xref: /openbsd-src/usr.bin/make/engine.c (revision 2b0358df1d88d06ef4139321dd05bd5e05d91eaf)
1 /*	$OpenBSD: engine.c,v 1.22 2008/11/10 10:48:43 espie Exp $ */
2 /*
3  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
4  * Copyright (c) 1988, 1989 by Adam de Boor
5  * Copyright (c) 1989 by Berkeley Softworks
6  * All rights reserved.
7  *
8  * This code is derived from software contributed to Berkeley by
9  * Adam de Boor.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/types.h>
37 #include <sys/wait.h>
38 #include <assert.h>
39 #include <limits.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <ctype.h>
43 #include <errno.h>
44 #include <fcntl.h>
45 #include <unistd.h>
46 #include <string.h>
47 #include <signal.h>
48 #include "config.h"
49 #include "defines.h"
50 #include "dir.h"
51 #include "engine.h"
52 #include "arch.h"
53 #include "gnode.h"
54 #include "targ.h"
55 #include "var.h"
56 #include "extern.h"
57 #include "lst.h"
58 #include "timestamp.h"
59 #include "make.h"
60 #include "pathnames.h"
61 #include "error.h"
62 #include "str.h"
63 #include "memory.h"
64 #include "buf.h"
65 
66 static void MakeTimeStamp(void *, void *);
67 static int rewrite_time(const char *);
68 static void setup_signal(int);
69 static void setup_all_signals(void);
70 static void setup_meta(void);
71 static char **recheck_command_for_shell(char **);
72 
73 static int setup_and_run_command(char *, GNode *, int);
74 static void run_command(const char *, bool);
75 static void handle_compat_interrupts(GNode *);
76 
77 bool
78 Job_CheckCommands(GNode *gn)
79 {
80 	/* Alter our type to tell if errors should be ignored or things
81 	 * should not be printed so setup_and_run_command knows what to do.
82 	 */
83 	if (Targ_Ignore(gn))
84 		gn->type |= OP_IGNORE;
85 	if (Targ_Silent(gn))
86 		gn->type |= OP_SILENT;
87 
88 	if (OP_NOP(gn->type) && Lst_IsEmpty(&gn->commands) &&
89 	    (gn->type & OP_LIB) == 0) {
90 		/*
91 		 * No commands. Look for .DEFAULT rule from which we might infer
92 		 * commands
93 		 */
94 		if ((gn->type & OP_NODEFAULT) == 0 &&
95 		    (DEFAULT->type & OP_DUMMY) == 0 &&
96 		    !Lst_IsEmpty(&DEFAULT->commands)) {
97 			/*
98 			 * Make only looks for a .DEFAULT if the node was never
99 			 * the target of an operator, so that's what we do too.
100 			 * If a .DEFAULT was given, we substitute its commands
101 			 * for gn's commands and set the IMPSRC variable to be
102 			 * the target's name The DEFAULT node acts like a
103 			 * transformation rule, in that gn also inherits any
104 			 * attributes or sources attached to .DEFAULT itself.
105 			 */
106 			Make_HandleUse(DEFAULT, gn);
107 			Var(IMPSRC_INDEX, gn) = Var(TARGET_INDEX, gn);
108 		} else if (is_out_of_date(Dir_MTime(gn))) {
109 			/*
110 			 * The node wasn't the target of an operator we have no
111 			 * .DEFAULT rule to go on and the target doesn't
112 			 * already exist. There's nothing more we can do for
113 			 * this branch.
114 			 */
115 			 return false;
116 	    	}
117 	}
118 	return true;
119 }
120 
121 void
122 job_failure(GNode *gn, void (*abortProc)(char *, ...))
123 {
124 	/*
125 	 If the -k flag wasn't given, we stop in
126 	 * our tracks, otherwise we just don't update this
127 	 * node's parents so they never get examined.
