2 * sparse/smatch_states.c
4 * Copyright (C) 2006 Dan Carpenter.
6 * Licensed under the Open Software License version 1.1
11 * You have a lists of states. kernel = locked, foo = NULL, ...
12 * When you hit an if {} else {} statement then you swap the list
13 * of states for a different list of states. The lists are stored
16 * At the beginning of this file there are list of the stacks that
17 * we use. Each function in this file does something to one of
20 * So the smatch_flow.c understands code but it doesn't understand states.
21 * smatch_flow calls functions in this file. This file calls functions
22 * in smatch_slist.c which just has boring generic plumbing for handling
23 * state lists. But really it's this file where all the magic happens.
30 #include "smatch_slist.h"
31 #include "smatch_extra.h"
33 struct smatch_state undefined
= { .name
= "undefined" };
34 struct smatch_state merged
= { .name
= "merged" };
35 struct smatch_state true_state
= { .name
= "true" };
36 struct smatch_state false_state
= { .name
= "false" };
38 static struct state_list
*cur_slist
; /* current states */
40 static struct state_list_stack
*true_stack
; /* states after a t/f branch */
41 static struct state_list_stack
*false_stack
;
42 static struct state_list_stack
*pre_cond_stack
; /* states before a t/f branch */
44 static struct state_list_stack
*cond_true_stack
; /* states affected by a branch */
45 static struct state_list_stack
*cond_false_stack
;
48 struct state_list
*__fake_cur_slist
= NULL
;
49 int __fake_conditions
= 0;
50 struct state_list
*__fake_cond_true
= NULL
;
51 struct state_list
*__fake_cond_false
= NULL
;
53 static struct state_list_stack
*break_stack
;
54 static struct state_list_stack
*switch_stack
;
55 static struct range_list_stack
*remaining_cases
;
56 static struct state_list_stack
*default_stack
;
57 static struct state_list_stack
*continue_stack
;
58 static struct state_list_stack
*false_only_stack
;
60 static struct named_stack
*goto_stack
;
62 struct state_list_stack
*implied_pools
;
66 void __print_cur_slist()
68 __print_slist(cur_slist
);
71 static int unreachable()
73 static int reset_warnings
= 1;
80 if (reset_warnings
|| debug_states
)
81 sm_msg("info: ignoring unreachable code.");
86 void set_state(int owner
, const char *name
, struct symbol
*sym
,
87 struct smatch_state
*state
)
93 struct smatch_state
*s
;
95 s
= get_state(owner
, name
, sym
);
97 printf("%d new state. name='%s' [%s] %s\n",
98 get_lineno(), name
, check_name(owner
), show_state(state
));
100 printf("%d state change name='%s' [%s] %s => %s\n",
101 get_lineno(), name
, check_name(owner
), show_state(s
),
105 if (owner
!= -1 && unreachable())
109 set_state_slist(&__fake_cur_slist
, owner
, name
, sym
, state
);
113 set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
115 if (cond_true_stack
) {
116 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
117 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
121 void set_state_expr(int owner
, struct expression
*expr
,
122 struct smatch_state
*state
)
127 expr
= strip_expr(expr
);
128 name
= get_variable_from_expr(expr
, &sym
);
131 reset_on_container_modified(owner
, expr
);
132 set_state(owner
, name
, sym
, state
);
138 void __set_state(struct sm_state
*sm
)
141 struct smatch_state
*s
;
143 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
145 printf("%d new state. name='%s' [%s] %s\n",
146 get_lineno(), sm
->name
, check_name(sm
->owner
),
147 show_state(sm
->state
));
149 printf("%d state change name='%s' [%s] %s => %s\n",
150 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
151 show_state(sm
->state
));
157 overwrite_sm_state(&cur_slist
, sm
);
159 if (cond_true_stack
) {
160 overwrite_sm_state_stack(&cond_true_stack
, sm
);
161 overwrite_sm_state_stack(&cond_false_stack
, sm
);
165 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
167 return get_state_slist(cur_slist
, owner
, name
, sym
);
170 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
174 struct smatch_state
*ret
= NULL
;
176 expr
= strip_expr(expr
);
177 name
= get_variable_from_expr(expr
, &sym
);
180 ret
= get_state(owner
, name
, sym
);
186 struct state_list
