1 /*
2 * Copyright (C) 2008 Dan Carpenter.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 *
17 * Copyright 2019 Joyent, Inc.
18 */
19
20 /*
21 * Imagine we have this code:
22 * foo = 1;
23 * if (bar)
24 * foo = 99;
25 * else
26 * frob();
27 * // <-- point #1
28 * if (foo == 99) // <-- point #2
29 * bar->baz; // <-- point #3
30 *
31 *
32 * At point #3 bar is non null and can be dereferenced.
33 *
34 * It's smatch_implied.c which sets bar to non null at point #2.
35 *
36 * At point #1 merge_slist() stores the list of states from both
37 * the true and false paths. On the true path foo == 99 and on
38 * the false path foo == 1. merge_slist() sets their pool
39 * list to show the other states which were there when foo == 99.
40 *
41 * When it comes to the if (foo == 99) the smatch implied hook
42 * looks for all the pools where foo was not 99. It makes a list
43 * of those.
44 *
45 * Then for bar (and all the other states) it says, ok bar is a
46 * merged state that came from these previous states. We'll
47 * chop out all the states where it came from a pool where
48 * foo != 99 and merge it all back together.
49 *
50 * That is the implied state of bar.
51 *
52 * merge_slist() sets up ->pool. An sm_state only has one ->pool and
53 * that is the pool where it was first set. The my pool gets set when
54 * code paths merge. States that have been set since the last merge do
55 * not have a ->pool.
56 * merge_sm_state() sets ->left and ->right. (These are the states which were
57 * merged to form the current state.)
58 * a pool: a pool is an slist that has been merged with another slist.
59 */
60
61 #include <time.h>
62 #include "smatch.h"
63 #include "smatch_slist.h"
64 #include "smatch_extra.h"
65
66 char *implied_debug_msg;
67
68 bool implications_off;
69
70 #define implied_debug 0
71 #define DIMPLIED(msg...) do { if (implied_debug) printf(msg); } while (0)
72
73 bool debug_implied(void)
74 {
75 if (option_debug)
76 return true;
77 return implied_debug;
78 }
79
80 /*
81 * tmp_range_list():
82 * It messes things up to free range list allocations. This helper fuction
83 * lets us reuse memory instead of doing new allocations.
84 */
85 static struct range_list *tmp_range_list(struct symbol *type, long long num)
86 {
87 static struct range_list *my_list = NULL;
88 static struct data_range *my_range;
89
90 __free_ptr_list((struct ptr_list **)&my_list);
91 my_range = alloc_range(ll_to_sval(num), ll_to_sval(num));
92 add_ptr_list(&my_list, my_range);
93 return my_list;
94 }
95
96 static const char *show_comparison(int op)
97 {
98 if (op == PARAM_LIMIT)
99 return "<lim>";
100 return show_special(op);
101 }
102
103 static void print_debug_tf(struct sm_state *sm, int istrue, int isfalse)
104 {
105 if (!implied_debug && !option_debug)
106 return;
107
108 if (istrue && isfalse) {
109 printf("%s: %d: does not exist.\n", show_sm(sm), sm->line);
110 } else if (istrue) {
111 printf("'%s = %s' from %d is true. %s[stree %d]\n", sm->name, show_state(sm->state),
112 sm->line, sm->merged ? "[merged]" : "[leaf]",
113 get_stree_id(sm->pool));
114 } else if (isfalse) {
115 printf("'%s = %s' from %d is false. %s[stree %d]\n", sm->name, show_state(sm->state),
116 sm->line,
117 sm->merged ? "[merged]" : "[leaf]",
118 get_stree_id(sm->pool));
119 } else {
120 printf("'%s = %s' from %d could be true or false. %s[stree %d]\n", sm->name,
121 show_state(sm->state), sm->line,
122 sm->merged ? "[merged]" : "[leaf]",
123 get_stree_id(sm->pool));
124 }
125 }
126
127 void split_comparison_helper(struct range_list *left_orig, int op, struct range_list *right_orig,
128 struct range_list **left_true_rl, struct range_list **left_false_rl)
129 {
130 if (op == PARAM_LIMIT) {
131 *left_true_rl = rl_intersection(left_orig, right_orig);
132 *left_false_rl = rl_filter(left_orig, right_orig);
133 return;
134 }
135
136 split_comparison_rl(left_orig, op, right_orig, left_true_rl, left_false_rl, NULL, NULL);
137 }
138
139 static int create_fake_history(struct sm_state *sm, int comparison, struct range_list *rl)
140 {
141 struct range_list *orig_rl;
142 struct range_list *true_rl, *false_rl;
143 struct stree *true_stree, *false_stree;
144 struct sm_state *true_sm, *false_sm;
145 sval_t sval;
146
147 if (is_merged(sm) || sm->left || sm->right)
148 return 0;
149 if (!rl_to_sval(rl, &sval))
150 return 0;
151 if (!estate_rl(sm->state))
152 return 0;
153
154 orig_rl = cast_rl(rl_type(rl), estate_rl(sm->state));
155 split_comparison_helper(orig_rl, comparison, rl, &true_rl, &false_rl);
156
157 true_rl = rl_truncate_cast(estate_type(sm->state), true_rl);
158 false_rl = rl_truncate_cast(estate_type(sm->state), false_rl);
159 if (is_whole_rl(true_rl) || is_whole_rl(false_rl) ||
160 !true_rl || !false_rl ||
161 rl_equiv(orig_rl, true_rl) || rl_equiv(orig_rl, false_rl) ||
162 rl_equiv(estate_rl(sm->state), true_rl) || rl_equiv(estate_rl(sm->state), false_rl))
163 return 0;
164
165 if (rl_intersection(true_rl, false_rl)) {
166 /*
167 * Normally these won't intersect, but one exception is when
168 * we're dealing with mtags. We have a long list of mtags and
169 * then negate the list. Now it's over the limit for mtag list
170 * length and we squash it down to 4096-ptr_max. So then it's
171 * possible for the true and false rl to overlap.