128 	 */
129 	static const char msg[] =
130 	    "make: don't know how to make";
131 
132 	if (gn->type & OP_OPTIONAL) {
133 		(void)fprintf(stdout, "%s %s(ignored)\n", msg,
134 		    gn->name);
135 		(void)fflush(stdout);
136 	} else if (keepgoing) {
137 		(void)fprintf(stdout, "%s %s(continuing)\n",
138 		    msg, gn->name);
139 		(void)fflush(stdout);
140 	} else {
141 		(*abortProc)("%s %s. Stop in %s.", msg,
142 		    gn->name, Var_Value(".CURDIR"));
143 	}
144 }
145 /* touch files the hard way, by writing stuff to them */
146 static int
147 rewrite_time(const char *name)
148 {
149 	int fd;
150 	char c;
151 
152 	fd = open(name, O_RDWR | O_CREAT, 0666);
153 	if (fd < 0)
154 		return -1;
155 	/*
156 	 * Read and write a byte to the file to change
157 	 * the modification time.
158 	 */
159 	if (read(fd, &c, 1) == 1) {
160 		(void)lseek(fd, 0, SEEK_SET);
161 		(void)write(fd, &c, 1);
162 	}
163 
164 	(void)close(fd);
165 	return 0;
166 }
167 
168 void
169 Job_Touch(GNode *gn)
170 {
171 	if (gn->type & (OP_JOIN|OP_USE|OP_EXEC|OP_OPTIONAL)) {
172 		/*
173 		 * .JOIN, .USE, and .OPTIONAL targets are "virtual" targets
174 		 * and, as such, shouldn't really be created.
175 		 */
176 		return;
177 	}
178 
179 	if (!(gn->type & OP_SILENT)) {
180 		(void)fprintf(stdout, "touch %s\n", gn->name);
181 		(void)fflush(stdout);
182 	}
183 
184 	if (noExecute) {
185 		return;
186 	}
187 
188 	if (gn->type & OP_ARCHV) {
189 		Arch_Touch(gn);
190 	} else if (gn->type & OP_LIB) {
191 		Arch_TouchLib(gn);
192 	} else {
193 		const char *file = gn->path != NULL ? gn->path : gn->name;
194 
195 		if (set_times(file) == -1){
196 			if (rewrite_time(file) == -1) {
197 				(void)fprintf(stdout,
198 				    "*** couldn't touch %s: %s", file,
199 				    strerror(errno));
200 				(void)fflush(stdout);
201 		    	}
202 		}
203 	}
204 }
205 
206 void
207 Make_TimeStamp(GNode *parent, GNode *child)
208 {
209 	if (is_strictly_before(parent->cmtime, child->mtime))
210 		parent->cmtime = child->mtime;
211 }
212 
213 void
214 Make_HandleUse(GNode	*cgn,	/* The .USE node */
215     GNode	*pgn)	/* The target of the .USE node */
216 {
217 	GNode	*gn;	/* A child of the .USE node */
218 	LstNode	ln;	/* An element in the children list */
219 
220 
221 	assert(cgn->type & (OP_USE|OP_TRANSFORM));
222 
223 	if ((cgn->type & OP_USE) || Lst_IsEmpty(&pgn->commands)) {
224 		/* .USE or transformation and target has no commands
225 		 * -- append the child's commands to the parent.  */
226 		Lst_Concat(&pgn->commands, &cgn->commands);
227 	}
228 
229 	for (ln = Lst_First(&cgn->children); ln != NULL;
230 	    ln = Lst_Adv(ln)) {
231 		gn = (GNode *)Lst_Datum(ln);
232 
233 		if (Lst_AddNew(&pgn->children, gn)) {
234 			Lst_AtEnd(&gn->parents, pgn);
235 			pgn->unmade++;
236 		}
237 	}
238 
239 	pgn->type |= cgn->type & ~(OP_OPMASK|OP_USE|OP_TRANSFORM);
240 
241 	/*
242 	 * This child node is now "made", so we decrement the count of
243 	 * unmade children in the parent... We also remove the child
244 	 * from the parent's list to accurately reflect the number of
245 	 * decent children the parent has. This is used by Make_Run to
246 	 * decide whether to queue the parent or examine its children...
