xref: /original-bsd/bin/sh/jobs.c (revision 51dd4909)
1 /*-
2  * Copyright (c) 1991 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Kenneth Almquist.
7  *
8  * %sccs.include.redist.c%
9  */
10 
11 #ifndef lint
12 static char sccsid[] = "@(#)jobs.c	5.1 (Berkeley) 03/07/91";
13 #endif /* not lint */
14 
15 #include "shell.h"
16 #if JOBS
17 #include "sgtty.h"
18 #undef CEOF			/* syntax.h redefines this */
19 #endif
20 #include "main.h"
21 #include "parser.h"
22 #include "nodes.h"
23 #include "jobs.h"
24 #include "options.h"
25 #include "trap.h"
26 #include "signames.h"
27 #include "syntax.h"
28 #include "input.h"
29 #include "output.h"
30 #include "memalloc.h"
31 #include "error.h"
32 #include "mystring.h"
33 #include <fcntl.h>
34 #include <signal.h>
35 #include <errno.h>
36 #ifdef BSD
37 #include <sys/types.h>
38 #include <sys/wait.h>
39 #include <sys/time.h>
40 #include <sys/resource.h>
41 #endif
42 
43 
44 
45 struct job *jobtab;		/* array of jobs */
46 int njobs;			/* size of array */
47 MKINIT short backgndpid = -1;	/* pid of last background process */
48 #if JOBS
49 int initialpgrp;		/* pgrp of shell on invocation */
50 short curjob;			/* current job */
51 #endif
52 
53 #ifdef __STDC__
54 STATIC void restartjob(struct job *);
55 STATIC struct job *getjob(char *);
56 STATIC void freejob(struct job *);
57 STATIC int procrunning(int);
58 STATIC int dowait(int, struct job *);
59 STATIC int waitproc(int, int *);
60 STATIC char *commandtext(union node *);
61 #else
62 STATIC void restartjob();
63 STATIC struct job *getjob();
64 STATIC void freejob();
65 STATIC int procrunning();
66 STATIC int dowait();
67 STATIC int waitproc();
68 STATIC char *commandtext();
69 #endif
70 
71 
72 
73 #if JOBS
74 /*
75  * Turn job control on and off.
76  *
77  * Note:  This code assumes that the third arg to ioctl is a character
78  * pointer, which is true on Berkeley systems but not System V.  Since
79  * System V doesn't have job control yet, this isn't a problem now.
80  */
81 
82 MKINIT int jobctl;
83 
84 void
85 setjobctl(on) {
86 	int ldisc;
87 
88 	if (on == jobctl || rootshell == 0)
89 		return;
90 	if (on) {
91 		do { /* while we are in the background */
92 			if (ioctl(2, TIOCGPGRP, (char *)&initialpgrp) < 0) {
93 				out2str("ash: can't access tty; job control turned off\n");
94 				jflag = 0;
95 				return;
96 			}
97 			if (initialpgrp == -1)
98 				initialpgrp = getpgrp(0);
99 			else if (initialpgrp != getpgrp(0)) {
100 				killpg(initialpgrp, SIGTTIN);
101 				continue;
102 			}
103 		} while (0);
104 		if (ioctl(2, TIOCGETD, (char *)&ldisc) < 0 || ldisc != NTTYDISC) {
105 			out2str("ash: need new tty driver to run job control; job control turned off\n");
106 			jflag = 0;
107 			return;
108 		}
109 		setsignal(SIGTSTP);
110 		setsignal(SIGTTOU);
111 		setpgrp(0, rootpid);
112 		ioctl(2, TIOCSPGRP, (char *)&rootpid);
113 	} else { /* turning job control off */
114 		setpgrp(0, initialpgrp);
115 		ioctl(2, TIOCSPGRP, (char *)&initialpgrp);
116 		setsignal(SIGTSTP);
117 		setsignal(SIGTTOU);
118 	}
119 	jobctl = on;
120 }
121 #endif
122 
123 
124 #ifdef mkinit
125 
126 SHELLPROC {
127 	backgndpid = -1;
128 #if JOBS
129 	jobctl = 0;
