eval.c revision 208630 
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: head/bin/sh/eval.c 208630 2010-05-28 22:40:24Z 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 */
78STATIC int skipcount;		/* number of levels to skip */
79MKINIT 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 void evalcase(union node *, int);
93STATIC void evalsubshell(union node *, int);
94STATIC void evalredir(union node *, int);
95STATIC void expredir(union node *);
96STATIC void evalpipe(union node *);
97STATIC void evalcommand(union node *, int, struct backcmd *);
98STATIC void prehash(union node *);
99
100
101/*
102 * Called to reset things after an exception.
103 */
104
105#ifdef mkinit
106INCLUDE "eval.h"
107
108RESET {
109	evalskip = 0;
110	loopnest = 0;
111	funcnest = 0;
112}
113
114SHELLPROC {
115	exitstatus = 0;
116}
117#endif
118
119
120
121/*
122 * The eval command.
123 */
124
125int
126evalcmd(int argc, char **argv)
127{
128        char *p;
129        char *concat;
130        char **ap;
131
132        if (argc > 1) {
133                p = argv[1];
134                if (argc > 2) {
135                        STARTSTACKSTR(concat);
136                        ap = argv + 2;
137                        for (;;) {
138                                while (*p)
139                                        STPUTC(*p++, concat);
140                                if ((p = *ap++) == NULL)
141                                        break;
142                                STPUTC(' ', concat);
143                        }
144                        STPUTC('\0', concat);
145                        p = grabstackstr(concat);
146                }
147                evalstring(p, builtin_flags & EV_TESTED);
148        }
149        return exitstatus;
150}
151
152
153/*
154 * Execute a command or commands contained in a string.
155 */
156
157void
158evalstring(char *s, int flags)
159{
160	union node *n;
161	struct stackmark smark;
162	int flags_exit;
163
164	flags_exit = flags & EV_EXIT;
165	flags &= ~EV_EXIT;
166	setstackmark(&smark);
167	setinputstring(s, 1);
168	while ((n = parsecmd(0)) != NEOF) {
169		if (n != NULL) {
170			if (flags_exit && preadateof())
171				evaltree(n, flags | EV_EXIT);
172			else
173				evaltree(n, flags);
174		}
175		popstackmark(&smark);
176	}
177	popfile();
178	popstackmark(&smark);
179	if (flags_exit)
180		exitshell(exitstatus);
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
194	do_etest = 0;
195	if (n == NULL) {
196		TRACE(("evaltree(NULL) called\n"));
197		exitstatus = 0;
198		goto out;
199	}
200#ifndef NO_HISTORY
201	displayhist = 1;	/* show history substitutions done with fc */
202#endif
203	TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
204	switch (n->type) {
205	case NSEMI:
206		evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
207		if (evalskip)
208			goto out;
209		evaltree(n->nbinary.ch2, flags);
210		break;
211	case NAND:
212		evaltree(n->nbinary.ch1, EV_TESTED);
213		if (evalskip || exitstatus != 0) {
214			goto out;
215		}
216		evaltree(n->nbinary.ch2, flags);
217		break;
218	case NOR:
219		evaltree(n->nbinary.ch1, EV_TESTED);
220		if (evalskip || exitstatus == 0)
221			goto out;
222		evaltree(n->nbinary.ch2, flags);
223		break;
224	case NREDIR:
225		evalredir(n, flags);
226		break;
227	case NSUBSHELL:
228		evalsubshell(n, flags);
229		do_etest = !(flags & EV_TESTED);
230		break;
231	case NBACKGND:
232		evalsubshell(n, flags);
233		break;
234	case NIF: {
235		evaltree(n->nif.test, EV_TESTED);
236		if (evalskip)
237			goto out;
238		if (exitstatus == 0)
239			evaltree(n->nif.ifpart, flags);
240		else if (n->nif.elsepart)
241			evaltree(n->nif.elsepart, flags);
242		else
243			exitstatus = 0;
244		break;
245	}
246	case NWHILE:
