EventWaitHandle.GetAccessControl Methode
Definition
Wichtig
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Ruft ein EventWaitHandleSecurity-Objekt ab, das die Zugriffssteuerungssicherheit für das benannte Systemereignis darstellt, das durch das aktuelle EventWaitHandle-Objekt dargestellt wird.
public:
System::Security::AccessControl::EventWaitHandleSecurity ^ GetAccessControl();public System.Security.AccessControl.EventWaitHandleSecurity GetAccessControl ();member this.GetAccessControl : unit -> System.Security.AccessControl.EventWaitHandleSecurityPublic Function GetAccessControl () As EventWaitHandleSecurityGibt zurück
Ein EventWaitHandleSecurity-Objekt, das die Zugriffssteuerungssicherheit für das benannte Systemereignis darstellt.
Ausnahmen
Das aktuelle EventWaitHandle-Objekt stellt ein benanntes Systemereignis dar, und der Benutzer verfügt nicht über ReadPermissions.
- oder - Das aktuelle EventWaitHandle-Objekt stellt eine benanntes Systemereignis dar und wurde nicht mit ReadPermissions geöffnet.
Die Close()-Methode wurde zuvor für dieses EventWaitHandle aufgerufen.
Beispiele
Im folgenden Codebeispiel wird das Prozessverhalten eines benannten Systemereigniss mit Zugriffssteuerungssicherheit veranschaulicht. Im Beispiel wird die Methodenüberladung verwendet, um die Existenz eines benannten OpenExisting(String) Ereignisses zu testen.
Wenn das Ereignis nicht vorhanden ist, wird es mit der anfänglichen Besitz- und Zugriffssteuerungssicherheit erstellt, die den aktuellen Benutzer das Recht auf Verwendung des Ereignisses verweigert, aber das Recht gewährt, Berechtigungen für das Ereignis zu lesen und zu ändern.
Wenn Sie das kompilierte Beispiel aus zwei Befehlsfenstern ausführen, löst die zweite Kopie eine Zugriffsverletzungs ausnahme auf dem Aufruf aus OpenExisting(String). Die Ausnahme wird abgefangen, und das Beispiel verwendet die OpenExisting(String, EventWaitHandleRights) Methodenüberladung, um auf das Ereignis zu warten, mit den Rechten, die zum Lesen und Ändern der Berechtigungen erforderlich sind.
Nachdem die Berechtigungen gelesen wurden, verwenden Sie die GetAccessControl Methode und geändert, wird das Ereignis mit den Rechten geöffnet, die erforderlich sind, um darauf zu warten und es zu signalisieren. Wenn Sie das kompilierte Beispiel aus einem dritten Befehlsfenster ausführen, wird das Beispiel mit den neuen Berechtigungen ausgeführt.
using namespace System;
using namespace System::Threading;
using namespace System::Security::AccessControl;
using namespace System::Security::Permissions;
public ref class Example
{
public:
[SecurityPermissionAttribute(SecurityAction::Demand,Flags=SecurityPermissionFlag::UnmanagedCode)]
static void Main()
{
String^ ewhName = L"EventWaitHandleExample5";
EventWaitHandle^ ewh = nullptr;
bool doesNotExist = false;
bool unauthorized = false;
// The value of this variable is set by the event
// constructor. It is true if the named system event was
// created, and false if the named event already existed.
//
bool wasCreated;
// Attempt to open the named event.
try
{
// Open the event with (EventWaitHandleRights.Synchronize
// | EventWaitHandleRights.Modify), to wait on and
// signal the named event.
//
ewh = EventWaitHandle::OpenExisting( ewhName );
}
catch ( WaitHandleCannotBeOpenedException^ )
{
Console::WriteLine( L"Named event does not exist." );
doesNotExist = true;
}
catch ( UnauthorizedAccessException^ ex )
{
Console::WriteLine( L"Unauthorized access: {0}", ex->Message );
unauthorized = true;
}
// There are three cases: (1) The event does not exist.
// (2) The event exists, but the current user doesn't
// have access. (3) The event exists and the user has
// access.
//
if ( doesNotExist )
{
// The event does not exist, so create it.
// Create an access control list (ACL) that denies the
// current user the right to wait on or signal the
// event, but allows the right to read and change
// security information for the event.