172 */
173 return 0;
174 }
175
176 if (implied_debug)
177 sm_msg("fake_history: %s vs %s. %s %s %s. --> T: %s F: %s",
178 sm->name, show_rl(rl), sm->state->name, show_comparison(comparison), show_rl(rl),
179 show_rl(true_rl), show_rl(false_rl));
180
181 true_sm = clone_sm(sm);
182 false_sm = clone_sm(sm);
183
184 true_sm->state = clone_partial_estate(sm->state, true_rl);
185 free_slist(&true_sm->possible);
186 add_possible_sm(true_sm, true_sm);
187 false_sm->state = clone_partial_estate(sm->state, false_rl);
188 free_slist(&false_sm->possible);
189 add_possible_sm(false_sm, false_sm);
190
191 true_stree = clone_stree(sm->pool);
192 false_stree = clone_stree(sm->pool);
193
194 overwrite_sm_state_stree(&true_stree, true_sm);
195 overwrite_sm_state_stree(&false_stree, false_sm);
196
197 true_sm->pool = true_stree;
198 false_sm->pool = false_stree;
199
200 sm->merged = 1;
201 sm->left = true_sm;
202 sm->right = false_sm;
203
204 return 1;
205 }
206
207 /*
208 * add_pool() adds a slist to *pools. If the slist has already been
209 * added earlier then it doesn't get added a second time.
210 */
211 void add_pool(struct state_list **pools, struct sm_state *new)
212 {
213 struct sm_state *tmp;
214
215 FOR_EACH_PTR(*pools, tmp) {
216 if (tmp->pool < new->pool)
217 continue;
218 else if (tmp->pool == new->pool) {
219 return;
220 } else {
221 INSERT_CURRENT(new, tmp);
222 return;
223 }
224 } END_FOR_EACH_PTR(tmp);
225 add_ptr_list(pools, new);
226 }
227
228 static int pool_in_pools(struct stree *pool,
229 const struct state_list *slist)
230 {
231 struct sm_state *tmp;
232
233 FOR_EACH_PTR(slist, tmp) {
234 if (!tmp->pool)
235 continue;
236 if (tmp->pool == pool)
237 return 1;
238 } END_FOR_EACH_PTR(tmp);
239 return 0;
240 }
241
242 static int remove_pool(struct state_list **pools, struct stree *remove)
243 {
244 struct sm_state *tmp;
245 int ret = 0;
246
247 FOR_EACH_PTR(*pools, tmp) {
248 if (tmp->pool == remove) {
249 DELETE_CURRENT_PTR(tmp);
250 ret = 1;
251 }
252 } END_FOR_EACH_PTR(tmp);
253
254 return ret;
255 }
256
257 static bool possibly_true_helper(struct range_list *var_rl, int comparison, struct range_list *rl)
258 {
259 if (comparison == PARAM_LIMIT) {
260 struct range_list *intersect;
261
262 intersect = rl_intersection(var_rl, rl);
263 if (intersect)
264 return true;
265 return false;
266 }
267 return possibly_true_rl(var_rl, comparison, rl);
268 }
269
270 static bool possibly_false_helper(struct range_list *var_rl, int comparison, struct range_list *rl)
271 {
272 if (comparison == PARAM_LIMIT) {
273 struct range_list *intersect;
274
275 intersect = rl_intersection(var_rl, rl);
276 if (!rl_equiv(var_rl, intersect))
277 return true;
278 return false;
279 }
280 return possibly_false_rl(var_rl, comparison, rl);
281 }
282
283 /*
284 * If 'foo' == 99 add it that pool to the true pools. If it's false, add it to
285 * the false pools. If we're not sure, then we don't add it to either.
286 */
287 static void do_compare(struct sm_state *sm, int comparison, struct range_list *rl,
288 struct state_list **true_stack,
289 struct state_list **maybe_stack,
290 struct state_list **false_stack,
291 int *mixed, struct sm_state *gate_sm)
292 {
293 int istrue;
294 int isfalse;
295 struct range_list *var_rl;
296
297 if (!sm->pool)
298 return;
299
300 var_rl = cast_rl(rl_type(rl), estate_rl(sm->state));
301
302 istrue = !possibly_false_helper(var_rl, comparison, rl);
303 isfalse = !possibly_true_helper(var_rl, comparison, rl);
304
305 print_debug_tf(sm, istrue, isfalse);
306
307 /* give up if we have borrowed implications (smatch_equiv.c) */
308 if (sm->sym != gate_sm->sym ||
309 strcmp(sm->name, gate_sm->name) != 0) {
310 if (mixed)
311 *mixed = 1;
312 }
313
314 if (mixed && !*mixed && !is_merged(sm) && !istrue && !isfalse) {
315 if (!create_fake_history(sm, comparison, rl))
316 *mixed = 1;
317 }
318
319 if (istrue)
320 add_pool(true_stack, sm);
321 else if (isfalse)
322 add_pool(false_stack, sm);
323 else
324 add_pool(maybe_stack, sm);
325 }
326
327 static int is_checked(struct state_list *checked, struct sm_state *sm)
328 {
329 struct sm_state *tmp;
330
331 FOR_EACH_PTR(checked, tmp) {
332 if (tmp == sm)
333 return 1;
334 } END_FOR_EACH_PTR(tmp);
335 return 0;
336 }
337
338 /*
339 * separate_pools():
340 * Example code: if (foo == 99) {
341 *
342 * Say 'foo' is a merged state that has many possible values. It is the combination
343 * of merges. separate_pools() iterates through the pools recursively and calls
344 * do_compare() for each time 'foo' was set.
