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math: export get_const_value()
[smatch.git] / smatch_extra.c
blob8ae8abd38120d4f165ced1dc1962733d7937b7a7
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 if (!stmt)
37 return 0;
38 macro = get_macro_name(stmt->pos);
39 if (!macro)
40 return 0;
41
42 FOR_EACH_PTR(__ignored_macros, tmp) {
43 if (!strcmp(tmp, macro))
44 return 1;
45 } END_FOR_EACH_PTR(tmp);
46 return 0;
47 }
48
49 typedef void (mod_hook)(const char *name, struct symbol *sym, struct smatch_state *state);
50 DECLARE_PTR_LIST(void_fn_list, mod_hook *);
51 static struct void_fn_list *extra_mod_hooks;
52 void add_extra_mod_hook(mod_hook *fn)
53 {
54 mod_hook **p = malloc(sizeof(mod_hook *));
55 *p = fn;
56 add_ptr_list(&extra_mod_hooks, p);
57 }
58
59 void call_extra_mod_hooks(const char *name, struct symbol *sym, struct smatch_state *state)
60 {
61 mod_hook **fn;
62
63 FOR_EACH_PTR(extra_mod_hooks, fn) {
64 (*fn)(name, sym, state);
65 } END_FOR_EACH_PTR(fn);
66 }
67
68 struct sm_state *set_extra_mod(const char *name, struct symbol *sym, struct smatch_state *state)
69 {
70 if (in_warn_on_macro())
71 return NULL;
72 remove_from_equiv(name, sym);
73 call_extra_mod_hooks(name, sym, state);
74 return set_state(SMATCH_EXTRA, name, sym, state);
75 }
76
77 struct sm_state *set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
78 {
79 struct symbol *sym;
80 char *name;
81 struct sm_state *ret = NULL;
82
83 expr = strip_expr(expr);
84 name = expr_to_var_sym(expr, &sym);
85 if (!name || !sym)
86 goto free;
87 ret = set_extra_mod(name, sym, state);
88 free:
89 free_string(name);
90 return ret;
91 }
92
93 void set_extra_nomod(const char *name, struct symbol *sym, struct smatch_state *state)
94 {
95 struct relation *rel;
96 struct smatch_state *orig_state;
97
98 orig_state = get_state(SMATCH_EXTRA, name, sym);
99
100 if (!estate_related(orig_state)) {
101 set_state(SMATCH_EXTRA, name, sym, state);
102 return;
103 }
104
105 set_related(state, estate_related(orig_state));
106 FOR_EACH_PTR(estate_related(orig_state), rel) {
107 if (option_debug_related)
108 sm_msg("updating related %s to %s", rel->name, state->name);
109 set_state(SMATCH_EXTRA, rel->name, rel->sym, state);
110 } END_FOR_EACH_PTR(rel);
111 }
112
113 /*
114 * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
115 */
116 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
117 {
118 char *name;
119 struct symbol *sym;
120
121 name = expr_to_var_sym(expr, &sym);
122 if (!name || !sym)
123 goto free;
124 set_extra_nomod(name, sym, state);
125 free:
126 free_string(name);
127
128 }
129
130 static void set_extra_true_false(const char *name, struct symbol *sym,
131 struct smatch_state *true_state,
132 struct smatch_state *false_state)
133 {
134 struct relation *rel;
135 struct smatch_state *orig_state;
136
137 if (in_warn_on_macro())
138 return;
139
140 orig_state = get_state(SMATCH_EXTRA, name, sym);
141
142 if (!estate_related(orig_state)) {
143 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
144 return;
145 }
146
147 if (true_state)
148 set_related(true_state, estate_related(orig_state));
149 if (false_state)
150 set_related(false_state, estate_related(orig_state));
151
152 FOR_EACH_PTR(estate_related(orig_state), rel) {
153 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
154 true_state, false_state);
155 } END_FOR_EACH_PTR(rel);
156 }
157
158 static void set_extra_expr_true_false(struct expression *expr,
159 struct smatch_state *true_state,
160 struct smatch_state *false_state)
161 {
162 char *name;
163 struct symbol *sym;
164
165 expr = strip_expr(expr);
166 name = expr_to_var_sym(expr, &sym);
167 if (!name || !sym)
168 goto free;
169 set_extra_true_false(name, sym, true_state, false_state);
170 free:
171 free_string(name);
172 }
173
174 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
175 {
176 struct expression *iter_var;
177 struct expression *condition;
178 struct sm_state *sm;
179 struct smatch_state *estate;
180 sval_t start;
181
182 condition = strip_expr(loop->iterator_pre_condition);
183 if (!condition)
184 return NULL;
185 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
186 return NULL;
187 if (condition->op != SPECIAL_DECREMENT)
188 return NULL;
189
190 iter_var = condition->unop;
191 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
192 if (!sm)
193 return NULL;
194 if (sval_cmp_val(estate_min(sm->state), 0) < 0)
195 return NULL;
196 start = estate_max(sm->state);
197 if (sval_cmp_val(start, 0) <= 0)
198 return NULL;
199 if (!sval_is_max(start))
200 start.value--;
201
202 if (condition->type == EXPR_PREOP) {
203 estate = alloc_estate_range(sval_type_val(start.type, 1), start);
204 if (estate_has_hard_max(sm->state))
205 estate_set_hard_max(estate);
206 set_extra_expr_mod(iter_var, estate);
207 }
208 if (condition->type == EXPR_POSTOP) {
209 estate = alloc_estate_range(sval_type_val(start.type, 0), start);
210 if (estate_has_hard_max(sm->state))
211 estate_set_hard_max(estate);
