?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
comparison: handle preops like "if (++a == b)"
[smatch.git] / smatch_extra.c
blob75f2fcb8f147e89f7a8be28a1b390695850bccd4
1 /*
2 * Copyright (C) 2008 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 * smatch_extra.c is supposed to track the value of every variable.
20 *
21 */
22
23 #include <stdlib.h>
24 #include <errno.h>
25 #ifndef __USE_ISOC99
26 #define __USE_ISOC99
27 #endif
28 #include <limits.h>
29 #include "parse.h"
30 #include "smatch.h"
31 #include "smatch_slist.h"
32 #include "smatch_extra.h"
33
34 static int my_id;
35
36 struct string_list *__ignored_macros = NULL;
37 static int in_warn_on_macro(void)
38 {
39 struct statement *stmt;
40 char *tmp;
41 char *macro;
42
43 stmt = get_current_statement();
44 if (!stmt)
45 return 0;
46 macro = get_macro_name(stmt->pos);
47 if (!macro)
48 return 0;
49
50 FOR_EACH_PTR(__ignored_macros, tmp) {
51 if (!strcmp(tmp, macro))
52 return 1;
53 } END_FOR_EACH_PTR(tmp);
54 return 0;
55 }
56
57 typedef void (mod_hook)(const char *name, struct symbol *sym, struct smatch_state *state);
58 DECLARE_PTR_LIST(void_fn_list, mod_hook *);
59 static struct void_fn_list *extra_mod_hooks;
60 void add_extra_mod_hook(mod_hook *fn)
61 {
62 mod_hook **p = malloc(sizeof(mod_hook *));
63 *p = fn;
64 add_ptr_list(&extra_mod_hooks, p);
65 }
66
67 void call_extra_mod_hooks(const char *name, struct symbol *sym, struct smatch_state *state)
68 {
69 mod_hook **fn;
70
71 FOR_EACH_PTR(extra_mod_hooks, fn) {
72 (*fn)(name, sym, state);
73 } END_FOR_EACH_PTR(fn);
74 }
75
76 struct sm_state *set_extra_mod_helper(const char *name, struct symbol *sym, struct smatch_state *state)
77 {
78 remove_from_equiv(name, sym);
79 call_extra_mod_hooks(name, sym, state);
80 return set_state(SMATCH_EXTRA, name, sym, state);
81 }
82
83 static char *get_other_name_sym(const char *name, struct symbol *sym, struct symbol **new_sym)
84 {
85 struct expression *assigned;
86 char *orig_name;
87 char buf[256];
88 char *ret = NULL;
89 int skip;
90
91 *new_sym = NULL;
92
93 if (!sym->ident)
94 return NULL;
95
96 skip = strlen(sym->ident->name);
97 if (name[skip] != '-' || name[skip + 1] != '>')
98 return NULL;
99 skip += 2;
100
101 assigned = get_assigned_expr_name_sym(sym->ident->name, sym);
102 if (!assigned)
103 return NULL;
104 if (assigned->type != EXPR_PREOP || assigned->op != '&')
105 return NULL;
106
107 orig_name = expr_to_var_sym(assigned, new_sym);
108 if (!orig_name || !*new_sym)
109 goto free;
110
111 snprintf(buf, sizeof(buf), "%s.%s", orig_name + 1, name + skip);
112 ret = alloc_string(buf);
113 free:
114 free_string(orig_name);
115 return ret;
116 }
117
118 struct sm_state *set_extra_mod(const char *name, struct symbol *sym, struct smatch_state *state)
119 {
120 char *new_name;
121 struct symbol *new_sym;
122 struct sm_state *sm;
123
124 if (in_warn_on_macro())
125 return NULL;
126 sm = set_extra_mod_helper(name, sym, state);
127 new_name = get_other_name_sym(name, sym, &new_sym);
128 if (new_name && new_sym)
129 set_extra_mod_helper(new_name, new_sym, state);
130 free_string(new_name);
131 return sm;
132 }
133
134 struct sm_state *set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
135 {
136 struct symbol *sym;
137 char *name;
138 struct sm_state *ret = NULL;
139
140 expr = strip_expr(expr);
141 name = expr_to_var_sym(expr, &sym);
142 if (!name || !sym)
143 goto free;
144 ret = set_extra_mod(name, sym, state);
145 free:
146 free_string(name);
147 return ret;
148 }
149
150 void set_extra_nomod(const char *name, struct symbol *sym, struct smatch_state *state)
151 {
152 char *new_name;
153 struct symbol *new_sym;
154 struct relation *rel;
155 struct smatch_state *orig_state;
156
157 orig_state = get_state(SMATCH_EXTRA, name, sym);
158
159 new_name = get_other_name_sym(name, sym, &new_sym);
160 if (new_name && new_sym)
161 set_state(SMATCH_EXTRA, new_name, new_sym, state);
162 free_string(new_name);
163
164 if (!estate_related(orig_state)) {
165 set_state(SMATCH_EXTRA, name, sym, state);
166 return;
167 }
168
169 set_related(state, estate_related(orig_state));
170 FOR_EACH_PTR(estate_related(orig_state), rel) {
171 if (option_debug_related)
172 sm_msg("%s updating related %s to %s", name, rel->name, state->name);
173 set_state(SMATCH_EXTRA, rel->name, rel->sym, state);
174 } END_FOR_EACH_PTR(rel);
175 }
176
177 /*
178 * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
179 */
180 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
181 {
182 char *name;
183 struct symbol *sym;
184
185 name = expr_to_var_sym(expr, &sym);
186 if (!name || !sym)
187 goto free;
188 set_extra_nomod(name, sym, state);
189 free:
190 free_string(name);
191
192 }
193
194 static void set_extra_true_false(const char *name, struct symbol *sym,
195 struct smatch_state *true_state,
196 struct smatch_state *false_state)
197 {
198 char *new_name;
199 struct symbol *new_sym;
200 struct relation *rel;
201 struct smatch_state *orig_state;
202
203 if (in_warn_on_macro())
204 return;
205
206 new_name = get_other_name_sym(name, sym, &new_sym);
207 if (new_name && new_sym)
208 set_true_false_states(SMATCH_EXTRA, new_name, new_sym, true_state, false_state);
209 free_string(new_name);
210
211 orig_state = get_state(SMATCH_EXTRA, name, sym);
212
213 if (!estate_related(orig_state)) {
214 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
215 return;
216 }
217
218 if (true_state)
219 set_related(true_state, estate_related(orig_state));
220 if (false_state)
221 set_related(false_state, estate_related(orig_state));
222
223 FOR_EACH_PTR(estate_related(orig_state), rel) {
224 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
225 true_state, false_state);
226 } END_FOR_EACH_PTR(rel);
227 }
228
229 static void set_extra_expr_true_false(struct expression *expr,
230 struct smatch_state *true_state,
231 struct smatch_state *false_state)
232 {
233 char *name;
234 struct symbol *sym;
235
236 expr = strip_expr(expr);
237 name = expr_to_var_sym(expr, &sym);
238 if (!name || !sym)
239 goto free;
240 set_extra_true_false(name, sym, true_state, false_state);
241 free:
242 free_string(name);
243 }
244
245 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
246 {
247 struct expression *iter_var;
248 struct expression *condition;
249 struct sm_state *sm;
250 struct smatch_state *estate;
251 sval_t start;
252
253 condition = strip_expr(loop->iterator_pre_condition);
254 if (!condition)
255 return NULL;
256 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
257 return NULL;
258 if (condition->op != SPECIAL_DECREMENT)
259 return NULL;
260
