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 #include "smatch_slist.h"
  28
  29 #define VAR_LEN 512
  30
  31 char *alloc_string(const char *str)
  32 {
  33         char *tmp;
  34
  35         if (!str)
  36                 return NULL;
  37         tmp = malloc(strlen(str) + 1);
  38         strcpy(tmp, str);
  39         return tmp;
  40 }
  41
  42 void free_string(char *str)
  43 {
  44         free(str);
  45 }
  46
  47 void remove_parens(char *str)
  48 {
  49         char *src, *dst;
  50
  51         dst = src = str;
  52         while (*src != '\0') {
  53                 if (*src == '(' || *src == ')') {
  54                         src++;
  55                         continue;
  56                 }
  57                 *dst++ = *src++;
  58         }
  59         *dst = *src;
  60 }
  61
  62 struct smatch_state *alloc_state_num(int num)
  63 {
  64         struct smatch_state *state;
  65         static char buff[256];
  66
  67         state = __alloc_smatch_state(0);
  68         snprintf(buff, 255, "%d", num);
  69         buff[255] = '\0';
  70         state->name = alloc_string(buff);
  71         state->data = INT_PTR(num);
  72         return state;
  73 }
  74
  75 struct smatch_state *alloc_state_str(const char *name)
  76 {
  77         struct smatch_state *state;
  78
  79         state = __alloc_smatch_state(0);
  80         state->name = alloc_string(name);
  81         return state;
  82 }
  83
  84 struct smatch_state *alloc_state_expr(struct expression *expr)
  85 {
  86         struct smatch_state *state;
  87         char *name;
  88
  89         state = __alloc_smatch_state(0);
  90         expr = strip_expr(expr);
  91         name = expr_to_str(expr);
  92         state->name = alloc_sname(name);
  93         free_string(name);
  94         state->data = expr;
  95         return state;
  96 }
  97
  98 void append(char *dest, const char *data, int buff_len)
  99 {
 100         strncat(dest, data, buff_len - strlen(dest) - 1);
 101 }
 102
 103 /*
 104  * If you have "foo(a, b, 1);" then use
 105  * get_argument_from_call_expr(expr, 0) to return the expression for
 106  * a.  Yes, it does start counting from 0.
 107  */
 108 struct expression *get_argument_from_call_expr(struct expression_list *args,
 109                                                int num)
 110 {
 111         struct expression *expr;
 112         int i = 0;
 113
 114         if (!args)
 115                 return NULL;
 116
 117         FOR_EACH_PTR(args, expr) {
 118                 if (i == num)
 119                         return expr;
 120                 i++;
 121         } END_FOR_EACH_PTR(expr);
 122         return NULL;
 123 }
 124
 125 static struct expression *get_array_expr(struct expression *expr)
 126 {
 127         struct symbol *type;
 128
 129         if (expr->type != EXPR_BINOP || expr->op != '+')
 130                 return NULL;
 131
 132         type = get_type(expr->left);
 133         if (!type || type->type != SYM_ARRAY)
 134                 return NULL;
 135         return expr->left;
 136 }
 137
 138 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 139                                      struct expression *expr, int len,
 140                                      int *complicated, int no_parens)
 141 {
 142
 143
 144         if (!expr) {
 145                 /* can't happen on valid code */
 146                 *complicated = 1;
 147                 return;
 148         }
 149
 150         switch (expr->type) {
 151         case EXPR_DEREF: {
 152                 struct expression *deref;
 153                 int op;
 154
 155                 deref = expr->deref;
 156                 op = deref->op;
 157                 if (op == '*') {
 158                         struct expression *unop = strip_expr(deref->unop);
 159
 160                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 161                                 deref = unop->unop;
 162                                 op = '.';
 163                         } else {
 164                                 deref = deref->unop;
 165                                 if (!is_pointer(deref))
 166                                         op = '.';
 167                         }
 168                 }
 169
 170                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 171
 172                 if (op == '*')
 173                         append(buf, "->", len);
 174                 else
 175                         append(buf, ".", len);
 176
 177                 if (expr->member)
 178                         append(buf, expr->member->name, len);
 179                 else
 180                         append(buf, "unknown_member", len);
 181
 182                 return;
 183         }
 184         case EXPR_SYMBOL:
 185                 if (expr->symbol_name)
 186                         append(buf, expr->symbol_name->name, len);
 187                 if (sym_ptr) {
 188                         if (*sym_ptr)
 189                                 *complicated = 1;
 190                         *sym_ptr = expr->symbol;
 191                 }
 192                 return;
 193         case EXPR_PREOP: {
 194                 const char *tmp;
 195
 196                 if (get_expression_statement(expr)) {
 197                         *complicated = 2;
 198                         return;
 199                 }
 200
 201                 if (expr->op == '(') {
 202                         if (!no_parens && expr->unop->type != EXPR_SYMBOL)
