fix(deps): update module github.com/containers/image/v5 to v5.28.0

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

vendor/github.com/containers/image/v5/copy/compression.go

@@ -286,7 +286,8 @@ func (d *bpCompressionStepData) recordValidatedDigestData(c *copier, uploadedInf
 	if d.uploadedCompressorName != "" && d.uploadedCompressorName != internalblobinfocache.UnknownCompression {
 		c.blobInfoCache.RecordDigestCompressorName(uploadedInfo.Digest, d.uploadedCompressorName)
 	}
-	if srcInfo.Digest != "" && d.srcCompressorName != "" && d.srcCompressorName != internalblobinfocache.UnknownCompression {
+	if srcInfo.Digest != "" && srcInfo.Digest != uploadedInfo.Digest &&
+		d.srcCompressorName != "" && d.srcCompressorName != internalblobinfocache.UnknownCompression {
 		c.blobInfoCache.RecordDigestCompressorName(srcInfo.Digest, d.srcCompressorName)
 	}
 	return nil

vendor/github.com/containers/image/v5/copy/copy.go

@@ -242,11 +242,13 @@ func Image(ctx context.Context, policyContext *signature.PolicyContext, destRef,
 
 		unparsedToplevel: image.UnparsedInstance(rawSource, nil),
 		// FIXME? The cache is used for sources and destinations equally, but we only have a SourceCtx and DestinationCtx.
-		// For now, use DestinationCtx (because blob reuse changes the behavior of the destination side more); eventually
-		// we might want to add a separate CommonCtx — or would that be too confusing?
+		// For now, use DestinationCtx (because blob reuse changes the behavior of the destination side more).
+		// Conceptually the cache settings should be in copy.Options instead.
 		blobInfoCache: internalblobinfocache.FromBlobInfoCache(blobinfocache.DefaultCache(options.DestinationCtx)),
 	}
 	defer c.close()
+	c.blobInfoCache.Open()
+	defer c.blobInfoCache.Close()
 
 	// Set the concurrentBlobCopiesSemaphore if we can copy layers in parallel.
 	if dest.HasThreadSafePutBlob() && rawSource.HasThreadSafeGetBlob() {

vendor/github.com/containers/image/v5/copy/single.go

@@ -161,7 +161,7 @@ func (c *copier) copySingleImage(ctx context.Context, unparsedImage *image.Unpar
 		return copySingleImageResult{}, err
 	}
 
-	destRequiresOciEncryption := (isEncrypted(src) && ic.c.options.OciDecryptConfig != nil) || c.options.OciEncryptLayers != nil
+	destRequiresOciEncryption := (isEncrypted(src) && ic.c.options.OciDecryptConfig == nil) || c.options.OciEncryptLayers != nil
 
 	manifestConversionPlan, err := determineManifestConversion(determineManifestConversionInputs{
 		srcMIMEType:                    ic.src.ManifestMIMEType,
@@ -662,8 +662,12 @@ func (ic *imageCopier) copyLayer(ctx context.Context, srcInfo types.BlobInfo, to
 
 	ic.c.printCopyInfo("blob", srcInfo)
 
-	cachedDiffID := ic.c.blobInfoCache.UncompressedDigest(srcInfo.Digest) // May be ""
-	diffIDIsNeeded := ic.diffIDsAreNeeded && cachedDiffID == ""
+	diffIDIsNeeded := false
+	var cachedDiffID digest.Digest = ""
+	if ic.diffIDsAreNeeded {
+		cachedDiffID = ic.c.blobInfoCache.UncompressedDigest(srcInfo.Digest) // May be ""
+		diffIDIsNeeded = cachedDiffID == ""
+	}
 	// When encrypting to decrypting, only use the simple code path. We might be able to optimize more
 	// (e.g. if we know the DiffID of an encrypted compressed layer, it might not be necessary to pull, decrypt and decompress again),
 	// but it’s not trivially safe to do such things, so until someone takes the effort to make a comprehensive argument, let’s not.

vendor/github.com/containers/image/v5/internal/blobinfocache/blobinfocache.go

@@ -23,6 +23,12 @@ type v1OnlyBlobInfoCache struct {
 	types.BlobInfoCache
 }
 
+func (bic *v1OnlyBlobInfoCache) Open() {
+}
+
+func (bic *v1OnlyBlobInfoCache) Close() {
+}
+
 func (bic *v1OnlyBlobInfoCache) RecordDigestCompressorName(anyDigest digest.Digest, compressorName string) {
 }
 

vendor/github.com/containers/image/v5/internal/blobinfocache/types.go

@@ -18,6 +18,13 @@ const (
 // of compression was applied to the blobs it keeps information about.
 type BlobInfoCache2 interface {
 	types.BlobInfoCache
+
+	// Open() sets up the cache for future accesses, potentially acquiring costly state. Each Open() must be paired with a Close().
+	// Note that public callers may call the types.BlobInfoCache operations without Open()/Close().
+	Open()
+	// Close destroys state created by Open().
+	Close()
+
 	// RecordDigestCompressorName records a compressor for the blob with the specified digest,
 	// or Uncompressed or UnknownCompression.
 	// WARNING: Only call this with LOCALLY VERIFIED data; don’t record a compressor for a

vendor/github.com/containers/image/v5/internal/image/oci.go

@@ -12,8 +12,10 @@ import (
 	"github.com/containers/image/v5/manifest"
 	"github.com/containers/image/v5/pkg/blobinfocache/none"
 	"github.com/containers/image/v5/types"
+	ociencspec "github.com/containers/ocicrypt/spec"
 	"github.com/opencontainers/go-digest"
 	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
+	"golang.org/x/exp/slices"
 )
 
 type manifestOCI1 struct {
@@ -194,26 +196,72 @@ func (m *manifestOCI1) convertToManifestSchema2Generic(ctx context.Context, opti
 	return m.convertToManifestSchema2(ctx, options)
 }
 
+// prepareLayerDecryptEditsIfNecessary checks if options requires layer decryptions.
+// If not, it returns (nil, nil).
+// If decryption is required, it returns a set of edits to provide to OCI1.UpdateLayerInfos,
+// and edits *options to not try decryption again.
+func (m *manifestOCI1) prepareLayerDecryptEditsIfNecessary(options *types.ManifestUpdateOptions) ([]types.BlobInfo, error) {
+	if options == nil || !slices.ContainsFunc(options.LayerInfos, func(info types.BlobInfo) bool {
+		return info.CryptoOperation == types.Decrypt
+	}) {
+		return nil, nil
+	}
+
+	originalInfos := m.LayerInfos()
+	if len(originalInfos) != len(options.LayerInfos) {
+		return nil, fmt.Errorf("preparing to decrypt before conversion: %d layers vs. %d layer edits", len(originalInfos), len(options.LayerInfos))
+	}
+
+	res := slices.Clone(originalInfos) // Start with a full copy so that we don't forget to copy anything: use the current data in full unless we intentionaly deviate.
+	updatedEdits := slices.Clone(options.LayerInfos)
+	for i, info := range options.LayerInfos {
+		if info.CryptoOperation == types.Decrypt {
+			res[i].CryptoOperation = types.Decrypt
+			updatedEdits[i].CryptoOperation = types.PreserveOriginalCrypto // Don't try to decrypt in a schema[12] manifest later, that would fail.
+		}
+		// Don't do any compression-related MIME type conversions. m.LayerInfos() should not set these edit instructions, but be explicit.
+		res[i].CompressionOperation = types.PreserveOriginal
+		res[i].CompressionAlgorithm = nil
+	}
+	options.LayerInfos = updatedEdits
+	return res, nil
+}
+
 // convertToManifestSchema2 returns a genericManifest implementation converted to manifest.DockerV2Schema2MediaType.
 // It may use options.InformationOnly and also adjust *options to be appropriate for editing the returned
 // value.
 // This does not change the state of the original manifestOCI1 object.
-func (m *manifestOCI1) convertToManifestSchema2(_ context.Context, _ *types.ManifestUpdateOptions) (*manifestSchema2, error) {
+func (m *manifestOCI1) convertToManifestSchema2(_ context.Context, options *types.ManifestUpdateOptions) (*manifestSchema2, error) {
 	if m.m.Config.MediaType != imgspecv1.MediaTypeImageConfig {
 		return nil, internalManifest.NewNonImageArtifactError(&m.m.Manifest)
 	}
 