*get_possible_states(int owner
, const char *name
,
189 struct sm_state
*sms
;
191 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
193 return sms
->possible
;
197 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
201 struct state_list
*ret
= NULL
;
203 expr
= strip_expr(expr
);
204 name
= get_variable_from_expr(expr
, &sym
);
207 ret
= get_possible_states(owner
, name
, sym
);
213 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
215 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
218 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
222 struct sm_state
*ret
= NULL
;
224 expr
= strip_expr(expr
);
225 name
= get_variable_from_expr(expr
, &sym
);
228 ret
= get_sm_state(owner
, name
, sym
);
234 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
236 delete_state_slist(&cur_slist
, owner
, name
, sym
);
239 void delete_state_expr(int owner
, struct expression
*expr
)
244 expr
= strip_expr(expr
);
245 name
= get_variable_from_expr(expr
, &sym
);
248 delete_state(owner
, name
, sym
);
253 struct state_list
*get_all_states(int owner
)
255 struct state_list
*slist
= NULL
;
256 struct sm_state
*tmp
;
258 FOR_EACH_PTR(cur_slist
, tmp
) {
259 if (tmp
->owner
== owner
) {
260 add_ptr_list(&slist
, tmp
);
262 } END_FOR_EACH_PTR(tmp
);
274 struct state_list
*__get_cur_slist()
279 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
280 struct smatch_state
*true_state
,
281 struct smatch_state
*false_state
)
284 struct smatch_state
*tmp
;
286 tmp
= get_state(owner
, name
, sym
);
287 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
288 get_lineno(), name
, show_state(tmp
),
289 show_state(true_state
), show_state(false_state
));
295 if (__fake_conditions
) {
297 set_state_slist(&__fake_cond_true
, owner
, name
, sym
, true_state
);
299 set_state_slist(&__fake_cond_false
, owner
, name
, sym
, false_state
);
303 if (!cond_false_stack
|| !cond_true_stack
) {
304 printf("Error: missing true/false stacks\n");
309 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
310 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
313 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
316 void set_true_false_states_expr(int owner
, struct expression
*expr
,
317 struct smatch_state
*true_state
,
318 struct smatch_state
*false_state
)
323 expr
= strip_expr(expr
);
324 name
= get_variable_from_expr(expr
, &sym
);
327 reset_on_container_modified(owner
, expr
);
328 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
333 void __set_true_false_sm(struct sm_state
*true_state
,
334 struct sm_state
*false_state
)
339 if (!cond_false_stack
|| !cond_true_stack
) {
340 printf("Error: missing true/false stacks\n");
345 overwrite_sm_state(&cur_slist
, true_state
);
346 overwrite_sm_state_stack(&cond_true_stack
, true_state
);
349 overwrite_sm_state_stack(&cond_false_stack
, false_state
);
354 free_slist(&cur_slist
);
357 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
363 * At the start of every function we mark the path
364 * as unnull. That there is always at least one state
365 * in the cur_slist until nullify_path is called. This
366 * is used in merge_slist() for the first null check.
369 void __unnullify_path()
371 set_state(-1, "unnull_path", NULL
, &true_state
);
381 void clear_all_states()
383 struct named_slist
*named_slist
;
386 free_stack_and_slists(&true_stack
);
387 free_stack_and_slists(&false_stack
);
388 free_stack_and_slists(&false_only_stack
);
389 free_stack_and_slists(&pre_cond_stack
);
390 free_stack_and_slists(&cond_true_stack
);
391 free_stack_and_slists(&cond_false_stack
);
392 free_stack_and_slists(&break_stack
);
393 free_stack_and_slists(&switch_stack
);
394 free_stack_and_slists(&continue_stack
);
395 free_stack_and_slists(&implied_pools
);
397 FOR_EACH_PTR(goto_stack
, named_slist
) {
398 free_slist(&named_slist
->slist
);
399 } END_FOR_EACH_PTR(named_slist
);
400 __free_ptr_list((struct ptr_list
**)&goto_stack
);
401 free_every_single_sm_state();
405 void __push_cond_stacks()
407 push_slist(&cond_true_stack
, NULL
);
408 push_slist(&cond_false_stack
, NULL
);
412 * This combines the pre cond states with either the true or false states.
