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shift_to_zero: be even more conservative (avoid false positives)
[smatch.git] / smatch_comparison.c
blob8267555e14eb10618aa746f25b2741d964aa5aea
1 /*
2 * Copyright (C) 2012 Oracle.
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 * The point here is to store the relationships between two variables.
20 * Ie: y > x.
21 * To do that we create a state with the two variables in alphabetical order:
22 * ->name = "x vs y" and the state would be "<". On the false path the state
23 * would be ">=".
24 *
25 * Part of the trick of it is that if x or y is modified then we need to reset
26 * the state. We need to keep a list of all the states which depend on x and
27 * all the states which depend on y. The link_id code handles this.
28 *
29 */
30
31 #include "smatch.h"
32 #include "smatch_extra.h"
33 #include "smatch_slist.h"
34
35 int comparison_id;
36 static int link_id;
37 static int inc_dec_id;
38 static int inc_dec_link_id;
39
40 static void add_comparison(struct expression *left, int comparison, struct expression *right);
41
42 /* for handling for loops */
43 STATE(start);
44 STATE(incremented);
45
46 ALLOCATOR(compare_data, "compare data");
47
48 static struct symbol *vsl_to_sym(struct var_sym_list *vsl)
49 {
50 struct var_sym *vs;
51
52 if (!vsl)
53 return NULL;
54 if (ptr_list_size((struct ptr_list *)vsl) != 1)
55 return NULL;
56 vs = first_ptr_list((struct ptr_list *)vsl);
57 return vs->sym;
58 }
59
60 static const char *show_comparison(int comparison)
61 {
62 if (comparison == IMPOSSIBLE_COMPARISON)
63 return "impossible";
64 if (comparison == UNKNOWN_COMPARISON)
65 return "unknown";
66 return show_special(comparison);
67 }
68
69 struct smatch_state *alloc_compare_state(
70 struct expression *left,
71 const char *left_var, struct var_sym_list *left_vsl,
72 int comparison,
73 struct expression *right,
74 const char *right_var, struct var_sym_list *right_vsl)
75 {
76 struct smatch_state *state;
77 struct compare_data *data;
78
79 state = __alloc_smatch_state(0);
80 state->name = alloc_sname(show_comparison(comparison));
81 data = __alloc_compare_data(0);
82 data->left = left;
83 data->left_var = alloc_sname(left_var);
84 data->left_vsl = clone_var_sym_list(left_vsl);
85 data->comparison = comparison;
86 data->right = right;
87 data->right_var = alloc_sname(right_var);
88 data->right_vsl = clone_var_sym_list(right_vsl);
89 state->data = data;
90 return state;
91 }
92
93 int state_to_comparison(struct smatch_state *state)
94 {
95 if (!state || !state->data)
96 return UNKNOWN_COMPARISON;
97 return ((struct compare_data *)state->data)->comparison;
98 }
99
100 /*
101 * flip_comparison() reverses the op left and right. So "x >= y" becomes "y <= x".
102 */
103 int flip_comparison(int op)
104 {
105 switch (op) {
106 case UNKNOWN_COMPARISON:
107 return UNKNOWN_COMPARISON;
108 case '<':
109 return '>';
110 case SPECIAL_UNSIGNED_LT:
111 return SPECIAL_UNSIGNED_GT;
112 case SPECIAL_LTE:
113 return SPECIAL_GTE;
114 case SPECIAL_UNSIGNED_LTE:
115 return SPECIAL_UNSIGNED_GTE;
116 case SPECIAL_EQUAL:
117 return SPECIAL_EQUAL;
118 case SPECIAL_NOTEQUAL:
119 return SPECIAL_NOTEQUAL;
120 case SPECIAL_GTE:
121 return SPECIAL_LTE;
122 case SPECIAL_UNSIGNED_GTE:
123 return SPECIAL_UNSIGNED_LTE;
124 case '>':
125 return '<';
126 case SPECIAL_UNSIGNED_GT:
127 return SPECIAL_UNSIGNED_LT;
128 case IMPOSSIBLE_COMPARISON:
129 return UNKNOWN_COMPARISON;
130 default:
131 sm_perror("unhandled comparison %d", op);
132 return op;
133 }
134 }
135
136 int negate_comparison(int op)
137 {
138 switch (op) {
139 case UNKNOWN_COMPARISON:
140 return UNKNOWN_COMPARISON;
141 case '<':
142 return SPECIAL_GTE;
143 case SPECIAL_UNSIGNED_LT:
144 return SPECIAL_UNSIGNED_GTE;
145 case SPECIAL_LTE:
146 return '>';
147 case SPECIAL_UNSIGNED_LTE:
148 return SPECIAL_UNSIGNED_GT;
149 case SPECIAL_EQUAL:
150 return SPECIAL_NOTEQUAL;
151 case SPECIAL_NOTEQUAL:
152 return SPECIAL_EQUAL;
153 case SPECIAL_GTE:
154 return '<';
155 case SPECIAL_UNSIGNED_GTE:
156 return SPECIAL_UNSIGNED_LT;
157 case '>':
158 return SPECIAL_LTE;
159 case SPECIAL_UNSIGNED_GT:
160 return SPECIAL_UNSIGNED_LTE;
161 case IMPOSSIBLE_COMPARISON:
162 return UNKNOWN_COMPARISON;
163 default:
164 sm_perror("unhandled comparison %d", op);
165 return op;
166 }
167 }
168
169 static int rl_comparison(struct range_list *left_rl, struct range_list *right_rl)
170 {
171 sval_t left_min, left_max, right_min, right_max;
172 struct symbol *type = &int_ctype;
173
174 if (!left_rl || !right_rl)
175 return UNKNOWN_COMPARISON;
176
177 if (type_positive_bits(rl_type(left_rl)) > type_positive_bits(type))
178 type = rl_type(left_rl);
179 if (type_positive_bits(rl_type(right_rl)) > type_positive_bits(type))
180 type = rl_type(right_rl);
181
182 left_rl = cast_rl(type, left_rl);
183 right_rl = cast_rl(type, right_rl);
184
185 left_min = rl_min(left_rl);
186 left_max = rl_max(left_rl);
187 right_min = rl_min(right_rl);
188 right_max = rl_max(right_rl);
189
190 if (left_min.value == left_max.value &&
191 right_min.value == right_max.value &&
192 left_min.value == right_min.value)
193 return SPECIAL_EQUAL;
194
195 if (sval_cmp(left_max, right_min) < 0)
196 return '<';
197 if (sval_cmp(left_max, right_min) == 0)
198 return SPECIAL_LTE;
199 if (sval_cmp(left_min, right_max) > 0)
200 return '>';
201 if (sval_cmp(left_min, right_max) == 0)
202 return SPECIAL_GTE;
203
204 return UNKNOWN_COMPARISON;
205 }
206
207 static int comparison_from_extra(struct expression *a, struct expression *b)
208 {
209 struct range_list *left, *right;
210
211 if (!get_implied_rl(a, &left))
212 return UNKNOWN_COMPARISON;
213 if (!get_implied_rl(b, &right))
214 return UNKNOWN_COMPARISON;
215
216 return rl_comparison(left, right);
217 }
218
219 static struct range_list *get_orig_rl(struct var_sym_list *vsl)
220 {
221 struct symbol *sym;
222 struct smatch_state *state;
223
224 if (!vsl)
225 return NULL;
226 sym = vsl_to_sym(vsl);
227 if (!sym || !sym->ident)
228 return NULL;
229 state = get_orig_estate(sym->ident->name, sym);
230 return estate_rl(state);
231 }
232
233 static struct smatch_state *unmatched_comparison(struct sm_state *sm)
234 {
235 struct compare_data *data = sm->state->data;
236 struct range_list *left_rl, *right_rl;
237 int op = UNKNOWN_COMPARISON;
238
239 if (!data)
240 return &undefined;
241
242 if (is_impossible_path()) {
243 op = IMPOSSIBLE_COMPARISON;
244 goto alloc;
245 }
246
247 if (strstr(data->left_var, " orig"))
248 left_rl = get_orig_rl(data->left_vsl);
249 else if (!get_implied_rl_var_sym(data->left_var, vsl_to_sym(data->left_vsl), &left_rl))
250 goto alloc;
251
252 if (strstr(data->right_var, " orig"))
253 right_rl = get_orig_rl(data->right_vsl);
254 else if (!get_implied_rl_var_sym(data->right_var, vsl_to_sym(data->right_vsl), &right_rl))
255 goto alloc;
256
257 op = rl_comparison(left_rl, right_rl);
258
259 alloc:
260 return alloc_compare_state(data->left, data->left_var, data->left_vsl,
261 op,
262 data->right, data->right_var, data->right_vsl);
263 }
264
265 /* remove_unsigned_from_comparison() is obviously a hack. */
266 int remove_unsigned_from_comparison(int op)
267 {
268 switch (op) {
269 case SPECIAL_UNSIGNED_LT:
270 return '<';
271 case SPECIAL_UNSIGNED_LTE:
272 return SPECIAL_LTE;
273 case SPECIAL_UNSIGNED_GTE:
274 return SPECIAL_GTE;
275 case SPECIAL_UNSIGNED_GT:
276 return '>';
277 default:
278 return op;
279 }
280 }
281
282 /*
283 * This is for when you merge states "a < b" and "a == b", the result is that
284 * we can say for sure, "a <= b" after the merge.
285 */
286 int merge_comparisons(int one, int two)
287 {
288 int LT, EQ, GT;
289
290 if (one == UNKNOWN_COMPARISON || two == UNKNOWN_COMPARISON)
291 return UNKNOWN_COMPARISON;
292
293 if (one == IMPOSSIBLE_COMPARISON)
294 return two;
295 if (two == IMPOSSIBLE_COMPARISON)
296 return one;
297
298 one = remove_unsigned_from_comparison(one);
299 two = remove_unsigned_from_comparison(two);
300
301 if (one == two)
302 return one;
303
304 LT = EQ = GT = 0;
305
306 switch (one) {
307 case '<':
308 LT = 1;
309 break;
310 case SPECIAL_LTE:
311 LT = 1;
312 EQ = 1;
313 break;
314 case SPECIAL_EQUAL:
315 EQ = 1;
316 break;
317 case SPECIAL_GTE:
318 GT = 1;
319 EQ = 1;
320 break;
321 case '>':
322 GT = 1;
323 }
324
325 switch (two) {
326 case '<':
327 LT = 1;
328 break;
329 case SPECIAL_LTE:
330 LT = 1;
331 EQ = 1;
332 break;
333 case SPECIAL_EQUAL:
334 EQ = 1;
335 break;
336 case SPECIAL_GTE:
337 GT = 1;
338 EQ = 1;
339 break;
340 case '>':
341 GT = 1;
342 }
343
344 if (LT && EQ && GT)
345 return UNKNOWN_COMPARISON;
346 if (LT && EQ)
347 return SPECIAL_LTE;
348 if (LT && GT)
349 return SPECIAL_NOTEQUAL;
350 if (LT)
351 return '<';
352 if (EQ && GT)
353 return SPECIAL_GTE;
354 if (GT)
355 return '>';
356 return UNKNOWN_COMPARISON;
357 }
358
359 /*
360 * This is for if you have "a < b" and "b <= c" and you want to see how "a
361 * compares to c". You would call this like get_combined_comparison('<', '<=').
