smatch_param_limit.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 this:
  20  *
  21  * int foo(int a)
  22  * {
  23  *        if (a >= 0 && a < 10) {
  24  *                 a = 42;
  25  *                 return 1;
  26  *        }
  27  *        return 0;
  28  * }
  29  *
  30  * If we pass in 5, it returns 1.
  31  *
  32  * It's a bit complicated because we can't just consider the final value, we
  33  * have to always consider the passed in value.
  34  *
  35  */
  36
  37 #include "scope.h"
  38 #include "smatch.h"
  39 #include "smatch_extra.h"
  40 #include "smatch_slist.h"
  41
  42 static int my_id;
  43
  44 STATE(original);
  45
  46 static struct state_list *start_states;
  47 static struct state_list_stack *saved_stack;
  48
  49 static void save_start_states(struct statement *stmt)
  50 {
  51         start_states = get_all_states(SMATCH_EXTRA);
  52 }
  53
  54 static void match_end_func(void)
  55 {
  56         free_slist(&start_states);
  57 }
  58
  59 static struct smatch_state *unmatched_state(struct sm_state *sm)
  60 {
  61         return &original;
  62 }
  63
  64 static struct smatch_state *filter_my_sm(struct sm_state *sm)
  65 {
  66         struct range_list *ret = NULL;
  67         struct sm_state *tmp;
  68         struct smatch_state *estate;
  69
  70         FOR_EACH_PTR(sm->possible, tmp) {
  71                 if (tmp->state == &merged)
  72                         continue;
  73                 if (tmp->state == &original) {
  74                         estate = get_state_slist(tmp->pool, SMATCH_EXTRA, tmp->name, tmp->sym);
  75                         if (!estate) {
  76 //                              sm_msg("debug: no value found in pool %p", tmp->pool);
  77                                 continue;
  78                         }
  79                 } else {
  80                         estate = tmp->state;
  81                 }
  82                 ret = rl_union(ret, estate_rl(estate));
  83         } END_FOR_EACH_PTR(tmp);
  84
  85         return alloc_estate_rl(ret);
  86 }
  87
  88 struct smatch_state *get_orig_estate(const char *name, struct symbol *sym)
  89 {
  90         struct sm_state *sm;
  91         struct smatch_state *state;
  92
  93         sm = get_sm_state(my_id, name, sym);
  94         if (sm)
  95                 return filter_my_sm(sm);
  96
  97         state = get_state(SMATCH_EXTRA, name, sym);
  98         if (state)
  99                 return state;
 100         return alloc_estate_rl(alloc_whole_rl(get_real_base_type(sym)));
 101 }
 102
 103 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 104 {
 105         struct state_list *extra_slist;
 106         struct sm_state *tmp;
 107         struct sm_state *my_sm;
 108         struct smatch_state *state;
 109         int param;
 110
 111         extra_slist = get_all_states(SMATCH_EXTRA);
 112
 113         FOR_EACH_PTR(extra_slist, tmp) {
 114                 if (!tmp->sym || !tmp->sym->ident || strcmp(tmp->name, tmp->sym->ident->name) != 0)
 115                         continue;
 116
 117                 param = get_param_num_from_sym(tmp->sym);
 118                 if (param < 0)
 119                         continue;
 120
 121                 my_sm = get_sm_state(my_id, tmp->name, tmp->sym);
 122                 if (!my_sm) {
 123                         struct smatch_state *old;
 124
 125                         if (estate_is_whole(tmp->state))
 126                                 continue;
 127                         old = get_state_slist(start_states, SMATCH_EXTRA, tmp->name, tmp->sym);
 128                         if (old && estates_equiv(old, tmp->state))
 129                                 continue;
 130                         sql_insert_return_states(return_id, return_ranges,
 131                                         LIMITED_VALUE, param, "$$",
 132                                         tmp->state->name);
 133                         continue;
 134                 }
 135
 136                 state = filter_my_sm(my_sm);
 137                 if (!state)
 138                         continue;
 139                 /* This represents an impossible state.  I screwd up.  Bail. */
 140                 if (!estate_rl(state))
 141                         continue;
 142                 if (estate_is_whole(state))
 143                         continue;
 144                 sql_insert_return_states(return_id, return_ranges,
 145                                         LIMITED_VALUE, param, "$$",
 146                                         state->name);
 147         } END_FOR_EACH_PTR(tmp);
 148
 149         free_slist(&extra_slist);
 150 }
 151
 152 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
 153 {
 154         struct smatch_state *orig_vals;
 155         int param;
 156
 157         param = get_param_num_from_sym(sym);
 158         if (param < 0)
 159                 return;
 160
 161         /* we are only saving params for now */
 162         if (!sym->ident || strcmp(name, sym->ident->name) != 0)
 163                 return;
 164
 165         orig_vals = get_orig_estate(name, sym);
 166         set_state(my_id, name, sym, orig_vals);
 167 }
 168
 169 static void match_save_states(struct expression *expr)
 170 {
 171         push_slist(&saved_stack, start_states);
 172         start_states = NULL;
 173 }
 174
 175 static void match_restore_states(struct expression *expr)
 176 {
 177         start_states = pop_slist(&saved_stack);
 178 }
 179
 180 void register_param_limit(int id)
 181 {
 182         my_id = id;
 183
 184         add_hook(&save_start_states, AFTER_DEF_HOOK);
 185         add_extra_mod_hook(&extra_mod_hook);
 186         add_unmatched_state_hook(my_id, &unmatched_state);
 187         add_split_return_callback(&print_return_value_param);
 188         add_hook(&match_end_func, END_FUNC_HOOK);
 189         add_hook(&match_save_states, INLINE_FN_START);
 190         add_hook(&match_restore_states, INLINE_FN_END);
 191
 192 }
 193