130 #endif
131 }
132 
133 #endif
134 
135 
136 
137 #if JOBS
138 fgcmd(argc, argv)  char **argv; {
139 	struct job *jp;
140 	int pgrp;
141 	int status;
142 
143 	jp = getjob(argv[1]);
144 	if (jp->jobctl == 0)
145 		error("job not created under job control");
146 	pgrp = jp->ps[0].pid;
147 	ioctl(2, TIOCSPGRP, (char *)&pgrp);
148 	restartjob(jp);
149 	INTOFF;
150 	status = waitforjob(jp);
151 	INTON;
152 	return status;
153 }
154 
155 
156 bgcmd(argc, argv)  char **argv; {
157 	struct job *jp;
158 
159 	do {
160 		jp = getjob(*++argv);
161 		if (jp->jobctl == 0)
162 			error("job not created under job control");
163 		restartjob(jp);
164 	} while (--argc > 1);
165 	return 0;
166 }
167 
168 
169 STATIC void
170 restartjob(jp)
171 	struct job *jp;
172 	{
173 	struct procstat *ps;
174 	int i;
175 
176 	if (jp->state == JOBDONE)
177 		return;
178 	INTOFF;
179 	killpg(jp->ps[0].pid, SIGCONT);
180 	for (ps = jp->ps, i = jp->nprocs ; --i >= 0 ; ps++) {
181 		if ((ps->status & 0377) == 0177) {
182 			ps->status = -1;
183 			jp->state = 0;
184 		}
185 	}
186 	INTON;
187 }
188 #endif
189 
190 
191 int
192 jobscmd(argc, argv)  char **argv; {
193 	showjobs(0);
194 	return 0;
195 }
196 
197 
198 /*
199  * Print a list of jobs.  If "change" is nonzero, only print jobs whose
200  * statuses have changed since the last call to showjobs.
201  *
202  * If the shell is interrupted in the process of creating a job, the
203  * result may be a job structure containing zero processes.  Such structures
204  * will be freed here.
205  */
206 
207 void
208 showjobs(change) {
209 	int jobno;
210 	int procno;
211 	int i;
212 	struct job *jp;
213 	struct procstat *ps;
214 	int col;
215 	char s[64];
216 
217 	TRACE(("showjobs(%d) called\n", change));
218 	while (dowait(0, (struct job *)NULL) > 0);
219 	for (jobno = 1, jp = jobtab ; jobno <= njobs ; jobno++, jp++) {
220 		if (! jp->used)
221 			continue;
222 		if (jp->nprocs == 0) {
223 			freejob(jp);
224 			continue;
225 		}
226 		if (change && ! jp->changed)
227 			continue;
228 		procno = jp->nprocs;
229 		for (ps = jp->ps ; ; ps++) {	/* for each process */
230 			if (ps == jp->ps)
231 				fmtstr(s, 64, "[%d] %d ", jobno, ps->pid);
232 			else
233 				fmtstr(s, 64, "    %d ", ps->pid);
234 			out1str(s);
235 			col = strlen(s);
236 			s[0] = '\0';
237 			if (ps->status == -1) {
238 				/* don't print anything */
239 			} else if ((ps->status & 0xFF) == 0) {
240 				fmtstr(s, 64, "Exit %d", ps->status >> 8);
241 			} else {
242 				i = ps->status;
243 #if JOBS
244 				if ((i & 0xFF) == 0177)
245 					i >>= 8;
246 #endif
247 				if ((i & 0x7F) <= MAXSIG && sigmesg[i & 0x7F])
248 					scopy(sigmesg[i & 0x7F], s);
249 				else
250 					fmtstr(s, 64, "Signal %d", i & 0x7F);
251 				if (i & 0x80)
252 					strcat(s, " (core dumped)");
253 			}
254 			out1str(s);
255 			col += strlen(s);
256 			do {
257 				out1c(' ');
258 				col++;
259 			} while (col < 30);
260 			out1str(ps->cmd);
261 			out1c('\n');
262 			if (--procno <= 0)
263 				break;
264 		}
265 		jp->changed = 0;
266 		if (jp->state == JOBDONE) {
267 			freejob(jp);
268 		}
269 	}
270 }
271 
272 
273 /*
274  * Mark a job structure as unused.
