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 expression *parent;
 128         struct symbol *type;
 129
 130         if (expr->type != EXPR_BINOP || expr->op != '+')
 131                 return NULL;
 132
 133         type = get_type(expr->left);
 134         if (!type)
 135                 return NULL;
 136         if (type->type == SYM_ARRAY)
 137                 return expr->left;
 138         if (type->type != SYM_PTR)
 139                 return NULL;
 140
 141         parent = expr_get_parent_expr(expr);
 142         if (!parent)
 143                 return NULL;
 144         if (parent->type == EXPR_PREOP && parent->op == '*')
 145                 return expr->left;
 146
 147         return NULL;
 148 }
 149
 150 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 151                                      struct expression *expr, int len,
 152                                      int *complicated, int no_parens)
 153 {
 154
 155
 156         if (!expr) {
 157                 /* can't happen on valid code */
 158                 *complicated = 1;
 159                 return;
 160         }
 161
 162         switch (expr->type) {
 163         case EXPR_DEREF: {
 164                 struct expression *deref;
 165                 int op;
 166
 167                 deref = expr->deref;
 168                 op = deref->op;
 169                 if (op == '*') {
 170                         struct expression *unop = strip_expr(deref->unop);
 171
 172                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 173                                 deref = unop->unop;
 174                                 op = '.';
 175                         } else {
 176                                 deref = deref->unop;
 177                                 if (!is_pointer(deref))
 178                                         op = '.';
 179                         }
 180                 }
 181
 182                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 183
 184                 if (op == '*')
 185                         append(buf, "->", len);
 186                 else
 187                         append(buf, ".", len);
 188
 189                 if (expr->member)
 190                         append(buf, expr->member->name, len);
 191                 else
 192                         append(buf, "unknown_member", len);
 193
 194                 return;
 195         }
 196         case EXPR_SYMBOL:
 197                 if (expr->symbol_name)
 198                         append(buf, expr->symbol_name->name, len);
 199                 if (sym_ptr) {
 200                         if (*sym_ptr)
 201                                 *complicated = 1;
 202                         *sym_ptr = expr->symbol;
 203                 }
 204                 return;
 205         case EXPR_PREOP: {
 206                 const char *tmp;
 207
 208                 if (get_expression_statement(expr)) {
 209                         *complicated = 2;
 210                         return;
 211                 }
 212
 213                 if (expr->op == '(') {
 214                         if (!no_parens && expr->unop->type != EXPR_SYMBOL)
 215                                 append(buf, "(", len);
 216                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 217                         tmp = show_special(expr->op);
 218                         append(buf, tmp, len);
 219                 }
 220                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 221                                                  len, complicated, no_parens);
 222
 223                 if (expr->op == '(' && !no_parens && expr->unop->type != EXPR_SYMBOL)
 224                         append(buf, ")", len);
 225
 226                 if (expr->op == SPECIAL_DECREMENT ||
 227                                 expr->op == SPECIAL_INCREMENT)
 228                         *complicated = 1;
 229
 230                 return;
 231         }
 232         case EXPR_POSTOP: {
 233                 const char *tmp;
 234
 235                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 236                                                  len, complicated, no_parens);
 237                 tmp = show_special(expr->op);
 238                 append(buf, tmp, len);
 239
 240                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 241                         *complicated = 1;
 242                 return;
 243         }
 244         case EXPR_ASSIGNMENT:
 245         case EXPR_COMPARE:
 246         case EXPR_LOGICAL:
 247         case EXPR_BINOP: {
 248                 char tmp[10];
 249                 struct expression *array_expr;
 250
 251                 *complicated = 1;
 252                 array_expr = get_array_expr(expr);
 253                 if (array_expr) {
 254                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 255                         append(buf, "[", len);
 256                 } else {
 257                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 258                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 259                         append(buf, tmp, len);
 260                 }
