1 files changed, 103 insertions, 0 deletions
diff --git a/object/store/packed/read_reader.go b/object/store/packed/read_reader.go
new file mode 100644
index 00000000..5f4fa604
--- /dev/null
+++ b/object/store/packed/read_reader.go
@@ -0,0 +1,103 @@
+package packed
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"codeberg.org/lindenii/furgit/internal/iolimit"
+	objectheader "codeberg.org/lindenii/furgit/object/header"
+	objectid "codeberg.org/lindenii/furgit/object/id"
+	objecttype "codeberg.org/lindenii/furgit/object/type"
+	packfmt "codeberg.org/lindenii/furgit/packfile"
+)
+
+// ReadReaderContent reads an object's type, declared content size, and content
+// stream.
+//
+// The caller must close the returned reader.
+//
+// For base pack entries, the returned reader borrows store-owned mapped pack
+// data and is only valid until the store is closed.
+//
+// Close releases reader-local resources only. It does not drain unread data for
+// additional validation. In particular, malformed trailing compressed data,
+// trailing bytes past the declared object size, and the zlib Adler-32 trailer
+// may go unverified unless the caller reads to io.EOF.
+func (store *Store) ReadReaderContent(id objectid.ObjectID) (objecttype.Type, int64, io.ReadCloser, error) {
+	loc, err := store.lookup(id)
+	if err != nil {
+		return objecttype.TypeInvalid, 0, nil, err
+	}
+
+	pack, meta, err := store.entryMetaAt(loc)
+	if err != nil {
+		return objecttype.TypeInvalid, 0, nil, err
+	}
+
+	if packfmt.IsBaseObjectType(meta.ty) {
+		zr, err := zlibReaderAt(pack, meta.dataOffset)
+		if err != nil {
+			return objecttype.TypeInvalid, 0, nil, err
+		}
+
+		return meta.ty, meta.size, &readCloser{
+			reader: iolimit.ExpectLengthReader(zr, meta.size),
+			closer: zr,
+		}, nil
+	}
+
+	ty, content, err := store.deltaResolveContent(loc)
+	if err != nil {
+		return objecttype.TypeInvalid, 0, nil, err
+	}
+
+	return ty, int64(len(content)), io.NopCloser(bytes.NewReader(content)), nil
+}
+
+// ReadReaderFull reads a full serialized object stream as "type size\0content".
+//
+// The caller must close the returned reader.
+//
+// For base pack entries, the returned reader borrows store-owned mapped pack
+// data and is only valid until the store is closed.
+//
+// Close releases reader-local resources only. It does not drain unread data for
+// additional validation. In particular, malformed trailing compressed data,
+// trailing bytes past the declared object size, and the zlib Adler-32 trailer
+// may go unverified unless the caller reads to io.EOF.
+func (store *Store) ReadReaderFull(id objectid.ObjectID) (io.ReadCloser, error) {
+	loc, err := store.lookup(id)
+	if err != nil {
+		return nil, err
+	}
+
+	pack, meta, err := store.entryMetaAt(loc)
+	if err != nil {
+		return nil, err
+	}
+
+	if packfmt.IsBaseObjectType(meta.ty) {
+		header, ok := objectheader.Encode(meta.ty, meta.size)
+		if !ok {
+			return nil, fmt.Errorf("objectstore/packed: failed to encode object header for type %d", meta.ty)
+		}
+
+		zr, err := zlibReaderAt(pack, meta.dataOffset)
+		if err != nil {
+			return nil, err
+		}
+
+		return &readCloser{
+			reader: io.MultiReader(bytes.NewReader(header), iolimit.ExpectLengthReader(zr, meta.size)),
+			closer: zr,
+		}, nil
+	}
+
+	raw, err := store.ReadBytesFull(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return io.NopCloser(bytes.NewReader(raw)), nil
+}