[sha512]: common: add scalable digest utilities and update libimage

- Create common/pkg/digestutils package with comprehensive digest handling functions
  * IsDigestReference() for robust digest detection using go-digest library
  * ExtractAlgorithmFromDigest() for parsing digest strings with validation
  * HasDigestPrefix(), GetDigestPrefix(), TrimDigestPrefix() for scalable prefix handling
- Update libimage to use digestutils instead of hardcoded SHA256/SHA512 checks
  * Replace strings.HasPrefix() calls in filters.go, image.go, runtime.go
  * Support only SHA256 and SHA512 algorithms as per container-libs requirements
- Update existing libimage tests to work with new digestutils functions

Signed-off-by: Lokesh Mandvekar <[email protected]>

Author: lsm5

common/libimage/filters.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/sirupsen/logrus"
+	"go.podman.io/common/pkg/digestutils"
 	filtersPkg "go.podman.io/common/pkg/filters"
 	"go.podman.io/common/pkg/timetype"
 	"go.podman.io/image/v5/docker/reference"
@@ -481,7 +482,7 @@ func filterID(value string) filterFunc {
 
 // filterDigest creates a digest filter for matching the specified value.
 func filterDigest(value string) (filterFunc, error) {
-	if !strings.HasPrefix(value, "sha256:") {
+	if !digestutils.HasDigestPrefix(value) {
 		return nil, fmt.Errorf("invalid value %q for digest filter", value)
 	}
 	return func(img *Image, _ *layerTree) (bool, error) {

common/libimage/filters_test.go

@@ -169,19 +169,35 @@ func TestFilterDigest(t *testing.T) {
 	}{
 		{string(busybox.Digest()[:10]), 1, busybox.ID()},
 		{string(alpine.Digest()[:10]), 1, alpine.ID()},
+		// Test SHA512 digest prefix matching
+		{"sha512:1234567890abcdef", 0, ""}, // Non-existent SHA512 digest
+		{"sha256:1234567890abcdef", 0, ""}, // Non-existent SHA256 digest
 	} {
 		listOptions := &ListImagesOptions{
 			Filters: []string{"digest=" + test.filter},
 		}
 		listedImages, err := runtime.ListImages(ctx, listOptions)
 		require.NoError(t, err, "%v", test)
 		require.Len(t, listedImages, test.matches, "%s -> %v", test.filter, listedImages)
-		require.Equal(t, listedImages[0].ID(), test.id)
+		if test.matches > 0 {
+			require.Equal(t, listedImages[0].ID(), test.id)
+		}
 	}
 	_, err = runtime.ListImages(ctx, &ListImagesOptions{
 		Filters: []string{"digest=this-is-not-a-digest"},
 	})
 	assert.Error(t, err)
+
+	// Test invalid digest algorithms
+	_, err = runtime.ListImages(ctx, &ListImagesOptions{
+		Filters: []string{"digest=md5:1234567890abcdef"},
+	})
+	assert.Error(t, err)
+
+	_, err = runtime.ListImages(ctx, &ListImagesOptions{
+		Filters: []string{"digest=sha384:1234567890abcdef"},
+	})
+	assert.Error(t, err)
 }
 
 func TestFilterID(t *testing.T) {

common/libimage/image.go

@@ -18,6 +18,7 @@ import (
 	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/sirupsen/logrus"
 	"go.podman.io/common/libimage/platform"
+	"go.podman.io/common/pkg/digestutils"
 	"go.podman.io/image/v5/docker/reference"
 	"go.podman.io/image/v5/image"
 	"go.podman.io/image/v5/manifest"
@@ -474,7 +475,7 @@ func (i *Image) removeRecursive(ctx context.Context, rmMap map[string]*RemoveIma
 	// error.
 	if referencedBy != "" && numNames != 1 {
 		byID := strings.HasPrefix(i.ID(), referencedBy)
-		byDigest := strings.HasPrefix(referencedBy, "sha256:")
+		byDigest := digestutils.HasDigestPrefix(referencedBy)
 		if !options.Force {
 			if byID && numNames > 1 {
 				return processedIDs, fmt.Errorf("unable to delete image %q by ID with more than one tag (%s): please force removal", i.ID(), i.Names())
@@ -577,7 +578,7 @@ var errTagDigest = errors.New("tag by digest not supported")
 // Tag the image with the specified name and store it in the local containers
 // storage.  The name is normalized according to the rules of NormalizeName.
 func (i *Image) Tag(name string) error {
-	if strings.HasPrefix(name, "sha256:") { // ambiguous input
+	if digestutils.HasDigestPrefix(name) { // ambiguous input
 		return fmt.Errorf("%s: %w", name, errTagDigest)
 	}
 
