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 /* 2 * Implementation of SVID messages 3 * 4 * Author: Daniel Boulet 5 * 6 * Copyright 1993 Daniel Boulet and RTMX Inc. 7 * 8 * This system call was implemented by Daniel Boulet under contract from RTMX. 9 * 10 * Redistribution and use in source forms, with and without modification, 11 * are permitted provided that this entire comment appears intact. 12 * 13 * Redistribution in binary form may occur without any restrictions. 14 * Obviously, it would be nice if you gave credit where credit is due 15 * but requiring it would be too onerous. 16 * 17 * This software is provided ``AS IS'' without any warranties of any kind. 18 */ 19 20 #include <sys/cdefs.h> 21 __FBSDID("$FreeBSD: releng/5.3/sys/kern/sysv_msg.c 136588 2004-10-16 08:43:07Z cvs2svn $"); 22 23 #include "opt_sysvipc.h" 24 25 #include <sys/param.h> 26 #include <sys/systm.h> 27 #include <sys/sysproto.h> 28 #include <sys/kernel.h> 29 #include <sys/proc.h> 30 #include <sys/lock.h> 31 #include <sys/mutex.h> 32 #include <sys/module.h> 33 #include <sys/msg.h> 34 #include <sys/syscall.h> 35 #include <sys/sysent.h> 36 #include <sys/sysctl.h> 37 #include <sys/malloc.h> 38 #include <sys/jail.h> 39 40 static MALLOC_DEFINE(M_MSG, "msg", "SVID compatible message queues"); 41 42 static void msginit(void); 43 static int msgunload(void); 44 static int sysvmsg_modload(struct module *, int, void *); 45 46 #ifdef MSG_DEBUG 47 #define DPRINTF(a) printf a 48 #else 49 #define DPRINTF(a) 50 #endif 51 52 static void msg_freehdr(struct msg *msghdr); 53 54 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 55 static sy_call_t *msgcalls[] = { 56 (sy_call_t *)msgctl, (sy_call_t *)msgget, 57 (sy_call_t *)msgsnd, (sy_call_t *)msgrcv 58 }; 59 60 struct msg { 61 struct msg *msg_next; /* next msg in the chain */ 62 long msg_type; /* type of this message */ 63 /* >0 -> type of this message */ 64 /* 0 -> free header */ 65 u_short msg_ts; /* size of this message */ 66 short msg_spot; /* location of start of msg in buffer */ 67 }; 68 69 70 #ifndef MSGSSZ 71 #define MSGSSZ 8 /* Each segment must be 2^N long */ 72 #endif 73 #ifndef MSGSEG 74 #define MSGSEG 2048 /* must be less than 32767 */ 75 #endif 76 #define MSGMAX (MSGSSZ*MSGSEG) 77 #ifndef MSGMNB 78 #define MSGMNB 2048 /* max # of bytes in a queue */ 79 #endif 80 #ifndef MSGMNI 81 #define MSGMNI 40 82 #endif 83 #ifndef MSGTQL 84 #define MSGTQL 40 85 #endif 86 87 /* 88 * Based on the configuration parameters described in an SVR2 (yes, two) 89 * config(1m) man page. 90 * 91 * Each message is broken up and stored in segments that are msgssz bytes 92 * long. For efficiency reasons, this should be a power of two. Also, 93 * it doesn't make sense if it is less than 8 or greater than about 256. 94 * Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of 95 * two between 8 and 1024 inclusive (and panic's if it isn't). 96 */ 97 struct msginfo msginfo = { 98 MSGMAX, /* max chars in a message */ 99 MSGMNI, /* # of message queue identifiers */ 100 MSGMNB, /* max chars in a queue */ 101 MSGTQL, /* max messages in system */ 102 MSGSSZ, /* size of a message segment */ 103 /* (must be small power of 2 greater than 4) */ 104 MSGSEG /* number of message segments */ 105 }; 106 107 /* 108 * macros to convert between msqid_ds's and msqid's. 109 * (specific to this implementation) 110 */ 111 #define MSQID(ix,ds) ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000)) 112 #define MSQID_IX(id) ((id) & 0xffff) 113 #define MSQID_SEQ(id) (((id) >> 16) & 0xffff) 114 115 /* 116 * The rest of this file is specific to this particular implementation. 117 */ 118 119 struct msgmap { 120 short next; /* next segment in buffer */ 121 /* -1 -> available */ 122 /* 0..