xref: /freebsd/bin/sh/eval.c (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
1 /*-
2  * Copyright (c) 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  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 #if 0
35 static char sccsid[] = "@(#)eval.c	8.9 (Berkeley) 6/8/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include <paths.h>
42 #include <signal.h>
43 #include <stdlib.h>
44 #include <unistd.h>
45 #include <sys/resource.h>
46 #include <sys/wait.h> /* For WIFSIGNALED(status) */
47 #include <errno.h>
48 
49 /*
50  * Evaluate a command.
51  */
52 
53 #include "shell.h"
54 #include "nodes.h"
55 #include "syntax.h"
56 #include "expand.h"
57 #include "parser.h"
58 #include "jobs.h"
59 #include "eval.h"
60 #include "builtins.h"
61 #include "options.h"
62 #include "exec.h"
63 #include "redir.h"
64 #include "input.h"
65 #include "output.h"
66 #include "trap.h"
67 #include "var.h"
68 #include "memalloc.h"
69 #include "error.h"
70 #include "show.h"
71 #include "mystring.h"
72 #ifndef NO_HISTORY
73 #include "myhistedit.h"
74 #endif
75 
76 
77 /* flags in argument to evaltree */
78 #define EV_EXIT 01		/* exit after evaluating tree */
79 #define EV_TESTED 02		/* exit status is checked; ignore -e flag */
80 #define EV_BACKCMD 04		/* command executing within back quotes */
81 
82 MKINIT int evalskip;		/* set if we are skipping commands */
83 STATIC int skipcount;		/* number of levels to skip */
84 MKINIT int loopnest;		/* current loop nesting level */
85 int funcnest;			/* depth of function calls */
86 
87 
88 char *commandname;
89 struct strlist *cmdenviron;
90 int exitstatus;			/* exit status of last command */
91 int oexitstatus;		/* saved exit status */
92 
93 
94 STATIC void evalloop(union node *, int);
95 STATIC void evalfor(union node *, int);
96 STATIC void evalcase(union node *, int);
97 STATIC void evalsubshell(union node *, int);
98 STATIC void expredir(union node *);
99 STATIC void evalpipe(union node *);
100 STATIC void evalcommand(union node *, int, struct backcmd *);
101 STATIC void prehash(union node *);
102 
103 
104 /*
105  * Called to reset things after an exception.
106  */
107 
108 #ifdef mkinit
109 INCLUDE "eval.h"
110 
111 RESET {
112 	evalskip = 0;
113 	loopnest = 0;
114 	funcnest = 0;
115 }
116 
117 SHELLPROC {
118 	exitstatus = 0;
119 }
120 #endif
121 
122 
123 
124 /*
125  * The eval command.
126  */
127 
128 int
129 evalcmd(int argc, char **argv)
130 {
131         char *p;
132         char *concat;
133         char **ap;
134 
135         if (argc > 1) {
136                 p = argv[1];
137                 if (argc > 2) {
138                         STARTSTACKSTR(concat);
139                         ap = argv + 2;
140                         for (;;) {
141                                 while (*p)
142                                         STPUTC(*p++, concat);
143                                 if ((p = *ap++) == NULL)
144                                         break;
145                                 STPUTC(' ', concat);
146                         }
147                         STPUTC('\0', concat);
148                         p = grabstackstr(concat);
149                 }
150                 evalstring(p);
151         }
152         return exitstatus;
153 }
154 
155 
156 /*
157  * Execute a command or commands contained in a string.
158  */
159 
160 void
161 evalstring(char *s)
162 {
163 	union node *n;
164 	struct stackmark smark;
165 
166 	setstackmark(&smark);
167 	setinputstring(s, 1);
168 	while ((n = parsecmd(0)) != NEOF) {
169 		evaltree(n, 0);
170 		popstackmark(&smark);
171 	}
172 	popfile();
173 	popstackmark(&smark);
174 }
175 
176 
177 
178 /*
179  * Evaluate a parse tree.  The value is left in the global variable
180  * exitstatus.