212 set_extra_expr_mod(iter_var, estate);
213 }
214 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
215 }
216
217 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
218 struct expression *condition)
219 {
220 struct expression *iter_var;
221 struct sm_state *sm;
222 struct smatch_state *estate;
223 sval_t start, end, dummy;
224
225 iter_var = iter_expr->unop;
226 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
227 if (!sm)
228 return NULL;
229 if (!estate_get_single_value(sm->state, &start))
230 return NULL;
231 if (get_implied_max(condition->right, &end))
232 end = sval_cast(get_type(iter_var), end);
233 else
234 end = sval_type_max(get_type(iter_var));
235
236 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
237 return NULL;
238
239 switch (condition->op) {
240 case SPECIAL_NOTEQUAL:
241 case '<':
242 if (!sval_is_min(end))
243 end.value--;
244 break;
245 case SPECIAL_LTE:
246 break;
247 default:
248 return NULL;
249 }
250 if (sval_cmp(end, start) < 0)
251 return NULL;
252 estate = alloc_estate_range(start, end);
253 if (get_hard_max(condition->right, &dummy))
254 estate_set_hard_max(estate);
255 set_extra_expr_mod(iter_var, estate);
256 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
257 }
258
259 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
260 struct expression *condition)
261 {
262 struct expression *iter_var;
263 struct sm_state *sm;
264 struct smatch_state *estate;
265 sval_t start, end;
266
267 iter_var = iter_expr->unop;
268 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
269 if (!sm)
270 return NULL;
271 if (!estate_get_single_value(sm->state, &start))
272 return NULL;
273 if (!get_implied_min(condition->right, &end))
274 end = sval_type_min(get_type(iter_var));
275 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
276 return NULL;
277
278 switch (condition->op) {
279 case SPECIAL_NOTEQUAL:
280 case '>':
281 if (!sval_is_min(end) && !sval_is_max(end))
282 end.value++;
283 break;
284 case SPECIAL_GTE:
285 break;
286 default:
287 return NULL;
288 }
289 if (sval_cmp(end, start) > 0)
290 return NULL;
291 estate = alloc_estate_range(end, start);
292 estate_set_hard_max(estate);
293 set_extra_expr_mod(iter_var, estate);
294 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
295 }
296
297 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
298 {
299 struct expression *iter_expr;
300 struct expression *condition;
301
302 if (!loop->iterator_post_statement)
303 return NULL;
304 if (loop->iterator_post_statement->type != STMT_EXPRESSION)
305 return NULL;
306 iter_expr = loop->iterator_post_statement->expression;
307 if (!loop->iterator_pre_condition)
308 return NULL;
309 if (loop->iterator_pre_condition->type != EXPR_COMPARE)
310 return NULL;
311 condition = loop->iterator_pre_condition;
312
313 if (iter_expr->op == SPECIAL_INCREMENT)
314 return handle_canonical_for_inc(iter_expr, condition);
315 if (iter_expr->op == SPECIAL_DECREMENT)
316 return handle_canonical_for_dec(iter_expr, condition);
317 return NULL;
318 }
319
320 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct state_list **slist)
321 {
322 struct sm_state *ret;
323
324 __push_fake_cur_slist();
325 if (!loop->iterator_post_statement)
326 ret = handle_canonical_while_count_down(loop);
327 else
328 ret = handle_canonical_for_loops(loop);
329 *slist = __pop_fake_cur_slist();
330 return ret;
331 }
332
333 int __iterator_unchanged(struct sm_state *sm)
334 {
335 if (!sm)
336 return 0;
337 if (get_sm_state(my_id, sm->name, sm->sym) == sm)
338 return 1;
339 return 0;
340 }
341
342 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
343 {
344 sval_t after_value;
345
346 /* paranoid checking. prolly not needed */
347 condition = strip_expr(condition);
348 if (!condition)
349 return;
350 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
351 return;
352 if (condition->op != SPECIAL_DECREMENT)
353 return;
354 after_value = estate_min(sm->state);
355 after_value.value--;
356 set_extra_mod(sm->name, sm->sym, alloc_estate_sval(after_value));
357 }
358
359 void __extra_pre_loop_hook_after(struct sm_state *sm,
360 struct statement *iterator,
361 struct expression *condition)
362 {
363 struct expression *iter_expr;
364 sval_t limit;
365 struct smatch_state *state;
366
367 if (!iterator) {
368 while_count_down_after(sm, condition);
369 return;
370 }
371
372 iter_expr = iterator->expression;
373
374 if (condition->type != EXPR_COMPARE)
375 return;
376 if (iter_expr->op == SPECIAL_INCREMENT) {
377 limit = sval_binop(estate_max(sm->state), '+',
378 sval_type_val(estate_type(sm->state), 1));
379 } else {
380 limit = sval_binop(estate_min(sm->state), '-',
381 sval_type_val(estate_type(sm->state), 1));
382 }
383 if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
384 if (iter_expr->op == SPECIAL_INCREMENT)
385 state = alloc_estate_range(estate_min(sm->state), limit);
386 else
387 state = alloc_estate_range(limit, estate_max(sm->state));
388 } else {
389 state = alloc_estate_sval(limit);
390 }
