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 void save_start_states(struct statement *stmt)
  40 {
  41         start_states = get_all_states(SMATCH_EXTRA);
  42 }
  43
  44 static void match_end_func(void)
  45 {
  46         free_slist(&start_states);
  47 }
  48
  49 static struct smatch_state *unmatched_state(struct sm_state *sm)
  50 {
  51         return &original;
  52 }
  53
  54 static struct smatch_state *filter_my_sm(struct sm_state *sm)
  55 {
  56         struct range_list *ret = NULL;
  57         struct sm_state *tmp;
  58         struct smatch_state *estate;
  59
  60         FOR_EACH_PTR(sm->possible, tmp) {
  61                 if (tmp->state == &merged)
  62                         continue;
  63                 if (tmp->state == &original) {
  64                         estate = get_state_slist(tmp->pool, SMATCH_EXTRA, tmp->name, tmp->sym);
  65                         if (!estate) {
  66                                 sm_msg("debug: no value found in pool %p", tmp->pool);
  67                                 continue;
  68                         }
  69                 } else {
  70                         estate = tmp->state;
  71                 }
  72                 ret = rl_union(ret, estate_rl(estate));
  73         } END_FOR_EACH_PTR(tmp);
  74
  75         return alloc_estate_rl(ret);
  76 }
  77
  78 struct smatch_state *get_orig_estate(const char *name, struct symbol *sym)
  79 {
  80         struct sm_state *sm;
  81         struct smatch_state *state;
  82
  83         sm = get_sm_state(my_id, name, sym);
  84         if (sm)
  85                 return filter_my_sm(sm);
  86
  87         state = get_state(SMATCH_EXTRA, name, sym);
  88         if (state)
  89                 return state;
  90         return alloc_estate_rl(alloc_whole_rl(get_real_base_type(sym)));
  91 }
  92
  93 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr, struct state_list *slist)
  94 {
  95         struct state_list *extra_slist;
  96         struct sm_state *tmp;
  97         struct sm_state *my_sm;
  98         struct smatch_state *state;
  99         int param;
 100
 101         extra_slist = get_all_states_slist(SMATCH_EXTRA, slist);
 102
 103         FOR_EACH_PTR(extra_slist, tmp) {
 104                 if (!tmp->sym->ident || strcmp(tmp->name, tmp->sym->ident->name) != 0)
 105                         continue;
 106
 107                 param = get_param_num_from_sym(tmp->sym);
 108                 if (param < 0)
 109                         continue;
 110
 111                 my_sm = get_sm_state_slist(slist, my_id, tmp->name, tmp->sym);
 112                 if (!my_sm) {
 113                         struct smatch_state *old;
 114
 115                         old = get_state_slist(start_states, SMATCH_EXTRA, tmp->name, tmp->sym);
 116                         if (old && estates_equiv(old, tmp->state))
 117                                 continue;
 118                         sql_insert_return_states(return_id, return_ranges,
 119                                         LIMITED_VALUE, param, "$$",
 120                                         tmp->state->name);
 121                         continue;
 122                 }
 123
 124                 state = filter_my_sm(my_sm);
 125                 if (!state)
 126                         continue;
 127                 /* This represents an impossible state.  I screwd up.  Bail. */
 128                 if (!estate_rl(state))
 129                         continue;
 130                 sql_insert_return_states(return_id, return_ranges,
 131                                         LIMITED_VALUE, param, "$$",
 132                                         state->name);
 133         } END_FOR_EACH_PTR(tmp);
 134
 135         free_slist(&extra_slist);
 136 }
 137
 138 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
 139 {
 140         struct smatch_state *orig_vals;
 141         int param;
 142
 143         param = get_param_num_from_sym(sym);
 144         if (param < 0)
 145                 return;
 146
 147         /* we are only saving params for now */
 148         if (!sym->ident || strcmp(name, sym->ident->name) != 0)
 149                 return;
 150
 151         orig_vals = get_orig_estate(name, sym);
 152         set_state(my_id, name, sym, orig_vals);
 153 }
 154
 155 void register_param_limit(int id)
 156 {
 157         if (!option_info)
 158                 return;
 159
 160         my_id = id;
 161
 162         add_hook(&save_start_states, AFTER_DEF_HOOK);
 163         add_extra_mod_hook(&extra_mod_hook);
 164         add_unmatched_state_hook(my_id, &unmatched_state);
 165         add_returned_state_callback(&print_return_value_param);
 166         add_hook(&match_end_func, END_FUNC_HOOK);
 167 }
 168