WIP: Added packing of AR and TAR

AMWD.Common/Packing/Ar/ArWriter.cs

@@ -0,0 +1,147 @@
+using System;
+using System.IO;
+using System.Text;
+
+namespace AMWD.Common.Packing.Ar
+{
+	/// <summary>
+	/// Writes UNIX ar (archive) files in the GNU format.
+	/// </summary>
+	/// <remarks>
+	/// Copied from <a href="https://github.com/ygoe/DotnetMakeDeb/blob/v1.1.0/DotnetMakeDeb/Ar/ArWriter.cs"/>
+	/// </remarks>
+	public class ArWriter
+	{
+		// Source: http://en.wikipedia.org/wiki/Ar_%28Unix%29
+
+		private readonly Stream outStream;
+		private static readonly DateTime unixEpoch = new(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
+
+		/// <summary>
+		/// Initialises a new instance of the <see cref="ArWriter"/> class.
+		/// </summary>
+		/// <param name="outStream">The stream to write the archive to.</param>
+		public ArWriter(Stream outStream)
+		{
+			if (!outStream.CanWrite)
+				throw new ArgumentException("Stream not writable", nameof(outStream));
+
+			this.outStream = outStream;
+			Initialize();
+		}
+
+		/// <summary>
+		/// Writes a file from disk to the archive.
+		/// </summary>
+		/// <param name="fileName">The name of the file to copy.</param>
+		/// <param name="userId">The user ID of the file in the archive.</param>
+		/// <param name="groupId">The group ID of the file in the archive.</param>
+		/// <param name="mode">The mode of the file in the archive (decimal).</param>
+		public void WriteFile(string fileName, int userId = 0, int groupId = 0, int mode = 33188 /* 0100644 */)
+		{
+			var fi = new FileInfo(fileName);
+
+			using var fs = File.OpenRead(fileName);
+			WriteFile(fs, fi.Name, fi.LastWriteTimeUtc, userId, groupId, mode);
+		}
+
+		/// <summary>
+		/// Writes a file from a Stream to the archive.
+		/// </summary>
+		/// <param name="stream">The stream to read the file contents from.</param>
+		/// <param name="fileName">The name of the file in the archive.</param>
+		/// <param name="modifyTime">The last modification time of the file in the archive.</param>
+		/// <param name="userId">The user ID of the file in the archive.</param>
+		/// <param name="groupId">The group ID of the file in the archive.</param>
+		/// <param name="mode">The mode of the file in the archive (decimal).</param>
+		public void WriteFile(Stream stream, string fileName, DateTime modifyTime, int userId = 0, int groupId = 0, int mode = 33188 /* 0100644 */)
+		{
+			// Write file header
+			WriteFileHeader(fileName, modifyTime, userId, groupId, mode, stream.Length);
+
+			// Write file contents
+			stream.CopyTo(outStream);
+
+			// Align to even offsets, pad with LF bytes
+			if ((outStream.Position % 2) != 0)
+			{
+				byte[] bytes = new byte[] { 0x0A };
+				outStream.Write(bytes, 0, 1);
+			}
+		}
+
+		/// <summary>
+		/// Writes the archive header.
+		/// </summary>
+		private void Initialize()
+		{
+			WriteAsciiString("!<arch>\n");
+		}
+
+		/// <summary>
+		/// Writes a file header.
+		/// </summary>
+		private void WriteFileHeader(string fileName, DateTime modifyTime, int userId, int groupId, int mode, long fileSize)
+		{
+			// File name
+			if (fileName.Length > 16)
+				throw new ArgumentException("Long file names are not supported.");
+
+			WriteAsciiString(fileName.PadRight(16, ' '));
+
+			// File modification timestamp
+			int unixTime = (int)(modifyTime - unixEpoch).TotalSeconds;
+			WriteAsciiString(unixTime.ToString().PadRight(12, ' '));
+
+			// User ID
+			if (userId >= 0)
+			{
+				WriteAsciiString(userId.ToString().PadRight(6, ' '));
+			}
+			else
+			{
+				WriteAsciiString("      ");
+			}
+
+			// Group ID
+			if (groupId >= 0)
+			{
+				WriteAsciiString(groupId.ToString().PadRight(6, ' '));
+			}
+			else
+			{
+				WriteAsciiString("      ");
+			}
+
+			// File mode
+			if (mode >= 0)
+			{
+				WriteAsciiString(Convert.ToString(mode, 8).PadRight(8, ' '));
+			}
+			else
+			{
+				WriteAsciiString("        ");
+			}
+
+			// File size in bytes
+			if (fileSize < 0 || 10000000000 <= fileSize)
+				throw new ArgumentOutOfRangeException("Invalid file size."); // above 9.32 GB
+
+			WriteAsciiString(fileSize.ToString().PadRight(10, ' '));
+
+			// File magic
+			byte[] bytes = new byte[] { 0x60, 0x0A };
+			outStream.Write(bytes, 0, 2);
+		}
+
+		/// <summary>
+		/// Writes a string using ASCII encoding.
+		/// </summary>
+		/// <param name="str">The string to write to the output stream.</param>
+		private void WriteAsciiString(string str)
+		{
+			byte[] bytes = Encoding.ASCII.GetBytes(str);
+			outStream.Write(bytes, 0, bytes.Length);
+		}
+	}
+}