From fc93c9e3ea53ba6b6818db861551c0745ba18bec Mon Sep 17 00:00:00 2001
From: Ettore Di Giacinto <mudler@gentoo.org>
Date: Sun, 10 Nov 2019 10:46:57 +0100
Subject: [PATCH] Generate artifact delta from layer diffs

---
 pkg/compiler/artifact.go | 85 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)

diff --git a/pkg/compiler/artifact.go b/pkg/compiler/artifact.go
index e3c7f30d..7daa5bfb 100644
--- a/pkg/compiler/artifact.go
+++ b/pkg/compiler/artifact.go
@@ -15,6 +15,20 @@
 
 package compiler
 
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+
+	. "github.com/mudler/luet/pkg/logger"
+
+	"github.com/mudler/luet/pkg/helpers"
+	"github.com/pkg/errors"
+)
+
 type PackageArtifact struct {
 	Path string
 }
@@ -30,3 +44,74 @@ func (a *PackageArtifact) GetPath() string {
 func (a *PackageArtifact) SetPath(p string) {
 	a.Path = p
 }
+
+type CopyJob struct {
+	Src, Dst string
+}
+
+func worker(i int, wg *sync.WaitGroup, s <-chan CopyJob) {
+	defer wg.Done()
+
+	for job := range s {
+		Info("#"+strconv.Itoa(i), "copying", job.Src, "to", job.Dst)
+		if dir, err := helpers.IsDirectory(job.Src); err == nil && dir {
+			err = helpers.CopyDir(job.Src, job.Dst)
+			if err != nil {
+				Fatal("Error copying dir", job, err)
+			}
+			continue
+		}
+
+		if !helpers.Exists(job.Dst) {
+			if err := helpers.CopyFile(job.Src, job.Dst); err != nil {
+				Fatal("Error copying", job, err)
+			}
+		}
+	}
+}
+
+// ExtractArtifactFromDelta extracts deltas from ArtifactLayer from an image in tar format
+func ExtractArtifactFromDelta(src, dst string, layers []ArtifactLayer, concurrency int, keepPerms bool) (Artifact, error) {
+
+	archive, err := ioutil.TempDir(os.TempDir(), "archive")
+	if err != nil {
+		return nil, errors.Wrap(err, "Error met while creating tempdir for archive")
+	}
+	defer os.RemoveAll(archive) // clean up
+
+	if strings.HasSuffix(src, ".tar") {
+		rootfs, err := ioutil.TempDir(os.TempDir(), "rootfs")
+		if err != nil {
+			return nil, errors.Wrap(err, "Error met while creating tempdir for rootfs")
+		}
+		defer os.RemoveAll(rootfs) // clean up
+		err = helpers.Untar(src, rootfs, keepPerms)
+		if err != nil {
+			return nil, errors.Wrap(err, "Error met while unpacking rootfs")
+		}
+		src = rootfs
+	}
+
+	toCopy := make(chan CopyJob)
+
+	var wg = new(sync.WaitGroup)
+	for i := 0; i < concurrency; i++ {
+		wg.Add(1)
+		go worker(i, wg, toCopy)
+	}
+
+	for _, l := range layers {
+		// Consider d.Additions (and d.Changes? - warn at least) only
+		for _, a := range l.Diffs.Additions {
+			toCopy <- CopyJob{Src: filepath.Join(src, a.Name), Dst: filepath.Join(archive, a.Name)}
+		}
+	}
+	close(toCopy)
+	wg.Wait()
+
+	err = helpers.Tar(archive, dst)
+	if err != nil {
+		return nil, errors.Wrap(err, "Error met while creating package archive")
+	}
+	return NewPackageArtifact(dst), nil
+}