expr.y revision 166813 
1%{
2/*-
3 * Written by Pace Willisson (pace@blitz.com)
4 * and placed in the public domain.
5 *
6 * Largely rewritten by J.T. Conklin (jtc@wimsey.com)
7 *
8 * $FreeBSD: head/bin/expr/expr.y 166813 2007-02-18 19:48:59Z ceri $
9 */
10
11#include <sys/types.h>
12
13#include <ctype.h>
14#include <err.h>
15#include <errno.h>
16#include <inttypes.h>
17#include <limits.h>
18#include <locale.h>
19#include <stdio.h>
20#include <stdlib.h>
21#include <string.h>
22#include <regex.h>
23#include <unistd.h>
24
25/*
26 * POSIX specifies a specific error code for syntax errors.  We exit
27 * with this code for all errors.
28 */
29#define	ERR_EXIT	2
30
31enum valtype {
32	integer, numeric_string, string
33} ;
34
35struct val {
36	enum valtype type;
37	union {
38		char *s;
39		intmax_t i;
40	} u;
41} ;
42
43struct val *result;
44
45int		chk_div(intmax_t, intmax_t);
46int		chk_minus(intmax_t, intmax_t, intmax_t);
47int		chk_plus(intmax_t, intmax_t, intmax_t);
48int		chk_times(intmax_t, intmax_t, intmax_t);
49void		free_value(struct val *);
50int		is_zero_or_null(struct val *);
51int		isstring(struct val *);
52struct val	*make_integer(intmax_t);
53struct val	*make_str(const char *);
54struct val	*op_and(struct val *, struct val *);
55struct val	*op_colon(struct val *, struct val *);
56struct val	*op_div(struct val *, struct val *);
57struct val	*op_eq(struct val *, struct val *);
58struct val	*op_ge(struct val *, struct val *);
59struct val	*op_gt(struct val *, struct val *);
60struct val	*op_le(struct val *, struct val *);
61struct val	*op_lt(struct val *, struct val *);
62struct val	*op_minus(struct val *, struct val *);
63struct val	*op_ne(struct val *, struct val *);
64struct val	*op_or(struct val *, struct val *);
65struct val	*op_plus(struct val *, struct val *);
66struct val	*op_rem(struct val *, struct val *);
67struct val	*op_times(struct val *, struct val *);
68intmax_t	to_integer(struct val *);
69void		to_string(struct val *);
70int		yyerror(const char *);
71int		yylex(void);
72int		yyparse(void);
73
74static int	eflag;
75char **av;
76%}
77
78%union
79{
80	struct val *val;
81}
82
83%left <val> '|'
84%left <val> '&'
85%left <val> '=' '>' '<' GE LE NE
86%left <val> '+' '-'
87%left <val> '*' '/' '%'
88%left <val> ':'
89
90%token <val> TOKEN
91%type <val> start expr
92
93%%
94
95start: expr { result = $$; }
96
97expr:	TOKEN
98	| '(' expr ')' { $$ = $2; }
99	| expr '|' expr { $$ = op_or ($1, $3); }
100	| expr '&' expr { $$ = op_and ($1, $3); }
101	| expr '=' expr { $$ = op_eq ($1, $3); }
102	| expr '>' expr { $$ = op_gt ($1, $3); }
103	| expr '<' expr { $$ = op_lt ($1, $3); }
104	| expr GE expr  { $$ = op_ge ($1, $3); }
105	| expr LE expr  { $$ = op_le ($1, $3); }
106	| expr NE expr  { $$ = op_ne ($1, $3); }
107	| expr '+' expr { $$ = op_plus ($1, $3); }
108	| expr '-' expr { $$ = op_minus ($1, $3); }
109	| expr '*' expr { $$ = op_times ($1, $3); }
110	| expr '/' expr { $$ = op_div ($1, $3); }
111	| expr '%' expr { $$ = op_rem ($1, $3); }
112	| expr ':' expr { $$ = op_colon ($1, $3); }
113	;
114
115
116%%
117
118struct val *
119make_integer(intmax_t i)
120{
121	struct val *vp;
122
123	vp = (struct val *) malloc (sizeof (*vp));
124	if (vp == NULL) {
125		errx(ERR_EXIT, "malloc() failed");
126	}
127
128	vp->type = integer;
129	vp->u.i  = i;
130	return vp;
131}
132
133struct val *
134make_str(const char *s)
135{
136	struct val *vp;
137	char *ep;
138
139	vp = (struct val *) malloc (sizeof (*vp));
140	if (vp == NULL || ((vp->u.s = strdup (s)) == NULL)) {
141		errx(ERR_EXIT, "malloc() failed");
142	}
143
144	/*
145	 * Previously we tried to scan the string to see if it ``looked like''
146	 * an integer (erroneously, as it happened).  Let strtoimax() do the
147	 * dirty work.  We could cache the value, except that we are using
148	 * a union and need to preserve the original string form until we
149	 * are certain that it is not needed.
