Export (0) Print
Expand All

EventWaitHandleAccessRule Class

Represents a set of access rights allowed or denied for a user or group. This class cannot be inherited.

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

'Declaration
Public NotInheritable Class EventWaitHandleAccessRule
	Inherits AccessRule
'Usage
Dim instance As EventWaitHandleAccessRule

public final class EventWaitHandleAccessRule extends AccessRule
public final class EventWaitHandleAccessRule extends AccessRule
Not applicable.

The EventWaitHandleAccessRule class is one of a set of classes that the .NET Framework provides for managing Windows access control security on named system events. For an overview of these classes, and their relationship to the underlying Windows access control structures, see EventWaitHandleSecurity.

NoteNote:

Windows access control security is meaningful only for named system events. If an EventWaitHandle object represents a local event, access control is irrelevant.

To get a list of the rules currently applied to a named event, use the EventWaitHandle.GetAccessControl method to get an EventWaitHandleSecurity object, and then use its GetAccessRules method to obtain a collection of EventWaitHandleAccessRule objects.

EventWaitHandleAccessRule objects do not map one-to-one with access control entries in the underlying discretionary access control list (DACL). When you get the set of all access rules for an event, the set contains the minimum number of rules currently required to express all the access control entries.

NoteNote:

The underlying access control entries change as you apply and remove rules. The information in rules is merged if possible, to maintain the smallest number of access control entries. Thus, when you get the current list of rules, it might not look exactly like the list of all the rules you have added.

Use EventWaitHandleAccessRule objects to specify the access rights to allow or deny to a user or group. An EventWaitHandleAccessRule object always represents either allowed access or denied access, never both.

To apply a rule to a named system event, use the EventWaitHandle.GetAccessControl method to get the EventWaitHandleSecurity object. Modify the EventWaitHandleSecurity object by using its methods to add the rule, and then use the EventWaitHandle.SetAccessControl method to reattach the security object.

NoteImportant:

Changes you make to an EventWaitHandleSecurity object do not affect the access levels of the named event until you call the EventWaitHandle.SetAccessControl method to assign the altered security object to the named event.

EventWaitHandleAccessRule objects are immutable. Security for an event is modified using the methods of the EventWaitHandleSecurity class to add or remove rules; as you do this, the underlying access control entries are modified.

NoteNote:

Security on synchronization objects is not supported for Windows 98 or Windows Millennium Edition.

The following code example demonstrates the creation and use of EventWaitHandleAccessRule objects. The example creates an EventWaitHandleSecurity object, adds rules that allow and deny various rights for the current user, and displays the resulting pair of rules. The example then allows new rights for the current user and displays the result, showing that the new rights are merged with the existing Allow rule.

NoteNote:

This example does not attach the security object to a EventWaitHandle object. Examples that attach security objects can be found in EventWaitHandle.GetAccessControl and EventWaitHandle.SetAccessControl.

Imports System
Imports System.Threading
Imports System.Security.AccessControl
Imports System.Security.Principal

Public Class Example

    Public Shared Sub Main()

        ' Create a string representing the current user.
        Dim user As String = Environment.UserDomainName _ 
            & "\" & Environment.UserName

        ' Create a security object that grants no access.
        Dim mSec As New EventWaitHandleSecurity()

        ' Add a rule that grants the current user the 
        ' right to wait on or signal the event.
        Dim rule As New EventWaitHandleAccessRule(user, _
            EventWaitHandleRights.Synchronize _
            Or EventWaitHandleRights.Modify, _
            AccessControlType.Allow)
        mSec.AddAccessRule(rule)

        ' Add a rule that denies the current user the 
        ' right to change permissions on the event.
        rule = New EventWaitHandleAccessRule(user, _
            EventWaitHandleRights.ChangePermissions, _
            AccessControlType.Deny)
        mSec.AddAccessRule(rule)

        ' Display the rules in the security object.
        ShowSecurity(mSec)

        ' Add a rule that allows the current user the 
        ' right to read permissions on the event. This rule
        ' is merged with the existing Allow rule.
        rule = New EventWaitHandleAccessRule(user, _
            EventWaitHandleRights.ReadPermissions, _
            AccessControlType.Allow)
        mSec.AddAccessRule(rule)

        ShowSecurity(mSec)

    End Sub 

    Private Shared Sub ShowSecurity(ByVal security As EventWaitHandleSecurity)
        Console.WriteLine(vbCrLf & "Current access rules:" & vbCrLf)

        For Each ar As EventWaitHandleAccessRule In _
            security.GetAccessRules(True, True, GetType(NTAccount))

            Console.WriteLine("        User: {0}", ar.IdentityReference)
            Console.WriteLine("        Type: {0}", ar.AccessControlType)
            Console.WriteLine("      Rights: {0}", ar.EventWaitHandleRights)
            Console.WriteLine()
        Next

    End Sub
End Class 

'This code example produces output similar to following:
'
'Current access rules:
'
'        User: TestDomain\TestUser
'        Type: Deny
'      Rights: ChangePermissions
'
'        User: TestDomain\TestUser
'        Type: Allow
'      Rights: Modify, Synchronize
'
'
'Current access rules:
'
'        User: TestDomain\TestUser
'        Type: Deny
'      Rights: ChangePermissions
'
'        User: TestDomain\TestUser
'        Type: Allow
'      Rights: Modify, ReadPermissions, Synchronize

System.Object
   System.Security.AccessControl.AuthorizationRule
     System.Security.AccessControl.AccessRule
      System.Security.AccessControl.EventWaitHandleAccessRule

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

Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

Community Additions

ADD
Show:
© 2014 Microsoft