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         expr = strip_expr(expr);
 450
 451         /*
 452          * Don't forget to keep get_complication_score() and store_all_links()
 453          * in sync.
 454          *
 455          */
 456
 457         if (!expr)
 458                 return 990;
 459
 460         switch (expr->type) {
 461         case EXPR_CALL:
 462                 return 991;
 463         case EXPR_COMPARE:
 464         case EXPR_BINOP:
 465                 return get_complication_score(expr->left) +
 466                        get_complication_score(expr->right);
 467         case EXPR_SYMBOL:
 468                 return 1;
 469         case EXPR_PREOP:
 470                 if (expr->op == '*' || expr->op == '(')
 471                         return get_complication_score(expr->unop);
 472                 return 993;
 473         case EXPR_DEREF:
 474                 return get_complication_score(expr->deref);
 475         case EXPR_VALUE:
 476         case EXPR_SIZEOF:
 477                 return 0;
 478         default:
 479                 return 994;
 480         }
 481 }
 482
 483 struct expression *reorder_expr_alphabetically(struct expression *expr)
 484 {
 485         struct expression *ret;
 486         char *left, *right;
 487
 488         if (expr->type != EXPR_BINOP)
 489                 return expr;
 490         if (expr->op != '+' && expr->op != '*')
 491                 return expr;
 492
 493         left = expr_to_var(expr->left);
 494         right = expr_to_var(expr->right);
 495         ret = expr;
 496         if (!left || !right)
 497                 goto free;
 498         if (strcmp(left, right) <= 0)
 499                 goto free;
 500
 501         ret = binop_expression(expr->right, expr->op, expr->left);
 502 free:
 503         free_string(left);
 504         free_string(right);
 505
 506         return ret;
 507 }
 508
 509 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 510 {
 511         struct var_sym_list *tmp_vsl;
 512         char *name;
 513         struct symbol *tmp;
 514         int score;
 515
 516         if (vsl)
 517                 *vsl = NULL;
 518         if (sym)
 519                 *sym = NULL;
 520
 521         expr = strip_parens(expr);
 522         if (!expr)
 523                 return NULL;
 524
 525         name = expr_to_var_sym(expr, &tmp);
 526         if (name && tmp) {
 527                 if (sym)
 528                         *sym = tmp;
 529                 if (vsl)
 530                         *vsl = expr_to_vsl(expr);
 531                 return name;
 532         }
 533         free_string(name);
 534
 535         score = get_complication_score(expr);
 536         if (score <= 0 || score > 2)
 537                 return NULL;
 538
 539         tmp_vsl = expr_to_vsl(expr);
 540         if (vsl) {
 541                 *vsl = tmp_vsl;
 542                 if (!*vsl)
 543                         return NULL;
 544         }
 545         if (sym) {
 546                 if (ptr_list_size((struct ptr_list *)tmp_vsl) == 1) {
 547                         struct var_sym *vs;
 548
 549                         vs = first_ptr_list((struct ptr_list *)tmp_vsl);
 550                         *sym = vs->sym;
 551                 }
 552         }
 553
 554         expr = reorder_expr_alphabetically(expr);
 555
 556         return expr_to_str(expr);
 557 }
 558
 559 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 560 {
 561         return expr_to_chunk_helper(expr, sym, NULL);
 562 }
 563
 564 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 565 {
 566         return expr_to_chunk_helper(expr, sym, vsl);
 567 }
 568
 569 int sym_name_is(const char *name, struct expression *expr)
 570 {
 571         if (!expr)
 572                 return 0;
 573         if (expr->type != EXPR_SYMBOL)
 574                 return 0;
 575         if (!strcmp(expr->symbol_name->name, name))
 576                 return 1;
 577         return 0;
 578 }
 579
 580 int is_zero(struct expression *expr)
 581 {
 582         sval_t sval;
 583
 584         if (get_value(expr, &sval) && sval.value == 0)
 585                 return 1;
 586         return 0;
 587 }
 588
 589 int is_array(struct expression *expr)
 590 {
 591         struct symbol *type;
 592
 593         expr = strip_expr(expr);
 594         if (!expr)
 595                 return 0;
 596
 597         if (expr->type == EXPR_PREOP && expr->op == '*') {
 598                 expr = strip_expr(expr->unop);
 599                 if (!expr)
 600                         return 0;
 601                 if (expr->type == EXPR_BINOP && expr->op == '+')
 602                         return 1;
 603         }
 604
 605         if (expr->type != EXPR_BINOP || expr->op != '+')
 606                 return 0;
 607
 608         type = get_type(expr->left);
 609         if (!type || type->type != SYM_ARRAY)
 610                 return 0;
 611
 612         return 1;
 613 }
 614
 615 struct expression *get_array_base(struct expression *expr)
 616 {
 617         if (!is_array(expr))
 618                 return NULL;
 619         expr = strip_expr(expr);
