Mutex.OpenExisting Método

Definição

Abre um mutex nomeado especificado, caso ele já exista.Opens a specified named mutex, if it already exists.

Sobrecargas

OpenExisting(String)

Abre o mutex nomeado especificado, caso ele já exista.Opens the specified named mutex, if it already exists.

OpenExisting(String, MutexRights)

Abre o mutex nomeado especificado, caso ele já exista, com o acesso de segurança desejado.Opens the specified named mutex, if it already exists, with the desired security access.

OpenExisting(String)

Abre o mutex nomeado especificado, caso ele já exista.Opens the specified named mutex, if it already exists.

public:
 static System::Threading::Mutex ^ OpenExisting(System::String ^ name);
public static System.Threading.Mutex OpenExisting (string name);
[System.Security.SecurityCritical]
public static System.Threading.Mutex OpenExisting (string name);
static member OpenExisting : string -> System.Threading.Mutex
[<System.Security.SecurityCritical>]
static member OpenExisting : string -> System.Threading.Mutex
Public Shared Function OpenExisting (name As String) As Mutex

Parâmetros

name
String

O nome do objeto de sincronização a ser compartilhado com outros processos.The name of the synchronization object to be shared with other processes. O nome diferencia maiúsculas de minúsculas.The name is case-sensitive.

Retornos

Mutex

Um objeto que representa o mutex do sistema nomeado.An object that represents the named system mutex.

Atributos

Exceções

name é uma cadeia de caracteres vazia.name is an empty string.

- ou --or-

Somente .NET Framework: name é maior que MAX_PATH (260 caracteres)..NET Framework only: name is longer than MAX_PATH (260 characters).

name é null.name is null.

Não é possível criar um objeto de sincronização com o name fornecido.A synchronization object with the provided name cannot be created. Um objeto de sincronização de um tipo diferente pode ter o mesmo nome.A synchronization object of a different type might have the same name. Em alguns casos, essa exceção pode ser lançada para nomes inválidos.In some cases, this exception may be thrown for invalid names.

name é inválido.name is invalid. Isso pode ser por vários motivos, incluindo algumas restrições impostas pelo sistema operacional, como um prefixo desconhecido ou caracteres inválidos.This can be for various reasons, including some restrictions that may be placed by the operating system, such as an unknown prefix or invalid characters. Observe que o nome e os prefixos comuns "Global" e "Local" diferenciam maiúsculas de minúsculas.Note that the name and common prefixes "Global" and "Local" are case-sensitive.

- ou --or-

Ocorreu outro erro.There was some other error. A propriedade HResult pode fornecer mais informações.The HResult property may provide more information.

Somente Windows: name especificou um namespace desconhecido.Windows only: name specified an unknown namespace. Confira mais informações em Nomes do objeto.See Object Names for more information.

O name é muito longo.The name is too long. As restrições de comprimento podem depender do sistema operacional ou da configuração.Length restrictions may depend on the operating system or configuration.

O mutex nomeado existe, mas o usuário não tem o acesso de segurança necessário para usá-lo.The named mutex exists, but the user does not have the security access required to use it.

Exemplos

O exemplo de código a seguir demonstra o comportamento de processo cruzado de um mutex nomeado com segurança de controle de acesso.The following code example demonstrates the cross-process behavior of a named mutex with access control security. O exemplo usa a OpenExisting(String) sobrecarga do método para testar a existência de um mutex nomeado.The example uses the OpenExisting(String) method overload to test for the existence of a named mutex.

Se o mutex não existir, ele será criado com a propriedade inicial e a segurança de controle de acesso que nega ao usuário atual o direito de usar o mutex, mas concede o direito de ler e alterar permissões no mutex.If the mutex does not exist, it is created with initial ownership and access control security that denies the current user the right to use the mutex, but grants the right to read and change permissions on the mutex.

Se você executar o exemplo compilado de duas janelas de comando, a segunda cópia gerará uma exceção de violação de acesso na chamada para OpenExisting(String) .If you run the compiled example from two command windows, the second copy will throw an access violation exception on the call to OpenExisting(String). A exceção é capturada e o exemplo usa a OpenExisting(String, MutexRights) sobrecarga do método para abrir o mutex com os direitos necessários para ler e alterar as permissões.The exception is caught, and the example uses the OpenExisting(String, MutexRights) method overload to open the mutex with the rights needed to read and change the permissions.

Depois que as permissões são alteradas, o mutex é aberto com os direitos necessários para inseri-lo e liberá-lo.After the permissions are changed, the mutex is opened with the rights required to enter and release it. Se você executar o exemplo compilado de uma terceira janela de comando, ele será executado usando as novas permissões.If you run the compiled example from a third command window, it runs using the new permissions.

