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 struct symbol *expr_to_sym(struct expression *expr)
 346 {
 347         struct symbol *sym;
 348         char *name;
 349
 350         name = expr_to_var_sym(expr, &sym);
 351         free_string(name);
 352         return sym;
 353 }
 354
 355 int sym_name_is(const char *name, struct expression *expr)
 356 {
 357         if (!expr)
 358                 return 0;
 359         if (expr->type != EXPR_SYMBOL)
 360                 return 0;
 361         if (!strcmp(expr->symbol_name->name, name))
 362                 return 1;
 363         return 0;
 364 }
 365
 366 int is_zero(struct expression *expr)
 367 {
 368         sval_t sval;
 369
 370         if (get_value(expr, &sval) && sval.value == 0)
 371                 return 1;
 372         return 0;
 373 }
 374
 375 int is_array(struct expression *expr)
 376 {
 377         struct symbol *type;
 378
 379         expr = strip_expr(expr);
 380         if (!expr)
 381                 return 0;
 382
 383         if (expr->type == EXPR_PREOP && expr->op == '*') {
 384                 expr = strip_expr(expr->unop);
 385                 if (expr->type == EXPR_BINOP && expr->op == '+')
 386                         return 1;
 387         }
 388
 389         if (expr->type != EXPR_BINOP || expr->op != '+')
 390                 return 0;
 391
 392         type = get_type(expr->left);
 393         if (!type || type->type != SYM_ARRAY)
 394                 return 0;
 395
 396         return 1;
 397 }
 398
 399 struct expression *get_array_base(struct expression *expr)
 400 {
 401         if (!is_array(expr))
 402                 return NULL;
 403         expr = strip_expr(expr);
 404         if (expr->type == EXPR_PREOP && expr->op == '*')
 405                 expr = strip_expr(expr->unop);
 406         if (expr->type != EXPR_BINOP || expr->op != '+')
 407                 return NULL;
 408         return strip_parens(expr->left);
 409 }
 410
 411 struct expression *get_array_offset(struct expression *expr)
 412 {
 413         if (!is_array(expr))
 414                 return NULL;
 415         expr = strip_expr(expr);
 416         if (expr->type == EXPR_PREOP && expr->op == '*')
 417                 expr = strip_expr(expr->unop);
 418         if (expr->type != EXPR_BINOP || expr->op != '+')
 419                 return NULL;
 420         return strip_expr(expr->right);
 421 }
 422
 423 const char *show_state(struct smatch_state *state)
 424 {
 425         if (!state)
 426                 return NULL;
 427         return state->name;
 428 }
 429
 430 struct statement *get_expression_statement(struct expression *expr)
 431 {
 432         /* What are those things called? if (({....; ret;})) { ...*/
 433
 434         if (expr->type != EXPR_PREOP)
 435                 return NULL;
 436         if (expr->op != '(')
 437                 return NULL;
 438         if (expr->unop->type != EXPR_STATEMENT)
 439                 return NULL;
 440         if (expr->unop->statement->type != STMT_COMPOUND)
 441                 return NULL;
 442         return expr->unop->statement;
 443 }
 444
 445 struct expression *strip_parens(struct expression *expr)
 446 {
 447         if (!expr)
 448                 return NULL;
 449
 450         if (expr->type == EXPR_PREOP) {
 451                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 452                         expr->unop->statement->type == STMT_COMPOUND)
 453                         return expr;
 454                 if (expr->op == '(')
 455                         return strip_parens(expr->unop);
 456         }
 457         return expr;
 458 }
 459
 460 struct expression *strip_expr(struct expression *expr)
 461 {
 462         if (!expr)
 463                 return NULL;
 464
 465         switch (expr->type) {
 466         case EXPR_FORCE_CAST:
 467         case EXPR_CAST:
 468                 return strip_expr(expr->cast_expression);
 469         case EXPR_PREOP: {
 470                 struct expression *unop;
 471
 472                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 473                         expr->unop->statement->type == STMT_COMPOUND)
 474                         return expr;
 475
 476                 unop = strip_expr(expr->unop);
