smatch_type.c

   1 /*
   2  * Copyright (C) 2009 Dan Carpenter.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * The idea here is that you have an expression and you
  20  * want to know what the type is for that.
  21  */
  22
  23 #include "smatch.h"
  24 #include "smatch_slist.h"
  25
  26 struct symbol *get_real_base_type(struct symbol *sym)
  27 {
  28         struct symbol *ret;
  29
  30         if (!sym)
  31                 return NULL;
  32         ret = get_base_type(sym);
  33         if (!ret)
  34                 return NULL;
  35         if (ret->type == SYM_RESTRICT || ret->type == SYM_NODE)
  36                 return get_real_base_type(ret);
  37         return ret;
  38 }
  39
  40 int type_bits(struct symbol *type)
  41 {
  42         if (!type)
  43                 return 0;
  44         if (type->type == SYM_PTR)  /* Sparse doesn't set this for &pointers */
  45                 return bits_in_pointer;
  46         if (!type->examined)
  47                 examine_symbol_type(type);
  48         return type->bit_size;
  49 }
  50
  51 int type_bytes(struct symbol *type)
  52 {
  53         int bits = type_bits(type);
  54
  55         if (bits < 0)
  56                 return 0;
  57         return bits_to_bytes(bits);
  58 }
  59
  60 int type_positive_bits(struct symbol *type)
  61 {
  62         if (!type)
  63                 return 0;
  64         if (type_unsigned(type))
  65                 return type_bits(type);
  66         return type_bits(type) - 1;
  67 }
  68
  69 static struct symbol *get_binop_type(struct expression *expr)
  70 {
  71         struct symbol *left, *right;
  72
  73         left = get_type(expr->left);
  74         right = get_type(expr->right);
  75
  76         if (!left || !right)
  77                 return NULL;
  78
  79         if (left->type == SYM_PTR || left->type == SYM_ARRAY)
  80                 return left;
  81         if (right->type == SYM_PTR || right->type == SYM_ARRAY)
  82                 return right;
  83
  84         if (expr->op == SPECIAL_LEFTSHIFT ||
  85             expr->op == SPECIAL_RIGHTSHIFT) {
  86                 if (type_positive_bits(left) < 31)
  87                         return &int_ctype;
  88                 return left;
  89         }
  90
  91         if (type_positive_bits(left) < 31 && type_positive_bits(right) < 31)
  92                 return &int_ctype;
  93
  94         if (type_positive_bits(left) > type_positive_bits(right))
  95                 return left;
  96         return right;
  97 }
  98
  99 static struct symbol *get_type_symbol(struct expression *expr)
 100 {
 101         if (!expr || expr->type != EXPR_SYMBOL || !expr->symbol)
 102                 return NULL;
 103
 104         return get_real_base_type(expr->symbol);
 105 }
 106
 107 static struct symbol *get_member_symbol(struct symbol_list *symbol_list, struct ident *member)
 108 {
 109         struct symbol *tmp, *sub;
 110
 111         FOR_EACH_PTR(symbol_list, tmp) {
 112                 if (!tmp->ident) {
 113                         sub = get_real_base_type(tmp);
 114                         sub = get_member_symbol(sub->symbol_list, member);
 115                         if (sub)
 116                                 return sub;
 117                         continue;
 118                 }
 119                 if (tmp->ident == member)
 120                         return tmp;
 121         } END_FOR_EACH_PTR(tmp);
 122
 123         return NULL;
 124 }
 125
 126 static struct symbol *get_symbol_from_deref(struct expression *expr)
 127 {
 128         struct ident *member;
 129         struct symbol *sym;
 130
 131         if (!expr || expr->type != EXPR_DEREF)
 132                 return NULL;
 133
 134         member = expr->member;
 135         sym = get_type(expr->deref);
 136         if (!sym) {
 137                 // sm_msg("could not find struct type");
 138                 return NULL;
 139         }
 140         if (sym->type == SYM_PTR)
 141                 sym = get_real_base_type(sym);
 142         sym = get_member_symbol(sym->symbol_list, member);
 143         if (!sym)
 144                 return NULL;
 145         return get_real_base_type(sym);
 146 }
 147
 148 static struct symbol *get_return_type(struct expression *expr)
 149 {
 150         struct symbol *tmp;
 151
 152         tmp = get_type(expr->fn);
 153         if (!tmp)
 154                 return NULL;
 155         return get_real_base_type(tmp);
 156 }
 157
 158 static struct symbol *get_expr_stmt_type(struct statement *stmt)
 159 {
 160         if (stmt->type != STMT_COMPOUND)
 161                 return NULL;
 162         stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 163         if (!stmt || stmt->type != STMT_EXPRESSION)
 164                 return NULL;
 165         return get_type(stmt->expression);
 166 }
 167
 168 static struct symbol *get_select_type(struct expression *expr)
 169 {
 170         struct symbol *one, *two;
 171
 172         one = get_type(expr->cond_true);
 173         two = get_type(expr->cond_false);
 174         if (!one || !two)
 175                 return NULL;
 176         /*
 177          * This is a hack.  If the types are not equiv then we
 178          * really don't know the type.  But I think guessing is
 179          *  probably Ok here.
