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 static int FORMAT_ATTR(4) append(char *dest, int off, int len, const char *fmt, ...)
 124 {
 125         int n;
 126         va_list args;
 127
 128         if (len <= 0 || off < 0 || off >= len - 1)
 129                 return 0;
 130
 131         va_start(args, fmt);
 132         n = vsnprintf(dest + off, len - off, fmt, args);
 133         va_end(args);
 134
 135         if (n > len - off - 1)
 136                 return len - off - 1;
 137         return n;
 138 }
 139
 140 /*
 141  * If you have "foo(a, b, 1);" then use
 142  * get_argument_from_call_expr(expr, 0) to return the expression for
 143  * a.  Yes, it does start counting from 0.
 144  */
 145 struct expression *get_argument_from_call_expr(struct expression_list *args,
 146                                                int num)
 147 {
 148         struct expression *expr;
 149         int i = 0;
 150
 151         if (!args)
 152                 return NULL;
 153
 154         FOR_EACH_PTR(args, expr) {
 155                 if (i == num)
 156                         return expr;
 157                 i++;
 158         } END_FOR_EACH_PTR(expr);
 159         return NULL;
 160 }
 161
 162 struct expression *get_array_expr(struct expression *expr)
 163 {
 164         struct expression *parent;
 165         struct symbol *type;
 166
 167         if (expr->type != EXPR_BINOP || expr->op != '+')
 168                 return NULL;
 169
 170         type = get_type(expr->left);
 171         if (!type)
 172                 return NULL;
 173         if (type->type == SYM_ARRAY)
 174                 return expr->left;
 175         if (type->type != SYM_PTR)
 176                 return NULL;
 177
 178         parent = expr_get_parent_expr(expr);
 179         if (!parent)  /* Sometimes we haven't set up the ->parent yet. FIXME!! */
 180                 return expr->left;
 181         if (parent->type == EXPR_PREOP && parent->op == '*')
 182                 return expr->left;
 183
 184         return NULL;
 185 }
 186
 187 static struct expression *strip_star_address(struct expression *expr)
 188 {
 189         struct expression *unop;
 190
 191         if (expr->type != EXPR_PREOP || expr->op != '*')
 192                 return expr;
 193         unop = strip_parens(expr->unop);
 194         if (unop->type != EXPR_PREOP || unop->op != '&')
 195                 return expr;
 196
 197         return unop->unop;
 198 }
 199
 200 static struct expression *strip_parens_symbol(struct expression *expr)
 201 {
 202         struct expression *unop;
 203
 204         if (expr->type != EXPR_PREOP || expr->op != '(')
 205                 return expr;
 206         unop = strip_parens(expr->unop);
 207         if (unop->type != EXPR_SYMBOL)
 208                 return expr;
 209         return unop;
 210 }
 211
 212 static int __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 213                                      struct expression *expr, int off, int len,
 214                                      int *complicated)
 215 {
 216         int orig_off = off;
 217
 218         if (!expr) {
 219                 /* can't happen on valid code */
 220                 *complicated = 1;
 221                 return 0;
 222         }
 223
 224         expr = strip_star_address(expr);
 225         expr = strip_parens_symbol(expr);
 226
 227         switch (expr->type) {
 228         case EXPR_DEREF: {
 229                 struct expression *deref;
 230                 int op;
 231
 232                 op = expr->op;
 233                 deref = expr->deref;
 234
 235                 /* this is pure guess work and nonsense programming */
 236                 if (deref->type == EXPR_PREOP && deref->op == '*') {
 237                         op = '*';
 238                         deref = deref->unop;
 239                 }
 240
 241                 off += __get_variable_from_expr(sym_ptr, buf, deref, off, len, complicated);
 242
 243                 if (op == '*')
 244                         off += append(buf, off, len, "->");
 245                 else
 246                         off += append(buf, off, len, ".");
 247
 248                 if (expr->member)
 249                         off += append(buf, off, len, "%s", expr->member->name);
 250                 else
 251                         off += append(buf, off, len, "unknown_member");
 252                 return off - orig_off;
 253         }
 254         case EXPR_SYMBOL:
 255                 if (expr->symbol_name)
 256                         off += append(buf, off, len, "%s", expr->symbol_name->name);
 257                 if (sym_ptr) {
 258                         if (*sym_ptr)
 259                                 *complicated = 1;
 260                         *sym_ptr = expr->symbol;
 261                 }
 262                 return off - orig_off;
 263         case EXPR_PREOP: {
 264                 const char *tmp;
 265
 266                 if (get_expression_statement(expr)) {
