1 /* $FreeBSD$ */ 2 3 /* 4 * Implementation of SVID semaphores 5 * 6 * Author: Daniel Boulet 7 * 8 * This software is provided ``AS IS'' without any warranties of any kind. 9 */ 10 11 #include "opt_sysvipc.h" 12 13 #include <sys/param.h> 14 #include <sys/systm.h> 15 #include <sys/sysproto.h> 16 #include <sys/kernel.h> 17 #include <sys/proc.h> 18 #include <sys/sem.h> 19 #include <sys/syscall.h> 20 #include <sys/sysent.h> 21 #include <sys/sysctl.h> 22 #include <sys/malloc.h> 23 #include <sys/jail.h> 24 25 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores"); 26 27 static void seminit __P((void)); 28 static int sysvsem_modload __P((struct module *, int, void *)); 29 static int semunload __P((void)); 30 static void semexit_myhook __P((struct proc *p)); 31 32 #ifndef _SYS_SYSPROTO_H_ 33 struct __semctl_args; 34 int __semctl __P((struct proc *p, struct __semctl_args *uap)); 35 struct semget_args; 36 int semget __P((struct proc *p, struct semget_args *uap)); 37 struct semop_args; 38 int semop __P((struct proc *p, struct semop_args *uap)); 39 #endif 40 41 static struct sem_undo *semu_alloc __P((struct proc *p)); 42 static int semundo_adjust __P((struct proc *p, struct sem_undo **supptr, 43 int semid, int semnum, int adjval)); 44 static void semundo_clear __P((int semid, int semnum)); 45 46 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 47 static sy_call_t *semcalls[] = { 48 (sy_call_t *)__semctl, (sy_call_t *)semget, 49 (sy_call_t *)semop 50 }; 51 52 static int semtot = 0; 53 static struct semid_ds *sema; /* semaphore id pool */ 54 static struct sem *sem; /* semaphore pool */ 55 static struct sem_undo *semu_list; /* list of active undo structures */ 56 static int *semu; /* undo structure pool */ 57 58 struct sem { 59 u_short semval; /* semaphore value */ 60 pid_t sempid; /* pid of last operation */ 61 u_short semncnt; /* # awaiting semval > cval */ 62 u_short semzcnt; /* # awaiting semval = 0 */ 63 }; 64 65 /* 66 * Undo structure (one per process) 67 */ 68 struct sem_undo { 69 struct sem_undo *un_next; /* ptr to next active undo structure */ 70 struct proc *un_proc; /* owner of this structure */ 71 short un_cnt; /* # of active entries */ 72 struct undo { 73 short un_adjval; /* adjust on exit values */ 74 short un_num; /* semaphore # */ 75 int un_id; /* semid */ 76 } un_ent[1]; /* undo entries */ 77 }; 78 79 /* 80 * Configuration parameters 81 */ 82 #ifndef SEMMNI 83 #define SEMMNI 10 /* # of semaphore identifiers */ 84 #endif 85 #ifndef SEMMNS 86 #define SEMMNS 60 /* # of semaphores in system */ 87 #endif 88 #ifndef SEMUME 89 #define SEMUME 10 /* max # of undo entries per process */ 90 #endif 91 #ifndef SEMMNU 92 #define SEMMNU 30 /* # of undo structures in system */ 93 #endif 94 95 /* shouldn't need tuning */ 96 #ifndef SEMMAP 97 #define SEMMAP 30 /* # of entries in semaphore map */ 98 #endif 99 #ifndef SEMMSL 100 #define SEMMSL SEMMNS /* max # of semaphores per id */ 101 #endif 102 #ifndef SEMOPM 103 #define SEMOPM 100 /* max # of operations per semop call */ 104 #endif 105 106 #define SEMVMX 32767 /* semaphore maximum value */ 107 #define SEMAEM 16384 /* adjust on exit max value */ 108 109 /* 110 * Due to the way semaphore memory is allocated, we have to ensure that 111 * SEMUSZ is properly aligned. 