lib/omnibus/fetchers/net_fetcher.rb
def extract
      # Only used by tar
      compression_switch = ""
      compression_switch = "z"        if downloaded_file.end_with?("gz")
      compression_switch = "--lzma -" if downloaded_file.end_with?("lzma")
      compression_switch = "j"        if downloaded_file.end_with?("bz2")
      compression_switch = "J"        if downloaded_file.end_with?("xz")

      if Ohai["platform"] == "windows"
        if downloaded_file.end_with?(*TAR_EXTENSIONS) && source[:extract] != :seven_zip
          returns = [0]
          returns << 1 if source[:extract] == :lax_tar

          shellout!("tar #{compression_switch}xf #{safe_downloaded_file} -C#{safe_project_dir}", returns: returns)
        elsif downloaded_file.end_with?(*COMPRESSED_TAR_EXTENSIONS)
          Dir.mktmpdir do |temp_dir|
            log.debug(log_key) { "Temporarily extracting `#{safe_downloaded_file}' to `#{temp_dir}'" }

            shellout!("7z.exe x #{safe_downloaded_file} -o#{windows_safe_path(temp_dir)} -r -y")

            fname = File.basename(downloaded_file, File.extname(downloaded_file))
            fname << ".tar" if downloaded_file.end_with?("tgz", "txz")
            next_file = windows_safe_path(File.join(temp_dir, fname))

            log.debug(log_key) { "Temporarily extracting `#{next_file}' to `#{safe_project_dir}'" }
            shellout!("7z.exe x #{next_file} -o#{safe_project_dir} -r -y")
          end
        else
          shellout!("7z.exe x #{safe_downloaded_file} -o#{safe_project_dir} -r -y")
        end
      elsif downloaded_file.end_with?(".7z")
        shellout!("7z x #{safe_downloaded_file} -o#{safe_project_dir} -r -y")
      elsif downloaded_file.end_with?(".zip")
        shellout!("unzip #{safe_downloaded_file} -d #{safe_project_dir}")
      else
        shellout!("#{tar} #{compression_switch}xf #{safe_downloaded_file} -C#{safe_project_dir}")
      end
    end
def extract
      # Only used by tar
      compression_switch = ""
      compression_switch = "z"        if downloaded_file.end_with?("gz")
      compression_switch = "--lzma -" if downloaded_file.end_with?("lzma")
      compression_switch = "j"        if downloaded_file.end_with?("bz2")
      compression_switch = "J"        if downloaded_file.end_with?("xz")

      if Ohai["platform"] == "windows"
        if downloaded_file.end_with?(*TAR_EXTENSIONS) && source[:extract] != :seven_zip
          returns = [0]
          returns << 1 if source[:extract] == :lax_tar

          shellout!("tar #{compression_switch}xf #{safe_downloaded_file} -C#{safe_project_dir}", returns: returns)
        elsif downloaded_file.end_with?(*COMPRESSED_TAR_EXTENSIONS)
          Dir.mktmpdir do |temp_dir|
            log.debug(log_key) { "Temporarily extracting `#{safe_downloaded_file}' to `#{temp_dir}'" }

            shellout!("7z.exe x #{safe_downloaded_file} -o#{windows_safe_path(temp_dir)} -r -y")

            fname = File.basename(downloaded_file, File.extname(downloaded_file))
            fname << ".tar" if downloaded_file.end_with?("tgz", "txz")
            next_file = windows_safe_path(File.join(temp_dir, fname))

            log.debug(log_key) { "Temporarily extracting `#{next_file}' to `#{safe_project_dir}'" }
            shellout!("7z.exe x #{next_file} -o#{safe_project_dir} -r -y")
          end
        else
          shellout!("7z.exe x #{safe_downloaded_file} -o#{safe_project_dir} -r -y")
        end
      elsif downloaded_file.end_with?(".7z")
        shellout!("7z x #{safe_downloaded_file} -o#{safe_project_dir} -r -y")
      elsif downloaded_file.end_with?(".zip")
        shellout!("unzip #{safe_downloaded_file} -d #{safe_project_dir}")
      else
        shellout!("#{tar} #{compression_switch}xf #{safe_downloaded_file} -C#{safe_project_dir}")
      end
    end
Extracts the downloaded archive file into project_dir.

 On windows, this is a fuster cluck and we allow users to specify the
 preferred extractor to be used. The default is to use tar. User overrides
 can be set in source[:extract] as:
   :tar - use tar.exe and fail on errors (default strategy).
   :seven_zip - use 7zip for all tar/compressed tar files on windows.
   :lax_tar - use tar.exe on windows but ignore errors.

 Both 7z and bsdtar have issues on windows.

 7z cannot extract and untar at the same time. You need to extract to a
 temporary location and then extract again into project_dir.

 7z also doesn't handle symlinks well. A symlink to a non-existent
 location simply results in a text file with the target path written in
 it. It does this without throwing any errors.

 bsdtar will exit(1) if it is encounters symlinks on windows. So we can't
 use shellout! directly.

 bsdtar will also exit(1) and fail to overwrite files at the destination
 during extraction if a file already exists at the destination and is
 marked read-only. This used to be a problem when we weren't properly
 cleaning an existing project_dir. It should be less of a problem now...
 but who knows.