smatch_helper.c

   1 /*
   2  * Copyright (C) 2006 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  * Miscellaneous helper functions.
  20  */
  21
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include "allocate.h"
  25 #include "smatch.h"
  26 #include "smatch_extra.h"
  27
  28 #define VAR_LEN 512
  29
  30 char *alloc_string(const char *str)
  31 {
  32         char *tmp;
  33
  34         if (!str)
  35                 return NULL;
  36         tmp = malloc(strlen(str) + 1);
  37         strcpy(tmp, str);
  38         return tmp;
  39 }
  40
  41 void free_string(char *str)
  42 {
  43         free(str);
  44 }
  45
  46 void remove_parens(char *str)
  47 {
  48         char *src, *dst;
  49
  50         dst = src = str;
  51         while (*src != '\0') {
  52                 if (*src == '(' || *src == ')') {
  53                         src++;
  54                         continue;
  55                 }
  56                 *dst++ = *src++;
  57         }
  58         *dst = *src;
  59 }
  60
  61 struct smatch_state *alloc_state_num(int num)
  62 {
  63         struct smatch_state *state;
  64         static char buff[256];
  65
  66         state = __alloc_smatch_state(0);
  67         snprintf(buff, 255, "%d", num);
  68         buff[255] = '\0';
  69         state->name = alloc_string(buff);
  70         state->data = INT_PTR(num);
  71         return state;
  72 }
  73
  74 void append(char *dest, const char *data, int buff_len)
  75 {
  76         strncat(dest, data, buff_len - strlen(dest) - 1);
  77 }
  78
  79 /*
  80  * If you have "foo(a, b, 1);" then use
  81  * get_argument_from_call_expr(expr, 0) to return the expression for
  82  * a.  Yes, it does start counting from 0.
  83  */
  84 struct expression *get_argument_from_call_expr(struct expression_list *args,
  85                                                int num)
  86 {
  87         struct expression *expr;
  88         int i = 0;
  89
  90         if (!args)
  91                 return NULL;
  92
  93         FOR_EACH_PTR(args, expr) {
  94                 if (i == num)
  95                         return expr;
  96                 i++;
  97         } END_FOR_EACH_PTR(expr);
  98         return NULL;
  99 }
 100
 101 static struct expression *get_array_expr(struct expression *expr)
 102 {
 103         struct symbol *type;
 104
 105         if (expr->type != EXPR_BINOP || expr->op != '+')
 106                 return NULL;
 107
 108         type = get_type(expr->left);
 109         if (!type || type->type != SYM_ARRAY)
 110                 return NULL;
 111         return expr->left;
 112 }
 113
 114 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 115                                      struct expression *expr, int len,
 116                                      int *complicated, int no_parens)
 117 {
 118         switch (expr->type) {
 119         case EXPR_DEREF: {
 120                 struct expression *deref;
 121                 int op;
 122
 123                 deref = expr->deref;
 124                 op = deref->op;
 125                 if (op == '*') {
 126                         struct expression *unop = strip_expr(deref->unop);
 127
 128                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 129                                 deref = unop->unop;
 130                                 op = '.';
 131                         } else {
 132                                 deref = deref->unop;
 133                         }
 134                 }
 135
 136                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 137
 138                 if (op == '*')
 139                         append(buf, "->", len);
 140                 else
 141                         append(buf, ".", len);
 142
 143                 if (expr->member)
 144                         append(buf, expr->member->name, len);
 145                 else
 146                         append(buf, "unknown_member", len);
 147
 148                 return;
 149         }
 150         case EXPR_SYMBOL:
 151                 if (expr->symbol_name)
 152                         append(buf, expr->symbol_name->name, len);
 153                 if (sym_ptr) {
 154                         if (*sym_ptr)
 155                                 *complicated = 1;
 156                         *sym_ptr = expr->symbol;
 157                 }
 158                 return;
 159         case EXPR_PREOP: {
 160                 const char *tmp;
 161
 162                 if (get_expression_statement(expr)) {
 163                         *complicated = 2;
 164                         return;
 165                 }
 166
 167                 if (expr->op == '(') {
 168                         if (!no_parens)
 169                                 append(buf, "(", len);
 170                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 171                         tmp = show_special(expr->op);
 172                         append(buf, tmp, len);
 173                 }
 174                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 175                                                  len, complicated, no_parens);