261 iter_var = condition->unop;
262 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
263 if (!sm)
264 return NULL;
265 if (sval_cmp_val(estate_min(sm->state), 0) < 0)
266 return NULL;
267 start = estate_max(sm->state);
268 if (sval_cmp_val(start, 0) <= 0)
269 return NULL;
270 if (!sval_is_max(start))
271 start.value--;
272
273 if (condition->type == EXPR_PREOP) {
274 estate = alloc_estate_range(sval_type_val(start.type, 1), start);
275 if (estate_has_hard_max(sm->state))
276 estate_set_hard_max(estate);
277 estate_copy_fuzzy_max(estate, sm->state);
278 set_extra_expr_mod(iter_var, estate);
279 }
280 if (condition->type == EXPR_POSTOP) {
281 estate = alloc_estate_range(sval_type_val(start.type, 0), start);
282 if (estate_has_hard_max(sm->state))
283 estate_set_hard_max(estate);
284 estate_copy_fuzzy_max(estate, sm->state);
285 set_extra_expr_mod(iter_var, estate);
286 }
287 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
288 }
289
290 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
291 struct expression *condition)
292 {
293 struct expression *iter_var;
294 struct sm_state *sm;
295 struct smatch_state *estate;
296 sval_t start, end, max;
297
298 iter_var = iter_expr->unop;
299 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
300 if (!sm)
301 return NULL;
302 if (!estate_get_single_value(sm->state, &start))
303 return NULL;
304 if (get_implied_max(condition->right, &end))
305 end = sval_cast(get_type(iter_var), end);
306 else
307 end = sval_type_max(get_type(iter_var));
308
309 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
310 return NULL;
311
312 switch (condition->op) {
313 case SPECIAL_UNSIGNED_LT:
314 case SPECIAL_NOTEQUAL:
315 case '<':
316 if (!sval_is_min(end))
317 end.value--;
318 break;
319 case SPECIAL_UNSIGNED_LTE:
320 case SPECIAL_LTE:
321 break;
322 default:
323 return NULL;
324 }
325 if (sval_cmp(end, start) < 0)
326 return NULL;
327 estate = alloc_estate_range(start, end);
328 if (get_hard_max(condition->right, &max)) {
329 estate_set_hard_max(estate);
330 if (condition->op == '<' ||
331 condition->op == SPECIAL_UNSIGNED_LT ||
332 condition->op == SPECIAL_NOTEQUAL)
333 max.value--;
334 estate_set_fuzzy_max(estate, max);
335 }
336 set_extra_expr_mod(iter_var, estate);
337 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
338 }
339
340 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
341 struct expression *condition)
342 {
343 struct expression *iter_var;
344 struct sm_state *sm;
345 struct smatch_state *estate;
346 sval_t start, end;
347
348 iter_var = iter_expr->unop;
349 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
350 if (!sm)
351 return NULL;
352 if (!estate_get_single_value(sm->state, &start))
353 return NULL;
354 if (!get_implied_min(condition->right, &end))
355 end = sval_type_min(get_type(iter_var));
356 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
357 return NULL;
358
359 switch (condition->op) {
360 case SPECIAL_NOTEQUAL:
361 case '>':
362 if (!sval_is_min(end) && !sval_is_max(end))
363 end.value++;
364 break;
365 case SPECIAL_GTE:
366 break;
367 default:
368 return NULL;
369 }
370 if (sval_cmp(end, start) > 0)
371 return NULL;
372 estate = alloc_estate_range(end, start);
373 estate_set_hard_max(estate);
374 estate_set_fuzzy_max(estate, estate_get_fuzzy_max(estate));
375 set_extra_expr_mod(iter_var, estate);
376 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
377 }
378
379 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
380 {
381 struct expression *iter_expr;
382 struct expression *condition;
383
384 if (!loop->iterator_post_statement)
385 return NULL;
386 if (loop->iterator_post_statement->type != STMT_EXPRESSION)
387 return NULL;
388 iter_expr = loop->iterator_post_statement->expression;
389 if (!loop->iterator_pre_condition)
390 return NULL;
391 if (loop->iterator_pre_condition->type != EXPR_COMPARE)
392 return NULL;
393 condition = loop->iterator_pre_condition;
394
395 if (iter_expr->op == SPECIAL_INCREMENT)
396 return handle_canonical_for_inc(iter_expr, condition);
397 if (iter_expr->op == SPECIAL_DECREMENT)
398 return handle_canonical_for_dec(iter_expr, condition);
399 return NULL;
400 }
401
402 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct stree **stree)
403 {
404 struct sm_state *ret;
405
406 __push_fake_cur_stree();
407 if (!loop->iterator_post_statement)
408 ret = handle_canonical_while_count_down(loop);
409 else
410 ret = handle_canonical_for_loops(loop);
411 *stree = __pop_fake_cur_stree();
412 return ret;
413 }
414
415 int __iterator_unchanged(struct sm_state *sm)
416 {
417 if (!sm)
418 return 0;
419 if (get_sm_state(my_id, sm->name, sm->sym) == sm)
420 return 1;
421 return 0;
422 }
423
424 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
425 {
426 sval_t after_value;
427
428 /* paranoid checking. prolly not needed */
429 condition = strip_expr(condition);
430 if (!condition)
431 return;
432 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
433 return;
434 if (condition->op != SPECIAL_DECREMENT)
435 return;
436 after_value = estate_min(sm->state);
437 after_value.value--;
438 set_extra_mod(sm->name, sm->sym, alloc_estate_sval(after_value));
439 }
440
441 void __extra_pre_loop_hook_after(struct sm_state *sm,
442 struct statement *iterator,
443 struct expression *condition)
444 {
445 struct expression *iter_expr;
446 sval_t limit;
447 struct smatch_state *state;
448
449 if (!iterator) {
450 while_count_down_after(sm, condition);
451 return;
452 }
453
454 iter_expr = iterator->expression;
455
456 if (condition->type != EXPR_COMPARE)
457 return;
458 if (iter_expr->op == SPECIAL_INCREMENT) {
459 limit = sval_binop(estate_max(sm->state), '+',
460 sval_type_val(estate_type(sm->state), 1));
461 } else {
462 limit = sval_binop(estate_min(sm->state), '-',
463 sval_type_val(estate_type(sm->state), 1));
464 }
465 if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
466 if (iter_expr->op == SPECIAL_INCREMENT)
467 state = alloc_estate_range(estate_min(sm->state), limit);
468 else
469 state = alloc_estate_range(limit, estate_max(sm->state));
470 } else {
471 state = alloc_estate_sval(limit);
472 }
473 if (!estate_has_hard_max(sm->state)) {
474 estate_clear_hard_max(state);
475 }
476 if (estate_has_fuzzy_max(sm->state)) {
477 sval_t hmax = estate_get_fuzzy_max(sm->state);
478 sval_t max = estate_max(sm->state);
479
480 if (sval_cmp(hmax, max) != 0)
481 estate_clear_fuzzy_max(state);
482 } else if (!estate_has_fuzzy_max(sm->state)) {
483 estate_clear_fuzzy_max(state);
484 }
485
486 set_extra_mod(sm->name, sm->sym, state);
487 }
488
489 static struct stree *unmatched_stree;