150	 *
151	 * IEEE Std.1003.1-2001 says:
152	 * /integer/ An argument consisting only of an (optional) unary minus
153	 *	     followed by digits.
154	 *
155	 * This means that arguments which consist of digits followed by
156	 * non-digits MUST NOT be considered integers.  strtoimax() will
157	 * figure this out for us.
158	 */
159	if (eflag)
160		(void)strtoimax(s, &ep, 10);
161	else
162		(void)strtol(s, &ep, 10);
163
164	if (*ep != '\0')
165		vp->type = string;
166	else
167		vp->type = numeric_string;
168
169	return vp;
170}
171
172
173void
174free_value(struct val *vp)
175{
176	if (vp->type == string || vp->type == numeric_string)
177		free (vp->u.s);
178}
179
180
181intmax_t
182to_integer(struct val *vp)
183{
184	intmax_t i;
185
186	if (vp->type == integer)
187		return 1;
188
189	if (vp->type == string)
190		return 0;
191
192	/* vp->type == numeric_string, make it numeric */
193	errno = 0;
194	if (eflag) {
195		i  = strtoimax(vp->u.s, (char **)NULL, 10);
196		if (errno == ERANGE)
197			err(ERR_EXIT, NULL);
198	} else {
199		i = strtol(vp->u.s, (char **)NULL, 10);
200	}
201
202	free (vp->u.s);
203	vp->u.i = i;
204	vp->type = integer;
205	return 1;
206}
207
208void
209to_string(struct val *vp)
210{
211	char *tmp;
212
213	if (vp->type == string || vp->type == numeric_string)
214		return;
215
216	/*
217	 * log_10(x) ~= 0.3 * log_2(x).  Rounding up gives the number
218	 * of digits; add one each for the sign and terminating null
219	 * character, respectively.
220	 */
221#define	NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
222	tmp = malloc(NDIGITS(vp->u.i));
223	if (tmp == NULL)
224		errx(ERR_EXIT, "malloc() failed");
225
226	sprintf(tmp, "%jd", vp->u.i);
227	vp->type = string;
228	vp->u.s  = tmp;
229}
230
231
232int
233isstring(struct val *vp)
234{
235	/* only TRUE if this string is not a valid integer */
236	return (vp->type == string);
237}
238
239
240int
241yylex(void)
242{
243	char *p;
244
245	if (*av == NULL)
246		return (0);
247
248	p = *av++;
249
250	if (strlen (p) == 1) {
251		if (strchr ("|&=<>+-*/%:()", *p))
252			return (*p);
253	} else if (strlen (p) == 2 && p[1] == '=') {
254		switch (*p) {
255		case '>': return (GE);
256		case '<': return (LE);
257		case '!': return (NE);
258		}
259	}
260
261	yylval.val = make_str (p);
262	return (TOKEN);
263}
264
265int
266is_zero_or_null(struct val *vp)
267{
268	if (vp->type == integer) {
269		return (vp->u.i == 0);
270	} else {
271		return (*vp->u.s == 0 || (to_integer (vp) && vp->u.i == 0));
272	}
273	/* NOTREACHED */
274}
275
276int
277main(int argc, char *argv[])
278{
279	int c;
280
281	setlocale (LC_ALL, "");
282	if (getenv("EXPR_COMPAT") != NULL
283	    || check_utility_compat("expr")) {
284		av = argv + 1;
285		eflag = 1;
286	} else {
287		while ((c = getopt(argc, argv, "e")) != -1)
288			switch (c) {
289			case 'e':
290				eflag = 1;
291				break;
292
293			default:
294				fprintf(stderr,
295				    "usage: expr [-e] expression\n");
296				exit(ERR_EXIT);
297			}
298		av = argv + optind;
299	}
300
301	yyparse();
302
303	if (result->type == integer)
304		printf("%jd\n", result->u.i);
305	else
306		printf("%s\n", result->u.s);
307
308	return (is_zero_or_null(result));
309}
310
311int
312yyerror(const char *s __unused)
313{
314	errx(ERR_EXIT, "syntax error");
315}
316
317
318struct val *
319op_or(struct val *a, struct val *b)
320{
321	if (is_zero_or_null (a)) {
322		free_value (a);
323		return (b);
324	} else {
325		free_value (b);
326		return (a);
327	}
328}
329
330struct val *
331op_and(struct val *a, struct val *b)
332{
333	if (is_zero_or_null (a) || is_zero_or_null (b)) {
334		free_value (a);