362 * The return comparison would be '<'.
363 */
364 int combine_comparisons(int left_compare, int right_compare)
365 {
366 int LT, EQ, GT;
367
368 left_compare = remove_unsigned_from_comparison(left_compare);
369 right_compare = remove_unsigned_from_comparison(right_compare);
370
371 LT = EQ = GT = 0;
372
373 switch (left_compare) {
374 case '<':
375 LT++;
376 break;
377 case SPECIAL_LTE:
378 LT++;
379 EQ++;
380 break;
381 case SPECIAL_EQUAL:
382 return right_compare;
383 case SPECIAL_GTE:
384 GT++;
385 EQ++;
386 break;
387 case '>':
388 GT++;
389 }
390
391 switch (right_compare) {
392 case '<':
393 LT++;
394 break;
395 case SPECIAL_LTE:
396 LT++;
397 EQ++;
398 break;
399 case SPECIAL_EQUAL:
400 return left_compare;
401 case SPECIAL_GTE:
402 GT++;
403 EQ++;
404 break;
405 case '>':
406 GT++;
407 }
408
409 if (LT == 2) {
410 if (EQ == 2)
411 return SPECIAL_LTE;
412 return '<';
413 }
414
415 if (GT == 2) {
416 if (EQ == 2)
417 return SPECIAL_GTE;
418 return '>';
419 }
420 return UNKNOWN_COMPARISON;
421 }
422
423 /*
424 * This is mostly used when you know from extra state that a <= b but you
425 * know from comparisons that a != b so then if take the intersection then
426 * we know that a < b. The name is taken from the fact that the intersection
427 * of < and <= is <.
428 */
429 int comparison_intersection(int left_compare, int right_compare)
430 {
431 int LT, GT, EQ, NE, total;
432
433 if (left_compare == IMPOSSIBLE_COMPARISON ||
434 right_compare == IMPOSSIBLE_COMPARISON)
435 return IMPOSSIBLE_COMPARISON;
436
437 left_compare = remove_unsigned_from_comparison(left_compare);
438 right_compare = remove_unsigned_from_comparison(right_compare);
439
440 LT = GT = EQ = NE = total = 0;
441
442 /* Only one side is known. */
443 if (!left_compare)
444 return right_compare;
445 if (!right_compare)
446 return left_compare;
447
448 switch (left_compare) {
449 case '<':
450 LT++;
451 total += 1;
452 break;
453 case SPECIAL_LTE:
454 LT++;
455 EQ++;
456 total += 2;
457 break;
458 case SPECIAL_EQUAL:
459 EQ++;
460 total += 1;
461 break;
462 case SPECIAL_NOTEQUAL:
463 NE++;
464 total += 1;
465 break;
466 case SPECIAL_GTE:
467 GT++;
468 EQ++;
469 total += 2;
470 break;
471 case '>':
472 GT++;
473 total += 1;
474 break;
475 default:
476 return UNKNOWN_COMPARISON;
477 }
478
479 switch (right_compare) {
480 case '<':
481 LT++;
482 total += 1;
483 break;
484 case SPECIAL_LTE:
485 LT++;
486 EQ++;
487 total += 2;
488 break;
489 case SPECIAL_EQUAL:
490 EQ++;
491 total += 1;
492 break;
493 case SPECIAL_NOTEQUAL:
494 NE++;
495 total += 1;
496 break;
497 case SPECIAL_GTE:
498 GT++;
499 EQ++;
500 total += 2;
501 break;
502 case '>':
503 GT++;
504 total += 1;
505 break;
506 default:
507 return UNKNOWN_COMPARISON;
508 }
509
510 if (LT == 2) {
511 if (EQ == 2)
512 return SPECIAL_LTE;
513 return '<';
514 }
515
516 if (GT == 2) {
517 if (EQ == 2)
518 return SPECIAL_GTE;
519 return '>';
520 }
521 if (EQ == 2)
522 return SPECIAL_EQUAL;
523 if (total == 2 && EQ && NE)
524 return IMPOSSIBLE_COMPARISON;
525 if (GT && LT)
526 return IMPOSSIBLE_COMPARISON;
527 if (GT && NE)
528 return '>';
529 if (LT && NE)
530 return '<';
531 if (NE == 2)
532 return SPECIAL_NOTEQUAL;
533 if (total == 2 && (LT || GT) && EQ)
534 return IMPOSSIBLE_COMPARISON;
535
536 return UNKNOWN_COMPARISON;
537 }
538
539 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
540 {
541 struct compare_data *data = cur->state->data;
542 int extra, new;
543 static bool in_recurse;
544
545 // FIXME. No data is useless
546 if (!data)
547 return;
548
549 if (in_recurse)
550 return;
551 in_recurse = true;
552 extra = comparison_from_extra(data->left, data->right);
553 in_recurse = false;
554 if (!extra)
555 return;
556 new = comparison_intersection(extra, data->comparison);
557 if (new == data->comparison)
558 return;
559
560 // FIXME: we should always preserve implications
561 set_state(comparison_id, cur->name, NULL,
562 alloc_compare_state(data->left, data->left_var, data->left_vsl,
563 new,
564 data->right, data->right_var, data->right_vsl));
565 }
566
567 struct smatch_state *merge_compare_states(struct smatch_state *s1, struct smatch_state *s2)
568 {
569 struct compare_data *data = s1->data;
570 int op;
571
572 if (!data)
573 return &undefined;
574
575 op = merge_comparisons(state_to_comparison(s1), state_to_comparison(s2));
576 return alloc_compare_state(
577 data->left, data->left_var, data->left_vsl,
578 op,
579 data->right, data->right_var, data->right_vsl);
580 }
581
582 static struct smatch_state *alloc_link_state(struct string_list *links)
583 {
584 struct smatch_state *state;
585 static char buf[256];
586 char *tmp;
587 int i;
588
589 state = __alloc_smatch_state(0);
590
591 i = 0;
592 FOR_EACH_PTR(links, tmp) {
593 if (!i++) {
594 snprintf(buf, sizeof(buf), "%s", tmp);
595 } else {
596 append(buf, ", ", sizeof(buf));
597 append(buf, tmp, sizeof(buf));
598 }
599 } END_FOR_EACH_PTR(tmp);
600
601 state->name = alloc_sname(buf);
602 state->data = links;
603 return state;
604 }
605
606 static void save_start_states(struct statement *stmt)
607 {
608 struct symbol *param;
609 char orig[64];
610 char state_name[128];
611 struct smatch_state *state;
612 struct string_list *links;
613 char *link;
614
615 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
616 struct var_sym_list *left_vsl = NULL;
617 struct var_sym_list *right_vsl = NULL;
618
619 if (!param->ident)
620 continue;
621 snprintf(orig, sizeof(orig), "%s orig", param->ident->name);
622 snprintf(state_name, sizeof(state_name), "%s vs %s", param->ident->name, orig);
623 add_var_sym(&left_vsl, param->ident->name, param);
624 add_var_sym(&right_vsl, orig, param);
625 state = alloc_compare_state(
626 NULL, param->ident->name, left_vsl,
627 SPECIAL_EQUAL,
628 NULL, alloc_sname(orig), right_vsl);
629 set_state(comparison_id, state_name, NULL, state);
630
631 link = alloc_sname(state_name);
632 links = NULL;
633 insert_string(&links, link);
634 state = alloc_link_state(links);
635 set_state(link_id, param->ident->name, param, state);
636 } END_FOR_EACH_PTR(param);
637 }
638
639 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
640 {
641 struct smatch_state *ret;
642 struct string_list *links;
643
644 links = combine_string_lists(s1->data, s2->data);
645 ret = alloc_link_state(links);
646 return ret;
647 }
648
649 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
650 {
651 struct smatch_state *old_state, *new_state;
652 struct string_list *links;
653 char *new;
654
655 old_state = get_state(link_id, var, sym);
656 if (old_state)
657 links = clone_str_list(old_state->data);
658 else
659 links = NULL;
660
661 new = alloc_sname(link);
662 insert_string(&links, new);
663
664 new_state = alloc_link_state(links);
665 set_state(link_id, var, sym, new_state);
666 }
667
668 static void match_inc(struct sm_state *sm, bool preserve)
669 {
670 struct string_list *links;
671 struct smatch_state *state, *new;
672 struct compare_data *data;
673 char *tmp;
674 int flip;
675 int op;
676
677 links = sm->state->data;
678
679 FOR_EACH_PTR(links, tmp) {
680 state = get_state(comparison_id, tmp, NULL);
681 if (!state)
682 continue;
683 data = state->data;
684 if (!data)
685 continue;
686
687 flip = 0;
688 if (strncmp(sm->name, tmp, strlen(sm->name)) != 0 ||
689 tmp[strlen(sm->name)] != ' ')
690 flip = 1;
691
692 op = state_to_comparison(state);
693
694 switch (flip ? flip_comparison(op) : op) {
695 case SPECIAL_EQUAL:
696 case SPECIAL_GTE:
697 case SPECIAL_UNSIGNED_GTE:
698 case '>':
699 case SPECIAL_UNSIGNED_GT:
700 if (preserve)
701 break;
702 new = alloc_compare_state(
703 data->left, data->left_var, data->left_vsl,
704 flip ? '<' : '>',
705 data->right, data->right_var, data->right_vsl);
706 set_state(comparison_id, tmp, NULL, new);
707 break;
708 case '<':
709 case SPECIAL_UNSIGNED_LT:
710 new = alloc_compare_state(
711 data->left, data->left_var, data->left_vsl,
712 flip ? SPECIAL_GTE : SPECIAL_LTE,
713 data->right, data->right_var, data->right_vsl);
714 set_state(comparison_id, tmp, NULL, new);
715 break;
716 default:
717 new = alloc_compare_state(
718 data->left, data->left_var, data->left_vsl,
719 UNKNOWN_COMPARISON,
720 data->right, data->right_var, data->right_vsl);
721 set_state(comparison_id, tmp, NULL, new);
722 }
723 } END_FOR_EACH_PTR(tmp);
724 }
725
726 static void match_dec(struct sm_state *sm, bool preserve)
727 {
728 struct string_list *links;
729 struct smatch_state *state;
730 char *tmp;
731
732 links = sm->state->data;
733
734 FOR_EACH_PTR(links, tmp) {
735 struct compare_data *data;
736 struct smatch_state *new;
737
738 state = get_state(comparison_id, tmp, NULL);
739 if (!state || !state->data)
740 continue;
741
742 data = state->data;
743
744 switch (state_to_comparison(state)) {
745 case SPECIAL_EQUAL:
746 case SPECIAL_LTE:
747 case SPECIAL_UNSIGNED_LTE:
748 case '<':
749 case SPECIAL_UNSIGNED_LT: {
750 if (preserve)
751 break;
752
753 new = alloc_compare_state(
754 data->left, data->left_var, data->left_vsl,
755 '<',
756 data->right, data->right_var, data->right_vsl);
757 set_state(comparison_id, tmp, NULL, new);
758 break;
759 }
760 default:
761 new = alloc_compare_state(
762 data->left, data->left_var, data->left_vsl,
763 UNKNOWN_COMPARISON,
764 data->right, data->right_var, data->right_vsl);
765 set_state(comparison_id, tmp, NULL, new);
766 }
767 } END_FOR_EACH_PTR(tmp);
768 }
769
770 static void reset_sm(struct sm_state *sm)
771 {
772 struct string_list *links;
773 char *tmp;
774
775 links = sm->state->data;
776
777 FOR_EACH_PTR(links, tmp) {
778 struct smatch_state *old, *new;
779
780 old = get_state(comparison_id, tmp, NULL);
781 if (!old || !old->data) {
782 new = &undefined;
783 } else {
784 struct compare_data *data = old->data;
785
786 new = alloc_compare_state(
787 data->left, data->left_var, data->left_vsl,
788 UNKNOWN_COMPARISON,
789 data->right, data->right_var, data->right_vsl);
790 }
791 set_state(comparison_id, tmp, NULL, new);
792 } END_FOR_EACH_PTR(tmp);
793 set_state(link_id, sm->name, sm->sym, &undefined);
794 }
795
796 static bool match_add_sub_assign(struct sm_state *sm, struct expression *expr)
797 {
798 struct range_list *rl;
799 sval_t zero = { .type = &int_ctype };
800
801 if (!expr || expr->type != EXPR_ASSIGNMENT)
802 return false;
803 if (expr->op != SPECIAL_ADD_ASSIGN && expr->op != SPECIAL_SUB_ASSIGN)
804 return false;
805
806 get_absolute_rl(expr->right, &rl);
807 if (sval_is_negative(rl_min(rl))) {
808 reset_sm(sm);
809 return false;
810 }
811
812 if (expr->op == SPECIAL_ADD_ASSIGN)
813 match_inc(sm, rl_has_sval(rl, zero));
814 else
815 match_dec(sm, rl_has_sval(rl, zero));
816 return true;
817 }
818
819 static void match_inc_dec(struct sm_state *sm, struct expression *mod_expr)
820 {
821 /*
822 * if (foo > bar) then ++foo is also > bar.
