Semaphore.SetAccessControl(SemaphoreSecurity) 方法
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
為具名系統號誌設定存取控制安全性。
public:
void SetAccessControl(System::Security::AccessControl::SemaphoreSecurity ^ semaphoreSecurity);public void SetAccessControl (System.Security.AccessControl.SemaphoreSecurity semaphoreSecurity);member this.SetAccessControl : System.Security.AccessControl.SemaphoreSecurity -> unitPublic Sub SetAccessControl (semaphoreSecurity As SemaphoreSecurity)參數
- semaphoreSecurity
- SemaphoreSecurity
SemaphoreSecurity 物件，表示要套用到具名系統旗號的存取控制安全性。
例外狀況
semaphoreSecurity 為 null。
目前的 Semaphore 物件不代表具名系統號誌。
範例
下列程式碼範例示範具有存取控制安全性之具名號志的跨進程行為。 此範例會 OpenExisting(String) 使用 方法多載來測試具名號志是否存在。
如果旗號不存在，則會建立其計數上限為 2，且存取控制安全性會拒絕目前使用者使用旗號的許可權，但授與號志的讀取和變更許可權的許可權。
如果您從兩個命令視窗執行編譯的範例，第二個複本會在呼叫 OpenExisting(String) 方法時擲回存取違規例外狀況。 攔截到例外狀況，而此範例會 OpenExisting(String, SemaphoreRights) 使用 方法多載來開啟號志，並具有讀取和變更許可權所需的許可權。
變更許可權之後，會使用 SetAccessControl 方法開啟號志，並具有輸入和釋放所需的許可權。 如果您從第三個命令視窗執行已編譯的範例，它會使用新的許可權來執行。
#using <System.dll>
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^ semaphoreName = L"SemaphoreExample5";
Semaphore^ sem = nullptr;
bool doesNotExist = false;
bool unauthorized = false;
// Attempt to open the named semaphore.
try
{
// Open the semaphore with (SemaphoreRights.Synchronize
// | SemaphoreRights.Modify), to enter and release the
// named semaphore.
//
sem = Semaphore::OpenExisting( semaphoreName );
}
catch ( WaitHandleCannotBeOpenedException^ ex )
{
Console::WriteLine( L"Semaphore does not exist." );
doesNotExist = true;
}
catch ( UnauthorizedAccessException^ ex )
{
Console::WriteLine( L"Unauthorized access: {0}", ex->Message );
unauthorized = true;
}
// There are three cases: (1) The semaphore does not exist.
// (2) The semaphore exists, but the current user doesn't
// have access. (3) The semaphore exists and the user has
// access.
//
if ( doesNotExist )
{
// The semaphore does not exist, so create it.
//
// The value of this variable is set by the semaphore
// constructor. It is true if the named system semaphore was
// created, and false if the named semaphore already existed.
//
bool semaphoreWasCreated;
// Create an access control list (ACL) that denies the
// current user the right to enter or release the
// semaphore, but allows the right to read and change
// security information for the semaphore.
//
String^ user = String::Concat( Environment::UserDomainName,
L"\\", Environment::UserName );
SemaphoreSecurity^ semSec = gcnew SemaphoreSecurity;
SemaphoreAccessRule^ rule = gcnew SemaphoreAccessRule( user,
static_cast<SemaphoreRights>(
SemaphoreRights::Synchronize |
SemaphoreRights::Modify ),
AccessControlType::Deny );
semSec->AddAccessRule( rule );
rule = gcnew SemaphoreAccessRule( user,
static_cast<SemaphoreRights>(
SemaphoreRights::ReadPermissions |
SemaphoreRights::ChangePermissions ),
AccessControlType::Allow );
semSec->AddAccessRule( rule );
// Create a Semaphore object that represents the system
// semaphore named by the constant 'semaphoreName', with
// maximum count three, initial count three, and the
// specified security access. The Boolean value that
// indicates creation of the underlying system object is
// placed in semaphoreWasCreated.
