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function_hooks: fake an assignment when functions return "0-s32max[$0->bar]"
[smatch.git] / smatch_comparison.c
bloba7826b76e962a16a93bdd18f2f0e86d732bd2426
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 /* for handling for loops */
41 STATE(start);
42 STATE(incremented);
43
44 ALLOCATOR(compare_data, "compare data");
45
46 static struct symbol *vsl_to_sym(struct var_sym_list *vsl)
47 {
48 struct var_sym *vs;
49
50 if (!vsl)
51 return NULL;
52 if (ptr_list_size((struct ptr_list *)vsl) != 1)
53 return NULL;
54 vs = first_ptr_list((struct ptr_list *)vsl);
55 return vs->sym;
56 }
57
58 struct smatch_state *alloc_compare_state(
59 struct expression *left,
60 const char *left_var, struct var_sym_list *left_vsl,
61 int comparison,
62 struct expression *right,
63 const char *right_var, struct var_sym_list *right_vsl)
64 {
65 struct smatch_state *state;
66 struct compare_data *data;
67
68 state = __alloc_smatch_state(0);
69 state->name = alloc_sname(show_special(comparison));
70 data = __alloc_compare_data(0);
71 data->left = left;
72 data->left_var = alloc_sname(left_var);
73 data->left_vsl = clone_var_sym_list(left_vsl);
74 data->comparison = comparison;
75 data->right = right;
76 data->right_var = alloc_sname(right_var);
77 data->right_vsl = clone_var_sym_list(right_vsl);
78 state->data = data;
79 return state;
80 }
81
82 int state_to_comparison(struct smatch_state *state)
83 {
84 if (!state || !state->data)
85 return 0;
86 return ((struct compare_data *)state->data)->comparison;
87 }
88
89 /*
90 * flip_comparison() reverses the op left and right. So "x >= y" becomes "y <= x".
91 */
92 int flip_comparison(int op)
93 {
94 switch (op) {
95 case 0:
96 return 0;
97 case '<':
98 return '>';
99 case SPECIAL_UNSIGNED_LT:
100 return SPECIAL_UNSIGNED_GT;
101 case SPECIAL_LTE:
102 return SPECIAL_GTE;
103 case SPECIAL_UNSIGNED_LTE:
104 return SPECIAL_UNSIGNED_GTE;
105 case SPECIAL_EQUAL:
106 return SPECIAL_EQUAL;
107 case SPECIAL_NOTEQUAL:
108 return SPECIAL_NOTEQUAL;
109 case SPECIAL_GTE:
110 return SPECIAL_LTE;
111 case SPECIAL_UNSIGNED_GTE:
112 return SPECIAL_UNSIGNED_LTE;
113 case '>':
114 return '<';
115 case SPECIAL_UNSIGNED_GT:
116 return SPECIAL_UNSIGNED_LT;
117 default:
118 sm_msg("internal smatch bug. unhandled comparison %d", op);
119 return op;
120 }
121 }
122
123 int negate_comparison(int op)
124 {
125 switch (op) {
126 case 0:
127 return 0;
128 case '<':
129 return SPECIAL_GTE;
130 case SPECIAL_UNSIGNED_LT:
131 return SPECIAL_UNSIGNED_GTE;
132 case SPECIAL_LTE:
133 return '>';
134 case SPECIAL_UNSIGNED_LTE:
135 return SPECIAL_UNSIGNED_GT;
136 case SPECIAL_EQUAL:
137 return SPECIAL_NOTEQUAL;
138 case SPECIAL_NOTEQUAL:
139 return SPECIAL_EQUAL;
140 case SPECIAL_GTE:
141 return '<';
142 case SPECIAL_UNSIGNED_GTE:
143 return SPECIAL_UNSIGNED_LT;
144 case '>':
145 return SPECIAL_LTE;
146 case SPECIAL_UNSIGNED_GT:
147 return SPECIAL_UNSIGNED_LTE;
148 default:
149 sm_msg("internal smatch bug. unhandled comparison %d", op);
150 return op;
151 }
152 }
153
154 static int rl_comparison(struct range_list *left_rl, struct range_list *right_rl)
155 {
156 sval_t left_min, left_max, right_min, right_max;
157
158 if (!left_rl || !right_rl)
159 return 0;
160
161 left_min = rl_min(left_rl);
162 left_max = rl_max(left_rl);
163 right_min = rl_min(right_rl);
164 right_max = rl_max(right_rl);
165
166 if (left_min.value == left_max.value &&
167 right_min.value == right_max.value &&
168 left_min.value == right_min.value)
169 return SPECIAL_EQUAL;
170
171 if (sval_cmp(left_max, right_min) < 0)
172 return '<';
173 if (sval_cmp(left_max, right_min) == 0)
174 return SPECIAL_LTE;
175 if (sval_cmp(left_min, right_max) > 0)
176 return '>';
177 if (sval_cmp(left_min, right_max) == 0)
178 return SPECIAL_GTE;
179
180 return 0;
181 }
182
183 static struct range_list *get_orig_rl(struct var_sym_list *vsl)
184 {
185 struct symbol *sym;
186 struct smatch_state *state;
187
188 if (!vsl)
189 return NULL;
190 sym = vsl_to_sym(vsl);
191 if (!sym || !sym->ident)
192 return NULL;
193 state = get_orig_estate(sym->ident->name, sym);
194 return estate_rl(state);
195 }
196
197 static struct smatch_state *unmatched_comparison(struct sm_state *sm)
198 {
199 struct compare_data *data = sm->state->data;
200 struct range_list *left_rl, *right_rl;
201 int op;
202
203 if (!data)
204 return &undefined;
205
206 if (strstr(data->left_var, " orig"))
207 left_rl = get_orig_rl(data->left_vsl);
208 else if (!get_implied_rl_var_sym(data->left_var, vsl_to_sym(data->left_vsl), &left_rl))
209 return &undefined;
210 if (strstr(data->right_var, " orig"))
211 right_rl = get_orig_rl(data->right_vsl);
212 else if (!get_implied_rl_var_sym(data->right_var, vsl_to_sym(data->right_vsl), &right_rl))
213 return &undefined;
214
215
216 op = rl_comparison(left_rl, right_rl);
217 if (op)
218 return alloc_compare_state(
219 data->left, data->left_var, data->left_vsl,
220 op,
221 data->right, data->right_var, data->right_vsl);
222
223 return &undefined;
224 }
225
226 /* remove_unsigned_from_comparison() is obviously a hack. */
227 int remove_unsigned_from_comparison(int op)
228 {
229 switch (op) {
230 case SPECIAL_UNSIGNED_LT:
231 return '<';
232 case SPECIAL_UNSIGNED_LTE:
233 return SPECIAL_LTE;
234 case SPECIAL_UNSIGNED_GTE:
235 return SPECIAL_GTE;
236 case SPECIAL_UNSIGNED_GT:
237 return '>';
238 default:
239 return op;
240 }
241 }
242
243 /*
244 * This is for when you merge states "a < b" and "a == b", the result is that
245 * we can say for sure, "a <= b" after the merge.
246 */
247 int merge_comparisons(int one, int two)
248 {
249 int LT, EQ, GT;
250
251 if (!one || !two)
252 return 0;
253
254 one = remove_unsigned_from_comparison(one);
255 two = remove_unsigned_from_comparison(two);
256
257 if (one == two)
258 return one;
259
260 LT = EQ = GT = 0;
261
262 switch (one) {
263 case '<':
264 LT = 1;
265 break;
266 case SPECIAL_LTE:
267 LT = 1;
268 EQ = 1;
269 break;
270 case SPECIAL_EQUAL:
271 EQ = 1;
272 break;
273 case SPECIAL_GTE:
274 GT = 1;
275 EQ = 1;
276 break;
277 case '>':
278 GT = 1;
279 }
280
281 switch (two) {
282 case '<':
283 LT = 1;
284 break;
285 case SPECIAL_LTE:
286 LT = 1;
287 EQ = 1;
288 break;
289 case SPECIAL_EQUAL:
290 EQ = 1;
291 break;
292 case SPECIAL_GTE:
293 GT = 1;
294 EQ = 1;
295 break;
296 case '>':
297 GT = 1;
298 }
299
300 if (LT && EQ && GT)
301 return 0;
302 if (LT && EQ)
303 return SPECIAL_LTE;
304 if (LT && GT)
305 return SPECIAL_NOTEQUAL;
306 if (LT)
307 return '<';
308 if (EQ && GT)
309 return SPECIAL_GTE;
310 if (GT)
311 return '>';
312 return 0;
313 }
314
315 /*
316 * This is for if you have "a < b" and "b <= c". Or in other words,
317 * "a < b <= c". You would call this like get_combined_comparison('<', '<=').