247	case NUNTIL:
248		evalloop(n, flags & ~EV_EXIT);
249		break;
250	case NFOR:
251		evalfor(n, flags & ~EV_EXIT);
252		break;
253	case NCASE:
254		evalcase(n, flags);
255		break;
256	case NDEFUN:
257		defun(n->narg.text, n->narg.next);
258		exitstatus = 0;
259		break;
260	case NNOT:
261		evaltree(n->nnot.com, EV_TESTED);
262		exitstatus = !exitstatus;
263		break;
264
265	case NPIPE:
266		evalpipe(n);
267		do_etest = !(flags & EV_TESTED);
268		break;
269	case NCMD:
270		evalcommand(n, flags, (struct backcmd *)NULL);
271		do_etest = !(flags & EV_TESTED);
272		break;
273	default:
274		out1fmt("Node type = %d\n", n->type);
275		flushout(&output);
276		break;
277	}
278out:
279	if (pendingsigs)
280		dotrap();
281	if ((flags & EV_EXIT) || (eflag && exitstatus != 0 && do_etest))
282		exitshell(exitstatus);
283}
284
285
286STATIC void
287evalloop(union node *n, int flags)
288{
289	int status;
290
291	loopnest++;
292	status = 0;
293	for (;;) {
294		evaltree(n->nbinary.ch1, EV_TESTED);
295		if (evalskip) {
296skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
297				evalskip = 0;
298				continue;
299			}
300			if (evalskip == SKIPBREAK && --skipcount <= 0)
301				evalskip = 0;
302			break;
303		}
304		if (n->type == NWHILE) {
305			if (exitstatus != 0)
306				break;
307		} else {
308			if (exitstatus == 0)
309				break;
310		}
311		evaltree(n->nbinary.ch2, flags);
312		status = exitstatus;
313		if (evalskip)
314			goto skipping;
315	}
316	loopnest--;
317	exitstatus = status;
318}
319
320
321
322STATIC void
323evalfor(union node *n, int flags)
324{
325	struct arglist arglist;
326	union node *argp;
327	struct strlist *sp;
328	struct stackmark smark;
329
330	setstackmark(&smark);
331	arglist.lastp = &arglist.list;
332	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
333		oexitstatus = exitstatus;
334		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
335		if (evalskip)
336			goto out;
337	}
338	*arglist.lastp = NULL;
339
340	exitstatus = 0;
341	loopnest++;
342	for (sp = arglist.list ; sp ; sp = sp->next) {
343		setvar(n->nfor.var, sp->text, 0);
344		evaltree(n->nfor.body, flags);
345		if (evalskip) {
346			if (evalskip == SKIPCONT && --skipcount <= 0) {
347				evalskip = 0;
348				continue;
349			}
350			if (evalskip == SKIPBREAK && --skipcount <= 0)
351				evalskip = 0;
352			break;
353		}
354	}
355	loopnest--;
356out:
357	popstackmark(&smark);
358}
359
360
361
362STATIC void
363evalcase(union node *n, int flags)
364{
365	union node *cp;
366	union node *patp;
367	struct arglist arglist;
368	struct stackmark smark;
369
370	setstackmark(&smark);
371	arglist.lastp = &arglist.list;
372	oexitstatus = exitstatus;
373	exitstatus = 0;
374	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
375	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
376		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
377			if (casematch(patp, arglist.list->text)) {
378				if (evalskip == 0) {
379					evaltree(cp->nclist.body, flags);
380				}
381				goto out;
382			}
383		}
384	}
385out:
386	popstackmark(&smark);
387}
388
389
390
391/*
392 * Kick off a subshell to evaluate a tree.
393 */
394
395STATIC void
396evalsubshell(union node *n, int flags)
397{
398	struct job *jp;
399	int backgnd = (n->type == NBACKGND);
400
401	expredir(n->nredir.redirect);
402	if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
403			forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
404		if (backgnd)
405			flags &=~ EV_TESTED;
406		redirect(n->nredir.redirect, 0);
407		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
408	} else if (! backgnd) {
409		INTOFF;
410		exitstatus = waitforjob(jp, (int *)NULL);
411		INTON;
412	}
413}
414
415
416/*
417 * Evaluate a redirected compound command.
