1 /*
2 * Copyright (C) 2015 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 * Say we have a line like:
20 * foo = bar / 8;
21 * Assume we don't know anything about bar. Well, now we know that foo is less
22 * than UINT_MAX / 8. Which might be useful, but it probably is misleading
23 * useless knowledge. Up to now we have ignored those but now we have said to
24 * store them.
25 *
26 * It also works if you have something like "foo = (int)(char)unknown_var;".
27 *
28 * I feel like this data doesn't have to be perfect, it just has to be better
29 * than nothing and that will help eliminate some false positives.
30 *
31 */
32
33 #include "smatch.h"
34 #include "smatch_slist.h"
35 #include "smatch_extra.h"
36
37 static int my_id;
38
set_real_absolute(struct expression * expr,struct smatch_state * state)39 void set_real_absolute(struct expression *expr, struct smatch_state *state)
40 {
41 set_state_expr(my_id, expr, clone_estate(state));
42 }
43
extra_mod_hook(const char * name,struct symbol * sym,struct expression * expr,struct smatch_state * state)44 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
45 {
46 struct smatch_state *abs;
47 struct range_list *rl;
48
49 abs = get_state(my_id, name, sym);
50 if (!abs || !estate_rl(abs))
51 return;
52 rl = rl_intersection(estate_rl(abs), estate_rl(state));
53 set_state(my_id, name, sym, alloc_estate_rl(clone_rl(rl)));
54 }
55
pre_merge_hook(struct sm_state * cur,struct sm_state * other)56 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
57 {
58 struct smatch_state *extra;
59 struct range_list *rl;
60
61 extra = get_state(SMATCH_EXTRA, cur->name, cur->sym);
62 if (!extra || !estate_rl(extra))
63 return;
64 if (!estate_rl(cur->state)) {
65 set_state(my_id, cur->name, cur->sym, clone_estate(extra));
66 return;
67 }
68 rl = rl_intersection(estate_rl(cur->state), estate_rl(extra));
69 set_state(my_id, cur->name, cur->sym, alloc_estate_rl(clone_rl(rl)));
70 }
71
empty_state(struct sm_state * sm)72 static struct smatch_state *empty_state(struct sm_state *sm)
73 {
74 return alloc_estate_empty();
75 }
76
in_iterator_pre_statement(void)77 static int in_iterator_pre_statement(void)
78 {
79 struct statement *stmt;
80
81 /*
82 * we can't use __cur_stmt because that isn't set for
83 * iterator_pre_statement. Kind of a mess.
84 *
85 */
86
87 stmt = last_ptr_list((struct ptr_list *)big_statement_stack);
88
89 if (!stmt || !stmt->parent)
90 return 0;
91 if (stmt->parent->type != STMT_ITERATOR)
92 return 0;
93 if (stmt->parent->iterator_pre_statement != stmt)
94 return 0;
95 return 1;
96 }
97
match_assign(struct expression * expr)98 static void match_assign(struct expression *expr)
99 {
100 struct range_list *rl;
101 struct symbol *type;
102 sval_t sval;
103
104 if (expr->op != '=')
105 return;
106 if (is_fake_call(expr->right))
107 return;
108 if (in_iterator_pre_statement())
109 return;
110
111 get_real_absolute_rl(expr->right, &rl);
112
113 type = get_type(expr->left);
114 if (!type)
115 return;
116 if (type->type != SYM_PTR && type->type != SYM_BASETYPE &&
117 type->type != SYM_ENUM)
118 return;
119
120 rl = cast_rl(type, rl);
121 if (is_whole_rl(rl) && !get_state_expr(my_id, expr->left))
122 return;
123 /* These are handled by smatch_extra.c */
124 if (rl_to_sval(rl, &sval) && !get_state_expr(my_id, expr->left))
125 return;
126
127 set_state_expr(my_id, expr->left, alloc_estate_rl(clone_rl(rl)));
128 }
129
get_real_absolute_state(struct expression * expr)130 struct smatch_state *get_real_absolute_state(struct expression *expr)
131 {
132 return get_state_expr(my_id, expr);
133 }
134
get_real_absolute_state_var_sym(const char * name,struct symbol * sym)135 struct smatch_state *get_real_absolute_state_var_sym(const char *name, struct symbol *sym)
136 {
137 return __get_state(my_id, name, sym);
138 }
139
register_real_absolute(int id)140 void register_real_absolute(int id)
141 {
142 my_id = id;
143
144 set_dynamic_states(my_id);
145 add_pre_merge_hook(my_id, &pre_merge_hook);
146 add_unmatched_state_hook(my_id, &empty_state);
147 add_merge_hook(my_id, &merge_estates);
148 add_extra_mod_hook(&extra_mod_hook);
149
150 add_hook(&match_assign, ASSIGNMENT_HOOK);
151 }
152
153