src/Lucene.Net/Support/IO/FileStreamOptions.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.IO;
#nullable enable

namespace Lucene.Net.Support.IO
{
    /// <summary>
    /// Poached from dotnet runtime. This is only available on .NET 6+, so we just made a copy to
    /// make passing parameters easier.
    /// </summary>
    internal sealed class FileStreamOptions
    {
        //private FileMode _mode = FileMode.Open;
        private FileAccess _access = FileAccess.Write; // Changed from Read - we are creating a new file for writing
        private FileShare _share = FileShare.Read;
        private FileOptions _options;
        //private long _preallocationSize;
        private int _bufferSize = 8196; // NOTE: This is the default buffer size in Java's BufferedOutputStream

        ///// <summary>
        ///// One of the enumeration values that determines how to open or create the file.
        ///// </summary>
        ///// <exception cref="T:System.ArgumentOutOfRangeException">When <paramref name="value" /> contains an invalid value.</exception>
        //public FileMode Mode
        //{
        //    get => _mode;
        //    set
        //    {
        //        if (value < FileMode.CreateNew || value > FileMode.Append)
        //        {
        //            throw new ArgumentOutOfRangeException(nameof(value), "Enum value was out of legal range.");
        //        }

        //        _mode = value;
        //    }
        //}

        /// <summary>
        /// A bitwise combination of the enumeration values that determines how the file can be accessed by the <see cref="FileStream" /> object. This also determines the values returned by the <see cref="System.IO.FileStream.CanRead" /> and <see cref="System.IO.FileStream.CanWrite" /> properties of the <see cref="FileStream" /> object.
        /// </summary>
        /// <exception cref="T:System.ArgumentOutOfRangeException">When <paramref name="value" /> contains an invalid value.</exception>
        public FileAccess Access
        {
            get => _access;
            set
            {
                if (value < FileAccess.Read || value > FileAccess.ReadWrite)
                {
                    throw new ArgumentOutOfRangeException(nameof(value), "Enum value was out of legal range.");
                }

                _access = value;
            }
        }

        /// <summary>
        /// A bitwise combination of the enumeration values that determines how the file will be shared by processes. The default value is <see cref="System.IO.FileShare.Read" />.
        /// </summary>
        /// <exception cref="T:System.ArgumentOutOfRangeException">When <paramref name="value" /> contains an invalid value.</exception>
        public FileShare Share
        {
            get => _share;
            set
            {
                // don't include inheritable in our bounds check for share
                FileShare tempshare = value & ~FileShare.Inheritable;
                if (tempshare < FileShare.None || tempshare > (FileShare.ReadWrite | FileShare.Delete))
                {
                    throw new ArgumentOutOfRangeException(nameof(value), "Enum value was out of legal range.");
                }

                _share = value;
            }
        }

        /// <summary>
        /// A bitwise combination of the enumeration values that specifies additional file options. The default value is <see cref="System.IO.FileOptions.None" />, which indicates synchronous IO.
        /// </summary>
        /// <exception cref="T:System.ArgumentOutOfRangeException">When <paramref name="value" /> contains an invalid value.</exception>
        public FileOptions Options
        {
            get => _options;
            set
            {
                // NOTE: any change to FileOptions enum needs to be matched here in the error validation
                if (value != FileOptions.None && (value & ~(FileOptions.WriteThrough | FileOptions.Asynchronous | FileOptions.RandomAccess | FileOptions.DeleteOnClose | FileOptions.SequentialScan | FileOptions.Encrypted | (FileOptions)0x20000000 /* NoBuffering */)) != 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(value), "Enum value was out of legal range.");
                }

                _options = value;
            }
        }

        ///// <summary>
        ///// The initial allocation size in bytes for the file. A positive value is effective only when a regular file is being created, overwritten, or replaced.
        ///// Negative values are not allowed.
        ///// In other cases (including the default 0 value), it's ignored.
        ///// </summary>
        ///// <exception cref="T:System.ArgumentOutOfRangeException">When <paramref name="value" /> is negative.</exception>
        //public long PreallocationSize
        //{
        //    get => _preallocationSize;
        //    set => _preallocationSize = value >= 0 ? value : throw new ArgumentOutOfRangeException(nameof(value), "Non-negative number required.");
        //}

        /// <summary>
        /// The size of the buffer used by <see cref="FileStream" /> for buffering. The default buffer size is 4096.
        /// 0 or 1 means that buffering should be disabled. Negative values are not allowed.
        /// </summary>
        /// <exception cref="T:System.ArgumentOutOfRangeException">When <paramref name="value" /> is negative.</exception>
        public int BufferSize
        {
            get => _bufferSize;
            set => _bufferSize = value >= 0 ? value : throw new ArgumentOutOfRangeException(nameof(value), "Non-negative number required.");
        }
    }
}