xref: /illumos-gate/usr/src/tools/smatch/src/smatch_imaginary_absolute.c (revision efe51d0cc2398b9ac179568b63a44e4bf295b8e2)
1 /*
2  * Copyright (C) 2016 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  * Say you have a condition like:
20  *
21  *     if (foo < 0)
22  *         return foo;
23  *
24  * But we actually know that foo is zero.  Then in smatch_extra.c we set "foo"
25  * to the empty state and then for the return statement we say that "foo" is
26  * s32min-s32max because we can't return the empty state.
27  *
28  * This file is supposed to provide an alternative to say that actually "foo" is
29  * less than zero.
30  *
31  */
32 
33 #include "smatch.h"
34 #include "smatch_slist.h"
35 #include "smatch_extra.h"
36 
37 static int my_id;
38 
empty_state(struct sm_state * sm)39 static struct smatch_state *empty_state(struct sm_state *sm)
40 {
41 	return alloc_estate_empty();
42 }
43 
merge_is_empty(struct smatch_state * s1,struct smatch_state * s2)44 struct smatch_state *merge_is_empty(struct smatch_state *s1, struct smatch_state *s2)
45 {
46 	return alloc_estate_empty();
47 }
48 
reset(struct sm_state * sm,struct expression * mod_expr)49 static void reset(struct sm_state *sm, struct expression *mod_expr)
50 {
51 	set_state(my_id, sm->name, sm->sym, alloc_estate_empty());
52 }
53 
__save_imaginary_state(struct expression * expr,struct range_list * true_rl,struct range_list * false_rl)54 void __save_imaginary_state(struct expression *expr, struct range_list *true_rl, struct range_list *false_rl)
55 {
56 	if (__in_pre_condition)
57 		return;
58 	set_true_false_states_expr(my_id, expr, alloc_estate_rl(true_rl), alloc_estate_rl(false_rl));
59 }
60 
get_imaginary_absolute(struct expression * expr,struct range_list ** rl)61 int get_imaginary_absolute(struct expression *expr, struct range_list **rl)
62 {
63 	struct smatch_state *state;
64 
65 	*rl = NULL;
66 
67 	state = get_state_expr(my_id, expr);
68 	if (!state || !estate_rl(state))
69 		return 0;
70 
71 	*rl = estate_rl(state);
72 	return 1;
73 }
74 
register_imaginary_absolute(int id)75 void register_imaginary_absolute(int id)
76 {
77 	my_id = id;
78 
79 	set_dynamic_states(my_id);
80 	add_unmatched_state_hook(my_id, &empty_state);
81 	add_merge_hook(my_id, &merge_is_empty);
82 	add_modification_hook(my_id, &reset);
83 }
84 
85