endif
284 msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */
285 }
286 if (msqbuf.msg_qbytes == 0) {
287 #ifdef MSG_DEBUG_OK
288 printf("can't reduce msg_qbytes to 0\n");
289 #endif
290 return(EINVAL); /* non-standard errno! */
291 }
292 msqptr->msg_perm.uid = msqbuf.msg_perm.uid; /* change the owner */
293 msqptr->msg_perm.gid = msqbuf.msg_perm.gid; /* change the owner */
294 msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) |
295 (msqbuf.msg_perm.mode & 0777);
296 msqptr->msg_qbytes = msqbuf.msg_qbytes;
297 msqptr->msg_ctime = time_second;
298 break;
299
300 case IPC_STAT:
301 if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) {
302 #ifdef MSG_DEBUG_OK
303 printf("requester doesn't have read access\n");
304 #endif
305 return(eval);
306 }
307 eval = copyout((caddr_t)msqptr, user_msqptr,
308 sizeof(struct msqid_ds));
309 break;
310
311 default:
312 #ifdef MSG_DEBUG_OK
313 printf("invalid command %d\n", cmd);
314 #endif
315 return(EINVAL);
316 }
317
318 if (eval == 0)
319 p->p_retval[0] = rval;
320 return(eval);
321 }
322
323 #ifndef _SYS_SYSPROTO_H_
324 struct msgget_args {
325 key_t key;
326 int msgflg;
327 };
328 #endif
329
330 int
331 msgget(p, uap)
332 struct proc *p;
333 register struct msgget_args *uap;
334 {
335 int msqid, eval;
336 int key = uap->key;
337 int msgflg = uap->msgflg;
338 struct ucred *cred = p->p_ucred;
339 register struct msqid_ds *msqptr = NULL;
340
341 #ifdef MSG_DEBUG_OK
342 printf("msgget(0x%x, 0%o)\n", key, msgflg);
343 #endif
344
345 if (key != IPC_PRIVATE) {
346 for (msqid = 0; msqid < msginfo.msgmni; msqid++) {
347 msqptr = &msqids[msqid];
348 if (msqptr->msg_qbytes != 0 &&
349 msqptr->msg_perm.key == key)
350 break;
351 }
352 if (msqid < msginfo.msgmni) {
353 #ifdef MSG_DEBUG_OK
354 printf("found public key\n");
355 #endif
356 if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) {
357 #ifdef MSG_DEBUG_OK
358 printf("not exclusive\n");
359 #endif
360 return(EEXIST);
361 }
362 if ((eval = ipcperm(cred, &msqptr->msg_perm, msgflg & 0700 ))) {
363 #ifdef MSG_DEBUG_OK
364 printf("requester doesn't have 0%o access\n",
365 msgflg & 0700);
366 #endif
367 return(eval);
368 }
369 goto found;
370 }
371 }
372
373 #ifdef MSG_DEBUG_OK
374 printf("need to allocate the msqid_ds\n");
375 #endif
376 if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) {
377 for (msqid = 0; msqid < msginfo.msgmni; msqid++) {
378 /*
379 * Look for an unallocated and unlocked msqid_ds.
380 * msqid_ds's can be locked by msgsnd or msgrcv while
381 * they are copying the message in/out. We can't
382 * re-use the entry until they release it.
