xref: /openbsd/bin/ksh/syn.c (revision 133306f0)
1 /*	$OpenBSD: syn.c,v 1.12 1999/06/15 01:18:36 millert Exp $	*/
2 
3 /*
4  * shell parser (C version)
5  */
6 
7 #include "sh.h"
8 #include "c_test.h"
9 
10 struct nesting_state {
11 	int	start_token;	/* token than began nesting (eg, FOR) */
12 	int	start_line;	/* line nesting began on */
13 };
14 
15 static void	yyparse		ARGS((void));
16 static struct op *pipeline	ARGS((int cf));
17 static struct op *andor		ARGS((void));
18 static struct op *c_list	ARGS((int multi));
19 static struct ioword *synio	ARGS((int cf));
20 static void	musthave	ARGS((int c, int cf));
21 static struct op *nested	ARGS((int type, int smark, int emark));
22 static struct op *get_command	ARGS((int cf));
23 static struct op *dogroup	ARGS((void));
24 static struct op *thenpart	ARGS((void));
25 static struct op *elsepart	ARGS((void));
26 static struct op *caselist	ARGS((void));
27 static struct op *casepart	ARGS((int endtok));
28 static struct op *function_body	ARGS((char *name, int ksh_func));
29 static char **	wordlist	ARGS((void));
30 static struct op *block		ARGS((int type, struct op *t1, struct op *t2,
31 				      char **wp));
32 static struct op *newtp		ARGS((int type));
33 static void	syntaxerr	ARGS((const char *what))
34 						GCC_FUNC_ATTR(noreturn);
35 static void	nesting_push ARGS((struct nesting_state *save, int tok));
36 static void	nesting_pop ARGS((struct nesting_state *saved));
37 static int	assign_command ARGS((char *s));
38 static int	inalias ARGS((struct source *s));
39 #ifdef KSH
40 static int	dbtestp_isa ARGS((Test_env *te, Test_meta meta));
41 static const char *dbtestp_getopnd ARGS((Test_env *te, Test_op op,
42 					int do_eval));
43 static int	dbtestp_eval ARGS((Test_env *te, Test_op op, const char *opnd1,
44 				const char *opnd2, int do_eval));
45 static void	dbtestp_error ARGS((Test_env *te, int offset, const char *msg));
46 #endif /* KSH */
47 
48 static	struct	op	*outtree; /* yyparse output */
49 
50 static struct nesting_state nesting;	/* \n changed to ; */
51 
52 static	int	reject;		/* token(cf) gets symbol again */
53 static	int	symbol;		/* yylex value */
54 
55 #define	REJECT	(reject = 1)
56 #define	ACCEPT	(reject = 0)
57 #define	token(cf) \
58 	((reject) ? (ACCEPT, symbol) : (symbol = yylex(cf)))
59 #define	tpeek(cf) \
60 	((reject) ? (symbol) : (REJECT, symbol = yylex(cf)))
61 
62 static void
63 yyparse()
64 {
65 	int c;
66 
67 	ACCEPT;
68 
69 	outtree = c_list(source->type == SSTRING);
70 	c = tpeek(0);
71 	if (c == 0 && !outtree)
72 		outtree = newtp(TEOF);
73 	else if (c != '\n' && c != 0)
74 		syntaxerr((char *) 0);
75 }
76 
77 static struct op *
78 pipeline(cf)
79 	int cf;
80 {
81 	register struct op *t, *p, *tl = NULL;
82 
83 	t = get_command(cf);
84 	if (t != NULL) {
85 		while (token(0) == '|') {
86 			if ((p = get_command(CONTIN)) == NULL)
87 				syntaxerr((char *) 0);
88 			if (tl == NULL)
89 				t = tl = block(TPIPE, t, p, NOWORDS);
90 			else
