WIP: Added packing of AR and TAR

2023-03-13 10:08:50 +01:00
parent e8a1378f60
commit 7cd5358ac8
18 changed files with 2071 additions and 4 deletions
--- a/AMWD.Common/Packing/Ar/ArReader.cs
+++ b/AMWD.Common/Packing/Ar/ArReader.cs
@@ -0,0 +1,180 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+
+namespace AMWD.Common.Packing.Ar
+{
+	/// <summary>
+	/// Reads UNIX ar (archive) files in the GNU format.
+	/// </summary>
+	public class ArReader
+	{
+		// Source: http://en.wikipedia.org/wiki/Ar_%28Unix%29
+
+		private readonly Stream inStream;
+		private readonly List<ArFileInfoExtended> files = new();
+		private readonly long streamStartPosition;
+
+		private static readonly DateTime unixEpoch = new(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ArReader"/> class.
+		/// </summary>
+		/// <param name="inStream">The stream to read the archive from.</param>
+		public ArReader(Stream inStream)
+		{
+			if (!inStream.CanRead || !inStream.CanSeek)
+				throw new ArgumentException("Stream not readable or seekable", nameof(inStream));
+
+			streamStartPosition = inStream.Position;
+			this.inStream = inStream;
+
+			Initialize();
+		}
+
+		/// <summary>
+		/// Returns a list with all filenames of the archive.
+		/// </summary>
+		public IEnumerable<string> GetFileList()
+		{
+			return files.Select(fi => fi.FileName).ToList();
+		}
+
+		/// <summary>
+		/// Returns the file info of a specific file in the archive.
+		/// </summary>
+		/// <param name="fileName">The name of the specific file.</param>
+		public ArFileInfo GetFileInfo(string fileName)
+		{
+			return files
+				.Where(fi => fi.FileName == fileName)
+				.Select(fi => new ArFileInfo
+				{
+					FileName = fi.FileName,
+					FileSize = fi.FileSize,
+					GroupId = fi.GroupId,
+					Mode = fi.Mode,
+					ModifyTime = fi.ModifyTime,
+					UserId = fi.UserId
+				})
+				.FirstOrDefault();
+		}
+
+		/// <summary>
+		/// Reads a file from the archive into a stream.
+		/// </summary>
+		/// <param name="fileName">The file name in the archive.</param>
+		/// <param name="outStream">The output stream.</param>
+		public void ReadFile(string fileName, Stream outStream)
+		{
+			if (!outStream.CanWrite)
+				throw new ArgumentException("Stream not writable", nameof(outStream));
+
+			var info = files.Where(fi => fi.FileName == fileName).FirstOrDefault();
+			if (info == null)
+				return;
+
+			long bytesToRead = info.FileSize;
+			byte[] buffer = new byte[1024 * 1024];
+
+			inStream.Seek(info.DataPosition, SeekOrigin.Begin);
+			while (bytesToRead > 0)
+			{
+				int readCount = (int)Math.Min(bytesToRead, buffer.Length);
+				inStream.Read(buffer, 0, readCount);
+				outStream.Write(buffer, 0, readCount);
+
+				bytesToRead -= readCount;
+			}
+			inStream.Seek(streamStartPosition, SeekOrigin.Begin);
+		}
+
+		/// <summary>
+		/// Reads a fie from the archive and saves it to disk.
+		/// </summary>
+		/// <param name="fileName">The file name in the archive.</param>
+		/// <param name="destinationPath">The destination path on disk.</param>
+		public void ReadFile(string fileName, string destinationPath)
+		{
+			var info = files.Where(fi => fi.FileName == fileName).FirstOrDefault();
+			if (info == null)
+				return;
+
+			using (var fs = File.OpenWrite(destinationPath))
+			{
+				ReadFile(fileName, fs);
+			}
+			File.SetLastWriteTimeUtc(destinationPath, info.ModifyTime);
+		}
+
+		private void Initialize()
+		{
+			// Reset stream
+			inStream.Seek(streamStartPosition, SeekOrigin.Begin);
+
+			// Read header
+			string header = ReadAsciiString(8);
+			if (header != "!<arch>\n")
+				throw new FormatException("The file stream is no archive");
+
+			// Create file list
+			while (inStream.Position < inStream.Length)
+			{
+				var info = ReadFileHeader();
+				files.Add(info);
+
+				// Move stream behind file content
+				inStream.Seek(info.FileSize, SeekOrigin.Current);
+
+				// Align to even offsets (padded with LF bytes)
+				if (inStream.Position % 2 != 0)
+					inStream.Seek(1, SeekOrigin.Current);
+			}
+
+			// Reset stream
+			inStream.Seek(streamStartPosition, SeekOrigin.Begin);
+		}
+
+		private string ReadAsciiString(int byteCount)
+		{
+			byte[] buffer = new byte[byteCount];
+			inStream.Read(buffer, 0, byteCount);
+			return Encoding.ASCII.GetString(buffer);
+		}
+
+		private ArFileInfoExtended ReadFileHeader()
+		{
+			long startPosition = inStream.Position;
+
+			string fileName = ReadAsciiString(16).Trim();
+
+			int.TryParse(ReadAsciiString(12).Trim(), out int unixTimestamp);
+			int.TryParse(ReadAsciiString(6).Trim(), out int userId);
+			int.TryParse(ReadAsciiString(6).Trim(), out int groupId);
+			int mode = Convert.ToInt32(ReadAsciiString(8).Trim(), 8);
+
+			long.TryParse(ReadAsciiString(10).Trim(), out long fileSize);
+
+			// file magic
+			byte[] magic = new byte[2];
+			inStream.Read(magic, 0, magic.Length);
+
+			if (magic[0] != 0x60 || magic[1] != 0x0A)
+				throw new FormatException("Invalid file magic");
+
+			return new ArFileInfoExtended
+			{
+				HeaderPosition = startPosition,
+				DataPosition = inStream.Position,
+				FileName = fileName,
+				ModifyTime = unixEpoch.AddSeconds(unixTimestamp),
+				UserId = userId,
+				GroupId = groupId,
+				Mode = mode,
+				FileSize = fileSize
+			};
+		}
+	}
+}