414 * a = kmalloc() ; if (a !! foo(a)
415 * In the pre state a is possibly null. In the true state it is non null.
416 * In the false state it is null. Combine the pre and the false to get
417 * that when we call 'foo', 'a' is null.
420 static void __use_cond_stack(struct state_list_stack
**stack
)
422 struct state_list
*slist
;
424 free_slist(&cur_slist
);
426 cur_slist
= pop_slist(&pre_cond_stack
);
427 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
429 slist
= pop_slist(stack
);
430 overwrite_slist(slist
, &cur_slist
);
431 push_slist(stack
, slist
);
434 void __save_false_states_for_later()
436 struct state_list
*pre_conditions
;
437 struct state_list
*false_states
;
438 struct state_list
*tmp
;
440 pre_conditions
= pop_slist(&pre_cond_stack
);
441 false_states
= pop_slist(&cond_false_stack
);
442 tmp
= clone_slist(pre_conditions
);
444 overwrite_slist(false_states
, &tmp
);
446 push_slist(&pre_cond_stack
, tmp
);
447 push_slist(&pre_cond_stack
, pre_conditions
);
448 push_slist(&cond_false_stack
, false_states
);
451 void __use_previously_stored_false_states()
453 free_slist(&cur_slist
);
454 cur_slist
= pop_slist(&pre_cond_stack
);
457 void __use_cond_true_states()
459 __use_cond_stack(&cond_true_stack
);
462 void __use_cond_false_states()
464 __use_cond_stack(&cond_false_stack
);
467 void __negate_cond_stacks()
469 struct state_list
*old_false
, *old_true
;
471 __use_cond_stack(&cond_false_stack
);
472 old_false
= pop_slist(&cond_false_stack
);
473 old_true
= pop_slist(&cond_true_stack
);
474 push_slist(&cond_false_stack
, old_true
);
475 push_slist(&cond_true_stack
, old_false
);
478 void __and_cond_states()
480 and_slist_stack(&cond_true_stack
);
481 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
484 void __or_cond_states()
486 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
487 and_slist_stack(&cond_false_stack
);
490 void __save_pre_cond_states()
492 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
495 void __pop_pre_cond_states()
497 struct state_list
*tmp
;
499 tmp
= pop_slist(&pre_cond_stack
);
503 void __use_false_only_stack()
505 struct state_list
*slist
;
507 slist
= pop_slist(&false_only_stack
);
508 overwrite_slist(slist
, &cur_slist
);
512 void __pop_false_only_stack()
514 struct state_list
*slist
;
516 slist
= pop_slist(&false_only_stack
);
520 void __use_cond_states()
522 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
524 pre
= pop_slist(&pre_cond_stack
);
525 pre_clone
= clone_slist(pre
);
527 true_states
= pop_slist(&cond_true_stack
);
528 overwrite_slist(true_states
, &pre
);
529 /* we use the true states right away */
530 free_slist(&cur_slist
);
534 false_states
= pop_slist(&cond_false_stack
);
535 push_slist(&false_only_stack
, clone_slist(false_states
));
536 overwrite_slist(false_states
, &pre_clone
);
537 push_slist(&false_stack
, pre_clone
);
540 void __push_true_states()
542 push_slist(&true_stack
, clone_slist(cur_slist
));
545 void __use_false_states()
547 free_slist(&cur_slist
);
548 cur_slist
= pop_slist(&false_stack
);
551 void __pop_false_states()
553 struct state_list
*slist
;
555 slist
= pop_slist(&false_stack
);
559 void __merge_false_states()
561 struct state_list
*slist
;
563 slist
= pop_slist(&false_stack
);
564 merge_slist(&cur_slist
, slist
);
568 void __merge_true_states()
