xref: /freebsd/contrib/bmake/cond.c (revision 48c5129f93c5eb5419c87b08e4677d51513f1dc0)
1 /*	$NetBSD: cond.c,v 1.64 2012/06/12 19:21:50 joerg Exp $	*/
2 
3 /*
4  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Adam de Boor.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 /*
36  * Copyright (c) 1988, 1989 by Adam de Boor
37  * Copyright (c) 1989 by Berkeley Softworks
38  * All rights reserved.
39  *
40  * This code is derived from software contributed to Berkeley by
41  * Adam de Boor.
42  *
43  * Redistribution and use in source and binary forms, with or without
44  * modification, are permitted provided that the following conditions
45  * are met:
46  * 1. Redistributions of source code must retain the above copyright
47  *    notice, this list of conditions and the following disclaimer.
48  * 2. Redistributions in binary form must reproduce the above copyright
49  *    notice, this list of conditions and the following disclaimer in the
50  *    documentation and/or other materials provided with the distribution.
51  * 3. All advertising materials mentioning features or use of this software
52  *    must display the following acknowledgement:
53  *	This product includes software developed by the University of
54  *	California, Berkeley and its contributors.
55  * 4. Neither the name of the University nor the names of its contributors
56  *    may be used to endorse or promote products derived from this software
57  *    without specific prior written permission.
58  *
59  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
69  * SUCH DAMAGE.
70  */
71 
72 #ifndef MAKE_NATIVE
73 static char rcsid[] = "$NetBSD: cond.c,v 1.64 2012/06/12 19:21:50 joerg Exp $";
74 #else
75 #include <sys/cdefs.h>
76 #ifndef lint
77 #if 0
78 static char sccsid[] = "@(#)cond.c	8.2 (Berkeley) 1/2/94";
79 #else
80 __RCSID("$NetBSD: cond.c,v 1.64 2012/06/12 19:21:50 joerg Exp $");
81 #endif
82 #endif /* not lint */
83 #endif
84 
85 /*-
86  * cond.c --
87  *	Functions to handle conditionals in a makefile.
88  *
89  * Interface:
90  *	Cond_Eval 	Evaluate the conditional in the passed line.
91  *
92  */
93 
94 #include    <ctype.h>
95 #include    <errno.h>    /* For strtoul() error checking */
96 
97 #include    "make.h"
98 #include    "hash.h"
99 #include    "dir.h"
100 #include    "buf.h"
101 
102 /*
103  * The parsing of conditional expressions is based on this grammar:
104  *	E -> F || E
105  *	E -> F
106  *	F -> T && F
107  *	F -> T
108  *	T -> defined(variable)
109  *	T -> make(target)
110  *	T -> exists(file)
111  *	T -> empty(varspec)
112  *	T -> target(name)
113  *	T -> commands(name)
114  *	T -> symbol
115  *	T -> $(varspec) op value
116  *	T -> $(varspec) == "string"
117  *	T -> $(varspec) != "string"
118  *	T -> "string"
119  *	T -> ( E )
120  *	T -> ! T
121  *	op -> == | != | > | < | >= | <=
122  *
123  * 'symbol' is some other symbol to which the default function (condDefProc)
124  * is applied.
125  *
126  * Tokens are scanned from the 'condExpr' string. The scanner (CondToken)
127  * will return TOK_AND for '&' and '&&', TOK_OR for '|' and '||',
128  * TOK_NOT for '!', TOK_LPAREN for '(', TOK_RPAREN for ')' and will evaluate
129  * the other terminal symbols, using either the default function or the
130  * function given in the terminal, and return the result as either TOK_TRUE
131  * or TOK_FALSE.
132  *
133  * TOK_FALSE is 0 and TOK_TRUE 1 so we can directly assign C comparisons.
134  *
135  * All Non-Terminal functions (CondE, CondF and CondT) return TOK_ERROR on
136  * error.
137  */
138 typedef enum {
139     TOK_FALSE = 0, TOK_TRUE = 1, TOK_AND, TOK_OR, TOK_NOT,
140     TOK_LPAREN, TOK_RPAREN, TOK_EOF, TOK_NONE, TOK_ERROR
141 } Token;
142 
143 /*-
144  * Structures to handle elegantly the different forms of #if's. The
145  * last two fields are stored in condInvert and condDefProc, respectively.
146  */
147 static void CondPushBack(Token);
148 static int CondGetArg(char **, char **, const char *);
149 static Boolean CondDoDefined(int, const char *);
150 static int CondStrMatch(const void *, const void *);
151 static Boolean CondDoMake(int, const char *);
152 static Boolean CondDoExists(int, const char *);
153 static Boolean CondDoTarget(int, const char *);
154 static Boolean CondDoCommands(int, const char *);
155 static Boolean CondCvtArg(char *, double *);
156 static Token CondToken(Boolean);
157 static Token CondT(Boolean);
158 static Token CondF(Boolean);
159 static Token CondE(Boolean);
160 static int do_Cond_EvalExpression(Boolean *);
161 
162 static const struct If {
163     const char	*form;	      /* Form of if */
164     int		formlen;      /* Length of form */
165     Boolean	doNot;	      /* TRUE if default function should be negated */
166     Boolean	(*defProc)(int, const char *); /* Default function to apply */
167 } ifs[] = {
168     { "def",	  3,	  FALSE,  CondDoDefined },
169     { "ndef",	  4,	  TRUE,	  CondDoDefined },
170     { "make",	  4,	  FALSE,  CondDoMake },
171     { "nmake",	  5,	  TRUE,	  CondDoMake },
172     { "",	  0,	  FALSE,  CondDoDefined },
173     { NULL,	  0,	  FALSE,  NULL }
174 };
175 
176 static const struct If *if_info;        /* Info for current statement */
177 static char 	  *condExpr;	    	/* The expression to parse */
178 static Token	  condPushBack=TOK_NONE;	/* Single push-back token used in
179 					 * parsing */
180 
181 static unsigned int	cond_depth = 0;  	/* current .if nesting level */
182 static unsigned int	cond_min_depth = 0;  	/* depth at makefile open */
183 
184 static int
185 istoken(const char *str, const char *tok, size_t len)
186 {
187 	return strncmp(str, tok, len) == 0 && !isalpha((unsigned char)str[len]);
188 }
189 
190 /*-
191  *-----------------------------------------------------------------------
192  * CondPushBack --
193  *	Push back the most recent token read. We only need one level of
194  *	this, so the thing is just stored in 'condPushback'.
