xref: /freebsd/bin/expr/expr.y (revision ca987d4641cdcd7f27e153db17c5bf064934faf5) 
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  * $FreeBSD$
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 
31 enum valtype {
32 	integer, numeric_string, string
33 } ;
34 
35 struct val {
36 	enum valtype type;
37 	union {
38 		char *s;
39 		intmax_t i;
40 	} u;
41 } ;
42 
43 char		**av;
44 int		nonposix;
45 struct val	*result;
46 
47 void		assert_to_integer(struct val *);
48 void		assert_div(intmax_t, intmax_t);
49 void		assert_minus(intmax_t, intmax_t, intmax_t);
50 void		assert_plus(intmax_t, intmax_t, intmax_t);
51 void		assert_times(intmax_t, intmax_t, intmax_t);
52 int		compare_vals(struct val *, struct val *);
53 void		free_value(struct val *);
54 int		is_integer(const char *);
55 int		is_string(struct val *);
56 int		is_zero_or_null(struct val *);
57 struct val	*make_integer(intmax_t);
58 struct val	*make_str(const char *);
59 struct val	*op_and(struct val *, struct val *);
60 struct val	*op_colon(struct val *, struct val *);
61 struct val	*op_div(struct val *, struct val *);
62 struct val	*op_eq(struct val *, struct val *);
63 struct val	*op_ge(struct val *, struct val *);
64 struct val	*op_gt(struct val *, struct val *);
65 struct val	*op_le(struct val *, struct val *);
66 struct val	*op_lt(struct val *, struct val *);
67 struct val	*op_minus(struct val *, struct val *);
68 struct val	*op_ne(struct val *, struct val *);
69 struct val	*op_or(struct val *, struct val *);
70 struct val	*op_plus(struct val *, struct val *);
71 struct val	*op_rem(struct val *, struct val *);
72 struct val	*op_times(struct val *, struct val *);
73 int		to_integer(struct val *);
74 void		to_string(struct val *);
75 int		yyerror(const char *);
76 int		yylex(void);
77 
78 %}
79 
80 %union
81 {
82 	struct val *val;
83 }
84 
85 %left <val> '|'
86 %left <val> '&'
87 %left <val> '=' '>' '<' GE LE NE
88 %left <val> '+' '-'
89 %left <val> '*' '/' '%'
90 %left <val> ':'
91 
92 %token <val> TOKEN
93 %type <val> start expr
94 
95 %%
96 
97 start: expr { result = $$; }
98 
99 expr:	TOKEN
100 	| '(' expr ')' { $$ = $2; }
101 	| expr '|' expr { $$ = op_or($1, $3); }
102 	| expr '&' expr { $$ = op_and($1, $3); }
103 	| expr '=' expr { $$ = op_eq($1, $3); }
104 	| expr '>' expr { $$ = op_gt($1, $3); }
105 	| expr '<' expr { $$ = op_lt($1, $3); }
106 	| expr GE expr  { $$ = op_ge($1, $3); }
107 	| expr LE expr  { $$ = op_le($1, $3); }
108 	| expr NE expr  { $$ = op_ne($1, $3); }
109 	| expr '+' expr { $$ = op_plus($1, $3); }
110 	| expr '-' expr { $$ = op_minus($1, $3); }
111 	| expr '*' expr { $$ = op_times($1, $3); }
112 	| expr '/' expr { $$ = op_div($1, $3); }
113 	| expr '%' expr { $$ = op_rem($1, $3); }
114 	| expr ':' expr { $$ = op_colon($1, $3); }
115 	;
116 
117 %%
118 
119 struct val *
120 make_integer(intmax_t i)
121 {
122 	struct val *vp;
123 
124 	vp = (struct val *)malloc(sizeof(*vp));
125 	if (vp == NULL)
126 		errx(ERR_EXIT, "malloc() failed");
127 
128 	vp->type = integer;
129 	vp->u.i  = i;
130 	return (vp);
131 }
132 
133 struct val *
134 make_str(const char *s)
135 {
136 	struct val *vp;
137 
138 	vp = (struct val *)malloc(sizeof(*vp));
139 	if (vp == NULL || ((vp->u.s = strdup(s)) == NULL))
140 		errx(ERR_EXIT, "malloc() failed");
141 
