release/src/router/busybox/coreutils/expr.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini expr implementation for busybox
   4  *
   5  * based on GNU expr Mike Parker.
   6  * Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
   7  *
   8  * Busybox modifications
   9  * Copyright (c) 2000  Edward Betts <edward@debian.org>.
  10  * Copyright (C) 2003-2005  Vladimir Oleynik <dzo@simtreas.ru>
  11  *  - reduced 464 bytes.
  12  *  - 64 math support
  13  *
  14  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  15  */
  16
  17 /* This program evaluates expressions.  Each token (operator, operand,
  18  * parenthesis) of the expression must be a separate argument.  The
  19  * parser used is a reasonably general one, though any incarnation of
  20  * it is language-specific.  It is especially nice for expressions.
  21  *
  22  * No parse tree is needed; a new node is evaluated immediately.
  23  * One function can handle multiple operators all of equal precedence,
  24  * provided they all associate ((x op x) op x). */
  25
  26 /* no getopt needed */
  27
  28 //usage:#define expr_trivial_usage
  29 //usage:       "EXPRESSION"
  30 //usage:#define expr_full_usage "\n\n"
  31 //usage:       "Print the value of EXPRESSION to stdout\n"
  32 //usage:    "\n"
  33 //usage:       "EXPRESSION may be:\n"
  34 //usage:       "        ARG1 | ARG2     ARG1 if it is neither null nor 0, otherwise ARG2\n"
  35 //usage:       "        ARG1 & ARG2     ARG1 if neither argument is null or 0, otherwise 0\n"
  36 //usage:       "        ARG1 < ARG2     1 if ARG1 is less than ARG2, else 0. Similarly:\n"
  37 //usage:       "        ARG1 <= ARG2\n"
  38 //usage:       "        ARG1 = ARG2\n"
  39 //usage:       "        ARG1 != ARG2\n"
  40 //usage:       "        ARG1 >= ARG2\n"
  41 //usage:       "        ARG1 > ARG2\n"
  42 //usage:       "        ARG1 + ARG2     Sum of ARG1 and ARG2. Similarly:\n"
  43 //usage:       "        ARG1 - ARG2\n"
  44 //usage:       "        ARG1 * ARG2\n"
  45 //usage:       "        ARG1 / ARG2\n"
  46 //usage:       "        ARG1 % ARG2\n"
  47 //usage:       "        STRING : REGEXP         Anchored pattern match of REGEXP in STRING\n"
  48 //usage:       "        match STRING REGEXP     Same as STRING : REGEXP\n"
  49 //usage:       "        substr STRING POS LENGTH Substring of STRING, POS counted from 1\n"
  50 //usage:       "        index STRING CHARS      Index in STRING where any CHARS is found, or 0\n"
  51 //usage:       "        length STRING           Length of STRING\n"
  52 //usage:       "        quote TOKEN             Interpret TOKEN as a string, even if\n"
  53 //usage:       "                                it is a keyword like 'match' or an\n"
  54 //usage:       "                                operator like '/'\n"
  55 //usage:       "        (EXPRESSION)            Value of EXPRESSION\n"
  56 //usage:       "\n"
  57 //usage:       "Beware that many operators need to be escaped or quoted for shells.\n"
  58 //usage:       "Comparisons are arithmetic if both ARGs are numbers, else\n"
  59 //usage:       "lexicographical. Pattern matches return the string matched between\n"
  60 //usage:       "\\( and \\) or null; if \\( and \\) are not used, they return the number\n"
  61 //usage:       "of characters matched or 0."