 176
 177                 if (expr->op == '(' && !no_parens)
 178                         append(buf, ")", len);
 179
 180                 if (expr->op == SPECIAL_DECREMENT ||
 181                                 expr->op == SPECIAL_INCREMENT)
 182                         *complicated = 1;
 183
 184                 return;
 185         }
 186         case EXPR_POSTOP: {
 187                 const char *tmp;
 188
 189                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 190                                                  len, complicated, no_parens);
 191                 tmp = show_special(expr->op);
 192                 append(buf, tmp, len);
 193
 194                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 195                         *complicated = 1;
 196                 return;
 197         }
 198         case EXPR_ASSIGNMENT:
 199         case EXPR_COMPARE:
 200         case EXPR_LOGICAL:
 201         case EXPR_BINOP: {
 202                 char tmp[10];
 203                 struct expression *array_expr;
 204
 205                 *complicated = 1;
 206                 array_expr = get_array_expr(expr);
 207                 if (array_expr) {
 208                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 209                         append(buf, "[", len);
 210                 } else {
 211                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 212                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 213                         append(buf, tmp, len);
 214                 }
 215                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 216                 if (array_expr)
 217                         append(buf, "]", len);
 218                 return;
 219         }
 220         case EXPR_VALUE: {
 221                 char tmp[25];
 222
 223                 *complicated = 1;
 224                 snprintf(tmp, 25, "%lld", expr->value);
 225                 append(buf, tmp, len);
 226                 return;
 227         }
 228         case EXPR_STRING:
 229                 append(buf, "\"", len);
 230                 if (expr->string)
 231                         append(buf, expr->string->data, len);
 232                 append(buf, "\"", len);
 233                 return;
 234         case EXPR_CALL: {
 235                 struct expression *tmp;
 236                 int i;
 237
 238                 *complicated = 1;
 239                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 240                 append(buf, "(", len);
 241                 i = 0;
 242                 FOR_EACH_PTR(expr->args, tmp) {
 243                         if (i++)
 244                                 append(buf, ", ", len);
 245                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 246                 } END_FOR_EACH_PTR(tmp);
 247                 append(buf, ")", len);
 248                 return;
 249         }
 250         case EXPR_CAST:
 251                 __get_variable_from_expr(sym_ptr, buf,
 252                                          expr->cast_expression, len,
 253                                          complicated, no_parens);
 254                 return;
 255         case EXPR_SIZEOF: {
 256                 int size;
 257                 char tmp[25];
 258
 259                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 260                         size = type_bytes(get_base_type(expr->cast_type));
 261                         snprintf(tmp, 25, "%d", size);
 262                         append(buf, tmp, len);
 263                 }
 264                 return;
 265         }
 266         case EXPR_IDENTIFIER:
 267                 *complicated = 1;
 268                 if (expr->expr_ident)
 269                         append(buf, expr->expr_ident->name, len);
 270                 return;
 271         default:
 272                 *complicated = 1;
 273                 //printf("unknown type = %d\n", expr->type);
 274                 return;
 275         }
 276 }
 277
 278 /*
 279  * This is returns a stylized "c looking" representation of the
 280  * variable name.
 281  *
 282  * It uses the same buffer every time so you have to save the result
 283  * yourself if you want to keep it.
 284  *
 285  */
 286
 287 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 288 {
 289         static char var_name[VAR_LEN];
 290         int complicated = 0;
 291
 292         if (sym_ptr)
 293                 *sym_ptr = NULL;
 294         var_name[0] = '\0';
 295
 296         if (!expr)
 297                 return NULL;
 298         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 299                                  &complicated, 0);
 300         if (complicated < 2)
 301                 return alloc_string(var_name);
 302         else
 303                 return NULL;
 304 }
 305
 306 char *expr_to_str(struct expression *expr)
 307 {
 308         return expr_to_str_sym(expr, NULL);
 309 }
 310
 311 /*
 312  * get_variable_from_expr_simple() only returns simple variables.
