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)  /* Sometimes we haven't set up the ->parent yet. FIXME!! */
 143                 return expr->left;
 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 struct expr_str_cache_results {
 330         struct expression *expr;
 331         int no_parens;
 332         char str[VAR_LEN];
 333         struct symbol *sym;
 334         int complicated;
 335 };
 336
 337 static void get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 338                                      struct expression *expr, int len,
 339                                      int *complicated, int no_parens)
 340 {
 341         static struct expr_str_cache_results cached[8];
 342         struct symbol *tmp_sym = NULL;
 343         static int idx;
 344         int i;
 345
 346         for (i = 0; i < ARRAY_SIZE(cached); i++) {
 347                 if (expr == cached[i].expr &&
 348                     no_parens == cached[i].no_parens) {
 349                         strncpy(buf, cached[i].str, len);
 350                         if (sym_ptr)
 351                                 *sym_ptr = cached[i].sym;
 352                         *complicated = cached[i].complicated;
 353                         return;
 354                 }
 355         }
 356
 357         __get_variable_from_expr(&tmp_sym, buf, expr, len, complicated, no_parens);
 358         if (sym_ptr)
 359                 *sym_ptr = tmp_sym;
 360
 361         cached[idx].expr = expr;
 362         cached[idx].no_parens = no_parens;
 363         strncpy(cached[idx].str, buf, VAR_LEN);
 364         cached[idx].sym = tmp_sym;
 365         cached[idx].complicated = *complicated;
 366
 367         idx = (idx + 1) % ARRAY_SIZE(cached);
 368 }
 369
 370 /*
 371  * This is returns a stylized "c looking" representation of the
 372  * variable name.
 373  *
 374  * It uses the same buffer every time so you have to save the result
 375  * yourself if you want to keep it.
 376  *
 377  */
 378
 379 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 380 {
 381         static char var_name[VAR_LEN];
 382         int complicated = 0;
 383
 384         if (sym_ptr)
 385                 *sym_ptr = NULL;
 386         var_name[0] = '\0';
 387
 388         if (!expr)
 389                 return NULL;
 390         get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 391                                  &complicated, 0);
 392         if (complicated < 2)
 393                 return alloc_string(var_name);
 394         else
 395                 return NULL;
 396 }
 397
 398 char *expr_to_str(struct expression *expr)
 399 {
 400         return expr_to_str_sym(expr, NULL);
 401 }
 402
 403 /*
 404  * get_variable_from_expr_simple() only returns simple variables.
 405  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 406  * then it returns NULL.
 407  */
 408 char *expr_to_var_sym(struct expression *expr,
 409                                     struct symbol **sym_ptr)
 410 {
 411         static char var_name[VAR_LEN];
 412         int complicated = 0;
 413
 414         if (sym_ptr)
 415                 *sym_ptr = NULL;
 416         var_name[0] = '\0';
 417
 418         if (!expr)
 419                 return NULL;
 420         expr = strip_expr(expr);
 421         get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 422                                  &complicated, 1);
 423
 424         if (complicated) {
 425                 if (sym_ptr)
 426                         *sym_ptr = NULL;
 427                 return NULL;
 428         }
 429         return alloc_string(var_name);
 430 }
 431
 432 char *expr_to_var(struct expression *expr)
 433 {
 434         return expr_to_var_sym(expr, NULL);
 435 }
 436
 437 struct symbol *expr_to_sym(struct expression *expr)
 438 {
 439         struct symbol *sym;
 440         char *name;
 441
 442         name = expr_to_var_sym(expr, &sym);
 443         free_string(name);
 444         return sym;
 445 }
 446
 447 int get_complication_score(struct expression *expr)
 448 {
 449         int score = 0;
 450
 451         expr = strip_expr(expr);
 452
 453         /*
 454          * Don't forget to keep get_complication_score() and store_all_links()
 455          * in sync.