 261                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 262                 if (array_expr)
 263                         append(buf, "]", len);
 264                 return;
 265         }
 266         case EXPR_VALUE: {
 267                 char tmp[25];
 268
 269                 *complicated = 1;
 270                 snprintf(tmp, 25, "%lld", expr->value);
 271                 append(buf, tmp, len);
 272                 return;
 273         }
 274         case EXPR_STRING:
 275                 append(buf, "\"", len);
 276                 if (expr->string)
 277                         append(buf, expr->string->data, len);
 278                 append(buf, "\"", len);
 279                 return;
 280         case EXPR_CALL: {
 281                 struct expression *tmp;
 282                 int i;
 283
 284                 *complicated = 1;
 285                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 286                 append(buf, "(", len);
 287                 i = 0;
 288                 FOR_EACH_PTR(expr->args, tmp) {
 289                         if (i++)
 290                                 append(buf, ", ", len);
 291                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 292                 } END_FOR_EACH_PTR(tmp);
 293                 append(buf, ")", len);
 294                 return;
 295         }
 296         case EXPR_CAST:
 297         case EXPR_FORCE_CAST:
 298                 __get_variable_from_expr(sym_ptr, buf,
 299                                          expr->cast_expression, len,
 300                                          complicated, no_parens);
 301                 return;
 302         case EXPR_SIZEOF: {
 303                 sval_t sval;
 304                 int size;
 305                 char tmp[25];
 306
 307                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 308                         size = type_bytes(get_base_type(expr->cast_type));
 309                         snprintf(tmp, 25, "%d", size);
 310                         append(buf, tmp, len);
 311                 } else if (get_value(expr, &sval)) {
 312                         snprintf(tmp, 25, "%s", sval_to_str(sval));
 313                         append(buf, tmp, len);
 314                 }
 315                 return;
 316         }
 317         case EXPR_IDENTIFIER:
 318                 *complicated = 1;
 319                 if (expr->expr_ident)
 320                         append(buf, expr->expr_ident->name, len);
 321                 return;
 322         default:
 323                 *complicated = 1;
 324                 //printf("unknown type = %d\n", expr->type);
 325                 return;
 326         }
 327 }
 328
 329 /*
 330  * This is returns a stylized "c looking" representation of the
 331  * variable name.
 332  *
 333  * It uses the same buffer every time so you have to save the result
 334  * yourself if you want to keep it.
 335  *
 336  */
 337
 338 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 339 {
 340         static char var_name[VAR_LEN];
 341         int complicated = 0;
 342
 343         if (sym_ptr)
 344                 *sym_ptr = NULL;
 345         var_name[0] = '\0';
 346
 347         if (!expr)
 348                 return NULL;
 349         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 350                                  &complicated, 0);
 351         if (complicated < 2)
 352                 return alloc_string(var_name);
 353         else
 354                 return NULL;
 355 }
 356
 357 char *expr_to_str(struct expression *expr)
 358 {
 359         return expr_to_str_sym(expr, NULL);
 360 }
 361
 362 /*
 363  * get_variable_from_expr_simple() only returns simple variables.
 364  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 365  * then it returns NULL.
 366  */
 367 char *expr_to_var_sym(struct expression *expr,
 368                                     struct symbol **sym_ptr)
 369 {
 370         static char var_name[VAR_LEN];
 371         int complicated = 0;
 372
 373         if (sym_ptr)
 374                 *sym_ptr = NULL;
 375         var_name[0] = '\0';
 376
 377         if (!expr)
 378                 return NULL;
 379         expr = strip_expr(expr);
 380         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 381                                  &complicated, 1);
 382
 383         if (complicated) {
 384                 if (sym_ptr)
 385                         *sym_ptr = NULL;
 386                 return NULL;
 387         }
 388         return alloc_string(var_name);
 389 }
 390
 391 char *expr_to_var(struct expression *expr)
 392 {
 393         return expr_to_var_sym(expr, NULL);
 394 }
 395
 396 struct symbol *expr_to_sym(struct expression *expr)
 397 {
 398         struct symbol *sym;
 399         char *name;
 400
 401         name = expr_to_var_sym(expr, &sym);
 402         free_string(name);
 403         return sym;
 404 }
 405
 406 int get_complication_score(struct expression *expr)
 407 {
 408         int score = 0;
 409
 410         expr = strip_expr(expr);
 411
 412         /*
 413          * Don't forget to keep get_complication_score() and store_all_links()
 414          * in sync.
