Stub the custom "job" controller required by some workloads.

PiperOrigin-RevId: 369724358

1 files changed, 64 insertions, 0 deletions

diff --git a/pkg/sentry/fsimpl/cgroupfs/job.go b/pkg/sentry/fsimpl/cgroupfs/job.go
new file mode 100644
index 000000000..48919c338
--- /dev/null
+++ b/pkg/sentry/fsimpl/cgroupfs/job.go
@@ -0,0 +1,64 @@
+// Copyright 2021 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 cgroupfs
+
+import (
+	"bytes"
+	"fmt"
+
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/usermem"
+)
+
+// +stateify savable
+type jobController struct {
+	controllerCommon
+	id int64
+}
+
+var _ controller = (*jobController)(nil)
+
+func newJobController(fs *filesystem) *jobController {
+	c := &jobController{}
+	c.controllerCommon.init(controllerJob, fs)
+	return c
+}
+
+func (c *jobController) AddControlFiles(ctx context.Context, creds *auth.Credentials, _ *cgroupInode, contents map[string]kernfs.Inode) {
+	contents["job.id"] = c.fs.newControllerWritableFile(ctx, creds, &jobIDData{c: c})
+}
+
+// +stateify savable
+type jobIDData struct {
+	c *jobController
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *jobIDData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	fmt.Fprintf(buf, "%d\n", d.c.id)
+	return nil
+}
+
+// Write implements vfs.WritableDynamicBytesSource.Write.
+func (d *jobIDData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
+	val, n, err := parseInt64FromString(ctx, src, offset)
+	if err != nil {
+		return n, err
+	}
+	d.c.id = val
+	return n, nil
+}