490 static struct smatch_state *unmatched_state(struct sm_state *sm)
491 {
492 struct smatch_state *state;
493
494 if (unmatched_stree) {
495 state = get_state_stree(unmatched_stree, SMATCH_EXTRA, sm->name, sm->sym);
496 if (state)
497 return state;
498 }
499 if (parent_is_gone_var_sym(sm->name, sm->sym))
500 return alloc_estate_empty();
501 return alloc_estate_whole(estate_type(sm->state));
502 }
503
504 static void clear_the_pointed_at(struct expression *expr)
505 {
506 struct stree *stree;
507 char *name;
508 struct symbol *sym;
509 struct sm_state *tmp;
510
511 name = expr_to_var_sym(expr, &sym);
512 if (!name || !sym)
513 goto free;
514
515 stree = __get_cur_stree();
516 FOR_EACH_MY_SM(SMATCH_EXTRA, stree, tmp) {
517 if (tmp->name[0] != '*')
518 continue;
519 if (tmp->sym != sym)
520 continue;
521 if (strcmp(tmp->name + 1, name) != 0)
522 continue;
523 set_extra_mod(tmp->name, tmp->sym, alloc_estate_whole(estate_type(tmp->state)));
524 } END_FOR_EACH_SM(tmp);
525
526 free:
527 free_string(name);
528 }
529
530 static void match_function_call(struct expression *expr)
531 {
532 struct expression *arg;
533 struct expression *tmp;
534
535 /* if we have the db this is handled in smatch_function_hooks.c */
536 if (!option_no_db)
537 return;
538 if (inlinable(expr->fn))
539 return;
540
541 FOR_EACH_PTR(expr->args, arg) {
542 tmp = strip_expr(arg);
543 if (tmp->type == EXPR_PREOP && tmp->op == '&')
544 set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
545 else
546 clear_the_pointed_at(tmp);
547 } END_FOR_EACH_PTR(arg);
548 }
549
550 static int types_equiv_or_pointer(struct symbol *one, struct symbol *two)
551 {
552 if (!one || !two)
553 return 0;
554 if (one->type == SYM_PTR && two->type == SYM_PTR)
555 return 1;
556 return types_equiv(one, two);
557 }
558
559 static bool is_non_null_array(struct expression *expr)
560 {
561 struct symbol *type;
562 struct symbol *sym;
563 struct symbol *tmp;
564 char *name;
565 int i;
566
567 type = get_type(expr);
568 if (!type || type->type != SYM_ARRAY)
569 return 0;
570 if (expr->type == EXPR_SYMBOL)
571 return 1;
572 if (implied_not_equal(expr, 0))
573 return 1;
574
575 /* verify that it's not the first member of the struct */
576 if (expr->type != EXPR_DEREF || !expr->member)
577 return 0;
578 name = expr_to_var_sym(expr, &sym);
579 free_string(name);
580 if (!name || !sym)
581 return 0;
582 type = get_real_base_type(sym);
583 if (!type || type->type != SYM_PTR)
584 return 0;
585 type = get_real_base_type(type);
586 if (type->type != SYM_STRUCT)
587 return 0;
588
589 i = 0;
590 FOR_EACH_PTR(type->symbol_list, tmp) {
591 i++;
592 if (!tmp->ident)
593 continue;
594 if (strcmp(expr->member->name, tmp->ident->name) == 0) {
595 if (i == 1)
596 return 0;
597 return 1;
598 }
599 } END_FOR_EACH_PTR(tmp);
600
601 return 0;
602 }
603
604 static void match_vanilla_assign(struct expression *left, struct expression *right)
605 {
606 struct range_list *rl = NULL;
607 struct symbol *right_sym;
608 struct symbol *left_type;
609 struct symbol *right_type;
610 char *right_name = NULL;
611 struct symbol *sym;
612 char *name;
613 sval_t max;
614 struct smatch_state *state;
615
616 if (is_struct(left))
617 return;
618
619 name = expr_to_var_sym(left, &sym);
620 if (!name)
621 return;
622
623 left_type = get_type(left);
624 right_type = get_type(right);
625
626 right_name = expr_to_var_sym(right, &right_sym);
627
628 if (!(right->type == EXPR_PREOP && right->op == '&') &&
629 right_name && right_sym &&
630 types_equiv_or_pointer(left_type, right_type) &&
631 !has_symbol(right, sym)) {
632 set_equiv(left, right);
633 goto free;
634 }
635
636 if (is_non_null_array(right)) {
637 state = alloc_estate_range(array_min_sval, array_max_sval);
638 } else if (get_implied_rl(right, &rl)) {
639 rl = cast_rl(left_type, rl);
640 state = alloc_estate_rl(rl);
641 if (get_hard_max(right, &max)) {
642 estate_set_hard_max(state);
643 estate_set_fuzzy_max(state, max);
644 }
645 } else {
646 rl = alloc_whole_rl(right_type);
647 rl = cast_rl(left_type, rl);
648 state = alloc_estate_rl(rl);
649 }
650 set_extra_mod(name, sym, state);
651 free:
652 free_string(right_name);
653 }
654
655 static int op_remove_assign(int op)
656 {
657 switch (op) {
658 case SPECIAL_ADD_ASSIGN:
659 return '+';
660 case SPECIAL_SUB_ASSIGN:
661 return '-';
662 case SPECIAL_MUL_ASSIGN:
663 return '*';
664 case SPECIAL_DIV_ASSIGN:
665 return '/';
666 case SPECIAL_MOD_ASSIGN:
667 return '%';
668 case SPECIAL_AND_ASSIGN:
669 return '&';
670 case SPECIAL_OR_ASSIGN:
671 return '|';
672 case SPECIAL_XOR_ASSIGN:
673 return '^';
674 case SPECIAL_SHL_ASSIGN:
675 return SPECIAL_LEFTSHIFT;
676 case SPECIAL_SHR_ASSIGN:
677 return SPECIAL_RIGHTSHIFT;
678 default:
679 return op;
680 }
681 }
682
683 static void match_assign(struct expression *expr)
684 {
685 struct range_list *rl = NULL;
686 struct expression *left;
687 struct expression *right;
688 struct expression *binop_expr;
689 struct symbol *left_type;
690 struct symbol *right_type;
691 struct symbol *sym;
692 char *name;
693 sval_t left_min, left_max;
694 sval_t right_min, right_max;
695 sval_t res_min, res_max;
696
697 left = strip_expr(expr->left);
698
699 right = strip_expr(expr->right);
700 while (right->type == EXPR_ASSIGNMENT && right->op == '=')
701 right = strip_expr(right->left);
702
703 if (is_condition(expr->right))
704 return; /* handled in smatch_condition.c */
705 if (expr->op == '=' && right->type == EXPR_CALL)
706 return; /* handled in smatch_function_hooks.c */
707 if (expr->op == '=') {
708 match_vanilla_assign(left, right);
709 return;
710 }
711
712 name = expr_to_var_sym(left, &sym);
713 if (!name)
714 return;
715
716 left_type = get_type(left);
717 right_type = get_type(right);
718
719 res_min = sval_type_min(left_type);
720 res_max = sval_type_max(left_type);
721
722 switch (expr->op) {
723 case SPECIAL_ADD_ASSIGN:
724 get_absolute_max(left, &left_max);
725 get_absolute_max(right, &right_max);
726 if (sval_binop_overflows(left_max, '+', right_max))
727 break;
728 if (get_implied_min(left, &left_min) &&
729 !sval_is_negative_min(left_min) &&
730 get_implied_min(right, &right_min) &&
731 !sval_is_negative_min(right_min)) {
732 res_min = sval_binop(left_min, '+', right_min);
733 res_min = sval_cast(right_type, res_min);
734 }
735 if (inside_loop()) /* we are assuming loops don't lead to wrapping */
736 break;
737 res_max = sval_binop(left_max, '+', right_max);
738 res_max = sval_cast(right_type, res_max);
739 break;
740 case SPECIAL_SUB_ASSIGN:
741 if (get_implied_max(left, &left_max) &&
742 !sval_is_max(left_max) &&
