1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Kenneth Almquist. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $Id: jobs.c,v 1.6 1996/09/03 13:35:09 peter Exp $ 37 */ 38 39 #ifndef lint 40 static char sccsid[] = "@(#)jobs.c 8.5 (Berkeley) 5/4/95"; 41 #endif /* not lint */ 42 43 #include <fcntl.h> 44 #include <signal.h> 45 #include <errno.h> 46 #include <unistd.h> 47 #include <stdlib.h> 48 #include <sys/types.h> 49 #include <sys/param.h> 50 #ifdef BSD 51 #include <sys/wait.h> 52 #include <sys/time.h> 53 #include <sys/resource.h> 54 #endif 55 #include <sys/ioctl.h> 56 57 #include "shell.h" 58 #if JOBS 59 #ifdef OLD_TTY_DRIVER 60 #include "sgtty.h" 61 #else 62 #include <termios.h> 63 #endif 64 #undef CEOF /* syntax.h redefines this */ 65 #endif 66 #include "redir.h" 67 #include "show.h" 68 #include "main.h" 69 #include "parser.h" 70 #include "nodes.h" 71 #include "jobs.h" 72 #include "options.h" 73 #include "trap.h" 74 #include "syntax.h" 75 #include "input.h" 76 #include "output.h" 77 #include "memalloc.h" 78 #include "error.h" 79 #include "mystring.h" 80 81 82 struct job *jobtab; /* array of jobs */ 83 int njobs; /* size of array */ 84 MKINIT short backgndpid = -1; /* pid of last background process */ 85 #if JOBS 86 int initialpgrp; /* pgrp of shell on invocation */ 87 short curjob; /* current job */ 88 #endif 89 90 STATIC void restartjob __P((struct job *)); 91 STATIC void freejob __P((struct job *)); 92 STATIC struct job *getjob __P((char *)); 93 STATIC int dowait __P((int, struct job *)); 94 STATIC int onsigchild __P((void)); 95 STATIC int waitproc __P((int, int *)); 96 STATIC void cmdtxt __P((union node *)); 97 STATIC void cmdputs __P((char *)); 98 99 100 /* 101 * Turn job control on and off. 102 * 103 * Note: This code assumes that the third arg to ioctl is a character 104 * pointer, which is true on Berkeley systems but not System V. Since 105 * System V doesn't have job control yet, this isn't a problem now. 106 */ 107 108 MKINIT int jobctl; 109 110 void 111 setjobctl(on) 112 int on; 113 { 114 #ifdef OLD_TTY_DRIVER 115 int ldisc; 116 #endif 117 118 if (on == jobctl || rootshell == 0) 119 return; 120 if (on) { 121 do { /* while we are in the background */ 122 if (ioctl(2, TIOCGPGRP, (char *)&initialpgrp) < 0) { 123 out2str("sh: can't access tty; job control turned off\n"); 124 mflag = 0; 125 return; 126 } 127 if (initialpgrp == -1) 128 initialpgrp = getpgrp(); 129 else if (initialpgrp != getpgrp()) { 130 killpg(initialpgrp, SIGTTIN); 131 continue; 132 } 133 } while (0); 134 #ifdef OLD_TTY_DRIVER 135 if (ioctl(2, TIOCGETD, (char *)&ldisc) < 0 || ldisc != NTTYDISC) { 136 out2str("sh: need new tty driver to run job control; job control turned off\n"); 137 mflag = 0; 138 return; 139 } 140 #endif 141 setsignal(SIGTSTP); 142 setsignal(SIGTTOU); 143 setsignal(SIGTTIN); 144 setpgid(0, rootpid); 145 ioctl(2, TIOCSPGRP, (char *)&rootpid); 146 } else { /* turning job control off */ 147 setpgid(0, initialpgrp); 148 ioctl(2, TIOCSPGRP, (char *)&initialpgrp); 