Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_msg.c
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1 /* $FreeBSD: src/sys/kern/sysv_msg.c,v 1.23.2.5 2002/12/31 08:54:53 maxim Exp $ */ 2 3 /* 4 * Implementation of SVID messages 5 * 6 * Author: Daniel Boulet 7 * 8 * Copyright 1993 Daniel Boulet and RTMX Inc. 9 * 10 * This system call was implemented by Daniel Boulet under contract from RTMX. 11 * 12 * Redistribution and use in source forms, with and without modification, 13 * are permitted provided that this entire comment appears intact. 14 * 15 * Redistribution in binary form may occur without any restrictions. 16 * Obviously, it would be nice if you gave credit where credit is due 17 * but requiring it would be too onerous. 18 * 19 * This software is provided ``AS IS'' without any warranties of any kind. 20 */ 21 22 #include "opt_sysvipc.h" 23 24 #include <sys/param.h> 25 #include <sys/systm.h> 26 #include <sys/sysproto.h> 27 #include <sys/kernel.h> 28 #include <sys/proc.h> 29 #include <sys/priv.h> 30 #include <sys/msg.h> 31 #include <sys/sysent.h> 32 #include <sys/sysctl.h> 33 #include <sys/malloc.h> 34 #include <sys/jail.h> 35 36 #include <sys/mplock2.h> 37 38 static MALLOC_DEFINE(M_MSG, "msg", "SVID compatible message queues"); 39 40 static void msginit (void *); 41 42 #define MSG_DEBUG 43 #undef MSG_DEBUG_OK 44 45 static void msg_freehdr (struct msg *msghdr); 46 47 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 48 static sy_call_t *msgcalls[] = { 49 (sy_call_t *)sys_msgctl, (sy_call_t *)sys_msgget, 50 (sy_call_t *)sys_msgsnd, (sy_call_t *)sys_msgrcv 51 }; 52 53 struct msg { 54 struct msg *msg_next; /* next msg in the chain */ 55 long msg_type; /* type of this message */ 56 /* >0 -> type of this message */ 57 /* 0 -> free header */ 58 u_short msg_ts; /* size of this message */ 59 short msg_spot; /* location of start of msg in buffer */ 60 }; 61 62 63 #ifndef MSGSSZ 64 #define MSGSSZ 8 /* Each segment must be 2^N long */ 65 #endif 66 #ifndef MSGSEG 67 #define MSGSEG 2048 /* must be less than 32767 */ 68 #endif 69 #define MSGMAX (MSGSSZ*MSGSEG) 70 #ifndef MSGMNB 71 #define MSGMNB 2048 /* max # of bytes in a queue */ 72 #endif 73 #ifndef MSGMNI 74 #define MSGMNI 40 75 #endif 76 #ifndef MSGTQL 77 #define MSGTQL 40 78 #endif 79 80 /* 81 * Based on the configuration parameters described in an SVR2 (yes, two) 82 * config(1m) man page. 83 * 84 * Each message is broken up and stored in segments that are msgssz bytes 85 * long. For efficiency reasons, this should be a power of two. Also, 86 * it doesn't make sense if it is less than 8 or greater than about 256. 87 * Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of 88 * two between 8 and 1024 inclusive (and panic's if it isn't). 89 */ 90 struct msginfo msginfo = { 91 MSGMAX, /* max chars in a message */ 92 MSGMNI, /* # of message queue identifiers */ 93 MSGMNB, /* max chars in a queue */ 94 MSGTQL, /* max messages in system */ 95 MSGSSZ, /* size of a message segment */ 96 /* (must be small power of 2 greater than 4) */ 97 MSGSEG /* number of message segments */ 98 }; 99 100 /* 101 * macros to convert between msqid_ds's and msqid's. 102 * (specific to this implementation) 103 */ 104 #define MSQID(ix,ds) ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000)) 105 #define MSQID_IX(id) ((id) & 0xffff) 106 #define MSQID_SEQ(id) (((id) >> 16) & 0xffff) 107 108 /* 109 * The rest of this file is specific to this particular implementation. 110 */ 111 112 struct msgmap { 113 short next; /* next segment in buffer */ 114 /* -1 -> available */ 115 /* 0..