add git.iim.gay/grufwub/go-store for storage backend, replacing blob.Storage

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

vendor/git.iim.gay/grufwub/go-store/util/io.go

@@ -0,0 +1,42 @@
+package util
+
+import "io"
+
+// NopReadCloser turns a supplied io.Reader into io.ReadCloser with a nop Close() implementation
+func NopReadCloser(r io.Reader) io.ReadCloser {
+	return &nopReadCloser{r}
+}
+
+// NopWriteCloser turns a supplied io.Writer into io.WriteCloser with a nop Close() implementation
+func NopWriteCloser(w io.Writer) io.WriteCloser {
+	return &nopWriteCloser{w}
+}
+
+// ReadCloserWithCallback adds a customizable callback to be called upon Close() of a supplied io.ReadCloser
+func ReadCloserWithCallback(rc io.ReadCloser, cb func()) io.ReadCloser {
+	return &callbackReadCloser{
+		ReadCloser: rc,
+		callback:   cb,
+	}
+}
+
+// nopReadCloser turns an io.Reader -> io.ReadCloser with a nop Close()
+type nopReadCloser struct{ io.Reader }
+
+func (r *nopReadCloser) Close() error { return nil }
+
+// nopWriteCloser turns an io.Writer -> io.WriteCloser with a nop Close()
+type nopWriteCloser struct{ io.Writer }
+
+func (w nopWriteCloser) Close() error { return nil }
+
+// callbackReadCloser allows adding our own custom callback to an io.ReadCloser
+type callbackReadCloser struct {
+	io.ReadCloser
+	callback func()
+}
+
+func (c *callbackReadCloser) Close() error {
+	defer c.callback()
+	return c.ReadCloser.Close()
+}