275  */
276 
277 STATIC void
278 freejob(jp)
279 	struct job *jp;
280 	{
281 	struct procstat *ps;
282 	int i;
283 
284 	INTOFF;
285 	for (i = jp->nprocs, ps = jp->ps ; --i >= 0 ; ps++) {
286 		if (ps->cmd != nullstr)
287 			ckfree(ps->cmd);
288 	}
289 	if (jp->ps != &jp->ps0)
290 		ckfree(jp->ps);
291 	jp->used = 0;
292 #if JOBS
293 	if (curjob == jp - jobtab + 1)
294 		curjob = 0;
295 #endif
296 	INTON;
297 }
298 
299 
300 
301 int
302 waitcmd(argc, argv)  char **argv; {
303 	struct job *job;
304 	int status;
305 	struct job *jp;
306 
307 	if (argc > 1) {
308 		job = getjob(argv[1]);
309 	} else {
310 		job = NULL;
311 	}
312 	for (;;) {	/* loop until process terminated or stopped */
313 		if (job != NULL) {
314 			if (job->state) {
315 				status = job->ps[job->nprocs - 1].status;
316 				if ((status & 0xFF) == 0)
317 					status = status >> 8 & 0xFF;
318 #if JOBS
319 				else if ((status & 0xFF) == 0177)
320 					status = (status >> 8 & 0x7F) + 128;
321 #endif
322 				else
323 					status = (status & 0x7F) + 128;
324 				if (! iflag)
325 					freejob(job);
326 				return status;
327 			}
328 		} else {
329 			for (jp = jobtab ; ; jp++) {
330 				if (jp >= jobtab + njobs) {	/* no running procs */
331 					return 0;
332 				}
333 				if (jp->used && jp->state == 0)
334 					break;
335 			}
336 		}
337 		dowait(1, (struct job *)NULL);
338 	}
339 }
340 
341 
342 
343 jobidcmd(argc, argv)  char **argv; {
344 	struct job *jp;
345 	int i;
346 
347 	jp = getjob(argv[1]);
348 	for (i = 0 ; i < jp->nprocs ; ) {
349 		out1fmt("%d", jp->ps[i].pid);
350 		out1c(++i < jp->nprocs? ' ' : '\n');
351 	}
352 	return 0;
353 }
354 
355 
356 
357 /*
358  * Convert a job name to a job structure.
