1 /* This file deals with creating processes (via FORK) and deleting them (via 2 * EXIT/WAIT4). When a process forks, a new slot in the 'mproc' table is 3 * allocated for it, and a copy of the parent's core image is made for the 4 * child. Then the kernel and file system are informed. A process is removed 5 * from the 'mproc' table when two events have occurred: (1) it has exited or 6 * been killed by a signal, and (2) the parent has done a WAIT4. If the 7 * process exits first, it continues to occupy a slot until the parent does a 8 * WAIT4. 9 * 10 * The entry points into this file are: 11 * do_fork: perform the FORK system call 12 * do_srv_fork: special FORK, used by RS to create sys services 13 * do_exit: perform the EXIT system call (by calling exit_proc()) 14 * exit_proc: actually do the exiting, and tell VFS about it 15 * exit_restart: continue exiting a process after VFS has replied 16 * do_wait4: perform the WAIT4 system call 17 * wait_test: check whether a parent is waiting for a child 18 */ 19 20 #include "pm.h" 21 #include <sys/wait.h> 22 #include <assert.h> 23 #include <minix/callnr.h> 24 #include <minix/com.h> 25 #include <minix/sched.h> 26 #include <minix/vm.h> 27 #include <sys/ptrace.h> 28 #include <sys/resource.h> 29 #include <signal.h> 30 #include "mproc.h" 31 32 #define LAST_FEW 2 /* last few slots reserved for superuser */ 33 34 static void zombify(struct mproc *rmp); 35 static void check_parent(struct mproc *child, int try_cleanup); 36 static int tell_parent(struct mproc *child, vir_bytes addr); 37 static void tell_tracer(struct mproc *child); 38 static void tracer_died(struct mproc *child); 39 static void cleanup(register struct mproc *rmp); 40 41 /*===========================================================================* 42 * do_fork * 43 *===========================================================================*/ 44 int do_fork() 45 { 46 /* The process pointed to by 'mp' has forked. Create a child process. */ 47 register struct mproc *rmp; /* pointer to parent */ 48 register struct mproc *rmc; /* pointer to child */ 49 pid_t new_pid; 50 static unsigned int next_child = 0; 51 int i, n = 0, s; 52 endpoint_t child_ep; 53 message m; 54 55 /* If tables might fill up during FORK, don't even start since recovery half 56 * way through is such a nuisance. 57 */ 58 rmp = mp; 59 if ((procs_in_use == NR_PROCS) || 60 (procs_in_use >= NR_PROCS-LAST_FEW && rmp->mp_effuid != 0)) 61 { 62 printf("PM: warning, process table is full!\n"); 63 return(EAGAIN); 64 } 65 66 /* Find a slot in 'mproc' for the child process. A slot must exist. */ 67 do { 68 next_child = (next_child+1) % NR_PROCS; 69 n++; 70 } while((mproc[next_child].mp_flags & IN_USE) && n <= NR_PROCS); 71 if(n > NR_PROCS) 72 panic("do_fork can't find child slot"); 73 if(next_child >= NR_PROCS || (mproc[next_child].mp_flags & IN_USE)) 74 panic("do_fork finds wrong child slot: %d", next_child); 75 76 /* Memory part of the forking. */ 77 if((s=vm_fork(rmp->mp_endpoint, next_child, &child_ep)) != OK) { 78 return s; 79 } 80 81 /* PM may not fail fork after call to vm_fork(), as VM calls sys_fork(). */ 82 83 rmc = &mproc[next_child]; 84 /* Set up the child and its memory map; copy its 'mproc' slot from parent. */ 85 procs_in_use++; 86 *rmc = *rmp; /* copy parent's process slot to child's */ 87 rmc->mp_sigact = mpsigact[next_child]; /* restore mp_sigact ptr */ 88 memcpy(rmc->mp_sigact, rmp->mp_sigact, sizeof(mpsigact[next_child])); 89 rmc->mp_parent = who_p; /* record child's parent */ 90 if (!