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 char *alloc_string_newline(const char *str)
  43 {
  44         char *tmp;
  45         int len;
  46
  47         if (!str)
  48                 return NULL;
  49         len = strlen(str);
  50         tmp = malloc(len + 2);
  51         snprintf(tmp, len + 2, "%s\n", str);
  52         return tmp;
  53 }
  54
  55 void free_string(char *str)
  56 {
  57         free(str);
  58 }
  59
  60 void remove_parens(char *str)
  61 {
  62         char *src, *dst;
  63
  64         dst = src = str;
  65         while (*src != '\0') {
  66                 if (*src == '(' || *src == ')') {
  67                         src++;
  68                         continue;
  69                 }
  70                 *dst++ = *src++;
  71         }
  72         *dst = *src;
  73 }
  74
  75 struct smatch_state *alloc_state_num(int num)
  76 {
  77         struct smatch_state *state;
  78         static char buff[256];
  79
  80         state = __alloc_smatch_state(0);
  81         snprintf(buff, 255, "%d", num);
  82         buff[255] = '\0';
  83         state->name = alloc_string(buff);
  84         state->data = INT_PTR(num);
  85         return state;
  86 }
  87
  88 struct smatch_state *alloc_state_str(const char *name)
  89 {
  90         struct smatch_state *state;
  91
  92         state = __alloc_smatch_state(0);
  93         state->name = alloc_string(name);
  94         return state;
  95 }
  96
  97 struct smatch_state *merge_str_state(struct smatch_state *s1, struct smatch_state *s2)
  98 {
  99         if (!s1->name || !s2->name)
 100                 return &merged;
 101         if (strcmp(s1->name, s2->name) == 0)
 102                 return s1;
 103         return &merged;
 104 }
 105
 106 struct smatch_state *alloc_state_expr(struct expression *expr)
 107 {
 108         struct smatch_state *state;
 109         char *name;
 110
 111         expr = strip_expr(expr);
 112         name = expr_to_str(expr);
 113         if (!name)
 114                 return NULL;
 115
 116         state = __alloc_smatch_state(0);
 117         state->name = alloc_sname(name);
 118         free_string(name);
 119         state->data = expr;
 120         return state;
 121 }
 122
 123 void append(char *dest, const char *data, int buff_len)
 124 {
 125         strncat(dest, data, buff_len - strlen(dest) - 1);
 126 }
 127
 128 /*
 129  * If you have "foo(a, b, 1);" then use
 130  * get_argument_from_call_expr(expr, 0) to return the expression for
 131  * a.  Yes, it does start counting from 0.
 132  */
 133 struct expression *get_argument_from_call_expr(struct expression_list *args,
 134                                                int num)
 135 {
 136         struct expression *expr;
 137         int i = 0;
 138
 139         if (!args)
 140                 return NULL;
 141
 142         FOR_EACH_PTR(args, expr) {
 143                 if (i == num)
 144                         return expr;
 145                 i++;
 146         } END_FOR_EACH_PTR(expr);
 147         return NULL;
 148 }
 149
 150 struct expression *get_array_expr(struct expression *expr)
 151 {
 152         struct expression *parent;
 153         struct symbol *type;
 154
 155         if (expr->type != EXPR_BINOP || expr->op != '+')
 156                 return NULL;
 157
 158         type = get_type(expr->left);
 159         if (!type)
 160                 return NULL;
 161         if (type->type == SYM_ARRAY)
 162                 return expr->left;
 163         if (type->type != SYM_PTR)
 164                 return NULL;
 165
 166         parent = expr_get_parent_expr(expr);
 167         if (!parent)  /* Sometimes we haven't set up the ->parent yet. FIXME!! */
 168                 return expr->left;
 169         if (parent->type == EXPR_PREOP && parent->op == '*')
 170                 return expr->left;
 171
 172         return NULL;
 173 }
 174
 175 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 176                                      struct expression *expr, int len,
 177                                      int *complicated)
 178 {
 179         if (!expr) {
 180                 /* can't happen on valid code */
 181                 *complicated = 1;
 182                 return;
 183         }
 184
 185         switch (expr->type) {
 186         case EXPR_DEREF: {
 187                 struct expression *deref;
 188                 int op;
 189
 190                 deref = expr->deref;
 191                 op = deref->op;
 192                 if (deref->type == EXPR_PREOP && op == '*') {
 193                         struct expression *unop = strip_expr(deref->unop);
 194
 195                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 196                                 deref = unop->unop;
 197                                 op = '.';
 198                         } else {
 199                                 if (!is_pointer(deref) && !is_pointer(deref->unop))
 200                                         op = '.';
 201                                 deref = deref->unop;
 202                         }
 203                 }
 204
 205                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated);
 206
 207                 if (op == '*')
 208                         append(buf, "->", len);
 209                 else
 210                         append(buf, ".", len);
 211
 212                 if (expr->member)