149 setsignal(SIGTSTP); 150 setsignal(SIGTTOU); 151 setsignal(SIGTTIN); 152 } 153 jobctl = on; 154 } 155 156 157 #ifdef mkinit 158 INCLUDE <stdlib.h> 159 160 SHELLPROC { 161 backgndpid = -1; 162 #if JOBS 163 jobctl = 0; 164 #endif 165 } 166 167 #endif 168 169 170 171 #if JOBS 172 int 173 fgcmd(argc, argv) 174 int argc; 175 char **argv; 176 { 177 struct job *jp; 178 int pgrp; 179 int status; 180 181 jp = getjob(argv[1]); 182 if (jp->jobctl == 0) 183 error("job not created under job control"); 184 pgrp = jp->ps[0].pid; 185 ioctl(2, TIOCSPGRP, (char *)&pgrp); 186 restartjob(jp); 187 INTOFF; 188 status = waitforjob(jp); 189 INTON; 190 return status; 191 } 192 193 194 int 195 bgcmd(argc, argv) 196 int argc; 197 char **argv; 198 { 199 struct job *jp; 200 201 do { 202 jp = getjob(*++argv); 203 if (jp->jobctl == 0) 204 error("job not created under job control"); 205 restartjob(jp); 206 } while (--argc > 1); 207 return 0; 208 } 209 210 211 STATIC void 212 restartjob(jp) 213 struct job *jp; 214 { 215 struct procstat *ps; 216 int i; 217 218 if (jp->state == JOBDONE) 219 return; 220 INTOFF; 221 killpg(jp->ps[0].pid, SIGCONT); 222 for (ps = jp->ps, i = jp->nprocs ; --i >= 0 ; ps++) { 223 if ((ps->status & 0377) == 0177) { 224 ps->status = -1; 225 jp->state = 0; 226 } 227 } 228 INTON; 229 } 230 #endif 231 232 233 int 234 jobscmd(argc, argv) 235 int argc; 236 char **argv; 237 { 238 showjobs(0); 239 return 0; 240 } 241 242 243 /* 244 * Print a list of jobs. If "change" is nonzero, only print jobs whose 245 * statuses have changed since the last call to showjobs. 246 * 247 * If the shell is interrupted in the process of creating a job, the 248 * result may be a job structure containing zero processes. Such structures 249 * will be freed here. 250 */ 251 252 void 253 showjobs(change) 254 int change; 255 { 256 int jobno; 257 int procno; 258 int i; 259 struct job *jp; 260 struct procstat *ps; 261 int col; 262 char s[64]; 263 264 TRACE(("showjobs(%d) called\n", change)); 265 while (dowait(0, (struct job *)NULL) > 0); 266 for (jobno = 1, jp = jobtab ; jobno <= njobs ; jobno++, jp++) { 267 if (! jp->used) 268 continue; 269 if (jp->nprocs == 0) { 270 freejob(jp); 271 continue; 272 } 273 if (change && ! jp->changed) 274 continue; 275 procno = jp->nprocs; 276 for (ps = jp->ps ; ; ps++) { /* for each process */ 277 if (ps == jp->ps) 278 fmtstr(s, 64, "[%d] %d ", jobno, ps->pid); 279 else 280 fmtstr(s, 64, " %d ", ps->pid); 281 out1str(s); 282 col = strlen(s); 283 s[0] = '\0'; 284 if (ps->status == -1) { 285 /* don't print anything */ 286 } else if ((ps->status & 0xFF) == 0) { 287 fmtstr(s, 64, "Exit %d", ps->status >> 8); 288 } else { 289 i = ps->status; 290 #if JOBS 291 if ((i & 0xFF) == 0177) 292 i >>= 8; 293 #endif 294 if ((i & 0x7F) < NSIG && sys_siglist[i & 0x7F]) 295 scopy(sys_siglist[i & 0x7F], s); 296 else 297 fmtstr(s, 64, "Signal %d", i & 0x7F); 298 if (i & 0x80) 299 strcat(s, " (core dumped)"); 300 } 301 out1str(s); 302 col += strlen(s); 303 do { 304 out1c(' '); 305 col++; 306 } while (col < 30); 307 out1str(ps->cmd); 308 out1c('\n'); 309 if (--procno <= 0) 310 break; 311 } 312 jp->changed = 0; 313 if (jp->state == JOBDONE) { 314 freejob(jp); 315 } 316 } 317 } 318 319 320 /* 321 * Mark a job structure as unused. 