fix possible hang

Author: nia-e

src/shims/trace/child.rs

@@ -211,6 +211,10 @@ pub unsafe fn init_sv() -> Result<(), SvInitError> {
                 }
             }
             unistd::ForkResult::Child => {
+                // Make sure we never get orphaned and stuck in SIGSTOP or similar
+                // SAFETY: prctl PR_SET_PDEATHSIG is always safe to call
+                let ret = libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGTERM);
+                assert_eq!(ret, 0);
                 // First make sure the parent succeeded with ptracing us!
                 signal::raise(signal::SIGSTOP).unwrap();
                 // If we're the child process, save the supervisor info