//
String^ user = String::Concat( Environment::UserDomainName, L"\\",
Environment::UserName );
EventWaitHandleSecurity^ ewhSec = gcnew EventWaitHandleSecurity;
//following constructor fails
EventWaitHandleAccessRule^ rule = gcnew EventWaitHandleAccessRule(
user,
static_cast<EventWaitHandleRights>(
EventWaitHandleRights::Synchronize |
EventWaitHandleRights::Modify),
AccessControlType::Deny );
ewhSec->AddAccessRule( rule );
rule = gcnew EventWaitHandleAccessRule( user,
static_cast<EventWaitHandleRights>(
EventWaitHandleRights::ReadPermissions |
EventWaitHandleRights::ChangePermissions),
AccessControlType::Allow );
ewhSec->AddAccessRule( rule );
// Create an EventWaitHandle object that represents
// the system event named by the constant 'ewhName',
// initially signaled, with automatic reset, and with
// the specified security access. The Boolean value that
// indicates creation of the underlying system object
// is placed in wasCreated.
//
ewh = gcnew EventWaitHandle( true,
EventResetMode::AutoReset,
ewhName,
wasCreated,
ewhSec );
// If the named system event was created, it can be
// used by the current instance of this program, even
// though the current user is denied access. The current
// program owns the event. Otherwise, exit the program.
//
if ( wasCreated )
{
Console::WriteLine( L"Created the named event." );
}
else
{
Console::WriteLine( L"Unable to create the event." );
return;
}
}
else if ( unauthorized )
{
// Open the event to read and change the access control
// security. The access control security defined above
// allows the current user to do this.
//
try
{
ewh = EventWaitHandle::OpenExisting( ewhName,
static_cast<EventWaitHandleRights>(
EventWaitHandleRights::ReadPermissions |
EventWaitHandleRights::ChangePermissions) );
// Get the current ACL. This requires
// EventWaitHandleRights.ReadPermissions.
EventWaitHandleSecurity^ ewhSec = ewh->GetAccessControl();
String^ user = String::Concat( Environment::UserDomainName, L"\\",
Environment::UserName );
// First, the rule that denied the current user
// the right to enter and release the event must
// be removed.
EventWaitHandleAccessRule^ rule = gcnew EventWaitHandleAccessRule(
user,
static_cast<EventWaitHandleRights>(
EventWaitHandleRights::Synchronize |
EventWaitHandleRights::Modify),
AccessControlType::Deny );
ewhSec->RemoveAccessRule( rule );
// Now grant the user the correct rights.
//
rule = gcnew EventWaitHandleAccessRule( user,
static_cast<EventWaitHandleRights>(
EventWaitHandleRights::Synchronize |
EventWaitHandleRights::Modify),
AccessControlType::Allow );
ewhSec->AddAccessRule( rule );
// Update the ACL. This requires
// EventWaitHandleRights.ChangePermissions.
ewh->SetAccessControl( ewhSec );
Console::WriteLine( L"Updated event security." );
// Open the event with (EventWaitHandleRights.Synchronize
// | EventWaitHandleRights.Modify), the rights required
// to wait on and signal the event.
//
ewh = EventWaitHandle::OpenExisting( ewhName );
}
catch ( UnauthorizedAccessException^ ex )
{
Console::WriteLine( L"Unable to change permissions: {0}",
ex->Message );
return;
}
}
// Wait on the event, and hold it until the program
// exits.
//
try
{
Console::WriteLine( L"Wait on the event." );
ewh->WaitOne();
Console::WriteLine( L"Event was signaled." );
Console::WriteLine( L"Press the Enter key to signal the event and exit." );
Console::ReadLine();
}
catch ( UnauthorizedAccessException^ ex )
{
Console::WriteLine( L"Unauthorized access: {0}", ex->Message );
}
finally
{
ewh->Set();
}
}
};
int main()
{
Example::Main();
}
using System;
using System.Threading;
using System.Security.AccessControl;
internal class Example
{
internal static void Main()
{
const string ewhName = "EventWaitHandleExample5";
EventWaitHandle ewh = null;
bool doesNotExist = false;
bool unauthorized = false;
// The value of this variable is set by the event
// constructor. It is true if the named system event was
// created, and false if the named event already existed.
//
bool wasCreated;
// Attempt to open the named event.
try
{
// Open the event with (EventWaitHandleRights.Synchronize
// | EventWaitHandleRights.Modify), to wait on and
// signal the named event.
//
ewh = EventWaitHandle.OpenExisting(ewhName);
}
catch (WaitHandleCannotBeOpenedException)
{
Console.WriteLine("Named event does not exist.");
doesNotExist = true;
}
catch (UnauthorizedAccessException ex)
{
Console.WriteLine("Unauthorized access: {0}", ex.Message);
unauthorized = true;
}
// There are three cases: (1) The event does not exist.