823 */
824 if (!mod_expr)
825 return;
826 if (match_add_sub_assign(sm, mod_expr))
827 return;
828 if (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP)
829 return;
830
831 if (mod_expr->op == SPECIAL_INCREMENT)
832 match_inc(sm, false);
833 else if (mod_expr->op == SPECIAL_DECREMENT)
834 match_dec(sm, false);
835 }
836
837 static int is_self_assign(struct expression *expr)
838 {
839 if (!expr || expr->type != EXPR_ASSIGNMENT || expr->op != '=')
840 return 0;
841 return expr_equiv(expr->left, expr->right);
842 }
843
844 static void match_modify(struct sm_state *sm, struct expression *mod_expr)
845 {
846 if (mod_expr && is_self_assign(mod_expr))
847 return;
848
849 /* handled by match_inc_dec() */
850 if (mod_expr &&
851 ((mod_expr->type == EXPR_PREOP || mod_expr->type == EXPR_POSTOP) &&
852 (mod_expr->op == SPECIAL_INCREMENT || mod_expr->op == SPECIAL_DECREMENT)))
853 return;
854 if (mod_expr && mod_expr->type == EXPR_ASSIGNMENT &&
855 (mod_expr->op == SPECIAL_ADD_ASSIGN || mod_expr->op == SPECIAL_SUB_ASSIGN))
856 return;
857
858 reset_sm(sm);
859 }
860
861 static void match_preop(struct expression *expr)
862 {
863 struct expression *parent;
864 struct range_list *left, *right;
865 int op;
866
867 /*
868 * This is an important special case. Say you have:
869 *
870 * if (++j == limit)
871 *
872 * Assume that we know the range of limit is higher than the start
873 * value for "j". Then the first thing that we process is the ++j. We
874 * have not comparison states set up so it doesn't get caught by the
875 * modification hook. But it does get caught by smatch_extra which sets
876 * j to unknown then we parse the "j == limit" and sets false to != but
877 * really we want false to be <.
878 *
879 * So what we do is we set j < limit here, then the match_modify catches
880 * it and we do a match_inc_dec().
881 *
882 */
883
884 if (expr->type != EXPR_PREOP ||
885 (expr->op != SPECIAL_INCREMENT && expr->op != SPECIAL_DECREMENT))
886 return;
887
888 parent = expr_get_parent_expr(expr);
889 if (!parent)
890 return;
891 if (parent->type != EXPR_COMPARE || parent->op != SPECIAL_EQUAL)
892 return;
893 if (parent->left != expr)
894 return;
895
896 if (!get_implied_rl(expr->unop, &left) ||
897 !get_implied_rl(parent->right, &right))
898 return;
899
900 op = rl_comparison(left, right);
901 if (op == UNKNOWN_COMPARISON)
902 return;
903
904 add_comparison(expr->unop, op, parent->right);
905 }
906
907 static char *chunk_to_var_sym(struct expression *expr, struct symbol **sym)
908 {
909 expr = strip_expr(expr);
910 if (!expr)
911 return NULL;
912 if (sym)
913 *sym = NULL;
914
915 if (expr->type == EXPR_PREOP &&
916 (expr->op == SPECIAL_INCREMENT ||
917 expr->op == SPECIAL_DECREMENT))
918 expr = strip_expr(expr->unop);
919
920 if (expr->type == EXPR_CALL) {
921 char buf[64];
922
923 snprintf(buf, sizeof(buf), "return %p", expr);
924 return alloc_string(buf);
925 }
926
927 return expr_to_chunk_sym_vsl(expr, sym, NULL);
928 }
929
930 static char *chunk_to_var(struct expression *expr)
931 {
932 return chunk_to_var_sym(expr, NULL);
933 }
934
935 static struct smatch_state *get_state_chunk(int owner, struct expression *expr)
936 {
937 char *name;
938 struct symbol *sym;
939 struct smatch_state *ret;
940
941 name = chunk_to_var_sym(expr, &sym);
942 if (!name)
943 return NULL;
944
945 ret = get_state(owner, name, sym);
946 free_string(name);
947 return ret;
948 }
949
950 static void save_link(struct expression *expr, char *link)
951 {
952 char *var;
953 struct symbol *sym;
954
955 expr = strip_expr(expr);
956 if (expr->type == EXPR_BINOP) {
957 char *chunk;
958
959 chunk = chunk_to_var(expr);
960 if (!chunk)
961 return;
962
963 save_link(expr->left, link);
964 save_link(expr->right, link);
965 save_link_var_sym(chunk, NULL, link);
966 return;
967 }
968
969 var = chunk_to_var_sym(expr, &sym);
970 if (!var)
971 return;
972
973 save_link_var_sym(var, sym, link);
974 free_string(var);
975 }
976
977 static int get_orig_comparison(struct stree *pre_stree, const char *left, const char *right)
978 {
979 struct smatch_state *state;
980 struct compare_data *data;
981 int flip = 0;
982 char state_name[256];
983
984 if (strcmp(left, right) > 0) {
985 const char *tmp = right;
986
987 flip = 1;
988 right = left;
989 left = tmp;
990 }
991
992 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
993 state = get_state_stree(pre_stree, comparison_id, state_name, NULL);
994 if (!state || !state->data)
995 return 0;
996 data = state->data;
997 if (flip)
998 return flip_comparison(data->comparison);
999 return data->comparison;
1000
1001 }
1002
1003 static int have_common_var_sym(struct var_sym_list *left_vsl, struct var_sym_list *right_vsl)
1004 {
1005 struct var_sym *tmp;
1006
1007 FOR_EACH_PTR(left_vsl, tmp) {
1008 if (in_var_sym_list(right_vsl, tmp->var, tmp->sym))
1009 return 1;
1010 } END_FOR_EACH_PTR(tmp);
1011
1012 return 0;
1013 }
1014
1015 /*
1016 * The idea here is that we take a comparison "a < b" and then we look at all
1017 * the things which "b" is compared against "b < c" and we say that that implies
1018 * a relationship "a < c".
1019 *
1020 * The names here about because the comparisons are organized like this
1021 * "a < b < c".