 415          *
 416          */
 417
 418         if (!expr)
 419                 return 999;
 420
 421         switch (expr->type) {
 422         case EXPR_CALL:
 423                 return 999;
 424         case EXPR_COMPARE:
 425         case EXPR_BINOP:
 426                 score += get_complication_score(expr->left);
 427                 score += get_complication_score(expr->right);
 428                 return score;
 429         case EXPR_SYMBOL:
 430                 if (is_local_variable(expr))
 431                         return 1;
 432                 return 999;
 433         case EXPR_PREOP:
 434                 if (expr->op == '*')
 435                         return score + get_complication_score(expr->unop);
 436                 return 999;
 437         case EXPR_DEREF:
 438                 return score + get_complication_score(expr->deref);
 439         case EXPR_VALUE:
 440                 return 0;
 441         default:
 442                 return 999;
 443         }
 444 }
 445
 446 struct expression *reorder_expr_alphabetically(struct expression *expr)
 447 {
 448         struct expression *ret;
 449         char *left, *right;
 450
 451         if (expr->type != EXPR_BINOP)
 452                 return expr;
 453         if (expr->op != '+' && expr->op != '*')
 454                 return expr;
 455
 456         left = expr_to_var(expr->left);
 457         right = expr_to_var(expr->right);
 458         ret = expr;
 459         if (!left || !right)
 460                 goto free;
 461         if (strcmp(left, right) <= 0)
 462                 goto free;
 463
 464         ret = binop_expression(expr->right, expr->op, expr->left);
 465 free:
 466         free_string(left);
 467         free_string(right);
 468
 469         return ret;
 470 }
 471
 472 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 473 {
 474         char *name;
 475         struct symbol *tmp;
 476         int score;
 477
 478         if (vsl)
 479                 *vsl = NULL;
 480         if (sym)
 481                 *sym = NULL;
 482
 483         expr = strip_parens(expr);
 484         if (!expr)
 485                 return NULL;
 486
 487         name = expr_to_var_sym(expr, &tmp);
 488         if (name && tmp) {
 489                 if (sym)
 490                         *sym = tmp;
 491                 if (vsl)
 492                         *vsl = expr_to_vsl(expr);
 493                 return name;
 494         }
 495         free_string(name);
 496
 497         score = get_complication_score(expr);
 498         if (score <= 0 || score > 2)
 499                 return NULL;
 500
 501         if (vsl) {
 502                 *vsl = expr_to_vsl(expr);
 503                 if (!*vsl)
 504                         return NULL;
 505         }
 506
 507         expr = reorder_expr_alphabetically(expr);
 508
 509         return expr_to_str(expr);
 510 }
 511
 512 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 513 {
 514         return expr_to_chunk_helper(expr, sym, NULL);
 515 }
 516
 517 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 518 {
 519         return expr_to_chunk_helper(expr, sym, vsl);
 520 }
 521
 522 int sym_name_is(const char *name, struct expression *expr)
 523 {
 524         if (!expr)
 525                 return 0;
 526         if (expr->type != EXPR_SYMBOL)
 527                 return 0;
 528         if (!strcmp(expr->symbol_name->name, name))
 529                 return 1;
 530         return 0;
 531 }
 532
 533 int is_zero(struct expression *expr)
 534 {
 535         sval_t sval;
 536
 537         if (get_value(expr, &sval) && sval.value == 0)
 538                 return 1;
 539         return 0;
 540 }
 541
 542 int is_array(struct expression *expr)
 543 {
 544         struct symbol *type;
 545
 546         expr = strip_expr(expr);
 547         if (!expr)
 548                 return 0;
 549
 550         if (expr->type == EXPR_PREOP && expr->op == '*') {
 551                 expr = strip_expr(expr->unop);
 552                 if (!expr)
 553                         return 0;
 554                 if (expr->type == EXPR_BINOP && expr->op == '+')
 555                         return 1;
 556         }
 557
 558         if (expr->type != EXPR_BINOP || expr->op != '+')
 559                 return 0;
 560
 561         type = get_type(expr->left);
 562         if (!type || type->type != SYM_ARRAY)
 563                 return 0;
 564
 565         return 1;
 566 }
 567