(MSGSEG-1) -> index of next segment */ 123 }; 124 125 #define MSG_LOCKED 01000 /* Is this msqid_ds locked? */ 126 127 static int nfree_msgmaps; /* # of free map entries */ 128 static short free_msgmaps; /* head of linked list of free map entries */ 129 static struct msg *free_msghdrs;/* list of free msg headers */ 130 static char *msgpool; /* MSGMAX byte long msg buffer pool */ 131 static struct msgmap *msgmaps; /* MSGSEG msgmap structures */ 132 static struct msg *msghdrs; /* MSGTQL msg headers */ 133 static struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */ 134 static struct mtx msq_mtx; /* global mutex for message queues. */ 135 136 static void 137 msginit() 138 { 139 register int i; 140 141 TUNABLE_INT_FETCH("kern.ipc.msgseg", &msginfo.msgseg); 142 TUNABLE_INT_FETCH("kern.ipc.msgssz", &msginfo.msgssz); 143 msginfo.msgmax = msginfo.msgseg * msginfo.msgssz; 144 TUNABLE_INT_FETCH("kern.ipc.msgmni", &msginfo.msgmni); 145 146 msgpool = malloc(msginfo.msgmax, M_MSG, M_WAITOK); 147 if (msgpool == NULL) 148 panic("msgpool is NULL"); 149 msgmaps = malloc(sizeof(struct msgmap) * msginfo.msgseg, M_MSG, M_WAITOK); 150 if (msgmaps == NULL) 151 panic("msgmaps is NULL"); 152 msghdrs = malloc(sizeof(struct msg) * msginfo.msgtql, M_MSG, M_WAITOK); 153 if (msghdrs == NULL) 154 panic("msghdrs is NULL"); 155 msqids = malloc(sizeof(struct msqid_ds) * msginfo.msgmni, M_MSG, M_WAITOK); 156 if (msqids == NULL) 157 panic("msqids is NULL"); 158 159 /* 160 * msginfo.msgssz should be a power of two for efficiency reasons. 161 * It is also pretty silly if msginfo.msgssz is less than 8 162 * or greater than about 256 so ... 163 */ 164 165 i = 8; 166 while (i < 1024 && i != msginfo.msgssz) 167 i <<= 1; 168 if (i != msginfo.msgssz) { 169 DPRINTF(("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz, 170 msginfo.msgssz)); 171 panic("msginfo.msgssz not a small power of 2"); 172 } 173 174 if (msginfo.msgseg > 32767) { 175 DPRINTF(("msginfo.msgseg=%d\n", msginfo.msgseg)); 176 panic("msginfo.msgseg > 32767"); 177 } 178 179 if (msgmaps == NULL) 180 panic("msgmaps is NULL"); 181 182 for (i = 0; i < msginfo.msgseg; i++) { 183 if (i > 0) 184 msgmaps[i-1].next = i; 185 msgmaps[i].next = -1; /* implies entry is available */ 186 } 187 free_msgmaps = 0; 188 nfree_msgmaps = msginfo.msgseg; 189 190 if (msghdrs == NULL) 191 panic("msghdrs is NULL"); 192 193 for (i = 0; i < msginfo.msgtql; i++) { 194 msghdrs[i].msg_type = 0; 195 if (i > 0) 196 msghdrs[i-1].msg_next = &msghdrs[i]; 197 msghdrs[i].msg_next = NULL; 198 } 199 free_msghdrs = &msghdrs[0]; 200 201 if (msqids == NULL) 202 panic("msqids is NULL"); 203 204 for (i = 0; i < msginfo.msgmni; i++) { 205 msqids[i].msg_qbytes = 0; /* implies entry is available */ 206 msqids[i].msg_perm.seq = 0; /* reset to a known value */ 207 msqids[i].msg_perm.mode = 0; 208 } 209 mtx_init(&msq_mtx, "msq", NULL, MTX_DEF); 210 } 211 212 static int 213 msgunload() 214 { 215 struct msqid_ds *msqptr; 216 int msqid; 217 218 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 219 /* 220 * Look for an unallocated and unlocked msqid_ds. 221 * msqid_ds's can be locked by msgsnd or msgrcv while 222 * they are copying the message in/out. We can't 223 * re-use the entry until they release it. 224 */ 225 msqptr = &msqids[msqid]; 226 if (msqptr->msg_qbytes != 0 || 227 (msqptr->msg_perm.mode & MSG_LOCKED) != 0) 228 break; 229 } 230 if (msqid != msginfo.msgmni) 231 return (EBUSY); 232 233 free(msgpool, M_MSG); 234 free(msgmaps, M_MSG); 235 free(msghdrs, M_MSG); 236 free(msqids, M_MSG); 237 mtx_destroy(&msq_mtx); 238 return (0); 239 } 240 241 242 static int 243 sysvmsg_modload(struct module *module, int cmd, void *arg) 244 { 245 int error = 0; 246 247 switch (cmd) { 248 case MOD_LOAD: 249 msginit(); 250 break; 251 case MOD_UNLOAD: 252 error = msgunload(); 253 break; 254 case