Podman Image SCP rootful to rootless transfer

Added functionality for users to transfer images from root storage to rootless storage without using sshd. This is
done through rootful podman by running `sudo podman image scp root@localhost::image user@localhost:: the user is needed
in order to find and use their uid/gid to exec a new process.

added necessary tests, and functions for this implementation. Created new image function Transfer so that
the underlying code is majorly removed from CLI

Signed-off-by: cdoern <cdoern@redhat.com>

1 files changed, 26 insertions, 5 deletions

diff --git a/cmd/podman/images/scp.go b/cmd/podman/images/scp.go
index c89a090bf..8402d9a10 100644
--- a/cmd/podman/images/scp.go
+++ b/cmd/podman/images/scp.go
@@ -16,6 +16,7 @@ import (
 	"github.com/containers/podman/v3/cmd/podman/system/connection"
 	"github.com/containers/podman/v3/libpod/define"
 	"github.com/containers/podman/v3/pkg/domain/entities"
+	"github.com/containers/podman/v3/pkg/rootless"
 	"github.com/docker/distribution/reference"
 	scpD "github.com/dtylman/scp"
 	"github.com/pkg/errors"
@@ -125,6 +126,11 @@ func scp(cmd *cobra.Command, args []string) (finalErr error) {
 		fmt.Println(rep)
 	// TODO: Add podman remote support
 	default: // else native load
+		scpOpts.Save.Format = "oci-archive"
+		_, err := os.Open(scpOpts.Save.Output)
+		if err != nil {
+			return err
+		}
 		if scpOpts.Tag != "" {
 			return errors.Wrapf(define.ErrInvalidArg, "Renaming of an image is currently not supported")
 		}
@@ -133,12 +139,20 @@ func scp(cmd *cobra.Command, args []string) (finalErr error) {
 		if abiErr != nil {
 			errors.Wrapf(abiErr, "could not save image as specified")
 		}
-		rep, err := abiEng.Load(context.Background(), scpOpts.Load)
-		if err != nil {
-			return err
+		if !rootless.IsRootless() && scpOpts.Rootless {
+			err := abiEng.Transfer(context.Background(), scpOpts)
+			if err != nil {
+				return err
+			}
+		} else {
+			rep, err := abiEng.Load(context.Background(), scpOpts.Load)
+			if err != nil {
+				return err
+			}
+			fmt.Println("Loaded image(s): " + strings.Join(rep.Names, ","))
 		}
-		fmt.Println("Loaded image(s): " + strings.Join(rep.Names, ","))
 	}
+
 	return nil
 }
 
@@ -271,7 +285,14 @@ func parseArgs(args []string, cfg *config.Config) (map[string]config.Destination
 			scpOpts.SourceImageName = args[0]
 		}
 	case 2:
-		if strings.Contains(args[0], "::") {
+		if strings.Contains(args[0], "localhost") || strings.Contains(args[1], "localhost") { // only supporting root to local using sudo at the moment
+			scpOpts.Rootless = true
+			scpOpts.User = strings.Split(args[1], "@")[0]
+			scpOpts.SourceImageName = strings.Split(args[0], "::")[1]
+			if strings.Split(args[0], "@")[0] != "root" {
+				return nil, errors.Wrapf(define.ErrInvalidArg, "cannot transfer images from any user besides root using sudo")
+			}
+		} else if strings.Contains(args[0], "::") {
 			if !(strings.Contains(args[1], "::")) && remoteArgLength(args[0], 1) == 0 { // if an image is specified, this mean we are loading to our client
 				cliConnections = append(cliConnections, args[0])
 				scpOpts.ToRemote = true