From 802ae36a019aa135892f4681b1664aa30ad8b8d4 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Sat, 10 Jan 2026 14:56:59 +0100
Subject: [PATCH 01/17] feat(root): refactor root access

step 1 restore outdated and buggy old root code
---
 app/build.gradle.kts                          |  1 +
 .../activities/LogActivity.java               |  2 +-
 .../activities/SettingsActivity.java          | 61 +++++++++++++-
 .../receiver/BootReceiver.java                | 17 ++++
 .../syncthingandroid/service/Constants.java   |  1 +
 .../service/SyncthingRunnable.java            | 35 ++++++--
 .../service/SyncthingService.java             |  1 -
 .../syncthingandroid/util/ConfigXml.java      |  4 +-
 .../nutomic/syncthingandroid/util/Util.java   | 80 ++++++++++++++++---
 app/src/main/res/values/strings.xml           |  5 ++
 app/src/main/res/xml/app_settings.xml         |  8 ++
 gradle/libs.versions.toml                     |  2 +
 12 files changed, 197 insertions(+), 20 deletions(-)

diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 7b926e030..9f6251348 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -26,6 +26,7 @@ dependencies {
     implementation(libs.gson)
     implementation(libs.guava)
     implementation(libs.jbcrypt)
+    implementation(libs.libsuperuser)
     implementation(libs.lingala.zip4j)
     implementation(libs.localbroadcastmanager)
     implementation(libs.preference.ktx)
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java b/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java
index f97ca6953..2105be876 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java
@@ -191,7 +191,7 @@ protected void onPostExecute(Void aVoid) {
          * @param syncthingLog Filter on Syncthing's native messages.
          */
         private String getAndroidLog() {
-            String output = Util.runShellCommandGetOutput("/system/bin/logcat -t " + Integer.toString(ANDROID_LOG_FILE_MAX_LINES) + " -v time *:i ps:s art:s");
+            String output = Util.runShellCommandGetOutput("/system/bin/logcat -t " + Integer.toString(ANDROID_LOG_FILE_MAX_LINES) + " -v time *:i ps:s art:s", false);
 
             // Filter Android log.
             output = output.replaceAll("I/SyncthingNativeCode", "");
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/activities/SettingsActivity.java b/app/src/main/java/com/nutomic/syncthingandroid/activities/SettingsActivity.java
index a5114f664..cab245141 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/activities/SettingsActivity.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/activities/SettingsActivity.java
@@ -68,6 +68,8 @@
 
 import javax.inject.Inject;
 
+import eu.chainfire.libsuperuser.Shell;
+
 public class SettingsActivity extends SyncthingActivity {
 
     private static final String TAG = "SettingsActivity";
@@ -179,6 +181,7 @@ public static class SettingsFragment extends PreferenceFragment
 
         /* Behaviour */
         private CheckBoxPreference mStartServiceOnBoot;
+        private CheckBoxPreference mUseRoot;
 
         /* Syncthing Options */
         private PreferenceScreen   mCategorySyncthingOptions;
@@ -306,6 +309,9 @@ public void onActivityCreated(Bundle savedInstanceState) {
             PreferenceScreen categoryBehaviour = (PreferenceScreen) findPreference("category_behaviour");
             mStartServiceOnBoot =
                     (CheckBoxPreference) findPreference(Constants.PREF_START_SERVICE_ON_BOOT);
+            mUseRoot =
+                    (CheckBoxPreference) findPreference(Constants.PREF_USE_ROOT);
+            setPreferenceCategoryChangeListener(categoryBehaviour, this::onBehaviourPreferenceChange);
 
             /* Syncthing Options */
             mDeviceName             = (EditTextPreference) findPreference("deviceName");
@@ -620,6 +626,20 @@ public boolean onUserInterfacePreferenceChange(Preference preference, Object o)
             return true;
         }
 
+        public boolean onBehaviourPreferenceChange(Preference preference, Object o) {
+            switch (preference.getKey()) {
+                case Constants.PREF_USE_ROOT:
+                    if ((Boolean) o) {
+                        new TestRootTask(this).execute();
+                    } else {
+                        new Thread(() -> Util.fixAppDataPermissions(getActivity())).start();
+                        mPendingConfig = true;
+                    }
+                    break;
+            }
+            return true;
+        }
+
         public boolean onSyncthingPreferenceChange(Preference preference, Object o) {
             Splitter splitter = Splitter.on(",").trimResults().omitEmptyStrings();
             switch (preference.getKey()) {
@@ -941,6 +961,43 @@ private static AlertDialog.Builder getAppRestartConfirmationDialog(Activity acti
                     .setNegativeButton(android.R.string.no, (dialogInterface, i) -> {});
         }
 
+        /**
+         * Enables or disables {@link #mUseRoot} preference depending whether root is available.
+         */
+        private static class TestRootTask extends AsyncTask<Void, Void, Boolean> {
+            private WeakReference<SettingsFragment> refSettingsFragment;
+
+            TestRootTask(SettingsFragment context) {
+                refSettingsFragment = new WeakReference<>(context);
+            }
+
+            @Override
+            protected Boolean doInBackground(Void... params) {
+                return Shell.SU.available();
+            }
+
+            @Override
+            protected void onPostExecute(Boolean haveRoot) {
+                // Get a reference to the fragment if it is still there.
+                SettingsFragment settingsFragment = refSettingsFragment.get();
+                if (settingsFragment == null) {
+                    return;
+                }
+                settingsFragment.mUseRoot.setOnPreferenceChangeListener(null);
+                settingsFragment.mUseRoot.setChecked(haveRoot);
+                if (haveRoot) {
+                    settingsFragment.mPendingConfig = true;
+                } else {
+                    SyncthingActivity syncthingActivity = (SyncthingActivity) settingsFragment.getActivity();
+                    if (syncthingActivity != null && !syncthingActivity.isFinishing()) {
+                        Toast.makeText(syncthingActivity, R.string.toast_root_denied, Toast.LENGTH_SHORT)
+                                .show();
+                    }
+                }
+                settingsFragment.mUseRoot.setOnPreferenceChangeListener(settingsFragment::onBehaviourPreferenceChange);
+            }
+        }
+
         /**
          * Performs export of settings, config and database in the background.
          */
@@ -1109,7 +1166,7 @@ private boolean handleHttpProxyPreferenceChange(Preference preference, String ne
          */
         private String getDatabaseSize() {
             String dbPath = Constants.getIndexDbFolder(mContext).getAbsolutePath();
-            String result = Util.runShellCommandGetOutput("/system/bin/du -sh " + dbPath);
+            String result = Util.runShellCommandGetOutput("/system/bin/du -sh " + dbPath, false);
             if (TextUtils.isEmpty(result)) {
                 return "N/A";
             }
@@ -1128,7 +1185,7 @@ private String getOpenFileLimit() {
             if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
                 shellCommand = "/system/bin/" + shellCommand;
             }
-            String result = Util.runShellCommandGetOutput(shellCommand);
+            String result = Util.runShellCommandGetOutput(shellCommand, false);
             if (TextUtils.isEmpty(result)) {
                 return "N/A";
             }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
index a8360de97..4cbba25e3 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
@@ -12,6 +12,8 @@
 import com.nutomic.syncthingandroid.service.SyncthingRunnable;
 import com.nutomic.syncthingandroid.service.SyncthingService;
 
+import eu.chainfire.libsuperuser.Shell;
+
 import java.lang.SecurityException;
 
 public class BootReceiver extends BroadcastReceiver {
@@ -30,6 +32,16 @@ public void onReceive(Context context, Intent intent) {
             return;
         }
 
+        if (packageReplaced) {
+            if (getPrefUseRoot(context) && Shell.SU.available()) {
+                /**
+                 * In Root mode, there will be a SyncthingNative process left running after app update.
+                 */
+                Log.d(TAG, "ACTION_MY_PACKAGE_REPLACED: Killing leftover SyncthingNative instance if present ...");
+                new SyncthingRunnable(context, SyncthingRunnable.Command.main).killSyncthing();
+            }
+        }
+
         // Check if we should (re)start now.
         if (!getPrefStartServiceOnBoot(context)) {
             return;
@@ -57,4 +69,9 @@ private static boolean getPrefStartServiceOnBoot(Context context) {
         SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
         return sp.getBoolean(Constants.PREF_START_SERVICE_ON_BOOT, false);
     }
+
+    private static boolean getPrefUseRoot(Context context) {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
+        return sp.getBoolean(Constants.PREF_USE_ROOT, false);
+    }
 }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/Constants.java b/app/src/main/java/com/nutomic/syncthingandroid/service/Constants.java
index 579f01a9c..d414d732a 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/Constants.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/Constants.java
@@ -52,6 +52,7 @@ private PowerSource() { }
     // Preferences - Behaviour
     public static final String PREF_START_SERVICE_ON_BOOT       = "always_run_in_background";
     public static final String PREF_BROADCAST_SERVICE_CONTROL   = "broadcast_service_control";
+    public static final String PREF_USE_ROOT                    = "use_root";
     public static final String PREF_ALLOW_OVERWRITE_FILES       = "allow_overwrite_files";
 