318 * The return comparison would be '<'.
319 *
320 * This function is different from merge_comparisons(), for example:
321 * merge_comparison('<', '==') returns '<='
322 * get_combined_comparison('<', '==') returns '<'
323 */
324 int combine_comparisons(int left_compare, int right_compare)
325 {
326 int LT, EQ, GT;
327
328 left_compare = remove_unsigned_from_comparison(left_compare);
329 right_compare = remove_unsigned_from_comparison(right_compare);
330
331 LT = EQ = GT = 0;
332
333 switch (left_compare) {
334 case '<':
335 LT++;
336 break;
337 case SPECIAL_LTE:
338 LT++;
339 EQ++;
340 break;
341 case SPECIAL_EQUAL:
342 return right_compare;
343 case SPECIAL_GTE:
344 GT++;
345 EQ++;
346 break;
347 case '>':
348 GT++;
349 }
350
351 switch (right_compare) {
352 case '<':
353 LT++;
354 break;
355 case SPECIAL_LTE:
356 LT++;
357 EQ++;
358 break;
359 case SPECIAL_EQUAL:
360 return left_compare;
361 case SPECIAL_GTE:
362 GT++;
363 EQ++;
364 break;
365 case '>':
366 GT++;
367 }
368
369 if (LT == 2) {
370 if (EQ == 2)
371 return SPECIAL_LTE;
372 return '<';
373 }
374
375 if (GT == 2) {
376 if (EQ == 2)
377 return SPECIAL_GTE;
378 return '>';
379 }
380 return 0;
381 }
382
383 static int filter_comparison(int orig, int op)
384 {
385 if (orig == op)
386 return orig;
387
388 switch (orig) {
389 case 0:
390 return op;
391 case '<':
392 switch (op) {
393 case '<':
394 case SPECIAL_LTE:
395 case SPECIAL_NOTEQUAL:
396 return '<';
397 }
398 return 0;
399 case SPECIAL_LTE:
400 switch (op) {
401 case '<':
402 case SPECIAL_LTE:
403 case SPECIAL_EQUAL:
404 return op;
405 case SPECIAL_NOTEQUAL:
406 return '<';
407 }
408 return 0;
409 case SPECIAL_EQUAL:
410 switch (op) {
411 case SPECIAL_LTE:
412 case SPECIAL_EQUAL:
413 case SPECIAL_GTE:
414 case SPECIAL_UNSIGNED_LTE:
415 case SPECIAL_UNSIGNED_GTE:
416 return SPECIAL_EQUAL;
417 }
418 return 0;
419 case SPECIAL_NOTEQUAL:
420 switch (op) {
421 case '<':
422 case SPECIAL_LTE:
423 return '<';
424 case SPECIAL_UNSIGNED_LT:
425 case SPECIAL_UNSIGNED_LTE:
426 return SPECIAL_UNSIGNED_LT;
427 case SPECIAL_NOTEQUAL:
428 return op;
429 case '>':
430 case SPECIAL_GTE:
431 return '>';
432 case SPECIAL_UNSIGNED_GT:
433 case SPECIAL_UNSIGNED_GTE:
434 return SPECIAL_UNSIGNED_GT;
435 }
436 return 0;
437 case SPECIAL_GTE:
438 switch (op) {
439 case SPECIAL_LTE:
440 return SPECIAL_EQUAL;
441 case '>':
442 case SPECIAL_GTE:
443 case SPECIAL_EQUAL:
444 return op;
445 case SPECIAL_NOTEQUAL:
446 return '>';
447 }
448 return 0;
449 case '>':
450 switch (op) {
451 case '>':
452 case SPECIAL_GTE:
453 case SPECIAL_NOTEQUAL:
454 return '>';
455 }
456 return 0;
457 case SPECIAL_UNSIGNED_LT:
458 switch (op) {
459 case SPECIAL_UNSIGNED_LT:
460 case SPECIAL_UNSIGNED_LTE:
461 case SPECIAL_NOTEQUAL:
462 return SPECIAL_UNSIGNED_LT;
463 }
464 return 0;
465 case SPECIAL_UNSIGNED_LTE:
466 switch (op) {
467 case SPECIAL_UNSIGNED_LT:
468 case SPECIAL_UNSIGNED_LTE:
469 case SPECIAL_EQUAL:
470 return op;
471 case SPECIAL_NOTEQUAL:
472 return SPECIAL_UNSIGNED_LT;
473 case SPECIAL_UNSIGNED_GTE:
474 return SPECIAL_EQUAL;
475 }
476 return 0;
477 case SPECIAL_UNSIGNED_GTE:
478 switch (op) {
479 case SPECIAL_UNSIGNED_LTE:
480 return SPECIAL_EQUAL;
481 case SPECIAL_NOTEQUAL:
482 return SPECIAL_UNSIGNED_GT;
483 case SPECIAL_EQUAL:
484 case SPECIAL_UNSIGNED_GTE:
485 case SPECIAL_UNSIGNED_GT:
486 return op;
487 }
488 return 0;
489 case SPECIAL_UNSIGNED_GT:
490 switch (op) {
491 case SPECIAL_UNSIGNED_GT:
492 case SPECIAL_UNSIGNED_GTE:
493 case SPECIAL_NOTEQUAL:
494 return SPECIAL_UNSIGNED_GT;
495 }
496 return 0;
497 }
498 return 0;
499 }
500
501 struct smatch_state *merge_compare_states(struct smatch_state *s1, struct smatch_state *s2)
502 {
503 struct compare_data *data = s1->data;
504 int op;
505
506 op = merge_comparisons(state_to_comparison(s1), state_to_comparison(s2));
507 if (op)
508 return alloc_compare_state(
509 data->left, data->left_var, data->left_vsl,
510 op,
511 data->right, data->right_var, data->right_vsl);
512 return &undefined;
513 }
514
515 static struct smatch_state *alloc_link_state(struct string_list *links)
516 {
517 struct smatch_state *state;
518 static char buf[256];
519 char *tmp;
520 int i;
521
522 state = __alloc_smatch_state(0);
523
524 i = 0;
525 FOR_EACH_PTR(links, tmp) {
526 if (!i++) {
527 snprintf(buf, sizeof(buf), "%s", tmp);
528 } else {
529 append(buf, ", ", sizeof(buf));
530 append(buf, tmp, sizeof(buf));
531 }
532 } END_FOR_EACH_PTR(tmp);
533
534 state->name = alloc_sname(buf);
535 state->data = links;
536 return state;
537 }
538
539 static void save_start_states(struct statement *stmt)
540 {
541 struct symbol *param;
542 char orig[64];
543 char state_name[128];
544 struct smatch_state *state;
545 struct string_list *links;
546 char *link;
547
548 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
549 struct var_sym_list *left_vsl = NULL;
550 struct var_sym_list *right_vsl = NULL;
551
552 if (!param->ident)
553 continue;
554 snprintf(orig, sizeof(orig), "%s orig", param->ident->name);
555 snprintf(state_name, sizeof(state_name), "%s vs %s", param->ident->name, orig);
556 add_var_sym(&left_vsl, param->ident->name, param);
557 add_var_sym(&right_vsl, orig, param);
558 state = alloc_compare_state(
559 NULL, param->ident->name, left_vsl,
560 SPECIAL_EQUAL,
561 NULL, alloc_sname(orig), right_vsl);
562 set_state(compare_id, state_name, NULL, state);
563
564 link = alloc_sname(state_name);
565 links = NULL;
566 insert_string(&links, link);
567 state = alloc_link_state(links);
568 set_state(link_id, param->ident->name, param, state);
569 } END_FOR_EACH_PTR(param);
570 }
571
572 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
573 {
574 struct smatch_state *ret;
575 struct string_list *links;
576
577 links = combine_string_lists(s1->data, s2->data);
578 ret = alloc_link_state(links);
579 return ret;
580 }
581
582 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
583 {
584 struct smatch_state *old_state, *new_state;
585 struct string_list *links;
586 char *new;
587
588 old_state = get_state(link_id, var, sym);
589 if (old_state)
590 links = clone_str_list(old_state->data);
591 else
592 links = NULL;
593
594 new = alloc_sname(link);
595 insert_string(&links, new);
596
597 new_state = alloc_link_state(links);
598 set_state(link_id, var, sym, new_state);
599 }
600
601 static void match_inc(struct sm_state *sm)
602 {
603 struct string_list *links;
604 struct smatch_state *state;
605 char *tmp;
606 int flip;
607 int op;
608
609 links = sm->state->data;
610
611 FOR_EACH_PTR(links, tmp) {
612 state = get_state(compare_id, tmp, NULL);
613
614 flip = 0;
615 if (strncmp(sm->name, tmp, strlen(sm->name)) != 0 ||
616 tmp[strlen(sm->name)] != ' ')
617 flip = 1;
618
619 op = state_to_comparison(state);
620
621 switch (flip ? flip_comparison(op) : op) {
622 case SPECIAL_EQUAL:
623 case SPECIAL_GTE:
624 case SPECIAL_UNSIGNED_GTE:
625 case '>':
626 case SPECIAL_UNSIGNED_GT: {
627 struct compare_data *data = state->data;
628 struct smatch_state *new;
629
630 new = alloc_compare_state(
631 data->left, data->left_var, data->left_vsl,
632 flip ? '<' : '>',
633 data->right, data->right_var, data->right_vsl);
634 set_state(compare_id, tmp, NULL, new);
635 break;
636 }
637 default:
638 set_state(compare_id, tmp, NULL, &undefined);
639 }
640 } END_FOR_EACH_PTR(tmp);
641 }
642
643 static void match_dec(struct sm_state *sm)
644 {
645 struct string_list *links;
646 struct smatch_state *state;
647 char *tmp;
648
649 links = sm->state->data;
650
651 FOR_EACH_PTR(links, tmp) {
652 state = get_state(compare_id, tmp, NULL);
653
654 switch (state_to_comparison(state)) {
655 case SPECIAL_EQUAL:
656 case SPECIAL_LTE:
657 case SPECIAL_UNSIGNED_LTE:
658 case '<':
659 case SPECIAL_UNSIGNED_LT: {
660 struct compare_data *data = state->data;
661 struct smatch_state *new;
662
663 new = alloc_compare_state(
664 data->left, data->left_var, data->left_vsl,
665 '<',
666 data->right, data->right_var, data->right_vsl);
667 set_state(compare_id, tmp, NULL, new);
668 break;
669 }
670 default:
671 set_state(compare_id, tmp, NULL, &undefined);
672 }
673 } END_FOR_EACH_PTR(tmp);
674 }
675
676 static int match_inc_dec(struct sm_state *sm, struct expression *mod_expr)
677 {
678 if (!mod_expr)
679 return 0;
680 if (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP)
681 return 0;
682
683 if (mod_expr->op == SPECIAL_INCREMENT) {
684 match_inc(sm);
685 return 1;
686 }
687 if (mod_expr->op == SPECIAL_DECREMENT) {
688 match_dec(sm);
689 return 1;
690 }
691 return 0;
692 }
693
694 static void match_modify(struct sm_state *sm, struct expression *mod_expr)
695 {
696 struct string_list *links;
697 char *tmp;
698
699 /*
700 * if (foo > bar) then ++foo is also > bar.
