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         if (!left)
  75                 return NULL;
  76
  77         if (expr->op == SPECIAL_LEFTSHIFT ||
  78             expr->op == SPECIAL_RIGHTSHIFT) {
  79                 if (type_positive_bits(left) < 31)
  80                         return &int_ctype;
  81                 return left;
  82         }
  83         if (left->type == SYM_PTR || left->type == SYM_ARRAY)
  84                 return left;
  85
  86         right = get_type(expr->right);
  87         if (!right)
  88                 return NULL;
  89
  90         if (right->type == SYM_PTR || right->type == SYM_ARRAY)
  91                 return right;
  92
  93         if (type_positive_bits(left) < 31 && type_positive_bits(right) < 31)
  94                 return &int_ctype;
  95
  96         if (type_positive_bits(left) > type_positive_bits(right))
  97                 return left;
  98         return right;
  99 }
 100
 101 static struct symbol *get_type_symbol(struct expression *expr)
 102 {
 103         if (!expr || expr->type != EXPR_SYMBOL || !expr->symbol)
 104                 return NULL;
 105
 106         return get_real_base_type(expr->symbol);
 107 }
 108
 109 static struct symbol *get_member_symbol(struct symbol_list *symbol_list, struct ident *member)
 110 {
 111         struct symbol *tmp, *sub;
 112
 113         FOR_EACH_PTR(symbol_list, tmp) {
 114                 if (!tmp->ident) {
 115                         sub = get_real_base_type(tmp);
 116                         sub = get_member_symbol(sub->symbol_list, member);
 117                         if (sub)
 118                                 return sub;
 119                         continue;
 120                 }
 121                 if (tmp->ident == member)
 122                         return tmp;
 123         } END_FOR_EACH_PTR(tmp);
 124
 125         return NULL;
 126 }
 127
 128 static struct symbol *get_symbol_from_deref(struct expression *expr)
 129 {
 130         struct ident *member;
 131         struct symbol *sym;
 132
 133         if (!expr || expr->type != EXPR_DEREF)
 134                 return NULL;
 135
 136         member = expr->member;
 137         sym = get_type(expr->deref);
 138         if (!sym) {
 139                 // sm_msg("could not find struct type");
 140                 return NULL;
 141         }
 142         if (sym->type == SYM_PTR)
 143                 sym = get_real_base_type(sym);
 144         sym = get_member_symbol(sym->symbol_list, member);
 145         if (!sym)
 146                 return NULL;
 147         return get_real_base_type(sym);
 148 }
 149
 150 static struct symbol *get_return_type(struct expression *expr)
 151 {
 152         struct symbol *tmp;
 153
 154         tmp = get_type(expr->fn);
 155         if (!tmp)
 156                 return NULL;
 157         return get_real_base_type(tmp);
 158 }
 159
 160 static struct symbol *get_expr_stmt_type(struct statement *stmt)
 161 {
 162         if (stmt->type != STMT_COMPOUND)
 163                 return NULL;
 164         stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 165         if (!stmt || stmt->type != STMT_EXPRESSION)
 166                 return NULL;
 167         return get_type(stmt->expression);
 168 }
 169
 170 static struct symbol *get_select_type(struct expression *expr)
 171 {
 172         struct symbol *one, *two;
 173
 174         one = get_type(expr->cond_true);
 175         two = get_type(expr->cond_false);
 176         if (!one || !two)
 177                 return NULL;
 178         /*
 179          * This is a hack.  If the types are not equiv then we
 180          * really don't know the type.  But I think guessing is
 181          *  probably Ok here.