 267                         *complicated = 2;
 268                         return 0;
 269                 }
 270                 if (expr->op == SPECIAL_DECREMENT ||
 271                     expr->op == SPECIAL_INCREMENT)
 272                         *complicated = 1;
 273
 274                 if (expr->op == '*' && get_array_expr(expr->unop))
 275                         tmp = "";
 276                 else
 277                         tmp = show_special(expr->op);
 278
 279                 off += append(buf, off, len, "%s", tmp);
 280                 off += __get_variable_from_expr(sym_ptr, buf, expr->unop, off,
 281                                                 len, complicated);
 282                 if (expr->op == '(')
 283                         off += append(buf, off, len, ")");
 284
 285                 return off - orig_off;
 286         }
 287         case EXPR_POSTOP: {
 288                 off += __get_variable_from_expr(sym_ptr, buf, expr->unop, off, len,
 289                                                 complicated);
 290                 off += append(buf, off, len, "%s", show_special(expr->op));
 291
 292                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 293                         *complicated = 1;
 294                 return off - orig_off;
 295         }
 296         case EXPR_ASSIGNMENT:
 297         case EXPR_COMPARE:
 298         case EXPR_LOGICAL:
 299         case EXPR_BINOP: {
 300                 struct expression *array_expr;
 301
 302                 *complicated = 1;
 303                 array_expr = get_array_expr(expr);
 304                 if (array_expr) {
 305                         off += __get_variable_from_expr(sym_ptr, buf, array_expr, off, len, complicated);
 306                         off += append(buf, off, len, "[");
 307                 } else {
 308                         off += __get_variable_from_expr(sym_ptr, buf, expr->left, off, len, complicated);
 309                         off += append(buf, off, len, " %s ", show_special(expr->op));
 310                 }
 311                 off += __get_variable_from_expr(NULL, buf, expr->right, off, len, complicated);
 312                 if (array_expr)
 313                         off += append(buf, off, len, "]");
 314                 return off - orig_off;
 315         }
 316         case EXPR_VALUE: {
 317                 sval_t sval = {};
 318
 319                 *complicated = 1;
 320                 if (!get_value(expr, &sval))
 321                         return 0;
 322                 off += append(buf, off, len, "%s", sval_to_numstr(sval));
 323                 return off - orig_off;
 324         }
 325         case EXPR_FVALUE: {
 326                 sval_t sval = {};
 327
 328                 *complicated = 1;
 329                 if (!get_value(expr, &sval))
 330                         return 0;
 331
 332                 off += append(buf, off, len, "%s", sval_to_numstr(sval));
 333                 return off - orig_off;
 334         }
 335         case EXPR_STRING:
 336                 off += append(buf, off, len, "\"");
 337                 if (expr->string)
 338                         off += append(buf, off, len, "%s", expr->string->data);
 339                 off += append(buf, off, len, "\"");
 340                 return off - orig_off;
 341         case EXPR_CALL: {
 342                 struct expression *tmp;
 343                 int i;
 344
 345                 *complicated = 1;
 346                 off += __get_variable_from_expr(NULL, buf, expr->fn, off, len, complicated);
 347                 off += append(buf, off, len, "(");
 348                 i = 0;
 349                 FOR_EACH_PTR(expr->args, tmp) {
 350                         if (i++)
 351                                 off += append(buf, off, len, ", ");
 352                         off += __get_variable_from_expr(NULL, buf, tmp, off, len, complicated);
 353                 } END_FOR_EACH_PTR(tmp);
 354                 off += append(buf, off, len, ")");
 355                 return off - orig_off;
 356         }
 357         case EXPR_CAST:
 358         case EXPR_FORCE_CAST:
 359                 return __get_variable_from_expr(sym_ptr, buf,
 360                                                 expr->cast_expression, off, len,
 361                                                 complicated);
 362         case EXPR_SIZEOF: {
 363                 sval_t sval;
 364                 int size;
 365
 366                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 367                         size = type_bytes(get_base_type(expr->cast_type));
 368                         off += append(buf, off, len, "%d", size);
 369                 } else if (get_value(expr, &sval)) {
 370                         off += append(buf, off, len, "%s", sval_to_str(sval));
 371                 }
 372                 return off - orig_off;
 373         }
 374         case EXPR_IDENTIFIER:
 375                 *complicated = 1;
 376                 if (expr->expr_ident)
 377                         off += append(buf, off, len, "%s", expr->expr_ident->name);
 378                 return off - orig_off;
 379         case EXPR_SELECT:
 380         case EXPR_CONDITIONAL:
 381                 *complicated = 1;
 382                 off += append(buf, off, len, "(");
 383                 off += __get_variable_from_expr(NULL, buf, expr->conditional, off, len, complicated);
 384                 off += append(buf, off, len, ") ?");
 385                 if (expr->cond_true)
 386                         off += __get_variable_from_expr(NULL, buf, expr->cond_true, off, len, complicated);
 387                 off += append(buf, off, len, ":");
 388                 off += __get_variable_from_expr(NULL, buf, expr->cond_false, off, len, complicated);
 389                 return off - orig_off;
 390         default:
 391                 off += append(buf, off, len, "$expr_%p(%d)", expr, expr->type);
 392                 return off - orig_off;
 393         }
 394 }
 395
 396 struct expr_str_cache_results {
 397         struct expression *expr;
 398         char str[VAR_LEN];
 399         struct symbol *sym;
 400         int complicated;
 401 };
 402
 403 static void get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 404                                      struct expression *expr, int len,
 405                                      int *complicated)
 406 {
 407         static struct expr_str_cache_results cached[8];
 408         struct symbol *tmp_sym = NULL;
 409         static int idx;
 410         int i;
 411
 412         for (i = 0; i < ARRAY_SIZE(cached); i++) {
 413                 if (expr == cached[i].expr) {
 414                         strncpy(buf, cached[i].str, len);
 415                         if (sym_ptr)
 416                                 *sym_ptr = cached[i].sym;
 417                         *complicated = cached[i].complicated;
 418                         return;
 419                 }
 420         }
 421
 422         __get_variable_from_expr(&tmp_sym, buf, expr, 0, len, complicated);
 423         if (sym_ptr)
 424                 *sym_ptr = tmp_sym;
 425
 426         if (expr->smatch_flags & Tmp)
 427                 return;
 428
 429         cached[idx].expr = expr;
 430         strncpy(cached[idx].str, buf, VAR_LEN);
 431         cached[idx].sym = tmp_sym;
 432         cached[idx].complicated = *complicated;
 433
 434         idx = (idx + 1) % ARRAY_SIZE(cached);
 435 }
 436
 437 /*
 438  * This is returns a stylized "c looking" representation of the
 439  * variable name.
 440  *
 441  * It uses the same buffer every time so you have to save the result
 442  * yourself if you want to keep it.
 443  *
 444  */
 445
 446 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 447 {
 448         static char var_name[VAR_LEN];
 449         int complicated = 0;
 450
 451         if (sym_ptr)
 452                 *sym_ptr = NULL;
 453         var_name[0] = '\0';
 454
 455         if (!expr)
 456                 return NULL;
 457         get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 458                                &complicated);
 459         if (complicated < 2)
 460                 return alloc_string(var_name);
 461         else
 462                 return NULL;
 463 }
 464
 465 char *expr_to_str(struct expression *expr)
 466 {
 467         return expr_to_str_sym(expr, NULL);
 468 }
 469
 470 /*
 471  * get_variable_from_expr_simple() only returns simple variables.
 472  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 473  * then it returns NULL.
 474  */
 475 char *expr_to_var_sym(struct expression *expr,
 476                                     struct symbol **sym_ptr)
 477 {
 478         static char var_name[VAR_LEN];
 479         int complicated = 0;
 480
 481         if (sym_ptr)
 482                 *sym_ptr = NULL;
 483         var_name[0] = '\0';
 484
 485         if (!expr)
 486                 return NULL;
 487         expr = strip_expr(expr);
 488         get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 489                                &complicated);
 490
 491         if (complicated) {
 492                 if (sym_ptr)
 493                         *sym_ptr = NULL;
 494                 return NULL;
 495         }
 496         return alloc_string(var_name);
 497 }
 498
 499 char *expr_to_var(struct expression *expr)
 500 {
 501         return expr_to_var_sym(expr, NULL);
 502 }
 503
 504 struct symbol *expr_to_sym(struct expression *expr)
 505 {
 506         struct symbol *sym;
 507         char *name;
 508
 509         name = expr_to_var_sym(expr, &sym);
 510         free_string(name);
 511         return sym;
 512 }
 513
 514 int get_complication_score(struct expression *expr)
 515 {
 516         expr = strip_expr(expr);
 517
 518         /*
 519          * Don't forget to keep get_complication_score() and store_all_links()
 520          * in sync.
