FormatterServices.CheckTypeSecurity(Type, TypeFilterLevel) FormatterServices.CheckTypeSecurity(Type, TypeFilterLevel) FormatterServices.CheckTypeSecurity(Type, TypeFilterLevel) FormatterServices.CheckTypeSecurity(Type, TypeFilterLevel) Method

Definition

Determines whether the specified Type can be deserialized with the TypeFilterLevel property set to Low.

public:
 static void CheckTypeSecurity(Type ^ t, System::Runtime::Serialization::Formatters::TypeFilterLevel securityLevel);
public static void CheckTypeSecurity (Type t, System.Runtime.Serialization.Formatters.TypeFilterLevel securityLevel);
static member CheckTypeSecurity : Type * System.Runtime.Serialization.Formatters.TypeFilterLevel -> unit
Public Shared Sub CheckTypeSecurity (t As Type, securityLevel As TypeFilterLevel)

Parameters

t
Type Type Type Type

The Type to check for the ability to deserialize.

Exceptions

The t parameter is an advanced type and cannot be deserialized when the TypeFilterLevel property is set to Low.

Examples

This example shows how to use the FormatterServices class to serialize or deserialize an object where the base class does not implement ISerializable but the derived class does.

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization;
using namespace System::Runtime::Serialization::Formatters;
using namespace System::Runtime::Serialization::Formatters::Binary;
using namespace System::Reflection;
using namespace System::Security::Permissions;

// Person is a serializable base class.
[Serializable]
public ref class Person
{
private:
    String^ title;

public:
    Person(String^ title)
    {
        this->title = title;
    }

public:
    virtual String^ ToString() override
    {
        return String::Format("{0}", title);
    }
};

// Employee is a serializable class derived from Person.
[Serializable]
public ref class Employee : public Person
{
private:
    String^ title;

public:
    Employee(String^ title) : Person("Person")
    {
        this->title = title;
    }

public:
    virtual String^ ToString() override
    {
        return String::Format("{0} -> {1}", title, Person::ToString());
    }
};

// Manager is a serializable and ISerializable class derived from Employee.
[Serializable]
ref class Manager : public Employee, public ISerializable
{
private:
    String^ title;

public:
    Manager() : Employee("Employee")
    {
        this->title = "Manager";
    }

public:
    [SecurityPermission(SecurityAction::Demand, SerializationFormatter = true)]
    virtual void GetObjectData(SerializationInfo^ info, StreamingContext context)
    {
        // Serialize the desired values for this class.
        info->AddValue("title", title);

        // Get the set of serializable members for the class and base classes.
        Type^ thisType = this->GetType();
        array<MemberInfo^>^ serializableMembers =
            FormatterServices::GetSerializableMembers(thisType, context);

        // Serialize the base class's fields to the info object.
        for each (MemberInfo^ serializableMember in serializableMembers)
        {
            // Do not serialize fields for this class.
            if (serializableMember->DeclaringType != thisType)
            {
                // Skip this field if it is marked NonSerialized.
                if (!(Attribute::IsDefined(serializableMember,
                    NonSerializedAttribute::typeid)))
                {
                    // Get the value of this field and add it to the
                    // SerializationInfo object.
                    info->AddValue(serializableMember->Name,
                        ((FieldInfo^)serializableMember)->GetValue(this));
                }
            }
        }

        // Call the method below to see the contents of the
        // SerializationInfo object.
        DisplaySerializationInfo(info);
    }

private:
    static void DisplaySerializationInfo(SerializationInfo^ info)
    {
        Console::WriteLine("Values in the SerializationInfo:");
        for each (SerializationEntry^ infoEntry in info)
        {
            Console::WriteLine("Name={0}, ObjectType={1}, Value={2}",
                infoEntry->Name, infoEntry->ObjectType, infoEntry->Value);
        }
    }

protected:
    Manager(SerializationInfo^ info,
        StreamingContext context) : Employee(nullptr)
    {
        // Get the set of serializable members for the class and base classes.
        Type^ thisType = this->GetType();
        array<MemberInfo^>^ serializableMembers =
            FormatterServices::GetSerializableMembers(thisType, context);

        // Deserialize the base class's fields from the info object.
        for each (MemberInfo^ serializableMember in serializableMembers)
        {
            // Do not deserialize fields for this class.
            if (serializableMember->DeclaringType != thisType)
            {
                // For easier coding, treat the member as a FieldInfo object
                FieldInfo^ fieldInformation = (FieldInfo^)serializableMember;

                // Skip this field if it is marked NonSerialized.
                if (!(Attribute::IsDefined(serializableMember,
                    NonSerializedAttribute::typeid)))
                {
                    // Get the value of this field from the
                    // SerializationInfo object.
                    fieldInformation->SetValue(this,
                        info->GetValue(fieldInformation->Name,
                        fieldInformation->FieldType));
                }
            }
        }

        // Deserialize the values that were serialized for this class.
        title = info->GetString("title");
    }

public:
    virtual String^ ToString() override
    {
        return String::Format("{0} -> {1}", title, Employee::ToString());
    }
};

int main()
{
    Stream^ stream = gcnew MemoryStream();
    IFormatter^ formatter = gcnew BinaryFormatter();
    Manager^ m = gcnew Manager();
    Console::WriteLine(m->ToString());
    formatter->Serialize(stream, m);

    stream->Position = 0;
    m = (Manager^) formatter->Deserialize(stream);
    Console::WriteLine(m->ToString());
}

