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points_to_user_data: fake calls are not user data
[smatch.git] / smatch_comparison.c
blob6a1e460445fc7f6948a173c8357d642ace05f684
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 int cnt = 0;
587 char *tmp;
588
589 state = __alloc_smatch_state(0);
590
591 FOR_EACH_PTR(links, tmp) {
592 cnt += snprintf(buf + cnt, sizeof(buf) - cnt, "%s%s", cnt ? ", " : "", tmp);
593 if (cnt >= sizeof(buf))
594 goto done;
595 } END_FOR_EACH_PTR(tmp);
596
597 done:
598 state->name = alloc_sname(buf);
599 state->data = links;
600 return state;
601 }
602
603 static void save_start_states(struct statement *stmt)
604 {
605 struct symbol *param;
606 char orig[64];
607 char state_name[128];
608 struct smatch_state *state;
609 struct string_list *links;
610 char *link;
611
612 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
613 struct var_sym_list *left_vsl = NULL;
614 struct var_sym_list *right_vsl = NULL;
615
616 if (!param->ident)
617 continue;
618 snprintf(orig, sizeof(orig), "%s orig", param->ident->name);
619 snprintf(state_name, sizeof(state_name), "%s vs %s", param->ident->name, orig);
620 add_var_sym(&left_vsl, param->ident->name, param);
621 add_var_sym(&right_vsl, orig, param);
622 state = alloc_compare_state(
623 NULL, param->ident->name, left_vsl,
624 SPECIAL_EQUAL,
625 NULL, alloc_sname(orig), right_vsl);
626 set_state(comparison_id, state_name, NULL, state);
627
628 link = alloc_sname(state_name);
629 links = NULL;
630 insert_string(&links, link);
631 state = alloc_link_state(links);
632 set_state(link_id, param->ident->name, param, state);
633 } END_FOR_EACH_PTR(param);
634 }
635
636 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
637 {
638 struct smatch_state *ret;
639 struct string_list *links;
640
641 links = combine_string_lists(s1->data, s2->data);
642 ret = alloc_link_state(links);
643 return ret;
644 }
645
646 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
647 {
648 struct smatch_state *old_state, *new_state;
649 struct string_list *links;
650 char *new;
651
652 old_state = get_state(link_id, var, sym);
653 if (old_state)
654 links = clone_str_list(old_state->data);
655 else
656 links = NULL;
657
658 new = alloc_sname(link);
659 insert_string(&links, new);
660
661 new_state = alloc_link_state(links);
662 set_state(link_id, var, sym, new_state);
663 }
664
665 static void match_inc(struct sm_state *sm, bool preserve)
666 {
667 struct string_list *links;
668 struct smatch_state *state, *new;
669 struct compare_data *data;
670 char *tmp;
671 int flip;
672 int op;
673
674 links = sm->state->data;
675
676 FOR_EACH_PTR(links, tmp) {
677 state = get_state(comparison_id, tmp, NULL);
678 if (!state)
679 continue;
680 data = state->data;
681 if (!data)
682 continue;
683
684 flip = 0;
685 if (strncmp(sm->name, tmp, strlen(sm->name)) != 0 ||
686 tmp[strlen(sm->name)] != ' ')
687 flip = 1;
688
689 op = state_to_comparison(state);
690
691 switch (flip ? flip_comparison(op) : op) {
692 case SPECIAL_EQUAL:
693 case SPECIAL_GTE:
694 case SPECIAL_UNSIGNED_GTE:
695 case '>':
696 case SPECIAL_UNSIGNED_GT:
697 if (preserve)
698 break;
699 new = alloc_compare_state(
700 data->left, data->left_var, data->left_vsl,
701 flip ? '<' : '>',
702 data->right, data->right_var, data->right_vsl);
703 set_state(comparison_id, tmp, NULL, new);
704 break;
705 case '<':
706 case SPECIAL_UNSIGNED_LT:
707 new = alloc_compare_state(
708 data->left, data->left_var, data->left_vsl,
709 flip ? SPECIAL_GTE : SPECIAL_LTE,
710 data->right, data->right_var, data->right_vsl);
711 set_state(comparison_id, tmp, NULL, new);
712 break;
713 default:
714 new = alloc_compare_state(
715 data->left, data->left_var, data->left_vsl,
716 UNKNOWN_COMPARISON,
717 data->right, data->right_var, data->right_vsl);
718 set_state(comparison_id, tmp, NULL, new);
719 }
720 } END_FOR_EACH_PTR(tmp);
721 }
722
723 static void match_dec(struct sm_state *sm, bool preserve)
724 {
725 struct string_list *links;
726 struct smatch_state *state;
727 char *tmp;
728
729 links = sm->state->data;
730
731 FOR_EACH_PTR(links, tmp) {
732 struct compare_data *data;
733 struct smatch_state *new;
734
735 state = get_state(comparison_id, tmp, NULL);
736 if (!state || !state->data)
737 continue;
738
739 data = state->data;
740
741 switch (state_to_comparison(state)) {
742 case SPECIAL_EQUAL:
743 case SPECIAL_LTE:
744 case SPECIAL_UNSIGNED_LTE:
745 case '<':
746 case SPECIAL_UNSIGNED_LT: {
747 if (preserve)
748 break;
749
750 new = alloc_compare_state(
751 data->left, data->left_var, data->left_vsl,
752 '<',
753 data->right, data->right_var, data->right_vsl);
754 set_state(comparison_id, tmp, NULL, new);
755 break;
756 }
757 default:
758 new = alloc_compare_state(
759 data->left, data->left_var, data->left_vsl,
760 UNKNOWN_COMPARISON,
761 data->right, data->right_var, data->right_vsl);
762 set_state(comparison_id, tmp, NULL, new);
763 }
764 } END_FOR_EACH_PTR(tmp);
765 }
766
767 static void reset_sm(struct sm_state *sm)
768 {
769 struct string_list *links;
770 char *tmp;
771
772 links = sm->state->data;
773
774 FOR_EACH_PTR(links, tmp) {
775 struct smatch_state *old, *new;
776
777 old = get_state(comparison_id, tmp, NULL);
778 if (!old || !old->data) {
779 new = &undefined;
780 } else {
781 struct compare_data *data = old->data;
782
783 new = alloc_compare_state(
784 data->left, data->left_var, data->left_vsl,
785 UNKNOWN_COMPARISON,
786 data->right, data->right_var, data->right_vsl);
787 }
788 set_state(comparison_id, tmp, NULL, new);
789 } END_FOR_EACH_PTR(tmp);
790 set_state(link_id, sm->name, sm->sym, &undefined);
791 }
792
793 static bool match_add_sub_assign(struct sm_state *sm, struct expression *expr)
794 {
795 struct range_list *rl;
796 sval_t zero = { .type = &int_ctype };
797
798 if (!expr || expr->type != EXPR_ASSIGNMENT)
799 return false;
800 if (expr->op != SPECIAL_ADD_ASSIGN && expr->op != SPECIAL_SUB_ASSIGN)
801 return false;
802
803 get_absolute_rl(expr->right, &rl);
804 if (sval_is_negative(rl_min(rl))) {
805 reset_sm(sm);
806 return false;
807 }
808
809 if (expr->op == SPECIAL_ADD_ASSIGN)
810 match_inc(sm, rl_has_sval(rl, zero));
811 else
812 match_dec(sm, rl_has_sval(rl, zero));
813 return true;
814 }
815
816 static void match_inc_dec(struct sm_state *sm, struct expression *mod_expr)
817 {
818 /*
819 * if (foo > bar) then ++foo is also > bar.
820 */
821 if (!mod_expr)
822 return;
823 if (match_add_sub_assign(sm, mod_expr))
824 return;
825 if (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP)
826 return;
827
828 if (mod_expr->op == SPECIAL_INCREMENT)
829 match_inc(sm, false);
830 else if (mod_expr->op == SPECIAL_DECREMENT)
831 match_dec(sm, false);
832 }
833
834 static int is_self_assign(struct expression *expr)
835 {
836 if (!expr || expr->type != EXPR_ASSIGNMENT || expr->op != '=')
837 return 0;
838 return expr_equiv(expr->left, expr->right);
839 }
840
841 static void match_modify(struct sm_state *sm, struct expression *mod_expr)
842 {
843 if (mod_expr && is_self_assign(mod_expr))
844 return;
845
846 /* handled by match_inc_dec() */
847 if (mod_expr &&
848 ((mod_expr->type == EXPR_PREOP || mod_expr->type == EXPR_POSTOP) &&
849 (mod_expr->op == SPECIAL_INCREMENT || mod_expr->op == SPECIAL_DECREMENT)))
850 return;
851 if (mod_expr && mod_expr->type == EXPR_ASSIGNMENT &&
852 (mod_expr->op == SPECIAL_ADD_ASSIGN || mod_expr->op == SPECIAL_SUB_ASSIGN))
853 return;
854
855 reset_sm(sm);
856 }
857
858 static void match_preop(struct expression *expr)
859 {
860 struct expression *parent;
861 struct range_list *left, *right;
862 int op;
863
864 /*
865 * This is an important special case. Say you have:
866 *
867 * if (++j == limit)
868 *
869 * Assume that we know the range of limit is higher than the start
870 * value for "j". Then the first thing that we process is the ++j. We
871 * have not comparison states set up so it doesn't get caught by the
872 * modification hook. But it does get caught by smatch_extra which sets
873 * j to unknown then we parse the "j == limit" and sets false to != but
874 * really we want false to be <.