359  */
360 
361 STATIC struct job *
362 getjob(name)
363 	char *name;
364 	{
365 	int jobno;
366 	register struct job *jp;
367 	int pid;
368 	int i;
369 
370 	if (name == NULL) {
371 #if JOBS
372 currentjob:
373 		if ((jobno = curjob) == 0 || jobtab[jobno - 1].used == 0)
374 			error("No current job");
375 		return &jobtab[jobno - 1];
376 #else
377 		error("No current job");
378 #endif
379 	} else if (name[0] == '%') {
380 		if (is_digit(name[1])) {
381 			jobno = number(name + 1);
382 			if (jobno > 0 && jobno <= njobs
383 			 && jobtab[jobno - 1].used != 0)
384 				return &jobtab[jobno - 1];
385 #if JOBS
386 		} else if (name[1] == '%' && name[2] == '\0') {
387 			goto currentjob;
388 #endif
389 		} else {
390 			register struct job *found = NULL;
391 			for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
392 				if (jp->used && jp->nprocs > 0
393 				 && prefix(name + 1, jp->ps[0].cmd)) {
394 					if (found)
395 						error("%s: ambiguous", name);
396 					found = jp;
397 				}
398 			}
399 			if (found)
400 				return found;
401 		}
402 	} else if (is_number(name)) {
403 		pid = number(name);
404 		for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
405 			if (jp->used && jp->nprocs > 0
406 			 && jp->ps[jp->nprocs - 1].pid == pid)
407 				return jp;
408 		}
409 	}
410 	error("No such job: %s", name);
411 }
412 
413 
414 
415 /*
416  * Return a new job structure,
417  */
418 
419 struct job *
420 makejob(node, nprocs)
421 	union node *node;
422 	{
423 	int i;
424 	struct job *jp;
425 
426 	for (i = njobs, jp = jobtab ; ; jp++) {
427 		if (--i < 0) {
428 			INTOFF;
429 			if (njobs == 0) {
430 				jobtab = ckmalloc(4 * sizeof jobtab[0]);
431 			} else {
432 				jp = ckmalloc((njobs + 4) * sizeof jobtab[0]);
433 				bcopy(jobtab, jp, njobs * sizeof jp[0]);
434 				ckfree(jobtab);
435 				jobtab = jp;
436 			}
437 			jp = jobtab + njobs;
438 			for (i = 4 ; --i >= 0 ; jobtab[njobs++].used = 0);
439 			INTON;
440 			break;
441 		}
442 		if (jp->used == 0)
443 			break;
444 	}
445 	INTOFF;
446 	jp->state = 0;
447 	jp->used = 1;
448 	jp->changed = 0;
449 	jp->nprocs = 0;
450 #if JOBS
451 	jp->jobctl = jobctl;
452 #endif
453 	if (nprocs > 1) {
454 		jp->ps = ckmalloc(nprocs * sizeof (struct procstat));
455 	} else {
456 		jp->ps = &jp->ps0;
457 	}
458 	INTON;
459 	TRACE(("makejob(0x%x, %d) returns %%%d\n", (int)node, nprocs, jp - jobtab + 1));
460 	return jp;
461 }
462 
463 
464 /*
465  * Fork of a subshell.  If we are doing job control, give the subshell its
466  * own process group.  Jp is a job structure that the job is to be added to.
467  * N is the command that will be evaluated by the child.  Both jp and n may
468  * be NULL.  The mode parameter can be one of the following:
469  *	FORK_FG - Fork off a foreground process.
470  *	FORK_BG - Fork off a background process.
471  *	FORK_NOJOB - Like FORK_FG, but don't give the process its own
472  *		     process group even if job control is on.
473  *
474  * When job control is turned off, background processes have their standard
475  * input redirected to /dev/null (except for the second and later processes
476  * in a pipeline).
477  */
478 
479 int
480 forkshell(jp, n, mode)
481 	union node *n;
482 	struct job *jp;
483 	{
484 	int pid;
485 	int pgrp;
486 
487 	TRACE(("forkshell(%%%d, 0x%x, %d) called\n", jp - jobtab, (int)n, mode));
488 	INTOFF;
489 	pid = fork();
490 	if (pid == -1) {
491 		TRACE(("Fork failed, errno=%d\n", errno));
492 		INTON;
493 		error("Cannot fork");
494 	}
495 	if (pid == 0) {
496 		struct job *p;
497 		int wasroot;
498 		int i;
499 
500 		TRACE(("Child shell %d\n", getpid()));
501 		wasroot = rootshell;
502 		rootshell = 0;
503 		for (i = njobs, p = jobtab ; --i >= 0 ; p++)
504 			if (p->used)
505 				freejob(p);
506 		closescript();
507 		INTON;
508 		clear_traps();
