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.
29 #include "smatch_slist.h"
30 #include "smatch_extra.h"
32 struct smatch_state undefined
= { .name
= "undefined" };
33 struct smatch_state merged
= { .name
= "merged" };
34 struct smatch_state true_state
= { .name
= "true" };
35 struct smatch_state false_state
= { .name
= "false" };
37 static struct state_list
*cur_slist
; /* current states */
39 static struct state_list_stack
*true_stack
; /* states after a t/f branch */
40 static struct state_list_stack
*false_stack
;
41 static struct state_list_stack
*pre_cond_stack
; /* states before a t/f branch */
43 static struct state_list_stack
*cond_true_stack
; /* states affected by a branch */
44 static struct state_list_stack
*cond_false_stack
;
47 struct state_list
*__fake_cur_slist
= NULL
;
48 int __fake_conditions
= 0;
49 struct state_list
*__fake_cond_true
= NULL
;
50 struct state_list
*__fake_cond_false
= NULL
;
52 static struct state_list_stack
*break_stack
;
53 static struct state_list_stack
*switch_stack
;
54 static struct range_list_stack
*remaining_cases
;
55 static struct state_list_stack
*default_stack
;
56 static struct state_list_stack
*continue_stack
;
58 static struct named_stack
*goto_stack
;
60 struct state_list_stack
*implied_pools
;
64 void __print_cur_slist(void)
66 __print_slist(cur_slist
);
69 static int in_declarations_bit(void)
71 struct statement
*tmp
;
73 FOR_EACH_PTR_REVERSE(big_statement_stack
, tmp
) {
74 if (tmp
->type
== STMT_DECLARATION
)
77 } END_FOR_EACH_PTR_REVERSE(tmp
);
83 static int reset_warnings
= 1;
90 if (in_declarations_bit())
93 /* option spammy turns on a noisier version of this */
94 if (reset_warnings
&& !option_spammy
)
95 sm_msg("info: ignoring unreachable code.");
100 void set_state(int owner
, const char *name
, struct symbol
*sym
, struct smatch_state
*state
)
106 struct smatch_state
*s
;
108 s
= get_state(owner
, name
, sym
);
110 printf("%d new state. name='%s' [%s] %s\n",
111 get_lineno(), name
, check_name(owner
), show_state(state
));
113 printf("%d state change name='%s' [%s] %s => %s\n",
114 get_lineno(), name
, check_name(owner
), show_state(s
),
118 if (owner
!= -1 && unreachable())
121 __use_default_modification_hook(owner
, name
);
124 set_state_slist(&__fake_cur_slist
, owner
, name
, sym
, state
);
128 set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
130 if (cond_true_stack
) {
131 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
132 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
136 void set_state_expr(int owner
, struct expression
*expr
, struct smatch_state
*state
)
141 expr
= strip_expr(expr
);
142 name
= get_variable_from_expr(expr
, &sym
);
145 set_state(owner
, name
, sym
, state
);
151 void __set_state(struct sm_state
*sm
)
154 struct smatch_state
*s
;
156 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
158 printf("%d new state. name='%s' [%s] %s\n",
159 get_lineno(), sm
->name
, check_name(sm
->owner
),
160 show_state(sm
->state
));
162 printf("%d state change name='%s' [%s] %s => %s\n",
163 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
164 show_state(sm
->state
));
170 overwrite_sm_state(&cur_slist
, sm
);
172 if (cond_true_stack
) {
173 overwrite_sm_state_stack(&cond_true_stack
, sm
);
174 overwrite_sm_state_stack(&cond_false_stack
, sm
);
178 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
180 return get_state_slist(cur_slist
, owner
, name
, sym
);
183 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
187 struct smatch_state
*ret
= NULL
;
189 expr
= strip_expr(expr
);
190 name
= get_variable_from_expr(expr
, &sym
);
193 ret
= get_state(owner
, name
, sym
);
199 struct state_list
*get_possible_states(int owner
, const char *name
, struct symbol
*sym
)
201 struct sm_state
*sms
;
203 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
205 return sms
->possible
;
209 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
213 struct state_list
*ret
= NULL
;
215 expr
= strip_expr(expr
);
216 name
= get_variable_from_expr(expr
, &sym
);
