Added a resume command to unpause a paused container.

Resume checks the status of the container and unpauses the kernel
if its status is paused. Otherwise nothing happens.
Tests were added to ensure that the process is in the correct state
after various commands.

PiperOrigin-RevId: 201251234
Change-Id: Ifd11b336c33b654fea6238738f864fcf2bf81e19

2 files changed, 69 insertions, 0 deletions

diff --git a/runsc/cmd/BUILD b/runsc/cmd/BUILD
index 8fbce294f..fffb6f359 100644
--- a/runsc/cmd/BUILD
+++ b/runsc/cmd/BUILD
@@ -20,6 +20,7 @@ go_library(
         "pause.go",
         "ps.go",
         "restore.go",
+        "resume.go",
         "run.go",
         "start.go",
         "state.go",
diff --git a/runsc/cmd/resume.go b/runsc/cmd/resume.go
new file mode 100644
index 000000000..a12adf1a3
--- /dev/null
+++ b/runsc/cmd/resume.go
@@ -0,0 +1,68 @@
+// Copyright 2018 Google Inc.
+//
+// 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 cmd
+
+import (
+	"context"
+	"flag"
+	"github.com/google/subcommands"
+	"gvisor.googlesource.com/gvisor/runsc/boot"
+	"gvisor.googlesource.com/gvisor/runsc/container"
+)
+
+// Resume implements subcommands.Command for the "resume" command.
+type Resume struct{}
+
+// Name implements subcommands.Command.Name.
+func (*Resume) Name() string {
+	return "resume"
+}
+
+// Synopsis implements subcommands.Command.Synopsis.
+func (*Resume) Synopsis() string {
+	return "Resume unpauses a paused container"
+}
+
+// Usage implements subcommands.Command.Usage.
+func (*Resume) Usage() string {
+	return `resume <container id> - resume a paused container.
+`
+}
+
+// SetFlags implements subcommands.Command.SetFlags.
+func (r *Resume) SetFlags(f *flag.FlagSet) {
+}
+
+// Execute implements subcommands.Command.Execute.
+func (r *Resume) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
+	if f.NArg() != 1 {
+		f.Usage()
+		return subcommands.ExitUsageError
+	}
+
+	id := f.Arg(0)
+	conf := args[0].(*boot.Config)
+
+	cont, err := container.Load(conf.RootDir, id)
+	if err != nil {
+		Fatalf("error loading container: %v", err)
+	}
+
+	if err := cont.Resume(); err != nil {
+		Fatalf("resume failed: %v", err)
+	}
+
+	return subcommands.ExitSuccess
+}