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^ mutexName = L"MutexExample4";

      Mutex^ m = nullptr;
      bool doesNotExist = false;
      bool unauthorized = false;
      
      // The value of this variable is set by the mutex
      // constructor. It is true if the named system mutex was
      // created, and false if the named mutex already existed.
      //
      bool mutexWasCreated = false;

      // Attempt to open the named mutex.
      try
      {
         // Open the mutex with (MutexRights.Synchronize |
         // MutexRights.Modify), to enter and release the
         // named mutex.
         //
         m = Mutex::OpenExisting( mutexName );
      }
      catch ( WaitHandleCannotBeOpenedException^ ) 
      {
         Console::WriteLine( L"Mutex does not exist." );
         doesNotExist = true;
      }
      catch ( UnauthorizedAccessException^ ex ) 
      {
         Console::WriteLine( L"Unauthorized access: {0}", ex->Message );
         unauthorized = true;
      }

      // There are three cases: (1) The mutex does not exist.
      // (2) The mutex exists, but the current user doesn't
      // have access. (3) The mutex exists and the user has
      // access.
      //
      if ( doesNotExist )
      {
         // The mutex does not exist, so create it.
         // Create an access control list (ACL) that denies the
         // current user the right to enter or release the
         // mutex, but allows the right to read and change
         // security information for the mutex.
         //
         String^ user = String::Concat( Environment::UserDomainName, L"\\",
            Environment::UserName );
         MutexSecurity^ mSec = gcnew MutexSecurity;

         MutexAccessRule^ rule = gcnew MutexAccessRule( user,
            static_cast<MutexRights>(
               MutexRights::Synchronize |
               MutexRights::Modify),
            AccessControlType::Deny );
         mSec->AddAccessRule( rule );

         rule = gcnew MutexAccessRule( user,
            static_cast<MutexRights>(
               MutexRights::ReadPermissions |
                MutexRights::ChangePermissions),
            AccessControlType::Allow );
         mSec->AddAccessRule( rule );
         
         // Create a Mutex object that represents the system
         // mutex named by the constant 'mutexName', with
         // initial ownership for this thread, and with the
         // specified security access. The Boolean value that
         // indicates creation of the underlying system object
         // is placed in mutexWasCreated.
         //
         m = gcnew Mutex( true,mutexName, mutexWasCreated,mSec );
         
         // If the named system mutex 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 mutex. Otherwise, exit the program.
         //
         if ( mutexWasCreated )
         {
            Console::WriteLine( L"Created the mutex." );
         }
         else
         {
            Console::WriteLine( L"Unable to create the mutex." );
            return;
         }
      }
      else if ( unauthorized )
      {
         // Open the mutex to read and change the access control
         // security. The access control security defined above
         // allows the current user to do this.
         //
         try
         {
            m = Mutex::OpenExisting( mutexName,
               static_cast<MutexRights>(
                  MutexRights::ReadPermissions |
                  MutexRights::ChangePermissions) );
            
            // Get the current ACL. This requires
            // MutexRights.ReadPermissions.
            MutexSecurity^ mSec = m->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 mutex must
            // be removed.
            MutexAccessRule^ rule = gcnew MutexAccessRule( user,
               static_cast<MutexRights>(
                  MutexRights::Synchronize |
                  MutexRights::Modify),
               AccessControlType::Deny );
            mSec->RemoveAccessRule( rule );
            
            // Now grant the user the correct rights.
            //
            rule = gcnew MutexAccessRule( user,
               static_cast<MutexRights>(
                  MutexRights::Synchronize |
                  MutexRights::Modify),
               AccessControlType::Allow );
            mSec->AddAccessRule( rule );
            
            // Update the ACL. This requires
            // MutexRights.ChangePermissions.
            m->SetAccessControl( mSec );

            Console::WriteLine( L"Updated mutex security." );
            
            // Open the mutex with (MutexRights.Synchronize
            // | MutexRights.Modify), the rights required to
            // enter and release the mutex.
            //
            m = Mutex::OpenExisting( mutexName );
         }
         catch ( UnauthorizedAccessException^ ex ) 
         {
            Console::WriteLine(
               L"Unable to change permissions: {0}", ex->Message );
            return;
         }
      }
      
      // If this program created the mutex, it already owns
      // the mutex.
      //
      if ( !mutexWasCreated )
      {
         // Enter the mutex, and hold it until the program
         // exits.
         //
         try
         {
            Console::WriteLine( L"Wait for the mutex." );
            m->WaitOne();
            Console::WriteLine( L"Entered the mutex." );
         }
         catch ( UnauthorizedAccessException^ ex ) 
         {
            Console::WriteLine( L"Unauthorized access: {0}",
               ex->Message );
         }
      }

      Console::WriteLine( L"Press the Enter key to exit." );
      Console::ReadLine();
      m->ReleaseMutex();
      m->Dispose();
   }
};

int main()
{
   Example::Main();
}
using System;
using System.Threading;
using System.Security.AccessControl;

internal class Example
{
    internal static void Main()
    {
        const string mutexName = "MutexExample4";

        Mutex m = null;
        bool doesNotExist = false;
        bool unauthorized = false;

        // The value of this variable is set by the mutex
        // constructor. It is true if the named system mutex was
        // created, and false if the named mutex already existed.
        //
        bool mutexWasCreated = false;

        // Attempt to open the named mutex.
        try
        {
            // Open the mutex with (MutexRights.Synchronize |
            // MutexRights.Modify), to enter and release the
            // named mutex.
            //
            m = Mutex.OpenExisting(mutexName);
        }
        catch(WaitHandleCannotBeOpenedException)
        {
            Console.WriteLine("Mutex does not exist.");
            doesNotExist = true;
        }
        catch(UnauthorizedAccessException ex)
        {
            Console.WriteLine("Unauthorized access: {0}", ex.Message);
            unauthorized = true;
        }

        // There are three cases: (1) The mutex does not exist.
        // (2) The mutex exists, but the current user doesn't 
        // have access. (3) The mutex exists and the user has
        // access.
        //
        if (doesNotExist)
        {
            // The mutex does not exist, so create it.