MOD_SHUTDOWN: 255 break; 256 default: 257 error = EINVAL; 258 break; 259 } 260 return (error); 261 } 262 263 static moduledata_t sysvmsg_mod = { 264 "sysvmsg", 265 &sysvmsg_modload, 266 NULL 267 }; 268 269 SYSCALL_MODULE_HELPER(msgsys); 270 SYSCALL_MODULE_HELPER(msgctl); 271 SYSCALL_MODULE_HELPER(msgget); 272 SYSCALL_MODULE_HELPER(msgsnd); 273 SYSCALL_MODULE_HELPER(msgrcv); 274 275 DECLARE_MODULE(sysvmsg, sysvmsg_mod, 276 SI_SUB_SYSV_MSG, SI_ORDER_FIRST); 277 MODULE_VERSION(sysvmsg, 1); 278 279 /* 280 * Entry point for all MSG calls 281 * 282 * MPSAFE 283 */ 284 int 285 msgsys(td, uap) 286 struct thread *td; 287 /* XXX actually varargs. */ 288 struct msgsys_args /* { 289 int which; 290 int a2; 291 int a3; 292 int a4; 293 int a5; 294 int a6; 295 } */ *uap; 296 { 297 int error; 298 299 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 300 return (ENOSYS); 301 if (uap->which < 0 || 302 uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0])) 303 return (EINVAL); 304 error = (*msgcalls[uap->which])(td, &uap->a2); 305 return (error); 306 } 307 308 static void 309 msg_freehdr(msghdr) 310 struct msg *msghdr; 311 { 312 while (msghdr->msg_ts > 0) { 313 short next; 314 if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg) 315 panic("msghdr->msg_spot out of range"); 316 next = msgmaps[msghdr->msg_spot].next; 317 msgmaps[msghdr->msg_spot].next = free_msgmaps; 318 free_msgmaps = msghdr->msg_spot; 319 nfree_msgmaps++; 320 msghdr->msg_spot = next; 321 if (msghdr->msg_ts >= msginfo.msgssz) 322 msghdr->msg_ts -= msginfo.msgssz; 323 else 324 msghdr->msg_ts = 0; 325 } 326 if (msghdr->msg_spot != -1) 327 panic("msghdr->msg_spot != -1"); 328 msghdr->msg_next = free_msghdrs; 329 free_msghdrs = msghdr; 330 } 331 332 #ifndef _SYS_SYSPROTO_H_ 333 struct msgctl_args { 334 int msqid; 335 int cmd; 336 struct msqid_ds *buf; 337 }; 338 #endif 339 340 /* 341 * MPSAFE 342 */ 343 int 344 msgctl(td, uap) 345 struct thread *td; 346 register struct msgctl_args *uap; 347 { 348 int msqid = uap->msqid; 349 int cmd = uap->cmd; 350 struct msqid_ds *user_msqptr = uap->buf; 351 int rval, error; 352 struct msqid_ds msqbuf; 353 register struct msqid_ds *msqptr; 354 355 DPRINTF(("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr)); 356 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 357 return (ENOSYS); 358 359 msqid = IPCID_TO_IX(msqid); 360 361 if (msqid < 0 || msqid >= msginfo.msgmni) { 362 DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid, 363 msginfo.msgmni)); 364 return (EINVAL); 365 } 366 if (cmd == IPC_SET && 367 (error = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0) 368 return (error); 369 370 msqptr = &msqids[msqid]; 371 372 mtx_lock(&msq_mtx); 373 if (msqptr->msg_qbytes == 0) { 374 DPRINTF(("no such msqid\n")); 375 error = EINVAL; 376 goto done2; 377 } 378 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 379 DPRINTF(("wrong sequence number\n")); 380 error = EINVAL; 381 goto done2; 382 } 383 384 error = 0; 385 rval = 0; 386 387 switch (cmd) { 388 389 case IPC_RMID: 390 { 391 struct msg *msghdr; 392 if ((error = ipcperm(td, &msqptr->msg_perm, IPC_M))) 393 goto done2; 394 /* Free the message headers */ 395 msghdr = msqptr->msg_first; 396 while (msghdr != NULL) { 397 struct msg *msghdr_tmp; 398 399 /* Free the segments of each message */ 400 msqptr->msg_cbytes -= msghdr->msg_ts; 401 msqptr->msg_qnum--; 402 msghdr_tmp = msghdr; 403 msghdr = msghdr->msg_next; 404 msg_freehdr(msghdr_tmp); 405 } 406 407 if (msqptr->msg_cbytes != 0) 408 panic("msg_cbytes is screwed up"); 409 if (msqptr->msg_qnum != 0) 410 panic("msg_qnum is screwed up"); 411 412 msqptr->msg_qbytes = 0; /* Mark it as free */ 413 414 wakeup(msqptr); 415 } 416 417 break; 418 419 case IPC_SET: 420 if ((error = ipcperm(td, &msqptr->msg_perm, IPC_M))) 421 