     // Preferences - Syncthing Options
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
index d54b11866..9e3981b23 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
@@ -47,6 +47,8 @@
 
 import javax.inject.Inject;
 
+import eu.chainfire.libsuperuser.Shell;
+
 import static com.nutomic.syncthingandroid.service.SyncthingService.EXTRA_STOP_AFTER_CRASHED_NATIVE;
 
 /**
@@ -68,6 +70,7 @@ public class SyncthingRunnable implements Runnable {
     private final File mSyncthingBinary;
     private String[] mCommand;
     private final File mSyncthingLogFile;
+    private final boolean mUseRoot;
 
     @Inject
     SharedPreferences mPreferences;
@@ -97,6 +100,7 @@ public SyncthingRunnable(Context context, Command command) {
         mSyncthingLogFile = Constants.getSyncthingLogFile(mContext);
 
         // Get preferences relevant to starting syncthing core.
+        mUseRoot = mPreferences.getBoolean(Constants.PREF_USE_ROOT, false) && Shell.SU.available();
         switch (command) {
             case deviceid:
                 mCommand = new String[]{mSyncthingBinary.getPath(), "device-id"};
@@ -270,7 +274,7 @@ private void putCustomEnvironmentVariables(Map<String, String> environment, Shar
      */
     private List<String> getSyncthingPIDs(Boolean enableLog) {
         List<String> syncthingPIDs = new ArrayList<String>();
-        String output = Util.runShellCommandGetOutput("ps\n");
+        String output = Util.runShellCommandGetOutput("ps\n", mUseRoot);
         if (TextUtils.isEmpty(output)) {
             Log.w(TAG, "Failed to list SyncthingNative processes. ps command returned empty.");
             return syncthingPIDs;
@@ -306,7 +310,7 @@ public void killSyncthing() {
             return;
         }
         for (String syncthingPID : syncthingPIDs) {
-            exitCode = Util.runShellCommand("kill -SIGINT " + syncthingPID + "\n");
+            exitCode = Util.runShellCommand("kill -SIGINT " + syncthingPID + "\n", mUseRoot);
             if (exitCode == 0) {
                 LogV("Sent kill SIGINT to process " + syncthingPID);
             } else {
@@ -458,9 +462,30 @@ private Process setupAndLaunch(HashMap<String, String> env) throws IOException,
                 throw new ExecutableNotFoundException(mCommand[0]);
             }
         }
-        ProcessBuilder pb = new ProcessBuilder(mCommand);
-        pb.environment().putAll(env);
-        return pb.start();
+
+        if (mUseRoot) {
+            ProcessBuilder pb = new ProcessBuilder("su");
+            Process process = pb.start();
+            // The su binary prohibits the inheritance of environment variables.
+            // Even with --preserve-environment the environment gets messed up.
+            // We therefore start a root shell, and set all the environment variables manually.
+            DataOutputStream suOut = new DataOutputStream(process.getOutputStream());
+            for (Map.Entry<String, String> entry : env.entrySet()) {
+                suOut.writeBytes(String.format("export %s=\"%s\"\n", entry.getKey(), entry.getValue()));
+            }
+            suOut.flush();
+            // Exec will replace the su process image by Syncthing as execlp in C does.
+            // Without using exec, the process will drop to the root shell as soon as Syncthing terminates like a normal shell does.
+            // If we did not use exec, we would wait infinitely for the process to terminate (ret = process.waitFor(); in run()).
+            // With exec the whole process terminates when Syncthing exits.
+            suOut.writeBytes("exec " + TextUtils.join(" ", mCommand) + "\n");
+            suOut.flush();
+            return process;
+        } else {
+            ProcessBuilder pb = new ProcessBuilder(mCommand);
+            pb.environment().putAll(env);
+            return pb.start();
+        }
     }
 
     public class ExecutableNotFoundException extends Exception {
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
index e694d3c28..97d36f06d 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
@@ -1095,7 +1095,6 @@ private boolean importConfigSharedPrefs(final File file) {
                         case "pref_current_language":
                         case "restartOnWakeup":
                         case "wakelock_while_binary_running":
-                        case "use_root":
                             LogV("importConfig: Ignoring deprecated pref \"" + prefKey + "\".");
                             break;
                         // Cached information which is not available on SettingsActivity.
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/ConfigXml.java b/app/src/main/java/com/nutomic/syncthingandroid/util/ConfigXml.java
index e290399dc..44278ab9b 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/ConfigXml.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/ConfigXml.java
@@ -225,7 +225,7 @@ private String getLocalDeviceIDandStoreToPref() throws SyncthingRunnable.Executa
     }
 
     private void parseConfig() {
-        if (!mConfigFile.canRead()) {
+        if (!mConfigFile.canRead() && !Util.fixAppDataPermissions(mContext)) {
             Log.w(TAG, "Failed to open config file '" + mConfigFile + "'");
             throw new OpenConfigException();
         }
@@ -1257,7 +1257,7 @@ private boolean addSyncthingCameraFolder() {
      * Writes updated mConfig back to file.
      */
     public void saveChanges() {
-        if (!mConfigFile.canWrite()) {
+        if (!mConfigFile.canWrite() && !Util.fixAppDataPermissions(mContext)) {
             Log.w(TAG, "Failed to save updated config. Cannot change the owner of the config file.");
             return;
         }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index c3b4482f8..394e2a410 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -31,6 +31,8 @@
 import java.time.ZoneOffset;
 import java.util.Locale;
 
+import eu.chainfire.libsuperuser.Shell;
+
 public class Util {
 
     private static final String TAG = "Util";
@@ -66,16 +68,76 @@ public static String readableTransferRate(Context context, long bits) {
                 .format(bytes / Math.pow(1024, digitGroups)) + " " + units[digitGroups];
     }
 
+    /**
+     * Normally an application's data directory is only accessible by the corresponding application.
+     * Therefore, every file and directory is owned by an application's user and group. When running Syncthing as root,
+     * it writes to the application's data directory. This leaves files and directories behind which are owned by root having 0600.
+     * Moreover, those actions performed as root changes a file's type in terms of SELinux.
+     * A subsequent start of Syncthing will fail due to insufficient permissions.
+     * Hence, this method fixes the owner, group and the files' type of the data directory.
+     *
+     * @return true if the operation was successfully performed. False otherwise.
+     */
+    public static boolean fixAppDataPermissions(Context context) {
+        // We can safely assume that root magic is somehow available, because readConfig and saveChanges check for
+        // read and write access before calling us.
+        // Be paranoid :) and check if root is available.
+        // Ignore the 'use_root' preference, because we might want to fix the permission
+        // just after the root option has been disabled.
+        if (!Shell.SU.available()) {
+            Log.e(TAG, "Root is not available. Cannot fix permissions.");
+            return false;
+        }
+
+        String packageName;
+        ApplicationInfo appInfo;
+        try {
+            packageName = context.getPackageName();
+            appInfo = context.getPackageManager().getApplicationInfo(packageName, 0);
+
+        } catch (NameNotFoundException e) {
+            // This should not happen!
+            // One should always be able to retrieve the application info for its own package.
+            Log.w(TAG, "Error getting current package name", e);
+            return false;
+        }
+        Log.d(TAG, "Uid of '" + packageName + "' is " + appInfo.uid);
+
+        // Get private app's "files" dir residing in "/data/data/[packageName]".
+        String dir = context.getFilesDir().getAbsolutePath();
+        String cmd = "chown -R " + appInfo.uid + ":" + appInfo.uid + " " + dir + "; ";
+        // Running Syncthing as root might change a file's or directories type in terms of SELinux.
+        // Leaving them as they are, the Android service won't be able to access them.
+        // At least for those files residing in an application's data folder.
+        // Simply reverting the type to its default should do the trick.
+        cmd += "restorecon -R " + dir + "\n";
+        Log.d(TAG, "Running: '" + cmd);
+        int exitCode = runShellCommand(cmd, true);
+        if (exitCode == 0) {
+            Log.i(TAG, "Fixed app data permissions on '" + dir + "'.");
+        } else {
+            Log.w(TAG, "Failed to fix app data permissions on '" + dir + "'. Result: " +
+                Integer.toString(exitCode));
+        }
+        return exitCode == 0;
+    }
+
     /**
      * Returns if the syncthing binary would be able to write a file into
      * the given folder given the configured access level.
      */
     public static boolean nativeBinaryCanWriteToPath(Context context, String absoluteFolderPath) {
         final String TOUCH_FILE_NAME = ".stwritetest";
+        Boolean useRoot = false;
+        Boolean prefUseRoot = PreferenceManager.getDefaultSharedPreferences(context)
+            .getBoolean(Constants.PREF_USE_ROOT, false);
+        if (prefUseRoot && Shell.SU.available()) {
+            useRoot = true;
+        }
 
