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nospec: use statement count to mark things as nospec
[smatch.git] / smatch_extra.c
blob57bbf1c9d5b8d53d6e72499eadd61f7554105e01
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 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 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_helper(const char *name, const char *chunk, int len, 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
144 assigned = get_assigned_expr_name_sym(chunk, sym);
145 if (!assigned)
146 return NULL;
147 if (assigned->type == EXPR_CALL)
148 return map_call_to_other_name_sym(name, sym, new_sym);
149 if (assigned->type == EXPR_PREOP && assigned->op == '&') {
150
151 orig_name = expr_to_var_sym(assigned, new_sym);
152 if (!orig_name || !*new_sym)
153 goto free;
154
155 snprintf(buf, sizeof(buf), "%s.%s", orig_name + 1, name + len);
156 ret = alloc_string(buf);
157 free_string(orig_name);
158 return ret;
159 }
160
161 orig_name = expr_to_var_sym(assigned, new_sym);
162 if (!orig_name || !*new_sym)
163 goto free;
164
165 snprintf(buf, sizeof(buf), "%s->%s", orig_name, name + len);
166 ret = alloc_string(buf);
167 free_string(orig_name);
168 return ret;
169 free:
170 free_string(orig_name);
171 return NULL;
172 }
173
174 char *get_other_name_sym(const char *name, struct symbol *sym, struct symbol **new_sym)
175 {
176 char buf[256];
177 char *ret;
178 int len;
179
180 *new_sym = NULL;
181
182 if (!sym || !sym->ident)
183 return NULL;
184
185 ret = get_pointed_at(name, sym, new_sym);
186 if (ret)
187 return ret;
188
189 len = snprintf(buf, sizeof(buf), "%s", name);
190 if (len >= sizeof(buf) - 2)
191 return NULL;
192
193 while (len >= 1) {
194 if (buf[len] == '>' && buf[len - 1] == '-') {
195 len--;
196 buf[len] = '\0';
197 ret = get_other_name_sym_helper(name, buf, len + 2, sym, new_sym);
198 if (ret)
199 return ret;
200 }
201 len--;
202 }
203
204 return NULL;
205 }
206
207 void set_extra_mod(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
208 {
209 char *new_name;
210 struct symbol *new_sym;
211
212 set_extra_mod_helper(name, sym, expr, state);
213 new_name = get_other_name_sym(name, sym, &new_sym);
214 if (new_name && new_sym)
215 set_extra_mod_helper(new_name, new_sym, expr, state);
216 free_string(new_name);
217 }
218
219 static struct expression *chunk_get_array_base(struct expression *expr)
220 {
221 /*
222 * The problem with is_array() is that it only returns true for things
223 * like foo[1] but not for foo[1].bar.
224 *
225 */
226 expr = strip_expr(expr);
227 while (expr && expr->type == EXPR_DEREF)
228 expr = strip_expr(expr->deref);
229 return get_array_base(expr);
230 }
231
232 static int chunk_has_array(struct expression *expr)
233 {
234 return !!chunk_get_array_base(expr);
235 }
236
237 static void clear_array_states(struct expression *array)
238 {
239 struct sm_state *sm;
240
241 sm = get_sm_state_expr(link_id, array);
242 if (sm)
243 match_link_modify(sm, NULL);
244 }
245
246 static void set_extra_array_mod(struct expression *expr, struct smatch_state *state)
247 {
248 struct expression *array;
249 struct var_sym_list *vsl;
250 struct var_sym *vs;
251 char *name;
252 struct symbol *sym;
253
254 array = chunk_get_array_base(expr);
255
256 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
257 if (!name || !vsl) {
258 clear_array_states(array);
259 goto free;
260 }
261
262 FOR_EACH_PTR(vsl, vs) {
263 store_link(link_id, vs->var, vs->sym, name, sym);
264 } END_FOR_EACH_PTR(vs);
265
266 call_extra_mod_hooks(name, sym, expr, state);
267 set_state(SMATCH_EXTRA, name, sym, state);
268 free:
269 free_string(name);
270 }
271
272 void set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
273 {
274 struct symbol *sym;
275 char *name;
276
277 if (chunk_has_array(expr)) {
278 set_extra_array_mod(expr, state);
279 return;
280 }
281
282 expr = strip_expr(expr);
283 name = expr_to_var_sym(expr, &sym);
284 if (!name || !sym)
285 goto free;
286 set_extra_mod(name, sym, expr, state);
287 free:
288 free_string(name);
289 }
290
291 void set_extra_nomod(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
292 {
293 char *new_name;
294 struct symbol *new_sym;
295 struct relation *rel;
296 struct smatch_state *orig_state;
297
298 orig_state = get_state(SMATCH_EXTRA, name, sym);
299
300 /* don't save unknown states if leaving it blank is the same */
301 if (!orig_state && estate_is_unknown(state))
302 return;
303
304 new_name = get_other_name_sym(name, sym, &new_sym);
305 if (new_name && new_sym)
306 set_extra_nomod_helper(new_name, new_sym, expr, state);
307 free_string(new_name);
308
309 if (!estate_related(orig_state)) {
310 set_extra_nomod_helper(name, sym, expr, state);
311 return;
312 }
313
314 set_related(state, estate_related(orig_state));
315 FOR_EACH_PTR(estate_related(orig_state), rel) {
316 struct smatch_state *estate;
317
318 if (option_debug_related)
319 sm_msg("%s updating related %s to %s", name, rel->name, state->name);
320 estate = get_state(SMATCH_EXTRA, rel->name, rel->sym);
321 if (!estate)
322 continue;
323 set_extra_nomod_helper(rel->name, rel->sym, expr, clone_estate_cast(estate_type(estate), state));
324 } END_FOR_EACH_PTR(rel);
325 }
326
327 void set_extra_nomod_vsl(const char *name, struct symbol *sym, struct var_sym_list *vsl, struct expression *expr, struct smatch_state *state)
328 {
329 struct var_sym *vs;
330
331 FOR_EACH_PTR(vsl, vs) {
332 store_link(link_id, vs->var, vs->sym, name, sym);
333 } END_FOR_EACH_PTR(vs);
334
335 set_extra_nomod(name, sym, expr, state);
336 }
337
338 /*
339 * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
340 */
341 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
342 {
343 struct var_sym_list *vsl;
344 struct var_sym *vs;
345 char *name;
346 struct symbol *sym;
347
348 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
349 if (!name || !vsl)
350 goto free;
351 FOR_EACH_PTR(vsl, vs) {
352 store_link(link_id, vs->var, vs->sym, name, sym);
353 } END_FOR_EACH_PTR(vs);
354
355 set_extra_nomod(name, sym, expr, state);
356 free:
357 free_string(name);
358 }
359
360 static void set_extra_true_false(const char *name, struct symbol *sym,
361 struct smatch_state *true_state,
362 struct smatch_state *false_state)
363 {
364 char *new_name;
365 struct symbol *new_sym;
366 struct relation *rel;
367 struct smatch_state *orig_state;
368
369 if (!true_state && !false_state)
370 return;
371
372 if (in_warn_on_macro())
373 return;
374
375 new_name = get_other_name_sym(name, sym, &new_sym);
376 if (new_name && new_sym)
377 set_true_false_states(SMATCH_EXTRA, new_name, new_sym, true_state, false_state);
378 free_string(new_name);
379
380 orig_state = get_state(SMATCH_EXTRA, name, sym);
381
382 if (!estate_related(orig_state)) {
383 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
384 return;
385 }
386
387 if (true_state)
388 set_related(true_state, estate_related(orig_state));
389 if (false_state)
390 set_related(false_state, estate_related(orig_state));
391
392 FOR_EACH_PTR(estate_related(orig_state), rel) {
393 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
394 true_state, false_state);
395 } END_FOR_EACH_PTR(rel);
396 }
397
398 static void set_extra_chunk_true_false(struct expression *expr,
399 struct smatch_state *true_state,
400 struct smatch_state *false_state)
401 {
402 struct var_sym_list *vsl;
403 struct var_sym *vs;
404 struct symbol *type;
405 char *name;
406 struct symbol *sym;
407
408 if (in_warn_on_macro())
409 return;
410
411 type = get_type(expr);
412 if (!type)
413 return;
414
415 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
416 if (!name || !vsl)
417 goto free;
418 FOR_EACH_PTR(vsl, vs) {
419 store_link(link_id, vs->var, vs->sym, name, sym);
420 } END_FOR_EACH_PTR(vs);
421
422 set_true_false_states(SMATCH_EXTRA, name, sym,
423 clone_estate(true_state),
424 clone_estate(false_state));
425 free:
426 free_string(name);
427 }
428
429 static void set_extra_expr_true_false(struct expression *expr,
430 struct smatch_state *true_state,
431 struct smatch_state *false_state)
432 {
433 char *name;
434 struct symbol *sym;
435 sval_t sval;
436
437 if (!true_state && !false_state)
438 return;
439
440 if (get_value(expr, &sval))
441 return;
442
443 expr = strip_expr(expr);
444 name = expr_to_var_sym(expr, &sym);
445 if (!name || !sym) {
446 free_string(name);
447 set_extra_chunk_true_false(expr, true_state, false_state);
448 return;
449 }
450 set_extra_true_false(name, sym, true_state, false_state);
451 free_string(name);
452 }
453
454 static int get_countdown_info(struct expression *condition, struct expression **unop, int *op, sval_t *right)
455 {
456 struct expression *unop_expr;
457 int comparison;
458 sval_t limit;
459
460 right->type = &int_ctype;
461 right->value = 0;
462
463 condition = strip_expr(condition);
464
465 if (condition->type == EXPR_COMPARE) {
466 comparison = remove_unsigned_from_comparison(condition->op);
467
468 if (comparison != SPECIAL_GTE && comparison != '>')
469 return 0;
470 if (!get_value(condition->right, &limit))
471 return 0;
472
473 unop_expr = condition->left;
474 if (unop_expr->type != EXPR_PREOP && unop_expr->type != EXPR_POSTOP)
475 return 0;
476 if (unop_expr->op != SPECIAL_DECREMENT)
477 return 0;
478
479 *unop = unop_expr;
480 *op = comparison;
481 *right = limit;
482
483 return 1;
484 }
485
