Complete artifact binary transfer streaming

platform/service/artifact_body_store.go

@@ -1,6 +1,7 @@
 package service
 
 import (
+	"bytes"
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
@@ -24,6 +25,7 @@ type ArtifactBodyStore interface {
 	PutPayload(string, []byte) error
 	GetPayload(string) ([]byte, error)
 	ReadPayloadRange(string, int64, int) ([]byte, error)
+	OpenPayloadRange(string, int64, int64) (io.ReadCloser, error)
 	CommitTransferPayload(domain.ArtifactTransferSession) error
 }
 
@@ -89,6 +91,17 @@ func (store *MemoryArtifactBodyStore) ReadPayloadRange(artifactID string, offset
 	return domain.CopyBytes(payload[int(offset) : int(offset)+length]), nil
 }
 
+func (store *MemoryArtifactBodyStore) OpenPayloadRange(artifactID string, offset int64, length int64) (io.ReadCloser, error) {
+	if length < 0 || length > int64(int(^uint(0)>>1)) {
+		return nil, fmt.Errorf("artifact range is invalid")
+	}
+	payload, err := store.ReadPayloadRange(artifactID, offset, int(length))
+	if err != nil {
+		return nil, err
+	}
+	return io.NopCloser(bytes.NewReader(payload)), nil
+}
+
 func (store *MemoryArtifactBodyStore) CommitTransferPayload(session domain.ArtifactTransferSession) error {
 	store.mu.Lock()
 	defer store.mu.Unlock()
@@ -243,6 +256,40 @@ func (store *FileArtifactBodyStore) ReadPayloadRange(artifactID string, offset i
 	return payload, nil
 }
 
+func (store *FileArtifactBodyStore) OpenPayloadRange(artifactID string, offset int64, length int64) (io.ReadCloser, error) {
+	if offset < 0 || length < 0 {
+		return nil, fmt.Errorf("artifact range is invalid")
+	}
+	store.mu.Lock()
+	defer store.mu.Unlock()
+	file, err := os.Open(store.payloadPath(artifactID))
+	if errors.Is(err, os.ErrNotExist) {
+		return nil, repo.ErrNotFound
+	}
+	if err != nil {
+		return nil, fmt.Errorf("open artifact payload: %w", err)
+	}
+	info, err := file.Stat()
+	if err != nil {
+		_ = file.Close()
+		return nil, fmt.Errorf("stat artifact payload: %w", err)
+	}
+	if offset > info.Size() || length > info.Size()-offset {
+		_ = file.Close()
+		return nil, fmt.Errorf("artifact range is invalid")
+	}
+	return sectionReadCloser{SectionReader: io.NewSectionReader(file, offset, length), file: file}, nil
+}
+
+type sectionReadCloser struct {
+	*io.SectionReader
+	file *os.File
+}
+
+func (reader sectionReadCloser) Close() error {
+	return reader.file.Close()
+}
+
 func (store *FileArtifactBodyStore) CommitTransferPayload(session domain.ArtifactTransferSession) error {
 	store.mu.Lock()
 	defer store.mu.Unlock()