 456          *
 457          */
 458
 459         if (!expr)
 460                 return 990;
 461
 462         switch (expr->type) {
 463         case EXPR_CALL:
 464                 return 991;
 465         case EXPR_COMPARE:
 466         case EXPR_BINOP:
 467                 score += get_complication_score(expr->left);
 468                 score += get_complication_score(expr->right);
 469                 return score;
 470         case EXPR_SYMBOL:
 471                 if (is_local_variable(expr))
 472                         return 1;
 473                 return 999;
 474         case EXPR_PREOP:
 475                 if (expr->op == '*')
 476                         return score + get_complication_score(expr->unop);
 477                 return 993;
 478         case EXPR_DEREF:
 479                 return score + get_complication_score(expr->deref);
 480         case EXPR_VALUE:
 481                 return 0;
 482         default:
 483                 return 994;
 484         }
 485 }
 486
 487 struct expression *reorder_expr_alphabetically(struct expression *expr)
 488 {
 489         struct expression *ret;
 490         char *left, *right;
 491
 492         if (expr->type != EXPR_BINOP)
 493                 return expr;
 494         if (expr->op != '+' && expr->op != '*')
 495                 return expr;
 496
 497         left = expr_to_var(expr->left);
 498         right = expr_to_var(expr->right);
 499         ret = expr;
 500         if (!left || !right)
 501                 goto free;
 502         if (strcmp(left, right) <= 0)
 503                 goto free;
 504
 505         ret = binop_expression(expr->right, expr->op, expr->left);
 506 free:
 507         free_string(left);
 508         free_string(right);
 509
 510         return ret;
 511 }
 512
 513 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 514 {
 515         char *name;
 516         struct symbol *tmp;
 517         int score;
 518
 519         if (vsl)
 520                 *vsl = NULL;
 521         if (sym)
 522                 *sym = NULL;
 523
 524         expr = strip_parens(expr);
 525         if (!expr)
 526                 return NULL;
 527
 528         name = expr_to_var_sym(expr, &tmp);
 529         if (name && tmp) {
 530                 if (sym)
 531                         *sym = tmp;
 532                 if (vsl)
 533                         *vsl = expr_to_vsl(expr);
 534                 return name;
 535         }
 536         free_string(name);
 537
 538         score = get_complication_score(expr);
 539         if (score <= 0 || score > 2)
 540                 return NULL;
 541
 542         if (vsl) {
 543                 *vsl = expr_to_vsl(expr);
 544                 if (!*vsl)
 545                         return NULL;
 546         }
 547
 548         expr = reorder_expr_alphabetically(expr);
 549
 550         return expr_to_str(expr);
 551 }
 552
 553 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 554 {
 555         return expr_to_chunk_helper(expr, sym, NULL);
 556 }
 557
 558 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 559 {
 560         return expr_to_chunk_helper(expr, sym, vsl);
 561 }
 562
 563 int sym_name_is(const char *name, struct expression *expr)
 564 {
 565         if (!expr)
 566                 return 0;
 567         if (expr->type != EXPR_SYMBOL)
 568                 return 0;
 569         if (!strcmp(expr->symbol_name->name, name))
 570                 return 1;
 571         return 0;
 572 }
 573
 574 int is_zero(struct expression *expr)
 575 {
 576         sval_t sval;
 577
 578         if (get_value(expr, &sval) && sval.value == 0)
 579                 return 1;
 580         return 0;
 581 }
 582
 583 int is_array(struct expression *expr)
 584 {
 585         struct symbol *type;
 586
 587         expr = strip_expr(expr);
 588         if (!expr)
 589                 return 0;
 590
 591         if (expr->type == EXPR_PREOP && expr->op == '*') {
 592                 expr = strip_expr(expr->unop);
 593                 if (!expr)
 594                         return 0;
 595                 if (expr->type == EXPR_BINOP && expr->op == '+')
 596                         return 1;
 597         }
 598
 599         if (expr->type != EXPR_BINOP || expr->op != '+')
 600                 return 0;
 601
 602         type = get_type(expr->left);
 603         if (!type || type->type != SYM_ARRAY)
 604                 return 0;
 605
 606         return 1;
 607 }
 608
 609 struct expression *get_array_base(struct expression *expr)
 610 {
 611         if (!is_array(expr))
 612                 return NULL;
 613         expr = strip_expr(expr);