            // Create an access control list (ACL) that denies the
            // current user the right to enter or release the 
            // mutex, but allows the right to read and change
            // security information for the mutex.
            //
            string user = Environment.UserDomainName + "\\"
                + Environment.UserName;
            MutexSecurity mSec = new MutexSecurity();

            MutexAccessRule rule = new MutexAccessRule(user, 
                MutexRights.Synchronize | MutexRights.Modify, 
                AccessControlType.Deny);
            mSec.AddAccessRule(rule);

            rule = new MutexAccessRule(user, 
                MutexRights.ReadPermissions | MutexRights.ChangePermissions,
                AccessControlType.Allow);
            mSec.AddAccessRule(rule);

            // Create a Mutex object that represents the system
            // mutex named by the constant 'mutexName', with
            // initial ownership for this thread, and with the
            // specified security access. The Boolean value that 
            // indicates creation of the underlying system object
            // is placed in mutexWasCreated.
            //
            m = new Mutex(true, mutexName, out mutexWasCreated, mSec);

            // If the named system mutex 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 mutex. Otherwise, exit the program.
            // 
            if (mutexWasCreated)
            {
                Console.WriteLine("Created the mutex.");
            }
            else
            {
                Console.WriteLine("Unable to create the mutex.");
                return;
            }
        }
        else if (unauthorized)
        {
            // Open the mutex to read and change the access control
            // security. The access control security defined above
            // allows the current user to do this.
            //
            try
            {
                m = Mutex.OpenExisting(mutexName, 
                    MutexRights.ReadPermissions | MutexRights.ChangePermissions);

                // Get the current ACL. This requires 
                // MutexRights.ReadPermissions.
                MutexSecurity mSec = m.GetAccessControl();
                
                string user = Environment.UserDomainName + "\\"
                    + Environment.UserName;

                // First, the rule that denied the current user 
                // the right to enter and release the mutex must
                // be removed.
                MutexAccessRule rule = new MutexAccessRule(user, 
                     MutexRights.Synchronize | MutexRights.Modify,
                     AccessControlType.Deny);
                mSec.RemoveAccessRule(rule);

                // Now grant the user the correct rights.
                // 
                rule = new MutexAccessRule(user, 
                    MutexRights.Synchronize | MutexRights.Modify,
                    AccessControlType.Allow);
                mSec.AddAccessRule(rule);

                // Update the ACL. This requires
                // MutexRights.ChangePermissions.
                m.SetAccessControl(mSec);

                Console.WriteLine("Updated mutex security.");

                // Open the mutex with (MutexRights.Synchronize 
                // | MutexRights.Modify), the rights required to
                // enter and release the mutex.
                //
                m = Mutex.OpenExisting(mutexName);
            }
            catch(UnauthorizedAccessException ex)
            {
                Console.WriteLine("Unable to change permissions: {0}",
                    ex.Message);
                return;
            }
        }

        // If this program created the mutex, it already owns
        // the mutex.
        //
        if (!mutexWasCreated)
        {
            // Enter the mutex, and hold it until the program
            // exits.
            //
            try
            {
                Console.WriteLine("Wait for the mutex.");
                m.WaitOne();
                Console.WriteLine("Entered the mutex.");
            }
            catch(UnauthorizedAccessException ex)
            {
                Console.WriteLine("Unauthorized access: {0}", ex.Message);
            }
        }

        Console.WriteLine("Press the Enter key to exit.");
        Console.ReadLine();
        m.ReleaseMutex();
        m.Dispose();
    }
}
Imports System.Threading
Imports System.Security.AccessControl

Friend Class Example

    <MTAThread> _
    Friend Shared Sub Main()
        Const mutexName As String = "MutexExample4"

        Dim m As Mutex = Nothing
        Dim doesNotExist as Boolean = False
        Dim unauthorized As Boolean = False

        ' The value of this variable is set by the mutex
        ' constructor. It is True if the named system mutex was
        ' created, and False if the named mutex already existed.
        '
        Dim mutexWasCreated As Boolean

        ' Attempt to open the named mutex.
        Try
            ' Open the mutex with (MutexRights.Synchronize Or
            ' MutexRights.Modify), to enter and release the
            ' named mutex.
            '
            m = Mutex.OpenExisting(mutexName)
        Catch ex As WaitHandleCannotBeOpenedException
            Console.WriteLine("Mutex 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 mutex does not exist.
        ' (2) The mutex exists, but the current user doesn't 
        ' have access. (3) The mutex exists and the user has
        ' access.
        '
        If doesNotExist Then
            ' The mutex does not exist, so create it.

            ' Create an access control list (ACL) that denies the
            ' current user the right to enter or release the 
            ' mutex, but allows the right to read and change
            ' security information for the mutex.
            '
            Dim user As String = Environment.UserDomainName _ 
                & "\" & Environment.UserName
            Dim mSec As New MutexSecurity()

            Dim rule As New MutexAccessRule(user, _
                MutexRights.Synchronize Or MutexRights.Modify, _
                AccessControlType.Deny)
            mSec.AddAccessRule(rule)

            rule = New MutexAccessRule(user, _
                MutexRights.ReadPermissions Or _
                MutexRights.ChangePermissions, _
                AccessControlType.Allow)
            mSec.AddAccessRule(rule)

            ' Create a Mutex object that represents the system
            ' mutex named by the constant 'mutexName', with
            ' initial ownership for this thread, and with the
            ' specified security access. The Boolean value that 
            ' indicates creation of the underlying system object
            ' is placed in mutexWasCreated.
            '
            m = New Mutex(True, mutexName, mutexWasCreated, mSec)

            ' If the named system mutex 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 mutex. Otherwise, exit the program.
            ' 
            If mutexWasCreated Then
                Console.WriteLine("Created the mutex.")
            Else
                Console.WriteLine("Unable to create the mutex.")
                Return
            End If