247 	 */
248 	if (cgn->type & OP_USE)
249 		pgn->unmade--;
250 
251 	/* if the parent node doesn't have any location, then inherit the
252 	 * use stuff, since that gives us better error messages.
253 	 */
254 	if (!pgn->lineno) {
255 		pgn->lineno = cgn->lineno;
256 		pgn->fname = cgn->fname;
257 	}
258 }
259 
260 void
261 Make_DoAllVar(GNode *gn)
262 {
263 	GNode *child;
264 	LstNode ln;
265 	BUFFER allsrc, oodate;
266 	char *target;
267 	bool do_oodate;
268 	int oodate_count, allsrc_count = 0;
269 
270 	oodate_count = 0;
271 	allsrc_count = 0;
272 
273 	for (ln = Lst_First(&gn->children); ln != NULL; ln = Lst_Adv(ln)) {
274 		child = (GNode *)Lst_Datum(ln);
275 		if ((child->type & (OP_EXEC|OP_USE|OP_INVISIBLE)) != 0)
276 			continue;
277 		if (OP_NOP(child->type) ||
278 		    (target = Var(TARGET_INDEX, child)) == NULL) {
279 			/*
280 			 * this node is only source; use the specific pathname
281 			 * for it
282 			 */
283 			target = child->path != NULL ? child->path :
284 			    child->name;
285 		}
286 
287 		/*
288 		 * It goes in the OODATE variable if the parent is younger than
289 		 * the child or if the child has been modified more recently
290 		 * than the start of the make.  This is to keep make from
291 		 * getting confused if something else updates the parent after
292 		 * the make starts (shouldn't happen, I know, but sometimes it
293 		 * does). In such a case, if we've updated the kid, the parent
294 		 * is likely to have a modification time later than that of the
295 		 * kid and anything that relies on the OODATE variable will be
296 		 * hosed.
297 		 */
298 		do_oodate = false;
299 		if (gn->type & OP_JOIN) {
300 			if (child->built_status == MADE)
301 				do_oodate = true;
302 		} else if (is_strictly_before(gn->mtime, child->mtime) ||
303 		   (!is_strictly_before(child->mtime, now) &&
304 		   child->built_status == MADE))
305 		   	do_oodate = true;
306 		if (do_oodate) {
307 			oodate_count++;
308 			if (oodate_count == 1)
309 				Var(OODATE_INDEX, gn) = target;
310 			else {
311 				if (oodate_count == 2) {
312 					Buf_Init(&oodate, 0);
313 					Buf_AddString(&oodate,
314 					    Var(OODATE_INDEX, gn));
315 				}
316 				Buf_AddSpace(&oodate);
317 				Buf_AddString(&oodate, target);
318 			}
319 		}
320 		allsrc_count++;
321 		if (allsrc_count == 1)
322 			Var(ALLSRC_INDEX, gn) = target;
323 		else {
324 			if (allsrc_count == 2) {
325 				Buf_Init(&allsrc, 0);
326 				Buf_AddString(&allsrc,
327 				    Var(ALLSRC_INDEX, gn));
328 			}
329 			Buf_AddSpace(&allsrc);
330 			Buf_AddString(&allsrc, target);
331 		}
332 	}
333 
334 	if (allsrc_count > 1)
335 		Var(ALLSRC_INDEX, gn) = Buf_Retrieve(&allsrc);
336 	if (oodate_count > 1)
337 		Var(OODATE_INDEX, gn) = Buf_Retrieve(&oodate);
338 
339 	if (gn->impliedsrc)
340 		Var(IMPSRC_INDEX, gn) = Var(TARGET_INDEX, gn->impliedsrc);
341 
342 	if (gn->type & OP_JOIN)
343 		Var(TARGET_INDEX, gn) = Var(ALLSRC_INDEX, gn);
344 }
345 
346 /* Wrapper to call Make_TimeStamp from a forEach loop.	*/
347 static void
348 MakeTimeStamp(void *parent, void *child)
349 {
350     Make_TimeStamp((GNode *)parent, (GNode *)child);
351 }
352 
353 bool
354 Make_OODate(GNode *gn)
355 {
356 	bool	    oodate;
357 
358 	/*
359 	 * Certain types of targets needn't even be sought as their datedness
360 	 * doesn't depend on their modification time...
