expr.y revision 1.39
1 /* $NetBSD: expr.y,v 1.39 2016/09/05 01:00:07 sevan 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> and J.T. Conklin <jtc (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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 %{ 33 #include <sys/cdefs.h> 34 #ifndef lint 35 __RCSID("$NetBSD: expr.y,v 1.39 2016/09/05 01:00:07 sevan Exp $"); 36 #endif /* not lint */ 37 38 #include <sys/types.h> 39 40 #include <err.h> 41 #include <errno.h> 42 #include <limits.h> 43 #include <locale.h> 44 #include <regex.h> 45 #include <stdarg.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 50 static const char * const *av; 51 52 static void yyerror(const char *, ...) __dead; 53 static int yylex(void); 54 static int is_zero_or_null(const char *); 55 static int is_integer(const char *); 56 static int64_t perform_arith_op(const char *, const char *, const char *); 57 58 #define YYSTYPE const char * 59 60 %} 61 %token STRING 62 %left SPEC_OR 63 %left SPEC_AND 64 %left COMPARE 65 %left ADD_SUB_OPERATOR 66 %left MUL_DIV_MOD_OPERATOR 67 %left SPEC_REG 68 %left LENGTH 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 $$ = "0"; 101 } 102 | expr SPEC_REG expr = { 103 /* 104 * The ``:'' operator matches first expr against the second, 105 * which must be a regular expression. 106 */ 107 regex_t rp; 108 regmatch_t rm[2]; 109 int eval; 110 111 /* compile regular expression */ 112 if ((eval = regcomp(&rp, $3, REG_BASIC)) != 0) { 113 char errbuf[256]; 114 (void)regerror(eval, &rp, errbuf, sizeof(errbuf)); 115 yyerror("%s", errbuf); 116 /* NOT REACHED */ 117 } 118 119 /* compare string against pattern -- remember that patterns 120 are anchored to the beginning of the line */ 121 if (regexec(&rp, $1, 2, rm, 0) == 0 && rm[0].rm_so == 0) { 122 char *val; 123 if (rm[1].rm_so >= 0) { 124 (void) asprintf(&val, "%.*s", 125 (int) (rm[1].rm_eo - rm[1].rm_so), 126 $1 + rm[1].rm_so); 127 } else { 128 (void) asprintf(&val, "%d", 129 (int)(rm[0].rm_eo - rm[0].rm_so)); 130 } 131 if (val == NULL) 132 err(1, NULL); 133 $$ = val; 134 } else { 135 if (rp.re_nsub == 0) { 136 $$ = "0"; 137 } else { 138 $$ = ""; 139 } 140 } 141 142 } 143 | expr ADD_SUB_OPERATOR expr = { 144 /* Returns the results of addition, subtraction */ 145 char *val; 146 int64_t res; 147 148 res = perform_arith_op($1, $2, $3); 149 (void) asprintf(&val, "%lld", (long long int) res); 150 if (val == NULL) 151 err(1, NULL); 152 $$ = val; 153 } 154 155 | expr MUL_DIV_MOD_OPERATOR expr = { 156 /* 157 * Returns the results of multiply, divide or remainder of 158 * numeric-valued arguments. 159 */ 160 char *val; 161 int64_t res; 162 163 res = perform_arith_op($1, $2, $3); 164 (void) asprintf(&val, "%lld", (long long int) res); 165 if (val == NULL) 166 err(1, NULL); 167 $$ = val; 168 169 } 170 | expr COMPARE expr = { 171 /* 172 * Returns the results of integer comparison if both arguments 173 * are integers; otherwise, returns the results of string 174 * comparison using the locale-specific collation sequence. 175 * The result of each comparison is 1 if the specified relation 176 * is true, or 0 if the relation is false. 