        ElseIf unauthorized Then

            ' Open the mutex to read and change the access control
            ' security. The access control security defined above
            ' allows the current user to do this.
            '
            Try
                m = Mutex.OpenExisting(mutexName, _
                    MutexRights.ReadPermissions Or _
                    MutexRights.ChangePermissions)

                ' Get the current ACL. This requires 
                ' MutexRights.ReadPermissions.
                Dim mSec As MutexSecurity = m.GetAccessControl()
                
                Dim user As String = Environment.UserDomainName _ 
                    & "\" & Environment.UserName

                ' First, the rule that denied the current user 
                ' the right to enter and release the mutex must
                ' be removed.
                Dim rule As New MutexAccessRule(user, _
                    MutexRights.Synchronize Or MutexRights.Modify, _
                    AccessControlType.Deny)
                mSec.RemoveAccessRule(rule)

                ' Now grant the user the correct rights.
                ' 
                rule = New MutexAccessRule(user, _
                    MutexRights.Synchronize Or MutexRights.Modify, _
                    AccessControlType.Allow)
                mSec.AddAccessRule(rule)

                ' Update the ACL. This requires
                ' MutexRights.ChangePermissions.
                m.SetAccessControl(mSec)

                Console.WriteLine("Updated mutex security.")

                ' Open the mutex with (MutexRights.Synchronize 
                ' Or MutexRights.Modify), the rights required to
                ' enter and release the mutex.
                '
                m = Mutex.OpenExisting(mutexName)

            Catch ex As UnauthorizedAccessException
                Console.WriteLine("Unable to change permissions: {0}", _
                    ex.Message)
                Return
            End Try

        End If

        ' If this program created the mutex, it already owns
        ' the mutex.
        '
        If Not mutexWasCreated Then
            ' Enter the mutex, and hold it until the program
            ' exits.
            '
            Try
                Console.WriteLine("Wait for the mutex.")
                m.WaitOne()
                Console.WriteLine("Entered the mutex.")
            Catch ex As UnauthorizedAccessException
                Console.WriteLine("Unauthorized access: {0}", _
                    ex.Message)
            End Try
        End If

        Console.WriteLine("Press the Enter key to exit.")
        Console.ReadLine()
        m.ReleaseMutex()
        m.Dispose()
    End Sub 
End Class 

Comentários

O name pode ser prefixado com Global\ or Local\ para especificar um namespace.The name may be prefixed with Global\ or Local\ to specify a namespace. Quando o Global namespace é especificado, o objeto de sincronização pode ser compartilhado com qualquer processo no sistema.When the Global namespace is specified, the synchronization object may be shared with any processes on the system. Quando o Local namespace é especificado, que também é o padrão quando nenhum namespace é especificado, o objeto de sincronização pode ser compartilhado com processos na mesma sessão.When the Local namespace is specified, which is also the default when no namespace is specified, the synchronization object may be shared with processes in the same session. No Windows, uma sessão é uma sessão de logon e os serviços normalmente são executados em uma sessão não interativa diferente.On Windows, a session is a login session, and services typically run in a different non-interactive session. Em sistemas operacionais semelhantes ao Unix, cada shell tem sua própria sessão.On Unix-like operating systems, each shell has its own session. Os objetos de sincronização de sessão local podem ser apropriados para sincronizar entre processos com uma relação pai/filho em que todos eles são executados na mesma sessão.Session-local synchronization objects may be appropriate for synchronizing between processes with a parent/child relationship where they all run in the same session. Para obter mais informações sobre nomes de objetos Synchornization no Windows, consulte nomes de objetos.For more information about synchornization object names on Windows, see Object Names.

Se um objeto de sincronização do tipo solicitado existir no namespace, o objeto de sincronização existente será aberto.If a synchronization object of the requested type exists in the namespace, the existing synchronization object is opened. Se um objeto de sincronização não existir no namespace ou se um objeto de sincronização de um tipo diferente existir no namespace, um WaitHandleCannotBeOpenedException será gerado.If a synchronization object does not exist in the namespace, or a synchronization object of a different type exists in the namespace, a WaitHandleCannotBeOpenedException is thrown.

O OpenExisting método tenta abrir o mutex do sistema nomeado especificado.The OpenExisting method tries to open the specified named system mutex. Para criar o mutex do sistema quando ele ainda não existir, use um dos Mutex construtores que tem um name parâmetro.To create the system mutex when it does not already exist, use one of the Mutex constructors that has a name parameter.

Várias chamadas para esse método que usam o mesmo valor para não name retornam necessariamente o mesmo Mutex objeto, embora os objetos retornados representem o mesmo mutex de sistema nomeado.Multiple calls to this method that use the same value for name do not necessarily return the same Mutex object, even though the objects that are returned represent the same named system mutex.

Essa sobrecarga de método é equivalente à chamada da OpenExisting(String, MutexRights) sobrecarga do método e à especificação MutexRights.Synchronize e MutexRights.Modify aos direitos, combinados com o uso da operação OR bit a bit.This method overload is equivalent to calling the OpenExisting(String, MutexRights) method overload and specifying MutexRights.Synchronize and MutexRights.Modify rights, combined by using the bitwise OR operation.

Especificar o MutexRights.Synchronize sinalizador permite que um thread aguarde o mutex e especificar o MutexRights.Modify sinalizador permite que um thread chame o ReleaseMutex método.Specifying the MutexRights.Synchronize flag allows a thread to wait on the mutex, and specifying the MutexRights.Modify flag allows a thread to call the ReleaseMutex method.

