xref: /freebsd/bin/sh/parser.c (revision cc3f4b99653c34ae64f8a1fddea370abefef680e)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Kenneth Almquist.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 #if 0
35 static char sccsid[] = "@(#)parser.c	8.7 (Berkeley) 5/16/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include <stdlib.h>
42 #include <unistd.h>
43 #include <stdio.h>
44 
45 #include "shell.h"
46 #include "parser.h"
47 #include "nodes.h"
48 #include "expand.h"	/* defines rmescapes() */
49 #include "syntax.h"
50 #include "options.h"
51 #include "input.h"
52 #include "output.h"
53 #include "var.h"
54 #include "error.h"
55 #include "memalloc.h"
56 #include "mystring.h"
57 #include "alias.h"
58 #include "show.h"
59 #include "eval.h"
60 #include "exec.h"	/* to check for special builtins */
61 #ifndef NO_HISTORY
62 #include "myhistedit.h"
63 #endif
64 
65 /*
66  * Shell command parser.
67  */
68 
69 #define	EOFMARKLEN	79
70 #define	PROMPTLEN	128
71 
72 /* values of checkkwd variable */
73 #define CHKALIAS	0x1
74 #define CHKKWD		0x2
75 #define CHKNL		0x4
76 
77 /* values returned by readtoken */
78 #include "token.h"
79 
80 
81 
82 struct heredoc {
83 	struct heredoc *next;	/* next here document in list */
84 	union node *here;		/* redirection node */
85 	char *eofmark;		/* string indicating end of input */
86 	int striptabs;		/* if set, strip leading tabs */
87 };
88 
89 struct parser_temp {
90 	struct parser_temp *next;
91 	void *data;
92 };
93 
94 
95 static struct heredoc *heredoclist;	/* list of here documents to read */
96 static int doprompt;		/* if set, prompt the user */
97 static int needprompt;		/* true if interactive and at start of line */
98 static int lasttoken;		/* last token read */
99 static int tokpushback;		/* last token pushed back */
100 static char *wordtext;		/* text of last word returned by readtoken */
101 static int checkkwd;
102 static struct nodelist *backquotelist;
103 static union node *redirnode;
104 static struct heredoc *heredoc;
105 static int quoteflag;		/* set if (part of) last token was quoted */
106 static int startlinno;		/* line # where last token started */
107 static int funclinno;		/* line # where the current function started */
108 static struct parser_temp *parser_temp;
109 
110 
111 static union node *list(int);
112 static union node *andor(void);
113 static union node *pipeline(void);
114 static union node *command(void);
115 static union node *simplecmd(union node **, union node *);
116 static union node *makename(void);
117 static union node *makebinary(int type, union node *n1, union node *n2);
118 static void parsefname(void);
119 static void parseheredoc(void);
120 static int peektoken(void);
121 static int readtoken(void);
122 static int xxreadtoken(void);
123 static int readtoken1(int, const char *, const char *, int);
124 static int noexpand(char *);
125 static void consumetoken(int);
126 static void synexpect(int) __dead2;
127 static void synerror(const char *) __dead2;
128 static void setprompt(int);
129 
130 
131 static void *
132 parser_temp_alloc(size_t len)
133 {
134 	struct parser_temp *t;
135 
136 	INTOFF;
137 	t = ckmalloc(sizeof(*t));
138 	t->data = NULL;
139 	t->next = parser_temp;
140 	parser_temp = t;
141 	t->data = ckmalloc(len);
142 	INTON;
143 	return t->data;
144 }
145 
146 
147 static void *
148 parser_temp_realloc(void *ptr, size_t len)
149 {
150 	struct parser_temp *t;
151 
152 	INTOFF;
153 	t = parser_temp;
154 	if (ptr != t->data)
155 		error("bug: parser_temp_realloc misused");
156 	t->data = ckrealloc(t->data, len);
157 	INTON;
158 	return t->data;
159 }
160 
161 
162 static void
163 parser_temp_free_upto(void *ptr)
164 {
165 	struct parser_temp *t;
166 	int done = 0;
167 
168 	INTOFF;
169 	while (parser_temp != NULL && !done) {
170 		t = parser_temp;
171 		parser_temp = t->next;
172 		done = t->data == ptr;
173 		ckfree(t->data);
174 		ckfree(t);
175 	}
176 	INTON;
177 	if (!done)
178 		error("bug: parser_temp_free_upto misused");
179 }
180 
181 
182 static void
183 parser_temp_free_all(void)
184 {
185 	struct parser_temp *t;
186 
187 	INTOFF;
188 	while (parser_temp != NULL) {
189 		t = parser_temp;
190 		parser_temp = t->next;
191 		ckfree(t->data);
192 		ckfree(t);
193 	}
194 	INTON;
195 }
196 
197 
198 /*
199  * Read and parse a command.  Returns NEOF on end of file.  (NULL is a
200  * valid parse tree indicating a blank line.)
201  */
202 
203 union node *
204 parsecmd(int interact)
205 {
206 	int t;
207 
208 	/* This assumes the parser is not re-entered,
209 	 * which could happen if we add command substitution on PS1/PS2.
210 	 */
211 	parser_temp_free_all();
212 	heredoclist = NULL;
213 
214 	tokpushback = 0;
215 	checkkwd = 0;
216 	doprompt = interact;
217 	if (doprompt)
218 		setprompt(1);
219 	else
220 		setprompt(0);
221 	needprompt = 0;
222 	t = readtoken();
223 	if (t == TEOF)
224 		return NEOF;
225 	if (t == TNL)
226 		return NULL;
227 	tokpushback++;
228 	return list(1);
229 }
230 
231 
232 static union node *
233 list(int nlflag)
234 {
235 	union node *ntop, *n1, *n2, *n3;
236 	int tok;
237 
238 	checkkwd = CHKNL | CHKKWD | CHKALIAS;
239 	if (!nlflag && tokendlist[peektoken()])
240 		return NULL;
241 	ntop = n1 = NULL;
242 	for (;;) {
243 		n2 = andor();
244 		tok = readtoken();
245 		if (tok == TBACKGND) {
246 			if (n2 != NULL && n2->type == NPIPE) {
247 				n2->npipe.backgnd = 1;
248 			} else if (n2 != NULL && n2->type == NREDIR) {
249 				n2->type = NBACKGND;
250 			} else {
251 				n3 = (union node *)stalloc(sizeof (struct nredir));
252 				n3->type = NBACKGND;
253 				n3->nredir.n = n2;
254 				n3->nredir.redirect = NULL;
255 				n2 = n3;
256 			}
257 		}
258 		if (ntop == NULL)
259 			ntop = n2;
260 		else if (n1 == NULL) {
261 			n1 = makebinary(NSEMI, ntop, n2);
262 			ntop = n1;
263 		}
264 		else {
265 			n3 = makebinary(NSEMI, n1->nbinary.ch2, n2);
266 			n1->nbinary.ch2 = n3;
267 			n1 = n3;
268 		}
269 		switch (tok) {
270 		case TBACKGND:
271 		case TSEMI:
272 			tok = readtoken();
273 			/* FALLTHROUGH */
274 		case TNL:
275 			if (tok == TNL) {
276 				parseheredoc();
277 				if (nlflag)
278 					return ntop;
279 			} else if (tok == TEOF && nlflag) {
280 				parseheredoc();
281 				return ntop;
282 			} else {
283 				tokpushback++;
284 			}
285 			checkkwd = CHKNL | CHKKWD | CHKALIAS;
286 			if (!nlflag && tokendlist[peektoken()])
287 				return ntop;
288 			break;
289 		case TEOF:
290 			if (heredoclist)
291 				parseheredoc();
292 			else
293 				pungetc();		/* push back EOF on input */
294 			return ntop;
295 		default:
296 			if (nlflag)
297 				synexpect(-1);
298 			tokpushback++;
299 			return ntop;
300 		}
301 	}
302 }
303 
304 
305 
306 static union node *
307 andor(void)
308 {
309 	union node *n;
310 	int t;
311 
312 	n = pipeline();
313 	for (;;) {
314 		if ((t = readtoken()) == TAND) {
315 			t = NAND;
316 		} else if (t == TOR) {
317 			t = NOR;
318 		} else {
319 			tokpushback++;
320 			return n;
321 		}
322 		n = makebinary(t, n, pipeline());
323 	}
324 }
325 
326 
327 
328 static union node *
329 pipeline(void)
330 {
331 	union node *n1, *n2, *pipenode;
332 	struct nodelist *lp, *prev;
333 	int negate, t;
334 
335 	negate = 0;
336 	checkkwd = CHKNL | CHKKWD | CHKALIAS;