 182          */
 183         if (type_positive_bits(one) > type_positive_bits(two))
 184                 return one;
 185         return two;
 186 }
 187
 188 struct symbol *get_pointer_type(struct expression *expr)
 189 {
 190         struct symbol *sym;
 191
 192         sym = get_type(expr);
 193         if (!sym)
 194                 return NULL;
 195         if (sym->type == SYM_NODE) {
 196                 sym = get_real_base_type(sym);
 197                 if (!sym)
 198                         return NULL;
 199         }
 200         if (sym->type != SYM_PTR && sym->type != SYM_ARRAY)
 201                 return NULL;
 202         return get_real_base_type(sym);
 203 }
 204
 205 static struct symbol *fake_pointer_sym(struct expression *expr)
 206 {
 207         struct symbol *sym;
 208         struct symbol *base;
 209
 210         sym = alloc_symbol(expr->pos, SYM_PTR);
 211         expr = expr->unop;
 212         base = get_type(expr);
 213         if (!base)
 214                 return NULL;
 215         sym->ctype.base_type = base;
 216         return sym;
 217 }
 218
 219 struct symbol *get_type(struct expression *expr)
 220 {
 221         struct symbol *ret;
 222
 223         expr = strip_parens(expr);
 224         if (!expr)
 225                 return NULL;
 226
 227         if (expr->ctype)
 228                 return expr->ctype;
 229
 230         switch (expr->type) {
 231         case EXPR_STRING:
 232                 ret = &string_ctype;
 233                 break;
 234         case EXPR_SYMBOL:
 235                 ret = get_type_symbol(expr);
 236                 break;
 237         case EXPR_DEREF:
 238                 ret = get_symbol_from_deref(expr);
 239                 break;
 240         case EXPR_PREOP:
 241         case EXPR_POSTOP:
 242                 if (expr->op == '&')
 243                         ret = fake_pointer_sym(expr);
 244                 else if (expr->op == '*')
 245                         ret = get_pointer_type(expr->unop);
 246                 else
 247                         ret = get_type(expr->unop);
 248                 break;
 249         case EXPR_ASSIGNMENT:
 250                 ret = get_type(expr->left);
 251                 break;
 252         case EXPR_CAST:
 253         case EXPR_FORCE_CAST:
 254         case EXPR_IMPLIED_CAST:
 255                 ret = get_real_base_type(expr->cast_type);
 256                 break;
 257         case EXPR_COMPARE:
 258         case EXPR_BINOP:
 259                 ret = get_binop_type(expr);
 260                 break;
 261         case EXPR_CALL:
 262                 ret = get_return_type(expr);
 263                 break;
 264         case EXPR_STATEMENT:
 265                 ret = get_expr_stmt_type(expr->statement);
 266                 break;
 267         case EXPR_CONDITIONAL:
 268         case EXPR_SELECT:
 269                 ret = get_select_type(expr);
 270                 break;
 271         case EXPR_SIZEOF:
 272                 ret = &ulong_ctype;
 273                 break;
 274         case EXPR_LOGICAL:
 275                 ret = &int_ctype;
 276                 break;
 277         default:
 278                 return NULL;
 279         }
 280
 281         expr->ctype = ret;
 282         return ret;
 283 }
 284
 285 int type_unsigned(struct symbol *base_type)
 286 {
 287         if (!base_type)
 288                 return 0;
 289         if (base_type->ctype.modifiers & MOD_UNSIGNED)
 290                 return 1;
 291         return 0;
 292 }
 293
 294 int type_signed(struct symbol *base_type)
 295 {
 296         if (!base_type)
 297                 return 0;
 298         if (base_type->ctype.modifiers & MOD_SIGNED)
 299                 return 1;
 300         return 0;
 301 }
 302
 303 int expr_unsigned(struct expression *expr)
 304 {
 305         struct symbol *sym;
 306
 307         sym = get_type(expr);
 308         if (!sym)
 309                 return 0;
 310         if (type_unsigned(sym))
 311                 return 1;
 312         return 0;
 313 }
 314
 315 int expr_signed(struct expression *expr)
 316 {
 317         struct symbol *sym;
 318
 319         sym = get_type(expr);
 320         if (!sym)
 321                 return 0;