181  */
182 
183 void
184 evaltree(union node *n, int flags)
185 {
186 	int do_etest;
187 
188 	do_etest = 0;
189 	if (n == NULL) {
190 		TRACE(("evaltree(NULL) called\n"));
191 		exitstatus = 0;
192 		goto out;
193 	}
194 #ifndef NO_HISTORY
195 	displayhist = 1;	/* show history substitutions done with fc */
196 #endif
197 	TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
198 	switch (n->type) {
199 	case NSEMI:
200 		evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
201 		if (evalskip)
202 			goto out;
203 		evaltree(n->nbinary.ch2, flags);
204 		break;
205 	case NAND:
206 		evaltree(n->nbinary.ch1, EV_TESTED);
207 		if (evalskip || exitstatus != 0) {
208 			goto out;
209 		}
210 		evaltree(n->nbinary.ch2, flags);
211 		break;
212 	case NOR:
213 		evaltree(n->nbinary.ch1, EV_TESTED);
214 		if (evalskip || exitstatus == 0)
215 			goto out;
216 		evaltree(n->nbinary.ch2, flags);
217 		break;
218 	case NREDIR:
219 		expredir(n->nredir.redirect);
220 		redirect(n->nredir.redirect, REDIR_PUSH);
221 		evaltree(n->nredir.n, flags);
222 		popredir();
223 		break;
224 	case NSUBSHELL:
225 		evalsubshell(n, flags);
226 		do_etest = !(flags & EV_TESTED);
227 		break;
228 	case NBACKGND:
229 		evalsubshell(n, flags);
230 		break;
231 	case NIF: {
232 		evaltree(n->nif.test, EV_TESTED);
233 		if (evalskip)
234 			goto out;
235 		if (exitstatus == 0)
236 			evaltree(n->nif.ifpart, flags);
237 		else if (n->nif.elsepart)
238 			evaltree(n->nif.elsepart, flags);
239 		else
240 			exitstatus = 0;
241 		break;
242 	}
243 	case NWHILE:
244 	case NUNTIL:
245 		evalloop(n, flags & ~EV_EXIT);
246 		break;
247 	case NFOR:
248 		evalfor(n, flags & ~EV_EXIT);
249 		break;
250 	case NCASE:
251 		evalcase(n, flags);
252 		break;
253 	case NDEFUN:
254 		defun(n->narg.text, n->narg.next);
255 		exitstatus = 0;
256 		break;
257 	case NNOT:
258 		evaltree(n->nnot.com, EV_TESTED);
259 		exitstatus = !exitstatus;
260 		break;
261 
262 	case NPIPE:
263 		evalpipe(n);
264 		do_etest = !(flags & EV_TESTED);
265 		break;
266 	case NCMD:
267 		evalcommand(n, flags, (struct backcmd *)NULL);
268 		do_etest = !(flags & EV_TESTED);
269 		break;
270 	default:
271 		out1fmt("Node type = %d\n", n->type);
272 		flushout(&output);
273 		break;
274 	}
275 out:
276 	if (pendingsigs)
277 		dotrap();
278 	if ((flags & EV_EXIT) || (eflag && exitstatus != 0 && do_etest))
279 		exitshell(exitstatus);
280 }
281 
282 
283 STATIC void
284 evalloop(union node *n, int flags)
285 {
286 	int status;
287 
288 	loopnest++;
289 	status = 0;
290 	for (;;) {
291 		evaltree(n->nbinary.ch1, EV_TESTED);
292 		if (evalskip) {
293 skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
294 				evalskip = 0;
295 				continue;
296 			}
297 			if (evalskip == SKIPBREAK && --skipcount <= 0)
298 				evalskip = 0;
299 			break;
300 		}
301 		if (n->type == NWHILE) {
302 			if (exitstatus != 0)
303 				break;
304 		} else {
305 			if (exitstatus == 0)
306 				break;
307 		}
308 		evaltree(n->nbinary.ch2, flags);
309 		status = exitstatus;
310 		if (evalskip)
311 			goto skipping;
312 	}
313 	loopnest--;
314 	exitstatus = status;
315 }
316 
317 
318 
319 STATIC void
320 evalfor(union node *n, int flags)