// (2) The event exists, but the current user doesn't
// have access. (3) The event exists and the user has
// access.
//
if (doesNotExist)
{
// The event does not exist, so create it.
// Create an access control list (ACL) that denies the
// current user the right to wait on or signal the
// event, but allows the right to read and change
// security information for the event.
//
string user = Environment.UserDomainName + "\\"
+ Environment.UserName;
EventWaitHandleSecurity ewhSec =
new EventWaitHandleSecurity();
EventWaitHandleAccessRule rule =
new EventWaitHandleAccessRule(user,
EventWaitHandleRights.Synchronize |
EventWaitHandleRights.Modify,
AccessControlType.Deny);
ewhSec.AddAccessRule(rule);
rule = new EventWaitHandleAccessRule(user,
EventWaitHandleRights.ReadPermissions |
EventWaitHandleRights.ChangePermissions,
AccessControlType.Allow);
ewhSec.AddAccessRule(rule);
// Create an EventWaitHandle object that represents
// the system event named by the constant 'ewhName',
// initially signaled, with automatic reset, and with
// the specified security access. The Boolean value that
// indicates creation of the underlying system object
// is placed in wasCreated.
//
ewh = new EventWaitHandle(true,
EventResetMode.AutoReset,
ewhName,
out wasCreated,
ewhSec);
// If the named system event was created, it can be
// used by the current instance of this program, even
// though the current user is denied access. The current
// program owns the event. Otherwise, exit the program.
//
if (wasCreated)
{
Console.WriteLine("Created the named event.");
}
else
{
Console.WriteLine("Unable to create the event.");
return;
}
}
else if (unauthorized)
{
// Open the event to read and change the access control
// security. The access control security defined above
// allows the current user to do this.
//
try
{
ewh = EventWaitHandle.OpenExisting(ewhName,
EventWaitHandleRights.ReadPermissions |
EventWaitHandleRights.ChangePermissions);
// Get the current ACL. This requires
// EventWaitHandleRights.ReadPermissions.
EventWaitHandleSecurity ewhSec = ewh.GetAccessControl();
string user = Environment.UserDomainName + "\\"
+ Environment.UserName;
// First, the rule that denied the current user
// the right to enter and release the event must
// be removed.
EventWaitHandleAccessRule rule =
new EventWaitHandleAccessRule(user,
EventWaitHandleRights.Synchronize |
EventWaitHandleRights.Modify,
AccessControlType.Deny);
ewhSec.RemoveAccessRule(rule);
// Now grant the user the correct rights.
//
rule = new EventWaitHandleAccessRule(user,
EventWaitHandleRights.Synchronize |
EventWaitHandleRights.Modify,
AccessControlType.Allow);
ewhSec.AddAccessRule(rule);
// Update the ACL. This requires
// EventWaitHandleRights.ChangePermissions.
ewh.SetAccessControl(ewhSec);
Console.WriteLine("Updated event security.");
// Open the event with (EventWaitHandleRights.Synchronize
// | EventWaitHandleRights.Modify), the rights required
// to wait on and signal the event.
//
ewh = EventWaitHandle.OpenExisting(ewhName);
}
catch (UnauthorizedAccessException ex)
{
Console.WriteLine("Unable to change permissions: {0}",
ex.Message);
return;
}
}
// Wait on the event, and hold it until the program
// exits.
//
try
{
Console.WriteLine("Wait on the event.");
ewh.WaitOne();
Console.WriteLine("Event was signaled.");
Console.WriteLine("Press the Enter key to signal the event and exit.");
Console.ReadLine();
}
catch (UnauthorizedAccessException ex)
{
Console.WriteLine("Unauthorized access: {0}", ex.Message);
}
finally
{
ewh.Set();
}
}
}
Imports System.Threading
Imports System.Security.AccessControl
Friend Class Example
<MTAThread> _
Friend Shared Sub Main()
Const ewhName As String = "EventWaitHandleExample5"
Dim ewh As EventWaitHandle = Nothing
Dim doesNotExist as Boolean = False
Dim unauthorized As Boolean = False
' The value of this variable is set by the event
' constructor. It is True if the named system event was
' created, and False if the named event already existed.
'
Dim wasCreated As Boolean
' Attempt to open the named event.
Try
' Open the event with (EventWaitHandleRights.Synchronize
' Or EventWaitHandleRights.Modify), to wait on and
' signal the named event.