 180          */
 181         if (type_positive_bits(one) > type_positive_bits(two))
 182                 return one;
 183         return two;
 184 }
 185
 186 struct symbol *get_pointer_type(struct expression *expr)
 187 {
 188         struct symbol *sym;
 189
 190         sym = get_type(expr);
 191         if (!sym)
 192                 return NULL;
 193         if (sym->type == SYM_NODE) {
 194                 sym = get_real_base_type(sym);
 195                 if (!sym)
 196                         return NULL;
 197         }
 198         if (sym->type != SYM_PTR && sym->type != SYM_ARRAY)
 199                 return NULL;
 200         return get_real_base_type(sym);
 201 }
 202
 203 static struct symbol *fake_pointer_sym(struct expression *expr)
 204 {
 205         struct symbol *sym;
 206         struct symbol *base;
 207
 208         sym = alloc_symbol(expr->pos, SYM_PTR);
 209         expr = expr->unop;
 210         base = get_type(expr);
 211         if (!base)
 212                 return NULL;
 213         sym->ctype.base_type = base;
 214         return sym;
 215 }
 216
 217 struct symbol *get_type(struct expression *expr)
 218 {
 219         if (!expr)
 220                 return NULL;
 221         expr = strip_parens(expr);
 222
 223         switch (expr->type) {
 224         case EXPR_STRING:
 225                 return &string_ctype;
 226         case EXPR_SYMBOL:
 227                 return get_type_symbol(expr);
 228         case EXPR_DEREF:
 229                 return get_symbol_from_deref(expr);
 230         case EXPR_PREOP:
 231         case EXPR_POSTOP:
 232                 if (expr->op == '&')
 233                         return fake_pointer_sym(expr);
 234                 if (expr->op == '*')
 235                         return get_pointer_type(expr->unop);
 236                 return get_type(expr->unop);
 237         case EXPR_ASSIGNMENT:
 238                 return get_type(expr->left);
 239         case EXPR_CAST:
 240         case EXPR_FORCE_CAST:
 241         case EXPR_IMPLIED_CAST:
 242                 return get_real_base_type(expr->cast_type);
 243         case EXPR_COMPARE:
 244         case EXPR_BINOP:
 245                 return get_binop_type(expr);
 246         case EXPR_CALL:
 247                 return get_return_type(expr);
 248         case EXPR_STATEMENT:
 249                 return get_expr_stmt_type(expr->statement);
 250         case EXPR_CONDITIONAL:
 251         case EXPR_SELECT:
 252                 return get_select_type(expr);
 253         case EXPR_SIZEOF:
 254                 return &ulong_ctype;
 255         case EXPR_LOGICAL:
 256                 return &int_ctype;
 257         default:
 258 //              sm_msg("unhandled type %d", expr->type);
 259                 return expr->ctype;
 260         }
 261         return NULL;
 262 }
 263
 264 int type_unsigned(struct symbol *base_type)
 265 {
 266         if (!base_type)
 267                 return 0;
 268         if (base_type->ctype.modifiers & MOD_UNSIGNED)
 269                 return 1;
 270         return 0;
 271 }
 272
 273 int type_signed(struct symbol *base_type)
 274 {
 275         if (!base_type)
 276                 return 0;
 277         if (base_type->ctype.modifiers & MOD_SIGNED)
 278                 return 1;
 279         return 0;
 280 }
 281
 282 int expr_unsigned(struct expression *expr)
 283 {
 284         struct symbol *sym;
 285
 286         sym = get_type(expr);
 287         if (!sym)
 288                 return 0;
 289         if (type_unsigned(sym))
 290                 return 1;
 291         return 0;
 292 }
 293
 294 int expr_signed(struct expression *expr)
 295 {
 296         struct symbol *sym;
 297
 298         sym = get_type(expr);
 299         if (!sym)
 300                 return 0;
 301         if (type_signed(sym))
 302                 return 1;
 303         return 0;
 304 }
 305
 306 int returns_unsigned(struct symbol *sym)
 307 {
 308         if (!sym)
 309                 return 0;
 310         sym = get_base_type(sym);
 311         if (!sym || sym->type != SYM_FN)
 312                 return 0;