 203                                 append(buf, "(", len);
 204                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 205                         tmp = show_special(expr->op);
 206                         append(buf, tmp, len);
 207                 }
 208                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 209                                                  len, complicated, no_parens);
 210
 211                 if (expr->op == '(' && !no_parens && expr->unop->type != EXPR_SYMBOL)
 212                         append(buf, ")", len);
 213
 214                 if (expr->op == SPECIAL_DECREMENT ||
 215                                 expr->op == SPECIAL_INCREMENT)
 216                         *complicated = 1;
 217
 218                 return;
 219         }
 220         case EXPR_POSTOP: {
 221                 const char *tmp;
 222
 223                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 224                                                  len, complicated, no_parens);
 225                 tmp = show_special(expr->op);
 226                 append(buf, tmp, len);
 227
 228                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 229                         *complicated = 1;
 230                 return;
 231         }
 232         case EXPR_ASSIGNMENT:
 233         case EXPR_COMPARE:
 234         case EXPR_LOGICAL:
 235         case EXPR_BINOP: {
 236                 char tmp[10];
 237                 struct expression *array_expr;
 238
 239                 *complicated = 1;
 240                 array_expr = get_array_expr(expr);
 241                 if (array_expr) {
 242                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 243                         append(buf, "[", len);
 244                 } else {
 245                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 246                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 247                         append(buf, tmp, len);
 248                 }
 249                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 250                 if (array_expr)
 251                         append(buf, "]", len);
 252                 return;
 253         }
 254         case EXPR_VALUE: {
 255                 char tmp[25];
 256
 257                 *complicated = 1;
 258                 snprintf(tmp, 25, "%lld", expr->value);
 259                 append(buf, tmp, len);
 260                 return;
 261         }
 262         case EXPR_STRING:
 263                 append(buf, "\"", len);
 264                 if (expr->string)
 265                         append(buf, expr->string->data, len);
 266                 append(buf, "\"", len);
 267                 return;
 268         case EXPR_CALL: {
 269                 struct expression *tmp;
 270                 int i;
 271
 272                 *complicated = 1;
 273                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 274                 append(buf, "(", len);
 275                 i = 0;
 276                 FOR_EACH_PTR(expr->args, tmp) {
 277                         if (i++)
 278                                 append(buf, ", ", len);
 279                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 280                 } END_FOR_EACH_PTR(tmp);
 281                 append(buf, ")", len);
 282                 return;
 283         }
 284         case EXPR_CAST:
 285         case EXPR_FORCE_CAST:
 286                 __get_variable_from_expr(sym_ptr, buf,
 287                                          expr->cast_expression, len,
 288                                          complicated, no_parens);
 289                 return;
 290         case EXPR_SIZEOF: {
 291                 int size;
 292                 char tmp[25];
 293
 294                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 295                         size = type_bytes(get_base_type(expr->cast_type));
 296                         snprintf(tmp, 25, "%d", size);
 297                         append(buf, tmp, len);
 298                 }
 299                 return;
 300         }
 301         case EXPR_IDENTIFIER:
 302                 *complicated = 1;
 303                 if (expr->expr_ident)
 304                         append(buf, expr->expr_ident->name, len);
 305                 return;
 306         default:
 307                 *complicated = 1;
 308                 //printf("unknown type = %d\n", expr->type);
 309                 return;
 310         }
 311 }
 312
 313 /*
 314  * This is returns a stylized "c looking" representation of the
 315  * variable name.
 316  *
 317  * It uses the same buffer every time so you have to save the result
 318  * yourself if you want to keep it.
 319  *
 320  */
 321
 322 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 323 {
 324         static char var_name[VAR_LEN];
 325         int complicated = 0;
 326
 327         if (sym_ptr)
 328                 *sym_ptr = NULL;
 329         var_name[0] = '\0';
 330
 331         if (!expr)
 332                 return NULL;
 333         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 334                                  &complicated, 0);
 335         if (complicated < 2)
 336                 return alloc_string(var_name);
 337         else
 338                 return NULL;
 339 }
 340
 341 char *expr_to_str(struct expression *expr)
 342 {
 343         return expr_to_str_sym(expr, NULL);
 344 }
 345
 346 /*
 347  * get_variable_from_expr_simple() only returns simple variables.