701 */
702 if (match_inc_dec(sm, mod_expr))
703 return;
704
705 links = sm->state->data;
706
707 FOR_EACH_PTR(links, tmp) {
708 set_state(compare_id, tmp, NULL, &undefined);
709 } END_FOR_EACH_PTR(tmp);
710 set_state(link_id, sm->name, sm->sym, &undefined);
711 }
712
713 static char *chunk_to_var_sym(struct expression *expr, struct symbol **sym)
714 {
715 expr = strip_expr(expr);
716 if (!expr)
717 return NULL;
718 if (sym)
719 *sym = NULL;
720
721 if (expr->type == EXPR_PREOP &&
722 (expr->op == SPECIAL_INCREMENT ||
723 expr->op == SPECIAL_DECREMENT))
724 expr = strip_expr(expr->unop);
725
726 if (expr->type == EXPR_CALL) {
727 char buf[64];
728
729 snprintf(buf, sizeof(buf), "return %p", expr);
730 return alloc_string(buf);
731 }
732
733 return expr_to_chunk_sym_vsl(expr, sym, NULL);
734 }
735
736 static char *chunk_to_var(struct expression *expr)
737 {
738 return chunk_to_var_sym(expr, NULL);
739 }
740
741 static struct smatch_state *get_state_chunk(int owner, struct expression *expr)
742 {
743 char *name;
744 struct symbol *sym;
745 struct smatch_state *ret;
746
747 name = chunk_to_var_sym(expr, &sym);
748 if (!name)
749 return NULL;
750
751 ret = get_state(owner, name, sym);
752 free_string(name);
753 return ret;
754 }
755
756 static void save_link(struct expression *expr, char *link)
757 {
758 char *var;
759 struct symbol *sym;
760
761 expr = strip_expr(expr);
762 if (expr->type == EXPR_BINOP) {
763 char *chunk;
764
765 chunk = chunk_to_var(expr);
766 if (!chunk)
767 return;
768
769 save_link(expr->left, link);
770 save_link(expr->right, link);
771 save_link_var_sym(chunk, NULL, link);
772 return;
773 }
774
775 var = chunk_to_var_sym(expr, &sym);
776 if (!var)
777 return;
778
779 save_link_var_sym(var, sym, link);
780 free_string(var);
781 }
782
783 static int get_orig_comparison(struct stree *pre_stree, const char *left, const char *right)
784 {
785 struct smatch_state *state;
786 struct compare_data *data;
787 int flip = 0;
788 char state_name[256];
789
790 if (strcmp(left, right) > 0) {
791 const char *tmp = right;
792
793 flip = 1;
794 right = left;
795 left = tmp;
796 }
797
798 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
799 state = get_state_stree(pre_stree, compare_id, state_name, NULL);
800 if (!state || !state->data)
801 return 0;
802 data = state->data;
803 if (flip)
804 return flip_comparison(data->comparison);
805 return data->comparison;
806
807 }
808
809 static int have_common_var_sym(struct var_sym_list *left_vsl, struct var_sym_list *right_vsl)
810 {
811 struct var_sym *tmp;
812
813 FOR_EACH_PTR(left_vsl, tmp) {
814 if (in_var_sym_list(right_vsl, tmp->var, tmp->sym))
815 return 1;
816 } END_FOR_EACH_PTR(tmp);
817
818 return 0;
819 }
820
821 /*
822 * The idea here is that we take a comparison "a < b" and then we look at all
823 * the things which "b" is compared against "b < c" and we say that that implies
824 * a relationship "a < c".
825 *
826 * The names here about because the comparisons are organized like this
827 * "a < b < c".