345 */
346 static void __separate_pools(struct sm_state *sm, int comparison, struct range_list *rl,
347 struct state_list **true_stack,
348 struct state_list **maybe_stack,
349 struct state_list **false_stack,
350 struct state_list **checked, int *mixed, struct sm_state *gate_sm,
351 struct timeval *start_time)
352 {
353 int free_checked = 0;
354 struct state_list *checked_states = NULL;
355 struct timeval now, diff;
356
357 if (!sm)
358 return;
359
360 gettimeofday(&now, NULL);
361 timersub(&now, start_time, &diff);
362 if (diff.tv_sec >= 1) {
363 if (implied_debug) {
364 sm_msg("debug: %s: implications taking too long. (%s %s %s)",
365 __func__, sm->state->name, show_comparison(comparison), show_rl(rl));
366 }
367 if (mixed)
368 *mixed = 1;
369 }
370
371 if (checked == NULL) {
372 checked = &checked_states;
373 free_checked = 1;
374 }
375 if (is_checked(*checked, sm))
376 return;
377 add_ptr_list(checked, sm);
378
379 do_compare(sm, comparison, rl, true_stack, maybe_stack, false_stack, mixed, gate_sm);
380
381 __separate_pools(sm->left, comparison, rl, true_stack, maybe_stack, false_stack, checked, mixed, gate_sm, start_time);
382 __separate_pools(sm->right, comparison, rl, true_stack, maybe_stack, false_stack, checked, mixed, gate_sm, start_time);
383 if (free_checked)
384 free_slist(checked);
385 }
386
387 static void separate_pools(struct sm_state *sm, int comparison, struct range_list *rl,
388 struct state_list **true_stack,
389 struct state_list **false_stack,
390 struct state_list **checked, int *mixed)
391 {
392 struct state_list *maybe_stack = NULL;
393 struct sm_state *tmp;
394 struct timeval start_time;
395
396
397 gettimeofday(&start_time, NULL);
398 __separate_pools(sm, comparison, rl, true_stack, &maybe_stack, false_stack, checked, mixed, sm, &start_time);
399
400 if (implied_debug) {
401 struct sm_state *sm;
402
403 FOR_EACH_PTR(*true_stack, sm) {
404 sm_msg("TRUE %s [stree %d]", show_sm(sm), get_stree_id(sm->pool));
405 } END_FOR_EACH_PTR(sm);
406
407 FOR_EACH_PTR(maybe_stack, sm) {
408 sm_msg("MAYBE %s %s[stree %d]",
409 show_sm(sm), sm->merged ? "(merged) ": "", get_stree_id(sm->pool));
410 } END_FOR_EACH_PTR(sm);
411
412 FOR_EACH_PTR(*false_stack, sm) {
413 sm_msg("FALSE %s [stree %d]", show_sm(sm), get_stree_id(sm->pool));
414 } END_FOR_EACH_PTR(sm);
415 }
416 /* if it's a maybe then remove it */
417 FOR_EACH_PTR(maybe_stack, tmp) {
418 remove_pool(false_stack, tmp->pool);
419 remove_pool(true_stack, tmp->pool);
420 } END_FOR_EACH_PTR(tmp);
421
422 /* if it's both true and false remove it from both */
423 FOR_EACH_PTR(*true_stack, tmp) {
424 if (remove_pool(false_stack, tmp->pool))
425 DELETE_CURRENT_PTR(tmp);
426 } END_FOR_EACH_PTR(tmp);
427 }
428
429 static int sm_in_keep_leafs(struct sm_state *sm, const struct state_list *keep_gates)
430 {
431 struct sm_state *tmp, *old;
432
433 FOR_EACH_PTR(keep_gates, tmp) {
434 if (is_merged(tmp))
435 continue;
436 old = get_sm_state_stree(tmp->pool, sm->owner, sm->name, sm->sym);
437 if (!old)
438 continue;
439 if (old == sm)
440 return 1;
441 } END_FOR_EACH_PTR(tmp);
442 return 0;
443 }
444
445 static int going_too_slow(void)
446 {
447 static void *printed;
448
449 if (out_of_memory()) {
450 implications_off = true;
451 return 1;
452 }
453
454 if (!option_timeout || time_parsing_function() < option_timeout) {
455 implications_off = false;
456 return 0;
457 }
458
459 if (!__inline_fn && printed != cur_func_sym) {
460 if (!is_skipped_function())
461 sm_perror("turning off implications after %d seconds", option_timeout);
462 printed = cur_func_sym;
463 }
464 implications_off = true;
465 return 1;
466 }
467
468 static char *sm_state_info(struct sm_state *sm)
469 {
470 static char buf[512];
471 int n = 0;
472
473 n += snprintf(buf + n, sizeof(buf) - n, "[stree %d line %d] ",
474 get_stree_id(sm->pool), sm->line);
475 if (n >= sizeof(buf))
476 return buf;
477 n += snprintf(buf + n, sizeof(buf) - n, "%s ", show_sm(sm));
478 if (n >= sizeof(buf))
479 return buf;
480 n += snprintf(buf + n, sizeof(buf) - n, "left = %s [stree %d] ",
481 sm->left ? sm->left->state->name : "<none>",
482 sm->left ? get_stree_id(sm->left->pool) : -1);
483 if (n >= sizeof(buf))
484 return buf;
485 n += snprintf(buf + n, sizeof(buf) - n, "right = %s [stree %d]",
486 sm->right ? sm->right->state->name : "<none>",
487 sm->right ? get_stree_id(sm->right->pool) : -1);
488 return buf;
489 }
490
491 /*
492 * NOTE: If a state is in both the keep stack and the remove stack then that is
493 * a bug. Only add states which are definitely true or definitely false. If
494 * you have a leaf state that could be both true and false, then create a fake
495 * split history where one side is true and one side is false. Otherwise, if
496 * you can't do that, then don't add it to either list.
