objectheader: Add loose-object header parsing and emitting code

1 files changed, 27 insertions, 0 deletions

diff --git a/internal/objectheader/append.go b/internal/objectheader/append.go
new file mode 100644
index 00000000..3965dc21
--- /dev/null
+++ b/internal/objectheader/append.go
@@ -0,0 +1,27 @@
+package objectheader
+
+import (
+	"strconv"
+
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+// Append appends a canonical loose-object header ("type size\\x00") to dst.
+func Append(dst []byte, ty objecttype.Type, size int64) ([]byte, bool) {
+	if size < 0 {
+		return nil, false
+	}
+	tyName, ok := objecttype.Name(ty)
+	if !ok {
+		return nil, false
+	}
+
+	sizeStr := strconv.FormatInt(size, 10)
+	out := make([]byte, 0, len(dst)+len(tyName)+len(sizeStr)+2)
+	out = append(out, dst...)
+	out = append(out, tyName...)
+	out = append(out, ' ')
+	out = append(out, sizeStr...)
+	out = append(out, 0)
+	return out, true
+}