337 	TRACE(("pipeline: entered\n"));
338 	while (readtoken() == TNOT)
339 		negate = !negate;
340 	tokpushback++;
341 	n1 = command();
342 	if (readtoken() == TPIPE) {
343 		pipenode = (union node *)stalloc(sizeof (struct npipe));
344 		pipenode->type = NPIPE;
345 		pipenode->npipe.backgnd = 0;
346 		lp = (struct nodelist *)stalloc(sizeof (struct nodelist));
347 		pipenode->npipe.cmdlist = lp;
348 		lp->n = n1;
349 		do {
350 			prev = lp;
351 			lp = (struct nodelist *)stalloc(sizeof (struct nodelist));
352 			checkkwd = CHKNL | CHKKWD | CHKALIAS;
353 			t = readtoken();
354 			tokpushback++;
355 			if (t == TNOT)
356 				lp->n = pipeline();
357 			else
358 				lp->n = command();
359 			prev->next = lp;
360 		} while (readtoken() == TPIPE);
361 		lp->next = NULL;
362 		n1 = pipenode;
363 	}
364 	tokpushback++;
365 	if (negate) {
366 		n2 = (union node *)stalloc(sizeof (struct nnot));
367 		n2->type = NNOT;
368 		n2->nnot.com = n1;
369 		return n2;
370 	} else
371 		return n1;
372 }
373 
374 
375 
376 static union node *
377 command(void)
378 {
379 	union node *n1, *n2;
380 	union node *ap, **app;
381 	union node *cp, **cpp;
382 	union node *redir, **rpp;
383 	int t;
384 	int is_subshell;
385 
386 	checkkwd = CHKNL | CHKKWD | CHKALIAS;
387 	is_subshell = 0;
388 	redir = NULL;
389 	n1 = NULL;
390 	rpp = &redir;
391 
392 	/* Check for redirection which may precede command */
393 	while (readtoken() == TREDIR) {
394 		*rpp = n2 = redirnode;
395 		rpp = &n2->nfile.next;
396 		parsefname();
397 	}
398 	tokpushback++;
399 
400 	switch (readtoken()) {
401 	case TIF:
402 		n1 = (union node *)stalloc(sizeof (struct nif));
403 		n1->type = NIF;
404 		if ((n1->nif.test = list(0)) == NULL)
405 			synexpect(-1);
406 		consumetoken(TTHEN);
407 		n1->nif.ifpart = list(0);
408 		n2 = n1;
409 		while (readtoken() == TELIF) {
410 			n2->nif.elsepart = (union node *)stalloc(sizeof (struct nif));
411 			n2 = n2->nif.elsepart;
412 			n2->type = NIF;
413 			if ((n2->nif.test = list(0)) == NULL)
414 				synexpect(-1);
415 			consumetoken(TTHEN);
416 			n2->nif.ifpart = list(0);
417 		}
418 		if (lasttoken == TELSE)
419 			n2->nif.elsepart = list(0);
420 		else {
421 			n2->nif.elsepart = NULL;
422 			tokpushback++;
423 		}
424 		consumetoken(TFI);
425 		checkkwd = CHKKWD | CHKALIAS;
426 		break;
427 	case TWHILE:
428 	case TUNTIL:
429 		t = lasttoken;
430 		if ((n1 = list(0)) == NULL)
431 			synexpect(-1);
432 		consumetoken(TDO);
433 		n1 = makebinary((t == TWHILE)? NWHILE : NUNTIL, n1, list(0));
434 		consumetoken(TDONE);
435 		checkkwd = CHKKWD | CHKALIAS;
436 		break;
437 	case TFOR:
438 		if (readtoken() != TWORD || quoteflag || ! goodname(wordtext))
439 			synerror("Bad for loop variable");
440 		n1 = (union node *)stalloc(sizeof (struct nfor));
441 		n1->type = NFOR;
442 		n1->nfor.var = wordtext;
443 		while (readtoken() == TNL)
444 			;
445 		if (lasttoken == TWORD && ! quoteflag && equal(wordtext, "in")) {
446 			app = &ap;
447 			while (readtoken() == TWORD) {
448 				n2 = makename();
449 				*app = n2;
450 				app = &n2->narg.next;
451 			}
452 			*app = NULL;
453 			n1->nfor.args = ap;
454 			if (lasttoken != TNL && lasttoken != TSEMI)
455 				synexpect(-1);
456 		} else {
457 			static char argvars[5] = {
458 				CTLVAR, VSNORMAL|VSQUOTE, '@', '=', '\0'
459 			};
460 			n2 = (union node *)stalloc(sizeof (struct narg));
461 			n2->type = NARG;
462 			n2->narg.text = argvars;
463 			n2->narg.backquote = NULL;
464 			n2->narg.next = NULL;
465 			n1->nfor.args = n2;
466 			/*
467 			 * Newline or semicolon here is optional (but note
468 			 * that the original Bourne shell only allowed NL).
469 			 */
470 			if (lasttoken != TNL && lasttoken != TSEMI)
471 				tokpushback++;
472 		}
473 		checkkwd = CHKNL | CHKKWD | CHKALIAS;
474 		if ((t = readtoken()) == TDO)
475 			t = TDONE;
476 		else if (t == TBEGIN)
477 			t = TEND;
478 		else
479 			synexpect(-1);
480 		n1->nfor.body = list(0);
481 		consumetoken(t);
482 		checkkwd = CHKKWD | CHKALIAS;
483 		break;
484 	case TCASE:
485 		n1 = (union node *)stalloc(sizeof (struct ncase));
486 		n1->type = NCASE;
487 		consumetoken(TWORD);
488 		n1->ncase.expr = makename();
489 		while (readtoken() == TNL);
490 		if (lasttoken != TWORD || ! equal(wordtext, "in"))
491 			synerror("expecting \"in\"");
492 		cpp = &n1->ncase.cases;
493 		checkkwd = CHKNL | CHKKWD, readtoken();
494 		while (lasttoken != TESAC) {
495 			*cpp = cp = (union node *)stalloc(sizeof (struct nclist));
496 			cp->type = NCLIST;
497 			app = &cp->nclist.pattern;
498 			if (lasttoken == TLP)
499 				readtoken();
500 			for (;;) {
501 				*app = ap = makename();
502 				checkkwd = CHKNL | CHKKWD;
503 				if (readtoken() != TPIPE)
504 					break;
505 				app = &ap->narg.next;
506 				readtoken();
507 			}
508 			ap->narg.next = NULL;
509 			if (lasttoken != TRP)
510 				synexpect(TRP);
511 			cp->nclist.body = list(0);
512 
513 			checkkwd = CHKNL | CHKKWD | CHKALIAS;
514 			if ((t = readtoken()) != TESAC) {
515 				if (t == TENDCASE)
516 					;
517 				else if (t == TFALLTHRU)
518 					cp->type = NCLISTFALLTHRU;
519 				else
520 					synexpect(TENDCASE);
521 				checkkwd = CHKNL | CHKKWD, readtoken();
522 			}
523 			cpp = &cp->nclist.next;
524 		}
525 		*cpp = NULL;
526 		checkkwd = CHKKWD | CHKALIAS;
527 		break;
528 	case TLP:
529 		n1 = (union node *)stalloc(sizeof (struct nredir));
530 		n1->type = NSUBSHELL;
531 		n1->nredir.n = list(0);
532 		n1->nredir.redirect = NULL;
533 		consumetoken(TRP);
534 		checkkwd = CHKKWD | CHKALIAS;
535 		is_subshell = 1;
536 		break;
537 	case TBEGIN:
538 		n1 = list(0);
539 		consumetoken(TEND);
540 		checkkwd = CHKKWD | CHKALIAS;
541 		break;
542 	/* A simple command must have at least one redirection or word. */
543 	case TBACKGND:
544 	case TSEMI:
545 	case TAND:
546 	case TOR:
547 	case TPIPE:
548 	case TENDCASE:
549 	case TFALLTHRU:
550 	case TEOF:
551 	case TNL:
552 	case TRP:
553 		if (!redir)
554 			synexpect(-1);
555 	case TWORD:
556 		tokpushback++;
557 		n1 = simplecmd(rpp, redir);
558 		return n1;
559 	default:
560 		synexpect(-1);
561 	}
562 
563 	/* Now check for redirection which may follow command */
564 	while (readtoken() == TREDIR) {
565 		*rpp = n2 = redirnode;
566 		rpp = &n2->nfile.next;
567 		parsefname();
568 	}
569 	tokpushback++;
570 	*rpp = NULL;
571 	if (redir) {
572 		if (!is_subshell) {
573 			n2 = (union node *)stalloc(sizeof (struct nredir));
574 			n2->type = NREDIR;
575 			n2->nredir.n = n1;
576 			n1 = n2;
577 		}
578 		n1->nredir.redirect = redir;
579 	}
580 
581 	return n1;
582 }
583 
584 
585 static union node *
586 simplecmd(union node **rpp, union node *redir)
587 {
588 	union node *args, **app;
589 	union node **orig_rpp = rpp;
590 	union node *n = NULL;
591 	int special;
592 	int savecheckkwd;
593 
594 	/* If we don't have any redirections already, then we must reset */
595 	/* rpp to be the address of the local redir variable.  */
596 	if (redir == 0)
597 		rpp = &redir;
598 
599 	args = NULL;
600 	app = &args;
601 	/*
602 	 * We save the incoming value, because we need this for shell
603 	 * functions.  There can not be a redirect or an argument between
604 	 * the function name and the open parenthesis.