383 */
384 msqptr = &msqids[msqid];
385 if (msqptr->msg_qbytes == 0 &&
386 (msqptr->msg_perm.mode & MSG_LOCKED) == 0)
387 break;
388 }
389 if (msqid == msginfo.msgmni) {
390 #ifdef MSG_DEBUG_OK
391 printf("no more msqid_ds's available\n");
392 #endif
393 return(ENOSPC);
394 }
395 #ifdef MSG_DEBUG_OK
396 printf("msqid %d is available\n", msqid);
397 #endif
398 msqptr->msg_perm.key = key;
399 msqptr->msg_perm.cuid = cred->cr_uid;
400 msqptr->msg_perm.uid = cred->cr_uid;
401 msqptr->msg_perm.cgid = cred->cr_gid;
402 msqptr->msg_perm.gid = cred->cr_gid;
403 msqptr->msg_perm.mode = (msgflg & 0777);
404 /* Make sure that the returned msqid is unique */
405 msqptr->msg_perm.seq++;
406 msqptr->msg_first = NULL;
407 msqptr->msg_last = NULL;
408 msqptr->msg_cbytes = 0;
409 msqptr->msg_qnum = 0;
410 msqptr->msg_qbytes = msginfo.msgmnb;
411 msqptr->msg_lspid = 0;
412 msqptr->msg_lrpid = 0;
413 msqptr->msg_stime = 0;
414 msqptr->msg_rtime = 0;
415 msqptr->msg_ctime = time_second;
416 } else {
417 #ifdef MSG_DEBUG_OK
418 printf("didn't find it and wasn't asked to create it\n");
419 #endif
420 return(ENOENT);
421 }
422
423 found:
424 /* Construct the unique msqid */
425 p->p_retval[0] = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm);
426 return(0);
427 }
428
429 #ifndef _SYS_SYSPROTO_H_
430 struct msgsnd_args {
431 int msqid;
432 void *msgp;
433 size_t msgsz;
434 int msgflg;
435 };
436 #endif
437
438 int
439 msgsnd(p, uap)
440 struct proc *p;
441 register struct msgsnd_args *uap;
442 {
443 int msqid = uap->msqid;
444 void *user_msgp = uap->msgp;
445 size_t msgsz = uap->msgsz;
446 int msgflg = uap->msgflg;
447 int segs_needed, eval;
448 struct ucred *cred = p->p_ucred;
449 register struct msqid_ds *msqptr;
450 register struct msg *msghdr;
451 short next;
452
453 #ifdef MSG_DEBUG_OK
454 printf("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz,
455 msgflg);
456 #endif
457
458 msqid = IPCID_TO_IX(msqid);
459
460 if (msqid < 0 || msqid >= msginfo.msgmni) {
461 #ifdef MSG_DEBUG_OK
462 printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
463 msginfo.msgmni);
464 #endif
465 return(EINVAL);
466 }
467
468 msqptr = &msqids[msqid];
469 if (msqptr->msg_qbytes == 0) {
470 #ifdef MSG_DEBUG_OK
471 printf("no such message queue id\n");
472 #endif
473 return(EINVAL);
474 }
475 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
476 #ifdef MSG_DEBUG_OK
477 printf("wrong sequence number\n");
478 #endif
479 return(EINVAL);
480 }
481
482 if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_W))) {
483 #ifdef MSG_DEBUG_OK
484 printf("requester doesn't have write access\n");
485 #endif
486 return(eval);
487 }
488
489 segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz;
490 #ifdef MSG_DEBUG_OK
491 printf("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz,
492 segs_needed);
493 #endif
494 for (;;) {
495 int need_more_resources = 0;
496
497 /*
498 * check msgsz
499 * (inside this loop in case msg_qbytes changes while we sleep)
500 */
501
502 if (msgsz > msqptr->msg_qbytes) {
503 #ifdef MSG_DEBUG_OK
504 printf("msgsz > msqptr->msg_qbytes\n");
505 #endif
506 return(EINVAL);
507 }
508
509 if (msqptr->msg_perm.mode & MSG_LOCKED) {
510 #ifdef MSG_DEBUG_OK
