Marshal.ZeroFreeGlobalAllocAnsi(IntPtr) Methode

Definition

Namespace:

System.Runtime.InteropServices

Assembly:

System.Runtime.InteropServices.dll

Assembly:

mscorlib.dll

Assembly:

netstandard.dll

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

public:
 static void ZeroFreeGlobalAllocAnsi(IntPtr s);

[System.Security.SecurityCritical]
public static void ZeroFreeGlobalAllocAnsi (IntPtr s);

public static void ZeroFreeGlobalAllocAnsi (IntPtr s);

[<System.Security.SecurityCritical>]
static member ZeroFreeGlobalAllocAnsi : nativeint -> unit

static member ZeroFreeGlobalAllocAnsi : nativeint -> unit

Public Shared Sub ZeroFreeGlobalAllocAnsi (s As IntPtr)

Parameter

s

IntPtr

nativeint

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

Attribute

SecurityCriticalAttribute

Beispiele

Im folgenden Beispiel wird die SecureStringToGlobalAllocAnsi Methode verwendet, um den Inhalt eines SecureString Objekts zu einem Block des nicht verwalteten Arbeitsspeichers zu erregen und zu entschlüsseln. Anschließend wird die ZeroFreeGlobalAllocAnsi Methode zum Nullen verwendet und der nicht verwaltete Block entsorgt.

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.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.

Hinweise

Die ZeroFreeGlobalAllocAnsi Methode nullt zuerst aus und gibt dann nicht verwalteten Arbeitsspeicher frei, der mithilfe der SecureStringToGlobalAllocAnsi Methode zugewiesen wurde.