eval.c revision 287750 
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
35static char sccsid[] = "@(#)eval.c	8.9 (Berkeley) 6/8/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: stable/10/bin/sh/eval.c 287750 2015-09-13 13:43:08Z jilles $");
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
77int evalskip;			/* set if we are skipping commands */
78int skipcount;			/* number of levels to skip */
79static int loopnest;		/* current loop nesting level */
80int funcnest;			/* depth of function calls */
81static int builtin_flags;	/* evalcommand flags for builtins */
82
83
84char *commandname;
85struct strlist *cmdenviron;
86int exitstatus;			/* exit status of last command */
87int oexitstatus;		/* saved exit status */
88
89
90static void evalloop(union node *, int);
91static void evalfor(union node *, int);
92static union node *evalcase(union node *);
93static void evalsubshell(union node *, int);
94static void evalredir(union node *, int);
95static void exphere(union node *, struct arglist *);
96static void expredir(union node *);
97static void evalpipe(union node *);
98static int is_valid_fast_cmdsubst(union node *n);
99static void evalcommand(union node *, int, struct backcmd *);
100static void prehash(union node *);
101
102
103/*
104 * Called to reset things after an exception.
105 */
106
107void
108reseteval(void)
109{
110	evalskip = 0;
111	loopnest = 0;
112}
113
114
115/*
116 * The eval command.
117 */
118
119int
120evalcmd(int argc, char **argv)
121{
122        char *p;
123        char *concat;
124        char **ap;
125
126        if (argc > 1) {
127                p = argv[1];
128                if (argc > 2) {
129                        STARTSTACKSTR(concat);
130                        ap = argv + 2;
131                        for (;;) {
132                                STPUTS(p, concat);
133                                if ((p = *ap++) == NULL)
134                                        break;
135                                STPUTC(' ', concat);
136                        }
137                        STPUTC('\0', concat);
138                        p = grabstackstr(concat);
139                }
140                evalstring(p, builtin_flags);
141        } else
142                exitstatus = 0;
143        return exitstatus;
144}
145
146
147/*
148 * Execute a command or commands contained in a string.
149 */
150
151void
152evalstring(char *s, int flags)
153{
154	union node *n;
155	struct stackmark smark;
156	int flags_exit;
157	int any;
158
159	flags_exit = flags & EV_EXIT;
160	flags &= ~EV_EXIT;
161	any = 0;
162	setstackmark(&smark);
163	setinputstring(s, 1);
164	while ((n = parsecmd(0)) != NEOF) {
165		if (n != NULL && !nflag) {
166			if (flags_exit && preadateof())
167				evaltree(n, flags | EV_EXIT);
168			else
169				evaltree(n, flags);
170			any = 1;
171		}
172		popstackmark(&smark);
173		setstackmark(&smark);
174	}
175	popfile();
176	popstackmark(&smark);
177	if (!any)
178		exitstatus = 0;
179	if (flags_exit)
180		exraise(EXEXIT);
181}
182
183
184/*
185 * Evaluate a parse tree.  The value is left in the global variable
186 * exitstatus.
187 */
188
189void
190evaltree(union node *n, int flags)
191{
192	int do_etest;
193	union node *next;
194	struct stackmark smark;
195
196	setstackmark(&smark);
197	do_etest = 0;
198	if (n == NULL) {
199		TRACE(("evaltree(NULL) called\n"));
200		exitstatus = 0;
201		goto out;
202	}
203	do {
204		next = NULL;
205#ifndef NO_HISTORY
206		displayhist = 1;	/* show history substitutions done with fc */
207#endif
208		TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
209		switch (n->type) {
210		case NSEMI:
211			evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
212			if (evalskip)
213				goto out;
214			next = n->nbinary.ch2;
215			break;
216		case NAND:
217			evaltree(n->nbinary.ch1, EV_TESTED);
218			if (evalskip || exitstatus != 0) {
219				goto out;
220			}
221			next = n->nbinary.ch2;
222			break;
223		case NOR:
224			evaltree(n->nbinary.ch1, EV_TESTED);
225			if (evalskip || exitstatus == 0)
226				goto out;
227			next = n->nbinary.ch2;
228			break;
229		case NREDIR:
230			evalredir(n, flags);
231			break;
232		case NSUBSHELL:
233			evalsubshell(n, flags);
234			do_etest = !(flags & EV_TESTED);