(rmc->mp_trace_flags & TO_TRACEFORK)) { 91 rmc->mp_tracer = NO_TRACER; /* no tracer attached */ 92 rmc->mp_trace_flags = 0; 93 (void) sigemptyset(&rmc->mp_sigtrace); 94 } 95 96 /* Some system servers like to call regular fork, such as RS spawning 97 * recovery scripts; in this case PM will take care of their scheduling 98 * because RS cannot do so for non-system processes */ 99 if (rmc->mp_flags & PRIV_PROC) { 100 assert(rmc->mp_scheduler == NONE); 101 rmc->mp_scheduler = SCHED_PROC_NR; 102 } 103 104 /* Inherit only these flags. In normal fork(), PRIV_PROC is not inherited. */ 105 rmc->mp_flags &= (IN_USE|DELAY_CALL|TAINTED); 106 rmc->mp_child_utime = 0; /* reset administration */ 107 rmc->mp_child_stime = 0; /* reset administration */ 108 rmc->mp_exitstatus = 0; 109 rmc->mp_sigstatus = 0; 110 rmc->mp_endpoint = child_ep; /* passed back by VM */ 111 for (i = 0; i < NR_ITIMERS; i++) 112 rmc->mp_interval[i] = 0; /* reset timer intervals */ 113 rmc->mp_started = getticks(); /* remember start time, for ps(1) */ 114 115 assert(rmc->mp_eventsub == NO_EVENTSUB); 116 117 /* Find a free pid for the child and put it in the table. */ 118 new_pid = get_free_pid(); 119 rmc->mp_pid = new_pid; /* assign pid to child */ 120 121 memset(&m, 0, sizeof(m)); 122 m.m_type = VFS_PM_FORK; 123 m.VFS_PM_ENDPT = rmc->mp_endpoint; 124 m.VFS_PM_PENDPT = rmp->mp_endpoint; 125 m.VFS_PM_CPID = rmc->mp_pid; 126 m.VFS_PM_REUID = -1; /* Not used by VFS_PM_FORK */ 127 m.VFS_PM_REGID = -1; /* Not used by VFS_PM_FORK */ 128 129 tell_vfs(rmc, &m); 130 131 /* Tell the tracer, if any, about the new child */ 132 if (rmc->mp_tracer != NO_TRACER) 133 sig_proc(rmc, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */); 134 135 /* Do not reply until VFS is ready to process the fork 136 * request 137 */ 138 return SUSPEND; 139 } 140 141 /*===========================================================================* 142 * do_srv_fork * 143 *===========================================================================*/ 144 int do_srv_fork() 145 { 146 /* The process pointed to by 'mp' has forked. Create a child process. */ 147 register struct mproc *rmp; /* pointer to parent */ 148 register struct mproc *rmc; /* pointer to child */ 149 int s; 150 pid_t new_pid; 151 static unsigned int next_child = 0; 152 int i, n = 0; 153 endpoint_t child_ep; 154 message m; 155 156 /* Only RS is allowed to use srv_fork. */ 157 if (mp->mp_endpoint != RS_PROC_NR) 158 return EPERM; 159 160 /* If tables might fill up during FORK, don't even start since recovery half 161 * way through is such a nuisance. 162 */ 163 rmp = mp; 164 if ((procs_in_use == NR_PROCS) || 165 (procs_in_use >= NR_PROCS-LAST_FEW && rmp->mp_effuid != 0)) 166 { 167 printf("PM: warning, process table is full!\n"); 168 return(EAGAIN); 169 } 170 171 /* Find a slot in 'mproc' for the child process. A slot must exist. */ 172 do { 173 next_child = (next_child+1) % NR_PROCS; 174 n++; 175 } while((mproc[next_child].mp_flags & IN_USE) && n <= NR_PROCS); 176 if(n > NR_PROCS) 177 panic("do_fork can't find child slot"); 178 if(next_child >= NR_PROCS || (mproc[next_child].mp_flags & IN_USE)) 179 panic("do_fork finds wrong child slot: %d", next_child); 180 181 if((s=vm_fork(rmp->mp_endpoint, next_child, &child_ep)) != OK) { 182 return s; 183 } 184 185 rmc = &mproc[next_child]; 186 /* Set up the child and its memory map; copy its 'mproc' slot from parent. */ 187 procs_in_use++; 188 *rmc = *rmp; /* copy parent's process slot to child's */ 189 rmc->mp_sigact = mpsigact[next_child]; /* restore mp_sigact ptr */ 190 memcpy(rmc->mp_sigact, rmp->mp_sigact, sizeof(mpsigact[next_child])); 191 rmc->mp_parent = who_p; /* record child's parent */ 192 if (!