         // Write permission test file.
         String touchFile = absoluteFolderPath + "/" + TOUCH_FILE_NAME;
-        int exitCode = runShellCommand("echo \"\" > \"" + touchFile + "\"\n");
+        int exitCode = runShellCommand("echo \"\" > \"" + touchFile + "\"\n", useRoot);
         if (exitCode != 0) {
             String error;
             switch (exitCode) {
@@ -94,7 +156,7 @@ public static boolean nativeBinaryCanWriteToPath(Context context, String absolut
         Log.i(TAG, "Successfully wrote test file '" + touchFile + "'");
 
         // Remove test file.
-        if (runShellCommand("rm \"" + touchFile + "\"\n") != 0) {
+        if (runShellCommand("rm \"" + touchFile + "\"\n", useRoot) != 0) {
             // This is very unlikely to happen, so we have less error handling.
             Log.i(TAG, "Failed to remove test file");
         }
@@ -104,14 +166,14 @@ public static boolean nativeBinaryCanWriteToPath(Context context, String absolut
     /**
      * Run command in a shell and return the exit code.
      */
-    public static int runShellCommand(String cmd) {
+    public static int runShellCommand(String cmd, Boolean useRoot) {
         // Assume "failure" exit code if an error is caught.
         // Note: redirectErrorStream(true); System.getProperty("line.separator");
         int exitCode = 255;
         Process shellProc = null;
         DataOutputStream shellOut = null;
         try {
-            shellProc = Runtime.getRuntime().exec("sh");
+            shellProc = Runtime.getRuntime().exec((useRoot) ? "su" : "sh");
             shellOut = new DataOutputStream(shellProc.getOutputStream());
             BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(shellOut));
             Log.d(TAG, "runShellCommand: " + cmd);
@@ -151,14 +213,14 @@ public static int runShellCommand(String cmd) {
         return exitCode;
     }
 
-    public static String runShellCommandGetOutput(String cmd) {
+    public static String runShellCommandGetOutput(String cmd, Boolean useRoot) {
         // Note: redirectErrorStream(true); System.getProperty("line.separator");
         int exitCode = 255;
         String capturedStdOut = "";
         Process shellProc = null;
         DataOutputStream shellOut = null;
         try {
-            shellProc = Runtime.getRuntime().exec("sh");
+            shellProc = Runtime.getRuntime().exec((useRoot) ? "su" : "sh");
             shellOut = new DataOutputStream(shellProc.getOutputStream());
             BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(shellOut));
             Log.d(TAG, "runShellCommandGetOutput: " + cmd);
@@ -209,7 +271,7 @@ public static String runShellCommandGetOutput(String cmd) {
      */
     public static Boolean isTcpPortListening(Integer port) {
         // t: tcp, l: listening, n: numeric
-        String output = runShellCommandGetOutput("netstat -t -l -n");
+        String output = runShellCommandGetOutput("netstat -t -l -n", false);
         if (TextUtils.isEmpty(output)) {
             Log.w(TAG, "isTcpPortListening: Failed to run netstat. Returning false.");
             return false;
@@ -430,7 +492,7 @@ public boolean accept(File dir, String name) {
             // Execute script.
             String command = cmdBuilder.toString();
             // Log.d(TAG, "runScriptSet: Exec [" + command + "]");
-            Log.v(TAG, "runScriptSet: Exec result [" + runShellCommandGetOutput(command) + "]");
+            Log.v(TAG, "runScriptSet: Exec result [" + runShellCommandGetOutput(command, false) + "]");
         }
     }
     
@@ -445,7 +507,7 @@ public static String[] getSyncConflictFiles(final String absPath) {
         cmdBuilder.append("find -type f -name \"*\\.sync-conflict-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]-[a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9]*\" -not -path \"\\.\\/\\" + Constants.FOLDER_NAME_STVERSIONS + "\\/*\" -print | sed \"s~\\\\.\\/~~\"");
         String command = cmdBuilder.toString();
         // Log.v(TAG, "getSyncConflictFileCount: Exec [" + command + "]");
-        String output = runShellCommandGetOutput(command);
+        String output = runShellCommandGetOutput(command, false);
         // Log.v(TAG, "getSyncConflictFileCount: Exec result [" + output + "]");
         if (output == null || output.isEmpty()) {
             return new String[]{};
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 9cbb26c85..bfed4944a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -410,6 +410,9 @@
     <!-- Shown if no folders are configured -->
     <string name="folders_list_empty">No folders configured. Tap to add a new folder.</string>
 
+    <!-- Toast show if we could not get root permissions -->
+    <string name="toast_root_denied">Did not get root permissions</string>
+
     <!-- RecentChangesActivity -->
 
     <string name="no_recent_changes">There are no recent changes.</string>
@@ -520,6 +523,8 @@
     <string name="behaviour_autostart_title">Autostart</string>
     <string name="behaviour_autostart_summary">Start app automatically on operating system startup.</string>
 
+    <string name="use_root_title">Run Syncthing as Superuser</string>
+    <string name="use_root_summary">Running Syncthing as root allows it to write to folders Android normally restricts to be readonly accessed. Use this feature with caution.</string>
 
     <string name="allow_overwrite_files_title">Allow overwrite of existing files</string>
     <string name="allow_overwrite_files_summary">When another app shares files to one of our folders.</string>
diff --git a/app/src/main/res/xml/app_settings.xml b/app/src/main/res/xml/app_settings.xml
index f6bf59aec..073b4d593 100644
--- a/app/src/main/res/xml/app_settings.xml
+++ b/app/src/main/res/xml/app_settings.xml
@@ -166,6 +166,14 @@
             android:summary="@string/broadcast_service_control_summary"
             android:singleLineTitle="false" />
 
+        <!-- Use root -->
+        <CheckBoxPreference
+            android:key="use_root"
+            android:title="@string/use_root_title"
+            android:summary="@string/use_root_summary"
+            android:singleLineTitle="false"
+            android:defaultValue="false" />
+
         <!-- Allow overwrite of existing files -->
         <CheckBoxPreference
             android:key="allow_overwrite_files"
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index d54831cf8..405ebd2c5 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -30,6 +30,7 @@ guava = "33.5.0-android"
 jbcrypt = "0.4"
 kotlin = "2.3.0"
 ksp = "2.3.4"
+libsuperuser = "1.1.1"
 lingala-zip4j = "2.11.5"
 localbroadcastmanager = "1.1.0"
 preference-ktx = "1.2.1"
@@ -59,6 +60,7 @@ fragment-ktx = { module = "androidx.fragment:fragment-ktx", version.ref = "fragm
 gson = { module = "com.google.code.gson:gson", version.ref = "gson" }
 guava = { module = "com.google.guava:guava", version.ref = "guava" }
 jbcrypt = { module = "org.mindrot:jbcrypt", version.ref = "jbcrypt" }
+libsuperuser = { module = "eu.chainfire:libsuperuser", version.ref = "libsuperuser" }
 lingala-zip4j = { module = "net.lingala.zip4j:zip4j", version.ref = "lingala-zip4j" }
 localbroadcastmanager = { module = "androidx.localbroadcastmanager:localbroadcastmanager", version.ref = "localbroadcastmanager" }
 preference-ktx = { module = "androidx.preference:preference-ktx", version.ref = "preference-ktx" }

From 5d03d3967aaab40175e54301e27a06628c4929f0 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Sat, 10 Jan 2026 15:05:57 +0100
Subject: [PATCH 02/17] readd imports dropped in
 e778efb4d6e0fc30f4ff8fabeb8c0567537a66c7

---
 app/src/main/java/com/nutomic/syncthingandroid/util/Util.java | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index 394e2a410..caf1ba364 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -3,12 +3,15 @@
 import android.app.Dialog;
 import android.app.UiModeManager;
 import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.res.Configuration;
 import android.os.Build;
 import android.text.TextUtils;
 import android.util.Log;
 
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.preference.PreferenceManager;
 
 import com.google.common.base.Charsets;
 import com.nutomic.syncthingandroid.R;