  62
  63 #include "libbb.h"
  64 #include "xregex.h"
  65
  66 #if ENABLE_EXPR_MATH_SUPPORT_64
  67 typedef int64_t arith_t;
  68
  69 #define PF_REZ      "ll"
  70 #define PF_REZ_TYPE (long long)
  71 #define STRTOL(s, e, b) strtoll(s, e, b)
  72 #else
  73 typedef long arith_t;
  74
  75 #define PF_REZ      "l"
  76 #define PF_REZ_TYPE (long)
  77 #define STRTOL(s, e, b) strtol(s, e, b)
  78 #endif
  79
  80 /* TODO: use bb_strtol[l]? It's easier to check for errors... */
  81
  82 /* The kinds of value we can have.  */
  83 enum {
  84         INTEGER,
  85         STRING
  86 };
  87
  88 /* A value is.... */
  89 struct valinfo {
  90         smallint type;                  /* Which kind. */
  91         union {                         /* The value itself. */
  92                 arith_t i;
  93                 char *s;
  94         } u;
  95 };
  96 typedef struct valinfo VALUE;
  97
  98 /* The arguments given to the program, minus the program name.  */
  99 struct globals {
 100         char **args;
 101 } FIX_ALIASING;
 102 #define G (*(struct globals*)&bb_common_bufsiz1)
 103 #define INIT_G() do { } while (0)
 104
 105 /* forward declarations */
 106 static VALUE *eval(void);
 107
 108
 109 /* Return a VALUE for I.  */
 110
 111 static VALUE *int_value(arith_t i)
 112 {
 113         VALUE *v;
 114
 115         v = xzalloc(sizeof(VALUE));
 116         if (INTEGER) /* otherwise xzaaloc did it already */
 117                 v->type = INTEGER;
 118         v->u.i = i;
 119         return v;
 120 }
 121
 122 /* Return a VALUE for S.  */
 123
 124 static VALUE *str_value(const char *s)
 125 {
 126         VALUE *v;
 127
 128         v = xzalloc(sizeof(VALUE));
 129         if (STRING) /* otherwise xzaaloc did it already */
 130                 v->type = STRING;
 131         v->u.s = xstrdup(s);
 132         return v;
 133 }
 134
 135 /* Free VALUE V, including structure components.  */
 136
 137 static void freev(VALUE *v)
 138 {
 139         if (v->type == STRING)
 140                 free(v->u.s);
 141         free(v);
 142 }
 143
 144 /* Return nonzero if V is a null-string or zero-number.  */
 145
 146 static int null(VALUE *v)
 147 {
 148         if (v->type == INTEGER)
 149                 return v->u.i == 0;
 150         /* STRING: */
 151         return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
 152 }
 153
 154 /* Coerce V to a STRING value (can't fail).  */
 155
 156 static void tostring(VALUE *v)
 157 {
 158         if (v->type == INTEGER) {
 159                 v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
 160                 v->type = STRING;
 161         }
 162 }
 163
 164 /* Coerce V to an INTEGER value.  Return 1 on success, 0 on failure.  */
 165
 166 static bool toarith(VALUE *v)
 167 {
 168         if (v->type == STRING) {
 169                 arith_t i;
 170                 char *e;
 171
 172                 /* Don't interpret the empty string as an integer.  */
 173                 /* Currently does not worry about overflow or int/long differences. */
 174                 i = STRTOL(v->u.s, &e, 10);
 175                 if ((v->u.s == e) || *e)
 176                         return 0;
 177                 free(v->u.s);
 178                 v->u.i = i;
 179                 v->type = INTEGER;
 180         }
 181         return 1;
 182 }
 183
 184 /* Return str[0]+str[1] if the next token matches STR exactly.
 185    STR must not be NULL.  */
 186
 187 static int nextarg(const char *str)
 188 {
 189         if (*G.args == NULL || strcmp(*G.args, str) != 0)
 190                 return 0;
 191         return (unsigned char)str[0] + (unsigned char)str[1];
 192 }
 193
 194 /* The comparison operator handling functions.  */
 195
 196 static int cmp_common(VALUE *l, VALUE *r, int op)
 197 {
 198         arith_t ll, rr;
 199
 200         ll = l->u.i;
 201         rr = r->u.i;
 202         if (l->type == STRING || r->type == STRING) {
 203                 tostring(l);
 204                 tostring(r);
 205                 ll = strcmp(l->u.s, r->u.s);
 206                 rr = 0;
 207         }
 208         /* calculating ll - rr and checking the result is prone to overflows.
 209          * We'll do it differently: */
 210         if (op == '<')
 211                 return ll < rr;
 212         if (op == ('<' + '='))
 213                 return ll <= rr;
 214         if (op == '=' || (op == '=' + '='))
 215                 return ll == rr;
 216         if (op == '!' + '=')
 217                 return ll != rr;
 218         if (op == '>')
 219                 return ll > rr;
 220         /* >= */
 221         return ll >= rr;
 222 }
 223
 224 /* The arithmetic operator handling functions.  */
 225
 226 static arith_t arithmetic_common(VALUE *l, VALUE *r, int op)
 227 {
 228         arith_t li, ri;
 229
 230         if (!toarith(l) || !toarith(r))
 231                 bb_error_msg_and_die("non-numeric argument");
 232         li = l->u.i;
 233         ri = r->u.i;
 234         if (op == '+')
 235                 return li + ri;
 236         if (op == '-')
 237                 return li - ri;
 238         if (op == '*')
 239                 return li * ri;
 240         if (ri == 0)
 241                 bb_error_msg_and_die("division by zero");
 242         if (op == '/')
 243                 return li / ri;
 244         return li % ri;
 245 }
 246
 247 /* Do the : operator.
