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 STATE(modified);
  39 STATE(original);
  40
  41 static struct stree *start_states;
  42 static struct stree_stack *saved_stack;
  43 static void save_start_states(struct statement *stmt)
  44 {
  45         start_states = get_all_states_stree(SMATCH_EXTRA);
  46 }
  47
  48 static void match_end_func(void)
  49 {
  50         free_stree(&start_states);
  51 }
  52
  53 static void match_save_states(struct expression *expr)
  54 {
  55         push_stree(&saved_stack, start_states);
  56         start_states = NULL;
  57 }
  58
  59 static void match_restore_states(struct expression *expr)
  60 {
  61         free_stree(&start_states);
  62         start_states = pop_stree(&saved_stack);
  63 }
  64
  65 static struct smatch_state *unmatched_state(struct sm_state *sm)
  66 {
  67         return &original;
  68 }
  69
  70 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
  71 {
  72         int param;
  73
  74         param = get_param_num_from_sym(sym);
  75         if (param < 0)
  76                 return;
  77
  78         set_state(my_id, name, sym, &modified);
  79 }
  80
  81 /*
  82  * This relies on the fact that these states are stored so that
  83  * foo->bar is before foo->bar->baz.
  84  */
  85 static int parent_set(struct string_list *list, const char *name)
  86 {
  87         char *tmp;
  88         int len;
  89         int ret;
  90
  91         FOR_EACH_PTR(list, tmp) {
  92                 len = strlen(tmp);
  93                 ret = strncmp(tmp, name, len);
  94                 if (ret < 0)
  95                         continue;
  96                 if (ret > 0)
  97                         return 0;
  98                 if (name[len] == '-')
  99                         return 1;
 100         } END_FOR_EACH_PTR(tmp);
 101
 102         return 0;
 103 }
 104
 105 static struct range_list *get_orig_rl(struct sm_state *sm)
 106 {
 107         struct range_list *ret = NULL;
 108         struct sm_state *tmp;
 109         struct smatch_state *extra;
 110
 111         FOR_EACH_PTR(sm->possible, tmp) {
 112                 if (tmp->state != &original)
 113                         continue;
 114                 extra = get_state_stree(tmp->pool, SMATCH_EXTRA, tmp->name, tmp->sym);
 115                 if (!extra) {
 116 //                      sm_msg("debug: no value found in pool %p", tmp->pool);
 117                         return NULL;
 118                 }
 119                 ret = rl_union(ret, estate_rl(extra));
 120         } END_FOR_EACH_PTR(tmp);
 121         return ret;
 122 }
 123
 124 static void print_one_mod_param(int return_id, char *return_ranges,
 125                         int param, struct sm_state *sm, struct string_list **totally_filtered)
 126 {
 127         const char *param_name;
 128         struct range_list *rl;
 129
 130         param_name = get_param_name(sm);
 131         if (!param_name)
 132                 return;
 133         rl = get_orig_rl(sm);
 134         if (is_whole_rl(rl))
 135                 return;
 136
 137         if (!rl)
 138                 insert_string(totally_filtered, (char *)sm->name);
 139
 140         sql_insert_return_states(return_id, return_ranges, FILTER_VALUE, param,
 141                         param_name, show_rl(rl));
 142 }
 143
 144 static void print_one_extra_param(int return_id, char *return_ranges,
 145                         int param, struct sm_state *sm, struct string_list **totally_filtered)
 146 {
 147         struct smatch_state *old;
 148         const char *param_name;
 149
 150         if (estate_is_whole(sm->state))
 151                 return;
 152         old = get_state_stree(start_states, SMATCH_EXTRA, sm->name, sm->sym);
 153         if (old && estates_equiv(old, sm->state))
 154                 return;
 155
 156         param_name = get_param_name(sm);
 157         if (!param_name)
 158                 return;
 159
 160         if (strcmp(sm->state->name, "") == 0)
 161                 insert_string(totally_filtered, (char *)sm->name);
 162
 163         sql_insert_return_states(return_id, return_ranges, FILTER_VALUE, param,
 164                         param_name, sm->state->name);
 165 }
 166
 167 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 168 {
 169         struct stree *stree;
 170         struct sm_state *tmp;
 171         struct sm_state *sm;
 172         struct string_list *totally_filtered = NULL;
 173         int param;
 174
 175         stree = __get_cur_stree();
 176
 177         FOR_EACH_MY_SM(SMATCH_EXTRA, stree, tmp) {
 178                 param = get_param_num_from_sym(tmp->sym);
 179                 if (param < 0)
 180                         continue;
 181                 /*
 182                  * skip the parameter itself because that's stored on the stack
 183                  * and thus handled by smatch_param_limit.c.
 184                  */
 185                 if (tmp->sym->ident && strcmp(tmp->sym->ident->name, tmp->name) == 0)
 186                         continue;
 187
 188                 if (parent_set(totally_filtered, tmp->name))
 189                         continue;
 190
 191                 sm = get_sm_state(my_id, tmp->name, tmp->sym);
 192                 if (sm)
 193                         print_one_mod_param(return_id, return_ranges, param, sm, &totally_filtered);
 194                 else
 195                         print_one_extra_param(return_id, return_ranges, param, tmp, &totally_filtered);
 196         } END_FOR_EACH_SM(tmp);
 197
 198         free_ptr_list((struct ptr_list **)&totally_filtered);
 199 }
 200
 201 void register_param_filter(int id)
 202 {
 203         my_id = id;
 204
 205         add_hook(&save_start_states, AFTER_DEF_HOOK);
 206         add_extra_mod_hook(&extra_mod_hook);
 207         add_unmatched_state_hook(my_id, &unmatched_state);
 208         add_split_return_callback(&print_return_value_param);
 209         add_hook(&match_end_func, END_FUNC_HOOK);
 210         add_hook(&match_save_states, INLINE_FN_START);
 211         add_hook(&match_restore_states, INLINE_FN_END);
 212 }
 213