322 */ 323 324 STATIC void 325 freejob(jp) 326 struct job *jp; 327 { 328 struct procstat *ps; 329 int i; 330 331 INTOFF; 332 for (i = jp->nprocs, ps = jp->ps ; --i >= 0 ; ps++) { 333 if (ps->cmd != nullstr) 334 ckfree(ps->cmd); 335 } 336 if (jp->ps != &jp->ps0) 337 ckfree(jp->ps); 338 jp->used = 0; 339 #if JOBS 340 if (curjob == jp - jobtab + 1) 341 curjob = 0; 342 #endif 343 INTON; 344 } 345 346 347 348 int 349 waitcmd(argc, argv) 350 int argc; 351 char **argv; 352 { 353 struct job *job; 354 int status; 355 struct job *jp; 356 357 if (argc > 1) { 358 job = getjob(argv[1]); 359 } else { 360 job = NULL; 361 } 362 for (;;) { /* loop until process terminated or stopped */ 363 if (job != NULL) { 364 if (job->state) { 365 status = job->ps[job->nprocs - 1].status; 366 if ((status & 0xFF) == 0) 367 status = status >> 8 & 0xFF; 368 #if JOBS 369 else if ((status & 0xFF) == 0177) 370 status = (status >> 8 & 0x7F) + 128; 371 #endif 372 else 373 status = (status & 0x7F) + 128; 374 if (! iflag) 375 freejob(job); 376 return status; 377 } 378 } else { 379 for (jp = jobtab ; ; jp++) { 380 if (jp >= jobtab + njobs) { /* no running procs */ 381 return 0; 382 } 383 if (jp->used && jp->state == 0) 384 break; 385 } 386 } 387 dowait(1, (struct job *)NULL); 388 } 389 } 390 391 392 393 int 394 jobidcmd(argc, argv) 395 int argc; 396 char **argv; 397 { 398 struct job *jp; 399 int i; 400 401 jp = getjob(argv[1]); 402 for (i = 0 ; i < jp->nprocs ; ) { 403 out1fmt("%d", jp->ps[i].pid); 404 out1c(++i < jp->nprocs? ' ' : '\n'); 405 } 406 return 0; 407 } 408 409 410 411 /* 412 * Convert a job name to a job structure. 413 */ 414 415 STATIC struct job * 416 getjob(name) 417 char *name; 418 { 419 int jobno; 420 register struct job *jp; 421 int pid; 422 int i; 423 424 if (name == NULL) { 425 #if JOBS 426 currentjob: 427 if ((jobno = curjob) == 0 || jobtab[jobno - 1].used == 0) 428 error("No current job"); 429 return &jobtab[jobno - 1]; 430 #else 431 error("No current job"); 432 #endif 433 } else if (name[0] == '%') { 434 if (is_digit(name[1])) { 435 jobno = number(name + 1); 436 if (jobno > 0 && jobno <= njobs 437 && jobtab[jobno - 1].used != 0) 438 return &jobtab[jobno - 1]; 439 #if JOBS 440 } else if (name[1] == '%' && name[2] == '\0') { 441 goto currentjob; 442 #endif 443 } else { 444 register struct job *found = NULL; 445 for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) { 446 if (jp->used && jp->nprocs > 0 447 && prefix(name + 1, jp->ps[0].cmd)) { 448 if (found) 449 error("%s: ambiguous", name); 450 found = jp; 451 } 452 } 453 if (found) 454 return found; 455 } 456 } else if (is_number(name)) { 457 pid = number(name); 458 for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) { 459 if (jp->used && jp->nprocs > 0 460 && jp->ps[jp->nprocs - 1].pid == pid) 