335		free_value (b);
336		return (make_integer ((intmax_t)0));
337	} else {
338		free_value (b);
339		return (a);
340	}
341}
342
343struct val *
344op_eq(struct val *a, struct val *b)
345{
346	struct val *r;
347
348	if (isstring (a) || isstring (b)) {
349		to_string (a);
350		to_string (b);
351		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) == 0));
352	} else {
353		(void)to_integer(a);
354		(void)to_integer(b);
355		r = make_integer ((intmax_t)(a->u.i == b->u.i));
356	}
357
358	free_value (a);
359	free_value (b);
360	return r;
361}
362
363struct val *
364op_gt(struct val *a, struct val *b)
365{
366	struct val *r;
367
368	if (isstring (a) || isstring (b)) {
369		to_string (a);
370		to_string (b);
371		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) > 0));
372	} else {
373		(void)to_integer(a);
374		(void)to_integer(b);
375		r = make_integer ((intmax_t)(a->u.i > b->u.i));
376	}
377
378	free_value (a);
379	free_value (b);
380	return r;
381}
382
383struct val *
384op_lt(struct val *a, struct val *b)
385{
386	struct val *r;
387
388	if (isstring (a) || isstring (b)) {
389		to_string (a);
390		to_string (b);
391		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) < 0));
392	} else {
393		(void)to_integer(a);
394		(void)to_integer(b);
395		r = make_integer ((intmax_t)(a->u.i < b->u.i));
396	}
397
398	free_value (a);
399	free_value (b);
400	return r;
401}
402
403struct val *
404op_ge(struct val *a, struct val *b)
405{
406	struct val *r;
407
408	if (isstring (a) || isstring (b)) {
409		to_string (a);
410		to_string (b);
411		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) >= 0));
412	} else {
413		(void)to_integer(a);
414		(void)to_integer(b);
415		r = make_integer ((intmax_t)(a->u.i >= b->u.i));
416	}
417
418	free_value (a);
419	free_value (b);
420	return r;
421}
422
423struct val *
424op_le(struct val *a, struct val *b)
425{
426	struct val *r;
427
428	if (isstring (a) || isstring (b)) {
429		to_string (a);
430		to_string (b);
431		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) <= 0));
432	} else {
433		(void)to_integer(a);
434		(void)to_integer(b);
435		r = make_integer ((intmax_t)(a->u.i <= b->u.i));
436	}
437
438	free_value (a);
439	free_value (b);
440	return r;
441}
442
443struct val *
444op_ne(struct val *a, struct val *b)
445{
446	struct val *r;
447
448	if (isstring (a) || isstring (b)) {
449		to_string (a);
450		to_string (b);
451		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) != 0));
452	} else {
453		(void)to_integer(a);
454		(void)to_integer(b);
455		r = make_integer ((intmax_t)(a->u.i != b->u.i));
456	}
457
458	free_value (a);
459	free_value (b);
460	return r;
461}
462
463int
464chk_plus(intmax_t a, intmax_t b, intmax_t r)
465{
466
467	/* sum of two positive numbers must be positive */
468	if (a > 0 && b > 0 && r <= 0)
469		return 1;
470	/* sum of two negative numbers must be negative */
471	if (a < 0 && b < 0 && r >= 0)
472		return 1;
473	/* all other cases are OK */
474	return 0;
475}
476
477struct val *
478op_plus(struct val *a, struct val *b)
479{
480	struct val *r;
481
482	if (!to_integer(a) || !to_integer(b)) {
483		errx(ERR_EXIT, "non-numeric argument");
484	}
485
486	if (eflag) {
487		r = make_integer(a->u.i + b->u.i);
488		if (chk_plus(a->u.i, b->u.i, r->u.i)) {
489			errx(ERR_EXIT, "overflow");
490		}
491	} else
492		r = make_integer((long)a->u.i + (long)b->u.i);
493
494	free_value (a);
495	free_value (b);
496	return r;
497}
498
499int
500chk_minus(intmax_t a, intmax_t b, intmax_t r)
501{
502
503	/* special case subtraction of INTMAX_MIN */
504	if (b == INTMAX_MIN) {
505		if (a >= 0)
506			return 1;
507		else