418 */
419
420STATIC void
421evalredir(union node *n, int flags)
422{
423	struct jmploc jmploc;
424	struct jmploc *savehandler;
425	volatile int in_redirect = 1;
426
427	expredir(n->nredir.redirect);
428	savehandler = handler;
429	if (setjmp(jmploc.loc)) {
430		int e;
431
432		handler = savehandler;
433		e = exception;
434		if (e == EXERROR || e == EXEXEC) {
435			popredir();
436			if (in_redirect) {
437				exitstatus = 2;
438				return;
439			}
440		}
441		longjmp(handler->loc, 1);
442	} else {
443		INTOFF;
444		handler = &jmploc;
445		redirect(n->nredir.redirect, REDIR_PUSH);
446		in_redirect = 0;
447		INTON;
448		evaltree(n->nredir.n, flags);
449	}
450	INTOFF;
451	handler = savehandler;
452	popredir();
453	INTON;
454}
455
456
457/*
458 * Compute the names of the files in a redirection list.
459 */
460
461STATIC void
462expredir(union node *n)
463{
464	union node *redir;
465
466	for (redir = n ; redir ; redir = redir->nfile.next) {
467		struct arglist fn;
468		fn.lastp = &fn.list;
469		oexitstatus = exitstatus;
470		switch (redir->type) {
471		case NFROM:
472		case NTO:
473		case NFROMTO:
474		case NAPPEND:
475		case NCLOBBER:
476			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
477			redir->nfile.expfname = fn.list->text;
478			break;
479		case NFROMFD:
480		case NTOFD:
481			if (redir->ndup.vname) {
482				expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
483				fixredir(redir, fn.list->text, 1);
484			}
485			break;
486		}
487	}
488}
489
490
491
492/*
493 * Evaluate a pipeline.  All the processes in the pipeline are children
494 * of the process creating the pipeline.  (This differs from some versions
495 * of the shell, which make the last process in a pipeline the parent
496 * of all the rest.)
497 */
498
499STATIC void
500evalpipe(union node *n)
501{
502	struct job *jp;
503	struct nodelist *lp;
504	int pipelen;
505	int prevfd;
506	int pip[2];
507
508	TRACE(("evalpipe(%p) called\n", (void *)n));
509	pipelen = 0;
510	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
511		pipelen++;
512	INTOFF;
513	jp = makejob(n, pipelen);
514	prevfd = -1;
515	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
516		prehash(lp->n);
517		pip[1] = -1;
518		if (lp->next) {
519			if (pipe(pip) < 0) {
520				close(prevfd);
521				error("Pipe call failed: %s", strerror(errno));
522			}
523		}
524		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
525			INTON;
526			if (prevfd > 0) {
527				dup2(prevfd, 0);
528				close(prevfd);
529			}
530			if (pip[1] >= 0) {
531				if (!(prevfd >= 0 && pip[0] == 0))
532					close(pip[0]);
533				if (pip[1] != 1) {
534					dup2(pip[1], 1);
535					close(pip[1]);
536				}
537			}
538			evaltree(lp->n, EV_EXIT);
539		}
540		if (prevfd >= 0)
541			close(prevfd);
542		prevfd = pip[0];
543		close(pip[1]);
544	}
545	INTON;
546	if (n->npipe.backgnd == 0) {
547		INTOFF;
548		exitstatus = waitforjob(jp, (int *)NULL);
549		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
550		INTON;
551	}
552}
553
554
555
556/*
557 * Execute a command inside back quotes.  If it's a builtin command, we
558 * want to save its output in a block obtained from malloc.  Otherwise
559 * we fork off a subprocess and get the output of the command via a pipe.
560 * Should be called with interrupts off.
