xref: /freebsd/bin/expr/expr.y (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf) 
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 
9 #include <sys/types.h>
10 
11 #include <ctype.h>
12 #include <err.h>
13 #include <errno.h>
14 #include <inttypes.h>
15 #include <limits.h>
16 #include <locale.h>
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <string.h>
20 #include <regex.h>
21 #include <unistd.h>
22 
23 /*
24  * POSIX specifies a specific error code for syntax errors.  We exit
25  * with this code for all errors.
26  */
27 #define	ERR_EXIT	2
28 
29 enum valtype {
30 	integer, numeric_string, string
31 } ;
32 
33 struct val {
34 	enum valtype type;
35 	union {
36 		char *s;
37 		intmax_t i;
38 	} u;
39 } ;
40 
41 char		**av;
42 int		nonposix;
43 struct val	*result;
44 
45 void		assert_to_integer(struct val *);
46 void		assert_div(intmax_t, intmax_t);
47 void		assert_minus(intmax_t, intmax_t, intmax_t);
48 void		assert_plus(intmax_t, intmax_t, intmax_t);
49 void		assert_times(intmax_t, intmax_t, intmax_t);
50 int		compare_vals(struct val *, struct val *);
51 void		free_value(struct val *);
52 int		is_integer(const char *);
53 int		is_string(struct val *);
54 int		is_zero_or_null(struct val *);
55 struct val	*make_integer(intmax_t);
56 struct val	*make_str(const char *);
57 struct val	*op_and(struct val *, struct val *);
58 struct val	*op_colon(struct val *, struct val *);
59 struct val	*op_div(struct val *, struct val *);
60 struct val	*op_eq(struct val *, struct val *);
61 struct val	*op_ge(struct val *, struct val *);
62 struct val	*op_gt(struct val *, struct val *);
63 struct val	*op_le(struct val *, struct val *);
64 struct val	*op_lt(struct val *, struct val *);
65 struct val	*op_minus(struct val *, struct val *);
66 struct val	*op_ne(struct val *, struct val *);
67 struct val	*op_or(struct val *, struct val *);
68 struct val	*op_plus(struct val *, struct val *);
69 struct val	*op_rem(struct val *, struct val *);
70 struct val	*op_times(struct val *, struct val *);
71 int		to_integer(struct val *);
72 void		to_string(struct val *);
73 int		yyerror(const char *);
74 int		yylex(void);
75 
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 
95 start: expr { result = $$; }
96 
97 expr:	TOKEN
98 	| '(' expr ')' { $$ = $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 struct val *
118 make_integer(intmax_t i)
119 {
120 	struct val *vp;
121 
122 	vp = (struct val *)malloc(sizeof(*vp));
123 	if (vp == NULL)
124 		errx(ERR_EXIT, "malloc() failed");
125 
126 	vp->type = integer;
127 	vp->u.i  = i;
128 	return (vp);
129 }
130 
131 struct val *
132 make_str(const char *s)
133 {
134 	struct val *vp;
135 
136 	vp = (struct val *)malloc(sizeof(*vp));
137 	if (vp == NULL || ((vp->u.s = strdup(s)) == NULL))
138 		errx(ERR_EXIT, "malloc() failed");
139 
140 	if (is_integer(s))
141 		vp->type = numeric_string;
142 	else
143 		vp->type = string;
144 
145 	return (vp);
146 }
147 
148 void
149 free_value(struct val *vp)
150 {
151 	if (vp->type == string || vp->type == numeric_string)
152 		free(vp->u.s);
153 }
154 
155 int
156 to_integer(struct val *vp)
157 {
158 	intmax_t i;
159 
160 	/* we can only convert numeric_string to integer, here */
161 	if (vp->type == numeric_string) {
162 		errno = 0;
163 		i  = strtoimax(vp->u.s, (char **)NULL, 10);
164 		/* just keep as numeric_string, if the conversion fails */
165 		if (errno != ERANGE) {
166 			free(vp->u.s);
167 			vp->u.i = i;
168 			vp->type = integer;
169 		}
170 	}
171 	return (vp->type == integer);
172 }
173 
174 void
175 assert_to_integer(struct val *vp)
176 {
177 	if (vp->type == string)
178 		errx(ERR_EXIT, "not a decimal number: '%s'", vp->u.s);
179 	if (!to_integer(vp))
180 		errx(ERR_EXIT, "operand too large: '%s'", vp->u.s);
181 }
182 
183 void
184 to_string(struct val *vp)
185 {
186 	char *tmp;
187 
188 	if (vp->type == string || vp->type == numeric_string)
189 		return;
190 
191 	/*
192 	 * log_10(x) ~= 0.3 * log_2(x).  Rounding up gives the number
193 	 * of digits; add one each for the sign and terminating null
194 	 * character, respectively.