605 	 */
606 	orig_rpp = rpp;
607 
608 	savecheckkwd = CHKALIAS;
609 
610 	for (;;) {
611 		checkkwd = savecheckkwd;
612 		if (readtoken() == TWORD) {
613 			n = makename();
614 			*app = n;
615 			app = &n->narg.next;
616 			if (savecheckkwd != 0 && !isassignment(wordtext))
617 				savecheckkwd = 0;
618 		} else if (lasttoken == TREDIR) {
619 			*rpp = n = redirnode;
620 			rpp = &n->nfile.next;
621 			parsefname();	/* read name of redirection file */
622 		} else if (lasttoken == TLP && app == &args->narg.next
623 					    && rpp == orig_rpp) {
624 			/* We have a function */
625 			consumetoken(TRP);
626 			funclinno = plinno;
627 			/*
628 			 * - Require plain text.
629 			 * - Functions with '/' cannot be called.
630 			 * - Reject name=().
631 			 * - Reject ksh extended glob patterns.
632 			 */
633 			if (!noexpand(n->narg.text) || quoteflag ||
634 			    strchr(n->narg.text, '/') ||
635 			    strchr("!%*+-=?@}~",
636 				n->narg.text[strlen(n->narg.text) - 1]))
637 				synerror("Bad function name");
638 			rmescapes(n->narg.text);
639 			if (find_builtin(n->narg.text, &special) >= 0 &&
640 			    special)
641 				synerror("Cannot override a special builtin with a function");
642 			n->type = NDEFUN;
643 			n->narg.next = command();
644 			funclinno = 0;
645 			return n;
646 		} else {
647 			tokpushback++;
648 			break;
649 		}
650 	}
651 	*app = NULL;
652 	*rpp = NULL;
653 	n = (union node *)stalloc(sizeof (struct ncmd));
654 	n->type = NCMD;
655 	n->ncmd.args = args;
656 	n->ncmd.redirect = redir;
657 	return n;
658 }
659 
660 static union node *
661 makename(void)
662 {
663 	union node *n;
664 
665 	n = (union node *)stalloc(sizeof (struct narg));
666 	n->type = NARG;
667 	n->narg.next = NULL;
668 	n->narg.text = wordtext;
669 	n->narg.backquote = backquotelist;
670 	return n;
671 }
672 
673 static union node *
674 makebinary(int type, union node *n1, union node *n2)
675 {
676 	union node *n;
677 
678 	n = (union node *)stalloc(sizeof (struct nbinary));
679 	n->type = type;
680 	n->nbinary.ch1 = n1;
681 	n->nbinary.ch2 = n2;
682 	return (n);
683 }
684 
685 void
686 forcealias(void)
687 {
688 	checkkwd |= CHKALIAS;
689 }
690 
691 void
692 fixredir(union node *n, const char *text, int err)
693 {
694 	TRACE(("Fix redir %s %d\n", text, err));
695 	if (!err)
696 		n->ndup.vname = NULL;
697 
698 	if (is_digit(text[0]) && text[1] == '\0')
699 		n->ndup.dupfd = digit_val(text[0]);
700 	else if (text[0] == '-' && text[1] == '\0')
701 		n->ndup.dupfd = -1;
702 	else {
703 
704 		if (err)
705 			synerror("Bad fd number");
706 		else
707 			n->ndup.vname = makename();
708 	}
709 }
710 
711 
712 static void
713 parsefname(void)
714 {
715 	union node *n = redirnode;
716 
717 	consumetoken(TWORD);
718 	if (n->type == NHERE) {
719 		struct heredoc *here = heredoc;
720 		struct heredoc *p;
721 		int i;
722 
723 		if (quoteflag == 0)
724 			n->type = NXHERE;
725 		TRACE(("Here document %d\n", n->type));
726 		if (here->striptabs) {
727 			while (*wordtext == '\t')
728 				wordtext++;
729 		}
730 		if (! noexpand(wordtext) || (i = strlen(wordtext)) == 0 || i > EOFMARKLEN)
731 			synerror("Illegal eof marker for << redirection");
732 		rmescapes(wordtext);
733 		here->eofmark = wordtext;
734 		here->next = NULL;
735 		if (heredoclist == NULL)
736 			heredoclist = here;
737 		else {
738 			for (p = heredoclist ; p->next ; p = p->next);
739 			p->next = here;
740 		}
741 	} else if (n->type == NTOFD || n->type == NFROMFD) {
742 		fixredir(n, wordtext, 0);
743 	} else {
744 		n->nfile.fname = makename();
745 	}
746 }
747 
748 
749 /*
750  * Input any here documents.
751  */
752 
753 static void
754 parseheredoc(void)
755 {
756 	struct heredoc *here;
757 	union node *n;
758 
759 	while (heredoclist) {
760 		here = heredoclist;
761 		heredoclist = here->next;
762 		if (needprompt) {
763 			setprompt(2);
764 			needprompt = 0;
765 		}
766 		readtoken1(pgetc(), here->here->type == NHERE? SQSYNTAX : DQSYNTAX,
767 				here->eofmark, here->striptabs);
768 		n = makename();
769 		here->here->nhere.doc = n;
770 	}
771 }
772 
773 static int
774 peektoken(void)
775 {
776 	int t;
777 
778 	t = readtoken();
779 	tokpushback++;
780 	return (t);
781 }
782 
783 static int
784 readtoken(void)
785 {
786 	int t;
787 	struct alias *ap;
788 #ifdef DEBUG
789 	int alreadyseen = tokpushback;
790 #endif
791 
792 	top:
793 	t = xxreadtoken();
794 
795 	/*
796 	 * eat newlines
797 	 */
798 	if (checkkwd & CHKNL) {
799 		while (t == TNL) {
800 			parseheredoc();
801 			t = xxreadtoken();
802 		}
803 	}
804 
805 	/*
806 	 * check for keywords and aliases
807 	 */
808 	if (t == TWORD && !quoteflag)
809 	{
810 		const char * const *pp;
811 
812 		if (checkkwd & CHKKWD)
813 			for (pp = parsekwd; *pp; pp++) {
814 				if (**pp == *wordtext && equal(*pp, wordtext))
815 				{
816 					lasttoken = t = pp - parsekwd + KWDOFFSET;
817 					TRACE(("keyword %s recognized\n", tokname[t]));
818 					goto out;
819 				}
820 			}
821 		if (checkkwd & CHKALIAS &&
822 		    (ap = lookupalias(wordtext, 1)) != NULL) {
823 			pushstring(ap->val, strlen(ap->val), ap);
824 			goto top;
825 		}
826 	}
827 out:
828 	if (t != TNOT)
829 		checkkwd = 0;
830 
831 #ifdef DEBUG
832 	if (!alreadyseen)
833 	    TRACE(("token %s %s\n", tokname[t], t == TWORD ? wordtext : ""));
834 	else
835 	    TRACE(("reread token %s %s\n", tokname[t], t == TWORD ? wordtext : ""));
836 #endif
837 	return (t);
838 }
839 
840 
841 /*
842  * Read the next input token.