391 if (!estate_has_hard_max(sm->state))
392 estate_clear_hard_max(state);
393 set_extra_mod(sm->name, sm->sym, state);
394 }
395
396 static struct state_list *unmatched_slist;
397 static struct smatch_state *unmatched_state(struct sm_state *sm)
398 {
399 struct smatch_state *state;
400
401 if (unmatched_slist) {
402 state = get_state_slist(unmatched_slist, SMATCH_EXTRA, sm->name, sm->sym);
403 if (state)
404 return state;
405 }
406 return alloc_estate_whole(estate_type(sm->state));
407 }
408
409 static void clear_the_pointed_at(struct expression *expr, struct state_list *slist)
410 {
411 char *name;
412 struct symbol *sym;
413 struct sm_state *tmp;
414
415 name = expr_to_var_sym(expr, &sym);
416 if (!name || !sym)
417 goto free;
418
419 FOR_EACH_PTR(slist, tmp) {
420 if (tmp->name[0] != '*')
421 continue;
422 if (tmp->sym != sym)
423 continue;
424 if (strcmp(tmp->name + 1, name) != 0)
425 continue;
426 set_extra_mod(tmp->name, tmp->sym, alloc_estate_whole(estate_type(tmp->state)));
427 } END_FOR_EACH_PTR(tmp);
428
429 free:
430 free_string(name);
431 }
432
433 static void match_function_call(struct expression *expr)
434 {
435 struct expression *arg;
436 struct expression *tmp;
437 struct state_list *slist;
438
439 /* if we have the db this is handled in smatch_function_hooks.c */
440 if (!option_no_db)
441 return;
442 if (inlinable(expr->fn))
443 return;
444
445 slist = get_all_states(SMATCH_EXTRA);
446
447 FOR_EACH_PTR(expr->args, arg) {
448 tmp = strip_expr(arg);
449 if (tmp->type == EXPR_PREOP && tmp->op == '&')
450 set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
451 else
452 clear_the_pointed_at(tmp, slist);
453 } END_FOR_EACH_PTR(arg);
454
455 free_slist(&slist);
456 }
457
458 static int types_equiv_or_pointer(struct symbol *one, struct symbol *two)
459 {
460 if (!one || !two)
461 return 0;
462 if (one->type == SYM_PTR && two->type == SYM_PTR)
463 return 1;
464 return types_equiv(one, two);
465 }
466
467 static void match_vanilla_assign(struct expression *left, struct expression *right)
468 {
469 struct range_list *rl = NULL;
470 struct symbol *right_sym;
471 struct symbol *left_type;
472 struct symbol *right_type;
473 char *right_name = NULL;
474 struct symbol *sym;
475 char *name;
476 sval_t tmp;
477 struct smatch_state *state;
478
479 name = expr_to_var_sym(left, &sym);
480 if (!name)
481 return;
482
483 left_type = get_type(left);
484 right_type = get_type(right);
485
486 right_name = expr_to_var_sym(right, &right_sym);
487 if (right_name && right_sym &&
488 types_equiv_or_pointer(left_type, right_type)) {
489 set_equiv(left, right);
490 goto free;
491 }
492
493 if (get_implied_rl(right, &rl)) {
494 rl = cast_rl(left_type, rl);
495 state = alloc_estate_rl(rl);
496 if (get_hard_max(right, &tmp))
497 estate_set_hard_max(state);
498 } else {
499 rl = alloc_whole_rl(right_type);
500 rl = cast_rl(left_type, rl);
501 state = alloc_estate_rl(rl);
502 }
503 set_extra_mod(name, sym, state);
504 free:
505 free_string(right_name);
506 }
507
508 static int op_remove_assign(int op)
509 {
510 switch (op) {
511 case SPECIAL_ADD_ASSIGN:
512 return '+';
513 case SPECIAL_SUB_ASSIGN:
514 return '-';
515 case SPECIAL_MUL_ASSIGN:
516 return '*';
517 case SPECIAL_DIV_ASSIGN:
518 return '/';
519 case SPECIAL_MOD_ASSIGN:
520 return '%';
521 case SPECIAL_AND_ASSIGN:
522 return '&';
523 case SPECIAL_OR_ASSIGN:
524 return '|';
525 case SPECIAL_XOR_ASSIGN:
526 return '^';
527 case SPECIAL_SHL_ASSIGN:
528 return SPECIAL_LEFTSHIFT;
529 case SPECIAL_SHR_ASSIGN:
530 return SPECIAL_RIGHTSHIFT;
531 default:
532 return op;
533 }
534 }
535
536 static void match_assign(struct expression *expr)
537 {
538 struct range_list *rl = NULL;
539 struct expression *left;
540 struct expression *right;
541 struct expression *binop_expr;
542 struct symbol *left_type;
543 struct symbol *right_type;
544 struct symbol *sym;
545 char *name;
546 sval_t left_min, left_max;
547 sval_t right_min, right_max;
548 sval_t res_min, res_max;
549
550 left = strip_expr(expr->left);
551
552 right = strip_expr(expr->right);
553 while (right->type == EXPR_ASSIGNMENT && right->op == '=')
554 right = strip_expr(right->left);
555
556 if (is_condition(expr->right))
557 return; /* handled in smatch_condition.c */
558 if (expr->op == '=' && right->type == EXPR_CALL)
559 return; /* handled in smatch_function_hooks.c */
560 if (expr->op == '=') {
561 match_vanilla_assign(left, right);
562 return;
563 }
564
565 name = expr_to_var_sym(left, &sym);
566 if (!name)
567 return;
568
569 left_type = get_type(left);
570 right_type = get_type(right);
571
572 res_min = sval_type_min(right_type);
573 res_max = sval_type_max(right_type);
574
575 switch (expr->op) {
576 case SPECIAL_ADD_ASSIGN:
577 get_absolute_max(left, &left_max);
578 get_absolute_max(right, &right_max);
579 if (sval_binop_overflows(left_max, '+', right_max))
580 break;
581 if (get_implied_min(left, &left_min) &&
582 !sval_is_negative_min(left_min) &&
583 get_implied_min(right, &right_min) &&
