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FirstMatchCodeGroup Class

Note: This API is now obsolete.

Allows security policy to be defined by the union of the policy statement of a code group and that of the first child code group that matches. This class cannot be inherited.

System.Object
  System.Security.Policy.CodeGroup
    System.Security.Policy.FirstMatchCodeGroup

Namespace:  System.Security.Policy
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
<ObsoleteAttribute("This type is obsolete and will be removed in a future release of the .NET Framework. See http://go.microsoft.com/fwlink/?LinkID=155570 for more information.")> _
Public NotInheritable Class FirstMatchCodeGroup _
	Inherits CodeGroup

The FirstMatchCodeGroup type exposes the following members.

  NameDescription
Public methodFirstMatchCodeGroupInitializes a new instance of the FirstMatchCodeGroup class.
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  NameDescription
Public propertyAttributeStringGets a string representation of the attributes of the policy statement for the code group. (Inherited from CodeGroup.)
Public propertyChildrenGets or sets an ordered list of the child code groups of a code group. (Inherited from CodeGroup.)
Public propertyDescriptionGets or sets the description of the code group. (Inherited from CodeGroup.)
Public propertyMembershipConditionGets or sets the code group's membership condition. (Inherited from CodeGroup.)
Public propertyMergeLogicGets the merge logic. (Overrides CodeGroup.MergeLogic.)
Public propertyNameGets or sets the name of the code group. (Inherited from CodeGroup.)
Public propertyPermissionSetNameGets the name of the named permission set for the code group. (Inherited from CodeGroup.)
Public propertyPolicyStatementGets or sets the policy statement associated with the code group. (Inherited from CodeGroup.)
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  NameDescription
Public methodAddChildAdds a child code group to the current code group. (Inherited from CodeGroup.)
Public methodCopyMakes a deep copy of the code group. (Overrides CodeGroup.Copy.)
Public methodEquals(Object)Determines whether the specified code group is equivalent to the current code group. (Inherited from CodeGroup.)
Public methodEquals(CodeGroup, Boolean)Determines whether the specified code group is equivalent to the current code group, checking the child code groups as well, if specified. (Inherited from CodeGroup.)
Public methodFromXml(SecurityElement)Reconstructs a security object with a given state from an XML encoding. (Inherited from CodeGroup.)
Public methodFromXml(SecurityElement, PolicyLevel)Reconstructs a security object with a given state and policy level from an XML encoding. (Inherited from CodeGroup.)
Public methodGetHashCodeGets the hash code of the current code group. (Inherited from CodeGroup.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodRemoveChildRemoves the specified child code group. (Inherited from CodeGroup.)
Public methodResolveResolves policy for the code group and its descendants for a set of evidence. (Overrides CodeGroup.Resolve(Evidence).)
Public methodResolveMatchingCodeGroupsResolves matching code groups. (Overrides CodeGroup.ResolveMatchingCodeGroups(Evidence).)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodToXmlCreates an XML encoding of the security object and its current state. (Inherited from CodeGroup.)
Public methodToXml(PolicyLevel)Creates an XML encoding of the security object, its current state, and the policy level within which the code exists. (Inherited from CodeGroup.)
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Code groups are the building blocks of code access security policy. Each policy level consists of a root code group that can have child code groups. Each child code group can have their own child code groups; this behavior extends to any number of levels, forming a tree. Each code group has a membership condition that determines if a given assembly belongs to it based on the evidence for that assembly. Only code groups whose membership conditions match a given assembly and their child code groups apply policy.

Like any code group, FirstMatchCodeGroup only applies when its membership condition matches evidence for an assembly. If there is a match, it tests the membership condition of each child in order, stopping when the first match occurs. The result of FirstMatchCodeGroup is the union of the policy statement of the root code group and the policy statement of the first child group of that code group that matches.

FirstMatchCodeGroup is intended for programmatic use by application domain hosts to set domain policy.

The following example shows the use of members of the FirstMatchCodeGroup class.