509 #if JOBS
510 		jobctl = 0;		/* do job control only in root shell */
511 		if (wasroot && mode != FORK_NOJOB && jflag) {
512 			if (jp == NULL || jp->nprocs == 0)
513 				pgrp = getpid();
514 			else
515 				pgrp = jp->ps[0].pid;
516 			setpgrp(0, pgrp);
517 			if (mode == FORK_FG) {
518 				/*** this causes superfluous TIOCSPGRPS ***/
519 				if (ioctl(2, TIOCSPGRP, (char *)&pgrp) < 0)
520 					error("TIOCSPGRP failed, errno=%d\n", errno);
521 			}
522 			setsignal(SIGTSTP);
523 			setsignal(SIGTTOU);
524 		} else if (mode == FORK_BG) {
525 			ignoresig(SIGINT);
526 			ignoresig(SIGQUIT);
527 			if (jp == NULL || jp->nprocs == 0) {
528 				close(0);
529 				if (open("/dev/null", O_RDONLY) != 0)
530 					error("Can't open /dev/null");
531 			}
532 		}
533 #else
534 		if (mode == FORK_BG) {
535 			ignoresig(SIGINT);
536 			ignoresig(SIGQUIT);
537 			if (jp == NULL || jp->nprocs == 0) {
538 				close(0);
539 				if (open("/dev/null", O_RDONLY) != 0)
540 					error("Can't open /dev/null");
541 			}
542 		}
543 #endif
544 		if (wasroot && iflag) {
545 			setsignal(SIGINT);
546 			setsignal(SIGQUIT);
547 			setsignal(SIGTERM);
548 		}
549 		return pid;
550 	}
551 	if (rootshell && mode != FORK_NOJOB && jflag) {
552 		if (jp == NULL || jp->nprocs == 0)
553 			pgrp = pid;
554 		else
555 			pgrp = jp->ps[0].pid;
556 		setpgrp(pid, pgrp);
557 	}
558 	if (mode == FORK_BG)
559 		backgndpid = pid;		/* set $! */
560 	if (jp) {
561 		struct procstat *ps = &jp->ps[jp->nprocs++];
562 		ps->pid = pid;
563 		ps->status = -1;
564 		ps->cmd = nullstr;
565 		if (iflag && rootshell && n)
566 			ps->cmd = commandtext(n);
567 	}
568 	INTON;
569 	TRACE(("In parent shell:  child = %d\n", pid));
570 	return pid;
571 }
572 
573 
574 
575 /*
576  * Wait for job to finish.
577  *
578  * Under job control we have the problem that while a child process is
579  * running interrupts generated by the user are sent to the child but not
580  * to the shell.  This means that an infinite loop started by an inter-
581  * active user may be hard to kill.  With job control turned off, an
582  * interactive user may place an interactive program inside a loop.  If
583  * the interactive program catches interrupts, the user doesn't want
584  * these interrupts to also abort the loop.  The approach we take here
585  * is to have the shell ignore interrupt signals while waiting for a
586  * forground process to terminate, and then send itself an interrupt
587  * signal if the child process was terminated by an interrupt signal.
588  * Unfortunately, some programs want to do a bit of cleanup and then
589  * exit on interrupt; unless these processes terminate themselves by
590  * sending a signal to themselves (instead of calling exit) they will
591  * confuse this approach.
592  */
593 
594 int
595 waitforjob(jp)
596 	register struct job *jp;
597 	{
598 #if JOBS
599 	int mypgrp = getpgrp(0);
600 #endif
601 	int status;
602 	int st;
603 
604 	INTOFF;
605 	TRACE(("waitforjob(%%%d) called\n", jp - jobtab + 1));
606 	while (jp->state == 0) {
607 		dowait(1, jp);
608 	}
609 #if JOBS
610 	if (jp->jobctl) {
611 		if (ioctl(2, TIOCSPGRP, (char *)&mypgrp) < 0)
612 			error("TIOCSPGRP failed, errno=%d\n", errno);
613 	}
614 	if (jp->state == JOBSTOPPED)
615 		curjob = jp - jobtab + 1;
616 #endif
617 	status = jp->ps[jp->nprocs - 1].status;
618 	/* convert to 8 bits */
619 	if ((status & 0xFF) == 0)
620 		st = status >> 8 & 0xFF;
621 #if JOBS
622 	else if ((status & 0xFF) == 0177)
623 		st = (status >> 8 & 0x7F) + 128;
624 #endif
625 	else
626 		st = (status & 0x7F) + 128;
627 	if (! JOBS || jp->state == JOBDONE)
628 		freejob(jp);
629 	CLEAR_PENDING_INT;
630 	if ((status & 0x7F) == SIGINT)
631 		kill(getpid(), SIGINT);
632 	INTON;
633 	return st;
634 }
635 
636 
637 
638 /*
639  * Wait for a process to terminate.