828 *
829 */
830 static void update_tf_links(struct stree *pre_stree,
831 struct expression *left_expr,
832 const char *left_var, struct var_sym_list *left_vsl,
833 int left_comparison, int left_false_comparison,
834 const char *mid_var, struct var_sym_list *mid_vsl,
835 struct string_list *links)
836 {
837 struct smatch_state *state;
838 struct smatch_state *true_state, *false_state;
839 struct compare_data *data;
840 struct expression *right_expr;
841 const char *right_var;
842 struct var_sym_list *right_vsl;
843 int orig_comparison;
844 int right_comparison;
845 int true_comparison;
846 int false_comparison;
847 char *tmp;
848 char state_name[256];
849 struct var_sym *vs;
850
851 FOR_EACH_PTR(links, tmp) {
852 state = get_state_stree(pre_stree, compare_id, tmp, NULL);
853 if (!state || !state->data)
854 continue;
855 data = state->data;
856 right_comparison = data->comparison;
857 right_expr = data->right;
858 right_var = data->right_var;
859 right_vsl = data->right_vsl;
860 if (strcmp(mid_var, right_var) == 0) {
861 right_expr = data->left;
862 right_var = data->left_var;
863 right_vsl = data->left_vsl;
864 right_comparison = flip_comparison(right_comparison);
865 }
866 if (have_common_var_sym(left_vsl, right_vsl))
867 continue;
868
869 orig_comparison = get_orig_comparison(pre_stree, left_var, right_var);
870
871 true_comparison = combine_comparisons(left_comparison, right_comparison);
872 false_comparison = combine_comparisons(left_false_comparison, right_comparison);
873
874 true_comparison = filter_comparison(orig_comparison, true_comparison);
875 false_comparison = filter_comparison(orig_comparison, false_comparison);
876
877 if (strcmp(left_var, right_var) > 0) {
878 struct expression *tmp_expr = left_expr;
879 const char *tmp_var = left_var;
880 struct var_sym_list *tmp_vsl = left_vsl;
881
882 left_expr = right_expr;
883 left_var = right_var;
884 left_vsl = right_vsl;
885 right_expr = tmp_expr;
886 right_var = tmp_var;
887 right_vsl = tmp_vsl;
888 true_comparison = flip_comparison(true_comparison);
889 false_comparison = flip_comparison(false_comparison);
890 }
891
892 if (!true_comparison && !false_comparison)
893 continue;
894
895 if (true_comparison)
896 true_state = alloc_compare_state(
897 left_expr, left_var, left_vsl,
898 true_comparison,
899 right_expr, right_var, right_vsl);
900 else
901 true_state = NULL;
902 if (false_comparison)
903 false_state = alloc_compare_state(
904 left_expr, left_var, left_vsl,
905 false_comparison,
906 right_expr, right_var, right_vsl);
907 else
908 false_state = NULL;
909
910 snprintf(state_name, sizeof(state_name), "%s vs %s", left_var, right_var);
911 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
912 FOR_EACH_PTR(left_vsl, vs) {
913 save_link_var_sym(vs->var, vs->sym, state_name);
914 } END_FOR_EACH_PTR(vs);
915 FOR_EACH_PTR(right_vsl, vs) {
916 save_link_var_sym(vs->var, vs->sym, state_name);
917 } END_FOR_EACH_PTR(vs);
918 if (!vsl_to_sym(left_vsl))
919 save_link_var_sym(left_var, NULL, state_name);
920 if (!vsl_to_sym(right_vsl))
921 save_link_var_sym(right_var, NULL, state_name);
922 } END_FOR_EACH_PTR(tmp);
923 }
924
925 static void update_tf_data(struct stree *pre_stree,
926 struct expression *left_expr,
927 const char *left_name, struct var_sym_list *left_vsl,
928 struct expression *right_expr,
929 const char *right_name, struct var_sym_list *right_vsl,
930 int true_comparison, int false_comparison)
931 {
932 struct smatch_state *state;
933
934 state = get_state_stree(pre_stree, link_id, right_name, vsl_to_sym(right_vsl));
935 if (state)
936 update_tf_links(pre_stree, left_expr, left_name, left_vsl, true_comparison, false_comparison, right_name, right_vsl, state->data);
937
938 state = get_state_stree(pre_stree, link_id, left_name, vsl_to_sym(left_vsl));
939 if (state)
940 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);
941 }
942
943 static void iter_modify(struct sm_state *sm, struct expression *mod_expr)
944 {
945 if (sm->state != &start ||
946 !mod_expr ||
947 (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP) ||
948 mod_expr->op != SPECIAL_INCREMENT)
949 set_state(inc_dec_id, sm->name, sm->sym, &undefined);
950 else
951 set_state(inc_dec_id, sm->name, sm->sym, &incremented);
952 }
953
954 static void handle_for_loops(struct expression *expr, char *state_name, struct smatch_state *false_state)
955 {
956 sval_t sval;
957 char *iter_name, *cap_name;
958 struct symbol *iter_sym, *cap_sym;
959 struct compare_data *data;
960
961 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
962 return;
963
964 if (!__cur_stmt || !__prev_stmt)
965 return;
966 if (__cur_stmt->type != STMT_ITERATOR)
967 return;
968 if (__cur_stmt->iterator_pre_condition != expr)
969 return;
970
971 /* literals are handled in smatch_extra.c */
972 if (get_value(expr->right, &sval))
973 return;
974
975 /* First time checking the condition */
976 if (__prev_stmt == __cur_stmt->iterator_pre_statement) {
977 if (!get_implied_value(expr->left, &sval) ||
978 sval.value != 0)
979 return;
980
981 iter_name = expr_to_var_sym(expr->left, &iter_sym);
982 cap_name = expr_to_var_sym(expr->right, &cap_sym);
983 if (!iter_name || !cap_name || !iter_sym || !cap_sym) {
984 free_string(iter_name);
985 free_string(cap_name);
986 return;
987 }
988
989 set_state(inc_dec_id, iter_name, iter_sym, &start);
990 store_link(inc_dec_link_id, cap_name, cap_sym, iter_name, iter_sym);
991
992 free_string(iter_name);
993 free_string(cap_name);
994 return;
995 }
996
997 /* Second time checking the condtion */
998 if (__prev_stmt != __cur_stmt->iterator_post_statement)
999 return;
1000
1001 if (get_state_chunk(inc_dec_id, expr->left) != &incremented)
1002 return;
1003
1004 data = false_state->data;
1005 false_state = alloc_compare_state(
1006 data->left, data->left_var, data->left_vsl,
1007 SPECIAL_EQUAL,
1008 data->right, data->right_var, data->right_vsl);
1009
1010 set_true_false_states(compare_id, state_name, NULL, NULL, false_state);
1011 }
1012
1013 static void handle_comparison(struct expression *left_expr, int op, struct expression *right_expr, char **_state_name, struct smatch_state **_false_state)
1014 {
1015 char *left = NULL;
1016 char *right = NULL;
1017 struct symbol *left_sym, *right_sym;
1018 struct var_sym_list *left_vsl, *right_vsl;
1019 int false_op;
1020 int orig_comparison;
1021 struct smatch_state *true_state, *false_state;
1022 static char state_name[256];
1023 struct stree *pre_stree;
1024 sval_t sval;
1025
1026 false_op = negate_comparison(op);
1027
1028 if (op == SPECIAL_UNSIGNED_LT &&
1029 get_implied_value(left_expr, &sval) &&
1030 sval.value == 0)
1031 false_op = SPECIAL_EQUAL;
1032
1033 if (op == SPECIAL_UNSIGNED_GT &&
1034 get_implied_value(right_expr, &sval) &&
1035 sval.value == 0)
1036 false_op = SPECIAL_EQUAL;
1037
1038 left = chunk_to_var_sym(left_expr, &left_sym);
1039 if (!left)
1040 goto free;
1041 left_vsl = expr_to_vsl(left_expr);
1042 right = chunk_to_var_sym(right_expr, &right_sym);
1043 if (!right)
1044 goto free;
1045 right_vsl = expr_to_vsl(right_expr);
1046
1047 if (strcmp(left, right) > 0) {
1048 struct symbol *tmp_sym = left_sym;
1049 char *tmp_name = left;
1050 struct var_sym_list *tmp_vsl = left_vsl;
1051 struct expression *tmp_expr = left_expr;
1052
1053 left = right;
1054 left_sym = right_sym;
1055 left_vsl = right_vsl;
1056 left_expr = right_expr;
1057 right = tmp_name;
1058 right_sym = tmp_sym;
1059 right_vsl = tmp_vsl;
1060 right_expr = tmp_expr;
1061 op = flip_comparison(op);
1062 false_op = flip_comparison(false_op);
1063 }
1064
1065 orig_comparison = get_comparison_strings(left, right);
1066 op = filter_comparison(orig_comparison, op);
1067 false_op = filter_comparison(orig_comparison, false_op);
1068
1069 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
1070 true_state = alloc_compare_state(
1071 left_expr, left, left_vsl,
1072 op,
1073 right_expr, right, right_vsl);
1074 false_state = alloc_compare_state(
1075 left_expr, left, left_vsl,
1076 false_op,
