1 /*
2  * Copyright (C) 2012 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  * This is an --info recipe.  The goal is to print a message for every parameter
20  * which we can not avoid dereferencing.  This is maybe a bit restrictive but it
21  * avoids some false positives.
22  */
23 
24 #include "smatch.h"
25 #include "smatch_extra.h"
26 #include "smatch_slist.h"
27 
28 static int my_id;
29 
30 STATE(derefed);
31 STATE(ignore);
32 STATE(param);
33 
34 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
35 {
36 	if (sm->state == &derefed)
37 		return;
38 	set_state(my_id, sm->name, sm->sym, &ignore);
39 }
40 
41 static void match_function_def(struct symbol *sym)
42 {
43 	struct symbol *arg;
44 	int i;
45 
46 	i = -1;
47 	FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
48 		i++;
49 		if (!arg->ident)
50 			continue;
51 		set_state(my_id, arg->ident->name, arg, &param);
52 	} END_FOR_EACH_PTR(arg);
53 }
54 
55 static void check_deref(struct expression *expr)
56 {
57 	struct expression *tmp;
58 	struct sm_state *sm;
59 
60 	tmp = get_assigned_expr(expr);
61 	if (tmp)
62 		expr = tmp;
63 	expr = strip_expr(expr);
64 
65 	if (get_param_num(expr) < 0)
66 		return;
67 
68 	if (param_was_set(expr))
69 		return;
70 
71 	sm = get_sm_state_expr(my_id, expr);
72 	if (sm && slist_has_state(sm->possible, &ignore))
73 		return;
74 	set_state_expr(my_id, expr, &derefed);
75 }
76 
77 static void match_dereference(struct expression *expr)
78 {
79 	if (expr->type != EXPR_PREOP)
80 		return;
81 	if (getting_address())
82 		return;
83 	check_deref(expr->unop);
84 }
85 
86 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
87 {
88 	/* XXX FIXME: param_implies has more information now */
89 	if (strcmp(key, "$") != 0)
90 		return;
91 	check_deref(arg);
92 }
93 
94 static void process_states(void)
95 {
96 	struct sm_state *tmp;
97 	int arg;
98 	const char *name;
99 
100 	FOR_EACH_MY_SM(my_id, __get_cur_stree(), tmp) {
101 		if (tmp->state != &derefed)
102 			continue;
103 		arg = get_param_num_from_sym(tmp->sym);
104 		if (arg < 0)
105 			continue;
106 		name = get_param_name(tmp);
107 		if (!name)
108 			continue;
109 		sql_insert_return_implies(DEREFERENCE, arg, name, "1");
110 	} END_FOR_EACH_SM(tmp);
111 }
112 
113 static void match_pointer_as_array(struct expression *expr)
114 {
115 	if (!is_array(expr))
116 		return;
117 	check_deref(get_array_base(expr));
118 }
119 
120 void check_dereferences_param(int id)
121 {
122 	my_id = id;
123 
124 	add_hook(&match_function_def, FUNC_DEF_HOOK);
125 
126 	add_hook(&match_dereference, DEREF_HOOK);
127 	add_hook(&match_pointer_as_array, OP_HOOK);
128 	select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
129 	add_modification_hook(my_id, &set_ignore);
130 
131 	all_return_states_hook(&process_states);
132 }
133