support multi-image (docker) archives

Support loading and saving tarballs with more than one image.
Add a new `/libpod/images/export` endpoint to the rest API to
allow for exporting/saving multiple images into an archive.

Note that a non-release version of containers/image is vendored.
A release version must be vendored before cutting a new Podman
release.  We force the containers/image version via a replace in
the go.mod file; this way go won't try to match the versions.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/github.com/containers/image/v5/docker/archive/src.go

@@ -3,9 +3,8 @@ package archive
 import (
 	"context"
 
-	"github.com/containers/image/v5/docker/tarfile"
+	"github.com/containers/image/v5/docker/internal/tarfile"
 	"github.com/containers/image/v5/types"
-	"github.com/sirupsen/logrus"
 )
 
 type archiveImageSource struct {
@@ -16,13 +15,20 @@ type archiveImageSource struct {
 // newImageSource returns a types.ImageSource for the specified image reference.
 // The caller must call .Close() on the returned ImageSource.
 func newImageSource(ctx context.Context, sys *types.SystemContext, ref archiveReference) (types.ImageSource, error) {
-	if ref.destinationRef != nil {
-		logrus.Warnf("docker-archive: references are not supported for sources (ignoring)")
-	}
-	src, err := tarfile.NewSourceFromFileWithContext(sys, ref.path)
-	if err != nil {
-		return nil, err
+	var archive *tarfile.Reader
+	var closeArchive bool
+	if ref.archiveReader != nil {
+		archive = ref.archiveReader
+		closeArchive = false
+	} else {
+		a, err := tarfile.NewReaderFromFile(sys, ref.path)
+		if err != nil {
+			return nil, err
+		}
+		archive = a
+		closeArchive = true
 	}
+	src := tarfile.NewSource(archive, closeArchive, ref.ref, ref.sourceIndex)
 	return &archiveImageSource{
 		Source: src,
 		ref:    ref,