Refactor pmctl into new portmaster-start

cmds/portmaster-start/lock.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	processInfo "github.com/shirou/gopsutil/process"
+)
+
+func checkAndCreateInstanceLock(name string) (pid int32, err error) {
+	lockFilePath := filepath.Join(dataRoot.Path, fmt.Sprintf("%s-lock.pid", name))
+
+	// read current pid file
+	data, err := ioutil.ReadFile(lockFilePath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// create new lock
+			return 0, createInstanceLock(lockFilePath)
+		}
+		return 0, err
+	}
+
+	// file exists!
+	parsedPid, err := strconv.ParseInt(strings.TrimSpace(string(data)), 10, 64)
+	if err != nil {
+		log.Printf("failed to parse existing lock pid file (ignoring): %s\n", err)
+		return 0, createInstanceLock(lockFilePath)
+	}
+
+	// check if process exists
+	p, err := processInfo.NewProcess(int32(parsedPid))
+	if err == nil {
+		return p.Pid, nil
+	}
+
+	// else create new lock
+	return 0, createInstanceLock(lockFilePath)
+}
+
+func createInstanceLock(lockFilePath string) error {
+	// check data root dir
+	err := dataRoot.Ensure()
+	if err != nil {
+		log.Printf("failed to check data root dir: %s\n", err)
+	}
+
+	// create lock file
+	err = ioutil.WriteFile(lockFilePath, []byte(fmt.Sprintf("%d", os.Getpid())), 0666)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func deleteInstanceLock(name string) error {
+	lockFilePath := filepath.Join(dataRoot.Path, fmt.Sprintf("%s-lock.pid", name))
+	return os.Remove(lockFilePath)
+}