497 */
498 #define RECURSE_LIMIT 300
499 struct sm_state *filter_pools(struct sm_state *sm,
500 const struct state_list *remove_stack,
501 const struct state_list *keep_stack,
502 int *modified, int *recurse_cnt,
503 struct timeval *start, int *skip, int *bail)
504 {
505 struct sm_state *ret = NULL;
506 struct sm_state *left;
507 struct sm_state *right;
508 int removed = 0;
509 struct timeval now, diff;
510
511 if (!sm)
512 return NULL;
513 if (*bail)
514 return NULL;
515 gettimeofday(&now, NULL);
516 timersub(&now, start, &diff);
517 if (diff.tv_sec >= 3) {
518 DIMPLIED("%s: implications taking too long: %s\n", __func__, sm_state_info(sm));
519 *bail = 1;
520 return NULL;
521 }
522 if ((*recurse_cnt)++ > RECURSE_LIMIT) {
523 DIMPLIED("%s: recursed too far: %s\n", __func__, sm_state_info(sm));
524 *skip = 1;
525 return NULL;
526 }
527
528 if (pool_in_pools(sm->pool, remove_stack)) {
529 DIMPLIED("%s: remove: %s\n", __func__, sm_state_info(sm));
530 *modified = 1;
531 return NULL;
532 }
533
534 if (!is_merged(sm) || pool_in_pools(sm->pool, keep_stack) || sm_in_keep_leafs(sm, keep_stack)) {
535 DIMPLIED("%s: keep %s (%s, %s, %s): %s\n", __func__, sm->state->name,
536 is_merged(sm) ? "merged" : "not merged",
537 pool_in_pools(sm->pool, keep_stack) ? "not in keep pools" : "in keep pools",
538 sm_in_keep_leafs(sm, keep_stack) ? "reachable keep leaf" : "no keep leaf",
539 sm_state_info(sm));
540 return sm;
541 }
542
543 left = filter_pools(sm->left, remove_stack, keep_stack, &removed, recurse_cnt, start, skip, bail);
544 right = filter_pools(sm->right, remove_stack, keep_stack, &removed, recurse_cnt, start, skip, bail);
545 if (*bail || *skip)
546 return NULL;
547 if (!removed) {
548 DIMPLIED("%s: kept all: %s\n", __func__, sm_state_info(sm));
549 return sm;
550 }
551 *modified = 1;
552 if (!left && !right) {
553 DIMPLIED("%s: removed all: %s\n", __func__, sm_state_info(sm));
554 return NULL;
555 }
556
557 if (!left) {
558 ret = clone_sm(right);
559 ret->merged = 1;
560 ret->right = right;
561 ret->left = NULL;
562 } else if (!right) {
563 ret = clone_sm(left);
564 ret->merged = 1;
565 ret->left = left;
566 ret->right = NULL;
567 } else {
568 if (left->sym != sm->sym || strcmp(left->name, sm->name) != 0) {
569 left = clone_sm(left);
570 left->sym = sm->sym;
571 left->name = sm->name;
572 }
573 if (right->sym != sm->sym || strcmp(right->name, sm->name) != 0) {
574 right = clone_sm(right);
575 right->sym = sm->sym;
576 right->name = sm->name;
577 }
578 ret = merge_sm_states(left, right);
579 }
580
581 ret->pool = sm->pool;
582
583 DIMPLIED("%s: partial: %s\n", __func__, sm_state_info(sm));
584 return ret;
585 }
586
587 static struct stree *filter_stack(struct sm_state *gate_sm,
588 struct stree *pre_stree,
589 const struct state_list *remove_stack,
590 const struct state_list *keep_stack)
591 {
592 struct stree *ret = NULL;
593 struct sm_state *tmp;
594 struct sm_state *filtered_sm;
595 int modified;
596 int recurse_cnt;
597 struct timeval start;
598 int skip;
599 int bail = 0;
600
601 if (!remove_stack)
602 return NULL;
603
604 gettimeofday(&start, NULL);
605 FOR_EACH_SM(pre_stree, tmp) {
606 if (!tmp->merged || sm_in_keep_leafs(tmp, keep_stack))
607 continue;
608 modified = 0;
609 recurse_cnt = 0;
610 skip = 0;
611 filtered_sm = filter_pools(tmp, remove_stack, keep_stack, &modified, &recurse_cnt, &start, &skip, &bail);
612 if (going_too_slow())
613 return NULL;
614 if (bail)
615 return ret; /* Return the implications we figured out before time ran out. */
616
617
618 if (skip || !filtered_sm || !modified)
619 continue;
620 /* the assignments here are for borrowed implications */
621 filtered_sm->name = tmp->name;
622 filtered_sm->sym = tmp->sym;
623 avl_insert(&ret, filtered_sm);
624 } END_FOR_EACH_SM(tmp);
625 return ret;
626 }
627
628 static void separate_and_filter(struct sm_state *sm, int comparison, struct range_list *rl,
629 struct stree *pre_stree,
630 struct stree **true_states,
631 struct stree **false_states,
632 int *mixed)
633 {
634 struct state_list *true_stack = NULL;
635 struct state_list *false_stack = NULL;
636 struct timeval time_before;
637 struct timeval time_after;
638 int sec;
639
640 gettimeofday(&time_before, NULL);
641
642 DIMPLIED("checking implications: (%s (%s) %s %s)\n",
643 sm->name, sm->state->name, show_comparison(comparison), show_rl(rl));
644
645 if (!is_merged(sm)) {