195 	 */
196 #define	NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
197 	tmp = malloc(NDIGITS(vp->u.i));
198 	if (tmp == NULL)
199 		errx(ERR_EXIT, "malloc() failed");
200 
201 	sprintf(tmp, "%jd", vp->u.i);
202 	vp->type = string;
203 	vp->u.s  = tmp;
204 }
205 
206 int
207 is_integer(const char *s)
208 {
209 	if (nonposix) {
210 		if (*s == '\0')
211 			return (1);
212 		while (isspace((unsigned char)*s))
213 			s++;
214 	}
215 	if (*s == '-' || (nonposix && *s == '+'))
216 		s++;
217 	if (*s == '\0')
218 		return (0);
219 	while (isdigit((unsigned char)*s))
220 		s++;
221 	return (*s == '\0');
222 }
223 
224 int
225 is_string(struct val *vp)
226 {
227 	/* only TRUE if this string is not a valid integer */
228 	return (vp->type == string);
229 }
230 
231 int
232 yylex(void)
233 {
234 	char *p;
235 
236 	if (*av == NULL)
237 		return (0);
238 
239 	p = *av++;
240 
241 	if (strlen(p) == 1) {
242 		if (strchr("|&=<>+-*/%:()", *p))
243 			return (*p);
244 	} else if (strlen(p) == 2 && p[1] == '=') {
245 		switch (*p) {
246 		case '>': return (GE);
247 		case '<': return (LE);
248 		case '!': return (NE);
249 		}
250 	}
251 
252 	yylval.val = make_str(p);
253 	return (TOKEN);
254 }
255 
256 int
257 is_zero_or_null(struct val *vp)
258 {
259 	if (vp->type == integer)
260 		return (vp->u.i == 0);
261 
262 	return (*vp->u.s == 0 || (to_integer(vp) && vp->u.i == 0));
263 }
264 
265 int
266 main(int argc, char *argv[])
267 {
268 	int c;
269 
270 	setlocale(LC_ALL, "");
271 	if (getenv("EXPR_COMPAT") != NULL
272 	    || check_utility_compat("expr")) {
273 		av = argv + 1;
274 		nonposix = 1;
275 	} else {
276 		while ((c = getopt(argc, argv, "e")) != -1) {
277 			switch (c) {
278 			case 'e':
279 				nonposix = 1;
280 				break;
281 			default:
282 				errx(ERR_EXIT,
283 				    "usage: expr [-e] expression\n");
284 			}
285 		}
286 		av = argv + optind;
287 	}
288 
289 	yyparse();
290 
291 	if (result->type == integer)
292 		printf("%jd\n", result->u.i);
293 	else
294 		printf("%s\n", result->u.s);
295 
296 	return (is_zero_or_null(result));
297 }
298 
299 int
300 yyerror(const char *s __unused)
301 {
302 	errx(ERR_EXIT, "syntax error");
303 }
304 
305 struct val *
306 op_or(struct val *a, struct val *b)
307 {
308 	if (!is_zero_or_null(a)) {
309 		free_value(b);
310 		return (a);
311 	}
312 	free_value(a);
313 	if (!is_zero_or_null(b))
314 		return (b);
315 	free_value(b);
316 	return (make_integer((intmax_t)0));
317 }
318 
319 struct val *
320 op_and(struct val *a, struct val *b)
321 {
322 	if (is_zero_or_null(a) || is_zero_or_null(b)) {
323 		free_value(a);