 313  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 314  * then it returns NULL.
 315  */
 316 char *expr_to_var_sym(struct expression *expr,
 317                                     struct symbol **sym_ptr)
 318 {
 319         static char var_name[VAR_LEN];
 320         int complicated = 0;
 321
 322         if (sym_ptr)
 323                 *sym_ptr = NULL;
 324         var_name[0] = '\0';
 325
 326         if (!expr)
 327                 return NULL;
 328         expr = strip_expr(expr);
 329         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 330                                  &complicated, 1);
 331
 332         if (complicated) {
 333                 if (sym_ptr)
 334                         *sym_ptr = NULL;
 335                 return NULL;
 336         }
 337         return alloc_string(var_name);
 338 }
 339
 340 char *expr_to_var(struct expression *expr)
 341 {
 342         return expr_to_var_sym(expr, NULL);
 343 }
 344
 345 int sym_name_is(const char *name, struct expression *expr)
 346 {
 347         if (!expr)
 348                 return 0;
 349         if (expr->type != EXPR_SYMBOL)
 350                 return 0;
 351         if (!strcmp(expr->symbol_name->name, name))
 352                 return 1;
 353         return 0;
 354 }
 355
 356 int is_zero(struct expression *expr)
 357 {
 358         sval_t sval;
 359
 360         if (get_value(expr, &sval) && sval.value == 0)
 361                 return 1;
 362         return 0;
 363 }
 364
 365 int is_array(struct expression *expr)
 366 {
 367         struct symbol *type;
 368
 369         expr = strip_expr(expr);
 370         if (!expr)
 371                 return 0;
 372
 373         if (expr->type == EXPR_PREOP || expr->op == '*') {
 374                 expr = strip_expr(expr->unop);
 375                 if (expr->type == EXPR_BINOP && expr->op == '+')
 376                         return 1;
 377         }
 378
 379         if (expr->type != EXPR_BINOP || expr->op != '+')
 380                 return 0;
 381
 382         type = get_type(expr->left);
 383         if (!type || type->type != SYM_ARRAY)
 384                 return 0;
 385
 386         return 1;
 387 }
 388
 389 struct expression *get_array_base(struct expression *expr)
 390 {
 391         if (!is_array(expr))
 392                 return NULL;
 393         expr = strip_expr(expr);
 394         if (expr->type == EXPR_PREOP && expr->op == '*')
 395                 expr = strip_expr(expr->unop);
 396         if (expr->type != EXPR_BINOP || expr->op != '+')
 397                 return NULL;
 398         return strip_parens(expr->left);
 399 }
 400
 401 struct expression *get_array_offset(struct expression *expr)
 402 {
 403         if (!is_array(expr))
 404                 return NULL;
 405         expr = strip_expr(expr);
 406         if (expr->type == EXPR_PREOP && expr->op == '*')
 407                 expr = strip_expr(expr->unop);
 408         if (expr->type != EXPR_BINOP || expr->op != '+')
 409                 return NULL;
 410         return strip_expr(expr->right);
 411 }
 412
 413 const char *show_state(struct smatch_state *state)
 414 {
 415         if (!state)
 416                 return NULL;
 417         return state->name;
 418 }
 419
 420 struct statement *get_expression_statement(struct expression *expr)
 421 {
 422         /* What are those things called? if (({....; ret;})) { ...*/
 423
 424         if (expr->type != EXPR_PREOP)
 425                 return NULL;
 426         if (expr->op != '(')
 427                 return NULL;
 428         if (expr->unop->type != EXPR_STATEMENT)
 429                 return NULL;
 430         if (expr->unop->statement->type != STMT_COMPOUND)
 431                 return NULL;
 432         return expr->unop->statement;
 433 }
 434
 435 struct expression *strip_parens(struct expression *expr)
 436 {
 437         if (!expr)
 438                 return NULL;
 439
 440         if (expr->type == EXPR_PREOP) {
 441                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 442                         expr->unop->statement->type == STMT_COMPOUND)
 443                         return expr;
 444                 if (expr->op == '(')
 445                         return strip_parens(expr->unop);
 446         }
 447         return expr;
 448 }
 449
 450 struct expression *strip_expr(struct expression *expr)
 451 {
 452         if (!expr)
 453                 return NULL;
 454
 455         switch (expr->type) {
