objectstore/loose: Add loose backend

1 files changed, 45 insertions, 0 deletions

diff --git a/objectstore/loose/parse.go b/objectstore/loose/parse.go
new file mode 100644
index 00000000..30c7e251
--- /dev/null
+++ b/objectstore/loose/parse.go
@@ -0,0 +1,45 @@
+package loose
+
+import (
+	"bufio"
+	"compress/zlib"
+	"errors"
+	"io"
+	"os"
+
+	"codeberg.org/lindenii/furgit/objectheader"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+// decodeAll inflates the full loose object payload from file.
+func decodeAll(file *os.File) ([]byte, error) {
+	zr, err := zlib.NewReader(file)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = zr.Close() }()
+	return io.ReadAll(zr)
+}
+
+// parseRaw parses a loose object payload in "type size\0content" format.
+func parseRaw(raw []byte) (objecttype.Type, []byte, error) {
+	ty, _, headerLen, ok := objectheader.Parse(raw)
+	if !ok {
+		return objecttype.TypeInvalid, nil, errors.New("objectstore/loose: malformed object header")
+	}
+	return ty, raw[headerLen:], nil
+}
+
+// readHeader reads and parses a loose object header from br.
+// br must be positioned at the start of decoded loose object bytes.
+func readHeader(br *bufio.Reader) (objecttype.Type, int64, error) {
+	header, err := br.ReadSlice(0)
+	if err != nil {
+		return objecttype.TypeInvalid, 0, err
+	}
+	ty, size, _, ok := objectheader.Parse(header)
+	if !ok {
+		return objecttype.TypeInvalid, 0, errors.New("objectstore/loose: malformed object header")
+	}
+	return ty, size, nil
+}