Backup and restore start-stop-daemon and initctl to prevent more serv…

…ices from starting during package installation

internal/helper/helper.go

@@ -20,8 +20,12 @@ import (
 )
 
 // define some functions that can be mocked by test cases
-var osRename = os.Rename
-var osRemove = os.Remove
+var (
+	osRename         = os.Rename
+	osRemove         = os.Remove
+	osWriteFile      = os.WriteFile
+	osutilFileExists = osutil.FileExists
+)
 
 func BoolPtr(b bool) *bool {
 	return &b
@@ -501,3 +505,42 @@ func RestoreResolvConf(chroot string) error {
 	}
 	return nil
 }
+
+const backupExt = ".REAL"
+
+// BackupReplace backup the target file and replace it with the given content
+// Returns the restore function.
+func BackupReplace(target string, content string) (func(error) error, error) {
+	backup := target + backupExt
+	if osutilFileExists(backup) {
+		// already backed up so do nothing
+		return nil, nil
+	}
+
+	if err := osRename(target, backup); err != nil {
+		return nil, fmt.Errorf("Error moving file \"%s\" to \"%s\": %s", target, backup, err.Error())
+	}
+
+	if err := osWriteFile(target, []byte(content), 0755); err != nil {
+		return nil, fmt.Errorf("Error writing to %s : %s", target, err.Error())
+	}
+
+	return genRestoreFile(target), nil
+}
+
+// genRestoreFile returns the function to be called to restore the backuped file
+func genRestoreFile(target string) func(err error) error {
+	return func(err error) error {
+		src := target + backupExt
+		if !osutilFileExists(src) {
+			return err
+		}
+
+		if tmpErr := osRename(src, target); tmpErr != nil {
+			tmpErr = fmt.Errorf("Error moving file \"%s\" to \"%s\": %s", src, target, tmpErr.Error())
+			return fmt.Errorf("%s\n%s", err, tmpErr)
+		}
+
+		return err
+	}
+}

internal/statemachine/classic_states.go

@@ -339,6 +339,28 @@ func (stateMachine *StateMachine) installPackages() error {
 		err = unsetDenyingPolicyRcD(err)
 	}()
 
+	restoreStartStopDaemon, err := backupReplaceStartStopDaemon(classicStateMachine.tempDirs.chroot)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		err = restoreStartStopDaemon(err)
+	}()
+
+	initctlPath := filepath.Join(classicStateMachine.tempDirs.chroot, "sbin", "initctl")
+
+	if osutil.FileExists(initctlPath) {
+		restoreInitctl, err := backupReplaceInitctl(classicStateMachine.tempDirs.chroot)
+		if err != nil {
+			return err
+		}
+
+		defer func() {
+			err = restoreInitctl(err)
+		}()
+	}
+
 	installPackagesCmds := generateAptCmds(stateMachine.tempDirs.chroot, classicStateMachine.Packages)
 
 	err = helper.RunCmds(installPackagesCmds, classicStateMachine.commonFlags.Debug)

internal/statemachine/helper.go

@@ -707,20 +707,29 @@ func dpkgDivert(baseDir string, target string) (*exec.Cmd, *exec.Cmd) {
 	return execCommand("chroot", divert...), execCommand("chroot", undivert...)
 }
 
-type mountPoint struct {
-	src     string
-	relpath string
-	path    string
-	typ     string
-	opts    []string
-	bind    bool
+// backupReplaceStartStopDaemon backup start-stop-daemon and replace it with a fake one
+// Returns a restore function to put the original one in place
+func backupReplaceStartStopDaemon(baseDir string) (func(error) error, error) {
+	const startStopDaemonContent = `#!/bin/sh
+echo
+echo "Warning: Fake start-stop-daemon called, doing nothing"
+`
+
+	startStopDaemon := filepath.Join(baseDir, "sbin", "start-stop-daemon")
+	return helper.BackupReplace(startStopDaemon, startStopDaemonContent)
 }
 
-func getUnmountCmd(targetPath string) []*exec.Cmd {
-	return []*exec.Cmd{
-		execCommand("mount", "--make-rprivate", targetPath),
-		execCommand("umount", "--recursive", targetPath),
-	}
+// backupReplaceInitctl backup initctl and replace it with a fake one
+// Returns a restore function to put the original one in place
+func backupReplaceInitctl(baseDir string) (func(error) error, error) {
+	const initctlContent = `#!/bin/sh
+if [ "$1" = version ]; then exec /sbin/initctl.REAL "$@"; fi
+echo
+echo "Warning: Fake initctl called, doing nothing"
+`
+
+	initctl := filepath.Join(baseDir, "sbin", "initctl")
+	return helper.BackupReplace(initctl, initctlContent)
 }
 
 // getMountCmd returns mount/umount commands to mount the given mountpoint
@@ -777,47 +786,6 @@ func getNewMountPoints(olds []mountPoint, currents []mountPoint) []mountPoint {
 	return news
 }
 
-func listMounts(path string) ([]mountPoint, error) {
-	procMounts := "/proc/self/mounts"
-	f, err := osReadFile(procMounts)
-	if err != nil {
-		return nil, err
-	}
-
-	return parseMounts(string(f), path)
-}
-
-// parseMounts list existing mounts and submounts in the current path
-// The returned splice is already inverted so unmount can be called on it
-// without further modification.
-func parseMounts(procMount string, path string) ([]mountPoint, error) {
-	mountPoints := []mountPoint{}
-	mountLines := strings.Split(procMount, "\n")
-
-	for _, line := range mountLines {
-		if line == "" {
-			continue
-		}
-
-		fields := strings.Fields(line)
-		mountPath := fields[1]
-
-		if len(path) != 0 && !strings.HasPrefix(mountPath, path) {
-			continue
-		}
-
-		m := mountPoint{
-			src:  fields[0],
-			path: mountPath,
-			typ:  fields[2],
-			opts: strings.Split(fields[3], ","),
-		}
-		mountPoints = append([]mountPoint{m}, mountPoints...)
-	}
-
-	return mountPoints, nil
-}
-
 // execTeardownCmds executes given commands and collects error to join them with an existing error.
 // Failure to execute one command will not stop from executing following ones.
 func execTeardownCmds(teardownCmds []*exec.Cmd, debug bool, prevErr error) (err error) {