219 ret
= get_possible_states(owner
, name
, sym
);
225 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
227 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
230 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
234 struct sm_state
*ret
= NULL
;
236 expr
= strip_expr(expr
);
237 name
= get_variable_from_expr(expr
, &sym
);
240 ret
= get_sm_state(owner
, name
, sym
);
246 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
248 delete_state_slist(&cur_slist
, owner
, name
, sym
);
249 if (cond_true_stack
) {
250 delete_state_stack(&pre_cond_stack
, owner
, name
, sym
);
251 delete_state_stack(&cond_true_stack
, owner
, name
, sym
);
252 delete_state_stack(&cond_false_stack
, owner
, name
, sym
);
256 void delete_state_expr(int owner
, struct expression
*expr
)
261 expr
= strip_expr(expr
);
262 name
= get_variable_from_expr(expr
, &sym
);
265 delete_state(owner
, name
, sym
);
270 struct state_list
*get_all_states(int owner
)
272 struct state_list
*slist
= NULL
;
273 struct sm_state
*tmp
;
275 FOR_EACH_PTR(cur_slist
, tmp
) {
276 if (tmp
->owner
== owner
) {
277 add_ptr_list(&slist
, tmp
);
279 } END_FOR_EACH_PTR(tmp
);
284 int is_reachable(void)
291 struct state_list
*__get_cur_slist(void)
296 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
297 struct smatch_state
*true_state
,
298 struct smatch_state
*false_state
)
301 struct smatch_state
*tmp
;
303 tmp
= get_state(owner
, name
, sym
);
304 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
305 get_lineno(), name
, show_state(tmp
),
306 show_state(true_state
), show_state(false_state
));
312 if (__fake_conditions
) {
314 set_state_slist(&__fake_cond_true
, owner
, name
, sym
, true_state
);
316 set_state_slist(&__fake_cond_false
, owner
, name
, sym
, false_state
);
320 if (!cond_false_stack
|| !cond_true_stack
) {
321 printf("Error: missing true/false stacks\n");
326 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
327 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
330 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
333 void set_true_false_states_expr(int owner
, struct expression
*expr
,
334 struct smatch_state
*true_state
,
335 struct smatch_state
*false_state
)
340 expr
= strip_expr(expr
);
341 name
= get_variable_from_expr(expr
, &sym
);
344 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
349 void __set_true_false_sm(struct sm_state
*true_state
, struct sm_state
*false_state
)
354 if (!cond_false_stack
|| !cond_true_stack
) {
355 printf("Error: missing true/false stacks\n");
360 overwrite_sm_state(&cur_slist
, true_state
);
361 overwrite_sm_state_stack(&cond_true_stack
, true_state
);
364 overwrite_sm_state_stack(&cond_false_stack
, false_state
);
367 void nullify_path(void)
369 free_slist(&cur_slist
);
372 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
379 * At the start of every function we mark the path
380 * as unnull. That there is always at least one state
381 * in the cur_slist until nullify_path is called. This
382 * is used in merge_slist() for the first null check.
384 void __unnullify_path(void)
386 set_state(-1, "unnull_path", NULL
, &true_state
);
389 int __path_is_null(void)
396 void clear_all_states(void)
398 struct named_slist
*named_slist
;
401 free_stack_and_slists(&true_stack
);
402 free_stack_and_slists(&false_stack
);
403 free_stack_and_slists(&pre_cond_stack
);
404 free_stack_and_slists(&cond_true_stack
);
405 free_stack_and_slists(&cond_false_stack
);
406 free_stack_and_slists(&break_stack
);
407 free_stack_and_slists(&switch_stack
);
408 free_stack_and_slists(&continue_stack
);
409 free_stack_and_slists(&implied_pools
);
411 FOR_EACH_PTR(goto_stack
, named_slist
) {
412 free_slist(&named_slist
->slist
);
413 } END_FOR_EACH_PTR(named_slist
);
414 __free_ptr_list((struct ptr_list
**)&goto_stack
);
415 free_every_single_sm_state();
418 void __push_cond_stacks(void)
420 push_slist(&cond_true_stack
, NULL
);
421 push_slist(&cond_false_stack
, NULL
);
425 * This combines the pre cond states with either the true or false states.