(MSGSEG-1) -> index of next segment */ 116 }; 117 118 #define MSG_LOCKED 01000 /* Is this msqid_ds locked? */ 119 120 static int nfree_msgmaps; /* # of free map entries */ 121 static short free_msgmaps; /* head of linked list of free map entries */ 122 static struct msg *free_msghdrs;/* list of free msg headers */ 123 static char *msgpool; /* MSGMAX byte long msg buffer pool */ 124 static struct msgmap *msgmaps; /* MSGSEG msgmap structures */ 125 static struct msg *msghdrs; /* MSGTQL msg headers */ 126 static struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */ 127 128 static void 129 msginit(void *dummy) 130 { 131 int i; 132 133 msginfo.msgmax = msginfo.msgseg * msginfo.msgssz; 134 msgpool = kmalloc(msginfo.msgmax, M_MSG, M_WAITOK); 135 msgmaps = kmalloc(sizeof(struct msgmap) * msginfo.msgseg, M_MSG, M_WAITOK); 136 msghdrs = kmalloc(sizeof(struct msg) * msginfo.msgtql, M_MSG, M_WAITOK); 137 msqids = kmalloc(sizeof(struct msqid_ds) * msginfo.msgmni, M_MSG, M_WAITOK); 138 139 /* 140 * msginfo.msgssz should be a power of two for efficiency reasons. 141 * It is also pretty silly if msginfo.msgssz is less than 8 142 * or greater than about 256 so ... 143 */ 144 145 i = 8; 146 while (i < 1024 && i != msginfo.msgssz) 147 i <<= 1; 148 if (i != msginfo.msgssz) { 149 kprintf("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz, 150 msginfo.msgssz); 151 panic("msginfo.msgssz not a small power of 2"); 152 } 153 154 if (msginfo.msgseg > 32767) { 155 kprintf("msginfo.msgseg=%d\n", msginfo.msgseg); 156 panic("msginfo.msgseg > 32767"); 157 } 158 159 for (i = 0; i < msginfo.msgseg; i++) { 160 if (i > 0) 161 msgmaps[i-1].next = i; 162 msgmaps[i].next = -1; /* implies entry is available */ 163 } 164 free_msgmaps = 0; 165 nfree_msgmaps = msginfo.msgseg; 166 167 for (i = 0; i < msginfo.msgtql; i++) { 168 msghdrs[i].msg_type = 0; 169 if (i > 0) 170 msghdrs[i-1].msg_next = &msghdrs[i]; 171 msghdrs[i].msg_next = NULL; 172 } 173 free_msghdrs = &msghdrs[0]; 174 175 for (i = 0; i < msginfo.msgmni; i++) { 176 msqids[i].msg_qbytes = 0; /* implies entry is available */ 177 msqids[i].msg_perm.seq = 0; /* reset to a known value */ 178 msqids[i].msg_perm.mode = 0; 179 } 180 } 181 SYSINIT(sysv_msg, SI_SUB_SYSV_MSG, SI_ORDER_FIRST, msginit, NULL) 182 183 /* 184 * Entry point for all MSG calls 185 * 186 * msgsys_args(int which, int a2, ...) (VARARGS) 187 * 188 * MPALMOSTSAFE 189 */ 190 int 191 sys_msgsys(struct msgsys_args *uap) 192 { 193 struct thread *td = curthread; 194 unsigned int which = (unsigned int)uap->which; 195 int error; 196 197 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 198 return (ENOSYS); 199 200 if (which >= NELEM(msgcalls)) 201 return (EINVAL); 202 bcopy(&uap->a2, &uap->which, 203 sizeof(struct msgsys_args) - offsetof(struct msgsys_args, a2)); 204 get_mplock(); 205 error = (*msgcalls[which])(uap); 206 rel_mplock(); 207 return (error); 208 } 209 210 static void 211 msg_freehdr(struct msg *msghdr) 212 { 213 while (msghdr->msg_ts > 0) { 214 short next; 215 if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg) 216 panic("msghdr->msg_spot out of range"); 217 next = msgmaps[msghdr->msg_spot].next; 218 msgmaps[msghdr->msg_spot].next = free_msgmaps; 219 free_msgmaps = msghdr->msg_spot; 220 nfree_msgmaps++; 221 msghdr->msg_spot = next; 222 if (msghdr->msg_ts >= msginfo.msgssz) 223 msghdr->msg_ts -= msginfo.msgssz; 224 else 225 msghdr->msg_ts = 0; 226 } 227 if (msghdr->msg_spot != -1) 228 panic("msghdr->msg_spot != -1"); 229 msghdr->msg_next = free_msghdrs; 230 free_msghdrs = msghdr; 231 } 232 233 /* 234 * MPALMOSTSAFE 235 */ 236 int 237 sys_msgctl(struct msgctl_args *uap) 238 { 239 struct thread *td = curthread; 240 struct proc *p = td->td_proc; 241 int msqid = uap->msqid; 242 int cmd = uap->cmd; 243 struct msqid_ds *user_msqptr = uap->buf; 244 int rval, eval; 245 struct msqid_ds msqbuf; 246 struct msqid_ds *msqptr; 247 248 #ifdef MSG_DEBUG_OK 249 kprintf("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr); 250 #endif 251 252 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 253 return (ENOSYS); 254 255 get_mplock(); 256 msqid = IPCID_TO_IX(msqid); 257 258 if (msqid < 0 || msqid >= msginfo.msgmni) { 259 #ifdef MSG_DEBUG_OK 260 kprintf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, 261 msginfo.msgmni); 262 #endif 263 eval = EINVAL; 264 goto done; 265 } 266 267 msqptr = &msqids[msqid]; 268 269 if (msqptr->msg_qbytes == 0) { 270 #ifdef MSG_DEBUG_OK 271 kprintf("no such msqid\n"); 272 #endif 273 eval = EINVAL; 274 goto done; 275 } 276 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 277 #ifdef MSG_DEBUG_OK 278 kprintf("wrong sequence number\n"); 279 #endif 280 eval = EINVAL; 281 goto done; 282 } 283 284 rval = 0; 285 286 switch (cmd) { 287 case IPC_RMID: 288 { 289 struct msg *msghdr; 290 if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_M)) != 0) 291 break; 292 /* Free the message headers */ 293 msghdr = msqptr->msg_first; 294 while (msghdr != NULL) { 295 struct msg *msghdr_tmp; 296 297 /* Free the segments of each message */ 298 msqptr->msg_cbytes -= msghdr->msg_ts; 299 msqptr->msg_qnum--; 300 msghdr_tmp = msghdr; 301 msghdr = msghdr->msg_next; 302 msg_freehdr(msghdr_tmp); 303 } 304 305 if (msqptr->msg_cbytes != 0) 306 panic("msg_cbytes is screwed up"); 307 if (msqptr->msg_qnum != 0) 308 panic("msg_qnum is screwed up"); 309 310 msqptr->msg_qbytes = 0; /* Mark it as free */ 311 312 wakeup((caddr_t)msqptr); 313 } 314 315 break; 316 317 case IPC_SET: 318 if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_M)) != 0) 319 break; 320 if ((eval = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0) 321 break; 322 if (msqbuf.msg_qbytes > msqptr->msg_qbytes) { 323 eval = priv_check(td, PRIV_ROOT); 324 if (eval) 325 break; 326 } 327 if (msqbuf.msg_qbytes > msginfo.msgmnb) { 328 #ifdef MSG_DEBUG_OK 329 kprintf("can't increase msg_qbytes beyond %d (truncating)\n", 330 msginfo.msgmnb); 331 #endif 332 msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */ 333 } 334 if (msqbuf.msg_qbytes == 0) { 335 #ifdef MSG_DEBUG_OK 336 kprintf("can't reduce msg_qbytes to 0\n"); 337 #endif 338 eval = EINVAL; /* non-standard errno! */ 339 break; 340 } 341 msqptr->msg_perm.uid = msqbuf.msg_perm.uid; /* change the owner */ 342 msqptr->msg_perm.gid = msqbuf.msg_perm.gid; /* change the owner */ 343 msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) | 344 (msqbuf.msg_perm.mode & 0777); 345 msqptr->msg_qbytes = msqbuf.msg_qbytes; 346 msqptr->msg_ctime = time_second; 347 break; 348 349 case IPC_STAT: 350 if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_R))) { 351 #ifdef MSG_DEBUG_OK 352 kprintf("requester doesn't have read access\n"); 353 #endif 354 eval = EINVAL; 355 break; 356 } 357 eval = copyout(msqptr, user_msqptr, sizeof(struct msqid_ds)); 358 break; 359 360 default: 361 #ifdef MSG_DEBUG_OK 362 kprintf("invalid command %d\n", cmd); 363 #endif 364 eval = EINVAL; 365 break; 366 } 367 done: 368 rel_mplock(); 369 if (eval == 0) 370 uap->sysmsg_result = rval; 371 return(eval); 372 } 373 374 /* 375 * MPALMOSTSAFE 376 */ 377 int 378 sys_msgget(struct msgget_args *uap) 379 { 380 struct thread *td = curthread; 381 int msqid, eval; 382 int key = uap->key; 383 int msgflg = uap->msgflg; 384 struct ucred *cred = td->td_ucred; 385 struct msqid_ds *msqptr = NULL; 386 387 #ifdef MSG_DEBUG_OK 388 kprintf("msgget(0x%x, 0%o)\n", key, msgflg); 389 #endif 390 if (!jail_sysvipc_allowed && cred->cr_prison != NULL) 391 return (ENOSYS); 392 393 eval = 0; 394 get_mplock(); 395 396 if (key != IPC_PRIVATE) { 397 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 398 msqptr = &msqids[msqid]; 399 if (msqptr->msg_qbytes != 0 && 400 msqptr->msg_perm.key == key) 401 break; 402 } 403 if (msqid < msginfo.msgmni) { 404 #ifdef MSG_DEBUG_OK 405 kprintf("found public key\n"); 406 #endif 407 if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) { 408 #ifdef MSG_DEBUG_OK 409 kprintf("not exclusive\n"); 410 #endif 411 eval = EEXIST; 412 goto done; 413 } 414 if ((eval = ipcperm(td->td_proc, &msqptr->msg_perm, msgflg & 0700 ))) { 415 #ifdef MSG_DEBUG_OK 416 kprintf("requester doesn't have 0%o access\n", 417 msgflg & 0700); 418 #endif 419 goto done; 420 } 421 goto done; 422 } 423 } 424 425 #ifdef MSG_DEBUG_OK 426 kprintf("need to allocate the msqid_ds\n"); 427 #endif 428 if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) { 429 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 430 /* 431 * Look for an unallocated and unlocked msqid_ds. 432 * msqid_ds's can be locked by msgsnd or msgrcv while 433 * they are copying the message in/out. We can't 434 * re-use the entry until they release it. 435 */ 436 msqptr = &msqids[msqid]; 437 if (msqptr->msg_qbytes == 0 && 438 (msqptr->msg_perm.mode & MSG_LOCKED) == 0) 439 break; 440 } 441 if (msqid == msginfo.msgmni) { 442 #ifdef MSG_DEBUG_OK 443 kprintf("no more msqid_ds's available\n"); 444 #endif 445 eval = ENOSPC; 446 goto done; 447 } 448 #ifdef MSG_DEBUG_OK 449 kprintf("msqid %d is available\n", msqid); 450 #endif 451 msqptr->msg_perm.key = key; 452 msqptr->msg_perm.cuid = cred->cr_uid; 453 msqptr->msg_perm.uid = cred->cr_uid; 454 msqptr->msg_perm.cgid = cred->cr_gid; 455 msqptr->msg_perm.gid = cred->cr_gid; 456 msqptr->msg_perm.mode = (msgflg & 0777); 457 /* Make sure that the returned msqid is unique */ 458 msqptr->msg_perm.seq = (msqptr->msg_perm.seq + 1) & 0x7fff; 459 msqptr->msg_first = NULL; 460 msqptr->msg_last = NULL; 461 msqptr->msg_cbytes = 0; 462 msqptr->msg_qnum = 0; 463 msqptr->msg_qbytes = msginfo.msgmnb; 464 msqptr->msg_lspid = 0; 465 msqptr->msg_lrpid = 0; 466 msqptr->msg_stime = 0; 467 msqptr->msg_rtime = 0; 468 msqptr->msg_ctime = time_second; 469 } else { 470 #ifdef MSG_DEBUG_OK 471 kprintf("didn't find it and wasn't asked to create it\n"); 472 #endif 473 eval = ENOENT; 474 } 475 476 done: 477 rel_mplock(); 478 /* Construct the unique msqid */ 479 if (eval == 0) 480 uap->sysmsg_result = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm); 481 return(eval); 482 } 483 484 /* 485 * MPALMOSTSAFE 486 */ 487 int 488 sys_msgsnd(struct msgsnd_args *uap) 489 { 490 struct thread *td = curthread; 491 int msqid = uap->msqid; 492 void *user_msgp = uap->msgp; 493 size_t msgsz = uap->msgsz; 494 int msgflg = uap->msgflg; 495 int segs_needed, eval; 496 struct msqid_ds *msqptr; 497 struct msg *msghdr; 498 short next; 499 500 #ifdef MSG_DEBUG_OK 501 kprintf("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz, 502 msgflg); 503 #endif 504 505 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 506 return (ENOSYS); 507 508 get_mplock(); 509 msqid = IPCID_TO_IX(msqid); 510 511 if (msqid < 0 || msqid >= msginfo.msgmni) { 512 #ifdef MSG_DEBUG_OK 513 kprintf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, 514 msginfo.msgmni); 515 #endif 516 eval = EINVAL; 517 goto done; 518 } 519 520 msqptr = &msqids[msqid]; 521 if (msqptr->msg_qbytes == 0) { 522 #ifdef MSG_DEBUG_OK 523 kprintf("no such message queue id\n"); 524 #endif 525 eval = EINVAL; 526 goto done; 527 } 528 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 529 #ifdef MSG_DEBUG_OK 530 kprintf("wrong sequence number\n"); 531 #endif 532 eval = EINVAL; 533 goto done; 