check_dereferences_param.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   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  * This is an --info recipe.  The goal is to print a message for every parameter
  20  * which we can not avoid dereferencing.  This is maybe a bit restrictive but it
  21  * avoids some false positives.
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_extra.h"
  26 #include "smatch_slist.h"
  27
  28 static int my_id;
  29
  30 STATE(derefed);
  31 STATE(ignore);
  32 STATE(param);
  33
  34 static int is_arg(struct expression *expr)
  35 {
  36         struct symbol *arg;
  37
  38         if (expr->type != EXPR_SYMBOL)
  39                 return 0;
  40
  41         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
  42                 if (arg == expr->symbol)
  43                         return 1;
  44         } END_FOR_EACH_PTR(arg);
  45         return 0;
  46 }
  47
  48 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  49 {
  50         if (sm->state == &derefed)
  51                 return;
  52         set_state(my_id, sm->name, sm->sym, &ignore);
  53 }
  54
  55 static void match_function_def(struct symbol *sym)
  56 {
  57         struct symbol *arg;
  58         int i;
  59
  60         i = -1;
  61         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
  62                 i++;
  63                 if (!arg->ident)
  64                         continue;
  65                 set_state(my_id, arg->ident->name, arg, &param);
  66         } END_FOR_EACH_PTR(arg);
  67 }
  68
  69 static void check_deref(struct expression *expr)
  70 {
  71         struct expression *tmp;
  72         struct sm_state *sm;
  73
  74         tmp = get_assigned_expr(expr);
  75         if (tmp)
  76                 expr = tmp;
  77         expr = strip_expr(expr);
  78
  79         if (!is_arg(expr))
  80                 return;
  81
  82         sm = get_sm_state_expr(my_id, expr);
  83         if (sm && slist_has_state(sm->possible, &ignore))
  84                 return;
  85         set_state_expr(my_id, expr, &derefed);
  86 }
  87
  88 static void match_dereference(struct expression *expr)
  89 {
  90         if (expr->type != EXPR_PREOP)
  91                 return;
  92         if (getting_address())
  93                 return;
  94         check_deref(expr->unop);
  95 }
  96
  97 static void set_param_dereferenced(struct expression *arg, char *unused)
  98 {
  99         check_deref(arg);
 100 }
 101
 102 static void process_states(struct stree *stree)
 103 {
 104         struct symbol *arg;
 105         int i;
 106
 107         i = -1;
 108         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 109                 i++;
 110                 if (!arg->ident)
 111                         continue;
 112                 if (get_state_stree(stree, my_id, arg->ident->name, arg) == &derefed)
 113                         sql_insert_call_implies(DEREFERENCE, i, 1);
 114         } END_FOR_EACH_PTR(arg);
 115 }
 116
 117 void check_dereferences_param(int id)
 118 {
 119         my_id = id;
 120
 121         add_hook(&match_function_def, FUNC_DEF_HOOK);
 122
 123         add_hook(&match_dereference, DEREF_HOOK);
 124         select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);
 125         add_modification_hook(my_id, &set_ignore);
 126
 127         all_return_states_hook(&process_states);
 128 }