// Copyright (c) Microsoft Open Technologies, Inc.
// All Rights Reserved
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
// WITHOUT LIMITATION ANY IMPLIED WARRANTIES OR CONDITIONS OF
// TITLE, FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABLITY OR
// NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing
// permissions and limitations under the License.

using System;
using System.Diagnostics;

namespace Microsoft.AspNet.Security.DataProtection.Util
{
    /// <summary>
    /// Defines helper methods for working with fixed expression blocks.
    /// </summary>
    internal static class ByteArrayExtensions
    {
        private static readonly byte[] _dummyBuffer = new byte[1];

        // Since the 'fixed' keyword turns a zero-length array into a pointer, we need
        // to make sure we're always providing a buffer of length >= 1 so that the
        // p/invoke methods we pass the pointers to don't see a null pointer. Callers
        // are still responsible for passing a proper length to the p/invoke routines.
        public static byte[] AsFixed(this byte[] buffer)
        {
            Debug.Assert(buffer != null);
            return (buffer.Length != 0) ? buffer : _dummyBuffer;
        }
    }
}