361 	 */
362 	if ((gn->type & (OP_JOIN|OP_USE|OP_EXEC|OP_PHONY)) == 0) {
363 		(void)Dir_MTime(gn);
364 		if (DEBUG(MAKE)) {
365 			if (!is_out_of_date(gn->mtime))
366 				printf("modified %s...",
367 				    time_to_string(gn->mtime));
368 			else
369 				printf("non-existent...");
370 		}
371 	}
372 
373 	/*
374 	 * A target is remade in one of the following circumstances:
375 	 * - its modification time is smaller than that of its youngest child
376 	 *   and it would actually be run (has commands or type OP_NOP)
377 	 * - it's the object of a force operator
378 	 * - it has no children, was on the lhs of an operator and doesn't
379 	 *   exist already.
380 	 *
381 	 * Libraries are only considered out-of-date if the archive module says
382 	 * they are.
383 	 */
384 	if (gn->type & OP_USE) {
385 		/*
386 		 * If the node is a USE node it is *never* out of date
387 		 * no matter *what*.
388 		 */
389 		if (DEBUG(MAKE))
390 			printf(".USE node...");
391 		oodate = false;
392 	} else if ((gn->type & OP_LIB) && Arch_IsLib(gn)) {
393 		if (DEBUG(MAKE))
394 		    printf("library...");
395 
396 		/* always out of date if no children and :: target */
397 		oodate = Arch_LibOODate(gn) ||
398 		    (is_out_of_date(gn->cmtime) && (gn->type & OP_DOUBLEDEP));
399 	} else if (gn->type & OP_JOIN) {
400 		/*
401 		 * A target with the .JOIN attribute is only considered
402 		 * out-of-date if any of its children was out-of-date.
403 		 */
404 		if (DEBUG(MAKE))
405 			printf(".JOIN node...");
406 		oodate = gn->childMade;
407 	} else if (gn->type & (OP_FORCE|OP_EXEC|OP_PHONY)) {
408 		/*
409 		 * A node which is the object of the force (!) operator or which
410 		 * has the .EXEC attribute is always considered out-of-date.
411 		 */
412 		if (DEBUG(MAKE)) {
413 			if (gn->type & OP_FORCE)
414 				printf("! operator...");
415 			else if (gn->type & OP_PHONY)
416 				printf(".PHONY node...");
417 			else
418 				printf(".EXEC node...");
419 		}
420 		oodate = true;
421 	} else if (is_strictly_before(gn->mtime, gn->cmtime) ||
422 	   (is_out_of_date(gn->cmtime) &&
423 	    (is_out_of_date(gn->mtime) || (gn->type & OP_DOUBLEDEP)))) {
424 		/*
425 		 * A node whose modification time is less than that of its
426 		 * youngest child or that has no children (cmtime ==
427 		 * OUT_OF_DATE) and either doesn't exist (mtime == OUT_OF_DATE)
428 		 * or was the object of a :: operator is out-of-date.
429 		 */
430 		if (DEBUG(MAKE)) {
431 			if (is_strictly_before(gn->mtime, gn->cmtime))
432 				printf("modified before source...");
433 			else if (is_out_of_date(gn->mtime))
434 				printf("non-existent and no sources...");
435 			else
436 				printf(":: operator and no sources...");
437 		}
438 		oodate = true;
439 	} else {
440 		oodate = false;
441 	}
442 
443 	/*
444 	 * If the target isn't out-of-date, the parents need to know its
445 	 * modification time. Note that targets that appear to be out-of-date
446 	 * but aren't, because they have no commands and aren't of type OP_NOP,
447 	 * have their mtime stay below their children's mtime to keep parents
448 	 * from thinking they're out-of-date.
