Add crane-based methods for extraction

- create a new api package to encapsulate image manipulation
- use new api method to calculate delta

Fixes #258
Fixes #204
Fixes #90

pkg/api/core/image/extract.go

@@ -0,0 +1,119 @@
+// Copyright © 2021 Ettore Di Giacinto <mudler@mocaccino.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, see <http://www.gnu.org/licenses/>.
+
+package image
+
+import (
+	"archive/tar"
+	"context"
+
+	containerdarchive "github.com/containerd/containerd/archive"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/mudler/luet/pkg/api/core/types"
+	"github.com/pkg/errors"
+)
+
+// Extract dir:
+// -> First extract delta considering the dir
+// Afterward create artifact pointing to the dir
+
+// ExtractDeltaFiles returns an handler to extract files in a list
+func ExtractDeltaFiles(
+	ctx *types.Context,
+	d ImageDiff,
+	includes []string, excludes []string,
+) func(h *tar.Header) (bool, error) {
+
+	includeRegexp := compileRegexes(includes)
+	excludeRegexp := compileRegexes(excludes)
+
+	return func(h *tar.Header) (bool, error) {
+		switch {
+		case len(includes) == 0 && len(excludes) != 0:
+			for _, a := range d.Additions {
+				if h.Name == a.Name {
+					for _, i := range excludeRegexp {
+						if i.MatchString(a.Name) && h.Name == a.Name {
+							return false, nil
+						}
+					}
+					ctx.Info("Adding name", h.Name)
+
+					return true, nil
+				}
+			}
+			return false, nil
+		case len(includes) > 0 && len(excludes) == 0:
+			for _, a := range d.Additions {
+				for _, i := range includeRegexp {
+					if i.MatchString(a.Name) && h.Name == a.Name {
+						ctx.Info("Adding name", h.Name)
+
+						return true, nil
+					}
+				}
+			}
+			return false, nil
+		case len(includes) != 0 && len(excludes) != 0:
+			for _, a := range d.Additions {
+				for _, i := range includeRegexp {
+					if i.MatchString(a.Name) && h.Name == a.Name {
+						for _, e := range excludeRegexp {
+							if e.MatchString(a.Name) {
+								return false, nil
+							}
+						}
+						ctx.Info("Adding name", h.Name)
+
+						return true, nil
+					}
+				}
+			}
+			return false, nil
+		default:
+			for _, a := range d.Additions {
+				if h.Name == a.Name {
+					ctx.Info("Adding name", h.Name)
+
+					return true, nil
+				}
+			}
+			return false, nil
+		}
+
+	}
+}
+
+func Extract(ctx *types.Context, img v1.Image, filter func(h *tar.Header) (bool, error), opts ...containerdarchive.ApplyOpt) (string, error) {
+	src := mutate.Extract(img)
+	defer src.Close()
+
+	tmpdiffs, err := ctx.Config.GetSystem().TempDir("extraction")
+	if err != nil {
+		return "", errors.Wrap(err, "Error met while creating tempdir for rootfs")
+	}
+
+	if filter != nil {
+		opts = append(opts, containerdarchive.WithFilter(filter))
+	}
+
+	_, err = containerdarchive.Apply(context.Background(), tmpdiffs, src, opts...)
+	if err != nil {
+		return "", err
+	}
+
+	return tmpdiffs, nil
+}