From 4121203174e066736850e99b17b60b31f75800d2 Mon Sep 17 00:00:00 2001
From: Daniel Baumgarten <incognym@googlemail.com>
Date: Mon, 23 Jul 2018 23:57:46 +0200
Subject: [PATCH] Automatically unmount on termination

---
 afs/addfs.go | 17 +++++++++++++++--
 main.go      | 25 +++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/afs/addfs.go b/afs/addfs.go
index 222d1d4..79d5540 100644
--- a/afs/addfs.go
+++ b/afs/addfs.go
@@ -1,8 +1,10 @@
 package afs
 
 import (
+	"errors"
 	"flag"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"regexp"
 	"time"
@@ -17,6 +19,7 @@ type AddFS struct {
 	pathfs.FileSystem
 	opts                AddFSOpts
 	mutableFilesRegexes []*regexp.Regexp
+	mountpoint          string
 }
 
 type AddFSOpts struct {
@@ -30,6 +33,7 @@ func NewAddFS(source string, opts AddFSOpts) (*AddFS, error) {
 		pathfs.NewLoopbackFileSystem(source),
 		opts,
 		make([]*regexp.Regexp, len(opts.MutableFiles)),
+		"",
 	}
 	for i, v := range opts.MutableFiles {
 		var err error
@@ -41,7 +45,7 @@ func NewAddFS(source string, opts AddFSOpts) (*AddFS, error) {
 	return fs, nil
 }
 
-func (fs *AddFS) Run() error {
+func (fs *AddFS) Mount(mountpoint string) error {
 	origAbs, _ := filepath.Abs(flag.Arg(0))
 	mOpts := &fuse.MountOptions{
 		Options:    []string{"default_permissions"},
@@ -57,14 +61,23 @@ func (fs *AddFS) Run() error {
 	}
 	pathNode := pathfs.NewPathNodeFs(fs, &pathfs.PathNodeFsOptions{})
 	conn := nodefs.NewFileSystemConnector(pathNode.Root(), opts)
-	server, err := fuse.NewServer(conn.RawFS(), flag.Arg(1), mOpts)
+	server, err := fuse.NewServer(conn.RawFS(), mountpoint, mOpts)
 	if err != nil {
 		return err
 	}
+	fs.mountpoint = mountpoint
 	server.Serve()
 	return nil
 }
 
+func (fs *AddFS) Unmount() error {
+	if fs.mountpoint == "" {
+		return errors.New("cannot unmount before successfully mounting")
+	}
+	umcmd := exec.Command("fusermount", "-u", fs.mountpoint)
+	return umcmd.Run()
+}
+
 func (fs *AddFS) rootUserPermit(context *fuse.Context) bool {
 	return fs.opts.AllowRootMutation && context.Uid == 0
 }
diff --git a/main.go b/main.go
index c67e53c..8bc8030 100644
--- a/main.go
+++ b/main.go
@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"os/signal"
 	"syscall"
 
 	"github.com/dbaumgarten/addfs/afs"
@@ -21,6 +22,7 @@ Possible flags:
 
 var allowRootMutation = flag.Bool("allowRootMutation", false, "Allow the root-user to mutate files and folders")
 var ignoreWarnings = flag.Bool("ignoreWarnings", false, "Ignore all errors about file-ownership. ONLY USE IF YOU KNOW WHAT YOU ARE DOING!")
+var keepMounted = flag.Bool("keepMounted", false, "Do not attempt to unmount on exiting")
 var mutableFiles arrayFlags
 
 func main() {
@@ -37,7 +39,7 @@ func main() {
 
 	if !*ignoreWarnings {
 		if os.Getegid() != 0 {
-			fmt.Println("WARNING!: Not running. Only directories that are write-accessible for the user can be mounted. This defeats  addfs' write-protection. Aborting for safety-reasons.")
+			fmt.Println("WARNING!: Not running as root. Only directories that are write-accessible for the user can be mounted. This defeats  addfs' write-protection. Aborting for safety-reasons.")
 			os.Exit(1)
 		}
 		err := checkSourceDirectory(flag.Arg(0))
@@ -56,14 +58,33 @@ func main() {
 		fmt.Println("Error: ", err)
 		os.Exit(1)
 	}
+
+	if !*keepMounted {
+		c := make(chan os.Signal, 1)
+		signal.Notify(c, os.Interrupt)
+		go unmountOnInterrupt(afs, c)
+	}
+
 	fmt.Println("Starting FUSE-Filesystem!")
-	err = afs.Run()
+	err = afs.Mount(flag.Arg(1))
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
 }
 
+func unmountOnInterrupt(afs *afs.AddFS, c chan os.Signal) {
+	for _ = range c {
+		fmt.Println("Unmounting...")
+		err := afs.Unmount()
+		if err != nil {
+			fmt.Println("Error when unmounting:", err)
+			os.Exit(1)
+		}
+		fmt.Println("Successfully unmounted!")
+	}
+}
+
 func checkSourceDirectory(path string) error {
 	stat, err := os.Stat(path)
 	if err != nil {