smatch_param_filter.c

   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 smatch_state *unmatched_state(struct sm_state *sm)
  39 {
  40         struct smatch_state *state;
  41
  42         if (parent_is_gone_var_sym(sm->name, sm->sym))
  43                 return alloc_estate_empty();
  44
  45         state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
  46         if (state)
  47                 return state;
  48         return alloc_estate_whole(estate_type(sm->state));
  49 }
  50
  51 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
  52 {
  53         struct smatch_state *extra;
  54         struct range_list *rl;
  55
  56         if (estate_rl(other->state))
  57                 return;
  58
  59         extra = get_state(SMATCH_EXTRA, cur->name, cur->sym);
  60         if (!extra)
  61                 return;
  62
  63         rl = rl_intersection(estate_rl(extra), estate_rl(cur->state));
  64         if (rl_equiv(rl, estate_rl(cur->state)))
  65                 return;
  66         set_state(my_id, cur->name, cur->sym, alloc_estate_rl(clone_rl(rl)));
  67 }
  68
  69 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
  70 {
  71         struct symbol *param_sym;
  72         char *param_name;
  73
  74         param_name = get_param_var_sym_var_sym(name, sym, NULL, &param_sym);
  75         if (!param_name || !param_sym)
  76                 goto free;
  77         if (get_param_num_from_sym(param_sym) < 0)
  78                 goto free;
  79
  80         /* on stack parameters are handled in smatch_param_limit.c */
  81         if (param_sym->ident && strcmp(param_sym->ident->name, name) == 0)
  82                 return;
  83
  84         set_state(my_id, param_name, param_sym, alloc_estate_empty());
  85 free:
  86         free_string(param_name);
  87 }
  88
  89 /*
  90  * This relies on the fact that these states are stored so that
  91  * foo->bar is before foo->bar->baz.
  92  */
  93 static int parent_set(struct string_list *list, const char *name)
  94 {
  95         char *tmp;
  96         int len;
  97         int ret;
  98
  99         FOR_EACH_PTR(list, tmp) {
 100                 len = strlen(tmp);
 101                 ret = strncmp(tmp, name, len);
 102                 if (ret < 0)
 103                         continue;
 104                 if (ret > 0)
 105                         return 0;
 106                 if (name[len] == '-')
 107                         return 1;
 108         } END_FOR_EACH_PTR(tmp);
 109
 110         return 0;
 111 }
 112
 113 static void print_one_mod_param(int return_id, char *return_ranges,
 114                         int param, struct sm_state *sm, struct string_list **totally_filtered)
 115 {
 116         const char *param_name;
 117
 118         param_name = get_param_name(sm);
 119         if (!param_name)
 120                 return;
 121         if (is_whole_rl(estate_rl(sm->state)))
 122                 return;
 123         if (!estate_rl(sm->state)) {
 124                 insert_string(totally_filtered, (char *)sm->name);
 125                 return;
 126         }
 127
 128         if (is_ignored_kernel_data(param_name)) {
 129                 insert_string(totally_filtered, (char *)sm->name);
 130                 return;
 131         }
 132
 133         sql_insert_return_states(return_id, return_ranges, PARAM_FILTER, param,
 134                         param_name, show_rl(estate_rl(sm->state)));
 135 }
 136
 137 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 138 {
 139         struct sm_state *tmp;
 140         struct sm_state *sm;
 141         struct string_list *totally_filtered = NULL;
 142         int param;
 143
 144         FOR_EACH_MY_SM(SMATCH_EXTRA, __get_cur_stree(), tmp) {
 145                 param = get_param_num_from_sym(tmp->sym);
 146                 if (param < 0)
 147                         continue;
 148
 149                 /* on stack parameters are handled in smatch_param_limit.c */
 150                 if (tmp->sym->ident && strcmp(tmp->sym->ident->name, tmp->name) == 0)
 151                         continue;
 152
 153                 if (parent_set(totally_filtered, tmp->name))
 154                         continue;
 155
 156                 sm = get_sm_state(my_id, tmp->name, tmp->sym);
 157                 if (sm)
 158                         print_one_mod_param(return_id, return_ranges, param, sm, &totally_filtered);
 159         } END_FOR_EACH_SM(tmp);
 160
 161         free_ptr_list((struct ptr_list **)&totally_filtered);
 162 }
 163
 164 int param_has_filter_data(struct sm_state *sm)
 165 {
 166         struct smatch_state *state;
 167
 168         state = get_state(my_id, sm->name, sm->sym);
 169         if (!state) {
 170                 if (get_assigned_expr_name_sym(sm->name, sm->sym))
 171                         return 0;
 172                 return 1;
 173         }
 174         if (estate_rl(state))
 175                 return 1;
 176         return 0;
 177 }
 178
 179 void register_param_filter(int id)
 180 {
 181         my_id = id;
 182
 183         set_dynamic_states(my_id);
 184
 185         add_extra_mod_hook(&extra_mod_hook);
 186         add_unmatched_state_hook(my_id, &unmatched_state);
 187         add_pre_merge_hook(my_id, &pre_merge_hook);
 188         add_merge_hook(my_id, &merge_estates);
 189
 190         add_split_return_callback(&print_return_value_param);
 191 }
 192