 348  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 349  * then it returns NULL.
 350  */
 351 char *expr_to_var_sym(struct expression *expr,
 352                                     struct symbol **sym_ptr)
 353 {
 354         static char var_name[VAR_LEN];
 355         int complicated = 0;
 356
 357         if (sym_ptr)
 358                 *sym_ptr = NULL;
 359         var_name[0] = '\0';
 360
 361         if (!expr)
 362                 return NULL;
 363         expr = strip_expr(expr);
 364         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 365                                  &complicated, 1);
 366
 367         if (complicated) {
 368                 if (sym_ptr)
 369                         *sym_ptr = NULL;
 370                 return NULL;
 371         }
 372         return alloc_string(var_name);
 373 }
 374
 375 char *expr_to_var(struct expression *expr)
 376 {
 377         return expr_to_var_sym(expr, NULL);
 378 }
 379
 380 struct symbol *expr_to_sym(struct expression *expr)
 381 {
 382         struct symbol *sym;
 383         char *name;
 384
 385         name = expr_to_var_sym(expr, &sym);
 386         free_string(name);
 387         return sym;
 388 }
 389
 390 int get_complication_score(struct expression *expr)
 391 {
 392         int score = 0;
 393
 394         expr = strip_expr(expr);
 395
 396         /*
 397          * Don't forget to keep get_complication_score() and store_all_links()
 398          * in sync.
 399          *
 400          */
 401
 402         if (!expr)
 403                 return 999;
 404
 405         switch (expr->type) {
 406         case EXPR_CALL:
 407                 return 999;
 408         case EXPR_COMPARE:
 409         case EXPR_BINOP:
 410                 score += get_complication_score(expr->left);
 411                 score += get_complication_score(expr->right);
 412                 return score;
 413         case EXPR_SYMBOL:
 414                 if (is_local_variable(expr))
 415                         return 1;
 416                 return 999;
 417         case EXPR_PREOP:
 418                 if (expr->op == '*')
 419                         return score + get_complication_score(expr->unop);
 420                 return 999;
 421         case EXPR_DEREF:
 422                 return score + get_complication_score(expr->deref);
 423         case EXPR_VALUE:
 424                 return 0;
 425         default:
 426                 return 999;
 427         }
 428 }
 429
 430 struct expression *reorder_expr_alphabetically(struct expression *expr)
 431 {
 432         struct expression *ret;
 433         char *left, *right;
 434
 435         if (expr->type != EXPR_BINOP)
 436                 return expr;
 437         if (expr->op != '+' && expr->op != '*')
 438                 return expr;
 439
 440         left = expr_to_var(expr->left);
 441         right = expr_to_var(expr->right);
 442         ret = expr;
 443         if (!left || !right)
 444                 goto free;
 445         if (strcmp(left, right) <= 0)
 446                 goto free;
 447
 448         ret = binop_expression(expr->right, expr->op, expr->left);
 449 free:
 450         free_string(left);
 451         free_string(right);
 452
 453         return ret;
 454 }
 455
 456 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 457 {
 458         char *name;
 459         struct symbol *tmp;
 460         int score;
 461
 462         if (vsl)
 463                 *vsl = NULL;
 464         if (sym)
 465                 *sym = NULL;
 466
 467         expr = strip_parens(expr);
 468         if (!expr)
 469                 return NULL;
 470
 471         name = expr_to_var_sym(expr, &tmp);
 472         if (name && tmp) {
 473                 if (sym)
 474                         *sym = tmp;
 475                 if (vsl)
 476                         *vsl = expr_to_vsl(expr);
 477                 return name;
 478         }
 479         free_string(name);
 480
 481         score = get_complication_score(expr);
 482         if (score <= 0 || score > 2)
 483                 return NULL;
 484
 485         if (vsl) {
 486                 *vsl = expr_to_vsl(expr);
 487                 if (!*vsl)
 488                         return NULL;
 489         }
 490
 491         expr = reorder_expr_alphabetically(expr);
 492
 493         return expr_to_str(expr);
 494 }
 495
 496 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 497 {
 498         return expr_to_chunk_helper(expr, sym, NULL);
 499 }
 500
 501 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 502 {
 503         return expr_to_chunk_helper(expr, sym, vsl);
 504 }
 505
 506 int sym_name_is(const char *name, struct expression *expr)
 507 {
 508         if (!expr)
 509                 return 0;
 510         if (expr->type != EXPR_SYMBOL)
 511                 return 0;