235			break;
236		case NBACKGND:
237			evalsubshell(n, flags);
238			break;
239		case NIF: {
240			evaltree(n->nif.test, EV_TESTED);
241			if (evalskip)
242				goto out;
243			if (exitstatus == 0)
244				next = n->nif.ifpart;
245			else if (n->nif.elsepart)
246				next = n->nif.elsepart;
247			else
248				exitstatus = 0;
249			break;
250		}
251		case NWHILE:
252		case NUNTIL:
253			evalloop(n, flags & ~EV_EXIT);
254			break;
255		case NFOR:
256			evalfor(n, flags & ~EV_EXIT);
257			break;
258		case NCASE:
259			next = evalcase(n);
260			break;
261		case NCLIST:
262			next = n->nclist.body;
263			break;
264		case NCLISTFALLTHRU:
265			if (n->nclist.body) {
266				evaltree(n->nclist.body, flags & ~EV_EXIT);
267				if (evalskip)
268					goto out;
269			}
270			next = n->nclist.next;
271			break;
272		case NDEFUN:
273			defun(n->narg.text, n->narg.next);
274			exitstatus = 0;
275			break;
276		case NNOT:
277			evaltree(n->nnot.com, EV_TESTED);
278			if (evalskip)
279				goto out;
280			exitstatus = !exitstatus;
281			break;
282
283		case NPIPE:
284			evalpipe(n);
285			do_etest = !(flags & EV_TESTED);
286			break;
287		case NCMD:
288			evalcommand(n, flags, (struct backcmd *)NULL);
289			do_etest = !(flags & EV_TESTED);
290			break;
291		default:
292			out1fmt("Node type = %d\n", n->type);
293			flushout(&output);
294			break;
295		}
296		n = next;
297		popstackmark(&smark);
298		setstackmark(&smark);
299	} while (n != NULL);
300out:
301	popstackmark(&smark);
302	if (pendingsig)
303		dotrap();
304	if (eflag && exitstatus != 0 && do_etest)
305		exitshell(exitstatus);
306	if (flags & EV_EXIT)
307		exraise(EXEXIT);
308}
309
310
311static void
312evalloop(union node *n, int flags)
313{
314	int status;
315
316	loopnest++;
317	status = 0;
318	for (;;) {
319		if (!evalskip)
320			evaltree(n->nbinary.ch1, EV_TESTED);
321		if (evalskip) {
322			if (evalskip == SKIPCONT && --skipcount <= 0) {
323				evalskip = 0;
324				continue;
325			}
326			if (evalskip == SKIPBREAK && --skipcount <= 0)
327				evalskip = 0;
328			if (evalskip == SKIPRETURN)
329				status = exitstatus;
330			break;
331		}
332		if (n->type == NWHILE) {
333			if (exitstatus != 0)
334				break;
335		} else {
336			if (exitstatus == 0)
337				break;
338		}
339		evaltree(n->nbinary.ch2, flags);
340		status = exitstatus;
341	}
342	loopnest--;
343	exitstatus = status;
344}
345
346
347
348static void
349evalfor(union node *n, int flags)
350{
351	struct arglist arglist;
352	union node *argp;
353	struct strlist *sp;
354	int status;
355
356	arglist.lastp = &arglist.list;
357	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
358		oexitstatus = exitstatus;
359		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
360	}
361	*arglist.lastp = NULL;
362
363	loopnest++;
364	status = 0;
365	for (sp = arglist.list ; sp ; sp = sp->next) {
366		setvar(n->nfor.var, sp->text, 0);
367		evaltree(n->nfor.body, flags);
368		status = exitstatus;
369		if (evalskip) {
370			if (evalskip == SKIPCONT && --skipcount <= 0) {
371				evalskip = 0;
372				continue;
373			}
374			if (evalskip == SKIPBREAK && --skipcount <= 0)
375				evalskip = 0;
376			break;
377		}
378	}
379	loopnest--;
380	exitstatus = status;
381}
382
383
384/*
385 * Evaluate a case statement, returning the selected tree.
386 *
387 * The exit status needs care to get right.
388 */
389
390static union node *
391evalcase(union node *n)
392{
393	union node *cp;
394	union node *patp;
395	struct arglist arglist;
396
397	arglist.lastp = &arglist.list;
398	oexitstatus = exitstatus;
399	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
400	for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
401		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
402			if (casematch(patp, arglist.list->text)) {
403				while (cp->nclist.next &&
404				    cp->type == NCLISTFALLTHRU &&
405				    cp->nclist.body == NULL)
406					cp = cp->nclist.next;
407				if (cp->nclist.next &&
408				    cp->type == NCLISTFALLTHRU)
409					return (cp);
410				if (cp->nclist.body == NULL)
411					exitstatus = 0;
412				return (cp->nclist.body);
413			}
414		}
415	}
416	exitstatus = 0;
417	return (NULL);
418}
419
420
421
422/*
423 * Kick off a subshell to evaluate a tree.