 213                         append(buf, expr->member->name, len);
 214                 else
 215                         append(buf, "unknown_member", len);
 216
 217                 return;
 218         }
 219         case EXPR_SYMBOL:
 220                 if (expr->symbol_name)
 221                         append(buf, expr->symbol_name->name, len);
 222                 if (sym_ptr) {
 223                         if (*sym_ptr)
 224                                 *complicated = 1;
 225                         *sym_ptr = expr->symbol;
 226                 }
 227                 return;
 228         case EXPR_PREOP: {
 229                 const char *tmp;
 230
 231                 if (get_expression_statement(expr)) {
 232                         *complicated = 2;
 233                         return;
 234                 }
 235
 236                 if (expr->op == '(') {
 237                         if (expr->unop->type != EXPR_SYMBOL)
 238                                 append(buf, "(", len);
 239                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 240                         tmp = show_special(expr->op);
 241                         append(buf, tmp, len);
 242                 }
 243                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 244                                                  len, complicated);
 245
 246                 if (expr->op == '(' && expr->unop->type != EXPR_SYMBOL)
 247                         append(buf, ")", len);
 248
 249                 if (expr->op == SPECIAL_DECREMENT ||
 250                     expr->op == SPECIAL_INCREMENT)
 251                         *complicated = 1;
 252
 253                 return;
 254         }
 255         case EXPR_POSTOP: {
 256                 const char *tmp;
 257
 258                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 259                                                  len, complicated);
 260                 tmp = show_special(expr->op);
 261                 append(buf, tmp, len);
 262
 263                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 264                         *complicated = 1;
 265                 return;
 266         }
 267         case EXPR_ASSIGNMENT:
 268         case EXPR_COMPARE:
 269         case EXPR_LOGICAL:
 270         case EXPR_BINOP: {
 271                 char tmp[10];
 272                 struct expression *array_expr;
 273
 274                 *complicated = 1;
 275                 array_expr = get_array_expr(expr);
 276                 if (array_expr) {
 277                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated);
 278                         append(buf, "[", len);
 279                 } else {
 280                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated);
 281                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 282                         append(buf, tmp, len);
 283                 }
 284                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated);
 285                 if (array_expr)
 286                         append(buf, "]", len);
 287                 return;
 288         }
 289         case EXPR_VALUE: {
 290                 sval_t sval = {};
 291                 char tmp[25];
 292
 293                 *complicated = 1;
 294                 if (!get_value(expr, &sval))
 295                         return;
 296                 snprintf(tmp, 25, "%s", sval_to_numstr(sval));
 297                 append(buf, tmp, len);
 298                 return;
 299         }
 300         case EXPR_FVALUE: {
 301                 sval_t sval = {};
 302                 char tmp[25];
 303
 304                 *complicated = 1;
 305                 if (!get_value(expr, &sval))
 306                         return;
 307                 snprintf(tmp, 25, "%s", sval_to_numstr(sval));
 308                 append(buf, tmp, len);
 309                 return;
 310         }
 311         case EXPR_STRING:
 312                 append(buf, "\"", len);
 313                 if (expr->string)
 314                         append(buf, expr->string->data, len);
 315                 append(buf, "\"", len);
 316                 return;
 317         case EXPR_CALL: {
 318                 struct expression *tmp;
 319                 int i;
 320
 321                 *complicated = 1;
 322                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated);
 323                 append(buf, "(", len);
 324                 i = 0;
 325                 FOR_EACH_PTR(expr->args, tmp) {
 326                         if (i++)
 327                                 append(buf, ", ", len);
 328                         __get_variable_from_expr(NULL, buf, tmp, len, complicated);
 329                 } END_FOR_EACH_PTR(tmp);
 330                 append(buf, ")", len);
 331                 return;
 332         }
 333         case EXPR_CAST:
 334         case EXPR_FORCE_CAST:
 335                 __get_variable_from_expr(sym_ptr, buf,
 336                                          expr->cast_expression, len,
 337                                          complicated);
 338                 return;
 339         case EXPR_SIZEOF: {
 340                 sval_t sval;
 341                 int size;
 342                 char tmp[25];
 343
 344                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 345                         size = type_bytes(get_base_type(expr->cast_type));