427 * a = kmalloc() ; if (a !! foo(a)
428 * In the pre state a is possibly null. In the true state it is non null.
429 * In the false state it is null. Combine the pre and the false to get
430 * that when we call 'foo', 'a' is null.
432 static void __use_cond_stack(struct state_list_stack
**stack
)
434 struct state_list
*slist
;
436 free_slist(&cur_slist
);
438 cur_slist
= pop_slist(&pre_cond_stack
);
439 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
441 slist
= pop_slist(stack
);
442 overwrite_slist(slist
, &cur_slist
);
443 push_slist(stack
, slist
);
446 void __save_false_states_for_later(void)
448 struct state_list
*pre_conditions
;
449 struct state_list
*false_states
;
450 struct state_list
*tmp
;
452 pre_conditions
= pop_slist(&pre_cond_stack
);
453 false_states
= pop_slist(&cond_false_stack
);
454 tmp
= clone_slist(pre_conditions
);
456 overwrite_slist(false_states
, &tmp
);
458 push_slist(&pre_cond_stack
, tmp
);
459 push_slist(&pre_cond_stack
, pre_conditions
);
460 push_slist(&cond_false_stack
, false_states
);
463 void __use_previously_stored_false_states(void)
465 free_slist(&cur_slist
);
466 cur_slist
= pop_slist(&pre_cond_stack
);
469 void __use_cond_true_states(void)
471 __use_cond_stack(&cond_true_stack
);
474 void __use_cond_false_states(void)
476 __use_cond_stack(&cond_false_stack
);
479 void __negate_cond_stacks(void)
481 struct state_list
*old_false
, *old_true
;
483 __use_cond_stack(&cond_false_stack
);
484 old_false
= pop_slist(&cond_false_stack
);
485 old_true
= pop_slist(&cond_true_stack
);
486 push_slist(&cond_false_stack
, old_true
);
487 push_slist(&cond_true_stack
, old_false
);
490 void __and_cond_states(void)
492 and_slist_stack(&cond_true_stack
);
493 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
496 void __or_cond_states(void)
498 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
499 and_slist_stack(&cond_false_stack
);
502 void __save_pre_cond_states(void)
504 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
507 void __pop_pre_cond_states(void)
509 struct state_list
*tmp
;
511 tmp
= pop_slist(&pre_cond_stack
);
515 void __use_cond_states(void)
517 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
519 pre
= pop_slist(&pre_cond_stack
);
520 pre_clone
= clone_slist(pre
);
522 true_states
= pop_slist(&cond_true_stack
);
523 overwrite_slist(true_states
, &pre
);
524 /* we use the true states right away */
525 free_slist(&cur_slist
);
528 false_states
= pop_slist(&cond_false_stack
);
529 overwrite_slist(false_states
, &pre_clone
);
530 push_slist(&false_stack
, pre_clone
);
533 void __push_true_states(void)
535 push_slist(&true_stack
, clone_slist(cur_slist
));
538 void __use_false_states(void)
540 free_slist(&cur_slist
);
541 cur_slist
= pop_slist(&false_stack
);
544 void __pop_false_states(void)
546 struct state_list
*slist
;
548 slist
= pop_slist(&false_stack
);
552 void __merge_false_states(void)
554 struct state_list
*slist
;
556 slist
= pop_slist(&false_stack
);
557 merge_slist(&cur_slist
, slist
);
561 void __merge_true_states(void)
563 struct state_list
*slist
;
565 slist
= pop_slist(&true_stack
);
566 merge_slist(&cur_slist
, slist
);
570 void __push_continues(void)
572 push_slist(&continue_stack
, NULL
);
575 void __pop_continues(void)