goto done2; 422 if (msqbuf.msg_qbytes > msqptr->msg_qbytes) { 423 error = suser(td); 424 if (error) 425 goto done2; 426 } 427 if (msqbuf.msg_qbytes > msginfo.msgmnb) { 428 DPRINTF(("can't increase msg_qbytes beyond %d" 429 "(truncating)\n", msginfo.msgmnb)); 430 msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */ 431 } 432 if (msqbuf.msg_qbytes == 0) { 433 DPRINTF(("can't reduce msg_qbytes to 0\n")); 434 error = EINVAL; /* non-standard errno! */ 435 goto done2; 436 } 437 msqptr->msg_perm.uid = msqbuf.msg_perm.uid; /* change the owner */ 438 msqptr->msg_perm.gid = msqbuf.msg_perm.gid; /* change the owner */ 439 msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) | 440 (msqbuf.msg_perm.mode & 0777); 441 msqptr->msg_qbytes = msqbuf.msg_qbytes; 442 msqptr->msg_ctime = time_second; 443 break; 444 445 case IPC_STAT: 446 if ((error = ipcperm(td, &msqptr->msg_perm, IPC_R))) { 447 DPRINTF(("requester doesn't have read access\n")); 448 goto done2; 449 } 450 break; 451 452 default: 453 DPRINTF(("invalid command %d\n", cmd)); 454 error = EINVAL; 455 goto done2; 456 } 457 458 if (error == 0) 459 td->td_retval[0] = rval; 460 done2: 461 mtx_unlock(&msq_mtx); 462 if (cmd == IPC_STAT && error == 0) 463 error = copyout(msqptr, user_msqptr, sizeof(struct msqid_ds)); 464 return(error); 465 } 466 467 #ifndef _SYS_SYSPROTO_H_ 468 struct msgget_args { 469 key_t key; 470 int msgflg; 471 }; 472 #endif 473 474 /* 475 * MPSAFE 476 */ 477 int 478 msgget(td, uap) 479 struct thread *td; 480 register struct msgget_args *uap; 481 { 482 int msqid, error = 0; 483 int key = uap->key; 484 int msgflg = uap->msgflg; 485 struct ucred *cred = td->td_ucred; 486 register struct msqid_ds *msqptr = NULL; 487 488 DPRINTF(("msgget(0x%x, 0%o)\n", key, msgflg)); 489 490 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 491 return (ENOSYS); 492 493 mtx_lock(&msq_mtx); 494 if (key != IPC_PRIVATE) { 495 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 496 msqptr = &msqids[msqid]; 497 if (msqptr->msg_qbytes != 0 && 498 msqptr->msg_perm.key == key) 499 break; 500 } 501 if (msqid < msginfo.msgmni) { 502 DPRINTF(("found public key\n")); 503 if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) { 504 DPRINTF(("not exclusive\n")); 505 error = EEXIST; 506 goto done2; 507 } 508 if ((error = ipcperm(td, &msqptr->msg_perm, msgflg & 0700))) { 509 DPRINTF(("requester doesn't have 0%o access\n", 510 msgflg & 0700)); 511 goto done2; 512 } 513 goto found; 514 } 515 } 516 517 DPRINTF(("need to allocate the msqid_ds\n")); 518 if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) { 519 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 520 /* 521 * Look for an unallocated and unlocked msqid_ds. 522 * msqid_ds's can be locked by msgsnd or msgrcv while 523 * they are copying the message in/out. We can't 524 * re-use the entry until they release it. 525 */ 526 msqptr = &msqids[msqid]; 527 if (msqptr->msg_qbytes == 0 && 528 (msqptr->msg_perm.mode & MSG_LOCKED) == 0) 529 break; 530 } 531 if (msqid == msginfo.msgmni) { 532 DPRINTF(("no more msqid_ds's available\n")); 533 error = ENOSPC; 534 goto done2; 535 } 536 DPRINTF(("msqid %d is available\n", msqid)); 537 msqptr->msg_perm.key = key; 538 msqptr->msg_perm.cuid = cred->cr_uid; 539 msqptr->msg_perm.uid = cred->cr_uid; 540 msqptr->msg_perm.cgid = cred->cr_gid; 541 msqptr->msg_perm.gid = cred->cr_gid; 542 msqptr->msg_perm.mode = (msgflg & 0777); 543 /* Make sure that the returned msqid is unique */ 544 msqptr->msg_perm.seq = (msqptr->msg_perm.seq + 1) & 0x7fff; 545 msqptr->msg_first = NULL; 546 msqptr->msg_last = NULL; 547 msqptr->msg_cbytes = 0; 548 msqptr->msg_qnum = 0; 549 msqptr->msg_qbytes = msginfo.msgmnb; 550 msqptr->msg_lspid = 0; 551 msqptr->msg_lrpid = 0; 552 msqptr->msg_stime = 0; 553 msqptr->msg_rtime = 0; 554 msqptr->msg_ctime = time_second; 555 } else { 556 DPRINTF(("didn't find it and wasn't asked to create it\n")); 557 error = ENOENT; 558 goto done2; 559 } 560 561 found: 562 /* Construct the unique msqid */ 563 td->td_retval[0] = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm); 564 done2: 565 mtx_unlock(&msq_mtx); 566 return (error); 567 } 568 569 #ifndef _SYS_SYSPROTO_H_ 570 struct msgsnd_args { 571 int msqid; 572 const void *msgp; 573 size_t msgsz; 574 int msgflg; 575 }; 576 #endif 577 578 /* 579 * MPSAFE 580 */ 581 int 582 msgsnd(td, uap) 583 struct thread *td; 584 register struct msgsnd_args *uap; 585 { 586 int msqid = uap->msqid; 587 const void *user_msgp = uap->msgp; 588 size_t msgsz = uap->msgsz; 589 int msgflg = uap->msgflg; 590 int segs_needed, error = 0; 591 register struct msqid_ds *msqptr; 592 register struct msg *msghdr; 593 short next; 594 595 DPRINTF(("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz, 596 msgflg)); 597 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 598 return (ENOSYS); 599 600 mtx_lock(&msq_mtx); 601 msqid = IPCID_TO_IX(msqid); 602 603 if (msqid < 0 || msqid >= msginfo.msgmni) { 604 DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid, 605 msginfo.msgmni)); 606 error = EINVAL; 607 goto done2; 608 } 609 610 msqptr = &msqids[msqid]; 611 if (msqptr->msg_qbytes == 0) { 612 DPRINTF(("no such message queue id\n")); 613 error = EINVAL; 614 goto done2; 615 } 616 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 617 DPRINTF(("wrong sequence number\n")); 618 error = EINVAL; 619 goto done2; 620 } 621 622 if ((error = ipcperm(td, &msqptr->msg_perm, IPC_W))) { 623 DPRINTF(("requester doesn't have write access\n")); 624 goto done2; 625 } 626 627 segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz; 628 DPRINTF(("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz, 629 segs_needed)); 630 for (;;) { 631 int need_more_resources = 0; 632 633 /* 634 * check msgsz 635 * (inside this loop in case msg_qbytes changes while we sleep) 636 */ 637 638 if (msgsz > msqptr->msg_qbytes) { 639 DPRINTF(("msgsz > msqptr->msg_qbytes\n")); 640 error = EINVAL; 641 goto done2; 642 } 643 644 if (msqptr->msg_perm.mode & MSG_LOCKED) { 645 DPRINTF(("msqid is locked\n")); 646 need_more_resources = 1; 647 } 648 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) { 649 DPRINTF(("msgsz + msg_cbytes > msg_qbytes\n")); 650 need_more_resources = 1; 651 } 652 if (segs_needed > nfree_msgmaps) { 653 DPRINTF(("segs_needed > nfree_msgmaps\n")); 654 need_more_resources = 1; 655 } 656 if (free_msghdrs == NULL) { 657 DPRINTF(("no more msghdrs\n")); 658 need_more_resources = 1; 659 } 660 661 if (need_more_resources) { 662 int we_own_it; 663 664 if ((msgflg & IPC_NOWAIT) != 0) { 665 DPRINTF(("need more resources but caller " 666 "doesn't want to wait\n")); 667 error = EAGAIN; 668 goto done2; 669 } 670 671 if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) { 672 DPRINTF(("we don't own the msqid_ds\n")); 673 we_own_it = 0; 674 } else { 675 /* Force later arrivals to wait for our 676 request */ 677 DPRINTF(("we own the msqid_ds\n")); 678 msqptr->msg_perm.mode |= MSG_LOCKED; 679 we_own_it = 1; 680 } 681 DPRINTF(("goodnight\n")); 682 error = msleep(msqptr, &msq_mtx, (PZERO - 4) | PCATCH, 683 "msgwait", 0); 684 DPRINTF(("good morning, error=%d\n", error)); 685 if (we_own_it) 686 msqptr->msg_perm.mode &= ~MSG_LOCKED; 687 if (error != 0) { 688 DPRINTF(("msgsnd: interrupted system call\n")); 689 error = EINTR; 690 goto done2; 691 } 692 693 /* 694 * Make sure that the msq queue still exists 695 */ 696 697 if (msqptr->msg_qbytes == 0) { 698 DPRINTF(("msqid deleted\n")); 699 error = EIDRM; 700 goto done2; 701 } 702 703 } else { 704 DPRINTF(("got all the resources that we need\n")); 705 break; 