1077 right_expr, right, right_vsl);
1078
1079 pre_stree = clone_stree(__get_cur_stree());
1080 update_tf_data(pre_stree, left_expr, left, left_vsl, right_expr, right, right_vsl, op, false_op);
1081 free_stree(&pre_stree);
1082
1083 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
1084 __compare_param_limit_hook(left_expr, right_expr, state_name, true_state, false_state);
1085 save_link(left_expr, state_name);
1086 save_link(right_expr, state_name);
1087
1088 if (_false_state)
1089 *_false_state = false_state;
1090 if (_state_name)
1091 *_state_name = state_name;
1092 free:
1093 free_string(left);
1094 free_string(right);
1095
1096 }
1097
1098 void __comparison_match_condition(struct expression *expr)
1099 {
1100 struct expression *left, *right, *new_left, *new_right;
1101 struct smatch_state *false_state = NULL;
1102 char *state_name = NULL;
1103
1104 if (expr->type != EXPR_COMPARE)
1105 return;
1106
1107 handle_comparison(expr->left, expr->op, expr->right, &state_name, &false_state);
1108 if (false_state && state_name)
1109 handle_for_loops(expr, state_name, false_state);
1110
1111
1112 left = strip_parens(expr->left);
1113 right = strip_parens(expr->right);
1114
1115 if (left->type == EXPR_BINOP && left->op == '+') {
1116 new_left = left->left;
1117 new_right = binop_expression(right, '-', left->right);
1118 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1119
1120 new_left = left->right;
1121 new_right = binop_expression(right, '-', left->left);
1122 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1123 }
1124 }
1125
1126 static void add_comparison_var_sym(
1127 struct expression *left_expr,
1128 const char *left_name, struct var_sym_list *left_vsl,
1129 int comparison,
1130 struct expression *right_expr,
1131 const char *right_name, struct var_sym_list *right_vsl)
1132 {
1133 struct smatch_state *state;
1134 struct var_sym *vs;
1135 char state_name[256];
1136
1137 if (strcmp(left_name, right_name) > 0) {
1138 struct expression *tmp_expr = left_expr;
1139 const char *tmp_name = left_name;
1140 struct var_sym_list *tmp_vsl = left_vsl;
1141
1142 left_expr = right_expr;
1143 left_name = right_name;
1144 left_vsl = right_vsl;
1145 right_expr = tmp_expr;
1146 right_name = tmp_name;
1147 right_vsl = tmp_vsl;
1148 comparison = flip_comparison(comparison);
1149 }
1150 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1151 state = alloc_compare_state(
1152 left_expr, left_name, left_vsl,
1153 comparison,
1154 right_expr, right_name, right_vsl);
1155
1156 set_state(compare_id, state_name, NULL, state);
1157
1158 FOR_EACH_PTR(left_vsl, vs) {
1159 save_link_var_sym(vs->var, vs->sym, state_name);
1160 } END_FOR_EACH_PTR(vs);
1161 FOR_EACH_PTR(right_vsl, vs) {
1162 save_link_var_sym(vs->var, vs->sym, state_name);
1163 } END_FOR_EACH_PTR(vs);
1164 }
1165
1166 static void add_comparison(struct expression *left, int comparison, struct expression *right)
1167 {
1168 char *left_name = NULL;
1169 char *right_name = NULL;
1170 struct symbol *left_sym, *right_sym;
1171 struct var_sym_list *left_vsl, *right_vsl;
1172 struct smatch_state *state;
1173 char state_name[256];
1174
1175 left_name = chunk_to_var_sym(left, &left_sym);
1176 if (!left_name)
1177 goto free;
1178 left_vsl = expr_to_vsl(left);
1179 right_name = chunk_to_var_sym(right, &right_sym);
1180 if (!right_name)
1181 goto free;
1182 right_vsl = expr_to_vsl(right);
1183
1184 if (strcmp(left_name, right_name) > 0) {
1185 struct expression *tmp_expr = left;
1186 struct symbol *tmp_sym = left_sym;
1187 char *tmp_name = left_name;
1188 struct var_sym_list *tmp_vsl = left_vsl;
1189
1190 left = right;
1191 left_name = right_name;
1192 left_sym = right_sym;
1193 left_vsl = right_vsl;
1194 right = tmp_expr;
1195 right_name = tmp_name;
1196 right_sym = tmp_sym;
1197 right_vsl = tmp_vsl;
1198 comparison = flip_comparison(comparison);
1199 }
1200 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1201 state = alloc_compare_state(
1202 left, left_name, left_vsl,
1203 comparison,
1204 right, right_name, right_vsl);
1205
1206 set_state(compare_id, state_name, NULL, state);
1207 save_link(left, state_name);
1208 save_link(right, state_name);
1209
1210 free:
1211 free_string(left_name);
1212 free_string(right_name);
1213 }
1214
1215 static void match_assign_add(struct expression *expr)
1216 {
1217 struct expression *right;
1218 struct expression *r_left, *r_right;
1219 sval_t left_tmp, right_tmp;
1220
1221 right = strip_expr(expr->right);
1222 r_left = strip_expr(right->left);
1223 r_right = strip_expr(right->right);
1224
1225 get_absolute_min(r_left, &left_tmp);
1226 get_absolute_min(r_right, &right_tmp);
1227
1228 if (left_tmp.value > 0)
1229 add_comparison(expr->left, '>', r_right);
1230 else if (left_tmp.value == 0)
1231 add_comparison(expr->left, SPECIAL_GTE, r_right);
1232
1233 if (right_tmp.value > 0)
1234 add_comparison(expr->left, '>', r_left);
1235 else if (right_tmp.value == 0)
1236 add_comparison(expr->left, SPECIAL_GTE, r_left);
1237 }
1238
1239 static void match_assign_sub(struct expression *expr)
1240 {
1241 struct expression *right;
1242 struct expression *r_left, *r_right;
1243 int comparison;
1244 sval_t min;
1245
1246 right = strip_expr(expr->right);
1247 r_left = strip_expr(right->left);
1248 r_right = strip_expr(right->right);
1249
1250 if (get_absolute_min(r_right, &min) && sval_is_negative(min))
1251 return;
1252
1253 comparison = get_comparison(r_left, r_right);
1254
1255 switch (comparison) {
1256 case '>':
1257 case SPECIAL_GTE:
1258 if (implied_not_equal(r_right, 0))
1259 add_comparison(expr->left, '>', r_left);
1260 else
1261 add_comparison(expr->left, SPECIAL_GTE, r_left);
1262 return;
1263 }
1264 }
1265
1266 static void match_assign_divide(struct expression *expr)
1267 {
1268 struct expression *right;
1269 struct expression *r_left, *r_right;
1270 sval_t min;
1271
1272 right = strip_expr(expr->right);
1273 r_left = strip_expr(right->left);
1274 r_right = strip_expr(right->right);
1275 if (!get_implied_min(r_right, &min) || min.value <= 1)
1276 return;
1277
1278 add_comparison(expr->left, '<', r_left);
1279 }
1280
1281 static void match_binop_assign(struct expression *expr)
1282 {
1283 struct expression *right;
1284
1285 right = strip_expr(expr->right);
1286 if (right->op == '+')
1287 match_assign_add(expr);
1288 if (right->op == '-')
1289 match_assign_sub(expr);
1290 if (right->op == '/')
1291 match_assign_divide(expr);
1292 }
1293
1294 static void copy_comparisons(struct expression *left, struct expression *right)
1295 {
1296 struct string_list *links;
1297 struct smatch_state *state;
1298 struct compare_data *data;
1299 struct symbol *left_sym, *right_sym;
1300 char *left_var = NULL;
1301 char *right_var = NULL;
1302 struct var_sym_list *left_vsl;
1303 struct expression *expr;
1304 const char *var;
1305 struct var_sym_list *vsl;
1306 int comparison;
1307 char *tmp;
1308
1309 left_var = chunk_to_var_sym(left, &left_sym);
1310 if (!left_var)
1311 goto done;
1312 left_vsl = expr_to_vsl(left);
1313 right_var = chunk_to_var_sym(right, &right_sym);
1314 if (!right_var)
1315 goto done;
1316
1317 state = get_state(link_id, right_var, right_sym);
1318 if (!state)
1319 return;
1320 links = state->data;
1321
1322 FOR_EACH_PTR(links, tmp) {
1323 state = get_state(compare_id, tmp, NULL);
1324 if (!state || !state->data)
1325 continue;
1326 data = state->data;
1327 comparison = data->comparison;
1328 expr = data->right;
1329 var = data->right_var;
1330 vsl = data->right_vsl;
1331 if (strcmp(var, right_var) == 0) {
1332 expr = data->left;
1333 var = data->left_var;
1334 vsl = data->left_vsl;
1335 comparison = flip_comparison(comparison);
1336 }
1337 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1338 } END_FOR_EACH_PTR(tmp);
1339
1340 done:
1341 free_string(right_var);
1342 }
1343
1344 static void match_assign(struct expression *expr)
1345 {
1346 struct expression *right;
1347
1348 if (expr->op != '=')
1349 return;
1350 if (__in_fake_assign || outside_of_function())
1351 return;