From 6b8d6e4b826a087bbd32758919a833f09f37a2dc Mon Sep 17 00:00:00 2001
From: Dhruv Bhavsar <40565844+dbhavsar76@users.noreply.github.com>
Date: Tue, 24 Feb 2026 04:52:11 +0530
Subject: [PATCH 03/17] Resolve conflict with main, add use root preference to
 new settings screen (#172)

Signed-off-by: Jonas <244199422+researchxxl@users.noreply.github.com>
Co-authored-by: Dhruv Bhavsar <dhruv.bhavsar@optimoz.com>
Co-authored-by: Jonas <244199422+researchxxl@users.noreply.github.com>
---
 .../activities/LogActivity.java               |  2 +-
 .../settings/SettingsBehaviorScreen.kt        | 41 +++++++++++++++++++
 .../nutomic/syncthingandroid/util/Util.java   | 10 +++--
 gradle/libs.versions.toml                     |  2 +-
 4 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java b/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java
index 2105be876..f97ca6953 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/activities/LogActivity.java
@@ -191,7 +191,7 @@ protected void onPostExecute(Void aVoid) {
          * @param syncthingLog Filter on Syncthing's native messages.
          */
         private String getAndroidLog() {
-            String output = Util.runShellCommandGetOutput("/system/bin/logcat -t " + Integer.toString(ANDROID_LOG_FILE_MAX_LINES) + " -v time *:i ps:s art:s", false);
+            String output = Util.runShellCommandGetOutput("/system/bin/logcat -t " + Integer.toString(ANDROID_LOG_FILE_MAX_LINES) + " -v time *:i ps:s art:s");
 
             // Filter Android log.
             output = output.replaceAll("I/SyncthingNativeCode", "");
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
index 68d5e0bf4..1c74d818a 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
+++ b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
@@ -1,11 +1,18 @@
 package com.nutomic.syncthingandroid.settings
 
+import android.widget.Toast
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.navigation3.runtime.EntryProviderScope
 import com.nutomic.syncthingandroid.R
 import com.nutomic.syncthingandroid.service.Constants
+import com.nutomic.syncthingandroid.util.Util
+import eu.chainfire.libsuperuser.Shell
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import me.zhanghai.compose.preference.SwitchPreference
 import me.zhanghai.compose.preference.rememberPreferenceState
 
@@ -19,10 +26,34 @@ fun EntryProviderScope<SettingsRoute>.settingsBehaviorEntry() {
 
 @Composable
 fun SettingsBehaviorScreen() {
+    val context = LocalContext.current
+    val scope = LocalActivityScope.current
 
     val autoStart = rememberPreferenceState(Constants.PREF_START_SERVICE_ON_BOOT, false)
     val broadcast = rememberPreferenceState(Constants.PREF_BROADCAST_SERVICE_CONTROL, false)
     val overwrite = rememberPreferenceState(Constants.PREF_ALLOW_OVERWRITE_FILES, false)
+    val useRoot = rememberPreferenceState(Constants.PREF_USE_ROOT, false)
+
+    val toggleRoot = { enabled: Boolean ->
+        scope.launch(Dispatchers.IO) {
+            if (enabled) {
+                if (Shell.SU.available()) {
+                    useRoot.value = true
+                } else {
+                    withContext(Dispatchers.Main) {
+                        Toast.makeText(
+                            context,
+                            R.string.toast_root_denied,
+                            Toast.LENGTH_LONG
+                        ).show()
+                    }
+                }
+            } else {
+                Util.fixAppDataPermissions(context)
+                useRoot.value = false
+            }
+        }
+    }
 
     SettingsScaffold(
         title = stringResource(R.string.category_behaviour),
@@ -48,5 +79,15 @@ fun SettingsBehaviorScreen() {
                 state = overwrite,
             )
         }
+        item {
+            SwitchPreference(
+                title = { Text(stringResource(R.string.use_root_title)) },
+                summary = { Text(stringResource(R.string.use_root_summary)) },
+                value = useRoot.value,
+                onValueChange = {
+                    toggleRoot(it)
+                },
+            )
+        }
     }
 }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index caf1ba364..b5a3eea15 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -216,6 +216,10 @@ public static int runShellCommand(String cmd, Boolean useRoot) {
         return exitCode;
     }
 
+    public static String runShellCommandGetOutput(String cmd) {
+        return runShellCommandGetOutput(cmd, false);
+    }
+
     public static String runShellCommandGetOutput(String cmd, Boolean useRoot) {
         // Note: redirectErrorStream(true); System.getProperty("line.separator");
         int exitCode = 255;
@@ -274,7 +278,7 @@ public static String runShellCommandGetOutput(String cmd, Boolean useRoot) {
      */
     public static Boolean isTcpPortListening(Integer port) {
         // t: tcp, l: listening, n: numeric
-        String output = runShellCommandGetOutput("netstat -t -l -n", false);
+        String output = runShellCommandGetOutput("netstat -t -l -n");
         if (TextUtils.isEmpty(output)) {
             Log.w(TAG, "isTcpPortListening: Failed to run netstat. Returning false.");
             return false;
@@ -495,7 +499,7 @@ public boolean accept(File dir, String name) {
             // Execute script.
             String command = cmdBuilder.toString();
             // Log.d(TAG, "runScriptSet: Exec [" + command + "]");
-            Log.v(TAG, "runScriptSet: Exec result [" + runShellCommandGetOutput(command, false) + "]");
+            Log.v(TAG, "runScriptSet: Exec result [" + runShellCommandGetOutput(command) + "]");
         }
     }
     
@@ -510,7 +514,7 @@ public static String[] getSyncConflictFiles(final String absPath) {
         cmdBuilder.append("find -type f -name \"*\\.sync-conflict-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]-[a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9]*\" -not -path \"\\.\\/\\" + Constants.FOLDER_NAME_STVERSIONS + "\\/*\" -print | sed \"s~\\\\.\\/~~\"");
         String command = cmdBuilder.toString();
         // Log.v(TAG, "getSyncConflictFileCount: Exec [" + command + "]");
-        String output = runShellCommandGetOutput(command, false);
+        String output = runShellCommandGetOutput(command);
         // Log.v(TAG, "getSyncConflictFileCount: Exec result [" + output + "]");
         if (output == null || output.isEmpty()) {
             return new String[]{};
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 66665c270..95b9c97d7 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -87,4 +87,4 @@ aboutLibraries = { id = "com.mikepenz.aboutlibraries.plugin.android", version.re
 android-application = { id = "com.android.application", version.ref = "android-gradle-plugin" }
 compose-compiler = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
 ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }
-jetbrains-kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlinSerialization"}
+jetbrains-kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlinSerialization" }

From 59d7dd4e8aeb3ee8c90f5657620e16d07ed40ead Mon Sep 17 00:00:00 2001
From: Dhruv Bhavsar <40565844+dbhavsar76@users.noreply.github.com>
Date: Thu, 26 Feb 2026 18:59:27 +0530
Subject: [PATCH 04/17] restart syncthing after enabling/disabling root (#173)

Co-authored-by: Dhruv Bhavsar <dhruv.bhavsar@optimoz.com>
---
 .../settings/SettingsBehaviorScreen.kt        | 20 +++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
index 1c74d818a..7e6d0b842 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
+++ b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
@@ -1,5 +1,6 @@
 package com.nutomic.syncthingandroid.settings
 
+import android.content.Intent
 import android.widget.Toast
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -8,6 +9,7 @@ import androidx.compose.ui.res.stringResource
 import androidx.navigation3.runtime.EntryProviderScope
 import com.nutomic.syncthingandroid.R
 import com.nutomic.syncthingandroid.service.Constants
+import com.nutomic.syncthingandroid.service.SyncthingService
 import com.nutomic.syncthingandroid.util.Util
 import eu.chainfire.libsuperuser.Shell
 import kotlinx.coroutines.Dispatchers
@@ -34,11 +36,22 @@ fun SettingsBehaviorScreen() {
     val overwrite = rememberPreferenceState(Constants.PREF_ALLOW_OVERWRITE_FILES, false)
     val useRoot = rememberPreferenceState(Constants.PREF_USE_ROOT, false)
 