486 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
487 return 0;
488 if (condition->op != SPECIAL_DECREMENT)
489 return 0;
490
491 *unop = condition;
492 *op = '>';
493
494 return 1;
495 }
496
497 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
498 {
499 struct expression *iter_var;
500 struct expression *condition, *unop;
501 struct sm_state *sm;
502 struct smatch_state *estate;
503 int op;
504 sval_t start, right;
505
506 right.type = &int_ctype;
507 right.value = 0;
508
509 condition = strip_expr(loop->iterator_pre_condition);
510 if (!condition)
511 return NULL;
512
513 if (!get_countdown_info(condition, &unop, &op, &right))
514 return NULL;
515
516 iter_var = unop->unop;
517
518 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
519 if (!sm)
520 return NULL;
521 if (sval_cmp(estate_min(sm->state), right) < 0)
522 return NULL;
523 start = estate_max(sm->state);
524 if (sval_cmp(start, right) <= 0)
525 return NULL;
526 if (!sval_is_max(start))
527 start.value--;
528
529 if (op == SPECIAL_GTE)
530 right.value--;
531
532 if (unop->type == EXPR_PREOP) {
533 right.value++;
534 estate = alloc_estate_range(right, start);
535 if (estate_has_hard_max(sm->state))
536 estate_set_hard_max(estate);
537 estate_copy_fuzzy_max(estate, sm->state);
538 set_extra_expr_mod(iter_var, estate);
539 }
540 if (unop->type == EXPR_POSTOP) {
541 estate = alloc_estate_range(right, start);
542 if (estate_has_hard_max(sm->state))
543 estate_set_hard_max(estate);
544 estate_copy_fuzzy_max(estate, sm->state);
545 set_extra_expr_mod(iter_var, estate);
546 }
547 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
548 }
549
550 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
551 struct expression *condition)
552 {
553 struct expression *iter_var;
554 struct sm_state *sm;
555 struct smatch_state *estate;
556 sval_t start, end, max;
557
558 iter_var = iter_expr->unop;
559 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
560 if (!sm)
561 return NULL;
562 if (!estate_get_single_value(sm->state, &start))
563 return NULL;
564 if (!get_implied_value(condition->right, &end))
565 return NULL;
566
567 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
568 return NULL;
569
570 switch (condition->op) {
571 case SPECIAL_UNSIGNED_LT:
572 case SPECIAL_NOTEQUAL:
573 case '<':
574 if (!sval_is_min(end))
575 end.value--;
576 break;
577 case SPECIAL_UNSIGNED_LTE:
578 case SPECIAL_LTE:
579 break;
580 default:
581 return NULL;
582 }
583 if (sval_cmp(end, start) < 0)
584 return NULL;
585 estate = alloc_estate_range(start, end);
586 if (get_hard_max(condition->right, &max)) {
587 if (!get_macro_name(condition->pos))
588 estate_set_hard_max(estate);
589 if (condition->op == '<' ||
590 condition->op == SPECIAL_UNSIGNED_LT ||
591 condition->op == SPECIAL_NOTEQUAL)
592 max.value--;
593 estate_set_fuzzy_max(estate, max);
594 }
595 set_extra_expr_mod(iter_var, estate);
596 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
597 }
598
599 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
600 struct expression *condition)
601 {
602 struct expression *iter_var;
603 struct sm_state *sm;
604 struct smatch_state *estate;
605 sval_t start, end;
606
607 iter_var = iter_expr->unop;
608 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
609 if (!sm)
610 return NULL;
611 if (!estate_get_single_value(sm->state, &start))
612 return NULL;
613 if (!get_implied_min(condition->right, &end))
614 end = sval_type_min(get_type(iter_var));
615 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
616 return NULL;
617
618 switch (condition->op) {
619 case SPECIAL_NOTEQUAL:
620 case '>':
621 if (!sval_is_min(end) && !sval_is_max(end))
622 end.value++;
623 break;
624 case SPECIAL_GTE:
625 break;
626 default:
627 return NULL;
628 }
629 if (sval_cmp(end, start) > 0)
630 return NULL;
631 estate = alloc_estate_range(end, start);
632 estate_set_hard_max(estate);
633 estate_set_fuzzy_max(estate, estate_get_fuzzy_max(estate));
634 set_extra_expr_mod(iter_var, estate);
635 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
636 }
637
638 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
639 {
640 struct expression *iter_expr;
641 struct expression *condition;
642
643 if (!loop->iterator_post_statement)
644 return NULL;
645 if (loop->iterator_post_statement->type != STMT_EXPRESSION)
646 return NULL;
647 iter_expr = loop->iterator_post_statement->expression;
648 if (!loop->iterator_pre_condition)
649 return NULL;
650 if (loop->iterator_pre_condition->type != EXPR_COMPARE)
651 return NULL;
652 condition = loop->iterator_pre_condition;
653
654 if (iter_expr->op == SPECIAL_INCREMENT)
655 return handle_canonical_for_inc(iter_expr, condition);
656 if (iter_expr->op == SPECIAL_DECREMENT)
657 return handle_canonical_for_dec(iter_expr, condition);
658 return NULL;
659 }
660
661 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct stree **stree)
662 {
663 struct sm_state *ret;
664
665 /*
666 * Canonical loops are a hack. The proper way to handle this is to
667 * use two passes, but unfortunately, doing two passes makes parsing
668 * code twice as slow.
669 *
670 * What we do is we set the inside state here, which overwrites whatever
671 * __extra_match_condition() does. Then we set the outside state in
672 * __extra_pre_loop_hook_after().
673 *
674 */
675 __push_fake_cur_stree();
676 if (!loop->iterator_post_statement)
677 ret = handle_canonical_while_count_down(loop);
678 else
679 ret = handle_canonical_for_loops(loop);
680 *stree = __pop_fake_cur_stree();
681 return ret;
682 }
683
684 int __iterator_unchanged(struct sm_state *sm)
685 {
686 if (!sm)
687 return 0;
688 if (get_sm_state(my_id, sm->name, sm->sym) == sm)
689 return 1;
690 return 0;
691 }
692
693 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
694 {
695 struct expression *unop;
696 int op;
697 sval_t limit, after_value;
698
699 if (!get_countdown_info(condition, &unop, &op, &limit))
700 return;
701 after_value = estate_min(sm->state);
702 after_value.value--;
703 set_extra_mod(sm->name, sm->sym, condition->unop, alloc_estate_sval(after_value));
704 }
705
706 void __extra_pre_loop_hook_after(struct sm_state *sm,
707 struct statement *iterator,
708 struct expression *condition)
709 {
710 struct expression *iter_expr;
711 sval_t limit;
712 struct smatch_state *state;
713
714 if (!iterator) {
715 while_count_down_after(sm, condition);
716 return;
717 }
718
719 iter_expr = iterator->expression;
720
721 if (condition->type != EXPR_COMPARE)
722 return;
723 if (iter_expr->op == SPECIAL_INCREMENT) {
724 limit = sval_binop(estate_max(sm->state), '+',
725 sval_type_val(estate_type(sm->state), 1));
726 } else {
727 limit = sval_binop(estate_min(sm->state), '-',
728 sval_type_val(estate_type(sm->state), 1));
729 }
730 if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
731 if (iter_expr->op == SPECIAL_INCREMENT)
732 state = alloc_estate_range(estate_min(sm->state), limit);
733 else
734 state = alloc_estate_range(limit, estate_max(sm->state));
735 } else {
736 state = alloc_estate_sval(limit);
737 }
738 if (!estate_has_hard_max(sm->state)) {
739 estate_clear_hard_max(state);
740 }
741 if (estate_has_fuzzy_max(sm->state)) {
742 sval_t hmax = estate_get_fuzzy_max(sm->state);
743 sval_t max = estate_max(sm->state);
744
745 if (sval_cmp(hmax, max) != 0)
746 estate_clear_fuzzy_max(state);
747 } else if (!estate_has_fuzzy_max(sm->state)) {
748 estate_clear_fuzzy_max(state);
749 }
750
751 set_extra_mod(sm->name, sm->sym, iter_expr, state);
752 }
753
754 static struct stree *unmatched_stree;
755 static struct smatch_state *unmatched_state(struct sm_state *sm)
756 {
757 struct smatch_state *state;
758
759 if (unmatched_stree) {
760 state = get_state_stree(unmatched_stree, SMATCH_EXTRA, sm->name, sm->sym);
761 if (state)
762 return state;
763 }
764 if (parent_is_gone_var_sym(sm->name, sm->sym))
765 return alloc_estate_empty();
766 return alloc_estate_whole(estate_type(sm->state));
767 }
768
769 static void clear_the_pointed_at(struct expression *expr)
770 {
771 struct stree *stree;
772 char *name;
773 struct symbol *sym;
774 struct sm_state *tmp;
775
776 name = expr_to_var_sym(expr, &sym);
777 if (!name || !sym)
778 goto free;
779
780 stree = __get_cur_stree();
781 FOR_EACH_MY_SM(SMATCH_EXTRA, stree, tmp) {
782 if (tmp->name[0] != '*')
783 continue;
784 if (tmp->sym != sym)
785 continue;
786 if (strcmp(tmp->name + 1, name) != 0)
787 continue;
788 set_extra_mod(tmp->name, tmp->sym, expr, alloc_estate_whole(estate_type(tmp->state)));
789 } END_FOR_EACH_SM(tmp);
790
791 free:
792 free_string(name);
793 }
794
795 static int is_const_param(struct expression *expr, int param)
796 {
797 struct symbol *type;
798
799 type = get_arg_type(expr, param);
800 if (!type)
801 return 0;
802 if (type->ctype.modifiers & MOD_CONST)
803 return 1;
804 return 0;
805 }
806
807 static void match_function_call(struct expression *expr)
808 {
809 struct expression *arg;
810 struct expression *tmp;
811 int param = -1;
812
813 /* if we have the db this is handled in smatch_function_hooks.c */
814 if (!option_no_db)
815 return;
816 if (inlinable(expr->fn))
817 return;
818
819 FOR_EACH_PTR(expr->args, arg) {
820 param++;
821 if (is_const_param(expr->fn, param))
822 continue;
823 tmp = strip_expr(arg);
824 if (tmp->type == EXPR_PREOP && tmp->op == '&')
