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implied: introduce impossible_assumption()
[smatch.git] / smatch_extra.c
blob8d1fd82cd8a0946a50bacdf33437e102e20f5807
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 #define _GNU_SOURCE
24 #include <string.h>
25
26 #include <stdlib.h>
27 #include <errno.h>
28 #ifndef __USE_ISOC99
29 #define __USE_ISOC99
30 #endif
31 #include <limits.h>
32 #include "parse.h"
33 #include "smatch.h"
34 #include "smatch_slist.h"
35 #include "smatch_extra.h"
36
37 static int my_id;
38 static int link_id;
39
40 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr);
41
42 struct string_list *__ignored_macros = NULL;
43 static int in_warn_on_macro(void)
44 {
45 struct statement *stmt;
46 char *tmp;
47 char *macro;
48
49 stmt = get_current_statement();
50 if (!stmt)
51 return 0;
52 macro = get_macro_name(stmt->pos);
53 if (!macro)
54 return 0;
55
56 FOR_EACH_PTR(__ignored_macros, tmp) {
57 if (!strcmp(tmp, macro))
58 return 1;
59 } END_FOR_EACH_PTR(tmp);
60 return 0;
61 }
62
63 typedef void (mod_hook)(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state);
64 DECLARE_PTR_LIST(void_fn_list, mod_hook *);
65 static struct void_fn_list *extra_mod_hooks;
66 static struct void_fn_list *extra_nomod_hooks;
67
68 void add_extra_mod_hook(mod_hook *fn)
69 {
70 mod_hook **p = malloc(sizeof(mod_hook *));
71 *p = fn;
72 add_ptr_list(&extra_mod_hooks, p);
73 }
74
75 void add_extra_nomod_hook(mod_hook *fn)
76 {
77 mod_hook **p = malloc(sizeof(mod_hook *));
78 *p = fn;
79 add_ptr_list(&extra_nomod_hooks, p);
80 }
81
82 void call_extra_hooks(struct void_fn_list *hooks, const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
83 {
84 mod_hook **fn;
85
86 FOR_EACH_PTR(hooks, fn) {
87 (*fn)(name, sym, expr, state);
88 } END_FOR_EACH_PTR(fn);
89 }
90
91 void call_extra_mod_hooks(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
92 {
93 call_extra_hooks(extra_mod_hooks, name, sym, expr, state);
94 }
95
96 void call_extra_nomod_hooks(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
97 {
98 call_extra_hooks(extra_nomod_hooks, name, sym, expr, state);
99 }
100
101 static bool in_param_set;
102 static void set_extra_mod_helper(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
103 {
104 remove_from_equiv(name, sym);
105 call_extra_mod_hooks(name, sym, expr, state);
106 if ((__in_fake_assign || in_param_set) &&
107 estate_is_unknown(state) && !get_state(SMATCH_EXTRA, name, sym))
108 return;
109 set_state(SMATCH_EXTRA, name, sym, state);
110 }
111
112 static void set_extra_nomod_helper(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
113 {
114 call_extra_nomod_hooks(name, sym, expr, state);
115 set_state(SMATCH_EXTRA, name, sym, state);
116 }
117
118 static char *get_pointed_at(const char *name, struct symbol *sym, struct symbol **new_sym)
119 {
120 struct expression *assigned;
121
122 if (name[0] != '*')
123 return NULL;
124 if (strcmp(name + 1, sym->ident->name) != 0)
125 return NULL;
126
127 assigned = get_assigned_expr_name_sym(sym->ident->name, sym);
128 if (!assigned)
129 return NULL;
130 assigned = strip_parens(assigned);
131 if (assigned->type != EXPR_PREOP || assigned->op != '&')
132 return NULL;
133
134 return expr_to_var_sym(assigned->unop, new_sym);
135 }
136
137 char *get_other_name_sym(const char *name, struct symbol *sym, struct symbol **new_sym)
138 {
139 struct expression *assigned;
140 char *orig_name = NULL;
141 char buf[256];
142 char *ret = NULL;
143 int skip;
144
145 *new_sym = NULL;
146
147 if (!sym || !sym->ident)
148 return NULL;
149
150 ret = get_pointed_at(name, sym, new_sym);
151 if (ret)
152 return ret;
153
154 skip = strlen(sym->ident->name);
155 if (name[skip] != '-' || name[skip + 1] != '>')
156 return NULL;
157 skip += 2;
158
159 assigned = get_assigned_expr_name_sym(sym->ident->name, sym);
160 if (!assigned)
161 return NULL;
162 if (assigned->type == EXPR_CALL)
163 return map_call_to_other_name_sym(name, sym, new_sym);
164 if (assigned->type == EXPR_PREOP || assigned->op == '&') {
165
166 orig_name = expr_to_var_sym(assigned, new_sym);
167 if (!orig_name || !*new_sym)
168 goto free;
169
170 snprintf(buf, sizeof(buf), "%s.%s", orig_name + 1, name + skip);
171 ret = alloc_string(buf);
172 free_string(orig_name);
173 return ret;
174 }
175
176 if (assigned->type != EXPR_DEREF)
177 goto free;
178
179 orig_name = expr_to_var_sym(assigned, new_sym);
180 if (!orig_name || !*new_sym)
181 goto free;
182
183 snprintf(buf, sizeof(buf), "%s->%s", orig_name, name + skip);
184 ret = alloc_string(buf);
185 free_string(orig_name);
186 return ret;
187
188 free:
189 free_string(orig_name);
190 return NULL;
191 }
192
193 void set_extra_mod(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
194 {
195 char *new_name;
196 struct symbol *new_sym;
197
198 set_extra_mod_helper(name, sym, expr, state);
199 new_name = get_other_name_sym(name, sym, &new_sym);
200 if (new_name && new_sym)
201 set_extra_mod_helper(new_name, new_sym, expr, state);
202 free_string(new_name);
203 }
204
205 static struct expression *chunk_get_array_base(struct expression *expr)
206 {
207 /*
208 * The problem with is_array() is that it only returns true for things
209 * like foo[1] but not for foo[1].bar.
210 *
211 */
212 expr = strip_expr(expr);
213 while (expr && expr->type == EXPR_DEREF)
214 expr = strip_expr(expr->deref);
215 return get_array_base(expr);
216 }
217
218 static int chunk_has_array(struct expression *expr)
219 {
220 return !!chunk_get_array_base(expr);
221 }
222
223 static void clear_array_states(struct expression *array)
224 {
225 struct sm_state *sm;
226
227 sm = get_sm_state_expr(link_id, array);
228 if (sm)
229 match_link_modify(sm, NULL);
230 }
231
232 static void set_extra_array_mod(struct expression *expr, struct smatch_state *state)
233 {
234 struct expression *array;
235 struct var_sym_list *vsl;
236 struct var_sym *vs;
237 char *name;
238 struct symbol *sym;
239
240 array = chunk_get_array_base(expr);
241
242 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
243 if (!name || !vsl) {
244 clear_array_states(array);
245 goto free;
246 }
247
248 FOR_EACH_PTR(vsl, vs) {
249 store_link(link_id, vs->var, vs->sym, name, sym);
250 } END_FOR_EACH_PTR(vs);
251
252 call_extra_mod_hooks(name, sym, expr, state);
253 set_state(SMATCH_EXTRA, name, sym, state);
254 free:
255 free_string(name);
256 }
257
258 void set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
259 {
260 struct symbol *sym;
261 char *name;
262
263 if (chunk_has_array(expr)) {
264 set_extra_array_mod(expr, state);
265 return;
266 }
267
268 expr = strip_expr(expr);
269 name = expr_to_var_sym(expr, &sym);
270 if (!name || !sym)
271 goto free;
272 set_extra_mod(name, sym, expr, state);
273 free:
274 free_string(name);
275 }
276
277 void set_extra_nomod(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
278 {
279 char *new_name;
280 struct symbol *new_sym;
281 struct relation *rel;
282 struct smatch_state *orig_state;
283
284 orig_state = get_state(SMATCH_EXTRA, name, sym);
285
286 /* don't save unknown states if leaving it blank is the same */
287 if (!orig_state && estate_is_unknown(state))
288 return;
289
290 new_name = get_other_name_sym(name, sym, &new_sym);
291 if (new_name && new_sym)
292 set_extra_nomod_helper(new_name, new_sym, expr, state);
293 free_string(new_name);
294
295 if (!estate_related(orig_state)) {
296 set_extra_nomod_helper(name, sym, expr, state);
297 return;
298 }
299
300 set_related(state, estate_related(orig_state));
301 FOR_EACH_PTR(estate_related(orig_state), rel) {
302 struct smatch_state *estate;
303
304 if (option_debug_related)
305 sm_msg("%s updating related %s to %s", name, rel->name, state->name);
306 estate = get_state(SMATCH_EXTRA, rel->name, rel->sym);
307 if (!estate)
308 continue;
309 set_extra_nomod_helper(rel->name, rel->sym, expr, clone_estate_cast(estate_type(estate), state));
310 } END_FOR_EACH_PTR(rel);
311 }
312
313 void set_extra_nomod_vsl(const char *name, struct symbol *sym, struct var_sym_list *vsl, struct expression *expr, struct smatch_state *state)
314 {
315 struct var_sym *vs;
316
317 FOR_EACH_PTR(vsl, vs) {
318 store_link(link_id, vs->var, vs->sym, name, sym);
319 } END_FOR_EACH_PTR(vs);
320
321 set_extra_nomod(name, sym, expr, state);
322 }
323
324 /*
325 * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
326 */
327 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
328 {
329 struct var_sym_list *vsl;
330 struct var_sym *vs;
331 char *name;
332 struct symbol *sym;
333
334 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
335 if (!name || !vsl)
336 goto free;
337 FOR_EACH_PTR(vsl, vs) {
338 store_link(link_id, vs->var, vs->sym, name, sym);