Imports System.Security
Imports System.Security.Policy
Imports System.Security.Permissions
Imports System.Reflection
Imports System.Windows.Forms

Public Class Form1
    Inherits System.Windows.Forms.Form

    ' Event handler for Run button. 
    Private Sub Button1_Click( _
        ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button1.Click

        tbxOutput.Cursor = Cursors.WaitCursor
        tbxOutput.Text = "" 

        ' Create a new FirstMatchCodeGroup. 
        Dim codeGroup As FirstMatchCodeGroup = constructDefaultGroup()

        ' Create a deep copy of the FirstMatchCodeGroup. 
        Dim copyCodeGroup As FirstMatchCodeGroup
        copyCodeGroup = CType(codeGroup.Copy(), FirstMatchCodeGroup)

        ' Compare the original code group with the copy.
        CompareTwoCodeGroups(codeGroup, copyCodeGroup)

        addPolicy(codeGroup)
        addXmlMember(codeGroup)
        updateMembershipCondition(codeGroup)
        addChildCodeGroup(codeGroup)

        Write("Comparing the resolved code group ")
        WriteLine("with the initial code group.")

        Dim resolvedCodeGroup As FirstMatchCodeGroup
        resolvedCodeGroup = ResolveGroupToEvidence(codeGroup)
        If (CompareTwoCodeGroups(codeGroup, resolvedCodeGroup)) Then
            PrintCodeGroup(resolvedCodeGroup)
        Else
            PrintCodeGroup(codeGroup)
        End If 

        ' Reset the cursor and conclude application.
        tbxOutput.AppendText(vbCrLf + "This sample completed " + _
            "successfully; press Exit to continue.")
        tbxOutput.Cursor = Cursors.Default 
    End Sub 
    ' Create a FirstMatchCodeGroup with an exclusive policy and membership 
    ' condition. 
    Private Function constructDefaultGroup() As FirstMatchCodeGroup
        ' Construct a new FirstMatchCodeGroup with Read, Write, Append  
        ' and PathDiscovery access. 
        ' Create read access permission to the root directory on drive C. 
        Dim rootFilePermissions As New FileIOPermission(PermissionState.None)
        rootFilePermissions.AllLocalFiles = FileIOPermissionAccess.Read
        rootFilePermissions.SetPathList(FileIOPermissionAccess.Read, "C:\\")

        ' Add a permission to a named permission set. 
        Dim namedPermissions As New NamedPermissionSet("RootPermissions")
        namedPermissions.AddPermission(rootFilePermissions)

        ' Create a PolicyStatement with exclusive rights to the policy. 
        Dim policy As New PolicyStatement( _
            namedPermissions, _
            PolicyStatementAttribute.Exclusive)

        ' Create a FirstMatchCodeGroup with a membership condition that  
        ' matches all code, and an exclusive policy. 
        Dim codeGroup As New FirstMatchCodeGroup( _
            New AllMembershipCondition, _
            policy)

        ' Set the name of the first match code group.
        codeGroup.Name = "TempCodeGroup" 

        ' Set the description of the first match code group.
        codeGroup.Description = "Temp folder permissions group" 

        Return codeGroup
    End Function 

    ' Add file permission to restrict write access to all files  
    ' on the local machine. 
    Private Sub addPolicy(ByRef codeGroup As FirstMatchCodeGroup)
        ' Set the PolicyStatement property to a policy with read access to the 
        ' root directory on drive C. 
        Dim rootFilePermissions As New FileIOPermission(PermissionState.None)
        rootFilePermissions.AllLocalFiles = FileIOPermissionAccess.Read
        rootFilePermissions.SetPathList(FileIOPermissionAccess.Read, "C:\\")

        Dim namedPermissions As New NamedPermissionSet("RootPermissions")
        namedPermissions.AddPermission(rootFilePermissions)

        ' Create a PolicyStatement with exclusive rights to the policy. 
        Dim policy As New PolicyStatement( _
            namedPermissions, _
            PolicyStatementAttribute.Exclusive)

        codeGroup.PolicyStatement = policy
    End Sub 

    ' Set the membership condition of the code group. 
    Private Sub updateMembershipCondition( _
        ByRef codeGroup As FirstMatchCodeGroup)

        ' Set the membership condition of the specified FirstMatchCodeGroup  
        ' to the Intranet zone. 
        Dim zoneCondition As _
            New ZoneMembershipCondition(SecurityZone.Intranet)
        codeGroup.MembershipCondition = zoneCondition
    End Sub 