461 return jp; 462 } 463 } 464 error("No such job: %s", name); 465 /*NOTREACHED*/ 466 return NULL; 467 } 468 469 470 471 /* 472 * Return a new job structure, 473 */ 474 475 struct job * 476 makejob(node, nprocs) 477 union node *node; 478 int nprocs; 479 { 480 int i; 481 struct job *jp; 482 483 for (i = njobs, jp = jobtab ; ; jp++) { 484 if (--i < 0) { 485 INTOFF; 486 if (njobs == 0) { 487 jobtab = ckmalloc(4 * sizeof jobtab[0]); 488 } else { 489 struct job *ojp; 490 491 jp = ckmalloc((njobs + 4) * sizeof jobtab[0]); 492 for (i = njobs, ojp = jobtab; --i >= 0; 493 jp++, ojp++) 494 if (ojp->ps == &ojp->ps0) 495 ojp->ps = &jp->ps0; 496 jp -= njobs; 497 memcpy(jp, jobtab, njobs * sizeof jp[0]); 498 ckfree(jobtab); 499 jobtab = jp; 500 } 501 jp = jobtab + njobs; 502 for (i = 4 ; --i >= 0 ; jobtab[njobs++].used = 0); 503 INTON; 504 break; 505 } 506 if (jp->used == 0) 507 break; 508 } 509 INTOFF; 510 jp->state = 0; 511 jp->used = 1; 512 jp->changed = 0; 513 jp->nprocs = 0; 514 #if JOBS 515 jp->jobctl = jobctl; 516 #endif 517 if (nprocs > 1) { 518 jp->ps = ckmalloc(nprocs * sizeof (struct procstat)); 519 } else { 520 jp->ps = &jp->ps0; 521 } 522 INTON; 523 TRACE(("makejob(0x%lx, %d) returns %%%d\n", (long)node, nprocs, 524 jp - jobtab + 1)); 525 return jp; 526 } 527 528 529 /* 530 * Fork of a subshell. If we are doing job control, give the subshell its 531 * own process group. Jp is a job structure that the job is to be added to. 532 * N is the command that will be evaluated by the child. Both jp and n may 533 * be NULL. The mode parameter can be one of the following: 534 * FORK_FG - Fork off a foreground process. 535 * FORK_BG - Fork off a background process. 536 * FORK_NOJOB - Like FORK_FG, but don't give the process its own 537 * process group even if job control is on. 538 * 539 * When job control is turned off, background processes have their standard 540 * input redirected to /dev/null (except for the second and later processes 541 * in a pipeline). 542 */ 543 544 int 545 forkshell(jp, n, mode) 546 union node *n; 547 struct job *jp; 548 int mode; 549 { 550 int pid; 551 int pgrp; 552 553 TRACE(("forkshell(%%%d, 0x%lx, %d) called\n", jp - jobtab, (long)n, 554 mode)); 555 INTOFF; 556 pid = fork(); 557 if (pid == -1) { 558 TRACE(("Fork failed, errno=%d\n", errno)); 559 INTON; 560 error("Cannot fork"); 561 } 562 if (pid == 0) { 563 struct job *p; 564 int wasroot; 565 int i; 566 567 TRACE(("Child shell %d\n", getpid())); 568 wasroot = rootshell; 569 rootshell = 0; 570 for (i = njobs, p = jobtab ; --i >= 0 ; p++) 571 if (p->used) 572 freejob(p); 573 closescript(); 574 INTON; 575 clear_traps(); 576 #if JOBS 577 jobctl = 0; /* do job control only in root shell */ 578 if (wasroot && mode != FORK_NOJOB && mflag) { 579 if (jp == NULL || jp->nprocs == 0) 580 pgrp = getpid(); 581 else 582 pgrp = jp->ps[0].pid; 583 setpgid(0, pgrp); 584 if (mode == FORK_FG) { 585 /*** this causes superfluous TIOCSPGRPS ***/ 586 if (ioctl(2, TIOCSPGRP, (char *)&pgrp) < 0) 587 error("TIOCSPGRP