 620         if (expr->type == EXPR_PREOP && expr->op == '*')
 621                 expr = strip_expr(expr->unop);
 622         if (expr->type != EXPR_BINOP || expr->op != '+')
 623                 return NULL;
 624         return strip_parens(expr->left);
 625 }
 626
 627 struct expression *get_array_offset(struct expression *expr)
 628 {
 629         if (!is_array(expr))
 630                 return NULL;
 631         expr = strip_expr(expr);
 632         if (expr->type == EXPR_PREOP && expr->op == '*')
 633                 expr = strip_expr(expr->unop);
 634         if (expr->type != EXPR_BINOP || expr->op != '+')
 635                 return NULL;
 636         return strip_parens(expr->right);
 637 }
 638
 639 const char *show_state(struct smatch_state *state)
 640 {
 641         if (!state)
 642                 return NULL;
 643         return state->name;
 644 }
 645
 646 struct statement *get_expression_statement(struct expression *expr)
 647 {
 648         /* What are those things called? if (({....; ret;})) { ...*/
 649
 650         if (expr->type != EXPR_PREOP)
 651                 return NULL;
 652         if (expr->op != '(')
 653                 return NULL;
 654         if (!expr->unop)
 655                 return NULL;
 656         if (expr->unop->type != EXPR_STATEMENT)
 657                 return NULL;
 658         if (expr->unop->statement->type != STMT_COMPOUND)
 659                 return NULL;
 660         return expr->unop->statement;
 661 }
 662
 663 struct expression *strip_parens(struct expression *expr)
 664 {
 665         if (!expr)
 666                 return NULL;
 667
 668         if (expr->type == EXPR_PREOP) {
 669                 if (!expr->unop)
 670                         return expr;  /* parsing invalid code */
 671
 672                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 673                         expr->unop->statement->type == STMT_COMPOUND)
 674                         return expr;
 675                 if (expr->op == '(')
 676                         return strip_parens(expr->unop);
 677         }
 678         return expr;
 679 }
 680
 681 struct expression *strip_expr(struct expression *expr)
 682 {
 683         if (!expr)
 684                 return NULL;
 685
 686         switch (expr->type) {
 687         case EXPR_FORCE_CAST:
 688         case EXPR_CAST:
 689                 if (!expr->cast_expression)
 690                         return expr;
 691                 return strip_expr(expr->cast_expression);
 692         case EXPR_PREOP: {
 693                 struct expression *unop;
 694
 695                 if (!expr->unop)  /* parsing invalid code */
 696                         return expr;
 697
 698                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 699                         expr->unop->statement->type == STMT_COMPOUND)
 700                         return expr;
 701
 702                 unop = strip_expr(expr->unop);
 703
 704                 if (expr->op == '*' && unop &&
 705                     unop->type == EXPR_PREOP && unop->op == '&') {
 706                         struct symbol *type = get_type(unop->unop);
 707
 708                         if (type && type->type == SYM_ARRAY)
 709                                 return expr;
 710                         return strip_expr(unop->unop);
 711                 }
 712
 713                 if (expr->op == '(')
 714                         return unop;
 715
 716                 return expr;
 717         }
 718         case EXPR_CONDITIONAL:
 719                 if (known_condition_true(expr->conditional)) {
 720                         if (expr->cond_true)
 721                                 return strip_expr(expr->cond_true);
 722                         return strip_expr(expr->conditional);
 723                 }
 724                 if (known_condition_false(expr->conditional))
 725                         return strip_expr(expr->cond_false);
 726                 return expr;
 727         case EXPR_CALL:
 728                 if (sym_name_is("__builtin_expect", expr->fn) ||
 729                     sym_name_is("__builtin_bswap16", expr->fn) ||
 730                     sym_name_is("__builtin_bswap32", expr->fn) ||
 731                     sym_name_is("__builtin_bswap64", expr->fn)) {
 732                         expr = get_argument_from_call_expr(expr->args, 0);
 733                         return strip_expr(expr);
 734                 }
 735                 return expr;
 736         }
 737         return expr;
 738 }
 739
 740 static void delete_state_tracker(struct tracker *t)
 741 {
 742         delete_state(t->owner, t->name, t->sym);
 743         __free_tracker(t);
 744 }
 745
 746 void scoped_state(int my_id, const char *name, struct symbol *sym)
 747 {
 748         struct tracker *t;
 749
 750         t = alloc_tracker(my_id, name, sym);
 751         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 752 }
 753
 754 int is_error_return(struct expression *expr)
 755 {
 756         struct symbol *cur_func = cur_func_sym;
 757         struct range_list *rl;
 758         sval_t sval;
 759
 760         if (!expr)
 761                 return 0;
 762         if (cur_func->type != SYM_NODE)
