objectstore/loose: Add loose backend

1 files changed, 84 insertions, 0 deletions

diff --git a/objectstore/loose/read_reader.go b/objectstore/loose/read_reader.go
new file mode 100644
index 00000000..dde0de07
--- /dev/null
+++ b/objectstore/loose/read_reader.go
@@ -0,0 +1,84 @@
+package loose
+
+import (
+	"bufio"
+	"compress/zlib"
+	"errors"
+	"io"
+	"os"
+
+	"codeberg.org/lindenii/furgit/objectid"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+type objectReader struct {
+	// reader is the stream exposed by Read. It may be the raw zlib reader
+	// (full object) or a buffered reader positioned at content bytes only.
+	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\\x00content".
+// The caller must close the returned reader.
+func (store *Store) ReadReaderFull(id objectid.ObjectID) (io.ReadCloser, error) {
+	file, zr, err := store.openInflated(id)
+	if err != nil {
+		return nil, err
+	}
+	return &objectReader{
+		reader: zr,
+		file:   file,
+		zr:     zr,
+	}, nil
+}
+
+// ReadReaderContent reads an object's type, declared content length, and content stream.
+// The caller must close the returned reader.
+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: br,
+		file:   file,
+		zr:     zr,
+	}, nil
+}