object/fetch: Port reader

1 files changed, 26 insertions, 0 deletions

diff --git a/object/fetch/reader.go b/object/fetch/reader.go
new file mode 100644
index 00000000..197efd84
--- /dev/null
+++ b/object/fetch/reader.go
@@ -0,0 +1,26 @@
+package fetch
+
+import (
+	"io"
+
+	"lindenii.org/go/furgit/errs"
+	oid "lindenii.org/go/furgit/object/id"
+	"lindenii.org/go/furgit/object/typ"
+)
+
+// exactReader reads one object's content stream
+// and verifies that its header type matches wantType.
+func (r *Fetcher) exactReader(id oid.ObjectID, wantType typ.Type) (io.ReadCloser, int64, error) {
+	gotType, size, rc, err := r.store.ReadReaderContent(id)
+	if err != nil {
+		return nil, 0, wrapObjectReadError(id, err)
+	}
+
+	if gotType != wantType {
+		_ = rc.Close()
+
+		return nil, 0, &errs.ObjectTypeError{OID: id, Got: gotType, Want: wantType}
+	}
+
+	return rc, size, nil
+}