875 *
876 * So what we do is we set j < limit here, then the match_modify catches
877 * it and we do a match_inc_dec().
878 *
879 */
880
881 if (expr->type != EXPR_PREOP ||
882 (expr->op != SPECIAL_INCREMENT && expr->op != SPECIAL_DECREMENT))
883 return;
884
885 parent = expr_get_parent_expr(expr);
886 if (!parent)
887 return;
888 if (parent->type != EXPR_COMPARE || parent->op != SPECIAL_EQUAL)
889 return;
890 if (parent->left != expr)
891 return;
892
893 if (!get_implied_rl(expr->unop, &left) ||
894 !get_implied_rl(parent->right, &right))
895 return;
896
897 op = rl_comparison(left, right);
898 if (op == UNKNOWN_COMPARISON)
899 return;
900
901 add_comparison(expr->unop, op, parent->right);
902 }
903
904 static char *chunk_to_var_sym(struct expression *expr, struct symbol **sym)
905 {
906 expr = strip_expr(expr);
907 if (!expr)
908 return NULL;
909 if (sym)
910 *sym = NULL;
911
912 if (expr->type == EXPR_PREOP &&
913 (expr->op == SPECIAL_INCREMENT ||
914 expr->op == SPECIAL_DECREMENT))
915 expr = strip_expr(expr->unop);
916
917 if (expr->type == EXPR_CALL) {
918 char buf[64];
919
920 snprintf(buf, sizeof(buf), "return %p", expr);
921 return alloc_string(buf);
922 }
923
924 return expr_to_chunk_sym_vsl(expr, sym, NULL);
925 }
926
927 static char *chunk_to_var(struct expression *expr)
928 {
929 return chunk_to_var_sym(expr, NULL);
930 }
931
932 static struct smatch_state *get_state_chunk(int owner, struct expression *expr)
933 {
934 char *name;
935 struct symbol *sym;
936 struct smatch_state *ret;
937
938 name = chunk_to_var_sym(expr, &sym);
939 if (!name)
940 return NULL;
941
942 ret = get_state(owner, name, sym);
943 free_string(name);
944 return ret;
945 }
946
947 static void save_link(struct expression *expr, char *link)
948 {
949 char *var;
950 struct symbol *sym;
951
952 expr = strip_expr(expr);
953 if (expr->type == EXPR_BINOP) {
954 char *chunk;
955
956 chunk = chunk_to_var(expr);
957 if (!chunk)
958 return;
959
960 save_link(expr->left, link);
961 save_link(expr->right, link);
962 save_link_var_sym(chunk, NULL, link);
963 return;
964 }
965
966 var = chunk_to_var_sym(expr, &sym);
967 if (!var)
968 return;
969
970 save_link_var_sym(var, sym, link);
971 free_string(var);
972 }
973
974 static int get_orig_comparison(struct stree *pre_stree, const char *left, const char *right)
975 {
976 struct smatch_state *state;
977 struct compare_data *data;
978 int flip = 0;
979 char state_name[256];
980
981 if (strcmp(left, right) > 0) {
982 const char *tmp = right;
983
984 flip = 1;
985 right = left;
986 left = tmp;
987 }
988
989 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
990 state = get_state_stree(pre_stree, comparison_id, state_name, NULL);
991 if (!state || !state->data)
992 return 0;
993 data = state->data;
994 if (flip)
995 return flip_comparison(data->comparison);
996 return data->comparison;
997
998 }
999
1000 static int have_common_var_sym(struct var_sym_list *left_vsl, struct var_sym_list *right_vsl)
1001 {
1002 struct var_sym *tmp;
1003
1004 FOR_EACH_PTR(left_vsl, tmp) {
1005 if (in_var_sym_list(right_vsl, tmp->var, tmp->sym))
1006 return 1;
1007 } END_FOR_EACH_PTR(tmp);
1008
1009 return 0;
1010 }
1011
1012 /*
1013 * The idea here is that we take a comparison "a < b" and then we look at all
1014 * the things which "b" is compared against "b < c" and we say that that implies
1015 * a relationship "a < c".
1016 *
1017 * The names here about because the comparisons are organized like this
1018 * "a < b < c".
1019 *
1020 */
1021 static void update_tf_links(struct stree *pre_stree,
1022 struct expression *left_expr,
1023 const char *left_var, struct var_sym_list *left_vsl,
1024 int left_comparison, int left_false_comparison,
1025 const char *mid_var, struct var_sym_list *mid_vsl,
1026 struct string_list *links)
1027 {
1028 struct smatch_state *state;
1029 struct smatch_state *true_state, *false_state;
1030 struct compare_data *data;
1031 struct expression *right_expr;
1032 const char *right_var;
1033 struct var_sym_list *right_vsl;
1034 int orig_comparison;
1035 int right_comparison;
1036 int true_comparison;
1037 int false_comparison;
1038 char *tmp;
1039 char state_name[256];
1040 struct var_sym *vs;
1041
1042 FOR_EACH_PTR(links, tmp) {
1043 state = get_state_stree(pre_stree, comparison_id, tmp, NULL);
1044 if (!state || !state->data)
1045 continue;
1046 data = state->data;
1047 right_comparison = data->comparison;
1048 right_expr = data->right;
1049 right_var = data->right_var;
1050 right_vsl = data->right_vsl;
1051 if (strcmp(mid_var, right_var) == 0) {
1052 right_expr = data->left;
1053 right_var = data->left_var;
1054 right_vsl = data->left_vsl;
1055 right_comparison = flip_comparison(right_comparison);
1056 }
1057 if (have_common_var_sym(left_vsl, right_vsl))
1058 continue;
1059
1060 orig_comparison = get_orig_comparison(pre_stree, left_var, right_var);
1061
1062 true_comparison = combine_comparisons(left_comparison, right_comparison);
1063 false_comparison = combine_comparisons(left_false_comparison, right_comparison);
1064
1065 true_comparison = comparison_intersection(orig_comparison, true_comparison);
1066 false_comparison = comparison_intersection(orig_comparison, false_comparison);
1067
1068 if (strcmp(left_var, right_var) > 0) {
1069 struct expression *tmp_expr = left_expr;
1070 const char *tmp_var = left_var;
1071 struct var_sym_list *tmp_vsl = left_vsl;
1072
1073 left_expr = right_expr;
1074 left_var = right_var;
1075 left_vsl = right_vsl;
1076 right_expr = tmp_expr;
1077 right_var = tmp_var;
1078 right_vsl = tmp_vsl;
1079 true_comparison = flip_comparison(true_comparison);
1080 false_comparison = flip_comparison(false_comparison);
1081 }
1082
1083 if (!true_comparison && !false_comparison)
1084 continue;
1085
1086 if (true_comparison)
1087 true_state = alloc_compare_state(
1088 left_expr, left_var, left_vsl,
1089 true_comparison,
1090 right_expr, right_var, right_vsl);
1091 else
1092 true_state = NULL;
1093 if (false_comparison)
1094 false_state = alloc_compare_state(
1095 left_expr, left_var, left_vsl,
1096 false_comparison,
1097 right_expr, right_var, right_vsl);
1098 else
1099 false_state = NULL;
1100
1101 snprintf(state_name, sizeof(state_name), "%s vs %s", left_var, right_var);
1102 set_true_false_states(comparison_id, state_name, NULL, true_state, false_state);
1103 FOR_EACH_PTR(left_vsl, vs) {
1104 save_link_var_sym(vs->var, vs->sym, state_name);
1105 } END_FOR_EACH_PTR(vs);
1106 FOR_EACH_PTR(right_vsl, vs) {
1107 save_link_var_sym(vs->var, vs->sym, state_name);
1108 } END_FOR_EACH_PTR(vs);
1109 if (!vsl_to_sym(left_vsl))
1110 save_link_var_sym(left_var, NULL, state_name);
1111 if (!vsl_to_sym(right_vsl))
1112 save_link_var_sym(right_var, NULL, state_name);
1113 } END_FOR_EACH_PTR(tmp);
1114 }
1115
1116 static void update_tf_data(struct stree *pre_stree,
1117 struct expression *left_expr,
1118 const char *left_name, struct var_sym_list *left_vsl,
1119 struct expression *right_expr,
1120 const char *right_name, struct var_sym_list *right_vsl,
1121 int true_comparison, int false_comparison)
1122 {
1123 struct smatch_state *state;
1124
1125 state = get_state_stree(pre_stree, link_id, right_name, vsl_to_sym(right_vsl));
1126 if (state)
1127 update_tf_links(pre_stree, left_expr, left_name, left_vsl, true_comparison, false_comparison, right_name, right_vsl, state->data);
1128
1129 state = get_state_stree(pre_stree, link_id, left_name, vsl_to_sym(left_vsl));
1130 if (state)
1131 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);
1132 }
1133
1134 static void iter_modify(struct sm_state *sm, struct expression *mod_expr)
1135 {
1136 if (sm->state != &start ||
1137 !mod_expr ||
1138 (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP) ||
1139 mod_expr->op != SPECIAL_INCREMENT)
