infrakit: Fix detection of running proceses

os.FindProcess() does not return an error when then process does not
exist. It even returns a dummy process object.

Use the go-ps package to find out if the hyperkit process is actually
running.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

tools/infrakit.hyperkit/vendor/github.com/mitchellh/go-ps/process_linux.go

@@ -0,0 +1,35 @@
+// +build linux
+
+package ps
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+)
+
+// Refresh reloads all the data associated with this process.
+func (p *UnixProcess) Refresh() error {
+	statPath := fmt.Sprintf("/proc/%d/stat", p.pid)
+	dataBytes, err := ioutil.ReadFile(statPath)
+	if err != nil {
+		return err
+	}
+
+	// First, parse out the image name
+	data := string(dataBytes)
+	binStart := strings.IndexRune(data, '(') + 1
+	binEnd := strings.IndexRune(data[binStart:], ')')
+	p.binary = data[binStart : binStart+binEnd]
+
+	// Move past the image name and start parsing the rest
+	data = data[binStart+binEnd+2:]
+	_, err = fmt.Sscanf(data,
+		"%c %d %d %d",
+		&p.state,
+		&p.ppid,
+		&p.pgrp,
+		&p.sid)
+
+	return err
+}