584 !sval_is_negative_min(right_min)) {
585 res_min = sval_binop(left_min, '+', right_min);
586 res_min = sval_cast(right_type, res_min);
587 }
588 if (inside_loop()) /* we are assuming loops don't lead to wrapping */
589 break;
590 res_max = sval_binop(left_max, '+', right_max);
591 res_max = sval_cast(right_type, res_max);
592 break;
593 case SPECIAL_SUB_ASSIGN:
594 if (get_implied_max(left, &left_max) &&
595 !sval_is_max(left_max) &&
596 get_implied_min(right, &right_min) &&
597 !sval_is_min(right_min)) {
598 res_max = sval_binop(left_max, '-', right_min);
599 res_max = sval_cast(right_type, res_max);
600 }
601 if (inside_loop())
602 break;
603 if (get_implied_min(left, &left_min) &&
604 !sval_is_min(left_min) &&
605 get_implied_max(right, &right_max) &&
606 !sval_is_max(right_max)) {
607 res_min = sval_binop(left_min, '-', right_max);
608 res_min = sval_cast(right_type, res_min);
609 }
610 break;
611 case SPECIAL_AND_ASSIGN:
612 case SPECIAL_MOD_ASSIGN:
613 binop_expr = binop_expression(expr->left,
614 op_remove_assign(expr->op),
615 expr->right);
616 if (get_implied_rl(binop_expr, &rl)) {
617 rl = cast_rl(left_type, rl);
618 set_extra_mod(name, sym, alloc_estate_rl(rl));
619 goto free;
620 }
621 }
622 rl = cast_rl(left_type, alloc_rl(res_min, res_max));
623 set_extra_mod(name, sym, alloc_estate_rl(rl));
624 free:
625 free_string(name);
626 }
627
628 static struct smatch_state *increment_state(struct smatch_state *state)
629 {
630 sval_t min = estate_min(state);
631 sval_t max = estate_max(state);
632
633 if (!estate_rl(state))
634 return NULL;
635
636 if (inside_loop())
637 max = sval_type_max(max.type);
638
639 if (!sval_is_min(min) && !sval_is_max(min))
640 min.value++;
641 if (!sval_is_min(max) && !sval_is_max(max))
642 max.value++;
643 return alloc_estate_range(min, max);
644 }
645
646 static struct smatch_state *decrement_state(struct smatch_state *state)
647 {
648 sval_t min = estate_min(state);
649 sval_t max = estate_max(state);
650
651 if (!estate_rl(state))
652 return NULL;
653
654 if (inside_loop())
655 min = sval_type_min(min.type);
656
657 if (!sval_is_min(min) && !sval_is_max(min))
658 min.value--;
659 if (!sval_is_min(max) && !sval_is_max(max))
660 max.value--;
661 return alloc_estate_range(min, max);
662 }
663
664 static void unop_expr(struct expression *expr)
665 {
666 struct smatch_state *state;
667
668 if (expr->smatch_flags & Handled)
669 return;
670
671 switch (expr->op) {
672 case SPECIAL_INCREMENT:
673 state = get_state_expr(SMATCH_EXTRA, expr->unop);
674 state = increment_state(state);
675 if (!state)
676 state = alloc_estate_whole(get_type(expr));
677 set_extra_expr_mod(expr->unop, state);
678 break;
679 case SPECIAL_DECREMENT:
680 state = get_state_expr(SMATCH_EXTRA, expr->unop);
681 state = decrement_state(state);
682 if (!state)
683 state = alloc_estate_whole(get_type(expr));
684 set_extra_expr_mod(expr->unop, state);
685 break;
686 default:
687 return;
688 }
689 }
690
691 static void asm_expr(struct statement *stmt)
692 {
693
694 struct expression *expr;
695 struct symbol *type;
696 int state = 0;
697
698 FOR_EACH_PTR(stmt->asm_outputs, expr) {
699 switch (state) {
700 case 0: /* identifier */
701 case 1: /* constraint */
702 state++;
703 continue;
704 case 2: /* expression */
705 state = 0;
706 type = get_type(strip_expr(expr));
707 set_extra_expr_mod(expr, alloc_estate_whole(type));
708 continue;
709 }
710 } END_FOR_EACH_PTR(expr);
711 }
712
713 static void delete_state_tracker(struct tracker *t)
714 {
715 remove_from_equiv(t->name, t->sym);
716 delete_state(t->owner, t->name, t->sym);
717 }
718
719 static void scoped_state_extra(const char *name, struct symbol *sym)
720 {
721 struct tracker *t;
722
723 t = alloc_tracker(SMATCH_EXTRA, name, sym);
724 add_scope_hook((scope_hook *)&delete_state_tracker, t);
725 }
726
727 static void match_declarations(struct symbol *sym)
728 {
729 const char *name;
730
731 if (sym->ident) {
732 name = sym->ident->name;
733 if (!sym->initializer) {
734 set_state(SMATCH_EXTRA, name, sym, alloc_estate_whole(get_real_base_type(sym)));
735 scoped_state_extra(name, sym);
736 }
737 }
738 }
739
740 static void check_dereference(struct expression *expr)
741 {
742 set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
743 }
744
745 static void match_dereferences(struct expression *expr)
746 {
747 if (expr->type != EXPR_PREOP)
748 return;
749 check_dereference(expr->unop);
750 }
751
752 static void match_pointer_as_array(struct expression *expr)
753 {
754 if (!is_array(expr))
755 return;
756 check_dereference(expr->unop->left);
757 }
758
759 static void set_param_dereferenced(struct expression *arg, char *unused)
760 {
761 check_dereference(arg);
762 }
763
764 static void match_function_def(struct symbol *sym)
765 {
766 struct symbol *arg;
767
768 FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
769 if (!arg->ident)
770 continue;
771 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
772 } END_FOR_EACH_PTR(arg);
773 }
774
