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 for functions like:
20 *
21 * void foo(int *x)
22 * {
23 * if (*x == 42)
24 * *x = 0;
25 * }
26 *
27 * The final value of *x depends on the input to the function but with *x == 42
28 * filtered out.
29 *
30 */
31
32 #include "smatch.h"
33 #include "smatch_extra.h"
34 #include "smatch_slist.h"
35
36 static int my_id;
37
38 static struct stree *start_states;
39 static struct stree_stack *saved_stack;
40 static void save_start_states(struct statement *stmt)
41 {
42 start_states = get_all_states_stree(SMATCH_EXTRA);
43 }
44
45 static void free_start_states(void)
46 {
47 free_stree(&start_states);
48 }
49
50 static void match_save_states(struct expression *expr)
51 {
52 push_stree(&saved_stack, start_states);
53 start_states = NULL;
54 }
55
56 static void match_restore_states(struct expression *expr)
57 {
58 free_stree(&start_states);
59 start_states = pop_stree(&saved_stack);
60 }
61
62 static struct smatch_state *unmatched_state(struct sm_state *sm)
63 {
64 struct smatch_state *state;
65
66 if (parent_is_gone_var_sym(sm->name, sm->sym))
67 return alloc_estate_empty();
68
69 state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
70 if (state)
71 return state;
72 return alloc_estate_whole(estate_type(sm->state));
73 }
74
75 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
76 {
77 struct smatch_state *extra;
78 struct range_list *rl;
79
80 if (estate_rl(other->state))
81 return;
82
83 extra = get_state(SMATCH_EXTRA, cur->name, cur->sym);
84 if (!extra)
85 return;
86
87 rl = rl_intersection(estate_rl(extra), estate_rl(cur->state));
88 if (rl_equiv(rl, estate_rl(cur->state)))
89 return;
90 set_state(my_id, cur->name, cur->sym, alloc_estate_rl(clone_rl(rl)));
91 }
92
93 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
94 {
95 int param;
96
97 if (__in_fake_assign)
98 return;
99
100 param = get_param_num_from_sym(sym);
101 if (param < 0)
102 return;
103
104 /* on stack parameters are handled in smatch_param_limit.c */
105 if (sym->ident && strcmp(sym->ident->name, name) == 0)
106 return;
107
108 set_state(my_id, name, sym, alloc_estate_empty());
109 }
110
111 /*
112 * This relies on the fact that these states are stored so that
113 * foo->bar is before foo->bar->baz.
114 */
115 static int parent_set(struct string_list *list, const char *name)
116 {
117 char *tmp;
118 int len;
119 int ret;
120
121 FOR_EACH_PTR(list, tmp) {
122 len = strlen(tmp);
123 ret = strncmp(tmp, name, len);
124 if (ret < 0)
125 continue;
126 if (ret > 0)
127 return 0;
128 if (name[len] == '-')
129 return 1;
130 } END_FOR_EACH_PTR(tmp);
131
132 return 0;
133 }
134
135 static void print_one_mod_param(int return_id, char *return_ranges,
136 int param, struct sm_state *sm, struct string_list **totally_filtered)
137 {
138 const char *param_name;
139
140 param_name = get_param_name(sm);
141 if (!param_name)
142 return;
143 if (is_whole_rl(estate_rl(sm->state)))
144 return;
145 if (!estate_rl(sm->state)) {
146 insert_string(totally_filtered, (char *)sm->name);
147 return;
148 }
149
150 if (is_ignored_kernel_data(param_name)) {
151 insert_string(totally_filtered, (char *)sm->name);
152 return;
153 }
154
155 sql_insert_return_states(return_id, return_ranges, PARAM_FILTER, param,
156 param_name, show_rl(estate_rl(sm->state)));
157 }
158
159 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
160 {
161 struct sm_state *tmp;
162 struct sm_state *sm;
163 struct string_list *totally_filtered = NULL;
164 int param;
165
166 FOR_EACH_MY_SM(SMATCH_EXTRA, __get_cur_stree(), tmp) {
167 param = get_param_num_from_sym(tmp->sym);
168 if (param < 0)
169 continue;
170
171 /* on stack parameters are handled in smatch_param_limit.c */
172 if (tmp->sym->ident && strcmp(tmp->sym->ident->name, tmp->name) == 0)
173 continue;
174
175 if (parent_set(totally_filtered, tmp->name))
176 continue;
177
178 sm = get_sm_state(my_id, tmp->name, tmp->sym);
179 if (sm)
180 print_one_mod_param(return_id, return_ranges, param, sm, &totally_filtered);
181 } END_FOR_EACH_SM(tmp);
182
183 free_ptr_list((struct ptr_list **)&totally_filtered);
184 }
185
186 int param_has_filter_data(struct sm_state *sm)
187 {
188 struct smatch_state *state;
189
190 state = get_state(my_id, sm->name, sm->sym);
191 if (!state) {
192 if (get_assigned_expr_name_sym(sm->name, sm->sym))
193 return 0;
194 return 1;
195 }
196 if (estate_rl(state))
197 return 1;
198 return 0;
199 }
200
201 void register_param_filter(int id)
202 {
203 my_id = id;
204
205 set_dynamic_states(my_id);
206 add_hook(&save_start_states, AFTER_DEF_HOOK);
207 add_hook(&free_start_states, AFTER_FUNC_HOOK);
208
209 add_extra_mod_hook(&extra_mod_hook);
210 add_unmatched_state_hook(my_id, &unmatched_state);
211 add_pre_merge_hook(my_id, &pre_merge_hook);
212 add_merge_hook(my_id, &merge_estates);
213
214 add_hook(&match_save_states, INLINE_FN_START);
215 add_hook(&match_restore_states, INLINE_FN_END);
216
217 add_split_return_callback(&print_return_value_param);
218 }
219