+	// Mostly we first make a format conversion, and _afterwards_ do layer edits. But first we need to do the layer edits
+	// which remove OCI-specific features, because trying to convert those layers would fail.
+	// So, do the layer updates for decryption.
+	ociManifest := m.m
+	layerDecryptEdits, err := m.prepareLayerDecryptEditsIfNecessary(options)
+	if err != nil {
+		return nil, err
+	}
+	if layerDecryptEdits != nil {
+		ociManifest = manifest.OCI1Clone(ociManifest)
+		if err := ociManifest.UpdateLayerInfos(layerDecryptEdits); err != nil {
+			return nil, err
+		}
+	}
+
 	// Create a copy of the descriptor.
-	config := schema2DescriptorFromOCI1Descriptor(m.m.Config)
+	config := schema2DescriptorFromOCI1Descriptor(ociManifest.Config)
 
 	// Above, we have already checked that this manifest refers to an image, not an OCI artifact,
 	// so the only difference between OCI and DockerSchema2 is the mediatypes. The
 	// media type of the manifest is handled by manifestSchema2FromComponents.
 	config.MediaType = manifest.DockerV2Schema2ConfigMediaType
 
-	layers := make([]manifest.Schema2Descriptor, len(m.m.Layers))
+	layers := make([]manifest.Schema2Descriptor, len(ociManifest.Layers))
 	for idx := range layers {
-		layers[idx] = schema2DescriptorFromOCI1Descriptor(m.m.Layers[idx])
+		layers[idx] = schema2DescriptorFromOCI1Descriptor(ociManifest.Layers[idx])
 		switch layers[idx].MediaType {
 		case imgspecv1.MediaTypeImageLayerNonDistributable: //nolint:staticcheck // NonDistributable layers are deprecated, but we want to continue to support manipulating pre-existing images.
 			layers[idx].MediaType = manifest.DockerV2Schema2ForeignLayerMediaType
@@ -227,6 +275,10 @@ func (m *manifestOCI1) convertToManifestSchema2(_ context.Context, _ *types.Mani
 			layers[idx].MediaType = manifest.DockerV2Schema2LayerMediaType
 		case imgspecv1.MediaTypeImageLayerZstd:
 			return nil, fmt.Errorf("Error during manifest conversion: %q: zstd compression is not supported for docker images", layers[idx].MediaType)
+			// FIXME: s/Zsdt/Zstd/ after ocicrypt with https://github.com/containers/ocicrypt/pull/91 is released
+		case ociencspec.MediaTypeLayerEnc, ociencspec.MediaTypeLayerGzipEnc, ociencspec.MediaTypeLayerZstdEnc,
+			ociencspec.MediaTypeLayerNonDistributableEnc, ociencspec.MediaTypeLayerNonDistributableGzipEnc, ociencspec.MediaTypeLayerNonDistributableZsdtEnc:
+			return nil, fmt.Errorf("during manifest conversion: encrypted layers (%q) are not supported in docker images", layers[idx].MediaType)
 		default:
 			return nil, fmt.Errorf("Unknown media type during manifest conversion: %q", layers[idx].MediaType)
 		}

vendor/github.com/containers/image/v5/manifest/docker_schema1.go

@@ -154,6 +154,9 @@ func (m *Schema1) UpdateLayerInfos(layerInfos []types.BlobInfo) error {
 		// but (docker pull) ignores them in favor of computing DiffIDs from uncompressed data, except verifying the child->parent links and uniqueness.
 		// So, we don't bother recomputing the IDs in m.History.V1Compatibility.
 		m.FSLayers[(len(layerInfos)-1)-i].BlobSum = info.Digest
+		if info.CryptoOperation != types.PreserveOriginalCrypto {
+			return fmt.Errorf("encryption change (for layer %q) is not supported in schema1 manifests", info.Digest)
+		}
 	}
 	return nil
 }

vendor/github.com/containers/image/v5/manifest/docker_schema2.go

@@ -247,6 +247,9 @@ func (m *Schema2) UpdateLayerInfos(layerInfos []types.BlobInfo) error {
 		m.LayersDescriptors[i].Digest = info.Digest
 		m.LayersDescriptors[i].Size = info.Size
 		m.LayersDescriptors[i].URLs = info.URLs
+		if info.CryptoOperation != types.PreserveOriginalCrypto {
+			return fmt.Errorf("encryption change (for layer %q) is not supported in schema2 manifests", info.Digest)
+		}
 	}
 	return nil
 }

