tar #

This package provides stream-based readers and writers for tar files.

When working with large tar files, this library consumes considerably less memory than package:archive, although it is slightly slower.

Reading #

To read entries from a tar file, use

import 'dart:io';
import 'package:tar/tar.dart' as tar;

Future<void> main() async {
  final tarFile = File('file.tar')
       .openRead()
       .transform(tar.reader);

  await for (final entry in tarFile) {
    print(entry.name);
    print(await entry.transform(utf8.decoder).first);
  }
}

To read .tar.gz files, transform the stream with gzip.decoder first.

Writing #

You can write tar files into a StreamSink<List<int>>, such as an IOSink:

import 'dart:io';
import 'package:tar/tar.dart' as tar;

Future<void> main() async {
  final output = File('test.tar').openWrite();

  await Stream<tar.Entry>.value(
    tar.MemoryEntry(
      tar.Header(
        name: 'hello.txt',
        mode: int.parse('644', radix: 8),
      ),
      utf8.encode('Hello world'),
    ),
  ).pipe(tar.WritingSink(output));
}

Note that tar files are always written in the pax format defined by the POSIX.1-2001 specification (--format=posix in GNU tar). When all entries have file names shorter than 100 chars and a size smaller than 8 GB, this is equivalent to the ustar format. This library won't write PAX headers when there is no reason to do so.

To write .tar.gz files, you can again transform the stream twice:

import 'dart:io';
import 'package:tar/tar.dart' as tar;

Future<void> write(Stream<tar.Entry> entries) {
  return entries
      .transform(tar.writer)
      .transform(gzip.encoder)
      .pipe(File('output.tar.gz').openWrite())
}

Features #

• Supports ustar archives
• Supports extended pax headers for long file or link names
• Supports long file and link names generated by GNU-tar
• Hardened against denial-of-service attacks with invalid tar files