 346                         snprintf(tmp, 25, "%d", size);
 347                         append(buf, tmp, len);
 348                 } else if (get_value(expr, &sval)) {
 349                         snprintf(tmp, 25, "%s", sval_to_str(sval));
 350                         append(buf, tmp, len);
 351                 }
 352                 return;
 353         }
 354         case EXPR_IDENTIFIER:
 355                 *complicated = 1;
 356                 if (expr->expr_ident)
 357                         append(buf, expr->expr_ident->name, len);
 358                 return;
 359         case EXPR_SELECT:
 360         case EXPR_CONDITIONAL:
 361                 *complicated = 1;
 362                 append(buf, "(", len);
 363                 __get_variable_from_expr(NULL, buf, expr->conditional, len, complicated);
 364                 append(buf, ") ?", len);
 365                 if (expr->cond_true)
 366                         __get_variable_from_expr(NULL, buf, expr->cond_true, len, complicated);
 367                 append(buf, ":", len);
 368                 __get_variable_from_expr(NULL, buf, expr->cond_false, len, complicated);
 369                 return;
 370         default: {
 371                         char tmp[64];
 372
 373                         snprintf(tmp, sizeof(tmp), "$expr_%p(%d)", expr, expr->type);
 374                         append(buf, tmp, len);
 375                         *complicated = 1;
 376                 }
 377                 return;
 378         }
 379 }
 380
 381 struct expr_str_cache_results {
 382         struct expression *expr;
 383         char str[VAR_LEN];
 384         struct symbol *sym;
 385         int complicated;
 386 };
 387
 388 static void get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 389                                      struct expression *expr, int len,
 390                                      int *complicated)
 391 {
 392         static struct expr_str_cache_results cached[8];
 393         struct symbol *tmp_sym = NULL;
 394         static int idx;
 395         int i;
 396
 397         for (i = 0; i < ARRAY_SIZE(cached); i++) {
 398                 if (expr == cached[i].expr) {
 399                         strncpy(buf, cached[i].str, len);
 400                         if (sym_ptr)
 401                                 *sym_ptr = cached[i].sym;
 402                         *complicated = cached[i].complicated;
 403                         return;
 404                 }
 405         }
 406
 407         __get_variable_from_expr(&tmp_sym, buf, expr, len, complicated);
 408         if (sym_ptr)
 409                 *sym_ptr = tmp_sym;
 410
 411         if (expr->smatch_flags & Tmp)
 412                 return;
 413
 414         cached[idx].expr = expr;
 415         strncpy(cached[idx].str, buf, VAR_LEN);
 416         cached[idx].sym = tmp_sym;
 417         cached[idx].complicated = *complicated;
 418
 419         idx = (idx + 1) % ARRAY_SIZE(cached);
 420 }
 421
 422 /*
 423  * This is returns a stylized "c looking" representation of the
 424  * variable name.
 425  *
 426  * It uses the same buffer every time so you have to save the result
 427  * yourself if you want to keep it.
 428  *
 429  */
 430
 431 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 432 {
 433         static char var_name[VAR_LEN];
 434         int complicated = 0;
 435
 436         if (sym_ptr)
 437                 *sym_ptr = NULL;
 438         var_name[0] = '\0';
 439
 440         if (!expr)
 441                 return NULL;
 442         get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 443                                &complicated);
 444         if (complicated < 2)
 445                 return alloc_string(var_name);
 446         else
 447                 return NULL;
 448 }
 449
 450 char *expr_to_str(struct expression *expr)
 451 {
 452         return expr_to_str_sym(expr, NULL);
 453 }
 454
 455 /*
 456  * get_variable_from_expr_simple() only returns simple variables.
 457  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 458  * then it returns NULL.
 459  */
 460 char *expr_to_var_sym(struct expression *expr,
 461                                     struct symbol **sym_ptr)
 462 {
 463         static char var_name[VAR_LEN];
 464         int complicated = 0;
 465
 466         if (sym_ptr)
 467                 *sym_ptr = NULL;
 468         var_name[0] = '\0';
 469
 470         if (!expr)
 471                 return NULL;
 472         expr = strip_expr(expr);
 473         get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 474                                &complicated);
 475
 476         if (complicated) {
 477                 if (sym_ptr)
 478                         *sym_ptr = NULL;
 479                 return NULL;
 480         }
 481         return alloc_string(var_name);
 482 }
 483
 484 char *expr_to_var(struct expression *expr)
 485 {
 486         return expr_to_var_sym(expr, NULL);
 487 }
 488
 489 struct symbol *expr_to_sym(struct expression *expr)
 490 {
 491         struct symbol *sym;
 492         char *name;
 493
 494         name = expr_to_var_sym(expr, &sym);
 495         free_string(name);
 496         return sym;
 497 }
 498
 499 int get_complication_score(struct expression *expr)
 500 {
 501         expr = strip_expr(expr);
 502
 503         /*
 504          * Don't forget to keep get_complication_score() and store_all_links()
 505          * in sync.