706 } 707 } 708 709 /* 710 * We have the resources that we need. 711 * Make sure! 712 */ 713 714 if (msqptr->msg_perm.mode & MSG_LOCKED) 715 panic("msg_perm.mode & MSG_LOCKED"); 716 if (segs_needed > nfree_msgmaps) 717 panic("segs_needed > nfree_msgmaps"); 718 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) 719 panic("msgsz + msg_cbytes > msg_qbytes"); 720 if (free_msghdrs == NULL) 721 panic("no more msghdrs"); 722 723 /* 724 * Re-lock the msqid_ds in case we page-fault when copying in the 725 * message 726 */ 727 728 if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) 729 panic("msqid_ds is already locked"); 730 msqptr->msg_perm.mode |= MSG_LOCKED; 731 732 /* 733 * Allocate a message header 734 */ 735 736 msghdr = free_msghdrs; 737 free_msghdrs = msghdr->msg_next; 738 msghdr->msg_spot = -1; 739 msghdr->msg_ts = msgsz; 740 741 /* 742 * Allocate space for the message 743 */ 744 745 while (segs_needed > 0) { 746 if (nfree_msgmaps <= 0) 747 panic("not enough msgmaps"); 748 if (free_msgmaps == -1) 749 panic("nil free_msgmaps"); 750 next = free_msgmaps; 751 if (next <= -1) 752 panic("next too low #1"); 753 if (next >= msginfo.msgseg) 754 panic("next out of range #1"); 755 DPRINTF(("allocating segment %d to message\n", next)); 756 free_msgmaps = msgmaps[next].next; 757 nfree_msgmaps--; 758 msgmaps[next].next = msghdr->msg_spot; 759 msghdr->msg_spot = next; 760 segs_needed--; 761 } 762 763 /* 764 * Copy in the message type 765 */ 766 767 mtx_unlock(&msq_mtx); 768 if ((error = copyin(user_msgp, &msghdr->msg_type, 769 sizeof(msghdr->msg_type))) != 0) { 770 mtx_lock(&msq_mtx); 771 DPRINTF(("error %d copying the message type\n", error)); 772 msg_freehdr(msghdr); 773 msqptr->msg_perm.mode &= ~MSG_LOCKED; 774 wakeup(msqptr); 775 goto done2; 776 } 777 mtx_lock(&msq_mtx); 778 user_msgp = (const char *)user_msgp + sizeof(msghdr->msg_type); 779 780 /* 781 * Validate the message type 782 */ 783 784 if (msghdr->msg_type < 1) { 785 msg_freehdr(msghdr); 786 msqptr->msg_perm.mode &= ~MSG_LOCKED; 787 wakeup(msqptr); 788 DPRINTF(("mtype (%d) < 1\n", msghdr->msg_type)); 789 error = EINVAL; 790 goto done2; 791 } 792 793 /* 794 * Copy in the message body 795 */ 796 797 next = msghdr->msg_spot; 798 while (msgsz > 0) { 799 size_t tlen; 800 if (msgsz > msginfo.msgssz) 801 tlen = msginfo.msgssz; 802 else 803 tlen = msgsz; 804 if (next <= -1) 805 panic("next too low #2"); 806 if (next >= msginfo.msgseg) 807 panic("next out of range #2"); 808 mtx_unlock(&msq_mtx); 809 if ((error = copyin(user_msgp, &msgpool[next * msginfo.msgssz], 810 tlen)) != 0) { 811 mtx_lock(&msq_mtx); 812 DPRINTF(("error %d copying in message segment\n", 813 error)); 814 msg_freehdr(msghdr); 815 msqptr->msg_perm.mode &= ~MSG_LOCKED; 816 wakeup(msqptr); 817 goto done2; 818 } 819 mtx_lock(&msq_mtx); 820 msgsz -= tlen; 821 user_msgp = (const char *)user_msgp + tlen; 822 next = msgmaps[next].next; 823 } 824 if (next != -1) 825 panic("didn't use all the msg segments"); 826 827 /* 828 * We've got the message. Unlock the msqid_ds. 829 */ 830 831 msqptr->msg_perm.mode &= ~MSG_LOCKED; 832 833 /* 834 * Make sure that the msqid_ds is still allocated. 835 */ 836 837 if (msqptr->msg_qbytes == 0) { 838 msg_freehdr(msghdr); 839 wakeup(msqptr); 840 error = EIDRM; 841 goto done2; 842 } 843 844 /* 845 * Put the message into the queue 846 */ 847 848 if (msqptr->msg_first == NULL) { 849 msqptr->msg_first = msghdr; 850 msqptr->msg_last = msghdr; 851 } else { 852 msqptr->msg_last->msg_next = msghdr; 853 msqptr->msg_last = msghdr; 854 } 855 msqptr->msg_last->msg_next = NULL; 856 857 msqptr->msg_cbytes += msghdr->msg_ts; 858 msqptr->msg_qnum++; 859 msqptr->msg_lspid = td->td_proc->p_pid; 860 msqptr->msg_stime = time_second; 861 862 wakeup(msqptr); 863 td->td_retval[0] = 0; 864 done2: 