561 */
562
563void
564evalbackcmd(union node *n, struct backcmd *result)
565{
566	int pip[2];
567	struct job *jp;
568	struct stackmark smark;		/* unnecessary */
569
570	setstackmark(&smark);
571	result->fd = -1;
572	result->buf = NULL;
573	result->nleft = 0;
574	result->jp = NULL;
575	if (n == NULL) {
576		exitstatus = 0;
577		goto out;
578	}
579	if (n->type == NCMD) {
580		exitstatus = oexitstatus;
581		evalcommand(n, EV_BACKCMD, result);
582	} else {
583		exitstatus = 0;
584		if (pipe(pip) < 0)
585			error("Pipe call failed: %s", strerror(errno));
586		jp = makejob(n, 1);
587		if (forkshell(jp, n, FORK_NOJOB) == 0) {
588			FORCEINTON;
589			close(pip[0]);
590			if (pip[1] != 1) {
591				dup2(pip[1], 1);
592				close(pip[1]);
593			}
594			evaltree(n, EV_EXIT);
595		}
596		close(pip[1]);
597		result->fd = pip[0];
598		result->jp = jp;
599	}
600out:
601	popstackmark(&smark);
602	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
603		result->fd, result->buf, result->nleft, result->jp));
604}
605
606
607
608/*
609 * Execute a simple command.
610 */
611
612STATIC void
613evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
614{
615	struct stackmark smark;
616	union node *argp;
617	struct arglist arglist;
618	struct arglist varlist;
619	char **argv;
620	int argc;
621	char **envp;
622	int varflag;
623	struct strlist *sp;
624	int mode;
625	int pip[2];
626	struct cmdentry cmdentry;
627	struct job *jp;
628	struct jmploc jmploc;
629	struct jmploc *savehandler;
630	char *savecmdname;
631	struct shparam saveparam;
632	struct localvar *savelocalvars;
633	struct parsefile *savetopfile;
634	volatile int e;
635	char *lastarg;
636	int realstatus;
637	int do_clearcmdentry;
638	char *path = pathval();
639
640	/* First expand the arguments. */
641	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
642	setstackmark(&smark);
643	arglist.lastp = &arglist.list;
644	varlist.lastp = &varlist.list;
645	varflag = 1;
646	do_clearcmdentry = 0;
647	oexitstatus = exitstatus;
648	exitstatus = 0;
649	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
650		char *p = argp->narg.text;
651		if (varflag && is_name(*p)) {
652			do {
653				p++;
654			} while (is_in_name(*p));
655			if (*p == '=') {
656				expandarg(argp, &varlist, EXP_VARTILDE);
657				continue;
658			}
659		}
660		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
661		varflag = 0;
662	}
663	*arglist.lastp = NULL;
664	*varlist.lastp = NULL;
665	expredir(cmd->ncmd.redirect);
666	argc = 0;
667	for (sp = arglist.list ; sp ; sp = sp->next)
668		argc++;
669	argv = stalloc(sizeof (char *) * (argc + 1));
670
671	for (sp = arglist.list ; sp ; sp = sp->next) {
672		TRACE(("evalcommand arg: %s\n", sp->text));
673		*argv++ = sp->text;
674	}
675	*argv = NULL;
676	lastarg = NULL;
677	if (iflag && funcnest == 0 && argc > 0)
678		lastarg = argv[-1];
679	argv -= argc;
680
681	/* Print the command if xflag is set. */
682	if (xflag) {
683		char sep = 0;
684		const char *p;
685		out2str(ps4val());
686		for (sp = varlist.list ; sp ; sp = sp->next) {
687			if (sep != 0)
688				out2c(' ');
689			p = sp->text;
690			while (*p != '=' && *p != '\0')
691				out2c(*p++);
692			if (*p != '\0') {
693				out2c(*p++);
694				out2qstr(p);
695			}
696			sep = ' ';
697		}