1140 set_state(inc_dec_id, sm->name, sm->sym, &undefined);
1141 else
1142 set_state(inc_dec_id, sm->name, sm->sym, &incremented);
1143 }
1144
1145 static void handle_for_loops(struct expression *expr, char *state_name, struct smatch_state *false_state)
1146 {
1147 sval_t sval;
1148 char *iter_name, *cap_name;
1149 struct symbol *iter_sym, *cap_sym;
1150 struct compare_data *data;
1151
1152 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1153 return;
1154
1155 if (!__cur_stmt || !__prev_stmt)
1156 return;
1157 if (__cur_stmt->type != STMT_ITERATOR)
1158 return;
1159 if (__cur_stmt->iterator_pre_condition != expr)
1160 return;
1161
1162 /* literals are handled in smatch_extra.c */
1163 if (get_value(expr->right, &sval))
1164 return;
1165
1166 /* First time checking the condition */
1167 if (__prev_stmt == __cur_stmt->iterator_pre_statement) {
1168 if (!get_implied_value(expr->left, &sval) ||
1169 sval.value != 0)
1170 return;
1171
1172 iter_name = expr_to_var_sym(expr->left, &iter_sym);
1173 cap_name = expr_to_var_sym(expr->right, &cap_sym);
1174 if (!iter_name || !cap_name || !iter_sym || !cap_sym) {
1175 free_string(iter_name);
1176 free_string(cap_name);
1177 return;
1178 }
1179
1180 set_state(inc_dec_id, iter_name, iter_sym, &start);
1181 store_link(inc_dec_link_id, cap_name, cap_sym, iter_name, iter_sym);
1182
1183 free_string(iter_name);
1184 free_string(cap_name);
1185 return;
1186 }
1187
1188 /* Second time checking the condtion */
1189 if (__prev_stmt != __cur_stmt->iterator_post_statement)
1190 return;
1191
1192 if (get_state_chunk(inc_dec_id, expr->left) != &incremented)
1193 return;
1194
1195 data = false_state->data;
1196 false_state = alloc_compare_state(
1197 data->left, data->left_var, data->left_vsl,
1198 SPECIAL_EQUAL,
1199 data->right, data->right_var, data->right_vsl);
1200
1201 // FIXME: This doesn't handle links correct so it doesn't set "param orig"
1202 set_true_false_states(comparison_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 remove_plus_minus_zero(struct expression **expr_p)
1228 {
1229 struct expression *expr = *expr_p;
1230 sval_t sval;
1231
1232 if (!expr || expr->type != EXPR_BINOP)
1233 return;
1234 if (expr->op == '+') {
1235 if (get_implied_value(expr->left, &sval) && sval.value == 0)
1236 *expr_p = expr->right;
1237 else if (get_implied_value(expr->right, &sval) && sval.value == 0)
1238 *expr_p = expr->left;
1239 else
1240 return;
1241 return remove_plus_minus_zero(expr_p);
1242 }
1243 if (expr->op == '-') {
1244 if (get_implied_value(expr->right, &sval) && sval.value == 0) {
1245 *expr_p = expr->left;
1246 return remove_plus_minus_zero(expr_p);
1247 }
1248 }
1249 }
1250
1251 static void move_plus_to_minus_helper(struct expression **left_p, struct expression **right_p)
1252 {
1253 struct expression *left = *left_p;
1254 struct expression *right = *right_p;
1255
1256 /*
1257 * These two are basically equivalent: "foo + 1 != bar" and
1258 * "foo != bar - 1". There are issues with signedness and integer
1259 * overflows. There are also issues with type as well. But let's
1260 * pretend we can ignore all that stuff for now.
1261 *
1262 */
1263
1264 if (!is_plus_one(left))
1265 return;
1266
1267 *left_p = left->left;
1268 *right_p = binop_expression(right, '-', left->right);
1269 }
1270
1271 static void move_plus_to_minus(struct expression **left_p, struct expression **right_p)
1272 {
1273 if (is_plus_one(*left_p) && is_plus_one(*right_p))
1274 return;
1275
1276 move_plus_to_minus_helper(left_p, right_p);
1277 move_plus_to_minus_helper(right_p, left_p);
1278 }
1279
1280 static void simplify_binops(struct expression **left_p, struct expression **right_p)
1281 {
1282 remove_plus_minus_zero(left_p);
1283 remove_plus_minus_zero(right_p);
1284
1285 move_plus_to_minus(left_p, right_p);
1286 }
1287
1288 static void handle_comparison(struct expression *left_expr, int op, struct expression *right_expr, char **_state_name, struct smatch_state **_false_state)
1289 {
1290 char *left = NULL;
1291 char *right = NULL;
1292 struct symbol *left_sym, *right_sym;
1293 struct var_sym_list *left_vsl = NULL;
1294 struct var_sym_list *right_vsl = NULL;
1295 int false_op;
1296 int orig_comparison;
1297 struct smatch_state *true_state, *false_state;
1298 static char state_name[256];
1299 struct stree *pre_stree;
1300 sval_t sval;
1301
1302 if (!left_expr || !right_expr)
1303 return;
1304
1305 left_expr = strip_parens(left_expr);
1306 right_expr = strip_parens(right_expr);
1307
1308 while (left_expr->type == EXPR_ASSIGNMENT)
1309 left_expr = strip_parens(left_expr->left);
1310 while (right_expr->type == EXPR_ASSIGNMENT)
1311 right_expr = strip_parens(right_expr->left);
1312
1313 false_op = negate_comparison(op);
1314
1315 simplify_binops(&left_expr, &right_expr);
1316
1317 if (op == SPECIAL_UNSIGNED_LT &&
1318 get_implied_value(left_expr, &sval) &&
1319 sval.value == 0)
1320 false_op = SPECIAL_EQUAL;
1321
1322 if (op == SPECIAL_UNSIGNED_GT &&
1323 get_implied_value(right_expr, &sval) &&
1324 sval.value == 0)
1325 false_op = SPECIAL_EQUAL;
1326
1327 left = chunk_to_var_sym(left_expr, &left_sym);
1328 if (!left)
1329 goto free;
1330 if (left_sym)
1331 add_var_sym(&left_vsl, left, left_sym);
1332 else
1333 left_vsl = expr_to_vsl(left_expr);
1334 right = chunk_to_var_sym(right_expr, &right_sym);
1335 if (!right)
1336 goto free;
1337 if (right_sym)
1338 add_var_sym(&right_vsl, right, right_sym);
1339 else
1340 right_vsl = expr_to_vsl(right_expr);
1341
1342 if (strcmp(left, right) > 0) {
1343 char *tmp_name = left;
1344 struct var_sym_list *tmp_vsl = left_vsl;
1345 struct expression *tmp_expr = left_expr;
1346
1347 left = right;
1348 left_vsl = right_vsl;
1349 left_expr = right_expr;
1350 right = tmp_name;
1351 right_vsl = tmp_vsl;
1352 right_expr = tmp_expr;
1353 op = flip_comparison(op);
1354 false_op = flip_comparison(false_op);
1355 }
1356
1357 orig_comparison = get_comparison(left_expr, right_expr);
1358 op = comparison_intersection(orig_comparison, op);
1359 false_op = comparison_intersection(orig_comparison, false_op);
1360
1361 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
1362 true_state = alloc_compare_state(
1363 left_expr, left, left_vsl,
1364 op,
1365 right_expr, right, right_vsl);
1366 false_state = alloc_compare_state(
1367 left_expr, left, left_vsl,
1368 false_op,
1369 right_expr, right, right_vsl);
1370
1371 pre_stree = clone_stree(__get_cur_stree());
1372 update_tf_data(pre_stree, left_expr, left, left_vsl, right_expr, right, right_vsl, op, false_op);
1373 free_stree(&pre_stree);
1374
1375 set_true_false_states(comparison_id, state_name, NULL, true_state, false_state);
1376 __compare_param_limit_hook(left_expr, right_expr, state_name, true_state, false_state);
1377 save_link(left_expr, state_name);
1378 save_link(right_expr, state_name);
1379
1380 if (_false_state)
1381 *_false_state = false_state;
1382 if (_state_name)
1383 *_state_name = state_name;
1384 free:
1385 free_string(left);
1386 free_string(right);
1387 }
1388
1389 void __comparison_match_condition(struct expression *expr)
1390 {
1391 struct expression *left, *right, *new_left, *new_right, *tmp;
1392 struct smatch_state *false_state = NULL;
1393 char *state_name = NULL;
1394 int redo, count;
1395
1396 if (expr->type != EXPR_COMPARE)
1397 return;
1398
1399 handle_comparison(expr->left, expr->op, expr->right, &state_name, &false_state);
1400 if (false_state && state_name)
1401 handle_for_loops(expr, state_name, false_state);
1402
1403 left = strip_parens(expr->left);
1404 right = strip_parens(expr->right);
1405
1406 if (left->type == EXPR_BINOP && left->op == '+') {
1407 new_left = left->left;
1408 new_right = binop_expression(right, '-', left->right);
1409 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1410