    ' Create a child code group with read-access file permissions and add it 
    ' to the specified code group. 
    Private Sub addChildCodeGroup(ByRef codegroup As FirstMatchCodeGroup)
        ' Create a first match code group with read access. 
        Dim rootFilePermissions As New FileIOPermission(PermissionState.None)
        rootFilePermissions.AllLocalFiles = FileIOPermissionAccess.Read
        rootFilePermissions.SetPathList(FileIOPermissionAccess.Read, "C:\\")

        Dim permissions As New PermissionSet(PermissionState.Unrestricted)
        permissions.AddPermission(rootFilePermissions)

        Dim tempFolderCodeGroup = New FirstMatchCodeGroup( _
            New AllMembershipCondition, _
            New PolicyStatement(permissions))

        ' Set the name of the child code group and add it to the specified 
        ' code group.
        tempFolderCodeGroup.Name = "Read-only code group"
        codegroup.AddChild(tempFolderCodeGroup)
    End Sub 

    ' Compare the two FirstMatchCodeGroups. 
    Private Function CompareTwoCodeGroups( _
        ByVal firstCodeGroup As FirstMatchCodeGroup, _
        ByVal secondCodeGroup As FirstMatchCodeGroup) As Boolean 

        ' Compare the two specified FirstMatchCodeGroups for equality. 
        If (firstCodeGroup.Equals(secondCodeGroup)) Then

            WriteLine("The two code groups are equal.")
            Return True 
        Else
            WriteLine("The two code groups are not equal.")
            Return False 
        End If 
    End Function 

    ' Retrieve the resolved policy based on executing evidence found  
    ' in the specified code group. 
    Private Function ResolveEvidence(ByVal codeGroup As CodeGroup) As String 
        Dim policyString As String = "None" 

        ' Resolve the policy based on the executing assembly's evidence. 
        Dim executingAssembly As [Assembly] = Me.GetType().Assembly
        Dim executingEvidence As Evidence
        executingEvidence = executingAssembly.Evidence

        Dim policy As PolicyStatement = codeGroup.Resolve(executingEvidence)

        If (Not policy Is Nothing) Then
            policyString = policy.ToString()
        End If 

        Return policyString
    End Function 

    ' Retrieve the resolved code group based on the evidence from the  
    ' specified code group. 
    Private Function ResolveGroupToEvidence( _
        ByVal codegroup As FirstMatchCodeGroup) _
        As FirstMatchCodeGroup

        ' Resolve matching code groups to the executing assembly. 
        Dim executingAssembly As [Assembly] = Me.GetType().Assembly
        Dim evidence As Evidence = executingAssembly.Evidence
        Dim resolvedCodeGroup As CodeGroup
        resolvedCodeGroup = codegroup.ResolveMatchingCodeGroups(Evidence)

        Return CType(resolvedCodeGroup, FirstMatchCodeGroup)
    End Function 

    ' If a domain attribute is not found in the specified FirstMatchCodeGroup, 
    ' add a child XML element identifying a custom membership condition. 
    Private Sub addXmlMember(ByRef codeGroup As FirstMatchCodeGroup)
        Dim xmlElement As SecurityElement = codeGroup.ToXml()

        Dim rootElement As New SecurityElement("CodeGroup")

        If (xmlElement.Attribute("domain") Is Nothing) Then 
            Dim newElement As New SecurityElement("CustomMembershipCondition")
            newElement.AddAttribute("class", "CustomMembershipCondition")
            newElement.AddAttribute("version", "1")
            newElement.AddAttribute("domain", "contoso.com")

            rootElement.AddChild(newElement)

            codeGroup.FromXml(rootElement)
        End If

        WriteLine("Added a custom membership condition:")
        WriteLine(rootElement.ToString())
    End Sub 

    ' Print the properties of the specified code group to the console. 
    Private Sub PrintCodeGroup(ByVal codeGroup As CodeGroup)
        ' Compare the type of the specified object with the 
        ' FirstMatchCodeGroup type. 
        If (Not codeGroup.GetType() Is GetType(FirstMatchCodeGroup)) Then 
            Throw New ArgumentException( _
                "Expected the FirstMatchCodeGroup type.")