 614         if (expr->type == EXPR_PREOP && expr->op == '*')
 615                 expr = strip_expr(expr->unop);
 616         if (expr->type != EXPR_BINOP || expr->op != '+')
 617                 return NULL;
 618         return strip_parens(expr->left);
 619 }
 620
 621 struct expression *get_array_offset(struct expression *expr)
 622 {
 623         if (!is_array(expr))
 624                 return NULL;
 625         expr = strip_expr(expr);
 626         if (expr->type == EXPR_PREOP && expr->op == '*')
 627                 expr = strip_expr(expr->unop);
 628         if (expr->type != EXPR_BINOP || expr->op != '+')
 629                 return NULL;
 630         return strip_parens(expr->right);
 631 }
 632
 633 const char *show_state(struct smatch_state *state)
 634 {
 635         if (!state)
 636                 return NULL;
 637         return state->name;
 638 }
 639
 640 struct statement *get_expression_statement(struct expression *expr)
 641 {
 642         /* What are those things called? if (({....; ret;})) { ...*/
 643
 644         if (expr->type != EXPR_PREOP)
 645                 return NULL;
 646         if (expr->op != '(')
 647                 return NULL;
 648         if (!expr->unop)
 649                 return NULL;
 650         if (expr->unop->type != EXPR_STATEMENT)
 651                 return NULL;
 652         if (expr->unop->statement->type != STMT_COMPOUND)
 653                 return NULL;
 654         return expr->unop->statement;
 655 }
 656
 657 struct expression *strip_parens(struct expression *expr)
 658 {
 659         if (!expr)
 660                 return NULL;
 661
 662         if (expr->type == EXPR_PREOP) {
 663                 if (!expr->unop)
 664                         return expr;  /* parsing invalid code */
 665
 666                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 667                         expr->unop->statement->type == STMT_COMPOUND)
 668                         return expr;
 669                 if (expr->op == '(')
 670                         return strip_parens(expr->unop);
 671         }
 672         return expr;
 673 }
 674
 675 struct expression *strip_expr(struct expression *expr)
 676 {
 677         if (!expr)
 678                 return NULL;
 679
 680         switch (expr->type) {
 681         case EXPR_FORCE_CAST:
 682         case EXPR_CAST:
 683                 return strip_expr(expr->cast_expression);
 684         case EXPR_PREOP: {
 685                 struct expression *unop;
 686
 687                 if (!expr->unop)  /* parsing invalid code */
 688                         return expr;
 689
 690                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 691                         expr->unop->statement->type == STMT_COMPOUND)
 692                         return expr;
 693
 694                 unop = strip_expr(expr->unop);
 695
 696                 if (expr->op == '*' && unop &&
 697                     unop->type == EXPR_PREOP && unop->op == '&') {
 698                         struct symbol *type = get_type(unop->unop);
 699
 700                         if (type && type->type == SYM_ARRAY)
 701                                 return expr;
 702                         return strip_expr(unop->unop);
 703                 }
 704
 705                 if (expr->op == '(')
 706                         return unop;
 707
 708                 return expr;
 709         }
 710         case EXPR_CONDITIONAL:
 711                 if (known_condition_true(expr->conditional)) {
 712                         if (expr->cond_true)
 713                                 return strip_expr(expr->cond_true);
 714                         return strip_expr(expr->conditional);
 715                 }
 716                 if (known_condition_false(expr->conditional))
 717                         return strip_expr(expr->cond_false);
 718                 return expr;
 719         case EXPR_CALL:
 720                 if (sym_name_is("__builtin_expect", expr->fn)) {
 721                         expr = get_argument_from_call_expr(expr->args, 0);
 722                         return strip_expr(expr);
 723                 }
 724                 return expr;
 725         }
 726         return expr;
 727 }
 728
 729 static void delete_state_tracker(struct tracker *t)
 730 {
 731         delete_state(t->owner, t->name, t->sym);
 732         __free_tracker(t);
 733 }
 734
 735 void scoped_state(int my_id, const char *name, struct symbol *sym)
 736 {
 737         struct tracker *t;
 738
 739         t = alloc_tracker(my_id, name, sym);
 740         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 741 }