743 get_implied_min(right, &right_min) &&
744 !sval_is_min(right_min)) {
745 res_max = sval_binop(left_max, '-', right_min);
746 res_max = sval_cast(right_type, res_max);
747 }
748 if (inside_loop())
749 break;
750 if (get_implied_min(left, &left_min) &&
751 !sval_is_min(left_min) &&
752 get_implied_max(right, &right_max) &&
753 !sval_is_max(right_max)) {
754 res_min = sval_binop(left_min, '-', right_max);
755 res_min = sval_cast(right_type, res_min);
756 }
757 break;
758 case SPECIAL_AND_ASSIGN:
759 case SPECIAL_MOD_ASSIGN:
760 case SPECIAL_SHL_ASSIGN:
761 case SPECIAL_SHR_ASSIGN:
762 case SPECIAL_OR_ASSIGN:
763 case SPECIAL_XOR_ASSIGN:
764 case SPECIAL_MUL_ASSIGN:
765 case SPECIAL_DIV_ASSIGN:
766 binop_expr = binop_expression(expr->left,
767 op_remove_assign(expr->op),
768 expr->right);
769 if (get_absolute_rl(binop_expr, &rl)) {
770 rl = cast_rl(left_type, rl);
771 set_extra_mod(name, sym, alloc_estate_rl(rl));
772 goto free;
773 }
774 break;
775 }
776 rl = cast_rl(left_type, alloc_rl(res_min, res_max));
777 set_extra_mod(name, sym, alloc_estate_rl(rl));
778 free:
779 free_string(name);
780 }
781
782 static struct smatch_state *increment_state(struct smatch_state *state)
783 {
784 sval_t min = estate_min(state);
785 sval_t max = estate_max(state);
786
787 if (!estate_rl(state))
788 return NULL;
789
790 if (inside_loop())
791 max = sval_type_max(max.type);
792
793 if (!sval_is_min(min) && !sval_is_max(min))
794 min.value++;
795 if (!sval_is_min(max) && !sval_is_max(max))
796 max.value++;
797 return alloc_estate_range(min, max);
798 }
799
800 static struct smatch_state *decrement_state(struct smatch_state *state)
801 {
802 sval_t min = estate_min(state);
803 sval_t max = estate_max(state);
804
805 if (!estate_rl(state))
806 return NULL;
807
808 if (inside_loop())
809 min = sval_type_min(min.type);
810
811 if (!sval_is_min(min) && !sval_is_max(min))
812 min.value--;
813 if (!sval_is_min(max) && !sval_is_max(max))
814 max.value--;
815 return alloc_estate_range(min, max);
816 }
817
818 static void unop_expr(struct expression *expr)
819 {
820 struct smatch_state *state;
821
822 if (expr->smatch_flags & Handled)
823 return;
824
825 switch (expr->op) {
826 case SPECIAL_INCREMENT:
827 state = get_state_expr(SMATCH_EXTRA, expr->unop);
828 state = increment_state(state);
829 if (!state)
830 state = alloc_estate_whole(get_type(expr));
831 set_extra_expr_mod(expr->unop, state);
832 break;
833 case SPECIAL_DECREMENT:
834 state = get_state_expr(SMATCH_EXTRA, expr->unop);
835 state = decrement_state(state);
836 if (!state)
837 state = alloc_estate_whole(get_type(expr));
838 set_extra_expr_mod(expr->unop, state);
839 break;
840 default:
841 return;
842 }
843 }
844
845 static void asm_expr(struct statement *stmt)
846 {
847
848 struct expression *expr;
849 struct symbol *type;
850 int state = 0;
851
852 FOR_EACH_PTR(stmt->asm_outputs, expr) {
853 switch (state) {
854 case 0: /* identifier */
855 case 1: /* constraint */
856 state++;
857 continue;
858 case 2: /* expression */
859 state = 0;
860 type = get_type(strip_expr(expr));
861 set_extra_expr_mod(expr, alloc_estate_whole(type));
862 continue;
863 }
864 } END_FOR_EACH_PTR(expr);
865 }
866
867 static void delete_state_tracker(struct tracker *t)
868 {
869 remove_from_equiv(t->name, t->sym);
870 delete_state(t->owner, t->name, t->sym);
871 }
872
873 static void scoped_state_extra(const char *name, struct symbol *sym)
874 {
875 struct tracker *t;
876
877 t = alloc_tracker(SMATCH_EXTRA, name, sym);
878 add_scope_hook((scope_hook *)&delete_state_tracker, t);
879 }
880
881 static void match_declarations(struct symbol *sym)
882 {
883 const char *name;
884
885 if (sym->ident) {
886 name = sym->ident->name;
887 if (!sym->initializer) {
888 set_state(SMATCH_EXTRA, name, sym, alloc_estate_whole(get_real_base_type(sym)));
889 scoped_state_extra(name, sym);
890 }
891 }
892 }
893
894 static void check_dereference(struct expression *expr)
895 {
896 if (outside_of_function())
897 return;
898 set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
899 }
900
901 static void match_dereferences(struct expression *expr)
902 {
903 if (expr->type != EXPR_PREOP)
904 return;
905 check_dereference(expr->unop);
906 }
907
908 static void match_pointer_as_array(struct expression *expr)
909 {
910 if (!is_array(expr))
911 return;
912 check_dereference(get_array_base(expr));
913 }
914
915 static void set_param_dereferenced(struct expression *arg, char *key, char *unused)
916 {
917 struct symbol *sym;
918 char *name;
919
920 name = get_variable_from_key(arg, key, &sym);
921 if (!name || !sym)
922 goto free;
923
924 set_extra_nomod(name, sym, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
925
926 free:
927 free_string(name);
928 }
929
930 static void match_function_def(struct symbol *sym)
931 {
932 struct symbol *arg;
933
934 FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
935 if (!arg->ident)
936 continue;
937 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
938 } END_FOR_EACH_PTR(arg);
939 }
940
941 static sval_t add_one(sval_t sval)
942 {
943 sval.value++;
944 return sval;
945 }
946
947 static sval_t sub_one(sval_t sval)
948 {
949 sval.value--;
950 return sval;
951 }
952
953 static void handle_comparison(struct symbol *type, struct expression *left, int op, struct expression *right)
954 {
955 struct range_list *left_orig;
956 struct range_list *left_true;
957 struct range_list *left_false;
958 struct range_list *right_orig;
959 struct range_list *right_true;
960 struct range_list *right_false;
961 struct smatch_state *left_true_state;
962 struct smatch_state *left_false_state;
963 struct smatch_state *right_true_state;
964 struct smatch_state *right_false_state;
965 sval_t min, max, dummy, hard_max;
966 int left_postop = 0;
967 int right_postop = 0;
968
969 if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
970 if (left->type == EXPR_POSTOP) {
971 left->smatch_flags |= Handled;
972 left_postop = left->op;
973 }
974 left = strip_expr(left->unop);
975 }
976 while (left->type == EXPR_ASSIGNMENT)
977 left = strip_expr(left->left);
978
979 if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
980 if (right->type == EXPR_POSTOP) {
981 right->smatch_flags |= Handled;
982 right_postop = right->op;
983 }
984 right = strip_expr(right->unop);
985 }
986
987 if (get_implied_rl(left, &left_orig)) {
988 left_orig = cast_rl(type, left_orig);
989 } else {
990 min = sval_type_min(get_type(left));
991 max = sval_type_max(get_type(left));
992 left_orig = cast_rl(type, alloc_rl(min, max));
993 }
994
995 if (get_implied_rl(right, &right_orig)) {
996 right_orig = cast_rl(type, right_orig);