@@ -613,7 +614,7 @@ var errUntagDigest = errors.New("untag by digest not supported")
 // the local containers storage.  The name is normalized according to the rules
 // of NormalizeName.
 func (i *Image) Untag(name string) error {
-	if strings.HasPrefix(name, "sha256:") { // ambiguous input
+	if digestutils.HasDigestPrefix(name) { // ambiguous input
 		return fmt.Errorf("%s: %w", name, errUntagDigest)
 	}
 

common/libimage/import.go

@@ -11,9 +11,11 @@ import (
 
 	v1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/sirupsen/logrus"
+	"go.podman.io/common/pkg/digestutils"
 	"go.podman.io/common/pkg/download"
 	storageTransport "go.podman.io/image/v5/storage"
 	tarballTransport "go.podman.io/image/v5/tarball"
+	supportedDigests "go.podman.io/storage/pkg/supported-digests"
 )
 
 // ImportOptions allow for customizing image imports.
@@ -128,5 +130,14 @@ func (r *Runtime) Import(ctx context.Context, path string, options *ImportOption
 		}
 	}
 
-	return "sha256:" + name, nil
+	// Extract the algorithm from the getImageID result
+	// getImageID returns something like "@sha256:abc123" or "@sha512:def456"
+	// We need to preserve the algorithm that was actually used
+	if algorithm, hash := digestutils.ExtractAlgorithmFromDigest(name); algorithm != "" {
+		return algorithm + ":" + hash, nil
+	}
+
+	// Fallback to configured algorithm if we can't parse the digest
+	digestAlgorithm := supportedDigests.TmpDigestForNewObjects()
+	return digestAlgorithm.String() + ":" + name, nil
 }

common/libimage/pull.go

@@ -15,6 +15,7 @@ import (
 	ociSpec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/sirupsen/logrus"
 	"go.podman.io/common/pkg/config"
+	"go.podman.io/common/pkg/digestutils"
 	registryTransport "go.podman.io/image/v5/docker"
 	dockerArchiveTransport "go.podman.io/image/v5/docker/archive"
 	dockerDaemonTransport "go.podman.io/image/v5/docker/daemon"
@@ -26,6 +27,7 @@ import (
 	"go.podman.io/image/v5/transports/alltransports"
 	"go.podman.io/image/v5/types"
 	"go.podman.io/storage"
+	supportedDigests "go.podman.io/storage/pkg/supported-digests"
 )
 
 // PullOptions allows for customizing image pulls.
@@ -101,7 +103,7 @@ func (r *Runtime) Pull(ctx context.Context, name string, pullPolicy config.PullP
 
