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                 sval_t sval;
 292                 int size;
 293                 char tmp[25];
 294
 295                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 296                         size = type_bytes(get_base_type(expr->cast_type));
 297                         snprintf(tmp, 25, "%d", size);
 298                         append(buf, tmp, len);
 299                 } else if (get_value(expr, &sval)) {
 300                         snprintf(tmp, 25, "%s", sval_to_str(sval));
 301                         append(buf, tmp, len);
 302                 }
 303                 return;
 304         }
 305         case EXPR_IDENTIFIER:
 306                 *complicated = 1;
 307                 if (expr->expr_ident)
 308                         append(buf, expr->expr_ident->name, len);
 309                 return;
 310         default:
 311                 *complicated = 1;
 312                 //printf("unknown type = %d\n", expr->type);
 313                 return;
 314         }
 315 }
 316
 317 /*
 318  * This is returns a stylized "c looking" representation of the
 319  * variable name.
 320  *
 321  * It uses the same buffer every time so you have to save the result
 322  * yourself if you want to keep it.
 323  *
 324  */
 325
 326 char *expr_to_str_sym(struct expression *expr, 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         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 338                                  &complicated, 0);
 339         if (complicated < 2)
 340                 return alloc_string(var_name);
 341         else
 342                 return NULL;
 343 }
 344
 345 char *expr_to_str(struct expression *expr)
 346 {
 347         return expr_to_str_sym(expr, NULL);
 348 }
 349
 350 /*
 351  * get_variable_from_expr_simple() only returns simple variables.
 352  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 353  * then it returns NULL.
 354  */
 355 char *expr_to_var_sym(struct expression *expr,
 356                                     struct symbol **sym_ptr)
 357 {
 358         static char var_name[VAR_LEN];
 359         int complicated = 0;
 360
 361         if (sym_ptr)
 362                 *sym_ptr = NULL;
 363         var_name[0] = '\0';
 364
 365         if (!expr)
 366                 return NULL;
 367         expr = strip_expr(expr);
 368         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 369                                  &complicated, 1);
 370
 371         if (complicated) {
 372                 if (sym_ptr)
 373                         *sym_ptr = NULL;
 374                 return NULL;
 375         }
 376         return alloc_string(var_name);
 377 }
 378
 379 char *expr_to_var(struct expression *expr)
 380 {
 381         return expr_to_var_sym(expr, NULL);
 382 }
 383
 384 struct symbol *expr_to_sym(struct expression *expr)
 385 {
 386         struct symbol *sym;
 387         char *name;
 388
 389         name = expr_to_var_sym(expr, &sym);
 390         free_string(name);
 391         return sym;
 392 }
 393
 394 int get_complication_score(struct expression *expr)
 395 {
 396         int score = 0;
 397
 398         expr = strip_expr(expr);
 399
 400         /*
 401          * Don't forget to keep get_complication_score() and store_all_links()
 402          * in sync.
