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expr.y revision 1.20 
      1 /* $NetBSD: expr.y,v 1.20 2000/10/26 23:10:21 jdolecek Exp $ */
      2 
      3 /*_
      4  * Copyright (c) 2000 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jaromir Dolecek <jdolecek (at) NetBSD.org>.
      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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *      This product includes software developed by the NetBSD
     21  *      Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 
     38 %{
     39 #include <sys/cdefs.h>
     40 #ifndef lint
     41 __RCSID("$NetBSD: expr.y,v 1.20 2000/10/26 23:10:21 jdolecek Exp $");
     42 #endif /* not lint */
     43 
     44 #include <sys/types.h>
     45 #include <err.h>
     46 #include <errno.h>
     47 #include <limits.h>
     48 #include <locale.h>
     49 #include <regex.h>
     50 #include <stdarg.h>
     51 #include <stdio.h>
     52 #include <stdlib.h>
     53 #include <string.h>
     54 
     55 const char **av;
     56 
     57 static void yyerror(const char *, ...);
     58 static int yylex(void);
     59 static int is_zero_or_null(const char *);
     60 static int is_integer(const char *);
     61 static int yyparse(void);
     62 
     63 #define YYSTYPE	const char *
     64 
     65 %}
     66 %token STRING
     67 %left SPEC_OR SPEC_AND
     68 %left COMPARE ARITH_OPERATOR SPEC_REG
     69 %left LEFT_PARENT RIGHT_PARENT
     70 
     71 %%
     72 
     73 exp:	expr = {
     74 		(void) printf("%s\n", $1);
     75 		return (is_zero_or_null($1));
     76 		}
     77 	;
     78 
     79 expr:	item	{ $$ = $1; }
     80 	| expr SPEC_OR expr = {
     81 		/*
     82 		 * Return evaluation of first expression if it is neither
     83 		 * an empty string nor zero; otherwise, returns the evaluation
     84 		 * of second expression.
     85 		 */
     86 		if (!is_zero_or_null($1))
     87 			$$ = $1;
     88 		else
     89 			$$ = $3;
     90 		}
     91 	| expr SPEC_AND expr = {
     92 		/*
     93 		 * Returns the evaluation of first expr if neither expression
     94 		 * evaluates to an empty string or zero; otherwise, returns
     95 		 * zero.
     96 		 */
     97 		if (!is_zero_or_null($1) && !is_zero_or_null($3))
     98 			$$ = $1;
     99 		else
    100 			$$ = "0";
    101 		}
    102 	| expr SPEC_REG expr = {
    103 		/*
    104 		 * The ``:'' operator matches first expr against the second,
    105 		 * which must be a regular expression.
    106 		 */
    107 		regex_t rp;
    108 		regmatch_t rm[2];
    109 		int eval;
    110 
    111 		/* compile regular expression */
    112 		if ((eval = regcomp(&rp, $3, 0)) != 0) {
    113 			char errbuf[256];
    114 			(void)regerror(eval, &rp, errbuf, sizeof(errbuf));
    115 			yyerror("%s", errbuf);
    116 			/* NOT REACHED */
    117 		}
    118 
    119 		/* compare string against pattern --  remember that patterns
    120 		   are anchored to the beginning of the line */
    121 		if (regexec(&rp, $1, 2, rm, 0) == 0 && rm[0].rm_so == 0) {
    122 			char *val;
    123 			if (rm[1].rm_so >= 0) {
    124 				(void) asprintf(&val, "%.*s",
    125 					(int) (rm[1].rm_eo - rm[1].rm_so),
    126 					$1 + rm[1].rm_so);
    127 			} else {
    128 				(void) asprintf(&val, "%d",
    129 					(int)(rm[0].rm_eo - rm[0].rm_so));
    130 			}
    131 			$$ = val;
    132 		} else {
    133 			if (rp.re_nsub == 0) {
    134 				$$ = "0";
    135 			} else {
    136 				$$ = "";
    137 			}
    138 		}
    139 
    140 		}
    141 	| expr ARITH_OPERATOR expr = {
    142 		/*
    143 		 * Returns the results of multiplication, division,
    144 		 * addition, subtraction, remainder of numeric-valued arguments.