 742
 743 int is_error_return(struct expression *expr)
 744 {
 745         struct symbol *cur_func = cur_func_sym;
 746         sval_t sval;
 747
 748         if (!expr)
 749                 return 0;
 750         if (cur_func->type != SYM_NODE)
 751                 return 0;
 752         cur_func = get_base_type(cur_func);
 753         if (cur_func->type != SYM_FN)
 754                 return 0;
 755         cur_func = get_base_type(cur_func);
 756         if (cur_func == &void_ctype)
 757                 return 0;
 758         if (!get_implied_value(expr, &sval))
 759                 return 0;
 760         if (sval.value < 0)
 761                 return 1;
 762         if (cur_func->type == SYM_PTR && sval.value == 0)
 763                 return 1;
 764         return 0;
 765 }
 766
 767 int getting_address(void)
 768 {
 769         struct expression *tmp;
 770         int i = 0;
 771         int dot_ops = 0;
 772
 773         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 774                 if (!i++)
 775                         continue;
 776                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 777                         continue;
 778                 if (tmp->op == '.' && !dot_ops++)
 779                         continue;
 780                 if (tmp->op == '&')
 781                         return 1;
 782                 return 0;
 783         } END_FOR_EACH_PTR_REVERSE(tmp);
 784         return 0;
 785 }
 786
 787 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 788 {
 789         struct symbol *sym;
 790
 791         expr = strip_expr(expr);
 792         if (expr->type != EXPR_DEREF)
 793                 return 0;
 794         if (!expr->member)
 795                 return 0;
 796
 797         sym = get_type(expr->deref);
 798         if (!sym)
 799                 return 0;
 800         if (sym->type == SYM_UNION)
 801                 return 0;
 802         if (!sym->ident)
 803                 return 0;
 804
 805         *type = sym->ident->name;
 806         *member = expr->member->name;
 807         return 1;
 808 }
 809
 810 char *get_member_name(struct expression *expr)
 811 {
 812         char buf[256];
 813         struct symbol *sym;
 814
 815         expr = strip_expr(expr);
 816         if (!expr || expr->type != EXPR_DEREF)
 817                 return NULL;
 818         if (!expr->member)
 819                 return NULL;
 820
 821         sym = get_type(expr->deref);
 822         if (!sym)
 823                 return NULL;
 824         if (sym->type == SYM_UNION) {
 825                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 826                          sym->ident ? sym->ident->name : "anonymous",
 827                          expr->member->name);
 828                 return alloc_string(buf);
 829         }
 830         if (!sym->ident)
 831                 return NULL;
 832         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 833         return alloc_string(buf);
 834 }
 835
 836 int cmp_pos(struct position pos1, struct position pos2)
 837 {
 838         /* the stream position is ... */
 839         if (pos1.stream > pos2.stream)
 840                 return -1;
 841         if (pos1.stream < pos2.stream)
 842                 return 1;
 843
 844         if (pos1.line < pos2.line)
 845                 return -1;
 846         if (pos1.line > pos2.line)
 847                 return 1;
 848
 849         if (pos1.pos < pos2.pos)
 850                 return -1;
 851         if (pos1.pos > pos2.pos)
 852                 return 1;
 853
 854         return 0;
 855 }
 856
 857 int positions_eq(struct position pos1, struct position pos2)
 858 {
 859         if (pos1.line != pos2.line)
 860                 return 0;
 861         if (pos1.pos != pos2.pos)
 862                 return 0;
 863         if (pos1.stream != pos2.stream)
 864                 return 0;
 865         return 1;
 866 }
 867
 868 struct statement *get_current_statement(void)
 869 {
 870         struct statement *prev, *tmp;
 871
 872         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 873
 874         if (!prev || !get_macro_name(prev->pos))
 875                 return prev;
 876
 877         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 878                 if (positions_eq(tmp->pos, prev->pos))
 879                         continue;
 880                 if (prev->pos.line > tmp->pos.line)
 881                         return prev;
 882                 return tmp;
 883         } END_FOR_EACH_PTR_REVERSE(tmp);
 884         return prev;
 885 }
 886
 887 struct statement *get_prev_statement(void)