 403          *
 404          */
 405
 406         if (!expr)
 407                 return 999;
 408
 409         switch (expr->type) {
 410         case EXPR_CALL:
 411                 return 999;
 412         case EXPR_COMPARE:
 413         case EXPR_BINOP:
 414                 score += get_complication_score(expr->left);
 415                 score += get_complication_score(expr->right);
 416                 return score;
 417         case EXPR_SYMBOL:
 418                 if (is_local_variable(expr))
 419                         return 1;
 420                 return 999;
 421         case EXPR_PREOP:
 422                 if (expr->op == '*')
 423                         return score + get_complication_score(expr->unop);
 424                 return 999;
 425         case EXPR_DEREF:
 426                 return score + get_complication_score(expr->deref);
 427         case EXPR_VALUE:
 428                 return 0;
 429         default:
 430                 return 999;
 431         }
 432 }
 433
 434 struct expression *reorder_expr_alphabetically(struct expression *expr)
 435 {
 436         struct expression *ret;
 437         char *left, *right;
 438
 439         if (expr->type != EXPR_BINOP)
 440                 return expr;
 441         if (expr->op != '+' && expr->op != '*')
 442                 return expr;
 443
 444         left = expr_to_var(expr->left);
 445         right = expr_to_var(expr->right);
 446         ret = expr;
 447         if (!left || !right)
 448                 goto free;
 449         if (strcmp(left, right) <= 0)
 450                 goto free;
 451
 452         ret = binop_expression(expr->right, expr->op, expr->left);
 453 free:
 454         free_string(left);
 455         free_string(right);
 456
 457         return ret;
 458 }
 459
 460 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 461 {
 462         char *name;
 463         struct symbol *tmp;
 464         int score;
 465
 466         if (vsl)
 467                 *vsl = NULL;
 468         if (sym)
 469                 *sym = NULL;
 470
 471         expr = strip_parens(expr);
 472         if (!expr)
 473                 return NULL;
 474
 475         name = expr_to_var_sym(expr, &tmp);
 476         if (name && tmp) {
 477                 if (sym)
 478                         *sym = tmp;
 479                 if (vsl)
 480                         *vsl = expr_to_vsl(expr);
 481                 return name;
 482         }
 483         free_string(name);
 484
 485         score = get_complication_score(expr);
 486         if (score <= 0 || score > 2)
 487                 return NULL;
 488
 489         if (vsl) {
 490                 *vsl = expr_to_vsl(expr);
 491                 if (!*vsl)
 492                         return NULL;
 493         }
 494
 495         expr = reorder_expr_alphabetically(expr);
 496
 497         return expr_to_str(expr);
 498 }
 499
 500 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 501 {
 502         return expr_to_chunk_helper(expr, sym, NULL);
 503 }
 504
 505 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 506 {
 507         return expr_to_chunk_helper(expr, sym, vsl);
 508 }
 509
 510 int sym_name_is(const char *name, struct expression *expr)
 511 {
 512         if (!expr)
 513                 return 0;
 514         if (expr->type != EXPR_SYMBOL)
 515                 return 0;
 516         if (!strcmp(expr->symbol_name->name, name))
 517                 return 1;
 518         return 0;
 519 }
 520
 521 int is_zero(struct expression *expr)
 522 {
 523         sval_t sval;
 524
 525         if (get_value(expr, &sval) && sval.value == 0)
 526                 return 1;
 527         return 0;
 528 }
 529
 530 int is_array(struct expression *expr)
 531 {
 532         struct symbol *type;
 533
 534         expr = strip_expr(expr);
 535         if (!expr)
 536                 return 0;
 537
 538         if (expr->type == EXPR_PREOP && expr->op == '*') {
 539                 expr = strip_expr(expr->unop);
 540                 if (!expr)
 541                         return 0;
 542                 if (expr->type == EXPR_BINOP && expr->op == '+')
 543                         return 1;
 544         }
 545
 546         if (expr->type != EXPR_BINOP || expr->op != '+')
 547                 return 0;
 548
 549         type = get_type(expr->left);
 550         if (!type || type->type != SYM_ARRAY)
 551                 return 0;
 552
 553         return 1;
 554 }
 555
 556 struct expression *get_array_base(struct expression *expr)
 557 {
 558         if (!is_array(expr))
