move implementation to internal/ directory (#828)

internal/util/limitio/limitio.go

@@ -0,0 +1,36 @@
+package limitio
+
+import "io"
+
+type readCloser struct {
+	read  int64
+	limit int64
+	r     io.ReadCloser
+}
+
+func ReadCloser(rc io.ReadCloser, limit int64) io.ReadCloser {
+	return &readCloser{0, limit, rc}
+}
+
+var _ io.ReadCloser = (*readCloser)(nil)
+
+func (r *readCloser) Read(b []byte) (int, error) {
+
+	if len(b) == 0 {
+		return 0, nil
+	}
+
+	if r.read == r.limit {
+		return 0, io.EOF
+	}
+
+	if r.read+int64(len(b)) >= r.limit {
+		b = b[:int(r.limit-r.read)]
+	}
+
+	readN, err := r.r.Read(b)
+	r.read += int64(readN)
+	return readN, err
+}
+
+func (r *readCloser) Close() error { return r.r.Close() }