646 DIMPLIED("%d '%s' from line %d is not merged.\n", get_lineno(), sm->name, sm->line);
647 return;
648 }
649
650 separate_pools(sm, comparison, rl, &true_stack, &false_stack, NULL, mixed);
651
652 DIMPLIED("filtering true stack.\n");
653 *true_states = filter_stack(sm, pre_stree, false_stack, true_stack);
654 DIMPLIED("filtering false stack.\n");
655 *false_states = filter_stack(sm, pre_stree, true_stack, false_stack);
656 free_slist(&true_stack);
657 free_slist(&false_stack);
658
659 gettimeofday(&time_after, NULL);
660 sec = time_after.tv_sec - time_before.tv_sec;
661 if (option_timeout && sec > option_timeout) {
662 sm_perror("Function too hairy. Ignoring implications after %d seconds.", sec);
663 }
664 }
665
666 static struct expression *get_last_expr(struct statement *stmt)
667 {
668 struct statement *last;
669
670 last = last_ptr_list((struct ptr_list *)stmt->stmts);
671 if (last->type == STMT_EXPRESSION)
672 return last->expression;
673
674 if (last->type == STMT_LABEL) {
675 if (last->label_statement &&
676 last->label_statement->type == STMT_EXPRESSION)
677 return last->label_statement->expression;
678 }
679
680 return NULL;
681 }
682
683 static struct expression *get_left_most_expr(struct expression *expr)
684 {
685 struct statement *compound;
686
687 compound = get_expression_statement(expr);
688 if (compound)
689 return get_last_expr(compound);
690
691 expr = strip_parens(expr);
692 if (expr->type == EXPR_ASSIGNMENT)
693 return get_left_most_expr(expr->left);
694 return expr;
695 }
696
697 static int is_merged_expr(struct expression *expr)
698 {
699 struct sm_state *sm;
700 sval_t dummy;
701
702 if (get_value(expr, &dummy))
703 return 0;
704 sm = get_sm_state_expr(SMATCH_EXTRA, expr);
705 if (!sm)
706 return 0;
707 if (is_merged(sm))
708 return 1;
709 return 0;
710 }
711
712 static void delete_gate_sm_equiv(struct stree **stree, const char *name, struct symbol *sym)
713 {
714 struct smatch_state *state;
715 struct relation *rel;
716
717 state = get_state(SMATCH_EXTRA, name, sym);
718 if (!state)
719 return;
720 FOR_EACH_PTR(estate_related(state), rel) {
721 delete_state_stree(stree, SMATCH_EXTRA, rel->name, rel->sym);
722 } END_FOR_EACH_PTR(rel);
723 }
724
725 static void delete_gate_sm(struct stree **stree, const char *name, struct symbol *sym)
726 {
727 delete_state_stree(stree, SMATCH_EXTRA, name, sym);
728 }
729
730 static int handle_comparison(struct expression *expr,
731 struct stree **implied_true,
732 struct stree **implied_false)
733 {
734 struct sm_state *sm = NULL;
735 struct range_list *rl = NULL;
736 struct expression *left;
737 struct expression *right;
738 struct symbol *type;
739 int comparison = expr->op;
740 int mixed = 0;
741
742 left = get_left_most_expr(expr->left);
743 right = get_left_most_expr(expr->right);
744
745 if (is_merged_expr(left)) {
746 sm = get_sm_state_expr(SMATCH_EXTRA, left);
747 get_implied_rl(right, &rl);
748 } else if (is_merged_expr(right)) {
749 sm = get_sm_state_expr(SMATCH_EXTRA, right);
750 get_implied_rl(left, &rl);
751 comparison = flip_comparison(comparison);
752 }
753
754 if (!rl || !sm)
755 return 0;
756
757 type = get_type(expr);
758 if (!type)
759 return 0;
760 if (type_positive_bits(rl_type(rl)) > type_positive_bits(type))
761 type = rl_type(rl);
762 if (type_positive_bits(type) < 31)
763 type = &int_ctype;
764 rl = cast_rl(type, rl);
765
766 separate_and_filter(sm, comparison, rl, __get_cur_stree(), implied_true, implied_false, &mixed);
767
768 delete_gate_sm_equiv(implied_true, sm->name, sm->sym);
769 delete_gate_sm_equiv(implied_false, sm->name, sm->sym);
770 if (mixed) {
771 delete_gate_sm(implied_true, sm->name, sm->sym);
772 delete_gate_sm(implied_false, sm->name, sm->sym);
773 }
774
775 return 1;
776 }
777
778 static int handle_zero_comparison(struct expression *expr,
779 struct stree **implied_true,
780 struct stree **implied_false)
781 {
782 struct symbol *sym;
783 char *name;
784 struct sm_state *sm;
785 int mixed = 0;
786 int ret = 0;
787
788 if (expr->type == EXPR_POSTOP)
789 expr = strip_expr(expr->unop);
790
791 if (expr->type == EXPR_ASSIGNMENT) {
792 /* most of the time ->pools will be empty here because we
793 just set the state, but if have assigned a conditional
794 function there are implications. */
795 expr = expr->left;
796 }
797
798 name = expr_to_var_sym(expr, &sym);
799 if (!name || !sym)