Esse método não solicita a propriedade do mutex.This method does not request ownership of the mutex.

Aplica-se a

OpenExisting(String, MutexRights)

Abre o mutex nomeado especificado, caso ele já exista, com o acesso de segurança desejado.Opens the specified named mutex, if it already exists, with the desired security access.

public:
 static System::Threading::Mutex ^ OpenExisting(System::String ^ name, System::Security::AccessControl::MutexRights rights);
public static System.Threading.Mutex OpenExisting (string name, System.Security.AccessControl.MutexRights rights);
[System.Security.SecurityCritical]
public static System.Threading.Mutex OpenExisting (string name, System.Security.AccessControl.MutexRights rights);
static member OpenExisting : string * System.Security.AccessControl.MutexRights -> System.Threading.Mutex
[<System.Security.SecurityCritical>]
static member OpenExisting : string * System.Security.AccessControl.MutexRights -> System.Threading.Mutex
Public Shared Function OpenExisting (name As String, rights As MutexRights) As Mutex

Parâmetros

name
String

O nome do objeto de sincronização a ser compartilhado com outros processos.The name of the synchronization object to be shared with other processes. O nome diferencia maiúsculas de minúsculas.The name is case-sensitive.

rights
MutexRights

Uma combinação bit a bit dos valores de enumeração que representa o acesso de segurança desejado.A bitwise combination of the enumeration values that represent the desired security access.

Retornos

Mutex

Um objeto que representa o mutex do sistema nomeado.An object that represents the named system mutex.

Atributos

Exceções

name é uma cadeia de caracteres vazia.name is an empty string.

- ou --or-

Somente .NET Framework: name é maior que MAX_PATH (260 caracteres)..NET Framework only: name is longer than MAX_PATH (260 characters).

name é null.name is null.

Não é possível criar um objeto de sincronização com o name fornecido.A synchronization object with the provided name cannot be created. Um objeto de sincronização de um tipo diferente pode ter o mesmo nome.A synchronization object of a different type might have the same name. Em alguns casos, essa exceção pode ser lançada para nomes inválidos.In some cases, this exception may be thrown for invalid names.

name é inválido.name is invalid. Isso pode ser por vários motivos, incluindo algumas restrições impostas pelo sistema operacional, como um prefixo desconhecido ou caracteres inválidos.This can be for various reasons, including some restrictions that may be placed by the operating system, such as an unknown prefix or invalid characters. Observe que o nome e os prefixos comuns "Global" e "Local" diferenciam maiúsculas de minúsculas.Note that the name and common prefixes "Global" and "Local" are case-sensitive.

- ou --or-

Ocorreu outro erro.There was some other error. A propriedade HResult pode fornecer mais informações.The HResult property may provide more information.

Somente Windows: name especificou um namespace desconhecido.Windows only: name specified an unknown namespace. Confira mais informações em Nomes do objeto.See Object Names for more information.

O name é muito longo.The name is too long. As restrições de comprimento podem depender do sistema operacional ou da configuração.Length restrictions may depend on the operating system or configuration.

O mutex nomeado existe, mas o usuário não tem o acesso de segurança desejado.The named mutex exists, but the user does not have the desired security access.

Exemplos

O exemplo de código a seguir demonstra o comportamento de processo cruzado de um mutex nomeado com segurança de controle de acesso.The following code example demonstrates the cross-process behavior of a named mutex with access control security. O exemplo usa a OpenExisting(String) sobrecarga do método para testar a existência de um mutex nomeado.The example uses the OpenExisting(String) method overload to test for the existence of a named mutex.

Se o mutex não existir, ele será criado com a propriedade inicial e a segurança de controle de acesso que nega ao usuário atual o direito de usar o mutex, mas concede o direito de ler e alterar permissões no mutex.If the mutex does not exist, it is created with initial ownership and access control security that denies the current user the right to use the mutex, but grants the right to read and change permissions on the mutex.

Se você executar o exemplo compilado de duas janelas de comando, a segunda cópia gerará uma exceção de violação de acesso na chamada para OpenExisting(String) .If you run the compiled example from two command windows, the second copy will throw an access violation exception on the call to OpenExisting(String). A exceção é capturada e o exemplo usa a OpenExisting(String, MutexRights) sobrecarga do método para abrir o mutex com os direitos necessários para ler e alterar as permissões.The exception is caught, and the example uses the OpenExisting(String, MutexRights) method overload to open the mutex with the rights needed to read and change the permissions.

Depois que as permissões são alteradas, o mutex é aberto com os direitos necessários para inseri-lo e liberá-lo.After the permissions are changed, the mutex is opened with the rights required to enter and release it. Se você executar o exemplo compilado de uma terceira janela de comando, ele será executado usando as novas permissões.If you run the compiled example from a third command window, it runs using the new permissions.