1022 *
1023 */
1024 static void update_tf_links(struct stree *pre_stree,
1025 struct expression *left_expr,
1026 const char *left_var, struct var_sym_list *left_vsl,
1027 int left_comparison, int left_false_comparison,
1028 const char *mid_var, struct var_sym_list *mid_vsl,
1029 struct string_list *links)
1030 {
1031 struct smatch_state *state;
1032 struct smatch_state *true_state, *false_state;
1033 struct compare_data *data;
1034 struct expression *right_expr;
1035 const char *right_var;
1036 struct var_sym_list *right_vsl;
1037 int orig_comparison;
1038 int right_comparison;
1039 int true_comparison;
1040 int false_comparison;
1041 char *tmp;
1042 char state_name[256];
1043 struct var_sym *vs;
1044
1045 FOR_EACH_PTR(links, tmp) {
1046 state = get_state_stree(pre_stree, comparison_id, tmp, NULL);
1047 if (!state || !state->data)
1048 continue;
1049 data = state->data;
1050 right_comparison = data->comparison;
1051 right_expr = data->right;
1052 right_var = data->right_var;
1053 right_vsl = data->right_vsl;
1054 if (strcmp(mid_var, right_var) == 0) {
1055 right_expr = data->left;
1056 right_var = data->left_var;
1057 right_vsl = data->left_vsl;
1058 right_comparison = flip_comparison(right_comparison);
1059 }
1060 if (have_common_var_sym(left_vsl, right_vsl))
1061 continue;
1062
1063 orig_comparison = get_orig_comparison(pre_stree, left_var, right_var);
1064
1065 true_comparison = combine_comparisons(left_comparison, right_comparison);
1066 false_comparison = combine_comparisons(left_false_comparison, right_comparison);
1067
1068 true_comparison = comparison_intersection(orig_comparison, true_comparison);
1069 false_comparison = comparison_intersection(orig_comparison, false_comparison);
1070
1071 if (strcmp(left_var, right_var) > 0) {
1072 struct expression *tmp_expr = left_expr;
1073 const char *tmp_var = left_var;
1074 struct var_sym_list *tmp_vsl = left_vsl;
1075
1076 left_expr = right_expr;
1077 left_var = right_var;
1078 left_vsl = right_vsl;
1079 right_expr = tmp_expr;
1080 right_var = tmp_var;
1081 right_vsl = tmp_vsl;
1082 true_comparison = flip_comparison(true_comparison);
1083 false_comparison = flip_comparison(false_comparison);
1084 }
1085
1086 if (!true_comparison && !false_comparison)
1087 continue;
1088
1089 if (true_comparison)
1090 true_state = alloc_compare_state(
1091 left_expr, left_var, left_vsl,
1092 true_comparison,
1093 right_expr, right_var, right_vsl);
1094 else
1095 true_state = NULL;
1096 if (false_comparison)
1097 false_state = alloc_compare_state(
1098 left_expr, left_var, left_vsl,
1099 false_comparison,
1100 right_expr, right_var, right_vsl);
1101 else
1102 false_state = NULL;
1103
1104 snprintf(state_name, sizeof(state_name), "%s vs %s", left_var, right_var);
1105 set_true_false_states(comparison_id, state_name, NULL, true_state, false_state);
1106 FOR_EACH_PTR(left_vsl, vs) {
1107 save_link_var_sym(vs->var, vs->sym, state_name);
1108 } END_FOR_EACH_PTR(vs);
1109 FOR_EACH_PTR(right_vsl, vs) {
1110 save_link_var_sym(vs->var, vs->sym, state_name);
1111 } END_FOR_EACH_PTR(vs);
1112 if (!vsl_to_sym(left_vsl))
1113 save_link_var_sym(left_var, NULL, state_name);
1114 if (!vsl_to_sym(right_vsl))
1115 save_link_var_sym(right_var, NULL, state_name);
1116 } END_FOR_EACH_PTR(tmp);
1117 }
1118
1119 static void update_tf_data(struct stree *pre_stree,
1120 struct expression *left_expr,
1121 const char *left_name, struct var_sym_list *left_vsl,
1122 struct expression *right_expr,
1123 const char *right_name, struct var_sym_list *right_vsl,
1124 int true_comparison, int false_comparison)
1125 {
1126 struct smatch_state *state;
1127
1128 state = get_state_stree(pre_stree, link_id, right_name, vsl_to_sym(right_vsl));
1129 if (state)
1130 update_tf_links(pre_stree, left_expr, left_name, left_vsl, true_comparison, false_comparison, right_name, right_vsl, state->data);
1131
1132 state = get_state_stree(pre_stree, link_id, left_name, vsl_to_sym(left_vsl));
1133 if (state)
1134 update_tf_links(pre_stree, right_expr, right_name, right_vsl, flip_comparison(true_comparison), flip_comparison(false_comparison), left_name, left_vsl, state->data);
1135 }
1136
1137 static void iter_modify(struct sm_state *sm, struct expression *mod_expr)
1138 {
1139 if (sm->state != &start ||
1140 !mod_expr ||
1141 (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP) ||
1142 mod_expr->op != SPECIAL_INCREMENT)
1143 set_state(inc_dec_id, sm->name, sm->sym, &undefined);
1144 else
1145 set_state(inc_dec_id, sm->name, sm->sym, &incremented);
1146 }
1147
1148 static void handle_for_loops(struct expression *expr, char *state_name, struct smatch_state *false_state)
1149 {
1150 sval_t sval;
1151 char *iter_name, *cap_name;
1152 struct symbol *iter_sym, *cap_sym;
1153 struct compare_data *data;
1154
1155 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1156 return;
1157
1158 if (!__cur_stmt || !__prev_stmt)
1159 return;
1160 if (__cur_stmt->type != STMT_ITERATOR)
1161 return;
1162 if (__cur_stmt->iterator_pre_condition != expr)
1163 return;
1164
1165 /* literals are handled in smatch_extra.c */
1166 if (get_value(expr->right, &sval))
1167 return;
1168
1169 /* First time checking the condition */
1170 if (__prev_stmt == __cur_stmt->iterator_pre_statement) {
1171 if (!get_implied_value(expr->left, &sval) ||
1172 sval.value != 0)
1173 return;
1174
1175 iter_name = expr_to_var_sym(expr->left, &iter_sym);
1176 cap_name = expr_to_var_sym(expr->right, &cap_sym);
1177 if (!iter_name || !cap_name || !iter_sym || !cap_sym) {
1178 free_string(iter_name);
1179 free_string(cap_name);
1180 return;
1181 }
1182
1183 set_state(inc_dec_id, iter_name, iter_sym, &start);
1184 store_link(inc_dec_link_id, cap_name, cap_sym, iter_name, iter_sym);
1185
1186 free_string(iter_name);
1187 free_string(cap_name);
1188 return;
1189 }
1190
1191 /* Second time checking the condtion */
1192 if (__prev_stmt != __cur_stmt->iterator_post_statement)
1193 return;
1194
1195 if (get_state_chunk(inc_dec_id, expr->left) != &incremented)
1196 return;
1197
1198 data = false_state->data;
1199 false_state = alloc_compare_state(
1200 data->left, data->left_var, data->left_vsl,
1201 SPECIAL_EQUAL,
1202 data->right, data->right_var, data->right_vsl);
1203
1204 // FIXME: This doesn't handle links correct so it doesn't set "param orig"
1205 set_true_false_states(comparison_id, state_name, NULL, NULL, false_state);
1206 }
1207
1208 static int is_plus_one(struct expression *expr)
1209 {
1210 sval_t sval;
1211
1212 if (expr->type != EXPR_BINOP || expr->op != '+')
1213 return 0;
1214 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1215 return 0;
1216 return 1;
1217 }
1218
1219 static int is_minus_one(struct expression *expr)
1220 {
1221 sval_t sval;
1222
1223 if (expr->type != EXPR_BINOP || expr->op != '-')
1224 return 0;
1225 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1226 return 0;
1227 return 1;
1228 }
1229
1230 static void move_plus_to_minus_helper(struct expression **left_p, struct expression **right_p)
1231 {
1232 struct expression *left = *left_p;
1233 struct expression *right = *right_p;
1234
1235 /*
1236 * These two are basically equivalent: "foo + 1 != bar" and
1237 * "foo != bar - 1". There are issues with signedness and integer
1238 * overflows. There are also issues with type as well. But let's
1239 * pretend we can ignore all that stuff for now.
1240 *
1241 */
1242
1243 if (!is_plus_one(left))
1244 return;
1245
1246 *left_p = left->left;
1247 *right_p = binop_expression(right, '-', left->right);
1248 }
1249
1250 static void move_plus_to_minus(struct expression **left_p, struct expression **right_p)
1251 {
1252 if (is_plus_one(*left_p) && is_plus_one(*right_p))
1253 return;
1254
1255 move_plus_to_minus_helper(left_p, right_p);
1256 move_plus_to_minus_helper(right_p, left_p);
1257 }
1258
1259 static void handle_comparison(struct expression *left_expr, int op, struct expression *right_expr, char **_state_name, struct smatch_state **_false_state)
1260 {
1261 char *left = NULL;
1262 char *right = NULL;
1263 struct symbol *left_sym, *right_sym;
1264 struct var_sym_list *left_vsl = NULL;
1265 struct var_sym_list *right_vsl = NULL;
1266 int false_op;
1267 int orig_comparison;
1268 struct smatch_state *true_state, *false_state;
1269 static char state_name[256];
1270 struct stree *pre_stree;
1271 sval_t sval;
1272
1273 if (!left_expr || !right_expr)
1274 return;
1275
1276 left_expr = strip_parens(left_expr);
1277 right_expr = strip_parens(right_expr);
1278
1279 while (left_expr->type == EXPR_ASSIGNMENT)
1280 left_expr = strip_parens(left_expr->left);
1281 while (right_expr->type == EXPR_ASSIGNMENT)
1282 right_expr = strip_parens(right_expr->left);
1283
1284 false_op = negate_comparison(op);
1285
1286 move_plus_to_minus(&left_expr, &right_expr);
1287
1288 if (op == SPECIAL_UNSIGNED_LT &&
1289 get_implied_value(left_expr, &sval) &&
1290 sval.value == 0)
1291 false_op = SPECIAL_EQUAL;
1292
1293 if (op == SPECIAL_UNSIGNED_GT &&
1294 get_implied_value(right_expr, &sval) &&
1295 sval.value == 0)
1296 false_op = SPECIAL_EQUAL;
1297
1298 left = chunk_to_var_sym(left_expr, &left_sym);
1299 if (!left)
1300 goto free;
1301 if (left_sym)
1302 add_var_sym(&left_vsl, left, left_sym);
1303 else
1304 left_vsl = expr_to_vsl(left_expr);
1305 right = chunk_to_var_sym(right_expr, &right_sym);
1306 if (!right)
1307 goto free;
1308 if (right_sym)
1309 add_var_sym(&right_vsl, right, right_sym);
1310 else
1311 right_vsl = expr_to_vsl(right_expr);
1312
1313 if (strcmp(left, right) > 0) {
1314 char *tmp_name = left;
1315 struct var_sym_list *tmp_vsl = left_vsl;
1316 struct expression *tmp_expr = left_expr;