 506          *
 507          */
 508
 509         if (!expr)
 510                 return 990;
 511
 512         switch (expr->type) {
 513         case EXPR_CALL:
 514                 return 991;
 515         case EXPR_COMPARE:
 516         case EXPR_BINOP:
 517                 return get_complication_score(expr->left) +
 518                        get_complication_score(expr->right);
 519         case EXPR_SYMBOL:
 520                 return 1;
 521         case EXPR_PREOP:
 522                 if (expr->op == '*' || expr->op == '(')
 523                         return get_complication_score(expr->unop);
 524                 return 993;
 525         case EXPR_DEREF:
 526                 return get_complication_score(expr->deref);
 527         case EXPR_VALUE:
 528         case EXPR_SIZEOF:
 529                 return 0;
 530         default:
 531                 return 994;
 532         }
 533 }
 534
 535 struct expression *reorder_expr_alphabetically(struct expression *expr)
 536 {
 537         struct expression *ret;
 538         char *left, *right;
 539
 540         if (expr->type != EXPR_BINOP)
 541                 return expr;
 542         if (expr->op != '+' && expr->op != '*')
 543                 return expr;
 544
 545         left = expr_to_var(expr->left);
 546         right = expr_to_var(expr->right);
 547         ret = expr;
 548         if (!left || !right)
 549                 goto free;
 550         if (strcmp(left, right) <= 0)
 551                 goto free;
 552
 553         ret = binop_expression(expr->right, expr->op, expr->left);
 554 free:
 555         free_string(left);
 556         free_string(right);
 557
 558         return ret;
 559 }
 560
 561 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 562 {
 563         struct var_sym_list *tmp_vsl;
 564         char *name;
 565         struct symbol *tmp;
 566         int score;
 567
 568         if (vsl)
 569                 *vsl = NULL;
 570         if (sym)
 571                 *sym = NULL;
 572
 573         expr = strip_parens(expr);
 574         if (!expr)
 575                 return NULL;
 576
 577         name = expr_to_var_sym(expr, &tmp);
 578         if (name && tmp) {
 579                 if (sym)
 580                         *sym = tmp;
 581                 if (vsl)
 582                         add_var_sym(vsl, name, tmp);
 583                 return name;
 584         }
 585         free_string(name);
 586
 587         score = get_complication_score(expr);
 588         if (score <= 0 || score > 2)
 589                 return NULL;
 590
 591         tmp_vsl = expr_to_vsl(expr);
 592         if (vsl) {
 593                 *vsl = tmp_vsl;
 594                 if (!*vsl)
 595                         return NULL;
 596         }
 597         if (sym) {
 598                 if (ptr_list_size((struct ptr_list *)tmp_vsl) == 1) {
 599                         struct var_sym *vs;
 600
 601                         vs = first_ptr_list((struct ptr_list *)tmp_vsl);
 602                         *sym = vs->sym;
 603                 }
 604         }
 605
 606         expr = reorder_expr_alphabetically(expr);
 607
 608         return expr_to_str(expr);
 609 }
 610
 611 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 612 {
 613         return expr_to_chunk_helper(expr, sym, NULL);
 614 }
 615
 616 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 617 {
 618         return expr_to_chunk_helper(expr, sym, vsl);
 619 }
 620
 621 int sym_name_is(const char *name, struct expression *expr)
 622 {
 623         if (!expr)
 624                 return 0;
 625         if (expr->type != EXPR_SYMBOL)
 626                 return 0;
 627         if (!strcmp(expr->symbol_name->name, name))
 628                 return 1;
 629         return 0;
 630 }
 631
 632 int expr_is_zero(struct expression *expr)
 633 {
 634         sval_t sval;
 635
 636         if (get_value(expr, &sval) && sval.value == 0)
 637                 return 1;
 638         return 0;
 639 }
 640
 641 int is_array(struct expression *expr)
 642 {
 643         struct symbol *type;
 644
 645         expr = strip_expr(expr);
 646         if (!expr)
 647                 return 0;
 648
 649         if (expr->type == EXPR_PREOP && expr->op == '*') {
 650                 expr = strip_expr(expr->unop);
 651                 if (!expr)
 652                         return 0;
 653                 if (expr->type == EXPR_BINOP && expr->op == '+')
 654                         return 1;
 655         }
 656
 657         if (expr->type != EXPR_BINOP || expr->op != '+')
 658                 return 0;
 659
 660         type = get_type(expr->left);
 661         if (!type || type->type != SYM_ARRAY)
 662                 return 0;
 663
 664         return 1;
 665 }
 666
 667 struct expression *get_array_base(struct expression *expr)
 668 {
 669         if (!is_array(expr))
 670                 return NULL;
 671         expr = strip_expr(expr);
 672         if (expr->type == EXPR_PREOP && expr->op == '*')
 673                 expr = strip_expr(expr->unop);
 674         if (expr->type != EXPR_BINOP || expr->op != '+')
 675                 return NULL;
 676         return strip_parens(expr->left);
 677 }
 678
 679 struct expression *get_array_offset(struct expression *expr)