321 {
322 	struct arglist arglist;
323 	union node *argp;
324 	struct strlist *sp;
325 	struct stackmark smark;
326 
327 	setstackmark(&smark);
328 	arglist.lastp = &arglist.list;
329 	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
330 		oexitstatus = exitstatus;
331 		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
332 		if (evalskip)
333 			goto out;
334 	}
335 	*arglist.lastp = NULL;
336 
337 	exitstatus = 0;
338 	loopnest++;
339 	for (sp = arglist.list ; sp ; sp = sp->next) {
340 		setvar(n->nfor.var, sp->text, 0);
341 		evaltree(n->nfor.body, flags);
342 		if (evalskip) {
343 			if (evalskip == SKIPCONT && --skipcount <= 0) {
344 				evalskip = 0;
345 				continue;
346 			}
347 			if (evalskip == SKIPBREAK && --skipcount <= 0)
348 				evalskip = 0;
349 			break;
350 		}
351 	}
352 	loopnest--;
353 out:
354 	popstackmark(&smark);
355 }
356 
357 
358 
359 STATIC void
360 evalcase(union node *n, int flags)
361 {
362 	union node *cp;
363 	union node *patp;
364 	struct arglist arglist;
365 	struct stackmark smark;
366 
367 	setstackmark(&smark);
368 	arglist.lastp = &arglist.list;
369 	oexitstatus = exitstatus;
370 	exitstatus = 0;
371 	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
372 	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
373 		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
374 			if (casematch(patp, arglist.list->text)) {
375 				if (evalskip == 0) {
376 					evaltree(cp->nclist.body, flags);
377 				}
378 				goto out;
379 			}
380 		}
381 	}
382 out:
383 	popstackmark(&smark);
384 }
385 
386 
387 
388 /*
389  * Kick off a subshell to evaluate a tree.
390  */
391 
392 STATIC void
393 evalsubshell(union node *n, int flags)
394 {
395 	struct job *jp;
396 	int backgnd = (n->type == NBACKGND);
397 
398 	expredir(n->nredir.redirect);
399 	jp = makejob(n, 1);
400 	if (forkshell(jp, n, backgnd) == 0) {
401 		if (backgnd)
402 			flags &=~ EV_TESTED;
403 		redirect(n->nredir.redirect, 0);
404 		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
405 	}
406 	if (! backgnd) {
407 		INTOFF;
408 		exitstatus = waitforjob(jp, (int *)NULL);
409 		INTON;
410 	}
411 }
412 
413 
414 
415 /*
416  * Compute the names of the files in a redirection list.
417  */
418 
419 STATIC void
420 expredir(union node *n)
421 {
422 	union node *redir;
423 
424 	for (redir = n ; redir ; redir = redir->nfile.next) {
425 		struct arglist fn;
426 		fn.lastp = &fn.list;
427 		oexitstatus = exitstatus;
428 		switch (redir->type) {
429 		case NFROM:
430 		case NTO:
431 		case NFROMTO:
432 		case NAPPEND:
433 		case NCLOBBER:
434 			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
435 			redir->nfile.expfname = fn.list->text;
436 			break;
437 		case NFROMFD:
438 		case NTOFD:
439 			if (redir->ndup.vname) {
440 				expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
441 				fixredir(redir, fn.list->text, 1);
442 			}
443 			break;
444 		}
445 	}
446 }
447 
448 
449 
450 /*
451  * Evaluate a pipeline.  All the processes in the pipeline are children
452  * of the process creating the pipeline.  (This differs from some versions
453  * of the shell, which make the last process in a pipeline the parent
454  * of all the rest.)