1352
1353 if (is_struct(expr->left))
1354 return;
1355
1356 copy_comparisons(expr->left, expr->right);
1357 add_comparison(expr->left, SPECIAL_EQUAL, expr->right);
1358
1359 right = strip_expr(expr->right);
1360 if (right->type == EXPR_BINOP)
1361 match_binop_assign(expr);
1362 }
1363
1364 int get_comparison_strings(const char *one, const char *two)
1365 {
1366 char buf[256];
1367 struct smatch_state *state;
1368 int invert = 0;
1369 int ret = 0;
1370
1371 if (strcmp(one, two) == 0)
1372 return SPECIAL_EQUAL;
1373
1374 if (strcmp(one, two) > 0) {
1375 const char *tmp = one;
1376
1377 one = two;
1378 two = tmp;
1379 invert = 1;
1380 }
1381
1382 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1383 state = get_state(compare_id, buf, NULL);
1384 if (state)
1385 ret = state_to_comparison(state);
1386
1387 if (invert)
1388 ret = flip_comparison(ret);
1389
1390 return ret;
1391 }
1392
1393 int get_comparison(struct expression *a, struct expression *b)
1394 {
1395 char *one = NULL;
1396 char *two = NULL;
1397 int ret = 0;
1398
1399 one = chunk_to_var(a);
1400 if (!one)
1401 goto free;
1402 two = chunk_to_var(b);
1403 if (!two)
1404 goto free;
1405
1406 ret = get_comparison_strings(one, two);
1407 free:
1408 free_string(one);
1409 free_string(two);
1410 return ret;
1411 }
1412
1413 int possible_comparison(struct expression *a, int comparison, struct expression *b)
1414 {
1415 char *one = NULL;
1416 char *two = NULL;
1417 int ret = 0;
1418 char buf[256];
1419 struct sm_state *sm;
1420 int saved;
1421
1422 one = chunk_to_var(a);
1423 if (!one)
1424 goto free;
1425 two = chunk_to_var(b);
1426 if (!two)
1427 goto free;
1428
1429
1430 if (strcmp(one, two) == 0 && comparison == SPECIAL_EQUAL) {
1431 ret = 1;
1432 goto free;
1433 }
1434
1435 if (strcmp(one, two) > 0) {
1436 char *tmp = one;
1437
1438 one = two;
1439 two = tmp;
1440 comparison = flip_comparison(comparison);
1441 }
1442
1443 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1444 sm = get_sm_state(compare_id, buf, NULL);
1445 if (!sm)
1446 goto free;
1447
1448 FOR_EACH_PTR(sm->possible, sm) {
1449 if (!sm->state->data)
1450 continue;
1451 saved = ((struct compare_data *)sm->state->data)->comparison;
1452 if (saved == comparison)
1453 ret = 1;
1454 if (comparison == SPECIAL_EQUAL &&
1455 (saved == SPECIAL_LTE ||
1456 saved == SPECIAL_GTE ||
1457 saved == SPECIAL_UNSIGNED_LTE ||
1458 saved == SPECIAL_UNSIGNED_GTE))
1459 ret = 1;
1460 if (ret == 1)
1461 goto free;
1462 } END_FOR_EACH_PTR(sm);
1463
1464 return ret;
1465 free:
1466 free_string(one);
1467 free_string(two);
1468 return ret;
1469 }
1470
1471 struct state_list *get_all_comparisons(struct expression *expr)
1472 {
1473 struct smatch_state *state;
1474 struct string_list *links;
1475 struct state_list *ret = NULL;
1476 struct sm_state *sm;
1477 char *tmp;
1478
1479 state = get_state_chunk(link_id, expr);
1480 if (!state)
1481 return NULL;
1482 links = state->data;
1483
1484 FOR_EACH_PTR(links, tmp) {
1485 sm = get_sm_state(compare_id, tmp, NULL);
1486 if (!sm)
1487 continue;
1488 // FIXME have to compare name with vsl
1489 add_ptr_list(&ret, sm);
1490 } END_FOR_EACH_PTR(tmp);
1491
1492 return ret;
1493 }
1494
1495 struct state_list *get_all_possible_equal_comparisons(struct expression *expr)
1496 {
1497 struct smatch_state *state;
1498 struct string_list *links;
1499 struct state_list *ret = NULL;
1500 struct sm_state *sm;
1501 char *tmp;
1502
1503 state = get_state_chunk(link_id, expr);
1504 if (!state)
1505 return NULL;
1506 links = state->data;
1507
1508 FOR_EACH_PTR(links, tmp) {
1509 sm = get_sm_state(compare_id, tmp, NULL);
1510 if (!sm)
1511 continue;
1512 if (!strchr(sm->state->name, '='))
1513 continue;
1514 if (strcmp(sm->state->name, "!=") == 0)
1515 continue;
1516 add_ptr_list(&ret, sm);
1517 } END_FOR_EACH_PTR(tmp);
1518
1519 return ret;
1520 }
1521
1522
1523 static void update_links_from_call(struct expression *left,
1524 int left_compare,
1525 struct expression *right)
1526 {
1527 struct string_list *links;
1528 struct smatch_state *state;
1529 struct compare_data *data;
1530 struct symbol *left_sym, *right_sym;
1531 char *left_var = NULL;
1532 char *right_var = NULL;
1533 struct var_sym_list *left_vsl;
1534 struct expression *expr;
1535 const char *var;
1536 struct var_sym_list *vsl;
1537 int comparison;
1538 char *tmp;
1539
1540 left_var = chunk_to_var_sym(left, &left_sym);
1541 if (!left_var)
1542 goto done;
1543 left_vsl = expr_to_vsl(left);
1544 right_var = chunk_to_var_sym(right, &right_sym);
1545 if (!right_var)
1546 goto done;
1547
1548 state = get_state(link_id, right_var, right_sym);
1549 if (!state)
1550 return;
1551 links = state->data;
1552
1553 FOR_EACH_PTR(links, tmp) {
1554 state = get_state(compare_id, tmp, NULL);
1555 if (!state || !state->data)
1556 continue;
1557 data = state->data;
1558 comparison = data->comparison;
1559 expr = data->right;
1560 var = data->right_var;
1561 vsl = data->right_vsl;
1562 if (strcmp(var, right_var) == 0) {
1563 expr = data->left;
1564 var = data->left_var;
1565 vsl = data->left_vsl;
1566 comparison = flip_comparison(comparison);
1567 }
1568 comparison = combine_comparisons(left_compare, comparison);
1569 if (!comparison)
1570 continue;
1571 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1572 } END_FOR_EACH_PTR(tmp);
1573
1574 done:
1575 free_string(right_var);
1576 }
1577
1578 void __add_return_comparison(struct expression *call, const char *range)
1579 {
1580 struct expression *arg;
1581 int comparison;
1582 char buf[4];
1583
1584 if (!str_to_comparison_arg(range, call, &comparison, &arg))
1585 return;
1586 snprintf(buf, sizeof(buf), "%s", show_special(comparison));
1587 update_links_from_call(call, comparison, arg);
1588 add_comparison(call, comparison, arg);
1589 }
1590
1591 void __add_comparison_info(struct expression *expr, struct expression *call, const char *range)
1592 {
1593 copy_comparisons(expr, call);
1594 }
1595
1596 static char *range_comparison_to_param_helper(struct expression *expr, char starts_with, int ignore)
1597 {
1598 struct symbol *param;
1599 char *var = NULL;
1600 char buf[256];
1601 char *ret_str = NULL;
1602 int compare;
1603 int i;
1604
1605 var = chunk_to_var(expr);
1606 if (!var)
1607 goto free;
1608
1609 i = -1;
1610 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
1611 i++;
1612 if (i == ignore)
1613 continue;
1614 if (!param->ident)
1615 continue;
1616 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
1617 compare = get_comparison_strings(var, buf);
1618 if (!compare)
1619 continue;
1620 if (show_special(compare)[0] != starts_with)
1621 continue;
1622 snprintf(buf, sizeof(buf), "[%s$%d]", show_special(compare), i);
1623 ret_str = alloc_sname(buf);
1624 break;
1625 } END_FOR_EACH_PTR(param);
1626
1627 free:
1628 free_string(var);
1629 return ret_str;
1630 }
1631
1632 char *name_sym_to_param_comparison(const char *name, struct symbol *sym)
1633 {
1634 struct symbol *param;
1635 char buf[256];
1636 int compare;
1637 int i;
1638
1639 i = -1;
1640 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
1641 i++;
1642 if (!param->ident)
1643 continue;
1644 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
1645 compare = get_comparison_strings(name, buf);
1646 if (!compare)
1647 continue;
1648 snprintf(buf, sizeof(buf), "[%s$%d]", show_special(compare), i);
1649 return alloc_sname(buf);
1650 } END_FOR_EACH_PTR(param);
1651
1652 return NULL;
1653 }
1654
1655 char *expr_equal_to_param(struct expression *expr, int ignore)
1656 {
1657 return range_comparison_to_param_helper(expr, '=', ignore);
1658 }
1659
1660 char *expr_lte_to_param(struct expression *expr, int ignore)
1661 {
1662 return range_comparison_to_param_helper(expr, '<', ignore);
1663 }
1664
1665 char *expr_param_comparison(struct expression *expr, int ignore)
1666 {
1667 struct symbol *param;
1668 char *var = NULL;
1669 char buf[256];
1670 char *ret_str = NULL;
1671 int compare;
1672 int i;
1673
1674 var = chunk_to_var(expr);
1675 if (!var)
1676 goto free;