failed, errno=%d", errno); 588 } 589 setsignal(SIGTSTP); 590 setsignal(SIGTTOU); 591 } else if (mode == FORK_BG) { 592 ignoresig(SIGINT); 593 ignoresig(SIGQUIT); 594 if ((jp == NULL || jp->nprocs == 0) && 595 ! fd0_redirected_p ()) { 596 close(0); 597 if (open("/dev/null", O_RDONLY) != 0) 598 error("Can't open /dev/null"); 599 } 600 } 601 #else 602 if (mode == FORK_BG) { 603 ignoresig(SIGINT); 604 ignoresig(SIGQUIT); 605 if ((jp == NULL || jp->nprocs == 0) && 606 ! fd0_redirected_p ()) { 607 close(0); 608 if (open("/dev/null", O_RDONLY) != 0) 609 error("Can't open /dev/null"); 610 } 611 } 612 #endif 613 if (wasroot && iflag) { 614 setsignal(SIGINT); 615 setsignal(SIGQUIT); 616 setsignal(SIGTERM); 617 } 618 return pid; 619 } 620 if (rootshell && mode != FORK_NOJOB && mflag) { 621 if (jp == NULL || jp->nprocs == 0) 622 pgrp = pid; 623 else 624 pgrp = jp->ps[0].pid; 625 setpgid(pid, pgrp); 626 } 627 if (mode == FORK_BG) 628 backgndpid = pid; /* set $! */ 629 if (jp) { 630 struct procstat *ps = &jp->ps[jp->nprocs++]; 631 ps->pid = pid; 632 ps->status = -1; 633 ps->cmd = nullstr; 634 if (iflag && rootshell && n) 635 ps->cmd = commandtext(n); 636 } 637 INTON; 638 TRACE(("In parent shell: child = %d\n", pid)); 639 return pid; 640 } 641 642 643 644 /* 645 * Wait for job to finish. 646 * 647 * Under job control we have the problem that while a child process is 648 * running interrupts generated by the user are sent to the child but not 649 * to the shell. This means that an infinite loop started by an inter- 650 * active user may be hard to kill. With job control turned off, an 651 * interactive user may place an interactive program inside a loop. If 652 * the interactive program catches interrupts, the user doesn't want 653 * these interrupts to also abort the loop. The approach we take here 654 * is to have the shell ignore interrupt signals while waiting for a 655 * forground process to terminate, and then send itself an interrupt 656 * signal if the child process was terminated by an interrupt signal. 657 * Unfortunately, some programs want to do a bit of cleanup and then 658 * exit on interrupt; unless these processes terminate themselves by 659 * sending a signal to themselves (instead of calling exit) they will 660 * confuse this approach. 661 */ 662 663 int 664 waitforjob(jp) 665 register struct job *jp; 666 { 667 #if JOBS 668 int mypgrp = getpgrp(); 669 #endif 670 int status; 671 int st; 672 673 INTOFF; 674 TRACE(("waitforjob(%%%d) called\n", jp - jobtab + 1)); 675 while (jp->state == 0) { 676 dowait(1, jp); 677 } 678 #if JOBS 679 if (jp->jobctl) { 680 if (ioctl(2, TIOCSPGRP, (char *)&mypgrp) < 0) 681 error("TIOCSPGRP failed, errno=%d", errno); 682 } 683 if (jp->state == JOBSTOPPED) 684 curjob = jp - jobtab + 1; 685 #endif 686 status = jp->ps[jp->nprocs - 1].status; 687 /* convert to 8 bits */ 688 if ((status & 0xFF) == 0) 689 st = status >> 8 & 0xFF; 690 #if JOBS 691 else if ((status & 0xFF) == 0177) 692 st = (status >> 8 & 0x7F) + 128; 693 #endif 694 else 695 st = (status & 0x7F) + 128; 696 if (! JOBS || jp->state == JOBDONE) 697 freejob(jp); 698 CLEAR_PENDING_INT; 699 if ((status & 0x7F) == SIGINT) 700 kill(getpid(), SIGINT); 701 INTON; 702 return st; 703 } 704 705 706 707 /* 708 * Wait for a process to terminate. 