324 		free_value(b);
325 		return (make_integer((intmax_t)0));
326 	} else {
327 		free_value(b);
328 		return (a);
329 	}
330 }
331 
332 int
333 compare_vals(struct val *a, struct val *b)
334 {
335 	int r;
336 
337 	if (is_string(a) || is_string(b)) {
338 		to_string(a);
339 		to_string(b);
340 		r = strcoll(a->u.s, b->u.s);
341 	} else {
342 		assert_to_integer(a);
343 		assert_to_integer(b);
344 		if (a->u.i > b->u.i)
345 			r = 1;
346 		else if (a->u.i < b->u.i)
347 			r = -1;
348 		else
349 			r = 0;
350 	}
351 
352 	free_value(a);
353 	free_value(b);
354 	return (r);
355 }
356 
357 struct val *
358 op_eq(struct val *a, struct val *b)
359 {
360 	return (make_integer((intmax_t)(compare_vals(a, b) == 0)));
361 }
362 
363 struct val *
364 op_gt(struct val *a, struct val *b)
365 {
366 	return (make_integer((intmax_t)(compare_vals(a, b) > 0)));
367 }
368 
369 struct val *
370 op_lt(struct val *a, struct val *b)
371 {
372 	return (make_integer((intmax_t)(compare_vals(a, b) < 0)));
373 }
374 
375 struct val *
376 op_ge(struct val *a, struct val *b)
377 {
378 	return (make_integer((intmax_t)(compare_vals(a, b) >= 0)));
379 }
380 
381 struct val *
382 op_le(struct val *a, struct val *b)
383 {
384 	return (make_integer((intmax_t)(compare_vals(a, b) <= 0)));
385 }
386 
387 struct val *
388 op_ne(struct val *a, struct val *b)
389 {
390 	return (make_integer((intmax_t)(compare_vals(a, b) != 0)));
391 }
392 
393 void
394 assert_plus(intmax_t a, intmax_t b, intmax_t r)
395 {
396 	/*
397 	 * sum of two positive numbers must be positive,
398 	 * sum of two negative numbers must be negative
399 	 */
400 	if ((a > 0 && b > 0 && r <= 0) ||
401 	    (a < 0 && b < 0 && r >= 0))
402 		errx(ERR_EXIT, "overflow");
403 }
404 
405 struct val *
406 op_plus(struct val *a, struct val *b)
407 {
408 	struct val *r;
409 
410 	assert_to_integer(a);
411 	assert_to_integer(b);
412 	r = make_integer(a->u.i + b->u.i);
413 	assert_plus(a->u.i, b->u.i, r->u.i);
414 
415 	free_value(a);
416 	free_value(b);
417 	return (r);
418 }
419 
420 void
421 assert_minus(intmax_t a, intmax_t b, intmax_t r)
422 {
423 	if ((a >= 0 && b < 0 && r <= 0) ||
424 	    (a < 0 && b > 0 && r >= 0))
425 		errx(ERR_EXIT, "overflow");
426 }
427 
428 struct val *
429 op_minus(struct val *a, struct val *b)
430 {
431 	struct val *r;
432 
433 	assert_to_integer(a);
434 	assert_to_integer(b);
435 	r = make_integer(a->u.i - b->u.i);
436 	assert_minus(a->u.i, b->u.i, r->u.i);
437 
438 	free_value(a);
439 	free_value(b);
440 	return (r);
441 }
442 
443 /*
444  * We depend on undefined behaviour giving a result (in r).