142 	if (is_integer(s))
143 		vp->type = numeric_string;
144 	else
145 		vp->type = string;
146 
147 	return (vp);
148 }
149 
150 void
151 free_value(struct val *vp)
152 {
153 	if (vp->type == string || vp->type == numeric_string)
154 		free(vp->u.s);
155 }
156 
157 int
158 to_integer(struct val *vp)
159 {
160 	intmax_t i;
161 
162 	/* we can only convert numeric_string to integer, here */
163 	if (vp->type == numeric_string) {
164 		errno = 0;
165 		i  = strtoimax(vp->u.s, (char **)NULL, 10);
166 		/* just keep as numeric_string, if the conversion fails */
167 		if (errno != ERANGE) {
168 			free(vp->u.s);
169 			vp->u.i = i;
170 			vp->type = integer;
171 		}
172 	}
173 	return (vp->type == integer);
174 }
175 
176 void
177 assert_to_integer(struct val *vp)
178 {
179 	if (vp->type == string)
180 		errx(ERR_EXIT, "not a decimal number: '%s'", vp->u.s);
181 	if (!to_integer(vp))
182 		errx(ERR_EXIT, "operand too large: '%s'", vp->u.s);
183 }
184 
185 void
186 to_string(struct val *vp)
187 {
188 	char *tmp;
189 
190 	if (vp->type == string || vp->type == numeric_string)
191 		return;
192 
193 	/*
194 	 * log_10(x) ~= 0.3 * log_2(x).  Rounding up gives the number
195 	 * of digits; add one each for the sign and terminating null
196 	 * character, respectively.
197 	 */
198 #define	NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
199 	tmp = malloc(NDIGITS(vp->u.i));
200 	if (tmp == NULL)
201 		errx(ERR_EXIT, "malloc() failed");
202 
203 	sprintf(tmp, "%jd", vp->u.i);
204 	vp->type = string;
205 	vp->u.s  = tmp;
206 }
207 
208 int
209 is_integer(const char *s)
210 {
211 	if (nonposix) {
212 		if (*s == '\0')
213 			return (1);
214 		while (isspace((unsigned char)*s))
215 			s++;
216 	}
217 	if (*s == '-' || (nonposix && *s == '+'))
218 		s++;
219 	if (*s == '\0')
220 		return (0);
221 	while (isdigit((unsigned char)*s))
222 		s++;
223 	return (*s == '\0');
224 }
225 
226 int
227 is_string(struct val *vp)
228 {
229 	/* only TRUE if this string is not a valid integer */
230 	return (vp->type == string);
231 }
232 
233 int
234 yylex(void)
235 {
236 	char *p;
237 
238 	if (*av == NULL)
239 		return (0);
240 
241 	p = *av++;
242 
243 	if (strlen(p) == 1) {
244 		if (strchr("|&=<>+-*/%:()", *p))
245 			return (*p);
246 	} else if (strlen(p) == 2 && p[1] == '=') {
247 		switch (*p) {
248 		case '>': return (GE);
249 		case '<': return (LE);
250 		case '!': return (NE);
251 		}
252 	}
253 
254 	yylval.val = make_str(p);
255 	return (TOKEN);
256 }
257 
258 int
259 is_zero_or_null(struct val *vp)
260 {
261 	if (vp->type == integer)
262 		return (vp->u.i == 0);
263 
264 	return (*vp->u.s == 0 || (to_integer(vp) && vp->u.i == 0));
265 }
266 
267 int
268 main(int argc, char *argv[])
269 {
270 	int c;
271 
272 	setlocale(LC_ALL, "");
273 	if (getenv("EXPR_COMPAT") != NULL
274 	    || check_utility_compat("expr")) {
275 		av = argv + 1;
276 		nonposix = 1;
277 	} else {
278 		while ((c = getopt(argc, argv, "e")) != -1) {
279 			switch (c) {
280 			case 'e':
281 				nonposix = 1;
282 				break;
283 			default:
284 				errx(ERR_EXIT,
285 				    "usage: expr [-e] expression\n");
286 			}
287 		}
288 		av = argv + optind;
289 	}
290 
291 	yyparse();
292 
293 	if (result->type == integer)
294 		printf("%jd\n", result->u.i);
295 	else
