xref: /illumos-gate/usr/src/tools/smatch/src/smatch_impossible.c (revision 1f5207b7604fb44407eb4342aff613f7c4508508)
1 /*
2  * Copyright (C) 2014 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 #include "smatch.h"
19 #include "smatch_extra.h"
20 
21 static int my_id;
22 static int my_return_id;
23 
24 STATE(impossible);
25 
is_impossible_path(void)26 int is_impossible_path(void)
27 {
28 	if (get_state(my_id, "impossible", NULL) == &impossible)
29 		return 1;
30 	return 0;
31 }
32 
handle_compare(struct expression * left,int op,struct expression * right)33 static void handle_compare(struct expression *left, int op, struct expression *right)
34 {
35 	int true_impossible = 0;
36 	int false_impossible = 0;
37 
38 	left = strip_expr(left);
39 	while (left && left->type == EXPR_ASSIGNMENT)
40 		left = strip_expr(left->left);
41 
42 	if (!possibly_true(left, op, right))
43 		true_impossible = 1;
44 	if (!possibly_false(left, op, right))
45 		false_impossible = 1;
46 
47 	if (!true_impossible && !false_impossible)
48 		return;
49 
50 	set_true_false_states(my_id, "impossible", NULL,
51 			      true_impossible ? &impossible : NULL,
52 			      false_impossible ? &impossible : NULL);
53 
54 	if (inside_loop())
55 		return;
56 
57 	set_true_false_states(my_return_id, "impossible", NULL,
58 			      true_impossible ? &impossible : NULL,
59 			      false_impossible ? &impossible : NULL);
60 }
61 
match_condition(struct expression * expr)62 static void match_condition(struct expression *expr)
63 {
64 	if (expr->type == EXPR_COMPARE)
65 		handle_compare(expr->left, expr->op, expr->right);
66 	else
67 		handle_compare(expr, SPECIAL_NOTEQUAL, zero_expr());
68 }
69 
set_path_impossible(void)70 void set_path_impossible(void)
71 {
72 	set_state(my_id, "impossible", NULL, &impossible);
73 
74 	if (inside_loop())
75 		return;
76 
77 	set_state(my_return_id, "impossible", NULL, &impossible);
78 }
79 
match_case(struct expression * expr,struct range_list * rl)80 static void match_case(struct expression *expr, struct range_list *rl)
81 {
82 	if (rl)
83 		return;
84 	set_path_impossible();
85 }
86 
print_impossible_return(int return_id,char * return_ranges,struct expression * expr)87 static void print_impossible_return(int return_id, char *return_ranges, struct expression *expr)
88 {
89 	if (get_state(my_return_id, "impossible", NULL) == &impossible) {
90 		if (option_debug)
91 			sm_msg("impossible return.  return_id = %d return ranges = %s", return_id, return_ranges);
92 		sql_insert_return_states(return_id, return_ranges, CULL_PATH, -1, "", "");
93 	}
94 }
95 
register_impossible(int id)96 void register_impossible(int id)
97 {
98 	my_id = id;
99 
100 	add_hook(&match_condition, CONDITION_HOOK);
101 	add_hook(&match_case, CASE_HOOK);
102 }
103 
register_impossible_return(int id)104 void register_impossible_return(int id)
105 {
106 	my_return_id = id;
107 
108 	add_split_return_callback(&print_impossible_return);
109 }
110