internal static Task<TResult> FromAsyncImpl(Func<AsyncCallback, object, IAsyncResult> beginMethod, Func<IAsyncResult, TResult> endMethod, object state, TaskCreationOptions creationOptions)
{
    AsyncCallback callback = null;
    if (beginMethod == null)
    {
        throw new ArgumentNullException("beginMethod");
    }
    if (endMethod == null)
    {
        throw new ArgumentNullException("endMethod");
    }
    TaskFactory.CheckFromAsyncOptions(creationOptions, true);
    TaskCompletionSource<TResult> tcs = new TaskCompletionSource<TResult>(state, creationOptions);
    try
    {
        if (callback == null)
        {
            callback = delegate (IAsyncResult iar) {
                TaskFactory<TResult>.FromAsyncCoreLogic(iar, endMethod, tcs);
            };
        }
        beginMethod(callback, state);
    }
    catch
    {
        tcs.TrySetResult(default(TResult));
        throw;
    }
    return tcs.Task;
}

private static void FromAsyncCoreLogic(IAsyncResult iar, Func<IAsyncResult, TResult> endMethod, TaskCompletionSource<TResult> tcs)
{
    Exception exception = null;
    OperationCanceledException exception2 = null;
    TResult result = default(TResult);
    try
    {
        result = endMethod(iar);
    }
    catch (OperationCanceledException exception3)
    {
        exception2 = exception3;
    }
    catch (Exception exception4)
    {
        exception = exception4;
    }
    finally
    {
        if (exception2 != null)
        {
            tcs.TrySetCanceled();
        }
        else if (exception != null)
        {
            if (tcs.TrySetException(exception) && (exception is ThreadAbortException))
            {
                tcs.Task.m_contingentProperties.m_exceptionsHolder.MarkAsHandled(false);
            }
        }
        else
        {
            tcs.TrySetResult(result);
        }
    }
}