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 struct smatch_state *alloc_state_str(const char *name)
  75 {
  76         struct smatch_state *state;
  77
  78         state = __alloc_smatch_state(0);
  79         state->name = alloc_string(name);
  80         return state;
  81 }
  82
  83 void append(char *dest, const char *data, int buff_len)
  84 {
  85         strncat(dest, data, buff_len - strlen(dest) - 1);
  86 }
  87
  88 /*
  89  * If you have "foo(a, b, 1);" then use
  90  * get_argument_from_call_expr(expr, 0) to return the expression for
  91  * a.  Yes, it does start counting from 0.
  92  */
  93 struct expression *get_argument_from_call_expr(struct expression_list *args,
  94                                                int num)
  95 {
  96         struct expression *expr;
  97         int i = 0;
  98
  99         if (!args)
 100                 return NULL;
 101
 102         FOR_EACH_PTR(args, expr) {
 103                 if (i == num)
 104                         return expr;
 105                 i++;
 106         } END_FOR_EACH_PTR(expr);
 107         return NULL;
 108 }
 109
 110 static struct expression *get_array_expr(struct expression *expr)
 111 {
 112         struct symbol *type;
 113
 114         if (expr->type != EXPR_BINOP || expr->op != '+')
 115                 return NULL;
 116
 117         type = get_type(expr->left);
 118         if (!type || type->type != SYM_ARRAY)
 119                 return NULL;
 120         return expr->left;
 121 }
 122
 123 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 124                                      struct expression *expr, int len,
 125                                      int *complicated, int no_parens)
 126 {
 127         switch (expr->type) {
 128         case EXPR_DEREF: {
 129                 struct expression *deref;
 130                 int op;
 131
 132                 deref = expr->deref;
 133                 op = deref->op;
 134                 if (op == '*') {
 135                         struct expression *unop = strip_expr(deref->unop);
 136
 137                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 138                                 deref = unop->unop;
 139                                 op = '.';
 140                         } else {
 141                                 deref = deref->unop;
 142                         }
 143                 }
 144
 145                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 146
 147                 if (op == '*')
 148                         append(buf, "->", len);
 149                 else
 150                         append(buf, ".", len);
 151
 152                 if (expr->member)
 153                         append(buf, expr->member->name, len);
 154                 else
 155                         append(buf, "unknown_member", len);
 156
 157                 return;
 158         }
 159         case EXPR_SYMBOL:
 160                 if (expr->symbol_name)
 161                         append(buf, expr->symbol_name->name, len);
 162                 if (sym_ptr) {
 163                         if (*sym_ptr)
 164                                 *complicated = 1;
 165                         *sym_ptr = expr->symbol;
 166                 }
 167                 return;
 168         case EXPR_PREOP: {
 169                 const char *tmp;
 170
 171                 if (get_expression_statement(expr)) {
 172                         *complicated = 2;
 173                         return;
 174                 }
 175
 176                 if (expr->op == '(') {
 177                         if (!no_parens)
 178                                 append(buf, "(", len);
 179                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 180                         tmp = show_special(expr->op);
 181                         append(buf, tmp, len);
 182                 }
 183                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 184                                                  len, complicated, no_parens);
 185
 186                 if (expr->op == '(' && !no_parens)
 187                         append(buf, ")", len);
 188
 189                 if (expr->op == SPECIAL_DECREMENT ||
 190                                 expr->op == SPECIAL_INCREMENT)
 191                         *complicated = 1;
 192
 193                 return;
 194         }
 195         case EXPR_POSTOP: {
 196                 const char *tmp;
 197
 198                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 199                                                  len, complicated, no_parens);