339 } END_FOR_EACH_PTR(vs);
340
341 set_extra_nomod(name, sym, expr, state);
342 free:
343 free_string(name);
344 }
345
346 static void set_extra_true_false(const char *name, struct symbol *sym,
347 struct smatch_state *true_state,
348 struct smatch_state *false_state)
349 {
350 char *new_name;
351 struct symbol *new_sym;
352 struct relation *rel;
353 struct smatch_state *orig_state;
354
355 if (!true_state && !false_state)
356 return;
357
358 if (in_warn_on_macro())
359 return;
360
361 new_name = get_other_name_sym(name, sym, &new_sym);
362 if (new_name && new_sym)
363 set_true_false_states(SMATCH_EXTRA, new_name, new_sym, true_state, false_state);
364 free_string(new_name);
365
366 orig_state = get_state(SMATCH_EXTRA, name, sym);
367
368 if (!estate_related(orig_state)) {
369 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
370 return;
371 }
372
373 if (true_state)
374 set_related(true_state, estate_related(orig_state));
375 if (false_state)
376 set_related(false_state, estate_related(orig_state));
377
378 FOR_EACH_PTR(estate_related(orig_state), rel) {
379 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
380 true_state, false_state);
381 } END_FOR_EACH_PTR(rel);
382 }
383
384 static void set_extra_chunk_true_false(struct expression *expr,
385 struct smatch_state *true_state,
386 struct smatch_state *false_state)
387 {
388 struct var_sym_list *vsl;
389 struct var_sym *vs;
390 struct symbol *type;
391 char *name;
392 struct symbol *sym;
393
394 if (in_warn_on_macro())
395 return;
396
397 type = get_type(expr);
398 if (!type)
399 return;
400
401 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
402 if (!name || !vsl)
403 goto free;
404 FOR_EACH_PTR(vsl, vs) {
405 store_link(link_id, vs->var, vs->sym, name, sym);
406 } END_FOR_EACH_PTR(vs);
407
408 set_true_false_states(SMATCH_EXTRA, name, sym,
409 clone_estate(true_state),
410 clone_estate(false_state));
411 free:
412 free_string(name);
413 }
414
415 static void set_extra_expr_true_false(struct expression *expr,
416 struct smatch_state *true_state,
417 struct smatch_state *false_state)
418 {
419 char *name;
420 struct symbol *sym;
421 sval_t sval;
422
423 if (!true_state && !false_state)
424 return;
425
426 if (get_value(expr, &sval))
427 return;
428
429 expr = strip_expr(expr);
430 name = expr_to_var_sym(expr, &sym);
431 if (!name || !sym) {
432 free_string(name);
433 set_extra_chunk_true_false(expr, true_state, false_state);
434 return;
435 }
436 set_extra_true_false(name, sym, true_state, false_state);
437 free_string(name);
438 }
439
440 static int get_countdown_info(struct expression *condition, struct expression **unop, int *op, sval_t *right)
441 {
442 struct expression *unop_expr;
443 int comparison;
444 sval_t limit;
445
446 right->type = &int_ctype;
447 right->value = 0;
448
449 condition = strip_expr(condition);
450
451 if (condition->type == EXPR_COMPARE) {
452 comparison = remove_unsigned_from_comparison(condition->op);
453
454 if (comparison != SPECIAL_GTE && comparison != '>')
455 return 0;
456 if (!get_value(condition->right, &limit))
457 return 0;
458
459 unop_expr = condition->left;
460 if (unop_expr->type != EXPR_PREOP && unop_expr->type != EXPR_POSTOP)
461 return 0;
462 if (unop_expr->op != SPECIAL_DECREMENT)
463 return 0;
464
465 *unop = unop_expr;
466 *op = comparison;
467 *right = limit;
468
469 return 1;
470 }
471
472 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
473 return 0;
474 if (condition->op != SPECIAL_DECREMENT)
475 return 0;
476
477 *unop = condition;
478 *op = '>';
479
480 return 1;
481 }
482
483 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
484 {
485 struct expression *iter_var;
486 struct expression *condition, *unop;
487 struct sm_state *sm;
488 struct smatch_state *estate;
489 int op;
490 sval_t start, right;
491
492 right.type = &int_ctype;
493 right.value = 0;
494
495 condition = strip_expr(loop->iterator_pre_condition);
496 if (!condition)
497 return NULL;
498
499 if (!get_countdown_info(condition, &unop, &op, &right))
500 return NULL;
501
502 iter_var = unop->unop;
503
504 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
505 if (!sm)
506 return NULL;
507 if (sval_cmp(estate_min(sm->state), right) < 0)
508 return NULL;
509 start = estate_max(sm->state);
510 if (sval_cmp(start, right) <= 0)
511 return NULL;
512 if (!sval_is_max(start))
513 start.value--;
514
515 if (op == SPECIAL_GTE)
516 right.value--;
517
518 if (unop->type == EXPR_PREOP) {
519 right.value++;
520 estate = alloc_estate_range(right, start);
521 if (estate_has_hard_max(sm->state))
522 estate_set_hard_max(estate);
523 estate_copy_fuzzy_max(estate, sm->state);
524 set_extra_expr_mod(iter_var, estate);
525 }
526 if (unop->type == EXPR_POSTOP) {
527 estate = alloc_estate_range(right, start);
528 if (estate_has_hard_max(sm->state))
529 estate_set_hard_max(estate);
530 estate_copy_fuzzy_max(estate, sm->state);
531 set_extra_expr_mod(iter_var, estate);
532 }
533 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
534 }
535
536 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
537 struct expression *condition)
538 {
539 struct expression *iter_var;
540 struct sm_state *sm;
541 struct smatch_state *estate;
542 sval_t start, end, max;
543
544 iter_var = iter_expr->unop;
545 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
546 if (!sm)
547 return NULL;
548 if (!estate_get_single_value(sm->state, &start))
549 return NULL;
550 if (get_implied_max(condition->right, &end))
551 end = sval_cast(get_type(iter_var), end);
552 else
553 end = sval_type_max(get_type(iter_var));
554
555 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
556 return NULL;
557
558 switch (condition->op) {
559 case SPECIAL_UNSIGNED_LT:
560 case SPECIAL_NOTEQUAL:
561 case '<':
562 if (!sval_is_min(end))
563 end.value--;
564 break;
565 case SPECIAL_UNSIGNED_LTE:
566 case SPECIAL_LTE:
567 break;
568 default:
569 return NULL;
570 }
571 if (sval_cmp(end, start) < 0)
572 return NULL;
573 estate = alloc_estate_range(start, end);
574 if (get_hard_max(condition->right, &max)) {
575 estate_set_hard_max(estate);
576 if (condition->op == '<' ||
577 condition->op == SPECIAL_UNSIGNED_LT ||
578 condition->op == SPECIAL_NOTEQUAL)
579 max.value--;
580 estate_set_fuzzy_max(estate, max);
581 }
582 set_extra_expr_mod(iter_var, estate);
583 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
584 }
585
586 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
587 struct expression *condition)
588 {
589 struct expression *iter_var;
590 struct sm_state *sm;
591 struct smatch_state *estate;
592 sval_t start, end;
593
594 iter_var = iter_expr->unop;
595 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
596 if (!sm)
597 return NULL;
598 if (!estate_get_single_value(sm->state, &start))
599 return NULL;
600 if (!get_implied_min(condition->right, &end))
601 end = sval_type_min(get_type(iter_var));
602 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
603 return NULL;
604
605 switch (condition->op) {
606 case SPECIAL_NOTEQUAL:
607 case '>':
608 if (!sval_is_min(end) && !sval_is_max(end))
609 end.value++;
610 break;
611 case SPECIAL_GTE:
612 break;
613 default:
614 return NULL;
615 }
616 if (sval_cmp(end, start) > 0)
617 return NULL;
618 estate = alloc_estate_range(end, start);
619 estate_set_hard_max(estate);
620 estate_set_fuzzy_max(estate, estate_get_fuzzy_max(estate));
621 set_extra_expr_mod(iter_var, estate);
622 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
623 }
624
625 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
626 {
627 struct expression *iter_expr;
628 struct expression *condition;
629
630 if (!loop->iterator_post_statement)
631 return NULL;
632 if (loop->iterator_post_statement->type != STMT_EXPRESSION)
633 return NULL;
634 iter_expr = loop->iterator_post_statement->expression;
635 if (!loop->iterator_pre_condition)
636 return NULL;
637 if (loop->iterator_pre_condition->type != EXPR_COMPARE)
638 return NULL;
639 condition = loop->iterator_pre_condition;
640
641 if (iter_expr->op == SPECIAL_INCREMENT)
642 return handle_canonical_for_inc(iter_expr, condition);
643 if (iter_expr->op == SPECIAL_DECREMENT)
644 return handle_canonical_for_dec(iter_expr, condition);
645 return NULL;
646 }
647
648 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct stree **stree)
649 {
650 struct sm_state *ret;
651
652 /*
653 * Canonical loops are a hack. The proper way to handle this is to
654 * use two passes, but unfortunately, doing two passes makes parsing
655 * code twice as slow.
656 *
657 * What we do is we set the inside state here, which overwrites whatever
658 * __extra_match_condition() does. Then we set the outside state in
659 * __extra_pre_loop_hook_after().