195  *
196  * Input:
197  *	t		Token to push back into the "stream"
198  *
199  * Results:
200  *	None.
201  *
202  * Side Effects:
203  *	condPushback is overwritten.
204  *
205  *-----------------------------------------------------------------------
206  */
207 static void
208 CondPushBack(Token t)
209 {
210     condPushBack = t;
211 }
212 
213 /*-
214  *-----------------------------------------------------------------------
215  * CondGetArg --
216  *	Find the argument of a built-in function.
217  *
218  * Input:
219  *	parens		TRUE if arg should be bounded by parens
220  *
221  * Results:
222  *	The length of the argument and the address of the argument.
223  *
224  * Side Effects:
225  *	The pointer is set to point to the closing parenthesis of the
226  *	function call.
227  *
228  *-----------------------------------------------------------------------
229  */
230 static int
231 CondGetArg(char **linePtr, char **argPtr, const char *func)
232 {
233     char	  *cp;
234     int	    	  argLen;
235     Buffer	  buf;
236     int           paren_depth;
237     char          ch;
238 
239     cp = *linePtr;
240     if (func != NULL)
241 	/* Skip opening '(' - verfied by caller */
242 	cp++;
243 
244     if (*cp == '\0') {
245 	/*
246 	 * No arguments whatsoever. Because 'make' and 'defined' aren't really
247 	 * "reserved words", we don't print a message. I think this is better
248 	 * than hitting the user with a warning message every time s/he uses
249 	 * the word 'make' or 'defined' at the beginning of a symbol...
250 	 */
251 	*argPtr = NULL;
252 	return (0);
253     }
254 
255     while (*cp == ' ' || *cp == '\t') {
256 	cp++;
257     }
258 
259     /*
260      * Create a buffer for the argument and start it out at 16 characters
261      * long. Why 16? Why not?
262      */
263     Buf_Init(&buf, 16);
264 
265     paren_depth = 0;
266     for (;;) {
267 	ch = *cp;
268 	if (ch == 0 || ch == ' ' || ch == '\t')
269 	    break;
270 	if ((ch == '&' || ch == '|') && paren_depth == 0)
271 	    break;
272 	if (*cp == '$') {
273 	    /*
274 	     * Parse the variable spec and install it as part of the argument
275 	     * if it's valid. We tell Var_Parse to complain on an undefined
276 	     * variable, so we don't do it too. Nor do we return an error,
277 	     * though perhaps we should...
278 	     */
279 	    char  	*cp2;
280 	    int		len;
281 	    void	*freeIt;
282 
283 	    cp2 = Var_Parse(cp, VAR_CMD, TRUE, &len, &freeIt);
284 	    Buf_AddBytes(&buf, strlen(cp2), cp2);
285 	    if (freeIt)
286 		free(freeIt);
287 	    cp += len;
288 	    continue;
289 	}
290 	if (ch == '(')
291 	    paren_depth++;
292 	else
293 	    if (ch == ')' && --paren_depth < 0)
294 		break;
295 	Buf_AddByte(&buf, *cp);
296 	cp++;
297     }
298 
299     *argPtr = Buf_GetAll(&buf, &argLen);
300     Buf_Destroy(&buf, FALSE);
301 
302     while (*cp == ' ' || *cp == '\t') {
303 	cp++;
304     }
305 
306     if (func != NULL && *cp++ != ')') {
307 	Parse_Error(PARSE_WARNING, "Missing closing parenthesis for %s()",
308 		     func);
309 	return (0);
310     }
311 
312     *linePtr = cp;
313     return (argLen);
314 }
315 
316 /*-
317  *-----------------------------------------------------------------------
318  * CondDoDefined --
319  *	Handle the 'defined' function for conditionals.
320  *
321  * Results:
322  *	TRUE if the given variable is defined.
323  *
324  * Side Effects:
325  *	None.
326  *
327  *-----------------------------------------------------------------------
328  */
329 static Boolean
330 CondDoDefined(int argLen MAKE_ATTR_UNUSED, const char *arg)
331 {
332     char    *p1;
333     Boolean result;
334 
335     if (Var_Value(arg, VAR_CMD, &p1) != NULL) {
336 	result = TRUE;
337     } else {
338 	result = FALSE;
339     }
340     if (p1)
341 	free(p1);
342     return (result);
343 }
344 
345 /*-
346  *-----------------------------------------------------------------------
347  * CondStrMatch --
348  *	Front-end for Str_Match so it returns 0 on match and non-zero
349  *	on mismatch. Callback function for CondDoMake via Lst_Find
350  *
351  * Results:
352  *	0 if string matches pattern
353  *
354  * Side Effects:
355  *	None
356  *
357  *-----------------------------------------------------------------------
358  */
359 static int
360 CondStrMatch(const void *string, const void *pattern)
361 {
362     return(!Str_Match(string, pattern));
363 }
364 
365 /*-
366  *-----------------------------------------------------------------------
367  * CondDoMake --
368  *	Handle the 'make' function for conditionals.
