1 files changed, 154 insertions, 0 deletions
diff --git a/vendor/github.com/containers/image/v5/copy/manifest.go b/vendor/github.com/containers/image/v5/copy/manifest.go
new file mode 100644
index 000000000..f5f6c9c5f
--- /dev/null
+++ b/vendor/github.com/containers/image/v5/copy/manifest.go
@@ -0,0 +1,154 @@
+package copy
+
+import (
+	"context"
+	"strings"
+
+	"github.com/containers/image/v5/manifest"
+	"github.com/containers/image/v5/types"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// preferredManifestMIMETypes lists manifest MIME types in order of our preference, if we can't use the original manifest and need to convert.
+// Prefer v2s2 to v2s1 because v2s2 does not need to be changed when uploading to a different location.
+// Include v2s1 signed but not v2s1 unsigned, because docker/distribution requires a signature even if the unsigned MIME type is used.
+var preferredManifestMIMETypes = []string{manifest.DockerV2Schema2MediaType, manifest.DockerV2Schema1SignedMediaType}
+
+// orderedSet is a list of strings (MIME types in our case), with each string appearing at most once.
+type orderedSet struct {
+	list     []string
+	included map[string]struct{}
+}
+
+// newOrderedSet creates a correctly initialized orderedSet.
+// [Sometimes it would be really nice if Golang had constructors…]
+func newOrderedSet() *orderedSet {
+	return &orderedSet{
+		list:     []string{},
+		included: map[string]struct{}{},
+	}
+}
+
+// append adds s to the end of os, only if it is not included already.
+func (os *orderedSet) append(s string) {
+	if _, ok := os.included[s]; !ok {
+		os.list = append(os.list, s)
+		os.included[s] = struct{}{}
+	}
+}
+
+// determineManifestConversion updates ic.manifestUpdates to convert manifest to a supported MIME type, if necessary and ic.canModifyManifest.
+// Note that the conversion will only happen later, through ic.src.UpdatedImage
+// Returns the preferred manifest MIME type (whether we are converting to it or using it unmodified),
+// and a list of other possible alternatives, in order.
+func (ic *imageCopier) determineManifestConversion(ctx context.Context, destSupportedManifestMIMETypes []string, forceManifestMIMEType string) (string, []string, error) {
+	_, srcType, err := ic.src.Manifest(ctx)
+	if err != nil { // This should have been cached?!
+		return "", nil, errors.Wrap(err, "Error reading manifest")
+	}
+	normalizedSrcType := manifest.NormalizedMIMEType(srcType)
+	if srcType != normalizedSrcType {
+		logrus.Debugf("Source manifest MIME type %s, treating it as %s", srcType, normalizedSrcType)
+		srcType = normalizedSrcType
+	}
+
+	if forceManifestMIMEType != "" {
+		destSupportedManifestMIMETypes = []string{forceManifestMIMEType}
+	}
+
+	if len(destSupportedManifestMIMETypes) == 0 {
+		return srcType, []string{}, nil // Anything goes; just use the original as is, do not try any conversions.
+	}
+	supportedByDest := map[string]struct{}{}
+	for _, t := range destSupportedManifestMIMETypes {
+		supportedByDest[t] = struct{}{}
+	}
+
+	// destSupportedManifestMIMETypes is a static guess; a particular registry may still only support a subset of the types.
+	// So, build a list of types to try in order of decreasing preference.
+	// FIXME? This treats manifest.DockerV2Schema1SignedMediaType and manifest.DockerV2Schema1MediaType as distinct,
+	// although we are not really making any conversion, and it is very unlikely that a destination would support one but not the other.
+	// In practice, schema1 is probably the lowest common denominator, so we would expect to try the first one of the MIME types
+	// and never attempt the other one.
+	prioritizedTypes := newOrderedSet()
+
+	// First of all, prefer to keep the original manifest unmodified.
+	if _, ok := supportedByDest[srcType]; ok {
+		prioritizedTypes.append(srcType)
+	}
+	if !ic.canModifyManifest {
+		// We could also drop the !ic.canModifyManifest check and have the caller
+		// make the choice; it is already doing that to an extent, to improve error
+		// messages.  But it is nice to hide the “if !ic.canModifyManifest, do no conversion”
+		// special case in here; the caller can then worry (or not) only about a good UI.
+		logrus.Debugf("We can't modify the manifest, hoping for the best...")
+		return srcType, []string{}, nil // Take our chances - FIXME? Or should we fail without trying?
+	}
+
+	// Then use our list of preferred types.
+	for _, t := range preferredManifestMIMETypes {
+		if _, ok := supportedByDest[t]; ok {
+			prioritizedTypes.append(t)
+		}
+	}
+
+	// Finally, try anything else the destination supports.
+	for _, t := range destSupportedManifestMIMETypes {
+		prioritizedTypes.append(t)
+	}
+
+	logrus.Debugf("Manifest has MIME type %s, ordered candidate list [%s]", srcType, strings.Join(prioritizedTypes.list, ", "))
+	if len(prioritizedTypes.list) == 0 { // Coverage: destSupportedManifestMIMETypes is not empty (or we would have exited in the “Anything goes” case above), so this should never happen.
+		return "", nil, errors.New("Internal error: no candidate MIME types")
+	}
+	preferredType := prioritizedTypes.list[0]
+	if preferredType != srcType {
+		ic.manifestUpdates.ManifestMIMEType = preferredType
+	} else {
+		logrus.Debugf("... will first try using the original manifest unmodified")
+	}
+	return preferredType, prioritizedTypes.list[1:], nil
+}
+
+// isMultiImage returns true if img is a list of images
+func isMultiImage(ctx context.Context, img types.UnparsedImage) (bool, error) {
+	_, mt, err := img.Manifest(ctx)
+	if err != nil {
+		return false, err
+	}
+	return manifest.MIMETypeIsMultiImage(mt), nil
+}
+
+// determineListConversion takes the current MIME type of a list of manifests,
+// the list of MIME types supported for a given destination, and a possible
+// forced value, and returns the MIME type to which we should convert the list
+// of manifests, whether we are converting to it or using it unmodified.
+func (c *copier) determineListConversion(currentListMIMEType string, destSupportedMIMETypes []string, forcedListMIMEType string) (string, error) {
+	// If we're forcing it, we prefer the forced value over everything else.
+	if forcedListMIMEType != "" {
+		return forcedListMIMEType, nil
+	}
+	// If there's no list of supported types, then anything we support is expected to be supported.
+	if len(destSupportedMIMETypes) == 0 {
+		destSupportedMIMETypes = manifest.SupportedListMIMETypes
+	}
+	var selectedType string
+	for i := range destSupportedMIMETypes {
+		// The second priority is the first member of the list of acceptable types that is a list,
+		// but keep going in case current type occurs later in the list.
+		if selectedType == "" && manifest.MIMETypeIsMultiImage(destSupportedMIMETypes[i]) {
+			selectedType = destSupportedMIMETypes[i]
+		}
+		// The first priority is the current type, if it's in the list, since that lets us avoid a
+		// conversion that isn't strictly necessary.
+		if destSupportedMIMETypes[i] == currentListMIMEType {
+			selectedType = destSupportedMIMETypes[i]
+		}
+	}
+	if selectedType == "" {
+		return "", errors.Errorf("destination does not support any supported manifest list types (%v)", manifest.SupportedListMIMETypes)
+	}
+	// Done.
+	return selectedType, nil
+}