775 static sval_t add_one(sval_t sval)
776 {
777 sval.value++;
778 return sval;
779 }
780
781 static sval_t sub_one(sval_t sval)
782 {
783 sval.value--;
784 return sval;
785 }
786
787 static void handle_comparison(struct symbol *type, struct expression *left, int op, struct expression *right)
788 {
789 struct range_list *left_orig;
790 struct range_list *left_true;
791 struct range_list *left_false;
792 struct range_list *right_orig;
793 struct range_list *right_true;
794 struct range_list *right_false;
795 struct smatch_state *left_true_state;
796 struct smatch_state *left_false_state;
797 struct smatch_state *right_true_state;
798 struct smatch_state *right_false_state;
799 sval_t min, max, dummy;
800 int left_postop = 0;
801 int right_postop = 0;
802
803 if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
804 if (left->type == EXPR_POSTOP) {
805 left->smatch_flags |= Handled;
806 left_postop = left->op;
807 }
808 left = strip_expr(left->unop);
809 }
810 while (left->type == EXPR_ASSIGNMENT)
811 left = strip_expr(left->left);
812
813 if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
814 if (right->type == EXPR_POSTOP) {
815 right->smatch_flags |= Handled;
816 right_postop = right->op;
817 }
818 right = strip_expr(right->unop);
819 }
820
821 if (get_implied_rl(left, &left_orig)) {
822 left_orig = cast_rl(type, left_orig);
823 } else {
824 min = sval_type_min(get_type(left));
825 max = sval_type_max(get_type(left));
826 left_orig = cast_rl(type, alloc_rl(min, max));
827 }
828
829 if (get_implied_rl(right, &right_orig)) {
830 right_orig = cast_rl(type, right_orig);
831 } else {
832 min = sval_type_min(get_type(right));
833 max = sval_type_max(get_type(right));
834 right_orig = cast_rl(type, alloc_rl(min, max));
835 }
836 min = sval_type_min(type);
837 max = sval_type_max(type);
838
839 left_true = clone_rl(left_orig);
840 left_false = clone_rl(left_orig);
841 right_true = clone_rl(right_orig);
842 right_false = clone_rl(right_orig);
843
844 switch (op) {
845 case '<':
846 case SPECIAL_UNSIGNED_LT:
847 left_true = remove_range(left_orig, rl_max(right_orig), max);
848 if (!sval_is_min(rl_min(right_orig))) {
849 left_false = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
850 }
851
852 right_true = remove_range(right_orig, min, rl_min(left_orig));
853 if (!sval_is_max(rl_max(left_orig)))
854 right_false = remove_range(right_orig, add_one(rl_max(left_orig)), max);
855 break;
856 case SPECIAL_UNSIGNED_LTE:
857 case SPECIAL_LTE:
858 if (!sval_is_max(rl_max(right_orig)))
859 left_true = remove_range(left_orig, add_one(rl_max(right_orig)), max);
860 left_false = remove_range(left_orig, min, rl_min(right_orig));
861
862 if (!sval_is_min(rl_min(left_orig)))
863 right_true = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
864 right_false = remove_range(right_orig, rl_max(left_orig), max);
865
866 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
867 left_false = remove_range(left_false, rl_min(left_orig), rl_min(left_orig));
868 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
869 right_false = remove_range(right_false, rl_max(left_orig), rl_max(left_orig));
870 break;
871 case SPECIAL_EQUAL:
872 if (!sval_is_max(rl_max(right_orig))) {
873 left_true = remove_range(left_true, add_one(rl_max(right_orig)), max);
874 }
875 if (!sval_is_min(rl_min(right_orig))) {
876 left_true = remove_range(left_true, min, sub_one(rl_min(right_orig)));
877 }
878 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
879 left_false = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
880
881 if (!sval_is_max(rl_max(left_orig)))
882 right_true = remove_range(right_true, add_one(rl_max(left_orig)), max);
883 if (!sval_is_min(rl_min(left_orig)))
884 right_true = remove_range(right_true, min, sub_one(rl_min(left_orig)));
885 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
886 right_false = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
887 break;
888 case SPECIAL_UNSIGNED_GTE:
889 case SPECIAL_GTE:
890 if (!sval_is_min(rl_min(right_orig)))
891 left_true = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
892 left_false = remove_range(left_orig, rl_max(right_orig), max);
893
894 if (!sval_is_max(rl_max(left_orig)))
895 right_true = remove_range(right_orig, add_one(rl_max(left_orig)), max);
896 right_false = remove_range(right_orig, min, rl_min(left_orig));
897
898 if (sval_cmp(rl_min(left_orig), rl_min(right_orig)) == 0)
899 right_false = remove_range(right_false, rl_min(left_orig), rl_min(left_orig));
900 if (sval_cmp(rl_max(left_orig), rl_max(right_orig)) == 0)
901 left_false = remove_range(left_false, rl_max(left_orig), rl_max(left_orig));
902 break;
903 case '>':
904 case SPECIAL_UNSIGNED_GT:
905 left_true = remove_range(left_orig, min, rl_min(right_orig));
906 if (!sval_is_max(rl_max(right_orig)))
907 left_false = remove_range(left_orig, add_one(rl_max(right_orig)), max);
908
909 right_true = remove_range(right_orig, rl_max(left_orig), max);
910 if (!sval_is_min(rl_min(left_orig)))