825 set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
826 else
827 clear_the_pointed_at(tmp);
828 } END_FOR_EACH_PTR(arg);
829 }
830
831 static int values_fit_type(struct expression *left, struct expression *right)
832 {
833 struct range_list *rl;
834 struct symbol *type;
835
836 type = get_type(left);
837 if (!type)
838 return 0;
839 get_absolute_rl(right, &rl);
840 if (type_unsigned(type) && sval_is_negative(rl_min(rl)))
841 return 0;
842 if (sval_cmp(sval_type_min(type), rl_min(rl)) > 0)
843 return 0;
844 if (sval_cmp(sval_type_max(type), rl_max(rl)) < 0)
845 return 0;
846 return 1;
847 }
848
849 static void save_chunk_info(struct expression *left, struct expression *right)
850 {
851 struct var_sym_list *vsl;
852 struct var_sym *vs;
853 struct expression *add_expr;
854 struct symbol *type;
855 sval_t sval;
856 char *name;
857 struct symbol *sym;
858
859 if (right->type != EXPR_BINOP || right->op != '-')
860 return;
861 if (!get_value(right->left, &sval))
862 return;
863 if (!expr_to_sym(right->right))
864 return;
865
866 add_expr = binop_expression(left, '+', right->right);
867 type = get_type(add_expr);
868 if (!type)
869 return;
870 name = expr_to_chunk_sym_vsl(add_expr, &sym, &vsl);
871 if (!name || !vsl)
872 goto free;
873 FOR_EACH_PTR(vsl, vs) {
874 store_link(link_id, vs->var, vs->sym, name, sym);
875 } END_FOR_EACH_PTR(vs);
876
877 set_state(SMATCH_EXTRA, name, sym, alloc_estate_sval(sval_cast(type, sval)));
878 free:
879 free_string(name);
880 }
881
882 static void do_array_assign(struct expression *left, int op, struct expression *right)
883 {
884 struct range_list *rl;
885
886 if (op == '=') {
887 get_absolute_rl(right, &rl);
888 rl = cast_rl(get_type(left), rl);
889 } else {
890 rl = alloc_whole_rl(get_type(left));
891 }
892
893 set_extra_array_mod(left, alloc_estate_rl(rl));
894 }
895
896 static void match_vanilla_assign(struct expression *left, struct expression *right)
897 {
898 struct range_list *orig_rl = NULL;
899 struct range_list *rl = NULL;
900 struct symbol *right_sym;
901 struct symbol *left_type;
902 struct symbol *right_type;
903 char *right_name = NULL;
904 struct symbol *sym;
905 char *name;
906 sval_t sval, max;
907 struct smatch_state *state;
908 int comparison;
909
910 if (is_struct(left))
911 return;
912
913 save_chunk_info(left, right);
914
915 name = expr_to_var_sym(left, &sym);
916 if (!name) {
917 if (chunk_has_array(left))
918 do_array_assign(left, '=', right);
919 return;
920 }
921
922 left_type = get_type(left);
923 right_type = get_type(right);
924
925 right_name = expr_to_var_sym(right, &right_sym);
926
927 if (!__in_fake_assign &&
928 !(right->type == EXPR_PREOP && right->op == '&') &&
929 right_name && right_sym &&
930 values_fit_type(left, strip_expr(right)) &&
931 !has_symbol(right, sym)) {
932 set_equiv(left, right);
933 goto free;
934 }
935
936 if (is_pointer(right) && get_address_rl(right, &rl)) {
937 state = alloc_estate_rl(rl);
938 goto done;
939 }
940
941 if (get_implied_value(right, &sval)) {
942 state = alloc_estate_sval(sval_cast(left_type, sval));
943 goto done;
944 }
945
946 if (__in_fake_assign) {
947 struct smatch_state *right_state;
948 sval_t sval;
949
950 if (get_value(right, &sval)) {
951 sval = sval_cast(left_type, sval);
952 state = alloc_estate_sval(sval);
953 goto done;
954 }
955
956 right_state = get_state(SMATCH_EXTRA, right_name, right_sym);
957 if (right_state) {
958 /* simple assignment */
959 state = clone_estate(right_state);
960 goto done;
961 }
962
963 state = alloc_estate_rl(alloc_whole_rl(left_type));
964 goto done;
965 }
966
967 comparison = get_comparison(left, right);
968 if (comparison) {
969 comparison = flip_comparison(comparison);
970 get_implied_rl(left, &orig_rl);
971 }
972
973 if (get_implied_rl(right, &rl)) {
974 rl = cast_rl(left_type, rl);
975 if (orig_rl)
976 filter_by_comparison(&rl, comparison, orig_rl);
977 state = alloc_estate_rl(rl);
978 if (get_hard_max(right, &max)) {
979 estate_set_hard_max(state);
980 estate_set_fuzzy_max(state, max);
981 }
982 } else {
983 rl = alloc_whole_rl(right_type);
984 rl = cast_rl(left_type, rl);
985 if (orig_rl)
986 filter_by_comparison(&rl, comparison, orig_rl);
987 state = alloc_estate_rl(rl);
988 }
989
990 done:
991 set_extra_mod(name, sym, left, state);
992 free:
993 free_string(right_name);
994 }
995
996 static int op_remove_assign(int op)
997 {
998 switch (op) {
999 case SPECIAL_ADD_ASSIGN:
1000 return '+';
1001 case SPECIAL_SUB_ASSIGN:
1002 return '-';
1003 case SPECIAL_MUL_ASSIGN:
1004 return '*';
1005 case SPECIAL_DIV_ASSIGN:
1006 return '/';
1007 case SPECIAL_MOD_ASSIGN:
1008 return '%';
1009 case SPECIAL_AND_ASSIGN:
1010 return '&';
1011 case SPECIAL_OR_ASSIGN:
1012 return '|';
1013 case SPECIAL_XOR_ASSIGN:
1014 return '^';
1015 case SPECIAL_SHL_ASSIGN:
1016 return SPECIAL_LEFTSHIFT;
1017 case SPECIAL_SHR_ASSIGN:
1018 return SPECIAL_RIGHTSHIFT;
1019 default:
1020 return op;
1021 }
1022 }
1023
1024 static void match_assign(struct expression *expr)
1025 {
1026 struct range_list *rl = NULL;
1027 struct expression *left;
1028 struct expression *right;
1029 struct expression *binop_expr;
1030 struct symbol *left_type;
1031 struct symbol *sym;
1032 char *name;
1033 sval_t left_min, left_max;
1034 sval_t right_min, right_max;
1035 sval_t res_min, res_max;
1036
1037 left = strip_expr(expr->left);
1038
1039 right = strip_parens(expr->right);
1040 if (right->type == EXPR_CALL && sym_name_is("__builtin_expect", right->fn))
1041 right = get_argument_from_call_expr(right->args, 0);
1042 while (right->type == EXPR_ASSIGNMENT && right->op == '=')
1043 right = strip_parens(right->left);
1044
1045 if (expr->op == '=' && is_condition(expr->right))
1046 return; /* handled in smatch_condition.c */
1047 if (expr->op == '=' && right->type == EXPR_CALL)
1048 return; /* handled in smatch_function_hooks.c */
1049 if (expr->op == '=') {
1050 match_vanilla_assign(left, right);
1051 return;
1052 }
1053
1054 name = expr_to_var_sym(left, &sym);
1055 if (!name)
1056 return;
1057
1058 left_type = get_type(left);
1059
1060 res_min = sval_type_min(left_type);
1061 res_max = sval_type_max(left_type);
1062
1063 switch (expr->op) {
1064 case SPECIAL_ADD_ASSIGN:
1065 get_absolute_max(left, &left_max);
1066 get_absolute_max(right, &right_max);
1067 if (sval_binop_overflows(left_max, '+', sval_cast(left_type, right_max)))
1068 break;
1069 if (get_implied_min(left, &left_min) &&
1070 !sval_is_negative_min(left_min) &&
1071 get_implied_min(right, &right_min) &&
1072 !sval_is_negative_min(right_min)) {
1073 res_min = sval_binop(left_min, '+', right_min);
1074 res_min = sval_cast(left_type, res_min);
1075 }
1076 if (inside_loop()) /* we are assuming loops don't lead to wrapping */
1077 break;
1078 res_max = sval_binop(left_max, '+', right_max);
1079 res_max = sval_cast(left_type, res_max);
1080 break;
1081 case SPECIAL_SUB_ASSIGN:
1082 if (get_implied_max(left, &left_max) &&
1083 !sval_is_max(left_max) &&
1084 get_implied_min(right, &right_min) &&
1085 !sval_is_min(right_min)) {
1086 res_max = sval_binop(left_max, '-', right_min);
1087 res_max = sval_cast(left_type, res_max);
1088 }
1089 if (inside_loop())
1090 break;
1091 if (get_implied_min(left, &left_min) &&
1092 !sval_is_min(left_min) &&
1093 get_implied_max(right, &right_max) &&
1094 !sval_is_max(right_max)) {
1095 res_min = sval_binop(left_min, '-', right_max);
1096 res_min = sval_cast(left_type, res_min);
1097 }
1098 break;
1099 case SPECIAL_AND_ASSIGN:
1100 case SPECIAL_MOD_ASSIGN:
1101 case SPECIAL_SHL_ASSIGN:
1102 case SPECIAL_SHR_ASSIGN:
1103 case SPECIAL_OR_ASSIGN:
1104 case SPECIAL_XOR_ASSIGN:
1105 case SPECIAL_MUL_ASSIGN:
1106 case SPECIAL_DIV_ASSIGN:
1107 binop_expr = binop_expression(expr->left,
1108 op_remove_assign(expr->op),
1109 expr->right);
1110 if (get_absolute_rl(binop_expr, &rl)) {
1111 rl = cast_rl(left_type, rl);
1112 set_extra_mod(name, sym, left, alloc_estate_rl(rl));
1113 goto free;
1114 }
1115 break;
1116 }
1117 rl = cast_rl(left_type, alloc_rl(res_min, res_max));
1118 set_extra_mod(name, sym, left, alloc_estate_rl(rl));
1119 free:
1120 free_string(name);
1121 }
1122
1123 static struct smatch_state *increment_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 max = sval_type_max(max.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 struct smatch_state *decrement_state(struct smatch_state *state)
1142 {
1143 sval_t min = estate_min(state);
1144 sval_t max = estate_max(state);
1145
1146 if (!estate_rl(state))
1147 return NULL;
1148
1149 if (inside_loop())
1150 min = sval_type_min(min.type);
1151
1152 if (!sval_is_min(min) && !sval_is_max(min))
1153 min.value--;
1154 if (!sval_is_min(max) && !sval_is_max(max))
1155 max.value--;
1156 return alloc_estate_range(min, max);
1157 }
1158
1159 static void clear_pointed_at_state(struct expression *expr)
1160 {
1161 struct symbol *type;
1162
1163 /*
1164 * ALERT: This is sort of a mess. If it's is a struct assigment like
1165 * "foo = bar;", then that's handled by smatch_struct_assignment.c.
1166 * the same thing for p++ where "p" is a struct. Most modifications
1167 * are handled by the assignment hook or the db. Smatch_extra.c doesn't
1168 * use smatch_modification.c because we have to get the ordering right
1169 * or something. So if you have p++ where p is a pointer to a standard
1170 * c type then we handle that here. What a mess.