 322         if (type_signed(sym))
 323                 return 1;
 324         return 0;
 325 }
 326
 327 int returns_unsigned(struct symbol *sym)
 328 {
 329         if (!sym)
 330                 return 0;
 331         sym = get_base_type(sym);
 332         if (!sym || sym->type != SYM_FN)
 333                 return 0;
 334         sym = get_base_type(sym);
 335         return type_unsigned(sym);
 336 }
 337
 338 int is_pointer(struct expression *expr)
 339 {
 340         struct symbol *sym;
 341
 342         sym = get_type(expr);
 343         if (!sym)
 344                 return 0;
 345         if (sym == &string_ctype)
 346                 return 0;
 347         if (sym->type == SYM_PTR)
 348                 return 1;
 349         return 0;
 350 }
 351
 352 int returns_pointer(struct symbol *sym)
 353 {
 354         if (!sym)
 355                 return 0;
 356         sym = get_base_type(sym);
 357         if (!sym || sym->type != SYM_FN)
 358                 return 0;
 359         sym = get_base_type(sym);
 360         if (sym->type == SYM_PTR)
 361                 return 1;
 362         return 0;
 363 }
 364
 365 sval_t sval_type_max(struct symbol *base_type)
 366 {
 367         sval_t ret;
 368
 369         if (!base_type || !type_bits(base_type))
 370                 base_type = &llong_ctype;
 371         ret.type = base_type;
 372
 373         ret.value = (~0ULL) >> (64 - type_positive_bits(base_type));
 374         return ret;
 375 }
 376
 377 sval_t sval_type_min(struct symbol *base_type)
 378 {
 379         sval_t ret;
 380
 381         if (!base_type || !type_bits(base_type))
 382                 base_type = &llong_ctype;
 383         ret.type = base_type;
 384
 385         if (type_unsigned(base_type)) {
 386                 ret.value = 0;
 387                 return ret;
 388         }
 389
 390         ret.value = (~0ULL) << type_positive_bits(base_type);
 391
 392         return ret;
 393 }
 394
 395 int nr_bits(struct expression *expr)
 396 {
 397         struct symbol *type;
 398
 399         type = get_type(expr);
 400         if (!type)
 401                 return 0;
 402         return type_bits(type);
 403 }
 404
 405 int is_void_pointer(struct expression *expr)
 406 {
 407         struct symbol *type;
 408
 409         type = get_type(expr);
 410         if (!type || type->type != SYM_PTR)
 411                 return 0;
 412         type = get_real_base_type(type);
 413         if (type == &void_ctype)
 414                 return 1;
 415         return 0;
 416 }
 417
 418 int is_char_pointer(struct expression *expr)
 419 {
 420         struct symbol *type;
 421
 422         type = get_type(expr);
 423         if (!type || type->type != SYM_PTR)
 424                 return 0;
 425         type = get_real_base_type(type);
 426         if (type == &char_ctype)
 427                 return 1;
 428         return 0;
 429 }
 430
 431 int is_string(struct expression *expr)
 432 {
 433         expr = strip_expr(expr);
 434         if (!expr || expr->type != EXPR_STRING)
 435                 return 0;
 436         if (expr->string)
 437                 return 1;
 438         return 0;
 439 }
 440
 441 int is_static(struct expression *expr)
 442 {
 443         char *name;
 444         struct symbol *sym;
 445         int ret = 0;
 446
 447         name = expr_to_str_sym(expr, &sym);
 448         if (!name || !sym)
 449                 goto free;
 450
 451         if (sym->ctype.modifiers & MOD_STATIC)
 452                 ret = 1;
 453 free:
 454         free_string(name);
 455         return ret;
 456 }
 457
 458 int types_equiv(struct symbol *one, struct symbol *two)
 459 {
 460         if (!one && !two)
 461                 return 1;
 462         if (!one || !two)
 463                 return 0;
 464         if (one->type != two->type)
 465                 return 0;
 466         if (one->type == SYM_PTR)
 467                 return types_equiv(get_real_base_type(one), get_real_base_type(two));
 468         if (type_positive_bits(one) != type_positive_bits(two))
 469                 return 0;
 470         return 1;
 471 }
 472
 473 int fn_static(void)
 474 {
 475         return !!(cur_func_sym->ctype.modifiers & MOD_STATIC);
 476 }
