1*1f5207b7SJohn Levon /*
2*1f5207b7SJohn Levon  * Copyright (C) 2011 Dan Carpenter.
3*1f5207b7SJohn Levon  *
4*1f5207b7SJohn Levon  * This program is free software; you can redistribute it and/or
5*1f5207b7SJohn Levon  * modify it under the terms of the GNU General Public License
6*1f5207b7SJohn Levon  * as published by the Free Software Foundation; either version 2
7*1f5207b7SJohn Levon  * of the License, or (at your option) any later version.
8*1f5207b7SJohn Levon  *
9*1f5207b7SJohn Levon  * This program is distributed in the hope that it will be useful,
10*1f5207b7SJohn Levon  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11*1f5207b7SJohn Levon  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12*1f5207b7SJohn Levon  * GNU General Public License for more details.
13*1f5207b7SJohn Levon  *
14*1f5207b7SJohn Levon  * You should have received a copy of the GNU General Public License
15*1f5207b7SJohn Levon  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16*1f5207b7SJohn Levon  */
17*1f5207b7SJohn Levon 
18*1f5207b7SJohn Levon #include "smatch.h"
19*1f5207b7SJohn Levon #include "smatch_slist.h"
20*1f5207b7SJohn Levon 
21*1f5207b7SJohn Levon static int my_id;
22*1f5207b7SJohn Levon 
right_side_changes(struct expression * expr)23*1f5207b7SJohn Levon static int right_side_changes(struct expression *expr)
24*1f5207b7SJohn Levon {
25*1f5207b7SJohn Levon 	sval_t dummy;
26*1f5207b7SJohn Levon 
27*1f5207b7SJohn Levon 	if (get_value(expr->right, &dummy))
28*1f5207b7SJohn Levon 		return 0;
29*1f5207b7SJohn Levon 	return 1;
30*1f5207b7SJohn Levon }
31*1f5207b7SJohn Levon 
get_iterator_set(struct statement * stmt)32*1f5207b7SJohn Levon static struct expression *get_iterator_set(struct statement *stmt)
33*1f5207b7SJohn Levon {
34*1f5207b7SJohn Levon 	struct expression *expr;
35*1f5207b7SJohn Levon 
36*1f5207b7SJohn Levon 	if (!stmt)
37*1f5207b7SJohn Levon 		return NULL;
38*1f5207b7SJohn Levon 	if (stmt->type != STMT_EXPRESSION)
39*1f5207b7SJohn Levon 		return NULL;
40*1f5207b7SJohn Levon 	expr = stmt->expression;
41*1f5207b7SJohn Levon 	if (expr->type != EXPR_ASSIGNMENT)
42*1f5207b7SJohn Levon 		return NULL;
43*1f5207b7SJohn Levon 	if (expr->op != '=')
44*1f5207b7SJohn Levon 		return NULL;
45*1f5207b7SJohn Levon 	if (right_side_changes(expr))
46*1f5207b7SJohn Levon 		return NULL;
47*1f5207b7SJohn Levon 	return expr->left;
48*1f5207b7SJohn Levon }
49*1f5207b7SJohn Levon 
get_iterator_tested(struct expression * expr)50*1f5207b7SJohn Levon static struct expression *get_iterator_tested(struct expression *expr)
51*1f5207b7SJohn Levon {
52*1f5207b7SJohn Levon 	if (!expr)
53*1f5207b7SJohn Levon 		return NULL;
54*1f5207b7SJohn Levon 	if (expr->type != EXPR_COMPARE)
55*1f5207b7SJohn Levon 		return NULL;
56*1f5207b7SJohn Levon 	return expr->left;
57*1f5207b7SJohn Levon }
58*1f5207b7SJohn Levon 
match_loop(struct statement * stmt)59*1f5207b7SJohn Levon static void match_loop(struct statement *stmt)
60*1f5207b7SJohn Levon {
61*1f5207b7SJohn Levon 	struct expression *iterator;
62*1f5207b7SJohn Levon 	char *iter_set;
63*1f5207b7SJohn Levon 	char *iter_tested;
64*1f5207b7SJohn Levon 
65*1f5207b7SJohn Levon 	if (get_macro_name(stmt->pos))
66*1f5207b7SJohn Levon 		return;
67*1f5207b7SJohn Levon 
68*1f5207b7SJohn Levon 	iterator = get_iterator_set(stmt->iterator_pre_statement);
69*1f5207b7SJohn Levon 	iter_set = expr_to_var(iterator);
70*1f5207b7SJohn Levon 	iterator = get_iterator_tested(stmt->iterator_pre_condition);
71*1f5207b7SJohn Levon 	iter_tested = expr_to_var(iterator);
72*1f5207b7SJohn Levon 	if (!iter_set || !iter_tested)
73*1f5207b7SJohn Levon 		goto free;
74*1f5207b7SJohn Levon 	if (strcmp(iter_set, iter_tested))
75*1f5207b7SJohn Levon 		goto free;
76*1f5207b7SJohn Levon 
77*1f5207b7SJohn Levon 	/* smatch doesn't handle loops correctly so this silences some
78*1f5207b7SJohn Levon 	 * false positives.
79*1f5207b7SJohn Levon 	 */
80*1f5207b7SJohn Levon 	if (right_side_changes(stmt->iterator_pre_condition))
81*1f5207b7SJohn Levon 		goto free;
82*1f5207b7SJohn Levon 
83*1f5207b7SJohn Levon 	if (implied_condition_false(stmt->iterator_pre_condition))
84*1f5207b7SJohn Levon 		sm_warning("we never enter this loop");
85*1f5207b7SJohn Levon 
86*1f5207b7SJohn Levon free:
87*1f5207b7SJohn Levon 	free_string(iter_set);
88*1f5207b7SJohn Levon 	free_string(iter_tested);
89*1f5207b7SJohn Levon }
90*1f5207b7SJohn Levon 
check_bogus_loop(int id)91*1f5207b7SJohn Levon void check_bogus_loop(int id)
92*1f5207b7SJohn Levon {
93*1f5207b7SJohn Levon 	my_id = id;
94*1f5207b7SJohn Levon 	add_hook(&match_loop, PRELOOP_HOOK);
95*1f5207b7SJohn Levon }
96