660 *
661 */
662 __push_fake_cur_stree();
663 if (!loop->iterator_post_statement)
664 ret = handle_canonical_while_count_down(loop);
665 else
666 ret = handle_canonical_for_loops(loop);
667 *stree = __pop_fake_cur_stree();
668 return ret;
669 }
670
671 int __iterator_unchanged(struct sm_state *sm)
672 {
673 if (!sm)
674 return 0;
675 if (get_sm_state(my_id, sm->name, sm->sym) == sm)
676 return 1;
677 return 0;
678 }
679
680 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
681 {
682 struct expression *unop;
683 int op;
684 sval_t limit, after_value;
685
686 if (!get_countdown_info(condition, &unop, &op, &limit))
687 return;
688 after_value = estate_min(sm->state);
689 after_value.value--;
690 set_extra_mod(sm->name, sm->sym, condition->unop, alloc_estate_sval(after_value));
691 }
692
693 void __extra_pre_loop_hook_after(struct sm_state *sm,
694 struct statement *iterator,
695 struct expression *condition)
696 {
697 struct expression *iter_expr;
698 sval_t limit;
699 struct smatch_state *state;
700
701 if (!iterator) {
702 while_count_down_after(sm, condition);
703 return;
704 }
705
706 iter_expr = iterator->expression;
707
708 if (condition->type != EXPR_COMPARE)
709 return;
710 if (iter_expr->op == SPECIAL_INCREMENT) {
711 limit = sval_binop(estate_max(sm->state), '+',
712 sval_type_val(estate_type(sm->state), 1));
713 } else {
714 limit = sval_binop(estate_min(sm->state), '-',
715 sval_type_val(estate_type(sm->state), 1));
716 }
717 if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
718 if (iter_expr->op == SPECIAL_INCREMENT)
719 state = alloc_estate_range(estate_min(sm->state), limit);
720 else
721 state = alloc_estate_range(limit, estate_max(sm->state));
722 } else {
723 state = alloc_estate_sval(limit);
724 }
725 if (!estate_has_hard_max(sm->state)) {
726 estate_clear_hard_max(state);
727 }
728 if (estate_has_fuzzy_max(sm->state)) {
729 sval_t hmax = estate_get_fuzzy_max(sm->state);
730 sval_t max = estate_max(sm->state);
731
732 if (sval_cmp(hmax, max) != 0)
733 estate_clear_fuzzy_max(state);
734 } else if (!estate_has_fuzzy_max(sm->state)) {
735 estate_clear_fuzzy_max(state);
736 }
737
738 set_extra_mod(sm->name, sm->sym, iter_expr, state);
739 }
740
741 static struct stree *unmatched_stree;
742 static struct smatch_state *unmatched_state(struct sm_state *sm)
743 {
744 struct smatch_state *state;
745
746 if (unmatched_stree) {
747 state = get_state_stree(unmatched_stree, SMATCH_EXTRA, sm->name, sm->sym);
748 if (state)
749 return state;
750 }
751 if (parent_is_gone_var_sym(sm->name, sm->sym))
752 return alloc_estate_empty();
753 return alloc_estate_whole(estate_type(sm->state));
754 }
755
756 static void clear_the_pointed_at(struct expression *expr)
757 {
758 struct stree *stree;
759 char *name;
760 struct symbol *sym;
761 struct sm_state *tmp;
762
763 name = expr_to_var_sym(expr, &sym);
764 if (!name || !sym)
765 goto free;
766
767 stree = __get_cur_stree();
768 FOR_EACH_MY_SM(SMATCH_EXTRA, stree, tmp) {
769 if (tmp->name[0] != '*')
770 continue;
771 if (tmp->sym != sym)
772 continue;
773 if (strcmp(tmp->name + 1, name) != 0)
774 continue;
775 set_extra_mod(tmp->name, tmp->sym, expr, alloc_estate_whole(estate_type(tmp->state)));
776 } END_FOR_EACH_SM(tmp);
777
778 free:
779 free_string(name);
780 }
781
782 static int is_const_param(struct expression *expr, int param)
783 {
784 struct symbol *type;
785
786 type = get_arg_type(expr, param);
787 if (!type)
788 return 0;
789 if (type->ctype.modifiers & MOD_CONST)
790 return 1;
791 return 0;
792 }
793
794 static void match_function_call(struct expression *expr)
795 {
796 struct expression *arg;
797 struct expression *tmp;
798 int param = -1;
799
800 /* if we have the db this is handled in smatch_function_hooks.c */
801 if (!option_no_db)
802 return;
803 if (inlinable(expr->fn))
804 return;
805
806 FOR_EACH_PTR(expr->args, arg) {
807 param++;
808 if (is_const_param(expr->fn, param))
809 continue;
810 tmp = strip_expr(arg);
811 if (tmp->type == EXPR_PREOP && tmp->op == '&')
812 set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
813 else
814 clear_the_pointed_at(tmp);
815 } END_FOR_EACH_PTR(arg);
816 }
817
818 static int values_fit_type(struct expression *left, struct expression *right)
819 {
820 struct range_list *rl;
821 struct symbol *type;
822
823 type = get_type(left);
824 if (!type)
825 return 0;
826 get_absolute_rl(right, &rl);
827 if (type_unsigned(type) && sval_is_negative(rl_min(rl)))
828 return 0;
829 if (sval_cmp(sval_type_min(type), rl_min(rl)) > 0)
830 return 0;
831 if (sval_cmp(sval_type_max(type), rl_max(rl)) < 0)
832 return 0;
833 return 1;
834 }
835
836 static void save_chunk_info(struct expression *left, struct expression *right)
837 {
838 struct var_sym_list *vsl;
839 struct var_sym *vs;
840 struct expression *add_expr;
841 struct symbol *type;
842 sval_t sval;
843 char *name;
844 struct symbol *sym;
845
846 if (right->type != EXPR_BINOP || right->op != '-')
847 return;
848 if (!get_value(right->left, &sval))
849 return;
850 if (!expr_to_sym(right->right))
851 return;
852
853 add_expr = binop_expression(left, '+', right->right);
854 type = get_type(add_expr);
855 if (!type)
856 return;
857 name = expr_to_chunk_sym_vsl(add_expr, &sym, &vsl);
858 if (!name || !vsl)
859 goto free;
860 FOR_EACH_PTR(vsl, vs) {
861 store_link(link_id, vs->var, vs->sym, name, sym);
862 } END_FOR_EACH_PTR(vs);
863
864 set_state(SMATCH_EXTRA, name, sym, alloc_estate_sval(sval_cast(type, sval)));
865 free:
866 free_string(name);
867 }
868
869 static void do_array_assign(struct expression *left, int op, struct expression *right)
870 {
871 struct range_list *rl;
872
873 if (op == '=') {
874 get_absolute_rl(right, &rl);
875 rl = cast_rl(get_type(left), rl);
876 } else {
877 rl = alloc_whole_rl(get_type(left));
878 }
879
880 set_extra_array_mod(left, alloc_estate_rl(rl));
881 }
882
883 static void match_vanilla_assign(struct expression *left, struct expression *right)
884 {
885 struct range_list *orig_rl = NULL;
886 struct range_list *rl = NULL;
887 struct symbol *right_sym;
888 struct symbol *left_type;
889 struct symbol *right_type;
890 char *right_name = NULL;
891 struct symbol *sym;
892 char *name;
893 sval_t max;
894 struct smatch_state *state;
895 int comparison;
896
897 if (is_struct(left))
898 return;
899
900 save_chunk_info(left, right);
901
902 name = expr_to_var_sym(left, &sym);
903 if (!name) {
904 if (chunk_has_array(left))
905 do_array_assign(left, '=', right);
906 return;
907 }
908
909 left_type = get_type(left);
910 right_type = get_type(right);
911
912 right_name = expr_to_var_sym(right, &right_sym);
913
914 if (!__in_fake_assign &&
915 !(right->type == EXPR_PREOP && right->op == '&') &&
916 right_name && right_sym &&
917 values_fit_type(left, right) &&
918 !has_symbol(right, sym)) {
919 set_equiv(left, right);
920 goto free;
921 }
922
923 if (is_pointer(right) && get_address_rl(right, &rl)) {
924 state = alloc_estate_rl(rl);
925 goto done;
926 }
927
928 if (__in_fake_assign) {
929 struct smatch_state *right_state;
930 sval_t sval;
931
932 if (get_value(right, &sval)) {
933 sval = sval_cast(left_type, sval);
934 state = alloc_estate_sval(sval);
935 goto done;
936 }
937
938 right_state = get_state(SMATCH_EXTRA, right_name, right_sym);
939 if (right_state) {
940 /* simple assignment */
941 state = clone_estate(right_state);
942 goto done;
943 }
944
945 state = alloc_estate_rl(alloc_whole_rl(left_type));
946 goto done;
947 }
948
949 comparison = get_comparison(left, right);
950 if (comparison) {
951 comparison = flip_comparison(comparison);
952 get_implied_rl(left, &orig_rl);
953 }
954
955 if (get_implied_rl(right, &rl)) {
956 rl = cast_rl(left_type, rl);
957 if (orig_rl)
958 filter_by_comparison(&rl, comparison, orig_rl);
959 state = alloc_estate_rl(rl);
960 if (get_hard_max(right, &max)) {
961 estate_set_hard_max(state);
962 estate_set_fuzzy_max(state, max);
963 }
964 } else {
965 rl = alloc_whole_rl(right_type);
966 rl = cast_rl(left_type, rl);
967 if (orig_rl)
968 filter_by_comparison(&rl, comparison, orig_rl);
969 state = alloc_estate_rl(rl);
970 }
971
972 done:
973 set_extra_mod(name, sym, left, state);
974 free:
975 free_string(right_name);
976 }
977
978 static int op_remove_assign(int op)
979 {
980 switch (op) {
981 case SPECIAL_ADD_ASSIGN:
982 return '+';
983 case SPECIAL_SUB_ASSIGN:
984 return '-';
985 case SPECIAL_MUL_ASSIGN:
986 return '*';
987 case SPECIAL_DIV_ASSIGN:
988 return '/';
989 case SPECIAL_MOD_ASSIGN:
990 return '%';
991 case SPECIAL_AND_ASSIGN:
992 return '&';
993 case SPECIAL_OR_ASSIGN:
994 return '|';
995 case SPECIAL_XOR_ASSIGN:
996 return '^';
997 case SPECIAL_SHL_ASSIGN:
998 return SPECIAL_LEFTSHIFT;
999 case SPECIAL_SHR_ASSIGN:
1000 return SPECIAL_RIGHTSHIFT;
1001 default:
1002 return op;
1003 }
1004 }
1005
1006 static void match_assign(struct expression *expr)
1007 {
1008 struct range_list *rl = NULL;
1009 struct expression *left;
1010 struct expression *right;
1011 struct expression *binop_expr;
1012 struct symbol *left_type;
1013 struct symbol *sym;
1014 char *name;
1015 sval_t left_min, left_max;
1016 sval_t right_min, right_max;
1017 sval_t res_min, res_max;
1018
1019 left = strip_expr(expr->left);
1020
1021 right = strip_parens(expr->right);
1022 if (right->type == EXPR_CALL && sym_name_is("__builtin_expect", right->fn))
1023 right = get_argument_from_call_expr(right->args, 0);
1024 while (right->type == EXPR_ASSIGNMENT && right->op == '=')
1025 right = strip_parens(right->left);
1026
1027 if (expr->op == '=' && is_condition(expr->right))
1028 return; /* handled in smatch_condition.c */
1029 if (expr->op == '=' && right->type == EXPR_CALL)
1030 return; /* handled in smatch_function_hooks.c */
1031 if (expr->op == '=') {
1032 match_vanilla_assign(left, right);
1033 return;
1034 }
1035
1036 name = expr_to_var_sym(left, &sym);
1037 if (!name)
1038 return;
1039
1040 left_type = get_type(left);
1041
1042 res_min = sval_type_min(left_type);
1043 res_max = sval_type_max(left_type);
1044
1045 switch (expr->op) {
1046 case SPECIAL_ADD_ASSIGN:
1047 get_absolute_max(left, &left_max);
1048 get_absolute_max(right, &right_max);
1049 if (sval_binop_overflows(left_max, '+', sval_cast(left_type, right_max)))
1050 break;
1051 if (get_implied_min(left, &left_min) &&
1052 !sval_is_negative_min(left_min) &&
1053 get_implied_min(right, &right_min) &&
1054 !sval_is_negative_min(right_min)) {
1055 res_min = sval_binop(left_min, '+', right_min);
1056 res_min = sval_cast(left_type, res_min);
1057 }
1058 if (inside_loop()) /* we are assuming loops don't lead to wrapping */
1059 break;
1060 res_max = sval_binop(left_max, '+', right_max);
1061 res_max = sval_cast(left_type, res_max);
1062 break;
1063 case SPECIAL_SUB_ASSIGN:
1064 if (get_implied_max(left, &left_max) &&
1065 !sval_is_max(left_max) &&
1066 get_implied_min(right, &right_min) &&
1067 !sval_is_min(right_min)) {
1068 res_max = sval_binop(left_max, '-', right_min);
1069 res_max = sval_cast(left_type, res_max);
1070 }
1071 if (inside_loop())
1072 break;
1073 if (get_implied_min(left, &left_min) &&
1074 !sval_is_min(left_min) &&
1075 get_implied_max(right, &right_max) &&
1076 !sval_is_max(right_max)) {
1077 res_min = sval_binop(left_min, '-', right_max);
1078 res_min = sval_cast(left_type, res_min);
1079 }
1080 break;
1081 case SPECIAL_AND_ASSIGN:
1082 case SPECIAL_MOD_ASSIGN:
1083 case SPECIAL_SHL_ASSIGN:
1084 case SPECIAL_SHR_ASSIGN:
1085 case SPECIAL_OR_ASSIGN:
1086 case SPECIAL_XOR_ASSIGN:
1087 case SPECIAL_MUL_ASSIGN:
1088 case SPECIAL_DIV_ASSIGN:
1089 binop_expr = binop_expression(expr->left,
1090 op_remove_assign(expr->op),
1091 expr->right);
1092 if (get_absolute_rl(binop_expr, &rl)) {
1093 rl = cast_rl(left_type, rl);
1094 set_extra_mod(name, sym, left, alloc_estate_rl(rl));
1095 goto free;
1096 }
1097 break;
1098 }
1099 rl = cast_rl(left_type, alloc_rl(res_min, res_max));
1100 set_extra_mod(name, sym, left, alloc_estate_rl(rl));
1101 free:
1102 free_string(name);
1103 }
1104
1105 static struct smatch_state *increment_state(struct smatch_state *state)
1106 {
1107 sval_t min = estate_min(state);
1108 sval_t max = estate_max(state);
1109
1110 if (!estate_rl(state))
1111 return NULL;
1112
1113 if (inside_loop())
1114 max = sval_type_max(max.type);
1115
1116 if (!sval_is_min(min) && !sval_is_max(min))
1117 min.value++;
1118 if (!sval_is_min(max) && !sval_is_max(max))
1119 max.value++;
1120 return alloc_estate_range(min, max);
1121 }
1122
1123 static struct smatch_state *decrement_state(struct smatch_state *state)
1124 {
1125 sval_t min = estate_min(state);
1126 sval_t max = estate_max(state);
1127
1128 if (!estate_rl(state))
1129 return NULL;
1130
1131 if (inside_loop())
1132 min = sval_type_min(min.type);
1133
1134 if (!sval_is_min(min) && !sval_is_max(min))
1135 min.value--;
1136 if (!sval_is_min(max) && !sval_is_max(max))
1137 max.value--;
1138 return alloc_estate_range(min, max);
1139 }
1140
1141 static void clear_pointed_at_state(struct expression *expr)
1142 {
1143 struct symbol *type;
1144
1145 /*
1146 * ALERT: This is sort of a mess. If it's is a struct assigment like
1147 * "foo = bar;", then that's handled by smatch_struct_assignment.c.