369  *
370  * Results:
371  *	TRUE if the given target is being made.
372  *
373  * Side Effects:
374  *	None.
375  *
376  *-----------------------------------------------------------------------
377  */
378 static Boolean
379 CondDoMake(int argLen MAKE_ATTR_UNUSED, const char *arg)
380 {
381     return Lst_Find(create, arg, CondStrMatch) != NULL;
382 }
383 
384 /*-
385  *-----------------------------------------------------------------------
386  * CondDoExists --
387  *	See if the given file exists.
388  *
389  * Results:
390  *	TRUE if the file exists and FALSE if it does not.
391  *
392  * Side Effects:
393  *	None.
394  *
395  *-----------------------------------------------------------------------
396  */
397 static Boolean
398 CondDoExists(int argLen MAKE_ATTR_UNUSED, const char *arg)
399 {
400     Boolean result;
401     char    *path;
402 
403     path = Dir_FindFile(arg, dirSearchPath);
404     if (DEBUG(COND)) {
405 	fprintf(debug_file, "exists(%s) result is \"%s\"\n",
406 	       arg, path ? path : "");
407     }
408     if (path != NULL) {
409 	result = TRUE;
410 	free(path);
411     } else {
412 	result = FALSE;
413     }
414     return (result);
415 }
416 
417 /*-
418  *-----------------------------------------------------------------------
419  * CondDoTarget --
420  *	See if the given node exists and is an actual target.
421  *
422  * Results:
423  *	TRUE if the node exists as a target and FALSE if it does not.
424  *
425  * Side Effects:
426  *	None.
427  *
428  *-----------------------------------------------------------------------
429  */
430 static Boolean
431 CondDoTarget(int argLen MAKE_ATTR_UNUSED, const char *arg)
432 {
433     GNode   *gn;
434 
435     gn = Targ_FindNode(arg, TARG_NOCREATE);
436     return (gn != NULL) && !OP_NOP(gn->type);
437 }
438 
439 /*-
440  *-----------------------------------------------------------------------
441  * CondDoCommands --
442  *	See if the given node exists and is an actual target with commands
443  *	associated with it.
444  *
445  * Results:
446  *	TRUE if the node exists as a target and has commands associated with
447  *	it and FALSE if it does not.
448  *
449  * Side Effects:
450  *	None.
451  *
452  *-----------------------------------------------------------------------
453  */
454 static Boolean
455 CondDoCommands(int argLen MAKE_ATTR_UNUSED, const char *arg)
456 {
457     GNode   *gn;
458 
459     gn = Targ_FindNode(arg, TARG_NOCREATE);
460     return (gn != NULL) && !OP_NOP(gn->type) && !Lst_IsEmpty(gn->commands);
461 }
462 
463 /*-
464  *-----------------------------------------------------------------------
465  * CondCvtArg --
466  *	Convert the given number into a double.
467  *	We try a base 10 or 16 integer conversion first, if that fails
468  *	then we try a floating point conversion instead.
469  *
470  * Results:
471  *	Sets 'value' to double value of string.
472  *	Returns 'true' if the convertion suceeded
473  *
474  *-----------------------------------------------------------------------
475  */
476 static Boolean
477 CondCvtArg(char *str, double *value)
478 {
479     char *eptr, ech;
480     unsigned long l_val;
481     double d_val;
482 
483     errno = 0;
484     l_val = strtoul(str, &eptr, str[1] == 'x' ? 16 : 10);
485     ech = *eptr;
486     if (ech == 0 && errno != ERANGE) {
487 	d_val = str[0] == '-' ? -(double)-l_val : (double)l_val;
488     } else {
489 	if (ech != 0 && ech != '.' && ech != 'e' && ech != 'E')
490 	    return FALSE;
491 	d_val = strtod(str, &eptr);
492 	if (*eptr)
493 	    return FALSE;
494     }
495 
496     *value = d_val;
497     return TRUE;
498 }
499 
500 /*-
501  *-----------------------------------------------------------------------
502  * CondGetString --
503  *	Get a string from a variable reference or an optionally quoted
504  *	string.  This is called for the lhs and rhs of string compares.
505  *
506  * Results:
507  *	Sets freeIt if needed,
508  *	Sets quoted if string was quoted,
509  *	Returns NULL on error,
510  *	else returns string - absent any quotes.
511  *
512  * Side Effects:
513  *	Moves condExpr to end of this token.
514  *
515  *
516  *-----------------------------------------------------------------------
517  */
518 /* coverity:[+alloc : arg-*2] */
519 static char *
520 CondGetString(Boolean doEval, Boolean *quoted, void **freeIt)
521 {
522     Buffer buf;
523     char *cp;
524     char *str;
525     int	len;
526     int qt;
527     char *start;
528 
529     Buf_Init(&buf, 0);
530     str = NULL;
531     *freeIt = NULL;
532     *quoted = qt = *condExpr == '"' ? 1 : 0;
533     if (qt)
534 	condExpr++;
535     for (start = condExpr; *condExpr && str == NULL; condExpr++) {
536 	switch (*condExpr) {
537 	case '\\':
538 	    if (condExpr[1] != '\0') {
539 		condExpr++;
540 		Buf_AddByte(&buf, *condExpr);
541 	    }
542 	    break;
543 	case '"':
544 	    if (qt) {
545 		condExpr++;		/* we don't want the quotes */
546 		goto got_str;
547 	    } else
548 		Buf_AddByte(&buf, *condExpr); /* likely? */
549 	    break;
550 	case ')':
551 	case '!':
552 	case '=':
553 	case '>':
554 	case '<':
555 	case ' ':
556 	case '\t':
557 	    if (!qt)
558 		goto got_str;
559 	    else
560 		Buf_AddByte(&buf, *condExpr);
561 	    break;
562 	case '$':
563 	    /* if we are in quotes, then an undefined variable is ok */
564 	    str = Var_Parse(condExpr, VAR_CMD, (qt ? 0 : doEval),
565 			    &len, freeIt);
566 	    if (str == var_Error) {
567 		if (*freeIt) {
568 		    free(*freeIt);
569 		    *freeIt = NULL;
570 		}
571 		/*
572 		 * Even if !doEval, we still report syntax errors, which
573 		 * is what getting var_Error back with !doEval means.