 680 {
 681         if (!is_array(expr))
 682                 return NULL;
 683         expr = strip_expr(expr);
 684         if (expr->type == EXPR_PREOP && expr->op == '*')
 685                 expr = strip_expr(expr->unop);
 686         if (expr->type != EXPR_BINOP || expr->op != '+')
 687                 return NULL;
 688         return strip_parens(expr->right);
 689 }
 690
 691 const char *show_state(struct smatch_state *state)
 692 {
 693         if (!state)
 694                 return NULL;
 695         return state->name;
 696 }
 697
 698 struct statement *get_expression_statement(struct expression *expr)
 699 {
 700         /* What are those things called? if (({....; ret;})) { ...*/
 701
 702         if (expr->type != EXPR_PREOP)
 703                 return NULL;
 704         if (expr->op != '(')
 705                 return NULL;
 706         if (!expr->unop)
 707                 return NULL;
 708         if (expr->unop->type != EXPR_STATEMENT)
 709                 return NULL;
 710         if (expr->unop->statement->type != STMT_COMPOUND)
 711                 return NULL;
 712         return expr->unop->statement;
 713 }
 714
 715 struct expression *strip_parens(struct expression *expr)
 716 {
 717         if (!expr)
 718                 return NULL;
 719
 720         if (expr->type == EXPR_PREOP) {
 721                 if (!expr->unop)
 722                         return expr;  /* parsing invalid code */
 723
 724                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 725                         expr->unop->statement->type == STMT_COMPOUND)
 726                         return expr;
 727                 if (expr->op == '(')
 728                         return strip_parens(expr->unop);
 729         }
 730         return expr;
 731 }
 732
 733 static struct expression *strip_expr_helper(struct expression *expr, bool set_parent)
 734 {
 735         if (!expr)
 736                 return NULL;
 737
 738         switch (expr->type) {
 739         case EXPR_FORCE_CAST:
 740         case EXPR_CAST:
 741                 if (set_parent)
 742                         expr_set_parent_expr(expr->cast_expression, expr);
 743
 744                 if (!expr->cast_expression)
 745                         return expr;
 746                 return strip_expr_helper(expr->cast_expression, set_parent);
 747         case EXPR_PREOP: {
 748                 struct expression *unop;
 749
 750                 if (!expr->unop)  /* parsing invalid code */
 751                         return expr;
 752                 if (set_parent)
 753                         expr_set_parent_expr(expr->unop, expr);
 754
 755
 756                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 757                         expr->unop->statement->type == STMT_COMPOUND)
 758                         return expr;
 759
 760                 unop = strip_expr_helper(expr->unop, set_parent);
 761
 762                 if (expr->op == '*' && unop &&
 763                     unop->type == EXPR_PREOP && unop->op == '&') {
 764                         struct symbol *type = get_type(unop->unop);
 765
 766                         if (type && type->type == SYM_ARRAY)
 767                                 return expr;
 768                         return strip_expr_helper(unop->unop, set_parent);
 769                 }
 770
 771                 if (expr->op == '(')
 772                         return unop;
 773
 774                 return expr;
 775         }
 776         case EXPR_CONDITIONAL:
 777                 if (known_condition_true(expr->conditional)) {
 778                         if (expr->cond_true) {
 779                                 if (set_parent)
 780                                         expr_set_parent_expr(expr->cond_true, expr);
 781                                 return strip_expr_helper(expr->cond_true, set_parent);
 782                         }
 783                         if (set_parent)
 784                                 expr_set_parent_expr(expr->conditional, expr);
 785                         return strip_expr_helper(expr->conditional, set_parent);
 786                 }
 787                 if (known_condition_false(expr->conditional)) {
 788                         if (set_parent)
 789                                 expr_set_parent_expr(expr->cond_false, expr);
 790                         return strip_expr_helper(expr->cond_false, set_parent);
 791                 }
 792                 return expr;
 793         case EXPR_CALL:
 794                 if (sym_name_is("__builtin_expect", expr->fn) ||
 795                     sym_name_is("__builtin_bswap16", expr->fn) ||
 796                     sym_name_is("__builtin_bswap32", expr->fn) ||
 797                     sym_name_is("__builtin_bswap64", expr->fn)) {
 798                         expr = get_argument_from_call_expr(expr->args, 0);
 799                         return strip_expr_helper(expr, set_parent);
 800                 }
 801                 return expr;
 802         }
 803         return expr;
 804 }
 805
 806 struct expression *strip_expr(struct expression *expr)
 807 {
 808         return strip_expr_helper(expr, false);
 809 }
 810
 811 struct expression *strip_expr_set_parent(struct expression *expr)