 521          *
 522          */
 523
 524         if (!expr)
 525                 return 990;
 526
 527         switch (expr->type) {
 528         case EXPR_CALL:
 529                 return 991;
 530         case EXPR_COMPARE:
 531         case EXPR_BINOP:
 532                 return get_complication_score(expr->left) +
 533                        get_complication_score(expr->right);
 534         case EXPR_SYMBOL:
 535                 return 1;
 536         case EXPR_PREOP:
 537                 if (expr->op == '*' || expr->op == '(')
 538                         return get_complication_score(expr->unop);
 539                 return 993;
 540         case EXPR_DEREF:
 541                 return get_complication_score(expr->deref);
 542         case EXPR_VALUE:
 543         case EXPR_SIZEOF:
 544                 return 0;
 545         default:
 546                 return 994;
 547         }
 548 }
 549
 550 struct expression *reorder_expr_alphabetically(struct expression *expr)
 551 {
 552         struct expression *ret;
 553         char *left, *right;
 554
 555         if (expr->type != EXPR_BINOP)
 556                 return expr;
 557         if (expr->op != '+' && expr->op != '*')
 558                 return expr;
 559
 560         left = expr_to_var(expr->left);
 561         right = expr_to_var(expr->right);
 562         ret = expr;
 563         if (!left || !right)
 564                 goto free;
 565         if (strcmp(left, right) <= 0)
 566                 goto free;
 567
 568         ret = binop_expression(expr->right, expr->op, expr->left);
 569 free:
 570         free_string(left);
 571         free_string(right);
 572
 573         return ret;
 574 }
 575
 576 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 577 {
 578         struct var_sym_list *tmp_vsl;
 579         char *name;
 580         struct symbol *tmp;
 581         int score;
 582
 583         if (vsl)
 584                 *vsl = NULL;
 585         if (sym)
 586                 *sym = NULL;
 587
 588         expr = strip_parens(expr);
 589         if (!expr)
 590                 return NULL;
 591
 592         name = expr_to_var_sym(expr, &tmp);
 593         if (name && tmp) {
 594                 if (sym)
 595                         *sym = tmp;
 596                 if (vsl)
 597                         add_var_sym(vsl, name, tmp);
 598                 return name;
 599         }
 600         free_string(name);
 601
 602         score = get_complication_score(expr);
 603         if (score <= 0 || score > 2)
 604                 return NULL;
 605
 606         tmp_vsl = expr_to_vsl(expr);
 607         if (vsl) {
 608                 *vsl = tmp_vsl;
 609                 if (!*vsl)
 610                         return NULL;
 611         }
 612         if (sym) {
 613                 if (ptr_list_size((struct ptr_list *)tmp_vsl) == 1) {
 614                         struct var_sym *vs;
 615
 616                         vs = first_ptr_list((struct ptr_list *)tmp_vsl);
 617                         *sym = vs->sym;
 618                 }
 619         }
 620
 621         expr = reorder_expr_alphabetically(expr);
 622
 623         return expr_to_str(expr);
 624 }
 625
 626 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 627 {
 628         return expr_to_chunk_helper(expr, sym, NULL);
 629 }
 630
 631 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 632 {
 633         return expr_to_chunk_helper(expr, sym, vsl);
 634 }
 635
 636 int sym_name_is(const char *name, struct expression *expr)
 637 {
 638         if (!expr)
 639                 return 0;
 640         if (expr->type != EXPR_SYMBOL)
 641                 return 0;
 642         if (!strcmp(expr->symbol_name->name, name))
 643                 return 1;
 644         return 0;
 645 }
 646
 647 int expr_is_zero(struct expression *expr)
 648 {
 649         sval_t sval;
 650
 651         if (get_value(expr, &sval) && sval.value == 0)
 652                 return 1;
 653         return 0;
 654 }
 655
 656 int is_array(struct expression *expr)
 657 {
 658         struct symbol *type;
 659
 660         expr = strip_expr(expr);
 661         if (!expr)
 662                 return 0;
 663
 664         if (expr->type == EXPR_PREOP && expr->op == '*') {
 665                 expr = strip_expr(expr->unop);
 666                 if (!expr)
 667                         return 0;
 668                 if (expr->type == EXPR_BINOP && expr->op == '+')
 669                         return 1;
 670         }
 671
 672         if (expr->type != EXPR_BINOP || expr->op != '+')
 673                 return 0;
 674
 675         type = get_type(expr->left);
 676         if (!type || type->type != SYM_ARRAY)
 677                 return 0;
 678
 679         return 1;
 680 }
 681
 682 struct expression *get_array_base(struct expression *expr)
 683 {