91 				tl = tl->right = block(TPIPE, tl->right, p, NOWORDS);
92 		}
93 		REJECT;
94 	}
95 	return (t);
96 }
97 
98 static struct op *
99 andor()
100 {
101 	register struct op *t, *p;
102 	register int c;
103 
104 	t = pipeline(0);
105 	if (t != NULL) {
106 		while ((c = token(0)) == LOGAND || c == LOGOR) {
107 			if ((p = pipeline(CONTIN)) == NULL)
108 				syntaxerr((char *) 0);
109 			t = block(c == LOGAND? TAND: TOR, t, p, NOWORDS);
110 		}
111 		REJECT;
112 	}
113 	return (t);
114 }
115 
116 static struct op *
117 c_list(multi)
118 	int multi;
119 {
120 	register struct op *t = NULL, *p, *tl = NULL;
121 	register int c;
122 	int have_sep;
123 
124 	while (1) {
125 		p = andor();
126 		/* Token has always been read/rejected at this point, so
127 		 * we don't worry about what flags to pass token()
128 		 */
129 		c = token(0);
130 		have_sep = 1;
131 		if (c == '\n' && (multi || inalias(source))) {
132 			if (!p) /* ignore blank lines */
133 				continue;
134 		} else if (!p)
135 			break;
136 		else if (c == '&' || c == COPROC)
137 			p = block(c == '&' ? TASYNC : TCOPROC,
138 				  p, NOBLOCK, NOWORDS);
139 		else if (c != ';')
140 			have_sep = 0;
141 		if (!t)
142 			t = p;
143 		else if (!tl)
144 			t = tl = block(TLIST, t, p, NOWORDS);
145 		else
146 			tl = tl->right = block(TLIST, tl->right, p, NOWORDS);
147 		if (!have_sep)
148 			break;
149 	}
150 	REJECT;
151 	return t;
152 }
153 
154 static struct ioword *
155 synio(cf)
156 	int cf;
157 {
158 	register struct ioword *iop;
159 	int ishere;
160 
161 	if (tpeek(cf) != REDIR)
162 		return NULL;
163 	ACCEPT;
164 	iop = yylval.iop;
165 	ishere = (iop->flag&IOTYPE) == IOHERE;
166 	musthave(LWORD, ishere ? HEREDELIM : 0);
167 	if (ishere) {
168 		iop->delim = yylval.cp;
169 		if (*ident != 0) /* unquoted */
170 			iop->flag |= IOEVAL;
171 		if (herep >= &heres[HERES])
172 			yyerror("too many <<'s\n");
173 		*herep++ = iop;
174 	} else
175 		iop->name = yylval.cp;
176 	return iop;
177 }
178 
179 static void
180 musthave(c, cf)
181 	int c, cf;
182 {
183 	if ((token(cf)) != c)
184 		syntaxerr((char *) 0);
185 }
186 
187 static struct op *
188 nested(type, smark, emark)
189 	int type, smark, emark;
190 {
191 	register struct op *t;
192 	struct nesting_state old_nesting;
193 
194 	nesting_push(&old_nesting, smark);
195 	t = c_list(TRUE);
196 	musthave(emark, KEYWORD|ALIAS);
197 	nesting_pop(&old_nesting);
198 	return (block(type, t, NOBLOCK, NOWORDS));
199 }
200 
201 static struct op *
202 get_command(cf)
203 	int cf;
204 {
205 	register struct op *t;
206 	register int c, iopn = 0, syniocf;
207 	struct ioword *iop, **iops;
208 	XPtrV args, vars;
209 	struct nesting_state old_nesting;
210 
211 	iops = (struct ioword **) alloc(sizeofN(struct ioword *, NUFILE+1),
212 					ATEMP);
213 	XPinit(args, 16);
214 	XPinit(vars, 16);
215 
216 	syniocf = KEYWORD|ALIAS;
217 	switch (c = token(cf|KEYWORD|ALIAS|VARASN)) {
218 	  default:
219 		REJECT;
220 		afree((void*) iops, ATEMP);
221 		XPfree(args);
222 		XPfree(vars);
