1 files changed, 118 insertions, 0 deletions
diff --git a/object/store/loose/read_reader.go b/object/store/loose/read_reader.go
new file mode 100644
index 00000000..29b71627
--- /dev/null
+++ b/object/store/loose/read_reader.go
@@ -0,0 +1,118 @@
+package loose
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"os"
+
+	"codeberg.org/lindenii/furgit/internal/compress/zlib"
+	"codeberg.org/lindenii/furgit/internal/iolimit"
+	objectid "codeberg.org/lindenii/furgit/object/id"
+	objecttype "codeberg.org/lindenii/furgit/object/type"
+)
+
+type objectReader struct {
+	// reader is the stream exposed by Read.
+	reader io.Reader
+	// file is the underlying loose object file and is closed by Close.
+	file *os.File
+	// zr is the zlib decoder and is closed by Close.
+	zr io.ReadCloser
+}
+
+func (reader *objectReader) Read(dst []byte) (int, error) {
+	return reader.reader.Read(dst)
+}
+
+func (reader *objectReader) Close() error {
+	errZlib := reader.zr.Close()
+	errFile := reader.file.Close()
+
+	return errors.Join(errZlib, errFile)
+}
+
+// openInflated opens and zlib-decodes a loose object file.
+// The caller owns both returned closers and must close them.
+func (store *Store) openInflated(id objectid.ObjectID) (*os.File, io.ReadCloser, error) {
+	file, err := store.openObject(id)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	zr, err := zlib.NewReader(file)
+	if err != nil {
+		_ = file.Close()
+
+		return nil, nil, err
+	}
+
+	return file, zr, nil
+}
+
+// ReadReaderFull reads a full serialized object stream as "type size\0content".
+//
+// The caller must close the returned reader.
+//
+// Close releases 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) {
+	file, zr, err := store.openInflated(id)
+	if err != nil {
+		return nil, err
+	}
+
+	br := bufio.NewReader(zr)
+
+	header, _, size, err := readHeader(br)
+	if err != nil {
+		_ = zr.Close()
+		_ = file.Close()
+
+		return nil, err
+	}
+
+	return &objectReader{
+		reader: io.MultiReader(
+			bytes.NewReader(header),
+			iolimit.ExpectLengthReader(br, size),
+		),
+		file: file,
+		zr:   zr,
+	}, nil
+}
+
+// ReadReaderContent reads an object's type, declared content length, and
+// content stream.
+//
+// The caller must close the returned reader.
+//
+// Close releases 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) {
+	file, zr, err := store.openInflated(id)
+	if err != nil {
+		return objecttype.TypeInvalid, 0, nil, err
+	}
+
+	br := bufio.NewReader(zr)
+
+	_, ty, size, err := readHeader(br)
+	if err != nil {
+		_ = zr.Close()
+		_ = file.Close()
+
+		return objecttype.TypeInvalid, 0, nil, err
+	}
+
+	return ty, size, &objectReader{
+		reader: iolimit.ExpectLengthReader(br, size),
+		file:   file,
+		zr:     zr,
+	}, nil
+}