    145 		 */
    146 		char *val;
    147 		int64_t res, l, r;
    148 
    149 		if (!is_integer($1)) {
    150 			yyerror("non-integer argument '%s'", $1);
    151 			/* NOTREACHED */
    152 		}
    153 		if (!is_integer($3)) {
    154 			yyerror("non-integer argument '%s'", $3);
    155 			/* NOTREACHED */
    156 		}
    157 
    158 		errno = 0;
    159 		l = strtoll($1, NULL, 10);
    160 		if (errno == ERANGE) {
    161 			yyerror("value '%s' is %s is %lld", $1,
    162 				(l > 0)
    163 				? "too big, maximum" : "too small, minimum",
    164 				(l > 0) ? LLONG_MAX : LLONG_MIN
    165 			);
    166 			/* NOTREACHED */
    167 		}
    168 
    169 		errno = 0;
    170 		r = strtoll($3, NULL, 10);
    171 		if (errno == ERANGE) {
    172 			yyerror("value '%s' is %s is %lld", $3,
    173 				(l > 0)
    174 				? "too big, maximum" : "too small, minimum",
    175 				(l > 0) ? LLONG_MAX : LLONG_MIN
    176 			);
    177 			/* NOTREACHED */
    178 		}
    179 
    180 		switch($2[0]) {
    181 		case '+':
    182 			res = l + r;
    183 			/* very simplistic check for over-& underflow */
    184 			if ((res < 0 && l > 0 && r > 0 && l > r)
    185 				|| (res > 0 && l < 0 && r < 0 && l < r)) {
    186 				yyerror("integer overflow or underflow occured\
    187  for operation '%s %s %s'", $1, $2, $3);
    188 				/* NOTREACHED */
    189 			}
    190 			break;
    191 		case '-':
    192 			res = l - r;
    193 			/* very simplistic check for over-& underflow */
    194 			if ((res < 0 && l > 0 && l > r)
    195 				|| (res > 0 && l < 0 && l < r) ) {
    196 				yyerror("integer overflow or underflow occured\
    197  for operation '%s %s %s'", $1, $2, $3);
    198 				/* NOTREACHED */
    199 			}
    200 			break;
    201 		case '/':
    202 			if (r == 0) {
    203 				yyerror("second argument to '%s' must not be\
    204  zero", $2);
    205 				/* NOTREACHED */
    206 			}
    207 			res = l / r;
    208 
    209 			break;
    210 		case '%':
    211 			if (r == 0) {
    212 				yyerror("second argument to '%s' must not be zero", $2);
    213 				/* NOTREACHED */
    214 			}
    215 			res = l % r;
    216 			break;
    217 		case '*':
    218 			if (r == 0) {
    219 				res = 0;
    220 				break;
    221 			}
    222 
    223 			/* check if the result would over- or underflow */
    224 			if ((l > 0 && l > (LLONG_MAX / r))
    225 				|| (l < 0 && l < (LLONG_MIN / r))) {
    226 				yyerror("operation '%s %s %s' would cause over-\
    227  or underflow",
    228 					$1, $2, $3);
    229 				/* NOTREACHED */
    230 			}
    231 
    232 			res = l * r;
    233 			break;
    234 		}
    235 
    236 		(void) asprintf(&val, "%lld", (long long int) res);
    237 		$$ = val;
    238 
    239 		}
    240 	| expr COMPARE expr = {
    241 		/*
    242 		 * Returns the results of integer comparison if both arguments
    243 		 * are integers; otherwise, returns the results of string
    244 		 * comparison using the locale-specific collation sequence.
    245 		 * The result of each comparison is 1 if the specified relation
    246 		 * is true, or 0 if the relation is false.
    247 		 */
    248 
    249 		int64_t l, r;
    250 		int res;
    251 
    252 		/*
    253 		 * Slight hack to avoid differences in the compare code
    254 		 * between string and numeric compare.
