EventWaitHandle.GetAccessControl Método
Definición
Importante
Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.
Obtiene un objeto EventWaitHandleSecurity que representa la seguridad de control de acceso para el evento del sistema con nombre representado por el objetoEventWaitHandle actual.
public:
System::Security::AccessControl::EventWaitHandleSecurity ^ GetAccessControl();public System.Security.AccessControl.EventWaitHandleSecurity GetAccessControl ();member this.GetAccessControl : unit -> System.Security.AccessControl.EventWaitHandleSecurityPublic Function GetAccessControl () As EventWaitHandleSecurityDevoluciones
Objeto EventWaitHandleSecurity que representa la seguridad de control de acceso para el evento del sistema con nombre.
Excepciones
El objeto EventWaitHandle actual representa un evento del sistema con nombre y el usuario no tiene ReadPermissions.
o bien
El objeto EventWaitHandle actual representa un evento del sistema con nombre que no se ha abierto con ReadPermissions.
No se ha llamado previamente al método Close() en este EventWaitHandle.
Ejemplos
En el ejemplo de código siguiente se muestra el comportamiento entre procesos de un evento del sistema con nombre con seguridad de control de acceso. En el ejemplo se usa la sobrecarga del OpenExisting(String) método para probar la existencia de un evento con nombre.
Si el evento no existe, se crea con la propiedad inicial y la seguridad de control de acceso que deniega al usuario actual el derecho de usar el evento, pero concede el derecho de leer y cambiar permisos en el evento.
Si ejecuta el ejemplo compilado desde dos ventanas de comandos, la segunda copia producirá una excepción de infracción de acceso en la llamada a OpenExisting(String). La excepción se detecta y el ejemplo usa la OpenExisting(String, EventWaitHandleRights) sobrecarga del método para esperar en el evento con los derechos necesarios para leer y cambiar los permisos.
Una vez leídos los permisos, utilizando el GetAccessControl método y cambiado, el evento se abre con los derechos necesarios para esperar en él y indicarlo. Si ejecuta el ejemplo compilado desde una tercera ventana de comandos, el ejemplo se ejecuta con los nuevos permisos.
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
Comentarios
El GetAccessControl método usa la siguiente combinación de marcas (combinada con la operación OR bit a bit) para buscar permisos: AccessControlSections.Access, AccessControlSections.Ownery AccessControlSections.Group.
El usuario debe tener EventWaitHandleRights.ReadPermissions derechos para llamar a este método y el evento debe haberse abierto con la EventWaitHandleRights.ReadPermissions marca .
Se aplica a
Consulte también
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