1171 */
1172 expr = strip_expr(expr);
1173 type = get_type(expr);
1174 if (!type || type->type != SYM_PTR)
1175 return;
1176 type = get_real_base_type(type);
1177 if (!type || type->type != SYM_BASETYPE)
1178 return;
1179 set_extra_expr_nomod(deref_expression(expr), alloc_estate_whole(type));
1180 }
1181
1182 static void unop_expr(struct expression *expr)
1183 {
1184 struct smatch_state *state;
1185
1186 if (expr->smatch_flags & Handled)
1187 return;
1188
1189 switch (expr->op) {
1190 case SPECIAL_INCREMENT:
1191 state = get_state_expr(SMATCH_EXTRA, expr->unop);
1192 state = increment_state(state);
1193 if (!state)
1194 state = alloc_estate_whole(get_type(expr));
1195 set_extra_expr_mod(expr->unop, state);
1196 clear_pointed_at_state(expr->unop);
1197 break;
1198 case SPECIAL_DECREMENT:
1199 state = get_state_expr(SMATCH_EXTRA, expr->unop);
1200 state = decrement_state(state);
1201 if (!state)
1202 state = alloc_estate_whole(get_type(expr));
1203 set_extra_expr_mod(expr->unop, state);
1204 clear_pointed_at_state(expr->unop);
1205 break;
1206 default:
1207 return;
1208 }
1209 }
1210
1211 static void asm_expr(struct statement *stmt)
1212 {
1213
1214 struct expression *expr;
1215 struct symbol *type;
1216 int state = 0;
1217
1218 FOR_EACH_PTR(stmt->asm_outputs, expr) {
1219 switch (state) {
1220 case 0: /* identifier */
1221 case 1: /* constraint */
1222 state++;
1223 continue;
1224 case 2: /* expression */
1225 state = 0;
1226 type = get_type(strip_expr(expr));
1227 set_extra_expr_mod(expr, alloc_estate_whole(type));
1228 continue;
1229 }
1230 } END_FOR_EACH_PTR(expr);
1231 }
1232
1233 static void check_dereference(struct expression *expr)
1234 {
1235 struct smatch_state *state;
1236
1237 if (__in_fake_assign)
1238 return;
1239 if (outside_of_function())
1240 return;
1241 state = get_extra_state(expr);
1242 if (state) {
1243 struct range_list *rl;
1244
1245 rl = rl_intersection(estate_rl(state), valid_ptr_rl);
1246 if (rl_equiv(rl, estate_rl(state)))
1247 return;
1248 set_extra_expr_nomod(expr, alloc_estate_rl(rl));
1249 } else {
1250 set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
1251 }
1252 }
1253
1254 static void match_dereferences(struct expression *expr)
1255 {
1256 if (expr->type != EXPR_PREOP)
1257 return;
1258 /* it's saying that foo[1] = bar dereferences foo[1] */
1259 if (is_array(expr))
1260 return;
1261 check_dereference(expr->unop);
1262 }
1263
1264 static void match_pointer_as_array(struct expression *expr)
1265 {
1266 if (!is_array(expr))
1267 return;
1268 check_dereference(get_array_base(expr));
1269 }
1270
1271 static void find_dereferences(struct expression *expr)
1272 {
1273 while (expr->type == EXPR_PREOP) {
1274 if (expr->op == '*')
1275 check_dereference(expr->unop);
1276 expr = strip_expr(expr->unop);
1277 }
1278 }
1279
1280 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
1281 {
1282 struct symbol *sym;
1283 char *name;
1284
1285 name = get_variable_from_key(arg, key, &sym);
1286 if (name && sym) {
1287 struct smatch_state *orig, *new;
1288 struct range_list *rl;
1289
1290 orig = get_state(SMATCH_EXTRA, name, sym);
1291 if (orig) {
1292 rl = rl_intersection(estate_rl(orig),
1293 alloc_rl(valid_ptr_min_sval,
1294 valid_ptr_max_sval));
1295 new = alloc_estate_rl(rl);
1296 } else {
1297 new = alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval);
1298 }
1299
1300 set_extra_nomod(name, sym, NULL, new);
1301 }
1302 free_string(name);
1303
1304 find_dereferences(arg);
1305 }
1306
1307 static sval_t add_one(sval_t sval)
1308 {
1309 sval.value++;
1310 return sval;
1311 }
1312
1313 static int handle_postop_inc(struct expression *left, int op, struct expression *right)
1314 {
1315 struct statement *stmt;
1316 struct expression *cond;
1317 struct smatch_state *true_state, *false_state;
1318 sval_t start;
1319 sval_t limit;
1320
1321 /*
1322 * If we're decrementing here then that's a canonical while count down
1323 * so it's handled already. We're only handling loops like:
1324 * i = 0;
1325 * do { ... } while (i++ < 3);
1326 */
1327
1328 if (left->type != EXPR_POSTOP || left->op != SPECIAL_INCREMENT)
1329 return 0;
1330
1331 stmt = __cur_stmt->parent;
1332 if (!stmt)
1333 return 0;
1334 if (stmt->type == STMT_COMPOUND)
1335 stmt = stmt->parent;
1336 if (!stmt || stmt->type != STMT_ITERATOR || !stmt->iterator_post_condition)
1337 return 0;
1338
1339 cond = strip_expr(stmt->iterator_post_condition);
1340 if (cond->type != EXPR_COMPARE || cond->op != op)
1341 return 0;
1342 if (left != strip_expr(cond->left) || right != strip_expr(cond->right))
1343 return 0;
1344
1345 if (!get_implied_value(left->unop, &start))
1346 return 0;
1347 if (!get_implied_value(right, &limit))
1348 return 0;
1349
1350 if (sval_cmp(start, limit) > 0)
1351 return 0;
1352
1353 switch (op) {
1354 case '<':
1355 case SPECIAL_UNSIGNED_LT:
1356 break;
1357 case SPECIAL_LTE:
1358 case SPECIAL_UNSIGNED_LTE:
1359 limit = add_one(limit);
1360 default:
1361 return 0;
1362
1363 }
1364
1365 true_state = alloc_estate_range(add_one(start), limit);
1366 false_state = alloc_estate_range(add_one(limit), add_one(limit));
1367
1368 /* Currently we just discard the false state but when two passes is
1369 * implimented correctly then it will use it.
1370 */
1371
1372 set_extra_expr_true_false(left->unop, true_state, false_state);
1373
1374 return 1;
1375 }
1376
1377 bool is_impossible_variable(struct expression *expr)
1378 {
1379 struct smatch_state *state;
1380
1381 state = get_extra_state(expr);
1382 if (state && !estate_rl(state))
1383 return true;
1384 return false;
1385 }
1386
1387 static bool in_macro(struct expression *left, struct expression *right)
1388 {
1389 if (!left || !right)
1390 return 0;
1391 if (left->pos.line != right->pos.line || left->pos.pos != right->pos.pos)
1392 return 0;
1393 if (get_macro_name(left->pos))
1394 return 1;
1395 return 0;
1396 }
1397
1398 static void handle_comparison(struct symbol *type, struct expression *left, int op, struct expression *right)
1399 {
1400 struct range_list *left_orig;
1401 struct range_list *left_true;
1402 struct range_list *left_false;
1403 struct range_list *right_orig;
1404 struct range_list *right_true;
1405 struct range_list *right_false;
1406 struct smatch_state *left_true_state;
1407 struct smatch_state *left_false_state;
1408 struct smatch_state *right_true_state;
1409 struct smatch_state *right_false_state;
1410 sval_t dummy, hard_max;
1411 int left_postop = 0;
1412 int right_postop = 0;
1413
1414 if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
1415 if (left->type == EXPR_POSTOP) {
1416 left->smatch_flags |= Handled;
1417 left_postop = left->op;
1418 if (handle_postop_inc(left, op, right))
1419 return;
1420 }
1421 left = strip_parens(left->unop);
1422 }
1423 while (left->type == EXPR_ASSIGNMENT)
1424 left = strip_parens(left->left);
1425
1426 if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
1427 if (right->type == EXPR_POSTOP) {
1428 right->smatch_flags |= Handled;
1429 right_postop = right->op;
1430 }
1431 right = strip_parens(right->unop);
1432 }
1433
1434 if (is_impossible_variable(left) || is_impossible_variable(right))
1435 return;
1436
1437 get_real_absolute_rl(left, &left_orig);
1438 left_orig = cast_rl(type, left_orig);
1439
1440 get_real_absolute_rl(right, &right_orig);
1441 right_orig = cast_rl(type, right_orig);
1442
1443 split_comparison_rl(left_orig, op, right_orig, &left_true, &left_false, &right_true, &right_false);
1444
1445 left_true = rl_truncate_cast(get_type(strip_expr(left)), left_true);
1446 left_false = rl_truncate_cast(get_type(strip_expr(left)), left_false);
1447 right_true = rl_truncate_cast(get_type(strip_expr(right)), right_true);
1448 right_false = rl_truncate_cast(get_type(strip_expr(right)), right_false);
1449
1450 if (!left_true || !left_false) {
1451 struct range_list *tmp_true, *tmp_false;
1452
1453 split_comparison_rl(alloc_whole_rl(type), op, right_orig, &tmp_true, &tmp_false, NULL, NULL);
1454 tmp_true = rl_truncate_cast(get_type(strip_expr(left)), tmp_true);
1455 tmp_false = rl_truncate_cast(get_type(strip_expr(left)), tmp_false);
1456 if (tmp_true && tmp_false)
1457 __save_imaginary_state(left, tmp_true, tmp_false);
1458 }
1459
1460 if (!right_true || !right_false) {
1461 struct range_list *tmp_true, *tmp_false;
1462
1463 split_comparison_rl(alloc_whole_rl(type), op, right_orig, NULL, NULL, &tmp_true, &tmp_false);
1464 tmp_true = rl_truncate_cast(get_type(strip_expr(right)), tmp_true);
1465 tmp_false = rl_truncate_cast(get_type(strip_expr(right)), tmp_false);
1466 if (tmp_true && tmp_false)
1467 __save_imaginary_state(right, tmp_true, tmp_false);
1468 }
1469
1470 left_true_state = alloc_estate_rl(left_true);
1471 left_false_state = alloc_estate_rl(left_false);
1472 right_true_state = alloc_estate_rl(right_true);
1473 right_false_state = alloc_estate_rl(right_false);
1474
1475 switch (op) {
1476 case '<':
1477 case SPECIAL_UNSIGNED_LT:
1478 case SPECIAL_UNSIGNED_LTE:
1479 case SPECIAL_LTE:
1480 if (get_implied_value(right, &dummy) && !in_macro(left, right))
1481 estate_set_hard_max(left_true_state);
1482 if (get_implied_value(left, &dummy) && !in_macro(left, right))
1483 estate_set_hard_max(right_false_state);
1484 break;
1485 case '>':
1486 case SPECIAL_UNSIGNED_GT:
1487 case SPECIAL_UNSIGNED_GTE:
1488 case SPECIAL_GTE:
1489 if (get_implied_value(left, &dummy) && !in_macro(left, right))
1490 estate_set_hard_max(right_true_state);