        End If 

        Dim codeGroupName As String = codeGroup.Name
        Dim membershipCondition As String
        membershipCondition = codeGroup.MembershipCondition.ToString()

        Dim permissionSetName As String = codeGroup.PermissionSetName

        Dim hashCode As Integer = codeGroup.GetHashCode()

        Dim mergeLogic As String = "" 
        If (codeGroup.MergeLogic.Equals("First Match")) Then
            mergeLogic = "with first-match merge logic" 
        End If 

        ' Retrieve the class path for the FirstMatchCodeGroup. 
        Dim firstMatchGroupClass As String = codeGroup.ToString()

        Dim attributeString As String = "" 
        ' Retrieve the string representation of the FirstMatchCodeGroup's 
        ' attributes. 
        If (Not codeGroup.AttributeString Is Nothing) Then
            attributeString = codeGroup.AttributeString
        End If 

        ' Write a summary to the console window.
        WriteLine(vbCrLf + "* " + firstMatchGroupClass + " summary *")
        Write("A FirstMatchCodeGroup named ")
        Write(codeGroupName + mergeLogic)
        Write(" has been created with hash code ")
        WriteLine(hashCode.ToString() + ". ")

        Write("This code group contains a " + membershipCondition)
        Write(" membership condition with the ")
        Write(permissionSetName + " permission set. ")

        Write("The code group contains the following policy: ")
        Write(ResolveEvidence(codeGroup) + ". ")
        Write("It also contains the following attributes: ")
        WriteLine(attributeString)

        Dim childCount As Integer = codeGroup.Children.Count
        If (childCount > 0) Then
            Write("There are " + childCount.ToString())
            WriteLine(" child elements in the code group.")

            ' Iterate through the child code groups to display their names 
            ' and then remove them from the specified code group. 
            For i As Int16 = 0 To childCount - 1 Step 1
                ' Retrieve each child explicitly casted as a  
                ' FirstMatchCodeGroup type. 
                Dim childCodeGroup As FirstMatchCodeGroup
                childCodeGroup = _
                    CType(codeGroup.Children(i), FirstMatchCodeGroup)

                Write("Removing the " + childCodeGroup.Name + ".")
                ' Remove the child code group.
                codeGroup.RemoveChild(childCodeGroup)
            Next

            WriteLine("")
        Else
            WriteLine("No child code groups were found in this code group.")
        End If 
    End Sub 

    Private Sub WriteLine(ByVal message As String)
        tbxOutput.AppendText(message + vbCrLf)

    End Sub 

    Private Sub Write(ByVal message As String)
        tbxOutput.AppendText(message)

    End Sub 

    ' Event handler for Exit button. 
    Private Sub Button2_Click( _
        ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button2.Click

        Application.Exit()
    End Sub
#Region " Windows Form Designer generated code " 

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call 

    End Sub 

    'Form overrides dispose to clean up the component list. 
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then 
            If Not (components Is Nothing) Then
                components.Dispose()
            End If 
        End If 
        MyBase.Dispose(disposing)
    End Sub 

    'Required by the Windows Form Designer 
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer 
    'It can be modified using the Windows Form Designer.   
    'Do not modify it using the code editor. 
    Friend WithEvents Panel2 As System.Windows.Forms.Panel
    Friend WithEvents Panel1 As System.Windows.Forms.Panel
    Friend WithEvents Button1 As System.Windows.Forms.Button
    Friend WithEvents Button2 As System.Windows.Forms.Button
    Friend WithEvents tbxOutput As System.Windows.Forms.RichTextBox
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.Panel2 = New System.Windows.Forms.Panel
        Me.Button1 = New System.Windows.Forms.Button
        Me.Button2 = New System.Windows.Forms.Button
        Me.Panel1 = New System.Windows.Forms.Panel
        Me.tbxOutput = New System.Windows.Forms.RichTextBox
        Me.Panel2.SuspendLayout()
        Me.Panel1.SuspendLayout()
        Me.SuspendLayout()
        
        'Panel2 
        
        Me.Panel2.Controls.Add(Me.Button1)
        Me.Panel2.Controls.Add(Me.Button2)
        Me.Panel2.Dock = System.Windows.Forms.DockStyle.Bottom
        Me.Panel2.DockPadding.All = 20
        Me.Panel2.Location = New System.Drawing.Point(0, 320)
        Me.Panel2.Name = "Panel2" 
        Me.Panel2.Size = New System.Drawing.Size(616, 64)
        Me.Panel2.TabIndex = 1
        
