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check_overflow: silence some "not allocating enough data" false positives
[smatch.git] / smatch_extra.c
blob974d153182c8174b7abff192e420fbb1ea6829d6
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_cast(get_type(iter_var), end);
231 else
232 end = sval_type_max(get_type(iter_var));
233
234 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
235 return NULL;
236
237 switch (condition->op) {
238 case SPECIAL_NOTEQUAL:
239 case '<':
240 if (!sval_is_min(end))
241 end.value--;
242 break;
243 case SPECIAL_LTE:
244 break;
245 default:
246 return NULL;
247 }
248 if (sval_cmp(end, start) < 0)
249 return NULL;
250 estate = alloc_estate_range(start, end);
251 if (get_hard_max(condition->right, &dummy))
252 estate_set_hard_max(estate);
253 set_extra_expr_mod(iter_var, estate);
254 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
255 }
256
257 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
258 struct expression *condition)
259 {
260 struct expression *iter_var;
261 struct sm_state *sm;
262 struct smatch_state *estate;
263 sval_t start, end;
264
265 iter_var = iter_expr->unop;
266 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
267 if (!sm)
268 return NULL;
269 if (!estate_get_single_value(sm->state, &start))
270 return NULL;
271 if (!get_implied_min(condition->right, &end))
272 end = sval_type_min(get_type(iter_var));
273 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
274 return NULL;
275
276 switch (condition->op) {
277 case SPECIAL_NOTEQUAL:
278 case '>':
279 if (!sval_is_min(end) && !sval_is_max(end))
280 end.value++;
281 break;
282 case SPECIAL_GTE:
283 break;
284 default:
285 return NULL;
286 }
287 if (sval_cmp(end, start) > 0)
288 return NULL;
289 estate = alloc_estate_range(end, start);
290 estate_set_hard_max(estate);
291 set_extra_expr_mod(iter_var, estate);
292 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
293 }
294
295 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
296 {
297 struct expression *iter_expr;
298 struct expression *condition;
299
300 if (!loop->iterator_post_statement)
301 return NULL;
302 if (loop->iterator_post_statement->type != STMT_EXPRESSION)
303 return NULL;
304 iter_expr = loop->iterator_post_statement->expression;
305 if (!loop->iterator_pre_condition)
306 return NULL;
307 if (loop->iterator_pre_condition->type != EXPR_COMPARE)
308 return NULL;
309 condition = loop->iterator_pre_condition;
310
311 if (iter_expr->op == SPECIAL_INCREMENT)
312 return handle_canonical_for_inc(iter_expr, condition);
313 if (iter_expr->op == SPECIAL_DECREMENT)
314 return handle_canonical_for_dec(iter_expr, condition);
315 return NULL;
316 }
317
318 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct state_list **slist)
319 {
320 struct sm_state *ret;
321
322 __push_fake_cur_slist();
323 if (!loop->iterator_post_statement)
324 ret = handle_canonical_while_count_down(loop);
325 else
326 ret = handle_canonical_for_loops(loop);
327 *slist = __pop_fake_cur_slist();
328 return ret;
329 }
330
331 int __iterator_unchanged(struct sm_state *sm)
332 {
333 if (!sm)
334 return 0;
335 if (get_sm_state(my_id, sm->name, sm->sym) == sm)
336 return 1;
337 return 0;
338 }
339
340 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
341 {
342 sval_t after_value;
343
344 /* paranoid checking. prolly not needed */
345 condition = strip_expr(condition);
346 if (!condition)
347 return;
348 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
349 return;
350 if (condition->op != SPECIAL_DECREMENT)
351 return;
352 after_value = estate_min(sm->state);
353 after_value.value--;
354 set_extra_mod(sm->name, sm->sym, alloc_estate_sval(after_value));
355 }
356
357 void __extra_pre_loop_hook_after(struct sm_state *sm,
358 struct statement *iterator,
359 struct expression *condition)
360 {
361 struct expression *iter_expr;
362 sval_t limit;
363 struct smatch_state *state;
364
365 if (!iterator) {
366 while_count_down_after(sm, condition);
367 return;
368 }
369
370 iter_expr = iterator->expression;
371
372 if (condition->type != EXPR_COMPARE)
373 return;
374 if (iter_expr->op == SPECIAL_INCREMENT) {
375 limit = sval_binop(estate_max(sm->state), '+',
376 sval_type_val(estate_type(sm->state), 1));
377 } else {
