check_freeing_null.c

   1 /*
   2  * Copyright (C) 2010 Dan Carpenter.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 #include "smatch.h"
  19
  20 static int my_id;
  21
  22 static void match_free(const char *fn, struct expression *expr, void *data)
  23 {
  24         struct expression *arg_expr;
  25         char *name;
  26         sval_t sval;
  27
  28         arg_expr = get_argument_from_call_expr(expr->args, 0);
  29         if (!get_implied_value(arg_expr, &sval))
  30                 return;
  31         if (sval.value != 0)
  32                 return;
  33         name = expr_to_var(arg_expr);
  34         sm_msg("warn: calling %s() when '%s' is always NULL.", fn, name);
  35         free_string(name);
  36 }
  37
  38 void check_freeing_null(int id)
  39 {
  40         my_id = id;
  41         if (!option_spammy)
  42                 return;
  43         if (option_project == PROJ_KERNEL)
  44                 add_function_hook("kfree", &match_free, NULL);
  45         else
  46                 add_function_hook("free", &match_free, NULL);
  47 }