112 */ 113 114 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1)) 115 116 /* actual size of an undo structure */ 117 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME])) 118 119 /* 120 * Macro to find a particular sem_undo vector 121 */ 122 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz)) 123 124 /* 125 * semaphore info struct 126 */ 127 struct seminfo seminfo = { 128 SEMMAP, /* # of entries in semaphore map */ 129 SEMMNI, /* # of semaphore identifiers */ 130 SEMMNS, /* # of semaphores in system */ 131 SEMMNU, /* # of undo structures in system */ 132 SEMMSL, /* max # of semaphores per id */ 133 SEMOPM, /* max # of operations per semop call */ 134 SEMUME, /* max # of undo entries per process */ 135 SEMUSZ, /* size in bytes of undo structure */ 136 SEMVMX, /* semaphore maximum value */ 137 SEMAEM /* adjust on exit max value */ 138 }; 139 140 SYSCTL_DECL(_kern_ipc); 141 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, ""); 143 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, ""); 144 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, ""); 145 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 146 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, ""); 147 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, ""); 148 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, ""); 149 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 150 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 151 152 #if 0 153 RO seminfo.semmap /* SEMMAP unused */ 154 RO seminfo.semmni 155 RO seminfo.semmns 156 RO seminfo.semmnu /* undo entries per system */ 157 RW seminfo.semmsl 158 RO seminfo.semopm /* SEMOPM unused */ 159 RO seminfo.semume 160 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */ 161 RO seminfo.semvmx /* SEMVMX unused - user param */ 162 RO seminfo.semaem /* SEMAEM unused - user param */ 163 #endif 164 165 static void 166 seminit(void) 167 { 168 register int i; 169 170 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 171 if (sem == NULL) 172 panic("sem is NULL"); 173 sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK); 174 if (sema == NULL) 175 panic("sema is NULL"); 176 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 177 if (semu == NULL) 178 panic("semu is NULL"); 179 180 for (i = 0; i < seminfo.semmni; i++) { 181 sema[i].sem_base = 0; 182 sema[i].sem_perm.mode = 0; 183 } 184 for (i = 0; i < seminfo.semmnu; i++) { 185 register struct sem_undo *suptr = SEMU(i); 186 suptr->un_proc = NULL; 187 } 188 semu_list = NULL; 189 semexit_hook = &semexit_myhook; 190 } 191 192 static int 193 semunload(void) 194 { 195 196 if (semtot != 0) 197 return (EBUSY); 198 199 free(sem, M_SEM); 200 free(sema, M_SEM); 201 free(semu, M_SEM); 202 semexit_hook = NULL; 203 return (0); 204 } 205 206 static int 207 sysvsem_modload(struct module *module, int cmd, void *arg) 208 { 209 int error = 0; 210 211 switch (cmd) { 212 case MOD_LOAD: 213 seminit(); 214 break; 215 case MOD_UNLOAD: 216 error = semunload(); 217 break; 218 case MOD_SHUTDOWN: 219 break; 220 default: 221 error = EINVAL; 222 break; 223 } 224 return (error); 225 } 226 227 static moduledata_t sysvsem_moduledata = { 228 "sysvsem_mod", 229 &sysvsem_modload, 230 NULL 231 }; 232 233 SYSCALL_MODULE_HELPER(semsys, 5); 234 SYSCALL_MODULE_HELPER(__semctl, 4); 235 SYSCALL_MODULE_HELPER(semget, 3); 236 SYSCALL_MODULE_HELPER(semop, 3); 237 238 DECLARE_MODULE(sysvsem_mod, sysvsem_moduledata, 239 SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 240 241 /* 242 * Entry point for all SEM calls 243 */ 244 int 245 semsys(p, uap) 246 struct proc *p; 247 /* XXX