378 limit = sval_binop(estate_min(sm->state), '-',
379 sval_type_val(estate_type(sm->state), 1));
380 }
381 if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
382 if (iter_expr->op == SPECIAL_INCREMENT)
383 state = alloc_estate_range(estate_min(sm->state), limit);
384 else
385 state = alloc_estate_range(limit, estate_max(sm->state));
386 } else {
387 state = alloc_estate_sval(limit);
388 }
389 if (!estate_has_hard_max(sm->state))
390 estate_clear_hard_max(state);
391 set_extra_mod(sm->name, sm->sym, state);
392 }
393
394 static struct state_list *unmatched_slist;
395 static struct smatch_state *unmatched_state(struct sm_state *sm)
396 {
397 struct smatch_state *state;
398
399 if (unmatched_slist) {
400 state = get_state_slist(unmatched_slist, SMATCH_EXTRA, sm->name, sm->sym);
401 if (state)
402 return state;
403 }
404 return alloc_estate_whole(estate_type(sm->state));
405 }
406
407 static void clear_the_pointed_at(struct expression *expr, struct state_list *slist)
408 {
409 char *name;
410 struct symbol *sym;
411 struct sm_state *tmp;
412
413 name = expr_to_var_sym(expr, &sym);
414 if (!name || !sym)
415 goto free;
416
417 FOR_EACH_PTR(slist, tmp) {
418 if (tmp->name[0] != '*')
419 continue;
420 if (tmp->sym != sym)
421 continue;
422 if (strcmp(tmp->name + 1, name) != 0)
423 continue;
424 set_extra_mod(tmp->name, tmp->sym, alloc_estate_whole(estate_type(tmp->state)));
425 } END_FOR_EACH_PTR(tmp);
426
427 free:
428 free_string(name);
429 }
430
431 static void match_function_call(struct expression *expr)
432 {
433 struct expression *arg;
434 struct expression *tmp;
435 struct state_list *slist;
436
437 /* if we have the db this is handled in smatch_function_hooks.c */
438 if (!option_no_db)
439 return;
440 if (inlinable(expr->fn))
441 return;
442
443 slist = get_all_states(SMATCH_EXTRA);
444
445 FOR_EACH_PTR(expr->args, arg) {
446 tmp = strip_expr(arg);
447 if (tmp->type == EXPR_PREOP && tmp->op == '&')
448 set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
449 else
450 clear_the_pointed_at(tmp, slist);
451 } END_FOR_EACH_PTR(arg);
452
453 free_slist(&slist);
454 }
455
456 static int types_equiv_or_pointer(struct symbol *one, struct symbol *two)
457 {
458 if (!one || !two)
459 return 0;
460 if (one->type == SYM_PTR && two->type == SYM_PTR)
461 return 1;
462 return types_equiv(one, two);
463 }
464
465 static void match_vanilla_assign(struct expression *left, struct expression *right)
466 {
467 struct range_list *rl = NULL;
468 struct symbol *right_sym;
469 struct symbol *left_type;
470 struct symbol *right_type;
471 char *right_name = NULL;
472 struct symbol *sym;
473 char *name;
474 sval_t tmp;
475 struct smatch_state *state;
476
477 name = expr_to_var_sym(left, &sym);
478 if (!name)
479 return;
480
481 left_type = get_type(left);
482 right_type = get_type(right);
483
484 right_name = expr_to_var_sym(right, &right_sym);
485 if (right_name && right_sym &&
486 types_equiv_or_pointer(left_type, right_type)) {
487 set_equiv(left, right);
488 goto free;
489 }
490
491 if (get_implied_rl(right, &rl)) {
492 rl = cast_rl(left_type, rl);
493 state = alloc_estate_rl(rl);
494 if (get_hard_max(right, &tmp))
495 estate_set_hard_max(state);
496 } else {
497 rl = alloc_whole_rl(right_type);
498 rl = cast_rl(left_type, rl);
499 state = alloc_estate_rl(rl);
500 }
501 set_extra_mod(name, sym, state);
502 free:
503 free_string(right_name);
504 }
505
506 static int op_remove_assign(int op)
507 {
508 switch (op) {
509 case SPECIAL_ADD_ASSIGN:
510 return '+';
511 case SPECIAL_SUB_ASSIGN:
512 return '-';
513 case SPECIAL_MUL_ASSIGN:
514 return '*';
515 case SPECIAL_DIV_ASSIGN:
516 return '/';
517 case SPECIAL_MOD_ASSIGN:
518 return '%';
519 case SPECIAL_AND_ASSIGN:
520 return '&';
521 case SPECIAL_OR_ASSIGN:
522 return '|';
523 case SPECIAL_XOR_ASSIGN:
524 return '^';
525 case SPECIAL_SHL_ASSIGN:
526 return SPECIAL_LEFTSHIFT;
527 case SPECIAL_SHR_ASSIGN:
528 return SPECIAL_RIGHTSHIFT;
529 default:
530 return op;
531 }
532 }
533
534 static void match_assign(struct expression *expr)
535 {
536 struct range_list *rl = NULL;
537 struct expression *left;
538 struct expression *right;
539 struct expression *binop_expr;
540 struct symbol *left_type;
541 struct symbol *right_type;
542 struct symbol *sym;
543 char *name;