1317
1318 left = right;
1319 left_vsl = right_vsl;
1320 left_expr = right_expr;
1321 right = tmp_name;
1322 right_vsl = tmp_vsl;
1323 right_expr = tmp_expr;
1324 op = flip_comparison(op);
1325 false_op = flip_comparison(false_op);
1326 }
1327
1328 orig_comparison = get_comparison(left_expr, right_expr);
1329 op = comparison_intersection(orig_comparison, op);
1330 false_op = comparison_intersection(orig_comparison, false_op);
1331
1332 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
1333 true_state = alloc_compare_state(
1334 left_expr, left, left_vsl,
1335 op,
1336 right_expr, right, right_vsl);
1337 false_state = alloc_compare_state(
1338 left_expr, left, left_vsl,
1339 false_op,
1340 right_expr, right, right_vsl);
1341
1342 pre_stree = clone_stree(__get_cur_stree());
1343 update_tf_data(pre_stree, left_expr, left, left_vsl, right_expr, right, right_vsl, op, false_op);
1344 free_stree(&pre_stree);
1345
1346 set_true_false_states(comparison_id, state_name, NULL, true_state, false_state);
1347 __compare_param_limit_hook(left_expr, right_expr, state_name, true_state, false_state);
1348 save_link(left_expr, state_name);
1349 save_link(right_expr, state_name);
1350
1351 if (_false_state)
1352 *_false_state = false_state;
1353 if (_state_name)
1354 *_state_name = state_name;
1355 free:
1356 free_string(left);
1357 free_string(right);
1358 }
1359
1360 void __comparison_match_condition(struct expression *expr)
1361 {
1362 struct expression *left, *right, *new_left, *new_right, *tmp;
1363 struct smatch_state *false_state = NULL;
1364 char *state_name = NULL;
1365 int redo, count;
1366
1367 if (expr->type != EXPR_COMPARE)
1368 return;
1369
1370 handle_comparison(expr->left, expr->op, expr->right, &state_name, &false_state);
1371 if (false_state && state_name)
1372 handle_for_loops(expr, state_name, false_state);
1373
1374 left = strip_parens(expr->left);
1375 right = strip_parens(expr->right);
1376
1377 if (left->type == EXPR_BINOP && left->op == '+') {
1378 new_left = left->left;
1379 new_right = binop_expression(right, '-', left->right);
1380 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1381
1382 new_left = left->right;
1383 new_right = binop_expression(right, '-', left->left);
1384 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1385 }
1386
1387 redo = 0;
1388 left = strip_parens(expr->left);
1389 right = strip_parens(expr->right);
1390 if (get_last_expr_from_expression_stmt(expr->left)) {
1391 left = get_last_expr_from_expression_stmt(expr->left);
1392 redo = 1;
1393 }
1394 if (get_last_expr_from_expression_stmt(expr->right)) {
1395 right = get_last_expr_from_expression_stmt(expr->right);
1396 redo = 1;
1397 }
1398
1399 if (!redo)
1400 return;
1401
1402 count = 0;
1403 while ((tmp = get_assigned_expr(left))) {
1404 if (count++ > 3)
1405 break;
1406 left = strip_expr(tmp);
1407 }
1408 count = 0;
1409 while ((tmp = get_assigned_expr(right))) {
1410 if (count++ > 3)
1411 break;
1412 right = strip_expr(tmp);
1413 }
1414
1415 handle_comparison(left, expr->op, right, NULL, NULL);
1416 }
1417
1418 static void add_comparison_var_sym(
1419 struct expression *left_expr,
1420 const char *left_name, struct var_sym_list *left_vsl,
1421 int comparison,
1422 struct expression *right_expr,
1423 const char *right_name, struct var_sym_list *right_vsl)
1424 {
1425 struct smatch_state *state;
1426 struct var_sym *vs;
1427 char state_name[256];
1428
1429 if (strcmp(left_name, right_name) > 0) {
1430 struct expression *tmp_expr = left_expr;
1431 const char *tmp_name = left_name;
1432 struct var_sym_list *tmp_vsl = left_vsl;
1433
1434 left_expr = right_expr;
1435 left_name = right_name;
1436 left_vsl = right_vsl;
1437 right_expr = tmp_expr;
1438 right_name = tmp_name;
1439 right_vsl = tmp_vsl;
1440 comparison = flip_comparison(comparison);
1441 }
1442 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1443 state = alloc_compare_state(
1444 left_expr, left_name, left_vsl,
1445 comparison,
1446 right_expr, right_name, right_vsl);
1447
1448 set_state(comparison_id, state_name, NULL, state);
1449
1450 FOR_EACH_PTR(left_vsl, vs) {
1451 save_link_var_sym(vs->var, vs->sym, state_name);
1452 } END_FOR_EACH_PTR(vs);
1453 FOR_EACH_PTR(right_vsl, vs) {
1454 save_link_var_sym(vs->var, vs->sym, state_name);
1455 } END_FOR_EACH_PTR(vs);
1456 }
1457
1458 static void add_comparison(struct expression *left, int comparison, struct expression *right)
1459 {
1460 char *left_name = NULL;
1461 char *right_name = NULL;
1462 struct symbol *left_sym, *right_sym;
1463 struct var_sym_list *left_vsl, *right_vsl;
1464 struct smatch_state *state;
1465 char state_name[256];
1466
1467 left_name = chunk_to_var_sym(left, &left_sym);
1468 if (!left_name)
1469 goto free;
1470 left_vsl = expr_to_vsl(left);
1471 right_name = chunk_to_var_sym(right, &right_sym);
1472 if (!right_name)
1473 goto free;
1474 right_vsl = expr_to_vsl(right);
1475
1476 if (strcmp(left_name, right_name) > 0) {
1477 struct expression *tmp_expr = left;
1478 struct symbol *tmp_sym = left_sym;
1479 char *tmp_name = left_name;
1480 struct var_sym_list *tmp_vsl = left_vsl;
1481
1482 left = right;
1483 left_name = right_name;
1484 left_sym = right_sym;
1485 left_vsl = right_vsl;
1486 right = tmp_expr;
1487 right_name = tmp_name;
1488 right_sym = tmp_sym;
1489 right_vsl = tmp_vsl;
1490 comparison = flip_comparison(comparison);
1491 }
1492 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1493 state = alloc_compare_state(
1494 left, left_name, left_vsl,
1495 comparison,
1496 right, right_name, right_vsl);
1497
1498 set_state(comparison_id, state_name, NULL, state);
1499 save_link(left, state_name);
1500 save_link(right, state_name);
1501
1502 free:
1503 free_string(left_name);
1504 free_string(right_name);
1505 }
1506
1507 static void match_assign_add(struct expression *expr)
1508 {
1509 struct expression *right;
1510 struct expression *r_left, *r_right;
1511 sval_t left_tmp, right_tmp;
1512
1513 right = strip_expr(expr->right);
1514 r_left = strip_expr(right->left);
1515 r_right = strip_expr(right->right);
1516
1517 get_absolute_min(r_left, &left_tmp);
1518 get_absolute_min(r_right, &right_tmp);
1519
1520 if (left_tmp.value > 0)
1521 add_comparison(expr->left, '>', r_right);
1522 else if (left_tmp.value == 0)
1523 add_comparison(expr->left, SPECIAL_GTE, r_right);
1524
1525 if (right_tmp.value > 0)
1526 add_comparison(expr->left, '>', r_left);
1527 else if (right_tmp.value == 0)
1528 add_comparison(expr->left, SPECIAL_GTE, r_left);
1529 }
1530
1531 static void match_assign_sub(struct expression *expr)
1532 {
1533 struct expression *right;
1534 struct expression *r_left, *r_right;
1535 int comparison;
1536 sval_t min;
1537
1538 right = strip_expr(expr->right);
1539 r_left = strip_expr(right->left);
1540 r_right = strip_expr(right->right);
1541
1542 if (get_absolute_min(r_right, &min) && sval_is_negative(min))
1543 return;
1544
1545 comparison = get_comparison(r_left, r_right);
1546
1547 switch (comparison) {
1548 case '>':
1549 case SPECIAL_GTE:
1550 if (implied_not_equal(r_right, 0))
1551 add_comparison(expr->left, '>', r_left);
1552 else
1553 add_comparison(expr->left, SPECIAL_GTE, r_left);
1554 return;
1555 }
1556 }
1557
1558 static void match_assign_divide(struct expression *expr)
1559 {
1560 struct expression *right;
1561 struct expression *r_left, *r_right;
1562 sval_t min;
1563
1564 right = strip_expr(expr->right);
1565 r_left = strip_expr(right->left);
1566 r_right = strip_expr(right->right);
1567 if (!get_implied_min(r_right, &min) || min.value <= 1)
1568 return;
1569
1570 add_comparison(expr->left, '<', r_left);
1571 }
1572
1573 static void match_binop_assign(struct expression *expr)
1574 {
1575 struct expression *right;
1576
1577 right = strip_expr(expr->right);
1578 if (right->op == '+')
1579 match_assign_add(expr);
1580 if (right->op == '-')
1581 match_assign_sub(expr);
1582 if (right->op == '/')
1583 match_assign_divide(expr);
1584 }
1585
1586 static void copy_comparisons(struct expression *left, struct expression *right)
1587 {
1588 struct string_list *links;
1589 struct smatch_state *state;
1590 struct compare_data *data;
1591 struct symbol *left_sym, *right_sym;
1592 char *left_var = NULL;
1593 char *right_var = NULL;
1594 struct var_sym_list *left_vsl;
1595 struct expression *expr;
1596 const char *var;
1597 struct var_sym_list *vsl;
1598 int comparison;
1599 char *tmp;
1600
1601 left_var = chunk_to_var_sym(left, &left_sym);
1602 if (!left_var)
1603 goto done;
1604 left_vsl = expr_to_vsl(left);
1605 right_var = chunk_to_var_sym(right, &right_sym);
1606 if (!right_var)
1607 goto done;
1608
1609 state = get_state(link_id, right_var, right_sym);
1610 if (!state)
1611 return;
1612 links = state->data;
1613
1614 FOR_EACH_PTR(links, tmp) {
1615 state = get_state(comparison_id, tmp, NULL);
1616 if (!state || !state->data)
1617 continue;
1618 data = state->data;
1619 comparison = data->comparison;
1620 expr = data->right;
1621 var = data->right_var;
1622 vsl = data->right_vsl;
1623 if (strcmp(var, right_var) == 0) {
1624 expr = data->left;
1625 var = data->left_var;
1626 vsl = data->left_vsl;
1627 comparison = flip_comparison(comparison);
1628 }
1629 /* n = copy_from_user(dest, src, n); leads to n <= n which is nonsense */
1630 if (strcmp(left_var, var) == 0)
1631 continue;
1632 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1633 } END_FOR_EACH_PTR(tmp);
1634
1635 done:
1636 free_string(right_var);
1637 }
1638
1639 static void match_assign(struct expression *expr)
1640 {
1641 struct expression *right;
1642
1643 if (expr->op != '=')
1644 return;
1645 if (__in_fake_assign || outside_of_function())