actually varargs. */ 248 struct semsys_args /* { 249 u_int which; 250 int a2; 251 int a3; 252 int a4; 253 int a5; 254 } */ *uap; 255 { 256 257 if (!jail_sysvipc_allowed && p->p_prison != NULL) 258 return (ENOSYS); 259 260 if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 261 return (EINVAL); 262 return ((*semcalls[uap->which])(p, &uap->a2)); 263 } 264 265 /* 266 * Allocate a new sem_undo structure for a process 267 * (returns ptr to structure or NULL if no more room) 268 */ 269 270 static struct sem_undo * 271 semu_alloc(p) 272 struct proc *p; 273 { 274 register int i; 275 register struct sem_undo *suptr; 276 register struct sem_undo **supptr; 277 int attempt; 278 279 /* 280 * Try twice to allocate something. 281 * (we'll purge any empty structures after the first pass so 282 * two passes are always enough) 283 */ 284 285 for (attempt = 0; attempt < 2; attempt++) { 286 /* 287 * Look for a free structure. 288 * Fill it in and return it if we find one. 289 */ 290 291 for (i = 0; i < seminfo.semmnu; i++) { 292 suptr = SEMU(i); 293 if (suptr->un_proc == NULL) { 294 suptr->un_next = semu_list; 295 semu_list = suptr; 296 suptr->un_cnt = 0; 297 suptr->un_proc = p; 298 return(suptr); 299 } 300 } 301 302 /* 303 * We didn't find a free one, if this is the first attempt 304 * then try to free some structures. 305 */ 306 307 if (attempt == 0) { 308 /* All the structures are in use - try to free some */ 309 int did_something = 0; 310 311 supptr = &semu_list; 312 while ((suptr = *supptr) != NULL) { 313 if (suptr->un_cnt == 0) { 314 suptr->un_proc = NULL; 315 *supptr = suptr->un_next; 316 did_something = 1; 317 } else 318 supptr = &(suptr->un_next); 319 } 320 321 /* If we didn't free anything then just give-up */ 322 if (!did_something) 323 return(NULL); 324 } else { 325 /* 326 * The second pass failed even though we freed 327 * something after the first pass! 328 * This is IMPOSSIBLE! 329 */ 330 panic("semu_alloc - second attempt failed"); 331 } 332 } 333 return (NULL); 334 } 335 336 /* 337 * Adjust a particular entry for a particular proc 338 */ 339 340 static int 341 semundo_adjust(p, supptr, semid, semnum, adjval) 342 register struct proc *p; 343 struct sem_undo **supptr; 344 int semid, semnum; 345 int adjval; 346 { 347 register struct sem_undo *suptr; 348 register struct undo *sunptr; 349 int i; 350 351 /* Look for and remember the sem_undo if the caller doesn't provide 352 it */ 353 354 suptr = *supptr; 355 if (suptr == NULL) { 356 for (suptr = semu_list; suptr != NULL; 357 suptr = suptr->un_next) { 358 if (suptr->un_proc == p) { 359 *supptr = suptr; 360 break; 361 } 362 } 363 if (suptr == NULL) { 364 if (adjval == 0) 365 return(0); 366 suptr = semu_alloc(p); 367 if (suptr == NULL) 368 return(ENOSPC); 369 *supptr = suptr; 370 } 371 } 372 373 /* 374 * Look for the requested entry and adjust it (delete if adjval becomes 375 * 0). 376 */ 377 sunptr = &suptr->un_ent[0]; 378 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 379 if (sunptr->un_id != semid || sunptr->un_num != semnum) 380 continue; 381 if (adjval == 0) 382 sunptr->un_adjval = 0; 383 else 384 sunptr->un_adjval += adjval; 385 if (sunptr->un_adjval == 0) { 386 suptr->un_cnt--; 387 if (i < suptr->un_cnt) 388 suptr->un_ent[i] = 389 suptr->un_ent[suptr->un_cnt]; 390 } 391 return(0); 392 } 393 394 /* Didn't find the right entry - create it */ 395 if (adjval == 0) 396 return(0); 397 if (suptr->un_cnt != seminfo.semume) { 