449 	 */
450 	if (!oodate)
451 		Lst_ForEach(&gn->parents, MakeTimeStamp, gn);
452 
453 	return oodate;
454 }
455 
456 volatile sig_atomic_t got_signal;
457 
458 volatile sig_atomic_t got_SIGINT, got_SIGHUP, got_SIGQUIT,
459     got_SIGTERM, got_SIGTSTP, got_SIGTTOU, got_SIGTTIN, got_SIGWINCH;
460 
461 static void
462 setup_signal(int sig)
463 {
464 	if (signal(sig, SIG_IGN) != SIG_IGN) {
465 		(void)signal(sig, SigHandler);
466 	}
467 }
468 
469 static void
470 setup_all_signals()
471 {
472 	/*
473 	 * Catch the four signals that POSIX specifies if they aren't ignored.
474 	 * handle_signal will take care of calling JobInterrupt if appropriate.
475 	 */
476 	setup_signal(SIGINT);
477 	setup_signal(SIGHUP);
478 	setup_signal(SIGQUIT);
479 	setup_signal(SIGTERM);
480 	/*
481 	 * There are additional signals that need to be caught and passed if
482 	 * either the export system wants to be told directly of signals or if
483 	 * we're giving each job its own process group (since then it won't get
484 	 * signals from the terminal driver as we own the terminal)
485 	 */
486 #if defined(USE_PGRP)
487 	setup_signal(SIGTSTP);
488 	setup_signal(SIGTTOU);
489 	setup_signal(SIGTTIN);
490 	setup_signal(SIGWINCH);
491 #endif
492 }
493 
494 void
495 SigHandler(int sig)
496 {
497 	switch(sig) {
498 	case SIGINT:
499 		got_SIGINT++;
500 		got_signal = 1;
501 		break;
502 	case SIGHUP:
503 		got_SIGHUP++;
504 		got_signal = 1;
505 		break;
506 	case SIGQUIT:
507 		got_SIGQUIT++;
508 		got_signal = 1;
509 		break;
510 	case SIGTERM:
511 		got_SIGTERM++;
512 		got_signal = 1;
513 		break;
514 #ifdef USE_PGRP
515 	case SIGTSTP:
516 		got_SIGTSTP++;
517 		got_signal = 1;
518 		break;
519 	case SIGTTOU:
520 		got_SIGTTOU++;
521 		got_signal = 1;
522 		break;
523 	case SIGTTIN:
524 		got_SIGTTIN++;
525 		got_signal = 1;
526 		break;
527 	case SIGWINCH:
528 		got_SIGWINCH++;
529 		got_signal = 1;
530 		break;
531 #endif
532 	}
533 }
534 
535 /* The following array is used to make a fast determination of which
536  * characters are interpreted specially by the shell.  If a command
537  * contains any of these characters, it is executed by the shell, not
538  * directly by us.  */
539 static char	    meta[256];
540 
541 void
542 setup_meta(void)
543 {
544 	char *p;
545 
546 	for (p = "#=|^(){};&<>*?[]:$`\\\n"; *p != '\0'; p++)
547 		meta[(unsigned char) *p] = 1;
548 	/* The null character serves as a sentinel in the string.  */
549 	meta[0] = 1;
550 }
551 
552 static char **
553 recheck_command_for_shell(char **av)
554 {
555 	char *runsh[] = {
556 		"alias", "cd", "eval", "exit", "read", "set", "ulimit",
557 		"unalias", "unset", "wait", "umask", NULL
558 	};
559 
560 	char **p;
561 
562 	/* optimization: if exec cmd, we avoid the intermediate shell */
563 	if (strcmp(av[0], "exec") == 0)
564 		av++;
565 
566 	for (p = runsh; *p; p++)
567 		if (strcmp(av[0], *p) == 0)
568 			return NULL;
569 
570 	return av;
571 }
572 
573 static void
574 run_command(const char *cmd, bool errCheck)
575 {
576 	const char *p;
577 	char *shargv[4];
578 	char **todo;
579 
580 	shargv[0] = _PATH_BSHELL;
581 
582 	shargv[1] = errCheck ? "-ec" : "-c";
583 	shargv[2] = (char *)cmd;
584 	shargv[3] = NULL;
585 
586 	todo = shargv;
587 
588 
589 	/* Search for meta characters in the command. If there are no meta
590 	 * characters, there's no need to execute a shell to execute the
591 	 * command.  */
592 	for (p = cmd; !meta[(unsigned char)*p]; p++)
593 		continue;
594 	if (*p == '\0') {
595 		char *bp;
596 		char **av;
597 		int argc;
598 		/* No meta-characters, so probably no need to exec a shell.
