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 static int compare_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 if (!data)
546 return;
547
548 if (in_recurse)
549 return;
550 in_recurse = true;
551 extra = comparison_from_extra(data->left, data->right);
552 in_recurse = false;
553 if (!extra)
554 return;
555 new = comparison_intersection(extra, data->comparison);
556 if (new == data->comparison)
557 return;
558
559 set_state(compare_id, cur->name, NULL,
560 alloc_compare_state(data->left, data->left_var, data->left_vsl,
561 new,
562 data->right, data->right_var, data->right_vsl));
563 }
564
565 struct smatch_state *merge_compare_states(struct smatch_state *s1, struct smatch_state *s2)
566 {
567 struct compare_data *data = s1->data;
568 int op;
569
570 if (!data)
571 return &undefined;
572
573 op = merge_comparisons(state_to_comparison(s1), state_to_comparison(s2));
574 return alloc_compare_state(
575 data->left, data->left_var, data->left_vsl,
576 op,
577 data->right, data->right_var, data->right_vsl);
578 }
579
580 static struct smatch_state *alloc_link_state(struct string_list *links)
581 {
582 struct smatch_state *state;
583 static char buf[256];
584 char *tmp;
585 int i;
586
587 state = __alloc_smatch_state(0);
588
589 i = 0;
590 FOR_EACH_PTR(links, tmp) {
591 if (!i++) {
592 snprintf(buf, sizeof(buf), "%s", tmp);
593 } else {
594 append(buf, ", ", sizeof(buf));
595 append(buf, tmp, sizeof(buf));
596 }
597 } END_FOR_EACH_PTR(tmp);
598
599 state->name = alloc_sname(buf);
600 state->data = links;
601 return state;
602 }
603
604 static void save_start_states(struct statement *stmt)
605 {
606 struct symbol *param;
607 char orig[64];
608 char state_name[128];
609 struct smatch_state *state;
610 struct string_list *links;
611 char *link;
612
613 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
614 struct var_sym_list *left_vsl = NULL;
615 struct var_sym_list *right_vsl = NULL;
616
617 if (!param->ident)
618 continue;
619 snprintf(orig, sizeof(orig), "%s orig", param->ident->name);
620 snprintf(state_name, sizeof(state_name), "%s vs %s", param->ident->name, orig);
621 add_var_sym(&left_vsl, param->ident->name, param);
622 add_var_sym(&right_vsl, orig, param);
623 state = alloc_compare_state(
624 NULL, param->ident->name, left_vsl,
625 SPECIAL_EQUAL,
626 NULL, alloc_sname(orig), right_vsl);
627 set_state(compare_id, state_name, NULL, state);
628
629 link = alloc_sname(state_name);
630 links = NULL;
631 insert_string(&links, link);
632 state = alloc_link_state(links);
633 set_state(link_id, param->ident->name, param, state);
634 } END_FOR_EACH_PTR(param);
635 }
636
637 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
638 {
639 struct smatch_state *ret;
640 struct string_list *links;
641
642 links = combine_string_lists(s1->data, s2->data);
643 ret = alloc_link_state(links);
644 return ret;
645 }
646
647 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
648 {
649 struct smatch_state *old_state, *new_state;
650 struct string_list *links;
651 char *new;
652
653 old_state = get_state(link_id, var, sym);
654 if (old_state)
655 links = clone_str_list(old_state->data);
656 else
657 links = NULL;
658
659 new = alloc_sname(link);
660 insert_string(&links, new);
661
662 new_state = alloc_link_state(links);
663 set_state(link_id, var, sym, new_state);
664 }
665
666 static void match_inc(struct sm_state *sm, bool preserve)
667 {
668 struct string_list *links;
669 struct smatch_state *state, *new;
670 struct compare_data *data;
671 char *tmp;
672 int flip;
673 int op;
674
675 links = sm->state->data;
676
677 FOR_EACH_PTR(links, tmp) {
678 state = get_state(compare_id, tmp, NULL);
679 if (!state)
680 continue;
681 data = state->data;
682 if (!data)
683 continue;
684
685 flip = 0;
686 if (strncmp(sm->name, tmp, strlen(sm->name)) != 0 ||
687 tmp[strlen(sm->name)] != ' ')
688 flip = 1;
689
690 op = state_to_comparison(state);
691
692 switch (flip ? flip_comparison(op) : op) {
693 case SPECIAL_EQUAL:
694 case SPECIAL_GTE:
695 case SPECIAL_UNSIGNED_GTE:
696 case '>':
697 case SPECIAL_UNSIGNED_GT:
698 if (preserve)
699 break;
700 new = alloc_compare_state(
701 data->left, data->left_var, data->left_vsl,
702 flip ? '<' : '>',
703 data->right, data->right_var, data->right_vsl);
704 set_state(compare_id, tmp, NULL, new);
705 break;
706 case '<':
707 case SPECIAL_UNSIGNED_LT:
708 new = alloc_compare_state(
709 data->left, data->left_var, data->left_vsl,
710 flip ? SPECIAL_GTE : SPECIAL_LTE,
711 data->right, data->right_var, data->right_vsl);
712 set_state(compare_id, tmp, NULL, new);
713 break;
714 default:
715 new = alloc_compare_state(
716 data->left, data->left_var, data->left_vsl,
717 UNKNOWN_COMPARISON,
718 data->right, data->right_var, data->right_vsl);
719 set_state(compare_id, tmp, NULL, new);
720 }
721 } END_FOR_EACH_PTR(tmp);
722 }
723
724 static void match_dec(struct sm_state *sm, bool preserve)
725 {
726 struct string_list *links;
727 struct smatch_state *state;
728 char *tmp;
729
730 links = sm->state->data;
731
732 FOR_EACH_PTR(links, tmp) {
733 struct compare_data *data;
734 struct smatch_state *new;
735
736 state = get_state(compare_id, tmp, NULL);
737 if (!state || !state->data)
738 continue;
739
740 data = state->data;
741
742 switch (state_to_comparison(state)) {
743 case SPECIAL_EQUAL:
744 case SPECIAL_LTE:
745 case SPECIAL_UNSIGNED_LTE:
746 case '<':
747 case SPECIAL_UNSIGNED_LT: {
748 if (preserve)
749 break;
750
751 new = alloc_compare_state(
752 data->left, data->left_var, data->left_vsl,
753 '<',
754 data->right, data->right_var, data->right_vsl);
755 set_state(compare_id, tmp, NULL, new);
756 break;
757 }
758 default:
759 new = alloc_compare_state(
760 data->left, data->left_var, data->left_vsl,
761 UNKNOWN_COMPARISON,
762 data->right, data->right_var, data->right_vsl);
763 set_state(compare_id, tmp, NULL, new);
764 }
765 } END_FOR_EACH_PTR(tmp);
766 }
767
768 static void reset_sm(struct sm_state *sm)
769 {
770 struct string_list *links;
771 char *tmp;
772
773 links = sm->state->data;
774
775 FOR_EACH_PTR(links, tmp) {
776 struct smatch_state *old, *new;
777
778 old = get_state(compare_id, tmp, NULL);
779 if (!old || !old->data) {
780 new = &undefined;
781 } else {
782 struct compare_data *data = old->data;
783
784 new = alloc_compare_state(
785 data->left, data->left_var, data->left_vsl,
786 UNKNOWN_COMPARISON,
787 data->right, data->right_var, data->right_vsl);
788 }
789 set_state(compare_id, tmp, NULL, new);
790 } END_FOR_EACH_PTR(tmp);
791 set_state(link_id, sm->name, sm->sym, &undefined);
792 }
793
794 static bool match_add_sub_assign(struct sm_state *sm, struct expression *expr)
795 {
796 struct range_list *rl;
797 sval_t zero = { .type = &int_ctype };
798
799 if (!expr || expr->type != EXPR_ASSIGNMENT)
800 return false;
801 if (expr->op != SPECIAL_ADD_ASSIGN && expr->op != SPECIAL_SUB_ASSIGN)
802 return false;
803
804 get_absolute_rl(expr->right, &rl);
805 if (sval_is_negative(rl_min(rl))) {
806 reset_sm(sm);
807 return false;
808 }
809
810 if (expr->op == SPECIAL_ADD_ASSIGN)
811 match_inc(sm, rl_has_sval(rl, zero));
812 else
813 match_dec(sm, rl_has_sval(rl, zero));
814 return true;
815 }
816
817 static void match_inc_dec(struct sm_state *sm, struct expression *mod_expr)
818 {
819 /*
820 * if (foo > bar) then ++foo is also > bar.