698		for (sp = arglist.list ; sp ; sp = sp->next) {
699			if (sep != 0)
700				out2c(' ');
701			/* Disambiguate command looking like assignment. */
702			if (sp == arglist.list &&
703					strchr(sp->text, '=') != NULL &&
704					strchr(sp->text, '\'') == NULL) {
705				out2c('\'');
706				out2str(sp->text);
707				out2c('\'');
708			} else
709				out2qstr(sp->text);
710			sep = ' ';
711		}
712		out2c('\n');
713		flushout(&errout);
714	}
715
716	/* Now locate the command. */
717	if (argc == 0) {
718		/* Variable assignment(s) without command */
719		cmdentry.cmdtype = CMDBUILTIN;
720		cmdentry.u.index = BLTINCMD;
721		cmdentry.special = 0;
722	} else {
723		static const char PATH[] = "PATH=";
724		int cmd_flags = 0, bltinonly = 0;
725
726		/*
727		 * Modify the command lookup path, if a PATH= assignment
728		 * is present
729		 */
730		for (sp = varlist.list ; sp ; sp = sp->next)
731			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
732				path = sp->text + sizeof(PATH) - 1;
733				/*
734				 * On `PATH=... command`, we need to make
735				 * sure that the command isn't using the
736				 * non-updated hash table of the outer PATH
737				 * setting and we need to make sure that
738				 * the hash table isn't filled with items
739				 * from the temporary setting.
740				 *
741				 * It would be better to forbit using and
742				 * updating the table while this command
743				 * runs, by the command finding mechanism
744				 * is heavily integrated with hash handling,
745				 * so we just delete the hash before and after
746				 * the command runs. Partly deleting like
747				 * changepatch() does doesn't seem worth the
748				 * bookinging effort, since most such runs add
749				 * directories in front of the new PATH.
750				 */
751				clearcmdentry(0);
752				do_clearcmdentry = 1;
753			}
754
755		for (;;) {
756			if (bltinonly) {
757				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
758				if (cmdentry.u.index < 0) {
759					cmdentry.u.index = BLTINCMD;
760					argv--;
761					argc++;
762					break;
763				}
764			} else
765				find_command(argv[0], &cmdentry, cmd_flags, path);
766			/* implement the bltin and command builtins here */
767			if (cmdentry.cmdtype != CMDBUILTIN)
768				break;
769			if (cmdentry.u.index == BLTINCMD) {
770				if (argc == 1)
771					break;
772				argv++;
773				argc--;
774				bltinonly = 1;
775			} else if (cmdentry.u.index == COMMANDCMD) {
776				if (argc == 1)
777					break;
778				if (!strcmp(argv[1], "-p")) {
779					if (argc == 2)
780						break;
781					if (argv[2][0] == '-') {
782						if (strcmp(argv[2], "--"))
783							break;
784						if (argc == 3)
785							break;
786						argv += 3;
787						argc -= 3;
788					} else {
789						argv += 2;
790						argc -= 2;
791					}
792					path = _PATH_STDPATH;
793					clearcmdentry(0);
794					do_clearcmdentry = 1;
795				} else if (!strcmp(argv[1], "--")) {
796					if (argc == 2)
797						break;
798					argv += 2;
799					argc -= 2;
800				} else if (argv[1][0] == '-')
801					break;
802				else {
803					argv++;
804					argc--;
805				}
806				cmd_flags |= DO_NOFUNC;
807				bltinonly = 0;
808			} else
809				break;
810		}
811		/*
812		 * Special builtins lose their special properties when
813		 * called via 'command'.