1677
1678 i = -1;
1679 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
1680 i++;
1681 if (i == ignore)
1682 continue;
1683 if (!param->ident)
1684 continue;
1685 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
1686 compare = get_comparison_strings(var, buf);
1687 if (!compare)
1688 continue;
1689 snprintf(buf, sizeof(buf), "[%s$%d]", show_special(compare), i);
1690 ret_str = alloc_sname(buf);
1691 break;
1692 } END_FOR_EACH_PTR(param);
1693
1694 free:
1695 free_string(var);
1696 return ret_str;
1697 }
1698
1699 char *get_printed_param_name(struct expression *call, const char *param_name, struct symbol *param_sym)
1700 {
1701 struct expression *arg;
1702 char *name;
1703 struct symbol *sym;
1704 static char buf[256];
1705 int len;
1706 int i;
1707
1708 i = -1;
1709 FOR_EACH_PTR(call->args, arg) {
1710 i++;
1711
1712 name = expr_to_var_sym(arg, &sym);
1713 if (!name || !sym)
1714 continue;
1715 if (sym != param_sym)
1716 continue;
1717
1718 len = strlen(name);
1719 if (strncmp(name, param_name, len) != 0)
1720 continue;
1721 if (param_name[len] == '\0') {
1722 snprintf(buf, sizeof(buf), "$%d", i);
1723 return buf;
1724 }
1725 if (param_name[len] != '-')
1726 continue;
1727 snprintf(buf, sizeof(buf), "$%d%s", i, param_name + len);
1728 return buf;
1729 } END_FOR_EACH_PTR(arg);
1730
1731 return NULL;
1732 }
1733
1734 static void match_call_info(struct expression *expr)
1735 {
1736 struct expression *arg;
1737 struct smatch_state *state;
1738 struct sm_state *sm;
1739 struct compare_data *data;
1740 int comparison;
1741 struct string_list *links;
1742 char *arg_name;
1743 const char *right_name;
1744 char *link;
1745 char info_buf[256];
1746 int i;
1747
1748 i = -1;
1749 FOR_EACH_PTR(expr->args, arg) {
1750 i++;
1751
1752 state = get_state_chunk(link_id, arg);
1753 if (!state)
1754 continue;
1755
1756 links = state->data;
1757 FOR_EACH_PTR(links, link) {
1758 struct var_sym_list *right_vsl;
1759 struct var_sym *right_vs;
1760
1761
1762 if (strstr(link, " orig"))
1763 continue;
1764 sm = get_sm_state(compare_id, link, NULL);
1765 if (!sm)
1766 continue;
1767 data = sm->state->data;
1768 if (!data || !data->comparison)
1769 continue;
1770 arg_name = expr_to_var(arg);
1771 if (!arg_name)
1772 continue;
1773
1774 right_vsl = NULL;
1775 if (strcmp(data->left_var, arg_name) == 0) {
1776 comparison = data->comparison;
1777 right_name = data->right_var;
1778 right_vsl = data->right_vsl;
1779 } else if (strcmp(data->right_var, arg_name) == 0) {
1780 comparison = flip_comparison(data->comparison);
1781 right_name = data->left_var;
1782 right_vsl = data->left_vsl;
1783 }
1784 if (!right_vsl || ptr_list_size((struct ptr_list *)right_vsl) != 1)
1785 goto free;
1786
1787 right_vs = first_ptr_list((struct ptr_list *)right_vsl);
1788 if (strcmp(right_vs->var, right_name) != 0)
1789 goto free;
1790 right_name = get_printed_param_name(expr, right_vs->var, right_vs->sym);
1791 if (!right_name)
1792 goto free;
1793 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(comparison), right_name);
1794 sql_insert_caller_info(expr, PARAM_COMPARE, i, "$", info_buf);
1795
1796 free:
1797 free_string(arg_name);
1798 } END_FOR_EACH_PTR(link);
1799 } END_FOR_EACH_PTR(arg);
1800 }
1801
1802 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *link_sm)
1803 {
1804 struct sm_state *compare_sm;
1805 struct string_list *links;
1806 char *link;
1807 struct compare_data *data;
1808 struct var_sym *left, *right;
1809 static char info_buf[256];
1810 const char *right_name;
1811
1812 if (strstr(printed_name, " orig"))
1813 return;
1814
1815 links = link_sm->state->data;
1816 FOR_EACH_PTR(links, link) {
1817 compare_sm = get_sm_state(compare_id, link, NULL);
1818 if (!compare_sm)
1819 continue;
1820 data = compare_sm->state->data;
1821 if (!data || !data->comparison)
1822 continue;
1823
1824 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
1825 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
1826 continue;
1827 left = first_ptr_list((struct ptr_list *)data->left_vsl);
1828 right = first_ptr_list((struct ptr_list *)data->right_vsl);
1829 if (left->sym == right->sym &&
1830 strcmp(left->var, right->var) == 0)
1831 continue;
1832 /*
1833 * Both parameters link to this comparison so only
1834 * record the first one.
1835 */
1836 if (left->sym != link_sm->sym ||
1837 strcmp(left->var, link_sm->name) != 0)
1838 continue;
1839
1840 right_name = get_printed_param_name(call, right->var, right->sym);
1841 if (!right_name)
1842 continue;
1843 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_name);
1844 sql_insert_caller_info(call, PARAM_COMPARE, param, printed_name, info_buf);
1845 } END_FOR_EACH_PTR(link);
1846 }
1847
1848 static void print_return_value_comparison(int return_id, char *return_ranges, struct expression *expr)
1849 {
1850 char *name;
1851 const char *tmp_name;
1852 struct symbol *sym;
1853 int param;
1854 char info_buf[256];
1855
1856 /*
1857 * TODO: This only prints == comparisons. That's probably the most
1858 * useful comparison because == max has lots of implications. But it
1859 * would be good to capture the rest as well.
1860 *
1861 * This information is already in the DB but it's in the parameter math
1862 * bits and it's awkward to use it. This is is the simpler, possibly
1863 * cleaner way, but not necessarily the best, I don't know.
1864 */
1865
1866 if (!expr)
1867 return;
1868 name = expr_to_var_sym(expr, &sym);
1869 if (!name || !sym)
1870 goto free;
1871
1872 param = get_param_num_from_sym(sym);
1873 if (param < 0)
1874 goto free;
1875 if (param_was_set_var_sym(name, sym))
1876 goto free;
1877
1878 tmp_name = get_param_name_var_sym(name, sym);
1879 if (!tmp_name)
1880 goto free;
1881
1882 snprintf(info_buf, sizeof(info_buf), "== $%d%s", param, tmp_name + 1);
1883 sql_insert_return_states(return_id, return_ranges,
1884 PARAM_COMPARE, -1, "$", info_buf);
1885 free:
1886 free_string(name);
1887 }
1888
1889 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
1890 {
1891 struct sm_state *tmp;
1892 struct string_list *links;
1893 char *link;
1894 struct sm_state *sm;
1895 struct compare_data *data;
1896 struct var_sym *left, *right;
1897 int left_param, right_param;
1898 char left_buf[256];
1899 char right_buf[256];
1900 char info_buf[256];
1901 const char *tmp_name;
1902
1903 print_return_value_comparison(return_id, return_ranges, expr);
1904
1905 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
1906 if (get_param_num_from_sym(tmp->sym) < 0)
1907 continue;
1908 links = tmp->state->data;
1909 FOR_EACH_PTR(links, link) {
1910 sm = get_sm_state(compare_id, link, NULL);
1911 if (!sm)
1912 continue;
1913 data = sm->state->data;
1914 if (!data || !data->comparison)
1915 continue;
1916 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
1917 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
1918 continue;
1919 left = first_ptr_list((struct ptr_list *)data->left_vsl);
1920 right = first_ptr_list((struct ptr_list *)data->right_vsl);
1921 if (left->sym == right->sym &&
1922 strcmp(left->var, right->var) == 0)
1923 continue;
1924 /*
1925 * Both parameters link to this comparison so only
1926 * record the first one.
1927 */
1928 if (left->sym != tmp->sym ||
1929 strcmp(left->var, tmp->name) != 0)
1930 continue;
1931
1932 if (strstr(right->var, " orig"))
1933 continue;
1934
1935 left_param = get_param_num_from_sym(left->sym);
1936 right_param = get_param_num_from_sym(right->sym);
1937 if (left_param < 0 || right_param < 0)
1938 continue;
1939
1940 tmp_name = get_param_name_var_sym(left->var, left->sym);
1941 if (!tmp_name)
1942 continue;
1943 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
1944
1945 tmp_name = get_param_name_var_sym(right->var, right->sym);
1946 if (!tmp_name || tmp_name[0] != '$')
1947 continue;
1948 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
1949
1950 /*
1951 * FIXME: this should reject $ type variables (as
1952 * opposed to $->foo type). Those should come from
1953 * smatch_param_compare_limit.c.