 684         if (!is_array(expr))
 685                 return NULL;
 686         expr = strip_expr(expr);
 687         if (expr->type == EXPR_PREOP && expr->op == '*')
 688                 expr = strip_expr(expr->unop);
 689         if (expr->type != EXPR_BINOP || expr->op != '+')
 690                 return NULL;
 691         return strip_parens(expr->left);
 692 }
 693
 694 struct expression *get_array_offset(struct expression *expr)
 695 {
 696         if (!is_array(expr))
 697                 return NULL;
 698         expr = strip_expr(expr);
 699         if (expr->type == EXPR_PREOP && expr->op == '*')
 700                 expr = strip_expr(expr->unop);
 701         if (expr->type != EXPR_BINOP || expr->op != '+')
 702                 return NULL;
 703         return strip_parens(expr->right);
 704 }
 705
 706 const char *show_state(struct smatch_state *state)
 707 {
 708         if (!state)
 709                 return NULL;
 710         return state->name;
 711 }
 712
 713 struct statement *get_expression_statement(struct expression *expr)
 714 {
 715         /* What are those things called? if (({....; ret;})) { ...*/
 716
 717         if (expr->type != EXPR_PREOP)
 718                 return NULL;
 719         if (expr->op != '(')
 720                 return NULL;
 721         if (!expr->unop)
 722                 return NULL;
 723         if (expr->unop->type != EXPR_STATEMENT)
 724                 return NULL;
 725         if (expr->unop->statement->type != STMT_COMPOUND)
 726                 return NULL;
 727         return expr->unop->statement;
 728 }
 729
 730 struct expression *strip_parens(struct expression *expr)
 731 {
 732         if (!expr)
 733                 return NULL;
 734
 735         if (expr->type == EXPR_PREOP) {
 736                 if (!expr->unop)
 737                         return expr;  /* parsing invalid code */
 738
 739                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 740                         expr->unop->statement->type == STMT_COMPOUND)
 741                         return expr;
 742                 if (expr->op == '(')
 743                         return strip_parens(expr->unop);
 744         }
 745         return expr;
 746 }
 747
 748 static struct expression *strip_expr_helper(struct expression *expr, bool set_parent)
 749 {
 750         if (!expr)
 751                 return NULL;
 752
 753         switch (expr->type) {
 754         case EXPR_FORCE_CAST:
 755         case EXPR_CAST:
 756                 if (set_parent)
 757                         expr_set_parent_expr(expr->cast_expression, expr);
 758
 759                 if (!expr->cast_expression)
 760                         return expr;
 761                 return strip_expr_helper(expr->cast_expression, set_parent);
 762         case EXPR_PREOP: {
 763                 struct expression *unop;
 764
 765                 if (!expr->unop)  /* parsing invalid code */
 766                         return expr;
 767                 if (set_parent)
 768                         expr_set_parent_expr(expr->unop, expr);
 769
 770
 771                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 772                         expr->unop->statement->type == STMT_COMPOUND)
 773                         return expr;
 774
 775                 unop = strip_expr_helper(expr->unop, set_parent);
 776
 777                 if (expr->op == '*' && unop &&
 778                     unop->type == EXPR_PREOP && unop->op == '&') {
 779                         struct symbol *type = get_type(unop->unop);
 780
 781                         if (type && type->type == SYM_ARRAY)
 782                                 return expr;
 783                         return strip_expr_helper(unop->unop, set_parent);
 784                 }
 785
 786                 if (expr->op == '(')
 787                         return unop;
 788
 789                 return expr;
 790         }
 791         case EXPR_CONDITIONAL:
 792                 if (known_condition_true(expr->conditional)) {
 793                         if (expr->cond_true) {
 794                                 if (set_parent)
 795                                         expr_set_parent_expr(expr->cond_true, expr);
 796                                 return strip_expr_helper(expr->cond_true, set_parent);
 797                         }
 798                         if (set_parent)
 799                                 expr_set_parent_expr(expr->conditional, expr);
 800                         return strip_expr_helper(expr->conditional, set_parent);
 801                 }
 802                 if (known_condition_false(expr->conditional)) {
 803                         if (set_parent)
 804                                 expr_set_parent_expr(expr->cond_false, expr);
 805                         return strip_expr_helper(expr->cond_false, set_parent);
