Function splitConfigRootFSFromTar

daemon/pkg/plugin/backend_linux.go:759–818

(in io.ReadCloser, config *[]byte)

}

func splitConfigRootFSFromTar(in io.ReadCloser, config *[]byte) io.ReadCloser {
	pr, pw := io.Pipe()
	go func() {
		tarReader := tar.NewReader(in)
		tarWriter := tar.NewWriter(pw)
		defer in.Close()

		hasRootFS := false

		for {
			hdr, err := tarReader.Next()
			if err == io.EOF {
				if !hasRootFS {
					pw.CloseWithError(errors.Wrap(err, "no rootfs found"))
					return
				}
				// Signals end of archive.
				tarWriter.Close()
				pw.Close()
				return
			}
			if err != nil {
				pw.CloseWithError(errors.Wrap(err, "failed to read from tar"))
				return
			}

			content := io.Reader(tarReader)
			name := path.Clean(hdr.Name)
			if path.IsAbs(name) {
				name = name[1:]
			}
			if name == configFileName {
				dt, err := io.ReadAll(content)
				if err != nil {
					pw.CloseWithError(errors.Wrapf(err, "failed to read %s", configFileName))
					return
				}
				*config = dt
			}
			if parts := strings.Split(name, "/"); len(parts) != 0 && parts[0] == rootFSFileName {
				hdr.Name = path.Clean(path.Join(parts[1:]...))
				if hdr.Typeflag == tar.TypeLink && strings.HasPrefix(strings.ToLower(hdr.Linkname), rootFSFileName+"/") {
					hdr.Linkname = hdr.Linkname[len(rootFSFileName)+1:]
				}
				if err := tarWriter.WriteHeader(hdr); err != nil {
					pw.CloseWithError(errors.Wrap(err, "error writing tar header"))
					return
				}
				if _, err := pools.Copy(tarWriter, content); err != nil {
					pw.CloseWithError(errors.Wrap(err, "error copying tar data"))
					return
				}
				hasRootFS = true
			} else {
				io.Copy(io.Discard, content)
			}
		}
	}()