shell_cmds/expr/expr.y

   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: src/bin/expr/expr.y,v 1.28 2011/07/09 12:20:15 se Exp $
   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 int             yyparse(void);
  78
  79 %}
  80
  81 %union
  82 {
  83         struct val *val;
  84 }
  85
  86 %left <val> '|'
  87 %left <val> '&'
  88 %left <val> '=' '>' '<' GE LE NE
  89 %left <val> '+' '-'
  90 %left <val> '*' '/' '%'
  91 %left <val> ':'
  92
  93 %token <val> TOKEN
  94 %type <val> start expr
  95
  96 %%
  97
  98 start: expr { result = $$; }
  99
 100 expr:   TOKEN
 101         | '(' expr ')' { $$ = $2; }
 102         | expr '|' expr { $$ = op_or($1, $3); }
 103         | expr '&' expr { $$ = op_and($1, $3); }
 104         | expr '=' expr { $$ = op_eq($1, $3); }
 105         | expr '>' expr { $$ = op_gt($1, $3); }
 106         | expr '<' expr { $$ = op_lt($1, $3); }
 107         | expr GE expr  { $$ = op_ge($1, $3); }
 108         | expr LE expr  { $$ = op_le($1, $3); }
 109         | expr NE expr  { $$ = op_ne($1, $3); }
 110         | expr '+' expr { $$ = op_plus($1, $3); }
 111         | expr '-' expr { $$ = op_minus($1, $3); }
 112         | expr '*' expr { $$ = op_times($1, $3); }
 113         | expr '/' expr { $$ = op_div($1, $3); }
 114         | expr '%' expr { $$ = op_rem($1, $3); }
 115         | expr ':' expr { $$ = op_colon($1, $3); }
 116         ;
 117
 118 %%
 119
 120 struct val *
 121 make_integer(intmax_t i)
 122 {
 123         struct val *vp;
 124
 125         vp = (struct val *)malloc(sizeof(*vp));
 126         if (vp == NULL)
 127                 errx(ERR_EXIT, "malloc() failed");
 128
 129         vp->type = integer;
 130         vp->u.i  = i;
 131         return (vp);
 132 }
 133
 134 struct val *
 135 make_str(const char *s)
 136 {
 137         struct val *vp;
 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         if (is_integer(s))
 144                 vp->type = numeric_string;
 145         else
 146                 vp->type = string;
 147
 148         return (vp);
 149 }
 150
 151 void
 152 free_value(struct val *vp)
 153 {
 154         if (vp->type == string || vp->type == numeric_string)
 155                 free(vp->u.s);
 156 }
 157
 158 int
 159 to_integer(struct val *vp)
 160 {
 161         intmax_t i;
 162
 163         /* we can only convert numeric_string to integer, here */
 164         if (vp->type == numeric_string) {
 165                 errno = 0;
 166                 i  = strtoimax(vp->u.s, (char **)NULL, 10);
 167                 /* just keep as numeric_string, if the conversion fails */
 168                 if (errno != ERANGE) {
 169                         free(vp->u.s);
 170                         vp->u.i = i;
 171                         vp->type = integer;
 172                 }
 173         }
 174         return (vp->type == integer);
 175 }
 176
 177 void
 178 assert_to_integer(struct val *vp)
 179 {
 180         if (vp->type == string)
 181                 errx(ERR_EXIT, "not a decimal number: '%s'", vp->u.s);
 182         if (!to_integer(vp))
 183                 errx(ERR_EXIT, "operand too large: '%s'", vp->u.s);
 184 }
 185
 186 void
 187 to_string(struct val *vp)
 188 {
 189         char *tmp;
 190
 191         if (vp->type == string || vp->type == numeric_string)
 192                 return;
 193
 194         /*
 195          * log_10(x) ~= 0.3 * log_2(x).  Rounding up gives the number
 196          * of digits; add one each for the sign and terminating null
 197          * character, respectively.