821 */
822 if (!mod_expr)
823 return;
824 if (match_add_sub_assign(sm, mod_expr))
825 return;
826 if (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP)
827 return;
828
829 if (mod_expr->op == SPECIAL_INCREMENT)
830 match_inc(sm, false);
831 else if (mod_expr->op == SPECIAL_DECREMENT)
832 match_dec(sm, false);
833 }
834
835 static int is_self_assign(struct expression *expr)
836 {
837 if (!expr || expr->type != EXPR_ASSIGNMENT || expr->op != '=')
838 return 0;
839 return expr_equiv(expr->left, expr->right);
840 }
841
842 static void match_modify(struct sm_state *sm, struct expression *mod_expr)
843 {
844 if (mod_expr && is_self_assign(mod_expr))
845 return;
846
847 /* handled by match_inc_dec() */
848 if (mod_expr &&
849 ((mod_expr->type == EXPR_PREOP || mod_expr->type == EXPR_POSTOP) &&
850 (mod_expr->op == SPECIAL_INCREMENT || mod_expr->op == SPECIAL_DECREMENT)))
851 return;
852 if (mod_expr && mod_expr->type == EXPR_ASSIGNMENT &&
853 (mod_expr->op == SPECIAL_ADD_ASSIGN || mod_expr->op == SPECIAL_SUB_ASSIGN))
854 return;
855
856 reset_sm(sm);
857 }
858
859 static void match_preop(struct expression *expr)
860 {
861 struct expression *parent;
862 struct range_list *left, *right;
863 int op;
864
865 /*
866 * This is an important special case. Say you have:
867 *
868 * if (++j == limit)
869 *
870 * Assume that we know the range of limit is higher than the start
871 * value for "j". Then the first thing that we process is the ++j. We
872 * have not comparison states set up so it doesn't get caught by the
873 * modification hook. But it does get caught by smatch_extra which sets
874 * j to unknown then we parse the "j == limit" and sets false to != but
875 * really we want false to be <.
876 *
877 * So what we do is we set j < limit here, then the match_modify catches
878 * it and we do a match_inc_dec().
879 *
880 */
881
882 if (expr->type != EXPR_PREOP ||
883 (expr->op != SPECIAL_INCREMENT && expr->op != SPECIAL_DECREMENT))
884 return;
885
886 parent = expr_get_parent_expr(expr);
887 if (!parent)
888 return;
889 if (parent->type != EXPR_COMPARE || parent->op != SPECIAL_EQUAL)
890 return;
891 if (parent->left != expr)
892 return;
893
894 if (!get_implied_rl(expr->unop, &left) ||
895 !get_implied_rl(parent->right, &right))
896 return;
897
898 op = rl_comparison(left, right);
899 if (op == UNKNOWN_COMPARISON)
900 return;
901
902 add_comparison(expr->unop, op, parent->right);
903 }
904
905 static char *chunk_to_var_sym(struct expression *expr, struct symbol **sym)
906 {
907 expr = strip_expr(expr);
908 if (!expr)
909 return NULL;
910 if (sym)
911 *sym = NULL;
912
913 if (expr->type == EXPR_PREOP &&
914 (expr->op == SPECIAL_INCREMENT ||
915 expr->op == SPECIAL_DECREMENT))
916 expr = strip_expr(expr->unop);
917
918 if (expr->type == EXPR_CALL) {
919 char buf[64];
920
921 snprintf(buf, sizeof(buf), "return %p", expr);
922 return alloc_string(buf);
923 }
924
925 return expr_to_chunk_sym_vsl(expr, sym, NULL);
926 }
927
928 static char *chunk_to_var(struct expression *expr)
929 {
930 return chunk_to_var_sym(expr, NULL);
931 }
932
933 static struct smatch_state *get_state_chunk(int owner, struct expression *expr)
934 {
935 char *name;
936 struct symbol *sym;
937 struct smatch_state *ret;
938
939 name = chunk_to_var_sym(expr, &sym);
940 if (!name)
941 return NULL;
942
943 ret = get_state(owner, name, sym);
944 free_string(name);
945 return ret;
946 }
947
948 static void save_link(struct expression *expr, char *link)
949 {
950 char *var;
951 struct symbol *sym;
952
953 expr = strip_expr(expr);
954 if (expr->type == EXPR_BINOP) {
955 char *chunk;
956
957 chunk = chunk_to_var(expr);
958 if (!chunk)
959 return;
960
961 save_link(expr->left, link);
962 save_link(expr->right, link);
963 save_link_var_sym(chunk, NULL, link);
964 return;
965 }
966
967 var = chunk_to_var_sym(expr, &sym);
968 if (!var)
969 return;
970
971 save_link_var_sym(var, sym, link);
972 free_string(var);
973 }
974
975 static int get_orig_comparison(struct stree *pre_stree, const char *left, const char *right)
976 {
977 struct smatch_state *state;
978 struct compare_data *data;
979 int flip = 0;
980 char state_name[256];
981
982 if (strcmp(left, right) > 0) {
983 const char *tmp = right;
984
985 flip = 1;
986 right = left;
987 left = tmp;
988 }
989
990 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
991 state = get_state_stree(pre_stree, compare_id, state_name, NULL);
992 if (!state || !state->data)
993 return 0;
994 data = state->data;
995 if (flip)
996 return flip_comparison(data->comparison);
997 return data->comparison;
998
999 }
1000
1001 static int have_common_var_sym(struct var_sym_list *left_vsl, struct var_sym_list *right_vsl)
1002 {
1003 struct var_sym *tmp;
1004
1005 FOR_EACH_PTR(left_vsl, tmp) {
1006 if (in_var_sym_list(right_vsl, tmp->var, tmp->sym))
1007 return 1;
1008 } END_FOR_EACH_PTR(tmp);
1009
1010 return 0;
1011 }
1012
1013 /*
1014 * The idea here is that we take a comparison "a < b" and then we look at all
1015 * the things which "b" is compared against "b < c" and we say that that implies
1016 * a relationship "a < c".
1017 *
1018 * The names here about because the comparisons are organized like this
1019 * "a < b < c".
1020 *
1021 */
1022 static void update_tf_links(struct stree *pre_stree,
1023 struct expression *left_expr,
1024 const char *left_var, struct var_sym_list *left_vsl,
1025 int left_comparison, int left_false_comparison,
1026 const char *mid_var, struct var_sym_list *mid_vsl,
1027 struct string_list *links)
1028 {
1029 struct smatch_state *state;
1030 struct smatch_state *true_state, *false_state;
1031 struct compare_data *data;
1032 struct expression *right_expr;
1033 const char *right_var;
1034 struct var_sym_list *right_vsl;
1035 int orig_comparison;
1036 int right_comparison;
1037 int true_comparison;
1038 int false_comparison;
1039 char *tmp;
1040 char state_name[256];
1041 struct var_sym *vs;
1042
1043 FOR_EACH_PTR(links, tmp) {
1044 state = get_state_stree(pre_stree, compare_id, tmp, NULL);
1045 if (!state || !state->data)
1046 continue;
1047 data = state->data;
1048 right_comparison = data->comparison;
1049 right_expr = data->right;
1050 right_var = data->right_var;
1051 right_vsl = data->right_vsl;
1052 if (strcmp(mid_var, right_var) == 0) {
1053 right_expr = data->left;
1054 right_var = data->left_var;
1055 right_vsl = data->left_vsl;
1056 right_comparison = flip_comparison(right_comparison);
1057 }
1058 if (have_common_var_sym(left_vsl, right_vsl))
1059 continue;
1060
1061 orig_comparison = get_orig_comparison(pre_stree, left_var, right_var);
1062
1063 true_comparison = combine_comparisons(left_comparison, right_comparison);
1064 false_comparison = combine_comparisons(left_false_comparison, right_comparison);
1065
1066 true_comparison = comparison_intersection(orig_comparison, true_comparison);
1067 false_comparison = comparison_intersection(orig_comparison, false_comparison);
1068
1069 if (strcmp(left_var, right_var) > 0) {
1070 struct expression *tmp_expr = left_expr;
1071 const char *tmp_var = left_var;
1072 struct var_sym_list *tmp_vsl = left_vsl;
1073
1074 left_expr = right_expr;
1075 left_var = right_var;
1076 left_vsl = right_vsl;
1077 right_expr = tmp_expr;
1078 right_var = tmp_var;
1079 right_vsl = tmp_vsl;
1080 true_comparison = flip_comparison(true_comparison);
1081 false_comparison = flip_comparison(false_comparison);
1082 }
1083
1084 if (!true_comparison && !false_comparison)
1085 continue;
1086
1087 if (true_comparison)
1088 true_state = alloc_compare_state(
1089 left_expr, left_var, left_vsl,
1090 true_comparison,
1091 right_expr, right_var, right_vsl);
1092 else
1093 true_state = NULL;
1094 if (false_comparison)
1095 false_state = alloc_compare_state(
1096 left_expr, left_var, left_vsl,
1097 false_comparison,
1098 right_expr, right_var, right_vsl);
1099 else
1100 false_state = NULL;
1101
1102 snprintf(state_name, sizeof(state_name), "%s vs %s", left_var, right_var);