570 struct state_list
*slist
;
572 slist
= pop_slist(&true_stack
);
573 merge_slist(&cur_slist
, slist
);
577 void __push_continues()
579 push_slist(&continue_stack
, NULL
);
582 void __pop_continues()
584 struct state_list
*slist
;
586 slist
= pop_slist(&continue_stack
);
590 void __process_continues()
592 struct state_list
*slist
;
594 slist
= pop_slist(&continue_stack
);
596 slist
= clone_slist(cur_slist
);
598 merge_slist(&slist
, cur_slist
);
600 push_slist(&continue_stack
, slist
);
603 static int top_slist_empty(struct state_list_stack
**stack
)
605 struct state_list
*tmp
;
608 tmp
= pop_slist(stack
);
611 push_slist(stack
, tmp
);
615 /* a silly loop does this: while(i--) { return; } */
616 void __warn_on_silly_pre_loops()
618 if (!__path_is_null())
620 if (!top_slist_empty(&continue_stack
))
622 if (!top_slist_empty(&break_stack
))
624 /* if the path was nullified before the loop, then we already
625 printed an error earlier */
626 if (top_slist_empty(&false_stack
))
628 sm_msg("info: loop could be replaced with if statement.");
631 void __merge_continues()
633 struct state_list
*slist
;
635 slist
= pop_slist(&continue_stack
);
636 merge_slist(&cur_slist
, slist
);
642 push_slist(&break_stack
, NULL
);
645 void __process_breaks()
647 struct state_list
*slist
;
649 slist
= pop_slist(&break_stack
);
651 slist
= clone_slist(cur_slist
);
653 merge_slist(&slist
, cur_slist
);
655 push_slist(&break_stack
, slist
);
658 void __merge_breaks()
660 struct state_list
*slist
;
662 slist
= pop_slist(&break_stack
);
663 merge_slist(&cur_slist
, slist
);
669 free_slist(&cur_slist
);
670 cur_slist
= pop_slist(&break_stack
);
673 void __save_switch_states(struct expression
*switch_expr
)
675 push_range_list(&remaining_cases
, __get_implied_values(switch_expr
));
676 push_slist(&switch_stack
, clone_slist(cur_slist
));
679 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
681 struct state_list
*slist
;
682 struct state_list
*implied_slist
;
684 slist
= pop_slist(&switch_stack
);
685 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
686 merge_slist(&cur_slist
, implied_slist
);
687 free_slist(&implied_slist
);
688 push_slist(&switch_stack
, slist
);
691 void __pop_switches()
693 struct state_list
*slist
;
695 pop_range_list(&remaining_cases
);
696 slist
= pop_slist(&switch_stack
);
700 void __push_default()
702 push_slist(&default_stack
, NULL
);
707 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
712 struct state_list
*slist
;
714 slist
= pop_slist(&default_stack
);
722 static struct named_slist
*alloc_named_slist(const char *name
,
723 struct state_list
*slist
)
725 struct named_slist
*named_slist
= __alloc_named_slist(0);
727 named_slist
->name
= (char *)name
;
728 named_slist
->slist
= slist
;
732 void __save_gotos(const char *name
)
734 struct state_list
**slist
;
735 struct state_list
*clone
;
737 slist
= get_slist_from_named_stack(goto_stack
, name
);
739 clone
= clone_slist(cur_slist
);
740 merge_slist(slist
, clone
);
744 struct named_slist
*named_slist
;
746 clone
= clone_slist(cur_slist
);
747 named_slist
= alloc_named_slist(name
, clone
);
748 add_ptr_list(&goto_stack
, named_slist
);
752 void __merge_gotos(const char *name
)
754 struct state_list
**slist
;
756 slist
= get_slist_from_named_stack(goto_stack
, name
);
758 merge_slist(&cur_slist
, *slist
);