vendor/github.com/containers/image/v5/pkg/blobinfocache/boltdb/boltdb.go

@@ -1,393 +0,0 @@
-// Package boltdb implements a BlobInfoCache backed by BoltDB.
-package boltdb
-
-import (
-	"fmt"
-	"os"
-	"sync"
-	"time"
-
-	"github.com/containers/image/v5/internal/blobinfocache"
-	"github.com/containers/image/v5/pkg/blobinfocache/internal/prioritize"
-	"github.com/containers/image/v5/types"
-	"github.com/opencontainers/go-digest"
-	"github.com/sirupsen/logrus"
-	bolt "go.etcd.io/bbolt"
-)
-
-var (
-	// NOTE: There is no versioning data inside the file; this is a “cache”, so on an incompatible format upgrade
-	// we can simply start over with a different filename; update blobInfoCacheFilename.
-
-	// FIXME: For CRI-O, does this need to hide information between different users?
-
-	// uncompressedDigestBucket stores a mapping from any digest to an uncompressed digest.
-	uncompressedDigestBucket = []byte("uncompressedDigest")
-	// digestCompressorBucket stores a mapping from any digest to a compressor, or blobinfocache.Uncompressed
-	// It may not exist in caches created by older versions, even if uncompressedDigestBucket is present.
-	digestCompressorBucket = []byte("digestCompressor")
-	// digestByUncompressedBucket stores a bucket per uncompressed digest, with the bucket containing a set of digests for that uncompressed digest
-	// (as a set of key=digest, value="" pairs)
-	digestByUncompressedBucket = []byte("digestByUncompressed")
-	// knownLocationsBucket stores a nested structure of buckets, keyed by (transport name, scope string, blob digest), ultimately containing
-	// a bucket of (opaque location reference, BinaryMarshaller-encoded time.Time value).
-	knownLocationsBucket = []byte("knownLocations")
-)
-
-// Concurrency:
-// See https://www.sqlite.org/src/artifact/c230a7a24?ln=994-1081 for all the issues with locks, which make it extremely
-// difficult to use a single BoltDB file from multiple threads/goroutines inside a process.  So, we punt and only allow one at a time.
-
-// pathLock contains a lock for a specific BoltDB database path.
-type pathLock struct {
-	refCount int64      // Number of threads/goroutines owning or waiting on this lock.  Protected by global pathLocksMutex, NOT by the mutex field below!
-	mutex    sync.Mutex // Owned by the thread/goroutine allowed to access the BoltDB database.
-}
-
-var (
-	// pathLocks contains a lock for each currently open file.
-	// This must be global so that independently created instances of boltDBCache exclude each other.
-	// The map is protected by pathLocksMutex.
-	// FIXME? Should this be based on device:inode numbers instead of paths instead?
-	pathLocks      = map[string]*pathLock{}
-	pathLocksMutex = sync.Mutex{}
-)
-
-// lockPath obtains the pathLock for path.
-// The caller must call unlockPath eventually.
-func lockPath(path string) {
-	pl := func() *pathLock { // A scope for defer
-		pathLocksMutex.Lock()
-		defer pathLocksMutex.Unlock()
-		pl, ok := pathLocks[path]
-		if ok {
-			pl.refCount++
-		} else {
-			pl = &pathLock{refCount: 1, mutex: sync.Mutex{}}
-			pathLocks[path] = pl
-		}
-		return pl
-	}()
-	pl.mutex.Lock()
-}
-
-// unlockPath releases the pathLock for path.
-func unlockPath(path string) {
-	pathLocksMutex.Lock()
-	defer pathLocksMutex.Unlock()
-	pl, ok := pathLocks[path]
-	if !ok {
-		// Should this return an error instead? BlobInfoCache ultimately ignores errors…
-		panic(fmt.Sprintf("Internal error: unlocking nonexistent lock for path %s", path))
-	}
-	pl.mutex.Unlock()
-	pl.refCount--
-	if pl.refCount == 0 {
-		delete(pathLocks, path)
-	}
-}
-
-// cache is a BlobInfoCache implementation which uses a BoltDB file at the specified path.
-//
-// Note that we don’t keep the database open across operations, because that would lock the file and block any other
-// users; instead, we need to open/close it for every single write or lookup.
-type cache struct {
-	path string
-}
-
-// New returns a BlobInfoCache implementation which uses a BoltDB file at path.
-//
-// Most users should call blobinfocache.DefaultCache instead.
-func New(path string) types.BlobInfoCache {
-	return new2(path)
-}
-func new2(path string) *cache {
-	return &cache{path: path}
-}
-
-// view returns runs the specified fn within a read-only transaction on the database.
-func (bdc *cache) view(fn func(tx *bolt.Tx) error) (retErr error) {
-	// bolt.Open(bdc.path, 0600, &bolt.Options{ReadOnly: true}) will, if the file does not exist,
-	// nevertheless create it, but with an O_RDONLY file descriptor, try to initialize it, and fail — while holding
-	// a read lock, blocking any future writes.
-	// Hence this preliminary check, which is RACY: Another process could remove the file
-	// between the Lstat call and opening the database.
-	if _, err := os.Lstat(bdc.path); err != nil && os.IsNotExist(err) {
-		return err
-	}
-
-	lockPath(bdc.path)
-	defer unlockPath(bdc.path)
-	db, err := bolt.Open(bdc.path, 0600, &bolt.Options{ReadOnly: true})
-	if err != nil {
-		return err
-	}
-	defer func() {
-		if err := db.Close(); retErr == nil && err != nil {
-			retErr = err
-		}
-	}()
-
-	return db.View(fn)
-}
-
-// update returns runs the specified fn within a read-write transaction on the database.
-func (bdc *cache) update(fn func(tx *bolt.Tx) error) (retErr error) {
-	lockPath(bdc.path)
-	defer unlockPath(bdc.path)
-	db, err := bolt.Open(bdc.path, 0600, nil)
-	if err != nil {
-		return err
-	}
-	defer func() {
-		if err := db.Close(); retErr == nil && err != nil {
-			retErr = err
-		}
-	}()
-
-	return db.Update(fn)
-}
-
-// uncompressedDigest implements BlobInfoCache.UncompressedDigest within the provided read-only transaction.
-func (bdc *cache) uncompressedDigest(tx *bolt.Tx, anyDigest digest.Digest) digest.Digest {
-	if b := tx.Bucket(uncompressedDigestBucket); b != nil {
-		if uncompressedBytes := b.Get([]byte(anyDigest.String())); uncompressedBytes != nil {
-			d, err := digest.Parse(string(uncompressedBytes))
-			if err == nil {
-				return d
-			}
-			// FIXME? Log err (but throttle the log volume on repeated accesses)?
-		}
-	}
-	// Presence in digestsByUncompressedBucket implies that anyDigest must already refer to an uncompressed digest.
-	// This way we don't have to waste storage space with trivial (uncompressed, uncompressed) mappings
-	// when we already record a (compressed, uncompressed) pair.
-	if b := tx.Bucket(digestByUncompressedBucket); b != nil {
-		if b = b.Bucket([]byte(anyDigest.String())); b != nil {
-			c := b.Cursor()
-			if k, _ := c.First(); k != nil { // The bucket is non-empty
-				return anyDigest
-			}
-		}
-	}
-	return ""
-}
-
-// UncompressedDigest returns an uncompressed digest corresponding to anyDigest.
-// May return anyDigest if it is known to be uncompressed.
-// Returns "" if nothing is known about the digest (it may be compressed or uncompressed).
-func (bdc *cache) UncompressedDigest(anyDigest digest.Digest) digest.Digest {
-	var res digest.Digest
-	if err := bdc.view(func(tx *bolt.Tx) error {
-		res = bdc.uncompressedDigest(tx, anyDigest)
-		return nil
-	}); err != nil { // Including os.IsNotExist(err)
-		return "" // FIXME? Log err (but throttle the log volume on repeated accesses)?
-	}
-	return res
-}
-
-// RecordDigestUncompressedPair records that the uncompressed version of anyDigest is uncompressed.
-// It’s allowed for anyDigest == uncompressed.
-// WARNING: Only call this for LOCALLY VERIFIED data; don’t record a digest pair just because some remote author claims so (e.g.
-// because a manifest/config pair exists); otherwise the cache could be poisoned and allow substituting unexpected blobs.
-// (Eventually, the DiffIDs in image config could detect the substitution, but that may be too late, and not all image formats contain that data.)
-func (bdc *cache) RecordDigestUncompressedPair(anyDigest digest.Digest, uncompressed digest.Digest) {
-	_ = bdc.update(func(tx *bolt.Tx) error {
-		b, err := tx.CreateBucketIfNotExists(uncompressedDigestBucket)
-		if err != nil {
-			return err
-		}
-		key := []byte(anyDigest.String())
-		if previousBytes := b.Get(key); previousBytes != nil {
-			previous, err := digest.Parse(string(previousBytes))
-			if err != nil {
-				return err
-			}
-			if previous != uncompressed {
-				logrus.Warnf("Uncompressed digest for blob %s previously recorded as %s, now %s", anyDigest, previous, uncompressed)
-			}
-		}
-		if err := b.Put(key, []byte(uncompressed.String())); err != nil {
-			return err
-		}
-
-		b, err = tx.CreateBucketIfNotExists(digestByUncompressedBucket)
-		if err != nil {
-			return err
-		}
-		b, err = b.CreateBucketIfNotExists([]byte(uncompressed.String()))
-		if err != nil {
-			return err
-		}
-		if err := b.Put([]byte(anyDigest.String()), []byte{}); err != nil { // Possibly writing the same []byte{} presence marker again.
-			return err
-		}
-		return nil
-	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
-}
-
-// RecordDigestCompressorName records that the blob with digest anyDigest was compressed with the specified
-// compressor, or is blobinfocache.Uncompressed.
-// WARNING: Only call this for LOCALLY VERIFIED data; don’t record a digest pair just because some remote author claims so (e.g.
-// because a manifest/config pair exists); otherwise the cache could be poisoned and allow substituting unexpected blobs.
-// (Eventually, the DiffIDs in image config could detect the substitution, but that may be too late, and not all image formats contain that data.)
-func (bdc *cache) RecordDigestCompressorName(anyDigest digest.Digest, compressorName string) {
-	_ = bdc.update(func(tx *bolt.Tx) error {
-		b, err := tx.CreateBucketIfNotExists(digestCompressorBucket)
-		if err != nil {
-			return err
-		}
-		key := []byte(anyDigest.String())
-		if previousBytes := b.Get(key); previousBytes != nil {
-			if string(previousBytes) != compressorName {
-				logrus.Warnf("Compressor for blob with digest %s previously recorded as %s, now %s", anyDigest, string(previousBytes), compressorName)
-			}
-		}
-		if compressorName == blobinfocache.UnknownCompression {
-			return b.Delete(key)
-		}
-		return b.Put(key, []byte(compressorName))
-	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
-}
-
-// RecordKnownLocation records that a blob with the specified digest exists within the specified (transport, scope) scope,
-// and can be reused given the opaque location data.
-func (bdc *cache) RecordKnownLocation(transport types.ImageTransport, scope types.BICTransportScope, blobDigest digest.Digest, location types.BICLocationReference) {
-	_ = bdc.update(func(tx *bolt.Tx) error {
-		b, err := tx.CreateBucketIfNotExists(knownLocationsBucket)
-		if err != nil {
-			return err
-		}
-		b, err = b.CreateBucketIfNotExists([]byte(transport.Name()))
-		if err != nil {
-			return err
-		}
-		b, err = b.CreateBucketIfNotExists([]byte(scope.Opaque))
-		if err != nil {
-			return err
-		}
-		b, err = b.CreateBucketIfNotExists([]byte(blobDigest.String()))
-		if err != nil {
-			return err
-		}
-		value, err := time.Now().MarshalBinary()
-		if err != nil {
-			return err
-		}
-		if err := b.Put([]byte(location.Opaque), value); err != nil { // Possibly overwriting an older entry.
-			return err
-		}
-		return nil
-	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
-}
-
-// appendReplacementCandidates creates prioritize.CandidateWithTime values for digest in scopeBucket with corresponding compression info from compressionBucket (if compressionBucket is not nil), and returns the result of appending them to candidates.
-func (bdc *cache) appendReplacementCandidates(candidates []prioritize.CandidateWithTime, scopeBucket, compressionBucket *bolt.Bucket, digest digest.Digest, requireCompressionInfo bool) []prioritize.CandidateWithTime {
-	digestKey := []byte(digest.String())
-	b := scopeBucket.Bucket(digestKey)
-	if b == nil {
-		return candidates
-	}
-	compressorName := blobinfocache.UnknownCompression
-	if compressionBucket != nil {
-		// the bucket won't exist if the cache was created by a v1 implementation and
-		// hasn't yet been updated by a v2 implementation
-		if compressorNameValue := compressionBucket.Get(digestKey); len(compressorNameValue) > 0 {
-			compressorName = string(compressorNameValue)
-		}
-	}
-	if compressorName == blobinfocache.UnknownCompression && requireCompressionInfo {
-		return candidates
-	}
-	_ = b.ForEach(func(k, v []byte) error {
-		t := time.Time{}
-		if err := t.UnmarshalBinary(v); err != nil {
-			return err
-		}
-		candidates = append(candidates, prioritize.CandidateWithTime{
-			Candidate: blobinfocache.BICReplacementCandidate2{
-				Digest:         digest,
-				CompressorName: compressorName,
-				Location:       types.BICLocationReference{Opaque: string(k)},
-			},
-			LastSeen: t,
-		})
-		return nil
-	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
-	return candidates
-}
-
-// CandidateLocations2 returns a prioritized, limited, number of blobs and their locations that could possibly be reused
-// within the specified (transport scope) (if they still exist, which is not guaranteed).
-//
-// If !canSubstitute, the returned candidates will match the submitted digest exactly; if canSubstitute,
-// data from previous RecordDigestUncompressedPair calls is used to also look up variants of the blob which have the same
-// uncompressed digest.
-func (bdc *cache) CandidateLocations2(transport types.ImageTransport, scope types.BICTransportScope, primaryDigest digest.Digest, canSubstitute bool) []blobinfocache.BICReplacementCandidate2 {
-	return bdc.candidateLocations(transport, scope, primaryDigest, canSubstitute, true)
-}
-
-func (bdc *cache) candidateLocations(transport types.ImageTransport, scope types.BICTransportScope, primaryDigest digest.Digest, canSubstitute, requireCompressionInfo bool) []blobinfocache.BICReplacementCandidate2 {
-	res := []prioritize.CandidateWithTime{}
-	var uncompressedDigestValue digest.Digest // = ""
-	if err := bdc.view(func(tx *bolt.Tx) error {
-		scopeBucket := tx.Bucket(knownLocationsBucket)
-		if scopeBucket == nil {
-			return nil
-		}
-		scopeBucket = scopeBucket.Bucket([]byte(transport.Name()))
-		if scopeBucket == nil {
-			return nil
-		}
-		scopeBucket = scopeBucket.Bucket([]byte(scope.Opaque))
-		if scopeBucket == nil {
-			return nil
-		}
-		// compressionBucket won't have been created if previous writers never recorded info about compression,
-		// and we don't want to fail just because of that
-		compressionBucket := tx.Bucket(digestCompressorBucket)
-
-		res = bdc.appendReplacementCandidates(res, scopeBucket, compressionBucket, primaryDigest, requireCompressionInfo)
-		if canSubstitute {
-			if uncompressedDigestValue = bdc.uncompressedDigest(tx, primaryDigest); uncompressedDigestValue != "" {
-				b := tx.Bucket(digestByUncompressedBucket)
-				if b != nil {
-					b = b.Bucket([]byte(uncompressedDigestValue.String()))
-					if b != nil {
-						if err := b.ForEach(func(k, _ []byte) error {
-							d, err := digest.Parse(string(k))
-							if err != nil {
-								return err
-							}
-							if d != primaryDigest && d != uncompressedDigestValue {
-								res = bdc.appendReplacementCandidates(res, scopeBucket, compressionBucket, d, requireCompressionInfo)
-							}
-							return nil
-						}); err != nil {
-							return err
-						}
-					}
-				}
-				if uncompressedDigestValue != primaryDigest {
-					res = bdc.appendReplacementCandidates(res, scopeBucket, compressionBucket, uncompressedDigestValue, requireCompressionInfo)
-				}
-			}
-		}
-		return nil
-	}); err != nil { // Including os.IsNotExist(err)
-		return []blobinfocache.BICReplacementCandidate2{} // FIXME? Log err (but throttle the log volume on repeated accesses)?
-	}
-
-	return prioritize.DestructivelyPrioritizeReplacementCandidates(res, primaryDigest, uncompressedDigestValue)
-}
-
-// CandidateLocations returns a prioritized, limited, number of blobs and their locations that could possibly be reused
-// within the specified (transport scope) (if they still exist, which is not guaranteed).
-//
-// If !canSubstitute, the returned cadidates will match the submitted digest exactly; if canSubstitute,
-// data from previous RecordDigestUncompressedPair calls is used to also look up variants of the blob which have the same
-// uncompressed digest.
-func (bdc *cache) CandidateLocations(transport types.ImageTransport, scope types.BICTransportScope, primaryDigest digest.Digest, canSubstitute bool) []types.BICReplacementCandidate {
-	return blobinfocache.CandidateLocationsFromV2(bdc.candidateLocations(transport, scope, primaryDigest, canSubstitute, false))
-}