+    val restartSt = {
+        val intent = Intent(context, SyncthingService::class.java).apply {
+            action = SyncthingService.ACTION_RESTART
+        }
+        context.startService(intent)
+    }
+
     val toggleRoot = { enabled: Boolean ->
         scope.launch(Dispatchers.IO) {
             if (enabled) {
                 if (Shell.SU.available()) {
-                    useRoot.value = true
+                    withContext(Dispatchers.Main) {
+                        useRoot.value = true
+                    }
+                    // restart after enabling root
+                    restartSt()
                 } else {
                     withContext(Dispatchers.Main) {
                         Toast.makeText(
@@ -50,7 +63,10 @@ fun SettingsBehaviorScreen() {
                 }
             } else {
                 Util.fixAppDataPermissions(context)
-                useRoot.value = false
+                withContext(Dispatchers.Main) {
+                    useRoot.value = false
+                }
+                restartSt()
             }
         }
     }

From 60c557f36c97494645d497ae5acc3c1439efdd9e Mon Sep 17 00:00:00 2001
From: Dhruv Bhavsar <40565844+dbhavsar76@users.noreply.github.com>
Date: Tue, 5 May 2026 18:14:23 +0530
Subject: [PATCH 05/17] abstract all the libsuperuser calls to new RootAccess
 adapter

---
 .../syncthingandroid/receiver/BootReceiver.java     |  5 ++---
 .../nutomic/syncthingandroid/root/RootAccess.java   | 13 +++++++++++++
 .../syncthingandroid/service/SyncthingRunnable.java |  5 ++---
 .../settings/SettingsBehaviorScreen.kt              |  4 ++--
 .../com/nutomic/syncthingandroid/util/Util.java     |  7 +++----
 5 files changed, 22 insertions(+), 12 deletions(-)
 create mode 100644 app/src/main/java/com/nutomic/syncthingandroid/root/RootAccess.java

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
index 4cbba25e3..8bbe82aaa 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
@@ -11,8 +11,7 @@
 import com.nutomic.syncthingandroid.service.Constants;
 import com.nutomic.syncthingandroid.service.SyncthingRunnable;
 import com.nutomic.syncthingandroid.service.SyncthingService;
-
-import eu.chainfire.libsuperuser.Shell;
+import com.nutomic.syncthingandroid.root.RootAccess;
 
 import java.lang.SecurityException;
 
@@ -33,7 +32,7 @@ public void onReceive(Context context, Intent intent) {
         }
 
         if (packageReplaced) {
-            if (getPrefUseRoot(context) && Shell.SU.available()) {
+            if (getPrefUseRoot(context) && RootAccess.isRootAvailableBlocking()) {
                 /**
                  * In Root mode, there will be a SyncthingNative process left running after app update.
                  */
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/root/RootAccess.java b/app/src/main/java/com/nutomic/syncthingandroid/root/RootAccess.java
new file mode 100644
index 000000000..653d7c166
--- /dev/null
+++ b/app/src/main/java/com/nutomic/syncthingandroid/root/RootAccess.java
@@ -0,0 +1,13 @@
+package com.nutomic.syncthingandroid.root;
+
+import eu.chainfire.libsuperuser.Shell;
+
+public final class RootAccess {
+
+    private RootAccess() {
+    }
+
+    public static boolean isRootAvailableBlocking() {
+        return Shell.SU.available();
+    }
+}
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
index 9e3981b23..5c5dc8eba 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
@@ -22,6 +22,7 @@
 import com.google.common.io.Files;
 import com.nutomic.syncthingandroid.R;
 import com.nutomic.syncthingandroid.SyncthingApp;
+import com.nutomic.syncthingandroid.root.RootAccess;
 import com.nutomic.syncthingandroid.util.FileUtils;
 import com.nutomic.syncthingandroid.util.Util;
 
@@ -47,8 +48,6 @@
 
 import javax.inject.Inject;
 
-import eu.chainfire.libsuperuser.Shell;
-
 import static com.nutomic.syncthingandroid.service.SyncthingService.EXTRA_STOP_AFTER_CRASHED_NATIVE;
 
 /**
@@ -100,7 +99,7 @@ public SyncthingRunnable(Context context, Command command) {
         mSyncthingLogFile = Constants.getSyncthingLogFile(mContext);
 
         // Get preferences relevant to starting syncthing core.
-        mUseRoot = mPreferences.getBoolean(Constants.PREF_USE_ROOT, false) && Shell.SU.available();
+        mUseRoot = mPreferences.getBoolean(Constants.PREF_USE_ROOT, false) && RootAccess.isRootAvailableBlocking();
         switch (command) {
             case deviceid:
                 mCommand = new String[]{mSyncthingBinary.getPath(), "device-id"};
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
index 7e6d0b842..160150ca0 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
+++ b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
@@ -8,10 +8,10 @@ import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.navigation3.runtime.EntryProviderScope
 import com.nutomic.syncthingandroid.R
+import com.nutomic.syncthingandroid.root.RootAccess
 import com.nutomic.syncthingandroid.service.Constants
 import com.nutomic.syncthingandroid.service.SyncthingService
 import com.nutomic.syncthingandroid.util.Util
-import eu.chainfire.libsuperuser.Shell
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -46,7 +46,7 @@ fun SettingsBehaviorScreen() {
     val toggleRoot = { enabled: Boolean ->
         scope.launch(Dispatchers.IO) {
             if (enabled) {
-                if (Shell.SU.available()) {
+                if (RootAccess.isRootAvailableBlocking()) {
                     withContext(Dispatchers.Main) {
                         useRoot.value = true
                     }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index b5a3eea15..0f0aaa730 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -14,6 +14,7 @@
 import androidx.preference.PreferenceManager;
 
 import com.google.common.base.Charsets;
+import com.nutomic.syncthingandroid.root.RootAccess;
 import com.nutomic.syncthingandroid.R;
 import com.nutomic.syncthingandroid.service.Constants;
 
@@ -34,8 +35,6 @@
 import java.time.ZoneOffset;
 import java.util.Locale;
 
-import eu.chainfire.libsuperuser.Shell;
-
 public class Util {
 
     private static final String TAG = "Util";
@@ -87,7 +86,7 @@ public static boolean fixAppDataPermissions(Context context) {
         // Be paranoid :) and check if root is available.
         // Ignore the 'use_root' preference, because we might want to fix the permission
         // just after the root option has been disabled.
-        if (!Shell.SU.available()) {
+        if (!RootAccess.isRootAvailableBlocking()) {
             Log.e(TAG, "Root is not available. Cannot fix permissions.");
             return false;
         }
@@ -134,7 +133,7 @@ public static boolean nativeBinaryCanWriteToPath(Context context, String absolut
         Boolean useRoot = false;
         Boolean prefUseRoot = PreferenceManager.getDefaultSharedPreferences(context)
             .getBoolean(Constants.PREF_USE_ROOT, false);
-        if (prefUseRoot && Shell.SU.available()) {
+        if (prefUseRoot && RootAccess.isRootAvailableBlocking()) {
             useRoot = true;
         }
 

From 108ff5c28a98ad01a99335eb5104ea6a74b4fc5c Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Mon, 18 May 2026 17:15:04 +0200
Subject: [PATCH 06/17] java.io.DataOutputStream

---
 .../com/nutomic/syncthingandroid/service/SyncthingRunnable.java  | 1 +
 1 file changed, 1 insertion(+)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
index ad76863ed..6ebef53d2 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
@@ -23,6 +23,7 @@
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.io.BufferedReader;
+import java.io.DataOutputStream;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;

From c7b2a9a56068fd71e13d2c3a64b3ee29b50f1c00 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Fri, 12 Jun 2026 15:52:33 +0200
Subject: [PATCH 07/17] Update SettingsBehaviorScreen.kt

---
 .../nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt  | 1 +
 1 file changed, 1 insertion(+)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
index 160150ca0..d54dbcaf0 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
+++ b/app/src/main/java/com/nutomic/syncthingandroid/settings/SettingsBehaviorScreen.kt
@@ -11,6 +11,7 @@ import com.nutomic.syncthingandroid.R
 import com.nutomic.syncthingandroid.root.RootAccess
 import com.nutomic.syncthingandroid.service.Constants
 import com.nutomic.syncthingandroid.service.SyncthingService
+import com.nutomic.syncthingandroid.util.LocalActivityScope
 import com.nutomic.syncthingandroid.util.Util
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch

From be5253e0cce65f55bd1e7b91b16e5d126fa381b2 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 11:33:15 +0200
Subject: [PATCH 08/17] fix bootreceiver

---
 .../com/nutomic/syncthingandroid/receiver/BootReceiver.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
index 8bbe82aaa..77620670c 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
@@ -12,6 +12,7 @@
 import com.nutomic.syncthingandroid.service.SyncthingRunnable;
 import com.nutomic.syncthingandroid.service.SyncthingService;
 import com.nutomic.syncthingandroid.root.RootAccess;
+import com.nutomic.syncthingandroid.util.Util;
 
 import java.lang.SecurityException;
 