 812 {
 813         return strip_expr_helper(expr, true);
 814 }
 815
 816 static void delete_state_tracker(struct tracker *t)
 817 {
 818         delete_state(t->owner, t->name, t->sym);
 819         __free_tracker(t);
 820 }
 821
 822 void scoped_state(int my_id, const char *name, struct symbol *sym)
 823 {
 824         struct tracker *t;
 825
 826         t = alloc_tracker(my_id, name, sym);
 827         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 828 }
 829
 830 int is_error_return(struct expression *expr)
 831 {
 832         struct symbol *cur_func = cur_func_sym;
 833         struct range_list *rl;
 834         sval_t sval;
 835
 836         if (!expr)
 837                 return 0;
 838         if (cur_func->type != SYM_NODE)
 839                 return 0;
 840         cur_func = get_base_type(cur_func);
 841         if (cur_func->type != SYM_FN)
 842                 return 0;
 843         cur_func = get_base_type(cur_func);
 844         if (cur_func == &void_ctype)
 845                 return 0;
 846         if (option_project == PROJ_KERNEL &&
 847             get_implied_rl(expr, &rl) &&
 848             rl_type(rl) == &int_ctype &&
 849             sval_is_negative(rl_min(rl)) &&
 850             rl_max(rl).value == -1)
 851                 return 1;
 852         if (!get_implied_value(expr, &sval))
 853                 return 0;
 854         if (sval.value < 0)
 855                 return 1;
 856         if (cur_func->type == SYM_PTR && sval.value == 0)
 857                 return 1;
 858         return 0;
 859 }
 860
 861 int getting_address(struct expression *expr)
 862 {
 863         int deref_count = 0;
 864
 865         while ((expr = expr_get_parent_expr(expr))) {
 866                 if (expr->type == EXPR_PREOP && expr->op == '*') {
 867                         /* &foo->bar->baz dereferences "foo->bar" */
 868                         if (deref_count == 0)
 869                                 deref_count++;
 870                         return false;
 871                 }
 872                 if (expr->type == EXPR_PREOP && expr->op == '&')
 873                         return true;
 874         }
 875         return false;
 876 }
 877
 878 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 879 {
 880         struct symbol *sym;
 881
 882         expr = strip_expr(expr);
 883         if (expr->type != EXPR_DEREF)
 884                 return 0;
 885         if (!expr->member)
 886                 return 0;
 887
 888         sym = get_type(expr->deref);
 889         if (!sym)
 890                 return 0;
 891         if (sym->type == SYM_UNION)
 892                 return 0;
 893         if (!sym->ident)
 894                 return 0;
 895
 896         *type = sym->ident->name;
 897         *member = expr->member->name;
 898         return 1;
 899 }
 900
 901 char *get_member_name(struct expression *expr)
 902 {
 903         char buf[256];
 904         struct symbol *sym;
 905
 906         expr = strip_expr(expr);
 907         if (!expr || expr->type != EXPR_DEREF)
 908                 return NULL;
 909         if (!expr->member)
 910                 return NULL;
 911
 912         sym = get_type(expr->deref);
 913         if (!sym)
 914                 return NULL;
 915         if (sym->type == SYM_UNION) {
 916                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 917                          sym->ident ? sym->ident->name : "anonymous",
 918                          expr->member->name);
 919                 return alloc_string(buf);
 920         }
 921         if (!sym->ident) {
 922                 struct expression *deref;
 923                 char *full, *outer;
 924                 int len;
 925
 926                 /*
 927                  * If we're in an anonymous struct then maybe we can find an
 928                  * outer struct name to use as a name.  This code should be
 929                  * recursive and cleaner.  I am not very proud of it.
 930                  *
 931                  */
 932
 933                 deref = expr->deref;
 934                 if (deref->type != EXPR_DEREF || !deref->member)
 935                         return NULL;
 936                 sym = get_type(deref->deref);
 937                 if (!sym || sym->type != SYM_STRUCT || !sym->ident)
 938                         return NULL;
 939
 940                 full = expr_to_str(expr);
 941                 if (!full)
 942                         return NULL;
 943                 deref = deref->deref;
 944                 if (deref->type == EXPR_PREOP && deref->op == '*')
 945                         deref = deref->unop;
 946                 outer = expr_to_str(deref);
 947                 if (!outer) {
 948                         free_string(full);
 949                         return NULL;
 950                 }
 951                 len = strlen(outer);
 952                 if (strncmp(outer, full, len) != 0) {
 953                         free_string(full);
 954                         free_string(outer);
 955                         return NULL;
 956                 }
 957                 if (full[len] == '-' && full[len + 1] == '>')
 958                         len += 2;
 959                 if (full[len] == '.')
