Semaphore.SetAccessControl メソッド
アセンブリ: System (system.dll 内)

Dim instance As Semaphore Dim semaphoreSecurity As SemaphoreSecurity instance.SetAccessControl(semaphoreSecurity)


アクセス制御セキュリティは、名前付きシステム セマフォを表す Semaphore オブジェクトにだけ設定できます。
このメソッドを呼び出すための SemaphoreRights.ChangePermissions 権限がユーザーにあることが必要であり、セマフォは SemaphoreRights.ChangePermissions 権限で開かれている必要があります。

アクセス制御セキュリティを使用した名前付きセマフォのプロセス間の動作をデモンストレーションするコード例を次に示します。この例では、OpenExisting(String) メソッド オーバーロードを使用して、名前付きセマフォが存在するかどうかをテストしています。
セマフォが存在しない場合、カウントの最大値を 2 に指定し、現在のユーザーによるセマフォの使用を拒否しセマフォに対する読み取りと変更のアクセス許可のみ付与するアクセス制御セキュリティを指定して、セマフォが作成されます。
2 つのコマンド ウィンドウからコンパイルした例を実行すると、2 番目のコピーは OpenExisting(String) メソッドの呼び出しでアクセス違反例外をスローします。例外がキャッチされると、OpenExisting(String,SemaphoreRights) メソッド オーバーロードを使用し、アクセス許可の読み取りと変更に必要な権限で、セマフォを開きます。
アクセス許可が変更された後、SetAccessControl メソッドを使用して、入力と解放に必要な権限でセマフォが開かれます。3 つ目のコマンド ウィンドウからコンパイル済みの例を実行する場合、新しいアクセス許可を使用して実行されます。
Imports System 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
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); } } }
#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 ); } } };

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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