 559                 return NULL;
 560         expr = strip_expr(expr);
 561         if (expr->type == EXPR_PREOP && expr->op == '*')
 562                 expr = strip_expr(expr->unop);
 563         if (expr->type != EXPR_BINOP || expr->op != '+')
 564                 return NULL;
 565         return strip_parens(expr->left);
 566 }
 567
 568 struct expression *get_array_offset(struct expression *expr)
 569 {
 570         if (!is_array(expr))
 571                 return NULL;
 572         expr = strip_expr(expr);
 573         if (expr->type == EXPR_PREOP && expr->op == '*')
 574                 expr = strip_expr(expr->unop);
 575         if (expr->type != EXPR_BINOP || expr->op != '+')
 576                 return NULL;
 577         return strip_parens(expr->right);
 578 }
 579
 580 const char *show_state(struct smatch_state *state)
 581 {
 582         if (!state)
 583                 return NULL;
 584         return state->name;
 585 }
 586
 587 struct statement *get_expression_statement(struct expression *expr)
 588 {
 589         /* What are those things called? if (({....; ret;})) { ...*/
 590
 591         if (expr->type != EXPR_PREOP)
 592                 return NULL;
 593         if (expr->op != '(')
 594                 return NULL;
 595         if (expr->unop->type != EXPR_STATEMENT)
 596                 return NULL;
 597         if (expr->unop->statement->type != STMT_COMPOUND)
 598                 return NULL;
 599         return expr->unop->statement;
 600 }
 601
 602 struct expression *strip_parens(struct expression *expr)
 603 {
 604         if (!expr)
 605                 return NULL;
 606
 607         if (expr->type == EXPR_PREOP) {
 608                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 609                         expr->unop->statement->type == STMT_COMPOUND)
 610                         return expr;
 611                 if (expr->op == '(')
 612                         return strip_parens(expr->unop);
 613         }
 614         return expr;
 615 }
 616
 617 struct expression *strip_expr(struct expression *expr)
 618 {
 619         if (!expr)
 620                 return NULL;
 621
 622         switch (expr->type) {
 623         case EXPR_FORCE_CAST:
 624         case EXPR_CAST:
 625                 return strip_expr(expr->cast_expression);
 626         case EXPR_PREOP: {
 627                 struct expression *unop;
 628
 629                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 630                         expr->unop->statement->type == STMT_COMPOUND)
 631                         return expr;
 632
 633                 unop = strip_expr(expr->unop);
 634
 635                 if (expr->op == '*' && unop &&
 636                     unop->type == EXPR_PREOP && unop->op == '&') {
 637                         struct symbol *type = get_type(unop->unop);
 638
 639                         if (type && type->type == SYM_ARRAY)
 640                                 return expr;
 641                         return strip_expr(unop->unop);
 642                 }
 643
 644                 if (expr->op == '(')
 645                         return unop;
 646
 647                 return expr;
 648         }
 649         case EXPR_CONDITIONAL:
 650                 if (known_condition_true(expr->conditional)) {
 651                         if (expr->cond_true)
 652                                 return strip_expr(expr->cond_true);
 653                         return strip_expr(expr->conditional);
 654                 }
 655                 if (known_condition_false(expr->conditional))
 656                         return strip_expr(expr->cond_false);
 657                 return expr;
 658         case EXPR_CALL:
 659                 if (sym_name_is("__builtin_expect", expr->fn)) {
 660                         expr = get_argument_from_call_expr(expr->args, 0);
 661                         return strip_expr(expr);
 662                 }
 663                 return expr;
 664         }
 665         return expr;
 666 }
 667
 668 static void delete_state_tracker(struct tracker *t)
 669 {
 670         delete_state(t->owner, t->name, t->sym);
 671         __free_tracker(t);
 672 }
 673
 674 void scoped_state(int my_id, const char *name, struct symbol *sym)
 675 {
 676         struct tracker *t;
 677
 678         t = alloc_tracker(my_id, name, sym);
 679         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 680 }
 681
 682 int is_error_return(struct expression *expr)
 683 {
 684         struct symbol *cur_func = cur_func_sym;