(rmc->mp_trace_flags & TO_TRACEFORK)) { 193 rmc->mp_tracer = NO_TRACER; /* no tracer attached */ 194 rmc->mp_trace_flags = 0; 195 (void) sigemptyset(&rmc->mp_sigtrace); 196 } 197 /* inherit only these flags */ 198 rmc->mp_flags &= (IN_USE|PRIV_PROC|DELAY_CALL); 199 rmc->mp_child_utime = 0; /* reset administration */ 200 rmc->mp_child_stime = 0; /* reset administration */ 201 rmc->mp_exitstatus = 0; 202 rmc->mp_sigstatus = 0; 203 rmc->mp_endpoint = child_ep; /* passed back by VM */ 204 rmc->mp_realuid = m_in.m_lsys_pm_srv_fork.uid; 205 rmc->mp_effuid = m_in.m_lsys_pm_srv_fork.uid; 206 rmc->mp_svuid = m_in.m_lsys_pm_srv_fork.uid; 207 rmc->mp_realgid = m_in.m_lsys_pm_srv_fork.gid; 208 rmc->mp_effgid = m_in.m_lsys_pm_srv_fork.gid; 209 rmc->mp_svgid = m_in.m_lsys_pm_srv_fork.gid; 210 for (i = 0; i < NR_ITIMERS; i++) 211 rmc->mp_interval[i] = 0; /* reset timer intervals */ 212 rmc->mp_started = getticks(); /* remember start time, for ps(1) */ 213 214 assert(rmc->mp_eventsub == NO_EVENTSUB); 215 216 /* Find a free pid for the child and put it in the table. */ 217 new_pid = get_free_pid(); 218 rmc->mp_pid = new_pid; /* assign pid to child */ 219 220 memset(&m, 0, sizeof(m)); 221 m.m_type = VFS_PM_SRV_FORK; 222 m.VFS_PM_ENDPT = rmc->mp_endpoint; 223 m.VFS_PM_PENDPT = rmp->mp_endpoint; 224 m.VFS_PM_CPID = rmc->mp_pid; 225 m.VFS_PM_REUID = m_in.m_lsys_pm_srv_fork.uid; 226 m.VFS_PM_REGID = m_in.m_lsys_pm_srv_fork.gid; 227 228 tell_vfs(rmc, &m); 229 230 /* Tell the tracer, if any, about the new child */ 231 if (rmc->mp_tracer != NO_TRACER) 232 sig_proc(rmc, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */); 233 234 /* Wakeup the newly created process */ 235 reply(rmc-mproc, OK); 236 237 return rmc->mp_pid; 238 } 239 240 /*===========================================================================* 241 * do_exit * 242 *===========================================================================*/ 243 int do_exit() 244 { 245 /* Perform the exit(status) system call. The real work is done by exit_proc(), 246 * which is also called when a process is killed by a signal. System processes 247 * do not use PM's exit() to terminate. If they try to, we warn the user 248 * and send a SIGKILL signal to the system process. 249 */ 250 if(mp->mp_flags & PRIV_PROC) { 251 printf("PM: system process %d (%s) tries to exit(), sending SIGKILL\n", 252 mp->mp_endpoint, mp->mp_name); 253 sys_kill(mp->mp_endpoint, SIGKILL); 254 } 255 else { 256 exit_proc(mp, m_in.m_lc_pm_exit.status, FALSE /*dump_core*/); 257 } 258 return(SUSPEND); /* can't communicate from beyond the grave */ 259 } 260 261 /*===========================================================================* 262 * exit_proc * 263 *===========================================================================*/ 264 void exit_proc(rmp, exit_status, dump_core) 265 register struct mproc *rmp; /* pointer to the process to be terminated */ 266 int exit_status; /* the process' exit status (for parent) */ 267 int dump_core; /* flag indicating whether to dump core */ 268 { 269 /* A process is done. Release most of the process' possessions. If its 270 * parent is waiting, release the rest, else keep the process slot and 271 * become a zombie. 272 */ 273 register int proc_nr, proc_nr_e; 274 int r; 275 pid_t procgrp; 276 clock_t user_time, sys_time; 277 message m; 278 279 /* Do not create core files for set uid execution */ 280 if (dump_core && rmp->mp_realuid != rmp->mp_effuid) 281 dump_core = FALSE; 282 283 /* System processes are destroyed before informing VFS, meaning that VFS can 284 * not get their CPU state, so we can't generate a coredump for them either. 