1411 new_left = left->right;
1412 new_right = binop_expression(right, '-', left->left);
1413 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1414 }
1415
1416 redo = 0;
1417 left = strip_parens(expr->left);
1418 right = strip_parens(expr->right);
1419 if (get_last_expr_from_expression_stmt(expr->left)) {
1420 left = get_last_expr_from_expression_stmt(expr->left);
1421 redo = 1;
1422 }
1423 if (get_last_expr_from_expression_stmt(expr->right)) {
1424 right = get_last_expr_from_expression_stmt(expr->right);
1425 redo = 1;
1426 }
1427
1428 if (!redo)
1429 return;
1430
1431 count = 0;
1432 while ((tmp = get_assigned_expr(left))) {
1433 if (count++ > 3)
1434 break;
1435 left = strip_expr(tmp);
1436 }
1437 count = 0;
1438 while ((tmp = get_assigned_expr(right))) {
1439 if (count++ > 3)
1440 break;
1441 right = strip_expr(tmp);
1442 }
1443
1444 handle_comparison(left, expr->op, right, NULL, NULL);
1445 }
1446
1447 static void add_comparison_var_sym(
1448 struct expression *left_expr,
1449 const char *left_name, struct var_sym_list *left_vsl,
1450 int comparison,
1451 struct expression *right_expr,
1452 const char *right_name, struct var_sym_list *right_vsl)
1453 {
1454 struct smatch_state *state;
1455 struct var_sym *vs;
1456 char state_name[256];
1457
1458 if (strcmp(left_name, right_name) > 0) {
1459 struct expression *tmp_expr = left_expr;
1460 const char *tmp_name = left_name;
1461 struct var_sym_list *tmp_vsl = left_vsl;
1462
1463 left_expr = right_expr;
1464 left_name = right_name;
1465 left_vsl = right_vsl;
1466 right_expr = tmp_expr;
1467 right_name = tmp_name;
1468 right_vsl = tmp_vsl;
1469 comparison = flip_comparison(comparison);
1470 }
1471 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1472 state = alloc_compare_state(
1473 left_expr, left_name, left_vsl,
1474 comparison,
1475 right_expr, right_name, right_vsl);
1476
1477 set_state(comparison_id, state_name, NULL, state);
1478
1479 FOR_EACH_PTR(left_vsl, vs) {
1480 save_link_var_sym(vs->var, vs->sym, state_name);
1481 } END_FOR_EACH_PTR(vs);
1482 FOR_EACH_PTR(right_vsl, vs) {
1483 save_link_var_sym(vs->var, vs->sym, state_name);
1484 } END_FOR_EACH_PTR(vs);
1485 }
1486
1487 static void add_comparison(struct expression *left, int comparison, struct expression *right)
1488 {
1489 char *left_name = NULL;
1490 char *right_name = NULL;
1491 struct symbol *left_sym, *right_sym;
1492 struct var_sym_list *left_vsl, *right_vsl;
1493 struct smatch_state *state;
1494 char state_name[256];
1495
1496 left_name = chunk_to_var_sym(left, &left_sym);
1497 if (!left_name)
1498 goto free;
1499 left_vsl = expr_to_vsl(left);
1500 right_name = chunk_to_var_sym(right, &right_sym);
1501 if (!right_name)
1502 goto free;
1503 right_vsl = expr_to_vsl(right);
1504
1505 if (strcmp(left_name, right_name) > 0) {
1506 struct expression *tmp_expr = left;
1507 struct symbol *tmp_sym = left_sym;
1508 char *tmp_name = left_name;
1509 struct var_sym_list *tmp_vsl = left_vsl;
1510
1511 left = right;
1512 left_name = right_name;
1513 left_sym = right_sym;
1514 left_vsl = right_vsl;
1515 right = tmp_expr;
1516 right_name = tmp_name;
1517 right_sym = tmp_sym;
1518 right_vsl = tmp_vsl;
1519 comparison = flip_comparison(comparison);
1520 }
1521 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1522 state = alloc_compare_state(
1523 left, left_name, left_vsl,
1524 comparison,
1525 right, right_name, right_vsl);
1526
1527 set_state(comparison_id, state_name, NULL, state);
1528 save_link(left, state_name);
1529 save_link(right, state_name);
1530
1531 free:
1532 free_string(left_name);
1533 free_string(right_name);
1534 }
1535
1536 static void match_assign_add(struct expression *expr)
1537 {
1538 struct expression *right;
1539 struct expression *r_left, *r_right;
1540 sval_t left_tmp, right_tmp;
1541
1542 right = strip_expr(expr->right);
1543 r_left = strip_expr(right->left);
1544 r_right = strip_expr(right->right);
1545
1546 get_absolute_min(r_left, &left_tmp);
1547 get_absolute_min(r_right, &right_tmp);
1548
1549 if (left_tmp.value > 0)
1550 add_comparison(expr->left, '>', r_right);
1551 else if (left_tmp.value == 0)
1552 add_comparison(expr->left, SPECIAL_GTE, r_right);
1553
1554 if (right_tmp.value > 0)
1555 add_comparison(expr->left, '>', r_left);
1556 else if (right_tmp.value == 0)
1557 add_comparison(expr->left, SPECIAL_GTE, r_left);
1558 }
1559
1560 static void match_assign_sub(struct expression *expr)
1561 {
1562 struct expression *right;
1563 struct expression *r_left, *r_right;
1564 int comparison;
1565 sval_t min;
1566
1567 right = strip_expr(expr->right);
1568 r_left = strip_expr(right->left);
1569 r_right = strip_expr(right->right);
1570
1571 if (get_absolute_min(r_right, &min) && sval_is_negative(min))
1572 return;
1573
1574 comparison = get_comparison(r_left, r_right);
1575
1576 switch (comparison) {
1577 case '>':
1578 case SPECIAL_GTE:
1579 if (implied_not_equal(r_right, 0))
1580 add_comparison(expr->left, '>', r_left);
1581 else
1582 add_comparison(expr->left, SPECIAL_GTE, r_left);
1583 return;
1584 }
1585 }
1586
1587 static void match_assign_divide(struct expression *expr)
1588 {
1589 struct expression *right;
1590 struct expression *r_left, *r_right;
1591 sval_t min;
1592
1593 right = strip_expr(expr->right);
1594 r_left = strip_expr(right->left);
1595 r_right = strip_expr(right->right);
1596 if (!get_implied_min(r_right, &min) || min.value <= 1)
1597 return;
1598
1599 add_comparison(expr->left, '<', r_left);
1600 }
1601
1602 static void match_binop_assign(struct expression *expr)
1603 {
1604 struct expression *right;
1605
1606 right = strip_expr(expr->right);
1607 if (right->op == '+')
1608 match_assign_add(expr);
1609 if (right->op == '-')
1610 match_assign_sub(expr);
1611 if (right->op == '/')
1612 match_assign_divide(expr);
1613 }
1614
1615 static void copy_comparisons(struct expression *left, struct expression *right)
1616 {
1617 struct string_list *links;
1618 struct smatch_state *state;
1619 struct compare_data *data;
1620 struct symbol *left_sym, *right_sym;
1621 char *left_var = NULL;
1622 char *right_var = NULL;
1623 struct var_sym_list *left_vsl;
1624 struct expression *expr;
1625 const char *var;
1626 struct var_sym_list *vsl;
1627 int comparison;
1628 char *tmp;
1629
1630 left_var = chunk_to_var_sym(left, &left_sym);
1631 if (!left_var)
1632 goto done;
1633 left_vsl = expr_to_vsl(left);
1634 right_var = chunk_to_var_sym(right, &right_sym);
1635 if (!right_var)
1636 goto done;
1637
1638 state = get_state(link_id, right_var, right_sym);
1639 if (!state)
1640 return;
1641 links = state->data;
1642
1643 FOR_EACH_PTR(links, tmp) {
1644 state = get_state(comparison_id, tmp, NULL);
1645 if (!state || !state->data)
1646 continue;
1647 data = state->data;
1648 comparison = data->comparison;
1649 expr = data->right;
1650 var = data->right_var;
1651 vsl = data->right_vsl;
1652 if (strcmp(var, right_var) == 0) {
1653 expr = data->left;
1654 var = data->left_var;
1655 vsl = data->left_vsl;
1656 comparison = flip_comparison(comparison);
1657 }
1658 /* n = copy_from_user(dest, src, n); leads to n <= n which is nonsense */
1659 if (strcmp(left_var, var) == 0)
1660 continue;
1661 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1662 } END_FOR_EACH_PTR(tmp);
1663
1664 done:
1665 free_string(right_var);
1666 }
1667
1668 static bool is_empty_fake_assign(struct expression *expr)
1669 {
1670 if (!__in_fake_var_assign)
1671 return false;
1672 if (get_state_chunk(link_id, expr->right))
1673 return false;
1674 return true;
1675 }
1676
1677 static void match_assign(struct expression *expr)
1678 {
1679 struct expression *right;
1680
1681 if (expr->op != '=')
1682 return;
1683 if (__in_fake_assign || outside_of_function())
1684 return;
1685
1686 if (is_struct(expr->left))