997 } else {
998 min = sval_type_min(get_type(right));
999 max = sval_type_max(get_type(right));
1000 right_orig = cast_rl(type, alloc_rl(min, max));
1001 }
1002 min = sval_type_min(type);
1003 max = sval_type_max(type);
1004
1005 left_true = clone_rl(left_orig);
1006 left_false = clone_rl(left_orig);
1007 right_true = clone_rl(right_orig);
1008 right_false = clone_rl(right_orig);
1009
1010 switch (op) {
1011 case '<':
1012 case SPECIAL_UNSIGNED_LT:
1013 left_true = remove_range(left_orig, rl_max(right_orig), max);
1014 if (!sval_is_min(rl_min(right_orig))) {
1015 left_false = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
1016 }
1017
1018 right_true = remove_range(right_orig, min, rl_min(left_orig));
1019 if (!sval_is_max(rl_max(left_orig)))
1020 right_false = remove_range(right_orig, add_one(rl_max(left_orig)), max);
1021 break;
1022 case SPECIAL_UNSIGNED_LTE:
1023 case SPECIAL_LTE:
1024 if (!sval_is_max(rl_max(right_orig)))
1025 left_true = remove_range(left_orig, add_one(rl_max(right_orig)), max);
1026 left_false = remove_range(left_orig, min, rl_min(right_orig));
1027
1028 if (!sval_is_min(rl_min(left_orig)))
1029 right_true = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
1030 right_false = remove_range(right_orig, rl_max(left_orig), max);
1031
1032 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
1033 left_false = remove_range(left_false, rl_min(left_orig), rl_min(left_orig));
1034 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
1035 right_false = remove_range(right_false, rl_max(left_orig), rl_max(left_orig));
1036 break;
1037 case SPECIAL_EQUAL:
1038 if (!sval_is_max(rl_max(right_orig))) {
1039 left_true = remove_range(left_true, add_one(rl_max(right_orig)), max);
1040 }
1041 if (!sval_is_min(rl_min(right_orig))) {
1042 left_true = remove_range(left_true, min, sub_one(rl_min(right_orig)));
1043 }
1044 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
1045 left_false = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
1046
1047 if (!sval_is_max(rl_max(left_orig)))
1048 right_true = remove_range(right_true, add_one(rl_max(left_orig)), max);
1049 if (!sval_is_min(rl_min(left_orig)))
1050 right_true = remove_range(right_true, min, sub_one(rl_min(left_orig)));
1051 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
1052 right_false = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
1053 break;
1054 case SPECIAL_UNSIGNED_GTE:
1055 case SPECIAL_GTE:
1056 if (!sval_is_min(rl_min(right_orig)))
1057 left_true = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
1058 left_false = remove_range(left_orig, rl_max(right_orig), max);
1059
1060 if (!sval_is_max(rl_max(left_orig)))
1061 right_true = remove_range(right_orig, add_one(rl_max(left_orig)), max);
1062 right_false = remove_range(right_orig, min, rl_min(left_orig));
1063
1064 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
1065 right_false = remove_range(right_false, rl_min(left_orig), rl_min(left_orig));
1066 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
1067 left_false = remove_range(left_false, rl_max(left_orig), rl_max(left_orig));
1068 break;
1069 case '>':
1070 case SPECIAL_UNSIGNED_GT:
1071 left_true = remove_range(left_orig, min, rl_min(right_orig));
1072 if (!sval_is_max(rl_max(right_orig)))
1073 left_false = remove_range(left_orig, add_one(rl_max(right_orig)), max);
1074
1075 right_true = remove_range(right_orig, rl_max(left_orig), max);
1076 if (!sval_is_min(rl_min(left_orig)))
1077 right_false = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
1078 break;
1079 case SPECIAL_NOTEQUAL:
1080 if (!sval_is_max(rl_max(right_orig)))
1081 left_false = remove_range(left_false, add_one(rl_max(right_orig)), max);
1082 if (!sval_is_min(rl_min(right_orig)))
1083 left_false = remove_range(left_false, min, sub_one(rl_min(right_orig)));
1084 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
1085 left_true = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
1086
1087 if (!sval_is_max(rl_max(left_orig)))
1088 right_false = remove_range(right_false, add_one(rl_max(left_orig)), max);
1089 if (!sval_is_min(rl_min(left_orig)))
1090 right_false = remove_range(right_false, min, sub_one(rl_min(left_orig)));
1091 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
1092 right_true = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
1093 break;
1094 default:
1095 return;
1096 }
1097
1098 left_true = rl_truncate_cast(get_type(left), left_true);
1099 left_false = rl_truncate_cast(get_type(left), left_false);
1100 right_true = rl_truncate_cast(get_type(right), right_true);
1101 right_false = rl_truncate_cast(get_type(right), right_false);
1102
1103 left_true_state = alloc_estate_rl(left_true);
1104 left_false_state = alloc_estate_rl(left_false);
1105 right_true_state = alloc_estate_rl(right_true);
1106 right_false_state = alloc_estate_rl(right_false);
1107
1108 switch (op) {
1109 case '<':
1110 case SPECIAL_UNSIGNED_LT:
1111 case SPECIAL_UNSIGNED_LTE:
1112 case SPECIAL_LTE:
1113 if (get_hard_max(right, &dummy))
1114 estate_set_hard_max(left_true_state);
1115 if (get_hard_max(left, &dummy))
1116 estate_set_hard_max(right_false_state);
1117 break;
1118 case '>':
1119 case SPECIAL_UNSIGNED_GT:
1120 case SPECIAL_UNSIGNED_GTE:
1121 case SPECIAL_GTE:
1122 if (get_hard_max(left, &dummy))
1123 estate_set_hard_max(right_true_state);
1124 if (get_hard_max(right, &dummy))
1125 estate_set_hard_max(left_false_state);
1126 break;
1127 }
1128
1129 switch (op) {
1130 case '<':
1131 case SPECIAL_UNSIGNED_LT:
1132 case SPECIAL_UNSIGNED_LTE:
1133 case SPECIAL_LTE:
1134 if (get_hard_max(right, &hard_max)) {
1135 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1136 hard_max.value--;
1137 estate_set_fuzzy_max(left_true_state, hard_max);
1138 }
1139 if (get_implied_value(right, &hard_max)) {
1140 if (op == SPECIAL_UNSIGNED_LTE ||
1141 op == SPECIAL_LTE)
1142 hard_max.value++;
1143 estate_set_fuzzy_max(left_false_state, hard_max);
1144 }
1145 if (get_hard_max(left, &hard_max)) {
1146 if (op == SPECIAL_UNSIGNED_LTE ||
1147 op == SPECIAL_LTE)
1148 hard_max.value--;
1149 estate_set_fuzzy_max(right_false_state, hard_max);
1150 }
1151 if (get_implied_value(left, &hard_max)) {
1152 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1153 hard_max.value++;
1154 estate_set_fuzzy_max(right_true_state, hard_max);
1155 }
1156 break;
1157 case '>':
1158 case SPECIAL_UNSIGNED_GT:
1159 case SPECIAL_UNSIGNED_GTE:
1160 case SPECIAL_GTE:
1161 if (get_hard_max(left, &hard_max)) {
1162 if (op == '>' || op == SPECIAL_UNSIGNED_GT)
1163 hard_max.value--;
1164 estate_set_fuzzy_max(right_true_state, hard_max);