1148 * the same thing for p++ where "p" is a struct. Most modifications
1149 * are handled by the assignment hook or the db. Smatch_extra.c doesn't
1150 * use smatch_modification.c because we have to get the ordering right
1151 * or something. So if you have p++ where p is a pointer to a standard
1152 * c type then we handle that here. What a mess.
1153 */
1154
1155 type = get_type(expr);
1156 if (!type || type->type != SYM_PTR)
1157 return;
1158 type = get_real_base_type(type);
1159 if (!type || type->type != SYM_BASETYPE)
1160 return;
1161 set_extra_expr_mod(deref_expression(expr), alloc_estate_whole(type));
1162 }
1163
1164 static void unop_expr(struct expression *expr)
1165 {
1166 struct smatch_state *state;
1167
1168 if (expr->smatch_flags & Handled)
1169 return;
1170
1171 switch (expr->op) {
1172 case SPECIAL_INCREMENT:
1173 state = get_state_expr(SMATCH_EXTRA, expr->unop);
1174 state = increment_state(state);
1175 if (!state)
1176 state = alloc_estate_whole(get_type(expr));
1177 set_extra_expr_mod(expr->unop, state);
1178 clear_pointed_at_state(expr->unop);
1179 break;
1180 case SPECIAL_DECREMENT:
1181 state = get_state_expr(SMATCH_EXTRA, expr->unop);
1182 state = decrement_state(state);
1183 if (!state)
1184 state = alloc_estate_whole(get_type(expr));
1185 set_extra_expr_mod(expr->unop, state);
1186 clear_pointed_at_state(expr->unop);
1187 break;
1188 default:
1189 return;
1190 }
1191 }
1192
1193 static void asm_expr(struct statement *stmt)
1194 {
1195
1196 struct expression *expr;
1197 struct symbol *type;
1198 int state = 0;
1199
1200 FOR_EACH_PTR(stmt->asm_outputs, expr) {
1201 switch (state) {
1202 case 0: /* identifier */
1203 case 1: /* constraint */
1204 state++;
1205 continue;
1206 case 2: /* expression */
1207 state = 0;
1208 type = get_type(strip_expr(expr));
1209 set_extra_expr_mod(expr, alloc_estate_whole(type));
1210 continue;
1211 }
1212 } END_FOR_EACH_PTR(expr);
1213 }
1214
1215 static void check_dereference(struct expression *expr)
1216 {
1217 struct smatch_state *state;
1218
1219 if (__in_fake_assign)
1220 return;
1221 if (outside_of_function())
1222 return;
1223 state = get_extra_state(expr);
1224 if (state) {
1225 static struct range_list *valid_rl;
1226 struct range_list *rl;
1227
1228 if (!valid_rl) {
1229 valid_rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
1230 valid_rl = clone_rl_permanent(valid_rl);
1231 }
1232
1233 rl = rl_intersection(estate_rl(state), valid_rl);
1234 if (rl_equiv(rl, estate_rl(state)))
1235 return;
1236 set_extra_expr_nomod(expr, alloc_estate_rl(rl));
1237 } else {
1238 set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
1239 }
1240 }
1241
1242 static void match_dereferences(struct expression *expr)
1243 {
1244 if (expr->type != EXPR_PREOP)
1245 return;
1246 /* it's saying that foo[1] = bar dereferences foo[1] */
1247 if (is_array(expr))
1248 return;
1249 check_dereference(expr->unop);
1250 }
1251
1252 static void match_pointer_as_array(struct expression *expr)
1253 {
1254 if (!is_array(expr))
1255 return;
1256 check_dereference(get_array_base(expr));
1257 }
1258
1259 static void find_dereferences(struct expression *expr)
1260 {
1261 while (expr->type == EXPR_PREOP) {
1262 if (expr->op == '*')
1263 check_dereference(expr->unop);
1264 expr = strip_expr(expr->unop);
1265 }
1266 }
1267
1268 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
1269 {
1270 struct symbol *sym;
1271 char *name;
1272
1273 name = get_variable_from_key(arg, key, &sym);
1274 if (name && sym) {
1275 struct smatch_state *orig, *new;
1276 struct range_list *rl;
1277
1278 orig = get_state(SMATCH_EXTRA, name, sym);
1279 if (orig) {
1280 rl = rl_intersection(estate_rl(orig),
1281 alloc_rl(valid_ptr_min_sval,
1282 valid_ptr_max_sval));
1283 new = alloc_estate_rl(rl);
1284 } else {
1285 new = alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval);
1286 }
1287
1288 set_extra_nomod(name, sym, NULL, new);
1289 }
1290 free_string(name);
1291
1292 find_dereferences(arg);
1293 }
1294
1295 static sval_t add_one(sval_t sval)
1296 {
1297 sval.value++;
1298 return sval;
1299 }
1300
1301 static int handle_postop_inc(struct expression *left, int op, struct expression *right)
1302 {
1303 struct statement *stmt;
1304 struct expression *cond;
1305 struct smatch_state *true_state, *false_state;
1306 sval_t start;
1307 sval_t limit;
1308
1309 /*
1310 * If we're decrementing here then that's a canonical while count down
1311 * so it's handled already. We're only handling loops like:
1312 * i = 0;
1313 * do { ... } while (i++ < 3);
1314 */
1315
1316 if (left->type != EXPR_POSTOP || left->op != SPECIAL_INCREMENT)
1317 return 0;
1318
1319 stmt = __cur_stmt->parent;
1320 if (!stmt)
1321 return 0;
1322 if (stmt->type == STMT_COMPOUND)
1323 stmt = stmt->parent;
1324 if (!stmt || stmt->type != STMT_ITERATOR || !stmt->iterator_post_condition)
1325 return 0;
1326
1327 cond = strip_expr(stmt->iterator_post_condition);
1328 if (cond->type != EXPR_COMPARE || cond->op != op)
1329 return 0;
1330 if (left != strip_expr(cond->left) || right != strip_expr(cond->right))
1331 return 0;
1332
1333 if (!get_implied_value(left->unop, &start))
1334 return 0;
1335 if (!get_implied_value(right, &limit))
1336 return 0;
1337
1338 if (sval_cmp(start, limit) > 0)
1339 return 0;
1340
1341 switch (op) {
1342 case '<':
1343 case SPECIAL_UNSIGNED_LT:
1344 break;
1345 case SPECIAL_LTE:
1346 case SPECIAL_UNSIGNED_LTE:
1347 limit = add_one(limit);
1348 default:
1349 return 0;
1350
1351 }
1352
1353 true_state = alloc_estate_range(add_one(start), limit);
1354 false_state = alloc_estate_range(add_one(limit), add_one(limit));
1355
1356 /* Currently we just discard the false state but when two passes is
1357 * implimented correctly then it will use it.