455  */
456 
457 STATIC void
458 evalpipe(union node *n)
459 {
460 	struct job *jp;
461 	struct nodelist *lp;
462 	int pipelen;
463 	int prevfd;
464 	int pip[2];
465 
466 	TRACE(("evalpipe(%p) called\n", (void *)n));
467 	pipelen = 0;
468 	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
469 		pipelen++;
470 	INTOFF;
471 	jp = makejob(n, pipelen);
472 	prevfd = -1;
473 	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
474 		prehash(lp->n);
475 		pip[1] = -1;
476 		if (lp->next) {
477 			if (pipe(pip) < 0) {
478 				close(prevfd);
479 				error("Pipe call failed: %s", strerror(errno));
480 			}
481 		}
482 		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
483 			INTON;
484 			if (prevfd > 0) {
485 				dup2(prevfd, 0);
486 				close(prevfd);
487 			}
488 			if (pip[1] >= 0) {
489 				if (!(prevfd >= 0 && pip[0] == 0))
490 					close(pip[0]);
491 				if (pip[1] != 1) {
492 					dup2(pip[1], 1);
493 					close(pip[1]);
494 				}
495 			}
496 			evaltree(lp->n, EV_EXIT);
497 		}
498 		if (prevfd >= 0)
499 			close(prevfd);
500 		prevfd = pip[0];
501 		close(pip[1]);
502 	}
503 	INTON;
504 	if (n->npipe.backgnd == 0) {
505 		INTOFF;
506 		exitstatus = waitforjob(jp, (int *)NULL);
507 		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
508 		INTON;
509 	}
510 }
511 
512 
513 
514 /*
515  * Execute a command inside back quotes.  If it's a builtin command, we
516  * want to save its output in a block obtained from malloc.  Otherwise
517  * we fork off a subprocess and get the output of the command via a pipe.
518  * Should be called with interrupts off.
519  */
520 
521 void
522 evalbackcmd(union node *n, struct backcmd *result)
523 {
524 	int pip[2];
525 	struct job *jp;
526 	struct stackmark smark;		/* unnecessary */
527 
528 	setstackmark(&smark);
529 	result->fd = -1;
530 	result->buf = NULL;
531 	result->nleft = 0;
532 	result->jp = NULL;
533 	if (n == NULL) {
534 		exitstatus = 0;
535 		goto out;
536 	}
537 	if (n->type == NCMD) {
538 		exitstatus = oexitstatus;
539 		evalcommand(n, EV_BACKCMD, result);
540 	} else {
541 		exitstatus = 0;
542 		if (pipe(pip) < 0)
543 			error("Pipe call failed: %s", strerror(errno));
544 		jp = makejob(n, 1);
545 		if (forkshell(jp, n, FORK_NOJOB) == 0) {
546 			FORCEINTON;
547 			close(pip[0]);
548 			if (pip[1] != 1) {
549 				dup2(pip[1], 1);
550 				close(pip[1]);
551 			}
552 			evaltree(n, EV_EXIT);
553 		}
554 		close(pip[1]);
555 		result->fd = pip[0];
556 		result->jp = jp;
557 	}
558 out:
559 	popstackmark(&smark);
560 	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
561 		result->fd, result->buf, result->nleft, result->jp));
562 }
563 
564 
565 
566 /*
567  * Execute a simple command.
568  */
569 
570 STATIC void
571 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
572 {
573 	struct stackmark smark;
574 	union node *argp;
575 	struct arglist arglist;
576 	struct arglist varlist;
577 	char **argv;
578 	int argc;
579 	char **envp;
580 	int varflag;
581 	struct strlist *sp;
582 	int mode;
583 	int pip[2];
584 	struct cmdentry cmdentry;
585 	struct job *jp;
586 	struct jmploc jmploc;
587 	struct jmploc *volatile savehandler;
588 	char *volatile savecmdname;
589 	volatile struct shparam saveparam;
590 	struct localvar *volatile savelocalvars;
