Separate root remounting into new function and improve killProcesses function

src/enit/main.go

@@ -195,7 +195,8 @@ func killProcesses() {
 		return
 	}
 	for _, process := range processes {
-		if process.Pid() == 1 {
+		sid, _, _ := syscall.Syscall(syscall.SYS_GETSID, uintptr(process.Pid()), 0, 0)
+		if process.Pid() == 1 || sid == 1 {
 			continue
 		}
 
@@ -210,7 +211,8 @@ func killProcesses() {
 		return
 	}
 	for _, process := range processes {
-		if process.Pid() == 1 {
+		sid, _, _ := syscall.Syscall(syscall.SYS_GETSID, uintptr(process.Pid()), 0, 0)
+		if process.Pid() == 1 || sid == 1 {
 			continue
 		}
 
@@ -270,6 +272,7 @@ func shutdownSystem() {
 	stopServiceManager()
 	killProcesses()
 	unmountFilesystems()
+	remountRootReadonly()
 
 	fmt.Print("Syncing disks... ")
 	syscall.Sync()
@@ -288,6 +291,7 @@ func rebootSystem() {
 	stopServiceManager()
 	killProcesses()
 	unmountFilesystems()
+	remountRootReadonly()
 
 	fmt.Print("Syncing disks... ")
 	syscall.Sync()

src/enit/mount.go

@@ -241,11 +241,6 @@ func unmountFilesystems() {
 		log.Fatal(err)
 	}
 
-	// Reserve variables for root filesytem
-	rootSource := ""
-	rootFilesystem := ""
-	rootData := ""
-
 	// Unmount filesystems
 	entries := strings.Split(string(data), "\n")
 	slices.Reverse(entries)
@@ -259,17 +254,18 @@ func unmountFilesystems() {
 		fields := strings.Fields(entry)
 		mountpoint := fields[4]
 		filesystem := ""
-		source := ""
-		data := ""
 		for i := 6; i < len(fields); i++ {
 			if fields[i] == "-" {
 				filesystem = fields[i+1]
-				source = fields[i+2]
-				data = fields[i+3]
 				break
 			}
 		}
 
+		// Skip root filesystem
+		if mountpoint == "/" {
+			continue
+		}
+
 		// Skip root and ignored filesystems
 		ignoredFilesystems := []string{
 			"devtmpfs",
@@ -277,12 +273,6 @@ func unmountFilesystems() {
 			"sysfs",
 			"tmpfs",
 		}
-		if mountpoint == "/" {
-			rootSource = source
-			rootFilesystem = filesystem
-			_, rootData, _ = convertMountOptions(data)
-			continue
-		}
 
 		if slices.Contains(ignoredFilesystems, filesystem) {
 			continue
@@ -311,11 +301,49 @@ func unmountFilesystems() {
 			}
 		}
 	}
+}
 
+func remountRootReadonly() {
 	fmt.Print("Remounting root as read-only...")
+
+	data, err := os.ReadFile("/proc/self/mountinfo")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	filesystem := ""
+	source := ""
+	fsData := ""
+
+	// Get root filesystems
+	entries := strings.Split(string(data), "\n")
+	slices.Reverse(entries)
+	for _, entry := range entries {
+		entry = strings.TrimSpace(entry)
+		if len(entry) == 0 {
+			continue
+		}
+
+		// Get entry fields
+		fields := strings.Fields(entry)
+		mountpoint := fields[4]
+		for i := 6; i < len(fields); i++ {
+			if fields[i] == "-" {
+				filesystem = fields[i+1]
+				source = fields[i+2]
+				fsData = fields[i+3]
+				break
+			}
+		}
+
+		if mountpoint == "/" {
+			break
+		}
+	}
+
 	tries := 0
 	for {
-		err = unix.Mount(rootSource, "/", rootFilesystem, syscall.MS_RDONLY|syscall.MS_REMOUNT, rootData)
+		err := unix.Mount(source, "/", filesystem, syscall.MS_RDONLY|syscall.MS_REMOUNT, fsData)
 		if errors.Is(err, syscall.EBUSY) {
 			fmt.Print(".")
 			tries++