534 } 535 536 if ((eval = ipcperm(td->td_proc, &msqptr->msg_perm, IPC_W))) { 537 #ifdef MSG_DEBUG_OK 538 kprintf("requester doesn't have write access\n"); 539 #endif 540 eval = EINVAL; 541 goto done; 542 } 543 544 segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz; 545 #ifdef MSG_DEBUG_OK 546 kprintf("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz, 547 segs_needed); 548 #endif 549 for (;;) { 550 int need_more_resources = 0; 551 552 /* 553 * check msgsz 554 * (inside this loop in case msg_qbytes changes while we sleep) 555 */ 556 557 if (msgsz > msqptr->msg_qbytes) { 558 #ifdef MSG_DEBUG_OK 559 kprintf("msgsz > msqptr->msg_qbytes\n"); 560 #endif 561 eval = EINVAL; 562 goto done; 563 } 564 565 if (msqptr->msg_perm.mode & MSG_LOCKED) { 566 #ifdef MSG_DEBUG_OK 567 kprintf("msqid is locked\n"); 568 #endif 569 need_more_resources = 1; 570 } 571 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) { 572 #ifdef MSG_DEBUG_OK 573 kprintf("msgsz + msg_cbytes > msg_qbytes\n"); 574 #endif 575 need_more_resources = 1; 576 } 577 if (segs_needed > nfree_msgmaps) { 578 #ifdef MSG_DEBUG_OK 579 kprintf("segs_needed > nfree_msgmaps\n"); 580 #endif 581 need_more_resources = 1; 582 } 583 if (free_msghdrs == NULL) { 584 #ifdef MSG_DEBUG_OK 585 kprintf("no more msghdrs\n"); 586 #endif 587 need_more_resources = 1; 588 } 589 590 if (need_more_resources) { 591 int we_own_it; 592 593 if ((msgflg & IPC_NOWAIT) != 0) { 594 #ifdef MSG_DEBUG_OK 595 kprintf("need more resources but caller doesn't want to wait\n"); 596 #endif 597 eval = EAGAIN; 598 goto done; 599 } 600 601 if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) { 602 #ifdef MSG_DEBUG_OK 603 kprintf("we don't own the msqid_ds\n"); 604 #endif 605 we_own_it = 0; 606 } else { 607 /* Force later arrivals to wait for our 608 request */ 609 #ifdef MSG_DEBUG_OK 610 kprintf("we own the msqid_ds\n"); 611 #endif 612 msqptr->msg_perm.mode |= MSG_LOCKED; 613 we_own_it = 1; 614 } 615 #ifdef MSG_DEBUG_OK 616 kprintf("goodnight\n"); 617 #endif 618 eval = tsleep((caddr_t)msqptr, PCATCH, "msgwait", 0); 619 #ifdef MSG_DEBUG_OK 620 kprintf("good morning, eval=%d\n", eval); 621 #endif 622 if (we_own_it) 623 msqptr->msg_perm.mode &= ~MSG_LOCKED; 624 if (eval != 0) { 625 #ifdef MSG_DEBUG_OK 626 kprintf("msgsnd: interrupted system call\n"); 627 #endif 628 eval = EINTR; 629 goto done; 630 } 631 632 /* 633 * Make sure that the msq queue still exists 634 */ 635 636 if (msqptr->msg_qbytes == 0) { 637 #ifdef MSG_DEBUG_OK 638 kprintf("msqid deleted\n"); 639 #endif 640 eval = EIDRM; 641 goto done; 642 } 643 644 } else { 645 #ifdef MSG_DEBUG_OK 646 kprintf("got all the resources that we need\n"); 647 #endif 648 break; 649 } 650 } 651 652 /* 653 * We have the resources that we need. 654 * Make sure! 655 */ 656 657 if (msqptr->msg_perm.mode & MSG_LOCKED) 658 panic("msg_perm.mode & MSG_LOCKED"); 659 if (segs_needed > nfree_msgmaps) 660 panic("segs_needed > nfree_msgmaps"); 661 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) 662 panic("msgsz + msg_cbytes > msg_qbytes"); 663 if (free_msghdrs == NULL) 664 panic("no more msghdrs"); 665 666 /* 667 * Re-lock the msqid_ds in case we page-fault when copying in the 668 * message 669 */ 670 671 if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) 672 panic("msqid_ds is already locked"); 673 msqptr->msg_perm.mode |= MSG_LOCKED; 674 675 /* 676 * Allocate a message header 677 */ 678 679 msghdr = free_msghdrs; 680 free_msghdrs = msghdr->msg_next; 681 msghdr->msg_spot = -1; 682 msghdr->msg_ts = msgsz; 683 684 /* 685 * Allocate space for the message 686 */ 687 688 while (segs_needed > 0) { 689 if (nfree_msgmaps <= 0) 690 panic("not enough msgmaps"); 691 