runsc: Support multi-container exec.

We must use a context.Context with a Root Dirent that corresponds to the
container's chroot. Previously we were using the root context, which does not
have a chroot.

Getting the correct context required refactoring some of the path-lookup code.
We can't lookup the path without a context.Context, which requires
kernel.CreateProcArgs, which we only get inside control.Execute.  So we have to
do the path lookup much later than we previously were.

PiperOrigin-RevId: 212064734
Change-Id: I84a5cfadacb21fd9c3ab9c393f7e308a40b9b537

1 files changed, 6 insertions, 1 deletions

diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go
index 697210669..f272496a1 100644
--- a/runsc/sandbox/sandbox.go
+++ b/runsc/sandbox/sandbox.go
@@ -187,11 +187,16 @@ func (s *Sandbox) Execute(cid string, e *control.ExecArgs) (syscall.WaitStatus,
 	}
 	defer conn.Close()
 
+	ea := &boot.ExecArgs{
+		ExecArgs: *e,
+		CID:      cid,
+	}
+
 	// Send a message to the sandbox control server to start the container.
 	var waitStatus uint32
 	// TODO: Pass in the container id (cid) here. The sandbox
 	// should execute in the context of that container.
-	if err := conn.Call(boot.ContainerExecute, e, &waitStatus); err != nil {
+	if err := conn.Call(boot.ContainerExecute, ea, &waitStatus); err != nil {
 		return 0, fmt.Errorf("error executing in sandbox: %v", err)
 	}