296 		printf("%s\n", result->u.s);
297 
298 	return (is_zero_or_null(result));
299 }
300 
301 int
302 yyerror(const char *s __unused)
303 {
304 	errx(ERR_EXIT, "syntax error");
305 }
306 
307 struct val *
308 op_or(struct val *a, struct val *b)
309 {
310 	if (!is_zero_or_null(a)) {
311 		free_value(b);
312 		return (a);
313 	}
314 	free_value(a);
315 	if (!is_zero_or_null(b))
316 		return (b);
317 	free_value(b);
318 	return (make_integer((intmax_t)0));
319 }
320 
321 struct val *
322 op_and(struct val *a, struct val *b)
323 {
324 	if (is_zero_or_null(a) || is_zero_or_null(b)) {
325 		free_value(a);
326 		free_value(b);
327 		return (make_integer((intmax_t)0));
328 	} else {
329 		free_value(b);
330 		return (a);
331 	}
332 }
333 
334 int
335 compare_vals(struct val *a, struct val *b)
336 {
337 	int r;
338 
339 	if (is_string(a) || is_string(b)) {
340 		to_string(a);
341 		to_string(b);
342 		r = strcoll(a->u.s, b->u.s);
343 	} else {
344 		assert_to_integer(a);
345 		assert_to_integer(b);
346 		if (a->u.i > b->u.i)
347 			r = 1;
348 		else if (a->u.i < b->u.i)
349 			r = -1;
350 		else
351 			r = 0;
352 	}
353 
354 	free_value(a);
355 	free_value(b);
356 	return (r);
357 }
358 
359 struct val *
360 op_eq(struct val *a, struct val *b)
361 {
362 	return (make_integer((intmax_t)(compare_vals(a, b) == 0)));
363 }
364 
365 struct val *
366 op_gt(struct val *a, struct val *b)
367 {
368 	return (make_integer((intmax_t)(compare_vals(a, b) > 0)));
369 }
370 
371 struct val *
372 op_lt(struct val *a, struct val *b)
373 {
374 	return (make_integer((intmax_t)(compare_vals(a, b) < 0)));
375 }
376 
377 struct val *
378 op_ge(struct val *a, struct val *b)
379 {
380 	return (make_integer((intmax_t)(compare_vals(a, b) >= 0)));
381 }
382 
383 struct val *
384 op_le(struct val *a, struct val *b)
385 {
386 	return (make_integer((intmax_t)(compare_vals(a, b) <= 0)));
387 }
388 
389 struct val *
390 op_ne(struct val *a, struct val *b)
391 {
392 	return (make_integer((intmax_t)(compare_vals(a, b) != 0)));
393 }
394 
395 void
396 assert_plus(intmax_t a, intmax_t b, intmax_t r)
397 {
398 	/*
399 	 * sum of two positive numbers must be positive,
400 	 * sum of two negative numbers must be negative
401 	 */
402 	if ((a > 0 && b > 0 && r <= 0) ||
403 	    (a < 0 && b < 0 && r >= 0))
404 		errx(ERR_EXIT, "overflow");
405 }
406 
407 struct val *
408 op_plus(struct val *a, struct val *b)
409 {
410 	struct val *r;
411 
412 	assert_to_integer(a);
413 	assert_to_integer(b);
414 	r = make_integer(a->u.i + b->u.i);
415 	assert_plus(a->u.i, b->u.i, r->u.i);
416 
417 	free_value(a);
418 	free_value(b);
419 	return (r);
420 }
421 
422 void
423 assert_minus(intmax_t a, intmax_t b, intmax_t r)
424 {
425 	/* special case subtraction of INTMAX_MIN */
426 	if (b == INTMAX_MIN && a < 0)
427 		errx(ERR_EXIT, "overflow");
428 	/* check addition of negative subtrahend */
429 	assert_plus(a, -b, r);
430 }
431 
432 struct val *
433 op_minus(struct val *a, struct val *b)
434 {
435 	struct val *r;
436 
437 	assert_to_integer(a);
438 	assert_to_integer(b);
439 	r = make_integer(a->u.i - b->u.i);
440 	assert_minus(a->u.i, b->u.i, r->u.i);
441 
442 	free_value(a);
443 	free_value(b);
444 	return (r);
445 }
446 
447 /*
448  * We depend on undefined behaviour giving a result (in r).