1687 return;
1688
1689 if (is_self_assign(expr))
1690 return;
1691
1692 if (is_empty_fake_assign(expr))
1693 return;
1694
1695 copy_comparisons(expr->left, expr->right);
1696 add_comparison(expr->left, SPECIAL_EQUAL, expr->right);
1697
1698 right = strip_expr(expr->right);
1699 if (right->type == EXPR_BINOP)
1700 match_binop_assign(expr);
1701 }
1702
1703 int get_comparison_strings(const char *one, const char *two)
1704 {
1705 char buf[256];
1706 struct smatch_state *state;
1707 int invert = 0;
1708 int ret = 0;
1709
1710 if (!one || !two)
1711 return UNKNOWN_COMPARISON;
1712
1713 if (strcmp(one, two) == 0)
1714 return SPECIAL_EQUAL;
1715
1716 if (strcmp(one, two) > 0) {
1717 const char *tmp = one;
1718
1719 one = two;
1720 two = tmp;
1721 invert = 1;
1722 }
1723
1724 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1725 state = get_state(comparison_id, buf, NULL);
1726 if (state)
1727 ret = state_to_comparison(state);
1728
1729 if (invert)
1730 ret = flip_comparison(ret);
1731
1732 return ret;
1733 }
1734
1735 static int get_comparison_helper(struct expression *a, struct expression *b, bool use_extra)
1736 {
1737 char *one = NULL;
1738 char *two = NULL;
1739 int ret = UNKNOWN_COMPARISON;
1740 int extra = UNKNOWN_COMPARISON;
1741
1742 if (a == UNKNOWN_COMPARISON ||
1743 b == UNKNOWN_COMPARISON)
1744 return UNKNOWN_COMPARISON;
1745
1746 a = strip_parens(a);
1747 b = strip_parens(b);
1748
1749 move_plus_to_minus(&a, &b);
1750
1751 simplify_binops(&a, &b);
1752
1753 one = chunk_to_var(a);
1754 if (!one)
1755 goto free;
1756 two = chunk_to_var(b);
1757 if (!two)
1758 goto free;
1759
1760 ret = get_comparison_strings(one, two);
1761 if (ret)
1762 goto free;
1763
1764 if (is_plus_one(a) || is_minus_one(a)) {
1765 free_string(one);
1766 one = chunk_to_var(a->left);
1767 ret = get_comparison_strings(one, two);
1768 } else if (is_plus_one(b) || is_minus_one(b)) {
1769 free_string(two);
1770 two = chunk_to_var(b->left);
1771 ret = get_comparison_strings(one, two);
1772 }
1773
1774 if (ret == UNKNOWN_COMPARISON)
1775 goto free;
1776
1777 if ((is_plus_one(a) || is_minus_one(b)) && ret == '<')
1778 ret = SPECIAL_LTE;
1779 else if ((is_minus_one(a) || is_plus_one(b)) && ret == '>')
1780 ret = SPECIAL_GTE;
1781 else
1782 ret = UNKNOWN_COMPARISON;
1783
1784 free:
1785 free_string(one);
1786 free_string(two);
1787
1788 if (use_extra)
1789 extra = comparison_from_extra(a, b);
1790 return comparison_intersection(ret, extra);
1791 }
1792
1793 int get_comparison(struct expression *a, struct expression *b)
1794 {
1795 return get_comparison_helper(a, b, true);
1796 }
1797
1798 int get_comparison_no_extra(struct expression *a, struct expression *b)
1799 {
1800 return get_comparison_helper(a, b, false);
1801 }
1802
1803 int possible_comparison(struct expression *a, int comparison, struct expression *b)
1804 {
1805 char *one = NULL;
1806 char *two = NULL;
1807 int ret = 0;
1808 char buf[256];
1809 struct sm_state *sm;
1810 int saved;
1811
1812 one = chunk_to_var(a);
1813 if (!one)
1814 goto free;
1815 two = chunk_to_var(b);
1816 if (!two)
1817 goto free;
1818
1819
1820 if (strcmp(one, two) == 0 && comparison == SPECIAL_EQUAL) {
1821 ret = 1;
1822 goto free;
1823 }
1824
1825 if (strcmp(one, two) > 0) {
1826 char *tmp = one;
1827
1828 one = two;
1829 two = tmp;
1830 comparison = flip_comparison(comparison);
1831 }
1832
1833 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1834 sm = get_sm_state(comparison_id, buf, NULL);
1835 if (!sm)
1836 goto free;
1837
1838 FOR_EACH_PTR(sm->possible, sm) {
1839 if (!sm->state->data)
1840 continue;
1841 saved = ((struct compare_data *)sm->state->data)->comparison;
1842 if (saved == comparison)
1843 ret = 1;
1844 if (comparison == SPECIAL_EQUAL &&
1845 (saved == SPECIAL_LTE ||
1846 saved == SPECIAL_GTE ||
1847 saved == SPECIAL_UNSIGNED_LTE ||
1848 saved == SPECIAL_UNSIGNED_GTE))
1849 ret = 1;
1850 if (ret == 1)
1851 goto free;
1852 } END_FOR_EACH_PTR(sm);
1853
1854 return ret;
1855 free:
1856 free_string(one);
1857 free_string(two);
1858 return ret;
1859 }
1860
1861 struct state_list *get_all_comparisons(struct expression *expr)
1862 {
1863 struct smatch_state *state;
1864 struct string_list *links;
1865 struct state_list *ret = NULL;
1866 struct sm_state *sm;
1867 char *tmp;
1868
1869 state = get_state_chunk(link_id, expr);
1870 if (!state)
1871 return NULL;
1872 links = state->data;
1873
1874 FOR_EACH_PTR(links, tmp) {
1875 sm = get_sm_state(comparison_id, tmp, NULL);
1876 if (!sm)
1877 continue;
1878 // FIXME have to compare name with vsl
1879 add_ptr_list(&ret, sm);
1880 } END_FOR_EACH_PTR(tmp);
1881
1882 return ret;
1883 }
1884
1885 struct state_list *get_all_possible_equal_comparisons(struct expression *expr)
1886 {
1887 struct smatch_state *state;
1888 struct string_list *links;
1889 struct state_list *ret = NULL;
1890 struct sm_state *sm;
1891 char *tmp;
1892
1893 state = get_state_chunk(link_id, expr);
1894 if (!state)
1895 return NULL;
1896 links = state->data;
1897
1898 FOR_EACH_PTR(links, tmp) {
1899 sm = get_sm_state(comparison_id, tmp, NULL);
1900 if (!sm)
1901 continue;
1902 if (!strchr(sm->state->name, '='))
1903 continue;
1904 if (strcmp(sm->state->name, "!=") == 0)
1905 continue;
1906 add_ptr_list(&ret, sm);
1907 } END_FOR_EACH_PTR(tmp);
1908
1909 return ret;
1910 }
1911
1912 struct state_list *get_all_possible_not_equal_comparisons(struct expression *expr)
1913 {
1914 struct smatch_state *state;
1915 struct string_list *links;
1916 struct state_list *ret = NULL;
1917 struct sm_state *sm;
1918 struct sm_state *possible;
1919 char *link;
1920
1921 return NULL;
1922
1923 state = get_state_chunk(link_id, expr);
1924 if (!state)
1925 return NULL;
1926 links = state->data;
1927
1928 FOR_EACH_PTR(links, link) {
1929 sm = get_sm_state(comparison_id, link, NULL);
1930 if (!sm)
1931 continue;
1932 FOR_EACH_PTR(sm->possible, possible) {
1933 if (strcmp(possible->state->name, "!=") != 0)
1934 continue;
1935 add_ptr_list(&ret, sm);
1936 break;
1937 } END_FOR_EACH_PTR(possible);
1938 } END_FOR_EACH_PTR(link);
1939
1940 return ret;
1941 }
1942
1943 static void update_links_from_call(struct expression *left,
1944 int left_compare,
1945 struct expression *right)
1946 {
1947 struct string_list *links;
1948 struct smatch_state *state;
1949 struct compare_data *data;
1950 struct symbol *left_sym, *right_sym;
1951 char *left_var = NULL;
1952 char *right_var = NULL;
1953 struct var_sym_list *left_vsl;
1954 struct expression *expr;
1955 const char *var;
1956 struct var_sym_list *vsl;
1957 int comparison;
1958 char *tmp;
1959
1960 left_var = chunk_to_var_sym(left, &left_sym);
1961 if (!left_var)
1962 goto done;
1963 left_vsl = expr_to_vsl(left);
1964 right_var = chunk_to_var_sym(right, &right_sym);
1965 if (!right_var)
1966 goto done;
1967
1968 state = get_state(link_id, right_var, right_sym);
1969 if (!state)
1970 return;
1971 links = state->data;
1972
1973 FOR_EACH_PTR(links, tmp) {
1974 state = get_state(comparison_id, tmp, NULL);
1975 if (!state || !state->data)
1976 continue;
1977 data = state->data;
1978 comparison = data->comparison;
1979 expr = data->right;
1980 var = data->right_var;
1981 vsl = data->right_vsl;
1982 if (strcmp(var, right_var) == 0) {
1983 expr = data->left;
1984 var = data->left_var;
1985 vsl = data->left_vsl;
1986 comparison = flip_comparison(comparison);
1987 }
1988 comparison = combine_comparisons(left_compare, comparison);
1989 if (!comparison)
1990 continue;
1991 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1992 } END_FOR_EACH_PTR(tmp);
1993
1994 done:
1995 free_string(right_var);
1996 }
1997
1998 void __add_return_comparison(struct expression *call, const char *range)
1999 {
2000 struct expression *arg;
2001 int comparison;
2002 char buf[16];
2003