223 		return NULL; /* empty line */
224 
225 	  case LWORD:
226 	  case REDIR:
227 		REJECT;
228 		syniocf &= ~(KEYWORD|ALIAS);
229 		t = newtp(TCOM);
230 		t->lineno = source->line;
231 		while (1) {
232 			cf = (t->u.evalflags ? ARRAYVAR : 0)
233 			     | (XPsize(args) == 0 ? ALIAS|VARASN : CMDWORD);
234 			switch (tpeek(cf)) {
235 			  case REDIR:
236 				if (iopn >= NUFILE)
237 					yyerror("too many redirections\n");
238 				iops[iopn++] = synio(cf);
239 				break;
240 
241 			  case LWORD:
242 				ACCEPT;
243 				/* the iopn == 0 and XPsize(vars) == 0 are
244 				 * dubious but at&t ksh acts this way
245 				 */
246 				if (iopn == 0 && XPsize(vars) == 0
247 				    && XPsize(args) == 0
248 				    && assign_command(ident))
249 					t->u.evalflags = DOVACHECK;
250 				if ((XPsize(args) == 0 || Flag(FKEYWORD))
251 				    && is_wdvarassign(yylval.cp))
252 					XPput(vars, yylval.cp);
253 				else
254 					XPput(args, yylval.cp);
255 				break;
256 
257 			  case '(':
258 				/* Check for "> foo (echo hi)", which at&t ksh
259 				 * allows (not POSIX, but not disallowed)
260 				 */
261 				afree(t, ATEMP);
262 				if (XPsize(args) == 0 && XPsize(vars) == 0) {
263 					ACCEPT;
264 					goto Subshell;
265 				}
266 				/* Must be a function */
267 				if (iopn != 0 || XPsize(args) != 1
268 				    || XPsize(vars) != 0)
269 					syntaxerr((char *) 0);
270 				ACCEPT;
271 				/*(*/
272 				musthave(')', 0);
273 				t = function_body(XPptrv(args)[0], FALSE);
274 				goto Leave;
275 
276 			  default:
277 				goto Leave;
278 			}
279 		}
280 	  Leave:
281 		break;
282 
283 	  Subshell:
284 	  case '(':
285 		t = nested(TPAREN, '(', ')');
286 		break;
287 
288 	  case '{': /*}*/
289 		t = nested(TBRACE, '{', '}');
290 		break;
291 
292 #ifdef KSH
293 	  case MDPAREN:
294 	  {
295 		static const char let_cmd[] = { CHAR, 'l', CHAR, 'e',
296 						CHAR, 't', EOS };
297 		/* Leave KEYWORD in syniocf (allow if (( 1 )) then ...) */
298 		t = newtp(TCOM);
299 		t->lineno = source->line;
300 		ACCEPT;
301 		XPput(args, wdcopy(let_cmd, ATEMP));
302 		musthave(LWORD,LETEXPR);
303 		XPput(args, yylval.cp);
304 		break;
305 	  }
306 #endif /* KSH */
307 
308 #ifdef KSH
309 	  case DBRACKET: /* [[ .. ]] */
310 		/* Leave KEYWORD in syniocf (allow if [[ -n 1 ]] then ...) */
311 		t = newtp(TDBRACKET);
312 		ACCEPT;
313 		{
314 			Test_env te;
315 
316 			te.flags = TEF_DBRACKET;
317 			te.pos.av = &args;
318 			te.isa = dbtestp_isa;
319 			te.getopnd = dbtestp_getopnd;
320 			te.eval = dbtestp_eval;
321 			te.error = dbtestp_error;
322 
323 			test_parse(&te);
324 		}
325 		break;
326 #endif /* KSH */
327 
328 	  case FOR:
329 	  case SELECT:
330 		t = newtp((c == FOR) ? TFOR : TSELECT);
331 		musthave(LWORD, ARRAYVAR);
332 		if (!is_wdvarname(yylval.cp, TRUE))
333 			yyerror("%s: bad identifier\n",
334 				c == FOR ? "for" : "select");
335 		t->str = str_save(ident, ATEMP);
336 		nesting_push(&old_nesting, c);
337 		t->vars = wordlist();