1646 return;
1647
1648 if (is_struct(expr->left))
1649 return;
1650
1651 if (is_self_assign(expr))
1652 return;
1653
1654 copy_comparisons(expr->left, expr->right);
1655 add_comparison(expr->left, SPECIAL_EQUAL, expr->right);
1656
1657 right = strip_expr(expr->right);
1658 if (right->type == EXPR_BINOP)
1659 match_binop_assign(expr);
1660 }
1661
1662 int get_comparison_strings(const char *one, const char *two)
1663 {
1664 char buf[256];
1665 struct smatch_state *state;
1666 int invert = 0;
1667 int ret = 0;
1668
1669 if (!one || !two)
1670 return UNKNOWN_COMPARISON;
1671
1672 if (strcmp(one, two) == 0)
1673 return SPECIAL_EQUAL;
1674
1675 if (strcmp(one, two) > 0) {
1676 const char *tmp = one;
1677
1678 one = two;
1679 two = tmp;
1680 invert = 1;
1681 }
1682
1683 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1684 state = get_state(comparison_id, buf, NULL);
1685 if (state)
1686 ret = state_to_comparison(state);
1687
1688 if (invert)
1689 ret = flip_comparison(ret);
1690
1691 return ret;
1692 }
1693
1694 static int get_comparison_helper(struct expression *a, struct expression *b, bool use_extra)
1695 {
1696 char *one = NULL;
1697 char *two = NULL;
1698 int ret = UNKNOWN_COMPARISON;
1699 int extra = UNKNOWN_COMPARISON;
1700
1701 if (a == UNKNOWN_COMPARISON ||
1702 b == UNKNOWN_COMPARISON)
1703 return UNKNOWN_COMPARISON;
1704
1705 a = strip_parens(a);
1706 b = strip_parens(b);
1707
1708 move_plus_to_minus(&a, &b);
1709
1710 one = chunk_to_var(a);
1711 if (!one)
1712 goto free;
1713 two = chunk_to_var(b);
1714 if (!two)
1715 goto free;
1716
1717 ret = get_comparison_strings(one, two);
1718 if (ret)
1719 goto free;
1720
1721 if (is_plus_one(a) || is_minus_one(a)) {
1722 free_string(one);
1723 one = chunk_to_var(a->left);
1724 ret = get_comparison_strings(one, two);
1725 } else if (is_plus_one(b) || is_minus_one(b)) {
1726 free_string(two);
1727 two = chunk_to_var(b->left);
1728 ret = get_comparison_strings(one, two);
1729 }
1730
1731 if (ret == UNKNOWN_COMPARISON)
1732 goto free;
1733
1734 if ((is_plus_one(a) || is_minus_one(b)) && ret == '<')
1735 ret = SPECIAL_LTE;
1736 else if ((is_minus_one(a) || is_plus_one(b)) && ret == '>')
1737 ret = SPECIAL_GTE;
1738 else
1739 ret = UNKNOWN_COMPARISON;
1740
1741 free:
1742 free_string(one);
1743 free_string(two);
1744
1745 extra = comparison_from_extra(a, b);
1746 return comparison_intersection(ret, extra);
1747 }
1748
1749 int get_comparison(struct expression *a, struct expression *b)
1750 {
1751 return get_comparison_helper(a, b, true);
1752 }
1753
1754 int get_comparison_no_extra(struct expression *a, struct expression *b)
1755 {
1756 return get_comparison_helper(a, b, false);
1757 }
1758
1759 int possible_comparison(struct expression *a, int comparison, struct expression *b)
1760 {
1761 char *one = NULL;
1762 char *two = NULL;
1763 int ret = 0;
1764 char buf[256];
1765 struct sm_state *sm;
1766 int saved;
1767
1768 one = chunk_to_var(a);
1769 if (!one)
1770 goto free;
1771 two = chunk_to_var(b);
1772 if (!two)
1773 goto free;
1774
1775
1776 if (strcmp(one, two) == 0 && comparison == SPECIAL_EQUAL) {
1777 ret = 1;
1778 goto free;
1779 }
1780
1781 if (strcmp(one, two) > 0) {
1782 char *tmp = one;
1783
1784 one = two;
1785 two = tmp;
1786 comparison = flip_comparison(comparison);
1787 }
1788
1789 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1790 sm = get_sm_state(comparison_id, buf, NULL);
1791 if (!sm)
1792 goto free;
1793
1794 FOR_EACH_PTR(sm->possible, sm) {
1795 if (!sm->state->data)
1796 continue;
1797 saved = ((struct compare_data *)sm->state->data)->comparison;
1798 if (saved == comparison)
1799 ret = 1;
1800 if (comparison == SPECIAL_EQUAL &&
1801 (saved == SPECIAL_LTE ||
1802 saved == SPECIAL_GTE ||
1803 saved == SPECIAL_UNSIGNED_LTE ||
1804 saved == SPECIAL_UNSIGNED_GTE))
1805 ret = 1;
1806 if (ret == 1)
1807 goto free;
1808 } END_FOR_EACH_PTR(sm);
1809
1810 return ret;
1811 free:
1812 free_string(one);
1813 free_string(two);
1814 return ret;
1815 }
1816
1817 struct state_list *get_all_comparisons(struct expression *expr)
1818 {
1819 struct smatch_state *state;
1820 struct string_list *links;
1821 struct state_list *ret = NULL;
1822 struct sm_state *sm;
1823 char *tmp;
1824
1825 state = get_state_chunk(link_id, expr);
1826 if (!state)
1827 return NULL;
1828 links = state->data;
1829
1830 FOR_EACH_PTR(links, tmp) {
1831 sm = get_sm_state(comparison_id, tmp, NULL);
1832 if (!sm)
1833 continue;
1834 // FIXME have to compare name with vsl
1835 add_ptr_list(&ret, sm);
1836 } END_FOR_EACH_PTR(tmp);
1837
1838 return ret;
1839 }
1840
1841 struct state_list *get_all_possible_equal_comparisons(struct expression *expr)
1842 {
1843 struct smatch_state *state;
1844 struct string_list *links;
1845 struct state_list *ret = NULL;
1846 struct sm_state *sm;
1847 char *tmp;
1848
1849 state = get_state_chunk(link_id, expr);
1850 if (!state)
1851 return NULL;
1852 links = state->data;
1853
1854 FOR_EACH_PTR(links, tmp) {
1855 sm = get_sm_state(comparison_id, tmp, NULL);
1856 if (!sm)
1857 continue;
1858 if (!strchr(sm->state->name, '='))
1859 continue;
1860 if (strcmp(sm->state->name, "!=") == 0)
1861 continue;
1862 add_ptr_list(&ret, sm);
1863 } END_FOR_EACH_PTR(tmp);
1864
1865 return ret;
1866 }
1867
1868 struct state_list *get_all_possible_not_equal_comparisons(struct expression *expr)
1869 {
1870 struct smatch_state *state;
1871 struct string_list *links;
1872 struct state_list *ret = NULL;
1873 struct sm_state *sm;
1874 struct sm_state *possible;
1875 char *link;
1876
1877 return NULL;
1878
1879 state = get_state_chunk(link_id, expr);
1880 if (!state)
1881 return NULL;
1882 links = state->data;
1883
1884 FOR_EACH_PTR(links, link) {
1885 sm = get_sm_state(comparison_id, link, NULL);
1886 if (!sm)
1887 continue;
1888 FOR_EACH_PTR(sm->possible, possible) {
1889 if (strcmp(possible->state->name, "!=") != 0)
1890 continue;
1891 add_ptr_list(&ret, sm);
1892 break;
1893 } END_FOR_EACH_PTR(link);
1894 } END_FOR_EACH_PTR(link);
1895
1896 return ret;
1897 }
1898
1899 static void update_links_from_call(struct expression *left,
1900 int left_compare,
1901 struct expression *right)
1902 {
1903 struct string_list *links;
1904 struct smatch_state *state;
1905 struct compare_data *data;
1906 struct symbol *left_sym, *right_sym;
1907 char *left_var = NULL;
1908 char *right_var = NULL;
1909 struct var_sym_list *left_vsl;
1910 struct expression *expr;
1911 const char *var;
1912 struct var_sym_list *vsl;
1913 int comparison;
1914 char *tmp;
1915
1916 left_var = chunk_to_var_sym(left, &left_sym);
1917 if (!left_var)
1918 goto done;
1919 left_vsl = expr_to_vsl(left);
1920 right_var = chunk_to_var_sym(right, &right_sym);
1921 if (!right_var)
1922 goto done;
1923
1924 state = get_state(link_id, right_var, right_sym);
1925 if (!state)
1926 return;
1927 links = state->data;
1928
1929 FOR_EACH_PTR(links, tmp) {
1930 state = get_state(comparison_id, tmp, NULL);
1931 if (!state || !state->data)
1932 continue;
1933 data = state->data;
1934 comparison = data->comparison;
1935 expr = data->right;
1936 var = data->right_var;
1937 vsl = data->right_vsl;
1938 if (strcmp(var, right_var) == 0) {
1939 expr = data->left;
1940 var = data->left_var;
1941 vsl = data->left_vsl;
1942 comparison = flip_comparison(comparison);
1943 }
1944 comparison = combine_comparisons(left_compare, comparison);
1945 if (!comparison)
1946 continue;
1947 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1948 } END_FOR_EACH_PTR(tmp);
1949
1950 done:
1951 free_string(right_var);
1952 }
1953
1954 void __add_return_comparison(struct expression *call, const char *range)
1955 {
1956 struct expression *arg;
1957 int comparison;
1958 char buf[16];
1959
1960 if (!str_to_comparison_arg(range, call, &comparison, &arg))
1961 return;
1962 snprintf(buf, sizeof(buf), "%s", show_comparison(comparison));
1963 update_links_from_call(call, comparison, arg);
1964 add_comparison(call, comparison, arg);
1965 }
1966
1967 void __add_comparison_info(struct expression *expr, struct expression *call, const char *range)
1968 {
1969 copy_comparisons(expr, call);
1970 }
1971
1972 static char *get_mask_comparison(struct expression *expr, int ignore)
1973 {
1974 struct expression *tmp, *right;
1975 int count, param;
1976 char buf[256];
1977
1978 /* The return value for "return foo & param;" is <= param */
1979
1980 count = 0;
1981 while ((tmp = get_assigned_expr(expr))) {
1982 expr = strip_expr(tmp);
1983 if (count++ > 4)
1984 break;
1985 }
1986
1987 if (expr->type != EXPR_BINOP || expr->op != '&')
1988 return NULL;
1989
1990 right = strip_expr(expr->right);
1991 param = get_param_num(right);
1992 if (param < 0 || param == ignore)
1993 return NULL;
1994
1995 snprintf(buf, sizeof(buf), "[<=$%d]", param);
1996 return alloc_sname(buf);
1997 }
1998
1999 static char *range_comparison_to_param_helper(struct expression *expr, char starts_with, int ignore)
2000 {
2001 struct symbol *param;
2002 char *var = NULL;
2003 char buf[256];
2004 char *ret_str = NULL;
2005 int compare;
2006 int i;
2007
2008 if (!expr)
2009 return NULL;
2010
2011 var = chunk_to_var(expr);
2012 if (!var)
2013 goto try_mask;
2014
2015 i = -1;
2016 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2017 i++;
2018 if (i == ignore)
2019 continue;
2020 if (!param->ident)
2021 continue;
2022 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2023 compare = get_comparison_strings(var, buf);
2024 if (compare == UNKNOWN_COMPARISON ||
2025 compare == IMPOSSIBLE_COMPARISON)
2026 continue;
2027 if (show_comparison(compare)[0] != starts_with)
2028 continue;
2029 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2030 ret_str = alloc_sname(buf);
