it-tar

it-tar is a streaming tar parser (and maybe a generator in the future) and nothing else. It operates purely using async iterables which means you can easily extract/parse tarballs without ever hitting the file system.

About

it-tar packs and extracts tarballs.

It implements USTAR with additional support for pax extended headers. It should be compatible with all popular tar distributions out there (gnutar, bsdtar etc)

Example - Packing

To create a pack stream use tar.pack() and pipe entries to it.

import fs from 'node:fs'
import * as Tar from 'it-tar'
import { pipe } from 'it-pipe'
import { sink } from 'stream-to-it'

await pipe(
  [
    // add a file called my-test.txt with the content "Hello World!"
    {
      header: { name: 'my-test.txt' },
      body: 'Hello World!'
    },
    // add a file called my-stream-test.txt from a stream
    {
      header: { name: 'my-stream-test.txt', size: 11 },
      body: fs.createReadStream('./my-stream-test.txt')
    }
  ],
  Tar.pack(),
  // pipe the pack stream somewhere
  sink(process.stdout)
)

Example - Extracting

To extract a stream use tar.extract() and pipe a source iterable to it.

import * as Tar from 'it-tar'
import { pipe } from 'it-pipe'

await pipe(
  [Uint8Array.from([0, 1, 2, 3, 4])], // An async iterable (for example a Node.js readable stream)
  Tar.extract(),
  async source => {
    for await (const entry of source) {
      // entry.header is the tar header (see below)
      // entry.body is the content body (might be an empty async iterable)
      for await (const data of entry.body) {
        // do something with the data
      }
    }
    // all entries read
  }
)

The tar archive is streamed sequentially, meaning you must drain each entry's body as you get them or else the main extract stream will receive backpressure and stop reading.

Note that the body stream yields Uint8ArrayList objects not Uint8Arrayss.

Example - Modifying existing tarballs

Using tar-stream it is easy to rewrite paths / change modes etc in an existing tarball.

import * as Tar from 'it-tar'
import { pipe } from 'it-pipe'
import { sink } from 'stream-to-it'
import fs from 'node:fs'
import path from 'node:path'

await pipe(
  fs.createReadStream('./old-tarball.tar'),
  Tar.extract(),
  async function * (source) {
    for await (const entry of source) {
      // let's prefix all names with 'tmp'
      entry.header.name = path.join('tmp', entry.header.name)
      // write the new entry to the pack stream
      yield entry
    }
  },
  Tar.pack(),
  sink(fs.createWriteStream('./new-tarball.tar'))
)

Headers

The header object using in entry should contain the following properties. Most of these values can be found by stat'ing a file.

{
  name: 'path/to/this/entry.txt',
  size: 1314,        // entry size. defaults to 0
  mode: 0644,        // entry mode. defaults to to 0755 for dirs and 0644 otherwise
  mtime: new Date(), // last modified date for entry. defaults to now.
  type: 'file',      // type of entry. defaults to file. can be:
                     // file | link | symlink | directory | block-device
                     // character-device | fifo | contiguous-file
  linkname: 'path',  // linked file name
  uid: 0,            // uid of entry owner. defaults to 0
  gid: 0,            // gid of entry owner. defaults to 0
  uname: 'maf',      // uname of entry owner. defaults to null
  gname: 'staff',    // gname of entry owner. defaults to null
  devmajor: 0,       // device major version. defaults to 0
  devminor: 0        // device minor version. defaults to 0
}

Related

• it-pipe Utility to "pipe" async iterables together
• it-reader Read an exact number of bytes from a binary (async) iterable
• stream-to-it Convert Node.js streams to streaming iterables

Install

$ npm i it-tar

API Docs

• https://alanshaw.github.io/it-tar

License

Licensed under either of

• Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
• MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.