338 		t->left = dogroup();
339 		nesting_pop(&old_nesting);
340 		break;
341 
342 	  case WHILE:
343 	  case UNTIL:
344 		nesting_push(&old_nesting, c);
345 		t = newtp((c == WHILE) ? TWHILE : TUNTIL);
346 		t->left = c_list(TRUE);
347 		t->right = dogroup();
348 		nesting_pop(&old_nesting);
349 		break;
350 
351 	  case CASE:
352 		t = newtp(TCASE);
353 		musthave(LWORD, 0);
354 		t->str = yylval.cp;
355 		nesting_push(&old_nesting, c);
356 		t->left = caselist();
357 		nesting_pop(&old_nesting);
358 		break;
359 
360 	  case IF:
361 		nesting_push(&old_nesting, c);
362 		t = newtp(TIF);
363 		t->left = c_list(TRUE);
364 		t->right = thenpart();
365 		musthave(FI, KEYWORD|ALIAS);
366 		nesting_pop(&old_nesting);
367 		break;
368 
369 	  case BANG:
370 		syniocf &= ~(KEYWORD|ALIAS);
371 		t = pipeline(0);
372 		if (t == (struct op *) 0)
373 			syntaxerr((char *) 0);
374 		t = block(TBANG, NOBLOCK, t, NOWORDS);
375 		break;
376 
377 	  case TIME:
378 		syniocf &= ~(KEYWORD|ALIAS);
379 		t = pipeline(0);
380 		t = block(TTIME, t, NOBLOCK, NOWORDS);
381 		break;
382 
383 	  case FUNCTION:
384 		musthave(LWORD, 0);
385 		t = function_body(yylval.cp, TRUE);
386 		break;
387 	}
388 
389 	while ((iop = synio(syniocf)) != NULL) {
390 		if (iopn >= NUFILE)
391 			yyerror("too many redirections\n");
392 		iops[iopn++] = iop;
393 	}
394 
395 	if (iopn == 0) {
396 		afree((void*) iops, ATEMP);
397 		t->ioact = NULL;
398 	} else {
399 		iops[iopn++] = NULL;
400 		iops = (struct ioword **) aresize((void*) iops,
401 					sizeofN(struct ioword *, iopn), ATEMP);
402 		t->ioact = iops;
403 	}
404 
405 	if (t->type == TCOM || t->type == TDBRACKET) {
406 		XPput(args, NULL);
407 		t->args = (char **) XPclose(args);
408 		XPput(vars, NULL);
409 		t->vars = (char **) XPclose(vars);
410 	} else {
411 		XPfree(args);
412 		XPfree(vars);
413 	}
414 
415 	return t;
416 }
417 
418 static struct op *
419 dogroup()
420 {
421 	register int c;
422 	register struct op *list;
423 
424 	c = token(CONTIN|KEYWORD|ALIAS);
425 	/* A {...} can be used instead of do...done for for/select loops
426 	 * but not for while/until loops - we don't need to check if it
427 	 * is a while loop because it would have been parsed as part of
428 	 * the conditional command list...
429 	 */
430 	if (c == DO)
431 		c = DONE;
432 	else if (c == '{')
433 		c = '}';
434 	else
435 		syntaxerr((char *) 0);
436 	list = c_list(TRUE);
437 	musthave(c, KEYWORD|ALIAS);
438 	return list;
439 }
440 
441 static struct op *
442 thenpart()
443 {
444 	register struct op *t;
445 
446 	musthave(THEN, KEYWORD|ALIAS);
447 	t = newtp(0);
448 	t->left = c_list(TRUE);
449 	if (t->left == NULL)
450 		syntaxerr((char *) 0);
451 	t->right = elsepart();
452 	return (t);
453 }
454 
455 static struct op *
456 elsepart()
457 {
458 	register struct op *t;
459 
460 	switch (token(KEYWORD|ALIAS|VARASN)) {
461 	  case ELSE:
462 		if ((t = c_list(TRUE)) == NULL)
463 			syntaxerr((char *) 0);
464 		return (t);
465 
466 	  case ELIF:
467 		t = newtp(TELIF);
468 		t->left = c_list(TRUE);
469 		t->right = thenpart();
470 		return (t);
471 
472 	  default:
473 		REJECT;
474 	}
475 	return NULL;
476 }
477 
478 static struct op *
479 caselist()
480 {
481 	register struct op *t, *tl;
482 	int c;
483 
484 	c = token(CONTIN|KEYWORD|ALIAS);
485 	/* A {...} can be used instead of in...esac for case statements */
486 	if (c == IN)
487 		c = ESAC;
488 	else if (c == '{')
489 		c = '}';
490 	else
491 		syntaxerr((char *) 0);
492 	t = tl = NULL;
493 	while ((tpeek(CONTIN|KEYWORD|ESACONLY)) != c) { /* no ALIAS here */
494 		struct op *tc = casepart(c);
495 		if (tl == NULL)
496 			t = tl = tc, tl->right = NULL;
497 		else
498 			tl->right = tc, tl = tc;
499 	}
500 	musthave(c, KEYWORD|ALIAS);
501 	return (t);
502 }
503 
504 static struct op *
505 casepart(endtok)
506 	int endtok;
507 {
508 	register struct op *t;
509 	register int c;
510 	XPtrV ptns;
511 
512 	XPinit(ptns, 16);
513 	t = newtp(TPAT);
514 	c = token(CONTIN|KEYWORD); /* no ALIAS here */
515 	if (c != '(')
516 		REJECT;
517 	do {
518 		musthave(LWORD, 0);
519 		XPput(ptns, yylval.cp);
520 	} while ((c = token(0)) == '|');
521 	REJECT;
522 	XPput(ptns, NULL);
523 	t->vars = (char **) XPclose(ptns);
524 	musthave(')', 0);
525 
526 	t->left = c_list(TRUE);
527 	/* Note: Posix requires the ;; */
528 	if ((tpeek(CONTIN|KEYWORD|ALIAS)) != endtok)
529 		musthave(BREAK, CONTIN|KEYWORD|ALIAS);
530 	return (t);
531 }
532 
533 static struct op *
534 function_body(name, ksh_func)
535 	char *name;
536 	int ksh_func;	/* function foo { ... } vs foo() { .. } */
537 {
538 	char *sname, *p;
539 	struct op *t;
540 	int old_func_parse;
541 
542 	sname = wdstrip(name);
543 	/* Check for valid characters in name.  posix and ksh93 say only
544 	 * allow [a-zA-Z_0-9] but this allows more as old pdksh's have
545 	 * allowed more (the following were never allowed:
546 	 *	nul space nl tab $ ' " \ ` ( ) & | ; = < >
547 	 *  C_QUOTE covers all but = and adds # [ ? *)
548 	 */
549 	for (p = sname; *p; p++)
550 		if (ctype(*p, C_QUOTE) || *p == '=')
551 			yyerror("%s: invalid function name\n", sname);
552 
553 	t = newtp(TFUNCT);
554 	t->str = sname;
555 	t->u.ksh_func = ksh_func;
556 	t->lineno = source->line;
557 
558 	/* Note that POSIX allows only compound statements after foo(), sh and
559 	 * at&t ksh allow any command, go with the later since it shouldn't
560 	 * break anything.  However, for function foo, at&t ksh only accepts
561 	 * an open-brace.
562 	 */
563 	if (ksh_func) {
564 		musthave('{', CONTIN|KEYWORD|ALIAS); /* } */
565 		REJECT;
566 	}
567 
568 	old_func_parse = e->flags & EF_FUNC_PARSE;
569 	e->flags |= EF_FUNC_PARSE;
570 	if ((t->left = get_command(CONTIN)) == (struct op *) 0) {
571 		/*
572 		 * Probably something like foo() followed by eof or ;.
573 		 * This is accepted by sh and ksh88.
574 		 * To make "typset -f foo" work reliably (so its output can
575 		 * be used as input), we pretend there is a colon here.