591 	volatile int e;
592 	char *lastarg;
593 	int realstatus;
594 	int do_clearcmdentry;
595 #if __GNUC__
596 	/* Avoid longjmp clobbering */
597 	(void) &argv;
598 	(void) &argc;
599 	(void) &lastarg;
600 	(void) &flags;
601 	(void) &do_clearcmdentry;
602 #endif
603 
604 	/* First expand the arguments. */
605 	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
606 	setstackmark(&smark);
607 	arglist.lastp = &arglist.list;
608 	varlist.lastp = &varlist.list;
609 	varflag = 1;
610 	do_clearcmdentry = 0;
611 	oexitstatus = exitstatus;
612 	exitstatus = 0;
613 	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
614 		char *p = argp->narg.text;
615 		if (varflag && is_name(*p)) {
616 			do {
617 				p++;
618 			} while (is_in_name(*p));
619 			if (*p == '=') {
620 				expandarg(argp, &varlist, EXP_VARTILDE);
621 				continue;
622 			}
623 		}
624 		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
625 		varflag = 0;
626 	}
627 	*arglist.lastp = NULL;
628 	*varlist.lastp = NULL;
629 	expredir(cmd->ncmd.redirect);
630 	argc = 0;
631 	for (sp = arglist.list ; sp ; sp = sp->next)
632 		argc++;
633 	argv = stalloc(sizeof (char *) * (argc + 1));
634 
635 	for (sp = arglist.list ; sp ; sp = sp->next) {
636 		TRACE(("evalcommand arg: %s\n", sp->text));
637 		*argv++ = sp->text;
638 	}
639 	*argv = NULL;
640 	lastarg = NULL;
641 	if (iflag && funcnest == 0 && argc > 0)
642 		lastarg = argv[-1];
643 	argv -= argc;
644 
645 	/* Print the command if xflag is set. */
646 	if (xflag) {
647 		char sep = 0;
648 		out2str(ps4val());
649 		for (sp = varlist.list ; sp ; sp = sp->next) {
650 			if (sep != 0)
651 				outc(' ', &errout);
652 			out2str(sp->text);
653 			sep = ' ';
654 		}
655 		for (sp = arglist.list ; sp ; sp = sp->next) {
656 			if (sep != 0)
657 				outc(' ', &errout);
658 			out2str(sp->text);
659 			sep = ' ';
660 		}
661 		outc('\n', &errout);
662 		flushout(&errout);
663 	}
664 
665 	/* Now locate the command. */
666 	if (argc == 0) {
667 		/* Variable assignment(s) without command */
668 		cmdentry.cmdtype = CMDBUILTIN;
669 		cmdentry.u.index = BLTINCMD;
670 		cmdentry.special = 1;
671 	} else {
672 		static const char PATH[] = "PATH=";
673 		char *path = pathval();
674 
675 		/*
676 		 * Modify the command lookup path, if a PATH= assignment
677 		 * is present
678 		 */
679 		for (sp = varlist.list ; sp ; sp = sp->next)
680 			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
681 				path = sp->text + sizeof(PATH) - 1;
682 				/*
683 				 * On `PATH=... command`, we need to make
684 				 * sure that the command isn't using the
685 				 * non-updated hash table of the outer PATH
686 				 * setting and we need to make sure that
687 				 * the hash table isn't filled with items
688 				 * from the temporary setting.
689 				 *
690 				 * It would be better to forbit using and
691 				 * updating the table while this command
692 				 * runs, by the command finding mechanism
693 				 * is heavily integrated with hash handling,
694 				 * so we just delete the hash before and after
695 				 * the command runs. Partly deleting like
696 				 * changepatch() does doesn't seem worth the
697 				 * bookinging effort, since most such runs add
698 				 * directories in front of the new PATH.