1358 */
1359
1360 set_extra_expr_true_false(left->unop, true_state, false_state);
1361
1362 return 1;
1363 }
1364
1365 static void handle_comparison(struct symbol *type, struct expression *left, int op, struct expression *right)
1366 {
1367 struct range_list *left_orig;
1368 struct range_list *left_true;
1369 struct range_list *left_false;
1370 struct range_list *right_orig;
1371 struct range_list *right_true;
1372 struct range_list *right_false;
1373 struct smatch_state *left_true_state;
1374 struct smatch_state *left_false_state;
1375 struct smatch_state *right_true_state;
1376 struct smatch_state *right_false_state;
1377 sval_t dummy, hard_max;
1378 int left_postop = 0;
1379 int right_postop = 0;
1380
1381 if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
1382 if (left->type == EXPR_POSTOP) {
1383 left->smatch_flags |= Handled;
1384 left_postop = left->op;
1385 if (handle_postop_inc(left, op, right))
1386 return;
1387 }
1388 left = strip_parens(left->unop);
1389 }
1390 while (left->type == EXPR_ASSIGNMENT)
1391 left = strip_parens(left->left);
1392
1393 if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
1394 if (right->type == EXPR_POSTOP) {
1395 right->smatch_flags |= Handled;
1396 right_postop = right->op;
1397 }
1398 right = strip_parens(right->unop);
1399 }
1400
1401 get_real_absolute_rl(left, &left_orig);
1402 left_orig = cast_rl(type, left_orig);
1403
1404 get_real_absolute_rl(right, &right_orig);
1405 right_orig = cast_rl(type, right_orig);
1406
1407 split_comparison_rl(left_orig, op, right_orig, &left_true, &left_false, &right_true, &right_false);
1408
1409 left_true = rl_truncate_cast(get_type(strip_expr(left)), left_true);
1410 left_false = rl_truncate_cast(get_type(strip_expr(left)), left_false);
1411 right_true = rl_truncate_cast(get_type(strip_expr(right)), right_true);
1412 right_false = rl_truncate_cast(get_type(strip_expr(right)), right_false);
1413
1414 if (!left_true || !left_false) {
1415 struct range_list *tmp_true, *tmp_false;
1416
1417 split_comparison_rl(alloc_whole_rl(type), op, right_orig, &tmp_true, &tmp_false, NULL, NULL);
1418 tmp_true = rl_truncate_cast(get_type(strip_expr(left)), tmp_true);
1419 tmp_false = rl_truncate_cast(get_type(strip_expr(left)), tmp_false);
1420 if (tmp_true && tmp_false)
1421 __save_imaginary_state(left, tmp_true, tmp_false);
1422 }
1423
1424 if (!right_true || !right_false) {
1425 struct range_list *tmp_true, *tmp_false;
1426
1427 split_comparison_rl(alloc_whole_rl(type), op, right_orig, NULL, NULL, &tmp_true, &tmp_false);
1428 tmp_true = rl_truncate_cast(get_type(strip_expr(right)), tmp_true);
1429 tmp_false = rl_truncate_cast(get_type(strip_expr(right)), tmp_false);
1430 if (tmp_true && tmp_false)
1431 __save_imaginary_state(right, tmp_true, tmp_false);
1432 }
1433
1434 left_true_state = alloc_estate_rl(left_true);
1435 left_false_state = alloc_estate_rl(left_false);
1436 right_true_state = alloc_estate_rl(right_true);
1437 right_false_state = alloc_estate_rl(right_false);
1438
1439 switch (op) {
1440 case '<':
1441 case SPECIAL_UNSIGNED_LT:
1442 case SPECIAL_UNSIGNED_LTE:
1443 case SPECIAL_LTE:
1444 if (get_hard_max(right, &dummy))
1445 estate_set_hard_max(left_true_state);
1446 if (get_hard_max(left, &dummy))
1447 estate_set_hard_max(right_false_state);
1448 break;
1449 case '>':
1450 case SPECIAL_UNSIGNED_GT:
1451 case SPECIAL_UNSIGNED_GTE:
1452 case SPECIAL_GTE:
1453 if (get_hard_max(left, &dummy))
1454 estate_set_hard_max(right_true_state);
1455 if (get_hard_max(right, &dummy))
1456 estate_set_hard_max(left_false_state);
1457 break;
1458 }
1459
1460 switch (op) {
1461 case '<':
1462 case SPECIAL_UNSIGNED_LT:
1463 case SPECIAL_UNSIGNED_LTE:
1464 case SPECIAL_LTE:
1465 if (get_hard_max(right, &hard_max)) {
1466 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1467 hard_max.value--;
1468 estate_set_fuzzy_max(left_true_state, hard_max);
1469 }
1470 if (get_implied_value(right, &hard_max)) {
1471 if (op == SPECIAL_UNSIGNED_LTE ||
1472 op == SPECIAL_LTE)
1473 hard_max.value++;
1474 estate_set_fuzzy_max(left_false_state, hard_max);
1475 }
1476 if (get_hard_max(left, &hard_max)) {
1477 if (op == SPECIAL_UNSIGNED_LTE ||
1478 op == SPECIAL_LTE)
1479 hard_max.value--;
1480 estate_set_fuzzy_max(right_false_state, hard_max);
1481 }
1482 if (get_implied_value(left, &hard_max)) {
1483 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1484 hard_max.value++;
1485 estate_set_fuzzy_max(right_true_state, hard_max);
1486 }
1487 break;
1488 case '>':
1489 case SPECIAL_UNSIGNED_GT:
1490 case SPECIAL_UNSIGNED_GTE:
1491 case SPECIAL_GTE:
1492 if (get_hard_max(left, &hard_max)) {
1493 if (op == '>' || op == SPECIAL_UNSIGNED_GT)
1494 hard_max.value--;
1495 estate_set_fuzzy_max(right_true_state, hard_max);
1496 }
1497 if (get_implied_value(left, &hard_max)) {
1498 if (op == SPECIAL_UNSIGNED_GTE ||
1499 op == SPECIAL_GTE)
1500 hard_max.value++;
1501 estate_set_fuzzy_max(right_false_state, hard_max);
1502 }
1503 if (get_hard_max(right, &hard_max)) {
1504 if (op == SPECIAL_UNSIGNED_LTE ||
1505 op == SPECIAL_LTE)
1506 hard_max.value--;
1507 estate_set_fuzzy_max(left_false_state, hard_max);
1508 }
1509 if (get_implied_value(right, &hard_max)) {
1510 if (op == '>' ||
1511 op == SPECIAL_UNSIGNED_GT)
1512 hard_max.value++;
1513 estate_set_fuzzy_max(left_true_state, hard_max);
1514 }
1515 break;
1516 case SPECIAL_EQUAL:
1517 if (get_hard_max(left, &hard_max))
1518 estate_set_fuzzy_max(right_true_state, hard_max);
1519 if (get_hard_max(right, &hard_max))
1520 estate_set_fuzzy_max(left_true_state, hard_max);
1521 break;
1522 }
1523
1524 if (get_hard_max(left, &hard_max)) {
1525 estate_set_hard_max(left_true_state);
1526 estate_set_hard_max(left_false_state);
1527 }
1528 if (get_hard_max(right, &hard_max)) {
1529 estate_set_hard_max(right_true_state);
1530 estate_set_hard_max(right_false_state);
1531 }
1532
1533 if (left_postop == SPECIAL_INCREMENT) {
1534 left_true_state = increment_state(left_true_state);
1535 left_false_state = increment_state(left_false_state);
1536 }
1537 if (left_postop == SPECIAL_DECREMENT) {
1538 left_true_state = decrement_state(left_true_state);
1539 left_false_state = decrement_state(left_false_state);
1540 }
1541 if (right_postop == SPECIAL_INCREMENT) {
1542 right_true_state = increment_state(right_true_state);
1543 right_false_state = increment_state(right_false_state);
1544 }
1545 if (right_postop == SPECIAL_DECREMENT) {
1546 right_true_state = decrement_state(right_true_state);
1547 right_false_state = decrement_state(right_false_state);
1548 }
1549
1550 if (estate_rl(left_true_state) && estates_equiv(left_true_state, left_false_state)) {
1551 left_true_state = NULL;
1552 left_false_state = NULL;
1553 }
1554
1555 if (estate_rl(right_true_state) && estates_equiv(right_true_state, right_false_state)) {
1556 right_true_state = NULL;
1557 right_false_state = NULL;
1558 }
1559
1560 /* Don't introduce new states for known true/false conditions */
1561 if (rl_equiv(left_orig, estate_rl(left_true_state)))
1562 left_true_state = NULL;
1563 if (rl_equiv(left_orig, estate_rl(left_false_state)))
1564 left_false_state = NULL;
1565 if (rl_equiv(right_orig, estate_rl(right_true_state)))
1566 right_true_state = NULL;
1567 if (rl_equiv(right_orig, estate_rl(right_false_state)))
1568 right_false_state = NULL;
1569
1570 set_extra_expr_true_false(left, left_true_state, left_false_state);
1571 set_extra_expr_true_false(right, right_true_state, right_false_state);
1572 }
1573
1574 static int is_simple_math(struct expression *expr)
1575 {
1576 if (!expr)
1577 return 0;
1578 if (expr->type != EXPR_BINOP)
1579 return 0;
1580 switch (expr->op) {
1581 case '+':
1582 case '-':
1583 case '*':
1584 return 1;
1585 }
1586 return 0;
1587 }
1588
1589 static void move_known_values(struct expression **left_p, struct expression **right_p)
1590 {
1591 struct expression *left = *left_p;
1592 struct expression *right = *right_p;
1593 sval_t sval, dummy;
1594
1595 if (get_implied_value(left, &sval)) {
1596 if (!is_simple_math(right))
1597 return;
1598 if (get_implied_value(right, &dummy))
1599 return;
1600 if (right->op == '*') {
1601 sval_t divisor;
1602
1603 if (!get_value(right->right, &divisor))
1604 return;
1605 if (divisor.value == 0 && sval.value % divisor.value)
1606 return;
1607 *left_p = binop_expression(left, invert_op(right->op), right->right);
1608 *right_p = right->left;
1609 return;
1610 }
1611 if (right->op == '+' && get_value(right->left, &sval)) {
1612 *left_p = binop_expression(left, invert_op(right->op), right->left);
1613 *right_p = right->right;
1614 return;
1615 }
1616 if (get_value(right->right, &sval)) {
1617 *left_p = binop_expression(left, invert_op(right->op), right->right);
1618 *right_p = right->left;
1619 return;
1620 }
1621 return;
1622 }
1623 if (get_implied_value(right, &sval)) {
1624 if (!is_simple_math(left))
1625 return;
1626 if (get_implied_value(left, &dummy))
1627 return;
1628 if (left->op == '*') {
1629 sval_t divisor;
1630
1631 if (!get_value(left->right, &divisor))
1632 return;
1633 if (divisor.value == 0 && sval.value % divisor.value)
1634 return;
1635 *right_p = binop_expression(right, invert_op(left->op), left->right);
1636 *left_p = left->left;
1637 return;
1638 }
1639 if (left->op == '+' && get_value(left->left, &sval)) {
1640 *right_p = binop_expression(right, invert_op(left->op), left->left);
1641 *left_p = left->right;
1642 return;
1643 }
1644
1645 if (get_value(left->right, &sval)) {
1646 *right_p = binop_expression(right, invert_op(left->op), left->right);
1647 *left_p = left->left;
1648 return;
1649 }
1650 return;
1651 }
1652 }
1653
1654 /*
1655 * The reason for do_simple_algebra() is to solve things like:
1656 * if (foo > 66 || foo + bar > 64) {
1657 * "foo" is not really a known variable so it won't be handled by
1658 * move_known_variables() but it's a super common idiom.