424 */
425
426static void
427evalsubshell(union node *n, int flags)
428{
429	struct job *jp;
430	int backgnd = (n->type == NBACKGND);
431
432	oexitstatus = exitstatus;
433	expredir(n->nredir.redirect);
434	if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
435			forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
436		if (backgnd)
437			flags &=~ EV_TESTED;
438		redirect(n->nredir.redirect, 0);
439		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
440	} else if (! backgnd) {
441		INTOFF;
442		exitstatus = waitforjob(jp, (int *)NULL);
443		INTON;
444	} else
445		exitstatus = 0;
446}
447
448
449/*
450 * Evaluate a redirected compound command.
451 */
452
453static void
454evalredir(union node *n, int flags)
455{
456	struct jmploc jmploc;
457	struct jmploc *savehandler;
458	volatile int in_redirect = 1;
459
460	oexitstatus = exitstatus;
461	expredir(n->nredir.redirect);
462	savehandler = handler;
463	if (setjmp(jmploc.loc)) {
464		int e;
465
466		handler = savehandler;
467		e = exception;
468		popredir();
469		if (e == EXERROR || e == EXEXEC) {
470			if (in_redirect) {
471				exitstatus = 2;
472				return;
473			}
474		}
475		longjmp(handler->loc, 1);
476	} else {
477		INTOFF;
478		handler = &jmploc;
479		redirect(n->nredir.redirect, REDIR_PUSH);
480		in_redirect = 0;
481		INTON;
482		evaltree(n->nredir.n, flags);
483	}
484	INTOFF;
485	handler = savehandler;
486	popredir();
487	INTON;
488}
489
490
491static void
492exphere(union node *redir, struct arglist *fn)
493{
494	struct jmploc jmploc;
495	struct jmploc *savehandler;
496	struct localvar *savelocalvars;
497	int need_longjmp = 0;
498
499	redir->nhere.expdoc = nullstr;
500	savelocalvars = localvars;
501	localvars = NULL;
502	forcelocal++;
503	savehandler = handler;
504	if (setjmp(jmploc.loc))
505		need_longjmp = exception != EXERROR && exception != EXEXEC;
506	else {
507		handler = &jmploc;
508		expandarg(redir->nhere.doc, fn, 0);
509		redir->nhere.expdoc = fn->list->text;
510		INTOFF;
511	}
512	handler = savehandler;
513	forcelocal--;
514	poplocalvars();
515	localvars = savelocalvars;
516	if (need_longjmp)
517		longjmp(handler->loc, 1);
518	INTON;
519}
520
521
522/*
523 * Compute the names of the files in a redirection list.
524 */
525
526static void
527expredir(union node *n)
528{
529	union node *redir;
530
531	for (redir = n ; redir ; redir = redir->nfile.next) {
532		struct arglist fn;
533		fn.lastp = &fn.list;
534		switch (redir->type) {
535		case NFROM:
536		case NTO:
537		case NFROMTO:
538		case NAPPEND:
539		case NCLOBBER:
540			expandarg(redir->nfile.fname, &fn, EXP_TILDE);
541			redir->nfile.expfname = fn.list->text;
542			break;
543		case NFROMFD:
544		case NTOFD:
545			if (redir->ndup.vname) {
546				expandarg(redir->ndup.vname, &fn, EXP_TILDE);
547				fixredir(redir, fn.list->text, 1);
548			}
549			break;
550		case NXHERE:
551			exphere(redir, &fn);
552			break;
553		}
554	}
555}
556
557
558
559/*
560 * Evaluate a pipeline.  All the processes in the pipeline are children
561 * of the process creating the pipeline.  (This differs from some versions
562 * of the shell, which make the last process in a pipeline the parent
563 * of all the rest.)
564 */
565
566static void
567evalpipe(union node *n)
568{
569	struct job *jp;
570	struct nodelist *lp;
571	int pipelen;
572	int prevfd;
573	int pip[2];
574
575	TRACE(("evalpipe(%p) called\n", (void *)n));
576	pipelen = 0;
577	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
578		pipelen++;
579	INTOFF;
580	jp = makejob(n, pipelen);
581	prevfd = -1;
582	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
583		prehash(lp->n);
584		pip[1] = -1;
585		if (lp->next) {
586			if (pipe(pip) < 0) {
587				if (prevfd >= 0)
588					close(prevfd);
589				error("Pipe call failed: %s", strerror(errno));
590			}
591		}
592		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
593			INTON;
594			if (prevfd > 0) {
595				dup2(prevfd, 0);
596				close(prevfd);
597			}
598			if (pip[1] >= 0) {
599				if (!(prevfd >= 0 && pip[0] == 0))
600					close(pip[0]);
601				if (pip[1] != 1) {
602					dup2(pip[1], 1);
603					close(pip[1]);
604				}
605			}
606			evaltree(lp->n, EV_EXIT);
607		}
608		if (prevfd >= 0)
609			close(prevfd);
610		prevfd = pip[0];
611		if (pip[1] != -1)
612			close(pip[1]);
613	}
614	INTON;
615	if (n->npipe.backgnd == 0) {
616		INTOFF;
617		exitstatus = waitforjob(jp, (int *)NULL);
618		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
619		INTON;
620	} else
621		exitstatus = 0;
622}
623
624
625
626static int
627is_valid_fast_cmdsubst(union node *n)
628{
629
630	return (n->type == NCMD);
631}
632
633/*
634 * Execute a command inside back quotes.  If it's a builtin command, we
635 * want to save its output in a block obtained from malloc.  Otherwise
636 * we fork off a subprocess and get the output of the command via a pipe.