 888 {
 889         struct statement *tmp;
 890         int i;
 891
 892         i = 0;
 893         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 894                 if (i++ == 1)
 895                         return tmp;
 896         } END_FOR_EACH_PTR_REVERSE(tmp);
 897         return NULL;
 898 }
 899
 900 int get_param_num_from_sym(struct symbol *sym)
 901 {
 902         struct symbol *tmp;
 903         int i;
 904
 905         if (!cur_func_sym)
 906                 return -1;
 907
 908         i = 0;
 909         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 910                 if (tmp == sym)
 911                         return i;
 912                 i++;
 913         } END_FOR_EACH_PTR(tmp);
 914         return -1;
 915 }
 916
 917 int get_param_num(struct expression *expr)
 918 {
 919         struct symbol *sym;
 920         char *name;
 921
 922         if (!cur_func_sym)
 923                 return -1;
 924         name = expr_to_var_sym(expr, &sym);
 925         free_string(name);
 926         if (!sym)
 927                 return -1;
 928         return get_param_num_from_sym(sym);
 929 }
 930
 931 int ms_since(struct timeval *start)
 932 {
 933         struct timeval end;
 934         double diff;
 935
 936         gettimeofday(&end, NULL);
 937         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 938         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 939         return (int)diff;
 940 }
 941
 942 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 943 {
 944         if (!name || !sym)
 945                 return 0;
 946
 947         if (parent_is_null_var_sym(name, sym) ||
 948             parent_is_free_var_sym(name, sym))
 949                 return 1;
 950         return 0;
 951 }
 952
 953 int parent_is_gone(struct expression *expr)
 954 {
 955         struct symbol *sym;
 956         char *var;
 957         int ret = 0;
 958
 959         expr = strip_expr(expr);
 960         var = expr_to_var_sym(expr, &sym);
 961         if (!var || !sym)
 962                 goto free;
 963         ret = parent_is_gone_var_sym(var, sym);
 964 free:
 965         free_string(var);
 966         return ret;
 967 }
 968
 969 int invert_op(int op)
 970 {
 971         switch (op) {
 972         case '*':
 973                 return '/';
 974         case '/':
 975                 return '*';
 976         case '+':
 977                 return '-';
 978         case '-':
 979                 return '+';
 980         case SPECIAL_LEFTSHIFT:
 981                 return SPECIAL_RIGHTSHIFT;
 982         case SPECIAL_RIGHTSHIFT:
 983                 return SPECIAL_LEFTSHIFT;
 984         }
 985         return 0;
 986 }
 987
 988 int expr_equiv(struct expression *one, struct expression *two)
 989 {
 990         struct symbol *one_sym = NULL;
 991         struct symbol *two_sym = NULL;
 992         char *one_name = NULL;
 993         char *two_name = NULL;
 994         int ret = 0;
 995
 996         if (!one || !two)
 997                 return 0;
 998         if (one->type != two->type)
 999                 return 0;
1000
1001         one_name = expr_to_str_sym(one, &one_sym);
1002         if (!one_name)
1003                 goto free;
1004         two_name = expr_to_str_sym(two, &two_sym);
1005         if (!two_name)
1006                 goto free;
1007         if (one_sym != two_sym)
1008                 goto free;
1009         /*
1010          * This is a terrible hack because expr_to_str() sometimes gives up in
1011          * the middle and just returns what it has.  If you see a () you know
1012          * the string is bogus.
1013          */
1014         if (strstr(one_name, "()"))
1015                 goto free;
1016         if (strcmp(one_name, two_name) == 0)
1017                 ret = 1;
1018 free:
1019         free_string(one_name);
1020         free_string(two_name);
1021         return ret;
1022 }
1023
1024 void push_int(struct int_stack **stack, int num)
1025 {
1026         int *munged;
1027
1028         /*
1029          * Just put the int on directly instead of a pointer to the int.
1030          * Shift it to the left because Sparse uses the last two bits.
1031          * This is sort of a dirty hack, yes.
1032          */
1033
1034         munged = INT_PTR(num << 2);
1035
1036         add_ptr_list(stack, munged);
1037 }
1038
1039 int pop_int(struct int_stack **stack)
1040 {
1041         int *num;
1042
1043         num = last_ptr_list((struct ptr_list *)*stack);
1044         delete_ptr_list_last((struct ptr_list **)stack);
1045
1046         return PTR_INT(num) >> 2;
1047 }