2004 if (!str_to_comparison_arg(range, call, &comparison, &arg))
2005 return;
2006 snprintf(buf, sizeof(buf), "%s", show_comparison(comparison));
2007 update_links_from_call(call, comparison, arg);
2008 add_comparison(call, comparison, arg);
2009 }
2010
2011 void __add_comparison_info(struct expression *expr, struct expression *call, const char *range)
2012 {
2013 copy_comparisons(expr, call);
2014 }
2015
2016 static char *get_mask_comparison(struct expression *expr, int ignore)
2017 {
2018 struct expression *tmp, *right;
2019 int count, param;
2020 char buf[256];
2021
2022 /* The return value for "return foo & param;" is <= param */
2023
2024 count = 0;
2025 while ((tmp = get_assigned_expr(expr))) {
2026 expr = strip_expr(tmp);
2027 if (count++ > 4)
2028 break;
2029 }
2030
2031 if (expr->type != EXPR_BINOP || expr->op != '&')
2032 return NULL;
2033
2034 right = strip_expr(expr->right);
2035 param = get_param_num(right);
2036 if (param < 0 || param == ignore)
2037 return NULL;
2038
2039 snprintf(buf, sizeof(buf), "[<=$%d]", param);
2040 return alloc_sname(buf);
2041 }
2042
2043 static char *range_comparison_to_param_helper(struct expression *expr, char starts_with, int ignore)
2044 {
2045 struct symbol *param;
2046 char *var = NULL;
2047 char buf[256];
2048 char *ret_str = NULL;
2049 int compare;
2050 int i;
2051
2052 if (!expr)
2053 return NULL;
2054
2055 var = chunk_to_var(expr);
2056 if (!var)
2057 goto try_mask;
2058
2059 i = -1;
2060 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2061 i++;
2062 if (i == ignore)
2063 continue;
2064 if (!param->ident)
2065 continue;
2066 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2067 compare = get_comparison_strings(var, buf);
2068 if (compare == UNKNOWN_COMPARISON ||
2069 compare == IMPOSSIBLE_COMPARISON)
2070 continue;
2071 if (show_comparison(compare)[0] != starts_with)
2072 continue;
2073 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2074 ret_str = alloc_sname(buf);
2075 break;
2076 } END_FOR_EACH_PTR(param);
2077
2078 free_string(var);
2079 if (!ret_str)
2080 goto try_mask;
2081
2082 return ret_str;
2083
2084 try_mask:
2085 if (starts_with == '<')
2086 ret_str = get_mask_comparison(expr, ignore);
2087 return ret_str;
2088 }
2089
2090 char *name_sym_to_param_comparison(const char *name, struct symbol *sym)
2091 {
2092 struct symbol *param;
2093 char buf[256];
2094 int compare;
2095 int i;
2096
2097 i = -1;
2098 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2099 i++;
2100 if (!param->ident)
2101 continue;
2102 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2103 compare = get_comparison_strings(name, buf);
2104 if (compare == UNKNOWN_COMPARISON ||
2105 compare == IMPOSSIBLE_COMPARISON)
2106 continue;
2107 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2108 return alloc_sname(buf);
2109 } END_FOR_EACH_PTR(param);
2110
2111 return NULL;
2112 }
2113
2114 char *expr_equal_to_param(struct expression *expr, int ignore)
2115 {
2116 return range_comparison_to_param_helper(expr, '=', ignore);
2117 }
2118
2119 char *expr_lte_to_param(struct expression *expr, int ignore)
2120 {
2121 return range_comparison_to_param_helper(expr, '<', ignore);
2122 }
2123
2124 char *expr_param_comparison(struct expression *expr, int ignore)
2125 {
2126 struct symbol *param;
2127 char *var = NULL;
2128 char buf[256];
2129 char *ret_str = NULL;
2130 int compare;
2131 int i;
2132
2133 var = chunk_to_var(expr);
2134 if (!var)
2135 goto free;
2136
2137 i = -1;
2138 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2139 i++;
2140 if (i == ignore)
2141 continue;
2142 if (!param->ident)
2143 continue;
2144 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2145 compare = get_comparison_strings(var, buf);
2146 if (!compare)
2147 continue;
2148 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2149 ret_str = alloc_sname(buf);
2150 break;
2151 } END_FOR_EACH_PTR(param);
2152
2153 free:
2154 free_string(var);
2155 return ret_str;
2156 }
2157
2158 char *get_printed_param_name(struct expression *call, const char *param_name, struct symbol *param_sym)
2159 {
2160 struct expression *arg;
2161 char *name;
2162 struct symbol *sym;
2163 static char buf[256];
2164 int len;
2165 int i;
2166
2167 i = -1;
2168 FOR_EACH_PTR(call->args, arg) {
2169 i++;
2170
2171 name = expr_to_var_sym(arg, &sym);
2172 if (!name || !sym)
2173 continue;
2174 if (sym != param_sym)
2175 continue;
2176
2177 len = strlen(name);
2178 if (strncmp(name, param_name, len) != 0)
2179 continue;
2180 if (param_name[len] == '\0') {
2181 snprintf(buf, sizeof(buf), "$%d", i);
2182 return buf;
2183 }
2184 if (param_name[len] != '-')
2185 continue;
2186 snprintf(buf, sizeof(buf), "$%d%s", i, param_name + len);
2187 return buf;
2188 } END_FOR_EACH_PTR(arg);
2189
2190 return NULL;
2191 }
2192
2193 static void match_call_info(struct expression *expr)
2194 {
2195 struct expression *arg;
2196 struct smatch_state *state;
2197 struct sm_state *sm;
2198 struct compare_data *data;
2199 int comparison;
2200 struct string_list *links;
2201 char *arg_name;
2202 const char *right_name;
2203 char *link;
2204 char info_buf[256];
2205 int i;
2206
2207 i = -1;
2208 FOR_EACH_PTR(expr->args, arg) {
2209 i++;
2210
2211 state = get_state_chunk(link_id, arg);
2212 if (!state)
2213 continue;
2214
2215 links = state->data;
2216 FOR_EACH_PTR(links, link) {
2217 struct var_sym_list *right_vsl;
2218 struct var_sym *right_vs;
2219
2220
2221 if (strstr(link, " orig"))
2222 continue;
2223 sm = get_sm_state(comparison_id, link, NULL);
2224 if (!sm)
2225 continue;
2226 data = sm->state->data;
2227 if (!data ||
2228 data->comparison == UNKNOWN_COMPARISON ||
2229 data->comparison == IMPOSSIBLE_COMPARISON)
2230 continue;
2231 arg_name = expr_to_var(arg);
2232 if (!arg_name)
2233 continue;
2234
2235 right_vsl = NULL;
2236 if (strcmp(data->left_var, arg_name) == 0) {
2237 comparison = data->comparison;
2238 right_name = data->right_var;
2239 right_vsl = data->right_vsl;
2240 } else if (strcmp(data->right_var, arg_name) == 0) {
2241 comparison = flip_comparison(data->comparison);
2242 right_name = data->left_var;
2243 right_vsl = data->left_vsl;
2244 }
2245 if (!right_vsl || ptr_list_size((struct ptr_list *)right_vsl) != 1)
2246 goto free;
2247
2248 right_vs = first_ptr_list((struct ptr_list *)right_vsl);
2249 if (strcmp(right_vs->var, right_name) != 0)
2250 goto free;
2251 right_name = get_printed_param_name(expr, right_vs->var, right_vs->sym);
2252 if (!right_name)
2253 goto free;
2254 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(comparison), right_name);
2255 sql_insert_caller_info(expr, PARAM_COMPARE, i, "$", info_buf);
2256
2257 free:
2258 free_string(arg_name);
2259 } END_FOR_EACH_PTR(link);
2260 } END_FOR_EACH_PTR(arg);
2261 }
2262
2263 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *link_sm)
2264 {
2265 struct sm_state *compare_sm;
2266 struct string_list *links;
2267 char *link;
2268 struct compare_data *data;
2269 struct var_sym *left, *right;
2270 static char info_buf[256];
2271 const char *right_name;
2272
2273 if (strstr(printed_name, " orig"))
2274 return;
2275
2276 links = link_sm->state->data;
2277 FOR_EACH_PTR(links, link) {
2278 compare_sm = get_sm_state(comparison_id, link, NULL);
2279 if (!compare_sm)
2280 continue;
2281 data = compare_sm->state->data;
2282 if (!data || !data->comparison)
2283 continue;
2284
2285 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2286 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2287 continue;
2288 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2289 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2290 if (left->sym == right->sym &&
2291 strcmp(left->var, right->var) == 0)
2292 continue;
2293 /*
2294 * Both parameters link to this comparison so only
2295 * record the first one.