 960                         len++;
 961                 snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, full + len);
 962                 free_string(outer);
 963                 free_string(full);
 964
 965                 return alloc_string(buf);
 966         }
 967         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 968         return alloc_string(buf);
 969 }
 970
 971 int cmp_pos(struct position pos1, struct position pos2)
 972 {
 973         /* the stream position is ... */
 974         if (pos1.stream > pos2.stream)
 975                 return -1;
 976         if (pos1.stream < pos2.stream)
 977                 return 1;
 978
 979         if (pos1.line < pos2.line)
 980                 return -1;
 981         if (pos1.line > pos2.line)
 982                 return 1;
 983
 984         if (pos1.pos < pos2.pos)
 985                 return -1;
 986         if (pos1.pos > pos2.pos)
 987                 return 1;
 988
 989         return 0;
 990 }
 991
 992 int positions_eq(struct position pos1, struct position pos2)
 993 {
 994         if (pos1.line != pos2.line)
 995                 return 0;
 996         if (pos1.pos != pos2.pos)
 997                 return 0;
 998         if (pos1.stream != pos2.stream)
 999                 return 0;
1000         return 1;
1001 }
1002
1003 struct statement *get_current_statement(void)
1004 {
1005         struct statement *prev, *tmp;
1006
1007         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
1008
1009         if (!prev || !get_macro_name(prev->pos))
1010                 return prev;
1011
1012         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
1013                 if (positions_eq(tmp->pos, prev->pos))
1014                         continue;
1015                 if (prev->pos.line > tmp->pos.line)
1016                         return prev;
1017                 return tmp;
1018         } END_FOR_EACH_PTR_REVERSE(tmp);
1019         return prev;
1020 }
1021
1022 struct statement *get_prev_statement(void)
1023 {
1024         struct statement *tmp;
1025         int i;
1026
1027         i = 0;
1028         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
1029                 if (i++ == 1)
1030                         return tmp;
1031         } END_FOR_EACH_PTR_REVERSE(tmp);
1032         return NULL;
1033 }
1034
1035 struct expression *get_last_expr_from_expression_stmt(struct expression *expr)
1036 {
1037         struct statement *stmt;
1038         struct statement *last_stmt;
1039
1040         while (expr->type == EXPR_PREOP && expr->op == '(')
1041                 expr = expr->unop;
1042         if (expr->type != EXPR_STATEMENT)
1043                 return NULL;
1044         stmt = expr->statement;
1045         if (!stmt)
1046                 return NULL;
1047         if (stmt->type == STMT_COMPOUND) {
1048                 last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
1049                 if (!last_stmt)
1050                         return NULL;
1051                 if (last_stmt->type == STMT_LABEL)
1052                         last_stmt = last_stmt->label_statement;
1053                 if (last_stmt->type != STMT_EXPRESSION)
1054                         return NULL;
1055                 return last_stmt->expression;
1056         }
1057         if (stmt->type == STMT_EXPRESSION)
1058                 return stmt->expression;
1059         return NULL;
1060 }
1061
1062 int get_param_num_from_sym(struct symbol *sym)
1063 {
1064         struct symbol *tmp;
1065         int i;
1066
1067         if (!sym)
1068                 return UNKNOWN_SCOPE;
1069
1070         if (sym->ctype.modifiers & MOD_TOPLEVEL) {
1071                 if (sym->ctype.modifiers & MOD_STATIC)
1072                         return FILE_SCOPE;
1073                 return GLOBAL_SCOPE;
1074         }
1075
1076         if (!cur_func_sym) {
1077                 if (!parse_error) {
1078                         sm_msg("warn: internal.  problem with scope:  %s",
1079                                sym->ident ? sym->ident->name : "<anon var>");
1080                 }
1081                 return GLOBAL_SCOPE;
1082         }
1083
1084
1085         i = 0;
1086         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
1087                 if (tmp == sym)
1088                         return i;
1089                 i++;
1090         } END_FOR_EACH_PTR(tmp);
1091         return LOCAL_SCOPE;
1092 }
1093
1094 int get_param_num(struct expression *expr)
1095 {
1096         struct symbol *sym;
1097         char *name;
1098
1099         if (!cur_func_sym)
1100                 return UNKNOWN_SCOPE;
1101         name = expr_to_var_sym(expr, &sym);
1102         free_string(name);
1103         if (!sym)
1104                 return UNKNOWN_SCOPE;
1105         return get_param_num_from_sym(sym);
1106 }
1107