 313         sym = get_base_type(sym);
 314         return type_unsigned(sym);
 315 }
 316
 317 int is_pointer(struct expression *expr)
 318 {
 319         struct symbol *sym;
 320
 321         sym = get_type(expr);
 322         if (!sym)
 323                 return 0;
 324         if (sym == &string_ctype)
 325                 return 0;
 326         if (sym->type == SYM_PTR)
 327                 return 1;
 328         return 0;
 329 }
 330
 331 int returns_pointer(struct symbol *sym)
 332 {
 333         if (!sym)
 334                 return 0;
 335         sym = get_base_type(sym);
 336         if (!sym || sym->type != SYM_FN)
 337                 return 0;
 338         sym = get_base_type(sym);
 339         if (sym->type == SYM_PTR)
 340                 return 1;
 341         return 0;
 342 }
 343
 344 sval_t sval_type_max(struct symbol *base_type)
 345 {
 346         sval_t ret;
 347
 348         if (!base_type || !type_bits(base_type))
 349                 base_type = &llong_ctype;
 350         ret.type = base_type;
 351
 352         ret.value = (~0ULL) >> (64 - type_positive_bits(base_type));
 353         return ret;
 354 }
 355
 356 sval_t sval_type_min(struct symbol *base_type)
 357 {
 358         sval_t ret;
 359
 360         if (!base_type || !type_bits(base_type))
 361                 base_type = &llong_ctype;
 362         ret.type = base_type;
 363
 364         if (type_unsigned(base_type)) {
 365                 ret.value = 0;
 366                 return ret;
 367         }
 368
 369         ret.value = (~0ULL) << type_positive_bits(base_type);
 370
 371         return ret;
 372 }
 373
 374 int nr_bits(struct expression *expr)
 375 {
 376         struct symbol *type;
 377
 378         type = get_type(expr);
 379         if (!type)
 380                 return 0;
 381         return type_bits(type);
 382 }
 383
 384 int is_void_pointer(struct expression *expr)
 385 {
 386         struct symbol *type;
 387
 388         type = get_type(expr);
 389         if (!type || type->type != SYM_PTR)
 390                 return 0;
 391         type = get_real_base_type(type);
 392         if (type == &void_ctype)
 393                 return 1;
 394         return 0;
 395 }
 396
 397 int is_char_pointer(struct expression *expr)
 398 {
 399         struct symbol *type;
 400
 401         type = get_type(expr);
 402         if (!type || type->type != SYM_PTR)
 403                 return 0;
 404         type = get_real_base_type(type);
 405         if (type == &char_ctype)
 406                 return 1;
 407         return 0;
 408 }
 409
 410 int is_string(struct expression *expr)
 411 {
 412         expr = strip_expr(expr);
 413         if (!expr || expr->type != EXPR_STRING)
 414                 return 0;
 415         if (expr->string)
 416                 return 1;
 417         return 0;
 418 }
 419
 420 int is_static(struct expression *expr)
 421 {
 422         char *name;
 423         struct symbol *sym;
 424         int ret = 0;
 425
 426         name = expr_to_str_sym(expr, &sym);
 427         if (!name || !sym)
 428                 goto free;
 429
 430         if (sym->ctype.modifiers & MOD_STATIC)
 431                 ret = 1;
 432 free:
 433         free_string(name);
 434         return ret;
 435 }
 436
 437 int types_equiv(struct symbol *one, struct symbol *two)
 438 {
 439         if (!one && !two)
 440                 return 1;
 441         if (!one || !two)
 442                 return 0;
 443         if (one->type != two->type)
 444                 return 0;
 445         if (one->type == SYM_PTR)
 446                 return types_equiv(get_real_base_type(one), get_real_base_type(two));
 447         if (type_positive_bits(one) != type_positive_bits(two))
 448                 return 0;
 449         return 1;
 450 }
 451
 452 int fn_static(void)
 453 {
 454         return !!(cur_func_sym->ctype.modifiers & MOD_STATIC);
 455 }
 456
 457 const char *global_static(void)
 458 {
 459         if (cur_func_sym->ctype.modifiers & MOD_STATIC)
 460                 return "static";
 461         else
 462                 return "global";
 463 }
 464