574 		 */
575 		str = NULL;
576 		goto cleanup;
577 	    }
578 	    condExpr += len;
579 	    /*
580 	     * If the '$' was first char (no quotes), and we are
581 	     * followed by space, the operator or end of expression,
582 	     * we are done.
583 	     */
584 	    if ((condExpr == start + len) &&
585 		(*condExpr == '\0' ||
586 		 isspace((unsigned char) *condExpr) ||
587 		 strchr("!=><)", *condExpr))) {
588 		goto cleanup;
589 	    }
590 	    /*
591 	     * Nope, we better copy str to buf
592 	     */
593 	    for (cp = str; *cp; cp++) {
594 		Buf_AddByte(&buf, *cp);
595 	    }
596 	    if (*freeIt) {
597 		free(*freeIt);
598 		*freeIt = NULL;
599 	    }
600 	    str = NULL;			/* not finished yet */
601 	    condExpr--;			/* don't skip over next char */
602 	    break;
603 	default:
604 	    Buf_AddByte(&buf, *condExpr);
605 	    break;
606 	}
607     }
608  got_str:
609     str = Buf_GetAll(&buf, NULL);
610     *freeIt = str;
611  cleanup:
612     Buf_Destroy(&buf, FALSE);
613     return str;
614 }
615 
616 /*-
617  *-----------------------------------------------------------------------
618  * CondToken --
619  *	Return the next token from the input.
620  *
621  * Results:
622  *	A Token for the next lexical token in the stream.
623  *
624  * Side Effects:
625  *	condPushback will be set back to TOK_NONE if it is used.
626  *
627  *-----------------------------------------------------------------------
628  */
629 static Token
630 compare_expression(Boolean doEval)
631 {
632     Token	t;
633     char	*lhs;
634     char	*rhs;
635     char	*op;
636     void	*lhsFree;
637     void	*rhsFree;
638     Boolean lhsQuoted;
639     Boolean rhsQuoted;
640     double  	left, right;
641 
642     t = TOK_ERROR;
643     rhs = NULL;
644     lhsFree = rhsFree = FALSE;
645     lhsQuoted = rhsQuoted = FALSE;
646 
647     /*
648      * Parse the variable spec and skip over it, saving its
649      * value in lhs.
650      */
651     lhs = CondGetString(doEval, &lhsQuoted, &lhsFree);
652     if (!lhs)
653 	goto done;
654 
655     /*
656      * Skip whitespace to get to the operator
657      */
658     while (isspace((unsigned char) *condExpr))
659 	condExpr++;
660 
661     /*
662      * Make sure the operator is a valid one. If it isn't a
663      * known relational operator, pretend we got a
664      * != 0 comparison.
665      */
666     op = condExpr;
667     switch (*condExpr) {
668 	case '!':
669 	case '=':
670 	case '<':
671 	case '>':
672 	    if (condExpr[1] == '=') {
673 		condExpr += 2;
674 	    } else {
675 		condExpr += 1;
676 	    }
677 	    break;
678 	default:
679 	    if (!doEval) {
680 		t = TOK_FALSE;
681 		goto done;
682 	    }
683 	    /* For .ifxxx "..." check for non-empty string. */
684 	    if (lhsQuoted) {
685 		t = lhs[0] != 0;
686 		goto done;
687 	    }
688 	    /* For .ifxxx <number> compare against zero */
689 	    if (CondCvtArg(lhs, &left)) {
690 		t = left != 0.0;
691 		goto done;
692 	    }
693 	    /* For .if ${...} check for non-empty string (defProc is ifdef). */
694 	    if (if_info->form[0] == 0) {
695 		t = lhs[0] != 0;
696 		goto done;
697 	    }
698 	    /* Otherwise action default test ... */
699 	    t = if_info->defProc(strlen(lhs), lhs) != if_info->doNot;
700 	    goto done;
701     }
702 
703     while (isspace((unsigned char)*condExpr))
704 	condExpr++;
705 
706     if (*condExpr == '\0') {
707 	Parse_Error(PARSE_WARNING,
708 		    "Missing right-hand-side of operator");
709 	goto done;
710     }
711 
712     rhs = CondGetString(doEval, &rhsQuoted, &rhsFree);
713     if (!rhs)
714 	goto done;
715 
716     if (rhsQuoted || lhsQuoted) {
717 do_string_compare:
718 	if (((*op != '!') && (*op != '=')) || (op[1] != '=')) {
719 	    Parse_Error(PARSE_WARNING,
720     "String comparison operator should be either == or !=");
721 	    goto done;
722 	}
723 
724 	if (DEBUG(COND)) {
725 	    fprintf(debug_file, "lhs = \"%s\", rhs = \"%s\", op = %.2s\n",
726 		   lhs, rhs, op);
727 	}
728 	/*
729 	 * Null-terminate rhs and perform the comparison.
730 	 * t is set to the result.
731 	 */
732 	if (*op == '=') {
733 	    t = strcmp(lhs, rhs) == 0;
734 	} else {
735 	    t = strcmp(lhs, rhs) != 0;
736 	}
737     } else {
738 	/*
739 	 * rhs is either a float or an integer. Convert both the
740 	 * lhs and the rhs to a double and compare the two.