843  * If the token is a word, we set backquotelist to the list of cmds in
844  *	backquotes.  We set quoteflag to true if any part of the word was
845  *	quoted.
846  * If the token is TREDIR, then we set redirnode to a structure containing
847  *	the redirection.
848  * In all cases, the variable startlinno is set to the number of the line
849  *	on which the token starts.
850  *
851  * [Change comment:  here documents and internal procedures]
852  * [Readtoken shouldn't have any arguments.  Perhaps we should make the
853  *  word parsing code into a separate routine.  In this case, readtoken
854  *  doesn't need to have any internal procedures, but parseword does.
855  *  We could also make parseoperator in essence the main routine, and
856  *  have parseword (readtoken1?) handle both words and redirection.]
857  */
858 
859 #define RETURN(token)	return lasttoken = token
860 
861 static int
862 xxreadtoken(void)
863 {
864 	int c;
865 
866 	if (tokpushback) {
867 		tokpushback = 0;
868 		return lasttoken;
869 	}
870 	if (needprompt) {
871 		setprompt(2);
872 		needprompt = 0;
873 	}
874 	startlinno = plinno;
875 	for (;;) {	/* until token or start of word found */
876 		c = pgetc_macro();
877 		switch (c) {
878 		case ' ': case '\t':
879 			continue;
880 		case '#':
881 			while ((c = pgetc()) != '\n' && c != PEOF);
882 			pungetc();
883 			continue;
884 		case '\\':
885 			if (pgetc() == '\n') {
886 				startlinno = ++plinno;
887 				if (doprompt)
888 					setprompt(2);
889 				else
890 					setprompt(0);
891 				continue;
892 			}
893 			pungetc();
894 			goto breakloop;
895 		case '\n':
896 			plinno++;
897 			needprompt = doprompt;
898 			RETURN(TNL);
899 		case PEOF:
900 			RETURN(TEOF);
901 		case '&':
902 			if (pgetc() == '&')
903 				RETURN(TAND);
904 			pungetc();
905 			RETURN(TBACKGND);
906 		case '|':
907 			if (pgetc() == '|')
908 				RETURN(TOR);
909 			pungetc();
910 			RETURN(TPIPE);
911 		case ';':
912 			c = pgetc();
913 			if (c == ';')
914 				RETURN(TENDCASE);
915 			else if (c == '&')
916 				RETURN(TFALLTHRU);
917 			pungetc();
918 			RETURN(TSEMI);
919 		case '(':
920 			RETURN(TLP);
921 		case ')':
922 			RETURN(TRP);
923 		default:
924 			goto breakloop;
925 		}
926 	}
927 breakloop:
928 	return readtoken1(c, BASESYNTAX, (char *)NULL, 0);
929 #undef RETURN
930 }
931 
932 
933 #define MAXNEST_static 8
934 struct tokenstate
935 {
936 	const char *syntax; /* *SYNTAX */
937 	int parenlevel; /* levels of parentheses in arithmetic */
938 	enum tokenstate_category
939 	{
940 		TSTATE_TOP,
941 		TSTATE_VAR_OLD, /* ${var+-=?}, inherits dquotes */
942 		TSTATE_VAR_NEW, /* other ${var...}, own dquote state */
943 		TSTATE_ARITH
944 	} category;
945 };
946 
947 
948 /*
949  * Called to parse command substitutions.
950  */
951 
952 static char *
953 parsebackq(char *out, struct nodelist **pbqlist,
954 		int oldstyle, int dblquote, int quoted)
955 {
956 	struct nodelist **nlpp;
957 	union node *n;
958 	char *volatile str;
959 	struct jmploc jmploc;
960 	struct jmploc *const savehandler = handler;
961 	size_t savelen;
962 	int saveprompt;
963 	const int bq_startlinno = plinno;
964 	char *volatile ostr = NULL;
965 	struct parsefile *const savetopfile = getcurrentfile();
966 	struct heredoc *const saveheredoclist = heredoclist;
967 	struct heredoc *here;
968 
969 	str = NULL;
970 	if (setjmp(jmploc.loc)) {
971 		popfilesupto(savetopfile);
972 		if (str)
973 			ckfree(str);
974 		if (ostr)
975 			ckfree(ostr);
976 		heredoclist = saveheredoclist;
977 		handler = savehandler;
978 		if (exception == EXERROR) {
979 			startlinno = bq_startlinno;
980 			synerror("Error in command substitution");
981 		}
982 		longjmp(handler->loc, 1);
983 	}
984 	INTOFF;
985 	savelen = out - stackblock();
986 	if (savelen > 0) {
987 		str = ckmalloc(savelen);
988 		memcpy(str, stackblock(), savelen);
989 	}
990 	handler = &jmploc;
991 	heredoclist = NULL;
992 	INTON;
993         if (oldstyle) {
994                 /* We must read until the closing backquote, giving special
995                    treatment to some slashes, and then push the string and
996                    reread it as input, interpreting it normally.  */
997                 char *oout;
998                 int c;
999                 int olen;
1000 
1001 
1002                 STARTSTACKSTR(oout);
1003 		for (;;) {
1004 			if (needprompt) {
1005 				setprompt(2);
1006 				needprompt = 0;
1007 			}
1008 			CHECKSTRSPACE(2, oout);
1009 			switch (c = pgetc()) {
1010 			case '`':
1011 				goto done;
1012 
1013 			case '\\':
1014                                 if ((c = pgetc()) == '\n') {
1015 					plinno++;
1016 					if (doprompt)
1017 						setprompt(2);
1018 					else
1019 						setprompt(0);
1020 					/*
1021 					 * If eating a newline, avoid putting
1022 					 * the newline into the new character
1023 					 * stream (via the USTPUTC after the
1024 					 * switch).
1025 					 */
1026 					continue;
1027 				}
1028                                 if (c != '\\' && c != '`' && c != '$'
1029                                     && (!dblquote || c != '"'))
1030                                         USTPUTC('\\', oout);
1031 				break;
1032 
1033 			case '\n':
1034 				plinno++;
1035 				needprompt = doprompt;
1036 				break;
1037 
1038 			case PEOF:
1039 			        startlinno = plinno;
1040 				synerror("EOF in backquote substitution");
1041  				break;
1042 
1043 			default:
1044 				break;
1045 			}
1046 			USTPUTC(c, oout);
1047                 }
1048 done:
1049                 USTPUTC('\0', oout);
1050                 olen = oout - stackblock();
1051 		INTOFF;
1052 		ostr = ckmalloc(olen);
1053 		memcpy(ostr, stackblock(), olen);
1054 		setinputstring(ostr, 1);
1055 		INTON;
1056         }
1057 	nlpp = pbqlist;
1058 	while (*nlpp)
1059 		nlpp = &(*nlpp)->next;
1060 	*nlpp = (struct nodelist *)stalloc(sizeof (struct nodelist));
1061 	(*nlpp)->next = NULL;
1062 
1063 	if (oldstyle) {
1064 		saveprompt = doprompt;
1065 		doprompt = 0;
1066 	}
1067 
1068 	n = list(0);
1069 
1070 	if (oldstyle) {
1071 		if (peektoken() != TEOF)
1072 			synexpect(-1);
1073 		doprompt = saveprompt;
1074 	} else
1075 		consumetoken(TRP);
1076 
1077 	(*nlpp)->n = n;
1078         if (oldstyle) {
1079 		/*
1080 		 * Start reading from old file again, ignoring any pushed back
1081 		 * tokens left from the backquote parsing
1082 		 */
1083                 popfile();
1084 		tokpushback = 0;
1085 	}
1086 	STARTSTACKSTR(out);
1087 	CHECKSTRSPACE(savelen + 1, out);
1088 	INTOFF;
1089 	if (str) {
1090 		memcpy(out, str, savelen);
1091 		STADJUST(savelen, out);
1092 		ckfree(str);
1093 		str = NULL;
1094 	}
1095 	if (ostr) {
1096 		ckfree(ostr);
1097 		ostr = NULL;
1098 	}
1099 	here = saveheredoclist;
1100 	if (here != NULL) {
1101 		while (here->next != NULL)
1102 			here = here->next;
1103 		here->next = heredoclist;
1104 		heredoclist = saveheredoclist;
1105 	}
1106 	handler = savehandler;
1107 	INTON;
1108 	if (quoted)
1109 		USTPUTC(CTLBACKQ | CTLQUOTE, out);
1110 	else
1111 		USTPUTC(CTLBACKQ, out);
1112 	return out;
1113 }
1114 
1115 
1116 /*
1117  * Called to parse a backslash escape sequence inside $'...'.