544 sval_t left_min, left_max;
545 sval_t right_min, right_max;
546 sval_t res_min, res_max;
547
548 left = strip_expr(expr->left);
549
550 right = strip_expr(expr->right);
551 while (right->type == EXPR_ASSIGNMENT && right->op == '=')
552 right = strip_expr(right->left);
553
554 if (is_condition(expr->right))
555 return; /* handled in smatch_condition.c */
556 if (expr->op == '=' && right->type == EXPR_CALL)
557 return; /* handled in smatch_function_hooks.c */
558 if (expr->op == '=') {
559 match_vanilla_assign(left, right);
560 return;
561 }
562
563 name = expr_to_var_sym(left, &sym);
564 if (!name)
565 return;
566
567 left_type = get_type(left);
568 right_type = get_type(right);
569
570 res_min = sval_type_min(right_type);
571 res_max = sval_type_max(right_type);
572
573 switch (expr->op) {
574 case SPECIAL_ADD_ASSIGN:
575 get_absolute_max(left, &left_max);
576 get_absolute_max(right, &right_max);
577 if (sval_binop_overflows(left_max, '+', right_max))
578 break;
579 if (get_implied_min(left, &left_min) &&
580 !sval_is_negative_min(left_min) &&
581 get_implied_min(right, &right_min) &&
582 !sval_is_negative_min(right_min)) {
583 res_min = sval_binop(left_min, '+', right_min);
584 res_min = sval_cast(right_type, res_min);
585 }
586 if (inside_loop()) /* we are assuming loops don't lead to wrapping */
587 break;
588 res_max = sval_binop(left_max, '+', right_max);
589 res_max = sval_cast(right_type, res_max);
590 break;
591 case SPECIAL_SUB_ASSIGN:
592 if (get_implied_max(left, &left_max) &&
593 !sval_is_max(left_max) &&
594 get_implied_min(right, &right_min) &&
595 !sval_is_min(right_min)) {
596 res_max = sval_binop(left_max, '-', right_min);
597 res_max = sval_cast(right_type, res_max);
598 }
599 if (inside_loop())
600 break;
601 if (get_implied_min(left, &left_min) &&
602 !sval_is_min(left_min) &&
603 get_implied_max(right, &right_max) &&
604 !sval_is_max(right_max)) {
605 res_min = sval_binop(left_min, '-', right_max);
606 res_min = sval_cast(right_type, res_min);
607 }
608 break;
609 case SPECIAL_AND_ASSIGN:
610 case SPECIAL_MOD_ASSIGN:
611 binop_expr = binop_expression(expr->left,
612 op_remove_assign(expr->op),
613 expr->right);
614 if (get_implied_rl(binop_expr, &rl)) {
615 rl = cast_rl(left_type, rl);
616 set_extra_mod(name, sym, alloc_estate_rl(rl));
617 goto free;
618 }
619 }
620 rl = cast_rl(left_type, alloc_rl(res_min, res_max));
621 set_extra_mod(name, sym, alloc_estate_rl(rl));
622 free:
623 free_string(name);
624 }
625
626 static struct smatch_state *increment_state(struct smatch_state *state)
627 {
628 sval_t min = estate_min(state);
629 sval_t max = estate_max(state);
630
631 if (!estate_rl(state))
632 return NULL;
633
634 if (inside_loop())
635 max = sval_type_max(max.type);
636
637 if (!sval_is_min(min) && !sval_is_max(min))
638 min.value++;
639 if (!sval_is_min(max) && !sval_is_max(max))
640 max.value++;
641 return alloc_estate_range(min, max);
642 }
643
644 static struct smatch_state *decrement_state(struct smatch_state *state)
645 {
646 sval_t min = estate_min(state);
647 sval_t max = estate_max(state);
648
649 if (!estate_rl(state))
650 return NULL;
651
652 if (inside_loop())
653 min = sval_type_min(min.type);
654
655 if (!sval_is_min(min) && !sval_is_max(min))
656 min.value--;
657 if (!sval_is_min(max) && !sval_is_max(max))
658 max.value--;
659 return alloc_estate_range(min, max);
660 }
661
662 static void unop_expr(struct expression *expr)
663 {
664 struct smatch_state *state;
665
666 if (expr->smatch_flags & Handled)
667 return;
668
669 switch (expr->op) {
670 case SPECIAL_INCREMENT:
671 state = get_state_expr(SMATCH_EXTRA, expr->unop);
672 state = increment_state(state);
673 if (!state)
674 state = alloc_estate_whole(get_type(expr));
675 set_extra_expr_mod(expr->unop, state);
676 break;
677 case SPECIAL_DECREMENT:
678 state = get_state_expr(SMATCH_EXTRA, expr->unop);
679 state = decrement_state(state);
680 if (!state)
681 state = alloc_estate_whole(get_type(expr));
682 set_extra_expr_mod(expr->unop, state);
683 break;
684 default:
685 return;
686 }
687 }
688
689 static void asm_expr(struct statement *stmt)
690 {
691
692 struct expression *expr;
693 struct symbol *type;
694 int state = 0;
695
696 FOR_EACH_PTR(stmt->asm_outputs, expr) {
697 switch (state) {
698 case 0: /* identifier */