449  * To test this result, pass it as volatile.  This prevents
450  * optimizing away of the test based on the undefined behaviour.
451  */
452 void
453 assert_times(intmax_t a, intmax_t b, volatile intmax_t r)
454 {
455 	/*
456 	 * If the first operand is 0, no overflow is possible,
457 	 * else the result of the division test must match the
458 	 * second operand.
459 	 *
460 	 * Be careful to avoid overflow in the overflow test, as
461 	 * in assert_div().  Overflow in division would kill us
462 	 * with a SIGFPE before getting the test wrong.  In old
463 	 * buggy versions, optimization used to give a null test
464 	 * instead of a SIGFPE.
465 	 */
466 	if ((a == -1 && b == INTMAX_MIN) || (a != 0 && r / a != b))
467 		errx(ERR_EXIT, "overflow");
468 }
469 
470 struct val *
471 op_times(struct val *a, struct val *b)
472 {
473 	struct val *r;
474 
475 	assert_to_integer(a);
476 	assert_to_integer(b);
477 	r = make_integer(a->u.i * b->u.i);
478 	assert_times(a->u.i, b->u.i, r->u.i);
479 
480 	free_value(a);
481 	free_value(b);
482 	return (r);
483 }
484 
485 void
486 assert_div(intmax_t a, intmax_t b)
487 {
488 	if (b == 0)
489 		errx(ERR_EXIT, "division by zero");
490 	/* only INTMAX_MIN / -1 causes overflow */
491 	if (a == INTMAX_MIN && b == -1)
492 		errx(ERR_EXIT, "overflow");
493 }
494 
495 struct val *
496 op_div(struct val *a, struct val *b)
497 {
498 	struct val *r;
499 
500 	assert_to_integer(a);
501 	assert_to_integer(b);
502 	/* assert based on operands only, not on result */
503 	assert_div(a->u.i, b->u.i);
504 	r = make_integer(a->u.i / b->u.i);
505 
506 	free_value(a);
507 	free_value(b);
508 	return (r);
509 }
510 
511 struct val *
512 op_rem(struct val *a, struct val *b)
513 {
514 	struct val *r;
515 
516 	assert_to_integer(a);
517 	assert_to_integer(b);
518 	/* pass a=1 to only check for div by zero */
519 	assert_div(1, b->u.i);
520 	r = make_integer(a->u.i % b->u.i);
521 
522 	free_value(a);
523 	free_value(b);
524 	return (r);
525 }
526 
527 struct val *
528 op_colon(struct val *a, struct val *b)
529 {
530 	regex_t rp;
531 	regmatch_t rm[2];
532 	char errbuf[256];
533 	int eval;
534 	struct val *v;
535 
536 	/* coerce both arguments to strings */
537 	to_string(a);
538 	to_string(b);
539 
540 	/* compile regular expression */
541 	if ((eval = regcomp(&rp, b->u.s, 0)) != 0) {
542 		regerror(eval, &rp, errbuf, sizeof(errbuf));
543 		errx(ERR_EXIT, "%s", errbuf);
544 	}
545 
546 	/* compare string against pattern */
547 	/* remember that patterns are anchored to the beginning of the line */
548 	if (regexec(&rp, a->u.s, (size_t)2, rm, 0) == 0 && rm[0].rm_so == 0)
549 		if (rm[1].rm_so >= 0) {
550 			*(a->u.s + rm[1].rm_eo) = '\0';
551 			v = make_str(a->u.s + rm[1].rm_so);
552 
553 		} else
554 			v = make_integer((intmax_t)(rm[0].rm_eo));
555 	else
556 		if (rp.re_nsub == 0)
557 			v = make_integer((intmax_t)0);
558 		else
559 			v = make_str("");
560 
561 	/* free arguments and pattern buffer */
562 	free_value(a);
563 	free_value(b);
564 	regfree(&rp);
565 
566 	return (v);
567 }
568