 512         if (!strcmp(expr->symbol_name->name, name))
 513                 return 1;
 514         return 0;
 515 }
 516
 517 int is_zero(struct expression *expr)
 518 {
 519         sval_t sval;
 520
 521         if (get_value(expr, &sval) && sval.value == 0)
 522                 return 1;
 523         return 0;
 524 }
 525
 526 int is_array(struct expression *expr)
 527 {
 528         struct symbol *type;
 529
 530         expr = strip_expr(expr);
 531         if (!expr)
 532                 return 0;
 533
 534         if (expr->type == EXPR_PREOP && expr->op == '*') {
 535                 expr = strip_expr(expr->unop);
 536                 if (!expr)
 537                         return 0;
 538                 if (expr->type == EXPR_BINOP && expr->op == '+')
 539                         return 1;
 540         }
 541
 542         if (expr->type != EXPR_BINOP || expr->op != '+')
 543                 return 0;
 544
 545         type = get_type(expr->left);
 546         if (!type || type->type != SYM_ARRAY)
 547                 return 0;
 548
 549         return 1;
 550 }
 551
 552 struct expression *get_array_base(struct expression *expr)
 553 {
 554         if (!is_array(expr))
 555                 return NULL;
 556         expr = strip_expr(expr);
 557         if (expr->type == EXPR_PREOP && expr->op == '*')
 558                 expr = strip_expr(expr->unop);
 559         if (expr->type != EXPR_BINOP || expr->op != '+')
 560                 return NULL;
 561         return strip_parens(expr->left);
 562 }
 563
 564 struct expression *get_array_offset(struct expression *expr)
 565 {
 566         if (!is_array(expr))
 567                 return NULL;
 568         expr = strip_expr(expr);
 569         if (expr->type == EXPR_PREOP && expr->op == '*')
 570                 expr = strip_expr(expr->unop);
 571         if (expr->type != EXPR_BINOP || expr->op != '+')
 572                 return NULL;
 573         return strip_parens(expr->right);
 574 }
 575
 576 const char *show_state(struct smatch_state *state)
 577 {
 578         if (!state)
 579                 return NULL;
 580         return state->name;
 581 }
 582
 583 struct statement *get_expression_statement(struct expression *expr)
 584 {
 585         /* What are those things called? if (({....; ret;})) { ...*/
 586
 587         if (expr->type != EXPR_PREOP)
 588                 return NULL;
 589         if (expr->op != '(')
 590                 return NULL;
 591         if (expr->unop->type != EXPR_STATEMENT)
 592                 return NULL;
 593         if (expr->unop->statement->type != STMT_COMPOUND)
 594                 return NULL;
 595         return expr->unop->statement;
 596 }
 597
 598 struct expression *strip_parens(struct expression *expr)
 599 {
 600         if (!expr)
 601                 return NULL;
 602
 603         if (expr->type == EXPR_PREOP) {
 604                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 605                         expr->unop->statement->type == STMT_COMPOUND)
 606                         return expr;
 607                 if (expr->op == '(')
 608                         return strip_parens(expr->unop);
 609         }
 610         return expr;
 611 }
 612
 613 struct expression *strip_expr(struct expression *expr)
 614 {
 615         if (!expr)
 616                 return NULL;
 617
 618         switch (expr->type) {
 619         case EXPR_FORCE_CAST:
 620         case EXPR_CAST:
 621                 return strip_expr(expr->cast_expression);
 622         case EXPR_PREOP: {
 623                 struct expression *unop;
 624
 625                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 626                         expr->unop->statement->type == STMT_COMPOUND)
 627                         return expr;
 628
 629                 unop = strip_expr(expr->unop);
 630
 631                 if (expr->op == '*' && unop &&
 632                     unop->type == EXPR_PREOP && unop->op == '&') {
 633                         struct symbol *type = get_type(unop->unop);
 634
 635                         if (type && type->type == SYM_ARRAY)
 636                                 return expr;
 637                         return strip_expr(unop->unop);
 638                 }
 639
 640                 if (expr->op == '(')
 641                         return unop;
 642
 643                 return expr;
 644         }
 645         case EXPR_CONDITIONAL:
 646                 if (known_condition_true(expr->conditional)) {
 647                         if (expr->cond_true)
 648                                 return strip_expr(expr->cond_true);
 649                         return strip_expr(expr->conditional);
 650                 }
 651                 if (known_condition_false(expr->conditional))
 652                         return strip_expr(expr->cond_false);
