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 stree *start_states;
  47 static struct stree_stack *saved_stack;
  48
  49 static void save_start_states(struct statement *stmt)
  50 {
  51         start_states = get_all_states_stree(SMATCH_EXTRA);
  52 }
  53
  54 static void match_end_func(void)
  55 {
  56         free_stree(&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_stree(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 stree *stree;
 106         struct sm_state *tmp;
 107         struct sm_state *my_sm;
 108         struct smatch_state *state;
 109         int param;
 110         char *compare;
 111         const char *compare_str;
 112         char buf[256];
 113
 114         stree = __get_cur_stree();
 115
 116         FOR_EACH_MY_SM(SMATCH_EXTRA, stree, tmp) {
 117                 if (!tmp->sym || !tmp->sym->ident || strcmp(tmp->name, tmp->sym->ident->name) != 0)
 118                         continue;
 119
 120                 param = get_param_num_from_sym(tmp->sym);
 121                 if (param < 0)
 122                         continue;
 123
 124                 compare = expr_equal_to_param(symbol_expression(tmp->sym), param);
 125                 if (!compare)
 126                         compare = expr_lte_to_param(symbol_expression(tmp->sym), param);
 127                 compare_str = compare;
 128                 if (!compare_str)
 129                         compare_str = "";
 130
 131                 my_sm = get_sm_state(my_id, tmp->name, tmp->sym);
 132                 if (!my_sm) {
 133                         struct smatch_state *old;
 134
 135                         if (estate_is_whole(tmp->state) && !compare)
 136                                 continue;
 137                         old = get_state_stree(start_states, SMATCH_EXTRA, tmp->name, tmp->sym);
 138                         if (old && estates_equiv(old, tmp->state) && !compare)
 139                                 continue;
 140
 141                         snprintf(buf, sizeof(buf), "%s%s", tmp->state->name, compare_str);
 142                         sql_insert_return_states(return_id, return_ranges,
 143                                         LIMITED_VALUE, param, "$$", buf);
 144                         continue;
 145                 }
 146
 147                 state = filter_my_sm(my_sm);
 148                 if (!state)
 149                         continue;
 150                 /* This represents an impossible state.  I screwd up.  Bail. */
 151                 if (!estate_rl(state))
 152                         continue;
 153                 if (estate_is_whole(state) && !compare) {
 154                         continue;
 155                 }
 156
 157                 snprintf(buf, sizeof(buf), "%s%s", state->name, compare_str);
 158                 sql_insert_return_states(return_id, return_ranges,
 159                                         LIMITED_VALUE, param, "$$", buf);
 160         } END_FOR_EACH_SM(tmp);
 161 }
 162
 163 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
 164 {
 165         struct smatch_state *orig_vals;
 166         int param;
 167
 168         param = get_param_num_from_sym(sym);
 169         if (param < 0)
 170                 return;
 171
 172         /* we are only saving params for now */
 173         if (!sym->ident || strcmp(name, sym->ident->name) != 0)
 174                 return;
 175
 176         orig_vals = get_orig_estate(name, sym);
 177         set_state(my_id, name, sym, orig_vals);
 178 }
 179
 180 static void match_save_states(struct expression *expr)
 181 {
 182         push_stree(&saved_stack, start_states);
 183         start_states = NULL;
 184 }
 185
 186 static void match_restore_states(struct expression *expr)
 187 {
 188         free_stree(&start_states);
 189         start_states = pop_stree(&saved_stack);
 190 }
 191
 192 void register_param_limit(int id)
 193 {
 194         my_id = id;
 195
 196         add_hook(&save_start_states, AFTER_DEF_HOOK);
 197         add_extra_mod_hook(&extra_mod_hook);
 198         add_unmatched_state_hook(my_id, &unmatched_state);
 199         add_split_return_callback(&print_return_value_param);
 200         add_hook(&match_end_func, END_FUNC_HOOK);
 201         add_hook(&match_save_states, INLINE_FN_START);
 202         add_hook(&match_restore_states, INLINE_FN_END);
 203
 204 }
 205