'
ewh = EventWaitHandle.OpenExisting(ewhName)
Catch ex As WaitHandleCannotBeOpenedException
Console.WriteLine("Named event does not exist.")
doesNotExist = True
Catch ex As UnauthorizedAccessException
Console.WriteLine("Unauthorized access: {0}", ex.Message)
unauthorized = True
End Try
' There are three cases: (1) The event does not exist.
' (2) The event exists, but the current user doesn't
' have access. (3) The event exists and the user has
' access.
'
If doesNotExist Then
' The event does not exist, so create it.
' Create an access control list (ACL) that denies the
' current user the right to wait on or signal the
' event, but allows the right to read and change
' security information for the event.
'
Dim user As String = Environment.UserDomainName _
& "\" & Environment.UserName
Dim ewhSec As New EventWaitHandleSecurity()
Dim rule As New EventWaitHandleAccessRule(user, _
EventWaitHandleRights.Synchronize Or _
EventWaitHandleRights.Modify, _
AccessControlType.Deny)
ewhSec.AddAccessRule(rule)
rule = New EventWaitHandleAccessRule(user, _
EventWaitHandleRights.ReadPermissions Or _
EventWaitHandleRights.ChangePermissions, _
AccessControlType.Allow)
ewhSec.AddAccessRule(rule)
' Create an EventWaitHandle object that represents
' the system event named by the constant 'ewhName',
' initially signaled, with automatic reset, and with
' the specified security access. The Boolean value that
' indicates creation of the underlying system object
' is placed in wasCreated.
'
ewh = New EventWaitHandle(True, _
EventResetMode.AutoReset, ewhName, _
wasCreated, ewhSec)
' If the named system event was created, it can be
' used by the current instance of this program, even
' though the current user is denied access. The current
' program owns the event. Otherwise, exit the program.
'
If wasCreated Then
Console.WriteLine("Created the named event.")
Else
Console.WriteLine("Unable to create the event.")
Return
End If
ElseIf unauthorized Then
' Open the event to read and change the access control
' security. The access control security defined above
' allows the current user to do this.
'
Try
ewh = EventWaitHandle.OpenExisting(ewhName, _
EventWaitHandleRights.ReadPermissions Or _
EventWaitHandleRights.ChangePermissions)
' Get the current ACL. This requires
' EventWaitHandleRights.ReadPermissions.
Dim ewhSec As EventWaitHandleSecurity = _
ewh.GetAccessControl()
Dim user As String = Environment.UserDomainName _
& "\" & Environment.UserName
' First, the rule that denied the current user
' the right to enter and release the event must
' be removed.
Dim rule As New EventWaitHandleAccessRule(user, _
EventWaitHandleRights.Synchronize Or _
EventWaitHandleRights.Modify, _
AccessControlType.Deny)
ewhSec.RemoveAccessRule(rule)
' Now grant the user the correct rights.
'
rule = New EventWaitHandleAccessRule(user, _
EventWaitHandleRights.Synchronize Or _
EventWaitHandleRights.Modify, _
AccessControlType.Allow)
ewhSec.AddAccessRule(rule)
' Update the ACL. This requires
' EventWaitHandleRights.ChangePermissions.
ewh.SetAccessControl(ewhSec)
Console.WriteLine("Updated event security.")
' Open the event with (EventWaitHandleRights.Synchronize
' Or EventWaitHandleRights.Modify), the rights required
' to wait on and signal the event.
'
ewh = EventWaitHandle.OpenExisting(ewhName)
Catch ex As UnauthorizedAccessException
Console.WriteLine("Unable to change permissions: {0}", _
ex.Message)
Return
End Try
End If
' Wait on the event, and hold it until the program
' exits.
'
Try
Console.WriteLine("Wait on the event.")
ewh.WaitOne()
Console.WriteLine("Event was signaled.")
Console.WriteLine("Press the Enter key to signal the event and exit.")
Console.ReadLine()
Catch ex As UnauthorizedAccessException
Console.WriteLine("Unauthorized access: {0}", _
ex.Message)
Finally
ewh.Set()
End Try
End Sub
End Class
Hinweise
Die GetAccessControl Methode verwendet die folgende Kombination von Flags (kombiniert mit dem BitweiseR-Vorgang), um nach Berechtigungen zu suchen: AccessControlSections.Access, AccessControlSections.Ownerund AccessControlSections.Group.
Der Benutzer muss über Rechte zum Aufrufen dieser Methode verfügen, und das Ereignis muss EventWaitHandleRights.ReadPermissions mit dem EventWaitHandleRights.ReadPermissions Flag geöffnet worden sein.