 200                 tmp = show_special(expr->op);
 201                 append(buf, tmp, len);
 202
 203                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 204                         *complicated = 1;
 205                 return;
 206         }
 207         case EXPR_ASSIGNMENT:
 208         case EXPR_COMPARE:
 209         case EXPR_LOGICAL:
 210         case EXPR_BINOP: {
 211                 char tmp[10];
 212                 struct expression *array_expr;
 213
 214                 *complicated = 1;
 215                 array_expr = get_array_expr(expr);
 216                 if (array_expr) {
 217                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 218                         append(buf, "[", len);
 219                 } else {
 220                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 221                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 222                         append(buf, tmp, len);
 223                 }
 224                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 225                 if (array_expr)
 226                         append(buf, "]", len);
 227                 return;
 228         }
 229         case EXPR_VALUE: {
 230                 char tmp[25];
 231
 232                 *complicated = 1;
 233                 snprintf(tmp, 25, "%lld", expr->value);
 234                 append(buf, tmp, len);
 235                 return;
 236         }
 237         case EXPR_STRING:
 238                 append(buf, "\"", len);
 239                 if (expr->string)
 240                         append(buf, expr->string->data, len);
 241                 append(buf, "\"", len);
 242                 return;
 243         case EXPR_CALL: {
 244                 struct expression *tmp;
 245                 int i;
 246
 247                 *complicated = 1;
 248                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 249                 append(buf, "(", len);
 250                 i = 0;
 251                 FOR_EACH_PTR(expr->args, tmp) {
 252                         if (i++)
 253                                 append(buf, ", ", len);
 254                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 255                 } END_FOR_EACH_PTR(tmp);
 256                 append(buf, ")", len);
 257                 return;
 258         }
 259         case EXPR_CAST:
 260                 __get_variable_from_expr(sym_ptr, buf,
 261                                          expr->cast_expression, len,
 262                                          complicated, no_parens);
 263                 return;
 264         case EXPR_SIZEOF: {
 265                 int size;
 266                 char tmp[25];
 267
 268                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 269                         size = type_bytes(get_base_type(expr->cast_type));
 270                         snprintf(tmp, 25, "%d", size);
 271                         append(buf, tmp, len);
 272                 }
 273                 return;
 274         }
 275         case EXPR_IDENTIFIER:
 276                 *complicated = 1;
 277                 if (expr->expr_ident)
 278                         append(buf, expr->expr_ident->name, len);
 279                 return;
 280         default:
 281                 *complicated = 1;
 282                 //printf("unknown type = %d\n", expr->type);
 283                 return;
 284         }
 285 }
 286
 287 /*
 288  * This is returns a stylized "c looking" representation of the
 289  * variable name.
 290  *
 291  * It uses the same buffer every time so you have to save the result
 292  * yourself if you want to keep it.
 293  *
 294  */
 295
 296 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 297 {
 298         static char var_name[VAR_LEN];
 299         int complicated = 0;
 300
 301         if (sym_ptr)
 302                 *sym_ptr = NULL;
 303         var_name[0] = '\0';
 304
 305         if (!expr)
 306                 return NULL;
 307         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 308                                  &complicated, 0);
 309         if (complicated < 2)
 310                 return alloc_string(var_name);
 311         else
 312                 return NULL;
 313 }
 314
 315 char *expr_to_str(struct expression *expr)
 316 {
 317         return expr_to_str_sym(expr, NULL);
 318 }
 319
 320 /*
 321  * get_variable_from_expr_simple() only returns simple variables.
 322  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 323  * then it returns NULL.
