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