Marshal.ZeroFreeGlobalAllocAnsi-Methode: (IntPtr)

 

Veröffentlicht: Oktober 2016

Hinweis

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Gibt einen nicht verwalteten Zeichenfolgenzeiger frei, der mit der SecureStringToGlobalAllocAnsi-Methode reserviert wurde.

Namespace:   System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)

Syntax

[SecurityCriticalAttribute]
public static void ZeroFreeGlobalAllocAnsi(
    IntPtr s
)

public:
[SecurityCriticalAttribute]
static void ZeroFreeGlobalAllocAnsi(
    IntPtr s
)

[<SecurityCriticalAttribute>]
static member ZeroFreeGlobalAllocAnsi : 
        s:nativeint -> unit

<SecurityCriticalAttribute>
Public Shared Sub ZeroFreeGlobalAllocAnsi (
    s As IntPtr
)

Parameter

• s
  Type: System.IntPtr

  Die Adresse der nicht verwalteten Zeichenfolge, die freigegeben werden soll.

Hinweise

Die ZeroFreeGlobalAllocAnsi Methode zuerst Nullen und dann freigegeben nicht verwalteten Speicher, der belegt wurde mithilfe der SecureStringToGlobalAllocAnsi Methode.

Beispiele

Im folgenden Beispiel wird die SecureStringToGlobalAllocAnsi gemarshallt und Entschlüsseln des Inhalts der Methode ein SecureString Objekt, das einen nicht verwalteten Speicherblock. Es verwendet dann die ZeroFreeGlobalAllocAnsi Methode, die nicht verwaltete Block mit Nullen gefüllt und freigegeben.

using System;
using System.Runtime.InteropServices;
using System.Security;

class Example
{
    static void Main()
    {
        IntPtr unmanagedRef = IntPtr.Zero;

        // Ask the user for a password.
        Console.Write("Please enter your password: ");
        SecureString passWord = GetPassword();

        Console.WriteLine("Copying and decrypting the string to unmanaged memory...");
        // Copy the Secure string to unmanaged memory (and decrypt it).
        unmanagedRef = Marshal.SecureStringToGlobalAllocAnsi(passWord);
        passWord.Dispose();

        if (unmanagedRef != IntPtr.Zero) {
            Console.WriteLine("Zeroing out unmanaged memory...");
            Marshal.ZeroFreeGlobalAllocAnsi(unmanagedRef);
        }
        Console.WriteLine("Done.");
    }

    public static SecureString GetPassword()
    {
        SecureString password = new SecureString();

        // get the first character of the password
        ConsoleKeyInfo nextKey = Console.ReadKey(true);

        while (nextKey.Key != ConsoleKey.Enter) {
            if (nextKey.Key == ConsoleKey.Backspace) {
                if (password.Length > 0) {
                    password.RemoveAt(password.Length - 1);

                    // erase the last * as well
                    Console.Write(nextKey.KeyChar);
                    Console.Write(" ");
                    Console.Write(nextKey.KeyChar);
                }
            }
            else {
                password.AppendChar(nextKey.KeyChar);
                Console.Write("*");
            }

            nextKey = Console.ReadKey(true);
        }
        Console.WriteLine();

        // lock the password down
        password.MakeReadOnly();
        return password;
    }
}
// The example displays output like the following:
//       Please enter your password: ********
//       Copying and decrypting the string to unmanaged memory...
//       Zeroing out unmanaged memory...
//       Done.

Imports System
Imports System.Runtime.InteropServices
Imports System.Security

Module Example
    Sub Main()
        Dim unmanagedRef As IntPtr

        ' Ask the user for a password.
        Console.Write("Please enter your password: ")
        Dim passWord As SecureString = GetPassword()

        Console.WriteLine("Copying and decrypting the string to unmanaged memory...")
        ' Copy the Secure string to unmanaged memory (and decrypt it).
        unmanagedRef = Marshal.SecureStringToGlobalAllocAnsi(passWord)
        passWord.Dispose()

        If unmanagedRef <> IntPtr.Zero Then
            Console.WriteLine("Zeroing out unmanaged memory...")
            Marshal.ZeroFreeGlobalAllocAnsi(unmanagedRef)
        End If
        Console.WriteLine("Done.")
    End Sub

    Function GetPassword() As SecureString
        Dim password As New SecureString()

        ' get the first character of the password
        Dim nextKey As ConsoleKeyInfo = Console.ReadKey(True)

        While nextKey.Key <> ConsoleKey.Enter
            If nextKey.Key = ConsoleKey.BackSpace Then
                If password.Length > 0 Then
                    password.RemoveAt(password.Length - 1)

                    ' Erase the last * as well.
                    Console.Write(nextKey.KeyChar)
                    Console.Write(" ")
                    Console.Write(nextKey.KeyChar)
                End If
            Else
                password.AppendChar(nextKey.KeyChar)
                Console.Write("*")
            End If

            nextKey = Console.ReadKey(True)
        End While
        Console.WriteLine()

        ' lock the password down
        password.MakeReadOnly()
        Return password
    End Function
End Module
' The example displays output like the following:
'       Please enter your password: ********
'       Copying and decrypting the string to unmanaged memory...
'       Zeroing out unmanaged memory...
'       Done.

Sicherheit

SecurityCriticalAttribute

requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Versionsinformationen

Universelle Windows-Plattform
Verfügbar seit 8
.NET Framework
Verfügbar seit 2.0
Portierbare Klassenbibliothek
Unterstützt in: portierbare .NET-Plattformen
Windows Phone
Verfügbar seit 8.1

Siehe auch

Marshal-Klasse
System.Runtime.InteropServices-Namespace

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