 806                 }
 807                 return expr;
 808         case EXPR_CALL:
 809                 if (sym_name_is("__builtin_expect", expr->fn) ||
 810                     sym_name_is("__builtin_bswap16", expr->fn) ||
 811                     sym_name_is("__builtin_bswap32", expr->fn) ||
 812                     sym_name_is("__builtin_bswap64", expr->fn)) {
 813                         expr = get_argument_from_call_expr(expr->args, 0);
 814                         return strip_expr_helper(expr, set_parent);
 815                 }
 816                 return expr;
 817         }
 818         return expr;
 819 }
 820
 821 struct expression *strip_expr(struct expression *expr)
 822 {
 823         return strip_expr_helper(expr, false);
 824 }
 825
 826 struct expression *strip_expr_set_parent(struct expression *expr)
 827 {
 828         return strip_expr_helper(expr, true);
 829 }
 830
 831 static void delete_state_tracker(struct tracker *t)
 832 {
 833         __delete_state(t->owner, t->name, t->sym);
 834         __free_tracker(t);
 835 }
 836
 837 void scoped_state(int my_id, const char *name, struct symbol *sym)
 838 {
 839         struct tracker *t;
 840
 841         t = alloc_tracker(my_id, name, sym);
 842         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 843 }
 844
 845 int is_error_return(struct expression *expr)
 846 {
 847         struct symbol *cur_func = cur_func_sym;
 848         struct range_list *rl;
 849         sval_t sval;
 850
 851         if (!expr)
 852                 return 0;
 853         if (cur_func->type != SYM_NODE)
 854                 return 0;
 855         cur_func = get_base_type(cur_func);
 856         if (cur_func->type != SYM_FN)
 857                 return 0;
 858         cur_func = get_base_type(cur_func);
 859         if (cur_func == &void_ctype)
 860                 return 0;
 861         if (option_project == PROJ_KERNEL &&
 862             get_implied_rl(expr, &rl) &&
 863             rl_type(rl) == &int_ctype &&
 864             sval_is_negative(rl_min(rl)) &&
 865             rl_max(rl).value == -1)
 866                 return 1;
 867         if (!get_implied_value(expr, &sval))
 868                 return 0;
 869         if (sval.value < 0)
 870                 return 1;
 871         if (cur_func->type == SYM_PTR && sval.value == 0)
 872                 return 1;
 873         return 0;
 874 }
 875
 876 int getting_address(struct expression *expr)
 877 {
 878         int deref_count = 0;
 879
 880         while ((expr = expr_get_parent_expr(expr))) {
 881                 if (expr->type == EXPR_PREOP && expr->op == '*') {
 882                         /* &foo->bar->baz dereferences "foo->bar" */
 883                         if (deref_count == 0)
 884                                 deref_count++;
 885                         return false;
 886                 }
 887                 if (expr->type == EXPR_PREOP && expr->op == '&')
 888                         return true;
 889         }
 890         return false;
 891 }
 892
 893 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 894 {
 895         struct symbol *sym;
 896
 897         expr = strip_expr(expr);
 898         if (expr->type != EXPR_DEREF)
 899                 return 0;
 900         if (!expr->member)
 901                 return 0;
 902
 903         sym = get_type(expr->deref);
 904         if (!sym)
 905                 return 0;
 906         if (sym->type == SYM_UNION)
 907                 return 0;
 908         if (!sym->ident)
 909                 return 0;
 910
 911         *type = sym->ident->name;
 912         *member = expr->member->name;
 913         return 1;
 914 }
 915
 916 char *get_member_name(struct expression *expr)
 917 {
 918         char buf[256];
 919         struct symbol *sym;
 920
 921         expr = strip_expr(expr);
 922         if (!expr || expr->type != EXPR_DEREF)
 923                 return NULL;
 924         if (!expr->member)
 925                 return NULL;
 926
 927         sym = get_type(expr->deref);
 928         if (!sym)
 929                 return NULL;
 930         if (sym->type == SYM_UNION) {
 931                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 932                          sym->ident ? sym->ident->name : "anonymous",
 933                          expr->member->name);
 934                 return alloc_string(buf);
 935         }
 936         if (!sym->ident) {
 937                 struct expression *deref;
 938                 char *full, *outer;
 939                 int len;
 940
 941                 /*
 942                  * If we're in an anonymous struct then maybe we can find an
 943                  * outer struct name to use as a name.  This code should be
 944                  * recursive and cleaner.  I am not very proud of it.