285 */ 286 if (dump_core && (rmp->mp_flags & PRIV_PROC)) 287 dump_core = FALSE; 288 289 proc_nr = (int) (rmp - mproc); /* get process slot number */ 290 proc_nr_e = rmp->mp_endpoint; 291 292 /* Remember a session leader's process group. */ 293 procgrp = (rmp->mp_pid == mp->mp_procgrp) ? mp->mp_procgrp : 0; 294 295 /* If the exited process has a timer pending, kill it. */ 296 if (rmp->mp_flags & ALARM_ON) set_alarm(rmp, (clock_t) 0); 297 298 /* Do accounting: fetch usage times and save with dead child process. 299 * POSIX forbids accumulation at parent until child has been waited for. 300 */ 301 if((r=sys_times(proc_nr_e, &user_time, &sys_time, NULL, NULL)) != OK) 302 panic("exit_proc: sys_times failed: %d", r); 303 rmp->mp_child_utime += user_time; /* add user time */ 304 rmp->mp_child_stime += sys_time; /* add system time */ 305 306 /* Tell the kernel the process is no longer runnable to prevent it from 307 * being scheduled in between the following steps. Then tell VFS that it 308 * the process has exited and finally, clean up the process at the kernel. 309 * This order is important so that VFS can tell drivers to cancel requests 310 * such as copying to/ from the exiting process, before it is gone. 311 */ 312 /* If the process is not yet stopped, we force a stop here. This means that 313 * the process may still have a delay call pending. For this reason, the main 314 * message loop discards requests from exiting processes. 315 * 316 * TODO: make the kernel discard delayed calls upon forced stops for exits, 317 * so that no service needs to deal with this. Right now it appears that the 318 * only thing preventing problems with other services is the fact that 319 * regular messages are prioritized over asynchronous messages. 320 */ 321 if (!(rmp->mp_flags & PROC_STOPPED)) { 322 if ((r = sys_stop(proc_nr_e)) != OK) /* stop the process */ 323 panic("sys_stop failed: %d", r); 324 rmp->mp_flags |= PROC_STOPPED; 325 } 326 327 if((r=vm_willexit(proc_nr_e)) != OK) { 328 panic("exit_proc: vm_willexit failed: %d", r); 329 } 330 331 if (proc_nr_e == INIT_PROC_NR) 332 { 333 printf("PM: INIT died with exit status %d; showing stacktrace\n", exit_status); 334 sys_diagctl_stacktrace(proc_nr_e); 335 return; 336 } 337 if (proc_nr_e == VFS_PROC_NR) 338 { 339 panic("exit_proc: VFS died: %d", r); 340 } 341 342 /* Tell VFS, and after that any matching process event subscribers, about the 343 * exiting process. 344 */ 345 memset(&m, 0, sizeof(m)); 346 m.m_type = dump_core ? VFS_PM_DUMPCORE : VFS_PM_EXIT; 347 m.VFS_PM_ENDPT = rmp->mp_endpoint; 348 349 if (dump_core) { 350 m.VFS_PM_TERM_SIG = rmp->mp_sigstatus; 351 m.VFS_PM_PATH = rmp->mp_name; 352 } 353 354 tell_vfs(rmp, &m); 355 356 if (rmp->mp_flags & PRIV_PROC) 357 { 358 /* Destroy system processes without waiting for VFS. This is 359 * needed because the system process might be a block device 360 * driver that VFS is blocked waiting on. 361 */ 362 if((r= sys_clear(rmp->mp_endpoint)) != OK) 363 panic("exit_proc: sys_clear failed: %d", r); 364 } 365 366 /* Clean up most of the flags describing the process's state before the exit, 367 * and mark it as exiting. 368 */ 369 rmp->mp_flags &= (IN_USE|VFS_CALL|PRIV_PROC|TRACE_EXIT|PROC_STOPPED); 370 rmp->mp_flags |= EXITING; 371 372 /* Keep the process around until VFS is finished with it. */ 373 374 rmp->mp_exitstatus = (char) exit_status; 375 376 /* For normal exits, try to notify the parent as soon as possible. 377 * For core dumps, notify the parent only once the core dump has been made. 378 */ 379 if (!dump_core) 380 zombify(rmp); 381 382 /* If the process has children, disinherit them. INIT is the new parent. */ 383 for (rmp = &mproc[0]; rmp < &mproc[NR_PROCS]; rmp++) { 384 if (!