640  */
641 
642 STATIC int
643 dowait(block, job)
644 	struct job *job;
645 	{
646 	int pid;
647 	int status;
648 	struct procstat *sp;
649 	struct job *jp;
650 	struct job *thisjob;
651 	int done;
652 	int stopped;
653 	int core;
654 
655 	TRACE(("dowait(%d) called\n", block));
656 	do {
657 		pid = waitproc(block, &status);
658 		TRACE(("wait returns %d, status=%d\n", pid, status));
659 	} while (pid == -1 && errno == EINTR);
660 	if (pid <= 0)
661 		return pid;
662 	INTOFF;
663 	thisjob = NULL;
664 	for (jp = jobtab ; jp < jobtab + njobs ; jp++) {
665 		if (jp->used) {
666 			done = 1;
667 			stopped = 1;
668 			for (sp = jp->ps ; sp < jp->ps + jp->nprocs ; sp++) {
669 				if (sp->pid == -1)
670 					continue;
671 				if (sp->pid == pid) {
672 					TRACE(("Changin status of proc %d from 0x%x to 0x%x\n", pid, sp->status, status));
673 					sp->status = status;
674 					thisjob = jp;
675 				}
676 				if (sp->status == -1)
677 					stopped = 0;
678 				else if ((sp->status & 0377) == 0177)
679 					done = 0;
680 			}
681 			if (stopped) {		/* stopped or done */
682 				int state = done? JOBDONE : JOBSTOPPED;
683 				if (jp->state != state) {
684 					TRACE(("Job %d: changing state from %d to %d\n", jp - jobtab + 1, jp->state, state));
685 					jp->state = state;
686 #if JOBS
687 					if (done && curjob == jp - jobtab + 1)
688 						curjob = 0;		/* no current job */
689 #endif
690 				}
691 			}
692 		}
693 	}
694 	INTON;
695 	if (! rootshell || ! iflag || (job && thisjob == job)) {
696 #if JOBS
697 		if ((status & 0xFF) == 0177)
698 			status >>= 8;
699 #endif
700 		core = status & 0x80;
701 		status &= 0x7F;
702 		if (status != 0 && status != SIGINT && status != SIGPIPE) {
703 			if (thisjob != job)
704 				outfmt(out2, "%d: ", pid);
705 #if JOBS
706 			if (status == SIGTSTP && rootshell && iflag)
707 				outfmt(out2, "%%%d ", job - jobtab + 1);
708 #endif
709 			if (status <= MAXSIG && sigmesg[status])
710 				out2str(sigmesg[status]);
711 			else
712 				outfmt(out2, "Signal %d", status);
713 			if (core)
714 				out2str(" - core dumped");
715 			out2c('\n');
716 			flushout(&errout);
717 		} else {
718 			TRACE(("Not printing status: status=%d\n", status));
719 		}
720 	} else {
721 		TRACE(("Not printing status, rootshell=%d, job=0x%x\n", rootshell, job));
722 		if (thisjob)
723 			thisjob->changed = 1;
724 	}
725 	return pid;
726 }
727 
728 
729 
730 /*
731  * Do a wait system call.  If job control is compiled in, we accept
732  * stopped processes.  If block is zero, we return a value of zero
733  * rather than blocking.