vendor/github.com/containers/image/v5/pkg/blobinfocache/default.go

@@ -6,8 +6,8 @@ import (
 	"path/filepath"
 
 	"github.com/containers/image/v5/internal/rootless"
-	"github.com/containers/image/v5/pkg/blobinfocache/boltdb"
 	"github.com/containers/image/v5/pkg/blobinfocache/memory"
+	"github.com/containers/image/v5/pkg/blobinfocache/sqlite"
 	"github.com/containers/image/v5/types"
 	"github.com/sirupsen/logrus"
 )
@@ -15,7 +15,7 @@ import (
 const (
 	// blobInfoCacheFilename is the file name used for blob info caches.
 	// If the format changes in an incompatible way, increase the version number.
-	blobInfoCacheFilename = "blob-info-cache-v1.boltdb"
+	blobInfoCacheFilename = "blob-info-cache-v1.sqlite"
 	// systemBlobInfoCacheDir is the directory containing the blob info cache (in blobInfocacheFilename) for root-running processes.
 	systemBlobInfoCacheDir = "/var/lib/containers/cache"
 )
@@ -57,10 +57,20 @@ func DefaultCache(sys *types.SystemContext) types.BlobInfoCache {
 	}
 	path := filepath.Join(dir, blobInfoCacheFilename)
 	if err := os.MkdirAll(dir, 0700); err != nil {
-		logrus.Debugf("Error creating parent directories for %s, using a memory-only cache: %v", blobInfoCacheFilename, err)
+		logrus.Debugf("Error creating parent directories for %s, using a memory-only cache: %v", path, err)
 		return memory.New()
 	}
 