(rmp->mp_flags & IN_USE)) continue; 385 if (rmp->mp_tracer == proc_nr) { 386 /* This child's tracer died. Do something sensible. */ 387 tracer_died(rmp); 388 } 389 if (rmp->mp_parent == proc_nr) { 390 /* 'rmp' now points to a child to be disinherited. */ 391 rmp->mp_parent = INIT_PROC_NR; 392 393 /* If the process is making a VFS call, remember that we set 394 * a new parent. This prevents FORK from replying to the wrong 395 * parent upon completion. 396 */ 397 if (rmp->mp_flags & VFS_CALL) 398 rmp->mp_flags |= NEW_PARENT; 399 400 /* Notify new parent. */ 401 if (rmp->mp_flags & ZOMBIE) 402 check_parent(rmp, TRUE /*try_cleanup*/); 403 } 404 } 405 406 /* Send a hangup to the process' process group if it was a session leader. */ 407 if (procgrp != 0) check_sig(-procgrp, SIGHUP, FALSE /* ksig */); 408 } 409 410 /*===========================================================================* 411 * exit_restart * 412 *===========================================================================*/ 413 void exit_restart(struct mproc *rmp) 414 { 415 /* VFS replied to our exit or coredump request. Perform the second half of the 416 * exit code. 417 */ 418 int r; 419 420 if((r = sched_stop(rmp->mp_scheduler, rmp->mp_endpoint)) != OK) { 421 /* If the scheduler refuses to give up scheduling, there is 422 * little we can do, except report it. This may cause problems 423 * later on, if this scheduler is asked to schedule another proc 424 * that has an endpoint->schedproc mapping identical to the proc 425 * we just tried to stop scheduling. 426 */ 427 printf("PM: The scheduler did not want to give up " 428 "scheduling %s, ret=%d.\n", rmp->mp_name, r); 429 } 430 431 /* sched_stop is either called when the process is exiting or it is 432 * being moved between schedulers. If it is being moved between 433 * schedulers, we need to set the mp_scheduler to NONE so that PM 434 * doesn't forward messages to the process' scheduler while being moved 435 * (such as sched_nice). */ 436 rmp->mp_scheduler = NONE; 437 438 /* For core dumps, now is the right time to try to contact the parent. */ 439 if (!(rmp->mp_flags & (TRACE_ZOMBIE | ZOMBIE | TOLD_PARENT))) 440 zombify(rmp); 441 442 if (!(rmp->mp_flags & PRIV_PROC)) 443 { 444 /* destroy the (user) process */ 445 if((r=sys_clear(rmp->mp_endpoint)) != OK) 446 panic("exit_restart: sys_clear failed: %d", r); 447 } 448 449 /* Release the memory occupied by the child. */ 450 if((r=vm_exit(rmp->mp_endpoint)) != OK) { 451 panic("exit_restart: vm_exit failed: %d", r); 452 } 453 454 if (rmp->mp_flags & TRACE_EXIT) 455 { 456 /* Wake up the tracer, completing the ptrace(T_EXIT) call */ 457 mproc[rmp->mp_tracer].mp_reply.m_pm_lc_ptrace.data = 0; 458 reply(rmp->mp_tracer, OK); 459 } 460 461 /* Clean up if the parent has collected the exit status */ 462 if (rmp->mp_flags & TOLD_PARENT) 463 cleanup(rmp); 464 } 465 466 /*===========================================================================* 467 * do_wait4 * 468 *===========================================================================*/ 469 int do_wait4() 470 { 471 /* A process wants to wait for a child to terminate. If a child is already 472 * waiting, go clean it up and let this WAIT4 call terminate. Otherwise, 473 * really wait. 474 * A process calling WAIT4 never gets a reply in the usual way at the end 475 * of the main loop (unless WNOHANG is set or no qualifying child exists). 476 * If a child has already exited, the routine tell_parent() sends the reply 477 * to awaken the caller. 