        'Button1 
        
        Me.Button1.Dock = System.Windows.Forms.DockStyle.Right
        Me.Button1.Font = New System.Drawing.Font( _
            "Microsoft Sans Serif", _
            9.0!, _
            System.Drawing.FontStyle.Regular, _
            System.Drawing.GraphicsUnit.Point, _
            CType(0, Byte))
        Me.Button1.Location = New System.Drawing.Point(446, 20)
        Me.Button1.Name = "Button1" 
        Me.Button1.Size = New System.Drawing.Size(75, 24)
        Me.Button1.TabIndex = 2
        Me.Button1.Text = "&Run" 
        
        'Button2 
        
        Me.Button2.Dock = System.Windows.Forms.DockStyle.Right
        Me.Button2.Font = New System.Drawing.Font( _
            "Microsoft Sans Serif", _
            9.0!, _
            System.Drawing.FontStyle.Regular, _
            System.Drawing.GraphicsUnit.Point, _
            CType(0, Byte))
        Me.Button2.Location = New System.Drawing.Point(521, 20)
        Me.Button2.Name = "Button2" 
        Me.Button2.Size = New System.Drawing.Size(75, 24)
        Me.Button2.TabIndex = 3
        Me.Button2.Text = "E&xit" 
        
        'Panel1 
        
        Me.Panel1.Controls.Add(Me.tbxOutput)
        Me.Panel1.Dock = System.Windows.Forms.DockStyle.Fill
        Me.Panel1.DockPadding.All = 20
        Me.Panel1.Location = New System.Drawing.Point(0, 0)
        Me.Panel1.Name = "Panel1" 
        Me.Panel1.Size = New System.Drawing.Size(616, 320)
        Me.Panel1.TabIndex = 2
        
        'tbxOutput 
        
        Me.tbxOutput.AccessibleDescription = _
            "Displays output from application." 
        Me.tbxOutput.AccessibleName = "Output textbox." 
        Me.tbxOutput.Dock = System.Windows.Forms.DockStyle.Fill
        Me.tbxOutput.Location = New System.Drawing.Point(20, 20)
        Me.tbxOutput.Name = "tbxOutput" 
        Me.tbxOutput.Size = New System.Drawing.Size(576, 280)
        Me.tbxOutput.TabIndex = 1
        Me.tbxOutput.Text = "Click the Run button to run the application." 
        
        'Form1 
        
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 15)
        Me.ClientSize = New System.Drawing.Size(616, 384)
        Me.Controls.Add(Me.Panel1)
        Me.Controls.Add(Me.Panel2)
        Me.Name = "Form1" 
        Me.Text = "FirstMatchCodeGroup" 
        Me.Panel2.ResumeLayout(False)
        Me.Panel1.ResumeLayout(False)
        Me.ResumeLayout(False)

    End Sub

#End Region
End Class 

' This sample produces the following output: 

' The two code groups are equal. 
' Added a custom membership condition: 
' <CodeGroup> 
'    <CustomMembershipCondition class="CustomMembershipCondition" 
'                               version="1" 
'                               domain="contoso.com"/> 
' </CodeGroup> 
'  
' Comparing the resolved code group with the initial code group. 
' The two code groups are not equal. 
'  
' * System.Security.Policy.FirstMatchCodeGroup summary * 
' A FirstMatchCodeGroup named with first-match merge logic has been created 
' with hash code 113155593. This code group contains a Zone - Intranet  
' membership condition with the  permission set. The code group contains the 
' following policy: None. It also contains the following attributes:  
' There are 1 child elements in the code group. 
' Removing the Read-only code group. 
'  
' This sample completed successfully; press Exit to continue.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1
Obsolete (compiler warning) in 4.6
Obsolete (compiler warning) in 4.6
Obsolete (compiler warning) in 4.5
Obsolete (compiler warning) in 4.5.1
Obsolete (compiler warning) in 4.5.2
Obsolete (compiler warning) in 4

.NET Framework Client Profile

Supported in: 3.5 SP1
Obsolete (compiler warning) in 4

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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