699 case 1: /* constraint */
700 state++;
701 continue;
702 case 2: /* expression */
703 state = 0;
704 type = get_type(strip_expr(expr));
705 set_extra_expr_mod(expr, alloc_estate_whole(type));
706 continue;
707 }
708 } END_FOR_EACH_PTR(expr);
709 }
710
711 static void delete_state_tracker(struct tracker *t)
712 {
713 remove_from_equiv(t->name, t->sym);
714 delete_state(t->owner, t->name, t->sym);
715 }
716
717 static void scoped_state_extra(const char *name, struct symbol *sym)
718 {
719 struct tracker *t;
720
721 t = alloc_tracker(SMATCH_EXTRA, name, sym);
722 add_scope_hook((scope_hook *)&delete_state_tracker, t);
723 }
724
725 static void match_declarations(struct symbol *sym)
726 {
727 const char *name;
728
729 if (sym->ident) {
730 name = sym->ident->name;
731 if (!sym->initializer) {
732 set_state(SMATCH_EXTRA, name, sym, alloc_estate_whole(get_real_base_type(sym)));
733 scoped_state_extra(name, sym);
734 }
735 }
736 }
737
738 static void check_dereference(struct expression *expr)
739 {
740 set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
741 }
742
743 static void match_dereferences(struct expression *expr)
744 {
745 if (expr->type != EXPR_PREOP)
746 return;
747 check_dereference(expr->unop);
748 }
749
750 static void match_pointer_as_array(struct expression *expr)
751 {
752 if (!is_array(expr))
753 return;
754 check_dereference(expr->unop->left);
755 }
756
757 static void set_param_dereferenced(struct expression *arg, char *unused)
758 {
759 check_dereference(arg);
760 }
761
762 static void match_function_def(struct symbol *sym)
763 {
764 struct symbol *arg;
765
766 FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
767 if (!arg->ident)
768 continue;
769 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
770 } END_FOR_EACH_PTR(arg);
771 }
772
773 static sval_t add_one(sval_t sval)
774 {
775 sval.value++;
776 return sval;
777 }
778
779 static sval_t sub_one(sval_t sval)
780 {
781 sval.value--;
782 return sval;
783 }
784
785 static void handle_comparison(struct symbol *type, struct expression *left, int op, struct expression *right)
786 {
787 struct range_list *left_orig;
788 struct range_list *left_true;
789 struct range_list *left_false;
790 struct range_list *right_orig;
791 struct range_list *right_true;
792 struct range_list *right_false;
793 struct smatch_state *left_true_state;
794 struct smatch_state *left_false_state;
795 struct smatch_state *right_true_state;
796 struct smatch_state *right_false_state;
797 sval_t min, max, dummy;
798 int left_postop = 0;
799 int right_postop = 0;
800
801 if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
802 if (left->type == EXPR_POSTOP) {
803 left->smatch_flags |= Handled;
804 left_postop = left->op;
805 }
806 left = strip_expr(left->unop);
807 }
808 while (left->type == EXPR_ASSIGNMENT)
809 left = strip_expr(left->left);
810
811 if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
812 if (right->type == EXPR_POSTOP) {
813 right->smatch_flags |= Handled;
814 right_postop = right->op;
815 }
816 right = strip_expr(right->unop);
817 }
818
819 if (get_implied_rl(left, &left_orig)) {
820 left_orig = cast_rl(type, left_orig);
821 } else {
822 min = sval_type_min(get_type(left));
823 max = sval_type_max(get_type(left));
824 left_orig = cast_rl(type, alloc_rl(min, max));
825 }
826
827 if (get_implied_rl(right, &right_orig)) {
828 right_orig = cast_rl(type, right_orig);
829 } else {
830 min = sval_type_min(get_type(right));
831 max = sval_type_max(get_type(right));
832 right_orig = cast_rl(type, alloc_rl(min, max));
833 }
834 min = sval_type_min(type);
835 max = sval_type_max(type);
836
837 left_true = clone_rl(left_orig);
838 left_false = clone_rl(left_orig);
839 right_true = clone_rl(right_orig);
840 right_false = clone_rl(right_orig);
841
842 switch (op) {
843 case '<':
844 case SPECIAL_UNSIGNED_LT:
845 left_true = remove_range(left_orig, rl_max(right_orig), max);
846 if (!sval_is_min(rl_min(right_orig))) {
847 left_false = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
848 }
849
850 right_true = remove_range(right_orig, min, rl_min(left_orig));
851 if (!sval_is_max(rl_max(left_orig)))
852 right_false = remove_range(right_orig, add_one(rl_max(left_orig)), max);
853 break;
854 case SPECIAL_UNSIGNED_LTE:
855 case SPECIAL_LTE:
856 if (!sval_is_max(rl_max(right_orig)))
857 left_true = remove_range(left_orig, add_one(rl_max(right_orig)), max);
858 left_false = remove_range(left_orig, min, rl_min(right_orig));
859
860 if (!sval_is_min(rl_min(left_orig)))
861 right_true = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
862 right_false = remove_range(right_orig, rl_max(left_orig), max);
863
864 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
865 left_false = remove_range(left_false, rl_min(left_orig), rl_min(left_orig));
866 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
867 right_false = remove_range(right_false, rl_max(left_orig), rl_max(left_orig));
868 break;
869 case SPECIAL_EQUAL:
870 if (!sval_is_max(rl_max(right_orig))) {
871 left_true = remove_range(left_true, add_one(rl_max(right_orig)), max);
872 }
873 if (!sval_is_min(rl_min(right_orig))) {
874 left_true = remove_range(left_true, min, sub_one(rl_min(right_orig)));
875 }
876 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
877 left_false = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
878
879 if (!sval_is_max(rl_max(left_orig)))
880 right_true = remove_range(right_true, add_one(rl_max(left_orig)), max);
881 if (!sval_is_min(rl_min(left_orig)))
882 right_true = remove_range(right_true, min, sub_one(rl_min(left_orig)));
883 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
884 right_false = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
885 break;
886 case SPECIAL_UNSIGNED_GTE:
887 case SPECIAL_GTE:
888 if (!sval_is_min(rl_min(right_orig)))
889 left_true = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
890 left_false = remove_range(left_orig, rl_max(right_orig), max);
891
892 if (!sval_is_max(rl_max(left_orig)))
893 right_true = remove_range(right_orig, add_one(rl_max(left_orig)), max);
894 right_false = remove_range(right_orig, min, rl_min(left_orig));
895
896 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
897 right_false = remove_range(right_false, rl_min(left_orig), rl_min(left_orig));
898 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
899 left_false = remove_range(left_false, rl_max(left_orig), rl_max(left_orig));
900 break;
901 case '>':
902 case SPECIAL_UNSIGNED_GT:
903 left_true = remove_range(left_orig, min, rl_min(right_orig));
904 if (!sval_is_max(rl_max(right_orig)))
905 left_false = remove_range(left_orig, add_one(rl_max(right_orig)), max);
906
907 right_true = remove_range(right_orig, rl_max(left_orig), max);
908 if (!sval_is_min(rl_min(left_orig)))
909 right_false = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
910 break;
911 case SPECIAL_NOTEQUAL:
912 if (!sval_is_max(rl_max(right_orig)))
913 left_false = remove_range(left_false, add_one(rl_max(right_orig)), max);
914 if (!sval_is_min(rl_min(right_orig)))
915 left_false = remove_range(left_false, min, sub_one(rl_min(right_orig)));
916 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
917 left_true = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
918
919 if (!sval_is_max(rl_max(left_orig)))
920 right_false = remove_range(right_false, add_one(rl_max(left_orig)), max);
921 if (!sval_is_min(rl_min(left_orig)))
922 right_false = remove_range(right_false, min, sub_one(rl_min(left_orig)));
923 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
924 right_true = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
925 break;
926 default:
927 return;
928 }
929
930 left_true = rl_truncate_cast(get_type(left), left_true);
931 left_false = rl_truncate_cast(get_type(left), left_false);
932 right_true = rl_truncate_cast(get_type(right), right_true);
933 right_false = rl_truncate_cast(get_type(right), right_false);
934
935 left_true_state = alloc_estate_rl(left_true);
936 left_false_state = alloc_estate_rl(left_false);
937 right_true_state = alloc_estate_rl(right_true);
938 right_false_state = alloc_estate_rl(right_false);
939
940 switch (op) {
941 case '<':
942 case SPECIAL_UNSIGNED_LT:
943 case SPECIAL_UNSIGNED_LTE:
944 case SPECIAL_LTE:
945 if (get_hard_max(right, &dummy))
946 estate_set_hard_max(left_true_state);
947 if (get_hard_max(left, &dummy))
948 estate_set_hard_max(right_false_state);
949 break;
950 case '>':
951 case SPECIAL_UNSIGNED_GT:
952 case SPECIAL_UNSIGNED_GTE:
953 case SPECIAL_GTE:
954 if (get_hard_max(left, &dummy))