 248    SV is the VALUE for the lhs (the string),
 249    PV is the VALUE for the rhs (the pattern).  */
 250
 251 static VALUE *docolon(VALUE *sv, VALUE *pv)
 252 {
 253         enum { NMATCH = 2 };
 254         VALUE *v;
 255         regex_t re_buffer;
 256         regmatch_t re_regs[NMATCH];
 257
 258         tostring(sv);
 259         tostring(pv);
 260
 261         if (pv->u.s[0] == '^') {
 262                 bb_error_msg(
 263 "warning: '%s': using '^' as the first character\n"
 264 "of a basic regular expression is not portable; it is ignored", pv->u.s);
 265         }
 266
 267         memset(&re_buffer, 0, sizeof(re_buffer));
 268         memset(re_regs, 0, sizeof(re_regs));
 269         xregcomp(&re_buffer, pv->u.s, 0);
 270
 271         /* expr uses an anchored pattern match, so check that there was a
 272          * match and that the match starts at offset 0. */
 273         if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
 274          && re_regs[0].rm_so == 0
 275         ) {
 276                 /* Were \(...\) used? */
 277                 if (re_buffer.re_nsub > 0 && re_regs[1].rm_so >= 0) {
 278                         sv->u.s[re_regs[1].rm_eo] = '\0';
 279                         v = str_value(sv->u.s + re_regs[1].rm_so);
 280                 } else {
 281                         v = int_value(re_regs[0].rm_eo);
 282                 }
 283         } else {
 284                 /* Match failed -- return the right kind of null.  */
 285                 if (re_buffer.re_nsub > 0)
 286                         v = str_value("");
 287                 else
 288                         v = int_value(0);
 289         }
 290         regfree(&re_buffer);
 291         return v;
 292 }
 293
 294 /* Handle bare operands and ( expr ) syntax.  */
 295
 296 static VALUE *eval7(void)
 297 {
 298         VALUE *v;
 299
 300         if (!*G.args)
 301                 bb_error_msg_and_die("syntax error");
 302
 303         if (nextarg("(")) {
 304                 G.args++;
 305                 v = eval();
 306                 if (!nextarg(")"))
 307                         bb_error_msg_and_die("syntax error");
 308                 G.args++;
 309                 return v;
 310         }
 311
 312         if (nextarg(")"))
 313                 bb_error_msg_and_die("syntax error");
 314
 315         return str_value(*G.args++);
 316 }
 317
 318 /* Handle match, substr, index, length, and quote keywords.  */
 319
 320 static VALUE *eval6(void)
 321 {
 322         static const char keywords[] ALIGN1 =
 323                 "quote\0""length\0""match\0""index\0""substr\0";
 324
 325         VALUE *r, *i1, *i2;
 326         VALUE *l = l; /* silence gcc */
 327         VALUE *v = v; /* silence gcc */
 328         int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;
 329
 330         if (key == 0) /* not a keyword */
 331                 return eval7();
 332         G.args++; /* We have a valid token, so get the next argument.  */
 333         if (key == 1) { /* quote */
 334                 if (!*G.args)
 335                         bb_error_msg_and_die("syntax error");
 336                 return str_value(*G.args++);
 337         }
 338         if (key == 2) { /* length */
 339                 r = eval6();
 340                 tostring(r);
 341                 v = int_value(strlen(r->u.s));
 342                 freev(r);
 343         } else
 344                 l = eval6();
 345
 346         if (key == 3) { /* match */
 347                 r = eval6();
 348                 v = docolon(l, r);
 349                 freev(l);
 350                 freev(r);
 351         }
 352         if (key == 4) { /* index */
 353                 r = eval6();
 354                 tostring(l);
 355                 tostring(r);
 356                 v = int_value(strcspn(l->u.s, r->u.s) + 1);
 357                 if (v->u.i == (arith_t) strlen(l->u.s) + 1)
 358                         v->u.i = 0;
 359                 freev(l);
 360                 freev(r);
 361         }
 362         if (key == 5) { /* substr */
 363                 i1 = eval6();
 364                 i2 = eval6();
 365                 tostring(l);
 366                 if (!toarith(i1) || !toarith(i2)
 367                  || i1->u.i > (arith_t) strlen(l->u.s)
 368                  || i1->u.i <= 0 || i2->u.i <= 0)
 369                         v = str_value("");
 370                 else {
 371                         v = xmalloc(sizeof(VALUE));
 372                         v->type = STRING;
 373                         v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
 374                 }
 375                 freev(l);
 376                 freev(i1);
 377                 freev(i2);
 378         }
 379         return v;
 380 }
 381
 382 /* Handle : operator (pattern matching).