 685         sval_t sval;
 686
 687         if (!expr)
 688                 return 0;
 689         if (cur_func->type != SYM_NODE)
 690                 return 0;
 691         cur_func = get_base_type(cur_func);
 692         if (cur_func->type != SYM_FN)
 693                 return 0;
 694         cur_func = get_base_type(cur_func);
 695         if (cur_func == &void_ctype)
 696                 return 0;
 697         if (!get_implied_value(expr, &sval))
 698                 return 0;
 699         if (sval.value < 0)
 700                 return 1;
 701         if (cur_func->type == SYM_PTR && sval.value == 0)
 702                 return 1;
 703         return 0;
 704 }
 705
 706 int getting_address(void)
 707 {
 708         struct expression *tmp;
 709         int i = 0;
 710         int dot_ops = 0;
 711
 712         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 713                 if (!i++)
 714                         continue;
 715                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 716                         continue;
 717                 if (tmp->op == '.' && !dot_ops++)
 718                         continue;
 719                 if (tmp->op == '&')
 720                         return 1;
 721                 return 0;
 722         } END_FOR_EACH_PTR_REVERSE(tmp);
 723         return 0;
 724 }
 725
 726 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 727 {
 728         struct symbol *sym;
 729
 730         expr = strip_expr(expr);
 731         if (expr->type != EXPR_DEREF)
 732                 return 0;
 733         if (!expr->member)
 734                 return 0;
 735
 736         sym = get_type(expr->deref);
 737         if (!sym)
 738                 return 0;
 739         if (sym->type == SYM_UNION)
 740                 return 0;
 741         if (!sym->ident)
 742                 return 0;
 743
 744         *type = sym->ident->name;
 745         *member = expr->member->name;
 746         return 1;
 747 }
 748
 749 char *get_member_name(struct expression *expr)
 750 {
 751         char buf[256];
 752         struct symbol *sym;
 753
 754         expr = strip_expr(expr);
 755         if (expr->type != EXPR_DEREF)
 756                 return NULL;
 757         if (!expr->member)
 758                 return NULL;
 759
 760         sym = get_type(expr->deref);
 761         if (!sym)
 762                 return NULL;
 763         if (sym->type == SYM_UNION) {
 764                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 765                          sym->ident ? sym->ident->name : "anonymous",
 766                          expr->member->name);
 767                 return alloc_string(buf);
 768         }
 769         if (!sym->ident)
 770                 return NULL;
 771         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 772         return alloc_string(buf);
 773 }
 774
 775 int cmp_pos(struct position pos1, struct position pos2)
 776 {
 777         /* the stream position is ... */
 778         if (pos1.stream > pos2.stream)
 779                 return -1;
 780         if (pos1.stream < pos2.stream)
 781                 return 1;
 782
 783         if (pos1.line < pos2.line)
 784                 return -1;
 785         if (pos1.line > pos2.line)
 786                 return 1;
 787
 788         if (pos1.pos < pos2.pos)
 789                 return -1;
 790         if (pos1.pos > pos2.pos)
 791                 return 1;
 792
 793         return 0;
 794 }
 795
 796 int positions_eq(struct position pos1, struct position pos2)
 797 {
 798         if (pos1.line != pos2.line)
 799                 return 0;
 800         if (pos1.pos != pos2.pos)
 801                 return 0;
 802         if (pos1.stream != pos2.stream)
 803                 return 0;
 804         return 1;
 805 }
 806
 807 struct statement *get_current_statement(void)
 808 {
 809         struct statement *prev, *tmp;
 810
 811         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 812
 813         if (!prev || !get_macro_name(prev->pos))
 814                 return prev;
 815
 816         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 817                 if (positions_eq(tmp->pos, prev->pos))
 818                         continue;
 819                 if (prev->pos.line > tmp->pos.line)
 820                         return prev;
 821                 return tmp;
 822         } END_FOR_EACH_PTR_REVERSE(tmp);
 823         return prev;
 824 }
 825
 826 struct statement *get_prev_statement(void)
 827 {
 828         struct statement *tmp;