177 */ 178 179 int64_t l, r; 180 int res; 181 182 res = 0; 183 184 /* 185 * Slight hack to avoid differences in the compare code 186 * between string and numeric compare. 187 */ 188 if (is_integer($1) && is_integer($3)) { 189 /* numeric comparison */ 190 l = strtoll($1, NULL, 10); 191 r = strtoll($3, NULL, 10); 192 } else { 193 /* string comparison */ 194 l = strcoll($1, $3); 195 r = 0; 196 } 197 198 switch($2[0]) { 199 case '=': /* equal */ 200 res = (l == r); 201 break; 202 case '>': /* greater or greater-equal */ 203 if ($2[1] == '=') 204 res = (l >= r); 205 else 206 res = (l > r); 207 break; 208 case '<': /* lower or lower-equal */ 209 if ($2[1] == '=') 210 res = (l <= r); 211 else 212 res = (l < r); 213 break; 214 case '!': /* not equal */ 215 /* the check if this is != was done in yylex() */ 216 res = (l != r); 217 } 218 219 $$ = (res) ? "1" : "0"; 220 221 } 222 | LEFT_PARENT expr RIGHT_PARENT { $$ = $2; } 223 | LENGTH expr { 224 /* 225 * Return length of 'expr' in bytes. 226 */ 227 char *ln; 228 229 asprintf(&ln, "%ld", (long) strlen($2)); 230 if (ln == NULL) 231 err(1, NULL); 232 $$ = ln; 233 } 234 ; 235 236 item: STRING 237 | ADD_SUB_OPERATOR 238 | MUL_DIV_MOD_OPERATOR 239 | COMPARE 240 | SPEC_OR 241 | SPEC_AND 242 | SPEC_REG 243 | LENGTH 244 ; 245 %% 246 247 /* 248 * Returns 1 if the string is empty or contains only numeric zero. 249 */ 250 static int 251 is_zero_or_null(const char *str) 252 { 253 char *endptr; 254 255 return str[0] == '\0' 256 || ( strtoll(str, &endptr, 10) == 0LL 257 && endptr[0] == '\0'); 258 } 259 260 /* 261 * Returns 1 if the string is an integer. 262 */ 263 static int 264 is_integer(const char *str) 265 { 266 char *endptr; 267 268 (void) strtoll(str, &endptr, 10); 269 /* note we treat empty string as valid number */ 270 return (endptr[0] == '\0'); 271 } 272 273 static int64_t 274 perform_arith_op(const char *left, const char *op, const char *right) 275 { 276 int64_t res, sign, l, r; 277 u_int64_t temp; 278 279 res = 0; 280 281 if (!is_integer(left)) { 282 yyerror("non-integer argument '%s'", left); 283 /* NOTREACHED */ 284 } 285 if (!is_integer(right)) { 286 yyerror("non-integer argument '%s'", right); 287 /* NOTREACHED */ 288 } 289 290 errno = 0; 291 l = strtoll(left, NULL, 10); 292 if (errno == ERANGE) { 293 yyerror("value '%s' is %s is %lld", left, 294 (l > 0) ? "too big, maximum" : "too small, minimum", 295 (l > 0) ? LLONG_MAX : LLONG_MIN); 296 /* NOTREACHED */ 297 } 298 299 errno = 0; 300 r = strtoll(right, NULL, 10); 301 if (errno == ERANGE) { 302 yyerror("value '%s' is %s is %lld", right, 303 (l > 0) ? "too big, maximum" : "too small, minimum", 304 (l > 0) ? LLONG_MAX : LLONG_MIN); 305 /* NOTREACHED */ 306 } 307 308 switch(op[0]) { 309 case '+': 310 /* 311 * Do the op into an unsigned to avoid overflow and then cast 312 * back to check the resulting signage. 313 */ 314 temp = l + r; 315 res = (int64_t) temp; 316 /* very simplistic check for over-& underflow */ 317 if ((res < 0 && l > 0 && r > 0) 318 || (res > 0 && l < 0 && r < 0)) 319 yyerror("integer overflow or underflow occurred for " 320 "operation '%s %s %s'", left, op, right); 321 break; 322 case '-': 323 /* 324 * Do the op into an unsigned to avoid overflow and then cast 325 * back to check the resulting signage. 