helper/stub: write ready byte late

Hopefully eliminates spurious failures.

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

helper/stub.go

@@ -68,39 +68,35 @@ func genericStub(argsFile, statFile *os.File) {
 		}
 	}
 
-	// simulate status pipe behaviour
 	if statFile != nil {
+		// simulate status pipe behaviour
+		var epoll int
+		if fd, err := syscall.EpollCreate1(0); err != nil {
+			panic("cannot open epoll fd: " + err.Error())
+		} else {
+			defer func() {
+				if err = syscall.Close(fd); err != nil {
+					panic("cannot close epoll fd: " + err.Error())
+				}
+			}()
+			epoll = fd
+		}
+		if err := syscall.EpollCtl(epoll, syscall.EPOLL_CTL_ADD, int(statFile.Fd()), &syscall.EpollEvent{}); err != nil {
+			panic("cannot add status pipe to epoll: " + err.Error())
+		}
+
 		if _, err := statFile.Write([]byte{'x'}); err != nil {
 			panic("cannot write to status pipe: " + err.Error())
 		}
 
-		done := make(chan struct{})
-		go func() {
-			// wait for status pipe close
-			var epoll int
-			if fd, err := syscall.EpollCreate1(0); err != nil {
-				panic("cannot open epoll fd: " + err.Error())
-			} else {
-				defer func() {
-					if err = syscall.Close(fd); err != nil {
-						panic("cannot close epoll fd: " + err.Error())
-					}
-				}()
-				epoll = fd
-			}
-			if err := syscall.EpollCtl(epoll, syscall.EPOLL_CTL_ADD, int(statFile.Fd()), &syscall.EpollEvent{}); err != nil {
-				panic("cannot add status pipe to epoll: " + err.Error())
-			}
-			events := make([]syscall.EpollEvent, 1)
-			if _, err := syscall.EpollWait(epoll, events, -1); err != nil {
-				panic("cannot poll status pipe: " + err.Error())
-			}
-			if events[0].Events != syscall.EPOLLERR {
-				panic(strconv.Itoa(int(events[0].Events)))
+		// wait for status pipe close
+		events := make([]syscall.EpollEvent, 1)
+		if _, err := syscall.EpollWait(epoll, events, -1); err != nil {
+			panic("cannot poll status pipe: " + err.Error())
+		}
+		if events[0].Events != syscall.EPOLLERR {
+			panic(strconv.Itoa(int(events[0].Events)))
 
-			}
-			close(done)
-		}()
-		<-done
+		}
 	}
 }