577 struct state_list
*slist
;
579 slist
= pop_slist(&continue_stack
);
583 void __process_continues(void)
585 struct state_list
*slist
;
587 slist
= pop_slist(&continue_stack
);
589 slist
= clone_slist(cur_slist
);
591 merge_slist(&slist
, cur_slist
);
593 push_slist(&continue_stack
, slist
);
596 static int top_slist_empty(struct state_list_stack
**stack
)
598 struct state_list
*tmp
;
601 tmp
= pop_slist(stack
);
604 push_slist(stack
, tmp
);
608 /* a silly loop does this: while(i--) { return; } */
609 void __warn_on_silly_pre_loops(void)
611 if (!__path_is_null())
613 if (!top_slist_empty(&continue_stack
))
615 if (!top_slist_empty(&break_stack
))
617 /* if the path was nullified before the loop, then we already
618 printed an error earlier */
619 if (top_slist_empty(&false_stack
))
621 sm_msg("info: loop could be replaced with if statement.");
624 void __merge_continues(void)
626 struct state_list
*slist
;
628 slist
= pop_slist(&continue_stack
);
629 merge_slist(&cur_slist
, slist
);
633 void __push_breaks(void)
635 push_slist(&break_stack
, NULL
);
638 void __process_breaks(void)
640 struct state_list
*slist
;
642 slist
= pop_slist(&break_stack
);
644 slist
= clone_slist(cur_slist
);
646 merge_slist(&slist
, cur_slist
);
648 push_slist(&break_stack
, slist
);
651 void __merge_breaks(void)
653 struct state_list
*slist
;
655 slist
= pop_slist(&break_stack
);
656 merge_slist(&cur_slist
, slist
);
660 void __use_breaks(void)
662 free_slist(&cur_slist
);
663 cur_slist
= pop_slist(&break_stack
);
666 void __save_switch_states(struct expression
*switch_expr
)
668 push_range_list(&remaining_cases
, __get_implied_values(switch_expr
));
669 push_slist(&switch_stack
, clone_slist(cur_slist
));
672 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
674 struct state_list
*slist
;
675 struct state_list
*implied_slist
;
677 slist
= pop_slist(&switch_stack
);
678 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
679 merge_slist(&cur_slist
, implied_slist
);
680 free_slist(&implied_slist
);
681 push_slist(&switch_stack
, slist
);
684 void __pop_switches(void)
686 struct state_list
*slist
;
688 pop_range_list(&remaining_cases
);
689 slist
= pop_slist(&switch_stack
);
693 void __push_default(void)
695 push_slist(&default_stack
, NULL
);
698 void __set_default(void)
700 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
703 int __pop_default(void)
705 struct state_list
*slist
;
707 slist
= pop_slist(&default_stack
);
715 static struct named_slist
*alloc_named_slist(const char *name
, struct state_list
*slist
)
717 struct named_slist
*named_slist
= __alloc_named_slist(0);
719 named_slist
->name
= (char *)name
;
720 named_slist
->slist
= slist
;
724 void __save_gotos(const char *name
)
726 struct state_list
**slist
;
727 struct state_list
*clone
;
729 slist
= get_slist_from_named_stack(goto_stack
, name
);
731 clone
= clone_slist(cur_slist
);
732 merge_slist(slist
, clone
);
736 struct named_slist
*named_slist
;
738 clone
= clone_slist(cur_slist
);
739 named_slist
= alloc_named_slist(name
, clone
);
740 add_ptr_list(&goto_stack
, named_slist
);
744 void __merge_gotos(const char *name
)
746 struct state_list
**slist
;
748 slist
= get_slist_from_named_stack(goto_stack
, name
);
750 merge_slist(&cur_slist
, *slist
);