911 right_false = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
912 break;
913 case SPECIAL_NOTEQUAL:
914 if (!sval_is_max(rl_max(right_orig)))
915 left_false = remove_range(left_false, add_one(rl_max(right_orig)), max);
916 if (!sval_is_min(rl_min(right_orig)))
917 left_false = remove_range(left_false, min, sub_one(rl_min(right_orig)));
918 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
919 left_true = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
920
921 if (!sval_is_max(rl_max(left_orig)))
922 right_false = remove_range(right_false, add_one(rl_max(left_orig)), max);
923 if (!sval_is_min(rl_min(left_orig)))
924 right_false = remove_range(right_false, min, sub_one(rl_min(left_orig)));
925 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
926 right_true = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
927 break;
928 default:
929 return;
930 }
931
932 left_true = rl_truncate_cast(get_type(left), left_true);
933 left_false = rl_truncate_cast(get_type(left), left_false);
934 right_true = rl_truncate_cast(get_type(right), right_true);
935 right_false = rl_truncate_cast(get_type(right), right_false);
936
937 left_true_state = alloc_estate_rl(left_true);
938 left_false_state = alloc_estate_rl(left_false);
939 right_true_state = alloc_estate_rl(right_true);
940 right_false_state = alloc_estate_rl(right_false);
941
942 switch (op) {
943 case '<':
944 case SPECIAL_UNSIGNED_LT:
945 case SPECIAL_UNSIGNED_LTE:
946 case SPECIAL_LTE:
947 if (get_hard_max(right, &dummy))
948 estate_set_hard_max(left_true_state);
949 if (get_hard_max(left, &dummy))
950 estate_set_hard_max(right_false_state);
951 break;
952 case '>':
953 case SPECIAL_UNSIGNED_GT:
954 case SPECIAL_UNSIGNED_GTE:
955 case SPECIAL_GTE:
956 if (get_hard_max(left, &dummy))
957 estate_set_hard_max(right_true_state);
958 if (get_hard_max(right, &dummy))
959 estate_set_hard_max(left_false_state);
960 break;
961 }
962
963 if (get_hard_max(left, &dummy)) {
964 estate_set_hard_max(left_true_state);
965 estate_set_hard_max(left_false_state);
966 }
967 if (get_hard_max(right, &dummy)) {
968 estate_set_hard_max(right_true_state);
969 estate_set_hard_max(right_false_state);
970 }
971
972 if (left_postop == SPECIAL_INCREMENT) {
973 left_true_state = increment_state(left_true_state);
974 left_false_state = increment_state(left_false_state);
975 }
976 if (left_postop == SPECIAL_DECREMENT) {
977 left_true_state = decrement_state(left_true_state);
978 left_false_state = decrement_state(left_false_state);
979 }
980 if (right_postop == SPECIAL_INCREMENT) {
981 right_true_state = increment_state(right_true_state);
982 right_false_state = increment_state(right_false_state);
983 }
984 if (right_postop == SPECIAL_DECREMENT) {
985 right_true_state = decrement_state(right_true_state);
986 right_false_state = decrement_state(right_false_state);
987 }
988
989 set_extra_expr_true_false(left, left_true_state, left_false_state);
990 set_extra_expr_true_false(right, right_true_state, right_false_state);
991 }
992
993 static int opposite_op(int op)
994 {
995 switch (op) {
996 case '+':
997 return '-';
998 case '-':
999 return '+';
1000 }
1001 return 0;
1002 }
1003
1004 static int is_simple_math(struct expression *expr)
1005 {
1006 if (!expr)
1007 return 0;
1008 if (expr->type != EXPR_BINOP)
1009 return 0;
1010 if (!opposite_op(expr->op))
1011 return 0;
1012 return 1;
1013 }
1014
1015 static void move_known_values(struct expression **left_p, struct expression **right_p)
1016 {
1017 struct expression *left = *left_p;
1018 struct expression *right = *right_p;
1019 sval_t sval;
1020
1021 if (get_implied_value(left, &sval)) {
1022 if (!is_simple_math(right))
1023 return;
1024 if (right->op == '+' && get_value(right->left, &sval)) {
1025 *left_p = binop_expression(left, opposite_op(right->op), right->left);
1026 *right_p = right->right;
1027 return;
1028 }
1029 if (get_value(right->right, &sval)) {
1030 *left_p = binop_expression(left, opposite_op(right->op), right->right);
1031 *right_p = right->left;
1032 return;
1033 }
1034 return;
1035 }
1036 if (get_implied_value(right, &sval)) {
1037 if (!is_simple_math(left))
1038 return;
1039 if (left->op == '+' && get_value(left->left, &sval)) {
1040 *right_p = binop_expression(right, opposite_op(left->op), left->left);
1041 *left_p = left->right;
1042 return;
1043 }
1044
1045 if (get_value(left->right, &sval)) {
1046 *right_p = binop_expression(right, opposite_op(left->op), left->right);
1047 *left_p = left->left;
1048 return;
1049 }
1050 return;
1051 }
1052 }
1053
1054 static int match_func_comparison(struct expression *expr)
1055 {
1056 struct expression *left = strip_expr(expr->left);
1057 struct expression *right = strip_expr(expr->right);
1058 sval_t sval;
1059
1060 /*
1061 * fixme: think about this harder. We should always be trying to limit
1062 * the non-call side as well. If we can't determine the limitter does
1063 * that mean we aren't querying the database and are missing important
1064 * information?
