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