1491 if (get_implied_value(right, &dummy) && !in_macro(left, right))
1492 estate_set_hard_max(left_false_state);
1493 break;
1494 }
1495
1496 switch (op) {
1497 case '<':
1498 case SPECIAL_UNSIGNED_LT:
1499 case SPECIAL_UNSIGNED_LTE:
1500 case SPECIAL_LTE:
1501 if (get_hard_max(right, &hard_max)) {
1502 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1503 hard_max.value--;
1504 estate_set_fuzzy_max(left_true_state, hard_max);
1505 }
1506 if (get_implied_value(right, &hard_max)) {
1507 if (op == SPECIAL_UNSIGNED_LTE ||
1508 op == SPECIAL_LTE)
1509 hard_max.value++;
1510 estate_set_fuzzy_max(left_false_state, hard_max);
1511 }
1512 if (get_hard_max(left, &hard_max)) {
1513 if (op == SPECIAL_UNSIGNED_LTE ||
1514 op == SPECIAL_LTE)
1515 hard_max.value--;
1516 estate_set_fuzzy_max(right_false_state, hard_max);
1517 }
1518 if (get_implied_value(left, &hard_max)) {
1519 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1520 hard_max.value++;
1521 estate_set_fuzzy_max(right_true_state, hard_max);
1522 }
1523 break;
1524 case '>':
1525 case SPECIAL_UNSIGNED_GT:
1526 case SPECIAL_UNSIGNED_GTE:
1527 case SPECIAL_GTE:
1528 if (get_hard_max(left, &hard_max)) {
1529 if (op == '>' || op == SPECIAL_UNSIGNED_GT)
1530 hard_max.value--;
1531 estate_set_fuzzy_max(right_true_state, hard_max);
1532 }
1533 if (get_implied_value(left, &hard_max)) {
1534 if (op == SPECIAL_UNSIGNED_GTE ||
1535 op == SPECIAL_GTE)
1536 hard_max.value++;
1537 estate_set_fuzzy_max(right_false_state, hard_max);
1538 }
1539 if (get_hard_max(right, &hard_max)) {
1540 if (op == SPECIAL_UNSIGNED_LTE ||
1541 op == SPECIAL_LTE)
1542 hard_max.value--;
1543 estate_set_fuzzy_max(left_false_state, hard_max);
1544 }
1545 if (get_implied_value(right, &hard_max)) {
1546 if (op == '>' ||
1547 op == SPECIAL_UNSIGNED_GT)
1548 hard_max.value++;
1549 estate_set_fuzzy_max(left_true_state, hard_max);
1550 }
1551 break;
1552 case SPECIAL_EQUAL:
1553 if (get_hard_max(left, &hard_max))
1554 estate_set_fuzzy_max(right_true_state, hard_max);
1555 if (get_hard_max(right, &hard_max))
1556 estate_set_fuzzy_max(left_true_state, hard_max);
1557 break;
1558 }
1559
1560 if (get_hard_max(left, &hard_max)) {
1561 estate_set_hard_max(left_true_state);
1562 estate_set_hard_max(left_false_state);
1563 }
1564 if (get_hard_max(right, &hard_max)) {
1565 estate_set_hard_max(right_true_state);
1566 estate_set_hard_max(right_false_state);
1567 }
1568
1569 if (left_postop == SPECIAL_INCREMENT) {
1570 left_true_state = increment_state(left_true_state);
1571 left_false_state = increment_state(left_false_state);
1572 }
1573 if (left_postop == SPECIAL_DECREMENT) {
1574 left_true_state = decrement_state(left_true_state);
1575 left_false_state = decrement_state(left_false_state);
1576 }
1577 if (right_postop == SPECIAL_INCREMENT) {
1578 right_true_state = increment_state(right_true_state);
1579 right_false_state = increment_state(right_false_state);
1580 }
1581 if (right_postop == SPECIAL_DECREMENT) {
1582 right_true_state = decrement_state(right_true_state);
1583 right_false_state = decrement_state(right_false_state);
1584 }
1585
1586 if (estate_rl(left_true_state) && estates_equiv(left_true_state, left_false_state)) {
1587 left_true_state = NULL;
1588 left_false_state = NULL;
1589 }
1590
1591 if (estate_rl(right_true_state) && estates_equiv(right_true_state, right_false_state)) {
1592 right_true_state = NULL;
1593 right_false_state = NULL;
1594 }
1595
1596 /* Don't introduce new states for known true/false conditions */
1597 if (rl_equiv(left_orig, estate_rl(left_true_state)))
1598 left_true_state = NULL;
1599 if (rl_equiv(left_orig, estate_rl(left_false_state)))
1600 left_false_state = NULL;
1601 if (rl_equiv(right_orig, estate_rl(right_true_state)))
1602 right_true_state = NULL;
1603 if (rl_equiv(right_orig, estate_rl(right_false_state)))
1604 right_false_state = NULL;
1605
1606 set_extra_expr_true_false(left, left_true_state, left_false_state);
1607 set_extra_expr_true_false(right, right_true_state, right_false_state);
1608 }
1609
1610 static int is_simple_math(struct expression *expr)
1611 {
1612 if (!expr)
1613 return 0;
1614 if (expr->type != EXPR_BINOP)
1615 return 0;
1616 switch (expr->op) {
1617 case '+':
1618 case '-':
1619 case '*':
1620 return 1;
1621 }
1622 return 0;
1623 }
1624
1625 static void move_known_values(struct expression **left_p, struct expression **right_p)
1626 {
1627 struct expression *left = *left_p;
1628 struct expression *right = *right_p;
1629 sval_t sval, dummy;
1630
1631 if (get_implied_value(left, &sval)) {
1632 if (!is_simple_math(right))
1633 return;
1634 if (get_implied_value(right, &dummy))
1635 return;
1636 if (right->op == '*') {
1637 sval_t divisor;
1638
1639 if (!get_value(right->right, &divisor))
1640 return;
1641 if (divisor.value == 0)
1642 return;
1643 *left_p = binop_expression(left, invert_op(right->op), right->right);
1644 *right_p = right->left;
1645 return;
1646 }
1647 if (right->op == '+' && get_value(right->left, &sval)) {
1648 *left_p = binop_expression(left, invert_op(right->op), right->left);
1649 *right_p = right->right;
1650 return;
1651 }
1652 if (get_value(right->right, &sval)) {
1653 *left_p = binop_expression(left, invert_op(right->op), right->right);
1654 *right_p = right->left;
1655 return;
1656 }
1657 return;
1658 }
1659 if (get_implied_value(right, &sval)) {
1660 if (!is_simple_math(left))
1661 return;
1662 if (get_implied_value(left, &dummy))
1663 return;
1664 if (left->op == '*') {
1665 sval_t divisor;
1666
1667 if (!get_value(left->right, &divisor))
1668 return;
1669 if (divisor.value == 0)
1670 return;
1671 *right_p = binop_expression(right, invert_op(left->op), left->right);
1672 *left_p = left->left;
1673 return;
1674 }
1675 if (left->op == '+' && get_value(left->left, &sval)) {
1676 *right_p = binop_expression(right, invert_op(left->op), left->left);
1677 *left_p = left->right;
1678 return;
1679 }
1680
1681 if (get_value(left->right, &sval)) {
1682 *right_p = binop_expression(right, invert_op(left->op), left->right);
1683 *left_p = left->left;
1684 return;
1685 }
1686 return;
1687 }
1688 }
1689
1690 /*
1691 * The reason for do_simple_algebra() is to solve things like:
1692 * if (foo > 66 || foo + bar > 64) {
1693 * "foo" is not really a known variable so it won't be handled by
1694 * move_known_variables() but it's a super common idiom.
1695 *
1696 */
1697 static int do_simple_algebra(struct expression **left_p, struct expression **right_p)
1698 {
1699 struct expression *left = *left_p;
1700 struct expression *right = *right_p;
1701 struct range_list *rl;
1702 sval_t tmp;
1703
1704 if (left->type != EXPR_BINOP || left->op != '+')
1705 return 0;
1706 if (can_integer_overflow(get_type(left), left))
1707 return 0;
1708 if (!get_implied_value(right, &tmp))
1709 return 0;
1710
1711 if (!get_implied_value(left->left, &tmp) &&
1712 get_implied_rl(left->left, &rl) &&
1713 !is_whole_rl(rl)) {
1714 *right_p = binop_expression(right, '-', left->left);
1715 *left_p = left->right;
1716 return 1;
1717 }
1718 if (!get_implied_value(left->right, &tmp) &&
1719 get_implied_rl(left->right, &rl) &&
1720 !is_whole_rl(rl)) {
1721 *right_p = binop_expression(right, '-', left->right);
1722 *left_p = left->left;
1723 return 1;
1724 }
1725
1726 return 0;
1727 }
1728
1729 static int match_func_comparison(struct expression *expr)
1730 {
1731 struct expression *left = strip_expr(expr->left);
1732 struct expression *right = strip_expr(expr->right);
1733
1734 if (left->type == EXPR_CALL || right->type == EXPR_CALL) {
1735 function_comparison(left, expr->op, right);
1736 return 1;
1737 }
1738
1739 return 0;
1740 }
1741
1742 /* Handle conditions like "if (foo + bar < foo) {" */
1743 static int handle_integer_overflow_test(struct expression *expr)
1744 {
1745 struct expression *left, *right;
1746 struct symbol *type;
1747 sval_t left_min, right_min, min, max;
1748
1749 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1750 return 0;
1751
1752 left = strip_parens(expr->left);
1753 right = strip_parens(expr->right);
1754
1755 if (left->op != '+')
1756 return 0;
1757
1758 type = get_type(expr);
1759 if (!type)
1760 return 0;
1761 if (type_positive_bits(type) == 32) {
1762 max.type = &uint_ctype;
1763 max.uvalue = (unsigned int)-1;
1764 } else if (type_positive_bits(type) == 64) {
1765 max.type = &ulong_ctype;
1766 max.value = (unsigned long long)-1;
1767 } else {
1768 return 0;
1769 }
1770
1771 if (!expr_equiv(left->left, right) && !expr_equiv(left->right, right))
1772 return 0;
1773
1774 get_absolute_min(left->left, &left_min);
1775 get_absolute_min(left->right, &right_min);
1776 min = sval_binop(left_min, '+', right_min);
1777
1778 set_extra_chunk_true_false(left, NULL, alloc_estate_range(min, max));
1779 return 1;
1780 }
1781
1782 static void match_comparison(struct expression *expr)
1783 {
1784 struct expression *left_orig = strip_parens(expr->left);
1785 struct expression *right_orig = strip_parens(expr->right);
1786 struct expression *left, *right, *tmp;
1787 struct expression *prev;
1788 struct symbol *type;
1789 int redo, count;
1790
1791 if (match_func_comparison(expr))
1792 return;
1793
1794 type = get_type(expr);
1795 if (!type)
1796 type = &llong_ctype;
1797
1798 if (handle_integer_overflow_test(expr))
1799 return;
1800
1801 left = left_orig;
1802 right = right_orig;
1803 move_known_values(&left, &right);
1804 handle_comparison(type, left, expr->op, right);
1805
1806 left = left_orig;