 568 struct expression *get_array_base(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->left);
 578 }
 579
 580 struct expression *get_array_offset(struct expression *expr)
 581 {
 582         if (!is_array(expr))
 583                 return NULL;
 584         expr = strip_expr(expr);
 585         if (expr->type == EXPR_PREOP && expr->op == '*')
 586                 expr = strip_expr(expr->unop);
 587         if (expr->type != EXPR_BINOP || expr->op != '+')
 588                 return NULL;
 589         return strip_parens(expr->right);
 590 }
 591
 592 const char *show_state(struct smatch_state *state)
 593 {
 594         if (!state)
 595                 return NULL;
 596         return state->name;
 597 }
 598
 599 struct statement *get_expression_statement(struct expression *expr)
 600 {
 601         /* What are those things called? if (({....; ret;})) { ...*/
 602
 603         if (expr->type != EXPR_PREOP)
 604                 return NULL;
 605         if (expr->op != '(')
 606                 return NULL;
 607         if (expr->unop->type != EXPR_STATEMENT)
 608                 return NULL;
 609         if (expr->unop->statement->type != STMT_COMPOUND)
 610                 return NULL;
 611         return expr->unop->statement;
 612 }
 613
 614 struct expression *strip_parens(struct expression *expr)
 615 {
 616         if (!expr)
 617                 return NULL;
 618
 619         if (expr->type == EXPR_PREOP) {
 620                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 621                         expr->unop->statement->type == STMT_COMPOUND)
 622                         return expr;
 623                 if (expr->op == '(')
 624                         return strip_parens(expr->unop);
 625         }
 626         return expr;
 627 }
 628
 629 struct expression *strip_expr(struct expression *expr)
 630 {
 631         if (!expr)
 632                 return NULL;
 633
 634         switch (expr->type) {
 635         case EXPR_FORCE_CAST:
 636         case EXPR_CAST:
 637                 return strip_expr(expr->cast_expression);
 638         case EXPR_PREOP: {
 639                 struct expression *unop;
 640
 641                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 642                         expr->unop->statement->type == STMT_COMPOUND)
 643                         return expr;
 644
 645                 unop = strip_expr(expr->unop);
 646
 647                 if (expr->op == '*' && unop &&
 648                     unop->type == EXPR_PREOP && unop->op == '&') {
 649                         struct symbol *type = get_type(unop->unop);
 650
 651                         if (type && type->type == SYM_ARRAY)
 652                                 return expr;
 653                         return strip_expr(unop->unop);
 654                 }
 655
 656                 if (expr->op == '(')
 657                         return unop;
 658
 659                 return expr;
 660         }
 661         case EXPR_CONDITIONAL:
 662                 if (known_condition_true(expr->conditional)) {
 663                         if (expr->cond_true)
 664                                 return strip_expr(expr->cond_true);
 665                         return strip_expr(expr->conditional);
 666                 }
 667                 if (known_condition_false(expr->conditional))
 668                         return strip_expr(expr->cond_false);
 669                 return expr;
 670         case EXPR_CALL:
 671                 if (sym_name_is("__builtin_expect", expr->fn)) {
 672                         expr = get_argument_from_call_expr(expr->args, 0);
 673                         return strip_expr(expr);
 674                 }
 675                 return expr;
 676         }
 677         return expr;
 678 }
 679
 680 static void delete_state_tracker(struct tracker *t)
 681 {
 682         delete_state(t->owner, t->name, t->sym);
 683         __free_tracker(t);
 684 }
 685
 686 void scoped_state(int my_id, const char *name, struct symbol *sym)
 687 {
 688         struct tracker *t;
 689
 690         t = alloc_tracker(my_id, name, sym);
 691         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 692 }
 693
 694 int is_error_return(struct expression *expr)
 695 {
 696         struct symbol *cur_func = cur_func_sym;
 697         sval_t sval;
 698
 699         if (!expr)
 700                 return 0;
 701         if (cur_func->type != SYM_NODE)
 702                 return 0;
