smatch_param_filter.c

   1 /*
   2  * sparse/smatch_param_filter.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:
  12  *
  13  * void foo(int *x)
  14  * {
  15  *      if (*x == 42)
  16  *              *x = 0;
  17  * }
  18  *
  19  * The final value of *x depends on the input to the function but with *x == 42
  20  * filtered out.
  21  *
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_extra.h"
  26 #include "smatch_slist.h"
  27
  28 static int my_id;
  29
  30 STATE(modified);
  31 STATE(original);
  32
  33 static struct state_list *start_states;
  34 static struct state_list_stack *saved_stack;
  35 static void save_start_states(struct statement *stmt)
  36 {
  37         start_states = get_all_states(SMATCH_EXTRA);
  38 }
  39
  40 static void match_end_func(void)
  41 {
  42         free_slist(&start_states);
  43 }
  44
  45 static void match_save_states(struct expression *expr)
  46 {
  47         push_slist(&saved_stack, start_states);
  48         start_states = NULL;
  49 }
  50
  51 static void match_restore_states(struct expression *expr)
  52 {
  53         start_states = pop_slist(&saved_stack);
  54 }
  55
  56 static struct smatch_state *unmatched_state(struct sm_state *sm)
  57 {
  58         return &original;
  59 }
  60
  61 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
  62 {
  63         int param;
  64
  65         param = get_param_num_from_sym(sym);
  66         if (param < 0)
  67                 return;
  68
  69         set_state(my_id, name, sym, &modified);
  70 }
  71
  72 static struct range_list *get_orig_rl(struct sm_state *sm)
  73 {
  74         struct range_list *ret = NULL;
  75         struct sm_state *tmp;
  76         struct smatch_state *extra;
  77
  78         FOR_EACH_PTR(sm->possible, tmp) {
  79                 if (tmp->state != &original)
  80                         continue;
  81                 extra = get_state_slist(tmp->pool, SMATCH_EXTRA, tmp->name, tmp->sym);
  82                 if (!extra) {
  83 //                      sm_msg("debug: no value found in pool %p", tmp->pool);
  84                         return NULL;
  85                 }
  86                 ret = rl_union(ret, estate_rl(extra));
  87         } END_FOR_EACH_PTR(tmp);
  88         return ret;
  89 }
  90
  91 static void print_one_mod_param(int return_id, char *return_ranges,
  92                         int param, struct sm_state *sm)
  93 {
  94         const char *param_name;
  95         struct range_list *rl;
  96
  97         param_name = get_param_name(sm);
  98         if (!param_name)
  99                 return;
 100         rl = get_orig_rl(sm);
 101         if (is_whole_rl(rl))
 102                 return;
 103
 104         sql_insert_return_states(return_id, return_ranges, FILTER_VALUE, param,
 105                         param_name, show_rl(rl));
 106 }
 107
 108 static void print_one_extra_param(int return_id, char *return_ranges,
 109                         int param, struct sm_state *sm)
 110 {
 111         struct smatch_state *old;
 112         const char *param_name;
 113
 114         if (estate_is_whole(sm->state))
 115                 return;
 116         old = get_state_slist(start_states, SMATCH_EXTRA, sm->name, sm->sym);
 117         if (old && estates_equiv(old, sm->state))
 118                 return;
 119
 120         param_name = get_param_name(sm);
 121         if (!param_name)
 122                 return;
 123
 124         sql_insert_return_states(return_id, return_ranges, FILTER_VALUE, param,
 125                         param_name, sm->state->name);
 126 }
 127
 128 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 129 {
 130         struct state_list *extra_slist;
 131         struct sm_state *tmp;
 132         struct sm_state *sm;
 133         int param;
 134
 135         extra_slist = get_all_states(SMATCH_EXTRA);
 136
 137         FOR_EACH_PTR(extra_slist, tmp) {
 138                 param = get_param_num_from_sym(tmp->sym);
 139                 if (param < 0)
 140                         continue;
 141                 /*
 142                  * skip the parameter itself because that's handled by
 143                  * smatch_param_limit.c.
 144                  */
 145                 if (tmp->sym->ident && strcmp(tmp->sym->ident->name, tmp->name) == 0)
 146                         continue;
 147
 148                 sm = get_sm_state(my_id, tmp->name, tmp->sym);
 149                 if (sm)
 150                         print_one_mod_param(return_id, return_ranges, param, sm);
 151                 else
 152                         print_one_extra_param(return_id, return_ranges, param, tmp);
 153         } END_FOR_EACH_PTR(tmp);
 154
 155         free_slist(&extra_slist);
 156 }
 157
 158 void register_param_filter(int id)
 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_split_return_callback(&print_return_value_param);
 166         add_hook(&match_end_func, END_FUNC_HOOK);
 167         add_hook(&match_save_states, INLINE_FN_START);
 168         add_hook(&match_restore_states, INLINE_FN_END);
 169 }
 170