// This code produces the following output.
//
//  Manager -> Employee -> Person
//  Values in the SerializaitonInfo:
//  Name=title, ObjectType=System.String, Value=Manager
//  Name=Employee+title, ObjectType=System.String, Value=Employee
//  Name=Person+title, ObjectType=System.String, Value=Person
//  Manager -> Employee -> Person
using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters;
using System.Runtime.Serialization.Formatters.Binary;
using System.Reflection;
using System.Security.Permissions;


// Person is a serializable base class.
[Serializable]
public class Person
{
    private String title;

    public Person(String title)
    {
        this.title = title;
    }

    public override String ToString()
    {
        return String.Format("{0}", title);
    }
}

// Employee is a serializable class derived from Person.
[Serializable]
public class Employee : Person
{
    private String title;

    public Employee(String title) : base("Person")
    {
        this.title = title;
    }

    public override String ToString()
    {
        return String.Format("{0} -> {1}", title, base.ToString());
    }
}

// Manager is a serializable and ISerializable class derived from Employee.
[Serializable]
public class Manager : Employee, ISerializable
{
    private String title;

    public Manager() : base("Employee") 
    {
        this.title = "Manager";
    }

    [SecurityPermission(SecurityAction.Demand, SerializationFormatter = true)]
    public void GetObjectData(SerializationInfo info, StreamingContext context)
    {

        // Serialize the desired values for this class.
        info.AddValue("title", title);

        // Get the set of serializable members for the class and base classes.
        Type thisType = this.GetType();
        MemberInfo[] mi = FormatterServices.GetSerializableMembers(thisType, context);

        // Serialize the base class's fields to the info object.
        for (Int32 i = 0; i < mi.Length; i++)
        {
            // Do not serialize fields for this class.
            if (mi[i].DeclaringType == thisType) continue;

            // Skip this field if it is marked NonSerialized.
            if (Attribute.IsDefined(mi[i], typeof(NonSerializedAttribute))) continue;
         
            // Get the value of this field and add it to the SerializationInfo object.
            info.AddValue(mi[i].Name, ((FieldInfo) mi[i]).GetValue(this));
        }

        // Call the method below to see the contents of the SerializationInfo object.
        DisplaySerializationInfo(info);
    }
 
    private void DisplaySerializationInfo(SerializationInfo info)
    {
        SerializationInfoEnumerator e = info.GetEnumerator();
        Console.WriteLine("Values in the SerializationInfo:");
        while (e.MoveNext())
        {
            Console.WriteLine("Name={0}, ObjectType={1}, Value={2}", e.Name, e.ObjectType, e.Value);
        }
    }

    [SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.SerializationFormatter)]
    protected Manager(SerializationInfo info, StreamingContext context) : base(null)
    {

        // Get the set of serializable members for the class and base classes.
        Type thisType = this.GetType();
        MemberInfo[] mi = FormatterServices.GetSerializableMembers(thisType, context);

        // Deserialize the base class's fields from the info object.
        for (Int32 i = 0; i < mi.Length; i++)
        {
            // Do not deserialize fields for this class.
            if (mi[i].DeclaringType == thisType) continue;

            // For easier coding, treat the member as a FieldInfo object
            FieldInfo fi = (FieldInfo) mi[i];

            // Skip this field if it is marked NonSerialized.
            if (Attribute.IsDefined(mi[i], typeof(NonSerializedAttribute))) continue;

            // Get the value of this field from the SerializationInfo object.
            fi.SetValue(this, info.GetValue(fi.Name, fi.FieldType));
        }

        // Deserialize the values that were serialized for this class.
        title = info.GetString("title");
    }

    public override String ToString()
    {
        return String.Format("{0} -> {1}", title, base.ToString());
    }
}


public sealed class App
{
    public static void Main()
    {
        Run();
    }

    public static void Run()
    {
        using (Stream stream = new MemoryStream())
	{
            IFormatter formatter = new BinaryFormatter();
            Manager m = new Manager();
            Console.WriteLine(m.ToString());
            formatter.Serialize(stream, m);

            stream.Position = 0;
            m = (Manager) formatter.Deserialize(stream);
            Console.WriteLine(m.ToString());
        }
    }
}
// This code produces the following output.
//
//  Manager -> Employee -> Person
//  Values in the SerializaitonInfo:
//  Name=title, ObjectType=System.String, Value=Manager
//  Name=Employee+title, ObjectType=System.String, Value=Employee
//  Name=Person+title, ObjectType=System.String, Value=Person
//  Manager -> Employee -> Person

Remarks

Use this method to determine whether a specified type can be deserialized when the TypeFilterLevel property is set to Low.

.NET Framework remoting provides two levels of automatic deserialization, Low and Full. Low helps protect against deserialization attacks by deserializing only the types associated with the most basic remoting functionality. The Full deserialization level supports automatic deserialization of all types that remoting supports in all situations. For more information about the.NET Framework remoting types that Low and Full support, see Automatic Deserialization in .NET Framework Remoting.

Applies to

See also