smatch_extra.c

   1 /*
   2  * sparse/smatch_extra.c
   3  *
   4  * Copyright (C) 2008 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * smatch_extra.c is supposed to track the value of every variable.
  12  *
  13  */
  14
  15 #include <stdlib.h>
  16 #include <errno.h>
  17 #ifndef __USE_ISOC99
  18 #define __USE_ISOC99
  19 #endif
  20 #include <limits.h>
  21 #include "parse.h"
  22 #include "smatch.h"
  23 #include "smatch_slist.h"
  24 #include "smatch_extra.h"
  25
  26 static int my_id;
  27
  28 struct string_list *__ignored_macros = NULL;
  29 static int in_warn_on_macro()
  30 {
  31         struct statement *stmt;
  32         char *tmp;
  33         char *macro;
  34
  35         stmt = get_current_statement();
  36         macro = get_macro_name(stmt->pos);
  37         if (!macro)
  38                 return 0;
  39
  40         FOR_EACH_PTR(__ignored_macros, tmp) {
  41                 if (!strcmp(tmp, macro))
  42                         return 1;
  43         } END_FOR_EACH_PTR(tmp);
  44         return 0;
  45 }
  46
  47 typedef void (mod_hook)(const char *name, struct symbol *sym, struct smatch_state *state);
  48 DECLARE_PTR_LIST(void_fn_list, mod_hook *);
  49 static struct void_fn_list *extra_mod_hooks;
  50 void add_extra_mod_hook(mod_hook *fn)
  51 {
  52         mod_hook **p = malloc(sizeof(mod_hook *));
  53         *p = fn;
  54         add_ptr_list(&extra_mod_hooks, p);
  55 }
  56
  57 void call_extra_mod_hooks(const char *name, struct symbol *sym, struct smatch_state *state)
  58 {
  59         mod_hook **fn;
  60
  61         FOR_EACH_PTR(extra_mod_hooks, fn) {
  62                 (*fn)(name, sym, state);
  63         } END_FOR_EACH_PTR(fn);
  64 }
  65
  66 struct sm_state *set_extra_mod(const char *name, struct symbol *sym, struct smatch_state *state)
  67 {
  68         if (in_warn_on_macro())
  69                 return NULL;
  70         remove_from_equiv(name, sym);
  71         call_extra_mod_hooks(name, sym, state);
  72         return set_state(SMATCH_EXTRA, name, sym, state);
  73 }
  74
  75 struct sm_state *set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
  76 {
  77         struct symbol *sym;
  78         char *name;
  79         struct sm_state *ret = NULL;
  80
  81         expr = strip_expr(expr);
  82         name = expr_to_var_sym(expr, &sym);
  83         if (!name || !sym)
  84                 goto free;
  85         ret = set_extra_mod(name, sym, state);
  86 free:
  87         free_string(name);
  88         return ret;
  89 }
  90
  91 void set_extra_nomod(const char *name, struct symbol *sym, struct smatch_state *state)
  92 {
  93         struct relation *rel;
  94         struct smatch_state *orig_state;
  95
  96         orig_state = get_state(SMATCH_EXTRA, name, sym);
  97
  98         if (!estate_related(orig_state)) {
  99                 set_state(SMATCH_EXTRA, name, sym, state);
 100                 return;
 101         }
 102
 103         set_related(state, estate_related(orig_state));
 104         FOR_EACH_PTR(estate_related(orig_state), rel) {
 105                 if (option_debug_related)
 106                         sm_msg("updating related %s to %s", rel->name, state->name);
 107                 set_state(SMATCH_EXTRA, rel->name, rel->sym, state);
 108         } END_FOR_EACH_PTR(rel);
 109 }
 110
 111 /*
 112  * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
 113  */
 114 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
 115 {
 116         char *name;
 117         struct symbol *sym;
 118
 119         name = expr_to_var_sym(expr, &sym);
 120         if (!name || !sym)
 121                 goto free;
 122         set_extra_nomod(name, sym, state);
 123 free:
 124         free_string(name);
 125
 126 }
 127
 128 static void set_extra_true_false(const char *name, struct symbol *sym,
 129                         struct smatch_state *true_state,
 130                         struct smatch_state *false_state)
 131 {
 132         struct relation *rel;
 133         struct smatch_state *orig_state;
 134
 135         if (in_warn_on_macro())
 136                 return;
 137
 138         orig_state = get_state(SMATCH_EXTRA, name, sym);
 139
 140         if (!estate_related(orig_state)) {
 141                 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
 142                 return;
 143         }
 144
 145         if (true_state)
 146                 set_related(true_state, estate_related(orig_state));
 147         if (false_state)
 148                 set_related(false_state, estate_related(orig_state));
 149
 150         FOR_EACH_PTR(estate_related(orig_state), rel) {
 151                 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
 152                                 true_state, false_state);
 153         } END_FOR_EACH_PTR(rel);
 154 }
 155
 156 static void set_extra_expr_true_false(struct expression *expr,
 157                 struct smatch_state *true_state,
 158                 struct smatch_state *false_state)
 159 {
 160         char *name;
 161         struct symbol *sym;
 162
 163         expr = strip_expr(expr);
 164         name = expr_to_var_sym(expr, &sym);
 165         if (!name || !sym)
 166                 goto free;
 167         set_extra_true_false(name, sym, true_state, false_state);
 168 free:
 169         free_string(name);
 170 }
 171
 172 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
 173 {
 174         struct expression *iter_var;
 175         struct expression *condition;
 176         struct sm_state *sm;
 177         struct smatch_state *estate;
 178         sval_t start;
 179
 180         condition = strip_expr(loop->iterator_pre_condition);
 181         if (!condition)
 182                 return NULL;
 183         if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
 184                 return NULL;
 185         if (condition->op != SPECIAL_DECREMENT)
 186                 return NULL;
 187
 188         iter_var = condition->unop;
 189         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 190         if (!sm)
 191                 return NULL;