1103 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
1104 FOR_EACH_PTR(left_vsl, vs) {
1105 save_link_var_sym(vs->var, vs->sym, state_name);
1106 } END_FOR_EACH_PTR(vs);
1107 FOR_EACH_PTR(right_vsl, vs) {
1108 save_link_var_sym(vs->var, vs->sym, state_name);
1109 } END_FOR_EACH_PTR(vs);
1110 if (!vsl_to_sym(left_vsl))
1111 save_link_var_sym(left_var, NULL, state_name);
1112 if (!vsl_to_sym(right_vsl))
1113 save_link_var_sym(right_var, NULL, state_name);
1114 } END_FOR_EACH_PTR(tmp);
1115 }
1116
1117 static void update_tf_data(struct stree *pre_stree,
1118 struct expression *left_expr,
1119 const char *left_name, struct var_sym_list *left_vsl,
1120 struct expression *right_expr,
1121 const char *right_name, struct var_sym_list *right_vsl,
1122 int true_comparison, int false_comparison)
1123 {
1124 struct smatch_state *state;
1125
1126 state = get_state_stree(pre_stree, link_id, right_name, vsl_to_sym(right_vsl));
1127 if (state)
1128 update_tf_links(pre_stree, left_expr, left_name, left_vsl, true_comparison, false_comparison, right_name, right_vsl, state->data);
1129
1130 state = get_state_stree(pre_stree, link_id, left_name, vsl_to_sym(left_vsl));
1131 if (state)
1132 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);
1133 }
1134
1135 static void iter_modify(struct sm_state *sm, struct expression *mod_expr)
1136 {
1137 if (sm->state != &start ||
1138 !mod_expr ||
1139 (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP) ||
1140 mod_expr->op != SPECIAL_INCREMENT)
1141 set_state(inc_dec_id, sm->name, sm->sym, &undefined);
1142 else
1143 set_state(inc_dec_id, sm->name, sm->sym, &incremented);
1144 }
1145
1146 static void handle_for_loops(struct expression *expr, char *state_name, struct smatch_state *false_state)
1147 {
1148 sval_t sval;
1149 char *iter_name, *cap_name;
1150 struct symbol *iter_sym, *cap_sym;
1151 struct compare_data *data;
1152
1153 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1154 return;
1155
1156 if (!__cur_stmt || !__prev_stmt)
1157 return;
1158 if (__cur_stmt->type != STMT_ITERATOR)
1159 return;
1160 if (__cur_stmt->iterator_pre_condition != expr)
1161 return;
1162
1163 /* literals are handled in smatch_extra.c */
1164 if (get_value(expr->right, &sval))
1165 return;
1166
1167 /* First time checking the condition */
1168 if (__prev_stmt == __cur_stmt->iterator_pre_statement) {
1169 if (!get_implied_value(expr->left, &sval) ||
1170 sval.value != 0)
1171 return;
1172
1173 iter_name = expr_to_var_sym(expr->left, &iter_sym);
1174 cap_name = expr_to_var_sym(expr->right, &cap_sym);
1175 if (!iter_name || !cap_name || !iter_sym || !cap_sym) {
1176 free_string(iter_name);
1177 free_string(cap_name);
1178 return;
1179 }
1180
1181 set_state(inc_dec_id, iter_name, iter_sym, &start);
1182 store_link(inc_dec_link_id, cap_name, cap_sym, iter_name, iter_sym);
1183
1184 free_string(iter_name);
1185 free_string(cap_name);
1186 return;
1187 }
1188
1189 /* Second time checking the condtion */
1190 if (__prev_stmt != __cur_stmt->iterator_post_statement)
1191 return;
1192
1193 if (get_state_chunk(inc_dec_id, expr->left) != &incremented)
1194 return;
1195
1196 data = false_state->data;
1197 false_state = alloc_compare_state(
1198 data->left, data->left_var, data->left_vsl,
1199 SPECIAL_EQUAL,
1200 data->right, data->right_var, data->right_vsl);
1201
1202 set_true_false_states(compare_id, state_name, NULL, NULL, false_state);
1203 }
1204
1205 static int is_plus_one(struct expression *expr)
1206 {
1207 sval_t sval;
1208
1209 if (expr->type != EXPR_BINOP || expr->op != '+')
1210 return 0;
1211 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1212 return 0;
1213 return 1;
1214 }
1215
1216 static int is_minus_one(struct expression *expr)
1217 {
1218 sval_t sval;
1219
1220 if (expr->type != EXPR_BINOP || expr->op != '-')
1221 return 0;
1222 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1223 return 0;
1224 return 1;
1225 }
1226
1227 static void move_plus_to_minus_helper(struct expression **left_p, struct expression **right_p)
1228 {
1229 struct expression *left = *left_p;
1230 struct expression *right = *right_p;
1231
1232 /*
1233 * These two are basically equivalent: "foo + 1 != bar" and
1234 * "foo != bar - 1". There are issues with signedness and integer
1235 * overflows. There are also issues with type as well. But let's
1236 * pretend we can ignore all that stuff for now.
1237 *
1238 */
1239
1240 if (!is_plus_one(left))
1241 return;
1242
1243 *left_p = left->left;
1244 *right_p = binop_expression(right, '-', left->right);
1245 }
1246
1247 static void move_plus_to_minus(struct expression **left_p, struct expression **right_p)
1248 {
1249 if (is_plus_one(*left_p) && is_plus_one(*right_p))
1250 return;
1251
1252 move_plus_to_minus_helper(left_p, right_p);
1253 move_plus_to_minus_helper(right_p, left_p);
1254 }
1255
1256 static void handle_comparison(struct expression *left_expr, int op, struct expression *right_expr, char **_state_name, struct smatch_state **_false_state)
1257 {
1258 char *left = NULL;
1259 char *right = NULL;
1260 struct symbol *left_sym, *right_sym;
1261 struct var_sym_list *left_vsl = NULL;
1262 struct var_sym_list *right_vsl = NULL;
1263 int false_op;
1264 int orig_comparison;
1265 struct smatch_state *true_state, *false_state;
1266 static char state_name[256];
1267 struct stree *pre_stree;
1268 sval_t sval;
1269
1270 if (!left_expr || !right_expr)
1271 return;
1272
1273 left_expr = strip_parens(left_expr);
1274 right_expr = strip_parens(right_expr);
1275
1276 while (left_expr->type == EXPR_ASSIGNMENT)
1277 left_expr = strip_parens(left_expr->left);
1278 while (right_expr->type == EXPR_ASSIGNMENT)
1279 right_expr = strip_parens(right_expr->left);
1280
1281 false_op = negate_comparison(op);
1282
1283 move_plus_to_minus(&left_expr, &right_expr);
1284
1285 if (op == SPECIAL_UNSIGNED_LT &&
1286 get_implied_value(left_expr, &sval) &&
1287 sval.value == 0)
1288 false_op = SPECIAL_EQUAL;
1289
1290 if (op == SPECIAL_UNSIGNED_GT &&
1291 get_implied_value(right_expr, &sval) &&
1292 sval.value == 0)
1293 false_op = SPECIAL_EQUAL;
1294
1295 left = chunk_to_var_sym(left_expr, &left_sym);
1296 if (!left)
1297 goto free;
1298 if (left_sym)
1299 add_var_sym(&left_vsl, left, left_sym);
1300 else
1301 left_vsl = expr_to_vsl(left_expr);
1302 right = chunk_to_var_sym(right_expr, &right_sym);
1303 if (!right)
1304 goto free;
1305 if (right_sym)
1306 add_var_sym(&right_vsl, right, right_sym);
1307 else
1308 right_vsl = expr_to_vsl(right_expr);
1309
1310 if (strcmp(left, right) > 0) {
1311 char *tmp_name = left;
1312 struct var_sym_list *tmp_vsl = left_vsl;
1313 struct expression *tmp_expr = left_expr;
1314
1315 left = right;
1316 left_vsl = right_vsl;
1317 left_expr = right_expr;
1318 right = tmp_name;
1319 right_vsl = tmp_vsl;
1320 right_expr = tmp_expr;
1321 op = flip_comparison(op);
1322 false_op = flip_comparison(false_op);
1323 }
1324
1325 orig_comparison = get_comparison(left_expr, right_expr);
1326 op = comparison_intersection(orig_comparison, op);
1327 false_op = comparison_intersection(orig_comparison, false_op);
1328
1329 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
1330 true_state = alloc_compare_state(
1331 left_expr, left, left_vsl,
1332 op,
1333 right_expr, right, right_vsl);
1334 false_state = alloc_compare_state(
1335 left_expr, left, left_vsl,
1336 false_op,
1337 right_expr, right, right_vsl);
1338
1339 pre_stree = clone_stree(__get_cur_stree());
1340 update_tf_data(pre_stree, left_expr, left, left_vsl, right_expr, right, right_vsl, op, false_op);
1341 free_stree(&pre_stree);
1342
1343 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
1344 __compare_param_limit_hook(left_expr, right_expr, state_name, true_state, false_state);
1345 save_link(left_expr, state_name);
1346 save_link(right_expr, state_name);
1347
1348 if (_false_state)
1349 *_false_state = false_state;
1350 if (_state_name)