699 				 */
700 				clearcmdentry(0);
701 				do_clearcmdentry = 1;
702 			}
703 
704 		find_command(argv[0], &cmdentry, 1, path);
705 		if (cmdentry.cmdtype == CMDUNKNOWN) {	/* command not found */
706 			exitstatus = 127;
707 			flushout(&errout);
708 			return;
709 		}
710 		/* implement the bltin builtin here */
711 		if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
712 			for (;;) {
713 				argv++;
714 				if (--argc == 0)
715 					break;
716 				if ((cmdentry.u.index = find_builtin(*argv,
717 				    &cmdentry.special)) < 0) {
718 					outfmt(&errout, "%s: not found\n", *argv);
719 					exitstatus = 127;
720 					flushout(&errout);
721 					return;
722 				}
723 				if (cmdentry.u.index != BLTINCMD)
724 					break;
725 			}
726 		}
727 	}
728 
729 	/* Fork off a child process if necessary. */
730 	if (cmd->ncmd.backgnd
731 	 || (cmdentry.cmdtype == CMDNORMAL
732 	    && ((flags & EV_EXIT) == 0 || Tflag))
733 	 || ((flags & EV_BACKCMD) != 0
734 	    && (cmdentry.cmdtype != CMDBUILTIN
735 		 || cmdentry.u.index == CDCMD
736 		 || cmdentry.u.index == DOTCMD
737 		 || cmdentry.u.index == EVALCMD))
738 	 || (cmdentry.cmdtype == CMDBUILTIN &&
739 	    cmdentry.u.index == COMMANDCMD)) {
740 		jp = makejob(cmd, 1);
741 		mode = cmd->ncmd.backgnd;
742 		if (flags & EV_BACKCMD) {
743 			mode = FORK_NOJOB;
744 			if (pipe(pip) < 0)
745 				error("Pipe call failed: %s", strerror(errno));
746 		}
747 		if (forkshell(jp, cmd, mode) != 0)
748 			goto parent;	/* at end of routine */
749 		if (flags & EV_BACKCMD) {
750 			FORCEINTON;
751 			close(pip[0]);
752 			if (pip[1] != 1) {
753 				dup2(pip[1], 1);
754 				close(pip[1]);
755 			}
756 		}
757 		flags |= EV_EXIT;
758 	}
759 
760 	/* This is the child process if a fork occurred. */
761 	/* Execute the command. */
762 	if (cmdentry.cmdtype == CMDFUNCTION) {
763 #ifdef DEBUG
764 		trputs("Shell function:  ");  trargs(argv);
765 #endif
766 		redirect(cmd->ncmd.redirect, REDIR_PUSH);
767 		saveparam = shellparam;
768 		shellparam.malloc = 0;
769 		shellparam.reset = 1;
770 		shellparam.nparam = argc - 1;
771 		shellparam.p = argv + 1;
772 		shellparam.optnext = NULL;
773 		INTOFF;
774 		savelocalvars = localvars;
775 		localvars = NULL;
776 		INTON;
777 		if (setjmp(jmploc.loc)) {
778 			if (exception == EXSHELLPROC)
779 				freeparam((struct shparam *)&saveparam);
780 			else {
781 				freeparam(&shellparam);
782 				shellparam = saveparam;
783 			}
784 			poplocalvars();
785 			localvars = savelocalvars;
786 			handler = savehandler;
787 			longjmp(handler->loc, 1);
788 		}
789 		savehandler = handler;
790 		handler = &jmploc;
791 		for (sp = varlist.list ; sp ; sp = sp->next)
792 			mklocal(sp->text);
793 		funcnest++;
794 		exitstatus = oexitstatus;
795 		if (flags & EV_TESTED)
796 			evaltree(cmdentry.u.func, EV_TESTED);
797 		else
798 			evaltree(cmdentry.u.func, 0);
799 		funcnest--;
800 		INTOFF;
801 		poplocalvars();
802 		localvars = savelocalvars;
803 		freeparam(&shellparam);
804 		shellparam = saveparam;
805 		handler = savehandler;
806 		popredir();
807 		INTON;
808 		if (evalskip == SKIPFUNC) {
809 			evalskip = 0;
810 			skipcount = 0;
811 		}
812 		if (flags & EV_EXIT)
813 			exitshell(exitstatus);
814 	} else if (cmdentry.cmdtype == CMDBUILTIN) {
815 #ifdef DEBUG
816 		trputs("builtin command:  ");  trargs(argv);
817 #endif
818 		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
819 		if (flags == EV_BACKCMD) {
820 			memout.nleft = 0;
821 			memout.nextc = memout.buf;
822 			memout.bufsize = 64;
823 			mode |= REDIR_BACKQ;
824 		}
825 		savecmdname = commandname;
826 		cmdenviron = varlist.list;