@@ -37,7 +38,7 @@ public void onReceive(Context context, Intent intent) {
                  * In Root mode, there will be a SyncthingNative process left running after app update.
                  */
                 Log.d(TAG, "ACTION_MY_PACKAGE_REPLACED: Killing leftover SyncthingNative instance if present ...");
-                new SyncthingRunnable(context, SyncthingRunnable.Command.main).killSyncthing();
+                Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, true);
             }
         }
 

From db3f0b9f31043b1747172e23c9064bccebcce077 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 11:33:42 +0200
Subject: [PATCH 09/17] util: add useroot to new funcs

---
 .../java/com/nutomic/syncthingandroid/util/Util.java | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index 878c6df20..14a8460b6 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -177,9 +177,9 @@ public static boolean nativeBinaryCanWriteToPath(Context context, String absolut
      * Look for running processes and return an array
      * containing the PIDs of found instances.
      */
-    public static List<String> getProcessPIDs(final String processName) {
+    public static List<String> getProcessPIDs(final String processName, final Boolean useRoot) {
         List<String> processPIDs = new ArrayList<String>();
-        String output = runShellCommandGetOutput("ps\n");
+        String output = runShellCommandGetOutput("ps\n", useRoot);
         if (TextUtils.isEmpty(output)) {
             Log.w(TAG, "getProcessPIDs: Failed to list processes. ps command returned empty.");
             return processPIDs;
@@ -205,15 +205,15 @@ public static List<String> getProcessPIDs(final String processName) {
     /**
      * Look for running processes and end them gracefully.
      */
-    public static void killProcess(final String processName) {
+    public static void killProcess(final String processName, final Boolean useRoot) {
         int exitCode;
-        List<String> processPIDs = getProcessPIDs(processName);
+        List<String> processPIDs = getProcessPIDs(processName, useRoot);
         if (processPIDs.isEmpty()) {
             Log.v(TAG, "killProcess: Found no running instances of [" + processName + "]");
             return;
         }
         for (String processPID : processPIDs) {
-            exitCode = runShellCommand("kill -SIGINT " + processPID + "\n");
+            exitCode = runShellCommand("kill -SIGINT " + processPID + "\n", useRoot);
             if (exitCode != 0) {
                 Log.w(TAG, "killProcess: Failed to send kill SIGINT to process [" + processPID +
                         "] exit code " + Integer.toString(exitCode));
@@ -223,7 +223,7 @@ public static void killProcess(final String processName) {
         /**
          * Wait for process to end.
          */
-        while (!getProcessPIDs(processName).isEmpty()) {
+        while (!getProcessPIDs(processName, useRoot).isEmpty()) {
             SystemClock.sleep(50);
         }
         Log.d(TAG, "killProcess: No more instances of [" + processName + "] running");

From 08a7d374d10598aea405b77d5fdafef275c54494 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 11:33:50 +0200
Subject: [PATCH 10/17] fix restapi

---
 .../main/java/com/nutomic/syncthingandroid/service/RestApi.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java b/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
index ec028eb56..a567b64e5 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
@@ -613,7 +613,7 @@ public void sendConfig() {
     public void shutdown() {
         hasShutdown = true;
         executorService.shutdownNow();
-        Util.killProcess("find");
+        Util.killProcess("find", false);
         new PostRequest(mContext, mUrl, PostRequest.URI_SYSTEM_SHUTDOWN, mApiKey,
                 null, null, null);
     }

From 40788a7311a09534db2dff0e99a810296f46f8e3 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 11:42:12 +0200
Subject: [PATCH 11/17] add preference.java

---
 .../receiver/BootReceiver.java                | 18 +++--------------
 .../syncthingandroid/util/Preference.java     | 20 +++++++++++++++++++
 2 files changed, 23 insertions(+), 15 deletions(-)
 create mode 100644 app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
index 77620670c..3247544e9 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
@@ -3,15 +3,13 @@
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
-import android.content.SharedPreferences;
 import android.os.Build;
-import androidx.preference.PreferenceManager;
 import android.util.Log;
 
 import com.nutomic.syncthingandroid.service.Constants;
-import com.nutomic.syncthingandroid.service.SyncthingRunnable;
 import com.nutomic.syncthingandroid.service.SyncthingService;
 import com.nutomic.syncthingandroid.root.RootAccess;
+import com.nutomic.syncthingandroid.util.Preference;
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.lang.SecurityException;
@@ -33,7 +31,7 @@ public void onReceive(Context context, Intent intent) {
         }
 
         if (packageReplaced) {
-            if (getPrefUseRoot(context) && RootAccess.isRootAvailableBlocking()) {
+            if (Preference.getUseRoot(context) && RootAccess.isRootAvailableBlocking()) {
                 /**
                  * In Root mode, there will be a SyncthingNative process left running after app update.
                  */
@@ -43,7 +41,7 @@ public void onReceive(Context context, Intent intent) {
         }
 
         // Check if we should (re)start now.
-        if (!getPrefStartServiceOnBoot(context)) {
+        if (!Preference.getStartServiceOnBoot(context)) {
             return;
         }
 
@@ -64,14 +62,4 @@ public static void startServiceCompat(Context context) {
             context.startService(intent);
         }
     }
-
-    private static boolean getPrefStartServiceOnBoot(Context context) {
-        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
-        return sp.getBoolean(Constants.PREF_START_SERVICE_ON_BOOT, false);
-    }
-
-    private static boolean getPrefUseRoot(Context context) {
-        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
-        return sp.getBoolean(Constants.PREF_USE_ROOT, false);
-    }
 }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java
new file mode 100644
index 000000000..5580fba9a
--- /dev/null
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java
@@ -0,0 +1,20 @@
+package com.nutomic.syncthingandroid.util;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import androidx.preference.PreferenceManager;
+
+import com.nutomic.syncthingandroid.service.Constants;
+
+public class Preference {
+
+    public static boolean getStartServiceOnBoot(Context context) {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
+        return sp.getBoolean(Constants.PREF_START_SERVICE_ON_BOOT, false);
+    }
+
+    public static boolean getUseRoot(Context context) {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
+        return sp.getBoolean(Constants.PREF_USE_ROOT, false);
+    }
+}

From 8ec299e67fda32102b9d5078e79fc7020f75393b Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 11:47:21 +0200
Subject: [PATCH 12/17] fix syncthingservice

---
 .../nutomic/syncthingandroid/service/SyncthingService.java   | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
index cddfd48db..e06fc82f6 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
@@ -19,6 +19,7 @@
 import com.nutomic.syncthingandroid.util.ConfigXml;
 import com.nutomic.syncthingandroid.util.FileUtils;
 import com.nutomic.syncthingandroid.util.PermissionUtil;
+import com.nutomic.syncthingandroid.util.Preference;
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.io.File;
@@ -584,7 +585,7 @@ private void launchStartupTask(SyncthingRunnable.Command srCommand) {
          * Check if an old syncthing instance is still running.
          * This happens after an in-place app upgrade. If so, end it.
          */
-        Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY);
+        Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, Preference.getUseRoot(this));
 
         // Start the syncthing binary in a separate thread.
         Thread.UncaughtExceptionHandler syncthingRunnableThreadExceptionHandler = new Thread.UncaughtExceptionHandler() {
@@ -712,7 +713,7 @@ private void shutdown(State newState) {
         }
 
         if (mSyncthingRunnable != null) {
-            Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY);
+            Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, Preference.getUseRoot(this));
             if (mSyncthingRunnableThread != null) {
                 LogV("Waiting for mSyncthingRunnableThread to finish after killProcess(Syncthing) ...");
                 try {

From 18295cbe361fbf8037713b28a8edd943d923e718 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 11:52:25 +0200
Subject: [PATCH 13/17] fix conflict detector not working in root mode

---
 .../java/com/nutomic/syncthingandroid/service/RestApi.java   | 5 +++--
 .../main/java/com/nutomic/syncthingandroid/util/Util.java    | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java b/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
index a567b64e5..fd92c4f1c 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
@@ -52,6 +52,7 @@
 import com.nutomic.syncthingandroid.model.SystemVersion;
 import com.nutomic.syncthingandroid.service.Constants;
 import com.nutomic.syncthingandroid.util.FileUtils;
+import com.nutomic.syncthingandroid.util.Preference;
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.io.File;
@@ -613,7 +614,7 @@ public void sendConfig() {
     public void shutdown() {
         hasShutdown = true;
         executorService.shutdownNow();
-        Util.killProcess("find", false);
+        Util.killProcess("find", Preference.getUseRoot(mContext));
         new PostRequest(mContext, mUrl, PostRequest.URI_SYSTEM_SHUTDOWN, mApiKey,
                 null, null, null);
     }
@@ -1252,7 +1253,7 @@ public void setRemoteCompletionInfo(final String deviceId,
                 // Check for ".sync-conflict-YYYYMMDD-HHMMSS-DEVICEI*" files.
                 mLocalCompletion.setDiscoveredConflictFiles(
                         folderId,
-                        Util.getSyncConflictFiles(folder.path)
+                        Util.getSyncConflictFiles(folder.path, Preference.getUseRoot(mContext))
                 );
             }
 
