check_double_fget.c

   1 /*
   2  * Copyright 2023 Linaro Ltd.
   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 /*
  19  * Once you've used an fd one time, you can't use it again.
  20  * But the problem is that an fd is just an int.  It might be nice if we
  21  * tracked this in smatch_units.c.  Another hacky thing (not nice) might
  22  * be to mark it as freed after use so it could show up as a use after
  23  * free.  But instead I am doing this.
  24  *
  25  */
  26
  27 #include "smatch.h"
  28 #include "smatch_slist.h"
  29
  30 static int my_id;
  31
  32 STATE(fget);
  33
  34 static void match_fget(struct expression *expr, const char *name, struct symbol *sym, void *data)
  35 {
  36         if (local_debug) {
  37                 struct sm_state *sm = get_sm_state(my_id, name, sym);
  38                 sm_msg("%s: expr='%s' name='%s' sm='%s'", __func__, expr_to_str(expr), name, show_sm(sm));
  39         }
  40         if (has_possible_state(my_id, name, sym, &fget))
  41                 sm_warning("double fget(): '%s'", name);
  42         set_state(my_id, name, sym, &fget);
  43 }
  44
  45 static void return_info_callback(int return_id, char *return_ranges,
  46                                  struct expression *returned_expr,
  47                                  int param,
  48                                  const char *printed_name,
  49                                  struct sm_state *sm)
  50 {
  51         sql_insert_return_states(return_id, return_ranges,
  52                                  FGET,
  53                                  param, printed_name, "");
  54 }
  55
  56 static void caller_info_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
  57 {
  58         if (strcmp(printed_name, "$") != 0)
  59                 return;
  60         sm_warning("fd re-used after fget(): '%s'", sm->name);
  61 }
  62
  63 void check_double_fget(int id)
  64 {
  65         if (option_project != PROJ_KERNEL)
  66                 return;
  67
  68         my_id = id;
  69
  70         add_function_param_key_hook("fget", &match_fget, 0, "$", NULL);
  71         add_function_param_key_hook("fdget", &match_fget, 0, "$", NULL);
  72         add_return_info_callback(my_id, return_info_callback);
  73         select_return_param_key(FGET, &match_fget);
  74
  75         add_caller_info_callback(my_id, caller_info_callback);
  76 }