1118  * The backslash has already been read.
1119  */
1120 static char *
1121 readcstyleesc(char *out)
1122 {
1123 	int c, v, i, n;
1124 
1125 	c = pgetc();
1126 	switch (c) {
1127 	case '\0':
1128 		synerror("Unterminated quoted string");
1129 	case '\n':
1130 		plinno++;
1131 		if (doprompt)
1132 			setprompt(2);
1133 		else
1134 			setprompt(0);
1135 		return out;
1136 	case '\\':
1137 	case '\'':
1138 	case '"':
1139 		v = c;
1140 		break;
1141 	case 'a': v = '\a'; break;
1142 	case 'b': v = '\b'; break;
1143 	case 'e': v = '\033'; break;
1144 	case 'f': v = '\f'; break;
1145 	case 'n': v = '\n'; break;
1146 	case 'r': v = '\r'; break;
1147 	case 't': v = '\t'; break;
1148 	case 'v': v = '\v'; break;
1149 	case 'x':
1150 		  v = 0;
1151 		  for (;;) {
1152 			  c = pgetc();
1153 			  if (c >= '0' && c <= '9')
1154 				  v = (v << 4) + c - '0';
1155 			  else if (c >= 'A' && c <= 'F')
1156 				  v = (v << 4) + c - 'A' + 10;
1157 			  else if (c >= 'a' && c <= 'f')
1158 				  v = (v << 4) + c - 'a' + 10;
1159 			  else
1160 				  break;
1161 		  }
1162 		  pungetc();
1163 		  break;
1164 	case '0': case '1': case '2': case '3':
1165 	case '4': case '5': case '6': case '7':
1166 		  v = c - '0';
1167 		  c = pgetc();
1168 		  if (c >= '0' && c <= '7') {
1169 			  v <<= 3;
1170 			  v += c - '0';
1171 			  c = pgetc();
1172 			  if (c >= '0' && c <= '7') {
1173 				  v <<= 3;
1174 				  v += c - '0';
1175 			  } else
1176 				  pungetc();
1177 		  } else
1178 			  pungetc();
1179 		  break;
1180 	case 'c':
1181 		  c = pgetc();
1182 		  if (c < 0x3f || c > 0x7a || c == 0x60)
1183 			  synerror("Bad escape sequence");
1184 		  if (c == '\\' && pgetc() != '\\')
1185 			  synerror("Bad escape sequence");
1186 		  if (c == '?')
1187 			  v = 127;
1188 		  else
1189 			  v = c & 0x1f;
1190 		  break;
1191 	case 'u':
1192 	case 'U':
1193 		  n = c == 'U' ? 8 : 4;
1194 		  v = 0;
1195 		  for (i = 0; i < n; i++) {
1196 			  c = pgetc();
1197 			  if (c >= '0' && c <= '9')
1198 				  v = (v << 4) + c - '0';
1199 			  else if (c >= 'A' && c <= 'F')
1200 				  v = (v << 4) + c - 'A' + 10;
1201 			  else if (c >= 'a' && c <= 'f')
1202 				  v = (v << 4) + c - 'a' + 10;
1203 			  else
1204 				  synerror("Bad escape sequence");
1205 		  }
1206 		  if (v == 0 || (v >= 0xd800 && v <= 0xdfff))
1207 			  synerror("Bad escape sequence");
1208 		  /* We really need iconv here. */
1209 		  if (initial_localeisutf8 && v > 127) {
1210 			  CHECKSTRSPACE(4, out);
1211 			  /*
1212 			   * We cannot use wctomb() as the locale may have
1213 			   * changed.
1214 			   */
1215 			  if (v <= 0x7ff) {
1216 				  USTPUTC(0xc0 | v >> 6, out);
1217 				  USTPUTC(0x80 | (v & 0x3f), out);
1218 				  return out;
1219 			  } else if (v <= 0xffff) {
1220 				  USTPUTC(0xe0 | v >> 12, out);
1221 				  USTPUTC(0x80 | ((v >> 6) & 0x3f), out);
1222 				  USTPUTC(0x80 | (v & 0x3f), out);
1223 				  return out;
1224 			  } else if (v <= 0x10ffff) {
1225 				  USTPUTC(0xf0 | v >> 18, out);
1226 				  USTPUTC(0x80 | ((v >> 12) & 0x3f), out);
1227 				  USTPUTC(0x80 | ((v >> 6) & 0x3f), out);
1228 				  USTPUTC(0x80 | (v & 0x3f), out);
1229 				  return out;
1230 			  }
1231 		  }
1232 		  if (v > 127)
1233 			  v = '?';
1234 		  break;
1235 	default:
1236 		  synerror("Bad escape sequence");
1237 	}
1238 	v = (char)v;
1239 	/*
1240 	 * We can't handle NUL bytes.
1241 	 * POSIX says we should skip till the closing quote.
1242 	 */
1243 	if (v == '\0') {
1244 		while ((c = pgetc()) != '\'') {
1245 			if (c == '\\')
1246 				c = pgetc();
1247 			if (c == PEOF)
1248 				synerror("Unterminated quoted string");
1249 		}
1250 		pungetc();
1251 		return out;
1252 	}
1253 	if (SQSYNTAX[v] == CCTL)
1254 		USTPUTC(CTLESC, out);
1255 	USTPUTC(v, out);
1256 	return out;
1257 }
1258 
1259 
1260 /*
1261  * If eofmark is NULL, read a word or a redirection symbol.  If eofmark
1262  * is not NULL, read a here document.  In the latter case, eofmark is the
1263  * word which marks the end of the document and striptabs is true if
1264  * leading tabs should be stripped from the document.  The argument firstc
1265  * is the first character of the input token or document.
1266  *
1267  * Because C does not have internal subroutines, I have simulated them
1268  * using goto's to implement the subroutine linkage.  The following macros
1269  * will run code that appears at the end of readtoken1.