 198          */
 199 #define NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
 200         tmp = malloc(NDIGITS(vp->u.i));
 201         if (tmp == NULL)
 202                 errx(ERR_EXIT, "malloc() failed");
 203
 204         sprintf(tmp, "%jd", vp->u.i);
 205         vp->type = string;
 206         vp->u.s  = tmp;
 207 }
 208
 209 int
 210 is_integer(const char *s)
 211 {
 212         if (nonposix) {
 213                 if (*s == '\0')
 214                         return (1);
 215                 while (isspace((unsigned char)*s))
 216                         s++;
 217         }
 218         if (*s == '-' || (nonposix && *s == '+'))
 219                 s++;
 220         if (*s == '\0')
 221                 return (0);
 222         while (isdigit((unsigned char)*s))
 223                 s++;
 224         return (*s == '\0');
 225 }
 226
 227 int
 228 is_string(struct val *vp)
 229 {
 230         /* only TRUE if this string is not a valid integer */
 231         return (vp->type == string);
 232 }
 233
 234 int
 235 yylex(void)
 236 {
 237         char *p;
 238
 239         if (*av == NULL)
 240                 return (0);
 241
 242         p = *av++;
 243
 244         if (strlen(p) == 1) {
 245                 if (strchr("|&=<>+-*/%:()", *p))
 246                         return (*p);
 247         } else if (strlen(p) == 2 && p[1] == '=') {
 248                 switch (*p) {
 249                 case '>': return (GE);
 250                 case '<': return (LE);
 251                 case '!': return (NE);
 252                 }
 253         }
 254
 255         yylval.val = make_str(p);
 256         return (TOKEN);
 257 }
 258
 259 int
 260 is_zero_or_null(struct val *vp)
 261 {
 262         if (vp->type == integer)
 263                 return (vp->u.i == 0);
 264
 265         return (*vp->u.s == 0 || (to_integer(vp) && vp->u.i == 0));
 266 }
 267
 268 int
 269 main(int argc, char *argv[])
 270 {
 271 #ifndef __APPLE__
 272         int c;
 273 #endif
 274
 275         setlocale(LC_ALL, "");
 276 #ifdef __APPLE__
 277         av = argv + 1;
 278         if (*av && !strcmp(*av, "--"))
 279                 av++;
 280 #else
 281         if (getenv("EXPR_COMPAT") != NULL
 282             || check_utility_compat("expr")) {
 283                 av = argv + 1;
 284                 nonposix = 1;
 285         } else {
 286                 while ((c = getopt(argc, argv, "e")) != -1) {
 287                         switch (c) {
 288                         case 'e':
 289                                 nonposix = 1;
 290                                 break;
 291                         default:
 292                                 errx(ERR_EXIT,
 293                                     "usage: expr [-e] expression\n");
 294                         }
 295                 }
 296                 av = argv + optind;
 297         }
 298 #endif
 299
 300         yyparse();
 301
 302 #ifdef __APPLE__
 303         if (to_integer(result))
 304 #else
 305         if (result->type == integer)
 306 #endif
 307                 printf("%jd\n", result->u.i);
 308         else
 309                 printf("%s\n", result->u.s);
 310
 311         return (is_zero_or_null(result));
 312 }
 313
 314 int
 315 yyerror(const char *s __unused)
 316 {
 317         errx(ERR_EXIT, "syntax error");
 318 }
 319
 320 struct val *
 321 op_or(struct val *a, struct val *b)
 322 {
 323         if (!is_zero_or_null(a)) {
 324                 free_value(b);
 325                 return (a);
 326         }
 327         free_value(a);
 328         if (!is_zero_or_null(b))
 329                 return (b);
 330         free_value(b);
 331         return (make_integer((intmax_t)0));
 332 }
 333
 334 struct val *
 335 op_and(struct val *a, struct val *b)
 336 {
 337         if (is_zero_or_null(a) || is_zero_or_null(b)) {
 338                 free_value(a);
 339                 free_value(b);
 340                 return (make_integer((intmax_t)0));
 341         } else {
 342                 free_value(b);
 343                 return (a);
 344         }
 345 }
 346
 347 int
 348 compare_vals(struct val *a, struct val *b)
 349 {
 350         int r;
 351
 352         if (is_string(a) || is_string(b)) {
 353                 to_string(a);
 354                 to_string(b);
 355                 r = strcoll(a->u.s, b->u.s);
 356         } else {
 357                 assert_to_integer(a);
 358                 assert_to_integer(b);
 359                 if (a->u.i > b->u.i)
 360                         r = 1;
 361                 else if (a->u.i < b->u.i)
 362                         r = -1;
 363                 else
 364                         r = 0;
 365         }
 366
 367         free_value(a);
 368         free_value(b);
 369         return (r);
 370 }
 371
 372 struct val *
 373 op_eq(struct val *a, struct val *b)
 374 {
 375         return (make_integer((intmax_t)(compare_vals(a, b) == 0)));
 376 }
 377
 378 struct val *
 379 op_gt(struct val *a, struct val *b)
 380 {
 381         return (make_integer((intmax_t)(compare_vals(a, b) > 0)));
 382 }
 383
 384 struct val *
 385 op_lt(struct val *a, struct val *b)
 386 {
 387         return (make_integer((intmax_t)(compare_vals(a, b) < 0)));
 388 }
 389
 390 struct val *