800 goto free;
801 sm = get_sm_state(SMATCH_EXTRA, name, sym);
802 if (!sm || !sm->merged)
803 goto free;
804
805 separate_and_filter(sm, SPECIAL_NOTEQUAL, tmp_range_list(estate_type(sm->state), 0), __get_cur_stree(), implied_true, implied_false, &mixed);
806 delete_gate_sm_equiv(implied_true, sm->name, sm->sym);
807 delete_gate_sm_equiv(implied_false, sm->name, sm->sym);
808 if (mixed) {
809 delete_gate_sm(implied_true, sm->name, sm->sym);
810 delete_gate_sm(implied_false, sm->name, sm->sym);
811 }
812
813 ret = 1;
814 free:
815 free_string(name);
816 return ret;
817 }
818
819 static int handled_by_comparison_hook(struct expression *expr,
820 struct stree **implied_true,
821 struct stree **implied_false)
822 {
823 struct sm_state *sm, *true_sm, *false_sm;
824 struct state_list *true_stack = NULL;
825 struct state_list *false_stack = NULL;
826 struct stree *pre_stree;
827
828 sm = comparison_implication_hook(expr, &true_stack, &false_stack);
829 if (!sm)
830 return 0;
831
832 pre_stree = clone_stree(__get_cur_stree());
833
834 *implied_true = filter_stack(sm, pre_stree, false_stack, true_stack);
835 *implied_false = filter_stack(sm, pre_stree, true_stack, false_stack);
836
837 true_sm = get_sm_state_stree(*implied_true, sm->owner, sm->name, sm->sym);
838 false_sm = get_sm_state_stree(*implied_false, sm->owner, sm->name, sm->sym);
839 if (true_sm && strcmp(true_sm->state->name, "unknown") == 0)
840 delete_state_stree(implied_true, sm->owner, sm->name, sm->sym);
841 if (false_sm && strcmp(false_sm->state->name, "unknown") == 0)
842 delete_state_stree(implied_false, sm->owner, sm->name, sm->sym);
843
844 free_stree(&pre_stree);
845 free_slist(&true_stack);
846 free_slist(&false_stack);
847
848 return 1;
849 }
850
851 static int handled_by_extra_states(struct expression *expr,
852 struct stree **implied_true,
853 struct stree **implied_false)
854 {
855 sval_t sval;
856
857 /* If the expression is known then it has no implications. */
858 if (get_implied_value(expr, &sval))
859 return true;
860
861 if (expr->type == EXPR_COMPARE)
862 return handle_comparison(expr, implied_true, implied_false);
863 else
864 return handle_zero_comparison(expr, implied_true, implied_false);
865 }
866
867 static int handled_by_parsed_conditions(struct expression *expr,
868 struct stree **implied_true,
869 struct stree **implied_false)
870 {
871 struct state_list *true_stack = NULL;
872 struct state_list *false_stack = NULL;
873 struct stree *pre_stree;
874 struct sm_state *sm;
875
876 sm = parsed_condition_implication_hook(expr, &true_stack, &false_stack);
877 if (!sm)
878 return 0;
879
880 pre_stree = clone_stree(__get_cur_stree());
881
882 *implied_true = filter_stack(sm, pre_stree, false_stack, true_stack);
883 *implied_false = filter_stack(sm, pre_stree, true_stack, false_stack);
884
885 free_stree(&pre_stree);
886 free_slist(&true_stack);
887 free_slist(&false_stack);
888
889 return 1;
890 }
891
892 static int handled_by_stored_conditions(struct expression *expr,
893 struct stree **implied_true,
894 struct stree **implied_false)
895 {
896 struct state_list *true_stack = NULL;
897 struct state_list *false_stack = NULL;
898 struct stree *pre_stree;
899 struct sm_state *sm;
900
901 sm = stored_condition_implication_hook(expr, &true_stack, &false_stack);
902 if (!sm)
903 return 0;
904
905 pre_stree = clone_stree(__get_cur_stree());
906
907 *implied_true = filter_stack(sm, pre_stree, false_stack, true_stack);
908 *implied_false = filter_stack(sm, pre_stree, true_stack, false_stack);
909
910 free_stree(&pre_stree);
911 free_slist(&true_stack);
912 free_slist(&false_stack);
913
914 return 1;
915 }
916
917 static struct stree *saved_implied_true;
918 static struct stree *saved_implied_false;
919 static struct stree *extra_saved_implied_true;
920 static struct stree *extra_saved_implied_false;
921
922 static void separate_implication_states(struct stree **implied_true,
923 struct stree **implied_false,
924 int owner)
925 {
926 struct sm_state *sm;
927
928 /* We process these states later to preserve the implications. */
929 FOR_EACH_SM(*implied_true, sm) {
930 if (sm->owner == owner)
931 overwrite_sm_state_stree(&extra_saved_implied_true, sm);
932 } END_FOR_EACH_SM(sm);
933 FOR_EACH_SM(extra_saved_implied_true, sm) {
934 delete_state_stree(implied_true, sm->owner, sm->name, sm->sym);
935 } END_FOR_EACH_SM(sm);