-	logrus.Debugf("Using blob info cache at %s", path)
-	return boltdb.New(path)
+	// It might make sense to keep a single sqlite cache object, and a single initialized sqlite connection, open
+	// as global singleton, for the vast majority of callers who don’t override thde cache location.
+	// OTOH that would keep a file descriptor open forever, even for long-term callers who copy images rarely,
+	// and the performance benefit to this over using an Open()/Close() pair for a single image copy is < 10%.
+
+	cache, err := sqlite.New(path)
+	if err != nil {
+		logrus.Debugf("Error creating a SQLite blob info cache at %s, using a memory-only cache: %v", path, err)
+		return memory.New()
+	}
+	logrus.Debugf("Using SQLite blob info cache at %s", path)
+	return cache
 }

vendor/github.com/containers/image/v5/pkg/blobinfocache/memory/memory.go

@@ -27,7 +27,7 @@ type cache struct {
 	uncompressedDigests   map[digest.Digest]digest.Digest
 	digestsByUncompressed map[digest.Digest]*set.Set[digest.Digest]                // stores a set of digests for each uncompressed digest
 	knownLocations        map[locationKey]map[types.BICLocationReference]time.Time // stores last known existence time for each location reference
-	compressors           map[digest.Digest]string                                 // stores a compressor name, or blobinfocache.Unknown, for each digest
+	compressors           map[digest.Digest]string                                 // stores a compressor name, or blobinfocache.Unknown (not blobinfocache.UnknownCompression), for each digest
 }
 
 // New returns a BlobInfoCache implementation which is in-memory only.
@@ -51,6 +51,15 @@ func new2() *cache {
 	}
 }
 
+// Open() sets up the cache for future accesses, potentially acquiring costly state. Each Open() must be paired with a Close().
+// Note that public callers may call the types.BlobInfoCache operations without Open()/Close().
+func (mem *cache) Open() {
+}
+
+// Close destroys state created by Open().
+func (mem *cache) Close() {
+}
+
 // UncompressedDigest returns an uncompressed digest corresponding to anyDigest.
 // May return anyDigest if it is known to be uncompressed.
 // Returns "" if nothing is known about the digest (it may be compressed or uncompressed).
@@ -114,6 +123,9 @@ func (mem *cache) RecordKnownLocation(transport types.ImageTransport, scope type
 func (mem *cache) RecordDigestCompressorName(blobDigest digest.Digest, compressorName string) {
 	mem.mutex.Lock()
 	defer mem.mutex.Unlock()
+	if previous, ok := mem.compressors[blobDigest]; ok && previous != compressorName {
+		logrus.Warnf("Compressor for blob with digest %s previously recorded as %s, now %s", blobDigest, previous, compressorName)
+	}
 	if compressorName == blobinfocache.UnknownCompression {
 		delete(mem.compressors, blobDigest)
 		return