 192         if (sval_cmp_val(estate_min(sm->state), 0) < 0)
 193                 return NULL;
 194         start = estate_max(sm->state);
 195         if  (sval_cmp_val(start, 0) <= 0)
 196                 return NULL;
 197         if (!sval_is_max(start))
 198                 start.value--;
 199
 200         if (condition->type == EXPR_PREOP) {
 201                 estate = alloc_estate_range(sval_type_val(start.type, 1), start);
 202                 if (estate_has_hard_max(sm->state))
 203                         estate_set_hard_max(estate);
 204                 set_extra_expr_mod(iter_var, estate);
 205         }
 206         if (condition->type == EXPR_POSTOP) {
 207                 estate = alloc_estate_range(sval_type_val(start.type, 0), start);
 208                 if (estate_has_hard_max(sm->state))
 209                         estate_set_hard_max(estate);
 210                 set_extra_expr_mod(iter_var, estate);
 211         }
 212         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 213 }
 214
 215 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
 216                                                 struct expression *condition)
 217 {
 218         struct expression *iter_var;
 219         struct sm_state *sm;
 220         struct smatch_state *estate;
 221         sval_t start, end, dummy;
 222
 223         iter_var = iter_expr->unop;
 224         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 225         if (!sm)
 226                 return NULL;
 227         if (!estate_get_single_value(sm->state, &start))
 228                 return NULL;
 229         if (!get_implied_max(condition->right, &end))
 230                 end = sval_type_max(get_type(iter_var));
 231
 232         if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
 233                 return NULL;
 234
 235         switch (condition->op) {
 236         case SPECIAL_NOTEQUAL:
 237         case '<':
 238                 if (!sval_is_min(end))
 239                         end.value--;
 240                 break;
 241         case SPECIAL_LTE:
 242                 break;
 243         default:
 244                 return NULL;
 245         }
 246         if (sval_cmp(end, start) < 0)
 247                 return NULL;
 248         estate = alloc_estate_range(start, end);
 249         if (get_hard_max(condition->right, &dummy))
 250                 estate_set_hard_max(estate);
 251         set_extra_expr_mod(iter_var, estate);
 252         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 253 }
 254
 255 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
 256                                                 struct expression *condition)
 257 {
 258         struct expression *iter_var;
 259         struct sm_state *sm;
 260         struct smatch_state *estate;
 261         sval_t start, end;
 262
 263         iter_var = iter_expr->unop;
 264         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 265         if (!sm)
 266                 return NULL;
 267         if (!estate_get_single_value(sm->state, &start))
 268                 return NULL;
 269         if (!get_implied_min(condition->right, &end))
 270                 end = sval_type_min(get_type(iter_var));
 271         if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
 272                 return NULL;
 273
 274         switch (condition->op) {
 275         case SPECIAL_NOTEQUAL:
 276         case '>':
 277                 if (!sval_is_min(end) && !sval_is_max(end))
 278                         end.value++;
 279                 break;
 280         case SPECIAL_GTE:
 281                 break;
 282         default:
 283                 return NULL;
 284         }
 285         if (sval_cmp(end, start) > 0)
 286                 return NULL;
 287         estate = alloc_estate_range(end, start);
 288         estate_set_hard_max(estate);
 289         set_extra_expr_mod(iter_var, estate);
 290         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 291 }
 292
 293 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
 294 {
 295         struct expression *iter_expr;
 296         struct expression *condition;
 297
 298         if (!loop->iterator_post_statement)
 299                 return NULL;
 300         if (loop->iterator_post_statement->type != STMT_EXPRESSION)
 301                 return NULL;
 302         iter_expr = loop->iterator_post_statement->expression;
 303         if (!loop->iterator_pre_condition)
 304                 return NULL;
 305         if (loop->iterator_pre_condition->type != EXPR_COMPARE)
 306                 return NULL;
 307         condition = loop->iterator_pre_condition;
 308
 309         if (iter_expr->op == SPECIAL_INCREMENT)
 310                 return handle_canonical_for_inc(iter_expr, condition);
 311         if (iter_expr->op == SPECIAL_DECREMENT)
 312                 return handle_canonical_for_dec(iter_expr, condition);
 313         return NULL;
 314 }
 315
 316 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct state_list **slist)
 317 {
 318         struct sm_state *ret;
 319
 320         __push_fake_cur_slist();
 321         if (!loop->iterator_post_statement)
 322                 ret = handle_canonical_while_count_down(loop);
 323         else
 324                 ret = handle_canonical_for_loops(loop);
 325         *slist = __pop_fake_cur_slist();
 326         return ret;
 327 }
 328
 329 int __iterator_unchanged(struct sm_state *sm)
 330 {
 331         if (!sm)
 332                 return 0;
 333         if (get_sm_state(my_id, sm->name, sm->sym) == sm)
 334                 return 1;
 335         return 0;
 336 }
 337
 338 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
 339 {
 340         sval_t after_value;
 341
 342         /* paranoid checking.  prolly not needed */
 343         condition = strip_expr(condition);
 344         if (!condition)
 345                 return;
 346         if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
 347                 return;
 348         if (condition->op != SPECIAL_DECREMENT)
 349                 return;
 350         after_value = estate_min(sm->state);
