core: silence some false positives from parsing invalid code
[smatch.git] / smatch_param_limit.c
blob021da4598505d2c2e7ea5f8a2fd8b4444e52ff83
1 /*
2 * Copyright (C) 2012 Oracle.
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.
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.
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
19 * This is almost the same as smatch_param_filter.c. The difference is that
20 * this only deals with values passed on the stack and param filter only deals
21 * with values changed so that the caller sees the new value. It other words
22 * the key for these should always be "$" and the key for param_filter should
23 * never be "$". Also smatch_param_set() should never use "$" as the key.
24 * Param set should work together with param_filter to determine the value that
25 * the caller sees at the end.
27 * This is for functions like this:
29 * int foo(int a)
30 * {
31 * if (a >= 0 && a < 10) {
32 * a = 42;
33 * return 1;
34 * }
35 * return 0;
36 * }
38 * If we pass in 5, it returns 1.
40 * It's a bit complicated because we can't just consider the final value, we
41 * have to always consider the passed in value.
45 #include "scope.h"
46 #include "smatch.h"
47 #include "smatch_extra.h"
48 #include "smatch_slist.h"
50 static int my_id;
52 static struct stree *start_states;
53 static struct stree_stack *saved_stack;
55 static void save_start_states(struct statement *stmt)
57 start_states = get_all_states_stree(SMATCH_EXTRA);
60 static void free_start_states(void)
62 free_stree(&start_states);
65 static struct smatch_state *unmatched_state(struct sm_state *sm)
67 struct smatch_state *state;
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));
75 struct smatch_state *get_orig_estate(const char *name, struct symbol *sym)
77 struct smatch_state *state;
79 state = get_state(my_id, name, sym);
80 if (state)
81 return state;
83 state = get_state(SMATCH_EXTRA, name, sym);
84 if (state)
85 return state;
86 return alloc_estate_rl(alloc_whole_rl(get_real_base_type(sym)));
89 struct smatch_state *get_orig_estate_type(const char *name, struct symbol *sym, struct symbol *type)
91 struct smatch_state *state;
93 state = get_state(my_id, name, sym);
94 if (state)
95 return state;
97 state = get_state(SMATCH_EXTRA, name, sym);
98 if (state)
99 return state;
100 return alloc_estate_rl(alloc_whole_rl(type));
103 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
105 struct smatch_state *state, *old;
106 struct sm_state *tmp;
107 const char *param_name;
108 int param;
110 FOR_EACH_MY_SM(SMATCH_EXTRA, __get_cur_stree(), tmp) {
111 param = get_param_num_from_sym(tmp->sym);
112 if (param < 0)
113 continue;
115 param_name = get_param_name(tmp);
116 if (!param_name)
117 continue;
119 state = __get_state(my_id, tmp->name, tmp->sym);
120 if (!state)
121 state = tmp->state;
123 if (estate_is_whole(state) || estate_is_empty(state))
124 continue;
125 old = get_state_stree(start_states, SMATCH_EXTRA, tmp->name, tmp->sym);
126 if (old && rl_equiv(estate_rl(old), estate_rl(state)))
127 continue;
129 sql_insert_return_states(return_id, return_ranges, PARAM_LIMIT,
130 param, param_name, state->name);
131 } END_FOR_EACH_SM(tmp);
134 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
136 struct smatch_state *orig_vals;
137 int param;
139 param = get_param_num_from_sym(sym);
140 if (param < 0)
141 return;
143 orig_vals = get_orig_estate_type(name, sym, estate_type(state));
144 set_state(my_id, name, sym, orig_vals);
147 static void match_save_states(struct expression *expr)
149 push_stree(&saved_stack, start_states);
150 start_states = NULL;
153 static void match_restore_states(struct expression *expr)
155 free_stree(&start_states);
156 start_states = pop_stree(&saved_stack);
159 void register_param_limit(int id)
161 my_id = id;
163 add_hook(&save_start_states, AFTER_DEF_HOOK);
164 add_hook(&free_start_states, AFTER_FUNC_HOOK);
166 add_extra_mod_hook(&extra_mod_hook);
167 add_unmatched_state_hook(my_id, &unmatched_state);
168 add_merge_hook(my_id, &merge_estates);
170 add_hook(&match_save_states, INLINE_FN_START);
171 add_hook(&match_restore_states, INLINE_FN_END);
173 add_split_return_callback(&print_return_value_param);