 945                  *
 946                  */
 947
 948                 deref = expr->deref;
 949                 if (deref->type != EXPR_DEREF || !deref->member)
 950                         return NULL;
 951                 sym = get_type(deref->deref);
 952                 if (!sym || sym->type != SYM_STRUCT || !sym->ident)
 953                         return NULL;
 954
 955                 full = expr_to_str(expr);
 956                 if (!full)
 957                         return NULL;
 958                 deref = deref->deref;
 959                 if (deref->type == EXPR_PREOP && deref->op == '*')
 960                         deref = deref->unop;
 961                 outer = expr_to_str(deref);
 962                 if (!outer) {
 963                         free_string(full);
 964                         return NULL;
 965                 }
 966                 len = strlen(outer);
 967                 if (strncmp(outer, full, len) != 0) {
 968                         free_string(full);
 969                         free_string(outer);
 970                         return NULL;
 971                 }
 972                 if (full[len] == '-' && full[len + 1] == '>')
 973                         len += 2;
 974                 if (full[len] == '.')
 975                         len++;
 976                 snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, full + len);
 977                 free_string(outer);
 978                 free_string(full);
 979
 980                 return alloc_string(buf);
 981         }
 982         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 983         return alloc_string(buf);
 984 }
 985
 986 int cmp_pos(struct position pos1, struct position pos2)
 987 {
 988         /* the stream position is ... */
 989         if (pos1.stream > pos2.stream)
 990                 return -1;
 991         if (pos1.stream < pos2.stream)
 992                 return 1;
 993
 994         if (pos1.line < pos2.line)
 995                 return -1;
 996         if (pos1.line > pos2.line)
 997                 return 1;
 998
 999         if (pos1.pos < pos2.pos)
1000                 return -1;
1001         if (pos1.pos > pos2.pos)
1002                 return 1;
1003
1004         return 0;
1005 }
1006
1007 int positions_eq(struct position pos1, struct position pos2)
1008 {
1009         if (pos1.line != pos2.line)
1010                 return 0;
1011         if (pos1.pos != pos2.pos)
1012                 return 0;
1013         if (pos1.stream != pos2.stream)
1014                 return 0;
1015         return 1;
1016 }
1017
1018 struct statement *get_current_statement(void)
1019 {
1020         struct statement *prev, *tmp;
1021
1022         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
1023
1024         if (!prev || !get_macro_name(prev->pos))
1025                 return prev;
1026
1027         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
1028                 if (positions_eq(tmp->pos, prev->pos))
1029                         continue;
1030                 if (prev->pos.line > tmp->pos.line)
1031                         return prev;
1032                 return tmp;
1033         } END_FOR_EACH_PTR_REVERSE(tmp);
1034         return prev;
1035 }
1036
1037 struct statement *get_prev_statement(void)
1038 {
1039         struct statement *tmp;
1040         int i;
1041
1042         i = 0;
1043         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
1044                 if (i++ == 1)
1045                         return tmp;
1046         } END_FOR_EACH_PTR_REVERSE(tmp);
1047         return NULL;
1048 }
1049
1050 struct expression *get_last_expr_from_expression_stmt(struct expression *expr)
1051 {
1052         struct statement *stmt;
1053         struct statement *last_stmt;
1054
1055         while (expr->type == EXPR_PREOP && expr->op == '(')
1056                 expr = expr->unop;
1057         if (expr->type != EXPR_STATEMENT)
1058                 return NULL;
1059         stmt = expr->statement;
1060         if (!stmt)
1061                 return NULL;
1062         if (stmt->type == STMT_COMPOUND) {
1063                 last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
1064                 if (!last_stmt)
1065                         return NULL;
1066                 if (last_stmt->type == STMT_LABEL)
1067                         last_stmt = last_stmt->label_statement;
1068                 if (last_stmt->type != STMT_EXPRESSION)
1069                         return NULL;
1070                 return last_stmt->expression;
1071         }