1351 *_state_name = state_name;
1352 free:
1353 free_string(left);
1354 free_string(right);
1355 }
1356
1357 void __comparison_match_condition(struct expression *expr)
1358 {
1359 struct expression *left, *right, *new_left, *new_right, *tmp;
1360 struct smatch_state *false_state = NULL;
1361 char *state_name = NULL;
1362 int redo, count;
1363
1364 if (expr->type != EXPR_COMPARE)
1365 return;
1366
1367 handle_comparison(expr->left, expr->op, expr->right, &state_name, &false_state);
1368 if (false_state && state_name)
1369 handle_for_loops(expr, state_name, false_state);
1370
1371 left = strip_parens(expr->left);
1372 right = strip_parens(expr->right);
1373
1374 if (left->type == EXPR_BINOP && left->op == '+') {
1375 new_left = left->left;
1376 new_right = binop_expression(right, '-', left->right);
1377 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1378
1379 new_left = left->right;
1380 new_right = binop_expression(right, '-', left->left);
1381 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1382 }
1383
1384 redo = 0;
1385 left = strip_parens(expr->left);
1386 right = strip_parens(expr->right);
1387 if (get_last_expr_from_expression_stmt(expr->left)) {
1388 left = get_last_expr_from_expression_stmt(expr->left);
1389 redo = 1;
1390 }
1391 if (get_last_expr_from_expression_stmt(expr->right)) {
1392 right = get_last_expr_from_expression_stmt(expr->right);
1393 redo = 1;
1394 }
1395
1396 if (!redo)
1397 return;
1398
1399 count = 0;
1400 while ((tmp = get_assigned_expr(left))) {
1401 if (count++ > 3)
1402 break;
1403 left = strip_expr(tmp);
1404 }
1405 count = 0;
1406 while ((tmp = get_assigned_expr(right))) {
1407 if (count++ > 3)
1408 break;
1409 right = strip_expr(tmp);
1410 }
1411
1412 handle_comparison(left, expr->op, right, NULL, NULL);
1413 }
1414
1415 static void add_comparison_var_sym(
1416 struct expression *left_expr,
1417 const char *left_name, struct var_sym_list *left_vsl,
1418 int comparison,
1419 struct expression *right_expr,
1420 const char *right_name, struct var_sym_list *right_vsl)
1421 {
1422 struct smatch_state *state;
1423 struct var_sym *vs;
1424 char state_name[256];
1425
1426 if (strcmp(left_name, right_name) > 0) {
1427 struct expression *tmp_expr = left_expr;
1428 const char *tmp_name = left_name;
1429 struct var_sym_list *tmp_vsl = left_vsl;
1430
1431 left_expr = right_expr;
1432 left_name = right_name;
1433 left_vsl = right_vsl;
1434 right_expr = tmp_expr;
1435 right_name = tmp_name;
1436 right_vsl = tmp_vsl;
1437 comparison = flip_comparison(comparison);
1438 }
1439 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1440 state = alloc_compare_state(
1441 left_expr, left_name, left_vsl,
1442 comparison,
1443 right_expr, right_name, right_vsl);
1444
1445 set_state(compare_id, state_name, NULL, state);
1446
1447 FOR_EACH_PTR(left_vsl, vs) {
1448 save_link_var_sym(vs->var, vs->sym, state_name);
1449 } END_FOR_EACH_PTR(vs);
1450 FOR_EACH_PTR(right_vsl, vs) {
1451 save_link_var_sym(vs->var, vs->sym, state_name);
1452 } END_FOR_EACH_PTR(vs);
1453 }
1454
1455 static void add_comparison(struct expression *left, int comparison, struct expression *right)
1456 {
1457 char *left_name = NULL;
1458 char *right_name = NULL;
1459 struct symbol *left_sym, *right_sym;
1460 struct var_sym_list *left_vsl, *right_vsl;
1461 struct smatch_state *state;
1462 char state_name[256];
1463
1464 left_name = chunk_to_var_sym(left, &left_sym);
1465 if (!left_name)
1466 goto free;
1467 left_vsl = expr_to_vsl(left);
1468 right_name = chunk_to_var_sym(right, &right_sym);
1469 if (!right_name)
1470 goto free;
1471 right_vsl = expr_to_vsl(right);
1472
1473 if (strcmp(left_name, right_name) > 0) {
1474 struct expression *tmp_expr = left;
1475 struct symbol *tmp_sym = left_sym;
1476 char *tmp_name = left_name;
1477 struct var_sym_list *tmp_vsl = left_vsl;
1478
1479 left = right;
1480 left_name = right_name;
1481 left_sym = right_sym;
1482 left_vsl = right_vsl;
1483 right = tmp_expr;
1484 right_name = tmp_name;
1485 right_sym = tmp_sym;
1486 right_vsl = tmp_vsl;
1487 comparison = flip_comparison(comparison);
1488 }
1489 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1490 state = alloc_compare_state(
1491 left, left_name, left_vsl,
1492 comparison,
1493 right, right_name, right_vsl);
1494
1495 set_state(compare_id, state_name, NULL, state);
1496 save_link(left, state_name);
1497 save_link(right, state_name);
1498
1499 free:
1500 free_string(left_name);
1501 free_string(right_name);
1502 }
1503
1504 static void match_assign_add(struct expression *expr)
1505 {
1506 struct expression *right;
1507 struct expression *r_left, *r_right;
1508 sval_t left_tmp, right_tmp;
1509
1510 right = strip_expr(expr->right);
1511 r_left = strip_expr(right->left);
1512 r_right = strip_expr(right->right);
1513
1514 get_absolute_min(r_left, &left_tmp);
1515 get_absolute_min(r_right, &right_tmp);
1516
1517 if (left_tmp.value > 0)
1518 add_comparison(expr->left, '>', r_right);
1519 else if (left_tmp.value == 0)
1520 add_comparison(expr->left, SPECIAL_GTE, r_right);
1521
1522 if (right_tmp.value > 0)
1523 add_comparison(expr->left, '>', r_left);
1524 else if (right_tmp.value == 0)
1525 add_comparison(expr->left, SPECIAL_GTE, r_left);
1526 }
1527
1528 static void match_assign_sub(struct expression *expr)
1529 {
1530 struct expression *right;
1531 struct expression *r_left, *r_right;
1532 int comparison;
1533 sval_t min;
1534
1535 right = strip_expr(expr->right);
1536 r_left = strip_expr(right->left);
1537 r_right = strip_expr(right->right);
1538
1539 if (get_absolute_min(r_right, &min) && sval_is_negative(min))
1540 return;
1541
1542 comparison = get_comparison(r_left, r_right);
1543
1544 switch (comparison) {
1545 case '>':
1546 case SPECIAL_GTE:
1547 if (implied_not_equal(r_right, 0))
1548 add_comparison(expr->left, '>', r_left);
1549 else
1550 add_comparison(expr->left, SPECIAL_GTE, r_left);
1551 return;
1552 }
1553 }
1554
1555 static void match_assign_divide(struct expression *expr)
1556 {
1557 struct expression *right;
1558 struct expression *r_left, *r_right;
1559 sval_t min;
1560
1561 right = strip_expr(expr->right);
1562 r_left = strip_expr(right->left);
1563 r_right = strip_expr(right->right);
1564 if (!get_implied_min(r_right, &min) || min.value <= 1)
1565 return;
1566
1567 add_comparison(expr->left, '<', r_left);
1568 }
1569
1570 static void match_binop_assign(struct expression *expr)
1571 {
1572 struct expression *right;
1573
1574 right = strip_expr(expr->right);
1575 if (right->op == '+')
1576 match_assign_add(expr);
1577 if (right->op == '-')
1578 match_assign_sub(expr);
1579 if (right->op == '/')
1580 match_assign_divide(expr);
1581 }
1582
1583 static void copy_comparisons(struct expression *left, struct expression *right)
1584 {
1585 struct string_list *links;
1586 struct smatch_state *state;
1587 struct compare_data *data;
1588 struct symbol *left_sym, *right_sym;
1589 char *left_var = NULL;
1590 char *right_var = NULL;
1591 struct var_sym_list *left_vsl;
1592 struct expression *expr;
1593 const char *var;
1594 struct var_sym_list *vsl;
1595 int comparison;
1596 char *tmp;
1597
1598 left_var = chunk_to_var_sym(left, &left_sym);
1599 if (!left_var)
1600 goto done;
1601 left_vsl = expr_to_vsl(left);
1602 right_var = chunk_to_var_sym(right, &right_sym);
1603 if (!right_var)
1604 goto done;
1605
1606 state = get_state(link_id, right_var, right_sym);
1607 if (!state)
1608 return;
1609 links = state->data;
1610
1611 FOR_EACH_PTR(links, tmp) {
1612 state = get_state(compare_id, tmp, NULL);
1613 if (!state || !state->data)
1614 continue;
1615 data = state->data;
1616 comparison = data->comparison;
1617 expr = data->right;
1618 var = data->right_var;
1619 vsl = data->right_vsl;
1620 if (strcmp(var, right_var) == 0) {
1621 expr = data->left;
1622 var = data->left_var;
1623 vsl = data->left_vsl;
1624 comparison = flip_comparison(comparison);
1625 }
1626 /* n = copy_from_user(dest, src, n); leads to n <= n which is nonsense */