734  *
735  * System V doesn't have a non-blocking wait system call.  It does
736  * have a SIGCLD signal that is sent to a process when one of it's
737  * children dies.  The obvious way to use SIGCLD would be to install
738  * a handler for SIGCLD which simply bumped a counter when a SIGCLD
739  * was received, and have waitproc bump another counter when it got
740  * the status of a process.  Waitproc would then know that a wait
741  * system call would not block if the two counters were different.
742  * This approach doesn't work because if a process has children that
743  * have not been waited for, System V will send it a SIGCLD when it
744  * installs a signal handler for SIGCLD.  What this means is that when
745  * a child exits, the shell will be sent SIGCLD signals continuously
746  * until is runs out of stack space, unless it does a wait call before
747  * restoring the signal handler.  The code below takes advantage of
748  * this (mis)feature by installing a signal handler for SIGCLD and
749  * then checking to see whether it was called.  If there are any
750  * children to be waited for, it will be.
751  *
752  * If neither SYSV nor BSD is defined, we don't implement nonblocking
753  * waits at all.  In this case, the user will not be informed when
754  * a background process until the next time she runs a real program
755  * (as opposed to running a builtin command or just typing return),
756  * and the jobs command may give out of date information.
757  */
758 
759 #ifdef SYSV
760 STATIC int gotsigchild;
761 
762 STATIC int onsigchild() {
763 	gotsigchild = 1;
764 }
765 #endif
766 
767 
768 STATIC int
769 waitproc(block, status)
770 	int *status;
771 	{
772 #ifdef BSD
773 	int flags;
774 
775 #if JOBS
776 	flags = WUNTRACED;
777 #else
778 	flags = 0;
779 #endif
780 	if (block == 0)
781 		flags |= WNOHANG;
782 	return wait3((union wait *)status, flags, (struct rusage *)NULL);
783 #else
784 #ifdef SYSV
785 	int (*save)();
786 
787 	if (block == 0) {
788 		gotsigchild = 0;
789 		save = signal(SIGCLD, onsigchild);
790 		signal(SIGCLD, save);
791 		if (gotsigchild == 0)
792 			return 0;
793 	}
794 	return wait(status);
795 #else
796 	if (block == 0)
797 		return 0;
798 	return wait(status);
799 #endif
800 #endif
801 }
802 
803 
804 
805 /*
806  * Return a string identifying a command (to be printed by the
807  * jobs command.
808  */
809 
810 STATIC char *cmdnextc;
811 STATIC int cmdnleft;
812 STATIC void cmdtxt(), cmdputs();
813 
814 STATIC char *
815 commandtext(n)
816 	union node *n;
817 	{
818 	char *name;
819 
820 	cmdnextc = name = ckmalloc(50);
821 	cmdnleft = 50 - 4;
822 	cmdtxt(n);
823 	*cmdnextc = '\0';
824 	return name;
825 }
826 
827 
828 STATIC void
829 cmdtxt(n)
830 	union node *n;
831 	{
832 	union node *np;
833 	struct nodelist *lp;
834 	char *p;
835 	int i;
836 	char s[2];
837 
838 	switch (n->type) {
839 	case NSEMI:
840 		cmdtxt(n->nbinary.ch1);
841 		cmdputs("; ");
842 		cmdtxt(n->nbinary.ch2);
843 		break;
844 	case NAND:
845 		cmdtxt(n->nbinary.ch1);
846 		cmdputs(" && ");
847 		cmdtxt(n->nbinary.ch2);