326 */ 327 temp = l - r; 328 res = (int64_t) temp; 329 /* very simplistic check for over-& underflow */ 330 if ((res < 0 && l > 0 && l > r) 331 || (res > 0 && l < 0 && l < r) ) 332 yyerror("integer overflow or underflow occurred for " 333 "operation '%s %s %s'", left, op, right); 334 break; 335 case '/': 336 if (r == 0) 337 yyerror("second argument to '%s' must not be zero", op); 338 res = l / r; 339 340 break; 341 case '%': 342 if (r == 0) 343 yyerror("second argument to '%s' must not be zero", op); 344 res = l % r; 345 break; 346 case '*': 347 /* shortcut */ 348 if ((l == 0) || (r == 0)) { 349 res = 0; 350 break; 351 } 352 353 sign = 1; 354 if (l < 0) 355 sign *= -1; 356 if (r < 0) 357 sign *= -1; 358 359 res = l * r; 360 /* 361 * XXX: not the most portable but works on anything with 2's 362 * complement arithmetic. If the signs don't match or the 363 * result was 0 on 2's complement this overflowed. 364 */ 365 if ((res < 0 && sign > 0) || (res > 0 && sign < 0) || 366 (res == 0)) 367 yyerror("integer overflow or underflow occurred for " 368 "operation '%s %s %s'", left, op, right); 369 /* NOTREACHED */ 370 break; 371 } 372 return res; 373 } 374 375 static const char *x = "|&=<>+-*/%:()"; 376 static const int x_token[] = { 377 SPEC_OR, SPEC_AND, COMPARE, COMPARE, COMPARE, ADD_SUB_OPERATOR, 378 ADD_SUB_OPERATOR, MUL_DIV_MOD_OPERATOR, MUL_DIV_MOD_OPERATOR, 379 MUL_DIV_MOD_OPERATOR, SPEC_REG, LEFT_PARENT, RIGHT_PARENT 380 }; 381 382 static int handle_ddash = 1; 383 384 int 385 yylex(void) 386 { 387 const char *p = *av++; 388 int retval; 389 390 if (!p) 391 retval = 0; 392 else if (p[1] == '\0') { 393 const char *w = strchr(x, p[0]); 394 if (w) { 395 retval = x_token[w-x]; 396 } else { 397 retval = STRING; 398 } 399 } else if (p[1] == '=' && p[2] == '\0' 400 && (p[0] == '>' || p[0] == '<' || p[0] == '!')) 401 retval = COMPARE; 402 else if (handle_ddash && p[0] == '-' && p[1] == '-' && p[2] == '\0') { 403 /* ignore "--" if passed as first argument and isn't followed 404 * by another STRING */ 405 retval = yylex(); 406 if (retval != STRING && retval != LEFT_PARENT 407 && retval != RIGHT_PARENT) { 408 /* is not followed by string or parenthesis, use as 409 * STRING */ 410 retval = STRING; 411 av--; /* was increased in call to yylex() above */ 412 p = "--"; 413 } else { 414 /* "--" is to be ignored */ 415 p = yylval; 416 } 417 } else if (strcmp(p, "length") == 0) 418 retval = LENGTH; 419 else 420 retval = STRING; 421 422 handle_ddash = 0; 423 yylval = p; 424 425 return retval; 426 } 427 428 /* 429 * Print error message and exit with error 2 (syntax error). 430 */ 431 static __printflike(1, 2) void 432 yyerror(const char *fmt, ...) 433 { 434 va_list arg; 435 436 va_start(arg, fmt); 437 verrx(2, fmt, arg); 438 va_end(arg); 439 } 440 441 int 442 main(int argc, const char * const *argv) 443 { 444 setprogname(argv[0]); 445 (void)setlocale(LC_ALL, ""); 446 447 if (argc == 1) { 448 (void)fprintf(stderr, "usage: %s expression\n", 449 getprogname()); 450 exit(2); 451 } 452 453 av = argv + 1; 454 455 exit(yyparse()); 456 /* NOTREACHED */ 457 } 458
Indexes created Wed Oct 01 15:09:59 GMT 2025