 456         case EXPR_FORCE_CAST:
 457         case EXPR_CAST:
 458                 return strip_expr(expr->cast_expression);
 459         case EXPR_PREOP: {
 460                 struct expression *unop;
 461
 462                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 463                         expr->unop->statement->type == STMT_COMPOUND)
 464                         return expr;
 465
 466                 unop = strip_expr(expr->unop);
 467
 468                 if (expr->op == '*' &&
 469                     unop->type == EXPR_PREOP && unop->op == '&') {
 470                         struct symbol *type = get_type(unop->unop);
 471
 472                         if (type && type->type == SYM_ARRAY)
 473                                 return expr;
 474                         return strip_expr(unop->unop);
 475                 }
 476
 477                 if (expr->op == '(')
 478                         return unop;
 479
 480                 return expr;
 481         }
 482         case EXPR_CONDITIONAL:
 483                 if (known_condition_true(expr->conditional)) {
 484                         if (expr->cond_true)
 485                                 return strip_expr(expr->cond_true);
 486                         return strip_expr(expr->conditional);
 487                 }
 488                 if (known_condition_false(expr->conditional))
 489                         return strip_expr(expr->cond_false);
 490                 return expr;
 491         case EXPR_CALL:
 492                 if (sym_name_is("__builtin_expect", expr->fn)) {
 493                         expr = get_argument_from_call_expr(expr->args, 0);
 494                         return strip_expr(expr);
 495                 }
 496                 return expr;
 497         }
 498         return expr;
 499 }
 500
 501 static void delete_state_tracker(struct tracker *t)
 502 {
 503         delete_state(t->owner, t->name, t->sym);
 504         __free_tracker(t);
 505 }
 506
 507 void scoped_state(int my_id, const char *name, struct symbol *sym)
 508 {
 509         struct tracker *t;
 510
 511         t = alloc_tracker(my_id, name, sym);
 512         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 513 }
 514
 515 int is_error_return(struct expression *expr)
 516 {
 517         struct symbol *cur_func = cur_func_sym;
 518         sval_t sval;
 519
 520         if (!expr)
 521                 return 0;
 522         if (cur_func->type != SYM_NODE)
 523                 return 0;
 524         cur_func = get_base_type(cur_func);
 525         if (cur_func->type != SYM_FN)
 526                 return 0;
 527         cur_func = get_base_type(cur_func);
 528         if (cur_func == &void_ctype)
 529                 return 0;
 530         if (!get_implied_value(expr, &sval))
 531                 return 0;
 532         if (sval.value < 0)
 533                 return 1;
 534         if (cur_func->type == SYM_PTR && sval.value == 0)
 535                 return 1;
 536         return 0;
 537 }
 538
 539 int getting_address(void)
 540 {
 541         struct expression *tmp;
 542         int i = 0;
 543         int dot_ops = 0;
 544
 545         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 546                 if (!i++)
 547                         continue;
 548                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 549                         continue;
 550                 if (tmp->op == '.' && !dot_ops++)
 551                         continue;
 552                 if (tmp->op == '&')
 553                         return 1;
 554                 return 0;
 555         } END_FOR_EACH_PTR_REVERSE(tmp);
 556         return 0;
 557 }
 558
 559 char *get_member_name(struct expression *expr)
 560 {
 561         char buf[256];
 562         struct symbol *sym;
 563
 564         expr = strip_expr(expr);
 565         if (expr->type != EXPR_DEREF)
 566                 return NULL;
 567         sym = get_type(expr->deref);
 568         if (!sym)
 569                 return NULL;
 570         /* FIXME: HACK! Sparse isn't storing the names of unions...  Just take last member */
 571         if (sym->type == SYM_UNION) {
 572                 struct symbol *tmp;
 573
 574                 FOR_EACH_PTR_REVERSE(sym->symbol_list, tmp) {
 575                         if (tmp->ident) {
 576                                 const char *member_name;
 577
 578                                 if (expr->member)
 579                                         member_name = expr->member->name;