741 	 */
742 
743 	if (!CondCvtArg(lhs, &left) || !CondCvtArg(rhs, &right))
744 	    goto do_string_compare;
745 
746 	if (DEBUG(COND)) {
747 	    fprintf(debug_file, "left = %f, right = %f, op = %.2s\n", left,
748 		   right, op);
749 	}
750 	switch(op[0]) {
751 	case '!':
752 	    if (op[1] != '=') {
753 		Parse_Error(PARSE_WARNING,
754 			    "Unknown operator");
755 		goto done;
756 	    }
757 	    t = (left != right);
758 	    break;
759 	case '=':
760 	    if (op[1] != '=') {
761 		Parse_Error(PARSE_WARNING,
762 			    "Unknown operator");
763 		goto done;
764 	    }
765 	    t = (left == right);
766 	    break;
767 	case '<':
768 	    if (op[1] == '=') {
769 		t = (left <= right);
770 	    } else {
771 		t = (left < right);
772 	    }
773 	    break;
774 	case '>':
775 	    if (op[1] == '=') {
776 		t = (left >= right);
777 	    } else {
778 		t = (left > right);
779 	    }
780 	    break;
781 	}
782     }
783 
784 done:
785     if (lhsFree)
786 	free(lhsFree);
787     if (rhsFree)
788 	free(rhsFree);
789     return t;
790 }
791 
792 static int
793 get_mpt_arg(char **linePtr, char **argPtr, const char *func MAKE_ATTR_UNUSED)
794 {
795     /*
796      * Use Var_Parse to parse the spec in parens and return
797      * TOK_TRUE if the resulting string is empty.
798      */
799     int	    length;
800     void    *freeIt;
801     char    *val;
802     char    *cp = *linePtr;
803 
804     /* We do all the work here and return the result as the length */
805     *argPtr = NULL;
806 
807     val = Var_Parse(cp - 1, VAR_CMD, FALSE, &length, &freeIt);
808     /*
809      * Advance *linePtr to beyond the closing ). Note that
810      * we subtract one because 'length' is calculated from 'cp - 1'.
811      */
812     *linePtr = cp - 1 + length;
813 
814     if (val == var_Error) {
815 	free(freeIt);
816 	return -1;
817     }
818 
819     /* A variable is empty when it just contains spaces... 4/15/92, christos */
820     while (isspace(*(unsigned char *)val))
821 	val++;
822 
823     /*
824      * For consistency with the other functions we can't generate the
825      * true/false here.
826      */
827     length = *val ? 2 : 1;
828     if (freeIt)
829 	free(freeIt);
830     return length;
831 }
832 
833 static Boolean
834 CondDoEmpty(int arglen, const char *arg MAKE_ATTR_UNUSED)
835 {
836     return arglen == 1;
837 }
838 
839 static Token
840 compare_function(Boolean doEval)
841 {
842     static const struct fn_def {
843 	const char  *fn_name;
844 	int         fn_name_len;
845         int         (*fn_getarg)(char **, char **, const char *);
846 	Boolean     (*fn_proc)(int, const char *);
847     } fn_defs[] = {
848 	{ "defined",   7, CondGetArg, CondDoDefined },
849 	{ "make",      4, CondGetArg, CondDoMake },
850 	{ "exists",    6, CondGetArg, CondDoExists },
851 	{ "empty",     5, get_mpt_arg, CondDoEmpty },
852 	{ "target",    6, CondGetArg, CondDoTarget },
853 	{ "commands",  8, CondGetArg, CondDoCommands },
854 	{ NULL,        0, NULL, NULL },
855     };
856     const struct fn_def *fn_def;
857     Token	t;
858     char	*arg = NULL;
859     int	arglen;
860     char *cp = condExpr;
861     char *cp1;
862 
863     for (fn_def = fn_defs; fn_def->fn_name != NULL; fn_def++) {
864 	if (!istoken(cp, fn_def->fn_name, fn_def->fn_name_len))
865 	    continue;
866 	cp += fn_def->fn_name_len;
867 	/* There can only be whitespace before the '(' */
868 	while (isspace(*(unsigned char *)cp))
869 	    cp++;
870 	if (*cp != '(')
871 	    break;
872 
873 	arglen = fn_def->fn_getarg(&cp, &arg, fn_def->fn_name);
874 	if (arglen <= 0) {
875 	    condExpr = cp;
876 	    return arglen < 0 ? TOK_ERROR : TOK_FALSE;
877 	}
878 	/* Evaluate the argument using the required function. */
879 	t = !doEval || fn_def->fn_proc(arglen, arg);
880 	if (arg)
881 	    free(arg);
882 	condExpr = cp;
883 	return t;
884     }
885 
886     /* Push anything numeric through the compare expression */
887     cp = condExpr;
888     if (isdigit((unsigned char)cp[0]) || strchr("+-", cp[0]))
889 	return compare_expression(doEval);
890 
891     /*
892      * Most likely we have a naked token to apply the default function to.
893      * However ".if a == b" gets here when the "a" is unquoted and doesn't
894      * start with a '$'. This surprises people.
895      * If what follows the function argument is a '=' or '!' then the syntax
896      * would be invalid if we did "defined(a)" - so instead treat as an
897      * expression.
898      */
899     arglen = CondGetArg(&cp, &arg, NULL);
900     for (cp1 = cp; isspace(*(unsigned char *)cp1); cp1++)
901 	continue;
902     if (*cp1 == '=' || *cp1 == '!')
903 	return compare_expression(doEval);
904     condExpr = cp;
905 
906     /*
907      * Evaluate the argument using the default function.
