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andrewlockandrewlock
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Using tar with .NET
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‎UsingTarWithDotnet/Program.cs‎

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using System.Formats.Tar;
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using System.Globalization;
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using System.IO.Compression;
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if (args.Length < 1)
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{
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return PrintUsage();
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}
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if (args[0] == "--compress" && args.Length == 3)
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{
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var destination = args[1];
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var sourceDir = args[2];
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CreateTar(destination, sourceDir);
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}
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else if (args[0] == "--extract" && args.Length == 3)
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{
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var sourceTar = args[1];
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var destinationDir = args[2];
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ExtractTar(sourceTar, destinationDir);
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}
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else if (args[0] == "--single" && args.Length == 4)
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{
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var sourceTar = args[1];
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var pathInTar = args[2];
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var output = args[3];
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ExtractSingle(sourceTar, pathInTar, output);
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}
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else if (args[0] == "--list" && args.Length == 2)
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{
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var sourceTar = args[1];
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List(sourceTar);
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}
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else
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{
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return PrintUsage();
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}
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return 0;
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void CreateTar(string dest, string src)
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{
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Console.WriteLine($"Creating Tar file: '{dest}' from path '{src}");
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// Throws if the destination file exists
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using FileStream fs = new(dest, FileMode.CreateNew, FileAccess.Write);
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using GZipStream gz = new(fs, CompressionMode.Compress, leaveOpen: true);
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TarFile.CreateFromDirectory(src, gz, includeBaseDirectory: false);
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Console.WriteLine("Done");
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}
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void ExtractTar(string sourceTar, string dest)
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{
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Console.WriteLine($"Expanding Tar file: '{sourceTar}' to directory '{dest}");
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// Throws if the file does not exist
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using FileStream fs = new(sourceTar, FileMode.Open, FileAccess.Read);
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using GZipStream gz = new(fs, CompressionMode.Decompress, leaveOpen: true);
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TarFile.ExtractToDirectory(gz, dest, overwriteFiles: false);
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Console.WriteLine("Done");
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}
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void ExtractSingle(string sourceTar, string pathInTar, string destination)
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{
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Console.WriteLine($"Looking for '{pathInTar}' in file: '{sourceTar}'");
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// read the tar and extract a single file
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using FileStream fs = new(sourceTar, FileMode.Open, FileAccess.Read);
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using GZipStream gz = new(fs, CompressionMode.Decompress, leaveOpen: true);
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using var reader = new TarReader(gz, leaveOpen: true);
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while (reader.GetNextEntry() is { } entry)
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{
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if (entry.Name == pathInTar)
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{
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Console.WriteLine($"Found '{pathInTar}', extracting to '{destination}");
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entry.ExtractToFile(destination, overwrite: false);
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return;
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}
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}
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Console.WriteLine("Could not extract path - not found");
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}
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void List(string sourceTar)
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{
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Console.WriteLine($"Reading '{sourceTar}'");
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// read the tar and loop through the entries
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using FileStream fs = new(sourceTar, FileMode.Open, FileAccess.Read);
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using GZipStream gz = new(fs, CompressionMode.Decompress, leaveOpen: true);
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using var reader = new TarReader(gz, leaveOpen: true);
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while (reader.GetNextEntry() is { } entry)
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{
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// Get the file descriptor
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char type = entry.EntryType switch
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{
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TarEntryType.Directory => 'd',
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TarEntryType.HardLink => 'h',
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TarEntryType.SymbolicLink => 'l',
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_ => '-',
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};
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// Construct the permissions e.g. rwxr-xr-x
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// Moved to a separate function just because it's a bit verbose
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string permissions = GetPermissions(entry);
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// Display the owner info. 0 is special (root) but .NET doesn't
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// expose the mappings for these IDs natively, so ignoring for now
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string ownerUser = entry.Uid == 0 ? "root" : entry.Uid.ToString(CultureInfo.InvariantCulture);
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string ownerGroup = entry.Gid == 0 ? "root" : entry.Gid.ToString(CultureInfo.InvariantCulture);
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// The length of the data and the modification date in bytes
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long size = entry.Length;
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DateTimeOffset date = entry.ModificationTime.UtcDateTime;
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// Match the display format used by tar -tv
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string path = entry.EntryType switch
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{
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TarEntryType.HardLink => $"{entry.Name} link to {entry.LinkName}",
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TarEntryType.SymbolicLink => $"{entry.Name} -> {entry.LinkName}",
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_ => entry.Name,
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};
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// Write the entry!
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Console.WriteLine($"{type}{permissions} {ownerUser}/{ownerGroup} {size,9} {date:yyyy-MM-dd HH:mm} {path}");
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}
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// Construct the permissions
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static string GetPermissions(TarEntry entry)
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{
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var userRead = entry.Mode.HasFlag(UnixFileMode.UserRead) ? 'r' : '-';
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var userWrite = entry.Mode.HasFlag(UnixFileMode.UserWrite) ? 'w' : '-';
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var userExecute = entry.Mode.HasFlag(UnixFileMode.UserExecute) ? 'x' : '-';
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var groupRead = entry.Mode.HasFlag(UnixFileMode.GroupRead) ? 'r' : '-';
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var groupWrite = entry.Mode.HasFlag(UnixFileMode.GroupWrite) ? 'w' : '-';
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var groupExecute = entry.Mode.HasFlag(UnixFileMode.GroupExecute) ? 'x' : '-';
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var otherRead = entry.Mode.HasFlag(UnixFileMode.OtherRead) ? 'r' : '-';
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var otherWrite = entry.Mode.HasFlag(UnixFileMode.OtherWrite) ? 'w' : '-';
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var otherExecute = entry.Mode.HasFlag(UnixFileMode.OtherExecute) ? 'x' : '-';
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return $"{userRead}{userWrite}{userExecute}{groupRead}{groupWrite}{groupExecute}{otherRead}{otherWrite}{otherExecute}";
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}
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}
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int PrintUsage()
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{
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Console.WriteLine("USAGE: dotnetar --create <DESTINATIONTAR> <SOURCE>");
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Console.WriteLine("USAGE: dotnetar --extract <SOURCETAR> <DESTINATION>");
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Console.WriteLine("USAGE: dotnetar --single <SOURCETAR> <PATH_IN_TAR> <OUTPUT_PATH>");
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Console.WriteLine("USAGE: dotnetar --list <SOURCETAR>");
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return 1;
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}

‎UsingTarWithDotnet/dotnetar.csproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFrameworks>net7.0;net8.0</TargetFrameworks>
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<ImplicitUsings>enable</ImplicitUsings>
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<Nullable>enable</Nullable>
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</PropertyGroup>
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</Project>

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