 351         after_value.value--;
 352         set_extra_mod(sm->name, sm->sym, alloc_estate_sval(after_value));
 353 }
 354
 355 void __extra_pre_loop_hook_after(struct sm_state *sm,
 356                                 struct statement *iterator,
 357                                 struct expression *condition)
 358 {
 359         struct expression *iter_expr;
 360         sval_t limit;
 361         struct smatch_state *state;
 362
 363         if (!iterator) {
 364                 while_count_down_after(sm, condition);
 365                 return;
 366         }
 367
 368         iter_expr = iterator->expression;
 369
 370         if (condition->type != EXPR_COMPARE)
 371                 return;
 372         if (iter_expr->op == SPECIAL_INCREMENT) {
 373                 limit = sval_binop(estate_max(sm->state), '+',
 374                                    sval_type_val(estate_type(sm->state), 1));
 375         } else {
 376                 limit = sval_binop(estate_min(sm->state), '-',
 377                                    sval_type_val(estate_type(sm->state), 1));
 378         }
 379         if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
 380                 if (iter_expr->op == SPECIAL_INCREMENT)
 381                         state = alloc_estate_range(estate_min(sm->state), limit);
 382                 else
 383                         state = alloc_estate_range(limit, estate_max(sm->state));
 384         } else {
 385                 state = alloc_estate_sval(limit);
 386         }
 387         if (!estate_has_hard_max(sm->state))
 388                 estate_clear_hard_max(state);
 389         set_extra_mod(sm->name, sm->sym, state);
 390 }
 391
 392 static struct state_list *unmatched_slist;
 393 static struct smatch_state *unmatched_state(struct sm_state *sm)
 394 {
 395         struct smatch_state *state;
 396
 397         if (unmatched_slist) {
 398                 state = get_state_slist(unmatched_slist, SMATCH_EXTRA, sm->name, sm->sym);
 399                 if (state)
 400                         return state;
 401         }
 402         return alloc_estate_whole(estate_type(sm->state));
 403 }
 404
 405 static void clear_the_pointed_at(struct expression *expr, struct state_list *slist)
 406 {
 407         char *name;
 408         struct symbol *sym;
 409         struct sm_state *tmp;
 410
 411         name = expr_to_var_sym(expr, &sym);
 412         if (!name || !sym)
 413                 goto free;
 414
 415         FOR_EACH_PTR(slist, tmp) {
 416                 if (tmp->name[0] != '*')
 417                         continue;
 418                 if (tmp->sym != sym)
 419                         continue;
 420                 if (strcmp(tmp->name + 1, name) != 0)
 421                         continue;
 422                 set_extra_mod(tmp->name, tmp->sym, alloc_estate_whole(estate_type(tmp->state)));
 423         } END_FOR_EACH_PTR(tmp);
 424
 425 free:
 426         free_string(name);
 427 }
 428
 429 static void match_function_call(struct expression *expr)
 430 {
 431         struct expression *arg;
 432         struct expression *tmp;
 433         struct state_list *slist;
 434
 435         slist = get_all_states(SMATCH_EXTRA);
 436
 437         FOR_EACH_PTR(expr->args, arg) {
 438                 tmp = strip_expr(arg);
 439                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 440                         set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
 441                 else
 442                         clear_the_pointed_at(tmp, slist);
 443         } END_FOR_EACH_PTR(arg);
 444
 445         free_slist(&slist);
 446 }
 447
 448 static int types_equiv_or_pointer(struct symbol *one, struct symbol *two)
 449 {
 450         if (!one || !two)
 451                 return 0;
 452         if (one->type == SYM_PTR && two->type == SYM_PTR)
 453                 return 1;
 454         return types_equiv(one, two);
 455 }
 456
 457 static void match_assign(struct expression *expr)
 458 {
 459         struct range_list *rl = NULL;
 460         struct expression *left;
 461         struct expression *right;
 462         struct symbol *right_sym;
 463         char *right_name = NULL;
 464         struct symbol *sym;
 465         char *name;
 466         sval_t value;
 467         int known;
 468         sval_t right_min, right_max;
 469         sval_t tmp;
 470
 471         if (is_condition(expr->right))
 472                 return;
 473         left = strip_expr(expr->left);
 474         name = expr_to_var_sym(left, &sym);
 475         if (!name)
 476                 return;
 477         right = strip_parens(expr->right);
 478         while (right->type == EXPR_ASSIGNMENT && right->op == '=')
 479                 right = strip_parens(right->left);
 480
 481         if (expr->op == '=' && right->type == EXPR_CALL)
 482                 goto free;  /* these are handled in smatch_function_hooks.c */
 483
 484         right_name = expr_to_var_sym(right, &right_sym);
 485         if (expr->op == '=' && right_name && right_sym &&
 486             types_equiv_or_pointer(get_type(expr->left), get_type(expr->right))) {
 487                 set_equiv(left, right);
 488                 goto free;
 489         }
 490
 491         right_min = sval_type_min(get_type(expr->right));
 492         right_max = sval_type_max(get_type(expr->right));
 493
 494         known = get_implied_value(right, &value);
 495         switch (expr->op) {
 496         case '=': {
 497                 struct smatch_state *state;
 498
 499                 if (get_implied_rl(right, &rl)) {
 500                         rl = cast_rl(get_type(expr->left), rl);
 501                         state = alloc_estate_rl(rl);
 502                         if (get_hard_max(right, &tmp))
 503                                 estate_set_hard_max(state);
 504                 } else {
 505                         rl = alloc_whole_rl(get_type(right));
 506                         rl = cast_rl(get_type(expr->left), rl);
 507                         state = alloc_estate_rl(rl);
 508                 }
