1 files changed, 77 insertions, 0 deletions
diff --git a/format/pack/ingest/finalize.go b/format/pack/ingest/finalize.go
new file mode 100644
index 00000000..06b30102
--- /dev/null
+++ b/format/pack/ingest/finalize.go
@@ -0,0 +1,77 @@
+package ingest
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"strings"
+)
+
+// finalizeArtifacts links temporary files to final names and returns Result.
+func finalizeArtifacts(state *ingestState) (Result, error) {
+	base := "pack-" + state.packHash.String()
+	packFinal := base + ".pack"
+	idxFinal := base + ".idx"
+	revFinal := ""
+	if state.writeRev {
+		revFinal = base + ".rev"
+	}
+
+	if err := linkTempToFinal(state, state.packTmpName, packFinal); err != nil {
+		return Result{}, err
+	}
+	if err := linkTempToFinal(state, state.idxTmpName, idxFinal); err != nil {
+		return Result{}, err
+	}
+	if state.writeRev {
+		if err := linkTempToFinal(state, state.revTmpName, revFinal); err != nil {
+			return Result{}, err
+		}
+	}
+
+	return Result{
+		PackName:    packFinal,
+		IdxName:     idxFinal,
+		RevName:     revFinal,
+		PackHash:    state.packHash,
+		ObjectCount: uint32(len(state.records)),
+		ThinFixed:   state.thinFixed,
+	}, nil
+}
+
+// rollbackTemporaryArtifacts removes temporary files after failure.
+func rollbackTemporaryArtifacts(state *ingestState) {
+	if state.packTmpName != "" {
+		_ = state.destination.Remove(state.packTmpName)
+	}
+	if state.idxTmpName != "" {
+		_ = state.destination.Remove(state.idxTmpName)
+	}
+	if state.revTmpName != "" {
+		_ = state.destination.Remove(state.revTmpName)
+	}
+}
+
+// linkTempToFinal hard-links tmp to final, tolerating existing final paths.
+func linkTempToFinal(state *ingestState, tmp, final string) error {
+	if tmp == "" || final == "" {
+		return fmt.Errorf("format/pack/ingest: invalid finalize names tmp=%q final=%q", tmp, final)
+	}
+	if strings.Contains(final, "/") {
+		return fmt.Errorf("format/pack/ingest: final name must be leaf: %q", final)
+	}
+
+	err := state.destination.Link(tmp, final)
+	if err == nil {
+		_ = state.destination.Remove(tmp)
+
+		return nil
+	}
+	if errors.Is(err, fs.ErrExist) {
+		_ = state.destination.Remove(tmp)
+
+		return nil
+	}
+
+	return err
+}