1065 */
1066
1067 if (left->type == EXPR_CALL) {
1068 if (get_implied_value(left, &sval)) {
1069 handle_comparison(get_type(expr), left, expr->op, right);
1070 return 1;
1071 }
1072 if (!get_implied_value(right, &sval))
1073 return 1;
1074 function_comparison(expr->op, left, sval, 1);
1075 return 1;
1076 }
1077
1078 if (right->type == EXPR_CALL) {
1079 if (get_implied_value(right, &sval)) {
1080 handle_comparison(get_type(expr), left, expr->op, right);
1081 return 1;
1082 }
1083 if (!get_implied_value(left, &sval))
1084 return 1;
1085 function_comparison(expr->op, right, sval, 0);
1086 return 1;
1087 }
1088
1089 return 0;
1090 }
1091
1092 static void match_comparison(struct expression *expr)
1093 {
1094 struct expression *left_orig = strip_expr(expr->left);
1095 struct expression *right_orig = strip_expr(expr->right);
1096 struct expression *left, *right;
1097 struct expression *prev;
1098 struct symbol *type;
1099
1100 if (match_func_comparison(expr))
1101 return;
1102
1103 type = get_type(expr);
1104 if (!type)
1105 type = &llong_ctype;
1106
1107 left = left_orig;
1108 right = right_orig;
1109 move_known_values(&left, &right);
1110 handle_comparison(type, left, expr->op, right);
1111
1112 prev = get_assigned_expr(left_orig);
1113 if (is_simple_math(prev) && has_variable(prev, left_orig) == 0) {
1114 left = prev;
1115 right = right_orig;
1116 move_known_values(&left, &right);
1117 handle_comparison(type, left, expr->op, right);
1118 }
1119
1120 prev = get_assigned_expr(right_orig);
1121 if (is_simple_math(prev) && has_variable(prev, right_orig) == 0) {
1122 left = left_orig;
1123 right = prev;
1124 move_known_values(&left, &right);
1125 handle_comparison(type, left, expr->op, right);
1126 }
1127 }
1128
1129 static void handle_AND_condition(struct expression *expr)
1130 {
1131 struct range_list *rl = NULL;
1132 sval_t known;
1133
1134 if (get_implied_value(expr->left, &known) && known.value > 0) {
1135 known.value--;
1136 get_absolute_rl(expr->right, &rl);
1137 rl = remove_range(rl, sval_type_val(known.type, 0), known);
1138 set_extra_expr_true_false(expr->right, alloc_estate_rl(rl), NULL);
1139 return;
1140 }
1141
1142 if (get_implied_value(expr->right, &known) && known.value > 0) {
1143 known.value--;
1144 get_absolute_rl(expr->left, &rl);
1145 rl = remove_range(rl, sval_type_val(known.type, 0), known);
1146 set_extra_expr_true_false(expr->left, alloc_estate_rl(rl), NULL);
1147 return;
1148 }
1149 }
1150
1151 /* this is actually hooked from smatch_implied.c... it's hacky, yes */
1152 void __extra_match_condition(struct expression *expr)
1153 {
1154 struct symbol *sym;
1155 char *name;
1156 struct smatch_state *pre_state;
1157 struct smatch_state *true_state;
1158 struct smatch_state *false_state;
1159
1160 expr = strip_expr(expr);
1161 switch (expr->type) {
1162 case EXPR_CALL:
1163 function_comparison(SPECIAL_NOTEQUAL, expr, ll_to_sval(0), 1);
1164 return;
1165 case EXPR_PREOP:
1166 case EXPR_SYMBOL:
1167 case EXPR_DEREF: {
1168 sval_t zero;
1169
1170 zero = sval_blank(expr);
1171 zero.value = 0;
1172
1173 name = expr_to_var_sym(expr, &sym);
1174 if (!name)
1175 return;
1176 pre_state = get_state(my_id, name, sym);
1177 true_state = estate_filter_sval(pre_state, zero);
1178 if (possibly_true(expr, SPECIAL_EQUAL, zero_expr()))
1179 false_state = alloc_estate_sval(zero);
1180 else
1181 false_state = alloc_estate_empty();
1182 set_extra_true_false(name, sym, true_state, false_state);
1183 free_string(name);
1184 return;
1185 }
1186 case EXPR_COMPARE:
1187 match_comparison(expr);
1188 return;
1189 case EXPR_ASSIGNMENT:
1190 __extra_match_condition(expr->left);
1191 return;
1192 case EXPR_BINOP:
1193 if (expr->op == '&')
1194 handle_AND_condition(expr);
1195 return;
1196 }
1197 }
1198
1199 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
1200 int implied_not_equal(struct expression *expr, long long val)
1201 {
1202 return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
1203 }
1204
1205 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct smatch_state *state)
1206 {
1207 if (estate_is_whole(state))
1208 return;
1209 sql_insert_caller_info(call, PARAM_VALUE, param, printed_name, state->name);
1210 }
1211
1212 static void db_limited_before(void)
1213 {
1214 unmatched_slist = clone_slist(__get_cur_slist());
1215 }
1216
1217 static void db_limited_after(void)
1218 {
1219 free_slist(&unmatched_slist);
1220 }
1221
1222 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value, int mod)
1223 {
1224 struct expression *arg;
1225 char *name;
1226 struct symbol *sym;
1227 struct sm_state *sm;
1228 struct symbol *type;
1229 struct range_list *rl;
1230 struct range_list *limit;
1231 struct range_list *new;
1232
1233 while (expr->type == EXPR_ASSIGNMENT)
1234 expr = strip_expr(expr->right);
1235 if (expr->type != EXPR_CALL)
1236 return;
1237
1238 arg = get_argument_from_call_expr(expr->args, param);
1239 if (!arg)
1240 return;
1241
1242 name = get_variable_from_key(arg, key, &sym);
1243 if (!name || !sym)
1244 goto free;
1245
1246 sm = get_sm_state(SMATCH_EXTRA, name, sym);
1247 type = get_member_type_from_key(arg, key);
1248 if (sm)
1249 rl = estate_rl(sm->state);
1250 else
1251 rl = alloc_whole_rl(type);