vendor/github.com/containers/image/v5/pkg/blobinfocache/sqlite/sqlite.go

@@ -0,0 +1,553 @@
+// Package boltdb implements a BlobInfoCache backed by SQLite.
+package sqlite
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/containers/image/v5/internal/blobinfocache"
+	"github.com/containers/image/v5/pkg/blobinfocache/internal/prioritize"
+	"github.com/containers/image/v5/types"
+	_ "github.com/mattn/go-sqlite3" // Registers the "sqlite3" backend backend for database/sql
+	"github.com/opencontainers/go-digest"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	// NOTE: There is no versioning data inside the file; this is a “cache”, so on an incompatible format upgrade
+	// we can simply start over with a different filename; update blobInfoCacheFilename.
+	// That also means we don’t have to worry about co-existing readers/writers which know different versions of the schema
+	// (which would require compatibility in both directions).
+
+	// Assembled sqlite options used when opening the database.
+	sqliteOptions = "?" +
+		// Deal with timezone automatically.
+		// go-sqlite3 always _records_ timestamps as a text: time in local time + a time zone offset.
+		// _loc affects how the values are _parsed_: (which timezone is assumed for numeric timestamps or for text which does not specify an offset, or)
+		// if the time zone offset matches the specified time zone, the timestamp is assumed to be in that time zone / location;
+		// (otherwise an unnamed time zone carrying just a hard-coded offset, but no location / DST rules is used).
+		"_loc=auto" +
+		// Force an fsync after each transaction (https://www.sqlite.org/pragma.html#pragma_synchronous).
+		"&_sync=FULL" +
+		// Allow foreign keys (https://www.sqlite.org/pragma.html#pragma_foreign_keys).
+		// We don’t currently use any foreign keys, but this is a good choice long-term (not default in SQLite only for historical reasons).
+		"&_foreign_keys=1" +
+		// Use BEGIN EXCLUSIVE (https://www.sqlite.org/lang_transaction.html);
+		// i.e. obtain a write lock for _all_ transactions at the transaction start (never use a read lock,
+		// never upgrade from a read to a write lock - that can fail if multiple read lock owners try to do that simultaneously).
+		//
+		// This, together with go-sqlite3’s default for _busy_timeout=5000, means that we should never see a “database is locked” error,
+		// the database should block on the exclusive lock when starting a transaction, and the problematic case of two simultaneous
+		// holders of a read lock trying to upgrade to a write lock (and one necessarily failing) is prevented.
+		// Compare https://github.com/mattn/go-sqlite3/issues/274 .
+		//
+		// Ideally the BEGIN / BEGIN EXCLUSIVE decision could be made per-transaction, compare https://github.com/mattn/go-sqlite3/pull/1167
+		// or https://github.com/mattn/go-sqlite3/issues/400 .
+		// The currently-proposed  workaround is to create two different SQL “databases” (= connection pools) with different _txlock settings,
+		// which seems rather wasteful.
+		"&_txlock=exclusive"
+)
+
+// cache is a BlobInfoCache implementation which uses a SQLite file at the specified path.
+type cache struct {
+	path string
+
+	// The database/sql package says “It is rarely necessary to close a DB.”, and steers towards a long-term *sql.DB connection pool.
+	// That’s probably very applicable for database-backed services, where the database is the primary data store. That’s not necessarily
+	// the case for callers of c/image, where image operations might be a small proportion of hte total runtime, and the cache is fairly
+	// incidental even to the image operations. It’s also hard for us to use that model, because the public BlobInfoCache object doesn’t have
+	// a Close method, so creating a lot of single-use caches could leak data.
+	//
+	// Instead, the private BlobInfoCache2 interface provides Open/Close methods, and they are called by c/image/copy.Image.
+	// This amortizes the cost of opening/closing the SQLite state over a single image copy, while keeping no long-term resources open.
+	// Some rough benchmarks in https://github.com/containers/image/pull/2092 suggest relative costs on the order of "25" for a single
+	// *sql.DB left open long-term, "27" for a *sql.DB open for a single image copy, and "40" for opening/closing a *sql.DB for every
+	// single transaction; so the Open/Close per image copy seems a reasonable compromise (especially compared to the previous implementation,
+	// somewhere around "700").
+
+	lock sync.Mutex
+	// The following fields can only be accessed with lock held.
+	refCount int     // number of outstanding Open() calls
+	db       *sql.DB // nil if not set (may happen even if refCount > 0 on errors)
+}
+
+// New returns BlobInfoCache implementation which uses a SQLite file at path.
+//
+// Most users should call blobinfocache.DefaultCache instead.
+func New(path string) (types.BlobInfoCache, error) {
+	return new2(path)
+}
+
+func new2(path string) (*cache, error) {
+	db, err := rawOpen(path)
+	if err != nil {
+		return nil, fmt.Errorf("initializing blob info cache at %q: %w", path, err)
+	}
+	defer db.Close()
+
+	// We don’t check the schema before every operation, because that would be costly
+	// and because we assume schema changes will be handled by using a different path.
+	if err := ensureDBHasCurrentSchema(db); err != nil {
+		return nil, err
+	}
+
+	return &cache{
+		path:     path,
+		refCount: 0,
+		db:       nil,
+	}, nil
+}
+
+// rawOpen returns a new *sql.DB for path.
+// The caller should arrange for it to be .Close()d.
+func rawOpen(path string) (*sql.DB, error) {
+	// This exists to centralize the use of sqliteOptions.
+	return sql.Open("sqlite3", path+sqliteOptions)
+}
+
+// Open() sets up the cache for future accesses, potentially acquiring costly state. Each Open() must be paired with a Close().
+// Note that public callers may call the types.BlobInfoCache operations without Open()/Close().
+func (sqc *cache) Open() {
+	sqc.lock.Lock()
+	defer sqc.lock.Unlock()
+
+	if sqc.refCount == 0 {
+		db, err := rawOpen(sqc.path)
+		if err != nil {
+			logrus.Warnf("Error opening (previously-succesfully-opened) blob info cache at %q: %v", sqc.path, err)
+			db = nil // But still increase sqc.refCount, because a .Close() will happen
+		}
+		sqc.db = db
+	}
+	sqc.refCount++
+}
+
+// Close destroys state created by Open().
+func (sqc *cache) Close() {
+	sqc.lock.Lock()
+	defer sqc.lock.Unlock()
+
+	switch sqc.refCount {
+	case 0:
+		logrus.Errorf("internal error using pkg/blobinfocache/sqlite.cache: Close() without a matching Open()")
+		return
+	case 1:
+		if sqc.db != nil {
+			sqc.db.Close()
+			sqc.db = nil
+		}
+	}
+	sqc.refCount--
+}
+
+type void struct{} // So that we don’t have to write struct{}{} all over the place
+
+// transaction calls fn within a read-write transaction in sqc.
+func transaction[T any](sqc *cache, fn func(tx *sql.Tx) (T, error)) (T, error) {
+	db, closeDB, err := func() (*sql.DB, func(), error) { // A scope for defer
+		sqc.lock.Lock()
+		defer sqc.lock.Unlock()
+
+		if sqc.db != nil {
+			return sqc.db, func() {}, nil
+		}
+		db, err := rawOpen(sqc.path)
+		if err != nil {
+			return nil, nil, fmt.Errorf("opening blob info cache at %q: %w", sqc.path, err)
+		}
+		return db, func() { db.Close() }, nil
+	}()
+	if err != nil {
+		var zeroRes T // A zero value of T
+		return zeroRes, err
+	}
+	defer closeDB()
+
+	return dbTransaction(db, fn)
+}
+
+// dbTransaction calls fn within a read-write transaction in db.
+func dbTransaction[T any](db *sql.DB, fn func(tx *sql.Tx) (T, error)) (T, error) {
+	// Ideally we should be able to distinguish between read-only and read-write transctions, see the _txlock=exclusive dicussion.
+
+	var zeroRes T // A zero value of T
+
+	tx, err := db.Begin()
+	if err != nil {
+		return zeroRes, fmt.Errorf("beginning transaction: %w", err)
+	}
+	succeeded := false
+	defer func() {
+		if !succeeded {
+			if err := tx.Rollback(); err != nil {
+				logrus.Errorf("Rolling back transaction: %v", err)
+			}
+		}
+	}()
+
+	res, err := fn(tx)
+	if err != nil {
+		return zeroRes, err
+	}
+	if err := tx.Commit(); err != nil {
+		return zeroRes, fmt.Errorf("committing transaction: %w", err)
+	}
+
+	succeeded = true
+	return res, nil
+}
+
+// querySingleValue executes a SELECT which is expected to return at most one row with a single column.
+// It returns (value, true, nil) on success, or (value, false, nil) if no row was returned.
+func querySingleValue[T any](tx *sql.Tx, query string, params ...any) (T, bool, error) {
+	var value T
+	if err := tx.QueryRow(query, params...).Scan(&value); err != nil {
+		var zeroValue T // A zero value of T
+		if errors.Is(err, sql.ErrNoRows) {
+			return zeroValue, false, nil
+		}
+		return zeroValue, false, err
+	}
+	return value, true, nil
+}
+
+// ensureDBHasCurrentSchema adds the necessary tables and indices to a database.
+// This is typically used when creating a previously-nonexistent database.
+// We don’t really anticipate schema migrations; with c/image usually vendored, not using
+// shared libraries, migrating a schema on an existing database would affect old-version users.
+// Instead, schema changes are likely to be implemented by using a different cache file name,
+// and leaving existing caches around for old users.
+func ensureDBHasCurrentSchema(db *sql.DB) error {
+	// Considered schema design alternatives:
+	//
+	// (Overall, considering the overall network latency and disk I/O costs of many-megabyte layer pulls which are happening while referring
+	// to the blob info cache, it seems reasonable to prioritize readability over microoptimization of this database.)
+	//
+	// * This schema uses the text representation of digests.
+	//
+	//   We use the fairly wasteful text with hexadecimal digits because digest.Digest does not define a binary representation;
+	//   and the way digest.Digest.Hex() is deprecated in favor of digest.Digest.Encoded(), and the way digest.Algorithm
+	//   is documented to “define the string encoding” suggests that assuming a hexadecimal representation and turning that
+	//   into binary ourselves is not a good idea in general; we would have to special-case the currently-known algorithm
+	//   — and that would require us to implement two code paths, one of them basically never exercised / never tested.
+	//
+	// * There are two separate items for recording the uncompressed digest and digest compressors.
+	//   Alternatively, we could have a single "digest facts" table with NULLable columns.
+	//
+	//   The way the BlobInfoCache API works, we are only going to write one value at a time, so
+	//   sharing a table would not be any more efficient for writes (same number of lookups, larger row tuples).
+	//   Reads in candidateLocations would not be more efficient either, the searches in DigestCompressors and DigestUncompressedPairs
+	//   do not coincide (we want a compressor for every candidate, but the uncompressed digest only for the primary digest; and then
+	//   we search in DigestUncompressedPairs by uncompressed digest, not by the primary key).
+	//
+	//   Also, using separate items allows the single-item writes to be done using a simple INSERT OR REPLACE, instead of having to
+	//   do a more verbose ON CONFLICT(…) DO UPDATE SET … = ….
+	//
+	// * Joins (the two that exist in appendReplacementCandidates) are based on the text representation of digests.
+	//
+	//   Using integer primary keys might make the joins themselves a bit more efficient, but then we would need to involve an extra
+	//   join to translate from/to the user-provided digests anyway. If anything, that extra join (potentialy more btree lookups)
+	//   is probably costlier than comparing a few more bytes of data.
+	//
+	//   Perhaps more importantly, storing digest texts directly makes the database dumps much easier to read for humans without
+	//   having to do extra steps to decode the integers into digest values (either by running sqlite commands with joins, or mentally).
+	//
+	items := []struct{ itemName, command string }{
+		{
+			"DigestUncompressedPairs",
+			`CREATE TABLE IF NOT EXISTS DigestUncompressedPairs(` +
+				// index implied by PRIMARY KEY
+				`anyDigest			TEXT PRIMARY KEY NOT NULL,` +
+				// DigestUncompressedPairs_index_uncompressedDigest
+				`uncompressedDigest	TEXT NOT NULL
+			)`,
+		},
+		{
+			"DigestUncompressedPairs_index_uncompressedDigest",
+			`CREATE INDEX IF NOT EXISTS DigestUncompressedPairs_index_uncompressedDigest ON DigestUncompressedPairs(uncompressedDigest)`,
+		},
+		{
+			"DigestCompressors",
+			`CREATE TABLE IF NOT EXISTS DigestCompressors(` +
+				// index implied by PRIMARY KEY
+				`digest		TEXT PRIMARY KEY NOT NULL,` +
+				// May include blobinfocache.Uncompressed (not blobinfocache.UnknownCompression).
+				`compressor	TEXT NOT NULL
+			)`,
+		},
+		{
+			"KnownLocations",
+			`CREATE TABLE IF NOT EXISTS KnownLocations(
+				transport	TEXT NOT NULL,
+				scope 		TEXT NOT NULL,
+				digest		TEXT NOT NULL,
+				location	TEXT NOT NULL,` +
