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 *my_slist;
  96         struct sm_state *tmp;
  97         struct smatch_state *state;
  98         int param;
  99
 100         my_slist = get_all_states_slist(my_id, slist);
 101
 102         FOR_EACH_PTR(my_slist, tmp) {
 103                 param = get_param_num_from_sym(tmp->sym);
 104                 if (param < 0)
 105                         continue;
 106                 state = filter_my_sm(tmp);
 107                 if (!state)
 108                         continue;
 109                 /* This represents an impossible state.  I screwd up.  Bail. */
 110                 if (!estate_rl(state))
 111                         continue;
 112                 sm_msg("info: return_param_limit %d %d '%s' '$$' '%s' %s",
 113                        return_id, param, return_ranges,
 114                        state->name, global_static());
 115         } END_FOR_EACH_PTR(tmp);
 116
 117         free_slist(&my_slist);
 118 }
 119
 120
 121
 122 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
 123 {
 124         struct smatch_state *orig_vals;
 125         int param;
 126
 127         param = get_param_num_from_sym(sym);
 128         if (param < 0)
 129                 return;
 130
 131         /* we are only saving params for now */
 132         if (!sym->ident || strcmp(name, sym->ident->name) != 0)
 133                 return;
 134
 135         orig_vals = get_orig_estate(name, sym);
 136         set_state(my_id, name, sym, orig_vals);
 137 }
 138
 139 void register_param_limit(int id)
 140 {
 141         if (!option_info)
 142                 return;
 143
 144         my_id = id;
 145
 146         add_hook(&save_start_states, AFTER_DEF_HOOK);
 147         add_extra_mod_hook(&extra_mod_hook);
 148         add_unmatched_state_hook(my_id, &unmatched_state);
 149         add_returned_state_callback(&print_return_value_param);
 150         add_hook(&match_end_func, END_FUNC_HOOK);
 151 }
 152