How to dispose unmanaged resource manually?

Question

I am using some unmanaged code like-

 [DllImport("wininet.dll")]
    private extern static bool InternetGetConnectedState(out int Description, int ReservedValue);
    //Creating a function that uses the API function...
    public static bool IsConnectedToInternet() {
        int Desc;
        return InternetGetConnectedState(out Desc, 0);
    }

Any suggestions on how I can dispose/cleanup this extern static object when I call Dispose?

score 7 · Accepted Answer · answered Jan 18 '11 at 08:52

7

The thing you think is an 'extern static object' is not an object at all, it's just a set of instructions to the compiler/runtime about how to find a function in a DLL.

As Sander says, there's nothing to clean up.

answered Jan 18 '11 at 08:52

Will Dean

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score 4 · Answer 2 · answered Jan 18 '11 at 08:47

4

You do not have any handles to unmanaged resources here. There is nothing to clean up.

answered Jan 18 '11 at 08:47

Sander

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score 3 · Answer 3 · answered Jan 18 '11 at 08:56

It depends if you can get a pointer, as an example

[DllImport("advapi32.dll", SetLastError = true)]
static extern bool LogonUser(string principal, string authority, string password, LogonSessionType logonType, LogonProvider logonProvider, out IntPtr token);

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool CloseHandle(IntPtr handle);

public void DoSomething() {
    IntPtr token = IntPtr.Zero;
    WindowsImpersonationContext user = null;
    try {
        bool loggedin = LogonUser((string)parameters[1], (string)parameters[2], (string)parameters[3], LogonSessionType.Interactive, LogonProvider.Default, out token);
        if (loggedin) {
            WindowsIdentity id = new WindowsIdentity(token);
            user = id.Impersonate();
        }
    } catch (Exception ex) {

    } finally {
        if (user != null) {
            user.Undo();
        }
        if (token != IntPtr.Zero) {
            CloseHandle(token);
        }
    }
}

How to dispose unmanaged resource manually?

3 Answers3