576 		 */
577 		t->left = newtp(TCOM);
578 		t->left->args = (char **) alloc(sizeof(char *) * 2, ATEMP);
579 		t->left->args[0] = alloc(sizeof(char) * 3, ATEMP);
580 		t->left->args[0][0] = CHAR;
581 		t->left->args[0][1] = ':';
582 		t->left->args[0][2] = EOS;
583 		t->left->args[1] = (char *) 0;
584 		t->left->vars = (char **) alloc(sizeof(char *), ATEMP);
585 		t->left->vars[0] = (char *) 0;
586 		t->left->lineno = 1;
587 	}
588 	if (!old_func_parse)
589 		e->flags &= ~EF_FUNC_PARSE;
590 
591 	return t;
592 }
593 
594 static char **
595 wordlist()
596 {
597 	register int c;
598 	XPtrV args;
599 
600 	XPinit(args, 16);
601 	/* Posix does not do alias expansion here... */
602 	if ((c = token(CONTIN|KEYWORD|ALIAS)) != IN) {
603 		if (c != ';') /* non-POSIX, but at&t ksh accepts a ; here */
604 			REJECT;
605 		return NULL;
606 	}
607 	while ((c = token(0)) == LWORD)
608 		XPput(args, yylval.cp);
609 	if (c != '\n' && c != ';')
610 		syntaxerr((char *) 0);
611 	if (XPsize(args) == 0) {
612 		XPfree(args);
613 		return NULL;
614 	} else {
615 		XPput(args, NULL);
616 		return (char **) XPclose(args);
617 	}
618 }
619 
620 /*
621  * supporting functions
622  */
623 
624 static struct op *
625 block(type, t1, t2, wp)
626 	int type;
627 	struct op *t1, *t2;
628 	char **wp;
629 {
630 	register struct op *t;
631 
632 	t = newtp(type);
633 	t->left = t1;
634 	t->right = t2;
635 	t->vars = wp;
636 	return (t);
637 }
638 
639 const	struct tokeninfo {
640 	const char *name;
641 	short	val;
642 	short	reserved;
643 } tokentab[] = {
644 	/* Reserved words */
645 	{ "if",		IF,	TRUE },
646 	{ "then",	THEN,	TRUE },
647 	{ "else",	ELSE,	TRUE },
648 	{ "elif",	ELIF,	TRUE },
649 	{ "fi",		FI,	TRUE },
650 	{ "case",	CASE,	TRUE },
651 	{ "esac",	ESAC,	TRUE },
652 	{ "for",	FOR,	TRUE },
653 #ifdef KSH
654 	{ "select",	SELECT,	TRUE },
655 #endif /* KSH */
656 	{ "while",	WHILE,	TRUE },
657 	{ "until",	UNTIL,	TRUE },
658 	{ "do",		DO,	TRUE },
659 	{ "done",	DONE,	TRUE },
660 	{ "in",		IN,	TRUE },
661 	{ "function",	FUNCTION, TRUE },
662 	{ "time",	TIME,	TRUE },
663 	{ "{",		'{',	TRUE },
664 	{ "}",		'}',	TRUE },
665 	{ "!",		BANG,	TRUE },
666 #ifdef KSH
667 	{ "[[",		DBRACKET, TRUE },
668 #endif /* KSH */
669 	/* Lexical tokens (0[EOF], LWORD and REDIR handled specially) */
670 	{ "&&",		LOGAND,	FALSE },
671 	{ "||",		LOGOR,	FALSE },
672 	{ ";;",		BREAK,	FALSE },
673 #ifdef KSH
674 	{ "((",		MDPAREN, FALSE },
675 	{ "|&",		COPROC,	FALSE },
676 #endif /* KSH */
677 	/* and some special cases... */
678 	{ "newline",	'\n',	FALSE },
679 	{ 0 }
680 };
681 
682 void
683 initkeywords()
684 {
685 	register struct tokeninfo const *tt;
686 	register struct tbl *p;
687 
688 	tinit(&keywords, APERM, 32); /* must be 2^n (currently 20 keywords) */
689 	for (tt = tokentab; tt->name; tt++) {
690 		if (tt->reserved) {
691 			p = tenter(&keywords, tt->name, hash(tt->name));
692 			p->flag |= DEFINED|ISSET;
693 			p->type = CKEYWD;
694 			p->val.i = tt->val;
695 		}
696 	}
697 }
698 
699 static void
700 syntaxerr(what)
701 	const char *what;
702 {
703 	char redir[6];	/* 2<<- is the longest redirection, I think */