 580                                 else
 581                                         member_name = "unknown_member";
 582                                 snprintf(buf, sizeof(buf), "(union hack %s)->%s", tmp->ident->name, member_name);
 583                                 return alloc_string(buf);
 584                         }
 585                 } END_FOR_EACH_PTR_REVERSE(tmp);
 586                 return NULL;
 587         }
 588         if (!sym->ident || !expr->member)
 589                 return NULL;
 590         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 591         return alloc_string(buf);
 592 }
 593
 594 int cmp_pos(struct position pos1, struct position pos2)
 595 {
 596         /* the stream position is ... */
 597         if (pos1.stream > pos2.stream)
 598                 return -1;
 599         if (pos1.stream < pos2.stream)
 600                 return 1;
 601
 602         if (pos1.line < pos2.line)
 603                 return -1;
 604         if (pos1.line > pos2.line)
 605                 return 1;
 606
 607         if (pos1.pos < pos2.pos)
 608                 return -1;
 609         if (pos1.pos > pos2.pos)
 610                 return 1;
 611
 612         return 0;
 613 }
 614
 615 int positions_eq(struct position pos1, struct position pos2)
 616 {
 617         if (pos1.line != pos2.line)
 618                 return 0;
 619         if (pos1.pos != pos2.pos)
 620                 return 0;
 621         if (pos1.stream != pos2.stream)
 622                 return 0;
 623         return 1;
 624 }
 625
 626 struct statement *get_current_statement(void)
 627 {
 628         struct statement *prev, *tmp;
 629
 630         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 631
 632         if (!prev || !get_macro_name(prev->pos))
 633                 return prev;
 634
 635         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 636                 if (positions_eq(tmp->pos, prev->pos))
 637                         continue;
 638                 if (prev->pos.line > tmp->pos.line)
 639                         return prev;
 640                 return tmp;
 641         } END_FOR_EACH_PTR_REVERSE(tmp);
 642         return prev;
 643 }
 644
 645 struct statement *get_prev_statement(void)
 646 {
 647         struct statement *tmp;
 648         int i;
 649
 650         i = 0;
 651         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 652                 if (i++ == 1)
 653                         return tmp;
 654         } END_FOR_EACH_PTR_REVERSE(tmp);
 655         return NULL;
 656 }
 657
 658 int get_param_num_from_sym(struct symbol *sym)
 659 {
 660         struct symbol *tmp;
 661         int i;
 662
 663         if (!cur_func_sym)
 664                 return -1;
 665
 666         i = 0;
 667         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 668                 if (tmp == sym)
 669                         return i;
 670                 i++;
 671         } END_FOR_EACH_PTR(tmp);
 672         return -1;
 673 }
 674
 675 int get_param_num(struct expression *expr)
 676 {
 677         struct symbol *sym;
 678         char *name;
 679
 680         if (!cur_func_sym)
 681                 return -1;
 682         name = expr_to_var_sym(expr, &sym);
 683         free_string(name);
 684         if (!sym)
 685                 return -1;
 686         return get_param_num_from_sym(sym);
 687 }
 688
 689 int ms_since(struct timeval *start)
 690 {
 691         struct timeval end;
 692         double diff;
 693
 694         gettimeofday(&end, NULL);
 695         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 696         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 697         return (int)diff;
 698 }
 699
 700 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 701 {
 702         if (!name || !sym)
 703                 return 0;
 704
 705         if (parent_is_null_var_sym(name, sym) ||
 706             parent_is_free_var_sym(name, sym))
 707                 return 1;
 708         return 0;
 709 }
 710
 711 int parent_is_gone(struct expression *expr)
 712 {
 713         struct symbol *sym;
 714         char *var;
 715         int ret = 0;
 716
 717         expr = strip_expr(expr);
 718         var = expr_to_var_sym(expr, &sym);
 719         if (!var || !sym)
 720                 goto free;
 721         ret = parent_is_gone_var_sym(var, sym);
 722 free:
 723         free_string(var);
 724         return ret;
 725 }