1165 }
1166 if (get_implied_value(left, &hard_max)) {
1167 if (op == SPECIAL_UNSIGNED_GTE ||
1168 op == SPECIAL_GTE)
1169 hard_max.value++;
1170 estate_set_fuzzy_max(right_false_state, hard_max);
1171 }
1172 if (get_hard_max(right, &hard_max)) {
1173 if (op == SPECIAL_UNSIGNED_LTE ||
1174 op == SPECIAL_LTE)
1175 hard_max.value--;
1176 estate_set_fuzzy_max(left_false_state, hard_max);
1177 }
1178 if (get_implied_value(right, &hard_max)) {
1179 if (op == '>' ||
1180 op == SPECIAL_UNSIGNED_GT)
1181 hard_max.value++;
1182 estate_set_fuzzy_max(left_true_state, hard_max);
1183 }
1184 break;
1185 case SPECIAL_EQUAL:
1186 if (get_hard_max(left, &hard_max))
1187 estate_set_fuzzy_max(right_true_state, hard_max);
1188 if (get_hard_max(right, &hard_max))
1189 estate_set_fuzzy_max(left_true_state, hard_max);
1190 break;
1191 }
1192
1193 if (get_hard_max(left, &hard_max)) {
1194 estate_set_hard_max(left_true_state);
1195 estate_set_hard_max(left_false_state);
1196 }
1197 if (get_hard_max(right, &hard_max)) {
1198 estate_set_hard_max(right_true_state);
1199 estate_set_hard_max(right_false_state);
1200 }
1201
1202 if (left_postop == SPECIAL_INCREMENT) {
1203 left_true_state = increment_state(left_true_state);
1204 left_false_state = increment_state(left_false_state);
1205 }
1206 if (left_postop == SPECIAL_DECREMENT) {
1207 left_true_state = decrement_state(left_true_state);
1208 left_false_state = decrement_state(left_false_state);
1209 }
1210 if (right_postop == SPECIAL_INCREMENT) {
1211 right_true_state = increment_state(right_true_state);
1212 right_false_state = increment_state(right_false_state);
1213 }
1214 if (right_postop == SPECIAL_DECREMENT) {
1215 right_true_state = decrement_state(right_true_state);
1216 right_false_state = decrement_state(right_false_state);
1217 }
1218
1219 set_extra_expr_true_false(left, left_true_state, left_false_state);
1220 set_extra_expr_true_false(right, right_true_state, right_false_state);
1221 }
1222
1223 static int opposite_op(int op)
1224 {
1225 switch (op) {
1226 case '+':
1227 return '-';
1228 case '-':
1229 return '+';
1230 case '*':
1231 return '/';
1232 }
1233 return 0;
1234 }
1235
1236 static int is_simple_math(struct expression *expr)
1237 {
1238 if (!expr)
1239 return 0;
1240 if (expr->type != EXPR_BINOP)
1241 return 0;
1242 if (!opposite_op(expr->op))
1243 return 0;
1244 return 1;
1245 }
1246
1247 static void move_known_values(struct expression **left_p, struct expression **right_p)
1248 {
1249 struct expression *left = *left_p;
1250 struct expression *right = *right_p;
1251 sval_t sval;
1252
1253 if (get_implied_value(left, &sval)) {
1254 if (!is_simple_math(right))
1255 return;
1256 if (right->op == '*') {
1257 sval_t divisor;
1258
1259 if (!get_value(right->right, &divisor))
1260 return;
1261 if (divisor.value == 0 && sval.value % divisor.value)
1262 return;
1263 *left_p = binop_expression(left, opposite_op(right->op), right->right);
1264 *right_p = right->left;
1265 return;
1266 }
1267 if (right->op == '+' && get_value(right->left, &sval)) {
1268 *left_p = binop_expression(left, opposite_op(right->op), right->left);
1269 *right_p = right->right;
1270 return;
1271 }
1272 if (get_value(right->right, &sval)) {
1273 *left_p = binop_expression(left, opposite_op(right->op), right->right);
1274 *right_p = right->left;
1275 return;
1276 }
1277 return;
1278 }
1279 if (get_implied_value(right, &sval)) {
1280 if (!is_simple_math(left))
1281 return;
1282 if (left->op == '*') {
1283 sval_t divisor;
1284
1285 if (!get_value(left->right, &divisor))
1286 return;
1287 if (divisor.value == 0 && sval.value % divisor.value)
1288 return;
1289 *right_p = binop_expression(right, opposite_op(left->op), left->right);
1290 *left_p = left->left;
1291 return;
1292 }
1293 if (left->op == '+' && get_value(left->left, &sval)) {
1294 *right_p = binop_expression(right, opposite_op(left->op), left->left);
1295 *left_p = left->right;
1296 return;
1297 }
1298
1299 if (get_value(left->right, &sval)) {
1300 *right_p = binop_expression(right, opposite_op(left->op), left->right);
1301 *left_p = left->left;
1302 return;
1303 }
1304 return;
1305 }
1306 }
1307
1308 static int match_func_comparison(struct expression *expr)
1309 {
1310 struct expression *left = strip_expr(expr->left);
1311 struct expression *right = strip_expr(expr->right);
1312 sval_t sval;
1313
1314 /*
1315 * fixme: think about this harder. We should always be trying to limit
1316 * the non-call side as well. If we can't determine the limitter does
1317 * that mean we aren't querying the database and are missing important
1318 * information?
1319 */
1320
1321 if (left->type == EXPR_CALL) {
1322 if (get_implied_value(left, &sval)) {
1323 handle_comparison(get_type(expr), left, expr->op, right);
1324 return 1;
1325 }
1326 function_comparison(left, expr->op, right);
1327 return 1;
1328 }
1329
1330 if (right->type == EXPR_CALL) {
1331 if (get_implied_value(right, &sval)) {
1332 handle_comparison(get_type(expr), left, expr->op, right);
1333 return 1;
1334 }
1335 function_comparison(left, expr->op, right);
1336 return 1;
1337 }
1338
1339 return 0;
1340 }
1341
1342 static void match_comparison(struct expression *expr)
1343 {
1344 struct expression *left_orig = strip_expr(expr->left);
1345 struct expression *right_orig = strip_expr(expr->right);
1346 struct expression *left, *right;
1347 struct expression *prev;
1348 struct symbol *type;
1349
1350 if (match_func_comparison(expr))
1351 return;
1352
1353 type = get_type(expr);
1354 if (!type)
1355 type = &llong_ctype;
1356
1357 left = left_orig;
1358 right = right_orig;
1359 move_known_values(&left, &right);
1360 handle_comparison(type, left, expr->op, right);
1361
1362 prev = get_assigned_expr(left_orig);
1363 if (is_simple_math(prev) && has_variable(prev, left_orig) == 0) {
1364 left = prev;
1365 right = right_orig;
1366 move_known_values(&left, &right);
1367 handle_comparison(type, left, expr->op, right);
1368 }
1369
1370 prev = get_assigned_expr(right_orig);
1371 if (is_simple_math(prev) && has_variable(prev, right_orig) == 0) {
1372 left = left_orig;
1373 right = prev;
1374 move_known_values(&left, &right);
1375 handle_comparison(type, left, expr->op, right);
1376 }
1377 }
1378
1379 static void handle_AND_condition(struct expression *expr)
1380 {
1381 struct range_list *rl = NULL;
1382 sval_t known;
1383
1384 if (get_implied_value(expr->left, &known) && known.value > 0) {
1385 known.value--;
1386 get_absolute_rl(expr->right, &rl);
1387 rl = remove_range(rl, sval_type_val(known.type, 0), known);
1388 set_extra_expr_true_false(expr->right, alloc_estate_rl(rl), NULL);