704 	const char *s;
705 	struct tokeninfo const *tt;
706 	int c;
707 
708 	if (!what)
709 		what = "unexpected";
710 	REJECT;
711 	c = token(0);
712     Again:
713 	switch (c) {
714 	case 0:
715 		if (nesting.start_token) {
716 			c = nesting.start_token;
717 			source->errline = nesting.start_line;
718 			what = "unmatched";
719 			goto Again;
720 		}
721 		/* don't quote the EOF */
722 		yyerror("syntax error: unexpected EOF\n");
723 		/*NOTREACHED*/
724 
725 	case LWORD:
726 		s = snptreef((char *) 0, 32, "%S", yylval.cp);
727 		break;
728 
729 	case REDIR:
730 		s = snptreef(redir, sizeof(redir), "%R", yylval.iop);
731 		break;
732 
733 	default:
734 		for (tt = tokentab; tt->name; tt++)
735 			if (tt->val == c)
736 			    break;
737 		if (tt->name)
738 			s = tt->name;
739 		else {
740 			if (c > 0 && c < 256) {
741 				redir[0] = c;
742 				redir[1] = '\0';
743 			} else
744 				shf_snprintf(redir, sizeof(redir),
745 					"?%d", c);
746 			s = redir;
747 		}
748 	}
749 	yyerror("syntax error: `%s' %s\n", s, what);
750 }
751 
752 static void
753 nesting_push(save, tok)
754 	struct nesting_state *save;
755 	int tok;
756 {
757 	*save = nesting;
758 	nesting.start_token = tok;
759 	nesting.start_line = source->line;
760 }
761 
762 static void
763 nesting_pop(saved)
764 	struct nesting_state *saved;
765 {
766 	nesting = *saved;
767 }
768 
769 static struct op *
770 newtp(type)
771 	int type;
772 {
773 	register struct op *t;
774 
775 	t = (struct op *) alloc(sizeof(*t), ATEMP);
776 	t->type = type;
777 	t->u.evalflags = 0;
778 	t->args = t->vars = NULL;
779 	t->ioact = NULL;
780 	t->left = t->right = NULL;
781 	t->str = NULL;
782 	return (t);
783 }
784 
785 struct op *
786 compile(s)
787 	Source *s;
788 {
789 	nesting.start_token = 0;
790 	nesting.start_line = 0;
791 	herep = heres;
792 	source = s;
793 	yyparse();
794 	return outtree;
795 }
796 
797 /* This kludge exists to take care of sh/at&t ksh oddity in which
798  * the arguments of alias/export/readonly/typeset have no field
799  * splitting, file globbing, or (normal) tilde expansion done.
800  * at&t ksh seems to do something similar to this since
801  *	$ touch a=a; typeset a=[ab]; echo "$a"
802  *	a=[ab]
803  *	$ x=typeset; $x a=[ab]; echo "$a"
804  *	a=a
805  *	$
806  */
807 static int
808 assign_command(s)
809 	char *s;
810 {
811 	char c = *s;
812 
813 	if (Flag(FPOSIX) || !*s)
814 		return 0;
815 	return     (c == 'a' && strcmp(s, "alias") == 0)
816 		|| (c == 'e' && strcmp(s, "export") == 0)
817 		|| (c == 'r' && strcmp(s, "readonly") == 0)
818 		|| (c == 't' && strcmp(s, "typeset") == 0);
819 }
820 
821 /* Check if we are in the middle of reading an alias */
822 static int
823 inalias(s)
824 	struct source *s;
825 {
826 	for (; s && s->type == SALIAS; s = s->next)
827 		if (!(s->flags & SF_ALIASEND))
828 			return 1;
829 	return 0;
830 }
831 
832 
833 #ifdef KSH
834 /* Order important - indexed by Test_meta values
835  * Note that ||, &&, ( and ) can't appear in as unquoted strings
836  * in normal shell input, so these can be interpreted unambiguously
837  * in the evaluation pass.