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index 14a8460b6..067bf0343 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -569,7 +569,7 @@ public boolean accept(File dir, String name) {
     /**
      * Called by RestApi/setRemoteCompletionInfo after folder completed.
      */
-    public static String[] getSyncConflictFiles(final String absPath) {
+    public static String[] getSyncConflictFiles(final String absPath, final Boolean useRoot) {
         StringBuilder cmdBuilder = new StringBuilder();
         cmdBuilder.append("cd \"").append(absPath).append("/\";");
         // Unescaped:
@@ -577,7 +577,7 @@ public static String[] getSyncConflictFiles(final String absPath) {
         cmdBuilder.append("find -type f -name \"*\\.sync-conflict-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]-[a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9]*\" -not -path \"\\.\\/\\" + Constants.FOLDER_NAME_STVERSIONS + "\\/*\" -print | sed \"s~\\\\.\\/~~\"");
         String command = cmdBuilder.toString();
         // Log.v(TAG, "getSyncConflictFileCount: Exec [" + command + "]");
-        String output = runShellCommandGetOutput(command);
+        String output = runShellCommandGetOutput(command, useRoot);
         // Log.v(TAG, "getSyncConflictFileCount: Exec result [" + output + "]");
         if (output == null || output.isEmpty()) {
             return new String[]{};

From 5259afc7a37700a8def7971733678d7217fbb4bd Mon Sep 17 00:00:00 2001
From: Jonas <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 12:01:08 +0200
Subject: [PATCH 14/17] Apply suggestions from code review

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Jonas <244199422+researchxxl@users.noreply.github.com>
---
 app/src/main/res/values/strings.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 2f488e5a2..cd4cad795 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -531,7 +531,7 @@
     <string name="behaviour_autostart_summary">Start app automatically on operating system startup.</string>
 
     <string name="use_root_title">Run Syncthing as Superuser</string>
-    <string name="use_root_summary">Running Syncthing as root allows it to write to folders Android normally restricts to be readonly accessed. Use this feature with caution.</string>
+    <string name="use_root_summary">Running Syncthing as root allows it to write to folders Android normally restricts to read-only access. Use this feature with caution.</string>
 
     <string name="allow_overwrite_files_title">Allow overwrite of existing files</string>
     <string name="allow_overwrite_files_summary">When another app shares files to one of our folders.</string>

From 523228caeb8d89fc60acfb81b70a2e535ddbfbe3 Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 12:07:40 +0200
Subject: [PATCH 15/17] preference into appprefs

---
 .../receiver/BootReceiver.java                |  6 +++---
 .../syncthingandroid/service/AppPrefs.java    | 14 +++++++++++--
 .../syncthingandroid/service/RestApi.java     |  5 ++---
 .../service/SyncthingService.java             |  5 ++---
 .../syncthingandroid/util/Preference.java     | 20 -------------------
 5 files changed, 19 insertions(+), 31 deletions(-)
 delete mode 100644 app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
index 3247544e9..fd3f17787 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/receiver/BootReceiver.java
@@ -6,10 +6,10 @@
 import android.os.Build;
 import android.util.Log;
 
+import com.nutomic.syncthingandroid.service.AppPrefs;
 import com.nutomic.syncthingandroid.service.Constants;
 import com.nutomic.syncthingandroid.service.SyncthingService;
 import com.nutomic.syncthingandroid.root.RootAccess;
-import com.nutomic.syncthingandroid.util.Preference;
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.lang.SecurityException;
@@ -31,7 +31,7 @@ public void onReceive(Context context, Intent intent) {
         }
 
         if (packageReplaced) {
-            if (Preference.getUseRoot(context) && RootAccess.isRootAvailableBlocking()) {
+            if (AppPrefs.getUseRoot(context) && RootAccess.isRootAvailableBlocking()) {
                 /**
                  * In Root mode, there will be a SyncthingNative process left running after app update.
                  */
@@ -41,7 +41,7 @@ public void onReceive(Context context, Intent intent) {
         }
 
         // Check if we should (re)start now.
-        if (!Preference.getStartServiceOnBoot(context)) {
+        if (!AppPrefs.getStartServiceOnBoot(context)) {
             return;
         }
 
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/AppPrefs.java b/app/src/main/java/com/nutomic/syncthingandroid/service/AppPrefs.java
index 8e0c42b41..f71b26168 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/AppPrefs.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/AppPrefs.java
@@ -1,11 +1,11 @@
-
 package com.nutomic.syncthingandroid.service;
 
 import android.content.Context;
 import android.content.SharedPreferences;
-import androidx.preference.PreferenceManager;
 import android.util.Log;
 
+import androidx.preference.PreferenceManager;
+
 /**
  * Provides preference getters and setters.
  */
@@ -29,4 +29,14 @@ public static final boolean getPrefVerboseLog(SharedPreferences sharedPreference
         }
         return sharedPreferences.getBoolean(Constants.PREF_VERBOSE_LOG, PREF_VERBOSE_LOG_DEFAULT);
     }
+
+    public static final boolean getStartServiceOnBoot(Context context) {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
+        return sp.getBoolean(Constants.PREF_START_SERVICE_ON_BOOT, false);
+    }
+
+    public static final boolean getUseRoot(Context context) {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
+        return sp.getBoolean(Constants.PREF_USE_ROOT, false);
+    }
 }
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java b/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
index fd92c4f1c..42d70b012 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java
@@ -52,7 +52,6 @@
 import com.nutomic.syncthingandroid.model.SystemVersion;
 import com.nutomic.syncthingandroid.service.Constants;
 import com.nutomic.syncthingandroid.util.FileUtils;
-import com.nutomic.syncthingandroid.util.Preference;
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.io.File;
@@ -614,7 +613,7 @@ public void sendConfig() {
     public void shutdown() {
         hasShutdown = true;
         executorService.shutdownNow();
-        Util.killProcess("find", Preference.getUseRoot(mContext));
+        Util.killProcess("find", AppPrefs.getUseRoot(mContext));
         new PostRequest(mContext, mUrl, PostRequest.URI_SYSTEM_SHUTDOWN, mApiKey,
                 null, null, null);
     }
@@ -1253,7 +1252,7 @@ public void setRemoteCompletionInfo(final String deviceId,
                 // Check for ".sync-conflict-YYYYMMDD-HHMMSS-DEVICEI*" files.
                 mLocalCompletion.setDiscoveredConflictFiles(
                         folderId,
-                        Util.getSyncConflictFiles(folder.path, Preference.getUseRoot(mContext))
+                        Util.getSyncConflictFiles(folder.path, AppPrefs.getUseRoot(mContext))
                 );
             }
 
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
index e06fc82f6..8b5398fd8 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingService.java
@@ -19,7 +19,6 @@
 import com.nutomic.syncthingandroid.util.ConfigXml;
 import com.nutomic.syncthingandroid.util.FileUtils;
 import com.nutomic.syncthingandroid.util.PermissionUtil;
-import com.nutomic.syncthingandroid.util.Preference;
 import com.nutomic.syncthingandroid.util.Util;
 
 import java.io.File;
@@ -585,7 +584,7 @@ private void launchStartupTask(SyncthingRunnable.Command srCommand) {
          * Check if an old syncthing instance is still running.
          * This happens after an in-place app upgrade. If so, end it.
          */
-        Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, Preference.getUseRoot(this));
+        Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, AppPrefs.getUseRoot(this));
 
         // Start the syncthing binary in a separate thread.
         Thread.UncaughtExceptionHandler syncthingRunnableThreadExceptionHandler = new Thread.UncaughtExceptionHandler() {
@@ -713,7 +712,7 @@ private void shutdown(State newState) {
         }
 
         if (mSyncthingRunnable != null) {
-            Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, Preference.getUseRoot(this));
+            Util.killProcess(Constants.FILENAME_SYNCTHING_BINARY, AppPrefs.getUseRoot(this));
             if (mSyncthingRunnableThread != null) {
                 LogV("Waiting for mSyncthingRunnableThread to finish after killProcess(Syncthing) ...");
                 try {
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java
deleted file mode 100644
index 5580fba9a..000000000
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Preference.java
+++ /dev/null
@@ -1,20 +0,0 @@
-package com.nutomic.syncthingandroid.util;
-
-import android.content.Context;
-import android.content.SharedPreferences;
-import androidx.preference.PreferenceManager;
-
-import com.nutomic.syncthingandroid.service.Constants;
-
-public class Preference {
-
-    public static boolean getStartServiceOnBoot(Context context) {
-        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
-        return sp.getBoolean(Constants.PREF_START_SERVICE_ON_BOOT, false);
-    }
-
-    public static boolean getUseRoot(Context context) {
-        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
-        return sp.getBoolean(Constants.PREF_USE_ROOT, false);
-    }
-}