599 		 * Break the command into words to form an argument vector
600 		 * we can execute.  */
601 		av = brk_string(cmd, &argc, &bp);
602 		av = recheck_command_for_shell(av);
603 		if (av != NULL)
604 			todo = av;
605 	}
606 	execvp(todo[0], todo);
607 
608 	if (errno == ENOENT)
609 		fprintf(stderr, "%s: not found\n", todo[0]);
610 	else
611 		perror(todo[0]);
612 	_exit(1);
613 }
614 
615 /*-
616  *-----------------------------------------------------------------------
617  * setup_and_run_command --
618  *	Execute the next command for a target. If the command returns an
619  *	error, the node's built_status field is set to ERROR and creation stops.
620  *
621  * Results:
622  *	0 in case of error, 1 if ok.
623  *
624  * Side Effects:
625  *	The node's 'built_status' field may be set to ERROR.
626  *-----------------------------------------------------------------------
627  */
628 static int
629 setup_and_run_command(char *cmd, GNode *gn, int dont_fork)
630 {
631 	bool silent;	/* Don't print command */
632 	bool doExecute;	/* Execute the command */
633 	bool errCheck;	/* Check errors */
634 	int reason;	/* Reason for child's death */
635 	int status;	/* Description of child's death */
636 	pid_t cpid; 	/* Child actually found */
637 	pid_t stat;	/* Status of fork */
638 
639 	silent = gn->type & OP_SILENT;
640 	errCheck = !(gn->type & OP_IGNORE);
641 	doExecute = !noExecute;
642 
643 	/* How can we execute a null command ? we warn the user that the
644 	 * command expanded to nothing (is this the right thing to do?).  */
645 	if (*cmd == '\0') {
646 		Error("%s expands to empty string", cmd);
647 		return 1;
648 	}
649 
650 	for (;; cmd++) {
651 		if (*cmd == '@')
652 			silent = DEBUG(LOUD) ? false : true;
653 		else if (*cmd == '-')
654 			errCheck = false;
655 		else if (*cmd == '+')
656 			doExecute = true;
657 		else
658 			break;
659 	}
660 	while (isspace(*cmd))
661 		cmd++;
662 	/* Print the command before echoing if we're not supposed to be quiet
663 	 * for this one. We also print the command if -n given.  */
664 	if (!silent || noExecute) {
665 		printf("%s\n", cmd);
666 		fflush(stdout);
667 	}
668 	/* If we're not supposed to execute any commands, this is as far as
669 	 * we go...  */
670 	if (!doExecute)
671 		return 1;
672 
673 	/* if we're running in parallel mode, we try not to fork the last
674 	 * command, since it's exit status will be just fine... unless
675 	 * errCheck is not set, in which case we must deal with the
676 	 * status ourselves.