908      * This path always treats .if as .ifdef. To get here the character
909      * after .if must have been taken literally, so the argument cannot
910      * be empty - even if it contained a variable expansion.
911      */
912     t = !doEval || if_info->defProc(arglen, arg) != if_info->doNot;
913     if (arg)
914 	free(arg);
915     return t;
916 }
917 
918 static Token
919 CondToken(Boolean doEval)
920 {
921     Token t;
922 
923     t = condPushBack;
924     if (t != TOK_NONE) {
925 	condPushBack = TOK_NONE;
926 	return t;
927     }
928 
929     while (*condExpr == ' ' || *condExpr == '\t') {
930 	condExpr++;
931     }
932 
933     switch (*condExpr) {
934 
935     case '(':
936 	condExpr++;
937 	return TOK_LPAREN;
938 
939     case ')':
940 	condExpr++;
941 	return TOK_RPAREN;
942 
943     case '|':
944 	if (condExpr[1] == '|') {
945 	    condExpr++;
946 	}
947 	condExpr++;
948 	return TOK_OR;
949 
950     case '&':
951 	if (condExpr[1] == '&') {
952 	    condExpr++;
953 	}
954 	condExpr++;
955 	return TOK_AND;
956 
957     case '!':
958 	condExpr++;
959 	return TOK_NOT;
960 
961     case '#':
962     case '\n':
963     case '\0':
964 	return TOK_EOF;
965 
966     case '"':
967     case '$':
968 	return compare_expression(doEval);
969 
970     default:
971 	return compare_function(doEval);
972     }
973 }
974 
975 /*-
976  *-----------------------------------------------------------------------
977  * CondT --
978  *	Parse a single term in the expression. This consists of a terminal
979  *	symbol or TOK_NOT and a terminal symbol (not including the binary
980  *	operators):
981  *	    T -> defined(variable) | make(target) | exists(file) | symbol
982  *	    T -> ! T | ( E )
983  *
984  * Results:
985  *	TOK_TRUE, TOK_FALSE or TOK_ERROR.
986  *
987  * Side Effects:
988  *	Tokens are consumed.
989  *
990  *-----------------------------------------------------------------------
991  */
992 static Token
993 CondT(Boolean doEval)
994 {
995     Token   t;
996 
997     t = CondToken(doEval);
998 
999     if (t == TOK_EOF) {
1000 	/*
1001 	 * If we reached the end of the expression, the expression
1002 	 * is malformed...
1003 	 */
1004 	t = TOK_ERROR;
1005     } else if (t == TOK_LPAREN) {
1006 	/*
1007 	 * T -> ( E )
1008 	 */
1009 	t = CondE(doEval);
1010 	if (t != TOK_ERROR) {
1011 	    if (CondToken(doEval) != TOK_RPAREN) {
1012 		t = TOK_ERROR;
1013 	    }
1014 	}
1015     } else if (t == TOK_NOT) {
1016 	t = CondT(doEval);
1017 	if (t == TOK_TRUE) {
1018 	    t = TOK_FALSE;
1019 	} else if (t == TOK_FALSE) {
1020 	    t = TOK_TRUE;
1021 	}
1022     }
1023     return (t);
1024 }
1025 
1026 /*-
1027  *-----------------------------------------------------------------------
1028  * CondF --
1029  *	Parse a conjunctive factor (nice name, wot?)
1030  *	    F -> T && F | T
1031  *
1032  * Results:
1033  *	TOK_TRUE, TOK_FALSE or TOK_ERROR
1034  *
1035  * Side Effects:
1036  *	Tokens are consumed.
1037  *
1038  *-----------------------------------------------------------------------
1039  */
1040 static Token
1041 CondF(Boolean doEval)
1042 {
1043     Token   l, o;
1044 
1045     l = CondT(doEval);
1046     if (l != TOK_ERROR) {
1047 	o = CondToken(doEval);
1048 
1049 	if (o == TOK_AND) {
1050 	    /*
1051 	     * F -> T && F
1052 	     *
1053 	     * If T is TOK_FALSE, the whole thing will be TOK_FALSE, but we have to
1054 	     * parse the r.h.s. anyway (to throw it away).
1055 	     * If T is TOK_TRUE, the result is the r.h.s., be it an TOK_ERROR or no.
1056 	     */
1057 	    if (l == TOK_TRUE) {
1058 		l = CondF(doEval);
1059 	    } else {
1060 		(void)CondF(FALSE);
1061 	    }
1062 	} else {
1063 	    /*
1064 	     * F -> T
1065 	     */
1066 	    CondPushBack(o);
1067 	}
1068     }
1069     return (l);
1070 }
1071 
1072 /*-
1073  *-----------------------------------------------------------------------
1074  * CondE --
1075  *	Main expression production.
1076  *	    E -> F || E | F
1077  *
1078  * Results:
1079  *	TOK_TRUE, TOK_FALSE or TOK_ERROR.
1080  *
1081  * Side Effects:
1082  *	Tokens are, of course, consumed.
1083  *
1084  *-----------------------------------------------------------------------
1085  */
1086 static Token
1087 CondE(Boolean doEval)
1088 {
1089     Token   l, o;
1090 
1091     l = CondF(doEval);
1092     if (l != TOK_ERROR) {
1093 	o = CondToken(doEval);
1094 
1095 	if (o == TOK_OR) {
1096 	    /*
1097 	     * E -> F || E
1098 	     *
1099 	     * A similar thing occurs for ||, except that here we make sure
1100 	     * the l.h.s. is TOK_FALSE before we bother to evaluate the r.h.s.
1101 	     * Once again, if l is TOK_FALSE, the result is the r.h.s. and once
1102 	     * again if l is TOK_TRUE, we parse the r.h.s. to throw it away.
