smatch_param_limit.c

   1 /*
   2  * sparse/smatch_param_limit.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * This is for functions like this:
  12  *
  13  * int foo(int a)
  14  * {
  15  *        if (a >= 0 && a < 10) {
  16  *                 a = 42;
  17  *                 return 1;
  18  *        }
  19  *        return 0;
  20  * }
  21  *
  22  * If we pass in 5, it returns 1.
  23  *
  24  * It's a bit complicated because we can't just consider the final value, we
  25  * have to always consider the passed in value.
  26  *
  27  */
  28
  29 #include "scope.h"
  30 #include "smatch.h"
  31 #include "smatch_extra.h"
  32 #include "smatch_slist.h"
  33
  34 static int my_id;
  35
  36 STATE(original);
  37
  38 static struct state_list *start_states;
  39 static struct state_list_stack *saved_stack;
  40
  41 static void save_start_states(struct statement *stmt)
  42 {
  43         start_states = get_all_states(SMATCH_EXTRA);
  44 }
  45
  46 static void match_end_func(void)
  47 {
  48         free_slist(&start_states);
  49 }
  50
  51 static struct smatch_state *unmatched_state(struct sm_state *sm)
  52 {
  53         return &original;
  54 }
  55
  56 static struct smatch_state *filter_my_sm(struct sm_state *sm)
  57 {
  58         struct range_list *ret = NULL;
  59         struct sm_state *tmp;
  60         struct smatch_state *estate;
  61
  62         FOR_EACH_PTR(sm->possible, tmp) {
  63                 if (tmp->state == &merged)
  64                         continue;
  65                 if (tmp->state == &original) {
  66                         estate = get_state_slist(tmp->pool, SMATCH_EXTRA, tmp->name, tmp->sym);
  67                         if (!estate) {
  68 //                              sm_msg("debug: no value found in pool %p", tmp->pool);
  69                                 continue;
  70                         }
  71                 } else {
  72                         estate = tmp->state;
  73                 }
  74                 ret = rl_union(ret, estate_rl(estate));
  75         } END_FOR_EACH_PTR(tmp);
  76
  77         return alloc_estate_rl(ret);
  78 }
  79
  80 struct smatch_state *get_orig_estate(const char *name, struct symbol *sym)
  81 {
  82         struct sm_state *sm;
  83         struct smatch_state *state;
  84
  85         sm = get_sm_state(my_id, name, sym);
  86         if (sm)
  87                 return filter_my_sm(sm);
  88
  89         state = get_state(SMATCH_EXTRA, name, sym);
  90         if (state)
  91                 return state;
  92         return alloc_estate_rl(alloc_whole_rl(get_real_base_type(sym)));
  93 }
  94
  95 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr, struct state_list *slist)
  96 {
  97         struct state_list *extra_slist;
  98         struct sm_state *tmp;
  99         struct sm_state *my_sm;
 100         struct smatch_state *state;
 101         int param;
 102
 103         extra_slist = get_all_states_slist(SMATCH_EXTRA, slist);
 104
 105         FOR_EACH_PTR(extra_slist, tmp) {
 106                 if (!tmp->sym->ident || strcmp(tmp->name, tmp->sym->ident->name) != 0)
 107                         continue;
 108
 109                 param = get_param_num_from_sym(tmp->sym);
 110                 if (param < 0)
 111                         continue;
 112
 113                 my_sm = get_sm_state_slist(slist, my_id, tmp->name, tmp->sym);
 114                 if (!my_sm) {
 115                         struct smatch_state *old;
 116
 117                         old = get_state_slist(start_states, SMATCH_EXTRA, tmp->name, tmp->sym);
 118                         if (old && estates_equiv(old, tmp->state))
 119                                 continue;
 120                         sql_insert_return_states(return_id, return_ranges,
 121                                         LIMITED_VALUE, param, "$$",
 122                                         tmp->state->name);
 123                         continue;
 124                 }
 125
 126                 state = filter_my_sm(my_sm);
 127                 if (!state)
 128                         continue;
 129                 /* This represents an impossible state.  I screwd up.  Bail. */
 130                 if (!estate_rl(state))
 131                         continue;
 132                 sql_insert_return_states(return_id, return_ranges,
 133                                         LIMITED_VALUE, param, "$$",
 134                                         state->name);
 135         } END_FOR_EACH_PTR(tmp);
 136
 137         free_slist(&extra_slist);
 138 }
 139
 140 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
 141 {
 142         struct smatch_state *orig_vals;
 143         int param;
 144
 145         param = get_param_num_from_sym(sym);
 146         if (param < 0)
 147                 return;
 148
 149         /* we are only saving params for now */
 150         if (!sym->ident || strcmp(name, sym->ident->name) != 0)
 151                 return;
 152
 153         orig_vals = get_orig_estate(name, sym);
 154         set_state(my_id, name, sym, orig_vals);
 155 }
 156
 157 static void match_save_states(struct expression *expr)
 158 {
 159         push_slist(&saved_stack, start_states);
 160         start_states = NULL;
 161 }
 162
 163 static void match_restore_states(struct expression *expr)
 164 {
 165         start_states = pop_slist(&saved_stack);
 166 }
 167
 168 void register_param_limit(int id)
 169 {
 170         my_id = id;
 171
 172         add_hook(&save_start_states, AFTER_DEF_HOOK);
 173         add_extra_mod_hook(&extra_mod_hook);
 174         add_unmatched_state_hook(my_id, &unmatched_state);
 175         add_returned_state_callback(&print_return_value_param);
 176         add_hook(&match_end_func, END_FUNC_HOOK);
 177         add_hook(&match_save_states, INLINE_FN_START);
 178         add_hook(&match_restore_states, INLINE_FN_END);
 179
 180 }
 181