check_deref_check.c

   1 /*
   2  * sparse/check_deref_check.c
   3  *
   4  * Copyright (C) 2009 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11 #include "smatch_extra.h"
  12
  13 static int my_id;
  14
  15 STATE(derefed);
  16
  17 static void underef(struct sm_state *sm)
  18 {
  19         set_state(my_id, sm->name, sm->sym, &undefined);
  20 }
  21
  22 static void match_dereference(struct expression *expr)
  23 {
  24         char *name;
  25
  26         if (expr->type != EXPR_PREOP)
  27                 return;
  28         if (getting_address())
  29                 return;
  30         expr = strip_expr(expr->unop);
  31         if (implied_not_equal(expr, 0))
  32                 return;
  33
  34         set_state_expr(my_id, expr, &derefed);
  35         name = get_variable_from_expr(expr, NULL);
  36         if (!name)
  37                 return;
  38         free_string(name);
  39 }
  40
  41 static void set_param_dereferenced(struct expression *arg, char *unused)
  42 {
  43         if (implied_not_equal(arg, 0))
  44                 return;
  45         set_state_expr(my_id, arg, &derefed);
  46 }
  47
  48 static void match_condition(struct expression *expr)
  49 {
  50         struct sm_state *sm;
  51
  52         if (__in_pre_condition)
  53                 return;
  54
  55         if (get_macro_name(expr->pos))
  56                 return;
  57
  58         sm = get_sm_state_expr(my_id, expr);
  59         if (!sm || sm->state != &derefed)
  60                 return;
  61
  62         sm_msg("warn: variable dereferenced before check '%s' (see line %d)", sm->name, sm->line);
  63         set_state_expr(my_id, expr, &undefined);
  64 }
  65
  66 void check_deref_check(int id)
  67 {
  68         my_id = id;
  69         add_hook(&match_dereference, DEREF_HOOK);
  70         add_hook(&match_condition, CONDITION_HOOK);
  71         add_db_fn_call_callback(DEREFERENCE, &set_param_dereferenced);
  72         add_modification_hook(my_id, &underef);
  73 }