1108 struct symbol *get_param_sym_from_num(int num)
1109 {
1110         struct symbol *sym;
1111         int i;
1112
1113         if (!cur_func_sym)
1114                 return NULL;
1115
1116         i = 0;
1117         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, sym) {
1118                 if (i++ == num)
1119                         return sym;
1120         } END_FOR_EACH_PTR(sym);
1121         return NULL;
1122 }
1123
1124 int ms_since(struct timeval *start)
1125 {
1126         struct timeval end;
1127         double diff;
1128
1129         gettimeofday(&end, NULL);
1130         diff = (end.tv_sec - start->tv_sec) * 1000.0;
1131         diff += (end.tv_usec - start->tv_usec) / 1000.0;
1132         return (int)diff;
1133 }
1134
1135 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
1136 {
1137         if (!name || !sym)
1138                 return 0;
1139
1140         if (parent_is_null_var_sym(name, sym) ||
1141             parent_is_free_var_sym(name, sym))
1142                 return 1;
1143         return 0;
1144 }
1145
1146 int parent_is_gone(struct expression *expr)
1147 {
1148         struct symbol *sym;
1149         char *var;
1150         int ret = 0;
1151
1152         expr = strip_expr(expr);
1153         var = expr_to_var_sym(expr, &sym);
1154         if (!var || !sym)
1155                 goto free;
1156         ret = parent_is_gone_var_sym(var, sym);
1157 free:
1158         free_string(var);
1159         return ret;
1160 }
1161
1162 int invert_op(int op)
1163 {
1164         switch (op) {
1165         case '*':
1166                 return '/';
1167         case '/':
1168                 return '*';
1169         case '+':
1170                 return '-';
1171         case '-':
1172                 return '+';
1173         case SPECIAL_LEFTSHIFT:
1174                 return SPECIAL_RIGHTSHIFT;
1175         case SPECIAL_RIGHTSHIFT:
1176                 return SPECIAL_LEFTSHIFT;
1177         }
1178         return 0;
1179 }
1180
1181 int op_remove_assign(int op)
1182 {
1183         switch (op) {
1184         case SPECIAL_ADD_ASSIGN:
1185                 return '+';
1186         case SPECIAL_SUB_ASSIGN:
1187                 return '-';
1188         case SPECIAL_MUL_ASSIGN:
1189                 return '*';
1190         case SPECIAL_DIV_ASSIGN:
1191                 return '/';
1192         case SPECIAL_MOD_ASSIGN:
1193                 return '%';
1194         case SPECIAL_AND_ASSIGN:
1195                 return '&';
1196         case SPECIAL_OR_ASSIGN:
1197                 return '|';
1198         case SPECIAL_XOR_ASSIGN:
1199                 return '^';
1200         case SPECIAL_SHL_ASSIGN:
1201                 return SPECIAL_LEFTSHIFT;
1202         case SPECIAL_SHR_ASSIGN:
1203                 return SPECIAL_RIGHTSHIFT;
1204         default:
1205                 return op;
1206         }
1207 }
1208
1209 int expr_equiv(struct expression *one, struct expression *two)
1210 {
1211         struct symbol *one_sym = NULL;
1212         struct symbol *two_sym = NULL;
1213         char *one_name = NULL;
1214         char *two_name = NULL;
1215         int ret = 0;
1216
1217         if (!one || !two)
1218                 return 0;
1219         if (one->type != two->type)
1220                 return 0;
1221         if (is_fake_call(one) || is_fake_call(two))
1222                 return 0;
1223
1224         one_name = expr_to_str_sym(one, &one_sym);
1225         if (!one_name)
1226                 goto free;
1227         two_name = expr_to_str_sym(two, &two_sym);
1228         if (!two_name)
1229                 goto free;
1230         if (one_sym != two_sym)
1231                 goto free;
1232         /*
1233          * This is a terrible hack because expr_to_str() sometimes gives up in
1234          * the middle and just returns what it has.  If you see a () you know
1235          * the string is bogus.
1236          */
1237         if (strstr(one_name, "()"))
1238                 goto free;
1239         if (strcmp(one_name, two_name) == 0)
1240                 ret = 1;
1241 free:
1242         free_string(one_name);
1243         free_string(two_name);
1244         return ret;
1245 }
1246
1247 void push_int(struct int_stack **stack, int num)
1248 {
1249         int *munged;
1250
1251         /*
1252          * Just put the int on directly instead of a pointer to the int.
1253          * Shift it to the left because Sparse uses the last two bits.
1254          * This is sort of a dirty hack, yes.
1255          */
1256
1257         munged = INT_PTR(num << 2);
1258
1259         add_ptr_list(stack, munged);
1260 }
1261
1262 int pop_int(struct int_stack **stack)
1263 {
1264         int *num;
1265
1266         num = last_ptr_list((struct ptr_list *)*stack);
1267         delete_ptr_list_last((struct ptr_list **)stack);
1268
1269         return PTR_INT(num) >> 2;
1270 }