+				// TIMESTAMP is parsed by SQLITE as a NUMERIC affinity, but go-sqlite3 stores text in the (Go formatting semantics)
+				// format "2006-01-02 15:04:05.999999999-07:00".
+				// See also the _loc option in the sql.Open data source name.
+				`time		TIMESTAMP NOT NULL,` +
+				// Implies an index.
+				// We also search by (transport, scope, digest), that doesn’t need an extra index
+				// because it is a prefix of the implied primary-key index.
+				`PRIMARY KEY (transport, scope, digest, location)
+			)`,
+		},
+	}
+
+	_, err := dbTransaction(db, func(tx *sql.Tx) (void, error) {
+		// If the the last-created item exists, assume nothing needs to be done.
+		lastItemName := items[len(items)-1].itemName
+		_, found, err := querySingleValue[int](tx, "SELECT 1 FROM sqlite_schema WHERE name=?", lastItemName)
+		if err != nil {
+			return void{}, fmt.Errorf("checking if SQLite schema item %q exists: %w", lastItemName, err)
+		}
+		if !found {
+			// Item does not exist, assuming a fresh database.
+			for _, i := range items {
+				if _, err := tx.Exec(i.command); err != nil {
+					return void{}, fmt.Errorf("creating item %s: %w", i.itemName, err)
+				}
+			}
+		}
+		return void{}, nil
+	})
+	return err
+}
+
+// uncompressedDigest implements types.BlobInfoCache.UncompressedDigest within a transaction.
+func (sqc *cache) uncompressedDigest(tx *sql.Tx, anyDigest digest.Digest) (digest.Digest, error) {
+	uncompressedString, found, err := querySingleValue[string](tx, "SELECT uncompressedDigest FROM DigestUncompressedPairs WHERE anyDigest = ?", anyDigest.String())
+	if err != nil {
+		return "", err
+	}
+	if found {
+		d, err := digest.Parse(uncompressedString)
+		if err != nil {
+			return "", err
+		}
+		return d, nil
+
+	}
+	// A record as uncompressedDigest implies that anyDigest must already refer to an uncompressed digest.
+	// This way we don't have to waste storage space with trivial (uncompressed, uncompressed) mappings
+	// when we already record a (compressed, uncompressed) pair.
+	_, found, err = querySingleValue[int](tx, "SELECT 1 FROM DigestUncompressedPairs WHERE uncompressedDigest = ?", anyDigest.String())
+	if err != nil {
+		return "", err
+	}
+	if found {
+		return anyDigest, nil
+	}
+	return "", nil
+}
+
+// UncompressedDigest returns an uncompressed digest corresponding to anyDigest.
+// May return anyDigest if it is known to be uncompressed.
+// Returns "" if nothing is known about the digest (it may be compressed or uncompressed).
+func (sqc *cache) UncompressedDigest(anyDigest digest.Digest) digest.Digest {
+	res, err := transaction(sqc, func(tx *sql.Tx) (digest.Digest, error) {
+		return sqc.uncompressedDigest(tx, anyDigest)
+	})
+	if err != nil {
+		return "" // FIXME? Log err (but throttle the log volume on repeated accesses)?
+	}
+	return res
+}
+
+// RecordDigestUncompressedPair records that the uncompressed version of anyDigest is uncompressed.
+// It’s allowed for anyDigest == uncompressed.
+// WARNING: Only call this for LOCALLY VERIFIED data; don’t record a digest pair just because some remote author claims so (e.g.
+// because a manifest/config pair exists); otherwise the cache could be poisoned and allow substituting unexpected blobs.
+// (Eventually, the DiffIDs in image config could detect the substitution, but that may be too late, and not all image formats contain that data.)
+func (sqc *cache) RecordDigestUncompressedPair(anyDigest digest.Digest, uncompressed digest.Digest) {
+	_, _ = transaction(sqc, func(tx *sql.Tx) (void, error) {
+		previousString, gotPrevious, err := querySingleValue[string](tx, "SELECT uncompressedDigest FROM DigestUncompressedPairs WHERE anyDigest = ?", anyDigest.String())
+		if err != nil {
+			return void{}, fmt.Errorf("looking for uncompressed digest for %q", anyDigest)
+		}
+		if gotPrevious {
+			previous, err := digest.Parse(previousString)
+			if err != nil {
+				return void{}, err
+			}
+			if previous != uncompressed {
+				logrus.Warnf("Uncompressed digest for blob %s previously recorded as %s, now %s", anyDigest, previous, uncompressed)
+			}
+		}
+		if _, err := tx.Exec("INSERT OR REPLACE INTO DigestUncompressedPairs(anyDigest, uncompressedDigest) VALUES (?, ?)",
+			anyDigest.String(), uncompressed.String()); err != nil {
+			return void{}, fmt.Errorf("recording uncompressed digest %q for %q: %w", uncompressed, anyDigest, err)
+		}
+		return void{}, nil
+	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
+}
+
+// RecordKnownLocation records that a blob with the specified digest exists within the specified (transport, scope) scope,
+// and can be reused given the opaque location data.
+func (sqc *cache) RecordKnownLocation(transport types.ImageTransport, scope types.BICTransportScope, digest digest.Digest, location types.BICLocationReference) {
+	_, _ = transaction(sqc, func(tx *sql.Tx) (void, error) {
+		if _, err := tx.Exec("INSERT OR REPLACE INTO KnownLocations(transport, scope, digest, location, time) VALUES (?, ?, ?, ?, ?)",
+			transport.Name(), scope.Opaque, digest.String(), location.Opaque, time.Now()); err != nil { // Possibly overwriting an older entry.
+			return void{}, fmt.Errorf("recording known location %q for (%q, %q, %q): %w",
+				location.Opaque, transport.Name(), scope.Opaque, digest.String(), err)
+		}
+		return void{}, nil
+	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
+}
+
+// RecordDigestCompressorName records a compressor for the blob with the specified digest,
+// or Uncompressed or UnknownCompression.
+// WARNING: Only call this with LOCALLY VERIFIED data; don’t record a compressor for a
+// digest just because some remote author claims so (e.g. because a manifest says so);
+// otherwise the cache could be poisoned and cause us to make incorrect edits to type
+// information in a manifest.
+func (sqc *cache) RecordDigestCompressorName(anyDigest digest.Digest, compressorName string) {
+	_, _ = transaction(sqc, func(tx *sql.Tx) (void, error) {
+		previous, gotPrevious, err := querySingleValue[string](tx, "SELECT compressor FROM DigestCompressors WHERE digest = ?", anyDigest.String())
+		if err != nil {
+			return void{}, fmt.Errorf("looking for compressor of for %q", anyDigest)
+		}
+		if gotPrevious && previous != compressorName {
+			logrus.Warnf("Compressor for blob with digest %s previously recorded as %s, now %s", anyDigest, previous, compressorName)
+		}
+		if compressorName == blobinfocache.UnknownCompression {
+			if _, err := tx.Exec("DELETE FROM DigestCompressors WHERE digest = ?", anyDigest.String()); err != nil {
+				return void{}, fmt.Errorf("deleting compressor for digest %q: %w", anyDigest, err)
+			}
+		} else {
+			if _, err := tx.Exec("INSERT OR REPLACE INTO DigestCompressors(digest, compressor) VALUES (?, ?)",
+				anyDigest.String(), compressorName); err != nil {
+				return void{}, fmt.Errorf("recording compressor %q for %q: %w", compressorName, anyDigest, err)
+			}
+		}
+		return void{}, nil
+	}) // FIXME? Log error (but throttle the log volume on repeated accesses)?
+}
+
+// appendReplacementCandidates creates prioritize.CandidateWithTime values for (transport, scope, digest), and returns the result of appending them to candidates.
+func (sqc *cache) appendReplacementCandidates(candidates []prioritize.CandidateWithTime, tx *sql.Tx, transport types.ImageTransport, scope types.BICTransportScope, digest digest.Digest, requireCompressionInfo bool) ([]prioritize.CandidateWithTime, error) {
+	var rows *sql.Rows
+	var err error
+	if requireCompressionInfo {
+		rows, err = tx.Query("SELECT location, time, compressor FROM KnownLocations JOIN DigestCompressors "+
+			"ON KnownLocations.digest = DigestCompressors.digest "+
+			"WHERE transport = ? AND scope = ? AND KnownLocations.digest = ?",
+			transport.Name(), scope.Opaque, digest.String())
+	} else {
+		rows, err = tx.Query("SELECT location, time, IFNULL(compressor, ?) FROM KnownLocations "+
+			"LEFT JOIN DigestCompressors ON KnownLocations.digest = DigestCompressors.digest "+
+			"WHERE transport = ? AND scope = ? AND KnownLocations.digest = ?",
+			blobinfocache.UnknownCompression,
+			transport.Name(), scope.Opaque, digest.String())
+	}
+	if err != nil {
+		return nil, fmt.Errorf("looking up candidate locations: %w", err)
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var location string
+		var time time.Time
+		var compressorName string
+		if err := rows.Scan(&location, &time, &compressorName); err != nil {
+			return nil, fmt.Errorf("scanning candidate: %w", err)
+		}
+		candidates = append(candidates, prioritize.CandidateWithTime{
+			Candidate: blobinfocache.BICReplacementCandidate2{
+				Digest:         digest,
+				CompressorName: compressorName,
+				Location:       types.BICLocationReference{Opaque: location},
+			},
+			LastSeen: time,
+		})
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("iterating through locations: %w", err)
+	}
+	return candidates, nil
+}
+
+// CandidateLocations2 returns a prioritized, limited, number of blobs and their locations
+// that could possibly be reused within the specified (transport scope) (if they still
+// exist, which is not guaranteed).
+//
+// If !canSubstitute, the returned cadidates will match the submitted digest exactly; if
+// canSubstitute, data from previous RecordDigestUncompressedPair calls is used to also look
+// up variants of the blob which have the same uncompressed digest.
+//
+// The CompressorName fields in returned data must never be UnknownCompression.
+func (sqc *cache) CandidateLocations2(transport types.ImageTransport, scope types.BICTransportScope, digest digest.Digest, canSubstitute bool) []blobinfocache.BICReplacementCandidate2 {
+	return sqc.candidateLocations(transport, scope, digest, canSubstitute, true)
+}
+
+func (sqc *cache) candidateLocations(transport types.ImageTransport, scope types.BICTransportScope, primaryDigest digest.Digest, canSubstitute, requireCompressionInfo bool) []blobinfocache.BICReplacementCandidate2 {
+	var uncompressedDigest digest.Digest // = ""
+	res, err := transaction(sqc, func(tx *sql.Tx) ([]prioritize.CandidateWithTime, error) {
+		res := []prioritize.CandidateWithTime{}
+		res, err := sqc.appendReplacementCandidates(res, tx, transport, scope, primaryDigest, requireCompressionInfo)
+		if err != nil {
+			return nil, err
+		}
+		if canSubstitute {
+			uncompressedDigest, err = sqc.uncompressedDigest(tx, primaryDigest)
+			if err != nil {
+				return nil, err
+			}
+
+			// FIXME? We could integrate this with appendReplacementCandidates into a single join instead of N+1 queries.
+			// (In the extreme, we could turn _everything_ this function does into a single query.
+			// And going even further, even DestructivelyPrioritizeReplacementCandidates could be turned into SQL.)
+			// For now, we prioritize simplicity, and sharing both code and implementation structure with the other cache implementations.
+			rows, err := tx.Query("SELECT anyDigest FROM DigestUncompressedPairs WHERE uncompressedDigest = ?", uncompressedDigest.String())
+			if err != nil {
+				return nil, fmt.Errorf("querying for other digests: %w", err)
+			}
+			defer rows.Close()
+			for rows.Next() {
+				var otherDigestString string
+				if err := rows.Scan(&otherDigestString); err != nil {
+					return nil, fmt.Errorf("scanning other digest: %w", err)
+				}
+				otherDigest, err := digest.Parse(otherDigestString)
+				if err != nil {
+					return nil, err
+				}
+				if otherDigest != primaryDigest && otherDigest != uncompressedDigest {
+					res, err = sqc.appendReplacementCandidates(res, tx, transport, scope, otherDigest, requireCompressionInfo)
+					if err != nil {
+						return nil, err
+					}
+				}
+			}
+			if err := rows.Err(); err != nil {
+				return nil, fmt.Errorf("iterating through other digests: %w", err)
+			}
+
+			if uncompressedDigest != primaryDigest {
+				res, err = sqc.appendReplacementCandidates(res, tx, transport, scope, uncompressedDigest, requireCompressionInfo)
+				if err != nil {
+					return nil, err
+				}
+			}
+		}
+		return res, nil
+	})
+	if err != nil {
+		return []blobinfocache.BICReplacementCandidate2{} // FIXME? Log err (but throttle the log volume on repeated accesses)?
+	}
+	return prioritize.DestructivelyPrioritizeReplacementCandidates(res, primaryDigest, uncompressedDigest)
+
+}
+
+// CandidateLocations returns a prioritized, limited, number of blobs and their locations that could possibly be reused
+// within the specified (transport scope) (if they still exist, which is not guaranteed).
+//
+// If !canSubstitute, the returned candidates will match the submitted digest exactly; if canSubstitute,
+// data from previous RecordDigestUncompressedPair calls is used to also look up variants of the blob which have the same
+// uncompressed digest.
+func (sqc *cache) CandidateLocations(transport types.ImageTransport, scope types.BICTransportScope, digest digest.Digest, canSubstitute bool) []types.BICReplacementCandidate {
+	return blobinfocache.CandidateLocationsFromV2(sqc.candidateLocations(transport, scope, digest, canSubstitute, false))
+}

