xref: /illumos-gate/usr/src/tools/smatch/src/smatch_parsed_conditions.c (revision 5a0e240f87295cfc13c53236f30ccace0d5412c7)
1 /*
2  * Copyright (C) 2019 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 problem here is something like this:
20  *
21  * return (blah() || whatever()) ? NULL : some_function();
22  *
23  * When we are parsing this what happens is that we first parse all the
24  * expressions "(blah() || whatever()) ? NULL : some_function();" and then
25  * we parse the return statement.
26  *
27  * When we parse the return statement, we say "Oh, this is a conditional.  Let's
28  * get all the implications for true and false."  But because
29  * "(blah() || whatever())" is a function pointer, that means there aren't any
30  * implications.
31  *
32  * So what this module does is it ties the implications to the expression
33  * pointer so that we can retreive them easily.  It's similar to Smatch stored
34  * implications but it doesn't save condition, it saves the pointer.
35  *
36  * We ignore pre loop conditions which Smatch parses twice.
37  *
38  */
39 
40 #include "smatch.h"
41 #include "smatch_slist.h"
42 
43 static int my_id;
44 
45 STATE(true_path);
46 STATE(false_path);
47 
record_condition(struct expression * expr)48 void record_condition(struct expression *expr)
49 {
50 	char name[32];
51 	sval_t val;
52 
53 	if (get_value(expr, &val))
54 		return;
55 
56 	if (__in_pre_condition)
57 		return;
58 
59 	snprintf(name, sizeof(name), "condition %p", expr);
60 	set_true_false_states(my_id, name, NULL, &true_path, &false_path);
61 }
62 
register_parsed_conditions(int id)63 void register_parsed_conditions(int id)
64 {
65 	my_id = id;
66 	add_hook(&record_condition, CONDITION_HOOK);
67 }
68 
filter_by_sm(struct sm_state * sm,struct state_list ** true_stack,struct state_list ** false_stack)69 static void filter_by_sm(struct sm_state *sm,
70 		       struct state_list **true_stack,
71 		       struct state_list **false_stack)
72 {
73 	if (!sm)
74 		return;
75 
76 	if (sm->state == &true_path)
77 		add_ptr_list(true_stack, sm);
78 	else if (sm->state == &false_path)
79 		add_ptr_list(false_stack, sm);
80 
81 	if (sm->merged) {
82 		filter_by_sm(sm->left, true_stack, false_stack);
83 		filter_by_sm(sm->right, true_stack, false_stack);
84 	}
85 }
86 
parsed_condition_implication_hook(struct expression * expr,struct state_list ** true_stack,struct state_list ** false_stack)87 struct sm_state *parsed_condition_implication_hook(struct expression *expr,
88 				struct state_list **true_stack,
89 				struct state_list **false_stack)
90 {
91 	struct state_list *tmp_true = NULL;
92 	struct state_list *tmp_false = NULL;
93 	struct sm_state *sm, *tmp;
94 	char name[32];
95 
96 	snprintf(name, sizeof(name), "condition %p", expr);
97 
98 	sm = get_sm_state(my_id, name, NULL);
99 	if (!sm)
100 		return NULL;
101 	if (!sm->merged)
102 		return NULL;
103 
104 	filter_by_sm(sm, &tmp_true, &tmp_false);
105 	if (!tmp_true && !tmp_false)
106 		return NULL;
107 
108 	FOR_EACH_PTR(tmp_true, tmp) {
109 		add_ptr_list(true_stack, tmp);
110 	} END_FOR_EACH_PTR(tmp);
111 
112 	FOR_EACH_PTR(tmp_false, tmp) {
113 		add_ptr_list(false_stack, tmp);
114 	} END_FOR_EACH_PTR(tmp);
115 
116 	free_slist(&tmp_true);
117 	free_slist(&tmp_false);
118 
119 	return sm;
120 }
121 
122