# `Tank.Image.Tar`
[🔗](https://github.com/oshlabs/tank/blob/v0.2.0/lib/tank/image/tar.ex#L1)

Extracts an OCI image layer -- a gzipped tar -- into a directory.

Why not `:erl_tar`: it refuses absolute and `..`-escaping symlinks as an
anti-symlink-attack measure, with no opt-out. A container root filesystem
legitimately contains absolute symlinks (`/bin/sh -> /bin/busybox` and many
more), so `:erl_tar.extract` cannot assemble OCI layers. This module reads
the tar itself and creates every entry, symlinks included.

It understands the ustar format plus the GNU long-name (`L`/`K`) and PAX
extended-header (`x`/`g`) extensions. Character/block devices and FIFOs are
skipped -- creating them needs privilege and images rarely ship them in
layers.

OCI whiteout markers are honoured so layers stack correctly: `.wh.<name>`
deletes a lower-layer entry, and `.wh..wh..opq` empties a directory of its
lower-layer contents. The markers themselves are never written.

# `extract`

```elixir
@spec extract(Path.t(), Path.t()) :: :ok | {:error, term()}
```

Extracts the gzipped-tar layer at `path` into `dest` (created if absent).

Returns `:ok` or `{:error, reason}`.

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*Consult [api-reference.md](api-reference.md) for complete listing*