838  */
839 static const char dbtest_or[] = { CHAR, '|', CHAR, '|', EOS };
840 static const char dbtest_and[] = { CHAR, '&', CHAR, '&', EOS };
841 static const char dbtest_not[] = { CHAR, '!', EOS };
842 static const char dbtest_oparen[] = { CHAR, '(', EOS };
843 static const char dbtest_cparen[] = { CHAR, ')', EOS };
844 const char *const dbtest_tokens[] = {
845 			dbtest_or, dbtest_and, dbtest_not,
846 			dbtest_oparen, dbtest_cparen
847 		};
848 const char db_close[] = { CHAR, ']', CHAR, ']', EOS };
849 const char db_lthan[] = { CHAR, '<', EOS };
850 const char db_gthan[] = { CHAR, '>', EOS };
851 
852 /* Test if the current token is a whatever.  Accepts the current token if
853  * it is.  Returns 0 if it is not, non-zero if it is (in the case of
854  * TM_UNOP and TM_BINOP, the returned value is a Test_op).
855  */
856 static int
857 dbtestp_isa(te, meta)
858 	Test_env *te;
859 	Test_meta meta;
860 {
861 	int c = tpeek(ARRAYVAR | (meta == TM_BINOP ? 0 : CONTIN));
862 	int uqword = 0;
863 	char *save = (char *) 0;
864 	int ret = 0;
865 
866 	/* unquoted word? */
867 	uqword = c == LWORD && *ident;
868 
869 	if (meta == TM_OR)
870 		ret = c == LOGOR;
871 	else if (meta == TM_AND)
872 		ret = c == LOGAND;
873 	else if (meta == TM_NOT)
874 		ret = uqword && strcmp(yylval.cp, dbtest_tokens[(int) TM_NOT]) == 0;
875 	else if (meta == TM_OPAREN)
876 		ret = c == '(' /*)*/;
877 	else if (meta == TM_CPAREN)
878 		ret = c == /*(*/ ')';
879 	else if (meta == TM_UNOP || meta == TM_BINOP) {
880 		if (meta == TM_BINOP && c == REDIR
881 		    && (yylval.iop->flag == IOREAD
882 			|| yylval.iop->flag == IOWRITE))
883 		{
884 			ret = 1;
885 			save = wdcopy(yylval.iop->flag == IOREAD ?
886 				db_lthan : db_gthan, ATEMP);
887 		} else if (uqword && (ret = (int) test_isop(te, meta, ident)))
888 			save = yylval.cp;
889 	} else /* meta == TM_END */
890 		ret = uqword && strcmp(yylval.cp, db_close) == 0;
891 	if (ret) {
892 		ACCEPT;
893 		if (meta != TM_END) {
894 			if (!save)
895 				save = wdcopy(dbtest_tokens[(int) meta], ATEMP);
896 			XPput(*te->pos.av, save);
897 		}
898 	}
899 	return ret;
900 }
901 
902 static const char *
903 dbtestp_getopnd(te, op, do_eval)
904 	Test_env *te;
905 	Test_op op;
906 	int do_eval;
907 {
908 	int c = tpeek(ARRAYVAR);
909 
910 	if (c != LWORD)
911 		return (const char *) 0;
912 
913 	ACCEPT;
914 	XPput(*te->pos.av, yylval.cp);
915 
916 	return null;
917 }
918 
919 static int
920 dbtestp_eval(te, op, opnd1, opnd2, do_eval)
921 	Test_env *te;
922 	Test_op op;
923 	const char *opnd1;
924 	const char *opnd2;
925 	int do_eval;
926 {
927 	return 1;
928 }
929 
930 static void
931 dbtestp_error(te, offset, msg)
932 	Test_env *te;
933 	int offset;
934 	const char *msg;
935 {
936 	te->flags |= TEF_ERROR;
937 
938 	if (offset < 0) {
939 		REJECT;
940 		/* Kludgy to say the least... */
941 		symbol = LWORD;
942 		yylval.cp = *(XPptrv(*te->pos.av) + XPsize(*te->pos.av)
943 				+ offset);
944 	}
945 	syntaxerr(msg);
946 }
947 #endif /* KSH */
948