511 printf("msqid is locked\n");
512 #endif
513 need_more_resources = 1;
514 }
515 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) {
516 #ifdef MSG_DEBUG_OK
517 printf("msgsz + msg_cbytes > msg_qbytes\n");
518 #endif
519 need_more_resources = 1;
520 }
521 if (segs_needed > nfree_msgmaps) {
522 #ifdef MSG_DEBUG_OK
523 printf("segs_needed > nfree_msgmaps\n");
524 #endif
525 need_more_resources = 1;
526 }
527 if (free_msghdrs == NULL) {
528 #ifdef MSG_DEBUG_OK
529 printf("no more msghdrs\n");
530 #endif
531 need_more_resources = 1;
532 }
533
534 if (need_more_resources) {
535 int we_own_it;
536
537 if ((msgflg & IPC_NOWAIT) != 0) {
538 #ifdef MSG_DEBUG_OK
539 printf("need more resources but caller doesn't want to wait\n");
540 #endif
541 return(EAGAIN);
542 }
543
544 if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) {
545 #ifdef MSG_DEBUG_OK
546 printf("we don't own the msqid_ds\n");
547 #endif
548 we_own_it = 0;
549 } else {
550 /* Force later arrivals to wait for our
551 request */
552 #ifdef MSG_DEBUG_OK
553 printf("we own the msqid_ds\n");
554 #endif
555 msqptr->msg_perm.mode |= MSG_LOCKED;
556 we_own_it = 1;
557 }
558 #ifdef MSG_DEBUG_OK
559 printf("goodnight\n");
560 #endif
561 eval = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH,
562 "msgwait", 0);
563 #ifdef MSG_DEBUG_OK
564 printf("good morning, eval=%d\n", eval);
565 #endif
566 if (we_own_it)
567 msqptr->msg_perm.mode &= ~MSG_LOCKED;
568 if (eval != 0) {
569 #ifdef MSG_DEBUG_OK
570 printf("msgsnd: interrupted system call\n");
571 #endif
572 return(EINTR);
573 }
574
575 /*
576 * Make sure that the msq queue still exists
577 */
578
579 if (msqptr->msg_qbytes == 0) {
580 #ifdef MSG_DEBUG_OK
581 printf("msqid deleted\n");
582 #endif
583 /* The SVID says to return EIDRM. */
584 #ifdef EIDRM
585 return(EIDRM);
586 #else
587 /* Unfortunately, BSD doesn't define that code
588 yet! */
589 return(EINVAL);
590 #endif
591 }
592
593 } else {
594 #ifdef MSG_DEBUG_OK
595 printf("got all the resources that we need\n");
596 #endif
597 break;
598 }
599 }
600
601 /*
602 * We have the resources that we need.
603 * Make sure!
604 */
605
606 if (msqptr->msg_perm.mode & MSG_LOCKED)
607 panic("msg_perm.mode & MSG_LOCKED");
608 if (segs_needed > nfree_msgmaps)
609 panic("segs_needed > nfree_msgmaps");
610 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes)
611 panic("msgsz + msg_cbytes > msg_qbytes");
612 if (free_msghdrs == NULL)
613 panic("no more msghdrs");
614
615 /*
616 * Re-lock the msqid_ds in case we page-fault when copying in the
617 * message
618 */
619
620 if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0)
621 panic("msqid_ds is already locked");
622 msqptr->msg_perm.mode |= MSG_LOCKED;
623
624 /*
625 * Allocate a message header
626 */
627
628 msghdr = free_msghdrs;
629 free_msghdrs = msghdr->msg_next;
630 msghdr->msg_spot = -1;
631 msghdr->msg_ts = msgsz;
632
633 /*
634 * Allocate space for the message
635 */
636
637 while (segs_needed > 0) {
638 if (nfree_msgmaps <= 0)
639 panic("not enough msgmaps");
640 if (free_msgmaps == -1)
641 panic("nil free_msgmaps");
642 next = free_msgmaps;
643 if (next <= -1)
644 panic("next too low #1");
645 if (next >= msginfo.msgseg)