 		// If the image clearly refers to a local one, we can look it up directly.
 		// In fact, we need to since they are not parseable.
-		if strings.HasPrefix(name, "sha256:") || (len(name) == 64 && !strings.ContainsAny(name, "/.:@")) {
+		if digestutils.IsDigestReference(name) {
 			if pullPolicy == config.PullPolicyAlways {
 				return nil, fmt.Errorf("pull policy is always but image has been referred to by ID (%s)", name)
 			}
@@ -261,7 +263,16 @@ func (r *Runtime) copyFromDefault(ctx context.Context, ref types.ImageReference,
 			if err != nil {
 				return nil, nil, err
 			}
-			imageName = "sha256:" + storageName[1:]
+			// Extract the algorithm from the getImageID result
+			// getImageID returns something like "@sha256:abc123" or "@sha512:def456"
+			// We need to preserve the algorithm that was actually used
+			if algorithm, hash := digestutils.ExtractAlgorithmFromDigest(storageName); algorithm != "" {
+				imageName = algorithm + ":" + hash
+			} else {
+				// Fallback to configured algorithm
+				digestAlgorithm := supportedDigests.TmpDigestForNewObjects()
+				imageName = digestAlgorithm.String() + ":" + storageName[1:]
+			}
 		} else { // If the OCI-reference includes an image reference, use it
 			storageName = refName
 			imageName = storageName
@@ -280,7 +291,16 @@ func (r *Runtime) copyFromDefault(ctx context.Context, ref types.ImageReference,
 			if err != nil {
 				return nil, nil, err
 			}
-			imageName = "sha256:" + storageName[1:]
+			// Extract the algorithm from the getImageID result
+			// getImageID returns something like "@sha256:abc123" or "@sha512:def456"
+			// We need to preserve the algorithm that was actually used
+			if algorithm, hash := digestutils.ExtractAlgorithmFromDigest(storageName); algorithm != "" {
+				imageName = algorithm + ":" + hash
+			} else {
+				// Fallback to configured algorithm
+				digestAlgorithm := supportedDigests.TmpDigestForNewObjects()
+				imageName = digestAlgorithm.String() + ":" + storageName[1:]
+			}
 		default:
 			named, err := NormalizeName(storageName)
 			if err != nil {
@@ -306,7 +326,16 @@ func (r *Runtime) copyFromDefault(ctx context.Context, ref types.ImageReference,
 		if err != nil {
 			return nil, nil, err
 		}
-		imageName = "sha256:" + storageName[1:]
+		// Extract the algorithm from the getImageID result
+		// getImageID returns something like "@sha256:abc123" or "@sha512:def456"
+		// We need to preserve the algorithm that was actually used
+		if algorithm, hash := digestutils.ExtractAlgorithmFromDigest(storageName); algorithm != "" {
+			imageName = algorithm + ":" + hash
+		} else {
+			// Fallback to configured algorithm
+			digestAlgorithm := supportedDigests.TmpDigestForNewObjects()
+			imageName = digestAlgorithm.String() + ":" + storageName[1:]
+		}
 	}
 
 	// Create a storage reference.
@@ -340,8 +369,17 @@ func (r *Runtime) storageReferencesReferencesFromArchiveReader(ctx context.Conte
 		}
 		destNames = append(destNames, destName)
 		// Make sure the image can be loaded after the pull by
-		// replacing the @ with sha256:.
-		imageNames = append(imageNames, "sha256:"+destName[1:])
+		// replacing the @ with the correct algorithm.
+		// Extract the algorithm from the getImageID result
+		// getImageID returns something like "@sha256:abc123" or "@sha512:def456"
+		// We need to preserve the algorithm that was actually used
+		if algorithm, hash := digestutils.ExtractAlgorithmFromDigest(destName); algorithm != "" {
+			imageNames = append(imageNames, algorithm+":"+hash)
+		} else {
+			// Fallback to configured algorithm
+			digestAlgorithm := supportedDigests.TmpDigestForNewObjects()
+			imageNames = append(imageNames, digestAlgorithm.String()+":"+destName[1:])
+		}
 	} else {
 		for i := range destNames {
 			ref, err := NormalizeName(destNames[i])

common/libimage/runtime.go

@@ -16,6 +16,7 @@ import (
 	"go.podman.io/common/libimage/define"
 	"go.podman.io/common/libimage/platform"
 	"go.podman.io/common/pkg/config"
+	"go.podman.io/common/pkg/digestutils"
 	"go.podman.io/image/v5/docker/reference"
 	"go.podman.io/image/v5/pkg/shortnames"
 	storageTransport "go.podman.io/image/v5/storage"
@@ -273,9 +274,9 @@ func (r *Runtime) LookupImage(name string, options *LookupImageOptions) (*Image,
 
 	byDigest := false
 	originalName := name
-	if strings.HasPrefix(name, "sha256:") {
+	if trimmed, found := digestutils.TrimDigestPrefix(name); found {
 		byDigest = true
-		name = strings.TrimPrefix(name, "sha256:")
+		name = trimmed
 	}
 	byFullID := reference.IsFullIdentifier(name)
 