445  * To test this result, pass it as volatile.  This prevents
446  * optimizing away of the test based on the undefined behaviour.
447  */
448 void
449 assert_times(intmax_t a, intmax_t b, volatile intmax_t r)
450 {
451 	/*
452 	 * If the first operand is 0, no overflow is possible,
453 	 * else the result of the division test must match the
454 	 * second operand.
455 	 *
456 	 * Be careful to avoid overflow in the overflow test, as
457 	 * in assert_div().  Overflow in division would kill us
458 	 * with a SIGFPE before getting the test wrong.  In old
459 	 * buggy versions, optimization used to give a null test
460 	 * instead of a SIGFPE.
461 	 */
462 	if ((a == -1 && b == INTMAX_MIN) || (a != 0 && r / a != b))
463 		errx(ERR_EXIT, "overflow");
464 }
465 
466 struct val *
467 op_times(struct val *a, struct val *b)
468 {
469 	struct val *r;
470 
471 	assert_to_integer(a);
472 	assert_to_integer(b);
473 	r = make_integer(a->u.i * b->u.i);
474 	assert_times(a->u.i, b->u.i, r->u.i);
475 
476 	free_value(a);
477 	free_value(b);
478 	return (r);
479 }
480 
481 void
482 assert_div(intmax_t a, intmax_t b)
483 {
484 	if (b == 0)
485 		errx(ERR_EXIT, "division by zero");
486 	/* only INTMAX_MIN / -1 causes overflow */
487 	if (a == INTMAX_MIN && b == -1)
488 		errx(ERR_EXIT, "overflow");
489 }
490 
491 struct val *
492 op_div(struct val *a, struct val *b)
493 {
494 	struct val *r;
495 
496 	assert_to_integer(a);
497 	assert_to_integer(b);
498 	/* assert based on operands only, not on result */
499 	assert_div(a->u.i, b->u.i);
500 	r = make_integer(a->u.i / b->u.i);
501 
502 	free_value(a);
503 	free_value(b);
504 	return (r);
505 }
506 
507 struct val *
508 op_rem(struct val *a, struct val *b)
509 {
510 	struct val *r;
511 
512 	assert_to_integer(a);
513 	assert_to_integer(b);
514 	/* pass a=1 to only check for div by zero */
515 	assert_div(1, b->u.i);
516 	r = make_integer(a->u.i % b->u.i);
517 
518 	free_value(a);
519 	free_value(b);
520 	return (r);
521 }
522 
523 struct val *
524 op_colon(struct val *a, struct val *b)
525 {
526 	regex_t rp;
527 	regmatch_t rm[2];
528 	char errbuf[256];
529 	int eval;
530 	struct val *v;
531 
532 	/* coerce both arguments to strings */
533 	to_string(a);
534 	to_string(b);
535 
536 	/* compile regular expression */
537 	if ((eval = regcomp(&rp, b->u.s, 0)) != 0) {
538 		regerror(eval, &rp, errbuf, sizeof(errbuf));
539 		errx(ERR_EXIT, "%s", errbuf);
540 	}
541 
542 	/* compare string against pattern */
543 	/* remember that patterns are anchored to the beginning of the line */
544 	if (regexec(&rp, a->u.s, (size_t)2, rm, 0) == 0 && rm[0].rm_so == 0)
545 		if (rm[1].rm_so >= 0) {
546 			*(a->u.s + rm[1].rm_eo) = '\0';
547 			v = make_str(a->u.s + rm[1].rm_so);
548 
549 		} else
550 			v = make_integer((intmax_t)(rm[0].rm_eo));
551 	else
552 		if (rp.re_nsub == 0)
553 			v = make_integer((intmax_t)0);
554 		else
555 			v = make_str("");
556 
557 	/* free arguments and pattern buffer */
558 	free_value(a);
559 	free_value(b);
560 	regfree(&rp);
561 
562 	return (v);
563 }
564