637 * Should be called with interrupts off.
638 */
639
640void
641evalbackcmd(union node *n, struct backcmd *result)
642{
643	int pip[2];
644	struct job *jp;
645	struct stackmark smark;
646	struct jmploc jmploc;
647	struct jmploc *savehandler;
648	struct localvar *savelocalvars;
649
650	result->fd = -1;
651	result->buf = NULL;
652	result->nleft = 0;
653	result->jp = NULL;
654	if (n == NULL) {
655		exitstatus = 0;
656		return;
657	}
658	setstackmark(&smark);
659	exitstatus = oexitstatus;
660	if (is_valid_fast_cmdsubst(n)) {
661		savelocalvars = localvars;
662		localvars = NULL;
663		forcelocal++;
664		savehandler = handler;
665		if (setjmp(jmploc.loc)) {
666			if (exception == EXERROR || exception == EXEXEC)
667				exitstatus = 2;
668			else if (exception != 0) {
669				handler = savehandler;
670				forcelocal--;
671				poplocalvars();
672				localvars = savelocalvars;
673				longjmp(handler->loc, 1);
674			}
675		} else {
676			handler = &jmploc;
677			evalcommand(n, EV_BACKCMD, result);
678		}
679		handler = savehandler;
680		forcelocal--;
681		poplocalvars();
682		localvars = savelocalvars;
683	} else {
684		if (pipe(pip) < 0)
685			error("Pipe call failed: %s", strerror(errno));
686		jp = makejob(n, 1);
687		if (forkshell(jp, n, FORK_NOJOB) == 0) {
688			FORCEINTON;
689			close(pip[0]);
690			if (pip[1] != 1) {
691				dup2(pip[1], 1);
692				close(pip[1]);
693			}
694			evaltree(n, EV_EXIT);
695		}
696		close(pip[1]);
697		result->fd = pip[0];
698		result->jp = jp;
699	}
700	popstackmark(&smark);
701	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
702		result->fd, result->buf, result->nleft, result->jp));
703}
704
705static int
706mustexpandto(const char *argtext, const char *mask)
707{
708	for (;;) {
709		if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
710			argtext++;
711			continue;
712		}
713		if (*argtext == CTLESC)
714			argtext++;
715		else if (BASESYNTAX[(int)*argtext] == CCTL)
716			return (0);
717		if (*argtext != *mask)
718			return (0);
719		if (*argtext == '\0')
720			return (1);
721		argtext++;
722		mask++;
723	}
724}
725
726static int
727isdeclarationcmd(struct narg *arg)
728{
729	int have_command = 0;
730
731	if (arg == NULL)
732		return (0);
733	while (mustexpandto(arg->text, "command")) {
734		have_command = 1;
735		arg = &arg->next->narg;
736		if (arg == NULL)
737			return (0);
738		/*
739		 * To also allow "command -p" and "command --" as part of
740		 * a declaration command, add code here.
741		 * We do not do this, as ksh does not do it either and it
742		 * is not required by POSIX.
743		 */
744	}
745	return (mustexpandto(arg->text, "export") ||
746	    mustexpandto(arg->text, "readonly") ||
747	    (mustexpandto(arg->text, "local") &&
748		(have_command || !isfunc("local"))));
749}
750
751static void
752xtracecommand(struct arglist *varlist, struct arglist *arglist)
753{
754	struct strlist *sp;
755	char sep = 0;
756	const char *p, *ps4;
757
758	ps4 = expandstr(ps4val());
759	out2str(ps4 != NULL ? ps4 : ps4val());
760	for (sp = varlist->list ; sp ; sp = sp->next) {
761		if (sep != 0)
762			out2c(' ');
763		p = strchr(sp->text, '=');
764		if (p != NULL) {
765			p++;
766			outbin(sp->text, p - sp->text, out2);
767			out2qstr(p);
768		} else
769			out2qstr(sp->text);
770		sep = ' ';
771	}
772	for (sp = arglist->list ; sp ; sp = sp->next) {
773		if (sep != 0)
774			out2c(' ');
775		/* Disambiguate command looking like assignment. */
776		if (sp == arglist->list &&
777				strchr(sp->text, '=') != NULL &&
778				strchr(sp->text, '\'') == NULL) {
779			out2c('\'');
780			out2str(sp->text);
781			out2c('\'');
782		} else
783			out2qstr(sp->text);
784		sep = ' ';
785	}
786	out2c('\n');
787	flushout(&errout);
788}
789
790/*
791 * Check if a builtin can safely be executed in the same process,
792 * even though it should be in a subshell (command substitution).
