EventWaitHandle.GetAccessControl Metodo
Definizione
Importante
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Ottiene un oggetto EventWaitHandleSecurity che rappresenta la sicurezza del controllo di accesso per l'evento di sistema denominato rappresentato dall'oggetto EventWaitHandle corrente.
public:
System::Security::AccessControl::EventWaitHandleSecurity ^ GetAccessControl();public System.Security.AccessControl.EventWaitHandleSecurity GetAccessControl ();member this.GetAccessControl : unit -> System.Security.AccessControl.EventWaitHandleSecurityPublic Function GetAccessControl () As EventWaitHandleSecurityRestituisce
Oggetto EventWaitHandleSecurity che rappresenta la sicurezza del controllo di accesso per l'evento di sistema denominato.
Eccezioni
L'oggetto EventWaitHandle corrente rappresenta un evento di sistema denominato e l'utente non dispone di ReadPermissions.
-oppure-
L'oggetto EventWaitHandle corrente rappresenta un evento di sistema denominato e non è stato aperto con ReadPermissions.
Il metodo Close() non è stato chiamato precedentemente in questo oggetto EventWaitHandle.
Esempio
Nell'esempio di codice seguente viene illustrato il comportamento tra processi di un evento di sistema denominato con sicurezza del controllo di accesso. Nell'esempio viene utilizzato l'overload del OpenExisting(String) metodo per verificare l'esistenza di un evento denominato.
Se l'evento non esiste, viene creato con la proprietà iniziale e la sicurezza del controllo di accesso che nega all'utente corrente il diritto di usare l'evento, ma concede il diritto di leggere e modificare le autorizzazioni per l'evento.
Se si esegue l'esempio compilato da due finestre di comando, la seconda copia genererà un'eccezione di violazione di accesso nella chiamata a OpenExisting(String). L'eccezione viene intercettata e l'esempio usa l'overload del OpenExisting(String, EventWaitHandleRights) metodo per attendere l'evento con i diritti necessari per leggere e modificare le autorizzazioni.
Dopo aver letto le autorizzazioni, usando il GetAccessControl metodo e modificato, l'evento viene aperto con i diritti necessari per attenderlo e segnalarlo. Se si esegue l'esempio compilato da una terza finestra di comando, l'esempio viene eseguito usando le nuove autorizzazioni.
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
Commenti
Il GetAccessControl metodo usa la seguente combinazione di flag (combinati usando l'operazione OR bit per bit) per cercare le autorizzazioni: AccessControlSections.Access, AccessControlSections.Ownere AccessControlSections.Group.
L'utente deve disporre EventWaitHandleRights.ReadPermissions dei diritti per chiamare questo metodo e l'evento deve essere stato aperto con il EventWaitHandleRights.ReadPermissions flag .
Si applica a
Vedi anche
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