 465 struct symbol *cur_func_return_type(void)
 466 {
 467         struct symbol *sym;
 468
 469         sym = get_real_base_type(cur_func_sym);
 470         if (!sym || sym->type != SYM_FN)
 471                 return NULL;
 472         sym = get_real_base_type(sym);
 473         return sym;
 474 }
 475
 476 struct symbol *get_arg_type(struct expression *fn, int arg)
 477 {
 478         struct symbol *fn_type;
 479         struct symbol *tmp;
 480         struct symbol *arg_type;
 481         int i;
 482
 483         fn_type = get_type(fn);
 484         if (!fn_type)
 485                 return NULL;
 486         if (fn_type->type == SYM_PTR)
 487                 fn_type = get_real_base_type(fn_type);
 488         if (fn_type->type != SYM_FN)
 489                 return NULL;
 490
 491         i = 0;
 492         FOR_EACH_PTR(fn_type->arguments, tmp) {
 493                 arg_type = get_real_base_type(tmp);
 494                 if (i == arg) {
 495                         return arg_type;
 496                 }
 497                 i++;
 498         } END_FOR_EACH_PTR(tmp);
 499
 500         return NULL;
 501 }
 502
 503 static struct symbol *get_member_from_string(struct symbol_list *symbol_list, char *name)
 504 {
 505         struct symbol *tmp, *sub;
 506         int chunk_len;
 507
 508         if (strncmp(name, ".", 1) == 0)
 509                 name += 1;
 510         if (strncmp(name, "->", 2) == 0)
 511                 name += 2;
 512
 513         FOR_EACH_PTR(symbol_list, tmp) {
 514                 if (!tmp->ident) {
 515                         sub = get_real_base_type(tmp);
 516                         sub = get_member_from_string(sub->symbol_list, name);
 517                         if (sub)
 518                                 return sub;
 519                         continue;
 520                 }
 521
 522                 if (strcmp(tmp->ident->name, name) == 0)
 523                         return tmp;
 524
 525                 chunk_len = strlen(tmp->ident->name);
 526                 if (strncmp(tmp->ident->name, name, chunk_len) == 0 &&
 527                     (name[chunk_len] == '.' || name[chunk_len] == '-')) {
 528                         sub = get_real_base_type(tmp);
 529                         return get_member_from_string(sub->symbol_list, name + chunk_len);
 530                 }
 531
 532         } END_FOR_EACH_PTR(tmp);
 533
 534         return NULL;
 535 }
 536
 537 struct symbol *get_member_type_from_key(struct expression *expr, char *key)
 538 {
 539         struct symbol *sym;
 540         char *name;
 541
 542         if (strcmp(key, "$") == 0)
 543                 return get_type(expr);
 544
 545         if (strcmp(key, "*$") == 0) {
 546                 sym = get_type(expr);
 547                 if (!sym || sym->type != SYM_PTR)
 548                         return NULL;
 549                 return get_real_base_type(sym);
 550         }
 551
 552         name = expr_to_str_sym(expr, &sym);
 553         free_string(name);
 554         if (!sym)
 555                 return NULL;
 556         sym = get_real_base_type(sym);
 557         if (sym->type == SYM_PTR)
 558                 sym = get_real_base_type(sym);
 559
 560         key = key + 1;
 561         sym = get_member_from_string(sym->symbol_list, key);
 562         if (!sym)
 563                 return NULL;
 564         return get_real_base_type(sym);
 565 }
 566
 567 int is_struct(struct expression *expr)
 568 {
 569         struct symbol *type;
 570
 571         type = get_type(expr);
 572         if (type && type->type == SYM_STRUCT)
 573                 return 1;
 574         return 0;
 575 }
 576
 577 static struct {
 578         struct symbol *sym;
 579         const char *name;
 580 } base_types[] = {
 581         {&bool_ctype, "bool"},
 582         {&void_ctype, "void"},
 583         {&type_ctype, "type"},
 584         {&char_ctype, "char"},
 585         {&schar_ctype, "schar"},
 586         {&uchar_ctype, "uchar"},
 587         {&short_ctype, "short"},
 588         {&sshort_ctype, "sshort"},
 589         {&ushort_ctype, "ushort"},