814		 */
815		if (cmd_flags & DO_NOFUNC)
816			cmdentry.special = 0;
817	}
818
819	/* Fork off a child process if necessary. */
820	if (cmd->ncmd.backgnd
821	 || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
822	    && ((flags & EV_EXIT) == 0 || have_traps()))
823	 || ((flags & EV_BACKCMD) != 0
824	    && (cmdentry.cmdtype != CMDBUILTIN
825		 || cmdentry.u.index == CDCMD
826		 || cmdentry.u.index == DOTCMD
827		 || cmdentry.u.index == EVALCMD))) {
828		jp = makejob(cmd, 1);
829		mode = cmd->ncmd.backgnd;
830		if (flags & EV_BACKCMD) {
831			mode = FORK_NOJOB;
832			if (pipe(pip) < 0)
833				error("Pipe call failed: %s", strerror(errno));
834		}
835		if (forkshell(jp, cmd, mode) != 0)
836			goto parent;	/* at end of routine */
837		if (flags & EV_BACKCMD) {
838			FORCEINTON;
839			close(pip[0]);
840			if (pip[1] != 1) {
841				dup2(pip[1], 1);
842				close(pip[1]);
843			}
844		}
845		flags |= EV_EXIT;
846	}
847
848	/* This is the child process if a fork occurred. */
849	/* Execute the command. */
850	if (cmdentry.cmdtype == CMDFUNCTION) {
851#ifdef DEBUG
852		trputs("Shell function:  ");  trargs(argv);
853#endif
854		saveparam = shellparam;
855		shellparam.malloc = 0;
856		shellparam.reset = 1;
857		shellparam.nparam = argc - 1;
858		shellparam.p = argv + 1;
859		shellparam.optnext = NULL;
860		INTOFF;
861		savelocalvars = localvars;
862		localvars = NULL;
863		reffunc(cmdentry.u.func);
864		savehandler = handler;
865		if (setjmp(jmploc.loc)) {
866			if (exception == EXSHELLPROC)
867				freeparam(&saveparam);
868			else {
869				freeparam(&shellparam);
870				shellparam = saveparam;
871				if (exception == EXERROR || exception == EXEXEC)
872					popredir();
873			}
874			unreffunc(cmdentry.u.func);
875			poplocalvars();
876			localvars = savelocalvars;
877			funcnest--;
878			handler = savehandler;
879			longjmp(handler->loc, 1);
880		}
881		handler = &jmploc;
882		funcnest++;
883		redirect(cmd->ncmd.redirect, REDIR_PUSH);
884		INTON;
885		for (sp = varlist.list ; sp ; sp = sp->next)
886			mklocal(sp->text);
887		exitstatus = oexitstatus;
888		if (flags & EV_TESTED)
889			evaltree(getfuncnode(cmdentry.u.func), EV_TESTED);
890		else
891			evaltree(getfuncnode(cmdentry.u.func), 0);
892		INTOFF;
893		unreffunc(cmdentry.u.func);
894		poplocalvars();
895		localvars = savelocalvars;
896		freeparam(&shellparam);
897		shellparam = saveparam;
898		handler = savehandler;
899		funcnest--;
900		popredir();
901		INTON;
902		if (evalskip == SKIPFUNC) {
903			evalskip = 0;
904			skipcount = 0;
905		}
906		if (flags & EV_EXIT)
907			exitshell(exitstatus);
908	} else if (cmdentry.cmdtype == CMDBUILTIN) {
909#ifdef DEBUG
910		trputs("builtin command:  ");  trargs(argv);
911#endif
912		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
913		if (flags == EV_BACKCMD) {
914			memout.nleft = 0;
915			memout.nextc = memout.buf;
916			memout.bufsize = 64;
917			mode |= REDIR_BACKQ;
918			cmdentry.special = 0;
919		}
920		savecmdname = commandname;
921		savetopfile = getcurrentfile();
922		cmdenviron = varlist.list;
923		e = -1;
924		savehandler = handler;
925		if (setjmp(jmploc.loc)) {
926			e = exception;
927			exitstatus = (e == EXINT)? SIGINT+128 : 2;
928			goto cmddone;
929		}
930		handler = &jmploc;
931		redirect(cmd->ncmd.redirect, mode);
932		/*
933		 * If there is no command word, redirection errors should
934		 * not be fatal but assignment errors should.