common/pkg/digestutils/digestutils.go

@@ -0,0 +1,134 @@
+//go:build !remote
+
+package digestutils
+
+import (
+	"strings"
+
+	"github.com/opencontainers/go-digest"
+)
+
+// IsDigestReference determines if the given name is a digest-based reference.
+// This function properly detects digests using the go-digest library instead of
+// hardcoded string prefixes, avoiding conflicts with repository names like "sha256" or "sha512".
+//
+// The function supports:
+// - Standard digest formats (algorithm:hash) like "sha256:abc123..." or "sha512:def456..."
+// - Legacy 64-character hex format (SHA256 without algorithm prefix) for backward compatibility
+//
+// Examples:
+//   - "sha256:916f0027a575074ce72a331777c3478d6513f786a591bd892da1a577bf2335f9" → true
+//   - "sha512:0e1e21ecf105ec853d24d728867ad70613c21663a4693074b2a3619c1bd39d66b588c33723bb466c72424e80e3ca63c249078ab347bab9428500e7ee43059d0d" → true
+//   - "abcd1234567890abcdef1234567890abcdef1234567890abcdef1234567890ab" → true (legacy)
+//   - "sha256" → false (repository name)
+//   - "sha512:latest" → false (repository with tag)
+//   - "docker.io/sha256:latest" → false (repository with domain)
+func IsDigestReference(name string) bool {
+	// First check if it's a valid digest format (algorithm:hash)
+	if _, err := digest.Parse(name); err == nil {
+		return true
+	}
+
+	// Also check for the legacy 64-character hex format (SHA256 without algorithm prefix)
+	// This maintains backward compatibility for existing deployments
+	if len(name) == 64 && !strings.ContainsAny(name, "/.:@") {
+		// Verify it's actually hex
+		for _, c := range name {
+			if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
+				return false
+			}
+		}
+		return true
+	}
+
+	return false
+}
+
+// ExtractAlgorithmFromDigest extracts the algorithm and hash from a digest string.
+// It expects input like "@sha256:abc123" or "@sha512:def456".
+// Returns (algorithm, hash) if successful, or ("", "") if parsing fails.
+//
+// This function validates that the extracted algorithm and hash form a valid digest.
+// It is useful for preserving the algorithm that was determined by functions like getImageID,
+// rather than overriding it with a globally configured algorithm.
+//
+// Examples:
+//   - "@sha256:abc123" → ("sha256", "abc123") (if valid)
+//   - "@sha512:def456" → ("sha512", "def456") (if valid)
+//   - "sha256:abc123" → ("", "") (missing @ prefix)
+//   - "@invalid" → ("", "") (missing colon)
+//   - "@sha256:invalid" → ("", "") (invalid hash format)
+func ExtractAlgorithmFromDigest(digestStr string) (string, string) {
+	if !strings.HasPrefix(digestStr, "@") {
+		return "", ""
+	}
+
+	// Remove the "@" prefix
+	digestStr = digestStr[1:]
+
+	// Split on the first ":" to get algorithm:hash
+	parts := strings.SplitN(digestStr, ":", 2)
+	if len(parts) != 2 {
+		return "", ""
+	}
+
+	algorithm, hash := parts[0], parts[1]
+
+	// Validate that the algorithm and hash form a valid digest
+	// This ensures we only return valid digest components
+	if _, err := digest.Parse(algorithm + ":" + hash); err != nil {
+		return "", ""
+	}
+
+	return algorithm, hash
+}
+
+// HasDigestPrefix checks if a string starts with any supported digest algorithm prefix.
+// This is more scalable than hardcoding multiple HasPrefix checks for individual algorithms.
+//
+// Examples:
+//   - "sha256:abc123" → true
+//   - "sha512:def456" → true
+//   - "image:latest" → false
+//   - "registry.io/repo" → false
+func HasDigestPrefix(s string) bool {
+	// Check if the string starts with any supported digest algorithm
+	// This is more efficient than checking each algorithm individually
+	for _, prefix := range []string{"sha256:", "sha512:"} {
+		if strings.HasPrefix(s, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+// GetDigestPrefix returns the digest algorithm prefix if the string starts with one.
+// Returns the prefix (including colon) if found, empty string otherwise.
+//
+// Examples:
+//   - "sha256:abc123" → "sha256:"
+//   - "sha512:def456" → "sha512:"
+//   - "image:latest" → ""
+func GetDigestPrefix(s string) string {
+	prefixes := []string{"sha256:", "sha512:"}
+	for _, prefix := range prefixes {
+		if strings.HasPrefix(s, prefix) {
+			return prefix
+		}
+	}
+	return ""
+}
+
+// TrimDigestPrefix removes the digest algorithm prefix from a string if present.
+// Returns the string without the prefix and a boolean indicating if a prefix was found.
+//
+// Examples:
+//   - "sha256:abc123" → ("abc123", true)
+//   - "sha512:def456" → ("def456", true)
+//   - "image:latest" → ("image:latest", false)
+func TrimDigestPrefix(s string) (string, bool) {
+	if prefix := GetDigestPrefix(s); prefix != "" {
+		return strings.TrimPrefix(s, prefix), true
+	}
+	return s, false
+}