box/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 tarball for details.
  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 #include "libbb.h"
  29 #include "xregex.h"
  30
  31 /* The kinds of value we can have.  */
  32 enum valtype {
  33         integer,
  34         string
  35 };
  36 typedef enum valtype TYPE;
  37
  38 #if ENABLE_EXPR_MATH_SUPPORT_64
  39 typedef int64_t arith_t;
  40
  41 #define PF_REZ      "ll"
  42 #define PF_REZ_TYPE (long long)
  43 #define STRTOL(s, e, b) strtoll(s, e, b)
  44 #else
  45 typedef long arith_t;
  46
  47 #define PF_REZ      "l"
  48 #define PF_REZ_TYPE (long)
  49 #define STRTOL(s, e, b) strtol(s, e, b)
  50 #endif
  51
  52 /* TODO: use bb_strtol[l]? It's easier to check for errors... */
  53
  54 /* A value is.... */
  55 struct valinfo {
  56         TYPE type;                      /* Which kind. */
  57         union {                         /* The value itself. */
  58                 arith_t i;
  59                 char *s;
  60         } u;
  61 };
  62 typedef struct valinfo VALUE;
  63
  64 /* The arguments given to the program, minus the program name.  */
  65 struct globals {
  66         char **args;
  67 };
  68 #define G (*(struct globals*)&bb_common_bufsiz1)
  69
  70 /* forward declarations */
  71 static VALUE *eval(void);
  72
  73
  74 /* Return a VALUE for I.  */
  75
  76 static VALUE *int_value(arith_t i)
  77 {
  78         VALUE *v;
  79
  80         v = xmalloc(sizeof(VALUE));
  81         v->type = integer;
  82         v->u.i = i;
  83         return v;
  84 }
  85
  86 /* Return a VALUE for S.  */
  87
  88 static VALUE *str_value(const char *s)
  89 {
  90         VALUE *v;
  91
  92         v = xmalloc(sizeof(VALUE));
  93         v->type = string;
  94         v->u.s = xstrdup(s);
  95         return v;
  96 }
  97
  98 /* Free VALUE V, including structure components.  */
  99
 100 static void freev(VALUE * v)
 101 {
 102         if (v->type == string)
 103                 free(v->u.s);
 104         free(v);
 105 }
 106
 107 /* Return nonzero if V is a null-string or zero-number.  */
 108
 109 static int null(VALUE * v)
 110 {
 111         if (v->type == integer)
 112                 return v->u.i == 0;
 113         /* string: */
 114         return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
 115 }
 116
 117 /* Coerce V to a string value (can't fail).  */
 118
 119 static void tostring(VALUE * v)
 120 {
 121         if (v->type == integer) {
 122                 v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
 123                 v->type = string;
 124         }
 125 }
 126
 127 /* Coerce V to an integer value.  Return 1 on success, 0 on failure.  */
 128
 129 static bool toarith(VALUE * v)
 130 {
 131         if (v->type == string) {
 132                 arith_t i;
 133                 char *e;
 134
 135                 /* Don't interpret the empty string as an integer.  */
 136                 /* Currently does not worry about overflow or int/long differences. */
 137                 i = STRTOL(v->u.s, &e, 10);
 138                 if ((v->u.s == e) || *e)
 139                         return 0;
 140                 free(v->u.s);
 141                 v->u.i = i;
 142                 v->type = integer;
 143         }
 144         return 1;
 145 }
 146
 147 /* Return nonzero if the next token matches STR exactly.
 148    STR must not be NULL.  */
 149
 150 static bool nextarg(const char *str)
 151 {
 152         if (*G.args == NULL)
 153                 return 0;
 154         return strcmp(*G.args, str) == 0;
 155 }
 156
 157 /* The comparison operator handling functions.  */
 158
 159 static int cmp_common(VALUE * l, VALUE * r, int op)
 160 {
 161         int cmpval;
 162
 163         if (l->type == string || r->type == string) {
 164                 tostring(l);
 165                 tostring(r);
 166                 cmpval = strcmp(l->u.s, r->u.s);
 167         } else
 168                 cmpval = l->u.i - r->u.i;
 169         if (op == '<')
 170                 return cmpval < 0;
 171         if (op == ('L' + 'E'))
 172                 return cmpval <= 0;
 173         if (op == '=')
 174                 return cmpval == 0;
 175         if (op == '!')
