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 STATE(oktocheck);
  17
  18 static void underef(const char *name, struct symbol *sym, struct expression *expr, void *unused)
  19 {
  20         set_state(my_id, name, sym, &oktocheck);
  21 }
  22
  23 static void match_dereference(struct expression *expr)
  24 {
  25         char *name;
  26
  27         if (expr->type != EXPR_PREOP)
  28                 return;
  29         if (getting_address())
  30                 return;
  31
  32         expr = strip_expr(expr->unop);
  33         if (implied_not_equal(expr, 0))
  34                 return;
  35         set_state_expr(my_id, expr, &derefed);
  36         name = get_variable_from_expr(expr, NULL);
  37         if (!name)
  38                 return;
  39         add_modification_hook(my_id, name, &underef, NULL);
  40         free_string(name);
  41 }
  42
  43 static void set_param_dereferenced(struct expression *arg, char *unused)
  44 {
  45         set_state_expr(my_id, arg, &derefed);
  46         add_modification_hook_expr(my_id, arg, &underef, NULL);
  47 }
  48
  49 static void match_condition(struct expression *expr)
  50 {
  51         struct sm_state *sm;
  52
  53         if (__in_pre_condition)
  54                 return;
  55
  56         if (get_macro_name(expr->pos))
  57                 return;
  58
  59         sm = get_sm_state_expr(my_id, expr);
  60         if (!sm || sm->state != &derefed)
  61                 return;
  62         if (implied_not_equal(expr, 0))
  63                 return;
  64
  65         sm_msg("warn: variable dereferenced before check '%s' (see line %d)", sm->name, sm->line);
  66         set_state_expr(my_id, expr, &oktocheck);
  67 }
  68
  69 void check_deref_check(int id)
  70 {
  71         my_id = id;
  72         add_hook(&match_dereference, DEREF_HOOK);
  73         add_hook(&match_condition, CONDITION_HOOK);
  74         add_db_fn_call_callback(DEREFERENCE, &set_param_dereferenced);
  75 }