1627 if (strcmp(left_var, var) == 0)
1628 continue;
1629 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1630 } END_FOR_EACH_PTR(tmp);
1631
1632 done:
1633 free_string(right_var);
1634 }
1635
1636 static void match_assign(struct expression *expr)
1637 {
1638 struct expression *right;
1639
1640 if (expr->op != '=')
1641 return;
1642 if (__in_fake_assign || outside_of_function())
1643 return;
1644
1645 if (is_struct(expr->left))
1646 return;
1647
1648 if (is_self_assign(expr))
1649 return;
1650
1651 copy_comparisons(expr->left, expr->right);
1652 add_comparison(expr->left, SPECIAL_EQUAL, expr->right);
1653
1654 right = strip_expr(expr->right);
1655 if (right->type == EXPR_BINOP)
1656 match_binop_assign(expr);
1657 }
1658
1659 int get_comparison_strings(const char *one, const char *two)
1660 {
1661 char buf[256];
1662 struct smatch_state *state;
1663 int invert = 0;
1664 int ret = 0;
1665
1666 if (!one || !two)
1667 return UNKNOWN_COMPARISON;
1668
1669 if (strcmp(one, two) == 0)
1670 return SPECIAL_EQUAL;
1671
1672 if (strcmp(one, two) > 0) {
1673 const char *tmp = one;
1674
1675 one = two;
1676 two = tmp;
1677 invert = 1;
1678 }
1679
1680 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1681 state = get_state(compare_id, buf, NULL);
1682 if (state)
1683 ret = state_to_comparison(state);
1684
1685 if (invert)
1686 ret = flip_comparison(ret);
1687
1688 return ret;
1689 }
1690
1691 static int get_comparison_helper(struct expression *a, struct expression *b, bool use_extra)
1692 {
1693 char *one = NULL;
1694 char *two = NULL;
1695 int ret = UNKNOWN_COMPARISON;
1696 int extra = UNKNOWN_COMPARISON;
1697
1698 if (a == UNKNOWN_COMPARISON ||
1699 b == UNKNOWN_COMPARISON)
1700 return UNKNOWN_COMPARISON;
1701
1702 a = strip_parens(a);
1703 b = strip_parens(b);
1704
1705 move_plus_to_minus(&a, &b);
1706
1707 one = chunk_to_var(a);
1708 if (!one)
1709 goto free;
1710 two = chunk_to_var(b);
1711 if (!two)
1712 goto free;
1713
1714 ret = get_comparison_strings(one, two);
1715 if (ret)
1716 goto free;
1717
1718 if (is_plus_one(a) || is_minus_one(a)) {
1719 free_string(one);
1720 one = chunk_to_var(a->left);
1721 ret = get_comparison_strings(one, two);
1722 } else if (is_plus_one(b) || is_minus_one(b)) {
1723 free_string(two);
1724 two = chunk_to_var(b->left);
1725 ret = get_comparison_strings(one, two);
1726 }
1727
1728 if (ret == UNKNOWN_COMPARISON)
1729 goto free;
1730
1731 if ((is_plus_one(a) || is_minus_one(b)) && ret == '<')
1732 ret = SPECIAL_LTE;
1733 else if ((is_minus_one(a) || is_plus_one(b)) && ret == '>')
1734 ret = SPECIAL_GTE;
1735 else
1736 ret = UNKNOWN_COMPARISON;
1737
1738 free:
1739 free_string(one);
1740 free_string(two);
1741
1742 extra = comparison_from_extra(a, b);
1743 return comparison_intersection(ret, extra);
1744 }
1745
1746 int get_comparison(struct expression *a, struct expression *b)
1747 {
1748 return get_comparison_helper(a, b, true);
1749 }
1750
1751 int get_comparison_no_extra(struct expression *a, struct expression *b)
1752 {
1753 return get_comparison_helper(a, b, false);
1754 }
1755
1756 int possible_comparison(struct expression *a, int comparison, struct expression *b)
1757 {
1758 char *one = NULL;
1759 char *two = NULL;
1760 int ret = 0;
1761 char buf[256];
1762 struct sm_state *sm;
1763 int saved;
1764
1765 one = chunk_to_var(a);
1766 if (!one)
1767 goto free;
1768 two = chunk_to_var(b);
1769 if (!two)
1770 goto free;
1771
1772
1773 if (strcmp(one, two) == 0 && comparison == SPECIAL_EQUAL) {
1774 ret = 1;
1775 goto free;
1776 }
1777
1778 if (strcmp(one, two) > 0) {
1779 char *tmp = one;
1780
1781 one = two;
1782 two = tmp;
1783 comparison = flip_comparison(comparison);
1784 }
1785
1786 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1787 sm = get_sm_state(compare_id, buf, NULL);
1788 if (!sm)
1789 goto free;
1790
1791 FOR_EACH_PTR(sm->possible, sm) {
1792 if (!sm->state->data)
1793 continue;
1794 saved = ((struct compare_data *)sm->state->data)->comparison;
1795 if (saved == comparison)
1796 ret = 1;
1797 if (comparison == SPECIAL_EQUAL &&
1798 (saved == SPECIAL_LTE ||
1799 saved == SPECIAL_GTE ||
1800 saved == SPECIAL_UNSIGNED_LTE ||
1801 saved == SPECIAL_UNSIGNED_GTE))
1802 ret = 1;
1803 if (ret == 1)
1804 goto free;
1805 } END_FOR_EACH_PTR(sm);
1806
1807 return ret;
1808 free:
1809 free_string(one);
1810 free_string(two);
1811 return ret;
1812 }
1813
1814 struct state_list *get_all_comparisons(struct expression *expr)
1815 {
1816 struct smatch_state *state;
1817 struct string_list *links;
1818 struct state_list *ret = NULL;
1819 struct sm_state *sm;
1820 char *tmp;
1821
1822 state = get_state_chunk(link_id, expr);
1823 if (!state)
1824 return NULL;
1825 links = state->data;
1826
1827 FOR_EACH_PTR(links, tmp) {
1828 sm = get_sm_state(compare_id, tmp, NULL);
1829 if (!sm)
1830 continue;
1831 // FIXME have to compare name with vsl
1832 add_ptr_list(&ret, sm);
1833 } END_FOR_EACH_PTR(tmp);
1834
1835 return ret;
1836 }
1837
1838 struct state_list *get_all_possible_equal_comparisons(struct expression *expr)
1839 {
1840 struct smatch_state *state;
1841 struct string_list *links;
1842 struct state_list *ret = NULL;
1843 struct sm_state *sm;
1844 char *tmp;
1845
1846 state = get_state_chunk(link_id, expr);
1847 if (!state)
1848 return NULL;
1849 links = state->data;
1850
1851 FOR_EACH_PTR(links, tmp) {
1852 sm = get_sm_state(compare_id, tmp, NULL);
1853 if (!sm)
1854 continue;
1855 if (!strchr(sm->state->name, '='))
1856 continue;
1857 if (strcmp(sm->state->name, "!=") == 0)
1858 continue;
1859 add_ptr_list(&ret, sm);
1860 } END_FOR_EACH_PTR(tmp);
1861
1862 return ret;
1863 }
1864
1865 struct state_list *get_all_possible_not_equal_comparisons(struct expression *expr)
1866 {
1867 struct smatch_state *state;
1868 struct string_list *links;
1869 struct state_list *ret = NULL;
1870 struct sm_state *sm;
1871 struct sm_state *possible;
1872 char *link;
1873
1874 return NULL;
1875
1876 state = get_state_chunk(link_id, expr);
1877 if (!state)
1878 return NULL;
1879 links = state->data;
1880
1881 FOR_EACH_PTR(links, link) {
1882 sm = get_sm_state(compare_id, link, NULL);
1883 if (!sm)
1884 continue;
1885 FOR_EACH_PTR(sm->possible, possible) {
1886 if (strcmp(possible->state->name, "!=") != 0)
1887 continue;
1888 add_ptr_list(&ret, sm);
1889 break;
1890 } END_FOR_EACH_PTR(link);
1891 } END_FOR_EACH_PTR(link);
1892
1893 return ret;
1894 }
1895
1896 static void update_links_from_call(struct expression *left,
1897 int left_compare,
1898 struct expression *right)
1899 {
1900 struct string_list *links;
1901 struct smatch_state *state;
1902 struct compare_data *data;
1903 struct symbol *left_sym, *right_sym;
1904 char *left_var = NULL;
1905 char *right_var = NULL;
1906 struct var_sym_list *left_vsl;
1907 struct expression *expr;
1908 const char *var;
1909 struct var_sym_list *vsl;
1910 int comparison;
1911 char *tmp;
1912
1913 left_var = chunk_to_var_sym(left, &left_sym);
1914 if (!left_var)
1915 goto done;
1916 left_vsl = expr_to_vsl(left);
1917 right_var = chunk_to_var_sym(right, &right_sym);
1918 if (!right_var)
1919 goto done;
1920
1921 state = get_state(link_id, right_var, right_sym);
1922 if (!state)
1923 return;
1924 links = state->data;
1925
1926 FOR_EACH_PTR(links, tmp) {
1927 state = get_state(compare_id, tmp, NULL);
1928 if (!state || !state->data)
1929 continue;
1930 data = state->data;
1931 comparison = data->comparison;
1932 expr = data->right;
1933 var = data->right_var;
1934 vsl = data->right_vsl;
1935 if (strcmp(var, right_var) == 0) {
1936 expr = data->left;
1937 var = data->left_var;
1938 vsl = data->left_vsl;
1939 comparison = flip_comparison(comparison);
1940 }
1941 comparison = combine_comparisons(left_compare, comparison);
1942 if (!comparison)
1943 continue;
1944 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1945 } END_FOR_EACH_PTR(tmp);
1946
1947 done:
1948 free_string(right_var);
1949 }
1950