677 	 */
678 	if (dont_fork && errCheck)
679 		run_command(cmd, errCheck);
680 		/*NOTREACHED*/
681 
682 	/* Fork and execute the single command. If the fork fails, we abort.  */
683 	switch (cpid = fork()) {
684 	case -1:
685 		Fatal("Could not fork");
686 		/*NOTREACHED*/
687 	case 0:
688 		run_command(cmd, errCheck);
689 		/*NOTREACHED*/
690 	default:
691 		break;
692 	}
693 
694 	/* The child is off and running. Now all we can do is wait...  */
695 	while (1) {
696 
697 		while ((stat = wait(&reason)) != cpid) {
698 			if (stat == -1 && errno != EINTR)
699 				break;
700 		}
701 
702 		if (got_signal)
703 			break;
704 
705 		if (stat != -1) {
706 			if (WIFSTOPPED(reason))
707 				status = WSTOPSIG(reason);	/* stopped */
708 			else if (WIFEXITED(reason)) {
709 				status = WEXITSTATUS(reason);	/* exited */
710 				if (status != 0)
711 				    printf("*** Error code %d", status);
712 			} else {
713 				status = WTERMSIG(reason);	/* signaled */
714 				printf("*** Signal %d", status);
715 			}
716 
717 
718 			if (!WIFEXITED(reason) || status != 0) {
719 				if (errCheck) {
720 					gn->built_status = ERROR;
721 					if (keepgoing)
722 						/* Abort the current target,
723 						 * but let others continue.  */
724 						printf(" (continuing)\n");
725 				} else {
726 					/* Continue executing commands for
727 					 * this target.  If we return 0,
728 					 * this will happen...  */
729 					printf(" (ignored)\n");
730 					status = 0;
731 				}
732 			}
733 			return !status;
734 		} else
735 			Fatal("error in wait: %d", stat);
736 			/*NOTREACHED*/
737 	}
738 	return 0;
739 }
740 
741 static void
742 handle_compat_interrupts(GNode *gn)
743 {
744 	if (!Targ_Precious(gn)) {
745 		char *file = Var(TARGET_INDEX, gn);
746 
747 		if (!noExecute && eunlink(file) != -1)
748 			Error("*** %s removed\n", file);
749 	}
750 	if (got_SIGINT) {
751 		signal(SIGINT, SIG_IGN);
752 		signal(SIGTERM, SIG_IGN);
753 		signal(SIGHUP, SIG_IGN);
754 		signal(SIGQUIT, SIG_IGN);
755 		got_signal = 0;
756 		got_SIGINT = 0;
757 		run_gnode(interrupt_node);
758 		exit(255);
759 	}
760 	exit(255);
761 }
762 
763 void
764 expand_commands(GNode *gn)
765 {
766 	LstNode ln;
767 	char *cmd;
768 
769 	for (ln = Lst_First(&gn->commands); ln != NULL; ln = Lst_Adv(ln)) {
770 		cmd = Var_Subst(Lst_Datum(ln), &gn->context, false);
771 		Lst_AtEnd(&gn->expanded, cmd);
772 	}
773 }
774 
775 int
776 run_gnode(GNode *gn)
777 {
778 	if (gn != NULL && (gn->type & OP_DUMMY) == 0) {
779 		expand_commands(gn);
780 	}
781 	return run_prepared_gnode(gn, 0);
782 }
783 
784 int
785 run_prepared_gnode(GNode *gn, int parallel)
786 {
787 	char *cmd;
788 
789 	if (gn != NULL && (gn->type & OP_DUMMY) == 0) {
790 		gn->built_status = MADE;
791 		while ((cmd = Lst_DeQueue(&gn->expanded)) != NULL) {
792 			if (setup_and_run_command(cmd, gn,
793 			    parallel && Lst_IsEmpty(&gn->expanded)) == 0)
794 				break;
795 			free(cmd);
796 		}
797 		free(cmd);
798 		if (got_signal && !parallel)
799 			handle_compat_interrupts(gn);
800 		return gn->built_status;
801 	} else
802 		return NOSUCHNODE;
803 }
804 
805 void
806 setup_engine()
807 {
808 	static int already_setup = 0;
809 
810 	if (!already_setup) {
811 		setup_meta();
812 		setup_all_signals();
813 		already_setup = 1;
814 	}
815 }
816