1103 	     */
1104 	    if (l == TOK_FALSE) {
1105 		l = CondE(doEval);
1106 	    } else {
1107 		(void)CondE(FALSE);
1108 	    }
1109 	} else {
1110 	    /*
1111 	     * E -> F
1112 	     */
1113 	    CondPushBack(o);
1114 	}
1115     }
1116     return (l);
1117 }
1118 
1119 /*-
1120  *-----------------------------------------------------------------------
1121  * Cond_EvalExpression --
1122  *	Evaluate an expression in the passed line. The expression
1123  *	consists of &&, ||, !, make(target), defined(variable)
1124  *	and parenthetical groupings thereof.
1125  *
1126  * Results:
1127  *	COND_PARSE	if the condition was valid grammatically
1128  *	COND_INVALID  	if not a valid conditional.
1129  *
1130  *	(*value) is set to the boolean value of the condition
1131  *
1132  * Side Effects:
1133  *	None.
1134  *
1135  *-----------------------------------------------------------------------
1136  */
1137 int
1138 Cond_EvalExpression(const struct If *info, char *line, Boolean *value, int eprint)
1139 {
1140     static const struct If *dflt_info;
1141     const struct If *sv_if_info = if_info;
1142     char *sv_condExpr = condExpr;
1143     Token sv_condPushBack = condPushBack;
1144     int rval;
1145 
1146     while (*line == ' ' || *line == '\t')
1147 	line++;
1148 
1149     if (info == NULL && (info = dflt_info) == NULL) {
1150 	/* Scan for the entry for .if - it can't be first */
1151 	for (info = ifs; ; info++)
1152 	    if (info->form[0] == 0)
1153 		break;
1154 	dflt_info = info;
1155     }
1156 
1157     if_info = info != NULL ? info : ifs + 4;
1158     condExpr = line;
1159     condPushBack = TOK_NONE;
1160 
1161     rval = do_Cond_EvalExpression(value);
1162 
1163     if (rval == COND_INVALID && eprint)
1164 	Parse_Error(PARSE_FATAL, "Malformed conditional (%s)", line);
1165 
1166     if_info = sv_if_info;
1167     condExpr = sv_condExpr;
1168     condPushBack = sv_condPushBack;
1169 
1170     return rval;
1171 }
1172 
1173 static int
1174 do_Cond_EvalExpression(Boolean *value)
1175 {
1176 
1177     switch (CondE(TRUE)) {
1178     case TOK_TRUE:
1179 	if (CondToken(TRUE) == TOK_EOF) {
1180 	    *value = TRUE;
1181 	    return COND_PARSE;
1182 	}
1183 	break;
1184     case TOK_FALSE:
1185 	if (CondToken(TRUE) == TOK_EOF) {
1186 	    *value = FALSE;
1187 	    return COND_PARSE;
1188 	}
1189 	break;
1190     default:
1191     case TOK_ERROR:
1192 	break;
1193     }
1194 
1195     return COND_INVALID;
1196 }
1197 
1198 
1199 /*-
1200  *-----------------------------------------------------------------------
1201  * Cond_Eval --
1202  *	Evaluate the conditional in the passed line. The line
1203  *	looks like this:
1204  *	    .<cond-type> <expr>
1205  *	where <cond-type> is any of if, ifmake, ifnmake, ifdef,
1206  *	ifndef, elif, elifmake, elifnmake, elifdef, elifndef
1207  *	and <expr> consists of &&, ||, !, make(target), defined(variable)
1208  *	and parenthetical groupings thereof.
1209  *
1210  * Input:
1211  *	line		Line to parse
1212  *
1213  * Results:
1214  *	COND_PARSE	if should parse lines after the conditional
1215  *	COND_SKIP	if should skip lines after the conditional
1216  *	COND_INVALID  	if not a valid conditional.
1217  *
1218  * Side Effects:
1219  *	None.
1220  *
1221  * Note that the states IF_ACTIVE and ELSE_ACTIVE are only different in order
1222  * to detect splurious .else lines (as are SKIP_TO_ELSE and SKIP_TO_ENDIF)
1223  * otherwise .else could be treated as '.elif 1'.
