Make cwd required

Signed-off-by: Mrunal Patel <[email protected]>

Author: mrunalp

libcontainer/init_linux.go

@@ -134,10 +134,8 @@ func finalizeNamespace(config *initConfig) error {
 	if err := w.drop(); err != nil {
 		return err
 	}
-	if config.Cwd != "" {
-		if err := syscall.Chdir(config.Cwd); err != nil {
-			return err
-		}
+	if err := syscall.Chdir(config.Cwd); err != nil {
+		return err
 	}
 	return nil
 }

spec.go

@@ -53,6 +53,7 @@ var specCommand = cli.Command{
 						"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 						"TERM=xterm",
 					},
+					Cwd: "/",
 				},
 				Hostname: "shell",
 				Mounts: []specs.MountPoint{
@@ -290,6 +291,15 @@ var mountPropagationMapping = map[string]int{
 	"":         syscall.MS_PRIVATE | syscall.MS_REC,
 }
 
+// validateSpec validates the fields in the spec
+// TODO: Add validation for other fields where applicable
+func validateSpec(spec *specs.LinuxSpec, rspec *specs.LinuxRuntimeSpec) error {
+	if spec.Process.Cwd == "" {
+		return fmt.Errorf("Cwd property must not be empty")
+	}
+	return nil
+}
+
 // loadSpec loads the specification from the provided path.
 // If the path is empty then the default path will be "config.json"
 func loadSpec(cPath, rPath string) (spec *specs.LinuxSpec, rspec *specs.LinuxRuntimeSpec, err error) {
@@ -317,7 +327,10 @@ func loadSpec(cPath, rPath string) (spec *specs.LinuxSpec, rspec *specs.LinuxRun
 	if err = json.NewDecoder(rf).Decode(&rspec); err != nil {
 		return spec, rspec, err
 	}
-	return spec, rspec, checkSpecVersion(spec)
+	if err := checkSpecVersion(spec); err != nil {
+		return spec, rspec, err
+	}
+	return spec, rspec, validateSpec(spec, rspec)
 }
 
 // checkSpecVersion makes sure that the spec version matches runc's while we are in the initial

start.go

@@ -108,6 +108,7 @@ func startContainer(context *cli.Context, spec *specs.LinuxSpec, rspec *specs.Li
 	// ensure that the container is always removed if we were the process
 	// that created it.
 	defer destroy(container)
+
 	process := newProcess(spec.Process)
 
 	// Support on-demand socket activation by passing file descriptors into the container init process.