848 		break;
849 	case NOR:
850 		cmdtxt(n->nbinary.ch1);
851 		cmdputs(" || ");
852 		cmdtxt(n->nbinary.ch2);
853 		break;
854 	case NPIPE:
855 		for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
856 			cmdtxt(lp->n);
857 			if (lp->next)
858 				cmdputs(" | ");
859 		}
860 		break;
861 	case NSUBSHELL:
862 		cmdputs("(");
863 		cmdtxt(n->nredir.n);
864 		cmdputs(")");
865 		break;
866 	case NREDIR:
867 	case NBACKGND:
868 		cmdtxt(n->nredir.n);
869 		break;
870 	case NIF:
871 		cmdputs("if ");
872 		cmdtxt(n->nif.test);
873 		cmdputs("; then ");
874 		cmdtxt(n->nif.ifpart);
875 		cmdputs("...");
876 		break;
877 	case NWHILE:
878 		cmdputs("while ");
879 		goto until;
880 	case NUNTIL:
881 		cmdputs("until ");
882 until:
883 		cmdtxt(n->nbinary.ch1);
884 		cmdputs("; do ");
885 		cmdtxt(n->nbinary.ch2);
886 		cmdputs("; done");
887 		break;
888 	case NFOR:
889 		cmdputs("for ");
890 		cmdputs(n->nfor.var);
891 		cmdputs(" in ...");
892 		break;
893 	case NCASE:
894 		cmdputs("case ");
895 		cmdputs(n->ncase.expr->narg.text);
896 		cmdputs(" in ...");
897 		break;
898 	case NDEFUN:
899 		cmdputs(n->narg.text);
900 		cmdputs("() ...");
901 		break;
902 	case NCMD:
903 		for (np = n->ncmd.args ; np ; np = np->narg.next) {
904 			cmdtxt(np);
905 			if (np->narg.next)
906 				cmdputs(" ");
907 		}
908 		for (np = n->ncmd.redirect ; np ; np = np->nfile.next) {
909 			cmdputs(" ");
910 			cmdtxt(np);
911 		}
912 		break;
913 	case NARG:
914 		cmdputs(n->narg.text);
915 		break;
916 	case NTO:
917 		p = ">";  i = 1;  goto redir;
918 	case NAPPEND:
919 		p = ">>";  i = 1;  goto redir;
920 	case NTOFD:
921 		p = ">&";  i = 1;  goto redir;
922 	case NFROM:
923 		p = "<";  i = 0;  goto redir;
924 	case NFROMFD:
925 		p = "<&";  i = 0;  goto redir;
926 redir:
927 		if (n->nfile.fd != i) {
928 			s[0] = n->nfile.fd + '0';
929 			s[1] = '\0';
930 			cmdputs(s);
931 		}
932 		cmdputs(p);
933 		if (n->type == NTOFD || n->type == NFROMFD) {
934 			s[0] = n->ndup.dupfd + '0';
935 			s[1] = '\0';
936 			cmdputs(s);
937 		} else {
938 			cmdtxt(n->nfile.fname);
939 		}
940 		break;
941 	case NHERE:
942 	case NXHERE:
943 		cmdputs("<<...");
944 		break;
945 	default:
946 		cmdputs("???");
947 		break;
948 	}
949 }
950 
951 
952 
953 STATIC void
954 cmdputs(s)
955 	char *s;
956 	{
957 	register char *p, *q;
958 	register char c;
959 	int subtype = 0;
960 
961 	if (cmdnleft <= 0)
962 		return;
963 	p = s;
964 	q = cmdnextc;
965 	while ((c = *p++) != '\0') {
966 		if (c == CTLESC)
967 			*q++ = *p++;
968 		else if (c == CTLVAR) {
969 			*q++ = '$';
970 			if (--cmdnleft > 0)
971 				*q++ = '{';
972 			subtype = *p++;
973 		} else if (c == '=' && subtype != 0) {
974 			*q++ = "}-+?="[(subtype & VSTYPE) - VSNORMAL];
975 			subtype = 0;
976 		} else if (c == CTLENDVAR) {
977 			*q++ = '}';
978 		} else if (c == CTLBACKQ | c == CTLBACKQ+CTLQUOTE)
979 			cmdnleft++;		/* ignore it */
980 		else
981 			*q++ = c;
982 		if (--cmdnleft <= 0) {
983 			*q++ = '.';
984 			*q++ = '.';
985 			*q++ = '.';
986 			break;
987 		}
988 	}
989 	cmdnextc = q;
990 }
991