Update gomod and vendor

vendor/github.com/containerd/go-runc/monitor.go

@@ -0,0 +1,76 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package runc
+
+import (
+	"os/exec"
+	"syscall"
+	"time"
+)
+
+var Monitor ProcessMonitor = &defaultMonitor{}
+
+type Exit struct {
+	Timestamp time.Time
+	Pid       int
+	Status    int
+}
+
+// ProcessMonitor is an interface for process monitoring
+//
+// It allows daemons using go-runc to have a SIGCHLD handler
+// to handle exits without introducing races between the handler
+// and go's exec.Cmd
+// These methods should match the methods exposed by exec.Cmd to provide
+// a consistent experience for the caller
+type ProcessMonitor interface {
+	Start(*exec.Cmd) (chan Exit, error)
+	Wait(*exec.Cmd, chan Exit) (int, error)
+}
+
+type defaultMonitor struct {
+}
+
+func (m *defaultMonitor) Start(c *exec.Cmd) (chan Exit, error) {
+	if err := c.Start(); err != nil {
+		return nil, err
+	}
+	ec := make(chan Exit, 1)
+	go func() {
+		var status int
+		if err := c.Wait(); err != nil {
+			status = 255
+			if exitErr, ok := err.(*exec.ExitError); ok {
+				if ws, ok := exitErr.Sys().(syscall.WaitStatus); ok {
+					status = ws.ExitStatus()
+				}
+			}
+		}
+		ec <- Exit{
+			Timestamp: time.Now(),
+			Pid:       c.Process.Pid,
+			Status:    status,
+		}
+		close(ec)
+	}()
+	return ec, nil
+}
+
+func (m *defaultMonitor) Wait(c *exec.Cmd, ec chan Exit) (int, error) {
+	e := <-ec
+	return e.Status, nil
+}