 509                 set_extra_mod(name, sym, state);
 510                 goto free;
 511         }
 512         case SPECIAL_ADD_ASSIGN:
 513                 if (get_implied_min(left, &tmp)) {
 514                         if (known)
 515                                 right_min = sval_binop(tmp, '+', value);
 516                         else
 517                                 right_min = tmp;
 518                 }
 519                 if (!inside_loop() && known && get_implied_max(left, &tmp))
 520                         right_max = sval_binop(tmp, '+', value);
 521                 break;
 522         case SPECIAL_SUB_ASSIGN:
 523                 if (get_implied_max(left, &tmp)) {
 524                         if (known)
 525                                 right_max = sval_binop(tmp, '-', value);
 526                         else
 527                                 right_max = tmp;
 528                 }
 529                 if (!inside_loop() && known && get_implied_min(left, &tmp))
 530                         right_min = sval_binop(tmp, '-', value);
 531                 break;
 532         }
 533         if (!sval_is_min(right_min) || !sval_is_max(right_max))
 534                 rl = cast_rl(get_type(expr->left), alloc_rl(right_min, right_max));
 535         else
 536                 rl = alloc_whole_rl(get_type(expr->left));
 537         set_extra_mod(name, sym, alloc_estate_rl(rl));
 538 free:
 539         free_string(right_name);
 540         free_string(name);
 541 }
 542
 543 static void reset_struct_members(struct sm_state *sm)
 544 {
 545         if (!estate_rl(sm->state))
 546                 return;
 547         set_extra_mod(sm->name, sm->sym, alloc_estate_whole(estate_type(sm->state)));
 548 }
 549
 550 static struct smatch_state *increment_state(struct smatch_state *state)
 551 {
 552         sval_t min = estate_min(state);
 553         sval_t max = estate_max(state);
 554
 555         if (!estate_rl(state))
 556                 return NULL;
 557
 558         if (inside_loop())
 559                 max = sval_type_max(max.type);
 560
 561         if (!sval_is_min(min) && !sval_is_max(min))
 562                 min.value++;
 563         if (!sval_is_min(max) && !sval_is_max(max))
 564                 max.value++;
 565         return alloc_estate_range(min, max);
 566 }
 567
 568 static struct smatch_state *decrement_state(struct smatch_state *state)
 569 {
 570         sval_t min = estate_min(state);
 571         sval_t max = estate_max(state);
 572
 573         if (!estate_rl(state))
 574                 return NULL;
 575
 576         if (inside_loop())
 577                 min = sval_type_min(min.type);
 578
 579         if (!sval_is_min(min) && !sval_is_max(min))
 580                 min.value--;
 581         if (!sval_is_min(max) && !sval_is_max(max))
 582                 max.value--;
 583         return alloc_estate_range(min, max);
 584 }
 585
 586 static void unop_expr(struct expression *expr)
 587 {
 588         struct smatch_state *state;
 589
 590         if (expr->smatch_flags & Handled)
 591                 return;
 592
 593         switch (expr->op) {
 594         case SPECIAL_INCREMENT:
 595                 state = get_state_expr(SMATCH_EXTRA, expr->unop);
 596                 state = increment_state(state);
 597                 if (!state)
 598                         state = alloc_estate_whole(get_type(expr));
 599                 set_extra_expr_mod(expr->unop, state);
 600                 break;
 601         case SPECIAL_DECREMENT:
 602                 state = get_state_expr(SMATCH_EXTRA, expr->unop);
 603                 state = decrement_state(state);
 604                 if (!state)
 605                         state = alloc_estate_whole(get_type(expr));
 606                 set_extra_expr_mod(expr->unop, state);
 607                 break;
 608         default:
 609                 return;
 610         }
 611 }
 612
 613 static void asm_expr(struct statement *stmt)
 614 {
 615
 616         struct expression *expr;
 617         int state = 0;
 618
 619         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 620                 switch (state) {
 621                 case 0: /* identifier */
 622                 case 1: /* constraint */
 623                         state++;
 624                         continue;
 625                 case 2: /* expression */
 626                         state = 0;
 627                         set_extra_expr_mod(expr, alloc_estate_whole(get_type(expr)));
 628                         continue;
 629                 }
 630         } END_FOR_EACH_PTR(expr);
 631 }
 632
 633 static void delete_state_tracker(struct tracker *t)
 634 {
 635         remove_from_equiv(t->name, t->sym);
 636         delete_state(t->owner, t->name, t->sym);
 637 }
 638
 639 static void scoped_state_extra(const char *name, struct symbol *sym)
 640 {
 641         struct tracker *t;
 642
 643         t = alloc_tracker(SMATCH_EXTRA, name, sym);
 644         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 645 }
 646
 647 static void match_declarations(struct symbol *sym)
 648 {
 649         const char *name;
 650
 651         if (sym->ident) {
 652                 name = sym->ident->name;
 653                 if (!sym->initializer) {
 654                         set_state(SMATCH_EXTRA, name, sym, alloc_estate_whole(get_real_base_type(sym)));
 655                         scoped_state_extra(name, sym);
 656                 }
 657         }
 658 }
 659
 660 static void check_dereference(struct expression *expr)
 661 {
 662         set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 663 }
 664
 665 static void match_dereferences(struct expression *expr)
 666 {
 667         if (expr->type != EXPR_PREOP)
 668                 return;
 669         check_dereference(expr->unop);
 670 }
 671
 672 static void match_pointer_as_array(struct expression *expr)
 673 {
 674         if (!is_array(expr))
 675                 return;
 676         check_dereference(expr->unop->left);
 677 }
 678
 679 static void set_param_dereferenced(struct expression *arg, char *unused)
 680 {