2031 break;
2032 } END_FOR_EACH_PTR(param);
2033
2034 free_string(var);
2035 if (!ret_str)
2036 goto try_mask;
2037
2038 return ret_str;
2039
2040 try_mask:
2041 if (starts_with == '<')
2042 ret_str = get_mask_comparison(expr, ignore);
2043 return ret_str;
2044 }
2045
2046 char *name_sym_to_param_comparison(const char *name, struct symbol *sym)
2047 {
2048 struct symbol *param;
2049 char buf[256];
2050 int compare;
2051 int i;
2052
2053 i = -1;
2054 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2055 i++;
2056 if (!param->ident)
2057 continue;
2058 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2059 compare = get_comparison_strings(name, buf);
2060 if (compare == UNKNOWN_COMPARISON ||
2061 compare == IMPOSSIBLE_COMPARISON)
2062 continue;
2063 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2064 return alloc_sname(buf);
2065 } END_FOR_EACH_PTR(param);
2066
2067 return NULL;
2068 }
2069
2070 char *expr_equal_to_param(struct expression *expr, int ignore)
2071 {
2072 return range_comparison_to_param_helper(expr, '=', ignore);
2073 }
2074
2075 char *expr_lte_to_param(struct expression *expr, int ignore)
2076 {
2077 return range_comparison_to_param_helper(expr, '<', ignore);
2078 }
2079
2080 char *expr_param_comparison(struct expression *expr, int ignore)
2081 {
2082 struct symbol *param;
2083 char *var = NULL;
2084 char buf[256];
2085 char *ret_str = NULL;
2086 int compare;
2087 int i;
2088
2089 var = chunk_to_var(expr);
2090 if (!var)
2091 goto free;
2092
2093 i = -1;
2094 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2095 i++;
2096 if (i == ignore)
2097 continue;
2098 if (!param->ident)
2099 continue;
2100 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2101 compare = get_comparison_strings(var, buf);
2102 if (!compare)
2103 continue;
2104 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2105 ret_str = alloc_sname(buf);
2106 break;
2107 } END_FOR_EACH_PTR(param);
2108
2109 free:
2110 free_string(var);
2111 return ret_str;
2112 }
2113
2114 char *get_printed_param_name(struct expression *call, const char *param_name, struct symbol *param_sym)
2115 {
2116 struct expression *arg;
2117 char *name;
2118 struct symbol *sym;
2119 static char buf[256];
2120 int len;
2121 int i;
2122
2123 i = -1;
2124 FOR_EACH_PTR(call->args, arg) {
2125 i++;
2126
2127 name = expr_to_var_sym(arg, &sym);
2128 if (!name || !sym)
2129 continue;
2130 if (sym != param_sym)
2131 continue;
2132
2133 len = strlen(name);
2134 if (strncmp(name, param_name, len) != 0)
2135 continue;
2136 if (param_name[len] == '\0') {
2137 snprintf(buf, sizeof(buf), "$%d", i);
2138 return buf;
2139 }
2140 if (param_name[len] != '-')
2141 continue;
2142 snprintf(buf, sizeof(buf), "$%d%s", i, param_name + len);
2143 return buf;
2144 } END_FOR_EACH_PTR(arg);
2145
2146 return NULL;
2147 }
2148
2149 static void match_call_info(struct expression *expr)
2150 {
2151 struct expression *arg;
2152 struct smatch_state *state;
2153 struct sm_state *sm;
2154 struct compare_data *data;
2155 int comparison;
2156 struct string_list *links;
2157 char *arg_name;
2158 const char *right_name;
2159 char *link;
2160 char info_buf[256];
2161 int i;
2162
2163 i = -1;
2164 FOR_EACH_PTR(expr->args, arg) {
2165 i++;
2166
2167 state = get_state_chunk(link_id, arg);
2168 if (!state)
2169 continue;
2170
2171 links = state->data;
2172 FOR_EACH_PTR(links, link) {
2173 struct var_sym_list *right_vsl;
2174 struct var_sym *right_vs;
2175
2176
2177 if (strstr(link, " orig"))
2178 continue;
2179 sm = get_sm_state(comparison_id, link, NULL);
2180 if (!sm)
2181 continue;
2182 data = sm->state->data;
2183 if (!data ||
2184 data->comparison == UNKNOWN_COMPARISON ||
2185 data->comparison == IMPOSSIBLE_COMPARISON)
2186 continue;
2187 arg_name = expr_to_var(arg);
2188 if (!arg_name)
2189 continue;
2190
2191 right_vsl = NULL;
2192 if (strcmp(data->left_var, arg_name) == 0) {
2193 comparison = data->comparison;
2194 right_name = data->right_var;
2195 right_vsl = data->right_vsl;
2196 } else if (strcmp(data->right_var, arg_name) == 0) {
2197 comparison = flip_comparison(data->comparison);
2198 right_name = data->left_var;
2199 right_vsl = data->left_vsl;
2200 }
2201 if (!right_vsl || ptr_list_size((struct ptr_list *)right_vsl) != 1)
2202 goto free;
2203
2204 right_vs = first_ptr_list((struct ptr_list *)right_vsl);
2205 if (strcmp(right_vs->var, right_name) != 0)
2206 goto free;
2207 right_name = get_printed_param_name(expr, right_vs->var, right_vs->sym);
2208 if (!right_name)
2209 goto free;
2210 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(comparison), right_name);
2211 sql_insert_caller_info(expr, PARAM_COMPARE, i, "$", info_buf);
2212
2213 free:
2214 free_string(arg_name);
2215 } END_FOR_EACH_PTR(link);
2216 } END_FOR_EACH_PTR(arg);
2217 }
2218
2219 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *link_sm)
2220 {
2221 struct sm_state *compare_sm;
2222 struct string_list *links;
2223 char *link;
2224 struct compare_data *data;
2225 struct var_sym *left, *right;
2226 static char info_buf[256];
2227 const char *right_name;
2228
2229 if (strstr(printed_name, " orig"))
2230 return;
2231
2232 links = link_sm->state->data;
2233 FOR_EACH_PTR(links, link) {
2234 compare_sm = get_sm_state(comparison_id, link, NULL);
2235 if (!compare_sm)
2236 continue;
2237 data = compare_sm->state->data;
2238 if (!data || !data->comparison)
2239 continue;
2240
2241 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2242 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2243 continue;
2244 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2245 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2246 if (left->sym == right->sym &&
2247 strcmp(left->var, right->var) == 0)
2248 continue;
2249 /*
2250 * Both parameters link to this comparison so only
2251 * record the first one.
2252 */
2253 if (left->sym != link_sm->sym ||
2254 strcmp(left->var, link_sm->name) != 0)
2255 continue;
2256
2257 right_name = get_printed_param_name(call, right->var, right->sym);
2258 if (!right_name)
2259 continue;
2260 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_name);
2261 sql_insert_caller_info(call, PARAM_COMPARE, param, printed_name, info_buf);
2262 } END_FOR_EACH_PTR(link);
2263 }
2264
2265 static void print_return_value_comparison(int return_id, char *return_ranges, struct expression *expr)
2266 {
2267 char *name;
2268 const char *tmp_name;
2269 struct symbol *sym;
2270 int param;
2271 char info_buf[256];
2272
2273 /*
2274 * TODO: This only prints == comparisons. That's probably the most
2275 * useful comparison because == max has lots of implications. But it
2276 * would be good to capture the rest as well.
2277 *
2278 * This information is already in the DB but it's in the parameter math
2279 * bits and it's awkward to use it. This is is the simpler, possibly
2280 * cleaner way, but not necessarily the best, I don't know.
2281 */
2282
2283 if (!expr)
2284 return;
2285 name = expr_to_var_sym(expr, &sym);
2286 if (!name || !sym)
2287 goto free;
2288
2289 param = get_param_num_from_sym(sym);
2290 if (param < 0)
2291 goto free;
2292 if (param_was_set_var_sym(name, sym))
2293 goto free;
2294
2295 tmp_name = get_param_name_var_sym(name, sym);
2296 if (!tmp_name)
2297 goto free;
2298
2299 snprintf(info_buf, sizeof(info_buf), "== $%d%s", param, tmp_name + 1);
2300 sql_insert_return_states(return_id, return_ranges,
2301 PARAM_COMPARE, -1, "$", info_buf);
2302 free:
2303 free_string(name);
2304 }
2305
2306 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
2307 {
2308 struct sm_state *tmp;
2309 struct string_list *links;
2310 char *link;
2311 struct sm_state *sm;
2312 struct compare_data *data;
2313 struct var_sym *left, *right;
2314 int left_param, right_param;
2315 char left_buf[256];
2316 char right_buf[256];
2317 char info_buf[258];
2318 const char *tmp_name;
2319
2320 print_return_value_comparison(return_id, return_ranges, expr);
2321
2322 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
2323 if (get_param_num_from_sym(tmp->sym) < 0)
2324 continue;
2325 links = tmp->state->data;
2326 FOR_EACH_PTR(links, link) {
2327 sm = get_sm_state(comparison_id, link, NULL);
2328 if (!sm)
2329 continue;
2330 data = sm->state->data;
2331 if (!data ||
2332 data->comparison == UNKNOWN_COMPARISON ||
2333 data->comparison == IMPOSSIBLE_COMPARISON)
2334 continue;
2335 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2336 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2337 continue;
2338 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2339 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2340 if (left->sym == right->sym &&
2341 strcmp(left->var, right->var) == 0)
2342 continue;
2343 /*
2344 * Both parameters link to this comparison so only
2345 * record the first one.
2346 */
2347 if (left->sym != tmp->sym ||
2348 strcmp(left->var, tmp->name) != 0)
2349 continue;
2350
2351 if (strstr(right->var, " orig"))
2352 continue;
2353
2354 left_param = get_param_num_from_sym(left->sym);
2355 right_param = get_param_num_from_sym(right->sym);
2356 if (left_param < 0 || right_param < 0)
2357 continue;
2358
2359 tmp_name = get_param_name_var_sym(left->var, left->sym);
2360 if (!tmp_name)
2361 continue;
2362 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
2363
2364 tmp_name = get_param_name_var_sym(right->var, right->sym);
2365 if (!tmp_name || tmp_name[0] != '$')
2366 continue;
2367 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
2368
2369 /*
2370 * FIXME: this should reject $ type variables (as
2371 * opposed to $->foo type). Those should come from
2372 * smatch_param_compare_limit.c.