1270  */
1271 
1272 #define CHECKEND()	{goto checkend; checkend_return:;}
1273 #define PARSEREDIR()	{goto parseredir; parseredir_return:;}
1274 #define PARSESUB()	{goto parsesub; parsesub_return:;}
1275 #define	PARSEARITH()	{goto parsearith; parsearith_return:;}
1276 
1277 static int
1278 readtoken1(int firstc, char const *initialsyntax, const char *eofmark,
1279     int striptabs)
1280 {
1281 	int c = firstc;
1282 	char *out;
1283 	int len;
1284 	char line[EOFMARKLEN + 1];
1285 	struct nodelist *bqlist;
1286 	int quotef;
1287 	int newvarnest;
1288 	int level;
1289 	int synentry;
1290 	struct tokenstate state_static[MAXNEST_static];
1291 	int maxnest = MAXNEST_static;
1292 	struct tokenstate *state = state_static;
1293 	int sqiscstyle = 0;
1294 
1295 	startlinno = plinno;
1296 	quotef = 0;
1297 	bqlist = NULL;
1298 	newvarnest = 0;
1299 	level = 0;
1300 	state[level].syntax = initialsyntax;
1301 	state[level].parenlevel = 0;
1302 	state[level].category = TSTATE_TOP;
1303 
1304 	STARTSTACKSTR(out);
1305 	loop: {	/* for each line, until end of word */
1306 		CHECKEND();	/* set c to PEOF if at end of here document */
1307 		for (;;) {	/* until end of line or end of word */
1308 			CHECKSTRSPACE(4, out);	/* permit 4 calls to USTPUTC */
1309 
1310 			synentry = state[level].syntax[c];
1311 
1312 			switch(synentry) {
1313 			case CNL:	/* '\n' */
1314 				if (state[level].syntax == BASESYNTAX)
1315 					goto endword;	/* exit outer loop */
1316 				USTPUTC(c, out);
1317 				plinno++;
1318 				if (doprompt)
1319 					setprompt(2);
1320 				else
1321 					setprompt(0);
1322 				c = pgetc();
1323 				goto loop;		/* continue outer loop */
1324 			case CSBACK:
1325 				if (sqiscstyle) {
1326 					out = readcstyleesc(out);
1327 					break;
1328 				}
1329 				/* FALLTHROUGH */
1330 			case CWORD:
1331 				USTPUTC(c, out);
1332 				break;
1333 			case CCTL:
1334 				if (eofmark == NULL || initialsyntax != SQSYNTAX)
1335 					USTPUTC(CTLESC, out);
1336 				USTPUTC(c, out);
1337 				break;
1338 			case CBACK:	/* backslash */
1339 				c = pgetc();
1340 				if (c == PEOF) {
1341 					USTPUTC('\\', out);
1342 					pungetc();
1343 				} else if (c == '\n') {
1344 					plinno++;
1345 					if (doprompt)
1346 						setprompt(2);
1347 					else
1348 						setprompt(0);
1349 				} else {
1350 					if (state[level].syntax == DQSYNTAX &&
1351 					    c != '\\' && c != '`' && c != '$' &&
1352 					    (c != '"' || (eofmark != NULL &&
1353 						newvarnest == 0)) &&
1354 					    (c != '}' || state[level].category != TSTATE_VAR_OLD))
1355 						USTPUTC('\\', out);
1356 					if ((eofmark == NULL ||
1357 					    newvarnest > 0) &&
1358 					    state[level].syntax == BASESYNTAX)
1359 						USTPUTC(CTLQUOTEMARK, out);
1360 					if (SQSYNTAX[c] == CCTL)
1361 						USTPUTC(CTLESC, out);
1362 					USTPUTC(c, out);
1363 					if ((eofmark == NULL ||
1364 					    newvarnest > 0) &&
1365 					    state[level].syntax == BASESYNTAX &&
1366 					    state[level].category == TSTATE_VAR_OLD)
1367 						USTPUTC(CTLQUOTEEND, out);
1368 					quotef++;
1369 				}
1370 				break;
1371 			case CSQUOTE:
1372 				USTPUTC(CTLQUOTEMARK, out);
1373 				state[level].syntax = SQSYNTAX;
1374 				sqiscstyle = 0;
1375 				break;
1376 			case CDQUOTE:
1377 				USTPUTC(CTLQUOTEMARK, out);
1378 				state[level].syntax = DQSYNTAX;
1379 				break;
1380 			case CENDQUOTE:
1381 				if (eofmark != NULL && newvarnest == 0)
1382 					USTPUTC(c, out);
1383 				else {
1384 					if (state[level].category == TSTATE_VAR_OLD)
1385 						USTPUTC(CTLQUOTEEND, out);
1386 					state[level].syntax = BASESYNTAX;
1387 					quotef++;
1388 				}
1389 				break;
1390 			case CVAR:	/* '$' */
1391 				PARSESUB();		/* parse substitution */
1392 				break;
1393 			case CENDVAR:	/* '}' */
1394 				if (level > 0 &&
1395 				    ((state[level].category == TSTATE_VAR_OLD &&
1396 				      state[level].syntax ==
1397 				      state[level - 1].syntax) ||
1398 				    (state[level].category == TSTATE_VAR_NEW &&
1399 				     state[level].syntax == BASESYNTAX))) {
1400 					if (state[level].category == TSTATE_VAR_NEW)
1401 						newvarnest--;
1402 					level--;
1403 					USTPUTC(CTLENDVAR, out);
1404 				} else {
1405 					USTPUTC(c, out);
1406 				}
1407 				break;
1408 			case CLP:	/* '(' in arithmetic */
1409 				state[level].parenlevel++;
1410 				USTPUTC(c, out);
1411 				break;
1412 			case CRP:	/* ')' in arithmetic */
1413 				if (state[level].parenlevel > 0) {
1414 					USTPUTC(c, out);
1415 					--state[level].parenlevel;
1416 				} else {
1417 					if (pgetc() == ')') {
1418 						if (level > 0 &&
1419 						    state[level].category == TSTATE_ARITH) {
1420 							level--;
1421 							USTPUTC(CTLENDARI, out);
1422 						} else
1423 							USTPUTC(')', out);
1424 					} else {
1425 						/*
1426 						 * unbalanced parens
1427 						 *  (don't 2nd guess - no error)
1428 						 */
1429 						pungetc();
1430 						USTPUTC(')', out);
1431 					}
1432 				}
1433 				break;
1434 			case CBQUOTE:	/* '`' */
1435 				out = parsebackq(out, &bqlist, 1,
1436 				    state[level].syntax == DQSYNTAX &&
1437 				    (eofmark == NULL || newvarnest > 0),
1438 				    state[level].syntax == DQSYNTAX || state[level].syntax == ARISYNTAX);
1439 				break;
1440 			case CEOF:
1441 				goto endword;		/* exit outer loop */
1442 			case CIGN:
1443 				break;
1444 			default:
1445 				if (level == 0)
1446 					goto endword;	/* exit outer loop */
1447 				USTPUTC(c, out);
1448 			}
1449 			c = pgetc_macro();
1450 		}
1451 	}
1452 endword:
1453 	if (state[level].syntax == ARISYNTAX)
1454 		synerror("Missing '))'");
1455 	if (state[level].syntax != BASESYNTAX && eofmark == NULL)
1456 		synerror("Unterminated quoted string");
1457 	if (state[level].category == TSTATE_VAR_OLD ||
1458 	    state[level].category == TSTATE_VAR_NEW) {
1459 		startlinno = plinno;
1460 		synerror("Missing '}'");
1461 	}
1462 	if (state != state_static)
1463 		parser_temp_free_upto(state);
1464 	USTPUTC('\0', out);
1465 	len = out - stackblock();
1466 	out = stackblock();
1467 	if (eofmark == NULL) {
1468 		if ((c == '>' || c == '<')
1469 		 && quotef == 0
1470 		 && len <= 2
1471 		 && (*out == '\0' || is_digit(*out))) {
1472 			PARSEREDIR();
1473 			return lasttoken = TREDIR;
1474 		} else {
1475 			pungetc();
1476 		}
1477 	}
1478 	quoteflag = quotef;
1479 	backquotelist = bqlist;
1480 	grabstackblock(len);
1481 	wordtext = out;
1482 	return lasttoken = TWORD;
1483 /* end of readtoken routine */
1484 
1485 
1486 /*
1487  * Check to see whether we are at the end of the here document.  When this
1488  * is called, c is set to the first character of the next input line.  If
1489  * we are at the end of the here document, this routine sets the c to PEOF.
1490  */
1491 
1492 checkend: {
1493 	if (eofmark) {
1494 		if (striptabs) {
1495 			while (c == '\t')
1496 				c = pgetc();
1497 		}
1498 		if (c == *eofmark) {
1499 			if (pfgets(line, sizeof line) != NULL) {
1500 				const char *p, *q;
1501 
1502 				p = line;
1503 				for (q = eofmark + 1 ; *q && *p == *q ; p++, q++);
1504 				if ((*p == '\0' || *p == '\n') && *q == '\0') {
1505 					c = PEOF;
1506 					if (*p == '\n') {
1507 						plinno++;
1508 						needprompt = doprompt;
1509 					}
1510 				} else {
1511 					pushstring(line, strlen(line), NULL);
1512 				}
1513 			}
1514 		}
1515 	}
1516 	goto checkend_return;
1517 }
1518 
1519 
1520 /*
1521  * Parse a redirection operator.  The variable "out" points to a string
1522  * specifying the fd to be redirected.  The variable "c" contains the
1523  * first character of the redirection operator.