vendor/github.com/containers/image/v5/storage/storage_src.go

@@ -23,6 +23,7 @@ import (
 	"github.com/containers/image/v5/types"
 	"github.com/containers/storage"
 	"github.com/containers/storage/pkg/archive"
+	"github.com/containers/storage/pkg/ioutils"
 	digest "github.com/opencontainers/go-digest"
 	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/sirupsen/logrus"
@@ -129,15 +130,20 @@ func (s *storageImageSource) GetBlob(ctx context.Context, info types.BlobInfo, c
 		return nil, 0, err
 	}
 	success := false
+	tmpFileRemovePending := true
 	defer func() {
 		if !success {
 			tmpFile.Close()
+			if tmpFileRemovePending {
+				os.Remove(tmpFile.Name())
+			}
 		}
 	}()
 	// On Unix and modern Windows (2022 at least) we can eagerly unlink the file to ensure it's automatically
 	// cleaned up on process termination (or if the caller forgets to invoke Close())
+	// On older versions of Windows we will have to fallback to relying on the caller to invoke Close()
 	if err := os.Remove(tmpFile.Name()); err != nil {
-		return nil, 0, err
+		tmpFileRemovePending = false
 	}
 
 	if _, err := io.Copy(tmpFile, rc); err != nil {
@@ -148,6 +154,14 @@ func (s *storageImageSource) GetBlob(ctx context.Context, info types.BlobInfo, c
 	}
 
 	success = true
+
+	if tmpFileRemovePending {
+		return ioutils.NewReadCloserWrapper(tmpFile, func() error {
+			tmpFile.Close()
+			return os.Remove(tmpFile.Name())
+		}), n, nil
+	}
+
 	return tmpFile, n, nil
 }
 

vendor/github.com/containers/image/v5/version/version.go

@@ -6,12 +6,12 @@ const (
 	// VersionMajor is for an API incompatible changes
 	VersionMajor = 5
 	// VersionMinor is for functionality in a backwards-compatible manner
-	VersionMinor = 27
+	VersionMinor = 28
 	// VersionPatch is for backwards-compatible bug fixes
 	VersionPatch = 0
 
 	// VersionDev indicates development branch. Releases will be empty string.
-	VersionDev = "-dev"
+	VersionDev = ""
 )
 
 // Version is the specification version that the package types support.