 590         {&int_ctype, "int"},
 591         {&sint_ctype, "sint"},
 592         {&uint_ctype, "uint"},
 593         {&long_ctype, "long"},
 594         {&slong_ctype, "slong"},
 595         {&ulong_ctype, "ulong"},
 596         {&llong_ctype, "llong"},
 597         {&sllong_ctype, "sllong"},
 598         {&ullong_ctype, "ullong"},
 599         {&lllong_ctype, "lllong"},
 600         {&slllong_ctype, "slllong"},
 601         {&ulllong_ctype, "ulllong"},
 602         {&float_ctype, "float"},
 603         {&double_ctype, "double"},
 604         {&ldouble_ctype, "ldouble"},
 605         {&string_ctype, "string"},
 606         {&ptr_ctype, "ptr"},
 607         {&lazy_ptr_ctype, "lazy_ptr"},
 608         {&incomplete_ctype, "incomplete"},
 609         {&label_ctype, "label"},
 610         {&bad_ctype, "bad"},
 611         {&null_ctype, "null"},
 612 };
 613
 614 static const char *base_type_str(struct symbol *sym)
 615 {
 616         int i;
 617
 618         for (i = 0; i < ARRAY_SIZE(base_types); i++) {
 619                 if (sym == base_types[i].sym)
 620                         return base_types[i].name;
 621         }
 622         return "<unknown>";
 623 }
 624
 625 static int type_str_helper(char *buf, int size, struct symbol *type)
 626 {
 627         int n;
 628
 629         if (!type)
 630                 return snprintf(buf, size, "<unknown>");
 631
 632         if (type->type == SYM_BASETYPE) {
 633                 return snprintf(buf, size, base_type_str(type));
 634         } else if (type->type == SYM_PTR) {
 635                 type = get_real_base_type(type);
 636                 n = type_str_helper(buf, size, type);
 637                 if (n > size)
 638                         return n;
 639                 return n + snprintf(buf + n, size - n, "*");
 640         } else if (type->type == SYM_STRUCT) {
 641                 return snprintf(buf, size, "struct %s", type->ident ? type->ident->name : "");
 642         } else if (type->type == SYM_UNION) {
 643                 if (type->ident)
 644                         return snprintf(buf, size, "union %s", type->ident->name);
 645                 else
 646                         return snprintf(buf, size, "anonymous union");
 647         } else if (type->type == SYM_FN) {
 648                 struct symbol *arg, *return_type, *arg_type;
 649                 int i;
 650
 651                 return_type = get_real_base_type(type);
 652                 n = type_str_helper(buf, size, return_type);
 653                 if (n > size)
 654                         return n;
 655                 n += snprintf(buf + n, size - n, "(*)(");
 656                 if (n > size)
 657                         return n;
 658
 659                 i = 0;
 660                 FOR_EACH_PTR(type->arguments, arg) {
 661                         if (i++)
 662                                 n += snprintf(buf + n, size - n, ", ");
 663                         if (n > size)
 664                                 return n;
 665                         arg_type = get_real_base_type(arg);
 666                         n += type_str_helper(buf + n, size - n, arg_type);
 667                         if (n > size)
 668                                 return n;
 669                 } END_FOR_EACH_PTR(arg);
 670
 671                 return n + snprintf(buf + n, size - n, ")");
 672         } else if (type->type == SYM_NODE) {
 673                 n = snprintf(buf, size, "node {");
 674                 if (n > size)
 675                         return n;
 676                 type = get_real_base_type(type);
 677                 n += type_str_helper(buf + n, size - n, type);
 678                 if (n > size)
 679                         return n;
 680                 return n + snprintf(buf + n, size - n, "}");
 681         } else {
 682                 return snprintf(buf, size, "<type %d>", type->type);
 683         }
 684 }
 685
 686 char *type_to_str(struct symbol *type)
 687 {
 688         static char buf[256];
 689
 690         buf[0] = '\0';
 691         type_str_helper(buf, sizeof(buf), type);
 692         return buf;
 693 }