if (free_msgmaps == -1) 692 panic("nil free_msgmaps"); 693 next = free_msgmaps; 694 if (next <= -1) 695 panic("next too low #1"); 696 if (next >= msginfo.msgseg) 697 panic("next out of range #1"); 698 #ifdef MSG_DEBUG_OK 699 kprintf("allocating segment %d to message\n", next); 700 #endif 701 free_msgmaps = msgmaps[next].next; 702 nfree_msgmaps--; 703 msgmaps[next].next = msghdr->msg_spot; 704 msghdr->msg_spot = next; 705 segs_needed--; 706 } 707 708 /* 709 * Copy in the message type 710 */ 711 712 if ((eval = copyin(user_msgp, &msghdr->msg_type, 713 sizeof(msghdr->msg_type))) != 0) { 714 #ifdef MSG_DEBUG_OK 715 kprintf("error %d copying the message type\n", eval); 716 #endif 717 msg_freehdr(msghdr); 718 msqptr->msg_perm.mode &= ~MSG_LOCKED; 719 wakeup((caddr_t)msqptr); 720 goto done; 721 } 722 user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type); 723 724 /* 725 * Validate the message type 726 */ 727 728 if (msghdr->msg_type < 1) { 729 msg_freehdr(msghdr); 730 msqptr->msg_perm.mode &= ~MSG_LOCKED; 731 wakeup((caddr_t)msqptr); 732 #ifdef MSG_DEBUG_OK 733 kprintf("mtype (%d) < 1\n", msghdr->msg_type); 734 #endif 735 eval = EINVAL; 736 goto done; 737 } 738 739 /* 740 * Copy in the message body 741 */ 742 743 next = msghdr->msg_spot; 744 while (msgsz > 0) { 745 size_t tlen; 746 if (msgsz > msginfo.msgssz) 747 tlen = msginfo.msgssz; 748 else 749 tlen = msgsz; 750 if (next <= -1) 751 panic("next too low #2"); 752 if (next >= msginfo.msgseg) 753 panic("next out of range #2"); 754 if ((eval = copyin(user_msgp, &msgpool[next * msginfo.msgssz], 755 tlen)) != 0) { 756 #ifdef MSG_DEBUG_OK 757 kprintf("error %d copying in message segment\n", eval); 758 #endif 759 msg_freehdr(msghdr); 760 msqptr->msg_perm.mode &= ~MSG_LOCKED; 761 wakeup((caddr_t)msqptr); 762 goto done; 763 } 764 msgsz -= tlen; 765 user_msgp = (char *)user_msgp + tlen; 766 next = msgmaps[next].next; 767 } 768 if (next != -1) 769 panic("didn't use all the msg segments"); 770 771 /* 772 * We've got the message. Unlock the msqid_ds. 773 */ 774 775 msqptr->msg_perm.mode &= ~MSG_LOCKED; 776 777 /* 778 * Make sure that the msqid_ds is still allocated. 779 */ 780 781 if (msqptr->msg_qbytes == 0) { 782 msg_freehdr(msghdr); 783 wakeup((caddr_t)msqptr); 784 eval = EIDRM; 785 goto done; 786 } 787 788 /* 789 * Put the message into the queue 790 */ 791 792 if (msqptr->msg_first == NULL) { 793 msqptr->msg_first = msghdr; 794 msqptr->msg_last = msghdr; 795 } else { 796 msqptr->msg_last->msg_next = msghdr; 797 msqptr->msg_last = msghdr; 798 } 799 msqptr->msg_last->msg_next = NULL; 800 801 msqptr->msg_cbytes += msghdr->msg_ts; 802 msqptr->msg_qnum++; 803 msqptr->msg_lspid = td->td_proc->p_pid; 804 msqptr->msg_stime = time_second; 805 806 wakeup((caddr_t)msqptr); 807 eval = 0; 808 done: 809 rel_mplock(); 810 if (eval == 0) 811 uap->sysmsg_result = 0; 812 return (eval); 813 } 814 815 /* 816 * MPALMOSTSAFE 817 */ 818 int 819 sys_msgrcv(struct msgrcv_args *uap) 820 { 821 struct thread *td = curthread; 822 int msqid = uap->msqid; 823 void *user_msgp = uap->msgp; 824 size_t msgsz = uap->msgsz; 825 long msgtyp = uap->msgtyp; 826 int msgflg = uap->msgflg; 827 size_t len; 828 struct msqid_ds *msqptr; 829 struct msg *msghdr; 830 int eval; 831 short next; 832 833 #ifdef MSG_DEBUG_OK 834 kprintf("call to msgrcv(%d, 0x%x, %d, %ld, %d)\n", msqid, user_msgp, 835 msgsz, msgtyp, msgflg); 836 #endif 837 838 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 839 return (ENOSYS); 840 841 get_mplock(); 842 msqid = IPCID_TO_IX(msqid); 843 844 if (msqid < 0 || msqid >= msginfo.msgmni) { 845 #ifdef MSG_DEBUG_OK 846 kprintf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, 847 msginfo.msgmni); 