check_freeing_null.c

   1 /*
   2  * sparse/check_freeing_null.c
   3  *
   4  * Copyright (C) 2010 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11
  12 static int my_id;
  13
  14 static void match_free(const char *fn, struct expression *expr, void *data)
  15 {
  16         struct expression *arg_expr;
  17         char *name;
  18         sval_t sval;
  19
  20         arg_expr = get_argument_from_call_expr(expr->args, 0);
  21         if (!get_implied_value_sval(arg_expr, &sval))
  22                 return;
  23         if (sval.value != 0)
  24                 return;
  25         name = get_variable_from_expr(arg_expr, NULL);
  26         sm_msg("warn: calling %s() when '%s' is always NULL.", fn, name);
  27         free_string(name);
  28 }
  29
  30 void check_freeing_null(int id)
  31 {
  32         my_id = id;
  33         if (!option_spammy)
  34                 return;
  35         if (option_project == PROJ_KERNEL)
  36                 add_function_hook("kfree", &match_free, NULL);
  37         else
  38                 add_function_hook("free", &match_free, NULL);
  39 }