793 * Note that jobid, jobs, times and trap can show information not
794 * available in a child process; this is deliberate.
795 * The arguments should already have been expanded.
796 */
797static int
798safe_builtin(int idx, int argc, char **argv)
799{
800	if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
801	    idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
802	    idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
803	    idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
804	    idx == TYPECMD)
805		return (1);
806	if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
807	    idx == UMASKCMD)
808		return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
809	if (idx == SETCMD)
810		return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
811		    argv[1][0] == '+') && argv[1][1] == 'o' &&
812		    argv[1][2] == '\0'));
813	return (0);
814}
815
816/*
817 * Execute a simple command.
818 * Note: This may or may not return if (flags & EV_EXIT).
819 */
820
821static void
822evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
823{
824	union node *argp;
825	struct arglist arglist;
826	struct arglist varlist;
827	char **argv;
828	int argc;
829	char **envp;
830	int varflag;
831	struct strlist *sp;
832	int mode;
833	int pip[2];
834	struct cmdentry cmdentry;
835	struct job *jp;
836	struct jmploc jmploc;
837	struct jmploc *savehandler;
838	char *savecmdname;
839	struct shparam saveparam;
840	struct localvar *savelocalvars;
841	struct parsefile *savetopfile;
842	volatile int e;
843	char *lastarg;
844	int realstatus;
845	int do_clearcmdentry;
846	const char *path = pathval();
847
848	/* First expand the arguments. */
849	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
850	arglist.lastp = &arglist.list;
851	varlist.lastp = &varlist.list;
852	varflag = 1;
853	jp = NULL;
854	do_clearcmdentry = 0;
855	oexitstatus = exitstatus;
856	exitstatus = 0;
857	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
858		if (varflag && isassignment(argp->narg.text)) {
859			expandarg(argp, varflag == 1 ? &varlist : &arglist,
860			    EXP_VARTILDE);
861			continue;
862		} else if (varflag == 1)
863			varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
864		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
865	}
866	*arglist.lastp = NULL;
867	*varlist.lastp = NULL;
868	expredir(cmd->ncmd.redirect);
869	argc = 0;
870	for (sp = arglist.list ; sp ; sp = sp->next)
871		argc++;
872	/* Add one slot at the beginning for tryexec(). */
873	argv = stalloc(sizeof (char *) * (argc + 2));
874	argv++;
875
876	for (sp = arglist.list ; sp ; sp = sp->next) {
877		TRACE(("evalcommand arg: %s\n", sp->text));
878		*argv++ = sp->text;
879	}
880	*argv = NULL;
881	lastarg = NULL;
882	if (iflag && funcnest == 0 && argc > 0)
883		lastarg = argv[-1];
884	argv -= argc;
885
886	/* Print the command if xflag is set. */
887	if (xflag)
888		xtracecommand(&varlist, &arglist);
889
890	/* Now locate the command. */
891	if (argc == 0) {
892		/* Variable assignment(s) without command */
893		cmdentry.cmdtype = CMDBUILTIN;
894		cmdentry.u.index = BLTINCMD;
895		cmdentry.special = 0;
896	} else {
897		static const char PATH[] = "PATH=";
898		int cmd_flags = 0, bltinonly = 0;
899
900		/*
901		 * Modify the command lookup path, if a PATH= assignment
902		 * is present
903		 */
904		for (sp = varlist.list ; sp ; sp = sp->next)
905			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
906				path = sp->text + sizeof(PATH) - 1;
907				/*
908				 * On `PATH=... command`, we need to make
909				 * sure that the command isn't using the
910				 * non-updated hash table of the outer PATH
911				 * setting and we need to make sure that
912				 * the hash table isn't filled with items
913				 * from the temporary setting.
914				 *
915				 * It would be better to forbit using and
916				 * updating the table while this command
917				 * runs, by the command finding mechanism
918				 * is heavily integrated with hash handling,
919				 * so we just delete the hash before and after
920				 * the command runs. Partly deleting like
921				 * changepatch() does doesn't seem worth the
922				 * bookinging effort, since most such runs add
923				 * directories in front of the new PATH.