 324  */
 325 char *expr_to_var_sym(struct expression *expr,
 326                                     struct symbol **sym_ptr)
 327 {
 328         static char var_name[VAR_LEN];
 329         int complicated = 0;
 330
 331         if (sym_ptr)
 332                 *sym_ptr = NULL;
 333         var_name[0] = '\0';
 334
 335         if (!expr)
 336                 return NULL;
 337         expr = strip_expr(expr);
 338         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 339                                  &complicated, 1);
 340
 341         if (complicated) {
 342                 if (sym_ptr)
 343                         *sym_ptr = NULL;
 344                 return NULL;
 345         }
 346         return alloc_string(var_name);
 347 }
 348
 349 char *expr_to_var(struct expression *expr)
 350 {
 351         return expr_to_var_sym(expr, NULL);
 352 }
 353
 354 struct symbol *expr_to_sym(struct expression *expr)
 355 {
 356         struct symbol *sym;
 357         char *name;
 358
 359         name = expr_to_var_sym(expr, &sym);
 360         free_string(name);
 361         return sym;
 362 }
 363
 364 int sym_name_is(const char *name, struct expression *expr)
 365 {
 366         if (!expr)
 367                 return 0;
 368         if (expr->type != EXPR_SYMBOL)
 369                 return 0;
 370         if (!strcmp(expr->symbol_name->name, name))
 371                 return 1;
 372         return 0;
 373 }
 374
 375 int is_zero(struct expression *expr)
 376 {
 377         sval_t sval;
 378
 379         if (get_value(expr, &sval) && sval.value == 0)
 380                 return 1;
 381         return 0;
 382 }
 383
 384 int is_array(struct expression *expr)
 385 {
 386         struct symbol *type;
 387
 388         expr = strip_expr(expr);
 389         if (!expr)
 390                 return 0;
 391
 392         if (expr->type == EXPR_PREOP && expr->op == '*') {
 393                 expr = strip_expr(expr->unop);
 394                 if (expr->type == EXPR_BINOP && expr->op == '+')
 395                         return 1;
 396         }
 397
 398         if (expr->type != EXPR_BINOP || expr->op != '+')
 399                 return 0;
 400
 401         type = get_type(expr->left);
 402         if (!type || type->type != SYM_ARRAY)
 403                 return 0;
 404
 405         return 1;
 406 }
 407
 408 struct expression *get_array_base(struct expression *expr)
 409 {
 410         if (!is_array(expr))
 411                 return NULL;
 412         expr = strip_expr(expr);
 413         if (expr->type == EXPR_PREOP && expr->op == '*')
 414                 expr = strip_expr(expr->unop);
 415         if (expr->type != EXPR_BINOP || expr->op != '+')
 416                 return NULL;
 417         return strip_parens(expr->left);
 418 }
 419
 420 struct expression *get_array_offset(struct expression *expr)
 421 {
 422         if (!is_array(expr))
 423                 return NULL;
 424         expr = strip_expr(expr);
 425         if (expr->type == EXPR_PREOP && expr->op == '*')
 426                 expr = strip_expr(expr->unop);
 427         if (expr->type != EXPR_BINOP || expr->op != '+')
 428                 return NULL;
 429         return strip_expr(expr->right);
 430 }
 431
 432 const char *show_state(struct smatch_state *state)
 433 {
 434         if (!state)
 435                 return NULL;
 436         return state->name;
 437 }
 438
 439 struct statement *get_expression_statement(struct expression *expr)
 440 {
 441         /* What are those things called? if (({....; ret;})) { ...*/
 442
 443         if (expr->type != EXPR_PREOP)
 444                 return NULL;
 445         if (expr->op != '(')
 446                 return NULL;
 447         if (expr->unop->type != EXPR_STATEMENT)
 448                 return NULL;
 449         if (expr->unop->statement->type != STMT_COMPOUND)
 450                 return NULL;
 451         return expr->unop->statement;
 452 }
 453
 454 struct expression *strip_parens(struct expression *expr)
 455 {
 456         if (!expr)
 457                 return NULL;
 458
 459         if (expr->type == EXPR_PREOP) {
 460                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 461                         expr->unop->statement->type == STMT_COMPOUND)
 462                         return expr;
 463                 if (expr->op == '(')
 464                         return strip_parens(expr->unop);
 465         }
 466         return expr;
 467 }
 468
 469 struct expression *strip_expr(struct expression *expr)
 470 {
 471         if (!expr)
 472                 return NULL;