398 sunptr = &suptr->un_ent[suptr->un_cnt]; 399 suptr->un_cnt++; 400 sunptr->un_adjval = adjval; 401 sunptr->un_id = semid; sunptr->un_num = semnum; 402 } else 403 return(EINVAL); 404 return(0); 405 } 406 407 static void 408 semundo_clear(semid, semnum) 409 int semid, semnum; 410 { 411 register struct sem_undo *suptr; 412 413 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 414 register struct undo *sunptr = &suptr->un_ent[0]; 415 register int i = 0; 416 417 while (i < suptr->un_cnt) { 418 if (sunptr->un_id == semid) { 419 if (semnum == -1 || sunptr->un_num == semnum) { 420 suptr->un_cnt--; 421 if (i < suptr->un_cnt) { 422 suptr->un_ent[i] = 423 suptr->un_ent[suptr->un_cnt]; 424 continue; 425 } 426 } 427 if (semnum != -1) 428 break; 429 } 430 i++, sunptr++; 431 } 432 } 433 } 434 435 /* 436 * Note that the user-mode half of this passes a union, not a pointer 437 */ 438 #ifndef _SYS_SYSPROTO_H_ 439 struct __semctl_args { 440 int semid; 441 int semnum; 442 int cmd; 443 union semun *arg; 444 }; 445 #endif 446 447 int 448 __semctl(p, uap) 449 struct proc *p; 450 register struct __semctl_args *uap; 451 { 452 int semid = uap->semid; 453 int semnum = uap->semnum; 454 int cmd = uap->cmd; 455 union semun *arg = uap->arg; 456 union semun real_arg; 457 struct ucred *cred = p->p_ucred; 458 int i, rval, eval; 459 struct semid_ds sbuf; 460 register struct semid_ds *semaptr; 461 462 #ifdef SEM_DEBUG 463 printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 464 #endif 465 466 if (!jail_sysvipc_allowed && p->p_prison != NULL) 467 return (ENOSYS); 468 469 semid = IPCID_TO_IX(semid); 470 if (semid < 0 || semid >= seminfo.semmsl) 471 return(EINVAL); 472 473 semaptr = &sema[semid]; 474 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 475 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 476 return(EINVAL); 477 478 eval = 0; 479 rval = 0; 480 481 switch (cmd) { 482 case IPC_RMID: 483 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 484 return(eval); 485 semaptr->sem_perm.cuid = cred->cr_uid; 486 semaptr->sem_perm.uid = cred->cr_uid; 487 semtot -= semaptr->sem_nsems; 488 for (i = semaptr->sem_base - sem; i < semtot; i++) 489 sem[i] = sem[i + semaptr->sem_nsems]; 490 for (i = 0; i < seminfo.semmni; i++) { 491 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 492 sema[i].sem_base > semaptr->sem_base) 493 sema[i].sem_base -= semaptr->sem_nsems; 494 } 495 semaptr->sem_perm.mode = 0; 496 semundo_clear(semid, -1); 497 wakeup((caddr_t)semaptr); 498 break; 499 500 case IPC_SET: 501 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 502 return(eval); 503 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 504 return(eval); 505 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf, 506 sizeof(sbuf))) != 0) 507 return(eval); 508 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 509 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 510 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 511 (sbuf.sem_perm.mode & 0777); 512 semaptr->sem_ctime = time_second; 513 break; 514 515 case IPC_STAT: 516 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 517 return(eval); 518 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 519 return(eval); 520 eval = copyout((caddr_t)semaptr, real_arg.buf, 521 sizeof(struct semid_ds)); 522 break; 523 524 case GETNCNT: 525 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 526 return(eval); 527 if (semnum < 0 || semnum >= semaptr->sem_nsems) 528 return(EINVAL); 529 rval = semaptr->sem_base[semnum].semncnt; 530 break; 531 532 case GETPID: 533 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 534 return(eval); 535 if (semnum < 0 || semnum >= semaptr->sem_nsems) 536 return(EINVAL); 537 rval = semaptr->sem_base[semnum].sempid; 538 break; 539 540 case GETVAL: 541 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 542 return(eval); 543 if (semnum < 0 || semnum >= semaptr->sem_nsems) 544 return(EINVAL); 545 rval = semaptr->sem_base[semnum].semval; 546 break; 547 548 case GETALL: 549 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 550 return(eval); 551 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 552 return(eval); 553 for (i = 0; i < semaptr->sem_nsems; i++) { 554 eval = copyout((caddr_t)&semaptr->sem_base[i].semval, 555 &real_arg.array[i], sizeof(real_arg.array[0])); 556 if (eval != 0) 557 break; 558 } 559 break; 560 561 case GETZCNT: 562 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 563 return(eval); 564 if (semnum < 0 || semnum >= semaptr->sem_nsems) 565 return(EINVAL); 566 rval = semaptr->sem_base[semnum].semzcnt; 567 break; 568 569 case SETVAL: 570 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 571 return(eval); 572 if (semnum < 0 || semnum >= semaptr->sem_nsems) 573 return(EINVAL); 574 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 575 return(eval); 576 semaptr->sem_base[semnum].semval = real_arg.val; 577 semundo_clear(semid, semnum); 578 wakeup((caddr_t)semaptr); 579 break; 580 581 case SETALL: 582 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 583 return(eval); 584 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 585 return(eval); 586 for (i = 0; i < semaptr->sem_nsems; i++) { 587 eval = copyin(&real_arg.array[i], 588 (caddr_t)&semaptr->sem_base[i].semval, 589 sizeof(real_arg.array[0])); 590 if (eval != 0) 591 break; 592 } 593 semundo_clear(semid, -1); 594 wakeup((caddr_t)semaptr); 595 break; 596 597 default: 598 return(EINVAL); 599 } 600 601 if (eval == 0) 602 p->p_retval[0] = rval; 603 return(eval); 604 } 605 606 #ifndef _SYS_SYSPROTO_H_ 607 struct semget_args { 608 key_t key; 609 int nsems; 610 int semflg; 611 }; 612 #endif 613 614 int 615 semget(p, uap) 616 struct proc *p; 617 register struct semget_args *uap; 618 { 619 int semid, eval; 620 int key = uap->key; 621 int nsems = uap->nsems; 622 int semflg = uap->semflg; 623 struct ucred *cred = p->p_ucred; 624 625 #ifdef SEM_DEBUG 626 printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 627 #endif 628 629 if (!jail_sysvipc_allowed && p->p_prison != NULL) 630 return (ENOSYS); 631 632 if (key != IPC_PRIVATE) { 633 for (semid = 0; semid < seminfo.semmni; semid++) { 634 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 635 sema[semid].sem_perm.key == key) 636 break; 637 } 638 if (semid < seminfo.semmni) { 639 #ifdef SEM_DEBUG 640 printf("found public key\n"); 641 #endif 642 if ((eval = ipcperm(p, &sema[semid].sem_perm, 643 semflg & 0700))) 644 return(eval); 645 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 646 #ifdef SEM_DEBUG 647 printf("too small\n"); 648 #endif 649 return(EINVAL); 650 } 651 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 652 #ifdef SEM_DEBUG 653 printf("not exclusive\n"); 654 #endif 655 return(EEXIST); 656 } 657 goto found; 658 } 659 } 660 661 #ifdef SEM_DEBUG 662 printf("need to allocate the semid_ds\n"); 663 #endif 664 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 