646 panic("next out of range #1");
647 #ifdef MSG_DEBUG_OK
648 printf("allocating segment %d to message\n", next);
649 #endif
650 free_msgmaps = msgmaps[next].next;
651 nfree_msgmaps--;
652 msgmaps[next].next = msghdr->msg_spot;
653 msghdr->msg_spot = next;
654 segs_needed--;
655 }
656
657 /*
658 * Copy in the message type
659 */
660
661 if ((eval = copyin(user_msgp, &msghdr->msg_type,
662 sizeof(msghdr->msg_type))) != 0) {
663 #ifdef MSG_DEBUG_OK
664 printf("error %d copying the message type\n", eval);
665 #endif
666 msg_freehdr(msghdr);
667 msqptr->msg_perm.mode &= ~MSG_LOCKED;
668 wakeup((caddr_t)msqptr);
669 return(eval);
670 }
671 user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type);
672
673 /*
674 * Validate the message type
675 */
676
677 if (msghdr->msg_type < 1) {
678 msg_freehdr(msghdr);
679 msqptr->msg_perm.mode &= ~MSG_LOCKED;
680 wakeup((caddr_t)msqptr);
681 #ifdef MSG_DEBUG_OK
682 printf("mtype (%d) < 1\n", msghdr->msg_type);
683 #endif
684 return(EINVAL);
685 }
686
687 /*
688 * Copy in the message body
689 */
690
691 next = msghdr->msg_spot;
692 while (msgsz > 0) {
693 size_t tlen;
694 if (msgsz > msginfo.msgssz)
695 tlen = msginfo.msgssz;
696 else
697 tlen = msgsz;
698 if (next <= -1)
699 panic("next too low #2");
700 if (next >= msginfo.msgseg)
701 panic("next out of range #2");
702 if ((eval = copyin(user_msgp, &msgpool[next * msginfo.msgssz],
703 tlen)) != 0) {
704 #ifdef MSG_DEBUG_OK
705 printf("error %d copying in message segment\n", eval);
706 #endif
707 msg_freehdr(msghdr);
708 msqptr->msg_perm.mode &= ~MSG_LOCKED;
709 wakeup((caddr_t)msqptr);
710 return(eval);
711 }
712 msgsz -= tlen;
713 user_msgp = (char *)user_msgp + tlen;
714 next = msgmaps[next].next;
715 }
716 if (next != -1)
717 panic("didn't use all the msg segments");
718
719 /*
720 * We've got the message. Unlock the msqid_ds.
721 */
722
723 msqptr->msg_perm.mode &= ~MSG_LOCKED;
724
725 /*
726 * Make sure that the msqid_ds is still allocated.
727 */
728
729 if (msqptr->msg_qbytes == 0) {
730 msg_freehdr(msghdr);
731 wakeup((caddr_t)msqptr);
732 /* The SVID says to return EIDRM. */
733 #ifdef EIDRM
734 return(EIDRM);
735 #else
736 /* Unfortunately, BSD doesn't define that code yet! */
737 return(EINVAL);
738 #endif
739 }
740
741 /*
742 * Put the message into the queue
743 */
744
745 if (msqptr->msg_first == NULL) {
746 msqptr->msg_first = msghdr;
747 msqptr->msg_last = msghdr;
748 } else {
749 msqptr->msg_last->msg_next = msghdr;
750 msqptr->msg_last = msghdr;
751 }
752 msqptr->msg_last->msg_next = NULL;
753
754 msqptr->msg_cbytes += msghdr->msg_ts;
755 msqptr->msg_qnum++;
756 msqptr->msg_lspid = p->p_pid;
757 msqptr->msg_stime = time_second;
758
759 wakeup((caddr_t)msqptr);
760 p->p_retval[0] = 0;
761 return(0);
762 }
763
764 #ifndef _SYS_SYSPROTO_H_
765 struct msgrcv_args {
766 int msqid;
767 void *msgp;
768 size_t msgsz;
769 long msgtyp;
770 int msgflg;
771 };
772 #endif
773
774 int
775 msgrcv(p, uap)
776 struct proc *p;
777 register struct msgrcv_args *uap;
778 {
779 int msqid = uap->msqid;
780 void *user_msgp = uap->msgp;
781 size_t msgsz = uap->msgsz;
782 long msgtyp = uap->msgtyp;
783 int msgflg = uap->msgflg;
784 size_t len;
785 struct ucred *cred = p->p_ucred;