865 mtx_unlock(&msq_mtx); 866 return (error); 867 } 868 869 #ifndef _SYS_SYSPROTO_H_ 870 struct msgrcv_args { 871 int msqid; 872 void *msgp; 873 size_t msgsz; 874 long msgtyp; 875 int msgflg; 876 }; 877 #endif 878 879 /* 880 * MPSAFE 881 */ 882 int 883 msgrcv(td, uap) 884 struct thread *td; 885 register struct msgrcv_args *uap; 886 { 887 int msqid = uap->msqid; 888 void *user_msgp = uap->msgp; 889 size_t msgsz = uap->msgsz; 890 long msgtyp = uap->msgtyp; 891 int msgflg = uap->msgflg; 892 size_t len; 893 register struct msqid_ds *msqptr; 894 register struct msg *msghdr; 895 int error = 0; 896 short next; 897 898 DPRINTF(("call to msgrcv(%d, 0x%x, %d, %ld, %d)\n", msqid, user_msgp, 899 msgsz, msgtyp, msgflg)); 900 901 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 902 return (ENOSYS); 903 904 msqid = IPCID_TO_IX(msqid); 905 906 if (msqid < 0 || msqid >= msginfo.msgmni) { 907 DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid, 908 msginfo.msgmni)); 909 return (EINVAL); 910 } 911 912 msqptr = &msqids[msqid]; 913 mtx_lock(&msq_mtx); 914 if (msqptr->msg_qbytes == 0) { 915 DPRINTF(("no such message queue id\n")); 916 error = EINVAL; 917 goto done2; 918 } 919 if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 920 DPRINTF(("wrong sequence number\n")); 921 error = EINVAL; 922 goto done2; 923 } 924 925 if ((error = ipcperm(td, &msqptr->msg_perm, IPC_R))) { 926 DPRINTF(("requester doesn't have read access\n")); 927 goto done2; 928 } 929 930 msghdr = NULL; 931 while (msghdr == NULL) { 932 if (msgtyp == 0) { 933 msghdr = msqptr->msg_first; 934 if (msghdr != NULL) { 935 if (msgsz < msghdr->msg_ts && 936 (msgflg & MSG_NOERROR) == 0) { 937 DPRINTF(("first message on the queue " 938 "is too big (want %d, got %d)\n", 939 msgsz, msghdr->msg_ts)); 940 error = E2BIG; 941 goto done2; 942 } 943 if (msqptr->msg_first == msqptr->msg_last) { 944 msqptr->msg_first = NULL; 945 msqptr->msg_last = NULL; 946 } else { 947 msqptr->msg_first = msghdr->msg_next; 948 if (msqptr->msg_first == NULL) 949 panic("msg_first/last screwed up #1"); 950 } 951 } 952 } else { 953 struct msg *previous; 954 struct msg **prev; 955 956 previous = NULL; 957 prev = &(msqptr->msg_first); 958 while ((msghdr = *prev) != NULL) { 959 /* 960 * Is this message's type an exact match or is 961 * this message's type less than or equal to 962 * the absolute value of a negative msgtyp? 963 * Note that the second half of this test can 964 * NEVER be true if msgtyp is positive since 965 * msg_type is always positive! 966 */ 967 968 if (msgtyp == msghdr->msg_type || 969 msghdr->msg_type <= -msgtyp) { 970 DPRINTF(("found message type %d, " 971 "requested %d\n", 972 msghdr->msg_type, msgtyp)); 973 if (msgsz < msghdr->msg_ts && 974 (msgflg & MSG_NOERROR) == 0) { 975 DPRINTF(("requested message " 976 "on the queue is too big " 977 "(want %d, got %d)\n", 978 msgsz, msghdr->msg_ts)); 979 error = E2BIG; 980 goto done2; 981 } 982 *prev = msghdr->msg_next; 983 if (msghdr == msqptr->msg_last) { 984 if (previous == NULL) { 985 if (prev != 986 &msqptr->msg_first) 987 panic("msg_first/last screwed up #2"); 988 msqptr->msg_first = 989 NULL; 990 msqptr->msg_last = 991 NULL; 992 } else { 993 if (prev == 994 &msqptr->msg_first) 995 panic("msg_first/last screwed up #3"); 996 msqptr->msg_last = 997 previous; 998 } 999 } 1000 break; 1001 } 1002 previous = msghdr; 1003 prev = &(msghdr->msg_next); 1004 } 1005 } 1006 1007 /* 1008 * We've either extracted the msghdr for the appropriate 1009 * message or there isn't one. 1010 * If there is one then bail out of this loop. 1011 */ 1012 1013 if (msghdr != NULL) 1014 break; 1015 1016 /* 1017 * Hmph! No message found. Does the user want to wait? 1018 */ 1019 1020 if ((msgflg & IPC_NOWAIT) != 0) { 1021 DPRINTF(("no appropriate message found (msgtyp=%d)\n", 1022 msgtyp)); 1023 /* The SVID says to return ENOMSG. */ 1024 error = ENOMSG; 1025 goto done2; 1026 } 1027 1028 /* 1029 * Wait for something to happen 1030 */ 1031 1032 DPRINTF(("msgrcv: goodnight\n")); 1033 error = msleep(msqptr, &msq_mtx, (PZERO - 4) | PCATCH, 1034 "msgwait", 0); 1035 DPRINTF(("msgrcv: good morning (error=%d)\n", error)); 1036 1037 if (error != 0) { 1038 DPRINTF(("msgsnd: interrupted system call\n")); 1039 error = EINTR; 1040 goto done2; 1041 } 1042 1043 /* 1044 * Make sure that the msq queue still exists 1045 */ 1046 1047 if (msqptr->msg_qbytes == 0 || 1048 msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { 1049 DPRINTF(("msqid deleted\n")); 1050 error = EIDRM; 1051 goto done2; 1052 } 1053 } 1054 1055 /* 1056 * Return the message to the user. 1057 * 1058 * First, do the bookkeeping (before we risk being interrupted). 1059 */ 1060 1061 msqptr->msg_cbytes -= msghdr->msg_ts; 1062 msqptr->msg_qnum--; 1063 msqptr->msg_lrpid = td->td_proc->p_pid; 1064 msqptr->msg_rtime = time_second; 1065 1066 /* 1067 * Make msgsz the actual amount that we'll be returning. 1068 * Note that this effectively truncates the message if it is too long 1069 * (since msgsz is never increased). 1070 */ 1071 1072 DPRINTF(("found a message, msgsz=%d, msg_ts=%d\n", msgsz, 1073 msghdr->msg_ts)); 1074 if (msgsz > msghdr->msg_ts) 1075 msgsz = msghdr->msg_ts; 1076 1077 /* 1078 * Return the type to the user. 1079 */ 1080 1081 mtx_unlock(&msq_mtx); 1082 error = copyout(&(msghdr->msg_type), user_msgp, 1083 sizeof(msghdr->msg_type)); 1084 mtx_lock(&msq_mtx); 1085 if (error != 0) { 1086 DPRINTF(("error (%d) copying out message type\n", error)); 1087 msg_freehdr(msghdr); 1088 wakeup(msqptr); 1089 goto done2; 1090 } 1091 user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type); 1092 1093 /* 1094 * Return the segments to the user 1095 */ 1096 1097 next = msghdr->msg_spot; 1098 for (len = 0; len < msgsz; len += msginfo.msgssz) { 1099 size_t tlen; 1100 1101 if (msgsz - len > msginfo.msgssz) 1102 tlen = msginfo.msgssz; 1103 else 1104 tlen = msgsz - len; 1105 if (next <= -1) 1106 panic("next too low #3"); 1107 if (next >= msginfo.msgseg) 1108 panic("next out of range #3"); 1109 mtx_unlock(&msq_mtx); 1110 error = copyout(&msgpool[next * msginfo.msgssz], 1111 user_msgp, tlen); 1112 mtx_lock(&msq_mtx); 1113 if (error != 0) { 1114 DPRINTF(("error (%d) copying out message segment\n", 1115 error)); 1116 msg_freehdr(msghdr); 1117 wakeup(msqptr); 1118 goto done2; 1119 } 1120 user_msgp = (char *)user_msgp + tlen; 1121 next = msgmaps[next].next; 1122 } 1123 1124 /* 1125 * Done, return the actual number of bytes copied out. 1126 */ 1127 1128 msg_freehdr(msghdr); 1129 wakeup(msqptr); 1130 td->td_retval[0] = msgsz; 1131 done2: 1132 mtx_unlock(&msq_mtx); 1133 return (error); 1134 } 1135 1136 static int 1137 sysctl_msqids(SYSCTL_HANDLER_ARGS) 1138 { 1139 1140 return (SYSCTL_OUT(req, msqids, 1141 sizeof(struct msqid_ds) * msginfo.msgmni)); 1142 } 1143 1144 SYSCTL_DECL(_kern_ipc); 1145 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmax, CTLFLAG_RD, &msginfo.msgmax, 0, ""); 1146 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmni, CTLFLAG_RDTUN, &msginfo.msgmni, 0, ""); 1147 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmnb, CTLFLAG_RD, &msginfo.msgmnb, 0, ""); 1148 SYSCTL_INT(_kern_ipc, OID_AUTO, msgtql, CTLFLAG_RD, &msginfo.msgtql, 0, ""); 1149 SYSCTL_INT(_kern_ipc, OID_AUTO, msgssz, CTLFLAG_RDTUN, &msginfo.msgssz, 0, ""); 1150 SYSCTL_INT(_kern_ipc, OID_AUTO, msgseg, CTLFLAG_RDTUN, &msginfo.msgseg, 0, ""); 1151 SYSCTL_PROC(_kern_ipc, OID_AUTO, msqids, CTLFLAG_RD, 1152 NULL, 0, sysctl_msqids, "", "Message queue IDs");
Cache object: 511181702bbc50572710fda1818995f7
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