 176                 return cmpval != 0;
 177         if (op == '>')
 178                 return cmpval > 0;
 179         /* >= */
 180         return cmpval >= 0;
 181 }
 182
 183 /* The arithmetic operator handling functions.  */
 184
 185 static arith_t arithmetic_common(VALUE * l, VALUE * r, int op)
 186 {
 187         arith_t li, ri;
 188
 189         if (!toarith(l) || !toarith(r))
 190                 bb_error_msg_and_die("non-numeric argument");
 191         li = l->u.i;
 192         ri = r->u.i;
 193         if ((op == '/' || op == '%') && ri == 0)
 194                 bb_error_msg_and_die("division by zero");
 195         if (op == '+')
 196                 return li + ri;
 197         else if (op == '-')
 198                 return li - ri;
 199         else if (op == '*')
 200                 return li * ri;
 201         else if (op == '/')
 202                 return li / ri;
 203         else
 204                 return li % ri;
 205 }
 206
 207 /* Do the : operator.
 208    SV is the VALUE for the lhs (the string),
 209    PV is the VALUE for the rhs (the pattern).  */
 210
 211 static VALUE *docolon(VALUE * sv, VALUE * pv)
 212 {
 213         VALUE *v;
 214         regex_t re_buffer;
 215         const int NMATCH = 2;
 216         regmatch_t re_regs[NMATCH];
 217
 218         tostring(sv);
 219         tostring(pv);
 220
 221         if (pv->u.s[0] == '^') {
 222                 bb_error_msg("\
 223 warning: unportable BRE: `%s': using `^' as the first character\n\
 224 of a basic regular expression is not portable; it is being ignored", pv->u.s);
 225         }
 226
 227         memset(&re_buffer, 0, sizeof(re_buffer));
 228         memset(re_regs, 0, sizeof(*re_regs));
 229         xregcomp(&re_buffer, pv->u.s, 0);
 230
 231         /* expr uses an anchored pattern match, so check that there was a
 232          * match and that the match starts at offset 0. */
 233         if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH &&
 234                 re_regs[0].rm_so == 0) {
 235                 /* Were \(...\) used? */
 236                 if (re_buffer.re_nsub > 0) {
 237                         sv->u.s[re_regs[1].rm_eo] = '\0';
 238                         v = str_value(sv->u.s + re_regs[1].rm_so);
 239                 } else
 240                         v = int_value(re_regs[0].rm_eo);
 241         } else {
 242                 /* Match failed -- return the right kind of null.  */
 243                 if (re_buffer.re_nsub > 0)
 244                         v = str_value("");
 245                 else
 246                         v = int_value(0);
 247         }
 248 //FIXME: sounds like here is a bit missing: regfree(&re_buffer);
 249         return v;
 250 }
 251
 252 /* Handle bare operands and ( expr ) syntax.  */
 253
 254 static VALUE *eval7(void)
 255 {
 256         VALUE *v;
 257
 258         if (!*G.args)
 259                 bb_error_msg_and_die("syntax error");
 260
 261         if (nextarg("(")) {
 262                 G.args++;
 263                 v = eval();
 264                 if (!nextarg(")"))
 265                         bb_error_msg_and_die("syntax error");
 266                 G.args++;
 267                 return v;
 268         }
 269
 270         if (nextarg(")"))
 271                 bb_error_msg_and_die("syntax error");
 272
 273         return str_value(*G.args++);
 274 }
 275
 276 /* Handle match, substr, index, length, and quote keywords.  */
 277
 278 static VALUE *eval6(void)
 279 {
 280         VALUE *l, *r, *v = NULL /* silence gcc */, *i1, *i2;
 281         static const char * const keywords[] = {
 282                 "quote", "length", "match", "index", "substr", NULL
 283         };
 284
 285         smalluint key = *G.args ? index_in_str_array(keywords, *G.args) + 1 : 0;
 286         if (key == 0) /* not a keyword */
 287                 return eval7();
 288         G.args++; /* We have a valid token, so get the next argument.  */
 289         if (key == 1) { /* quote */
 290                 if (!*G.args)
 291                         bb_error_msg_and_die("syntax error");
 292                 return str_value(*G.args++);
 293         }
 294         if (key == 2) { /* length */
 295                 r = eval6();
 296                 tostring(r);
 297                 v = int_value(strlen(r->u.s));
 298                 freev(r);
 299         } else
 300                 l = eval6();
 301
 302         if (key == 3) { /* match */
 303                 r = eval6();
 304                 v = docolon(l, r);
 305                 freev(l);
 306                 freev(r);
 307         }
 308         if (key == 4) { /* index */
 309                 r = eval6();
 310                 tostring(l);
 311                 tostring(r);
 312                 v = int_value(strcspn(l->u.s, r->u.s) + 1);
 313                 if (v->u.i == (arith_t) strlen(l->u.s) + 1)
 314                         v->u.i = 0;
 315                 freev(l);
 316                 freev(r);
 317         }
 318         if (key == 5) { /* substr */
 319                 i1 = eval6();
 320                 i2 = eval6();
 321                 tostring(l);
 322                 if (!toarith(i1) || !toarith(i2)
 323                         || i1->u.i > (arith_t) strlen(l->u.s)
 324                         || i1->u.i <= 0 || i2->u.i <= 0)
 325                         v = str_value("");
 326                 else {
 327                         v = xmalloc(sizeof(VALUE));
 328                         v->type = string;
 329                         v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
 330                 }
 331                 freev(l);
 332                 freev(i1);
 333                 freev(i2);
 334         }
 335         return v;
 336
 337 }
 338
 339 /* Handle : operator (pattern matching).
