vendor: add buildkit

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/containerd/containerd/labels/validate.go

@@ -0,0 +1,37 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package labels
+
+import (
+	"github.com/containerd/containerd/errdefs"
+	"github.com/pkg/errors"
+)
+
+const (
+	maxSize = 4096
+)
+
+// Validate a label's key and value are under 4096 bytes
+func Validate(k, v string) error {
+	if (len(k) + len(v)) > maxSize {
+		if len(k) > 10 {
+			k = k[:10]
+		}
+		return errors.Wrapf(errdefs.ErrInvalidArgument, "label key and value greater than maximum size (%d bytes), key: %s", maxSize, k)
+	}
+	return nil
+}