 391 op_ge(struct val *a, struct val *b)
 392 {
 393         return (make_integer((intmax_t)(compare_vals(a, b) >= 0)));
 394 }
 395
 396 struct val *
 397 op_le(struct val *a, struct val *b)
 398 {
 399         return (make_integer((intmax_t)(compare_vals(a, b) <= 0)));
 400 }
 401
 402 struct val *
 403 op_ne(struct val *a, struct val *b)
 404 {
 405         return (make_integer((intmax_t)(compare_vals(a, b) != 0)));
 406 }
 407
 408 void
 409 assert_plus(intmax_t a, intmax_t b, intmax_t r)
 410 {
 411         /*
 412          * sum of two positive numbers must be positive,
 413          * sum of two negative numbers must be negative
 414          */
 415         if ((a > 0 && b > 0 && r <= 0) ||
 416             (a < 0 && b < 0 && r >= 0))
 417                 errx(ERR_EXIT, "overflow");
 418 }
 419
 420 struct val *
 421 op_plus(struct val *a, struct val *b)
 422 {
 423         struct val *r;
 424
 425         assert_to_integer(a);
 426         assert_to_integer(b);
 427         r = make_integer(a->u.i + b->u.i);
 428         assert_plus(a->u.i, b->u.i, r->u.i);
 429
 430         free_value(a);
 431         free_value(b);
 432         return (r);
 433 }
 434
 435 void
 436 assert_minus(intmax_t a, intmax_t b, intmax_t r)
 437 {
 438         /* special case subtraction of INTMAX_MIN */
 439         if (b == INTMAX_MIN && a < 0)
 440                 errx(ERR_EXIT, "overflow");
 441         /* check addition of negative subtrahend */
 442         assert_plus(a, -b, r);
 443 }
 444
 445 struct val *
 446 op_minus(struct val *a, struct val *b)
 447 {
 448         struct val *r;
 449
 450         assert_to_integer(a);
 451         assert_to_integer(b);
 452         r = make_integer(a->u.i - b->u.i);
 453         assert_minus(a->u.i, b->u.i, r->u.i);
 454
 455         free_value(a);
 456         free_value(b);
 457         return (r);
 458 }
 459
 460 void
 461 assert_times(intmax_t a, intmax_t b, intmax_t r)
 462 {
 463         /*
 464          * if first operand is 0, no overflow is possible,
 465          * else result of division test must match second operand
 466          */
 467         if (a != 0 && r / a != b)
 468                 errx(ERR_EXIT, "overflow");
 469 }
 470
 471 struct val *
 472 op_times(struct val *a, struct val *b)
 473 {
 474         struct val *r;
 475
 476         assert_to_integer(a);
 477         assert_to_integer(b);
 478         r = make_integer(a->u.i * b->u.i);
 479         assert_times(a->u.i, b->u.i, r->u.i);
 480
 481         free_value(a);
 482         free_value(b);
 483         return (r);
 484 }
 485
 486 void
 487 assert_div(intmax_t a, intmax_t b)
 488 {
 489         if (b == 0)
 490                 errx(ERR_EXIT, "division by zero");
 491         /* only INTMAX_MIN / -1 causes overflow */
 492         if (a == INTMAX_MIN && b == -1)
 493                 errx(ERR_EXIT, "overflow");
 494 }
 495
 496 struct val *
 497 op_div(struct val *a, struct val *b)
 498 {
 499         struct val *r;
 500
 501         assert_to_integer(a);
 502         assert_to_integer(b);
 503         /* assert based on operands only, not on result */
 504         assert_div(a->u.i, b->u.i);
 505         r = make_integer(a->u.i / b->u.i);
 506
 507         free_value(a);
 508         free_value(b);
 509         return (r);
 510 }
 511
 512 struct val *
 513 op_rem(struct val *a, struct val *b)
 514 {
 515         struct val *r;
 516
 517         assert_to_integer(a);
 518         assert_to_integer(b);
 519         /* pass a=1 to only check for div by zero */
 520         assert_div(1, b->u.i);
 521         r = make_integer(a->u.i % b->u.i);
 522
 523         free_value(a);
 524         free_value(b);
 525         return (r);
 526 }
 527
 528 struct val *
 529 op_colon(struct val *a, struct val *b)
 530 {
 531         regex_t rp;
 532         regmatch_t rm[2];
 533         char errbuf[256];
 534         int eval;
 535         struct val *v;
 536
 537         /* coerce both arguments to strings */
 538         to_string(a);
 539         to_string(b);
 540
 541         /* compile regular expression */
 542         if ((eval = regcomp(&rp, b->u.s, 0)) != 0) {
 543                 regerror(eval, &rp, errbuf, sizeof(errbuf));
 544                 errx(ERR_EXIT, "%s", errbuf);
 545         }
 546
 547         /* compare string against pattern */
 548         /* remember that patterns are anchored to the beginning of the line */
 549         if (regexec(&rp, a->u.s, (size_t)2, rm, 0) == 0 && rm[0].rm_so == 0)
 550                 if (rm[1].rm_so >= 0) {
 551                         *(a->u.s + rm[1].rm_eo) = '\0';
 552                         v = make_str(a->u.s + rm[1].rm_so);
 553 #ifdef __APPLE__
 554                         v->type = string; /* 8319378 */
 555 #endif
 556
 557                 } else
 558                         v = make_integer((intmax_t)(rm[0].rm_eo - rm[0].rm_so));
 559         else
 560                 if (rp.re_nsub == 0)
 561                         v = make_integer((intmax_t)0);
 562                 else
 563                         v = make_str("");
 564
 565         /* free arguments and pattern buffer */
 566         free_value(a);
 567         free_value(b);
 568         regfree(&rp);
 569
 570         return (v);
 571 }