 340    Calls docolon to do the real work.  */
 341
 342 static VALUE *eval5(void)
 343 {
 344         VALUE *l, *r, *v;
 345
 346         l = eval6();
 347         while (nextarg(":")) {
 348                 G.args++;
 349                 r = eval6();
 350                 v = docolon(l, r);
 351                 freev(l);
 352                 freev(r);
 353                 l = v;
 354         }
 355         return l;
 356 }
 357
 358 /* Handle *, /, % operators.  */
 359
 360 static VALUE *eval4(void)
 361 {
 362         VALUE *l, *r;
 363         int op;
 364         arith_t val;
 365
 366         l = eval5();
 367         while (1) {
 368                 if (nextarg("*"))
 369                         op = '*';
 370                 else if (nextarg("/"))
 371                         op = '/';
 372                 else if (nextarg("%"))
 373                         op = '%';
 374                 else
 375                         return l;
 376                 G.args++;
 377                 r = eval5();
 378                 val = arithmetic_common(l, r, op);
 379                 freev(l);
 380                 freev(r);
 381                 l = int_value(val);
 382         }
 383 }
 384
 385 /* Handle +, - operators.  */
 386
 387 static VALUE *eval3(void)
 388 {
 389         VALUE *l, *r;
 390         int op;
 391         arith_t val;
 392
 393         l = eval4();
 394         while (1) {
 395                 if (nextarg("+"))
 396                         op = '+';
 397                 else if (nextarg("-"))
 398                         op = '-';
 399                 else
 400                         return l;
 401                 G.args++;
 402                 r = eval4();
 403                 val = arithmetic_common(l, r, op);
 404                 freev(l);
 405                 freev(r);
 406                 l = int_value(val);
 407         }
 408 }
 409
 410 /* Handle comparisons.  */
 411
 412 static VALUE *eval2(void)
 413 {
 414         VALUE *l, *r;
 415         int op;
 416         arith_t val;
 417
 418         l = eval3();
 419         while (1) {
 420                 if (nextarg("<"))
 421                         op = '<';
 422                 else if (nextarg("<="))
 423                         op = 'L' + 'E';
 424                 else if (nextarg("=") || nextarg("=="))
 425                         op = '=';
 426                 else if (nextarg("!="))
 427                         op = '!';
 428                 else if (nextarg(">="))
 429                         op = 'G' + 'E';
 430                 else if (nextarg(">"))
 431                         op = '>';
 432                 else
 433                         return l;
 434                 G.args++;
 435                 r = eval3();
 436                 toarith(l);
 437                 toarith(r);
 438                 val = cmp_common(l, r, op);
 439                 freev(l);
 440                 freev(r);
 441                 l = int_value(val);
 442         }
 443 }
 444
 445 /* Handle &.  */
 446
 447 static VALUE *eval1(void)
 448 {
 449         VALUE *l, *r;
 450
 451         l = eval2();
 452         while (nextarg("&")) {
 453                 G.args++;
 454                 r = eval2();
 455                 if (null(l) || null(r)) {
 456                         freev(l);
 457                         freev(r);
 458                         l = int_value(0);
 459                 } else
 460                         freev(r);
 461         }
 462         return l;
 463 }
 464
 465 /* Handle |.  */
 466
 467 static VALUE *eval(void)
 468 {
 469         VALUE *l, *r;
 470
 471         l = eval1();
 472         while (nextarg("|")) {
 473                 G.args++;
 474                 r = eval1();
 475                 if (null(l)) {
 476                         freev(l);
 477                         l = r;
 478                 } else
 479                         freev(r);
 480         }
 481         return l;
 482 }
 483
 484 int expr_main(int argc, char **argv);
 485 int expr_main(int argc, char **argv)
 486 {
 487         VALUE *v;
 488
 489         if (argc == 1) {
 490                 bb_error_msg_and_die("too few arguments");
 491         }
 492
 493         G.args = argv + 1;
 494
 495         v = eval();
 496         if (*G.args)
 497                 bb_error_msg_and_die("syntax error");
 498
 499         if (v->type == integer)
 500                 printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
 501         else
 502                 puts(v->u.s);
 503
 504         fflush_stdout_and_exit(null(v));
 505 }
 506
 507