 703         cur_func = get_base_type(cur_func);
 704         if (cur_func->type != SYM_FN)
 705                 return 0;
 706         cur_func = get_base_type(cur_func);
 707         if (cur_func == &void_ctype)
 708                 return 0;
 709         if (!get_implied_value(expr, &sval))
 710                 return 0;
 711         if (sval.value < 0)
 712                 return 1;
 713         if (cur_func->type == SYM_PTR && sval.value == 0)
 714                 return 1;
 715         return 0;
 716 }
 717
 718 int getting_address(void)
 719 {
 720         struct expression *tmp;
 721         int i = 0;
 722         int dot_ops = 0;
 723
 724         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 725                 if (!i++)
 726                         continue;
 727                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 728                         continue;
 729                 if (tmp->op == '.' && !dot_ops++)
 730                         continue;
 731                 if (tmp->op == '&')
 732                         return 1;
 733                 return 0;
 734         } END_FOR_EACH_PTR_REVERSE(tmp);
 735         return 0;
 736 }
 737
 738 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 739 {
 740         struct symbol *sym;
 741
 742         expr = strip_expr(expr);
 743         if (expr->type != EXPR_DEREF)
 744                 return 0;
 745         if (!expr->member)
 746                 return 0;
 747
 748         sym = get_type(expr->deref);
 749         if (!sym)
 750                 return 0;
 751         if (sym->type == SYM_UNION)
 752                 return 0;
 753         if (!sym->ident)
 754                 return 0;
 755
 756         *type = sym->ident->name;
 757         *member = expr->member->name;
 758         return 1;
 759 }
 760
 761 char *get_member_name(struct expression *expr)
 762 {
 763         char buf[256];
 764         struct symbol *sym;
 765
 766         expr = strip_expr(expr);
 767         if (expr->type != EXPR_DEREF)
 768                 return NULL;
 769         if (!expr->member)
 770                 return NULL;
 771
 772         sym = get_type(expr->deref);
 773         if (!sym)
 774                 return NULL;
 775         if (sym->type == SYM_UNION) {
 776                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 777                          sym->ident ? sym->ident->name : "anonymous",
 778                          expr->member->name);
 779                 return alloc_string(buf);
 780         }
 781         if (!sym->ident)
 782                 return NULL;
 783         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 784         return alloc_string(buf);
 785 }
 786
 787 int cmp_pos(struct position pos1, struct position pos2)
 788 {
 789         /* the stream position is ... */
 790         if (pos1.stream > pos2.stream)
 791                 return -1;
 792         if (pos1.stream < pos2.stream)
 793                 return 1;
 794
 795         if (pos1.line < pos2.line)
 796                 return -1;
 797         if (pos1.line > pos2.line)
 798                 return 1;
 799
 800         if (pos1.pos < pos2.pos)
 801                 return -1;
 802         if (pos1.pos > pos2.pos)
 803                 return 1;
 804
 805         return 0;
 806 }
 807
 808 int positions_eq(struct position pos1, struct position pos2)
 809 {
 810         if (pos1.line != pos2.line)
 811                 return 0;
 812         if (pos1.pos != pos2.pos)
 813                 return 0;
 814         if (pos1.stream != pos2.stream)
 815                 return 0;
 816         return 1;
 817 }
 818
 819 struct statement *get_current_statement(void)
 820 {
 821         struct statement *prev, *tmp;
 822
 823         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 824
 825         if (!prev || !get_macro_name(prev->pos))
 826                 return prev;
 827
 828         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 829                 if (positions_eq(tmp->pos, prev->pos))
 830                         continue;
 831                 if (prev->pos.line > tmp->pos.line)
 832                         return prev;
 833                 return tmp;
 834         } END_FOR_EACH_PTR_REVERSE(tmp);
 835         return prev;
 836 }
 837
 838 struct statement *get_prev_statement(void)
 839 {
 840         struct statement *tmp;
 841         int i;
 842
 843         i = 0;