//
sem = gcnew Semaphore( 3,3,semaphoreName,semaphoreWasCreated,semSec );
// If the named system semaphore was created, it can be
// used by the current instance of this program, even
// though the current user is denied access. The current
// program enters the semaphore. Otherwise, exit the
// program.
//
if ( semaphoreWasCreated )
{
Console::WriteLine( L"Created the semaphore." );
}
else
{
Console::WriteLine( L"Unable to create the semaphore." );
return;
}
}
else if ( unauthorized )
{
// Open the semaphore to read and change the access
// control security. The access control security defined
// above allows the current user to do this.
//
try
{
sem = Semaphore::OpenExisting( semaphoreName,
static_cast<SemaphoreRights>(
SemaphoreRights::ReadPermissions |
SemaphoreRights::ChangePermissions ));
// Get the current ACL. This requires
// SemaphoreRights.ReadPermissions.
SemaphoreSecurity^ semSec = sem->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 semaphore must
// be removed.
SemaphoreAccessRule^ rule = gcnew SemaphoreAccessRule( user,
static_cast<SemaphoreRights>(
SemaphoreRights::Synchronize |
SemaphoreRights::Modify ),
AccessControlType::Deny );
semSec->RemoveAccessRule( rule );
// Now grant the user the correct rights.
//
rule = gcnew SemaphoreAccessRule( user,
static_cast<SemaphoreRights>(
SemaphoreRights::Synchronize |
SemaphoreRights::Modify ),
AccessControlType::Allow );
semSec->AddAccessRule( rule );
// Update the ACL. This requires
// SemaphoreRights.ChangePermissions.
sem->SetAccessControl( semSec );
Console::WriteLine( L"Updated semaphore security." );
// Open the semaphore with (SemaphoreRights.Synchronize
// | SemaphoreRights.Modify), the rights required to
// enter and release the semaphore.
//
sem = Semaphore::OpenExisting( semaphoreName );
}
catch ( UnauthorizedAccessException^ ex )
{
Console::WriteLine( L"Unable to change permissions: {0}", ex->Message );
return;
}
}
// Enter the semaphore, and hold it until the program
// exits.
//
try
{
sem->WaitOne();
Console::WriteLine( L"Entered the semaphore." );
Console::WriteLine( L"Press the Enter key to exit." );
Console::ReadLine();
sem->Release();
}
catch ( UnauthorizedAccessException^ ex )
{
Console::WriteLine( L"Unauthorized access: {0}", ex->Message );
}
}
};
using System;
using System.Threading;
using System.Security.AccessControl;
internal class Example
{
internal static void Main()
{
const string semaphoreName = "SemaphoreExample5";
Semaphore sem = null;
bool doesNotExist = false;
bool unauthorized = false;
// Attempt to open the named semaphore.
try
{
// Open the semaphore with (SemaphoreRights.Synchronize
// | SemaphoreRights.Modify), to enter and release the
// named semaphore.
//
sem = Semaphore.OpenExisting(semaphoreName);
}
catch(WaitHandleCannotBeOpenedException)
{
Console.WriteLine("Semaphore does not exist.");
doesNotExist = true;
}
catch(UnauthorizedAccessException ex)
{
Console.WriteLine("Unauthorized access: {0}", ex.Message);
unauthorized = true;
}
// There are three cases: (1) The semaphore does not exist.
// (2) The semaphore exists, but the current user doesn't
// have access. (3) The semaphore exists and the user has
// access.
//
if (doesNotExist)
{
// The semaphore does not exist, so create it.
//
// The value of this variable is set by the semaphore
// constructor. It is true if the named system semaphore was
// created, and false if the named semaphore already existed.
//
bool semaphoreWasCreated;
// Create an access control list (ACL) that denies the
// current user the right to enter or release the
// semaphore, but allows the right to read and change
// security information for the semaphore.