665 if (nsems <= 0 || nsems > seminfo.semmsl) { 666 #ifdef SEM_DEBUG 667 printf("nsems out of range (0<%d<=%d)\n", nsems, 668 seminfo.semmsl); 669 #endif 670 return(EINVAL); 671 } 672 if (nsems > seminfo.semmns - semtot) { 673 #ifdef SEM_DEBUG 674 printf("not enough semaphores left (need %d, got %d)\n", 675 nsems, seminfo.semmns - semtot); 676 #endif 677 return(ENOSPC); 678 } 679 for (semid = 0; semid < seminfo.semmni; semid++) { 680 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 681 break; 682 } 683 if (semid == seminfo.semmni) { 684 #ifdef SEM_DEBUG 685 printf("no more semid_ds's available\n"); 686 #endif 687 return(ENOSPC); 688 } 689 #ifdef SEM_DEBUG 690 printf("semid %d is available\n", semid); 691 #endif 692 sema[semid].sem_perm.key = key; 693 sema[semid].sem_perm.cuid = cred->cr_uid; 694 sema[semid].sem_perm.uid = cred->cr_uid; 695 sema[semid].sem_perm.cgid = cred->cr_gid; 696 sema[semid].sem_perm.gid = cred->cr_gid; 697 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 698 sema[semid].sem_perm.seq = 699 (sema[semid].sem_perm.seq + 1) & 0x7fff; 700 sema[semid].sem_nsems = nsems; 701 sema[semid].sem_otime = 0; 702 sema[semid].sem_ctime = time_second; 703 sema[semid].sem_base = &sem[semtot]; 704 semtot += nsems; 705 bzero(sema[semid].sem_base, 706 sizeof(sema[semid].sem_base[0])*nsems); 707 #ifdef SEM_DEBUG 708 printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 709 &sem[semtot]); 710 #endif 711 } else { 712 #ifdef SEM_DEBUG 713 printf("didn't find it and wasn't asked to create it\n"); 714 #endif 715 return(ENOENT); 716 } 717 718 found: 719 p->p_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 720 return(0); 721 } 722 723 #ifndef _SYS_SYSPROTO_H_ 724 struct semop_args { 725 int semid; 726 struct sembuf *sops; 727 int nsops; 728 }; 729 #endif 730 731 int 732 semop(p, uap) 733 struct proc *p; 734 register struct semop_args *uap; 735 { 736 int semid = uap->semid; 737 int nsops = uap->nsops; 738 struct sembuf sops[MAX_SOPS]; 739 register struct semid_ds *semaptr; 740 register struct sembuf *sopptr; 741 register struct sem *semptr; 742 struct sem_undo *suptr = NULL; 743 int i, j, eval; 744 int do_wakeup, do_undos; 745 746 #ifdef SEM_DEBUG 747 printf("call to semop(%d, 0x%x, %d)\n", semid, sops, nsops); 748 #endif 749 750 if (!jail_sysvipc_allowed && p->p_prison != NULL) 751 return (ENOSYS); 752 753 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 754 755 if (semid < 0 || semid >= seminfo.semmsl) 756 return(EINVAL); 757 758 semaptr = &sema[semid]; 759 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 760 return(EINVAL); 761 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 762 return(EINVAL); 763 764 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) { 765 #ifdef SEM_DEBUG 766 printf("eval = %d from ipaccess\n", eval); 767 #endif 768 return(eval); 769 } 770 771 if (nsops > MAX_SOPS) { 772 #ifdef SEM_DEBUG 773 printf("too many sops (max=%d, nsops=%d)\n", MAX_SOPS, nsops); 774 #endif 775 return(E2BIG); 776 } 777 778 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 779 #ifdef SEM_DEBUG 780 printf("eval = %d from copyin(%08x, %08x, %d)\n", eval, 781 uap->sops, &sops, nsops * sizeof(sops[0])); 782 #endif 783 return(eval); 784 } 785 786 /* 787 * Loop trying to satisfy the vector of requests. 788 * If we reach a point where we must wait, any requests already 789 * performed are rolled back and we go to sleep until some other 790 * process wakes us up. At this point, we start all over again. 