1659 *
1660 */
1661 static int do_simple_algebra(struct expression **left_p, struct expression **right_p)
1662 {
1663 struct expression *left = *left_p;
1664 struct expression *right = *right_p;
1665 struct range_list *rl;
1666 sval_t tmp;
1667
1668 if (left->type != EXPR_BINOP || left->op != '+')
1669 return 0;
1670 if (can_integer_overflow(get_type(left), left))
1671 return 0;
1672 if (!get_implied_value(right, &tmp))
1673 return 0;
1674
1675 if (!get_implied_value(left->left, &tmp) &&
1676 get_implied_rl(left->left, &rl) &&
1677 !is_whole_rl(rl)) {
1678 *right_p = binop_expression(right, '-', left->left);
1679 *left_p = left->right;
1680 return 1;
1681 }
1682 if (!get_implied_value(left->right, &tmp) &&
1683 get_implied_rl(left->right, &rl) &&
1684 !is_whole_rl(rl)) {
1685 *right_p = binop_expression(right, '-', left->right);
1686 *left_p = left->left;
1687 return 1;
1688 }
1689
1690 return 0;
1691 }
1692
1693 static int match_func_comparison(struct expression *expr)
1694 {
1695 struct expression *left = strip_expr(expr->left);
1696 struct expression *right = strip_expr(expr->right);
1697 sval_t sval;
1698
1699 /*
1700 * fixme: think about this harder. We should always be trying to limit
1701 * the non-call side as well. If we can't determine the limitter does
1702 * that mean we aren't querying the database and are missing important
1703 * information?
1704 */
1705
1706 if (left->type == EXPR_CALL) {
1707 if (get_implied_value(left, &sval)) {
1708 handle_comparison(get_type(expr), left, expr->op, right);
1709 return 1;
1710 }
1711 function_comparison(left, expr->op, right);
1712 return 1;
1713 }
1714
1715 if (right->type == EXPR_CALL) {
1716 if (get_implied_value(right, &sval)) {
1717 handle_comparison(get_type(expr), left, expr->op, right);
1718 return 1;
1719 }
1720 function_comparison(left, expr->op, right);
1721 return 1;
1722 }
1723
1724 return 0;
1725 }
1726
1727 /* Handle conditions like "if (foo + bar < foo) {" */
1728 static int handle_integer_overflow_test(struct expression *expr)
1729 {
1730 struct expression *left, *right;
1731 struct symbol *type;
1732 sval_t left_min, right_min, min, max;
1733
1734 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1735 return 0;
1736
1737 left = strip_parens(expr->left);
1738 right = strip_parens(expr->right);
1739
1740 if (left->op != '+')
1741 return 0;
1742
1743 type = get_type(expr);
1744 if (!type)
1745 return 0;
1746 if (type_positive_bits(type) == 32) {
1747 max.type = &uint_ctype;
1748 max.uvalue = (unsigned int)-1;
1749 } else if (type_positive_bits(type) == 64) {
1750 max.type = &ulong_ctype;
1751 max.value = (unsigned long long)-1;
1752 } else {
1753 return 0;
1754 }
1755
1756 if (!expr_equiv(left->left, right) && !expr_equiv(left->right, right))
1757 return 0;
1758
1759 get_absolute_min(left->left, &left_min);
1760 get_absolute_min(left->right, &right_min);
1761 min = sval_binop(left_min, '+', right_min);
1762
1763 set_extra_chunk_true_false(left, NULL, alloc_estate_range(min, max));
1764 return 1;
1765 }
1766
1767 static void match_comparison(struct expression *expr)
1768 {
1769 struct expression *left_orig = strip_parens(expr->left);
1770 struct expression *right_orig = strip_parens(expr->right);
1771 struct expression *left, *right;
1772 struct expression *prev;
1773 struct symbol *type;
1774
1775 if (match_func_comparison(expr))
1776 return;
1777
1778 type = get_type(expr);
1779 if (!type)
1780 type = &llong_ctype;
1781
1782 if (handle_integer_overflow_test(expr))
1783 return;
1784
1785 left = left_orig;
1786 right = right_orig;
1787 move_known_values(&left, &right);
1788 handle_comparison(type, left, expr->op, right);
1789
1790 left = left_orig;
1791 right = right_orig;
1792 if (do_simple_algebra(&left, &right))
1793 handle_comparison(type, left, expr->op, right);
1794
1795 prev = get_assigned_expr(left_orig);
1796 if (is_simple_math(prev) && has_variable(prev, left_orig) == 0) {
1797 left = prev;
1798 right = right_orig;
1799 move_known_values(&left, &right);
1800 handle_comparison(type, left, expr->op, right);
1801 }
1802
1803 prev = get_assigned_expr(right_orig);
1804 if (is_simple_math(prev) && has_variable(prev, right_orig) == 0) {
1805 left = left_orig;
1806 right = prev;
1807 move_known_values(&left, &right);
1808 handle_comparison(type, left, expr->op, right);
1809 }
1810 }
1811
1812 static sval_t get_high_mask(sval_t known)
1813 {
1814 sval_t ret;
1815 int i;
1816
1817 ret = known;
1818 ret.value = 0;
1819
1820 for (i = type_bits(known.type) - 1; i >= 0; i--) {
1821 if (known.uvalue & (1ULL << i))
1822 ret.uvalue |= (1ULL << i);
1823 else
1824 return ret;
1825
1826 }
1827 return ret;
1828 }
1829
1830 static void handle_AND_op(struct expression *var, sval_t known)
1831 {
1832 struct range_list *orig_rl;
1833 struct range_list *true_rl = NULL;
1834 struct range_list *false_rl = NULL;
1835 int bit;
1836 sval_t low_mask = known;
1837 sval_t high_mask;
1838 sval_t max;
1839
1840 get_absolute_rl(var, &orig_rl);
1841
1842 if (known.value > 0) {
1843 bit = ffsll(known.value) - 1;
1844 low_mask.uvalue = (1ULL << bit) - 1;
1845 true_rl = remove_range(orig_rl, sval_type_val(known.type, 0), low_mask);
1846 }
1847 high_mask = get_high_mask(known);
1848 if (high_mask.value) {
1849 bit = ffsll(high_mask.value) - 1;
1850 low_mask.uvalue = (1ULL << bit) - 1;
1851
1852 false_rl = orig_rl;
1853 if (sval_is_negative(rl_min(orig_rl)))
1854 false_rl = remove_range(false_rl, sval_type_min(known.type), sval_type_val(known.type, -1));
1855 false_rl = remove_range(false_rl, low_mask, sval_type_max(known.type));
1856 if (type_signed(high_mask.type) && type_unsigned(rl_type(false_rl))) {
1857 false_rl = remove_range(false_rl,
1858 sval_type_val(rl_type(false_rl), sval_type_max(known.type).uvalue),
1859 sval_type_val(rl_type(false_rl), -1));
1860 }
1861 } else if (known.value == 1 &&
1862 get_hard_max(var, &max) &&
1863 sval_cmp(max, rl_max(orig_rl)) == 0 &&
1864 max.value & 1) {
1865 false_rl = remove_range(orig_rl, max, max);
1866 }
1867 set_extra_expr_true_false(var,
1868 true_rl ? alloc_estate_rl(true_rl) : NULL,
1869 false_rl ? alloc_estate_rl(false_rl) : NULL);
1870 }
1871
1872 static void handle_AND_condition(struct expression *expr)
1873 {
1874 sval_t known;
1875
1876 if (get_implied_value(expr->left, &known))
1877 handle_AND_op(expr->right, known);
1878 else if (get_implied_value(expr->right, &known))
1879 handle_AND_op(expr->left, known);
1880 }
1881
1882 static void handle_MOD_condition(struct expression *expr)
1883 {
1884 struct range_list *orig_rl;
1885 struct range_list *true_rl;
1886 struct range_list *false_rl = NULL;
1887 sval_t right;
1888 sval_t zero = {
1889 .value = 0,
1890 };
1891
1892 if (!get_implied_value(expr->right, &right) || right.value == 0)
1893 return;
1894 get_absolute_rl(expr->left, &orig_rl);
1895
1896 zero.type = rl_type(orig_rl);
1897
1898 /* We're basically dorking around the min and max here */
1899 true_rl = remove_range(orig_rl, zero, zero);
1900 if (!sval_is_max(rl_max(true_rl)) &&
1901 !(rl_max(true_rl).value % right.value))
1902 true_rl = remove_range(true_rl, rl_max(true_rl), rl_max(true_rl));
1903
1904 if (rl_equiv(true_rl, orig_rl))
1905 true_rl = NULL;
1906
1907 if (sval_is_positive(rl_min(orig_rl)) &&
1908 (rl_max(orig_rl).value - rl_min(orig_rl).value) / right.value < 5) {
1909 sval_t add;
1910 int i;
1911
1912 add = rl_min(orig_rl);
1913 add.value += right.value - (add.value % right.value);
1914 add.value -= right.value;
1915
1916 for (i = 0; i < 5; i++) {
1917 add.value += right.value;
1918 if (add.value > rl_max(orig_rl).value)
1919 break;
1920 add_range(&false_rl, add, add);
1921 }
1922 } else {
1923 if (rl_min(orig_rl).uvalue != 0 &&
1924 rl_min(orig_rl).uvalue < right.uvalue) {
1925 sval_t chop = right;
1926 chop.value--;
1927 false_rl = remove_range(orig_rl, zero, chop);
1928 }
1929
1930 if (!sval_is_max(rl_max(orig_rl)) &&
1931 (rl_max(orig_rl).value % right.value)) {
1932 sval_t chop = rl_max(orig_rl);
1933 chop.value -= chop.value % right.value;
1934 chop.value++;
1935 if (!false_rl)
1936 false_rl = clone_rl(orig_rl);
1937 false_rl = remove_range(false_rl, chop, rl_max(orig_rl));
1938 }
1939 }
1940
1941 set_extra_expr_true_false(expr->left,
1942 true_rl ? alloc_estate_rl(true_rl) : NULL,
1943 false_rl ? alloc_estate_rl(false_rl) : NULL);
1944 }
1945
1946 /* this is actually hooked from smatch_implied.c... it's hacky, yes */
1947 void __extra_match_condition(struct expression *expr)
1948 {
1949 struct smatch_state *pre_state;
1950 struct smatch_state *true_state;
1951 struct smatch_state *false_state;
1952 struct range_list *pre_rl;
1953
1954 expr = strip_expr(expr);
1955 switch (expr->type) {
1956 case EXPR_CALL:
1957 function_comparison(expr, SPECIAL_NOTEQUAL, zero_expr());
1958 return;
1959 case EXPR_PREOP:
1960 case EXPR_SYMBOL:
1961 case EXPR_DEREF: {
1962 sval_t zero;
1963
1964 zero = sval_blank(expr);
1965 zero.value = 0;
1966
1967 pre_state = get_extra_state(expr);
1968 if (estate_is_empty(pre_state))