//
string user = Environment.UserDomainName + "\\"
+ Environment.UserName;
SemaphoreSecurity semSec = new SemaphoreSecurity();
SemaphoreAccessRule rule = new SemaphoreAccessRule(
user,
SemaphoreRights.Synchronize | SemaphoreRights.Modify,
AccessControlType.Deny);
semSec.AddAccessRule(rule);
rule = new SemaphoreAccessRule(
user,
SemaphoreRights.ReadPermissions | SemaphoreRights.ChangePermissions,
AccessControlType.Allow);
semSec.AddAccessRule(rule);
// Create a Semaphore object that represents the system
// semaphore named by the constant 'semaphoreName', with
// maximum count three, initial count three, and the
// specified security access. The Boolean value that
// indicates creation of the underlying system object is
// placed in semaphoreWasCreated.
//
sem = new Semaphore(3, 3, semaphoreName,
out semaphoreWasCreated, semSec);
// If the named system semaphore was created, it can be
// used by the current instance of this program, even
// though the current user is denied access. The current
// program enters the semaphore. Otherwise, exit the
// program.
//
if (semaphoreWasCreated)
{
Console.WriteLine("Created the semaphore.");
}
else
{
Console.WriteLine("Unable to create the semaphore.");
return;
}
}
else if (unauthorized)
{
// Open the semaphore to read and change the access
// control security. The access control security defined
// above allows the current user to do this.
//
try
{
sem = Semaphore.OpenExisting(
semaphoreName,
SemaphoreRights.ReadPermissions
| SemaphoreRights.ChangePermissions);
// Get the current ACL. This requires
// SemaphoreRights.ReadPermissions.
SemaphoreSecurity semSec = sem.GetAccessControl();
string user = Environment.UserDomainName + "\\"
+ Environment.UserName;
// First, the rule that denied the current user
// the right to enter and release the semaphore must
// be removed.
SemaphoreAccessRule rule = new SemaphoreAccessRule(
user,
SemaphoreRights.Synchronize | SemaphoreRights.Modify,
AccessControlType.Deny);
semSec.RemoveAccessRule(rule);
// Now grant the user the correct rights.
//
rule = new SemaphoreAccessRule(user,
SemaphoreRights.Synchronize | SemaphoreRights.Modify,
AccessControlType.Allow);
semSec.AddAccessRule(rule);
// Update the ACL. This requires
// SemaphoreRights.ChangePermissions.
sem.SetAccessControl(semSec);
Console.WriteLine("Updated semaphore security.");
// Open the semaphore with (SemaphoreRights.Synchronize
// | SemaphoreRights.Modify), the rights required to
// enter and release the semaphore.
//
sem = Semaphore.OpenExisting(semaphoreName);
}
catch(UnauthorizedAccessException ex)
{
Console.WriteLine("Unable to change permissions: {0}", ex.Message);
return;
}
}
// Enter the semaphore, and hold it until the program
// exits.
//
try
{
sem.WaitOne();
Console.WriteLine("Entered the semaphore.");
Console.WriteLine("Press the Enter key to exit.");
Console.ReadLine();
sem.Release();
}
catch(UnauthorizedAccessException ex)
{
Console.WriteLine("Unauthorized access: {0}", ex.Message);
}
}
}
Imports System.Threading
Imports System.Security.AccessControl
Friend Class Example
<MTAThread> _
Friend Shared Sub Main()
Const semaphoreName As String = "SemaphoreExample5"
Dim sem As Semaphore = Nothing
Dim doesNotExist as Boolean = False
Dim unauthorized As Boolean = False
' Attempt to open the named semaphore.
Try
' Open the semaphore with (SemaphoreRights.Synchronize
' Or SemaphoreRights.Modify), to enter and release the
' named semaphore.
'
sem = Semaphore.OpenExisting(semaphoreName)
Catch ex As WaitHandleCannotBeOpenedException
Console.WriteLine("Semaphore 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 semaphore does not exist.
' (2) The semaphore exists, but the current user doesn't
' have access. (3) The semaphore exists and the user has
' access.