 681         check_dereference(arg);
 682 }
 683
 684 static void match_function_def(struct symbol *sym)
 685 {
 686         struct symbol *arg;
 687
 688         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
 689                 if (!arg->ident)
 690                         continue;
 691                 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
 692         } END_FOR_EACH_PTR(arg);
 693 }
 694
 695 static int match_func_comparison(struct expression *expr)
 696 {
 697         struct expression *left = strip_expr(expr->left);
 698         struct expression *right = strip_expr(expr->right);
 699         sval_t sval;
 700
 701         if (left->type == EXPR_CALL) {
 702                 if (!get_implied_value(right, &sval))
 703                         return 1;
 704                 function_comparison(expr->op, left, sval, 1);
 705                 return 1;
 706         }
 707
 708         if (right->type == EXPR_CALL) {
 709                 if (!get_implied_value(left, &sval))
 710                         return 1;
 711                 function_comparison(expr->op, right, sval, 0);
 712                 return 1;
 713         }
 714
 715         return 0;
 716 }
 717
 718 static sval_t add_one(sval_t sval)
 719 {
 720         sval.value++;
 721         return sval;
 722 }
 723
 724 static sval_t sub_one(sval_t sval)
 725 {
 726         sval.value--;
 727         return sval;
 728 }
 729
 730 static void match_comparison(struct expression *expr)
 731 {
 732         struct expression *left = strip_expr(expr->left);
 733         struct expression *right = strip_expr(expr->right);
 734         struct symbol *type;
 735         struct range_list *left_orig;
 736         struct range_list *left_true;
 737         struct range_list *left_false;
 738         struct range_list *right_orig;
 739         struct range_list *right_true;
 740         struct range_list *right_false;
 741         struct smatch_state *left_true_state;
 742         struct smatch_state *left_false_state;
 743         struct smatch_state *right_true_state;
 744         struct smatch_state *right_false_state;
 745         sval_t min, max, dummy;
 746         int left_postop = 0;
 747         int right_postop = 0;
 748
 749         if (match_func_comparison(expr))
 750                 return;
 751
 752         if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
 753                 if (left->type == EXPR_POSTOP) {
 754                         left->smatch_flags |= Handled;
 755                         left_postop = left->op;
 756                 }
 757                 left = strip_expr(left->unop);
 758         }
 759         while (left->type == EXPR_ASSIGNMENT)
 760                 left = strip_expr(left->left);
 761
 762         if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
 763                 if (right->type == EXPR_POSTOP) {
 764                         right->smatch_flags |= Handled;
 765                         right_postop = right->op;
 766                 }
 767                 right = strip_expr(right->unop);
 768         }
 769
 770         type = get_type(expr);
 771         if (!type)
 772                 type = &llong_ctype;
 773
 774         if (get_implied_rl(left, &left_orig)) {
 775                 left_orig = cast_rl(type, left_orig);
 776         } else {
 777                 min = sval_type_min(get_type(left));
 778                 max = sval_type_max(get_type(left));
 779                 left_orig = cast_rl(type, alloc_rl(min, max));
 780         }
 781
 782         if (get_implied_rl(right, &right_orig)) {
 783                 right_orig = cast_rl(type, right_orig);
 784         } else {
 785                 min = sval_type_min(get_type(right));
 786                 max = sval_type_max(get_type(right));
 787                 right_orig = cast_rl(type, alloc_rl(min, max));
 788         }
 789         min = sval_type_min(type);
 790         max = sval_type_max(type);
 791
 792         left_true = clone_rl(left_orig);
 793         left_false = clone_rl(left_orig);
 794         right_true = clone_rl(right_orig);
 795         right_false = clone_rl(right_orig);
 796
 797         switch (expr->op) {
 798         case '<':
 799         case SPECIAL_UNSIGNED_LT:
 800                 left_true = remove_range(left_orig, rl_max(right_orig), max);
 801                 if (!sval_is_min(rl_min(right_orig))) {
 802                         left_false = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
 803                 }
 804
 805                 right_true = remove_range(right_orig, min, rl_min(left_orig));
 806                 if (!sval_is_max(rl_max(left_orig)))
 807                         right_false = remove_range(right_orig, add_one(rl_max(left_orig)), max);
 808                 break;
 809         case SPECIAL_UNSIGNED_LTE:
 810         case SPECIAL_LTE:
 811                 if (!sval_is_max(rl_max(right_orig)))
 812                         left_true = remove_range(left_orig, add_one(rl_max(right_orig)), max);
 813                 left_false = remove_range(left_orig, min, rl_min(right_orig));
 814
 815                 if (!sval_is_min(rl_min(left_orig)))
 816                         right_true = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
 817                 right_false = remove_range(right_orig, rl_max(left_orig), max);
 818
 819                 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
 820                         left_false = remove_range(left_false, rl_min(left_orig), rl_min(left_orig));
 821                 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
 822                         right_false = remove_range(right_false, rl_max(left_orig), rl_max(left_orig));
 823                 break;
 824         case SPECIAL_EQUAL:
 825                 if (!sval_is_max(rl_max(right_orig))) {
 826                         left_true = remove_range(left_true, add_one(rl_max(right_orig)), max);
 827                 }
 828                 if (!sval_is_min(rl_min(right_orig))) {
 829                         left_true = remove_range(left_true, min, sub_one(rl_min(right_orig)));