791 * 792 * This ensures that from the perspective of other tasks, a set 793 * of requests is atomic (never partially satisfied). 794 */ 795 do_undos = 0; 796 797 for (;;) { 798 do_wakeup = 0; 799 800 for (i = 0; i < nsops; i++) { 801 sopptr = &sops[i]; 802 803 if (sopptr->sem_num >= semaptr->sem_nsems) 804 return(EFBIG); 805 806 semptr = &semaptr->sem_base[sopptr->sem_num]; 807 808 #ifdef SEM_DEBUG 809 printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 810 semaptr, semaptr->sem_base, semptr, 811 sopptr->sem_num, semptr->semval, sopptr->sem_op, 812 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 813 #endif 814 815 if (sopptr->sem_op < 0) { 816 if (semptr->semval + sopptr->sem_op < 0) { 817 #ifdef SEM_DEBUG 818 printf("semop: can't do it now\n"); 819 #endif 820 break; 821 } else { 822 semptr->semval += sopptr->sem_op; 823 if (semptr->semval == 0 && 824 semptr->semzcnt > 0) 825 do_wakeup = 1; 826 } 827 if (sopptr->sem_flg & SEM_UNDO) 828 do_undos = 1; 829 } else if (sopptr->sem_op == 0) { 830 if (semptr->semval > 0) { 831 #ifdef SEM_DEBUG 832 printf("semop: not zero now\n"); 833 #endif 834 break; 835 } 836 } else { 837 if (semptr->semncnt > 0) 838 do_wakeup = 1; 839 semptr->semval += sopptr->sem_op; 840 if (sopptr->sem_flg & SEM_UNDO) 841 do_undos = 1; 842 } 843 } 844 845 /* 846 * Did we get through the entire vector? 847 */ 848 if (i >= nsops) 849 goto done; 850 851 /* 852 * No ... rollback anything that we've already done 853 */ 854 #ifdef SEM_DEBUG 855 printf("semop: rollback 0 through %d\n", i-1); 856 #endif 857 for (j = 0; j < i; j++) 858 semaptr->sem_base[sops[j].sem_num].semval -= 859 sops[j].sem_op; 860 861 /* 862 * If the request that we couldn't satisfy has the 863 * NOWAIT flag set then return with EAGAIN. 864 */ 865 if (sopptr->sem_flg & IPC_NOWAIT) 866 return(EAGAIN); 867 868 if (sopptr->sem_op == 0) 869 semptr->semzcnt++; 870 else 871 semptr->semncnt++; 872 873 #ifdef SEM_DEBUG 874 printf("semop: good night!\n"); 875 #endif 876 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 877 "semwait", 0); 878 #ifdef SEM_DEBUG 879 printf("semop: good morning (eval=%d)!\n", eval); 880 #endif 881 882 suptr = NULL; /* sem_undo may have been reallocated */ 883 884 if (eval != 0) 885 return(EINTR); 886 #ifdef SEM_DEBUG 887 printf("semop: good morning!\n"); 888 #endif 889 890 /* 891 * Make sure that the semaphore still exists 892 */ 893 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 894 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 895 return(EIDRM); 896 897 /* 898 * The semaphore is still alive. Readjust the count of 899 * waiting processes. 900 */ 901 if (sopptr->sem_op == 0) 902 semptr->semzcnt--; 903 else 904 semptr->semncnt--; 905 } 906 907 done: 908 /* 909 * Process any SEM_UNDO requests. 910 */ 911 if (do_undos) { 912 for (i = 0; i < nsops; i++) { 913 /* 914 * We only need to deal with SEM_UNDO's for non-zero 915 * op's. 916 */ 917 int adjval; 918 919 if ((sops[i].sem_flg & SEM_UNDO) == 0) 920 continue; 921 adjval = sops[i].sem_op; 922 if (adjval == 0) 923 continue; 924 eval = semundo_adjust(p, &suptr, semid, 925 sops[i].sem_num, -adjval); 926 if (eval == 0) 927 continue; 928 929 /* 930 * Oh-Oh! We ran out of either sem_undo's or undo's. 931 * Rollback the adjustments to this point and then 932 * rollback the semaphore ups and down so we can return 933 * with an error