478 */ 479 register struct mproc *rp; 480 vir_bytes addr; 481 int i, pidarg, options, children, waited_for; 482 483 /* Set internal variables. */ 484 pidarg = m_in.m_lc_pm_wait4.pid; /* 1st param */ 485 options = m_in.m_lc_pm_wait4.options; /* 3rd param */ 486 addr = m_in.m_lc_pm_wait4.addr; /* 4th param */ 487 if (pidarg == 0) pidarg = -mp->mp_procgrp; /* pidarg < 0 ==> proc grp */ 488 489 /* Is there a child waiting to be collected? At this point, pidarg != 0: 490 * pidarg > 0 means pidarg is pid of a specific process to wait for 491 * pidarg == -1 means wait for any child 492 * pidarg < -1 means wait for any child whose process group = -pidarg 493 */ 494 children = 0; 495 for (rp = &mproc[0]; rp < &mproc[NR_PROCS]; rp++) { 496 if ((rp->mp_flags & (IN_USE | TOLD_PARENT)) != IN_USE) continue; 497 if (rp->mp_parent != who_p && rp->mp_tracer != who_p) continue; 498 if (rp->mp_parent != who_p && (rp->mp_flags & ZOMBIE)) continue; 499 500 /* The value of pidarg determines which children qualify. */ 501 if (pidarg > 0 && pidarg != rp->mp_pid) continue; 502 if (pidarg < -1 && -pidarg != rp->mp_procgrp) continue; 503 504 children++; /* this child is acceptable */ 505 506 if (rp->mp_tracer == who_p) { 507 if (rp->mp_flags & TRACE_ZOMBIE) { 508 /* Traced child meets the pid test and has exited. */ 509 tell_tracer(rp); 510 check_parent(rp, TRUE /*try_cleanup*/); 511 return(SUSPEND); 512 } 513 if (rp->mp_flags & TRACE_STOPPED) { 514 /* This child meets the pid test and is being traced. 515 * Deliver a signal to the tracer, if any. 516 */ 517 for (i = 1; i < _NSIG; i++) { 518 if (sigismember(&rp->mp_sigtrace, i)) { 519 /* TODO: rusage support */ 520 521 sigdelset(&rp->mp_sigtrace, i); 522 523 mp->mp_reply.m_pm_lc_wait4.status = 524 W_STOPCODE(i); 525 return(rp->mp_pid); 526 } 527 } 528 } 529 } 530 531 if (rp->mp_parent == who_p) { 532 if (rp->mp_flags & ZOMBIE) { 533 /* This child meets the pid test and has exited. */ 534 waited_for = tell_parent(rp, addr); 535 536 if (waited_for && 537 !(rp->mp_flags & (VFS_CALL | EVENT_CALL))) 538 cleanup(rp); 539 return(SUSPEND); 540 } 541 } 542 } 543 544 /* No qualifying child has exited. Wait for one, unless none exists. */ 545 if (children > 0) { 546 /* At least 1 child meets the pid test exists, but has not exited. */ 547 if (options & WNOHANG) { 548 return(0); /* parent does not want to wait */ 549 } 550 mp->mp_flags |= WAITING; /* parent wants to wait */ 551 mp->mp_wpid = (pid_t) pidarg; /* save pid for later */ 552 mp->mp_waddr = addr; /* save rusage addr for later */ 553 return(SUSPEND); /* do not reply, let it wait */ 554 } else { 555 /* No child even meets the pid test. Return error immediately. */ 556 return(ECHILD); /* no - parent has no children */ 557 } 558 } 559 560 /*===========================================================================* 561 * wait_test * 562 *===========================================================================*/ 563 int wait_test(rmp, child) 564 struct mproc *rmp; /* process that may be waiting */ 565 struct mproc *child; /* process that may be waited for */ 566 { 567 /* See if a parent or tracer process is waiting for a child process. 568 * A tracer is considered to be a pseudo-parent. 569 */ 570 int parent_waiting, right_child; 571 pid_t pidarg; 572 573 pidarg = rmp->mp_wpid; /* who's being waited for? */ 574 parent_waiting = rmp->mp_flags & WAITING; 575 right_child = /* child meets one of the 3 tests? */ 576 (pidarg == -1 || pidarg == child->mp_pid || 577 -pidarg == child->mp_procgrp); 578 579 return (parent_waiting && right_child); 580 } 581 582 /*===========================================================================* 583 * zombify * 584 *===========================================================================*/ 585 static void zombify(rmp) 586 struct mproc *rmp; 587 { 588 /* Zombify a process. First check if the exiting process is traced by a process 589 * other than its parent; if so, the tracer must be notified about the exit 590 * first. Once that is done, the real parent may be notified about the exit of 591 * its child. 