1072         if (stmt->type == STMT_EXPRESSION)
1073                 return stmt->expression;
1074         return NULL;
1075 }
1076
1077 int ms_since(struct timeval *start)
1078 {
1079         struct timeval end;
1080         double diff;
1081
1082         gettimeofday(&end, NULL);
1083         diff = (end.tv_sec - start->tv_sec) * 1000.0;
1084         diff += (end.tv_usec - start->tv_usec) / 1000.0;
1085         return (int)diff;
1086 }
1087
1088 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
1089 {
1090         if (!name || !sym)
1091                 return 0;
1092
1093         if (parent_is_err_or_null_var_sym(name, sym) ||
1094             parent_is_free_var_sym(name, sym))
1095                 return 1;
1096         return 0;
1097 }
1098
1099 int parent_is_gone(struct expression *expr)
1100 {
1101         struct symbol *sym;
1102         char *var;
1103         int ret = 0;
1104
1105         expr = strip_expr(expr);
1106         var = expr_to_var_sym(expr, &sym);
1107         if (!var || !sym)
1108                 goto free;
1109         ret = parent_is_gone_var_sym(var, sym);
1110 free:
1111         free_string(var);
1112         return ret;
1113 }
1114
1115 int invert_op(int op)
1116 {
1117         switch (op) {
1118         case '*':
1119                 return '/';
1120         case '/':
1121                 return '*';
1122         case '+':
1123                 return '-';
1124         case '-':
1125                 return '+';
1126         case SPECIAL_LEFTSHIFT:
1127                 return SPECIAL_RIGHTSHIFT;
1128         case SPECIAL_RIGHTSHIFT:
1129                 return SPECIAL_LEFTSHIFT;
1130         }
1131         return 0;
1132 }
1133
1134 int op_remove_assign(int op)
1135 {
1136         switch (op) {
1137         case SPECIAL_ADD_ASSIGN:
1138                 return '+';
1139         case SPECIAL_SUB_ASSIGN:
1140                 return '-';
1141         case SPECIAL_MUL_ASSIGN:
1142                 return '*';
1143         case SPECIAL_DIV_ASSIGN:
1144                 return '/';
1145         case SPECIAL_MOD_ASSIGN:
1146                 return '%';
1147         case SPECIAL_AND_ASSIGN:
1148                 return '&';
1149         case SPECIAL_OR_ASSIGN:
1150                 return '|';
1151         case SPECIAL_XOR_ASSIGN:
1152                 return '^';
1153         case SPECIAL_SHL_ASSIGN:
1154                 return SPECIAL_LEFTSHIFT;
1155         case SPECIAL_SHR_ASSIGN:
1156                 return SPECIAL_RIGHTSHIFT;
1157         default:
1158                 return op;
1159         }
1160 }
1161
1162 int expr_equiv(struct expression *one, struct expression *two)
1163 {
1164         struct symbol *one_sym = NULL;
1165         struct symbol *two_sym = NULL;
1166         char *one_name = NULL;
1167         char *two_name = NULL;
1168         int ret = 0;
1169
1170         if (!one || !two)
1171                 return 0;
1172         if (one->type != two->type)
1173                 return 0;
1174         if (is_fake_call(one) || is_fake_call(two))
1175                 return 0;
1176
1177         one_name = expr_to_str_sym(one, &one_sym);
1178         if (!one_name)
1179                 goto free;
1180         two_name = expr_to_str_sym(two, &two_sym);
1181         if (!two_name)
1182                 goto free;
1183         if (one_sym != two_sym)
1184                 goto free;
1185         /*
1186          * This is a terrible hack because expr_to_str() sometimes gives up in
1187          * the middle and just returns what it has.  If you see a () you know
1188          * the string is bogus.
1189          */
1190         if (strstr(one_name, "()"))
1191                 goto free;
1192         if (strcmp(one_name, two_name) == 0)
1193                 ret = 1;
1194 free:
1195         free_string(one_name);
1196         free_string(two_name);
1197         return ret;
1198 }
1199
1200 void push_int(struct int_stack **stack, int num)
1201 {
1202         int *munged;
1203
1204         /*
1205          * Just put the int on directly instead of a pointer to the int.
1206          * Shift it to the left because Sparse uses the last two bits.
1207          * This is sort of a dirty hack, yes.
1208          */
1209
1210         munged = INT_PTR(num << 2);
1211
1212         add_ptr_list(stack, munged);
1213 }
1214
1215 int pop_int(struct int_stack **stack)
1216 {
1217         int *num;
1218
1219         num = last_ptr_list((struct ptr_list *)*stack);
1220         delete_ptr_list_last((struct ptr_list **)stack);
1221
1222         return PTR_INT(num) >> 2;
1223 }