924				 */
925				clearcmdentry();
926				do_clearcmdentry = 1;
927			}
928
929		for (;;) {
930			if (bltinonly) {
931				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
932				if (cmdentry.u.index < 0) {
933					cmdentry.u.index = BLTINCMD;
934					argv--;
935					argc++;
936					break;
937				}
938			} else
939				find_command(argv[0], &cmdentry, cmd_flags, path);
940			/* implement the bltin and command builtins here */
941			if (cmdentry.cmdtype != CMDBUILTIN)
942				break;
943			if (cmdentry.u.index == BLTINCMD) {
944				if (argc == 1)
945					break;
946				argv++;
947				argc--;
948				bltinonly = 1;
949			} else if (cmdentry.u.index == COMMANDCMD) {
950				if (argc == 1)
951					break;
952				if (!strcmp(argv[1], "-p")) {
953					if (argc == 2)
954						break;
955					if (argv[2][0] == '-') {
956						if (strcmp(argv[2], "--"))
957							break;
958						if (argc == 3)
959							break;
960						argv += 3;
961						argc -= 3;
962					} else {
963						argv += 2;
964						argc -= 2;
965					}
966					path = _PATH_STDPATH;
967					clearcmdentry();
968					do_clearcmdentry = 1;
969				} else if (!strcmp(argv[1], "--")) {
970					if (argc == 2)
971						break;
972					argv += 2;
973					argc -= 2;
974				} else if (argv[1][0] == '-')
975					break;
976				else {
977					argv++;
978					argc--;
979				}
980				cmd_flags |= DO_NOFUNC;
981				bltinonly = 0;
982			} else
983				break;
984		}
985		/*
986		 * Special builtins lose their special properties when
987		 * called via 'command'.
988		 */
989		if (cmd_flags & DO_NOFUNC)
990			cmdentry.special = 0;
991	}
992
993	/* Fork off a child process if necessary. */
994	if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
995	    && ((flags & EV_EXIT) == 0 || have_traps()))
996	 || ((flags & EV_BACKCMD) != 0
997	    && (cmdentry.cmdtype != CMDBUILTIN ||
998		 !safe_builtin(cmdentry.u.index, argc, argv)))) {
999		jp = makejob(cmd, 1);
1000		mode = FORK_FG;
1001		if (flags & EV_BACKCMD) {
1002			mode = FORK_NOJOB;
1003			if (pipe(pip) < 0)
1004				error("Pipe call failed: %s", strerror(errno));
1005		}
1006		if (cmdentry.cmdtype == CMDNORMAL &&
1007		    cmd->ncmd.redirect == NULL &&
1008		    varlist.list == NULL &&
1009		    (mode == FORK_FG || mode == FORK_NOJOB) &&
1010		    !disvforkset() && !iflag && !mflag) {
1011			vforkexecshell(jp, argv, environment(), path,
1012			    cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1013			goto parent;
1014		}
1015		if (forkshell(jp, cmd, mode) != 0)
1016			goto parent;	/* at end of routine */
1017		if (flags & EV_BACKCMD) {
1018			FORCEINTON;
1019			close(pip[0]);
1020			if (pip[1] != 1) {
1021				dup2(pip[1], 1);
1022				close(pip[1]);
1023			}
1024			flags &= ~EV_BACKCMD;
1025		}
1026		flags |= EV_EXIT;
1027	}
1028
1029	/* This is the child process if a fork occurred. */
1030	/* Execute the command. */
1031	if (cmdentry.cmdtype == CMDFUNCTION) {
1032#ifdef DEBUG
1033		trputs("Shell function:  ");  trargs(argv);
1034#endif
1035		saveparam = shellparam;
1036		shellparam.malloc = 0;
1037		shellparam.reset = 1;
1038		shellparam.nparam = argc - 1;
1039		shellparam.p = argv + 1;
1040		shellparam.optnext = NULL;
1041		INTOFF;
1042		savelocalvars = localvars;
1043		localvars = NULL;
1044		reffunc(cmdentry.u.func);
1045		savehandler = handler;
1046		if (setjmp(jmploc.loc)) {
1047			freeparam(&shellparam);
1048			shellparam = saveparam;
1049			popredir();
1050			unreffunc(cmdentry.u.func);
1051			poplocalvars();
1052			localvars = savelocalvars;
1053			funcnest--;
1054			handler = savehandler;
1055			longjmp(handler->loc, 1);
1056		}
1057		handler = &jmploc;
1058		funcnest++;
1059		redirect(cmd->ncmd.redirect, REDIR_PUSH);
1060		INTON;
1061		for (sp = varlist.list ; sp ; sp = sp->next)
1062			mklocal(sp->text);