955 estate_set_hard_max(right_true_state);
956 if (get_hard_max(right, &dummy))
957 estate_set_hard_max(left_false_state);
958 break;
959 }
960
961 if (get_hard_max(left, &dummy)) {
962 estate_set_hard_max(left_true_state);
963 estate_set_hard_max(left_false_state);
964 }
965 if (get_hard_max(right, &dummy)) {
966 estate_set_hard_max(right_true_state);
967 estate_set_hard_max(right_false_state);
968 }
969
970 if (left_postop == SPECIAL_INCREMENT) {
971 left_true_state = increment_state(left_true_state);
972 left_false_state = increment_state(left_false_state);
973 }
974 if (left_postop == SPECIAL_DECREMENT) {
975 left_true_state = decrement_state(left_true_state);
976 left_false_state = decrement_state(left_false_state);
977 }
978 if (right_postop == SPECIAL_INCREMENT) {
979 right_true_state = increment_state(right_true_state);
980 right_false_state = increment_state(right_false_state);
981 }
982 if (right_postop == SPECIAL_DECREMENT) {
983 right_true_state = decrement_state(right_true_state);
984 right_false_state = decrement_state(right_false_state);
985 }
986
987 set_extra_expr_true_false(left, left_true_state, left_false_state);
988 set_extra_expr_true_false(right, right_true_state, right_false_state);
989 }
990
991 static int opposite_op(int op)
992 {
993 switch (op) {
994 case '+':
995 return '-';
996 case '-':
997 return '+';
998 }
999 return 0;
1000 }
1001
1002 static int is_simple_math(struct expression *expr)
1003 {
1004 if (!expr)
1005 return 0;
1006 if (expr->type != EXPR_BINOP)
1007 return 0;
1008 if (!opposite_op(expr->op))
1009 return 0;
1010 return 1;
1011 }
1012
1013 static void move_known_values(struct expression **left_p, struct expression **right_p)
1014 {
1015 struct expression *left = *left_p;
1016 struct expression *right = *right_p;
1017 sval_t sval;
1018
1019 if (get_implied_value(left, &sval)) {
1020 if (!is_simple_math(right))
1021 return;
1022 if (right->op == '+' && get_value(right->left, &sval)) {
1023 *left_p = binop_expression(left, opposite_op(right->op), right->left);
1024 *right_p = right->right;
1025 return;
1026 }
1027 if (get_value(right->right, &sval)) {
1028 *left_p = binop_expression(left, opposite_op(right->op), right->right);
1029 *right_p = right->left;
1030 return;
1031 }
1032 return;
1033 }
1034 if (get_implied_value(right, &sval)) {
1035 if (!is_simple_math(left))
1036 return;
1037 if (left->op == '+' && get_value(left->left, &sval)) {
1038 *right_p = binop_expression(right, opposite_op(left->op), left->left);
1039 *left_p = left->right;
1040 return;
1041 }
1042
1043 if (get_value(left->right, &sval)) {
1044 *right_p = binop_expression(right, opposite_op(left->op), left->right);
1045 *left_p = left->left;
1046 return;
1047 }
1048 return;
1049 }
1050 }
1051
1052 static int match_func_comparison(struct expression *expr)
1053 {
1054 struct expression *left = strip_expr(expr->left);
1055 struct expression *right = strip_expr(expr->right);
1056 sval_t sval;
1057
1058 /*
1059 * fixme: think about this harder. We should always be trying to limit
1060 * the non-call side as well. If we can't determine the limitter does
1061 * that mean we aren't querying the database and are missing important
1062 * information?
1063 */
1064
1065 if (left->type == EXPR_CALL) {
1066 if (get_implied_value(left, &sval)) {
1067 handle_comparison(get_type(expr), left, expr->op, right);
1068 return 1;
1069 }
1070 if (!get_implied_value(right, &sval))
1071 return 1;
1072 function_comparison(expr->op, left, sval, 1);
1073 return 1;
1074 }
1075
1076 if (right->type == EXPR_CALL) {
1077 if (get_implied_value(right, &sval)) {
1078 handle_comparison(get_type(expr), left, expr->op, right);
1079 return 1;
1080 }
1081 if (!get_implied_value(left, &sval))
1082 return 1;
1083 function_comparison(expr->op, right, sval, 0);
1084 return 1;
1085 }
1086
1087 return 0;
1088 }
1089
1090 static void match_comparison(struct expression *expr)
1091 {
1092 struct expression *left_orig = strip_expr(expr->left);
1093 struct expression *right_orig = strip_expr(expr->right);
1094 struct expression *left, *right;
1095 struct expression *prev;
1096 struct symbol *type;
1097
1098 if (match_func_comparison(expr))
1099 return;
1100
1101 type = get_type(expr);
1102 if (!type)
1103 type = &llong_ctype;