2296 */
2297 if (left->sym != link_sm->sym ||
2298 strcmp(left->var, link_sm->name) != 0)
2299 continue;
2300
2301 right_name = get_printed_param_name(call, right->var, right->sym);
2302 if (!right_name)
2303 continue;
2304 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_name);
2305 sql_insert_caller_info(call, PARAM_COMPARE, param, printed_name, info_buf);
2306 } END_FOR_EACH_PTR(link);
2307 }
2308
2309 static void print_return_value_comparison(int return_id, char *return_ranges, struct expression *expr)
2310 {
2311 char *name;
2312 const char *tmp_name;
2313 struct symbol *sym;
2314 int param;
2315 char info_buf[256];
2316 bool is_addr = false;
2317
2318 /*
2319 * TODO: This only prints == comparisons. That's probably the most
2320 * useful comparison because == max has lots of implications. But it
2321 * would be good to capture the rest as well.
2322 *
2323 * This information is already in the DB but it's in the parameter math
2324 * bits and it's awkward to use it. This is is the simpler, possibly
2325 * cleaner way, but not necessarily the best, I don't know.
2326 */
2327
2328 if (!expr)
2329 return;
2330 name = expr_to_var_sym(expr, &sym);
2331 if (!name || !sym)
2332 goto free;
2333
2334 param = get_param_num_from_sym(sym);
2335 if (param < 0)
2336 goto free;
2337 if (param_was_set_var_sym(name, sym))
2338 goto free;
2339
2340 tmp_name = get_param_name_var_sym(name, sym);
2341 if (!tmp_name)
2342 goto free;
2343
2344 if (tmp_name[0] == '&') {
2345 tmp_name += 2;
2346 is_addr = true;
2347 } else {
2348 tmp_name += 1;
2349 }
2350
2351 snprintf(info_buf, sizeof(info_buf), "== %s$%d%s", is_addr ? "&" : "", param, tmp_name);
2352 sql_insert_return_states(return_id, return_ranges,
2353 PARAM_COMPARE, -1, "$", info_buf);
2354 free:
2355 free_string(name);
2356 }
2357
2358 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
2359 {
2360 struct sm_state *tmp;
2361 struct string_list *links;
2362 char *link;
2363 struct sm_state *sm;
2364 struct compare_data *data;
2365 struct var_sym *left, *right;
2366 int left_param, right_param;
2367 char left_buf[256];
2368 char right_buf[256];
2369 char info_buf[258];
2370 const char *tmp_name;
2371
2372 print_return_value_comparison(return_id, return_ranges, expr);
2373
2374 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
2375 if (get_param_num_from_sym(tmp->sym) < 0)
2376 continue;
2377 links = tmp->state->data;
2378 FOR_EACH_PTR(links, link) {
2379 sm = get_sm_state(comparison_id, link, NULL);
2380 if (!sm)
2381 continue;
2382 data = sm->state->data;
2383 if (!data ||
2384 data->comparison == UNKNOWN_COMPARISON ||
2385 data->comparison == IMPOSSIBLE_COMPARISON)
2386 continue;
2387 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2388 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2389 continue;
2390 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2391 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2392 if (left->sym == right->sym &&
2393 strcmp(left->var, right->var) == 0)
2394 continue;
2395 /*
2396 * Both parameters link to this comparison so only
2397 * record the first one.
2398 */
2399 if (left->sym != tmp->sym ||
2400 strcmp(left->var, tmp->name) != 0)
2401 continue;
2402
2403 if (strstr(right->var, " orig"))
2404 continue;
2405
2406 left_param = get_param_num_from_sym(left->sym);
2407 right_param = get_param_num_from_sym(right->sym);
2408 if (left_param < 0 || right_param < 0)
2409 continue;
2410
2411 tmp_name = get_param_name_var_sym(left->var, left->sym);
2412 if (!tmp_name)
2413 continue;
2414 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
2415
2416 tmp_name = get_param_name_var_sym(right->var, right->sym);
2417 if (!tmp_name || tmp_name[0] != '$')
2418 continue;
2419 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
2420
2421 /*
2422 * FIXME: this should reject $ type variables (as
2423 * opposed to $->foo type). Those should come from
2424 * smatch_param_compare_limit.c.
2425 */
2426
2427 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_buf);
2428 sql_insert_return_states(return_id, return_ranges,
2429 PARAM_COMPARE, left_param, left_buf, info_buf);
2430 } END_FOR_EACH_PTR(link);
2431
2432 } END_FOR_EACH_SM(tmp);
2433 }
2434
2435 static int parse_comparison(char **value, int *op)
2436 {
2437
2438 *op = **value;
2439
2440 switch (*op) {
2441 case '<':
2442 (*value)++;
2443 if (**value == '=') {
2444 (*value)++;
2445 *op = SPECIAL_LTE;
2446 }
2447 break;
2448 case '=':
2449 (*value)++;
2450 (*value)++;
2451 *op = SPECIAL_EQUAL;
2452 break;
2453 case '!':
2454 (*value)++;
2455 (*value)++;
2456 *op = SPECIAL_NOTEQUAL;
2457 break;
2458 case '>':
2459 (*value)++;
2460 if (**value == '=') {
2461 (*value)++;
2462 *op = SPECIAL_GTE;
2463 }
2464 break;
2465 default:
2466 return 0;
2467 }
2468
2469 if (**value != ' ') {
2470 sm_perror("parsing comparison. %s", *value);
2471 return 0;
2472 }
2473
2474 (*value)++;
2475 return 1;
2476 }
2477
2478 static int split_op_param_key(char *value, int *op, int *param, char **key)
2479 {
2480 static char buf[256];
2481 char *p;
2482
2483 if (!parse_comparison(&value, op))
2484 return 0;
2485
2486 snprintf(buf, sizeof(buf), "%s", value);
2487
2488 p = buf;
2489 if (*p++ != '$')
2490 return 0;
2491
2492 *param = atoi(p);
2493 if (*param < 0 || *param > 99)
2494 return 0;
2495 p++;
2496 if (*param > 9)
2497 p++;
2498 p--;
2499 *p = '$';
2500 *key = p;
2501
2502 return 1;
2503 }
2504
2505 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
2506 {
2507 struct expression *left_arg, *right_arg;
2508 char *left_name = NULL;
2509 struct symbol *left_sym;
2510 char *right_name = NULL;
2511 struct symbol *right_sym;
2512 int op;
2513 int right_param;
2514 char *right_key;
2515 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
2516
2517 if (left_param == -1) {
2518 if (expr->type != EXPR_ASSIGNMENT)
2519 return;
2520 left_arg = strip_expr(expr->left);
2521
2522 while (expr->type == EXPR_ASSIGNMENT)
2523 expr = strip_expr(expr->right);
2524 if (expr->type != EXPR_CALL)
2525 return;
2526 } else {
2527 while (expr->type == EXPR_ASSIGNMENT)
2528 expr = strip_expr(expr->right);
2529 if (expr->type != EXPR_CALL)
2530 return;
2531
2532 left_arg = get_argument_from_call_expr(expr->args, left_param);
2533 if (!left_arg)
2534 return;
2535 }
2536
2537 if (!split_op_param_key(value, &op, &right_param, &right_key))
2538 return;
2539
2540 right_arg = get_argument_from_call_expr(expr->args, right_param);
2541 if (!right_arg)
2542 return;
2543
2544 left_name = get_variable_from_key(left_arg, key, &left_sym);
2545 if (!left_name || !left_sym)
2546 goto free;
2547
2548 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2549 if (!right_name || !right_sym)
2550 goto free;
2551
2552 add_var_sym(&left_vsl, left_name, left_sym);
2553 add_var_sym(&right_vsl, right_name, right_sym);
2554
2555 add_comparison_var_sym(NULL, left_name, left_vsl, op, NULL, right_name, right_vsl);
2556
2557 free:
2558 free_string(left_name);
2559 free_string(right_name);
2560 }
2561
2562 int param_compare_limit_is_impossible(struct expression *expr, int left_param, char *left_key, char *value)
2563 {
2564 struct smatch_state *state;
2565 char *left_name = NULL;
2566 char *right_name = NULL;
2567 struct symbol *left_sym, *right_sym;
2568 struct expression *left_arg, *right_arg;
2569 int op, state_op;
2570 int right_param;
2571 char *right_key;
2572 int ret = 0;
2573 char buf[256];
2574
2575 while (expr->type == EXPR_ASSIGNMENT)
2576 expr = strip_expr(expr->right);
2577 if (expr->type != EXPR_CALL)
2578 return 0;
2579
2580 if (!split_op_param_key(value, &op, &right_param, &right_key))
2581 return 0;
2582
