1 files changed, 41 insertions, 0 deletions
diff --git a/pkg/sentry/fs/proc/cgroup.go b/pkg/sentry/fs/proc/cgroup.go
new file mode 100644
index 000000000..1019f862a
--- /dev/null
+++ b/pkg/sentry/fs/proc/cgroup.go
@@ -0,0 +1,41 @@
+// Copyright 2018 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 proc
+
+import (
+	"fmt"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+)
+
+func newCGroupInode(ctx context.Context, msrc *fs.MountSource, cgroupControllers map[string]string) *fs.Inode {
+	// From man 7 cgroups: "For each cgroup hierarchy of which the process
+	// is a member, there is one entry containing three colon-separated
+	// fields: hierarchy-ID:controller-list:cgroup-path"
+
+	// The hierarchy ids must be positive integers (for cgroup v1), but the
+	// exact number does not matter, so long as they are unique. We can
+	// just use a counter, but since linux sorts this file in descending
+	// order, we must count down to perserve this behavior.
+	i := len(cgroupControllers)
+	var data string
+	for name, dir := range cgroupControllers {
+		data += fmt.Sprintf("%d:%s:%s\n", i, name, dir)
+		i--
+	}
+
+	return newStaticProcInode(ctx, msrc, []byte(data))
+}