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 void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  35 {
  36         if (sm->state == &derefed)
  37                 return;
  38         set_state(my_id, sm->name, sm->sym, &ignore);
  39 }
  40 
  41 static void match_function_def(struct symbol *sym)
  42 {
  43         struct symbol *arg;
  44         int i;
  45 
  46         i = -1;
  47         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
  48                 i++;
  49                 if (!arg->ident)
  50                         continue;
  51                 set_state(my_id, arg->ident->name, arg, &param);
  52         } END_FOR_EACH_PTR(arg);
  53 }
  54 
  55 static void check_deref(struct expression *expr)
  56 {
  57         struct expression *tmp;
  58         struct sm_state *sm;
  59 
  60         tmp = get_assigned_expr(expr);
  61         if (tmp)
  62                 expr = tmp;
  63         expr = strip_expr(expr);
  64 
  65         if (get_param_num(expr) < 0)
  66                 return;
  67 
  68         if (param_was_set(expr))
  69                 return;
  70 
  71         sm = get_sm_state_expr(my_id, expr);
  72         if (sm && slist_has_state(sm->possible, &ignore))
  73                 return;
  74         set_state_expr(my_id, expr, &derefed);
  75 }
  76 
  77 static void match_dereference(struct expression *expr)
  78 {
  79         if (expr->type != EXPR_PREOP)
  80                 return;
  81         if (getting_address())
  82                 return;
  83         check_deref(expr->unop);
  84 }
  85 
  86 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
  87 {
  88         /* XXX FIXME: param_implies has more information now */
  89         if (strcmp(key, "$") != 0)
  90                 return;
  91         check_deref(arg);
  92 }
  93 
  94 static void process_states(void)
  95 {
  96         struct sm_state *tmp;
  97         int arg;
  98         const char *name;
  99 
 100         FOR_EACH_MY_SM(my_id, __get_cur_stree(), tmp) {
 101                 if (tmp->state != &derefed)
 102                         continue;
 103                 arg = get_param_num_from_sym(tmp->sym);
 104                 if (arg < 0)
 105                         continue;
 106                 name = get_param_name(tmp);
 107                 if (!name)
 108                         continue;
 109                 sql_insert_return_implies(DEREFERENCE, arg, name, "1");
 110         } END_FOR_EACH_SM(tmp);
 111 }
 112 
 113 static void match_pointer_as_array(struct expression *expr)
 114 {
 115         if (!is_array(expr))
 116                 return;
 117         check_deref(get_array_base(expr));
 118 }
 119 
 120 void check_dereferences_param(int id)
 121 {
 122         my_id = id;
 123 
 124         add_hook(&match_function_def, FUNC_DEF_HOOK);
 125 
 126         add_hook(&match_dereference, DEREF_HOOK);
 127         add_hook(&match_pointer_as_array, OP_HOOK);
 128         select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
 129         add_modification_hook(my_id, &set_ignore);
 130 
 131         all_return_states_hook(&process_states);
 132 }