709 */ 710 711 STATIC int 712 dowait(block, job) 713 int block; 714 struct job *job; 715 { 716 int pid; 717 int status; 718 struct procstat *sp; 719 struct job *jp; 720 struct job *thisjob; 721 int done; 722 int stopped; 723 int core; 724 725 TRACE(("dowait(%d) called\n", block)); 726 do { 727 pid = waitproc(block, &status); 728 TRACE(("wait returns %d, status=%d\n", pid, status)); 729 } while (pid == -1 && errno == EINTR); 730 if (pid <= 0) 731 return pid; 732 INTOFF; 733 thisjob = NULL; 734 for (jp = jobtab ; jp < jobtab + njobs ; jp++) { 735 if (jp->used) { 736 done = 1; 737 stopped = 1; 738 for (sp = jp->ps ; sp < jp->ps + jp->nprocs ; sp++) { 739 if (sp->pid == -1) 740 continue; 741 if (sp->pid == pid) { 742 TRACE(("Changin status of proc %d from 0x%x to 0x%x\n", pid, sp->status, status)); 743 sp->status = status; 744 thisjob = jp; 745 } 746 if (sp->status == -1) 747 stopped = 0; 748 else if ((sp->status & 0377) == 0177) 749 done = 0; 750 } 751 if (stopped) { /* stopped or done */ 752 int state = done? JOBDONE : JOBSTOPPED; 753 if (jp->state != state) { 754 TRACE(("Job %d: changing state from %d to %d\n", jp - jobtab + 1, jp->state, state)); 755 jp->state = state; 756 #if JOBS 757 if (done && curjob == jp - jobtab + 1) 758 curjob = 0; /* no current job */ 759 #endif 760 } 761 } 762 } 763 } 764 INTON; 765 if (! rootshell || ! iflag || (job && thisjob == job)) { 766 #if JOBS 767 if ((status & 0xFF) == 0177) 768 status >>= 8; 769 #endif 770 core = status & 0x80; 771 status &= 0x7F; 772 if (status != 0 && status != SIGINT && status != SIGPIPE) { 773 if (thisjob != job) 774 outfmt(out2, "%d: ", pid); 775 #if JOBS 776 if (status == SIGTSTP && rootshell && iflag) 777 outfmt(out2, "%%%d ", job - jobtab + 1); 778 #endif 779 if (status < NSIG && sys_siglist[status]) 780 out2str(sys_siglist[status]); 781 else 782 outfmt(out2, "Signal %d", status); 783 if (core) 784 out2str(" - core dumped"); 785 out2c('\n'); 786 flushout(&errout); 787 } else { 788 TRACE(("Not printing status: status=%d\n", status)); 789 } 790 } else { 791 TRACE(("Not printing status, rootshell=%d, job=0x%x\n", rootshell, job)); 792 if (thisjob) 793 thisjob->changed = 1; 794 } 795 return pid; 796 } 797 798 799 800 /* 801 * Do a wait system call. If job control is compiled in, we accept 802 * stopped processes. If block is zero, we return a value of zero 803 * rather than blocking. 804 * 805 * System V doesn't have a non-blocking wait system call. It does 806 * have a SIGCLD signal that is sent to a process when one of it's 807 * children dies. The obvious way to use SIGCLD would be to install 808 * a handler for SIGCLD which simply bumped a counter when a SIGCLD 809 * was received, and have waitproc bump another counter when it got 810 * the status of a process. Waitproc would then know that a wait 811 * system call would not block if the two counters were different. 