1951 void __add_return_comparison(struct expression *call, const char *range)
1952 {
1953 struct expression *arg;
1954 int comparison;
1955 char buf[16];
1956
1957 if (!str_to_comparison_arg(range, call, &comparison, &arg))
1958 return;
1959 snprintf(buf, sizeof(buf), "%s", show_comparison(comparison));
1960 update_links_from_call(call, comparison, arg);
1961 add_comparison(call, comparison, arg);
1962 }
1963
1964 void __add_comparison_info(struct expression *expr, struct expression *call, const char *range)
1965 {
1966 copy_comparisons(expr, call);
1967 }
1968
1969 static char *get_mask_comparison(struct expression *expr, int ignore)
1970 {
1971 struct expression *tmp, *right;
1972 int count, param;
1973 char buf[256];
1974
1975 /* The return value for "return foo & param;" is <= param */
1976
1977 count = 0;
1978 while ((tmp = get_assigned_expr(expr))) {
1979 expr = strip_expr(tmp);
1980 if (count++ > 4)
1981 break;
1982 }
1983
1984 if (expr->type != EXPR_BINOP || expr->op != '&')
1985 return NULL;
1986
1987 right = strip_expr(expr->right);
1988 param = get_param_num(right);
1989 if (param < 0 || param == ignore)
1990 return NULL;
1991
1992 snprintf(buf, sizeof(buf), "[<=$%d]", param);
1993 return alloc_sname(buf);
1994 }
1995
1996 static char *range_comparison_to_param_helper(struct expression *expr, char starts_with, int ignore)
1997 {
1998 struct symbol *param;
1999 char *var = NULL;
2000 char buf[256];
2001 char *ret_str = NULL;
2002 int compare;
2003 int i;
2004
2005 if (!expr)
2006 return NULL;
2007
2008 var = chunk_to_var(expr);
2009 if (!var)
2010 goto try_mask;
2011
2012 i = -1;
2013 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2014 i++;
2015 if (i == ignore)
2016 continue;
2017 if (!param->ident)
2018 continue;
2019 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2020 compare = get_comparison_strings(var, buf);
2021 if (compare == UNKNOWN_COMPARISON ||
2022 compare == IMPOSSIBLE_COMPARISON)
2023 continue;
2024 if (show_comparison(compare)[0] != starts_with)
2025 continue;
2026 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2027 ret_str = alloc_sname(buf);
2028 break;
2029 } END_FOR_EACH_PTR(param);
2030
2031 free_string(var);
2032 if (!ret_str)
2033 goto try_mask;
2034
2035 return ret_str;
2036
2037 try_mask:
2038 if (starts_with == '<')
2039 ret_str = get_mask_comparison(expr, ignore);
2040 return ret_str;
2041 }
2042
2043 char *name_sym_to_param_comparison(const char *name, struct symbol *sym)
2044 {
2045 struct symbol *param;
2046 char buf[256];
2047 int compare;
2048 int i;
2049
2050 i = -1;
2051 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2052 i++;
2053 if (!param->ident)
2054 continue;
2055 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2056 compare = get_comparison_strings(name, buf);
2057 if (compare == UNKNOWN_COMPARISON ||
2058 compare == IMPOSSIBLE_COMPARISON)
2059 continue;
2060 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2061 return alloc_sname(buf);
2062 } END_FOR_EACH_PTR(param);
2063
2064 return NULL;
2065 }
2066
2067 char *expr_equal_to_param(struct expression *expr, int ignore)
2068 {
2069 return range_comparison_to_param_helper(expr, '=', ignore);
2070 }
2071
2072 char *expr_lte_to_param(struct expression *expr, int ignore)
2073 {
2074 return range_comparison_to_param_helper(expr, '<', ignore);
2075 }
2076
2077 char *expr_param_comparison(struct expression *expr, int ignore)
2078 {
2079 struct symbol *param;
2080 char *var = NULL;
2081 char buf[256];
2082 char *ret_str = NULL;
2083 int compare;
2084 int i;
2085
2086 var = chunk_to_var(expr);
2087 if (!var)
2088 goto free;
2089
2090 i = -1;
2091 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2092 i++;
2093 if (i == ignore)
2094 continue;
2095 if (!param->ident)
2096 continue;
2097 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2098 compare = get_comparison_strings(var, buf);
2099 if (!compare)
2100 continue;
2101 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2102 ret_str = alloc_sname(buf);
2103 break;
2104 } END_FOR_EACH_PTR(param);
2105
2106 free:
2107 free_string(var);
2108 return ret_str;
2109 }
2110
2111 char *get_printed_param_name(struct expression *call, const char *param_name, struct symbol *param_sym)
2112 {
2113 struct expression *arg;
2114 char *name;
2115 struct symbol *sym;
2116 static char buf[256];
2117 int len;
2118 int i;
2119
2120 i = -1;
2121 FOR_EACH_PTR(call->args, arg) {
2122 i++;
2123
2124 name = expr_to_var_sym(arg, &sym);
2125 if (!name || !sym)
2126 continue;
2127 if (sym != param_sym)
2128 continue;
2129
2130 len = strlen(name);
2131 if (strncmp(name, param_name, len) != 0)
2132 continue;
2133 if (param_name[len] == '\0') {
2134 snprintf(buf, sizeof(buf), "$%d", i);
2135 return buf;
2136 }
2137 if (param_name[len] != '-')
2138 continue;
2139 snprintf(buf, sizeof(buf), "$%d%s", i, param_name + len);
2140 return buf;
2141 } END_FOR_EACH_PTR(arg);
2142
2143 return NULL;
2144 }
2145
2146 static void match_call_info(struct expression *expr)
2147 {
2148 struct expression *arg;
2149 struct smatch_state *state;
2150 struct sm_state *sm;
2151 struct compare_data *data;
2152 int comparison;
2153 struct string_list *links;
2154 char *arg_name;
2155 const char *right_name;
2156 char *link;
2157 char info_buf[256];
2158 int i;
2159
2160 i = -1;
2161 FOR_EACH_PTR(expr->args, arg) {
2162 i++;
2163
2164 state = get_state_chunk(link_id, arg);
2165 if (!state)
2166 continue;
2167
2168 links = state->data;
2169 FOR_EACH_PTR(links, link) {
2170 struct var_sym_list *right_vsl;
2171 struct var_sym *right_vs;
2172
2173
2174 if (strstr(link, " orig"))
2175 continue;
2176 sm = get_sm_state(compare_id, link, NULL);
2177 if (!sm)
2178 continue;
2179 data = sm->state->data;
2180 if (!data ||
2181 data->comparison == UNKNOWN_COMPARISON ||
2182 data->comparison == IMPOSSIBLE_COMPARISON)
2183 continue;
2184 arg_name = expr_to_var(arg);
2185 if (!arg_name)
2186 continue;
2187
2188 right_vsl = NULL;
2189 if (strcmp(data->left_var, arg_name) == 0) {
2190 comparison = data->comparison;
2191 right_name = data->right_var;
2192 right_vsl = data->right_vsl;
2193 } else if (strcmp(data->right_var, arg_name) == 0) {
2194 comparison = flip_comparison(data->comparison);
2195 right_name = data->left_var;
2196 right_vsl = data->left_vsl;
2197 }
2198 if (!right_vsl || ptr_list_size((struct ptr_list *)right_vsl) != 1)
2199 goto free;
2200
2201 right_vs = first_ptr_list((struct ptr_list *)right_vsl);
2202 if (strcmp(right_vs->var, right_name) != 0)
2203 goto free;
2204 right_name = get_printed_param_name(expr, right_vs->var, right_vs->sym);
2205 if (!right_name)
2206 goto free;
2207 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(comparison), right_name);
2208 sql_insert_caller_info(expr, PARAM_COMPARE, i, "$", info_buf);
2209
2210 free:
2211 free_string(arg_name);
2212 } END_FOR_EACH_PTR(link);
2213 } END_FOR_EACH_PTR(arg);
2214 }
2215
2216 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *link_sm)
2217 {
2218 struct sm_state *compare_sm;
2219 struct string_list *links;
2220 char *link;
2221 struct compare_data *data;
2222 struct var_sym *left, *right;
2223 static char info_buf[256];
2224 const char *right_name;
2225
2226 if (strstr(printed_name, " orig"))
2227 return;
2228
2229 links = link_sm->state->data;
2230 FOR_EACH_PTR(links, link) {
2231 compare_sm = get_sm_state(compare_id, link, NULL);
2232 if (!compare_sm)
2233 continue;
2234 data = compare_sm->state->data;
2235 if (!data || !data->comparison)
2236 continue;
2237
2238 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2239 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2240 continue;
2241 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2242 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2243 if (left->sym == right->sym &&
2244 strcmp(left->var, right->var) == 0)
2245 continue;
2246 /*
2247 * Both parameters link to this comparison so only
2248 * record the first one.