1807 right = right_orig;
1808 if (do_simple_algebra(&left, &right))
1809 handle_comparison(type, left, expr->op, right);
1810
1811 prev = get_assigned_expr(left_orig);
1812 if (is_simple_math(prev) && has_variable(prev, left_orig) == 0) {
1813 left = prev;
1814 right = right_orig;
1815 move_known_values(&left, &right);
1816 handle_comparison(type, left, expr->op, right);
1817 }
1818
1819 prev = get_assigned_expr(right_orig);
1820 if (is_simple_math(prev) && has_variable(prev, right_orig) == 0) {
1821 left = left_orig;
1822 right = prev;
1823 move_known_values(&left, &right);
1824 handle_comparison(type, left, expr->op, right);
1825 }
1826
1827 redo = 0;
1828 left = left_orig;
1829 right = right_orig;
1830 if (get_last_expr_from_expression_stmt(left_orig)) {
1831 left = get_last_expr_from_expression_stmt(left_orig);
1832 redo = 1;
1833 }
1834 if (get_last_expr_from_expression_stmt(right_orig)) {
1835 right = get_last_expr_from_expression_stmt(right_orig);
1836 redo = 1;
1837 }
1838
1839 if (!redo)
1840 return;
1841
1842 count = 0;
1843 while ((tmp = get_assigned_expr(left))) {
1844 if (count++ > 3)
1845 break;
1846 left = strip_expr(tmp);
1847 }
1848 count = 0;
1849 while ((tmp = get_assigned_expr(right))) {
1850 if (count++ > 3)
1851 break;
1852 right = strip_expr(tmp);
1853 }
1854
1855 handle_comparison(type, left, expr->op, right);
1856 }
1857
1858 static sval_t get_high_mask(sval_t known)
1859 {
1860 sval_t ret;
1861 int i;
1862
1863 ret = known;
1864 ret.value = 0;
1865
1866 for (i = type_bits(known.type) - 1; i >= 0; i--) {
1867 if (known.uvalue & (1ULL << i))
1868 ret.uvalue |= (1ULL << i);
1869 else
1870 return ret;
1871
1872 }
1873 return ret;
1874 }
1875
1876 static void handle_AND_op(struct expression *var, sval_t known)
1877 {
1878 struct range_list *orig_rl;
1879 struct range_list *true_rl = NULL;
1880 struct range_list *false_rl = NULL;
1881 int bit;
1882 sval_t low_mask = known;
1883 sval_t high_mask;
1884 sval_t max;
1885
1886 get_absolute_rl(var, &orig_rl);
1887
1888 if (known.value > 0) {
1889 bit = ffsll(known.value) - 1;
1890 low_mask.uvalue = (1ULL << bit) - 1;
1891 true_rl = remove_range(orig_rl, sval_type_val(known.type, 0), low_mask);
1892 }
1893 high_mask = get_high_mask(known);
1894 if (high_mask.value) {
1895 bit = ffsll(high_mask.value) - 1;
1896 low_mask.uvalue = (1ULL << bit) - 1;
1897
1898 false_rl = orig_rl;
1899 if (sval_is_negative(rl_min(orig_rl)))
1900 false_rl = remove_range(false_rl, sval_type_min(known.type), sval_type_val(known.type, -1));
1901 false_rl = remove_range(false_rl, low_mask, sval_type_max(known.type));
1902 if (type_signed(high_mask.type) && type_unsigned(rl_type(false_rl))) {
1903 false_rl = remove_range(false_rl,
1904 sval_type_val(rl_type(false_rl), sval_type_max(known.type).uvalue),
1905 sval_type_val(rl_type(false_rl), -1));
1906 }
1907 } else if (known.value == 1 &&
1908 get_hard_max(var, &max) &&
1909 sval_cmp(max, rl_max(orig_rl)) == 0 &&
1910 max.value & 1) {
1911 false_rl = remove_range(orig_rl, max, max);
1912 }
1913 set_extra_expr_true_false(var,
1914 true_rl ? alloc_estate_rl(true_rl) : NULL,
1915 false_rl ? alloc_estate_rl(false_rl) : NULL);
1916 }
1917
1918 static void handle_AND_condition(struct expression *expr)
1919 {
1920 sval_t known;
1921
1922 if (get_implied_value(expr->left, &known))
1923 handle_AND_op(expr->right, known);
1924 else if (get_implied_value(expr->right, &known))
1925 handle_AND_op(expr->left, known);
1926 }
1927
1928 static void handle_MOD_condition(struct expression *expr)
1929 {
1930 struct range_list *orig_rl;
1931 struct range_list *true_rl;
1932 struct range_list *false_rl = NULL;
1933 sval_t right;
1934 sval_t zero = {
1935 .value = 0,
1936 };
1937
1938 if (!get_implied_value(expr->right, &right) || right.value == 0)
1939 return;
1940 get_absolute_rl(expr->left, &orig_rl);
1941
1942 zero.type = rl_type(orig_rl);
1943
1944 /* We're basically dorking around the min and max here */
1945 true_rl = remove_range(orig_rl, zero, zero);
1946 if (!sval_is_max(rl_max(true_rl)) &&
1947 !(rl_max(true_rl).value % right.value))
1948 true_rl = remove_range(true_rl, rl_max(true_rl), rl_max(true_rl));
1949
1950 if (rl_equiv(true_rl, orig_rl))
1951 true_rl = NULL;
1952
1953 if (sval_is_positive(rl_min(orig_rl)) &&
1954 (rl_max(orig_rl).value - rl_min(orig_rl).value) / right.value < 5) {
1955 sval_t add;
1956 int i;
1957
1958 add = rl_min(orig_rl);
1959 add.value += right.value - (add.value % right.value);
1960 add.value -= right.value;
1961
1962 for (i = 0; i < 5; i++) {
1963 add.value += right.value;
1964 if (add.value > rl_max(orig_rl).value)
1965 break;
1966 add_range(&false_rl, add, add);
1967 }
1968 } else {
1969 if (rl_min(orig_rl).uvalue != 0 &&
1970 rl_min(orig_rl).uvalue < right.uvalue) {
1971 sval_t chop = right;
1972 chop.value--;
1973 false_rl = remove_range(orig_rl, zero, chop);
1974 }
1975
1976 if (!sval_is_max(rl_max(orig_rl)) &&
1977 (rl_max(orig_rl).value % right.value)) {
1978 sval_t chop = rl_max(orig_rl);
1979 chop.value -= chop.value % right.value;
1980 chop.value++;
1981 if (!false_rl)
1982 false_rl = clone_rl(orig_rl);
1983 false_rl = remove_range(false_rl, chop, rl_max(orig_rl));
1984 }
1985 }
1986
1987 set_extra_expr_true_false(expr->left,
1988 true_rl ? alloc_estate_rl(true_rl) : NULL,
1989 false_rl ? alloc_estate_rl(false_rl) : NULL);
1990 }
1991
1992 /* this is actually hooked from smatch_implied.c... it's hacky, yes */
1993 void __extra_match_condition(struct expression *expr)
1994 {
1995 expr = strip_expr(expr);
1996 switch (expr->type) {
1997 case EXPR_CALL:
1998 function_comparison(expr, SPECIAL_NOTEQUAL, zero_expr());
1999 return;
2000 case EXPR_PREOP:
2001 case EXPR_SYMBOL:
2002 case EXPR_DEREF:
2003 handle_comparison(get_type(expr), expr, SPECIAL_NOTEQUAL, zero_expr());
2004 return;
2005 case EXPR_COMPARE:
2006 match_comparison(expr);
2007 return;
2008 case EXPR_ASSIGNMENT:
2009 __extra_match_condition(expr->left);
2010 return;
2011 case EXPR_BINOP:
2012 if (expr->op == '&')
2013 handle_AND_condition(expr);
2014 if (expr->op == '%')
2015 handle_MOD_condition(expr);
2016 return;
2017 }
2018 }
2019
2020 static void assume_indexes_are_valid(struct expression *expr)
2021 {
2022 struct expression *array_expr;
2023 int array_size;
2024 struct expression *offset;
2025 struct symbol *offset_type;
2026 struct range_list *rl_before;
2027 struct range_list *rl_after;
2028 struct range_list *filter = NULL;
2029 sval_t size;
2030
2031 expr = strip_expr(expr);
2032 if (!is_array(expr))
2033 return;
2034
2035 offset = get_array_offset(expr);
2036 offset_type = get_type(offset);
2037 if (offset_type && type_signed(offset_type)) {
2038 filter = alloc_rl(sval_type_min(offset_type),
2039 sval_type_val(offset_type, -1));
2040 }
2041
2042 array_expr = get_array_base(expr);
2043 array_size = get_real_array_size(array_expr);
2044 if (array_size > 1) {
2045 size = sval_type_val(offset_type, array_size);
2046 add_range(&filter, size, sval_type_max(offset_type));
2047 }
2048
2049 if (!filter)
2050 return;
2051 get_absolute_rl(offset, &rl_before);
2052 rl_after = rl_filter(rl_before, filter);
2053 if (rl_equiv(rl_before, rl_after))
2054 return;
2055 set_extra_expr_nomod(offset, alloc_estate_rl(rl_after));
2056 }
2057
2058 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
2059 int implied_not_equal(struct expression *expr, long long val)
2060 {
2061 return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
2062 }
2063
2064 int implied_not_equal_name_sym(char *name, struct symbol *sym, long long val)
2065 {
2066 struct smatch_state *estate;
2067
2068 estate = get_state(SMATCH_EXTRA, name, sym);
2069 if (!estate)
2070 return 0;
2071 if (!rl_has_sval(estate_rl(estate), sval_type_val(estate_type(estate), 0)))
2072 return 1;
2073 return 0;
2074 }
2075
2076 int parent_is_null_var_sym(const char *name, struct symbol *sym)
2077 {
2078 char buf[256];
2079 char *start;
2080 char *end;
2081 struct smatch_state *state;
2082
2083 strncpy(buf, name, sizeof(buf) - 1);
2084 buf[sizeof(buf) - 1] = '\0';
2085
2086 start = &buf[0];
2087 while (*start == '*') {
2088 start++;
2089 state = get_state(SMATCH_EXTRA, start, sym);
2090 if (!state)
2091 continue;
2092 if (!estate_rl(state))
2093 return 1;
2094 if (estate_min(state).value == 0 &&
2095 estate_max(state).value == 0)
2096 return 1;
2097 }
2098
2099 start = &buf[0];
2100 while (*start == '&')
2101 start++;
2102
2103 while ((end = strrchr(start, '-'))) {
2104 *end = '\0';
2105 state = __get_state(SMATCH_EXTRA, start, sym);
2106 if (!state)
2107 continue;
2108 if (estate_min(state).value == 0 &&
2109 estate_max(state).value == 0)
2110 return 1;
2111 }
2112 return 0;
2113 }
2114
2115 int parent_is_null(struct expression *expr)
2116 {
2117 struct symbol *sym;
2118 char *var;
2119 int ret = 0;
2120
2121 expr = strip_expr(expr);
2122 var = expr_to_var_sym(expr, &sym);
2123 if (!var || !sym)
2124 goto free;
2125 ret = parent_is_null_var_sym(var, sym);
2126 free:
2127 free_string(var);
2128 return ret;
2129 }
2130
2131 static int param_used_callback(void *found, int argc, char **argv, char **azColName)
2132 {
2133 *(int *)found = 1;
2134 return 0;
2135 }
2136
2137 static int is_kzalloc_info(struct sm_state *sm)
2138 {
2139 sval_t sval;
2140
2141 /*
2142 * kzalloc() information is treated as special because so there is just
2143 * a lot of stuff initialized to zero and it makes building the database
2144 * take hours and hours.