 477
 478                 if (expr->op == '*' &&
 479                     unop->type == EXPR_PREOP && unop->op == '&') {
 480                         struct symbol *type = get_type(unop->unop);
 481
 482                         if (type && type->type == SYM_ARRAY)
 483                                 return expr;
 484                         return strip_expr(unop->unop);
 485                 }
 486
 487                 if (expr->op == '(')
 488                         return unop;
 489
 490                 return expr;
 491         }
 492         case EXPR_CONDITIONAL:
 493                 if (known_condition_true(expr->conditional)) {
 494                         if (expr->cond_true)
 495                                 return strip_expr(expr->cond_true);
 496                         return strip_expr(expr->conditional);
 497                 }
 498                 if (known_condition_false(expr->conditional))
 499                         return strip_expr(expr->cond_false);
 500                 return expr;
 501         case EXPR_CALL:
 502                 if (sym_name_is("__builtin_expect", expr->fn)) {
 503                         expr = get_argument_from_call_expr(expr->args, 0);
 504                         return strip_expr(expr);
 505                 }
 506                 return expr;
 507         }
 508         return expr;
 509 }
 510
 511 static void delete_state_tracker(struct tracker *t)
 512 {
 513         delete_state(t->owner, t->name, t->sym);
 514         __free_tracker(t);
 515 }
 516
 517 void scoped_state(int my_id, const char *name, struct symbol *sym)
 518 {
 519         struct tracker *t;
 520
 521         t = alloc_tracker(my_id, name, sym);
 522         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 523 }
 524
 525 int is_error_return(struct expression *expr)
 526 {
 527         struct symbol *cur_func = cur_func_sym;
 528         sval_t sval;
 529
 530         if (!expr)
 531                 return 0;
 532         if (cur_func->type != SYM_NODE)
 533                 return 0;
 534         cur_func = get_base_type(cur_func);
 535         if (cur_func->type != SYM_FN)
 536                 return 0;
 537         cur_func = get_base_type(cur_func);
 538         if (cur_func == &void_ctype)
 539                 return 0;
 540         if (!get_implied_value(expr, &sval))
 541                 return 0;
 542         if (sval.value < 0)
 543                 return 1;
 544         if (cur_func->type == SYM_PTR && sval.value == 0)
 545                 return 1;
 546         return 0;
 547 }
 548
 549 int getting_address(void)
 550 {
 551         struct expression *tmp;
 552         int i = 0;
 553         int dot_ops = 0;
 554
 555         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 556                 if (!i++)
 557                         continue;
 558                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 559                         continue;
 560                 if (tmp->op == '.' && !dot_ops++)
 561                         continue;
 562                 if (tmp->op == '&')
 563                         return 1;
 564                 return 0;
 565         } END_FOR_EACH_PTR_REVERSE(tmp);
 566         return 0;
 567 }
 568
 569 char *get_member_name(struct expression *expr)
 570 {
 571         char buf[256];
 572         struct symbol *sym;
 573
 574         expr = strip_expr(expr);
 575         if (expr->type != EXPR_DEREF)
 576                 return NULL;
 577         sym = get_type(expr->deref);
 578         if (!sym)
 579                 return NULL;
 580         /* FIXME: HACK! Sparse isn't storing the names of unions...  Just take last member */
 581         if (sym->type == SYM_UNION) {
 582                 struct symbol *tmp;
 583
 584                 FOR_EACH_PTR_REVERSE(sym->symbol_list, tmp) {
 585                         if (tmp->ident) {
 586                                 const char *member_name;
 587
 588                                 if (expr->member)
 589                                         member_name = expr->member->name;
 590                                 else
 591                                         member_name = "unknown_member";
 592                                 snprintf(buf, sizeof(buf), "(union hack %s)->%s", tmp->ident->name, member_name);