1104
1105 left = left_orig;
1106 right = right_orig;
1107 move_known_values(&left, &right);
1108 handle_comparison(type, left, expr->op, right);
1109
1110 prev = get_assigned_expr(left_orig);
1111 if (is_simple_math(prev) && has_variable(prev, left_orig) == 0) {
1112 left = prev;
1113 right = right_orig;
1114 move_known_values(&left, &right);
1115 handle_comparison(type, left, expr->op, right);
1116 }
1117
1118 prev = get_assigned_expr(right_orig);
1119 if (is_simple_math(prev) && has_variable(prev, right_orig) == 0) {
1120 left = left_orig;
1121 right = prev;
1122 move_known_values(&left, &right);
1123 handle_comparison(type, left, expr->op, right);
1124 }
1125 }
1126
1127 /* this is actually hooked from smatch_implied.c... it's hacky, yes */
1128 void __extra_match_condition(struct expression *expr)
1129 {
1130 struct symbol *sym;
1131 char *name;
1132 struct smatch_state *pre_state;
1133 struct smatch_state *true_state;
1134 struct smatch_state *false_state;
1135
1136 expr = strip_expr(expr);
1137 switch (expr->type) {
1138 case EXPR_CALL:
1139 function_comparison(SPECIAL_NOTEQUAL, expr, ll_to_sval(0), 1);
1140 return;
1141 case EXPR_PREOP:
1142 case EXPR_SYMBOL:
1143 case EXPR_DEREF: {
1144 sval_t zero;
1145
1146 zero = sval_blank(expr);
1147 zero.value = 0;
1148
1149 name = expr_to_var_sym(expr, &sym);
1150 if (!name)
1151 return;
1152 pre_state = get_state(my_id, name, sym);
1153 true_state = estate_filter_sval(pre_state, zero);
1154 if (possibly_true(expr, SPECIAL_EQUAL, zero_expr()))
1155 false_state = alloc_estate_sval(zero);
1156 else
1157 false_state = alloc_estate_empty();
1158 set_extra_true_false(name, sym, true_state, false_state);
1159 free_string(name);
1160 return;
1161 }
1162 case EXPR_COMPARE:
1163 match_comparison(expr);
1164 return;
1165 case EXPR_ASSIGNMENT:
1166 __extra_match_condition(expr->left);
1167 return;
1168 }
1169 }
1170
1171 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
1172 int implied_not_equal(struct expression *expr, long long val)
1173 {
1174 return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
1175 }
1176
1177 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct smatch_state *state)
1178 {
1179 if (estate_is_whole(state))
1180 return;
1181 sql_insert_caller_info(call, PARAM_VALUE, param, printed_name, state->name);
1182 }
1183
1184 static void db_limited_before(void)
1185 {
1186 unmatched_slist = clone_slist(__get_cur_slist());
1187 }
1188
1189 static void db_limited_after(void)
1190 {
1191 free_slist(&unmatched_slist);
1192 }
1193
1194 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value, int mod)
1195 {
1196 struct expression *arg;
1197 char *name;
1198 struct symbol *sym;
1199 struct sm_state *sm;
1200 struct symbol *type;
1201 struct range_list *rl;
1202 struct range_list *limit;
1203 struct range_list *new;
1204
1205 while (expr->type == EXPR_ASSIGNMENT)
1206 expr = strip_expr(expr->right);
1207 if (expr->type != EXPR_CALL)
1208 return;
1209
1210 arg = get_argument_from_call_expr(expr->args, param);
1211 if (!arg)
1212 return;
1213
1214 name = get_variable_from_key(arg, key, &sym);
1215 if (!name || !sym)
1216 goto free;
1217
1218 sm = get_sm_state(SMATCH_EXTRA, name, sym);
1219 type = get_member_type_from_key(arg, key);
1220 if (sm)
1221 rl = estate_rl(sm->state);
1222 else
1223 rl = alloc_whole_rl(type);
1224
1225 call_results_to_rl(expr, type, value, &limit);
1226 new = rl_intersection(rl, limit);
1227
1228 /* We want to preserve the implications here */
1229 if (sm && rl_equiv(estate_rl(sm->state), new)) {
1230 __set_sm(sm);
1231 } else {
1232 if (mod)
1233 set_extra_mod(name, sym, alloc_estate_rl(new));
1234 else
1235 set_extra_nomod(name, sym, alloc_estate_rl(new));
1236 }
1237
1238 free:
1239 free_string(name);
1240 }
1241
1242 static void db_param_limit(struct expression *expr, int param, char *key, char *value)
1243 {
1244 db_param_limit_filter(expr, param, key, value, 0);
1245 }
1246
1247 static void db_param_filter(struct expression *expr, int param, char *key, char *value)
1248 {
1249 db_param_limit_filter(expr, param, key, value, 1);
1250 }
1251
1252 static void db_param_add(struct expression *expr, int param, char *key, char *value)
1253 {
1254 struct expression *arg;
1255 char *name;
1256 struct symbol *sym;