592 */ 593 struct mproc *t_mp; 594 595 if (rmp->mp_flags & (TRACE_ZOMBIE | ZOMBIE)) 596 panic("zombify: process was already a zombie"); 597 598 /* See if we have to notify a tracer process first. */ 599 if (rmp->mp_tracer != NO_TRACER && rmp->mp_tracer != rmp->mp_parent) { 600 rmp->mp_flags |= TRACE_ZOMBIE; 601 602 t_mp = &mproc[rmp->mp_tracer]; 603 604 /* Do not bother sending SIGCHLD signals to tracers. */ 605 if (!wait_test(t_mp, rmp)) 606 return; 607 608 tell_tracer(rmp); 609 } 610 else { 611 rmp->mp_flags |= ZOMBIE; 612 } 613 614 /* No tracer, or tracer is parent, or tracer has now been notified. */ 615 check_parent(rmp, FALSE /*try_cleanup*/); 616 } 617 618 /*===========================================================================* 619 * check_parent * 620 *===========================================================================*/ 621 static void check_parent(child, try_cleanup) 622 struct mproc *child; /* tells which process is exiting */ 623 int try_cleanup; /* clean up the child when done? */ 624 { 625 /* We would like to inform the parent of an exiting child about the child's 626 * death. If the parent is waiting for the child, tell it immediately; 627 * otherwise, send it a SIGCHLD signal. 628 * 629 * Note that we may call this function twice on a single child; first with 630 * its original parent, later (if the parent died) with INIT as its parent. 631 */ 632 struct mproc *p_mp; 633 634 p_mp = &mproc[child->mp_parent]; 635 636 if (p_mp->mp_flags & EXITING) { 637 /* This may trigger if the child of a dead parent dies. The child will 638 * be assigned to INIT and rechecked shortly after. Do nothing. 639 */ 640 } 641 else if (wait_test(p_mp, child)) { 642 if (!tell_parent(child, p_mp->mp_waddr)) 643 try_cleanup = FALSE; /* child is still there */ 644 645 /* The 'try_cleanup' flag merely saves us from having to be really 646 * careful with statement ordering in exit_proc() and exit_restart(). 647 */ 648 if (try_cleanup && !(child->mp_flags & (VFS_CALL | EVENT_CALL))) 649 cleanup(child); 650 } 651 else { 652 /* Parent is not waiting. */ 653 sig_proc(p_mp, SIGCHLD, TRUE /*trace*/, FALSE /* ksig */); 654 } 655 } 656 657 /*===========================================================================* 658 * tell_parent * 659 *===========================================================================*/ 660 static int tell_parent(struct mproc *child, vir_bytes addr) 661 { 662 /* Tell the parent of the given process that it has terminated, by satisfying 663 * the parent's ongoing wait4() call. If the parent has requested the child 664 * tree's resource usage, copy that information out first. The copy may fail; 665 * in that case, the parent's wait4() call will return with an error, but the 666 * child will remain a zombie. Return TRUE if the child is cleaned up, or 667 * FALSE if the child is still a zombie. 668 */ 669 struct rusage r_usage; 670 int mp_parent; 671 struct mproc *parent; 672 int r; 673 674 mp_parent= child->mp_parent; 675 if (mp_parent <= 0) 676 panic("tell_parent: bad value in mp_parent: %d", mp_parent); 677 if(!(child->mp_flags & ZOMBIE)) 678 panic("tell_parent: child not a zombie"); 679 if(child->mp_flags & TOLD_PARENT) 680 panic("tell_parent: telling parent again"); 681 parent = &mproc[mp_parent]; 682 683 /* See if we need to report resource usage to the parent. */ 684 if (addr) { 685 /* We report only user and system times for now. TODO: support other 686 * fields, although this is tricky since the child process is already 687 * gone as far as the kernel and other services are concerned.. 