/bin/sh/eval.c

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