848 #endif 849 eval = EINVAL; 850 goto done; 851 } 852 853 msqptr = &msqids[msqid]; 854 if (msqptr->msg_qbytes == 0) { 855 #ifdef MSG_DEBUG_OK 856 kprintf("no such message queue id\n"); 857 #endif 858 eval = EINVAL; 859 goto done; 860 } 861 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 862 #ifdef MSG_DEBUG_OK 863 kprintf("wrong sequence number\n"); 864 #endif 865 eval = EINVAL; 866 goto done; 867 } 868 869 if ((eval = ipcperm(td->td_proc, &msqptr->msg_perm, IPC_R))) { 870 #ifdef MSG_DEBUG_OK 871 kprintf("requester doesn't have read access\n"); 872 #endif 873 goto done; 874 } 875 876 msghdr = NULL; 877 while (msghdr == NULL) { 878 if (msgtyp == 0) { 879 msghdr = msqptr->msg_first; 880 if (msghdr != NULL) { 881 if (msgsz < msghdr->msg_ts && 882 (msgflg & MSG_NOERROR) == 0) { 883 #ifdef MSG_DEBUG_OK 884 kprintf("first message on the queue is too big (want %d, got %d)\n", 885 msgsz, msghdr->msg_ts); 886 #endif 887 eval = E2BIG; 888 goto done; 889 } 890 if (msqptr->msg_first == msqptr->msg_last) { 891 msqptr->msg_first = NULL; 892 msqptr->msg_last = NULL; 893 } else { 894 msqptr->msg_first = msghdr->msg_next; 895 if (msqptr->msg_first == NULL) 896 panic("msg_first/last screwed up #1"); 897 } 898 } 899 } else { 900 struct msg *previous; 901 struct msg **prev; 902 903 previous = NULL; 904 prev = &(msqptr->msg_first); 905 while ((msghdr = *prev) != NULL) { 906 /* 907 * Is this message's type an exact match or is 908 * this message's type less than or equal to 909 * the absolute value of a negative msgtyp? 910 * Note that the second half of this test can 911 * NEVER be true if msgtyp is positive since 912 * msg_type is always positive! 913 */ 914 915 if (msgtyp == msghdr->msg_type || 916 msghdr->msg_type <= -msgtyp) { 917 #ifdef MSG_DEBUG_OK 918 kprintf("found message type %d, requested %d\n", 919 msghdr->msg_type, msgtyp); 920 #endif 921 if (msgsz < msghdr->msg_ts && 922 (msgflg & MSG_NOERROR) == 0) { 923 #ifdef MSG_DEBUG_OK 924 kprintf("requested message on the queue is too big (want %d, got %d)\n", 925 msgsz, msghdr->msg_ts); 926 #endif 927 eval = E2BIG; 928 goto done; 929 } 930 *prev = msghdr->msg_next; 931 if (msghdr == msqptr->msg_last) { 932 if (previous == NULL) { 933 if (prev != 934 &msqptr->msg_first) 935 panic("msg_first/last screwed up #2"); 936 msqptr->msg_first = 937 NULL; 938 msqptr->msg_last = 939 NULL; 940 } else { 941 if (prev == 942 &msqptr->msg_first) 943 panic("msg_first/last screwed up #3"); 944 msqptr->msg_last = 945 previous; 946 } 947 } 948 break; 949 } 950 previous = msghdr; 951 prev = &(msghdr->msg_next); 952 } 953 } 954 955 /* 956 * We've either extracted the msghdr for the appropriate 957 * message or there isn't one. 958 * If there is one then bail out of this loop. 959 */ 960 961 if (msghdr != NULL) 962 break; 963 964 /* 965 * Hmph! No message found. Does the user want to wait? 966 */ 967 968 if ((msgflg & IPC_NOWAIT) != 0) { 969 #ifdef MSG_DEBUG_OK 970 kprintf("no appropriate message found (msgtyp=%d)\n", 971 msgtyp); 972 #endif 973 /* The SVID says to return ENOMSG. */ 974 #ifdef ENOMSG 975 eval = ENOMSG; 976 #else 977 /* Unfortunately, BSD doesn't define that code yet! */ 978 eval = EAGAIN; 979 #endif 980 goto done; 981 } 982 983 /* 984 * Wait for something to happen 985 */ 986 987 #ifdef MSG_DEBUG_OK 988 kprintf("msgrcv: goodnight\n"); 989 #endif 990 eval = tsleep((caddr_t)msqptr, PCATCH, "msgwait", 0); 991 #ifdef MSG_DEBUG_OK 992 kprintf("msgrcv: good morning (eval=%d)\n", eval); 993 #endif 994 995 if (eval != 0) { 996 #ifdef MSG_DEBUG_OK 997 kprintf("msgsnd: interrupted system call\n"); 998 #endif 999 eval = EINTR; 1000 goto done; 1001 } 1002 1003 /* 1004 * Make sure that the msq queue still exists 1005 */ 1006 1007 if (msqptr->msg_qbytes == 0 || 1008 msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 1009 #ifdef MSG_DEBUG_OK 1010 kprintf("msqid deleted\n"); 1011 #endif 1012 eval = EIDRM; 1013 goto done; 1014 } 1015 } 1016 1017 /* 1018 * Return the message to the user. 1019 * 1020 * First, do the bookkeeping (before we risk being interrupted). 