1252
1253 call_results_to_rl(expr, type, value, &limit);
1254 new = rl_intersection(rl, limit);
1255
1256 /* We want to preserve the implications here */
1257 if (sm && rl_equiv(estate_rl(sm->state), new)) {
1258 __set_sm(sm);
1259 } else {
1260 if (mod)
1261 set_extra_mod(name, sym, alloc_estate_rl(new));
1262 else
1263 set_extra_nomod(name, sym, alloc_estate_rl(new));
1264 }
1265
1266 free:
1267 free_string(name);
1268 }
1269
1270 static void db_param_limit(struct expression *expr, int param, char *key, char *value)
1271 {
1272 db_param_limit_filter(expr, param, key, value, 0);
1273 }
1274
1275 static void db_param_filter(struct expression *expr, int param, char *key, char *value)
1276 {
1277 db_param_limit_filter(expr, param, key, value, 1);
1278 }
1279
1280 static void db_param_add(struct expression *expr, int param, char *key, char *value)
1281 {
1282 struct expression *arg;
1283 char *name;
1284 struct symbol *sym;
1285 struct symbol *type;
1286 struct smatch_state *state;
1287 struct range_list *added = NULL;
1288 struct range_list *new;
1289
1290 while (expr->type == EXPR_ASSIGNMENT)
1291 expr = strip_expr(expr->right);
1292 if (expr->type != EXPR_CALL)
1293 return;
1294
1295 arg = get_argument_from_call_expr(expr->args, param);
1296 if (!arg)
1297 return;
1298 name = get_variable_from_key(arg, key, &sym);
1299 if (!name || !sym)
1300 goto free;
1301
1302 type = get_member_type_from_key(arg, key);
1303 state = get_state(SMATCH_EXTRA, name, sym);
1304 if (state) {
1305 call_results_to_rl(expr, type, value, &added);
1306 new = rl_union(estate_rl(state), added);
1307 } else {
1308 new = alloc_whole_rl(type);
1309 }
1310
1311 set_extra_mod(name, sym, alloc_estate_rl(new));
1312 free:
1313 free_string(name);
1314 }
1315
1316 static void db_returned_member_info(struct expression *expr, int param, char *key, char *value)
1317 {
1318 struct symbol *type;
1319 struct symbol *sym;
1320 char *name;
1321 char member_name[256];
1322 struct range_list *rl;
1323
1324 if (expr->type != EXPR_ASSIGNMENT)
1325 return;
1326
1327 name = expr_to_var_sym(expr->left, &sym);
1328 if (!name || !sym)
1329 goto free;
1330 snprintf(member_name, sizeof(member_name), "%s%s", name, key + 2);
1331 type = get_member_type_from_key(expr->left, key);
1332 if (!type)
1333 return;
1334 call_results_to_rl(expr->right, type, value, &rl);
1335 set_extra_mod(member_name, sym, alloc_estate_rl(rl));
1336
1337 free:
1338 free_string(name);
1339 }
1340
1341 static void returned_member_callback(int return_id, char *return_ranges, char *printed_name, struct smatch_state *state)
1342 {
1343 if (estate_is_whole(state))
1344 return;
1345
1346 sql_insert_return_states(return_id, return_ranges, RETURN_VALUE, -1,
1347 printed_name, state->name);
1348 }
1349
1350 static void match_call_info(struct expression *expr)
1351 {
1352 struct range_list *rl = NULL;
1353 struct expression *arg;
1354 struct symbol *type;
1355 int i = 0;
1356
1357 FOR_EACH_PTR(expr->args, arg) {
1358 type = get_arg_type(expr->fn, i);
1359
1360 if (get_implied_rl(arg, &rl))
1361 rl = cast_rl(type, rl);
1362 else
1363 rl = cast_rl(type, alloc_whole_rl(get_type(arg)));
1364
1365 sql_insert_caller_info(expr, PARAM_VALUE, i, "$$", show_rl(rl));
1366 i++;
1367 } END_FOR_EACH_PTR(arg);
1368 }
1369
1370 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
1371 {
1372 struct range_list *rl = NULL;
1373 struct smatch_state *state;
1374 struct symbol *type;
1375 char fullname[256];
1376
1377 if (strcmp(key, "*$$") == 0)
1378 snprintf(fullname, sizeof(fullname), "*%s", name);
1379 else if (strncmp(key, "$$", 2) == 0)
1380 snprintf(fullname, 256, "%s%s", name, key + 2);
1381 else
1382 return;
1383
1384 type = get_member_type_from_key(symbol_expression(sym), key);
1385 str_to_rl(type, value, &rl);
1386 state = alloc_estate_rl(rl);
1387 set_state(SMATCH_EXTRA, fullname, sym, state);
1388 }
1389
1390 void register_smatch_extra(int id)
1391 {
1392 my_id = id;
1393
1394 add_merge_hook(my_id, &merge_estates);
1395 add_unmatched_state_hook(my_id, &unmatched_state);
1396 add_hook(&match_function_def, FUNC_DEF_HOOK);
1397 add_hook(&match_declarations, DECLARATION_HOOK);
1398 select_caller_info_hook(set_param_value, PARAM_VALUE);
1399 select_return_states_hook(RETURN_VALUE, &db_returned_member_info);
1400 select_return_states_before(&db_limited_before);
1401 select_return_states_hook(LIMITED_VALUE, &db_param_limit);
1402 select_return_states_hook(FILTER_VALUE, &db_param_filter);
1403 select_return_states_hook(ADDED_VALUE, &db_param_add);
1404 select_return_states_after(&db_limited_after);
1405 }
1406
1407 void register_smatch_extra_late(int id)
1408 {
1409 add_hook(&match_dereferences, DEREF_HOOK);
1410 add_hook(&match_pointer_as_array, OP_HOOK);
1411 select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);
1412 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
1413 add_hook(&match_assign, ASSIGNMENT_HOOK);
1414 add_hook(&unop_expr, OP_HOOK);
1415 add_hook(&asm_expr, ASM_HOOK);
1416
1417 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1418 add_member_info_callback(my_id, struct_member_callback);
1419 add_returned_member_callback(my_id, returned_member_callback);
1420 }
Static analysis for C