935		 */
936		if (argc == 0 && !(flags & EV_BACKCMD))
937			cmdentry.special = 1;
938		if (cmdentry.special)
939			listsetvar(cmdenviron);
940		if (argc > 0)
941			bltinsetlocale();
942		commandname = argv[0];
943		argptr = argv + 1;
944		nextopt_optptr = NULL;		/* initialize nextopt */
945		builtin_flags = flags;
946		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
947		flushall();
948cmddone:
949		if (argc > 0)
950			bltinunsetlocale();
951		cmdenviron = NULL;
952		out1 = &output;
953		out2 = &errout;
954		freestdout();
955		if (e != EXSHELLPROC) {
956			commandname = savecmdname;
957			if (flags & EV_EXIT) {
958				exitshell(exitstatus);
959			}
960		}
961		handler = savehandler;
962		if (flags == EV_BACKCMD) {
963			backcmd->buf = memout.buf;
964			backcmd->nleft = memout.nextc - memout.buf;
965			memout.buf = NULL;
966		}
967		if (cmdentry.u.index != EXECCMD &&
968				(e == -1 || e == EXERROR || e == EXEXEC))
969			popredir();
970		if (e != -1) {
971			if ((e != EXERROR && e != EXEXEC)
972			    || cmdentry.special)
973				exraise(e);
974			popfilesupto(savetopfile);
975			if (flags != EV_BACKCMD)
976				FORCEINTON;
977		}
978	} else {
979#ifdef DEBUG
980		trputs("normal command:  ");  trargs(argv);
981#endif
982		redirect(cmd->ncmd.redirect, 0);
983		for (sp = varlist.list ; sp ; sp = sp->next)
984			setvareq(sp->text, VEXPORT|VSTACK);
985		envp = environment();
986		shellexec(argv, envp, path, cmdentry.u.index);
987		/*NOTREACHED*/
988	}
989	goto out;
990
991parent:	/* parent process gets here (if we forked) */
992	if (mode == 0) {	/* argument to fork */
993		INTOFF;
994		exitstatus = waitforjob(jp, &realstatus);
995		INTON;
996		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
997			evalskip = SKIPBREAK;
998			skipcount = loopnest;
999		}
1000	} else if (mode == 2) {
1001		backcmd->fd = pip[0];
1002		close(pip[1]);
1003		backcmd->jp = jp;
1004	}
1005
1006out:
1007	if (lastarg)
1008		setvar("_", lastarg, 0);
1009	if (do_clearcmdentry)
1010		clearcmdentry(0);
1011	popstackmark(&smark);
1012}
1013
1014
1015
1016/*
1017 * Search for a command.  This is called before we fork so that the
1018 * location of the command will be available in the parent as well as
1019 * the child.  The check for "goodname" is an overly conservative
1020 * check that the name will not be subject to expansion.
1021 */
1022
1023STATIC void
1024prehash(union node *n)
1025{
1026	struct cmdentry entry;
1027
1028	if (n && n->type == NCMD && n->ncmd.args)
1029		if (goodname(n->ncmd.args->narg.text))
1030			find_command(n->ncmd.args->narg.text, &entry, 0,
1031				     pathval());
1032}
1033
1034
1035
1036/*
1037 * Builtin commands.  Builtin commands whose functions are closely
1038 * tied to evaluation are implemented here.
1039 */
1040
1041/*
1042 * No command given, a bltin command with no arguments, or a bltin command
1043 * with an invalid name.
1044 */
1045
1046int
1047bltincmd(int argc, char **argv)
1048{
1049	if (argc > 1) {
1050		out2fmt_flush("%s: not found\n", argv[1]);
1051		return 127;
1052	}
1053	/*
1054	 * Preserve exitstatus of a previous possible redirection
1055	 * as POSIX mandates
1056	 */
1057	return exitstatus;
1058}
1059
1060
1061/*
1062 * Handle break and continue commands.  Break, continue, and return are
1063 * all handled by setting the evalskip flag.  The evaluation routines
1064 * above all check this flag, and if it is set they start skipping
1065 * commands rather than executing them.  The variable skipcount is
1066 * the number of loops to break/continue, or the number of function
1067 * levels to return.  (The latter is always 1.)  It should probably
1068 * be an error to break out of more loops than exist, but it isn't
1069 * in the standard shell so we don't make it one here.