 830                 }
 831                 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
 832                         left_false = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
 833
 834                 if (!sval_is_max(rl_max(left_orig)))
 835                         right_true = remove_range(right_true, add_one(rl_max(left_orig)), max);
 836                 if (!sval_is_min(rl_min(left_orig)))
 837                         right_true = remove_range(right_true, min, sub_one(rl_min(left_orig)));
 838                 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
 839                         right_false = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
 840                 break;
 841         case SPECIAL_UNSIGNED_GTE:
 842         case SPECIAL_GTE:
 843                 if (!sval_is_min(rl_min(right_orig)))
 844                         left_true = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
 845                 left_false = remove_range(left_orig, rl_max(right_orig), max);
 846
 847                 if (!sval_is_max(rl_max(left_orig)))
 848                         right_true = remove_range(right_orig, add_one(rl_max(left_orig)), max);
 849                 right_false = remove_range(right_orig, min, rl_min(left_orig));
 850
 851                 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
 852                         right_false = remove_range(right_false, rl_min(left_orig), rl_min(left_orig));
 853                 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
 854                         left_false = remove_range(left_false, rl_max(left_orig), rl_max(left_orig));
 855                 break;
 856         case '>':
 857         case SPECIAL_UNSIGNED_GT:
 858                 left_true = remove_range(left_orig, min, rl_min(right_orig));
 859                 if (!sval_is_max(rl_max(right_orig)))
 860                         left_false = remove_range(left_orig, add_one(rl_max(right_orig)), max);
 861
 862                 right_true = remove_range(right_orig, rl_max(left_orig), max);
 863                 if (!sval_is_min(rl_min(left_orig)))
 864                         right_false = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
 865                 break;
 866         case SPECIAL_NOTEQUAL:
 867                 if (!sval_is_max(rl_max(right_orig)))
 868                         left_false = remove_range(left_false, add_one(rl_max(right_orig)), max);
 869                 if (!sval_is_min(rl_min(right_orig)))
 870                         left_false = remove_range(left_false, min, sub_one(rl_min(right_orig)));
 871                 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
 872                         left_true = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
 873
 874                 if (!sval_is_max(rl_max(left_orig)))
 875                         right_false = remove_range(right_false, add_one(rl_max(left_orig)), max);
 876                 if (!sval_is_min(rl_min(left_orig)))
 877                         right_false = remove_range(right_false, min, sub_one(rl_min(left_orig)));
 878                 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
 879                         right_true = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
 880                 break;
 881         default:
 882                 return;
 883         }
 884
 885         left_true_state = alloc_estate_rl(cast_rl(get_type(left), left_true));
 886         left_false_state = alloc_estate_rl(cast_rl(get_type(left), left_false));
 887         right_true_state = alloc_estate_rl(cast_rl(get_type(right), right_true));
 888         right_false_state = alloc_estate_rl(cast_rl(get_type(right), right_false));
 889
 890         switch (expr->op) {
 891         case '<':
 892         case SPECIAL_UNSIGNED_LT:
 893         case SPECIAL_UNSIGNED_LTE:
 894         case SPECIAL_LTE:
 895                 if (get_hard_max(right, &dummy))
 896                         estate_set_hard_max(left_true_state);
 897                 if (get_hard_max(left, &dummy))
 898                         estate_set_hard_max(right_false_state);
 899                 break;
 900         case '>':
 901         case SPECIAL_UNSIGNED_GT:
 902         case SPECIAL_UNSIGNED_GTE:
 903         case SPECIAL_GTE:
 904                 if (get_hard_max(left, &dummy))
 905                         estate_set_hard_max(right_true_state);
 906                 if (get_hard_max(right, &dummy))
 907                         estate_set_hard_max(left_false_state);
 908                 break;
 909         }
 910
 911         if (get_hard_max(left, &dummy)) {
 912                 estate_set_hard_max(left_true_state);
 913                 estate_set_hard_max(left_false_state);
 914         }
 915         if (get_hard_max(right, &dummy)) {
 916                 estate_set_hard_max(right_true_state);
 917                 estate_set_hard_max(right_false_state);
 918         }
 919
 920         if (left_postop == SPECIAL_INCREMENT) {
 921                 left_true_state = increment_state(left_true_state);
 922                 left_false_state = increment_state(left_false_state);
 923         }
 924         if (left_postop == SPECIAL_DECREMENT) {
 925                 left_true_state = decrement_state(left_true_state);
 926                 left_false_state = decrement_state(left_false_state);
 927         }
 928         if (right_postop == SPECIAL_INCREMENT) {
 929                 right_true_state = increment_state(right_true_state);
 930                 right_false_state = increment_state(right_false_state);
 931         }
 932         if (right_postop == SPECIAL_DECREMENT) {
 933                 right_true_state = decrement_state(right_true_state);
 934                 right_false_state = decrement_state(right_false_state);
 935         }
 936
 937         set_extra_expr_true_false(left, left_true_state, left_false_state);
 938         set_extra_expr_true_false(right, right_true_state, right_false_state);
 939 }
 940
 941 /* this is actually hooked from smatch_implied.c...  it's hacky, yes */
 942 void __extra_match_condition(struct expression *expr)