1021 */ 1022 1023 msqptr->msg_cbytes -= msghdr->msg_ts; 1024 msqptr->msg_qnum--; 1025 msqptr->msg_lrpid = td->td_proc->p_pid; 1026 msqptr->msg_rtime = time_second; 1027 1028 /* 1029 * Make msgsz the actual amount that we'll be returning. 1030 * Note that this effectively truncates the message if it is too long 1031 * (since msgsz is never increased). 1032 */ 1033 1034 #ifdef MSG_DEBUG_OK 1035 kprintf("found a message, msgsz=%d, msg_ts=%d\n", msgsz, 1036 msghdr->msg_ts); 1037 #endif 1038 if (msgsz > msghdr->msg_ts) 1039 msgsz = msghdr->msg_ts; 1040 1041 /* 1042 * Return the type to the user. 1043 */ 1044 1045 eval = copyout((caddr_t)&(msghdr->msg_type), user_msgp, 1046 sizeof(msghdr->msg_type)); 1047 if (eval != 0) { 1048 #ifdef MSG_DEBUG_OK 1049 kprintf("error (%d) copying out message type\n", eval); 1050 #endif 1051 msg_freehdr(msghdr); 1052 wakeup((caddr_t)msqptr); 1053 goto done; 1054 } 1055 user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type); 1056 1057 /* 1058 * Return the segments to the user 1059 */ 1060 1061 next = msghdr->msg_spot; 1062 for (len = 0; len < msgsz; len += msginfo.msgssz) { 1063 size_t tlen; 1064 1065 if (msgsz - len > msginfo.msgssz) 1066 tlen = msginfo.msgssz; 1067 else 1068 tlen = msgsz - len; 1069 if (next <= -1) 1070 panic("next too low #3"); 1071 if (next >= msginfo.msgseg) 1072 panic("next out of range #3"); 1073 eval = copyout((caddr_t)&msgpool[next * msginfo.msgssz], 1074 user_msgp, tlen); 1075 if (eval != 0) { 1076 #ifdef MSG_DEBUG_OK 1077 kprintf("error (%d) copying out message segment\n", 1078 eval); 1079 #endif 1080 msg_freehdr(msghdr); 1081 wakeup((caddr_t)msqptr); 1082 goto done; 1083 } 1084 user_msgp = (char *)user_msgp + tlen; 1085 next = msgmaps[next].next; 1086 } 1087 1088 /* 1089 * Done, return the actual number of bytes copied out. 1090 */ 1091 1092 msg_freehdr(msghdr); 1093 wakeup((caddr_t)msqptr); 1094 eval = 0; 1095 done: 1096 rel_mplock(); 1097 if (eval == 0) 1098 uap->sysmsg_result = msgsz; 1099 return(eval); 1100 } 1101 1102 static int 1103 sysctl_msqids(SYSCTL_HANDLER_ARGS) 1104 { 1105 1106 return (SYSCTL_OUT(req, msqids, 1107 sizeof(struct msqid_ds) * msginfo.msgmni)); 1108 } 1109 1110 TUNABLE_INT("kern.ipc.msgseg", &msginfo.msgseg); 1111 TUNABLE_INT("kern.ipc.msgssz", &msginfo.msgssz); 1112 TUNABLE_INT("kern.ipc.msgmni", &msginfo.msgmni); 1113 1114 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmax, CTLFLAG_RD, &msginfo.msgmax, 0, 1115 "Max characters in message"); 1116 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmni, CTLFLAG_RD, &msginfo.msgmni, 0, 1117 "Max message queue identifiers"); 1118 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmnb, CTLFLAG_RD, &msginfo.msgmnb, 0, 1119 "Max characters in message queue"); 1120 SYSCTL_INT(_kern_ipc, OID_AUTO, msgtql, CTLFLAG_RD, &msginfo.msgtql, 0, 1121 "Max SVID messages in system"); 1122 SYSCTL_INT(_kern_ipc, OID_AUTO, msgssz, CTLFLAG_RD, &msginfo.msgssz, 0, 1123 "Power-of-two size of a message segment"); 1124 SYSCTL_INT(_kern_ipc, OID_AUTO, msgseg, CTLFLAG_RD, &msginfo.msgseg, 0, 1125 "Number of message segments"); 1126 SYSCTL_PROC(_kern_ipc, OID_AUTO, msqids, CTLFLAG_RD, 1127 NULL, 0, sysctl_msqids, "", "Message queue IDs");
Cache object: 15023f82bfff1c3cbaa22b1b523d0e50
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