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^ mutexName = L"MutexExample4";

      Mutex^ m = nullptr;
      bool doesNotExist = false;
      bool unauthorized = false;
      
      // The value of this variable is set by the mutex
      // constructor. It is true if the named system mutex was
      // created, and false if the named mutex already existed.
      //
      bool mutexWasCreated = false;

      // Attempt to open the named mutex.
      try
      {
         // Open the mutex with (MutexRights.Synchronize |
         // MutexRights.Modify), to enter and release the
         // named mutex.
         //
         m = Mutex::OpenExisting( mutexName );
      }
      catch ( WaitHandleCannotBeOpenedException^ ) 
      {
         Console::WriteLine( L"Mutex does not exist." );
         doesNotExist = true;
      }
      catch ( UnauthorizedAccessException^ ex ) 
      {
         Console::WriteLine( L"Unauthorized access: {0}", ex->Message );
         unauthorized = true;
      }

      // There are three cases: (1) The mutex does not exist.
      // (2) The mutex exists, but the current user doesn't
      // have access. (3) The mutex exists and the user has
      // access.
      //
      if ( doesNotExist )
      {
         // The mutex does not exist, so create it.
         // Create an access control list (ACL) that denies the
         // current user the right to enter or release the
         // mutex, but allows the right to read and change
         // security information for the mutex.
         //
         String^ user = String::Concat( Environment::UserDomainName, L"\\",
            Environment::UserName );
         MutexSecurity^ mSec = gcnew MutexSecurity;

         MutexAccessRule^ rule = gcnew MutexAccessRule( user,
            static_cast<MutexRights>(
               MutexRights::Synchronize |
               MutexRights::Modify),
            AccessControlType::Deny );
         mSec->AddAccessRule( rule );

         rule = gcnew MutexAccessRule( user,
            static_cast<MutexRights>(
               MutexRights::ReadPermissions |
                MutexRights::ChangePermissions),
            AccessControlType::Allow );
         mSec->AddAccessRule( rule );
         
         // Create a Mutex object that represents the system
         // mutex named by the constant 'mutexName', with
         // initial ownership for this thread, and with the
         // specified security access. The Boolean value that
         // indicates creation of the underlying system object
         // is placed in mutexWasCreated.
         //
         m = gcnew Mutex( true,mutexName, mutexWasCreated,mSec );
         
         // If the named system mutex 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 mutex. Otherwise, exit the program.
         //
         if ( mutexWasCreated )
         {
            Console::WriteLine( L"Created the mutex." );
         }
         else
         {
            Console::WriteLine( L"Unable to create the mutex." );
            return;
         }
      }
      else if ( unauthorized )
      {
         // Open the mutex to read and change the access control
         // security. The access control security defined above
         // allows the current user to do this.
         //
         try
         {
            m = Mutex::OpenExisting( mutexName,
               static_cast<MutexRights>(
                  MutexRights::ReadPermissions |
                  MutexRights::ChangePermissions) );
            
            // Get the current ACL. This requires
            // MutexRights.ReadPermissions.
            MutexSecurity^ mSec = m->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 mutex must
            // be removed.
            MutexAccessRule^ rule = gcnew MutexAccessRule( user,
               static_cast<MutexRights>(
                  MutexRights::Synchronize |
                  MutexRights::Modify),
               AccessControlType::Deny );
            mSec->RemoveAccessRule( rule );
            
            // Now grant the user the correct rights.
            //
            rule = gcnew MutexAccessRule( user,
               static_cast<MutexRights>(
                  MutexRights::Synchronize |
                  MutexRights::Modify),
               AccessControlType::Allow );
            mSec->AddAccessRule( rule );
            
            // Update the ACL. This requires
            // MutexRights.ChangePermissions.
            m->SetAccessControl( mSec );

            Console::WriteLine( L"Updated mutex security." );
            
            // Open the mutex with (MutexRights.Synchronize
            // | MutexRights.Modify), the rights required to
            // enter and release the mutex.
            //
            m = Mutex::OpenExisting( mutexName );
         }
         catch ( UnauthorizedAccessException^ ex ) 
         {
            Console::WriteLine(
               L"Unable to change permissions: {0}", ex->Message );
            return;
         }
      }
      
      // If this program created the mutex, it already owns
      // the mutex.
      //
      if ( !mutexWasCreated )
      {
         // Enter the mutex, and hold it until the program
         // exits.
         //
         try
         {
            Console::WriteLine( L"Wait for the mutex." );
            m->WaitOne();
            Console::WriteLine( L"Entered the mutex." );
         }
         catch ( UnauthorizedAccessException^ ex ) 
         {
            Console::WriteLine( L"Unauthorized access: {0}",
               ex->Message );
         }
      }

      Console::WriteLine( L"Press the Enter key to exit." );
      Console::ReadLine();
      m->ReleaseMutex();
      m->Dispose();
   }
};

int main()
{
   Example::Main();
}
using System;
using System.Threading;
using System.Security.AccessControl;

internal class Example
{
    internal static void Main()
    {
        const string mutexName = "MutexExample4";

        Mutex m = null;
        bool doesNotExist = false;
        bool unauthorized = false;

        // The value of this variable is set by the mutex
        // constructor. It is true if the named system mutex was
        // created, and false if the named mutex already existed.
        //
        bool mutexWasCreated = false;

        // Attempt to open the named mutex.
        try
        {
            // Open the mutex with (MutexRights.Synchronize |
            // MutexRights.Modify), to enter and release the
            // named mutex.
            //
            m = Mutex.OpenExisting(mutexName);
        }
        catch(WaitHandleCannotBeOpenedException)
        {
            Console.WriteLine("Mutex does not exist.");
            doesNotExist = true;
        }
        catch(UnauthorizedAccessException ex)
        {
            Console.WriteLine("Unauthorized access: {0}", ex.Message);
            unauthorized = true;
        }

        // There are three cases: (1) The mutex does not exist.
        // (2) The mutex exists, but the current user doesn't 
        // have access. (3) The mutex exists and the user has
        // access.
        //
        if (doesNotExist)
        {
            // The mutex does not exist, so create it.