2249 */
2250 if (left->sym != link_sm->sym ||
2251 strcmp(left->var, link_sm->name) != 0)
2252 continue;
2253
2254 right_name = get_printed_param_name(call, right->var, right->sym);
2255 if (!right_name)
2256 continue;
2257 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_name);
2258 sql_insert_caller_info(call, PARAM_COMPARE, param, printed_name, info_buf);
2259 } END_FOR_EACH_PTR(link);
2260 }
2261
2262 static void print_return_value_comparison(int return_id, char *return_ranges, struct expression *expr)
2263 {
2264 char *name;
2265 const char *tmp_name;
2266 struct symbol *sym;
2267 int param;
2268 char info_buf[256];
2269
2270 /*
2271 * TODO: This only prints == comparisons. That's probably the most
2272 * useful comparison because == max has lots of implications. But it
2273 * would be good to capture the rest as well.
2274 *
2275 * This information is already in the DB but it's in the parameter math
2276 * bits and it's awkward to use it. This is is the simpler, possibly
2277 * cleaner way, but not necessarily the best, I don't know.
2278 */
2279
2280 if (!expr)
2281 return;
2282 name = expr_to_var_sym(expr, &sym);
2283 if (!name || !sym)
2284 goto free;
2285
2286 param = get_param_num_from_sym(sym);
2287 if (param < 0)
2288 goto free;
2289 if (param_was_set_var_sym(name, sym))
2290 goto free;
2291
2292 tmp_name = get_param_name_var_sym(name, sym);
2293 if (!tmp_name)
2294 goto free;
2295
2296 snprintf(info_buf, sizeof(info_buf), "== $%d%s", param, tmp_name + 1);
2297 sql_insert_return_states(return_id, return_ranges,
2298 PARAM_COMPARE, -1, "$", info_buf);
2299 free:
2300 free_string(name);
2301 }
2302
2303 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
2304 {
2305 struct sm_state *tmp;
2306 struct string_list *links;
2307 char *link;
2308 struct sm_state *sm;
2309 struct compare_data *data;
2310 struct var_sym *left, *right;
2311 int left_param, right_param;
2312 char left_buf[256];
2313 char right_buf[256];
2314 char info_buf[258];
2315 const char *tmp_name;
2316
2317 print_return_value_comparison(return_id, return_ranges, expr);
2318
2319 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
2320 if (get_param_num_from_sym(tmp->sym) < 0)
2321 continue;
2322 links = tmp->state->data;
2323 FOR_EACH_PTR(links, link) {
2324 sm = get_sm_state(compare_id, link, NULL);
2325 if (!sm)
2326 continue;
2327 data = sm->state->data;
2328 if (!data ||
2329 data->comparison == UNKNOWN_COMPARISON ||
2330 data->comparison == IMPOSSIBLE_COMPARISON)
2331 continue;
2332 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2333 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2334 continue;
2335 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2336 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2337 if (left->sym == right->sym &&
2338 strcmp(left->var, right->var) == 0)
2339 continue;
2340 /*
2341 * Both parameters link to this comparison so only
2342 * record the first one.
2343 */
2344 if (left->sym != tmp->sym ||
2345 strcmp(left->var, tmp->name) != 0)
2346 continue;
2347
2348 if (strstr(right->var, " orig"))
2349 continue;
2350
2351 left_param = get_param_num_from_sym(left->sym);
2352 right_param = get_param_num_from_sym(right->sym);
2353 if (left_param < 0 || right_param < 0)
2354 continue;
2355
2356 tmp_name = get_param_name_var_sym(left->var, left->sym);
2357 if (!tmp_name)
2358 continue;
2359 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
2360
2361 tmp_name = get_param_name_var_sym(right->var, right->sym);
2362 if (!tmp_name || tmp_name[0] != '$')
2363 continue;
2364 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
2365
2366 /*
2367 * FIXME: this should reject $ type variables (as
2368 * opposed to $->foo type). Those should come from
2369 * smatch_param_compare_limit.c.
2370 */
2371
2372 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_buf);
2373 sql_insert_return_states(return_id, return_ranges,
2374 PARAM_COMPARE, left_param, left_buf, info_buf);
2375 } END_FOR_EACH_PTR(link);
2376
2377 } END_FOR_EACH_SM(tmp);
2378 }
2379
2380 static int parse_comparison(char **value, int *op)
2381 {
2382
2383 *op = **value;
2384
2385 switch (*op) {
2386 case '<':
2387 (*value)++;
2388 if (**value == '=') {
2389 (*value)++;
2390 *op = SPECIAL_LTE;
2391 }
2392 break;
2393 case '=':
2394 (*value)++;
2395 (*value)++;
2396 *op = SPECIAL_EQUAL;
2397 break;
2398 case '!':
2399 (*value)++;
2400 (*value)++;
2401 *op = SPECIAL_NOTEQUAL;
2402 break;
2403 case '>':
2404 (*value)++;
2405 if (**value == '=') {
2406 (*value)++;
2407 *op = SPECIAL_GTE;
2408 }
2409 break;
2410 default:
2411 return 0;
2412 }
2413
2414 if (**value != ' ') {
2415 sm_perror("parsing comparison. %s", *value);
2416 return 0;
2417 }
2418
2419 (*value)++;
2420 return 1;
2421 }
2422
2423 static int split_op_param_key(char *value, int *op, int *param, char **key)
2424 {
2425 static char buf[256];
2426 char *p;
2427
2428 if (!parse_comparison(&value, op))
2429 return 0;
2430
2431 snprintf(buf, sizeof(buf), "%s", value);
2432
2433 p = buf;
2434 if (*p++ != '$')
2435 return 0;
2436
2437 *param = atoi(p);
2438 if (*param < 0 || *param > 99)
2439 return 0;
2440 p++;
2441 if (*param > 9)
2442 p++;
2443 p--;
2444 *p = '$';
2445 *key = p;
2446
2447 return 1;
2448 }
2449
2450 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
2451 {
2452 struct expression *left_arg, *right_arg;
2453 char *left_name = NULL;
2454 struct symbol *left_sym;
2455 char *right_name = NULL;
2456 struct symbol *right_sym;
2457 int op;
2458 int right_param;
2459 char *right_key;
2460 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
2461
2462 if (left_param == -1) {
2463 if (expr->type != EXPR_ASSIGNMENT)
2464 return;
2465 left_arg = strip_expr(expr->left);
2466
2467 while (expr->type == EXPR_ASSIGNMENT)
2468 expr = strip_expr(expr->right);
2469 if (expr->type != EXPR_CALL)
2470 return;
2471 } else {
2472 while (expr->type == EXPR_ASSIGNMENT)
2473 expr = strip_expr(expr->right);
2474 if (expr->type != EXPR_CALL)
2475 return;
2476
2477 left_arg = get_argument_from_call_expr(expr->args, left_param);
2478 if (!left_arg)
2479 return;
2480 }
2481
2482 if (!split_op_param_key(value, &op, &right_param, &right_key))
2483 return;
2484
2485 right_arg = get_argument_from_call_expr(expr->args, right_param);
2486 if (!right_arg)
2487 return;
2488
2489 left_name = get_variable_from_key(left_arg, key, &left_sym);
2490 if (!left_name || !left_sym)
2491 goto free;
2492
2493 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2494 if (!right_name || !right_sym)
2495 goto free;
2496
2497 add_var_sym(&left_vsl, left_name, left_sym);
2498 add_var_sym(&right_vsl, right_name, right_sym);
2499
2500 add_comparison_var_sym(NULL, left_name, left_vsl, op, NULL, right_name, right_vsl);
