untar

Minimalistic libtar-based library that can extract tar archives from a file on disk or from a memory buffer.

Installation

0. Make sure libtar is available on your system.

1. Add the dependency to your shard.yml:

   dependencies:
     untar:
       github: vivus-ignis/crystal-untar

2. Run shards install

Usage

There are two ways to use this library. Obviously, you can extract files from a tar archive on disk:

require "untar"

Dir.mkdir "/tmp/archive"
Untar.extract("archive.tar", "/tmp/archive")

The other option is to extract files from an archive that is loaded in a memory buffer. Consider the example below:

require "http/client"
require "gzip"
require "untar"

response = HTTP::Client.get "https://nginx.org/download/nginx-1.15.9.tar.gz"

zipped = IO::Memory.new(response.body)
unzipped = Gzip::Reader.open(zipped) { |gzip| gzip.gets_to_end }
tarball = IO::Memory.new(unzipped)

Dir.mkdir "/tmp/nginx"
Untar.extract(tarball, "/tmp/nginx")

Notice that the same Untar.extract method is used to unpack a tarball on disk and in memory.

For an in-memory archive there is an additional option to only extract a certain file. Let's pretend we want to fetch nginx changelog:

require "http/client"
require "gzip"
require "untar"

response = HTTP::Client.get "https://nginx.org/download/nginx-1.15.9.tar.gz"
zipped = IO::Memory.new(response.body)
unzipped = Gzip::Reader.open(zipped) { |gzip| gzip.gets_to_end }
tarball = IO::Memory.new(unzipped)

changelog = Untar.extract_file(tarball, "nginx-1.15.9/CHANGES")

puts changelog

Error handling

On errors Untar raises an UntarException.

Contributing

1. Fork it (https://github.com/vivus-ignis/crystal-untar/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Yaroslav Tarasenko - creator and maintainer