1389 return;
1390 }
1391
1392 if (get_implied_value(expr->right, &known) && known.value > 0) {
1393 known.value--;
1394 get_absolute_rl(expr->left, &rl);
1395 rl = remove_range(rl, sval_type_val(known.type, 0), known);
1396 set_extra_expr_true_false(expr->left, alloc_estate_rl(rl), NULL);
1397 return;
1398 }
1399 }
1400
1401 /* this is actually hooked from smatch_implied.c... it's hacky, yes */
1402 void __extra_match_condition(struct expression *expr)
1403 {
1404 struct symbol *sym;
1405 char *name;
1406 struct smatch_state *pre_state;
1407 struct smatch_state *true_state;
1408 struct smatch_state *false_state;
1409
1410 expr = strip_expr(expr);
1411 switch (expr->type) {
1412 case EXPR_CALL:
1413 function_comparison(expr, SPECIAL_NOTEQUAL, zero_expr());
1414 return;
1415 case EXPR_PREOP:
1416 case EXPR_SYMBOL:
1417 case EXPR_DEREF: {
1418 sval_t zero;
1419
1420 zero = sval_blank(expr);
1421 zero.value = 0;
1422
1423 name = expr_to_var_sym(expr, &sym);
1424 if (!name)
1425 return;
1426 pre_state = get_state(my_id, name, sym);
1427 true_state = estate_filter_sval(pre_state, zero);
1428 if (possibly_true(expr, SPECIAL_EQUAL, zero_expr()))
1429 false_state = alloc_estate_sval(zero);
1430 else
1431 false_state = alloc_estate_empty();
1432 set_extra_true_false(name, sym, true_state, false_state);
1433 free_string(name);
1434 return;
1435 }
1436 case EXPR_COMPARE:
1437 match_comparison(expr);
1438 return;
1439 case EXPR_ASSIGNMENT:
1440 __extra_match_condition(expr->left);
1441 return;
1442 case EXPR_BINOP:
1443 if (expr->op == '&')
1444 handle_AND_condition(expr);
1445 return;
1446 }
1447 }
1448
1449 static void assume_indexes_are_valid(struct expression *expr)
1450 {
1451 struct expression *array_expr;
1452 int array_size;
1453 struct expression *offset;
1454 struct symbol *offset_type;
1455 struct range_list *rl_before;
1456 struct range_list *rl_after;
1457 struct range_list *filter = NULL;
1458 sval_t size;
1459
1460 expr = strip_expr(expr);
1461 if (!is_array(expr))
1462 return;
1463
1464 offset = get_array_offset(expr);
1465 offset_type = get_type(offset);
1466 if (offset_type && type_signed(offset_type)) {
1467 filter = alloc_rl(sval_type_min(offset_type),
1468 sval_type_val(offset_type, -1));
1469 }
1470
1471 array_expr = get_array_base(expr);
1472 array_size = get_real_array_size(array_expr);
1473 if (array_size > 1) {
1474 size = sval_type_val(offset_type, array_size);
1475 add_range(&filter, size, sval_type_max(offset_type));
1476 }
1477
1478 if (!filter)
1479 return;
1480 get_absolute_rl(offset, &rl_before);
1481 rl_after = rl_filter(rl_before, filter);
1482 if (rl_equiv(rl_before, rl_after))
1483 return;
1484 set_extra_expr_nomod(offset, alloc_estate_rl(rl_after));
1485 }
1486
1487 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
1488 int implied_not_equal(struct expression *expr, long long val)
1489 {
1490 return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
1491 }
1492
1493 int implied_not_equal_name_sym(char *name, struct symbol *sym, long long val)
1494 {
1495 struct smatch_state *estate;
1496
1497 estate = get_state(SMATCH_EXTRA, name, sym);
1498 if (!estate)
1499 return 0;
1500 if (!rl_has_sval(estate_rl(estate), sval_type_val(estate_type(estate), 0)))
1501 return 1;
1502 return 0;
1503 }
1504
1505 int parent_is_null_var_sym(const char *name, struct symbol *sym)
1506 {
1507 char buf[256];
1508 char *start;
1509 char *end;
1510 struct smatch_state *state;
1511
1512 strncpy(buf, name, sizeof(buf) - 1);
1513 buf[sizeof(buf) - 1] = '\0';
1514
1515 start = &buf[0];
1516 while (*start == '*') {
1517 start++;
1518 state = get_state(SMATCH_EXTRA, start, sym);
1519 if (!state)
1520 continue;
1521 if (!estate_rl(state))
1522 return 1;
1523 if (estate_min(state).value == 0 &&
1524 estate_max(state).value == 0)
1525 return 1;
1526 }
1527
1528 start = &buf[0];
1529 while (*start == '&')
1530 start++;
1531
1532 while ((end = strrchr(start, '-'))) {
1533 *end = '\0';
1534 state = get_state(SMATCH_EXTRA, start, sym);
1535 if (!state)
1536 continue;
1537 if (estate_min(state).value == 0 &&
1538 estate_max(state).value == 0)
1539 return 1;
1540 }
1541 return 0;
1542 }
1543
1544 int parent_is_null(struct expression *expr)
1545 {
1546 struct symbol *sym;
1547 char *var;
1548 int ret = 0;
1549
1550 expr = strip_expr(expr);
1551 var = expr_to_var_sym(expr, &sym);
1552 if (!var || !sym)
1553 goto free;
1554 ret = parent_is_null_var_sym(var, sym);
1555 free:
1556 free_string(var);
1557 return ret;
1558 }
1559
1560 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
1561 {
1562 if (estate_is_whole(sm->state))
1563 return;
1564 sql_insert_caller_info(call, PARAM_VALUE, param, printed_name, sm->state->name);
1565 if (estate_has_fuzzy_max(sm->state))
1566 sql_insert_caller_info(call, FUZZY_MAX, param, printed_name,
1567 sval_to_str(estate_get_fuzzy_max(sm->state)));
1568 }
1569
1570 static void db_limited_before(void)
1571 {
1572 unmatched_stree = clone_stree(__get_cur_stree());
1573 }
1574
1575 static void db_limited_after(void)
1576 {
1577 free_stree(&unmatched_stree);
1578 }
1579
1580 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value)
1581 {
1582 struct expression *arg;
1583 char *name;
1584 struct symbol *sym;
1585 struct sm_state *sm;
1586 struct symbol *compare_type, *var_type;
1587 struct range_list *rl;
1588 struct range_list *limit;
1589 struct range_list *new;
1590
1591 while (expr->type == EXPR_ASSIGNMENT)
1592 expr = strip_expr(expr->right);
1593 if (expr->type != EXPR_CALL)
1594 return;
1595
1596 arg = get_argument_from_call_expr(expr->args, param);
1597 if (!arg)
1598 return;
1599
1600 name = get_variable_from_key(arg, key, &sym);
1601 if (!name || !sym)
1602 goto free;
1603
1604 if (strcmp(key, "$") == 0)
1605 compare_type = get_arg_type(expr->fn, param);
1606 else
1607 compare_type = get_member_type_from_key(arg, key);
1608
1609 sm = get_sm_state(SMATCH_EXTRA, name, sym);
1610 if (sm)
1611 rl = estate_rl(sm->state);
1612 else
1613 rl = alloc_whole_rl(compare_type);
1614
1615 call_results_to_rl(expr, compare_type, value, &limit);
1616 new = rl_intersection(rl, limit);
1617
1618 var_type = get_member_type_from_key(arg, key);
1619 new = cast_rl(var_type, new);
1620
1621 /* We want to preserve the implications here */
1622 if (sm && rl_equiv(estate_rl(sm->state), new))
1623 __set_sm(sm);
1624 else
1625 set_extra_nomod(name, sym, alloc_estate_rl(new));
1626
1627 free:
1628 free_string(name);
1629 }
1630
1631 static void db_param_add(struct expression *expr, int param, char *key, char *value)
1632 {
1633 struct expression *arg;