 844         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 845                 if (i++ == 1)
 846                         return tmp;
 847         } END_FOR_EACH_PTR_REVERSE(tmp);
 848         return NULL;
 849 }
 850
 851 int get_param_num_from_sym(struct symbol *sym)
 852 {
 853         struct symbol *tmp;
 854         int i;
 855
 856         if (!cur_func_sym)
 857                 return -1;
 858
 859         i = 0;
 860         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 861                 if (tmp == sym)
 862                         return i;
 863                 i++;
 864         } END_FOR_EACH_PTR(tmp);
 865         return -1;
 866 }
 867
 868 int get_param_num(struct expression *expr)
 869 {
 870         struct symbol *sym;
 871         char *name;
 872
 873         if (!cur_func_sym)
 874                 return -1;
 875         name = expr_to_var_sym(expr, &sym);
 876         free_string(name);
 877         if (!sym)
 878                 return -1;
 879         return get_param_num_from_sym(sym);
 880 }
 881
 882 int ms_since(struct timeval *start)
 883 {
 884         struct timeval end;
 885         double diff;
 886
 887         gettimeofday(&end, NULL);
 888         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 889         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 890         return (int)diff;
 891 }
 892
 893 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 894 {
 895         if (!name || !sym)
 896                 return 0;
 897
 898         if (parent_is_null_var_sym(name, sym) ||
 899             parent_is_free_var_sym(name, sym))
 900                 return 1;
 901         return 0;
 902 }
 903
 904 int parent_is_gone(struct expression *expr)
 905 {
 906         struct symbol *sym;
 907         char *var;
 908         int ret = 0;
 909
 910         expr = strip_expr(expr);
 911         var = expr_to_var_sym(expr, &sym);
 912         if (!var || !sym)
 913                 goto free;
 914         ret = parent_is_gone_var_sym(var, sym);
 915 free:
 916         free_string(var);
 917         return ret;
 918 }
 919
 920 int invert_op(int op)
 921 {
 922         switch (op) {
 923         case '*':
 924                 return '/';
 925         case '/':
 926                 return '*';
 927         case '+':
 928                 return '-';
 929         case '-':
 930                 return '+';
 931         case SPECIAL_LEFTSHIFT:
 932                 return SPECIAL_RIGHTSHIFT;
 933         case SPECIAL_RIGHTSHIFT:
 934                 return SPECIAL_LEFTSHIFT;
 935         }
 936         return 0;
 937 }
 938
 939 int expr_equiv(struct expression *one, struct expression *two)
 940 {
 941         struct symbol *one_sym = NULL;
 942         struct symbol *two_sym = NULL;
 943         char *one_name = NULL;
 944         char *two_name = NULL;
 945         int ret = 0;
 946
 947         if (!one || !two)
 948                 return 0;
 949         if (one->type != two->type)
 950                 return 0;
 951
 952         one_name = expr_to_str_sym(one, &one_sym);
 953         if (!one_name)
 954                 goto free;
 955         two_name = expr_to_str_sym(two, &two_sym);
 956         if (!two_name)
 957                 goto free;
 958         if (one_sym != two_sym)
 959                 goto free;
 960         /*
 961          * This is a terrible hack because expr_to_str() sometimes gives up in
 962          * the middle and just returns what it has.  If you see a () you know
 963          * the string is bogus.
 964          */
 965         if (strstr(one_name, "()"))
 966                 goto free;
 967         if (strcmp(one_name, two_name) == 0)
 968                 ret = 1;
 969 free:
 970         free_string(one_name);
 971         free_string(two_name);
 972         return ret;
 973 }
 974
 975 void push_int(struct int_stack **stack, int num)
 976 {
 977         int *munged;
 978
 979         /*
 980          * Just put the int on directly instead of a pointer to the int.
 981          * Shift it to the left because Sparse uses the last two bits.
 982          * This is sort of a dirty hack, yes.
 983          */
 984
 985         munged = INT_PTR(num << 2);
 986
 987         add_ptr_list(stack, munged);
 988 }
 989
 990 int pop_int(struct int_stack **stack)
 991 {
 992         int *num;
 993
 994         num = last_ptr_list((struct ptr_list *)*stack);
 995         delete_ptr_list_last((struct ptr_list **)stack);
 996
 997         return PTR_INT(num) >> 2;
 998 }