812 * This approach doesn't work because if a process has children that 813 * have not been waited for, System V will send it a SIGCLD when it 814 * installs a signal handler for SIGCLD. What this means is that when 815 * a child exits, the shell will be sent SIGCLD signals continuously 816 * until is runs out of stack space, unless it does a wait call before 817 * restoring the signal handler. The code below takes advantage of 818 * this (mis)feature by installing a signal handler for SIGCLD and 819 * then checking to see whether it was called. If there are any 820 * children to be waited for, it will be. 821 * 822 * If neither SYSV nor BSD is defined, we don't implement nonblocking 823 * waits at all. In this case, the user will not be informed when 824 * a background process until the next time she runs a real program 825 * (as opposed to running a builtin command or just typing return), 826 * and the jobs command may give out of date information. 827 */ 828 829 #ifdef SYSV 830 STATIC int gotsigchild; 831 832 STATIC int onsigchild() { 833 gotsigchild = 1; 834 } 835 #endif 836 837 838 STATIC int 839 waitproc(block, status) 840 int block; 841 int *status; 842 { 843 #ifdef BSD 844 int flags; 845 846 #if JOBS 847 flags = WUNTRACED; 848 #else 849 flags = 0; 850 #endif 851 if (block == 0) 852 flags |= WNOHANG; 853 return wait3(status, flags, (struct rusage *)NULL); 854 #else 855 #ifdef SYSV 856 int (*save)(); 857 858 if (block == 0) { 859 gotsigchild = 0; 860 save = signal(SIGCLD, onsigchild); 861 signal(SIGCLD, save); 862 if (gotsigchild == 0) 863 return 0; 864 } 865 return wait(status); 866 #else 867 if (block == 0) 868 return 0; 869 return wait(status); 870 #endif 871 #endif 872 } 873 874 /* 875 * return 1 if there are stopped jobs, otherwise 0 876 */ 877 int job_warning = 0; 878 int 879 stoppedjobs() 880 { 881 register int jobno; 882 register struct job *jp; 883 884 if (job_warning) 885 return (0); 886 for (jobno = 1, jp = jobtab; jobno <= njobs; jobno++, jp++) { 887 if (jp->used == 0) 888 continue; 889 if (jp->state == JOBSTOPPED) { 890 out2str("You have stopped jobs.\n"); 891 job_warning = 2; 892 return (1); 893 } 894 } 895 896 return (0); 897 } 898 899 /* 900 * Return a string identifying a command (to be printed by the 901 * jobs command. 902 */ 903 904 STATIC char *cmdnextc; 905 STATIC int cmdnleft; 906 STATIC void cmdtxt(), cmdputs(); 907 #define MAXCMDTEXT 200 908 909 char * 910 commandtext(n) 911 union node *n; 912 { 913 char *name; 914 915 cmdnextc = name = ckmalloc(MAXCMDTEXT); 916 cmdnleft = MAXCMDTEXT - 4; 917 cmdtxt(n); 918 *cmdnextc = '\0'; 919 return name; 920 } 921 922 923 STATIC void 924 cmdtxt(n) 925 union node *n; 926 { 927 union node *np; 928 struct nodelist *lp; 929 char *p; 930 int i; 931 char s[2]; 932 933 if (n == NULL) 934 return; 935 switch (n->type) { 936 case NSEMI: 937 cmdtxt(n->nbinary.ch1); 938 cmdputs("; "); 939 