2501
2502 free:
2503 free_string(left_name);
2504 free_string(right_name);
2505 }
2506
2507 int param_compare_limit_is_impossible(struct expression *expr, int left_param, char *left_key, char *value)
2508 {
2509 struct smatch_state *state;
2510 char *left_name = NULL;
2511 char *right_name = NULL;
2512 struct symbol *left_sym, *right_sym;
2513 struct expression *left_arg, *right_arg;
2514 int op, state_op;
2515 int right_param;
2516 char *right_key;
2517 int ret = 0;
2518 char buf[256];
2519
2520 while (expr->type == EXPR_ASSIGNMENT)
2521 expr = strip_expr(expr->right);
2522 if (expr->type != EXPR_CALL)
2523 return 0;
2524
2525 if (!split_op_param_key(value, &op, &right_param, &right_key))
2526 return 0;
2527
2528 left_arg = get_argument_from_call_expr(expr->args, left_param);
2529 if (!left_arg)
2530 return 0;
2531
2532 right_arg = get_argument_from_call_expr(expr->args, right_param);
2533 if (!right_arg)
2534 return 0;
2535
2536 left_name = get_variable_from_key(left_arg, left_key, &left_sym);
2537 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2538 if (!left_name || !right_name)
2539 goto free;
2540
2541 snprintf(buf, sizeof(buf), "%s vs %s", left_name, right_name);
2542 state = get_state(compare_id, buf, NULL);
2543 if (!state)
2544 goto free;
2545 state_op = state_to_comparison(state);
2546 if (!state_op)
2547 goto free;
2548
2549 if (!comparison_intersection(remove_unsigned_from_comparison(state_op), op))
2550 ret = 1;
2551 free:
2552 free_string(left_name);
2553 free_string(right_name);
2554 return ret;
2555 }
2556
2557 int impossibly_high_comparison(struct expression *expr)
2558 {
2559 struct smatch_state *link_state;
2560 struct sm_state *sm;
2561 struct string_list *links;
2562 char *link;
2563 struct compare_data *data;
2564
2565 link_state = get_state_expr(link_id, expr);
2566 if (!link_state) {
2567 if (expr->type == EXPR_BINOP &&
2568 (impossibly_high_comparison(expr->left) ||
2569 impossibly_high_comparison(expr->right)))
2570 return 1;
2571 return 0;
2572 }
2573
2574 links = link_state->data;
2575 FOR_EACH_PTR(links, link) {
2576 sm = get_sm_state(compare_id, link, NULL);
2577 if (!sm)
2578 continue;
2579 data = sm->state->data;
2580 if (!data)
2581 continue;
2582 if (!possibly_true(data->left, data->comparison, data->right))
2583 return 1;
2584 } END_FOR_EACH_PTR(link);
2585
2586 return 0;
2587 }
2588
2589 static void free_data(struct symbol *sym)
2590 {
2591 if (__inline_fn)
2592 return;
2593 clear_compare_data_alloc();
2594 }
2595
2596 void register_comparison(int id)
2597 {
2598 compare_id = id;
2599 set_dynamic_states(compare_id);
2600 add_hook(&save_start_states, AFTER_DEF_HOOK);
2601 add_unmatched_state_hook(compare_id, unmatched_comparison);
2602 add_pre_merge_hook(compare_id, &pre_merge_hook);
2603 add_merge_hook(compare_id, &merge_compare_states);
2604 add_hook(&free_data, AFTER_FUNC_HOOK);
2605 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2606 add_split_return_callback(&print_return_comparison);
2607
2608 select_return_states_hook(PARAM_COMPARE, &db_return_comparison);
2609 add_hook(&match_preop, OP_HOOK);
2610 }
2611
2612 void register_comparison_late(int id)
2613 {
2614 add_hook(&match_assign, ASSIGNMENT_HOOK);
2615 }
2616
2617 void register_comparison_links(int id)
2618 {
2619 link_id = id;
2620 db_ignore_states(link_id);
2621 set_dynamic_states(link_id);
2622 add_merge_hook(link_id, &merge_links);
2623 add_modification_hook(link_id, &match_modify);
2624 add_modification_hook_late(link_id, match_inc_dec);
2625
2626 add_member_info_callback(link_id, struct_member_callback);
2627 }
2628
2629 void register_comparison_inc_dec(int id)
2630 {
2631 inc_dec_id = id;
2632 add_modification_hook_late(inc_dec_id, &iter_modify);
2633 }
2634
2635 void register_comparison_inc_dec_links(int id)
2636 {
2637 inc_dec_link_id = id;
2638 set_dynamic_states(inc_dec_link_id);
2639 set_up_link_functions(inc_dec_id, inc_dec_link_id);
2640 }
2641
2642 static void filter_by_sm(struct sm_state *sm, int op,
2643 struct state_list **true_stack,
2644 struct state_list **false_stack)
2645 {
2646 struct compare_data *data;
2647 int is_true = 0;
2648 int is_false = 0;
2649
2650 if (!sm)
2651 return;
2652 data = sm->state->data;
2653 if (!data || data->comparison == UNKNOWN_COMPARISON)
2654 goto split;
2655 if (data->comparison == IMPOSSIBLE_COMPARISON)
2656 return;
2657
2658 /*
2659 * We want to check that "data->comparison" is totally inside "op". So
2660 * if data->comparison is < and op is <= then that's true. Or if
2661 * data->comparison is == and op is <= then that's true. But if
2662 * data->comparison is <= and op is < than that's neither true nor
2663 * false.
2664 */
2665 if (data->comparison == comparison_intersection(data->comparison, op))
2666 is_true = 1;
2667 if (data->comparison == comparison_intersection(data->comparison, negate_comparison(op)))
2668 is_false = 1;
2669
2670 if (debug_implied()) {
2671 sm_msg("%s: %s: op = '%s' negated '%s'. true_intersect = '%s' false_insersect = '%s' sm = '%s'",
2672 __func__,
2673 sm->state->name,
2674 alloc_sname(show_comparison(op)),
2675 alloc_sname(show_comparison(negate_comparison(op))),
2676 alloc_sname(show_comparison(comparison_intersection(data->comparison, op))),
2677 alloc_sname(show_comparison(comparison_intersection(data->comparison, negate_comparison(op)))),
2678 show_sm(sm));
2679 }
2680
2681 if (is_true)
2682 add_ptr_list(true_stack, sm);
2683 if (is_false)
2684 add_ptr_list(false_stack, sm);
2685 split:
2686 filter_by_sm(sm->left, op, true_stack, false_stack);
2687 filter_by_sm(sm->right, op, true_stack, false_stack);
2688 }
2689
2690 struct sm_state *comparison_implication_hook(struct expression *expr,
2691 struct state_list **true_stack,
2692 struct state_list **false_stack)
2693 {
2694 struct sm_state *sm;
2695 char *left, *right;
2696 int op;
2697 static char buf[256];
2698
2699 if (expr->type != EXPR_COMPARE)
2700 return NULL;
2701
2702 op = expr->op;
2703
2704 left = expr_to_var(expr->left);
2705 right = expr_to_var(expr->right);
2706 if (!left || !right) {
2707 free_string(left);
2708 free_string(right);
2709 return NULL;
2710 }
2711
2712 if (strcmp(left, right) > 0) {
2713 char *tmp = left;
2714
2715 left = right;
2716 right = tmp;
2717 op = flip_comparison(op);
2718 }
2719
2720 snprintf(buf, sizeof(buf), "%s vs %s", left, right);
2721 sm = get_sm_state(compare_id, buf, NULL);
2722 if (!sm)
2723 return NULL;
2724 if (!sm->merged)
2725 return NULL;
2726
2727 filter_by_sm(sm, op, true_stack, false_stack);
2728 if (!*true_stack && !*false_stack)
2729 return NULL;
2730
2731 if (debug_implied())
2732 sm_msg("implications from comparison: (%s)", show_sm(sm));
2733
2734 return sm;
2735 }