 383    Calls docolon to do the real work.  */
 384
 385 static VALUE *eval5(void)
 386 {
 387         VALUE *l, *r, *v;
 388
 389         l = eval6();
 390         while (nextarg(":")) {
 391                 G.args++;
 392                 r = eval6();
 393                 v = docolon(l, r);
 394                 freev(l);
 395                 freev(r);
 396                 l = v;
 397         }
 398         return l;
 399 }
 400
 401 /* Handle *, /, % operators.  */
 402
 403 static VALUE *eval4(void)
 404 {
 405         VALUE *l, *r;
 406         int op;
 407         arith_t val;
 408
 409         l = eval5();
 410         while (1) {
 411                 op = nextarg("*");
 412                 if (!op) { op = nextarg("/");
 413                  if (!op) { op = nextarg("%");
 414                   if (!op) return l;
 415                 }}
 416                 G.args++;
 417                 r = eval5();
 418                 val = arithmetic_common(l, r, op);
 419                 freev(l);
 420                 freev(r);
 421                 l = int_value(val);
 422         }
 423 }
 424
 425 /* Handle +, - operators.  */
 426
 427 static VALUE *eval3(void)
 428 {
 429         VALUE *l, *r;
 430         int op;
 431         arith_t val;
 432
 433         l = eval4();
 434         while (1) {
 435                 op = nextarg("+");
 436                 if (!op) {
 437                         op = nextarg("-");
 438                         if (!op) return l;
 439                 }
 440                 G.args++;
 441                 r = eval4();
 442                 val = arithmetic_common(l, r, op);
 443                 freev(l);
 444                 freev(r);
 445                 l = int_value(val);
 446         }
 447 }
 448
 449 /* Handle comparisons.  */
 450
 451 static VALUE *eval2(void)
 452 {
 453         VALUE *l, *r;
 454         int op;
 455         arith_t val;
 456
 457         l = eval3();
 458         while (1) {
 459                 op = nextarg("<");
 460                 if (!op) { op = nextarg("<=");
 461                  if (!op) { op = nextarg("=");
 462                   if (!op) { op = nextarg("==");
 463                    if (!op) { op = nextarg("!=");
 464                     if (!op) { op = nextarg(">=");
 465                      if (!op) { op = nextarg(">");
 466                       if (!op) return l;
 467                 }}}}}}
 468                 G.args++;
 469                 r = eval3();
 470                 toarith(l);
 471                 toarith(r);
 472                 val = cmp_common(l, r, op);
 473                 freev(l);
 474                 freev(r);
 475                 l = int_value(val);
 476         }
 477 }
 478
 479 /* Handle &.  */
 480
 481 static VALUE *eval1(void)
 482 {
 483         VALUE *l, *r;
 484
 485         l = eval2();
 486         while (nextarg("&")) {
 487                 G.args++;
 488                 r = eval2();
 489                 if (null(l) || null(r)) {
 490                         freev(l);
 491                         freev(r);
 492                         l = int_value(0);
 493                 } else
 494                         freev(r);
 495         }
 496         return l;
 497 }
 498
 499 /* Handle |.  */
 500
 501 static VALUE *eval(void)
 502 {
 503         VALUE *l, *r;
 504
 505         l = eval1();
 506         while (nextarg("|")) {
 507                 G.args++;
 508                 r = eval1();
 509                 if (null(l)) {
 510                         freev(l);
 511                         l = r;
 512                 } else
 513                         freev(r);
 514         }
 515         return l;
 516 }
 517
 518 int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 519 int expr_main(int argc UNUSED_PARAM, char **argv)
 520 {
 521         VALUE *v;
 522
 523         INIT_G();
 524
 525         xfunc_error_retval = 2; /* coreutils compat */
 526         G.args = argv + 1;
 527         if (*G.args == NULL) {
 528                 bb_error_msg_and_die("too few arguments");
 529         }
 530         v = eval();
 531         if (*G.args)
 532                 bb_error_msg_and_die("syntax error");
 533         if (v->type == INTEGER)
 534                 printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
 535         else
 536                 puts(v->u.s);
 537         fflush_stdout_and_exit(null(v));
 538 }