 473
 474         switch (expr->type) {
 475         case EXPR_FORCE_CAST:
 476         case EXPR_CAST:
 477                 return strip_expr(expr->cast_expression);
 478         case EXPR_PREOP: {
 479                 struct expression *unop;
 480
 481                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 482                         expr->unop->statement->type == STMT_COMPOUND)
 483                         return expr;
 484
 485                 unop = strip_expr(expr->unop);
 486
 487                 if (expr->op == '*' &&
 488                     unop->type == EXPR_PREOP && unop->op == '&') {
 489                         struct symbol *type = get_type(unop->unop);
 490
 491                         if (type && type->type == SYM_ARRAY)
 492                                 return expr;
 493                         return strip_expr(unop->unop);
 494                 }
 495
 496                 if (expr->op == '(')
 497                         return unop;
 498
 499                 return expr;
 500         }
 501         case EXPR_CONDITIONAL:
 502                 if (known_condition_true(expr->conditional)) {
 503                         if (expr->cond_true)
 504                                 return strip_expr(expr->cond_true);
 505                         return strip_expr(expr->conditional);
 506                 }
 507                 if (known_condition_false(expr->conditional))
 508                         return strip_expr(expr->cond_false);
 509                 return expr;
 510         case EXPR_CALL:
 511                 if (sym_name_is("__builtin_expect", expr->fn)) {
 512                         expr = get_argument_from_call_expr(expr->args, 0);
 513                         return strip_expr(expr);
 514                 }
 515                 return expr;
 516         }
 517         return expr;
 518 }
 519
 520 static void delete_state_tracker(struct tracker *t)
 521 {
 522         delete_state(t->owner, t->name, t->sym);
 523         __free_tracker(t);
 524 }
 525
 526 void scoped_state(int my_id, const char *name, struct symbol *sym)
 527 {
 528         struct tracker *t;
 529
 530         t = alloc_tracker(my_id, name, sym);
 531         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 532 }
 533
 534 int is_error_return(struct expression *expr)
 535 {
 536         struct symbol *cur_func = cur_func_sym;
 537         sval_t sval;
 538
 539         if (!expr)
 540                 return 0;
 541         if (cur_func->type != SYM_NODE)
 542                 return 0;
 543         cur_func = get_base_type(cur_func);
 544         if (cur_func->type != SYM_FN)
 545                 return 0;
 546         cur_func = get_base_type(cur_func);
 547         if (cur_func == &void_ctype)
 548                 return 0;
 549         if (!get_implied_value(expr, &sval))
 550                 return 0;
 551         if (sval.value < 0)
 552                 return 1;
 553         if (cur_func->type == SYM_PTR && sval.value == 0)
 554                 return 1;
 555         return 0;
 556 }
 557
 558 int getting_address(void)
 559 {
 560         struct expression *tmp;
 561         int i = 0;
 562         int dot_ops = 0;
 563
 564         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 565                 if (!i++)
 566                         continue;
 567                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 568                         continue;
 569                 if (tmp->op == '.' && !dot_ops++)
 570                         continue;
 571                 if (tmp->op == '&')
 572                         return 1;
 573                 return 0;
 574         } END_FOR_EACH_PTR_REVERSE(tmp);
 575         return 0;
 576 }
 577
 578 char *get_member_name(struct expression *expr)
 579 {
 580         char buf[256];
 581         struct symbol *sym;
 582
 583         expr = strip_expr(expr);
 584         if (expr->type != EXPR_DEREF)
 585                 return NULL;
 586         if (!expr->member)
 587                 return NULL;
 588
 589         sym = get_type(expr->deref);
 590         if (!sym)
 591                 return NULL;
 592         if (sym->type == SYM_UNION) {
 593                 sym = expr_to_sym(expr->deref);
 594                 sym = get_real_base_type(sym);
 595                 if (sym && sym->type == SYM_PTR)
 596                         sym = get_real_base_type(sym);
 597                 if (!sym || !sym->ident) {
 598                         snprintf(buf, sizeof(buf), "(union hack)->%s", expr->member->name);