827 		e = -1;
828 		if (setjmp(jmploc.loc)) {
829 			e = exception;
830 			exitstatus = (e == EXINT)? SIGINT+128 : 2;
831 			goto cmddone;
832 		}
833 		savehandler = handler;
834 		handler = &jmploc;
835 		redirect(cmd->ncmd.redirect, mode);
836 		if (cmdentry.special)
837 			listsetvar(cmdenviron);
838 		commandname = argv[0];
839 		argptr = argv + 1;
840 		optptr = NULL;			/* initialize nextopt */
841 		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
842 		flushall();
843 cmddone:
844 		cmdenviron = NULL;
845 		out1 = &output;
846 		out2 = &errout;
847 		freestdout();
848 		if (e != EXSHELLPROC) {
849 			commandname = savecmdname;
850 			if (flags & EV_EXIT) {
851 				exitshell(exitstatus);
852 			}
853 		}
854 		handler = savehandler;
855 		if (e != -1) {
856 			if ((e != EXERROR && e != EXEXEC)
857 			    || cmdentry.special)
858 				exraise(e);
859 			FORCEINTON;
860 		}
861 		if (cmdentry.u.index != EXECCMD)
862 			popredir();
863 		if (flags == EV_BACKCMD) {
864 			backcmd->buf = memout.buf;
865 			backcmd->nleft = memout.nextc - memout.buf;
866 			memout.buf = NULL;
867 		}
868 	} else {
869 #ifdef DEBUG
870 		trputs("normal command:  ");  trargs(argv);
871 #endif
872 		clearredir();
873 		redirect(cmd->ncmd.redirect, 0);
874 		for (sp = varlist.list ; sp ; sp = sp->next)
875 			setvareq(sp->text, VEXPORT|VSTACK);
876 		envp = environment();
877 		shellexec(argv, envp, pathval(), cmdentry.u.index);
878 		/*NOTREACHED*/
879 	}
880 	goto out;
881 
882 parent:	/* parent process gets here (if we forked) */
883 	if (mode == 0) {	/* argument to fork */
884 		INTOFF;
885 		exitstatus = waitforjob(jp, &realstatus);
886 		INTON;
887 		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
888 			evalskip = SKIPBREAK;
889 			skipcount = loopnest;
890 		}
891 	} else if (mode == 2) {
892 		backcmd->fd = pip[0];
893 		close(pip[1]);
894 		backcmd->jp = jp;
895 	}
896 
897 out:
898 	if (lastarg)
899 		setvar("_", lastarg, 0);
900 	if (do_clearcmdentry)
901 		clearcmdentry(0);
902 	popstackmark(&smark);
903 }
904 
905 
906 
907 /*
908  * Search for a command.  This is called before we fork so that the
909  * location of the command will be available in the parent as well as
910  * the child.  The check for "goodname" is an overly conservative
911  * check that the name will not be subject to expansion.
912  */
913 
914 STATIC void
915 prehash(union node *n)
916 {
917 	struct cmdentry entry;
918 
919 	if (n && n->type == NCMD && n->ncmd.args)
920 		if (goodname(n->ncmd.args->narg.text))
921 			find_command(n->ncmd.args->narg.text, &entry, 0,
922 				     pathval());
923 }
924 
925 
926 
927 /*
928  * Builtin commands.  Builtin commands whose functions are closely
929  * tied to evaluation are implemented here.
930  */
931 
932 /*
933  * No command given, or a bltin command with no arguments.
934  */
935 
936 int
937 bltincmd(int argc __unused, char **argv __unused)
938 {
939 	/*
940 	 * Preserve exitstatus of a previous possible redirection
941 	 * as POSIX mandates
942 	 */
943 	return exitstatus;
944 }
945 
946 
947 /*
948  * Handle break and continue commands.  Break, continue, and return are
949  * all handled by setting the evalskip flag.  The evaluation routines
950  * above all check this flag, and if it is set they start skipping
951  * commands rather than executing them.  The variable skipcount is
952  * the number of loops to break/continue, or the number of function
953  * levels to return.  (The latter is always 1.)  It should probably
954  * be an error to break out of more loops than exist, but it isn't
955  * in the standard shell so we don't make it one here.