936
937 FOR_EACH_SM(*implied_false, sm) {
938 if (sm->owner == owner)
939 overwrite_sm_state_stree(&extra_saved_implied_false, sm);
940 } END_FOR_EACH_SM(sm);
941 FOR_EACH_SM(extra_saved_implied_false, sm) {
942 delete_state_stree(implied_false, sm->owner, sm->name, sm->sym);
943 } END_FOR_EACH_SM(sm);
944 }
945
946 static void get_tf_states(struct expression *expr,
947 struct stree **implied_true,
948 struct stree **implied_false)
949 {
950 if (handled_by_parsed_conditions(expr, implied_true, implied_false))
951 return;
952
953 if (handled_by_comparison_hook(expr, implied_true, implied_false)) {
954 separate_implication_states(implied_true, implied_false, comparison_id);
955 return;
956 }
957
958 if (handled_by_extra_states(expr, implied_true, implied_false)) {
959 separate_implication_states(implied_true, implied_false, SMATCH_EXTRA);
960 return;
961 }
962
963 if (handled_by_stored_conditions(expr, implied_true, implied_false))
964 return;
965 }
966
967 static void save_implications_hook(struct expression *expr)
968 {
969 if (going_too_slow())
970 return;
971 get_tf_states(expr, &saved_implied_true, &saved_implied_false);
972 }
973
974 static void set_implied_states(struct expression *expr)
975 {
976 struct sm_state *sm;
977
978 if (implied_debug &&
979 (expr || saved_implied_true || saved_implied_false)) {
980 char *name;
981
982 name = expr_to_str(expr);
983 printf("These are the implied states for the true path: (%s)\n", name);
984 __print_stree(saved_implied_true);
985 printf("These are the implied states for the false path: (%s)\n", name);
986 __print_stree(saved_implied_false);
987 free_string(name);
988 }
989
990 FOR_EACH_SM(saved_implied_true, sm) {
991 __set_true_false_sm(sm, NULL);
992 } END_FOR_EACH_SM(sm);
993 free_stree(&saved_implied_true);
994
995 FOR_EACH_SM(saved_implied_false, sm) {
996 __set_true_false_sm(NULL, sm);
997 } END_FOR_EACH_SM(sm);
998 free_stree(&saved_implied_false);
999 }
1000
1001 static void set_extra_implied_states(struct expression *expr)
1002 {
1003 saved_implied_true = extra_saved_implied_true;
1004 saved_implied_false = extra_saved_implied_false;
1005 extra_saved_implied_true = NULL;
1006 extra_saved_implied_false = NULL;
1007 set_implied_states(NULL);
1008 }
1009
1010 void param_limit_implications(struct expression *expr, int param, char *key, char *value, struct stree **implied)
1011 {
1012 struct expression *orig_expr, *arg;
1013 struct symbol *compare_type;
1014 char *name;
1015 struct symbol *sym;
1016 struct sm_state *sm;
1017 struct sm_state *tmp;
1018 struct stree *implied_true = NULL;
1019 struct stree *implied_false = NULL;
1020 struct range_list *orig, *limit;
1021 char *left_name = NULL;
1022 struct symbol *left_sym = NULL;
1023 int mixed = 0;
1024
1025 if (time_parsing_function() > 40)
1026 return;
1027
1028 orig_expr = expr;
1029 while (expr->type == EXPR_ASSIGNMENT)
1030 expr = strip_expr(expr->right);
1031 if (expr->type != EXPR_CALL)
1032 return;
1033
1034 arg = get_argument_from_call_expr(expr->args, param);
1035 if (!arg)
1036 return;
1037
1038 arg = strip_parens(arg);
1039 while (arg->type == EXPR_ASSIGNMENT && arg->op == '=')
1040 arg = strip_parens(arg->left);
1041
1042 name = get_variable_from_key(arg, key, &sym);
1043 if (!name || !sym)
1044 goto free;
1045
1046 sm = get_sm_state(SMATCH_EXTRA, name, sym);
1047 if (!sm || !sm->merged)
1048 goto free;
1049
1050 if (strcmp(key, "$") == 0)
1051 compare_type = get_arg_type(expr->fn, param);
1052 else
1053 compare_type = get_member_type_from_key(arg, key);
1054
1055 orig = estate_rl(sm->state);
1056 orig = cast_rl(compare_type, orig);
1057
1058 call_results_to_rl(expr, compare_type, value, &limit);
1059
1060 separate_and_filter(sm, PARAM_LIMIT, limit, __get_cur_stree(), &implied_true, &implied_false, &mixed);
1061
1062 if (orig_expr->type == EXPR_ASSIGNMENT)
1063 left_name = expr_to_var_sym(orig_expr->left, &left_sym);
1064
1065 FOR_EACH_SM(implied_true, tmp) {
1066 /*
1067 * What we're trying to do here is preserve the sm state so that
1068 * smatch extra doesn't create a new sm state when it parses the
1069 * PARAM_LIMIT.
1070 */
1071 if (!mixed && tmp->sym == sym &&
1072 strcmp(tmp->name, name) == 0 &&
1073 (!left_name || strcmp(left_name, name) != 0)) {
1074 overwrite_sm_state_stree(implied, tmp);
1075 continue;
1076 }
1077
1078 // TODO why can't this just be __set_sm()?