1063		exitstatus = oexitstatus;
1064		evaltree(getfuncnode(cmdentry.u.func),
1065		    flags & (EV_TESTED | EV_EXIT));
1066		INTOFF;
1067		unreffunc(cmdentry.u.func);
1068		poplocalvars();
1069		localvars = savelocalvars;
1070		freeparam(&shellparam);
1071		shellparam = saveparam;
1072		handler = savehandler;
1073		funcnest--;
1074		popredir();
1075		INTON;
1076		if (evalskip == SKIPRETURN) {
1077			evalskip = 0;
1078			skipcount = 0;
1079		}
1080		if (jp)
1081			exitshell(exitstatus);
1082	} else if (cmdentry.cmdtype == CMDBUILTIN) {
1083#ifdef DEBUG
1084		trputs("builtin command:  ");  trargs(argv);
1085#endif
1086		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1087		if (flags == EV_BACKCMD) {
1088			memout.nleft = 0;
1089			memout.nextc = memout.buf;
1090			memout.bufsize = 64;
1091			mode |= REDIR_BACKQ;
1092		}
1093		savecmdname = commandname;
1094		savetopfile = getcurrentfile();
1095		cmdenviron = varlist.list;
1096		e = -1;
1097		savehandler = handler;
1098		if (setjmp(jmploc.loc)) {
1099			e = exception;
1100			if (e == EXINT)
1101				exitstatus = SIGINT+128;
1102			else if (e != EXEXIT)
1103				exitstatus = 2;
1104			goto cmddone;
1105		}
1106		handler = &jmploc;
1107		redirect(cmd->ncmd.redirect, mode);
1108		outclearerror(out1);
1109		/*
1110		 * If there is no command word, redirection errors should
1111		 * not be fatal but assignment errors should.
1112		 */
1113		if (argc == 0)
1114			cmdentry.special = 1;
1115		listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1116		if (argc > 0)
1117			bltinsetlocale();
1118		commandname = argv[0];
1119		argptr = argv + 1;
1120		nextopt_optptr = NULL;		/* initialize nextopt */
1121		builtin_flags = flags;
1122		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1123		flushall();
1124		if (outiserror(out1)) {
1125			warning("write error on stdout");
1126			if (exitstatus == 0 || exitstatus == 1)
1127				exitstatus = 2;
1128		}
1129cmddone:
1130		if (argc > 0)
1131			bltinunsetlocale();
1132		cmdenviron = NULL;
1133		out1 = &output;
1134		out2 = &errout;
1135		freestdout();
1136		handler = savehandler;
1137		commandname = savecmdname;
1138		if (jp)
1139			exitshell(exitstatus);
1140		if (flags == EV_BACKCMD) {
1141			backcmd->buf = memout.buf;
1142			backcmd->nleft = memout.nextc - memout.buf;
1143			memout.buf = NULL;
1144		}
1145		if (cmdentry.u.index != EXECCMD)
1146			popredir();
1147		if (e != -1) {
1148			if ((e != EXERROR && e != EXEXEC)
1149			    || cmdentry.special)
1150				exraise(e);
1151			popfilesupto(savetopfile);
1152			if (flags != EV_BACKCMD)
1153				FORCEINTON;
1154		}
1155	} else {
1156#ifdef DEBUG
1157		trputs("normal command:  ");  trargs(argv);
1158#endif
1159		redirect(cmd->ncmd.redirect, 0);
1160		for (sp = varlist.list ; sp ; sp = sp->next)
1161			setvareq(sp->text, VEXPORT|VSTACK);
1162		envp = environment();
1163		shellexec(argv, envp, path, cmdentry.u.index);
1164		/*NOTREACHED*/
1165	}
1166	goto out;
1167
1168parent:	/* parent process gets here (if we forked) */
1169	if (mode == FORK_FG) {	/* argument to fork */
1170		INTOFF;
1171		exitstatus = waitforjob(jp, &realstatus);
1172		INTON;
1173		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1174			evalskip = SKIPBREAK;
1175			skipcount = loopnest;
1176		}
1177	} else if (mode == FORK_NOJOB) {
1178		backcmd->fd = pip[0];
1179		close(pip[1]);
1180		backcmd->jp = jp;
1181	}
1182
1183out:
1184	if (lastarg)
1185		setvar("_", lastarg, 0);
1186	if (do_clearcmdentry)
1187		clearcmdentry();
1188}
1189
1190
1191
1192/*
1193 * Search for a command.  This is called before we fork so that the
1194 * location of the command will be available in the parent as well as
1195 * the child.  The check for "goodname" is an overly conservative
1196 * check that the name will not be subject to expansion.
