1 files changed, 99 insertions, 0 deletions
diff --git a/pkg/systray/pid.go b/pkg/systray/pid.go
new file mode 100644
index 0000000..6a1b32c
--- /dev/null
+++ b/pkg/systray/pid.go
@@ -0,0 +1,99 @@
+package systray
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"0xacab.org/leap/bitmask-systray/pkg/config"
+	"github.com/mitchellh/go-ps"
+)
+
+var pidFile = filepath.Join(config.Path, "systray.pid")
+
+func acquirePID() error {
+	pid := syscall.Getpid()
+	current, err := getPID()
+	if err != nil {
+		return err
+	}
+
+	if current != pid && pidRunning(current) {
+		return fmt.Errorf("Another systray is running with pid: %d", current)
+	}
+
+	return setPID(pid)
+}
+
+func releasePID() error {
+	pid := syscall.Getpid()
+	current, err := getPID()
+	if err != nil {
+		return err
+	}
+	if current != 0 && current != pid {
+		return fmt.Errorf("Can't release pid file, is not own by this process")
+	}
+
+	if current == pid {
+		return os.Remove(pidFile)
+	}
+	return nil
+}
+
+func getPID() (int, error) {
+	_, err := os.Stat(pidFile)
+	if os.IsNotExist(err) {
+		return 0, nil
+	}
+	if err != nil {
+		return 0, err
+	}
+
+	file, err := os.Open(pidFile)
+	if err != nil {
+		return 0, err
+	}
+	defer file.Close()
+
+	b, err := ioutil.ReadAll(file)
+	if err != nil {
+		return 0, err
+	}
+	if len(b) == 0 {
+		return 0, nil
+	}
+	return strconv.Atoi(string(b))
+}
+
+func setPID(pid int) error {
+	file, err := os.Create(pidFile)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	_, err = file.WriteString(fmt.Sprintf("%d", pid))
+	return err
+}
+
+func pidRunning(pid int) bool {
+	if pid == 0 {
+		return false
+	}
+	proc, err := ps.FindProcess(pid)
+	if err != nil {
+		log.Printf("An error ocurred finding process: %v", err)
+		return false
+	}
+	if proc == nil {
+		return false
+	}
+	log.Printf("There is a running process with the pid %d and executable: %s", pid, proc.Executable())
+	return strings.Contains(os.Args[0], proc.Executable())
+}