'
If doesNotExist Then
' The semaphore does not exist, so create it.
'
' The value of this variable is set by the semaphore
' constructor. It is True if the named system semaphore was
' created, and False if the named semaphore already existed.
'
Dim semaphoreWasCreated As Boolean
' Create an access control list (ACL) that denies the
' current user the right to enter or release the
' semaphore, but allows the right to read and change
' security information for the semaphore.
'
Dim user As String = Environment.UserDomainName _
& "\" & Environment.UserName
Dim semSec As New SemaphoreSecurity()
Dim rule As New SemaphoreAccessRule(user, _
SemaphoreRights.Synchronize Or SemaphoreRights.Modify, _
AccessControlType.Deny)
semSec.AddAccessRule(rule)
rule = New SemaphoreAccessRule(user, _
SemaphoreRights.ReadPermissions Or _
SemaphoreRights.ChangePermissions, _
AccessControlType.Allow)
semSec.AddAccessRule(rule)
' Create a Semaphore object that represents the system
' semaphore named by the constant 'semaphoreName', with
' maximum count three, initial count three, and the
' specified security access. The Boolean value that
' indicates creation of the underlying system object is
' placed in semaphoreWasCreated.
'
sem = New Semaphore(3, 3, semaphoreName, _
semaphoreWasCreated, semSec)
' If the named system semaphore was created, it can be
' used by the current instance of this program, even
' though the current user is denied access. The current
' program enters the semaphore. Otherwise, exit the
' program.
'
If semaphoreWasCreated Then
Console.WriteLine("Created the semaphore.")
Else
Console.WriteLine("Unable to create the semaphore.")
Return
End If
ElseIf unauthorized Then
' Open the semaphore to read and change the access
' control security. The access control security defined
' above allows the current user to do this.
'
Try
sem = Semaphore.OpenExisting(semaphoreName, _
SemaphoreRights.ReadPermissions Or _
SemaphoreRights.ChangePermissions)
' Get the current ACL. This requires
' SemaphoreRights.ReadPermissions.
Dim semSec As SemaphoreSecurity = sem.GetAccessControl()
Dim user As String = Environment.UserDomainName _
& "\" & Environment.UserName
' First, the rule that denied the current user
' the right to enter and release the semaphore must
' be removed.
Dim rule As New SemaphoreAccessRule(user, _
SemaphoreRights.Synchronize Or SemaphoreRights.Modify, _
AccessControlType.Deny)
semSec.RemoveAccessRule(rule)
' Now grant the user the correct rights.
'
rule = New SemaphoreAccessRule(user, _
SemaphoreRights.Synchronize Or SemaphoreRights.Modify, _
AccessControlType.Allow)
semSec.AddAccessRule(rule)
' Update the ACL. This requires
' SemaphoreRights.ChangePermissions.
sem.SetAccessControl(semSec)
Console.WriteLine("Updated semaphore security.")
' Open the semaphore with (SemaphoreRights.Synchronize
' Or SemaphoreRights.Modify), the rights required to
' enter and release the semaphore.
'
sem = Semaphore.OpenExisting(semaphoreName)
Catch ex As UnauthorizedAccessException
Console.WriteLine("Unable to change permissions: {0}", _
ex.Message)
Return
End Try
End If
' Enter the semaphore, and hold it until the program
' exits.
'
Try
sem.WaitOne()
Console.WriteLine("Entered the semaphore.")
Console.WriteLine("Press the Enter key to exit.")
Console.ReadLine()
sem.Release()
Catch ex As UnauthorizedAccessException
Console.WriteLine("Unauthorized access: {0}", _
ex.Message)
End Try
End Sub
End Class
備註
您只能在代表具名系統旗號的物件上 Semaphore 設定存取控制安全性。
使用者必須具有 SemaphoreRights.ChangePermissions 呼叫這個方法的許可權，而且必須以許可權開啟 SemaphoreRights.ChangePermissions 號志。