1524  */
1525 
1526 parseredir: {
1527 	char fd = *out;
1528 	union node *np;
1529 
1530 	np = (union node *)stalloc(sizeof (struct nfile));
1531 	if (c == '>') {
1532 		np->nfile.fd = 1;
1533 		c = pgetc();
1534 		if (c == '>')
1535 			np->type = NAPPEND;
1536 		else if (c == '&')
1537 			np->type = NTOFD;
1538 		else if (c == '|')
1539 			np->type = NCLOBBER;
1540 		else {
1541 			np->type = NTO;
1542 			pungetc();
1543 		}
1544 	} else {	/* c == '<' */
1545 		np->nfile.fd = 0;
1546 		c = pgetc();
1547 		if (c == '<') {
1548 			if (sizeof (struct nfile) != sizeof (struct nhere)) {
1549 				np = (union node *)stalloc(sizeof (struct nhere));
1550 				np->nfile.fd = 0;
1551 			}
1552 			np->type = NHERE;
1553 			heredoc = (struct heredoc *)stalloc(sizeof (struct heredoc));
1554 			heredoc->here = np;
1555 			if ((c = pgetc()) == '-') {
1556 				heredoc->striptabs = 1;
1557 			} else {
1558 				heredoc->striptabs = 0;
1559 				pungetc();
1560 			}
1561 		} else if (c == '&')
1562 			np->type = NFROMFD;
1563 		else if (c == '>')
1564 			np->type = NFROMTO;
1565 		else {
1566 			np->type = NFROM;
1567 			pungetc();
1568 		}
1569 	}
1570 	if (fd != '\0')
1571 		np->nfile.fd = digit_val(fd);
1572 	redirnode = np;
1573 	goto parseredir_return;
1574 }
1575 
1576 
1577 /*
1578  * Parse a substitution.  At this point, we have read the dollar sign
1579  * and nothing else.
1580  */
1581 
1582 parsesub: {
1583 	char buf[10];
1584 	int subtype;
1585 	int typeloc;
1586 	int flags;
1587 	char *p;
1588 	static const char types[] = "}-+?=";
1589 	int bracketed_name = 0; /* used to handle ${[0-9]*} variables */
1590 	int linno;
1591 	int length;
1592 	int c1;
1593 
1594 	c = pgetc();
1595 	if (c == '(') {	/* $(command) or $((arith)) */
1596 		if (pgetc() == '(') {
1597 			PARSEARITH();
1598 		} else {
1599 			pungetc();
1600 			out = parsebackq(out, &bqlist, 0,
1601 			    state[level].syntax == DQSYNTAX &&
1602 			    (eofmark == NULL || newvarnest > 0),
1603 			    state[level].syntax == DQSYNTAX ||
1604 			    state[level].syntax == ARISYNTAX);
1605 		}
1606 	} else if (c == '{' || is_name(c) || is_special(c)) {
1607 		USTPUTC(CTLVAR, out);
1608 		typeloc = out - stackblock();
1609 		USTPUTC(VSNORMAL, out);
1610 		subtype = VSNORMAL;
1611 		flags = 0;
1612 		if (c == '{') {
1613 			bracketed_name = 1;
1614 			c = pgetc();
1615 			subtype = 0;
1616 		}
1617 varname:
1618 		if (!is_eof(c) && is_name(c)) {
1619 			length = 0;
1620 			do {
1621 				STPUTC(c, out);
1622 				c = pgetc();
1623 				length++;
1624 			} while (!is_eof(c) && is_in_name(c));
1625 			if (length == 6 &&
1626 			    strncmp(out - length, "LINENO", length) == 0) {
1627 				/* Replace the variable name with the
1628 				 * current line number. */
1629 				linno = plinno;
1630 				if (funclinno != 0)
1631 					linno -= funclinno - 1;
1632 				snprintf(buf, sizeof(buf), "%d", linno);
1633 				STADJUST(-6, out);
1634 				STPUTS(buf, out);
1635 				flags |= VSLINENO;
1636 			}
1637 		} else if (is_digit(c)) {
1638 			if (bracketed_name) {
1639 				do {
1640 					STPUTC(c, out);
1641 					c = pgetc();
1642 				} while (is_digit(c));
1643 			} else {
1644 				STPUTC(c, out);
1645 				c = pgetc();
1646 			}
1647 		} else if (is_special(c)) {
1648 			c1 = c;
1649 			c = pgetc();
1650 			if (subtype == 0 && c1 == '#') {
1651 				subtype = VSLENGTH;
1652 				if (strchr(types, c) == NULL && c != ':' &&
1653 				    c != '#' && c != '%')
1654 					goto varname;
1655 				c1 = c;
1656 				c = pgetc();
1657 				if (c1 != '}' && c == '}') {
1658 					pungetc();
1659 					c = c1;
1660 					goto varname;
1661 				}
1662 				pungetc();
1663 				c = c1;
1664 				c1 = '#';
1665 				subtype = 0;
1666 			}
1667 			USTPUTC(c1, out);
1668 		} else {
1669 			subtype = VSERROR;
1670 			if (c == '}')
1671 				pungetc();
1672 			else if (c == '\n' || c == PEOF)
1673 				synerror("Unexpected end of line in substitution");
1674 			else
1675 				USTPUTC(c, out);
1676 		}
1677 		if (subtype == 0) {
1678 			switch (c) {
1679 			case ':':
1680 				flags |= VSNUL;
1681 				c = pgetc();
1682 				/*FALLTHROUGH*/
1683 			default:
1684 				p = strchr(types, c);
1685 				if (p == NULL) {
1686 					if (c == '\n' || c == PEOF)
1687 						synerror("Unexpected end of line in substitution");
1688 					if (flags == VSNUL)
1689 						STPUTC(':', out);
1690 					STPUTC(c, out);
1691 					subtype = VSERROR;
1692 				} else
1693 					subtype = p - types + VSNORMAL;
1694 				break;
1695 			case '%':
1696 			case '#':
1697 				{
1698 					int cc = c;
1699 					subtype = c == '#' ? VSTRIMLEFT :
1700 							     VSTRIMRIGHT;
1701 					c = pgetc();
1702 					if (c == cc)
1703 						subtype++;
1704 					else
1705 						pungetc();
1706 					break;
1707 				}
1708 			}
1709 		} else if (subtype != VSERROR) {
1710 			if (subtype == VSLENGTH && c != '}')
1711 				subtype = VSERROR;
1712 			pungetc();
1713 		}
1714 		STPUTC('=', out);
1715 		if (state[level].syntax == DQSYNTAX ||
1716 		    state[level].syntax == ARISYNTAX)
1717 			flags |= VSQUOTE;
1718 		*(stackblock() + typeloc) = subtype | flags;
1719 		if (subtype != VSNORMAL) {
1720 			if (level + 1 >= maxnest) {
1721 				maxnest *= 2;
1722 				if (state == state_static) {
1723 					state = parser_temp_alloc(
1724 					    maxnest * sizeof(*state));
1725 					memcpy(state, state_static,
1726 					    MAXNEST_static * sizeof(*state));
1727 				} else
1728 					state = parser_temp_realloc(state,
1729 					    maxnest * sizeof(*state));
1730 			}
1731 			level++;
1732 			state[level].parenlevel = 0;
1733 			if (subtype == VSMINUS || subtype == VSPLUS ||
1734 			    subtype == VSQUESTION || subtype == VSASSIGN) {
1735 				/*
1736 				 * For operators that were in the Bourne shell,
1737 				 * inherit the double-quote state.
1738 				 */
1739 				state[level].syntax = state[level - 1].syntax;
1740 				state[level].category = TSTATE_VAR_OLD;
1741 			} else {
1742 				/*
1743 				 * The other operators take a pattern,
1744 				 * so go to BASESYNTAX.
1745 				 * Also, ' and " are now special, even
1746 				 * in here documents.
1747 				 */
1748 				state[level].syntax = BASESYNTAX;
1749 				state[level].category = TSTATE_VAR_NEW;
1750 				newvarnest++;
1751 			}
1752 		}
1753 	} else if (c == '\'' && state[level].syntax == BASESYNTAX) {
1754 		/* $'cstylequotes' */
1755 		USTPUTC(CTLQUOTEMARK, out);
1756 		state[level].syntax = SQSYNTAX;
1757 		sqiscstyle = 1;
1758 	} else {
1759 		USTPUTC('$', out);
1760 		pungetc();
1761 	}
1762 	goto parsesub_return;
1763 }
1764 
1765 
1766 /*
1767  * Parse an arithmetic expansion (indicate start of one and set state)
1768  */
1769 parsearith: {
1770 
1771 	if (level + 1 >= maxnest) {
1772 		maxnest *= 2;
1773 		if (state == state_static) {
1774 			state = parser_temp_alloc(
1775 			    maxnest * sizeof(*state));
1776 			memcpy(state, state_static,
1777 			    MAXNEST_static * sizeof(*state));
1778 		} else
1779 			state = parser_temp_realloc(state,
1780 			    maxnest * sizeof(*state));
1781 	}
1782 	level++;
1783 	state[level].syntax = ARISYNTAX;
1784 	state[level].parenlevel = 0;
1785 	state[level].category = TSTATE_ARITH;
1786 	USTPUTC(CTLARI, out);
1787 	if (state[level - 1].syntax == DQSYNTAX)
1788 		USTPUTC('"',out);
1789 	else
1790 		USTPUTC(' ',out);
1791 	goto parsearith_return;
1792 }
1793 
1794 } /* end of readtoken */
1795 
1796 
1797 /*
1798  * Returns true if the text contains nothing to expand (no dollar signs
1799  * or backquotes).