1079 __set_sm_fake_stree(tmp);
1080 } END_FOR_EACH_SM(tmp);
1081
1082 free_stree(&implied_true);
1083 free_stree(&implied_false);
1084 free:
1085 free_string(name);
1086 }
1087
1088 struct stree *__implied_case_stree(struct expression *switch_expr,
1089 struct range_list *rl,
1090 struct range_list_stack **remaining_cases,
1091 struct stree **raw_stree)
1092 {
1093 char *name;
1094 struct symbol *sym;
1095 struct var_sym_list *vsl;
1096 struct sm_state *sm;
1097 struct stree *true_states = NULL;
1098 struct stree *false_states = NULL;
1099 struct stree *extra_states;
1100 struct stree *ret = clone_stree(*raw_stree);
1101
1102 name = expr_to_chunk_sym_vsl(switch_expr, &sym, &vsl);
1103
1104 if (rl)
1105 filter_top_rl(remaining_cases, rl);
1106 else
1107 rl = clone_rl(top_rl(*remaining_cases));
1108
1109 if (name) {
1110 sm = get_sm_state_stree(*raw_stree, SMATCH_EXTRA, name, sym);
1111 if (sm)
1112 separate_and_filter(sm, SPECIAL_EQUAL, rl, *raw_stree, &true_states, &false_states, NULL);
1113 }
1114
1115 __push_fake_cur_stree();
1116 __unnullify_path();
1117 if (name)
1118 set_extra_nomod_vsl(name, sym, vsl, NULL, alloc_estate_rl(rl));
1119 __pass_case_to_client(switch_expr, rl);
1120 extra_states = __pop_fake_cur_stree();
1121 overwrite_stree(extra_states, &true_states);
1122 overwrite_stree(true_states, &ret);
1123 free_stree(&extra_states);
1124 free_stree(&true_states);
1125 free_stree(&false_states);
1126
1127 free_string(name);
1128 return ret;
1129 }
1130
1131 static void match_end_func(struct symbol *sym)
1132 {
1133 if (__inline_fn)
1134 return;
1135 implied_debug_msg = NULL;
1136 }
1137
1138 static void get_tf_stacks_from_pool(struct sm_state *gate_sm,
1139 struct sm_state *pool_sm,
1140 struct state_list **true_stack,
1141 struct state_list **false_stack)
1142 {
1143 struct sm_state *tmp;
1144 int possibly_true = 0;
1145
1146 if (!gate_sm)
1147 return;
1148
1149 if (strcmp(gate_sm->state->name, pool_sm->state->name) == 0) {
1150 add_ptr_list(true_stack, pool_sm);
1151 return;
1152 }
1153
1154 FOR_EACH_PTR(gate_sm->possible, tmp) {
1155 if (strcmp(tmp->state->name, pool_sm->state->name) == 0) {
1156 possibly_true = 1;
1157 break;
1158 }
1159 } END_FOR_EACH_PTR(tmp);
1160
1161 if (!possibly_true) {
1162 add_ptr_list(false_stack, gate_sm);
1163 return;
1164 }
1165
1166 get_tf_stacks_from_pool(gate_sm->left, pool_sm, true_stack, false_stack);
1167 get_tf_stacks_from_pool(gate_sm->right, pool_sm, true_stack, false_stack);
1168 }
1169
1170 /*
1171 * The situation is we have a SMATCH_EXTRA state and we want to break it into
1172 * each of the ->possible states and find the implications of each. The caller
1173 * has to use __push_fake_cur_stree() to preserve the correct states so they
1174 * can be restored later.
1175 */
1176 void overwrite_states_using_pool(struct sm_state *gate_sm, struct sm_state *pool_sm)
1177 {
1178 struct state_list *true_stack = NULL;
1179 struct state_list *false_stack = NULL;
1180 struct stree *pre_stree;
1181 struct stree *implied_true;
1182 struct sm_state *tmp;
1183
1184 if (!pool_sm->pool)
1185 return;
1186
1187 get_tf_stacks_from_pool(gate_sm, pool_sm, &true_stack, &false_stack);
1188
1189 pre_stree = clone_stree(__get_cur_stree());
1190
1191 implied_true = filter_stack(gate_sm, pre_stree, false_stack, true_stack);
1192
1193 free_stree(&pre_stree);
1194 free_slist(&true_stack);
1195 free_slist(&false_stack);
1196
1197 FOR_EACH_SM(implied_true, tmp) {
1198 set_state(tmp->owner, tmp->name, tmp->sym, tmp->state);
1199 } END_FOR_EACH_SM(tmp);
1200
1201 free_stree(&implied_true);
1202 }
1203
1204 int assume(struct expression *expr)
1205 {
1206 int orig_final_pass = final_pass;
1207
1208 in_fake_env++;
1209 final_pass = 0;
1210 __push_fake_cur_stree();
1211 __split_whole_condition(expr);
1212 final_pass = orig_final_pass;
1213 in_fake_env--;
1214
1215 return 1;
1216 }
1217
1218 void end_assume(void)
1219 {
1220 __discard_false_states();
1221 __free_fake_cur_stree();
1222 }
1223
1224 int impossible_assumption(struct expression *left, int op, sval_t sval)
1225 {
1226 struct expression *value;
1227 struct expression *comparison;
1228 int ret;
1229
1230 value = value_expr(sval.value);
1231 comparison = compare_expression(left, op, value);
1232
1233 if (!assume(comparison))
1234 return 0;
1235 ret = is_impossible_path();
1236 end_assume();
1237
1238 return ret;
1239 }
1240
1241 void __extra_match_condition(struct expression *expr);
1242 void __comparison_match_condition(struct expression *expr);
1243 void __stored_condition(struct expression *expr);
1244 void register_implications(int id)
1245 {
1246 add_hook(&save_implications_hook, CONDITION_HOOK);
1247 add_hook(&set_implied_states, CONDITION_HOOK);
1248 add_hook(&__extra_match_condition, CONDITION_HOOK);
1249 add_hook(&__comparison_match_condition, CONDITION_HOOK);
1250 add_hook(&set_extra_implied_states, CONDITION_HOOK);
1251 add_hook(&__stored_condition, CONDITION_HOOK);
1252 add_hook(&match_end_func, END_FUNC_HOOK);
1253 }