 943 {
 944         struct symbol *sym;
 945         char *name;
 946         struct smatch_state *pre_state;
 947         struct smatch_state *true_state;
 948         struct smatch_state *false_state;
 949
 950         expr = strip_expr(expr);
 951         switch (expr->type) {
 952         case EXPR_CALL:
 953                 function_comparison(SPECIAL_NOTEQUAL, expr, ll_to_sval(0), 1);
 954                 return;
 955         case EXPR_PREOP:
 956         case EXPR_SYMBOL:
 957         case EXPR_DEREF: {
 958                 sval_t zero;
 959
 960                 zero = sval_blank(expr);
 961                 zero.value = 0;
 962
 963                 name = expr_to_var_sym(expr, &sym);
 964                 if (!name)
 965                         return;
 966                 pre_state = get_state(my_id, name, sym);
 967                 true_state = estate_filter_sval(pre_state, zero);
 968                 if (possibly_true(expr, SPECIAL_EQUAL, zero_expr()))
 969                         false_state = alloc_estate_sval(zero);
 970                 else
 971                         false_state = alloc_estate_empty();
 972                 set_extra_true_false(name, sym, true_state, false_state);
 973                 free_string(name);
 974                 return;
 975         }
 976         case EXPR_COMPARE:
 977                 match_comparison(expr);
 978                 return;
 979         case EXPR_ASSIGNMENT:
 980                 __extra_match_condition(expr->left);
 981                 return;
 982         }
 983 }
 984
 985 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
 986 int implied_not_equal(struct expression *expr, long long val)
 987 {
 988         return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
 989 }
 990
 991 static void struct_member_callback(char *fn, char *global_static, int param, char *printed_name, struct smatch_state *state)
 992 {
 993         if (estate_is_whole(state))
 994                 return;
 995         sm_msg("info: passes param_value '%s' %d '%s' %s %s", fn, param, printed_name, state->name, global_static);
 996 }
 997
 998 static void db_limited_before(void)
 999 {
1000         unmatched_slist = clone_slist(__get_cur_slist());
1001 }
1002
1003 static void db_limited_after(void)
1004 {
1005         free_slist(&unmatched_slist);
1006 }
1007
1008 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value)
1009 {
1010         struct expression *arg;
1011         char *name;
1012         struct symbol *sym;
1013         struct sm_state *sm;
1014         struct symbol *type;
1015         struct range_list *rl;
1016         struct range_list *limit;
1017         struct range_list *new;
1018
1019         while (expr->type == EXPR_ASSIGNMENT)
1020                 expr = strip_expr(expr->right);
1021         if (expr->type != EXPR_CALL)
1022                 return;
1023
1024         arg = get_argument_from_call_expr(expr->args, param);
1025         if (!arg)
1026                 return;
1027
1028         name = get_variable_from_key(arg, key, &sym);
1029         if (!name || !sym)
1030                 goto free;
1031
1032         sm = get_sm_state(SMATCH_EXTRA, name, sym);
1033         type = get_member_type_from_key(arg, key);
1034         if (sm)
1035                 rl = estate_rl(sm->state);
1036         else
1037                 rl = alloc_whole_rl(type);
1038
1039         str_to_rl(type, value, &limit);
1040         new = rl_intersection(rl, limit);
1041
1042         /* We want to preserve the implications here */
1043         if (sm && rl_equiv(estate_rl(sm->state), new))
1044                 __set_sm(sm);
1045         else
1046                 set_extra_nomod(name, sym, alloc_estate_rl(new));
1047
1048 free:
1049         free_string(name);
1050 }
1051
1052 static void db_param_add(struct expression *expr, int param, char *key, char *value)
1053 {
1054         struct expression *arg;
1055         char *name;
1056         struct symbol *sym;
1057         struct symbol *type;
1058         struct smatch_state *state;
1059         struct range_list *added = NULL;
1060         struct range_list *new;
1061
1062         while (expr->type == EXPR_ASSIGNMENT)
1063                 expr = strip_expr(expr->right);
1064         if (expr->type != EXPR_CALL)
1065                 return;
1066
1067         arg = get_argument_from_call_expr(expr->args, param);
1068         if (!arg)
1069                 return;
1070         name = get_variable_from_key(arg, key, &sym);
1071         if (!name || !sym)
1072                 goto free;
1073
1074         type = get_member_type_from_key(arg, key);
1075         state = get_state(SMATCH_EXTRA, name, sym);
1076         if (state) {
1077                 str_to_rl(type, value, &added);
1078                 new = rl_union(estate_rl(state), added);
1079         } else {
1080                 new = alloc_whole_rl(type);
1081         }
1082
1083         set_extra_mod(name, sym, alloc_estate_rl(new));
1084 free:
1085         free_string(name);
1086 }
1087
1088 static void db_returned_states_param(struct expression *expr, int param, char *key, char *value)
1089 {
1090         struct expression *arg;
1091         struct symbol *type;
1092         struct range_list *rl;
1093         char member_name[256];
1094         char *name;
1095         struct symbol *sym;
1096
1097         while (expr->type == EXPR_ASSIGNMENT)
1098                 expr = strip_expr(expr->right);
1099         if (expr->type != EXPR_CALL)
1100                 return;
1101         arg = get_argument_from_call_expr(expr->args, param);
1102         arg = strip_expr(arg);
1103         if (!arg)
1104                 return;
1105
1106         if (strcmp(key, "*$$") == 0) {
1107                 struct symbol *sym;
1108                 char buf[256];
1109                 char *name;
1110
1111                 if (arg->type == EXPR_PREOP && arg->op == '&') {
1112                         arg = strip_expr(arg->unop);
1113                         name = expr_to_var_sym(arg, &sym);
1114                 } else {
1115                         char *tmp = expr_to_var_sym(arg, &sym);