1969 return;
1970 if (pre_state)
1971 pre_rl = estate_rl(pre_state);
1972 else
1973 get_absolute_rl(expr, &pre_rl);
1974 if (possibly_true_rl(pre_rl, SPECIAL_EQUAL, rl_zero()))
1975 false_state = alloc_estate_sval(zero);
1976 else
1977 false_state = alloc_estate_empty();
1978 true_state = alloc_estate_rl(remove_range(pre_rl, zero, zero));
1979 set_extra_expr_true_false(expr, true_state, false_state);
1980 return;
1981 }
1982 case EXPR_COMPARE:
1983 match_comparison(expr);
1984 return;
1985 case EXPR_ASSIGNMENT:
1986 __extra_match_condition(expr->left);
1987 return;
1988 case EXPR_BINOP:
1989 if (expr->op == '&')
1990 handle_AND_condition(expr);
1991 if (expr->op == '%')
1992 handle_MOD_condition(expr);
1993 return;
1994 }
1995 }
1996
1997 static void assume_indexes_are_valid(struct expression *expr)
1998 {
1999 struct expression *array_expr;
2000 int array_size;
2001 struct expression *offset;
2002 struct symbol *offset_type;
2003 struct range_list *rl_before;
2004 struct range_list *rl_after;
2005 struct range_list *filter = NULL;
2006 sval_t size;
2007
2008 expr = strip_expr(expr);
2009 if (!is_array(expr))
2010 return;
2011
2012 offset = get_array_offset(expr);
2013 offset_type = get_type(offset);
2014 if (offset_type && type_signed(offset_type)) {
2015 filter = alloc_rl(sval_type_min(offset_type),
2016 sval_type_val(offset_type, -1));
2017 }
2018
2019 array_expr = get_array_base(expr);
2020 array_size = get_real_array_size(array_expr);
2021 if (array_size > 1) {
2022 size = sval_type_val(offset_type, array_size);
2023 add_range(&filter, size, sval_type_max(offset_type));
2024 }
2025
2026 if (!filter)
2027 return;
2028 get_absolute_rl(offset, &rl_before);
2029 rl_after = rl_filter(rl_before, filter);
2030 if (rl_equiv(rl_before, rl_after))
2031 return;
2032 set_extra_expr_nomod(offset, alloc_estate_rl(rl_after));
2033 }
2034
2035 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
2036 int implied_not_equal(struct expression *expr, long long val)
2037 {
2038 return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
2039 }
2040
2041 int implied_not_equal_name_sym(char *name, struct symbol *sym, long long val)
2042 {
2043 struct smatch_state *estate;
2044
2045 estate = get_state(SMATCH_EXTRA, name, sym);
2046 if (!estate)
2047 return 0;
2048 if (!rl_has_sval(estate_rl(estate), sval_type_val(estate_type(estate), 0)))
2049 return 1;
2050 return 0;
2051 }
2052
2053 int parent_is_null_var_sym(const char *name, struct symbol *sym)
2054 {
2055 char buf[256];
2056 char *start;
2057 char *end;
2058 struct smatch_state *state;
2059
2060 strncpy(buf, name, sizeof(buf) - 1);
2061 buf[sizeof(buf) - 1] = '\0';
2062
2063 start = &buf[0];
2064 while (*start == '*') {
2065 start++;
2066 state = get_state(SMATCH_EXTRA, start, sym);
2067 if (!state)
2068 continue;
2069 if (!estate_rl(state))
2070 return 1;
2071 if (estate_min(state).value == 0 &&
2072 estate_max(state).value == 0)
2073 return 1;
2074 }
2075
2076 start = &buf[0];
2077 while (*start == '&')
2078 start++;
2079
2080 while ((end = strrchr(start, '-'))) {
2081 *end = '\0';
2082 state = __get_state(SMATCH_EXTRA, start, sym);
2083 if (!state)
2084 continue;
2085 if (estate_min(state).value == 0 &&
2086 estate_max(state).value == 0)
2087 return 1;
2088 }
2089 return 0;
2090 }
2091
2092 int parent_is_null(struct expression *expr)
2093 {
2094 struct symbol *sym;
2095 char *var;
2096 int ret = 0;
2097
2098 expr = strip_expr(expr);
2099 var = expr_to_var_sym(expr, &sym);
2100 if (!var || !sym)
2101 goto free;
2102 ret = parent_is_null_var_sym(var, sym);
2103 free:
2104 free_string(var);
2105 return ret;
2106 }
2107
2108 static int param_used_callback(void *found, int argc, char **argv, char **azColName)
2109 {
2110 *(int *)found = 1;
2111 return 0;
2112 }
2113
2114 static int filter_unused_kzalloc_info(struct expression *call, int param, char *printed_name, struct sm_state *sm)
2115 {
2116 sval_t sval;
2117 int found = 0;
2118
2119 /* for function pointers assume everything is used */
2120 if (call->fn->type != EXPR_SYMBOL)
2121 return 0;
2122
2123 /*
2124 * kzalloc() information is treated as special because so there is just
2125 * a lot of stuff initialized to zero and it makes building the database
2126 * take hours and hours.
2127 *
2128 * In theory, we should just remove this line and not pass any unused
2129 * information, but I'm not sure enough that this code works so I want
2130 * to hold off on that for now.
2131 */
2132 if (!estate_get_single_value(sm->state, &sval) || sval.value != 0)
2133 return 0;
2134
2135 run_sql(&param_used_callback, &found,
2136 "select * from call_implies where %s and type = %d and parameter = %d and key = '%s';",
2137 get_static_filter(call->fn->symbol), PARAM_USED, param, printed_name);
2138 if (found)
2139 return 0;
2140
2141 /* If the database is not built yet, then assume everything is used */
2142 run_sql(&param_used_callback, &found,
2143 "select * from call_implies where %s and type = %d;",
2144 get_static_filter(call->fn->symbol), PARAM_USED);
2145 if (!found)
2146 return 0;
2147
2148 return 1;
2149 }
2150
2151 struct range_list *intersect_with_real_abs_var_sym(const char *name, struct symbol *sym, struct range_list *start)
2152 {
2153 struct smatch_state *state;
2154
2155 /*
2156 * Here is the difference between implied value and real absolute, say
2157 * you have:
2158 *
2159 * int a = (u8)x;
2160 *
2161 * Then you know that a is 0-255. That's real absolute. But you don't
2162 * know for sure that it actually goes up to 255. So it's not implied.
2163 * Implied indicates a degree of certainty.
2164 *
2165 * But then say you cap "a" at 8. That means you know it goes up to
2166 * 8. So now the implied value is s32min-8. But you can combine it
2167 * with the real absolute to say that actually it's 0-8.
2168 *
2169 * We are combining it here. But now that I think about it, this is
2170 * probably not the ideal place to combine it because it should proably
2171 * be done earlier. Oh well, this is an improvement on what was there
2172 * before so I'm going to commit this code.
2173 *
2174 */
2175
2176 state = get_real_absolute_state_var_sym(name, sym);
2177 if (!state || !estate_rl(state))
2178 return start;
2179
2180 return rl_intersection(estate_rl(state), start);
2181 }
2182
2183 struct range_list *intersect_with_real_abs_expr(struct expression *expr, struct range_list *start)
2184 {
2185 struct smatch_state *state;
2186
2187 state = get_real_absolute_state(expr);
2188 if (!state || !estate_rl(state))
2189 return start;
2190
2191 return rl_intersection(estate_rl(state), start);
2192 }
2193
2194 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
2195 {
2196 struct range_list *rl;
2197
2198 if (estate_is_whole(sm->state))
2199 return;
2200 if (filter_unused_kzalloc_info(call, param, printed_name, sm))
2201 return;
2202 rl = estate_rl(sm->state);
2203 rl = intersect_with_real_abs_var_sym(sm->name, sm->sym, rl);
2204 sql_insert_caller_info(call, PARAM_VALUE, param, printed_name, show_rl(rl));
2205 if (estate_has_fuzzy_max(sm->state))
2206 sql_insert_caller_info(call, FUZZY_MAX, param, printed_name,
2207 sval_to_str(estate_get_fuzzy_max(sm->state)));
2208 }
2209
2210 static void returned_struct_members(int return_id, char *return_ranges, struct expression *expr)
2211 {
2212 struct symbol *returned_sym;
2213 struct sm_state *sm;
2214 const char *param_name;
2215 char *compare_str;
2216 char buf[256];
2217
2218 returned_sym = expr_to_sym(expr);
2219 if (!returned_sym)
2220 return;
2221
2222 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
2223 if (!estate_rl(sm->state))
2224 continue;
2225 if (returned_sym != sm->sym)
2226 continue;
2227
2228 param_name = get_param_name(sm);
2229 if (!param_name)
2230 continue;
2231 if (strcmp(param_name, "$") == 0)
2232 continue;
2233 compare_str = name_sym_to_param_comparison(sm->name, sm->sym);
2234 if (!compare_str && estate_is_whole(sm->state))
2235 continue;
2236 snprintf(buf, sizeof(buf), "%s%s", sm->state->name, compare_str ?: "");
2237
2238 sql_insert_return_states(return_id, return_ranges, PARAM_VALUE,
2239 -1, param_name, buf);
2240 } END_FOR_EACH_SM(sm);
2241 }
2242
2243 static void db_limited_before(void)
2244 {
2245 unmatched_stree = clone_stree(__get_cur_stree());
2246 }
2247
2248 static void db_limited_after(void)
2249 {
2250 free_stree(&unmatched_stree);
2251 }
2252
2253 static int rl_fits_in_type(struct range_list *rl, struct symbol *type)
2254 {
2255 if (type_bits(rl_type(rl)) <= type_bits(type))
2256 return 1;
2257 if (sval_cmp(rl_max(rl), sval_type_max(type)) > 0)
2258 return 0;
2259 if (sval_is_negative(rl_min(rl)) &&
2260 sval_cmp(rl_min(rl), sval_type_min(type)) < 0)
2261 return 0;
2262 return 1;
2263 }
2264
2265 static int basically_the_same(struct range_list *orig, struct range_list *new)
2266 {
2267 if (rl_equiv(orig, new))
2268 return 1;
2269
2270 /*
2271 * The whole range is essentially the same as 0,4096-27777777777 so
2272 * don't overwrite the implications just to store that.
