container/initdaemon: copy wstatus from wait4 loop

Due to the special nature of the init process, direct use of wait outside the wait4 loop is racy. This change copies the wstatus from wait4 loop state instead.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/dispatcher.go

@@ -68,8 +68,6 @@ type syscallDispatcher interface {
 	notify(c chan<- os.Signal, sig ...os.Signal)
 	// start starts [os/exec.Cmd].
 	start(c *exec.Cmd) error
-	// wait waits on [os/exec.Cmd].
-	wait(c *exec.Cmd) error
 	// signal signals the underlying process of [os/exec.Cmd].
 	signal(c *exec.Cmd, sig os.Signal) error
 	// evalSymlinks provides [filepath.EvalSymlinks].
@@ -172,7 +170,6 @@ func (direct) seccompLoad(rules []std.NativeRule, flags seccomp.ExportFlag) erro
 }
 func (direct) notify(c chan<- os.Signal, sig ...os.Signal) { signal.Notify(c, sig...) }
 func (direct) start(c *exec.Cmd) error                     { return c.Start() }
-func (direct) wait(c *exec.Cmd) error                      { return c.Wait() }
 func (direct) signal(c *exec.Cmd, sig os.Signal) error     { return c.Process.Signal(sig) }
 func (direct) evalSymlinks(path string) (string, error)    { return filepath.EvalSymlinks(path) }