1634 char *name;
1635 struct symbol *sym;
1636 struct symbol *type;
1637 struct smatch_state *state;
1638 struct range_list *added = NULL;
1639 struct range_list *new;
1640
1641 while (expr->type == EXPR_ASSIGNMENT)
1642 expr = strip_expr(expr->right);
1643 if (expr->type != EXPR_CALL)
1644 return;
1645
1646 arg = get_argument_from_call_expr(expr->args, param);
1647 if (!arg)
1648 return;
1649 name = get_variable_from_key(arg, key, &sym);
1650 if (!name || !sym)
1651 goto free;
1652
1653 type = get_member_type_from_key(arg, key);
1654 state = get_state(SMATCH_EXTRA, name, sym);
1655 if (state) {
1656 call_results_to_rl(expr, type, value, &added);
1657 new = rl_union(estate_rl(state), added);
1658 } else {
1659 new = alloc_whole_rl(type);
1660 }
1661
1662 set_extra_mod(name, sym, alloc_estate_rl(new));
1663 free:
1664 free_string(name);
1665 }
1666
1667 static void db_returned_member_info(struct expression *expr, int param, char *key, char *value)
1668 {
1669 struct symbol *type;
1670 struct symbol *sym;
1671 char *name;
1672 struct range_list *rl;
1673
1674 if (expr->type != EXPR_ASSIGNMENT)
1675 return;
1676
1677 name = return_state_to_var_sym(expr, param, key, &sym);
1678 if (!name || !sym)
1679 goto free;
1680 type = get_member_type_from_key(expr->left, key);
1681 if (!type)
1682 return;
1683 call_results_to_rl(expr->right, type, value, &rl);
1684 set_extra_mod(name, sym, alloc_estate_rl(rl));
1685
1686 free:
1687 free_string(name);
1688 }
1689
1690 static char *in_terms_of_param_math(struct expression *expr, char *printed_name)
1691 {
1692 struct symbol *sym;
1693 char *var;
1694 char buf[256];
1695 char *ret = NULL;
1696
1697 var = expr_to_var_sym(expr, &sym);
1698 if (!var || !sym)
1699 goto free;
1700 snprintf(buf, sizeof(buf), "%s%s", var, printed_name + 2);
1701
1702 ret = get_value_in_terms_of_parameter_math_var_sym(buf, sym);
1703
1704 free:
1705 free_string(var);
1706 return ret;
1707 }
1708
1709 static void returned_member_callback(int return_id, char *return_ranges, struct expression *expr, char *printed_name, struct smatch_state *state)
1710 {
1711 char buf[256];
1712 char *math_str;
1713 sval_t sval;
1714
1715 /* these are handled in smatch_param_filter/set/limit.c */
1716 if (printed_name[0] != '*' &&
1717 !strchr(printed_name, '.') && !strchr(printed_name, '-'))
1718 return;
1719
1720 if (estate_get_single_value(state, &sval)) {
1721 sql_insert_return_states(return_id, return_ranges, RETURN_VALUE, -1,
1722 printed_name, sval_to_str(sval));
1723 return;
1724 }
1725
1726 math_str = in_terms_of_param_math(expr, printed_name);
1727 if (math_str) {
1728 snprintf(buf, sizeof(buf), "%s[%s]", state->name, math_str);
1729 sql_insert_return_states(return_id, return_ranges, RETURN_VALUE, -1,
1730 printed_name, buf);
1731 return;
1732 }
1733
1734 if (estate_is_whole(state))
1735 return;
1736
1737 sql_insert_return_states(return_id, return_ranges, RETURN_VALUE, -1,
1738 printed_name, state->name);
1739 }
1740
1741 static void match_call_info(struct expression *expr)
1742 {
1743 struct smatch_state *state;
1744 struct range_list *rl = NULL;
1745 struct expression *arg;
1746 struct symbol *type;
1747 int i = 0;
1748
1749 FOR_EACH_PTR(expr->args, arg) {
1750 type = get_arg_type(expr->fn, i);
1751
1752 if (get_implied_rl(arg, &rl))
1753 rl = cast_rl(type, rl);
1754 else
1755 rl = cast_rl(type, alloc_whole_rl(get_type(arg)));
1756
1757 if (!is_whole_rl(rl))
1758 sql_insert_caller_info(expr, PARAM_VALUE, i, "$", show_rl(rl));
1759 state = get_state_expr(SMATCH_EXTRA, arg);
1760 if (estate_has_fuzzy_max(state)) {
1761 sql_insert_caller_info(expr, FUZZY_MAX, i, "$",
1762 sval_to_str(estate_get_fuzzy_max(state)));
1763 }
1764 i++;
1765 } END_FOR_EACH_PTR(arg);
1766 }
1767
1768 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
1769 {
1770 struct range_list *rl = NULL;
1771 struct smatch_state *state;
1772 struct symbol *type;
1773 char fullname[256];
1774
1775 if (strcmp(key, "*$") == 0)
1776 snprintf(fullname, sizeof(fullname), "*%s", name);
1777 else if (strncmp(key, "$", 1) == 0)
1778 snprintf(fullname, 256, "%s%s", name, key + 1);
1779 else
1780 return;
1781
1782 type = get_member_type_from_key(symbol_expression(sym), key);
1783 str_to_rl(type, value, &rl);
1784 state = alloc_estate_rl(rl);
1785 set_state(SMATCH_EXTRA, fullname, sym, state);
1786 }
1787
1788 static void set_param_hard_max(const char *name, struct symbol *sym, char *key, char *value)
1789 {
1790 struct range_list *rl = NULL;
1791 struct smatch_state *state;
1792 struct symbol *type;
1793 char fullname[256];
1794 sval_t max;
1795
1796 if (strcmp(key, "*$") == 0)
1797 snprintf(fullname, sizeof(fullname), "*%s", name);
1798 else if (strncmp(key, "$", 1) == 0)
1799 snprintf(fullname, 256, "%s%s", name, key + 1);
1800 else
1801 return;
1802
1803 state = get_state(SMATCH_EXTRA, fullname, sym);
1804 if (!state)
1805 return;
1806 type = get_member_type_from_key(symbol_expression(sym), key);
1807 str_to_rl(type, value, &rl);
1808 if (!rl_to_sval(rl, &max))
1809 return;
1810 estate_set_fuzzy_max(state, max);
1811 }
1812
1813 void register_smatch_extra(int id)
1814 {
1815 my_id = id;
1816
1817 add_merge_hook(my_id, &merge_estates);
1818 add_unmatched_state_hook(my_id, &unmatched_state);
1819 add_hook(&match_function_def, FUNC_DEF_HOOK);
1820 add_hook(&match_declarations, DECLARATION_HOOK);
1821 select_caller_info_hook(set_param_value, PARAM_VALUE);
1822 select_caller_info_hook(set_param_hard_max, FUZZY_MAX);
1823 select_return_states_hook(RETURN_VALUE, &db_returned_member_info);
1824 select_return_states_before(&db_limited_before);
1825 select_return_states_hook(LIMITED_VALUE, &db_param_limit_filter);
1826 select_return_states_hook(FILTER_VALUE, &db_param_limit_filter);
1827 select_return_states_hook(ADDED_VALUE, &db_param_add);
1828 select_return_states_after(&db_limited_after);
1829 }
1830
1831 void register_smatch_extra_late(int id)
1832 {
1833 add_hook(&match_dereferences, DEREF_HOOK);
1834 add_hook(&match_pointer_as_array, OP_HOOK);
1835 select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);
1836 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
1837 add_hook(&match_assign, ASSIGNMENT_HOOK);
1838 add_hook(&match_assign, GLOBAL_ASSIGNMENT_HOOK);
1839 add_hook(&unop_expr, OP_HOOK);
1840 add_hook(&asm_expr, ASM_HOOK);
1841
1842 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1843 add_member_info_callback(my_id, struct_member_callback);
1844 add_returned_member_callback(my_id, returned_member_callback);
1845
1846 add_hook(&assume_indexes_are_valid, OP_HOOK);
1847 }
Static analysis for C