1070 */
1071
1072int
1073breakcmd(int argc, char **argv)
1074{
1075	int n = argc > 1 ? number(argv[1]) : 1;
1076
1077	if (n > loopnest)
1078		n = loopnest;
1079	if (n > 0) {
1080		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1081		skipcount = n;
1082	}
1083	return 0;
1084}
1085
1086/*
1087 * The `command' command.
1088 */
1089int
1090commandcmd(int argc, char **argv)
1091{
1092	const char *path;
1093	int ch;
1094	int cmd = -1;
1095
1096	path = bltinlookup("PATH", 1);
1097
1098	optind = optreset = 1;
1099	opterr = 0;
1100	while ((ch = getopt(argc, argv, "pvV")) != -1) {
1101		switch (ch) {
1102		case 'p':
1103			path = _PATH_STDPATH;
1104			break;
1105		case 'v':
1106			cmd = TYPECMD_SMALLV;
1107			break;
1108		case 'V':
1109			cmd = TYPECMD_BIGV;
1110			break;
1111		case '?':
1112		default:
1113			error("unknown option: -%c", optopt);
1114		}
1115	}
1116	argc -= optind;
1117	argv += optind;
1118
1119	if (cmd != -1) {
1120		if (argc != 1)
1121			error("wrong number of arguments");
1122		return typecmd_impl(2, argv - 1, cmd, path);
1123	}
1124	if (argc != 0)
1125		error("commandcmd() called while it should not be");
1126
1127	/*
1128	 * Do nothing successfully if no command was specified;
1129	 * ksh also does this.
1130	 */
1131	return 0;
1132}
1133
1134
1135/*
1136 * The return command.
1137 */
1138
1139int
1140returncmd(int argc, char **argv)
1141{
1142	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1143
1144	if (funcnest) {
1145		evalskip = SKIPFUNC;
1146		skipcount = 1;
1147	} else {
1148		/* skip the rest of the file */
1149		evalskip = SKIPFILE;
1150		skipcount = 1;
1151	}
1152	return ret;
1153}
1154
1155
1156int
1157falsecmd(int argc __unused, char **argv __unused)
1158{
1159	return 1;
1160}
1161
1162
1163int
1164truecmd(int argc __unused, char **argv __unused)
1165{
1166	return 0;
1167}
1168
1169
1170int
1171execcmd(int argc, char **argv)
1172{
1173	/*
1174	 * Because we have historically not supported any options,
1175	 * only treat "--" specially.
1176	 */
1177	if (argc > 1 && strcmp(argv[1], "--") == 0)
1178		argc--, argv++;
1179	if (argc > 1) {
1180		struct strlist *sp;
1181
1182		iflag = 0;		/* exit on error */
1183		mflag = 0;
1184		optschanged();
1185		for (sp = cmdenviron; sp ; sp = sp->next)
1186			setvareq(sp->text, VEXPORT|VSTACK);
1187		shellexec(argv + 1, environment(), pathval(), 0);
1188
1189	}
1190	return 0;
1191}
1192
1193
1194int
1195timescmd(int argc __unused, char **argv __unused)
1196{
1197	struct rusage ru;
1198	long shumins, shsmins, chumins, chsmins;
1199	double shusecs, shssecs, chusecs, chssecs;
1200
1201	if (getrusage(RUSAGE_SELF, &ru) < 0)
1202		return 1;
1203	shumins = ru.ru_utime.tv_sec / 60;
1204	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1205	shsmins = ru.ru_stime.tv_sec / 60;
1206	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1207	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1208		return 1;
1209	chumins = ru.ru_utime.tv_sec / 60;
1210	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1211	chsmins = ru.ru_stime.tv_sec / 60;
1212	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1213	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1214	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1215	return 0;
1216}
1217