2273 *
2274 */
2275 if (rl_type(orig)->type == SYM_PTR &&
2276 is_whole_rl(orig) &&
2277 rl_min(new).value == 0 &&
2278 rl_max(new).value == valid_ptr_max)
2279 return 1;
2280 return 0;
2281 }
2282
2283 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value, enum info_type op)
2284 {
2285 struct expression *arg;
2286 char *name;
2287 struct symbol *sym;
2288 struct var_sym_list *vsl = NULL;
2289 struct sm_state *sm;
2290 struct symbol *compare_type, *var_type;
2291 struct range_list *rl;
2292 struct range_list *limit;
2293 struct range_list *new;
2294
2295 while (expr->type == EXPR_ASSIGNMENT)
2296 expr = strip_expr(expr->right);
2297 if (expr->type != EXPR_CALL)
2298 return;
2299
2300 arg = get_argument_from_call_expr(expr->args, param);
2301 if (!arg)
2302 return;
2303
2304 name = get_chunk_from_key(arg, key, &sym, &vsl);
2305 if (!name)
2306 return;
2307 if (op != PARAM_LIMIT && !sym)
2308 goto free;
2309
2310 if (strcmp(key, "$") == 0)
2311 compare_type = get_arg_type(expr->fn, param);
2312 else
2313 compare_type = get_member_type_from_key(arg, key);
2314
2315 sm = get_sm_state(SMATCH_EXTRA, name, sym);
2316 if (sm)
2317 rl = estate_rl(sm->state);
2318 else
2319 rl = alloc_whole_rl(compare_type);
2320
2321 if (op == PARAM_LIMIT && !rl_fits_in_type(rl, compare_type))
2322 goto free;
2323
2324 call_results_to_rl(expr, compare_type, value, &limit);
2325 new = rl_intersection(rl, limit);
2326
2327 var_type = get_member_type_from_key(arg, key);
2328 new = cast_rl(var_type, new);
2329
2330 /* We want to preserve the implications here */
2331 if (sm && basically_the_same(estate_rl(sm->state), new))
2332 __set_sm(sm); /* FIXME: Is this really necessary? */
2333 else {
2334 char *tmp_name;
2335 struct symbol *tmp_sym;
2336
2337 tmp_name = map_long_to_short_name_sym(name, sym, &tmp_sym);
2338 if (tmp_name && tmp_sym) {
2339 free_string(name);
2340 name = tmp_name;
2341 sym = tmp_sym;
2342 }
2343
2344 if (op == PARAM_LIMIT)
2345 set_extra_nomod_vsl(name, sym, vsl, NULL, alloc_estate_rl(new));
2346 else
2347 set_extra_mod(name, sym, NULL, alloc_estate_rl(new));
2348 }
2349
2350 free:
2351 free_string(name);
2352 }
2353
2354 static void db_param_limit(struct expression *expr, int param, char *key, char *value)
2355 {
2356 db_param_limit_filter(expr, param, key, value, PARAM_LIMIT);
2357 }
2358
2359 static void db_param_filter(struct expression *expr, int param, char *key, char *value)
2360 {
2361 db_param_limit_filter(expr, param, key, value, PARAM_FILTER);
2362 }
2363
2364 static void db_param_add_set(struct expression *expr, int param, char *key, char *value, enum info_type op)
2365 {
2366 struct expression *arg;
2367 char *name, *tmp_name;
2368 struct symbol *sym, *tmp_sym;
2369 struct symbol *type;
2370 struct smatch_state *state;
2371 struct range_list *new = NULL;
2372 struct range_list *added = NULL;
2373
2374 while (expr->type == EXPR_ASSIGNMENT)
2375 expr = strip_expr(expr->right);
2376 if (expr->type != EXPR_CALL)
2377 return;
2378
2379 arg = get_argument_from_call_expr(expr->args, param);
2380 if (!arg)
2381 return;
2382 type = get_member_type_from_key(arg, key);
2383 name = get_variable_from_key(arg, key, &sym);
2384 if (!name || !sym)
2385 goto free;
2386
2387 state = get_state(SMATCH_EXTRA, name, sym);
2388 if (state)
2389 new = estate_rl(state);
2390
2391 call_results_to_rl(expr, type, value, &added);
2392
2393 if (op == PARAM_SET)
2394 new = added;
2395 else
2396 new = rl_union(new, added);
2397
2398 tmp_name = map_long_to_short_name_sym_nostack(name, sym, &tmp_sym);
2399 if (tmp_name && tmp_sym) {
2400 free_string(name);
2401 name = tmp_name;
2402 sym = tmp_sym;
2403 }
2404 set_extra_mod(name, sym, NULL, alloc_estate_rl(new));
2405 free:
2406 free_string(name);
2407 }
2408
2409 static void db_param_add(struct expression *expr, int param, char *key, char *value)
2410 {
2411 in_param_set = true;
2412 db_param_add_set(expr, param, key, value, PARAM_ADD);
2413 in_param_set = false;
2414 }
2415
2416 static void db_param_set(struct expression *expr, int param, char *key, char *value)
2417 {
2418 in_param_set = true;
2419 db_param_add_set(expr, param, key, value, PARAM_SET);
2420 in_param_set = false;
2421 }
2422
2423 static void db_param_value(struct expression *expr, int param, char *key, char *value)
2424 {
2425 struct expression *call;
2426 char *name;
2427 struct symbol *sym;
2428 struct symbol *type;
2429 struct range_list *rl = NULL;
2430
2431 if (param != -1)
2432 return;
2433
2434 call = expr;
2435 while (call->type == EXPR_ASSIGNMENT)
2436 call = strip_expr(call->right);
2437 if (call->type != EXPR_CALL)
2438 return;
2439
2440 type = get_member_type_from_key(expr->left, key);
2441 name = get_variable_from_key(expr->left, key, &sym);
2442 if (!name || !sym)
2443 goto free;
2444
2445 call_results_to_rl(call, type, value, &rl);
2446
2447 set_extra_mod(name, sym, NULL, alloc_estate_rl(rl));
2448 free:
2449 free_string(name);
2450 }
2451
2452 static void match_call_info(struct expression *expr)
2453 {
2454 struct smatch_state *state;
2455 struct range_list *rl = NULL;
2456 struct expression *arg;
2457 struct symbol *type;
2458 int i = 0;
2459
2460 FOR_EACH_PTR(expr->args, arg) {
2461 type = get_arg_type(expr->fn, i);
2462
2463 get_absolute_rl(arg, &rl);
2464 rl = cast_rl(type, rl);
2465
2466 if (!is_whole_rl(rl)) {
2467 rl = intersect_with_real_abs_expr(arg, rl);
2468 sql_insert_caller_info(expr, PARAM_VALUE, i, "$", show_rl(rl));
2469 }
2470 state = get_state_expr(SMATCH_EXTRA, arg);
2471 if (estate_has_fuzzy_max(state)) {
2472 sql_insert_caller_info(expr, FUZZY_MAX, i, "$",
2473 sval_to_str(estate_get_fuzzy_max(state)));
2474 }
2475 i++;
2476 } END_FOR_EACH_PTR(arg);
2477 }
2478
2479 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
2480 {
2481 struct range_list *rl = NULL;
2482 struct smatch_state *state;
2483 struct symbol *type;
2484 char fullname[256];
2485 sval_t dummy;
2486
2487 if (strcmp(key, "*$") == 0)
2488 snprintf(fullname, sizeof(fullname), "*%s", name);
2489 else if (strncmp(key, "$", 1) == 0)
2490 snprintf(fullname, 256, "%s%s", name, key + 1);
2491 else
2492 return;
2493
2494 type = get_member_type_from_key(symbol_expression(sym), key);
2495 str_to_rl(type, value, &rl);
2496 state = alloc_estate_rl(rl);
2497 if (estate_get_single_value(state, &dummy))
2498 estate_set_hard_max(state);
2499 set_state(SMATCH_EXTRA, fullname, sym, state);
2500 }
2501
2502 static void set_param_hard_max(const char *name, struct symbol *sym, char *key, char *value)
2503 {
2504 struct range_list *rl = NULL;
2505 struct smatch_state *state;
2506 struct symbol *type;
2507 char fullname[256];
2508 sval_t max;
2509
2510 if (strcmp(key, "*$") == 0)
2511 snprintf(fullname, sizeof(fullname), "*%s", name);
2512 else if (strncmp(key, "$", 1) == 0)
2513 snprintf(fullname, 256, "%s%s", name, key + 1);
2514 else
2515 return;
2516
2517 state = get_state(SMATCH_EXTRA, fullname, sym);
2518 if (!state)
2519 return;
2520 type = get_member_type_from_key(symbol_expression(sym), key);
2521 str_to_rl(type, value, &rl);
2522 if (!rl_to_sval(rl, &max))
2523 return;
2524 estate_set_fuzzy_max(state, max);
2525 }
2526
2527 struct smatch_state *get_extra_state(struct expression *expr)
2528 {
2529 char *name;
2530 struct symbol *sym;
2531 struct smatch_state *ret = NULL;
2532 struct range_list *rl;
2533
2534 if (is_pointer(expr) && get_address_rl(expr, &rl))
2535 return alloc_estate_rl(rl);
2536
2537 name = expr_to_known_chunk_sym(expr, &sym);
2538 if (!name)
2539 goto free;
2540
2541 ret = get_state(SMATCH_EXTRA, name, sym);
2542 free:
2543 free_string(name);
2544 return ret;
2545 }
2546
2547 void register_smatch_extra(int id)
2548 {
2549 my_id = id;
2550
2551 add_merge_hook(my_id, &merge_estates);
2552 add_unmatched_state_hook(my_id, &unmatched_state);
2553 select_caller_info_hook(set_param_value, PARAM_VALUE);
2554 select_caller_info_hook(set_param_hard_max, FUZZY_MAX);
2555 select_return_states_before(&db_limited_before);
2556 select_return_states_hook(PARAM_LIMIT, &db_param_limit);
2557 select_return_states_hook(PARAM_FILTER, &db_param_filter);
2558 select_return_states_hook(PARAM_ADD, &db_param_add);
2559 select_return_states_hook(PARAM_SET, &db_param_set);
2560 select_return_states_hook(PARAM_VALUE, &db_param_value);
2561 select_return_states_after(&db_limited_after);
2562 }
2563
2564 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr)
2565 {
2566 struct var_sym_list *links;
2567 struct var_sym *tmp;
2568 struct smatch_state *state;
2569
2570 links = sm->state->data;
2571
2572 FOR_EACH_PTR(links, tmp) {
2573 if (sm->sym == tmp->sym &&
2574 strcmp(sm->name, tmp->var) == 0)
2575 continue;
2576 state = get_state(SMATCH_EXTRA, tmp->var, tmp->sym);
2577 if (!state)
2578 continue;
2579 set_state(SMATCH_EXTRA, tmp->var, tmp->sym, alloc_estate_whole(estate_type(state)));
2580 } END_FOR_EACH_PTR(tmp);
2581 set_state(link_id, sm->name, sm->sym, &undefined);
2582 }
2583
2584 void register_smatch_extra_links(int id)
2585 {
2586 link_id = id;
2587 }
2588
2589 void register_smatch_extra_late(int id)
2590 {
2591 add_merge_hook(link_id, &merge_link_states);
2592 add_modification_hook(link_id, &match_link_modify);
2593 add_hook(&match_dereferences, DEREF_HOOK);
2594 add_hook(&match_pointer_as_array, OP_HOOK);
2595 select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);
2596 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
2597 add_hook(&match_assign, ASSIGNMENT_HOOK);
2598 add_hook(&match_assign, GLOBAL_ASSIGNMENT_HOOK);
2599 add_hook(&unop_expr, OP_HOOK);
2600 add_hook(&asm_expr, ASM_HOOK);
2601
2602 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2603 add_member_info_callback(my_id, struct_member_callback);
2604 add_split_return_callback(&returned_struct_members);
2605
2606 add_hook(&assume_indexes_are_valid, OP_HOOK);
2607 }
Static analysis for C