cmdtxt(n->nbinary.ch2); 940 break; 941 case NAND: 942 cmdtxt(n->nbinary.ch1); 943 cmdputs(" && "); 944 cmdtxt(n->nbinary.ch2); 945 break; 946 case NOR: 947 cmdtxt(n->nbinary.ch1); 948 cmdputs(" || "); 949 cmdtxt(n->nbinary.ch2); 950 break; 951 case NPIPE: 952 for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) { 953 cmdtxt(lp->n); 954 if (lp->next) 955 cmdputs(" | "); 956 } 957 break; 958 case NSUBSHELL: 959 cmdputs("("); 960 cmdtxt(n->nredir.n); 961 cmdputs(")"); 962 break; 963 case NREDIR: 964 case NBACKGND: 965 cmdtxt(n->nredir.n); 966 break; 967 case NIF: 968 cmdputs("if "); 969 cmdtxt(n->nif.test); 970 cmdputs("; then "); 971 cmdtxt(n->nif.ifpart); 972 cmdputs("..."); 973 break; 974 case NWHILE: 975 cmdputs("while "); 976 goto until; 977 case NUNTIL: 978 cmdputs("until "); 979 until: 980 cmdtxt(n->nbinary.ch1); 981 cmdputs("; do "); 982 cmdtxt(n->nbinary.ch2); 983 cmdputs("; done"); 984 break; 985 case NFOR: 986 cmdputs("for "); 987 cmdputs(n->nfor.var); 988 cmdputs(" in ..."); 989 break; 990 case NCASE: 991 cmdputs("case "); 992 cmdputs(n->ncase.expr->narg.text); 993 cmdputs(" in ..."); 994 break; 995 case NDEFUN: 996 cmdputs(n->narg.text); 997 cmdputs("() ..."); 998 break; 999 case NCMD: 1000 for (np = n->ncmd.args ; np ; np = np->narg.next) { 1001 cmdtxt(np); 1002 if (np->narg.next) 1003 cmdputs(" "); 1004 } 1005 for (np = n->ncmd.redirect ; np ; np = np->nfile.next) { 1006 cmdputs(" "); 1007 cmdtxt(np); 1008 } 1009 break; 1010 case NARG: 1011 cmdputs(n->narg.text); 1012 break; 1013 case NTO: 1014 p = ">"; i = 1; goto redir; 1015 case NAPPEND: 1016 p = ">>"; i = 1; goto redir; 1017 case NTOFD: 1018 p = ">&"; i = 1; goto redir; 1019 case NFROM: 1020 p = "<"; i = 0; goto redir; 1021 case NFROMFD: 1022 p = "<&"; i = 0; goto redir; 1023 redir: 1024 if (n->nfile.fd != i) { 1025 s[0] = n->nfile.fd + '0'; 1026 s[1] = '\0'; 1027 cmdputs(s); 1028 } 1029 cmdputs(p); 1030 if (n->type == NTOFD || n->type == NFROMFD) { 1031 s[0] = n->ndup.dupfd + '0'; 1032 s[1] = '\0'; 1033 cmdputs(s); 1034 } else { 1035 cmdtxt(n->nfile.fname); 1036 } 1037 break; 1038 case NHERE: 1039 case NXHERE: 1040 cmdputs("<<..."); 1041 break; 1042 default: 1043 cmdputs("???"); 1044 break; 1045 } 1046 } 1047 1048 1049 1050 STATIC void 1051 cmdputs(s) 1052 char *s; 1053 { 1054 register char *p, *q; 1055 register char c; 1056 int subtype = 0; 1057 1058 if (cmdnleft <= 0) 1059 return; 1060 p = s; 1061 q = cmdnextc; 1062 while ((c = *p++) != '\0') { 1063 if (c == CTLESC) 1064 *q++ = *p++; 1065 else if (c == CTLVAR) { 1066 *q++ = '$'; 1067 if (--cmdnleft > 0) 1068 *q++ = '{'; 1069 subtype = *p++; 1070 } else if (c == '=' && subtype != 0) { 1071 *q++ = "}-+?="[(subtype & VSTYPE) - VSNORMAL]; 1072 subtype = 0; 1073 } else if (c == CTLENDVAR) { 1074 *q++ = '}'; 1075 } else if (c == CTLBACKQ | c == CTLBACKQ+CTLQUOTE) 1076 cmdnleft++; /* ignore it */ 1077 else 1078 *q++ = c; 1079 if (--cmdnleft <= 0) { 1080 *q++ = '.'; 1081 *q++ = '.'; 1082 *q++ = '.'; 1083 break; 1084 } 1085 } 1086 cmdnextc = q; 1087 } 1088