1116
1117                         if (!tmp)
1118                                 return;
1119                         snprintf(buf, sizeof(buf), "*%s", tmp);
1120                         name = alloc_string(buf);
1121                         free_string(tmp);
1122                 }
1123                 if (!name || !sym) {
1124                         free_string(name);
1125                         return;
1126                 }
1127                 type = get_type(arg);
1128                 str_to_rl(type, value, &rl);
1129                 set_extra_mod(name, sym, alloc_estate_rl(rl));
1130                 free_string(name);
1131                 return;
1132         }
1133
1134         if (arg->type == EXPR_PREOP && arg->op == '&') {
1135                 arg = strip_expr(arg->unop);
1136                 name = expr_to_var_sym(arg, &sym);
1137                 if (!name || !sym)
1138                         goto free;
1139                 snprintf(member_name, sizeof(member_name), "%s.%s", name, key + 4);
1140         } else {
1141                 name = expr_to_var_sym(arg, &sym);
1142                 if (!name || !sym)
1143                         goto free;
1144                 snprintf(member_name, sizeof(member_name), "%s%s", name, key + 2);
1145         }
1146         type = get_member_type_from_key(arg, key);
1147         if (!type)
1148                 goto free;
1149         str_to_rl(type, value, &rl);
1150         set_extra_mod(member_name, sym, alloc_estate_rl(rl));
1151 free:
1152         free_string(name);
1153 }
1154
1155 static void db_returned_member_info(struct expression *expr, int param, char *key, char *value)
1156 {
1157         struct symbol *type;
1158         struct symbol *sym;
1159         char *name;
1160         char member_name[256];
1161         struct range_list *rl;
1162
1163         if (expr->type != EXPR_ASSIGNMENT)
1164                 return;
1165
1166         name = expr_to_var_sym(expr->left, &sym);
1167         if (!name || !sym)
1168                 goto free;
1169         snprintf(member_name, sizeof(member_name), "%s%s", name, key + 2);
1170         type = get_member_type_from_key(expr->left, key);
1171         if (!type)
1172                 return;
1173         str_to_rl(type, value, &rl);
1174         set_extra_mod(member_name, sym, alloc_estate_rl(rl));
1175
1176 free:
1177         free_string(name);
1178 }
1179
1180 static void returned_member_callback(int return_id, char *return_ranges, char *printed_name, struct smatch_state *state)
1181 {
1182         if (estate_is_whole(state))
1183                 return;
1184
1185         sql_insert_return_states(return_id, return_ranges, RETURN_VALUE, -1,
1186                         printed_name, state->name);
1187 }
1188
1189 static void match_call_info(struct expression *expr)
1190 {
1191         struct range_list *rl = NULL;
1192         struct expression *arg;
1193         struct symbol *type;
1194         char *name;
1195         int i = 0;
1196
1197         name = get_fnptr_name(expr->fn);
1198         if (!name)
1199                 return;
1200
1201         FOR_EACH_PTR(expr->args, arg) {
1202                 type = get_arg_type(expr->fn, i);
1203
1204                 if (get_implied_rl(arg, &rl))
1205                         rl = cast_rl(type, rl);
1206                 else
1207                         rl = cast_rl(type, alloc_whole_rl(get_type(arg)));
1208
1209                 sm_msg("info: passes param_value '%s' %d '$$' %s %s",
1210                        name, i, show_rl(rl),
1211                        is_static(expr->fn) ? "static" : "global");
1212                 i++;
1213         } END_FOR_EACH_PTR(arg);
1214
1215         free_string(name);
1216 }
1217
1218 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
1219 {
1220         struct range_list *rl = NULL;
1221         struct smatch_state *state;
1222         struct symbol *type;
1223         char fullname[256];
1224
1225         if (strncmp(key, "$$", 2))
1226                 return;
1227
1228         snprintf(fullname, 256, "%s%s", name, key + 2);
1229         type = get_member_type_from_key(symbol_expression(sym), key);
1230         str_to_rl(type, value, &rl);
1231         state = alloc_estate_rl(rl);
1232         set_state(SMATCH_EXTRA, fullname, sym, state);
1233 }
1234
1235 void register_smatch_extra(int id)
1236 {
1237         my_id = id;
1238
1239         add_merge_hook(my_id, &merge_estates);
1240         add_unmatched_state_hook(my_id, &unmatched_state);
1241         add_hook(&match_function_def, FUNC_DEF_HOOK);
1242         add_hook(&match_declarations, DECLARATION_HOOK);
1243         add_definition_db_callback(set_param_value, PARAM_VALUE);
1244         add_db_return_states_callback(RETURN_VALUE, &db_returned_member_info);
1245         add_db_return_states_callback(PARAM_VALUE, &db_returned_states_param);
1246         add_db_return_states_before(&db_limited_before);
1247         add_db_return_states_callback(LIMITED_VALUE, &db_param_limit_filter);
1248         add_db_return_states_callback(FILTER_VALUE, &db_param_limit_filter);
1249         add_db_return_states_callback(ADDED_VALUE, &db_param_add);
1250         add_db_return_states_after(&db_limited_after);
1251 }
1252
1253 void register_smatch_extra_late(int id)
1254 {
1255         add_hook(&match_dereferences, DEREF_HOOK);
1256         add_hook(&match_pointer_as_array, OP_HOOK);
1257         add_db_fn_call_callback(DEREFERENCE, &set_param_dereferenced);
1258         add_indirect_modification_hook(SMATCH_EXTRA, reset_struct_members);
1259         if (option_no_db)
1260                 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
1261         add_hook(&match_assign, ASSIGNMENT_HOOK);
1262         add_hook(&unop_expr, OP_HOOK);
1263         add_hook(&asm_expr, ASM_HOOK);
1264
1265         if (option_info) {
1266                 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1267                 add_member_info_callback(my_id, struct_member_callback);
1268                 add_returned_member_callback(my_id, returned_member_callback);
1269         }
1270 }