1224  *
1225  *-----------------------------------------------------------------------
1226  */
1227 int
1228 Cond_Eval(char *line)
1229 {
1230     #define	    MAXIF      128	/* maximum depth of .if'ing */
1231     enum if_states {
1232 	IF_ACTIVE,		/* .if or .elif part active */
1233 	ELSE_ACTIVE,		/* .else part active */
1234 	SEARCH_FOR_ELIF,	/* searching for .elif/else to execute */
1235 	SKIP_TO_ELSE,           /* has been true, but not seen '.else' */
1236 	SKIP_TO_ENDIF		/* nothing else to execute */
1237     };
1238     static enum if_states cond_state[MAXIF + 1] = { IF_ACTIVE };
1239 
1240     const struct If *ifp;
1241     Boolean 	    isElif;
1242     Boolean 	    value;
1243     int	    	    level;  	/* Level at which to report errors. */
1244     enum if_states  state;
1245 
1246     level = PARSE_FATAL;
1247 
1248     /* skip leading character (the '.') and any whitespace */
1249     for (line++; *line == ' ' || *line == '\t'; line++)
1250 	continue;
1251 
1252     /* Find what type of if we're dealing with.  */
1253     if (line[0] == 'e') {
1254 	if (line[1] != 'l') {
1255 	    if (!istoken(line + 1, "ndif", 4))
1256 		return COND_INVALID;
1257 	    /* End of conditional section */
1258 	    if (cond_depth == cond_min_depth) {
1259 		Parse_Error(level, "if-less endif");
1260 		return COND_PARSE;
1261 	    }
1262 	    /* Return state for previous conditional */
1263 	    cond_depth--;
1264 	    if (cond_depth > MAXIF)
1265 		return COND_SKIP;
1266 	    return cond_state[cond_depth] <= ELSE_ACTIVE ? COND_PARSE : COND_SKIP;
1267 	}
1268 
1269 	/* Quite likely this is 'else' or 'elif' */
1270 	line += 2;
1271 	if (istoken(line, "se", 2)) {
1272 	    /* It is else... */
1273 	    if (cond_depth == cond_min_depth) {
1274 		Parse_Error(level, "if-less else");
1275 		return COND_PARSE;
1276 	    }
1277 
1278 	    if (cond_depth > MAXIF)
1279 		return COND_SKIP;
1280 	    state = cond_state[cond_depth];
1281 	    switch (state) {
1282 	    case SEARCH_FOR_ELIF:
1283 		state = ELSE_ACTIVE;
1284 		break;
1285 	    case ELSE_ACTIVE:
1286 	    case SKIP_TO_ENDIF:
1287 		Parse_Error(PARSE_WARNING, "extra else");
1288 		/* FALLTHROUGH */
1289 	    default:
1290 	    case IF_ACTIVE:
1291 	    case SKIP_TO_ELSE:
1292 		state = SKIP_TO_ENDIF;
1293 		break;
1294 	    }
1295 	    cond_state[cond_depth] = state;
1296 	    return state <= ELSE_ACTIVE ? COND_PARSE : COND_SKIP;
1297 	}
1298 	/* Assume for now it is an elif */
1299 	isElif = TRUE;
1300     } else
1301 	isElif = FALSE;
1302 
1303     if (line[0] != 'i' || line[1] != 'f')
1304 	/* Not an ifxxx or elifxxx line */
1305 	return COND_INVALID;
1306 
1307     /*
1308      * Figure out what sort of conditional it is -- what its default
1309      * function is, etc. -- by looking in the table of valid "ifs"
1310      */
1311     line += 2;
1312     for (ifp = ifs; ; ifp++) {
1313 	if (ifp->form == NULL)
1314 	    return COND_INVALID;
1315 	if (istoken(ifp->form, line, ifp->formlen)) {
1316 	    line += ifp->formlen;
1317 	    break;
1318 	}
1319     }
1320 
1321     /* Now we know what sort of 'if' it is... */
1322 
1323     if (isElif) {
1324 	if (cond_depth == cond_min_depth) {
1325 	    Parse_Error(level, "if-less elif");
1326 	    return COND_PARSE;
1327 	}
1328 	if (cond_depth > MAXIF)
1329 	    /* Error reported when we saw the .if ... */
1330 	    return COND_SKIP;
1331 	state = cond_state[cond_depth];
1332 	if (state == SKIP_TO_ENDIF || state == ELSE_ACTIVE) {
1333 	    Parse_Error(PARSE_WARNING, "extra elif");
1334 	    cond_state[cond_depth] = SKIP_TO_ENDIF;
1335 	    return COND_SKIP;
1336 	}
1337 	if (state != SEARCH_FOR_ELIF) {
1338 	    /* Either just finished the 'true' block, or already SKIP_TO_ELSE */
1339 	    cond_state[cond_depth] = SKIP_TO_ELSE;
1340 	    return COND_SKIP;
1341 	}
1342     } else {
1343 	/* Normal .if */
1344 	if (cond_depth >= MAXIF) {
1345 	    cond_depth++;
1346 	    Parse_Error(PARSE_FATAL, "Too many nested if's. %d max.", MAXIF);
1347 	    return COND_SKIP;
1348 	}
1349 	state = cond_state[cond_depth];
1350 	cond_depth++;
1351 	if (state > ELSE_ACTIVE) {
1352 	    /* If we aren't parsing the data, treat as always false */
1353 	    cond_state[cond_depth] = SKIP_TO_ELSE;
1354 	    return COND_SKIP;
1355 	}
1356     }
1357 
1358     /* And evaluate the conditional expresssion */
1359     if (Cond_EvalExpression(ifp, line, &value, 1) == COND_INVALID) {
1360 	/* Syntax error in conditional, error message already output. */
1361 	/* Skip everything to matching .endif */
1362 	cond_state[cond_depth] = SKIP_TO_ELSE;
1363 	return COND_SKIP;
1364     }
1365 
1366     if (!value) {
1367 	cond_state[cond_depth] = SEARCH_FOR_ELIF;
1368 	return COND_SKIP;
1369     }
1370     cond_state[cond_depth] = IF_ACTIVE;
1371     return COND_PARSE;
1372 }
1373 
1374 
1375 
1376 /*-
1377  *-----------------------------------------------------------------------
1378  * Cond_End --
1379  *	Make sure everything's clean at the end of a makefile.
1380  *
1381  * Results:
1382  *	None.
1383  *
1384  * Side Effects:
1385  *	Parse_Error will be called if open conditionals are around.
1386  *
1387  *-----------------------------------------------------------------------
1388  */
1389 void
1390 Cond_restore_depth(unsigned int saved_depth)
1391 {
1392     int open_conds = cond_depth - cond_min_depth;
1393 
1394     if (open_conds != 0 || saved_depth > cond_depth) {
1395 	Parse_Error(PARSE_FATAL, "%d open conditional%s", open_conds,
1396 		    open_conds == 1 ? "" : "s");
1397 	cond_depth = cond_min_depth;
1398     }
1399 
1400     cond_min_depth = saved_depth;
1401 }
1402 
1403 unsigned int
1404 Cond_save_depth(void)
1405 {
1406     int depth = cond_min_depth;
1407 
1408     cond_min_depth = cond_depth;
1409     return depth;
1410 }
1411