Image Resolution Stage 1

This is the stage 1 effort for an image library that can be eventually used by buildah and
podman alike.  In eventuality, the main goal of the library (package) is to:

* provide a consistent approach to resolving image names in various forms (from users).
* based on the result of the above, provide image methods that in a singular spot but separate from the runtime.
* reduce the cruft and bloat in the current podman runtime.

The goal of stage 1 is to demonstrate fast, accurate image resolution for both local and remote images resulting in
an image object as part of the return.

Signed-off-by: baude <bbaude@redhat.com>

Closes: #463
Approved by: baude

1 files changed, 42 insertions, 0 deletions

diff --git a/libpod/image/utils.go b/libpod/image/utils.go
new file mode 100644
index 000000000..f312c8e4d
--- /dev/null
+++ b/libpod/image/utils.go
@@ -0,0 +1,42 @@
+package image
+
+import (
+	"github.com/containers/image/docker/reference"
+	"github.com/containers/storage"
+	"github.com/pkg/errors"
+)
+
+func getTags(nameInput string) (reference.NamedTagged, bool, error) {
+	inputRef, err := reference.Parse(nameInput)
+	if err != nil {
+		return nil, false, errors.Wrapf(err, "unable to obtain tag from input name")
+	}
+	tagged, isTagged := inputRef.(reference.NamedTagged)
+
+	return tagged, isTagged, nil
+}
+
+// findImageInRepotags takes an imageParts struct and searches images' repotags for
+// a match on name:tag
+func findImageInRepotags(search imageParts, images []*storage.Image) (*storage.Image, error) {
+	var results []*storage.Image
+	for _, image := range images {
+		for _, name := range image.Names {
+			d, err := decompose(name)
+			// if we get an error, ignore and keep going
+			if err != nil {
+				continue
+			}
+			if d.name == search.name && d.tag == search.tag {
+				results = append(results, image)
+				break
+			}
+		}
+	}
+	if len(results) == 0 {
+		return &storage.Image{}, errors.Errorf("unable to find a name and tag match for %s in repotags", search)
+	} else if len(results) > 1 {
+		return &storage.Image{}, errors.Errorf("found multiple name and tag matches for %s in repotags", search)
+	}
+	return results[0], nil
+}