 653                 return expr;
 654         case EXPR_CALL:
 655                 if (sym_name_is("__builtin_expect", expr->fn)) {
 656                         expr = get_argument_from_call_expr(expr->args, 0);
 657                         return strip_expr(expr);
 658                 }
 659                 return expr;
 660         }
 661         return expr;
 662 }
 663
 664 static void delete_state_tracker(struct tracker *t)
 665 {
 666         delete_state(t->owner, t->name, t->sym);
 667         __free_tracker(t);
 668 }
 669
 670 void scoped_state(int my_id, const char *name, struct symbol *sym)
 671 {
 672         struct tracker *t;
 673
 674         t = alloc_tracker(my_id, name, sym);
 675         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 676 }
 677
 678 int is_error_return(struct expression *expr)
 679 {
 680         struct symbol *cur_func = cur_func_sym;
 681         sval_t sval;
 682
 683         if (!expr)
 684                 return 0;
 685         if (cur_func->type != SYM_NODE)
 686                 return 0;
 687         cur_func = get_base_type(cur_func);
 688         if (cur_func->type != SYM_FN)
 689                 return 0;
 690         cur_func = get_base_type(cur_func);
 691         if (cur_func == &void_ctype)
 692                 return 0;
 693         if (!get_implied_value(expr, &sval))
 694                 return 0;
 695         if (sval.value < 0)
 696                 return 1;
 697         if (cur_func->type == SYM_PTR && sval.value == 0)
 698                 return 1;
 699         return 0;
 700 }
 701
 702 int getting_address(void)
 703 {
 704         struct expression *tmp;
 705         int i = 0;
 706         int dot_ops = 0;
 707
 708         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 709                 if (!i++)
 710                         continue;
 711                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 712                         continue;
 713                 if (tmp->op == '.' && !dot_ops++)
 714                         continue;
 715                 if (tmp->op == '&')
 716                         return 1;
 717                 return 0;
 718         } END_FOR_EACH_PTR_REVERSE(tmp);
 719         return 0;
 720 }
 721
 722 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 723 {
 724         struct symbol *sym;
 725
 726         expr = strip_expr(expr);
 727         if (expr->type != EXPR_DEREF)
 728                 return 0;
 729         if (!expr->member)
 730                 return 0;
 731
 732         sym = get_type(expr->deref);
 733         if (!sym)
 734                 return 0;
 735         if (sym->type == SYM_UNION)
 736                 return 0;
 737         if (!sym->ident)
 738                 return 0;
 739
 740         *type = sym->ident->name;
 741         *member = expr->member->name;
 742         return 1;
 743 }
 744
 745 char *get_member_name(struct expression *expr)
 746 {
 747         char buf[256];
 748         struct symbol *sym;
 749
 750         expr = strip_expr(expr);
 751         if (expr->type != EXPR_DEREF)
 752                 return NULL;
 753         if (!expr->member)
 754                 return NULL;
 755
 756         sym = get_type(expr->deref);
 757         if (!sym)
 758                 return NULL;
 759         if (sym->type == SYM_UNION) {
 760                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 761                          sym->ident ? sym->ident->name : "anonymous",
 762                          expr->member->name);
 763                 return alloc_string(buf);
 764         }
 765         if (!sym->ident)
 766                 return NULL;
 767         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 768         return alloc_string(buf);
 769 }
 770
 771 int cmp_pos(struct position pos1, struct position pos2)
 772 {
 773         /* the stream position is ... */
 774         if (pos1.stream > pos2.stream)
 775                 return -1;
 776         if (pos1.stream < pos2.stream)
 777                 return 1;
 778
 779         if (pos1.line < pos2.line)
 780                 return -1;
 781         if (pos1.line > pos2.line)
 782                 return 1;
 783
 784         if (pos1.pos < pos2.pos)
 785                 return -1;
 786         if (pos1.pos > pos2.pos)
 787                 return 1;
 788
 789         return 0;
 790 }
 791
 792 int positions_eq(struct position pos1, struct position pos2)
 793 {
 794         if (pos1.line != pos2.line)
 795                 return 0;
 796         if (pos1.pos != pos2.pos)
 797                 return 0;
 798         if (pos1.stream != pos2.stream)
 799                 return 0;
 800         return 1;
 801 }
 802
 803 struct statement *get_current_statement(void)
 804 {
 805         struct statement *prev, *tmp;
 806