688 */ 689 memset(&r_usage, 0, sizeof(r_usage)); 690 set_rusage_times(&r_usage, child->mp_child_utime, 691 child->mp_child_stime); 692 693 if ((r = sys_datacopy(SELF, (vir_bytes)&r_usage, parent->mp_endpoint, 694 addr, sizeof(r_usage))) != OK) { 695 reply(child->mp_parent, r); 696 697 return FALSE; /* copy error - the child is still there */ 698 } 699 } 700 701 /* Wake up the parent by sending the reply message. */ 702 parent->mp_reply.m_pm_lc_wait4.status = 703 W_EXITCODE(child->mp_exitstatus, child->mp_sigstatus); 704 reply(child->mp_parent, child->mp_pid); 705 parent->mp_flags &= ~WAITING; /* parent no longer waiting */ 706 child->mp_flags &= ~ZOMBIE; /* child no longer a zombie */ 707 child->mp_flags |= TOLD_PARENT; /* avoid informing parent twice */ 708 709 /* Now that the child has been waited for, accumulate the times of the 710 * terminated child process at the parent. 711 */ 712 parent->mp_child_utime += child->mp_child_utime; 713 parent->mp_child_stime += child->mp_child_stime; 714 715 return TRUE; /* child has been waited for */ 716 } 717 718 /*===========================================================================* 719 * tell_tracer * 720 *===========================================================================*/ 721 static void tell_tracer(child) 722 struct mproc *child; /* tells which process is exiting */ 723 { 724 int mp_tracer; 725 struct mproc *tracer; 726 727 mp_tracer = child->mp_tracer; 728 if (mp_tracer <= 0) 729 panic("tell_tracer: bad value in mp_tracer: %d", mp_tracer); 730 if(!(child->mp_flags & TRACE_ZOMBIE)) 731 panic("tell_tracer: child not a zombie"); 732 tracer = &mproc[mp_tracer]; 733 734 /* TODO: rusage support */ 735 736 tracer->mp_reply.m_pm_lc_wait4.status = 737 W_EXITCODE(child->mp_exitstatus, (child->mp_sigstatus & 0377)); 738 reply(child->mp_tracer, child->mp_pid); 739 tracer->mp_flags &= ~WAITING; /* tracer no longer waiting */ 740 child->mp_flags &= ~TRACE_ZOMBIE; /* child no longer zombie to tracer */ 741 child->mp_flags |= ZOMBIE; /* child is now zombie to parent */ 742 } 743 744 /*===========================================================================* 745 * tracer_died * 746 *===========================================================================*/ 747 static void tracer_died(child) 748 struct mproc *child; /* process being traced */ 749 { 750 /* The process that was tracing the given child, has died for some reason. 751 * This is really the tracer's fault, but we can't let INIT deal with this. 752 */ 753 754 child->mp_tracer = NO_TRACER; 755 child->mp_flags &= ~TRACE_EXIT; 756 757 /* If the tracer died while the child was running or stopped, we have no 758 * idea what state the child is in. Avoid a trainwreck, by killing the child. 759 * Note that this may cause cascading exits. 760 */ 761 if (!(child->mp_flags & EXITING)) { 762 sig_proc(child, SIGKILL, TRUE /*trace*/, FALSE /* ksig */); 763 764 return; 765 } 766 767 /* If the tracer died while the child was telling it about its own death, 768 * forget about the tracer and notify the real parent instead. 769 */ 770 if (child->mp_flags & TRACE_ZOMBIE) { 771 child->mp_flags &= ~TRACE_ZOMBIE; 772 child->mp_flags |= ZOMBIE; 773 774 check_parent(child, TRUE /*try_cleanup*/); 775 } 776 } 777 778 /*===========================================================================* 779 * cleanup * 780 *===========================================================================*/ 781 static void cleanup(rmp) 782 register struct mproc *rmp; /* tells which process is exiting */ 783 { 784 /* Release the process table entry and reinitialize some field. */ 785 rmp->mp_pid = 0; 786 rmp->mp_flags = 0; 787 rmp->mp_child_utime = 0; 788 rmp->mp_child_stime = 0; 789 procs_in_use--; 790 } 791 792