    255 		 */
    256 		if (is_integer($1) && is_integer($3)) {
    257 			/* numeric comparison */
    258 			l = strtoll($1, NULL, 10);
    259 			r = strtoll($3, NULL, 10);
    260 		} else {
    261 			/* string comparison */
    262 			l = strcoll($1, $3);
    263 			r = 0;
    264 		}
    265 
    266 		switch($2[0]) {
    267 		case '=': /* equal */
    268 			res = (l == r);
    269 			break;
    270 		case '>': /* greater or greater-equal */
    271 			if ($2[1] == '=')
    272 				res = (l >= r);
    273 			else
    274 				res = (l > r);
    275 			break;
    276 		case '<': /* lower or lower-equal */
    277 			if ($2[1] == '=')
    278 				res = (l <= r);
    279 			else
    280 				res = (l < r);
    281 			break;
    282 		case '!': /* not equal */
    283 			/* the check if this is != was done in yylex() */
    284 			res = (l != r);
    285 		}
    286 
    287 		$$ = (res) ? "1" : "0";
    288 
    289 		}
    290 	| LEFT_PARENT expr RIGHT_PARENT { $$ = $2; }
    291 	;
    292 
    293 item:	STRING
    294 	| ARITH_OPERATOR
    295 	| COMPARE
    296 	| SPEC_OR
    297 	| SPEC_AND
    298 	| SPEC_REG
    299 	;
    300 %%
    301 
    302 /*
    303  * Returns 1 if the string is empty or contains only numeric zero.
    304  */
    305 static int
    306 is_zero_or_null(const char *str)
    307 {
    308 	char *endptr;
    309 
    310 	return str[0] == '\0'
    311 		|| ( strtoll(str, &endptr, 10) == 0LL
    312 			&& endptr[0] == '\0');
    313 }
    314 
    315 /*
    316  * Returns 1 if the string is an integer.
    317  */
    318 static int
    319 is_integer(const char *str)
    320 {
    321 	char *endptr;
    322 
    323 	(void) strtoll(str, &endptr, 10);
    324 	/* note we treat empty string as valid number */
    325 	return (endptr[0] == '\0');
    326 }
    327 
    328 
    329 const char *x = "|&=<>+-*/%:()";
    330 const int x_token[] = {
    331 	SPEC_OR, SPEC_AND, COMPARE, COMPARE, COMPARE, ARITH_OPERATOR,
    332 	ARITH_OPERATOR, ARITH_OPERATOR, ARITH_OPERATOR, ARITH_OPERATOR,
    333 	SPEC_REG, LEFT_PARENT, RIGHT_PARENT
    334 };
    335 
    336 int
    337 yylex(void)
    338 {
    339 	const char *p = *av++;
    340 	int retval = 0;
    341 
    342 	if (!p) {
    343 		return 0;
    344 	}
    345 
    346 	if (p[1] == '\0') {
    347 		const char *w = strchr(x, p[0]);
    348 		if (w) {
    349 			retval = x_token[w-x];
    350 		} else {
    351 			retval = STRING;
    352 		}
    353 	} else if (p[1] == '=' && p[2] == '\0'
    354 			&& (p[0] == '>' || p[0] == '<' || p[0] == '!'))
    355 		retval = COMPARE;
    356 	else
    357 		retval = STRING;
    358 
    359 	yylval = p;
    360 
    361 	return retval;
    362 }
    363 
    364 /*
    365  * Print error message and exit with error 2 (syntax error).
    366  */
    367 static void
    368 yyerror(const char *fmt, ...)
    369 {
    370 	va_list arg;
    371 
    372 	va_start(arg, fmt);
    373 	verrx(2, fmt, arg);
    374 	va_end(arg);
    375 }
    376 
    377 int
    378 main(int argc, const char **argv)
    379 {
    380 	(void) setlocale(LC_ALL, "");
    381 
    382 	if (argc == 1) {
    383 		(void) fprintf(stderr, "usage: expr expression\n");
    384 		exit(2);
    385 	}
    386 
    387 	av = argv + 1;
    388 
    389 	exit(yyparse());
    390 	/* NOTREACHED */
    391 }
    392