2373 */
2374
2375 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_buf);
2376 sql_insert_return_states(return_id, return_ranges,
2377 PARAM_COMPARE, left_param, left_buf, info_buf);
2378 } END_FOR_EACH_PTR(link);
2379
2380 } END_FOR_EACH_SM(tmp);
2381 }
2382
2383 static int parse_comparison(char **value, int *op)
2384 {
2385
2386 *op = **value;
2387
2388 switch (*op) {
2389 case '<':
2390 (*value)++;
2391 if (**value == '=') {
2392 (*value)++;
2393 *op = SPECIAL_LTE;
2394 }
2395 break;
2396 case '=':
2397 (*value)++;
2398 (*value)++;
2399 *op = SPECIAL_EQUAL;
2400 break;
2401 case '!':
2402 (*value)++;
2403 (*value)++;
2404 *op = SPECIAL_NOTEQUAL;
2405 break;
2406 case '>':
2407 (*value)++;
2408 if (**value == '=') {
2409 (*value)++;
2410 *op = SPECIAL_GTE;
2411 }
2412 break;
2413 default:
2414 return 0;
2415 }
2416
2417 if (**value != ' ') {
2418 sm_perror("parsing comparison. %s", *value);
2419 return 0;
2420 }
2421
2422 (*value)++;
2423 return 1;
2424 }
2425
2426 static int split_op_param_key(char *value, int *op, int *param, char **key)
2427 {
2428 static char buf[256];
2429 char *p;
2430
2431 if (!parse_comparison(&value, op))
2432 return 0;
2433
2434 snprintf(buf, sizeof(buf), "%s", value);
2435
2436 p = buf;
2437 if (*p++ != '$')
2438 return 0;
2439
2440 *param = atoi(p);
2441 if (*param < 0 || *param > 99)
2442 return 0;
2443 p++;
2444 if (*param > 9)
2445 p++;
2446 p--;
2447 *p = '$';
2448 *key = p;
2449
2450 return 1;
2451 }
2452
2453 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
2454 {
2455 struct expression *left_arg, *right_arg;
2456 char *left_name = NULL;
2457 struct symbol *left_sym;
2458 char *right_name = NULL;
2459 struct symbol *right_sym;
2460 int op;
2461 int right_param;
2462 char *right_key;
2463 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
2464
2465 if (left_param == -1) {
2466 if (expr->type != EXPR_ASSIGNMENT)
2467 return;
2468 left_arg = strip_expr(expr->left);
2469
2470 while (expr->type == EXPR_ASSIGNMENT)
2471 expr = strip_expr(expr->right);
2472 if (expr->type != EXPR_CALL)
2473 return;
2474 } else {
2475 while (expr->type == EXPR_ASSIGNMENT)
2476 expr = strip_expr(expr->right);
2477 if (expr->type != EXPR_CALL)
2478 return;
2479
2480 left_arg = get_argument_from_call_expr(expr->args, left_param);
2481 if (!left_arg)
2482 return;
2483 }
2484
2485 if (!split_op_param_key(value, &op, &right_param, &right_key))
2486 return;
2487
2488 right_arg = get_argument_from_call_expr(expr->args, right_param);
2489 if (!right_arg)
2490 return;
2491
2492 left_name = get_variable_from_key(left_arg, key, &left_sym);
2493 if (!left_name || !left_sym)
2494 goto free;
2495
2496 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2497 if (!right_name || !right_sym)
2498 goto free;
2499
2500 add_var_sym(&left_vsl, left_name, left_sym);
2501 add_var_sym(&right_vsl, right_name, right_sym);
2502
2503 add_comparison_var_sym(NULL, left_name, left_vsl, op, NULL, right_name, right_vsl);
2504
2505 free:
2506 free_string(left_name);
2507 free_string(right_name);
2508 }
2509
2510 int param_compare_limit_is_impossible(struct expression *expr, int left_param, char *left_key, char *value)
2511 {
2512 struct smatch_state *state;
2513 char *left_name = NULL;
2514 char *right_name = NULL;
2515 struct symbol *left_sym, *right_sym;
2516 struct expression *left_arg, *right_arg;
2517 int op, state_op;
2518 int right_param;
2519 char *right_key;
2520 int ret = 0;
2521 char buf[256];
2522
2523 while (expr->type == EXPR_ASSIGNMENT)
2524 expr = strip_expr(expr->right);
2525 if (expr->type != EXPR_CALL)
2526 return 0;
2527
2528 if (!split_op_param_key(value, &op, &right_param, &right_key))
2529 return 0;
2530
2531 left_arg = get_argument_from_call_expr(expr->args, left_param);
2532 if (!left_arg)
2533 return 0;
2534
2535 right_arg = get_argument_from_call_expr(expr->args, right_param);
2536 if (!right_arg)
2537 return 0;
2538
2539 left_name = get_variable_from_key(left_arg, left_key, &left_sym);
2540 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2541 if (!left_name || !right_name)
2542 goto free;
2543
2544 snprintf(buf, sizeof(buf), "%s vs %s", left_name, right_name);
2545 state = get_state(comparison_id, buf, NULL);
2546 if (!state)
2547 goto free;
2548 state_op = state_to_comparison(state);
2549 if (!state_op)
2550 goto free;
2551
2552 if (!comparison_intersection(remove_unsigned_from_comparison(state_op), op))
2553 ret = 1;
2554 free:
2555 free_string(left_name);
2556 free_string(right_name);
2557 return ret;
2558 }
2559
2560 int impossibly_high_comparison(struct expression *expr)
2561 {
2562 struct smatch_state *link_state;
2563 struct sm_state *sm;
2564 struct string_list *links;
2565 char *link;
2566 struct compare_data *data;
2567
2568 link_state = get_state_expr(link_id, expr);
2569 if (!link_state) {
2570 if (expr->type == EXPR_BINOP &&
2571 (impossibly_high_comparison(expr->left) ||
2572 impossibly_high_comparison(expr->right)))
2573 return 1;
2574 return 0;
2575 }
2576
2577 links = link_state->data;
2578 FOR_EACH_PTR(links, link) {
2579 sm = get_sm_state(comparison_id, link, NULL);
2580 if (!sm)
2581 continue;
2582 data = sm->state->data;
2583 if (!data)
2584 continue;
2585 if (!possibly_true(data->left, data->comparison, data->right))
2586 return 1;
2587 } END_FOR_EACH_PTR(link);
2588
2589 return 0;
2590 }
2591
2592 static void free_data(struct symbol *sym)
2593 {
2594 if (__inline_fn)
2595 return;
2596 clear_compare_data_alloc();
2597 }
2598
2599 void register_comparison(int id)
2600 {
2601 comparison_id = id;
2602 set_dynamic_states(comparison_id);
2603 add_hook(&save_start_states, AFTER_DEF_HOOK);
2604 add_unmatched_state_hook(comparison_id, unmatched_comparison);
2605 add_pre_merge_hook(comparison_id, &pre_merge_hook);
2606 add_merge_hook(comparison_id, &merge_compare_states);
2607 add_hook(&free_data, AFTER_FUNC_HOOK);
2608 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2609 add_split_return_callback(&print_return_comparison);
2610
2611 select_return_states_hook(PARAM_COMPARE, &db_return_comparison);
2612 add_hook(&match_preop, OP_HOOK);
2613 }
2614
2615 void register_comparison_late(int id)
2616 {
2617 add_hook(&match_assign, ASSIGNMENT_HOOK);
2618 }
2619
2620 void register_comparison_links(int id)
2621 {
2622 link_id = id;
2623 db_ignore_states(link_id);
2624 set_dynamic_states(link_id);
2625 add_merge_hook(link_id, &merge_links);
2626 add_modification_hook(link_id, &match_modify);
2627 add_modification_hook_late(link_id, match_inc_dec);
2628
2629 add_member_info_callback(link_id, struct_member_callback);
2630 }
2631
2632 void register_comparison_inc_dec(int id)
2633 {
2634 inc_dec_id = id;
2635 add_modification_hook_late(inc_dec_id, &iter_modify);
2636 }
2637
2638 void register_comparison_inc_dec_links(int id)
2639 {
2640 inc_dec_link_id = id;
2641 set_dynamic_states(inc_dec_link_id);
2642 set_up_link_functions(inc_dec_id, inc_dec_link_id);
2643 }
2644
2645 static struct sm_state *clone_partial_sm(struct sm_state *sm, int comparison)
2646 {
2647 struct compare_data *data;
2648 struct sm_state *clone;
2649 struct stree *stree;
2650
2651 data = sm->state->data;
2652
2653 clone = clone_sm(sm);
2654 clone->state = alloc_compare_state(data->left, data->left_var, data->left_vsl,
2655 comparison,
2656 data->right, data->right_var, data->right_vsl);
2657 free_slist(&clone->possible);
2658 add_possible_sm(clone, clone);
2659
2660 stree = clone_stree(sm->pool);
2661 overwrite_sm_state_stree(&stree, clone);
2662 clone->pool = stree;
2663
2664 return clone;
2665 }
2666
2667 static void create_fake_history(struct sm_state *sm, int op,
2668 struct state_list **true_stack,
2669 struct state_list **false_stack)
2670 {
2671 struct sm_state *true_sm, *false_sm;
2672 struct compare_data *data;
2673 int true_comparison;
2674 int false_comparison;
2675
2676 data = sm->state->data;
2677
2678 if (is_merged(sm) || sm->left || sm->right)
2679 return;
2680
2681 true_comparison = comparison_intersection(data->comparison, op);
2682 false_comparison = comparison_intersection(data->comparison, negate_comparison(op));
2683
2684 true_sm = clone_partial_sm(sm, true_comparison);
2685 false_sm = clone_partial_sm(sm, false_comparison);
2686
2687 sm->merged = 1;
2688 sm->left = true_sm;
2689 sm->right = false_sm;
2690
2691 add_ptr_list(true_stack, true_sm);
2692 add_ptr_list(false_stack, false_sm);
2693 }
2694
2695 static void filter_by_sm(struct sm_state *sm, int op,
2696 struct state_list **true_stack,
2697 struct state_list **false_stack,
2698 bool *useful)
2699 {
2700 struct compare_data *data;
2701 int is_true = 0;
2702 int is_false = 0;
2703
2704 if (!sm)
2705 return;
2706 data = sm->state->data;
2707 if (!data)
2708 goto split;
2709 if (data->comparison == IMPOSSIBLE_COMPARISON)
2710 return;
2711
2712 /*
2713 * We want to check that "data->comparison" is totally inside "op". So
2714 * if data->comparison is < and op is <= then that's true. Or if
2715 * data->comparison is == and op is <= then that's true. But if
2716 * data->comparison is <= and op is < than that's neither true nor
2717 * false.
2718 */
2719 if (data->comparison == comparison_intersection(data->comparison, op))
2720 is_true = 1;
2721 if (data->comparison == comparison_intersection(data->comparison, negate_comparison(op)))
2722 is_false = 1;
2723
2724 if (!is_true && !is_false && !is_merged(sm)) {
2725 create_fake_history(sm, op, true_stack, false_stack);
2726 return;
2727 }
2728
2729 if (debug_implied()) {
2730 sm_msg("%s: %s: op = '%s' negated '%s'. true_intersect = '%s' false_insersect = '%s' sm = '%s'",
2731 __func__,
2732 sm->state->name,
2733 alloc_sname(show_comparison(op)),
2734 alloc_sname(show_comparison(negate_comparison(op))),
2735 alloc_sname(show_comparison(comparison_intersection(data->comparison, op))),
2736 alloc_sname(show_comparison(comparison_intersection(data->comparison, negate_comparison(op)))),
2737 show_sm(sm));
2738 }
2739
2740 *useful = true;
2741 if (is_true)
2742 add_ptr_list(true_stack, sm);
2743 if (is_false)
2744 add_ptr_list(false_stack, sm);
2745 split:
2746 filter_by_sm(sm->left, op, true_stack, false_stack, useful);
2747 filter_by_sm(sm->right, op, true_stack, false_stack, useful);
2748 }
2749
2750 struct sm_state *comparison_implication_hook(struct expression *expr,
2751 struct state_list **true_stack,
2752 struct state_list **false_stack)
2753 {
2754 struct sm_state *sm;
2755 char *left, *right;
2756 int op;
2757 static char buf[256];
2758 bool useful = false;
2759
2760 if (expr->type != EXPR_COMPARE)
2761 return NULL;
2762
2763 op = expr->op;
2764
2765 left = expr_to_var(expr->left);
2766 right = expr_to_var(expr->right);
2767 if (!left || !right) {
2768 free_string(left);
2769 free_string(right);
2770 return NULL;
2771 }
2772
2773 if (strcmp(left, right) > 0) {
2774 char *tmp = left;
2775
2776 left = right;
2777 right = tmp;
2778 op = flip_comparison(op);
2779 }
2780
2781 snprintf(buf, sizeof(buf), "%s vs %s", left, right);
2782 sm = get_sm_state(comparison_id, buf, NULL);
2783 if (!sm)
2784 return NULL;
2785 if (!sm->merged)
2786 return NULL;
2787
2788 filter_by_sm(sm, op, true_stack, false_stack, &useful);
2789 if (!useful)
2790 return NULL;
2791
2792 if (debug_implied())
2793 sm_msg("implications from comparison: (%s)", show_sm(sm));
2794
2795 return sm;
2796 }
Static analysis for C