CodeAccessPermission.IsSubsetOf(IPermission) Method
Definition
Important
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When implemented by a derived class, determines whether the current permission is a subset of the specified permission.
public:
abstract bool IsSubsetOf(System::Security::IPermission ^ target);public abstract bool IsSubsetOf (System.Security.IPermission target);abstract member IsSubsetOf : System.Security.IPermission -> boolPublic MustOverride Function IsSubsetOf (target As IPermission) As BooleanParameters
- target
- IPermission
A permission that is to be tested for the subset relationship. This permission must be of the same type as the current permission.
Returns
true if the current permission is a subset of the specified permission; otherwise, false.
Implements
Exceptions
The target parameter is not null and is not of the same type as the current permission.
Examples
The following code example shows an override of the IsSubsetOf method. This code example is part of a larger example provided for the CodeAccessPermission class.
public:
virtual bool IsSubsetOf( IPermission^ target ) override
{
#if ( debug )
Console::WriteLine( "************* Entering IsSubsetOf *********************" );
#endif
if ( target == nullptr )
{
Console::WriteLine( "IsSubsetOf: target == null" );
return false;
}
#if ( debug )
Console::WriteLine( "This is = {0}", ((NameIdPermission)this).Name );
Console::WriteLine( "Target is {0}", ((NameIdPermission)target).m_Name );
#endif
try
{
NameIdPermission^ operand = dynamic_cast<NameIdPermission^>(target);
// The following check for unrestricted permission is only included as an example for
// permissions that allow the unrestricted state. It is of no value for this permission.
if ( true == operand->m_Unrestricted )
{
return true;
}
else if ( true == this->m_Unrestricted )
{
return false;
}
if ( this->m_Name != nullptr )
{
if ( operand->m_Name == nullptr )
{
return false;
}
if ( this->m_Name->Equals( "" ) )
{
return true;
}
}
if ( this->m_Name->Equals( operand->m_Name ) )
{
return true;
}
else
{
// Check for wild card character '*'.
int i = operand->m_Name->LastIndexOf( "*" );
if ( i > 0 )
{
String^ prefix = operand->m_Name->Substring( 0, i );
if ( this->m_Name->StartsWith( prefix ) )
{
return true;
}
}
}
return false;
}
catch ( InvalidCastException^ )
{
throw gcnew ArgumentException( String::Format( "Argument_WrongType", this->GetType()->FullName ) );
}
}
public override bool IsSubsetOf(IPermission target)
{
#if(debug)
Console.WriteLine ("************* Entering IsSubsetOf *********************");
#endif
if (target == null)
{
Console.WriteLine ("IsSubsetOf: target == null");
return false;
}
#if(debug)
Console.WriteLine ("This is = " + (( NameIdPermission)this).Name);
Console.WriteLine ("Target is " + (( NameIdPermission)target).m_Name);
#endif
try
{
NameIdPermission operand = ( NameIdPermission)target;
// The following check for unrestricted permission is only included as an example for
// permissions that allow the unrestricted state. It is of no value for this permission.
if (true == operand.m_Unrestricted)
{
return true;
}
else if (true == this.m_Unrestricted)
{
return false;
}
if (this.m_Name != null)
{
if (operand.m_Name == null) return false;
if (this.m_Name == "") return true;
}
if (this.m_Name.Equals (operand.m_Name))
{
return true;
}
else
{
// Check for wild card character '*'.
int i = operand.m_Name.LastIndexOf ("*");
if (i > 0)
{
string prefix = operand.m_Name.Substring (0, i);
if (this.m_Name.StartsWith (prefix))
{
return true;
}
}
}
return false;
}
catch (InvalidCastException)
{
throw new ArgumentException (String.Format ("Argument_WrongType", this.GetType ().FullName));
}
}
Public Overrides Function IsSubsetOf(ByVal target As IPermission) As Boolean
#If (Debug) Then
Console.WriteLine("************* Entering IsSubsetOf *********************")
#End If
If target Is Nothing Then
Console.WriteLine("IsSubsetOf: target == null")
Return False
End If
#If (Debug) Then
Console.WriteLine(("This is = " + CType(Me, NameIdPermission).Name))
Console.WriteLine(("Target is " + CType(target, NameIdPermission).m_name))
#End If
Try
Dim operand As NameIdPermission = CType(target, NameIdPermission)
' The following check for unrestricted permission is only included as an example for
' permissions that allow the unrestricted state. It is of no value for this permission.
If True = operand.m_Unrestricted Then
Return True
ElseIf True = Me.m_Unrestricted Then
Return False
End If
If Not (Me.m_name Is Nothing) Then
If operand.m_name Is Nothing Then
Return False
End If
If Me.m_name = "" Then
Return True
End If
End If
If Me.m_name.Equals(operand.m_name) Then
Return True
Else
' Check for wild card character '*'.
Dim i As Integer = operand.m_name.LastIndexOf("*")
If i > 0 Then
Dim prefix As String = operand.m_name.Substring(0, i)
If Me.m_name.StartsWith(prefix) Then
Return True
End If
End If
End If
Return False
Catch
Throw New ArgumentException(String.Format("Argument_WrongType", Me.GetType().FullName))
End Try
End Function
Remarks
The current permission is a subset of the specified permission if the current permission specifies a set of operations that is wholly contained by the specified permission. For example, a permission that represents access to C:\example.txt is a subset of a permission that represents access to C:\. If this method returns true, the current permission represents no more access to the protected resource than does the specified permission.
The following statements are required to be true for all overrides of the IsSubsetOf method. X, Y, and Z represent custom code access permission objects that are not null references, U represents an unrestricted code access permission, and N represents an empty permission with a PermissionState of None.
X.IsSubsetOf(X) returns
true.X.IsSubsetOf(Y) returns the same value as Y.IsSubsetOf(X) if and only if X and Y represent the same set of permissions.
If X.IsSubsetOf(Y) and Y.IsSubsetOf(Z) both return
true, X.IsSubsetOf(Z) returnstrue.X.IsSubsetOf(U) returns
true.X.IsSubsetOf(N) returns
false.N.IsSubsetOf(X) returns
true.
If X and Y represent custom code access permission objects that are null references, X.IsSubsetOf(Y) returns true. If Z is also null, the compound set operation X.Union(Y).IsSubsetOf(Z) also returns true because the union of two null permissions is a null permission.
Notes to Implementers
You must override this method in a derived class.