 807         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 808
 809         if (!prev || !get_macro_name(prev->pos))
 810                 return prev;
 811
 812         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 813                 if (positions_eq(tmp->pos, prev->pos))
 814                         continue;
 815                 if (prev->pos.line > tmp->pos.line)
 816                         return prev;
 817                 return tmp;
 818         } END_FOR_EACH_PTR_REVERSE(tmp);
 819         return prev;
 820 }
 821
 822 struct statement *get_prev_statement(void)
 823 {
 824         struct statement *tmp;
 825         int i;
 826
 827         i = 0;
 828         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 829                 if (i++ == 1)
 830                         return tmp;
 831         } END_FOR_EACH_PTR_REVERSE(tmp);
 832         return NULL;
 833 }
 834
 835 int get_param_num_from_sym(struct symbol *sym)
 836 {
 837         struct symbol *tmp;
 838         int i;
 839
 840         if (!cur_func_sym)
 841                 return -1;
 842
 843         i = 0;
 844         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 845                 if (tmp == sym)
 846                         return i;
 847                 i++;
 848         } END_FOR_EACH_PTR(tmp);
 849         return -1;
 850 }
 851
 852 int get_param_num(struct expression *expr)
 853 {
 854         struct symbol *sym;
 855         char *name;
 856
 857         if (!cur_func_sym)
 858                 return -1;
 859         name = expr_to_var_sym(expr, &sym);
 860         free_string(name);
 861         if (!sym)
 862                 return -1;
 863         return get_param_num_from_sym(sym);
 864 }
 865
 866 int ms_since(struct timeval *start)
 867 {
 868         struct timeval end;
 869         double diff;
 870
 871         gettimeofday(&end, NULL);
 872         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 873         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 874         return (int)diff;
 875 }
 876
 877 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 878 {
 879         if (!name || !sym)
 880                 return 0;
 881
 882         if (parent_is_null_var_sym(name, sym) ||
 883             parent_is_free_var_sym(name, sym))
 884                 return 1;
 885         return 0;
 886 }
 887
 888 int parent_is_gone(struct expression *expr)
 889 {
 890         struct symbol *sym;
 891         char *var;
 892         int ret = 0;
 893
 894         expr = strip_expr(expr);
 895         var = expr_to_var_sym(expr, &sym);
 896         if (!var || !sym)
 897                 goto free;
 898         ret = parent_is_gone_var_sym(var, sym);
 899 free:
 900         free_string(var);
 901         return ret;
 902 }
 903
 904 int invert_op(int op)
 905 {
 906         switch (op) {
 907         case '*':
 908                 return '/';
 909         case '/':
 910                 return '*';
 911         case '+':
 912                 return '-';
 913         case '-':
 914                 return '+';
 915         case SPECIAL_LEFTSHIFT:
 916                 return SPECIAL_RIGHTSHIFT;
 917         case SPECIAL_RIGHTSHIFT:
 918                 return SPECIAL_LEFTSHIFT;
 919         }
 920         return 0;
 921 }
 922
 923 int expr_equiv(struct expression *one, struct expression *two)
 924 {
 925         struct symbol *one_sym, *two_sym;
 926         char *one_name = NULL;
 927         char *two_name = NULL;
 928         int ret = 0;
 929
 930         if (!one || !two)
 931                 return 0;
 932         if (one->type != two->type)
 933                 return 0;
 934
 935         one_name = expr_to_str_sym(one, &one_sym);
 936         if (!one_name || !one_sym)
 937                 goto free;
 938         two_name = expr_to_str_sym(two, &two_sym);
 939         if (!two_name || !two_sym)
 940                 goto free;
 941         if (one_sym != two_sym)
 942                 goto free;
 943         if (strcmp(one_name, two_name) == 0)
 944                 ret = 1;
 945 free:
 946         free_string(one_name);
 947         free_string(two_name);
 948         return ret;
 949 }
 950
 951 void push_int(struct int_stack **stack, int num)
 952 {
 953         int *munged;
 954
 955         /*
 956          * Just put the int on directly instead of a pointer to the int.
 957          * Shift it to the left because Sparse uses the last two bits.
 958          * This is sort of a dirty hack, yes.
 959          */
 960
 961         munged = INT_PTR(num << 2);
 962
 963         add_ptr_list(stack, munged);
 964 }
 965
 966 int pop_int(struct int_stack **stack)
 967 {
 968         int *num;
 969
 970         num = last_ptr_list((struct ptr_list *)*stack);
 971         delete_ptr_list_last((struct ptr_list **)stack);
 972
 973         return PTR_INT(num) >> 2;
 974 }