2145 *
2146 * In theory, we should just remove this line and not pass any unused
2147 * information, but I'm not sure enough that this code works so I want
2148 * to hold off on that for now.
2149 */
2150 if (!estate_get_single_value(sm->state, &sval))
2151 return 0;
2152 if (sval.value != 0)
2153 return 0;
2154 return 1;
2155 }
2156
2157 static int is_really_long(struct sm_state *sm)
2158 {
2159 const char *p;
2160 int cnt = 0;
2161
2162 p = sm->name;
2163 while ((p = strstr(p, "->"))) {
2164 p += 2;
2165 cnt++;
2166 }
2167
2168 if (cnt < 3 ||
2169 strlen(sm->name) < 40)
2170 return 0;
2171 return 1;
2172 }
2173
2174 static int filter_unused_param_value_info(struct expression *call, int param, char *printed_name, struct sm_state *sm)
2175 {
2176 int found = 0;
2177
2178 /* for function pointers assume everything is used */
2179 if (call->fn->type != EXPR_SYMBOL)
2180 return 0;
2181
2182 /*
2183 * This is to handle __builtin_mul_overflow(). In an ideal world we
2184 * would only need this for invalid code.
2185 *
2186 */
2187 if (!call->fn->symbol)
2188 return 0;
2189
2190 if (!is_kzalloc_info(sm) && !is_really_long(sm))
2191 return 0;
2192
2193 run_sql(&param_used_callback, &found,
2194 "select * from return_implies where %s and type = %d and parameter = %d and key = '%s';",
2195 get_static_filter(call->fn->symbol), PARAM_USED, param, printed_name);
2196 if (found)
2197 return 0;
2198
2199 /* If the database is not built yet, then assume everything is used */
2200 run_sql(&param_used_callback, &found,
2201 "select * from return_implies where %s and type = %d;",
2202 get_static_filter(call->fn->symbol), PARAM_USED);
2203 if (!found)
2204 return 0;
2205
2206 return 1;
2207 }
2208
2209 struct range_list *intersect_with_real_abs_var_sym(const char *name, struct symbol *sym, struct range_list *start)
2210 {
2211 struct smatch_state *state;
2212
2213 /*
2214 * Here is the difference between implied value and real absolute, say
2215 * you have:
2216 *
2217 * int a = (u8)x;
2218 *
2219 * Then you know that a is 0-255. That's real absolute. But you don't
2220 * know for sure that it actually goes up to 255. So it's not implied.
2221 * Implied indicates a degree of certainty.
2222 *
2223 * But then say you cap "a" at 8. That means you know it goes up to
2224 * 8. So now the implied value is s32min-8. But you can combine it
2225 * with the real absolute to say that actually it's 0-8.
2226 *
2227 * We are combining it here. But now that I think about it, this is
2228 * probably not the ideal place to combine it because it should proably
2229 * be done earlier. Oh well, this is an improvement on what was there
2230 * before so I'm going to commit this code.
2231 *
2232 */
2233
2234 state = get_real_absolute_state_var_sym(name, sym);
2235 if (!state || !estate_rl(state))
2236 return start;
2237
2238 return rl_intersection(estate_rl(state), start);
2239 }
2240
2241 struct range_list *intersect_with_real_abs_expr(struct expression *expr, struct range_list *start)
2242 {
2243 struct smatch_state *state;
2244 struct range_list *abs_rl;
2245
2246 state = get_real_absolute_state(expr);
2247 if (!state || !estate_rl(state))
2248 return start;
2249
2250 abs_rl = cast_rl(rl_type(start), estate_rl(state));
2251 return rl_intersection(abs_rl, start);
2252 }
2253
2254 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
2255 {
2256 struct range_list *rl;
2257
2258 if (estate_is_whole(sm->state))
2259 return;
2260 if (filter_unused_param_value_info(call, param, printed_name, sm))
2261 return;
2262 rl = estate_rl(sm->state);
2263 rl = intersect_with_real_abs_var_sym(sm->name, sm->sym, rl);
2264 sql_insert_caller_info(call, PARAM_VALUE, param, printed_name, show_rl(rl));
2265 if (estate_has_hard_max(sm->state))
2266 sql_insert_caller_info(call, HARD_MAX, param, printed_name,
2267 sval_to_str(estate_max(sm->state)));
2268 if (estate_has_fuzzy_max(sm->state))
2269 sql_insert_caller_info(call, FUZZY_MAX, param, printed_name,
2270 sval_to_str(estate_get_fuzzy_max(sm->state)));
2271 }
2272
2273 static void returned_struct_members(int return_id, char *return_ranges, struct expression *expr)
2274 {
2275 struct symbol *returned_sym;
2276 char *returned_name;
2277 struct sm_state *sm;
2278 char *compare_str;
2279 char name_buf[256];
2280 char val_buf[256];
2281 int len;
2282
2283 // FIXME handle *$
2284
2285 if (!is_pointer(expr))
2286 return;
2287
2288 returned_name = expr_to_var_sym(expr, &returned_sym);
2289 if (!returned_name || !returned_sym)
2290 goto free;
2291 len = strlen(returned_name);
2292
2293 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
2294 if (!estate_rl(sm->state))
2295 continue;
2296 if (returned_sym != sm->sym)
2297 continue;
2298 if (strncmp(returned_name, sm->name, len) != 0)
2299 continue;
2300 if (sm->name[len] != '-')
2301 continue;
2302
2303 snprintf(name_buf, sizeof(name_buf), "$%s", sm->name + len);
2304
2305 compare_str = name_sym_to_param_comparison(sm->name, sm->sym);
2306 if (!compare_str && estate_is_whole(sm->state))
2307 continue;
2308 snprintf(val_buf, sizeof(val_buf), "%s%s", sm->state->name, compare_str ?: "");
2309
2310 sql_insert_return_states(return_id, return_ranges, PARAM_VALUE,
2311 -1, name_buf, val_buf);
2312 } END_FOR_EACH_SM(sm);
2313
2314 free:
2315 free_string(returned_name);
2316 }
2317
2318 static void db_limited_before(void)
2319 {
2320 unmatched_stree = clone_stree(__get_cur_stree());
2321 }
2322
2323 static void db_limited_after(void)
2324 {
2325 free_stree(&unmatched_stree);
2326 }
2327
2328 static int rl_fits_in_type(struct range_list *rl, struct symbol *type)
2329 {
2330 if (type_bits(rl_type(rl)) <= type_bits(type))
2331 return 1;
2332 if (sval_cmp(rl_max(rl), sval_type_max(type)) > 0)
2333 return 0;
2334 if (sval_is_negative(rl_min(rl)) &&
2335 sval_cmp(rl_min(rl), sval_type_min(type)) < 0)
2336 return 0;
2337 return 1;
2338 }
2339
2340 static int basically_the_same(struct range_list *orig, struct range_list *new)
2341 {
2342 if (rl_equiv(orig, new))
2343 return 1;
2344
2345 /*
2346 * The whole range is essentially the same as 0,4096-27777777777 so
2347 * don't overwrite the implications just to store that.
2348 *
2349 */
2350 if (rl_type(orig)->type == SYM_PTR &&
2351 is_whole_rl(orig) &&
2352 rl_min(new).value == 0 &&
2353 rl_max(new).value == valid_ptr_max)
2354 return 1;
2355 return 0;
2356 }
2357
2358 static void db_param_limit_binops(struct expression *arg, char *key, struct range_list *rl)
2359 {
2360 struct range_list *left_rl;
2361 sval_t zero = { .type = rl_type(rl), };
2362 sval_t sval;
2363
2364 if (arg->op != '*')
2365 return;
2366 if (!get_implied_value(arg->right, &sval))
2367 return;
2368 if (can_integer_overflow(get_type(arg), arg))
2369 return;
2370
2371 left_rl = rl_binop(rl, '/', alloc_rl(sval, sval));
2372 if (!rl_has_sval(rl, zero))
2373 left_rl = remove_range(left_rl, zero, zero);
2374
2375 set_extra_expr_nomod(arg->left, alloc_estate_rl(left_rl));
2376 }
2377
2378 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value, enum info_type op)
2379 {
2380 struct expression *arg;
2381 char *name;
2382 struct symbol *sym;
2383 struct var_sym_list *vsl = NULL;
2384 struct sm_state *sm;
2385 struct symbol *compare_type, *var_type;
2386 struct range_list *rl;
2387 struct range_list *limit;
2388 struct range_list *new;
2389 char *other_name;
2390 struct symbol *other_sym;
2391
2392 while (expr->type == EXPR_ASSIGNMENT)
2393 expr = strip_expr(expr->right);
2394 if (expr->type != EXPR_CALL)
2395 return;
2396
2397 arg = get_argument_from_call_expr(expr->args, param);
2398 if (!arg)
2399 return;
2400
2401 name = get_chunk_from_key(arg, key, &sym, &vsl);
2402 if (!name)
2403 return;
2404 if (op != PARAM_LIMIT && !sym)
2405 goto free;
2406
2407 if (strcmp(key, "$") == 0)
2408 compare_type = get_arg_type(expr->fn, param);
2409 else
2410 compare_type = get_member_type_from_key(arg, key);
2411
2412 sm = get_sm_state(SMATCH_EXTRA, name, sym);
2413 if (sm)
2414 rl = estate_rl(sm->state);
2415 else
2416 rl = alloc_whole_rl(compare_type);
2417
2418 if (op == PARAM_LIMIT && !rl_fits_in_type(rl, compare_type))
2419 goto free;
2420
2421 call_results_to_rl(expr, compare_type, value, &limit);
2422 new = rl_intersection(rl, limit);
2423
2424 var_type = get_member_type_from_key(arg, key);
2425 new = cast_rl(var_type, new);
2426
2427 /* We want to preserve the implications here */
2428 if (sm && basically_the_same(estate_rl(sm->state), new))
2429 goto free;
2430 other_name = map_long_to_short_name_sym(name, sym, &other_sym);
2431
2432 if (op == PARAM_LIMIT)
2433 set_extra_nomod_vsl(name, sym, vsl, NULL, alloc_estate_rl(new));
2434 else
2435 set_extra_mod(name, sym, NULL, alloc_estate_rl(new));
2436
2437 if (other_name && other_sym) {
2438 if (op == PARAM_LIMIT)
2439 set_extra_nomod_vsl(other_name, other_sym, vsl, NULL, alloc_estate_rl(new));
2440 else
2441 set_extra_mod(other_name, other_sym, NULL, alloc_estate_rl(new));
2442 }
2443
2444 if (op == PARAM_LIMIT && arg->type == EXPR_BINOP)
2445 db_param_limit_binops(arg, key, new);
2446 free:
2447 free_string(name);
2448 }
2449