            // Create an access control list (ACL) that denies the
            // current user the right to enter or release the 
            // mutex, but allows the right to read and change
            // security information for the mutex.
            //
            string user = Environment.UserDomainName + "\\"
                + Environment.UserName;
            MutexSecurity mSec = new MutexSecurity();

            MutexAccessRule rule = new MutexAccessRule(user, 
                MutexRights.Synchronize | MutexRights.Modify, 
                AccessControlType.Deny);
            mSec.AddAccessRule(rule);

            rule = new MutexAccessRule(user, 
                MutexRights.ReadPermissions | MutexRights.ChangePermissions,
                AccessControlType.Allow);
            mSec.AddAccessRule(rule);

            // Create a Mutex object that represents the system
            // mutex named by the constant 'mutexName', with
            // initial ownership for this thread, and with the
            // specified security access. The Boolean value that 
            // indicates creation of the underlying system object
            // is placed in mutexWasCreated.
            //
            m = new Mutex(true, mutexName, out mutexWasCreated, mSec);

            // If the named system mutex 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 mutex. Otherwise, exit the program.
            // 
            if (mutexWasCreated)
            {
                Console.WriteLine("Created the mutex.");
            }
            else
            {
                Console.WriteLine("Unable to create the mutex.");
                return;
            }
        }
        else if (unauthorized)
        {
            // Open the mutex to read and change the access control
            // security. The access control security defined above
            // allows the current user to do this.
            //
            try
            {
                m = Mutex.OpenExisting(mutexName, 
                    MutexRights.ReadPermissions | MutexRights.ChangePermissions);

                // Get the current ACL. This requires 
                // MutexRights.ReadPermissions.
                MutexSecurity mSec = m.GetAccessControl();
                
                string user = Environment.UserDomainName + "\\"
                    + Environment.UserName;

                // First, the rule that denied the current user 
                // the right to enter and release the mutex must
                // be removed.
                MutexAccessRule rule = new MutexAccessRule(user, 
                     MutexRights.Synchronize | MutexRights.Modify,
                     AccessControlType.Deny);
                mSec.RemoveAccessRule(rule);

                // Now grant the user the correct rights.
                // 
                rule = new MutexAccessRule(user, 
                    MutexRights.Synchronize | MutexRights.Modify,
                    AccessControlType.Allow);
                mSec.AddAccessRule(rule);

                // Update the ACL. This requires
                // MutexRights.ChangePermissions.
                m.SetAccessControl(mSec);

                Console.WriteLine("Updated mutex security.");

                // Open the mutex with (MutexRights.Synchronize 
                // | MutexRights.Modify), the rights required to
                // enter and release the mutex.
                //
                m = Mutex.OpenExisting(mutexName);
            }
            catch(UnauthorizedAccessException ex)
            {
                Console.WriteLine("Unable to change permissions: {0}",
                    ex.Message);
                return;
            }
        }

        // If this program created the mutex, it already owns
        // the mutex.
        //
        if (!mutexWasCreated)
        {
            // Enter the mutex, and hold it until the program
            // exits.
            //
            try
            {
                Console.WriteLine("Wait for the mutex.");
                m.WaitOne();
                Console.WriteLine("Entered the mutex.");
            }
            catch(UnauthorizedAccessException ex)
            {
                Console.WriteLine("Unauthorized access: {0}", ex.Message);
            }
        }

        Console.WriteLine("Press the Enter key to exit.");
        Console.ReadLine();
        m.ReleaseMutex();
        m.Dispose();
    }
}
Imports System.Threading
Imports System.Security.AccessControl

Friend Class Example

    <MTAThread> _
    Friend Shared Sub Main()
        Const mutexName As String = "MutexExample4"

        Dim m As Mutex = Nothing
        Dim doesNotExist as Boolean = False
        Dim unauthorized As Boolean = False

        ' The value of this variable is set by the mutex
        ' constructor. It is True if the named system mutex was
        ' created, and False if the named mutex already existed.
        '
        Dim mutexWasCreated As Boolean

        ' Attempt to open the named mutex.
        Try
            ' Open the mutex with (MutexRights.Synchronize Or
            ' MutexRights.Modify), to enter and release the
            ' named mutex.
            '
            m = Mutex.OpenExisting(mutexName)
        Catch ex As WaitHandleCannotBeOpenedException
            Console.WriteLine("Mutex 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 mutex does not exist.
        ' (2) The mutex exists, but the current user doesn't 
        ' have access. (3) The mutex exists and the user has
        ' access.
        '
        If doesNotExist Then
            ' The mutex does not exist, so create it.

            ' Create an access control list (ACL) that denies the
            ' current user the right to enter or release the 
            ' mutex, but allows the right to read and change
            ' security information for the mutex.
            '
            Dim user As String = Environment.UserDomainName _ 
                & "\" & Environment.UserName
            Dim mSec As New MutexSecurity()

            Dim rule As New MutexAccessRule(user, _
                MutexRights.Synchronize Or MutexRights.Modify, _
                AccessControlType.Deny)
            mSec.AddAccessRule(rule)

            rule = New MutexAccessRule(user, _
                MutexRights.ReadPermissions Or _
                MutexRights.ChangePermissions, _
                AccessControlType.Allow)
            mSec.AddAccessRule(rule)

            ' Create a Mutex object that represents the system
            ' mutex named by the constant 'mutexName', with
            ' initial ownership for this thread, and with the
            ' specified security access. The Boolean value that 
            ' indicates creation of the underlying system object
            ' is placed in mutexWasCreated.
            '
            m = New Mutex(True, mutexName, mutexWasCreated, mSec)