1257 struct symbol *type;
1258 struct smatch_state *state;
1259 struct range_list *added = NULL;
1260 struct range_list *new;
1261
1262 while (expr->type == EXPR_ASSIGNMENT)
1263 expr = strip_expr(expr->right);
1264 if (expr->type != EXPR_CALL)
1265 return;
1266
1267 arg = get_argument_from_call_expr(expr->args, param);
1268 if (!arg)
1269 return;
1270 name = get_variable_from_key(arg, key, &sym);
1271 if (!name || !sym)
1272 goto free;
1273
1274 type = get_member_type_from_key(arg, key);
1275 state = get_state(SMATCH_EXTRA, name, sym);
1276 if (state) {
1277 call_results_to_rl(expr, type, value, &added);
1278 new = rl_union(estate_rl(state), added);
1279 } else {
1280 new = alloc_whole_rl(type);
1281 }
1282
1283 set_extra_mod(name, sym, alloc_estate_rl(new));
1284 free:
1285 free_string(name);
1286 }
1287
1288 static void db_returned_member_info(struct expression *expr, int param, char *key, char *value)
1289 {
1290 struct symbol *type;
1291 struct symbol *sym;
1292 char *name;
1293 char member_name[256];
1294 struct range_list *rl;
1295
1296 if (expr->type != EXPR_ASSIGNMENT)
1297 return;
1298
1299 name = expr_to_var_sym(expr->left, &sym);
1300 if (!name || !sym)
1301 goto free;
1302 snprintf(member_name, sizeof(member_name), "%s%s", name, key + 2);
1303 type = get_member_type_from_key(expr->left, key);
1304 if (!type)
1305 return;
1306 call_results_to_rl(expr->right, type, value, &rl);
1307 set_extra_mod(member_name, sym, alloc_estate_rl(rl));
1308
1309 free:
1310 free_string(name);
1311 }
1312
1313 static void returned_member_callback(int return_id, char *return_ranges, char *printed_name, struct smatch_state *state)
1314 {
1315 if (estate_is_whole(state))
1316 return;
1317
1318 sql_insert_return_states(return_id, return_ranges, RETURN_VALUE, -1,
1319 printed_name, state->name);
1320 }
1321
1322 static void match_call_info(struct expression *expr)
1323 {
1324 struct range_list *rl = NULL;
1325 struct expression *arg;
1326 struct symbol *type;
1327 int i = 0;
1328
1329 FOR_EACH_PTR(expr->args, arg) {
1330 type = get_arg_type(expr->fn, i);
1331
1332 if (get_implied_rl(arg, &rl))
1333 rl = cast_rl(type, rl);
1334 else
1335 rl = cast_rl(type, alloc_whole_rl(get_type(arg)));
1336
1337 sql_insert_caller_info(expr, PARAM_VALUE, i, "$$", show_rl(rl));
1338 i++;
1339 } END_FOR_EACH_PTR(arg);
1340 }
1341
1342 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
1343 {
1344 struct range_list *rl = NULL;
1345 struct smatch_state *state;
1346 struct symbol *type;
1347 char fullname[256];
1348
1349 if (strcmp(key, "*$$") == 0)
1350 snprintf(fullname, sizeof(fullname), "*%s", name);
1351 else if (strncmp(key, "$$", 2) == 0)
1352 snprintf(fullname, 256, "%s%s", name, key + 2);
1353 else
1354 return;
1355
1356 type = get_member_type_from_key(symbol_expression(sym), key);
1357 str_to_rl(type, value, &rl);
1358 state = alloc_estate_rl(rl);
1359 set_state(SMATCH_EXTRA, fullname, sym, state);
1360 }
1361
1362 void register_smatch_extra(int id)
1363 {
1364 my_id = id;
1365
1366 add_merge_hook(my_id, &merge_estates);
1367 add_unmatched_state_hook(my_id, &unmatched_state);
1368 add_hook(&match_function_def, FUNC_DEF_HOOK);
1369 add_hook(&match_declarations, DECLARATION_HOOK);
1370 select_caller_info_hook(set_param_value, PARAM_VALUE);
1371 select_return_states_hook(RETURN_VALUE, &db_returned_member_info);
1372 select_return_states_before(&db_limited_before);
1373 select_return_states_hook(LIMITED_VALUE, &db_param_limit);
1374 select_return_states_hook(FILTER_VALUE, &db_param_filter);
1375 select_return_states_hook(ADDED_VALUE, &db_param_add);
1376 select_return_states_after(&db_limited_after);
1377 }
1378
1379 void register_smatch_extra_late(int id)
1380 {
1381 add_hook(&match_dereferences, DEREF_HOOK);
1382 add_hook(&match_pointer_as_array, OP_HOOK);
1383 select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);
1384 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
1385 add_hook(&match_assign, ASSIGNMENT_HOOK);
1386 add_hook(&unop_expr, OP_HOOK);
1387 add_hook(&asm_expr, ASM_HOOK);
1388
1389 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1390 add_member_info_callback(my_id, struct_member_callback);
1391 add_returned_member_callback(my_id, returned_member_callback);
1392 }
Static analysis for C