with all structures restored. We 934 * rollback the undo's in the exact reverse order that 935 * we applied them. This guarantees that we won't run 936 * out of space as we roll things back out. 937 */ 938 for (j = i - 1; j >= 0; j--) { 939 if ((sops[j].sem_flg & SEM_UNDO) == 0) 940 continue; 941 adjval = sops[j].sem_op; 942 if (adjval == 0) 943 continue; 944 if (semundo_adjust(p, &suptr, semid, 945 sops[j].sem_num, adjval) != 0) 946 panic("semop - can't undo undos"); 947 } 948 949 for (j = 0; j < nsops; j++) 950 semaptr->sem_base[sops[j].sem_num].semval -= 951 sops[j].sem_op; 952 953 #ifdef SEM_DEBUG 954 printf("eval = %d from semundo_adjust\n", eval); 955 #endif 956 return(eval); 957 } /* loop through the sops */ 958 } /* if (do_undos) */ 959 960 /* We're definitely done - set the sempid's */ 961 for (i = 0; i < nsops; i++) { 962 sopptr = &sops[i]; 963 semptr = &semaptr->sem_base[sopptr->sem_num]; 964 semptr->sempid = p->p_pid; 965 } 966 967 /* Do a wakeup if any semaphore was up'd. */ 968 if (do_wakeup) { 969 #ifdef SEM_DEBUG 970 printf("semop: doing wakeup\n"); 971 #endif 972 wakeup((caddr_t)semaptr); 973 #ifdef SEM_DEBUG 974 printf("semop: back from wakeup\n"); 975 #endif 976 } 977 #ifdef SEM_DEBUG 978 printf("semop: done\n"); 979 #endif 980 p->p_retval[0] = 0; 981 return(0); 982 } 983 984 /* 985 * Go through the undo structures for this process and apply the adjustments to 986 * semaphores. 987 */ 988 static void 989 semexit_myhook(p) 990 struct proc *p; 991 { 992 register struct sem_undo *suptr; 993 register struct sem_undo **supptr; 994 int did_something; 995 996 did_something = 0; 997 998 /* 999 * Go through the chain of undo vectors looking for one 1000 * associated with this process. 1001 */ 1002 1003 for (supptr = &semu_list; (suptr = *supptr) != NULL; 1004 supptr = &suptr->un_next) { 1005 if (suptr->un_proc == p) 1006 break; 1007 } 1008 1009 if (suptr == NULL) 1010 return; 1011 1012 #ifdef SEM_DEBUG 1013 printf("proc @%08x has undo structure with %d entries\n", p, 1014 suptr->un_cnt); 1015 #endif 1016 1017 /* 1018 * If there are any active undo elements then process them. 1019 */ 1020 if (suptr->un_cnt > 0) { 1021 int ix; 1022 1023 for (ix = 0; ix < suptr->un_cnt; ix++) { 1024 int semid = suptr->un_ent[ix].un_id; 1025 int semnum = suptr->un_ent[ix].un_num; 1026 int adjval = suptr->un_ent[ix].un_adjval; 1027 struct semid_ds *semaptr; 1028 1029 semaptr = &sema[semid]; 1030 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1031 panic("semexit - semid not allocated"); 1032 if (semnum >= semaptr->sem_nsems) 1033 panic("semexit - semnum out of range"); 1034 1035 #ifdef SEM_DEBUG 1036 printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 1037 suptr->un_proc, suptr->un_ent[ix].un_id, 1038 suptr->un_ent[ix].un_num, 1039 suptr->un_ent[ix].un_adjval, 1040 semaptr->sem_base[semnum].semval); 1041 #endif 1042 1043 if (adjval < 0) { 1044 if (semaptr->sem_base[semnum].semval < -adjval) 1045 semaptr->sem_base[semnum].semval = 0; 1046 else 1047 semaptr->sem_base[semnum].semval += 1048 adjval; 1049 } else 1050 semaptr->sem_base[semnum].semval += adjval; 1051 1052 wakeup((caddr_t)semaptr); 1053 #ifdef SEM_DEBUG 1054 printf("semexit: back from wakeup\n"); 1055 #endif 1056 } 1057 } 1058 1059 /* 1060 * Deallocate the undo vector. 1061 */ 1062 #ifdef SEM_DEBUG 1063 printf("removing vector\n"); 1064 #endif 1065 suptr->un_proc = NULL; 1066 *supptr = suptr->un_next; 1067 } 1068