1/*
2 * Copyright (C) 2009 Dan Carpenter.
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
21static int my_id;
22
23STATE(derefed);
24
25static void underef(struct sm_state *sm, struct expression *mod_expr)
26{
27	set_state(my_id, sm->name, sm->sym, &undefined);
28}
29
30static void match_dereference(struct expression *expr)
31{
32	if (__in_fake_assign)
33		return;
34
35	if (expr->type != EXPR_PREOP)
36		return;
37	expr = strip_expr(expr->unop);
38	if (!is_pointer(expr))
39		return;
40	if (implied_not_equal(expr, 0))
41		return;
42
43	if (is_impossible_path())
44		return;
45
46	set_state_expr(my_id, expr, &derefed);
47}
48
49static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
50{
51	struct symbol *sym;
52	char *name;
53
54	name = get_variable_from_key(arg, key, &sym);
55	if (!name || !sym)
56		goto free;
57
58	if (implied_not_equal_name_sym(name, sym, 0))
59		goto free;
60	set_state(my_id, name, sym, &derefed);
61
62free:
63	free_string(name);
64}
65
66static void match_condition(struct expression *expr)
67{
68	struct sm_state *sm;
69	char *name;
70
71	if (__in_pre_condition)
72		return;
73
74	name = get_macro_name(expr->pos);
75	if (name &&
76	    (strcmp(name, "likely") != 0 && strcmp(name, "unlikely") != 0))
77		return;
78
79	if (!is_pointer(expr))
80		return;
81
82	sm = get_sm_state_expr(my_id, expr);
83	if (!sm || sm->state != &derefed)
84		return;
85
86	sm_warning("variable dereferenced before check '%s' (see line %d)", sm->name, sm->line);
87	set_state_expr(my_id, expr, &undefined);
88}
89
90void check_deref_check(int id)
91{
92	my_id = id;
93	add_hook(&match_dereference, DEREF_HOOK);
94	add_hook(&match_condition, CONDITION_HOOK);
95	select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
96	add_modification_hook(my_id, &underef);
97}
98