1197 */
1198
1199static void
1200prehash(union node *n)
1201{
1202	struct cmdentry entry;
1203
1204	if (n && n->type == NCMD && n->ncmd.args)
1205		if (goodname(n->ncmd.args->narg.text))
1206			find_command(n->ncmd.args->narg.text, &entry, 0,
1207				     pathval());
1208}
1209
1210
1211
1212/*
1213 * Builtin commands.  Builtin commands whose functions are closely
1214 * tied to evaluation are implemented here.
1215 */
1216
1217/*
1218 * No command given, a bltin command with no arguments, or a bltin command
1219 * with an invalid name.
1220 */
1221
1222int
1223bltincmd(int argc, char **argv)
1224{
1225	if (argc > 1) {
1226		out2fmt_flush("%s: not found\n", argv[1]);
1227		return 127;
1228	}
1229	/*
1230	 * Preserve exitstatus of a previous possible redirection
1231	 * as POSIX mandates
1232	 */
1233	return exitstatus;
1234}
1235
1236
1237/*
1238 * Handle break and continue commands.  Break, continue, and return are
1239 * all handled by setting the evalskip flag.  The evaluation routines
1240 * above all check this flag, and if it is set they start skipping
1241 * commands rather than executing them.  The variable skipcount is
1242 * the number of loops to break/continue, or the number of function
1243 * levels to return.  (The latter is always 1.)  It should probably
1244 * be an error to break out of more loops than exist, but it isn't
1245 * in the standard shell so we don't make it one here.
1246 */
1247
1248int
1249breakcmd(int argc, char **argv)
1250{
1251	int n = argc > 1 ? number(argv[1]) : 1;
1252
1253	if (n > loopnest)
1254		n = loopnest;
1255	if (n > 0) {
1256		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1257		skipcount = n;
1258	}
1259	return 0;
1260}
1261
1262/*
1263 * The `command' command.
1264 */
1265int
1266commandcmd(int argc __unused, char **argv __unused)
1267{
1268	const char *path;
1269	int ch;
1270	int cmd = -1;
1271
1272	path = bltinlookup("PATH", 1);
1273
1274	while ((ch = nextopt("pvV")) != '\0') {
1275		switch (ch) {
1276		case 'p':
1277			path = _PATH_STDPATH;
1278			break;
1279		case 'v':
1280			cmd = TYPECMD_SMALLV;
1281			break;
1282		case 'V':
1283			cmd = TYPECMD_BIGV;
1284			break;
1285		}
1286	}
1287
1288	if (cmd != -1) {
1289		if (*argptr == NULL || argptr[1] != NULL)
1290			error("wrong number of arguments");
1291		return typecmd_impl(2, argptr - 1, cmd, path);
1292	}
1293	if (*argptr != NULL)
1294		error("commandcmd bad call");
1295
1296	/*
1297	 * Do nothing successfully if no command was specified;
1298	 * ksh also does this.
1299	 */
1300	return 0;
1301}
1302
1303
1304/*
1305 * The return command.
1306 */
1307
1308int
1309returncmd(int argc, char **argv)
1310{
1311	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1312
1313	evalskip = SKIPRETURN;
1314	skipcount = 1;
1315	return ret;
1316}
1317
1318
1319int
1320falsecmd(int argc __unused, char **argv __unused)
1321{
1322	return 1;
1323}
1324
1325
1326int
1327truecmd(int argc __unused, char **argv __unused)
1328{
1329	return 0;
1330}
1331
1332
1333int
1334execcmd(int argc, char **argv)
1335{
1336	/*
1337	 * Because we have historically not supported any options,
1338	 * only treat "--" specially.
1339	 */
1340	if (argc > 1 && strcmp(argv[1], "--") == 0)
1341		argc--, argv++;
1342	if (argc > 1) {
1343		struct strlist *sp;
1344
1345		iflag = 0;		/* exit on error */
1346		mflag = 0;
1347		optschanged();
1348		for (sp = cmdenviron; sp ; sp = sp->next)
1349			setvareq(sp->text, VEXPORT|VSTACK);
1350		shellexec(argv + 1, environment(), pathval(), 0);
1351
1352	}
1353	return 0;
1354}
1355
1356
1357int
1358timescmd(int argc __unused, char **argv __unused)
1359{
1360	struct rusage ru;
1361	long shumins, shsmins, chumins, chsmins;
1362	double shusecs, shssecs, chusecs, chssecs;
1363
1364	if (getrusage(RUSAGE_SELF, &ru) < 0)
1365		return 1;
1366	shumins = ru.ru_utime.tv_sec / 60;
1367	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1368	shsmins = ru.ru_stime.tv_sec / 60;
1369	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1370	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1371		return 1;
1372	chumins = ru.ru_utime.tv_sec / 60;
1373	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1374	chsmins = ru.ru_stime.tv_sec / 60;
1375	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1376	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1377	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1378	return 0;
1379}
1380