786 register struct msqid_ds *msqptr;
787 register struct msg *msghdr;
788 int eval;
789 short next;
790
791 #ifdef MSG_DEBUG_OK
792 printf("call to msgrcv(%d, 0x%x, %d, %ld, %d)\n", msqid, user_msgp,
793 msgsz, msgtyp, msgflg);
794 #endif
795
796 msqid = IPCID_TO_IX(msqid);
797
798 if (msqid < 0 || msqid >= msginfo.msgmni) {
799 #ifdef MSG_DEBUG_OK
800 printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
801 msginfo.msgmni);
802 #endif
803 return(EINVAL);
804 }
805
806 msqptr = &msqids[msqid];
807 if (msqptr->msg_qbytes == 0) {
808 #ifdef MSG_DEBUG_OK
809 printf("no such message queue id\n");
810 #endif
811 return(EINVAL);
812 }
813 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
814 #ifdef MSG_DEBUG_OK
815 printf("wrong sequence number\n");
816 #endif
817 return(EINVAL);
818 }
819
820 if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) {
821 #ifdef MSG_DEBUG_OK
822 printf("requester doesn't have read access\n");
823 #endif
824 return(eval);
825 }
826
827 msghdr = NULL;
828 while (msghdr == NULL) {
829 if (msgtyp == 0) {
830 msghdr = msqptr->msg_first;
831 if (msghdr != NULL) {
832 if (msgsz < msghdr->msg_ts &&
833 (msgflg & MSG_NOERROR) == 0) {
834 #ifdef MSG_DEBUG_OK
835 printf("first message on the queue is too big (want %d, got %d)\n",
836 msgsz, msghdr->msg_ts);
837 #endif
838 return(E2BIG);
839 }
840 if (msqptr->msg_first == msqptr->msg_last) {
841 msqptr->msg_first = NULL;
842 msqptr->msg_last = NULL;
843 } else {
844 msqptr->msg_first = msghdr->msg_next;
845 if (msqptr->msg_first == NULL)
846 panic("msg_first/last messed up #1");
847 }
848 }
849 } else {
850 struct msg *previous;
851 struct msg **prev;
852
853 previous = NULL;
854 prev = &(msqptr->msg_first);
855 while ((msghdr = *prev) != NULL) {
856 /*
857 * Is this message's type an exact match or is
858 * this message's type less than or equal to
859 * the absolute value of a negative msgtyp?
860 * Note that the second half of this test can
861 * NEVER be true if msgtyp is positive since
862 * msg_type is always positive!
863 */
864
865 if (msgtyp == msghdr->msg_type ||
866 msghdr->msg_type <= -msgtyp) {
867 #ifdef MSG_DEBUG_OK
868 printf("found message type %d, requested %d\n",
869 msghdr->msg_type, msgtyp);
870 #endif
871 if (msgsz < msghdr->msg_ts &&
872 (msgflg & MSG_NOERROR) == 0) {
873 #ifdef MSG_DEBUG_OK
874 printf("requested message on the queue is too big (want %d, got %d)\n",
875 msgsz, msghdr->msg_ts);
876 #endif
877 return(E2BIG);
878 }
879 *prev = msghdr->msg_next;
880 if (msghdr == msqptr->msg_last) {
881 if (previous == NULL) {
882 if (prev !=
883 &msqptr->msg_first)
884 panic("msg_first/last messed up #2");
885 msqptr->msg_first =
886 NULL;
887 msqptr->msg_last =
888 NULL;
889 } else {
890 if (prev ==
891 &msqptr->msg_first)
892 panic("msg_first/last messed up #3");
893 msqptr->msg_last =
894 previous;
895 }
896 }
897 break;
898 }
899 previous = msghdr;
900 prev = &(msghdr->msg_next);
901 }
902 }
903
904 /*
905 * We've either extracted the msghdr for the appropriate
906 * message or there isn't one.
907 * If there is one then bail out of this loop.
908 */
909
910 if (msghdr != NULL)
911 break;
912
913 /*
914 * Hmph! No message found. Does the user want to wait?
