archive #

4.0 Update #

The Archive library was originally written when the web was the primary use of Dart. File IO was less of a concern and the design was around having everything in memory. As other uses of Dart came about, such as Flutter, a lot of File IO operations were added to the library, but not in a very clean way.

The design goal for the 4.0 revision of the library is to ensure File IO is a primary focus, while minimizing memory usage. Memory-only interfaces are still available for web platforms.

Migrating 3.x to 4.x.

Migration quick tips: #

• decodeBuffer has been renamed to decodeStream in the various decoder classes.
• InputStream has been renamed to InputMemoryStream.
• OutputStream has been renamed to OutputMemoryStream.

Overview #

A Dart library to encode and decode various archive and compression formats.

The archive library currently supports the following codecs:

• Zip
• Tar
• ZLib
• GZip
• BZip2
• XZ

Usage #

package:archive/archive.dart

• Can be used for both web and native applications.

package:archive/archive_io.dart

• Provides some extra utilities for 'dart:io' based applications.

Decoding a zip file in memory

import 'package:archive/archive.dart'; import 'dart:io'; void main() { final bytes = File('test.zip').readAsBytesSync(); final archive = ZipDecoder().decodeBytes(bytes); for (final entry in archive) { if (entry.isFile) { final fileBytes = file.readBytes(); File('out/${file.fullPathName}') ..createSync(recursive: true) ..writeAsBytesSync(fileBytes); } } } 

Using InputFileStream and OutputFileStream to extract a zip:

import 'dart:io'; import 'package:archive/archive.dart'; void main() { // Use an InputFileStream to access the zip file without storing it in memory. // Note that using InputFileStream will result in an error from the web platform // as there is no file system there. final inputStream = InputFileStream('test.zip'); // Decode the zip from the InputFileStream. The archive will have the contents of the // zip, without having stored the data in memory. final archive = ZipDecoder().decodeStream(inputStream); final symbolicLinks = []; // keep a list of the symbolic link entities, if any. // For all of the entries in the archive for (final file in archive) { // You should create symbolic links **after** the rest of the archive has been // extracted, otherwise the file being linked might not exist yet. if (file.isSymbolicLink) { symbolicLinks.add(file); continue; } if (file.isFile) { // Write the file content to a directory called 'out'. // In practice, you should make sure file.name doesn't include '..' paths // that would put it outside of the extraction directory. // An OutputFileStream will write the data to disk. final outputStream = OutputFileStream('out/${file.name}'); // The writeContent method will decompress the file content directly to disk without // storing the decompressed data in memory. entity.writeContent(outputStream); // Make sure to close the output stream so the File is closed. outputStream.closeSync(); } else { // If the entity is a directory, create it. Normally writing a file will create // the directories necessary, but sometimes an archive will have an empty directory // with no files. Directory('out/${file.name}').createSync(recursive: true); } } // Create symbolic links **after** the rest of the archive has been extracted to make sure // the file being linked exists. for (final entity in symbolicLinks) { // Before using this in production code, you should ensure the symbolicLink path // points to a file within the archive, otherwise it could be a security issue. final link = Link('out/${entity.fullPathName}'); link.createSync(entity.symbolicLink!, recursive: true); } } 

extractFileToDisk

extractFileToDisk is a convenience function to extract the contents of an archive file directory to an output directory. The type of archive it is will be determined by the file extension.

import 'package:archive/archive_io.dart'; // ... extractFileToDisk('test.zip', 'out'); 

extractArchiveToDisk

extractArchiveToDisk is a convenience function to write the contents of an Archive to an output directory.

import 'package:archive/archive_io.dart'; // ... // Use an InputFileStream to access the zip file without storing it in memory. final inputStream = InputFileStream('test.zip'); // Decode the zip from the InputFileStream. The archive will have the contents of the // zip, without having stored the data in memory. final archive = ZipDecoder().decodeStream(inputStream); extractArchiveToDisk(archive, 'out');