2450 static void db_param_limit(struct expression *expr, int param, char *key, char *value)
2451 {
2452 db_param_limit_filter(expr, param, key, value, PARAM_LIMIT);
2453 }
2454
2455 static void db_param_filter(struct expression *expr, int param, char *key, char *value)
2456 {
2457 db_param_limit_filter(expr, param, key, value, PARAM_FILTER);
2458 }
2459
2460 static void db_param_add_set(struct expression *expr, int param, char *key, char *value, enum info_type op)
2461 {
2462 struct expression *arg;
2463 char *name, *tmp_name;
2464 struct symbol *sym, *tmp_sym;
2465 struct symbol *param_type, *arg_type;
2466 struct smatch_state *state;
2467 struct range_list *new = NULL;
2468 struct range_list *added = NULL;
2469
2470 while (expr->type == EXPR_ASSIGNMENT)
2471 expr = strip_expr(expr->right);
2472 if (expr->type != EXPR_CALL)
2473 return;
2474
2475 arg = get_argument_from_call_expr(expr->args, param);
2476 if (!arg)
2477 return;
2478
2479 arg_type = get_arg_type_from_key(expr->fn, param, arg, key);
2480 param_type = get_member_type_from_key(arg, key);
2481 name = get_variable_from_key(arg, key, &sym);
2482 if (!name || !sym)
2483 goto free;
2484
2485 state = get_state(SMATCH_EXTRA, name, sym);
2486 if (state)
2487 new = estate_rl(state);
2488
2489 call_results_to_rl(expr, arg_type, value, &added);
2490 added = cast_rl(param_type, added);
2491 if (op == PARAM_SET)
2492 new = added;
2493 else
2494 new = rl_union(new, added);
2495
2496 tmp_name = map_long_to_short_name_sym_nostack(name, sym, &tmp_sym);
2497 if (tmp_name && tmp_sym) {
2498 free_string(name);
2499 name = tmp_name;
2500 sym = tmp_sym;
2501 }
2502 set_extra_mod(name, sym, NULL, alloc_estate_rl(new));
2503 free:
2504 free_string(name);
2505 }
2506
2507 static void db_param_add(struct expression *expr, int param, char *key, char *value)
2508 {
2509 in_param_set = true;
2510 db_param_add_set(expr, param, key, value, PARAM_ADD);
2511 in_param_set = false;
2512 }
2513
2514 static void db_param_set(struct expression *expr, int param, char *key, char *value)
2515 {
2516 in_param_set = true;
2517 db_param_add_set(expr, param, key, value, PARAM_SET);
2518 in_param_set = false;
2519 }
2520
2521 static void match_lost_param(struct expression *call, int param)
2522 {
2523 struct expression *arg;
2524
2525 if (is_const_param(call->fn, param))
2526 return;
2527
2528 arg = get_argument_from_call_expr(call->args, param);
2529 if (!arg)
2530 return;
2531
2532 arg = strip_expr(arg);
2533 if (arg->type == EXPR_PREOP && arg->op == '&')
2534 set_extra_expr_mod(arg->unop, alloc_estate_whole(get_type(arg->unop)));
2535 else
2536 ; /* if pointer then set struct members, maybe?*/
2537 }
2538
2539 static void db_param_value(struct expression *expr, int param, char *key, char *value)
2540 {
2541 struct expression *call;
2542 char *name;
2543 struct symbol *sym;
2544 struct symbol *type;
2545 struct range_list *rl = NULL;
2546
2547 if (param != -1)
2548 return;
2549
2550 call = expr;
2551 while (call->type == EXPR_ASSIGNMENT)
2552 call = strip_expr(call->right);
2553 if (call->type != EXPR_CALL)
2554 return;
2555
2556 type = get_member_type_from_key(expr->left, key);
2557 name = get_variable_from_key(expr->left, key, &sym);
2558 if (!name || !sym)
2559 goto free;
2560
2561 call_results_to_rl(call, type, value, &rl);
2562
2563 set_extra_mod(name, sym, NULL, alloc_estate_rl(rl));
2564 free:
2565 free_string(name);
2566 }
2567
2568 static void match_call_info(struct expression *expr)
2569 {
2570 struct smatch_state *state;
2571 struct range_list *rl = NULL;
2572 struct expression *arg;
2573 struct symbol *type;
2574 int i = 0;
2575
2576 FOR_EACH_PTR(expr->args, arg) {
2577 type = get_arg_type(expr->fn, i);
2578
2579 get_absolute_rl(arg, &rl);
2580 rl = cast_rl(type, rl);
2581
2582 if (!is_whole_rl(rl)) {
2583 rl = intersect_with_real_abs_expr(arg, rl);
2584 sql_insert_caller_info(expr, PARAM_VALUE, i, "$", show_rl(rl));
2585 }
2586 state = get_state_expr(SMATCH_EXTRA, arg);
2587 if (estate_has_hard_max(state)) {
2588 sql_insert_caller_info(expr, HARD_MAX, i, "$",
2589 sval_to_str(estate_max(state)));
2590 }
2591 if (estate_has_fuzzy_max(state)) {
2592 sql_insert_caller_info(expr, FUZZY_MAX, i, "$",
2593 sval_to_str(estate_get_fuzzy_max(state)));
2594 }
2595 i++;
2596 } END_FOR_EACH_PTR(arg);
2597 }
2598
2599 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
2600 {
2601 struct range_list *rl = NULL;
2602 struct smatch_state *state;
2603 struct symbol *type;
2604 char fullname[256];
2605 sval_t dummy;
2606
2607 if (strcmp(key, "*$") == 0)
2608 snprintf(fullname, sizeof(fullname), "*%s", name);
2609 else if (strncmp(key, "$", 1) == 0)
2610 snprintf(fullname, 256, "%s%s", name, key + 1);
2611 else
2612 return;
2613
2614 type = get_member_type_from_key(symbol_expression(sym), key);
2615 str_to_rl(type, value, &rl);
2616 state = alloc_estate_rl(rl);
2617 if (estate_get_single_value(state, &dummy))
2618 estate_set_hard_max(state);
2619 set_state(SMATCH_EXTRA, fullname, sym, state);
2620 }
2621
2622 static void set_param_fuzzy_max(const char *name, struct symbol *sym, char *key, char *value)
2623 {
2624 struct range_list *rl = NULL;
2625 struct smatch_state *state;
2626 struct symbol *type;
2627 char fullname[256];
2628 sval_t max;
2629
2630 if (strcmp(key, "*$") == 0)
2631 snprintf(fullname, sizeof(fullname), "*%s", name);
2632 else if (strncmp(key, "$", 1) == 0)
2633 snprintf(fullname, 256, "%s%s", name, key + 1);
2634 else
2635 return;
2636
2637 state = get_state(SMATCH_EXTRA, fullname, sym);
2638 if (!state)
2639 return;
2640 type = estate_type(state);
2641 str_to_rl(type, value, &rl);
2642 if (!rl_to_sval(rl, &max))
2643 return;
2644 estate_set_fuzzy_max(state, max);
2645 }
2646
2647 static void set_param_hard_max(const char *name, struct symbol *sym, char *key, char *value)
2648 {
2649 struct smatch_state *state;
2650 char fullname[256];
2651
2652 if (strcmp(key, "*$") == 0)
2653 snprintf(fullname, sizeof(fullname), "*%s", name);
2654 else if (strncmp(key, "$", 1) == 0)
2655 snprintf(fullname, 256, "%s%s", name, key + 1);
2656 else
2657 return;
2658
2659 state = get_state(SMATCH_EXTRA, fullname, sym);
2660 if (!state)
2661 return;
2662 estate_set_hard_max(state);
2663 }
2664
2665 struct sm_state *get_extra_sm_state(struct expression *expr)
2666 {
2667 char *name;
2668 struct symbol *sym;
2669 struct sm_state *ret = NULL;
2670
2671 name = expr_to_known_chunk_sym(expr, &sym);
2672 if (!name)
2673 goto free;
2674
2675 ret = get_sm_state(SMATCH_EXTRA, name, sym);
2676 free:
2677 free_string(name);
2678 return ret;
2679 }
2680
2681 struct smatch_state *get_extra_state(struct expression *expr)
2682 {
2683 struct sm_state *sm;
2684
2685 sm = get_extra_sm_state(expr);
2686 if (!sm)
2687 return NULL;
2688 return sm->state;
2689 }
2690
2691 void register_smatch_extra(int id)
2692 {
2693 my_id = id;
2694
2695 add_merge_hook(my_id, &merge_estates);
2696 add_unmatched_state_hook(my_id, &unmatched_state);
2697 select_caller_info_hook(set_param_value, PARAM_VALUE);
2698 select_caller_info_hook(set_param_fuzzy_max, FUZZY_MAX);
2699 select_caller_info_hook(set_param_hard_max, HARD_MAX);
2700 select_return_states_before(&db_limited_before);
2701 select_return_states_hook(PARAM_LIMIT, &db_param_limit);
2702 select_return_states_hook(PARAM_FILTER, &db_param_filter);
2703 select_return_states_hook(PARAM_ADD, &db_param_add);
2704 select_return_states_hook(PARAM_SET, &db_param_set);
2705 add_lost_param_hook(&match_lost_param);
2706 select_return_states_hook(PARAM_VALUE, &db_param_value);
2707 select_return_states_after(&db_limited_after);
2708 }
2709
2710 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr)
2711 {
2712 struct var_sym_list *links;
2713 struct var_sym *tmp;
2714 struct smatch_state *state;
2715
2716 links = sm->state->data;
2717
2718 FOR_EACH_PTR(links, tmp) {
2719 if (sm->sym == tmp->sym &&
2720 strcmp(sm->name, tmp->var) == 0)
2721 continue;
2722 state = get_state(SMATCH_EXTRA, tmp->var, tmp->sym);
2723 if (!state)
2724 continue;
2725 set_state(SMATCH_EXTRA, tmp->var, tmp->sym, alloc_estate_whole(estate_type(state)));
2726 } END_FOR_EACH_PTR(tmp);
2727 set_state(link_id, sm->name, sm->sym, &undefined);
2728 }
2729
2730 void register_smatch_extra_links(int id)
2731 {
2732 link_id = id;
2733 }
2734
2735 void register_smatch_extra_late(int id)
2736 {
2737 add_merge_hook(link_id, &merge_link_states);
2738 add_modification_hook(link_id, &match_link_modify);
2739 add_hook(&match_dereferences, DEREF_HOOK);
2740 add_hook(&match_pointer_as_array, OP_HOOK);
2741 select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
2742 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
2743 add_hook(&match_assign, ASSIGNMENT_HOOK);
2744 add_hook(&match_assign, GLOBAL_ASSIGNMENT_HOOK);
2745 add_hook(&unop_expr, OP_HOOK);
2746 add_hook(&asm_expr, ASM_HOOK);
2747
2748 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2749 add_member_info_callback(my_id, struct_member_callback);
2750 add_split_return_callback(&returned_struct_members);
2751
2752 // add_hook(&assume_indexes_are_valid, OP_HOOK);
2753 }
Static analysis for C