 477
 478 const char *global_static(void)
 479 {
 480         if (cur_func_sym->ctype.modifiers & MOD_STATIC)
 481                 return "static";
 482         else
 483                 return "global";
 484 }
 485
 486 struct symbol *cur_func_return_type(void)
 487 {
 488         struct symbol *sym;
 489
 490         sym = get_real_base_type(cur_func_sym);
 491         if (!sym || sym->type != SYM_FN)
 492                 return NULL;
 493         sym = get_real_base_type(sym);
 494         return sym;
 495 }
 496
 497 struct symbol *get_arg_type(struct expression *fn, int arg)
 498 {
 499         struct symbol *fn_type;
 500         struct symbol *tmp;
 501         struct symbol *arg_type;
 502         int i;
 503
 504         fn_type = get_type(fn);
 505         if (!fn_type)
 506                 return NULL;
 507         if (fn_type->type == SYM_PTR)
 508                 fn_type = get_real_base_type(fn_type);
 509         if (fn_type->type != SYM_FN)
 510                 return NULL;
 511
 512         i = 0;
 513         FOR_EACH_PTR(fn_type->arguments, tmp) {
 514                 arg_type = get_real_base_type(tmp);
 515                 if (i == arg) {
 516                         return arg_type;
 517                 }
 518                 i++;
 519         } END_FOR_EACH_PTR(tmp);
 520
 521         return NULL;
 522 }
 523
 524 static struct symbol *get_member_from_string(struct symbol_list *symbol_list, char *name)
 525 {
 526         struct symbol *tmp, *sub;
 527         int chunk_len;
 528
 529         if (strncmp(name, ".", 1) == 0)
 530                 name += 1;
 531         if (strncmp(name, "->", 2) == 0)
 532                 name += 2;
 533
 534         FOR_EACH_PTR(symbol_list, tmp) {
 535                 if (!tmp->ident) {
 536                         sub = get_real_base_type(tmp);
 537                         sub = get_member_from_string(sub->symbol_list, name);
 538                         if (sub)
 539                                 return sub;
 540                         continue;
 541                 }
 542
 543                 if (strcmp(tmp->ident->name, name) == 0)
 544                         return tmp;
 545
 546                 chunk_len = strlen(tmp->ident->name);
 547                 if (strncmp(tmp->ident->name, name, chunk_len) == 0 &&
 548                     (name[chunk_len] == '.' || name[chunk_len] == '-')) {
 549                         sub = get_real_base_type(tmp);
 550                         return get_member_from_string(sub->symbol_list, name + chunk_len);
 551                 }
 552
 553         } END_FOR_EACH_PTR(tmp);
 554
 555         return NULL;
 556 }
 557
 558 struct symbol *get_member_type_from_key(struct expression *expr, char *key)
 559 {
 560         struct symbol *sym;
 561         char *name;
 562
 563         if (strcmp(key, "$") == 0)
 564                 return get_type(expr);
 565
 566         if (strcmp(key, "*$") == 0) {
 567                 sym = get_type(expr);
 568                 if (!sym || sym->type != SYM_PTR)
 569                         return NULL;
 570                 return get_real_base_type(sym);
 571         }
 572
 573         name = expr_to_str_sym(expr, &sym);
 574         free_string(name);
 575         if (!sym)
 576                 return NULL;
 577         sym = get_real_base_type(sym);
 578         if (sym->type == SYM_PTR)
 579                 sym = get_real_base_type(sym);
 580
 581         key = key + 1;
 582         sym = get_member_from_string(sym->symbol_list, key);
 583         if (!sym)
 584                 return NULL;
 585         return get_real_base_type(sym);
 586 }
 587
 588 int is_struct(struct expression *expr)
 589 {
 590         struct symbol *type;
 591
 592         type = get_type(expr);
 593         if (type && type->type == SYM_STRUCT)
 594                 return 1;
 595         return 0;
 596 }
 597
 598 static struct {
 599         struct symbol *sym;
 600         const char *name;
 601 } base_types[] = {
 602         {&bool_ctype, "bool"},
 603         {&void_ctype, "void"},
 604         {&type_ctype, "type"},
 605         {&char_ctype, "char"},
 606         {&schar_ctype, "schar"},
 607         {&uchar_ctype, "uchar"},
 608         {&short_ctype, "short"},