1954 */
1955
1956 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_buf);
1957 sql_insert_return_states(return_id, return_ranges,
1958 PARAM_COMPARE, left_param, left_buf, info_buf);
1959 } END_FOR_EACH_PTR(link);
1960
1961 } END_FOR_EACH_SM(tmp);
1962 }
1963
1964 static int parse_comparison(char **value, int *op)
1965 {
1966
1967 *op = **value;
1968
1969 switch (*op) {
1970 case '<':
1971 (*value)++;
1972 if (**value == '=') {
1973 (*value)++;
1974 *op = SPECIAL_LTE;
1975 }
1976 break;
1977 case '=':
1978 (*value)++;
1979 (*value)++;
1980 *op = SPECIAL_EQUAL;
1981 break;
1982 case '!':
1983 (*value)++;
1984 (*value)++;
1985 *op = SPECIAL_NOTEQUAL;
1986 break;
1987 case '>':
1988 (*value)++;
1989 if (**value == '=') {
1990 (*value)++;
1991 *op = SPECIAL_GTE;
1992 }
1993 break;
1994 default:
1995 return 0;
1996 }
1997
1998 if (**value != ' ') {
1999 sm_msg("internal error parsing comparison. %s", *value);
2000 return 0;
2001 }
2002
2003 (*value)++;
2004 return 1;
2005 }
2006
2007 static int split_op_param_key(char *value, int *op, int *param, char **key)
2008 {
2009 static char buf[256];
2010 char *p;
2011
2012 if (!parse_comparison(&value, op))
2013 return 0;
2014
2015 snprintf(buf, sizeof(buf), value);
2016
2017 p = buf;
2018 if (*p++ != '$')
2019 return 0;
2020
2021 *param = atoi(p);
2022 if (*param < 0 || *param > 99)
2023 return 0;
2024 p++;
2025 if (*param > 9)
2026 p++;
2027 p--;
2028 *p = '$';
2029 *key = p;
2030
2031 return 1;
2032 }
2033
2034 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
2035 {
2036 struct expression *left_arg, *right_arg;
2037 char *left_name = NULL;
2038 struct symbol *left_sym;
2039 char *right_name = NULL;
2040 struct symbol *right_sym;
2041 int op;
2042 int right_param;
2043 char *right_key;
2044 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
2045
2046 if (left_param == -1) {
2047 if (expr->type != EXPR_ASSIGNMENT)
2048 return;
2049 left_arg = strip_expr(expr->left);
2050
2051 while (expr->type == EXPR_ASSIGNMENT)
2052 expr = strip_expr(expr->right);
2053 if (expr->type != EXPR_CALL)
2054 return;
2055 } else {
2056 while (expr->type == EXPR_ASSIGNMENT)
2057 expr = strip_expr(expr->right);
2058 if (expr->type != EXPR_CALL)
2059 return;
2060
2061 left_arg = get_argument_from_call_expr(expr->args, left_param);
2062 if (!left_arg)
2063 return;
2064 }
2065
2066 if (!split_op_param_key(value, &op, &right_param, &right_key))
2067 return;
2068
2069 right_arg = get_argument_from_call_expr(expr->args, right_param);
2070 if (!right_arg)
2071 return;
2072
2073 left_name = get_variable_from_key(left_arg, key, &left_sym);
2074 if (!left_name || !left_sym)
2075 goto free;
2076
2077 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2078 if (!right_name || !right_sym)
2079 goto free;
2080
2081 add_var_sym(&left_vsl, left_name, left_sym);
2082 add_var_sym(&right_vsl, right_name, right_sym);
2083
2084 add_comparison_var_sym(NULL, left_name, left_vsl, op, NULL, right_name, right_vsl);
2085
2086 free:
2087 free_string(left_name);
2088 free_string(right_name);
2089 }
2090
2091 int param_compare_limit_is_impossible(struct expression *expr, int left_param, char *left_key, char *value)
2092 {
2093 struct smatch_state *state;
2094 char *left_name = NULL;
2095 char *right_name = NULL;
2096 struct symbol *left_sym, *right_sym;
2097 struct expression *left_arg, *right_arg;
2098 int op, state_op;
2099 int right_param;
2100 char *right_key;
2101 int ret = 0;
2102 char buf[256];
2103
2104 while (expr->type == EXPR_ASSIGNMENT)
2105 expr = strip_expr(expr->right);
2106 if (expr->type != EXPR_CALL)
2107 return 0;
2108
2109 if (!split_op_param_key(value, &op, &right_param, &right_key))
2110 return 0;
2111
2112 left_arg = get_argument_from_call_expr(expr->args, left_param);
2113 if (!left_arg)
2114 return 0;
2115
2116 right_arg = get_argument_from_call_expr(expr->args, right_param);
2117 if (!right_arg)
2118 return 0;
2119
2120 left_name = get_variable_from_key(left_arg, left_key, &left_sym);
2121 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2122 if (!left_name || !right_name)
2123 goto free;
2124
2125 snprintf(buf, sizeof(buf), "%s vs %s", left_name, right_name);
2126 state = get_state(compare_id, buf, NULL);
2127 if (!state)
2128 goto free;
2129 state_op = state_to_comparison(state);
2130 if (!state_op)
2131 goto free;
2132
2133 if (!filter_comparison(remove_unsigned_from_comparison(state_op), op))
2134 ret = 1;
2135 free:
2136 free_string(left_name);
2137 free_string(right_name);
2138 return ret;
2139 }
2140
2141 static void free_data(struct symbol *sym)
2142 {
2143 if (__inline_fn)
2144 return;
2145 clear_compare_data_alloc();
2146 }
2147
2148 void register_comparison(int id)
2149 {
2150 compare_id = id;
2151 add_hook(&save_start_states, AFTER_DEF_HOOK);
2152 add_unmatched_state_hook(compare_id, unmatched_comparison);
2153 add_merge_hook(compare_id, &merge_compare_states);
2154 add_hook(&free_data, AFTER_FUNC_HOOK);
2155 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2156 add_split_return_callback(&print_return_comparison);
2157
2158 select_return_states_hook(PARAM_COMPARE, &db_return_comparison);
2159 }
2160
2161 void register_comparison_late(int id)
2162 {
2163 add_hook(&match_assign, ASSIGNMENT_HOOK);
2164 }
2165
2166 void register_comparison_links(int id)
2167 {
2168 link_id = id;
2169 add_merge_hook(link_id, &merge_links);
2170 add_modification_hook(link_id, &match_modify);
2171
2172 add_member_info_callback(link_id, struct_member_callback);
2173 }
2174
2175 void register_comparison_inc_dec(int id)
2176 {
2177 inc_dec_id = id;
2178 add_modification_hook_late(inc_dec_id, &iter_modify);
2179 }
2180
2181 void register_comparison_inc_dec_links(int id)
2182 {
2183 inc_dec_link_id = id;
2184 set_up_link_functions(inc_dec_id, inc_dec_link_id);
2185 }
2186
2187 static void filter_by_sm(struct sm_state *sm, int op,
2188 struct state_list **true_stack,
2189 struct state_list **false_stack)
2190 {
2191 struct compare_data *data;
2192 int istrue = 0;
2193 int isfalse = 0;
2194
2195 if (!sm)
2196 return;
2197 data = sm->state->data;
2198 if (!data) {
2199 if (sm->merged) {
2200 filter_by_sm(sm->left, op, true_stack, false_stack);
2201 filter_by_sm(sm->right, op, true_stack, false_stack);
2202 }
2203 return;
2204 }
2205
2206 if (data->comparison &&
2207 data->comparison == filter_comparison(data->comparison, op))
2208 istrue = 1;
2209
2210 if (data->comparison &&
2211 data->comparison == filter_comparison(data->comparison, negate_comparison(op)))
2212 isfalse = 1;
2213
2214 if (istrue)
2215 add_ptr_list(true_stack, sm);
2216 if (isfalse)
2217 add_ptr_list(false_stack, sm);
2218
2219 if (sm->merged) {
2220 filter_by_sm(sm->left, op, true_stack, false_stack);
2221 filter_by_sm(sm->right, op, true_stack, false_stack);
2222 }
2223 }
2224
2225 struct sm_state *comparison_implication_hook(struct expression *expr,
2226 struct state_list **true_stack,
2227 struct state_list **false_stack)
2228 {
2229 struct sm_state *sm;
2230 char *left, *right;
2231 int op;
2232 static char buf[256];
2233
2234 if (expr->type != EXPR_COMPARE)
2235 return NULL;
2236
2237 op = expr->op;
2238
2239 left = expr_to_var(expr->left);
2240 right = expr_to_var(expr->right);
2241 if (!left || !right) {
2242 free_string(left);
2243 free_string(right);
2244 return NULL;
2245 }
2246
2247 if (strcmp(left, right) > 0) {
2248 char *tmp = left;
2249
2250 left = right;
2251 right = tmp;
2252 op = flip_comparison(op);
2253 }
2254
2255 snprintf(buf, sizeof(buf), "%s vs %s", left, right);
2256 sm = get_sm_state(compare_id, buf, NULL);
2257 if (!sm)
2258 return NULL;
2259 if (!sm->merged)
2260 return NULL;
2261
2262 filter_by_sm(sm, op, true_stack, false_stack);
2263 if (!*true_stack && !*false_stack)
2264 return NULL;
2265
2266 return sm;
2267 }
Static analysis for C