 599                         return alloc_string(buf);
 600                 }
 601         }
 602         if (!sym->ident)
 603                 return NULL;
 604         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 605         return alloc_string(buf);
 606 }
 607
 608 int cmp_pos(struct position pos1, struct position pos2)
 609 {
 610         /* the stream position is ... */
 611         if (pos1.stream > pos2.stream)
 612                 return -1;
 613         if (pos1.stream < pos2.stream)
 614                 return 1;
 615
 616         if (pos1.line < pos2.line)
 617                 return -1;
 618         if (pos1.line > pos2.line)
 619                 return 1;
 620
 621         if (pos1.pos < pos2.pos)
 622                 return -1;
 623         if (pos1.pos > pos2.pos)
 624                 return 1;
 625
 626         return 0;
 627 }
 628
 629 int positions_eq(struct position pos1, struct position pos2)
 630 {
 631         if (pos1.line != pos2.line)
 632                 return 0;
 633         if (pos1.pos != pos2.pos)
 634                 return 0;
 635         if (pos1.stream != pos2.stream)
 636                 return 0;
 637         return 1;
 638 }
 639
 640 struct statement *get_current_statement(void)
 641 {
 642         struct statement *prev, *tmp;
 643
 644         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 645
 646         if (!prev || !get_macro_name(prev->pos))
 647                 return prev;
 648
 649         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 650                 if (positions_eq(tmp->pos, prev->pos))
 651                         continue;
 652                 if (prev->pos.line > tmp->pos.line)
 653                         return prev;
 654                 return tmp;
 655         } END_FOR_EACH_PTR_REVERSE(tmp);
 656         return prev;
 657 }
 658
 659 struct statement *get_prev_statement(void)
 660 {
 661         struct statement *tmp;
 662         int i;
 663
 664         i = 0;
 665         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 666                 if (i++ == 1)
 667                         return tmp;
 668         } END_FOR_EACH_PTR_REVERSE(tmp);
 669         return NULL;
 670 }
 671
 672 int get_param_num_from_sym(struct symbol *sym)
 673 {
 674         struct symbol *tmp;
 675         int i;
 676
 677         if (!cur_func_sym)
 678                 return -1;
 679
 680         i = 0;
 681         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 682                 if (tmp == sym)
 683                         return i;
 684                 i++;
 685         } END_FOR_EACH_PTR(tmp);
 686         return -1;
 687 }
 688
 689 int get_param_num(struct expression *expr)
 690 {
 691         struct symbol *sym;
 692         char *name;
 693
 694         if (!cur_func_sym)
 695                 return -1;
 696         name = expr_to_var_sym(expr, &sym);
 697         free_string(name);
 698         if (!sym)
 699                 return -1;
 700         return get_param_num_from_sym(sym);
 701 }
 702
 703 int ms_since(struct timeval *start)
 704 {
 705         struct timeval end;
 706         double diff;
 707
 708         gettimeofday(&end, NULL);
 709         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 710         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 711         return (int)diff;
 712 }
 713
 714 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 715 {
 716         if (!name || !sym)
 717                 return 0;
 718
 719         if (parent_is_null_var_sym(name, sym) ||
 720             parent_is_free_var_sym(name, sym))
 721                 return 1;
 722         return 0;
 723 }
 724
 725 int parent_is_gone(struct expression *expr)
 726 {
 727         struct symbol *sym;
 728         char *var;
 729         int ret = 0;
 730
 731         expr = strip_expr(expr);
 732         var = expr_to_var_sym(expr, &sym);
 733         if (!var || !sym)
 734                 goto free;
 735         ret = parent_is_gone_var_sym(var, sym);
 736 free:
 737         free_string(var);
 738         return ret;
 739 }
 740
 741 int invert_op(int op)
 742 {
 743         switch (op) {
 744         case '*':
 745                 return '/';
 746         case '/':
 747                 return '*';
 748         case '+':
 749                 return '-';
 750         case '-':
 751                 return '+';
 752         case SPECIAL_LEFTSHIFT:
 753                 return SPECIAL_RIGHTSHIFT;
 754         case SPECIAL_RIGHTSHIFT:
 755                 return SPECIAL_LEFTSHIFT;
 756         }
 757         return 0;
 758 }