Cannot access symlinks in archives

[irbull]

When traversing the contents of a Tar Archive, there doesn't appear to be a way to access the reference to which a sym link points. The TarEntry structure indicates that the type is symlink, but there is no other metadata with information about where the sym link points.

import { join } from "https://deno.land/std@0.171.0/path/mod.ts";
import { ensureDir, ensureFile } from "https://deno.land/std@0.171.0/fs/mod.ts";
import { copy } from "https://deno.land/std@0.171.0/streams/mod.ts";
import { Untar } from "https://deno.land/std@0.171.0/archive/mod.ts";

export async function extractTarArchive(archive: string, destination: string) {
  const reader = await Deno.open(archive, { read: true });
  const untar = new Untar(reader);
  for await (const entry of untar) {
    if (entry.type === "symlink") {
      console.log(entry);
      continue;
    }
    if (entry.type === "directory") {
      await ensureDir(join(destination, entry.fileName));
      continue;
    }
    await ensureFile(join(destination, entry.fileName));
    const file = await Deno.open(join(destination, entry.fileName), {
      write: true,
    });
    await copy(entry, file);
  }
}

extractTarArchive("tarball.tar", "output_folder");

Here is a snippet that will attempt to read the contents of a Tar Archive. If it encounters a symlink it prints the metadata, but there doesn't appear to be a way to see what the sym link points too. In the case of a symlink I see this:

TarEntry {
  fileName: "folder/linked_file.txt",
  fileMode: 493,
  mtime: 1677876636,
  uid: 501,
  gid: 20,
  owner: "irbull",
  group: "staff",
  type: "symlink",
  fileSize: 0
}

This link_file.txt should point to file.txt. I've attached a tar archive that includes a sym link. (sorry, I had to zip the tar archive, as GitHub doesn't accept .tar files.)

tarball.tar.zip

[cwirving]

I had to modify a copy of archive/untar.ts to expose the linkName property on the TarEntry type in order to work around this issue (extracting tar files containing symbolic links). If there is interest (I know that there is a lot of talk about changing the archive module to use streams -- #1985 -- so changes to the old version may not be welcome), I could contribute it back here.