 763                 return 0;
 764         cur_func = get_base_type(cur_func);
 765         if (cur_func->type != SYM_FN)
 766                 return 0;
 767         cur_func = get_base_type(cur_func);
 768         if (cur_func == &void_ctype)
 769                 return 0;
 770         if (option_project == PROJ_KERNEL &&
 771             get_implied_rl(expr, &rl) &&
 772             rl_type(rl) == &int_ctype &&
 773             sval_is_negative(rl_min(rl)) &&
 774             rl_max(rl).value == -1)
 775                 return 1;
 776         if (!get_implied_value(expr, &sval))
 777                 return 0;
 778         if (sval.value < 0)
 779                 return 1;
 780         if (cur_func->type == SYM_PTR && sval.value == 0)
 781                 return 1;
 782         return 0;
 783 }
 784
 785 int getting_address(void)
 786 {
 787         struct expression *tmp;
 788         int i = 0;
 789         int dot_ops = 0;
 790
 791         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 792                 if (!i++)
 793                         continue;
 794                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 795                         continue;
 796                 if (tmp->op == '.' && !dot_ops++)
 797                         continue;
 798                 if (tmp->op == '&')
 799                         return 1;
 800                 return 0;
 801         } END_FOR_EACH_PTR_REVERSE(tmp);
 802         return 0;
 803 }
 804
 805 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 806 {
 807         struct symbol *sym;
 808
 809         expr = strip_expr(expr);
 810         if (expr->type != EXPR_DEREF)
 811                 return 0;
 812         if (!expr->member)
 813                 return 0;
 814
 815         sym = get_type(expr->deref);
 816         if (!sym)
 817                 return 0;
 818         if (sym->type == SYM_UNION)
 819                 return 0;
 820         if (!sym->ident)
 821                 return 0;
 822
 823         *type = sym->ident->name;
 824         *member = expr->member->name;
 825         return 1;
 826 }
 827
 828 char *get_member_name(struct expression *expr)
 829 {
 830         char buf[256];
 831         struct symbol *sym;
 832
 833         expr = strip_expr(expr);
 834         if (!expr || expr->type != EXPR_DEREF)
 835                 return NULL;
 836         if (!expr->member)
 837                 return NULL;
 838
 839         sym = get_type(expr->deref);
 840         if (!sym)
 841                 return NULL;
 842         if (sym->type == SYM_UNION) {
 843                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 844                          sym->ident ? sym->ident->name : "anonymous",
 845                          expr->member->name);
 846                 return alloc_string(buf);
 847         }
 848         if (!sym->ident)
 849                 return NULL;
 850         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 851         return alloc_string(buf);
 852 }
 853
 854 int cmp_pos(struct position pos1, struct position pos2)
 855 {
 856         /* the stream position is ... */
 857         if (pos1.stream > pos2.stream)
 858                 return -1;
 859         if (pos1.stream < pos2.stream)
 860                 return 1;
 861
 862         if (pos1.line < pos2.line)
 863                 return -1;
 864         if (pos1.line > pos2.line)
 865                 return 1;
 866
 867         if (pos1.pos < pos2.pos)
 868                 return -1;
 869         if (pos1.pos > pos2.pos)
 870                 return 1;
 871
 872         return 0;
 873 }
 874
 875 int positions_eq(struct position pos1, struct position pos2)
 876 {
 877         if (pos1.line != pos2.line)
 878                 return 0;
 879         if (pos1.pos != pos2.pos)
 880                 return 0;
 881         if (pos1.stream != pos2.stream)
 882                 return 0;
 883         return 1;
 884 }
 885
 886 struct statement *get_current_statement(void)
 887 {
 888         struct statement *prev, *tmp;
 889
 890         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 891
 892         if (!prev || !get_macro_name(prev->pos))
 893                 return prev;
 894
 895         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 896                 if (positions_eq(tmp->pos, prev->pos))
 897                         continue;
 898                 if (prev->pos.line > tmp->pos.line)
 899                         return prev;
 900                 return tmp;
 901         } END_FOR_EACH_PTR_REVERSE(tmp);
 902         return prev;
 903 }
 904
 905 struct statement *get_prev_statement(void)
 906 {
 907         struct statement *tmp;
 908         int i;
 909
 910         i = 0;
 911         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 912                 if (i++ == 1)
 913                         return tmp;
 914         } END_FOR_EACH_PTR_REVERSE(tmp);
 915         return NULL;
 916 }
 917
 918 struct expression *get_last_expr_from_expression_stmt(struct expression *expr)
 919 {
 920         struct statement *stmt;
 921         struct statement *last_stmt;
 922