 829         int i;
 830
 831         i = 0;
 832         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 833                 if (i++ == 1)
 834                         return tmp;
 835         } END_FOR_EACH_PTR_REVERSE(tmp);
 836         return NULL;
 837 }
 838
 839 int get_param_num_from_sym(struct symbol *sym)
 840 {
 841         struct symbol *tmp;
 842         int i;
 843
 844         if (!cur_func_sym)
 845                 return -1;
 846
 847         i = 0;
 848         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 849                 if (tmp == sym)
 850                         return i;
 851                 i++;
 852         } END_FOR_EACH_PTR(tmp);
 853         return -1;
 854 }
 855
 856 int get_param_num(struct expression *expr)
 857 {
 858         struct symbol *sym;
 859         char *name;
 860
 861         if (!cur_func_sym)
 862                 return -1;
 863         name = expr_to_var_sym(expr, &sym);
 864         free_string(name);
 865         if (!sym)
 866                 return -1;
 867         return get_param_num_from_sym(sym);
 868 }
 869
 870 int ms_since(struct timeval *start)
 871 {
 872         struct timeval end;
 873         double diff;
 874
 875         gettimeofday(&end, NULL);
 876         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 877         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 878         return (int)diff;
 879 }
 880
 881 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 882 {
 883         if (!name || !sym)
 884                 return 0;
 885
 886         if (parent_is_null_var_sym(name, sym) ||
 887             parent_is_free_var_sym(name, sym))
 888                 return 1;
 889         return 0;
 890 }
 891
 892 int parent_is_gone(struct expression *expr)
 893 {
 894         struct symbol *sym;
 895         char *var;
 896         int ret = 0;
 897
 898         expr = strip_expr(expr);
 899         var = expr_to_var_sym(expr, &sym);
 900         if (!var || !sym)
 901                 goto free;
 902         ret = parent_is_gone_var_sym(var, sym);
 903 free:
 904         free_string(var);
 905         return ret;
 906 }
 907
 908 int invert_op(int op)
 909 {
 910         switch (op) {
 911         case '*':
 912                 return '/';
 913         case '/':
 914                 return '*';
 915         case '+':
 916                 return '-';
 917         case '-':
 918                 return '+';
 919         case SPECIAL_LEFTSHIFT:
 920                 return SPECIAL_RIGHTSHIFT;
 921         case SPECIAL_RIGHTSHIFT:
 922                 return SPECIAL_LEFTSHIFT;
 923         }
 924         return 0;
 925 }
 926
 927 int expr_equiv(struct expression *one, struct expression *two)
 928 {
 929         struct symbol *one_sym = NULL;
 930         struct symbol *two_sym = NULL;
 931         char *one_name = NULL;
 932         char *two_name = NULL;
 933         int ret = 0;
 934
 935         if (!one || !two)
 936                 return 0;
 937         if (one->type != two->type)
 938                 return 0;
 939
 940         one_name = expr_to_str_sym(one, &one_sym);
 941         if (!one_name)
 942                 goto free;
 943         two_name = expr_to_str_sym(two, &two_sym);
 944         if (!two_name)
 945                 goto free;
 946         if (one_sym != two_sym)
 947                 goto free;
 948         /*
 949          * This is a terrible hack because expr_to_str() sometimes gives up in
 950          * the middle and just returns what it has.  If you see a () you know
 951          * the string is bogus.
 952          */
 953         if (strstr(one_name, "()"))
 954                 goto free;
 955         if (strcmp(one_name, two_name) == 0)
 956                 ret = 1;
 957 free:
 958         free_string(one_name);
 959         free_string(two_name);
 960         return ret;
 961 }
 962
 963 void push_int(struct int_stack **stack, int num)
 964 {
 965         int *munged;
 966
 967         /*
 968          * Just put the int on directly instead of a pointer to the int.
 969          * Shift it to the left because Sparse uses the last two bits.
 970          * This is sort of a dirty hack, yes.
 971          */
 972
 973         munged = INT_PTR(num << 2);
 974
 975         add_ptr_list(stack, munged);
 976 }
 977
 978 int pop_int(struct int_stack **stack)
 979 {
 980         int *num;
 981
 982         num = last_ptr_list((struct ptr_list *)*stack);
 983         delete_ptr_list_last((struct ptr_list **)stack);
 984
 985         return PTR_INT(num) >> 2;
 986 }