1 files changed, 37 insertions, 0 deletions
diff --git a/pkg/sentry/vfs/context.go b/pkg/sentry/vfs/context.go
new file mode 100644
index 000000000..32cf9151b
--- /dev/null
+++ b/pkg/sentry/vfs/context.go
@@ -0,0 +1,37 @@
+// Copyright 2019 The gVisor 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 vfs
+
+import (
+	"gvisor.dev/gvisor/pkg/sentry/context"
+)
+
+// contextID is this package's type for context.Context.Value keys.
+type contextID int
+
+const (
+	// CtxMountNamespace is a Context.Value key for a MountNamespace.
+	CtxMountNamespace contextID = iota
+)
+
+// MountNamespaceFromContext returns the MountNamespace used by ctx. It does
+// not take a reference on the returned MountNamespace. If ctx is not
+// associated with a MountNamespace, MountNamespaceFromContext returns nil.
+func MountNamespaceFromContext(ctx context.Context) *MountNamespace {
+	if v := ctx.Value(CtxMountNamespace); v != nil {
+		return v.(*MountNamespace)
+	}
+	return nil
+}