 923         while (expr->type == EXPR_PREOP && expr->op == '(')
 924                 expr = expr->unop;
 925         if (expr->type != EXPR_STATEMENT)
 926                 return NULL;
 927         stmt = expr->statement;
 928         if (!stmt)
 929                 return NULL;
 930         if (stmt->type == STMT_COMPOUND) {
 931                 last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 932                 if (!last_stmt)
 933                         return NULL;
 934                 if (last_stmt->type == STMT_LABEL)
 935                         last_stmt = last_stmt->label_statement;
 936                 if (last_stmt->type != STMT_EXPRESSION)
 937                         return NULL;
 938                 return last_stmt->expression;
 939         }
 940         if (stmt->type == STMT_EXPRESSION)
 941                 return stmt->expression;
 942         return NULL;
 943 }
 944
 945 int get_param_num_from_sym(struct symbol *sym)
 946 {
 947         struct symbol *tmp;
 948         int i;
 949
 950         if (!cur_func_sym)
 951                 return -1;
 952
 953         i = 0;
 954         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 955                 if (tmp == sym)
 956                         return i;
 957                 i++;
 958         } END_FOR_EACH_PTR(tmp);
 959         return -1;
 960 }
 961
 962 int get_param_num(struct expression *expr)
 963 {
 964         struct symbol *sym;
 965         char *name;
 966
 967         if (!cur_func_sym)
 968                 return -1;
 969         name = expr_to_var_sym(expr, &sym);
 970         free_string(name);
 971         if (!sym)
 972                 return -1;
 973         return get_param_num_from_sym(sym);
 974 }
 975
 976 int ms_since(struct timeval *start)
 977 {
 978         struct timeval end;
 979         double diff;
 980
 981         gettimeofday(&end, NULL);
 982         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 983         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 984         return (int)diff;
 985 }
 986
 987 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 988 {
 989         if (!name || !sym)
 990                 return 0;
 991
 992         if (parent_is_null_var_sym(name, sym) ||
 993             parent_is_free_var_sym(name, sym))
 994                 return 1;
 995         return 0;
 996 }
 997
 998 int parent_is_gone(struct expression *expr)
 999 {
1000         struct symbol *sym;
1001         char *var;
1002         int ret = 0;
1003
1004         expr = strip_expr(expr);
1005         var = expr_to_var_sym(expr, &sym);
1006         if (!var || !sym)
1007                 goto free;
1008         ret = parent_is_gone_var_sym(var, sym);
1009 free:
1010         free_string(var);
1011         return ret;
1012 }
1013
1014 int invert_op(int op)
1015 {
1016         switch (op) {
1017         case '*':
1018                 return '/';
1019         case '/':
1020                 return '*';
1021         case '+':
1022                 return '-';
1023         case '-':
1024                 return '+';
1025         case SPECIAL_LEFTSHIFT:
1026                 return SPECIAL_RIGHTSHIFT;
1027         case SPECIAL_RIGHTSHIFT:
1028                 return SPECIAL_LEFTSHIFT;
1029         }
1030         return 0;
1031 }
1032
1033 int expr_equiv(struct expression *one, struct expression *two)
1034 {
1035         struct symbol *one_sym = NULL;
1036         struct symbol *two_sym = NULL;
1037         char *one_name = NULL;
1038         char *two_name = NULL;
1039         int ret = 0;
1040
1041         if (!one || !two)
1042                 return 0;
1043         if (one->type != two->type)
1044                 return 0;
1045
1046         one_name = expr_to_str_sym(one, &one_sym);
1047         if (!one_name)
1048                 goto free;
1049         two_name = expr_to_str_sym(two, &two_sym);
1050         if (!two_name)
1051                 goto free;
1052         if (one_sym != two_sym)
1053                 goto free;
1054         /*
1055          * This is a terrible hack because expr_to_str() sometimes gives up in
1056          * the middle and just returns what it has.  If you see a () you know
1057          * the string is bogus.
1058          */
1059         if (strstr(one_name, "()"))
1060                 goto free;
1061         if (strcmp(one_name, two_name) == 0)
1062                 ret = 1;
1063 free:
1064         free_string(one_name);
1065         free_string(two_name);
1066         return ret;
1067 }
1068
1069 void push_int(struct int_stack **stack, int num)
1070 {
1071         int *munged;
1072
1073         /*
1074          * Just put the int on directly instead of a pointer to the int.
1075          * Shift it to the left because Sparse uses the last two bits.
1076          * This is sort of a dirty hack, yes.
1077          */
1078
1079         munged = INT_PTR(num << 2);
1080
1081         add_ptr_list(stack, munged);
1082 }
1083
1084 int pop_int(struct int_stack **stack)
1085 {
1086         int *num;
1087
1088         num = last_ptr_list((struct ptr_list *)*stack);
1089         delete_ptr_list_last((struct ptr_list **)stack);
1090
1091         return PTR_INT(num) >> 2;
1092 }