508			return 0;
509	}
510	/* this is allowed for b != INTMAX_MIN */
511	return chk_plus (a, -b, r);
512}
513
514struct val *
515op_minus(struct val *a, struct val *b)
516{
517	struct val *r;
518
519	if (!to_integer(a) || !to_integer(b)) {
520		errx(ERR_EXIT, "non-numeric argument");
521	}
522
523	if (eflag) {
524		r = make_integer(a->u.i - b->u.i);
525		if (chk_minus(a->u.i, b->u.i, r->u.i)) {
526			errx(ERR_EXIT, "overflow");
527		}
528	} else
529		r = make_integer((long)a->u.i - (long)b->u.i);
530
531	free_value (a);
532	free_value (b);
533	return r;
534}
535
536int
537chk_times(intmax_t a, intmax_t b, intmax_t r)
538{
539	/* special case: first operand is 0, no overflow possible */
540	if (a == 0)
541		return 0;
542	/* verify that result of division matches second operand */
543	if (r / a != b)
544		return 1;
545	return 0;
546}
547
548struct val *
549op_times(struct val *a, struct val *b)
550{
551	struct val *r;
552
553	if (!to_integer(a) || !to_integer(b)) {
554		errx(ERR_EXIT, "non-numeric argument");
555	}
556
557	if (eflag) {
558		r = make_integer(a->u.i * b->u.i);
559		if (chk_times(a->u.i, b->u.i, r->u.i)) {
560			errx(ERR_EXIT, "overflow");
561		}
562	} else
563		r = make_integer((long)a->u.i * (long)b->u.i);
564
565	free_value (a);
566	free_value (b);
567	return (r);
568}
569
570int
571chk_div(intmax_t a, intmax_t b)
572{
573	/* div by zero has been taken care of before */
574	/* only INTMAX_MIN / -1 causes overflow */
575	if (a == INTMAX_MIN && b == -1)
576		return 1;
577	/* everything else is OK */
578	return 0;
579}
580
581struct val *
582op_div(struct val *a, struct val *b)
583{
584	struct val *r;
585
586	if (!to_integer(a) || !to_integer(b)) {
587		errx(ERR_EXIT, "non-numeric argument");
588	}
589
590	if (b->u.i == 0) {
591		errx(ERR_EXIT, "division by zero");
592	}
593
594	if (eflag) {
595		r = make_integer(a->u.i / b->u.i);
596		if (chk_div(a->u.i, b->u.i)) {
597			errx(ERR_EXIT, "overflow");
598		}
599	} else
600		r = make_integer((long)a->u.i / (long)b->u.i);
601
602	free_value (a);
603	free_value (b);
604	return r;
605}
606
607struct val *
608op_rem(struct val *a, struct val *b)
609{
610	struct val *r;
611
612	if (!to_integer(a) || !to_integer(b)) {
613		errx(ERR_EXIT, "non-numeric argument");
614	}
615
616	if (b->u.i == 0) {
617		errx(ERR_EXIT, "division by zero");
618	}
619
620	if (eflag)
621		r = make_integer(a->u.i % b->u.i);
622	        /* chk_rem necessary ??? */
623	else
624		r = make_integer((long)a->u.i % (long)b->u.i);
625
626	free_value (a);
627	free_value (b);
628	return r;
629}
630
631struct val *
632op_colon(struct val *a, struct val *b)
633{
634	regex_t rp;
635	regmatch_t rm[2];
636	char errbuf[256];
637	int eval;
638	struct val *v;
639
640	/* coerce both arguments to strings */
641	to_string(a);
642	to_string(b);
643
644	/* compile regular expression */
645	if ((eval = regcomp (&rp, b->u.s, 0)) != 0) {
646		regerror (eval, &rp, errbuf, sizeof(errbuf));
647		errx(ERR_EXIT, "%s", errbuf);
648	}
649
650	/* compare string against pattern */
651	/* remember that patterns are anchored to the beginning of the line */
652	if (regexec(&rp, a->u.s, (size_t)2, rm, 0) == 0 && rm[0].rm_so == 0) {
653		if (rm[1].rm_so >= 0) {
654			*(a->u.s + rm[1].rm_eo) = '\0';
655			v = make_str (a->u.s + rm[1].rm_so);
656
657		} else {
658			v = make_integer ((intmax_t)(rm[0].rm_eo - rm[0].rm_so));
659		}
660	} else {
661		if (rp.re_nsub == 0) {
662			v = make_integer ((intmax_t)0);
663		} else {
664			v = make_str ("");
665		}
666	}
667
668	/* free arguments and pattern buffer */
669	free_value (a);
670	free_value (b);
671	regfree (&rp);
672
673	return v;
674}
675