956  */
957 
958 int
959 breakcmd(int argc, char **argv)
960 {
961 	int n = argc > 1 ? number(argv[1]) : 1;
962 
963 	if (n > loopnest)
964 		n = loopnest;
965 	if (n > 0) {
966 		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
967 		skipcount = n;
968 	}
969 	return 0;
970 }
971 
972 /*
973  * The `command' command.
974  */
975 int
976 commandcmd(int argc, char **argv)
977 {
978 	static char stdpath[] = _PATH_STDPATH;
979 	struct jmploc loc, *old;
980 	struct strlist *sp;
981 	char *path;
982 	int ch;
983 	int cmd = -1;
984 
985 	for (sp = cmdenviron; sp ; sp = sp->next)
986 		setvareq(sp->text, VEXPORT|VSTACK);
987 	path = pathval();
988 
989 	optind = optreset = 1;
990 	opterr = 0;
991 	while ((ch = getopt(argc, argv, "pvV")) != -1) {
992 		switch (ch) {
993 		case 'p':
994 			path = stdpath;
995 			break;
996 		case 'v':
997 			cmd = TYPECMD_SMALLV;
998 			break;
999 		case 'V':
1000 			cmd = TYPECMD_BIGV;
1001 			break;
1002 		case '?':
1003 		default:
1004 			error("unknown option: -%c", optopt);
1005 		}
1006 	}
1007 	argc -= optind;
1008 	argv += optind;
1009 
1010 	if (cmd != -1) {
1011 		if (argc != 1)
1012 			error("wrong number of arguments");
1013 		return typecmd_impl(2, argv - 1, cmd);
1014 	}
1015 	if (argc != 0) {
1016 		old = handler;
1017 		handler = &loc;
1018 		if (setjmp(handler->loc) == 0)
1019 			shellexec(argv, environment(), path, 0);
1020 		handler = old;
1021 		if (exception == EXEXEC)
1022 			exit(exerrno);
1023 		exraise(exception);
1024 	}
1025 
1026 	/*
1027 	 * Do nothing successfully if no command was specified;
1028 	 * ksh also does this.
1029 	 */
1030 	exit(0);
1031 }
1032 
1033 
1034 /*
1035  * The return command.
1036  */
1037 
1038 int
1039 returncmd(int argc, char **argv)
1040 {
1041 	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1042 
1043 	if (funcnest) {
1044 		evalskip = SKIPFUNC;
1045 		skipcount = 1;
1046 	} else {
1047 		/* skip the rest of the file */
1048 		evalskip = SKIPFILE;
1049 		skipcount = 1;
1050 	}
1051 	return ret;
1052 }
1053 
1054 
1055 int
1056 falsecmd(int argc __unused, char **argv __unused)
1057 {
1058 	return 1;
1059 }
1060 
1061 
1062 int
1063 truecmd(int argc __unused, char **argv __unused)
1064 {
1065 	return 0;
1066 }
1067 
1068 
1069 int
1070 execcmd(int argc, char **argv)
1071 {
1072 	if (argc > 1) {
1073 		struct strlist *sp;
1074 
1075 		iflag = 0;		/* exit on error */
1076 		mflag = 0;
1077 		optschanged();
1078 		for (sp = cmdenviron; sp ; sp = sp->next)
1079 			setvareq(sp->text, VEXPORT|VSTACK);
1080 		shellexec(argv + 1, environment(), pathval(), 0);
1081 
1082 	}
1083 	return 0;
1084 }
1085 
1086 
1087 int
1088 timescmd(int argc __unused, char **argv __unused)
1089 {
1090 	struct rusage ru;
1091 	long shumins, shsmins, chumins, chsmins;
1092 	double shusecs, shssecs, chusecs, chssecs;
1093 
1094 	if (getrusage(RUSAGE_SELF, &ru) < 0)
1095 		return 1;
1096 	shumins = ru.ru_utime.tv_sec / 60;
1097 	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1098 	shsmins = ru.ru_stime.tv_sec / 60;
1099 	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1100 	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1101 		return 1;
1102 	chumins = ru.ru_utime.tv_sec / 60;
1103 	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1104 	chsmins = ru.ru_stime.tv_sec / 60;
1105 	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1106 	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1107 	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1108 	return 0;
1109 }
1110