2583 left_arg = get_argument_from_call_expr(expr->args, left_param);
2584 if (!left_arg)
2585 return 0;
2586
2587 right_arg = get_argument_from_call_expr(expr->args, right_param);
2588 if (!right_arg)
2589 return 0;
2590
2591 left_name = get_variable_from_key(left_arg, left_key, &left_sym);
2592 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2593 if (!left_name || !right_name)
2594 goto free;
2595
2596 snprintf(buf, sizeof(buf), "%s vs %s", left_name, right_name);
2597 state = get_state(comparison_id, buf, NULL);
2598 if (!state)
2599 goto free;
2600 state_op = state_to_comparison(state);
2601 if (!state_op)
2602 goto free;
2603
2604 if (!comparison_intersection(remove_unsigned_from_comparison(state_op), op))
2605 ret = 1;
2606 free:
2607 free_string(left_name);
2608 free_string(right_name);
2609 return ret;
2610 }
2611
2612 int impossibly_high_comparison(struct expression *expr)
2613 {
2614 struct smatch_state *link_state;
2615 struct sm_state *sm;
2616 struct string_list *links;
2617 char *link;
2618 struct compare_data *data;
2619
2620 link_state = get_state_expr(link_id, expr);
2621 if (!link_state) {
2622 if (expr->type == EXPR_BINOP &&
2623 (impossibly_high_comparison(expr->left) ||
2624 impossibly_high_comparison(expr->right)))
2625 return 1;
2626 return 0;
2627 }
2628
2629 links = link_state->data;
2630 FOR_EACH_PTR(links, link) {
2631 sm = get_sm_state(comparison_id, link, NULL);
2632 if (!sm)
2633 continue;
2634 data = sm->state->data;
2635 if (!data)
2636 continue;
2637 if (!possibly_true(data->left, data->comparison, data->right))
2638 return 1;
2639 } END_FOR_EACH_PTR(link);
2640
2641 return 0;
2642 }
2643
2644 static void free_data(struct symbol *sym)
2645 {
2646 if (__inline_fn)
2647 return;
2648 clear_compare_data_alloc();
2649 }
2650
2651 void register_comparison(int id)
2652 {
2653 comparison_id = id;
2654 set_dynamic_states(comparison_id);
2655 add_hook(&save_start_states, AFTER_DEF_HOOK);
2656 add_unmatched_state_hook(comparison_id, unmatched_comparison);
2657 add_pre_merge_hook(comparison_id, &pre_merge_hook);
2658 add_merge_hook(comparison_id, &merge_compare_states);
2659 add_hook(&free_data, AFTER_FUNC_HOOK);
2660 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2661 add_split_return_callback(&print_return_comparison);
2662
2663 select_return_states_hook(PARAM_COMPARE, &db_return_comparison);
2664 add_hook(&match_preop, OP_HOOK);
2665 }
2666
2667 void register_comparison_late(int id)
2668 {
2669 add_hook(&match_assign, ASSIGNMENT_HOOK);
2670 }
2671
2672 void register_comparison_links(int id)
2673 {
2674 link_id = id;
2675 db_ignore_states(link_id);
2676 set_dynamic_states(link_id);
2677 add_merge_hook(link_id, &merge_links);
2678 add_modification_hook(link_id, &match_modify);
2679 add_modification_hook_late(link_id, match_inc_dec);
2680
2681 add_member_info_callback(link_id, struct_member_callback);
2682 }
2683
2684 void register_comparison_inc_dec(int id)
2685 {
2686 inc_dec_id = id;
2687 add_modification_hook_late(inc_dec_id, &iter_modify);
2688 }
2689
2690 void register_comparison_inc_dec_links(int id)
2691 {
2692 inc_dec_link_id = id;
2693 set_dynamic_states(inc_dec_link_id);
2694 set_up_link_functions(inc_dec_id, inc_dec_link_id);
2695 }
2696
2697 static struct sm_state *clone_partial_sm(struct sm_state *sm, int comparison)
2698 {
2699 struct compare_data *data;
2700 struct sm_state *clone;
2701 struct stree *stree;
2702
2703 data = sm->state->data;
2704
2705 clone = clone_sm(sm);
2706 clone->state = alloc_compare_state(data->left, data->left_var, data->left_vsl,
2707 comparison,
2708 data->right, data->right_var, data->right_vsl);
2709 free_slist(&clone->possible);
2710 add_possible_sm(clone, clone);
2711
2712 stree = clone_stree(sm->pool);
2713 overwrite_sm_state_stree(&stree, clone);
2714 clone->pool = stree;
2715
2716 return clone;
2717 }
2718
2719 static void create_fake_history(struct sm_state *sm, int op,
2720 struct state_list **true_stack,
2721 struct state_list **false_stack)
2722 {
2723 struct sm_state *true_sm, *false_sm;
2724 struct compare_data *data;
2725 int true_comparison;
2726 int false_comparison;
2727
2728 data = sm->state->data;
2729
2730 if (is_merged(sm) || sm->left || sm->right)
2731 return;
2732
2733 true_comparison = comparison_intersection(data->comparison, op);
2734 false_comparison = comparison_intersection(data->comparison, negate_comparison(op));
2735
2736 true_sm = clone_partial_sm(sm, true_comparison);
2737 false_sm = clone_partial_sm(sm, false_comparison);
2738
2739 sm->merged = 1;
2740 sm->left = true_sm;
2741 sm->right = false_sm;
2742
2743 add_ptr_list(true_stack, true_sm);
2744 add_ptr_list(false_stack, false_sm);
2745 }
2746
2747 static void filter_by_sm(struct sm_state *sm, int op,
2748 struct state_list **true_stack,
2749 struct state_list **false_stack,
2750 bool *useful)
2751 {
2752 struct compare_data *data;
2753 int is_true = 0;
2754 int is_false = 0;
2755
2756 if (!sm)
2757 return;
2758 data = sm->state->data;
2759 if (!data)
2760 goto split;
2761 if (data->comparison == IMPOSSIBLE_COMPARISON)
2762 return;
2763
2764 /*
2765 * We want to check that "data->comparison" is totally inside "op". So
2766 * if data->comparison is < and op is <= then that's true. Or if
2767 * data->comparison is == and op is <= then that's true. But if
2768 * data->comparison is <= and op is < than that's neither true nor
2769 * false.
2770 */
2771 if (data->comparison == comparison_intersection(data->comparison, op))
2772 is_true = 1;
2773 if (data->comparison == comparison_intersection(data->comparison, negate_comparison(op)))
2774 is_false = 1;
2775
2776 if (!is_true && !is_false && !is_merged(sm)) {
2777 create_fake_history(sm, op, true_stack, false_stack);
2778 return;
2779 }
2780
2781 if (debug_implied()) {
2782 sm_msg("%s: %s: op = '%s' negated '%s'. true_intersect = '%s' false_insersect = '%s' sm = '%s'",
2783 __func__,
2784 sm->state->name,
2785 alloc_sname(show_comparison(op)),
2786 alloc_sname(show_comparison(negate_comparison(op))),
2787 alloc_sname(show_comparison(comparison_intersection(data->comparison, op))),
2788 alloc_sname(show_comparison(comparison_intersection(data->comparison, negate_comparison(op)))),
2789 show_sm(sm));
2790 }
2791
2792 *useful = true;
2793 if (is_true)
2794 add_ptr_list(true_stack, sm);
2795 if (is_false)
2796 add_ptr_list(false_stack, sm);
2797 split:
2798 filter_by_sm(sm->left, op, true_stack, false_stack, useful);
2799 filter_by_sm(sm->right, op, true_stack, false_stack, useful);
2800 }
2801
2802 struct sm_state *comparison_implication_hook(struct expression *expr,
2803 struct state_list **true_stack,
2804 struct state_list **false_stack)
2805 {
2806 struct sm_state *sm;
2807 char *left, *right;
2808 int op;
2809 static char buf[256];
2810 bool useful = false;
2811
2812 if (expr->type != EXPR_COMPARE)
2813 return NULL;
2814
2815 op = expr->op;
2816
2817 left = expr_to_var(expr->left);
2818 right = expr_to_var(expr->right);
2819 if (!left || !right) {
2820 free_string(left);
2821 free_string(right);
2822 return NULL;
2823 }
2824
2825 if (strcmp(left, right) > 0) {
2826 char *tmp = left;
2827
2828 left = right;
2829 right = tmp;
2830 op = flip_comparison(op);
2831 }
2832
2833 snprintf(buf, sizeof(buf), "%s vs %s", left, right);
2834 sm = get_sm_state(comparison_id, buf, NULL);
2835 if (!sm)
2836 return NULL;
2837 if (!sm->merged)
2838 return NULL;
2839
2840 filter_by_sm(sm, op, true_stack, false_stack, &useful);
2841 if (!useful)
2842 return NULL;
2843
2844 if (debug_implied())
2845 sm_msg("implications from comparison: (%s)", show_sm(sm));
2846
2847 return sm;
2848 }
Static analysis for C