1800  */
1801 
1802 static int
1803 noexpand(char *text)
1804 {
1805 	char *p;
1806 	char c;
1807 
1808 	p = text;
1809 	while ((c = *p++) != '\0') {
1810 		if ( c == CTLQUOTEMARK)
1811 			continue;
1812 		if (c == CTLESC)
1813 			p++;
1814 		else if (BASESYNTAX[(int)c] == CCTL)
1815 			return 0;
1816 	}
1817 	return 1;
1818 }
1819 
1820 
1821 /*
1822  * Return true if the argument is a legal variable name (a letter or
1823  * underscore followed by zero or more letters, underscores, and digits).
1824  */
1825 
1826 int
1827 goodname(const char *name)
1828 {
1829 	const char *p;
1830 
1831 	p = name;
1832 	if (! is_name(*p))
1833 		return 0;
1834 	while (*++p) {
1835 		if (! is_in_name(*p))
1836 			return 0;
1837 	}
1838 	return 1;
1839 }
1840 
1841 
1842 int
1843 isassignment(const char *p)
1844 {
1845 	if (!is_name(*p))
1846 		return 0;
1847 	p++;
1848 	for (;;) {
1849 		if (*p == '=')
1850 			return 1;
1851 		else if (!is_in_name(*p))
1852 			return 0;
1853 		p++;
1854 	}
1855 }
1856 
1857 
1858 static void
1859 consumetoken(int token)
1860 {
1861 	if (readtoken() != token)
1862 		synexpect(token);
1863 }
1864 
1865 
1866 /*
1867  * Called when an unexpected token is read during the parse.  The argument
1868  * is the token that is expected, or -1 if more than one type of token can
1869  * occur at this point.
1870  */
1871 
1872 static void
1873 synexpect(int token)
1874 {
1875 	char msg[64];
1876 
1877 	if (token >= 0) {
1878 		fmtstr(msg, 64, "%s unexpected (expecting %s)",
1879 			tokname[lasttoken], tokname[token]);
1880 	} else {
1881 		fmtstr(msg, 64, "%s unexpected", tokname[lasttoken]);
1882 	}
1883 	synerror(msg);
1884 }
1885 
1886 
1887 static void
1888 synerror(const char *msg)
1889 {
1890 	if (commandname)
1891 		outfmt(out2, "%s: %d: ", commandname, startlinno);
1892 	outfmt(out2, "Syntax error: %s\n", msg);
1893 	error((char *)NULL);
1894 }
1895 
1896 static void
1897 setprompt(int which)
1898 {
1899 	whichprompt = which;
1900 
1901 #ifndef NO_HISTORY
1902 	if (!el)
1903 #endif
1904 	{
1905 		out2str(getprompt(NULL));
1906 		flushout(out2);
1907 	}
1908 }
1909 
1910 /*
1911  * called by editline -- any expansions to the prompt
1912  *    should be added here.
1913  */
1914 char *
1915 getprompt(void *unused __unused)
1916 {
1917 	static char ps[PROMPTLEN];
1918 	char *fmt;
1919 	const char *pwd;
1920 	int i, trim;
1921 	static char internal_error[] = "??";
1922 
1923 	/*
1924 	 * Select prompt format.
1925 	 */
1926 	switch (whichprompt) {
1927 	case 0:
1928 		fmt = nullstr;
1929 		break;
1930 	case 1:
1931 		fmt = ps1val();
1932 		break;
1933 	case 2:
1934 		fmt = ps2val();
1935 		break;
1936 	default:
1937 		return internal_error;
1938 	}
1939 
1940 	/*
1941 	 * Format prompt string.
1942 	 */
1943 	for (i = 0; (i < 127) && (*fmt != '\0'); i++, fmt++)
1944 		if (*fmt == '\\')
1945 			switch (*++fmt) {
1946 
1947 				/*
1948 				 * Hostname.
1949 				 *
1950 				 * \h specifies just the local hostname,
1951 				 * \H specifies fully-qualified hostname.
1952 				 */
1953 			case 'h':
1954 			case 'H':
1955 				ps[i] = '\0';
1956 				gethostname(&ps[i], PROMPTLEN - i);
1957 				/* Skip to end of hostname. */
1958 				trim = (*fmt == 'h') ? '.' : '\0';
1959 				while ((ps[i+1] != '\0') && (ps[i+1] != trim))
1960 					i++;
1961 				break;
1962 
1963 				/*
1964 				 * Working directory.
1965 				 *
1966 				 * \W specifies just the final component,
1967 				 * \w specifies the entire path.
1968 				 */
1969 			case 'W':
1970 			case 'w':
1971 				pwd = lookupvar("PWD");
1972 				if (pwd == NULL)
1973 					pwd = "?";
1974 				if (*fmt == 'W' &&
1975 				    *pwd == '/' && pwd[1] != '\0')
1976 					strlcpy(&ps[i], strrchr(pwd, '/') + 1,
1977 					    PROMPTLEN - i);
1978 				else
1979 					strlcpy(&ps[i], pwd, PROMPTLEN - i);
1980 				/* Skip to end of path. */
1981 				while (ps[i + 1] != '\0')
1982 					i++;
1983 				break;
1984 
1985 				/*
1986 				 * Superuser status.
1987 				 *
1988 				 * '$' for normal users, '#' for root.
1989 				 */
1990 			case '$':
1991 				ps[i] = (geteuid() != 0) ? '$' : '#';
1992 				break;
1993 
1994 				/*
1995 				 * A literal \.
1996 				 */
1997 			case '\\':
1998 				ps[i] = '\\';
1999 				break;
2000 
2001 				/*
2002 				 * Emit unrecognized formats verbatim.
2003 				 */
2004 			default:
2005 				ps[i++] = '\\';
2006 				ps[i] = *fmt;
2007 				break;
2008 			}
2009 		else
2010 			ps[i] = *fmt;
2011 	ps[i] = '\0';
2012 	return (ps);
2013 }
2014 
2015 
2016 const char *
2017 expandstr(const char *ps)
2018 {
2019 	union node n;
2020 	struct jmploc jmploc;
2021 	struct jmploc *const savehandler = handler;
2022 	const int saveprompt = doprompt;
2023 	struct parsefile *const savetopfile = getcurrentfile();
2024 	struct parser_temp *const saveparser_temp = parser_temp;
2025 	const char *result = NULL;
2026 
2027 	if (!setjmp(jmploc.loc)) {
2028 		handler = &jmploc;
2029 		parser_temp = NULL;
2030 		setinputstring(ps, 1);
2031 		doprompt = 0;
2032 		readtoken1(pgetc(), DQSYNTAX, "\n\n", 0);
2033 		if (backquotelist != NULL)
2034 			error("Command substitution not allowed here");
2035 
2036 		n.narg.type = NARG;
2037 		n.narg.next = NULL;
2038 		n.narg.text = wordtext;
2039 		n.narg.backquote = backquotelist;
2040 
2041 		expandarg(&n, NULL, 0);
2042 		result = stackblock();
2043 		INTOFF;
2044 	}
2045 	handler = savehandler;
2046 	doprompt = saveprompt;
2047 	popfilesupto(savetopfile);
2048 	if (parser_temp != saveparser_temp) {
2049 		parser_temp_free_all();
2050 		parser_temp = saveparser_temp;
2051 	}
2052 	if (result != NULL) {
2053 		INTON;
2054 	} else if (exception == EXINT)
2055 		raise(SIGINT);
2056 	return result;
2057 }
2058