 609         {&sshort_ctype, "sshort"},
 610         {&ushort_ctype, "ushort"},
 611         {&int_ctype, "int"},
 612         {&sint_ctype, "sint"},
 613         {&uint_ctype, "uint"},
 614         {&long_ctype, "long"},
 615         {&slong_ctype, "slong"},
 616         {&ulong_ctype, "ulong"},
 617         {&llong_ctype, "llong"},
 618         {&sllong_ctype, "sllong"},
 619         {&ullong_ctype, "ullong"},
 620         {&lllong_ctype, "lllong"},
 621         {&slllong_ctype, "slllong"},
 622         {&ulllong_ctype, "ulllong"},
 623         {&float_ctype, "float"},
 624         {&double_ctype, "double"},
 625         {&ldouble_ctype, "ldouble"},
 626         {&string_ctype, "string"},
 627         {&ptr_ctype, "ptr"},
 628         {&lazy_ptr_ctype, "lazy_ptr"},
 629         {&incomplete_ctype, "incomplete"},
 630         {&label_ctype, "label"},
 631         {&bad_ctype, "bad"},
 632         {&null_ctype, "null"},
 633 };
 634
 635 static const char *base_type_str(struct symbol *sym)
 636 {
 637         int i;
 638
 639         for (i = 0; i < ARRAY_SIZE(base_types); i++) {
 640                 if (sym == base_types[i].sym)
 641                         return base_types[i].name;
 642         }
 643         return "<unknown>";
 644 }
 645
 646 static int type_str_helper(char *buf, int size, struct symbol *type)
 647 {
 648         int n;
 649
 650         if (!type)
 651                 return snprintf(buf, size, "<unknown>");
 652
 653         if (type->type == SYM_BASETYPE) {
 654                 return snprintf(buf, size, base_type_str(type));
 655         } else if (type->type == SYM_PTR) {
 656                 type = get_real_base_type(type);
 657                 n = type_str_helper(buf, size, type);
 658                 if (n > size)
 659                         return n;
 660                 return n + snprintf(buf + n, size - n, "*");
 661         } else if (type->type == SYM_STRUCT) {
 662                 return snprintf(buf, size, "struct %s", type->ident ? type->ident->name : "");
 663         } else if (type->type == SYM_UNION) {
 664                 if (type->ident)
 665                         return snprintf(buf, size, "union %s", type->ident->name);
 666                 else
 667                         return snprintf(buf, size, "anonymous union");
 668         } else if (type->type == SYM_FN) {
 669                 struct symbol *arg, *return_type, *arg_type;
 670                 int i;
 671
 672                 return_type = get_real_base_type(type);
 673                 n = type_str_helper(buf, size, return_type);
 674                 if (n > size)
 675                         return n;
 676                 n += snprintf(buf + n, size - n, "(*)(");
 677                 if (n > size)
 678                         return n;
 679
 680                 i = 0;
 681                 FOR_EACH_PTR(type->arguments, arg) {
 682                         if (i++)
 683                                 n += snprintf(buf + n, size - n, ", ");
 684                         if (n > size)
 685                                 return n;
 686                         arg_type = get_real_base_type(arg);
 687                         n += type_str_helper(buf + n, size - n, arg_type);
 688                         if (n > size)
 689                                 return n;
 690                 } END_FOR_EACH_PTR(arg);
 691
 692                 return n + snprintf(buf + n, size - n, ")");
 693         } else if (type->type == SYM_NODE) {
 694                 n = snprintf(buf, size, "node {");
 695                 if (n > size)
 696                         return n;
 697                 type = get_real_base_type(type);
 698                 n += type_str_helper(buf + n, size - n, type);
 699                 if (n > size)
 700                         return n;
 701                 return n + snprintf(buf + n, size - n, "}");
 702         } else {
 703                 return snprintf(buf, size, "<type %d>", type->type);
 704         }
 705 }
 706
 707 char *type_to_str(struct symbol *type)
 708 {
 709         static char buf[256];
 710
 711         buf[0] = '\0';
 712         type_str_helper(buf, sizeof(buf), type);
 713         return buf;
 714 }