            ' If the named system mutex 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 mutex. Otherwise, exit the program.
            ' 
            If mutexWasCreated Then
                Console.WriteLine("Created the mutex.")
            Else
                Console.WriteLine("Unable to create the mutex.")
                Return
            End If

        ElseIf unauthorized Then

            ' Open the mutex to read and change the access control
            ' security. The access control security defined above
            ' allows the current user to do this.
            '
            Try
                m = Mutex.OpenExisting(mutexName, _
                    MutexRights.ReadPermissions Or _
                    MutexRights.ChangePermissions)

                ' Get the current ACL. This requires 
                ' MutexRights.ReadPermissions.
                Dim mSec As MutexSecurity = m.GetAccessControl()
                
                Dim user As String = Environment.UserDomainName _ 
                    & "\" & Environment.UserName

                ' First, the rule that denied the current user 
                ' the right to enter and release the mutex must
                ' be removed.
                Dim rule As New MutexAccessRule(user, _
                    MutexRights.Synchronize Or MutexRights.Modify, _
                    AccessControlType.Deny)
                mSec.RemoveAccessRule(rule)

                ' Now grant the user the correct rights.
                ' 
                rule = New MutexAccessRule(user, _
                    MutexRights.Synchronize Or MutexRights.Modify, _
                    AccessControlType.Allow)
                mSec.AddAccessRule(rule)

                ' Update the ACL. This requires
                ' MutexRights.ChangePermissions.
                m.SetAccessControl(mSec)

                Console.WriteLine("Updated mutex security.")

                ' Open the mutex with (MutexRights.Synchronize 
                ' Or MutexRights.Modify), the rights required to
                ' enter and release the mutex.
                '
                m = Mutex.OpenExisting(mutexName)

            Catch ex As UnauthorizedAccessException
                Console.WriteLine("Unable to change permissions: {0}", _
                    ex.Message)
                Return
            End Try

        End If

        ' If this program created the mutex, it already owns
        ' the mutex.
        '
        If Not mutexWasCreated Then
            ' Enter the mutex, and hold it until the program
            ' exits.
            '
            Try
                Console.WriteLine("Wait for the mutex.")
                m.WaitOne()
                Console.WriteLine("Entered the mutex.")
            Catch ex As UnauthorizedAccessException
                Console.WriteLine("Unauthorized access: {0}", _
                    ex.Message)
            End Try
        End If

        Console.WriteLine("Press the Enter key to exit.")
        Console.ReadLine()
        m.ReleaseMutex()
        m.Dispose()
    End Sub 
End Class 

Comentários

O name pode ser prefixado com Global\ or Local\ para especificar um namespace.The name may be prefixed with Global\ or Local\ to specify a namespace. Quando o Global namespace é especificado, o objeto de sincronização pode ser compartilhado com qualquer processo no sistema.When the Global namespace is specified, the synchronization object may be shared with any processes on the system. Quando o Local namespace é especificado, que também é o padrão quando nenhum namespace é especificado, o objeto de sincronização pode ser compartilhado com processos na mesma sessão.When the Local namespace is specified, which is also the default when no namespace is specified, the synchronization object may be shared with processes in the same session. No Windows, uma sessão é uma sessão de logon e os serviços normalmente são executados em uma sessão não interativa diferente.On Windows, a session is a login session, and services typically run in a different non-interactive session. Em sistemas operacionais semelhantes ao Unix, cada shell tem sua própria sessão.On Unix-like operating systems, each shell has its own session. Os objetos de sincronização de sessão local podem ser apropriados para sincronizar entre processos com uma relação pai/filho em que todos eles são executados na mesma sessão.Session-local synchronization objects may be appropriate for synchronizing between processes with a parent/child relationship where they all run in the same session. Para obter mais informações sobre nomes de objetos Synchornization no Windows, consulte nomes de objetos.For more information about synchornization object names on Windows, see Object Names.

Se um objeto de sincronização do tipo solicitado existir no namespace, o objeto de sincronização existente será aberto.If a synchronization object of the requested type exists in the namespace, the existing synchronization object is opened. Se um objeto de sincronização não existir no namespace ou se um objeto de sincronização de um tipo diferente existir no namespace, um WaitHandleCannotBeOpenedException será gerado.If a synchronization object does not exist in the namespace, or a synchronization object of a different type exists in the namespace, a WaitHandleCannotBeOpenedException is thrown.

O rights parâmetro deve incluir o MutexRights.Synchronize sinalizador para permitir que os threads aguardem o mutex e o MutexRights.Modify sinalizador para permitir que os threads chamem o ReleaseMutex método.The rights parameter must include the MutexRights.Synchronize flag to allow threads to wait on the mutex, and the MutexRights.Modify flag to allow threads to call the ReleaseMutex method.

O OpenExisting método tenta abrir um mutex nomeado existente.The OpenExisting method tries to open an existing named mutex. Para criar o mutex do sistema quando ele ainda não existir, use um dos Mutex construtores que tem um name parâmetro.To create the system mutex when it does not already exist, use one of the Mutex constructors that has a name parameter.

Várias chamadas para esse método que usam o mesmo valor para não name retornam necessariamente o mesmo Mutex objeto, embora os objetos retornados representem o mesmo mutex de sistema nomeado.Multiple calls to this method that use the same value for name do not necessarily return the same Mutex object, even though the objects that are returned represent the same named system mutex.

Esse método não solicita a propriedade do mutex.This method does not request ownership of the mutex.

Aplica-se a