 593                                 return alloc_string(buf);
 594                         }
 595                 } END_FOR_EACH_PTR_REVERSE(tmp);
 596                 return NULL;
 597         }
 598         if (!sym->ident || !expr->member)
 599                 return NULL;
 600         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 601         return alloc_string(buf);
 602 }
 603
 604 int cmp_pos(struct position pos1, struct position pos2)
 605 {
 606         /* the stream position is ... */
 607         if (pos1.stream > pos2.stream)
 608                 return -1;
 609         if (pos1.stream < pos2.stream)
 610                 return 1;
 611
 612         if (pos1.line < pos2.line)
 613                 return -1;
 614         if (pos1.line > pos2.line)
 615                 return 1;
 616
 617         if (pos1.pos < pos2.pos)
 618                 return -1;
 619         if (pos1.pos > pos2.pos)
 620                 return 1;
 621
 622         return 0;
 623 }
 624
 625 int positions_eq(struct position pos1, struct position pos2)
 626 {
 627         if (pos1.line != pos2.line)
 628                 return 0;
 629         if (pos1.pos != pos2.pos)
 630                 return 0;
 631         if (pos1.stream != pos2.stream)
 632                 return 0;
 633         return 1;
 634 }
 635
 636 struct statement *get_current_statement(void)
 637 {
 638         struct statement *prev, *tmp;
 639
 640         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 641
 642         if (!prev || !get_macro_name(prev->pos))
 643                 return prev;
 644
 645         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 646                 if (positions_eq(tmp->pos, prev->pos))
 647                         continue;
 648                 if (prev->pos.line > tmp->pos.line)
 649                         return prev;
 650                 return tmp;
 651         } END_FOR_EACH_PTR_REVERSE(tmp);
 652         return prev;
 653 }
 654
 655 struct statement *get_prev_statement(void)
 656 {
 657         struct statement *tmp;
 658         int i;
 659
 660         i = 0;
 661         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 662                 if (i++ == 1)
 663                         return tmp;
 664         } END_FOR_EACH_PTR_REVERSE(tmp);
 665         return NULL;
 666 }
 667
 668 int get_param_num_from_sym(struct symbol *sym)
 669 {
 670         struct symbol *tmp;
 671         int i;
 672
 673         if (!cur_func_sym)
 674                 return -1;
 675
 676         i = 0;
 677         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 678                 if (tmp == sym)
 679                         return i;
 680                 i++;
 681         } END_FOR_EACH_PTR(tmp);
 682         return -1;
 683 }
 684
 685 int get_param_num(struct expression *expr)
 686 {
 687         struct symbol *sym;
 688         char *name;
 689
 690         if (!cur_func_sym)
 691                 return -1;
 692         name = expr_to_var_sym(expr, &sym);
 693         free_string(name);
 694         if (!sym)
 695                 return -1;
 696         return get_param_num_from_sym(sym);
 697 }
 698
 699 int ms_since(struct timeval *start)
 700 {
 701         struct timeval end;
 702         double diff;
 703
 704         gettimeofday(&end, NULL);
 705         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 706         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 707         return (int)diff;
 708 }
 709
 710 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 711 {
 712         if (!name || !sym)
 713                 return 0;
 714
 715         if (parent_is_null_var_sym(name, sym) ||
 716             parent_is_free_var_sym(name, sym))
 717                 return 1;
 718         return 0;
 719 }
 720
 721 int parent_is_gone(struct expression *expr)
 722 {
 723         struct symbol *sym;
 724         char *var;
 725         int ret = 0;
 726
 727         expr = strip_expr(expr);
 728         var = expr_to_var_sym(expr, &sym);
 729         if (!var || !sym)
 730                 goto free;
 731         ret = parent_is_gone_var_sym(var, sym);
 732 free:
 733         free_string(var);
 734         return ret;
 735 }