915 */
916
917 if ((msgflg & IPC_NOWAIT) != 0) {
918 #ifdef MSG_DEBUG_OK
919 printf("no appropriate message found (msgtyp=%d)\n",
920 msgtyp);
921 #endif
922 /* The SVID says to return ENOMSG. */
923 #ifdef ENOMSG
924 return(ENOMSG);
925 #else
926 /* Unfortunately, BSD doesn't define that code yet! */
927 return(EAGAIN);
928 #endif
929 }
930
931 /*
932 * Wait for something to happen
933 */
934
935 #ifdef MSG_DEBUG_OK
936 printf("msgrcv: goodnight\n");
937 #endif
938 eval = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH, "msgwait",
939 0);
940 #ifdef MSG_DEBUG_OK
941 printf("msgrcv: good morning (eval=%d)\n", eval);
942 #endif
943
944 if (eval != 0) {
945 #ifdef MSG_DEBUG_OK
946 printf("msgsnd: interrupted system call\n");
947 #endif
948 return(EINTR);
949 }
950
951 /*
952 * Make sure that the msq queue still exists
953 */
954
955 if (msqptr->msg_qbytes == 0 ||
956 msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
957 #ifdef MSG_DEBUG_OK
958 printf("msqid deleted\n");
959 #endif
960 /* The SVID says to return EIDRM. */
961 #ifdef EIDRM
962 return(EIDRM);
963 #else
964 /* Unfortunately, BSD doesn't define that code yet! */
965 return(EINVAL);
966 #endif
967 }
968 }
969
970 /*
971 * Return the message to the user.
972 *
973 * First, do the bookkeeping (before we risk being interrupted).
974 */
975
976 msqptr->msg_cbytes -= msghdr->msg_ts;
977 msqptr->msg_qnum--;
978 msqptr->msg_lrpid = p->p_pid;
979 msqptr->msg_rtime = time_second;
980
981 /*
982 * Make msgsz the actual amount that we'll be returning.
983 * Note that this effectively truncates the message if it is too long
984 * (since msgsz is never increased).
985 */
986
987 #ifdef MSG_DEBUG_OK
988 printf("found a message, msgsz=%d, msg_ts=%d\n", msgsz,
989 msghdr->msg_ts);
990 #endif
991 if (msgsz > msghdr->msg_ts)
992 msgsz = msghdr->msg_ts;
993
994 /*
995 * Return the type to the user.
996 */
997
998 eval = copyout((caddr_t)&(msghdr->msg_type), user_msgp,
999 sizeof(msghdr->msg_type));
1000 if (eval != 0) {
1001 #ifdef MSG_DEBUG_OK
1002 printf("error (%d) copying out message type\n", eval);
1003 #endif
1004 msg_freehdr(msghdr);
1005 wakeup((caddr_t)msqptr);
1006 return(eval);
1007 }
1008 user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type);
1009
1010 /*
1011 * Return the segments to the user
1012 */
1013
1014 next = msghdr->msg_spot;
1015 for (len = 0; len < msgsz; len += msginfo.msgssz) {
1016 size_t tlen;
1017
1018 if (msgsz > msginfo.msgssz)
1019 tlen = msginfo.msgssz;
1020 else
1021 tlen = msgsz;
1022 if (next <= -1)
1023 panic("next too low #3");
1024 if (next >= msginfo.msgseg)
1025 panic("next out of range #3");
1026 eval = copyout((caddr_t)&msgpool[next * msginfo.msgssz],
1027 user_msgp, tlen);
1028 if (eval != 0) {
1029 #ifdef MSG_DEBUG_OK
1030 printf("error (%d) copying out message segment\n",
1031 eval);
1032 #endif
1033 msg_freehdr(msghdr);
1034 wakeup((caddr_t)msqptr);
1035 return(eval);
1036 }
1037 user_msgp = (char *)user_msgp + tlen;
1038 next = msgmaps[next].next;
1039 }
1040
1041 /*
1042 * Done, return the actual number of bytes copied out.
1043 */
1044
1045 msg_freehdr(msghdr);
1046 wakeup((caddr_t)msqptr);
1047 p->p_retval[0] = msgsz;
1048 return(0);
1049 }
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