From fe3a6f6f1754f2f81987751fecfb4c5b86d64bdc Mon Sep 17 00:00:00 2001
From: researchxxl <244199422+researchxxl@users.noreply.github.com>
Date: Tue, 4 Aug 2026 12:26:20 +0200
Subject: [PATCH 16/17] simplify util

---
 .../main/java/com/nutomic/syncthingandroid/util/Util.java   | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index 067bf0343..befc939b1 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -12,11 +12,11 @@
 import android.util.Log;
 
 import androidx.appcompat.app.AppCompatActivity;
-import androidx.preference.PreferenceManager;
 
 import com.google.common.base.Charsets;
 import com.nutomic.syncthingandroid.root.RootAccess;
 import com.nutomic.syncthingandroid.R;
+import com.nutomic.syncthingandroid.service.AppPrefs;
 import com.nutomic.syncthingandroid.service.Constants;
 
 import java.io.BufferedReader;
@@ -139,9 +139,7 @@ public static boolean fixAppDataPermissions(Context context) {
     public static boolean nativeBinaryCanWriteToPath(Context context, String absoluteFolderPath) {
         final String TOUCH_FILE_NAME = ".stwritetest";
         Boolean useRoot = false;
-        Boolean prefUseRoot = PreferenceManager.getDefaultSharedPreferences(context)
-            .getBoolean(Constants.PREF_USE_ROOT, false);
-        if (prefUseRoot && RootAccess.isRootAvailableBlocking()) {
+        if (AppPrefs.getUseRoot(context) && RootAccess.isRootAvailableBlocking()) {
             useRoot = true;
         }
 

From d5f9170419c5acaee1b6f604fd1f1cccedea9f23 Mon Sep 17 00:00:00 2001
From: Dhruv Bhavsar <40565844+dbhavsar76@users.noreply.github.com>
Date: Tue, 25 Aug 2026 15:58:55 +0530
Subject: [PATCH 17/17] fix(root): escape values written into the root shell
 (#357)

---
 .../service/SyncthingRunnable.java            | 17 +++++-
 .../nutomic/syncthingandroid/util/Util.java   | 57 +++++++++++++++++--
 2 files changed, 68 insertions(+), 6 deletions(-)

diff --git a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
index 4a1de8c62..1e53cd131 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/service/SyncthingRunnable.java
@@ -448,15 +448,28 @@ private Process setupAndLaunch(HashMap<String, String> env) throws IOException,
             // Even with --preserve-environment the environment gets messed up.
             // We therefore start a root shell, and set all the environment variables manually.
             DataOutputStream suOut = new DataOutputStream(process.getOutputStream());
+            // Every value written into this shell must be quoted. The environment may contain
+            // user supplied entries (Constants.PREF_ENVIRONMENT_VARIABLES), and an unquoted value
+            // would be expanded by the shell - meaning e.g. "$(...)" executes as root.
             for (Map.Entry<String, String> entry : env.entrySet()) {
-                suOut.writeBytes(String.format("export %s=\"%s\"\n", entry.getKey(), entry.getValue()));
+                if (!Util.isValidEnvVarName(entry.getKey())) {
+                    // A name cannot be quoted, so reject it rather than let it inject commands.
+                    Log.w(TAG, "Skipping environment variable with invalid name [" + entry.getKey() + "]");
+                    continue;
+                }
+                suOut.writeBytes(String.format("export %s=%s\n",
+                        entry.getKey(), Util.shellQuote(entry.getValue())));
             }
             suOut.flush();
             // Exec will replace the su process image by Syncthing as execlp in C does.
             // Without using exec, the process will drop to the root shell as soon as Syncthing terminates like a normal shell does.
             // If we did not use exec, we would wait infinitely for the process to terminate (ret = process.waitFor(); in run()).
             // With exec the whole process terminates when Syncthing exits.
-            suOut.writeBytes("exec " + TextUtils.join(" ", mCommand) + "\n");
+            StringBuilder execLine = new StringBuilder("exec");
+            for (String arg : mCommand) {
+                execLine.append(' ').append(Util.shellQuote(arg));
+            }
+            suOut.writeBytes(execLine.append('\n').toString());
             suOut.flush();
             return process;
         } else {
diff --git a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
index befc939b1..e47dfca0e 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/util/Util.java
@@ -115,12 +115,13 @@ public static boolean fixAppDataPermissions(Context context) {
 
         // Get private app's "files" dir residing in "/data/data/[packageName]".
         String dir = context.getFilesDir().getAbsolutePath();
-        String cmd = "chown -R " + appInfo.uid + ":" + appInfo.uid + " " + dir + "; ";
+        String quotedDir = shellQuote(dir);
+        String cmd = "chown -R " + appInfo.uid + ":" + appInfo.uid + " " + quotedDir + "; ";
         // Running Syncthing as root might change a file's or directories type in terms of SELinux.
         // Leaving them as they are, the Android service won't be able to access them.
         // At least for those files residing in an application's data folder.
         // Simply reverting the type to its default should do the trick.
-        cmd += "restorecon -R " + dir + "\n";
+        cmd += "restorecon -R " + quotedDir + "\n";
         Log.d(TAG, "Running: '" + cmd);
         int exitCode = runShellCommand(cmd, true);
         if (exitCode == 0) {
@@ -144,8 +145,11 @@ public static boolean nativeBinaryCanWriteToPath(Context context, String absolut
         }
 
         // Write permission test file.
+        // The folder path is chosen by the user, so it must be quoted - it may contain characters
+        // the shell would otherwise expand, and this command runs as root when root mode is on.
         String touchFile = absoluteFolderPath + "/" + TOUCH_FILE_NAME;
-        int exitCode = runShellCommand("echo \"\" > \"" + touchFile + "\"\n", useRoot);
+        String quotedTouchFile = shellQuote(touchFile);
+        int exitCode = runShellCommand("echo \"\" > " + quotedTouchFile + "\n", useRoot);
         if (exitCode != 0) {
             String error;
             switch (exitCode) {
@@ -164,13 +168,58 @@ public static boolean nativeBinaryCanWriteToPath(Context context, String absolut
         Log.i(TAG, "Successfully wrote test file '" + touchFile + "'");
 
         // Remove test file.
-        if (runShellCommand("rm \"" + touchFile + "\"\n", useRoot) != 0) {
+        if (runShellCommand("rm " + quotedTouchFile + "\n", useRoot) != 0) {
             // This is very unlikely to happen, so we have less error handling.
             Log.i(TAG, "Failed to remove test file");
         }
         return true;
     }
 
+    /**
+     * Quotes a string for safe use as a single argument in a POSIX shell command line.
+     *
+     * Everything is wrapped in single quotes, within which the shell performs no expansion at all,
+     * so '$', '`', '"', '\' and whitespace are passed through literally. An embedded single quote
+     * cannot be escaped inside single quotes, so it is emitted as '\'' - closing the quoted run,
+     * appending an escaped quote, then reopening it.
+     *
+     * Always use this for any value that ends up in a command line, especially when the command
+     * runs as root. Values reachable from the UI (folder paths, custom environment variables) are
+     * otherwise evaluated by the shell.
+     */
+    public static String shellQuote(String s) {
+        if (s == null) {
+            return "''";
+        }
+        return "'" + s.replace("'", "'\\''") + "'";
+    }
+
+    /**
+     * Returns whether the given name is a valid POSIX shell variable name, i.e. matches
+     * [A-Za-z_][A-Za-z0-9_]*
+     *
+     * The name side of an "export NAME=value" statement cannot be quoted - it has to be a bare
+     * identifier - so unlike the value it cannot be made safe by escaping. It must be rejected
+     * instead, otherwise a crafted name injects additional shell commands.
+     */
+    public static boolean isValidEnvVarName(String name) {
+        if (TextUtils.isEmpty(name)) {
+            return false;
+        }
+        for (int i = 0; i < name.length(); i++) {
+            char c = name.charAt(i);
+            boolean isAlpha = (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_';
+            if (isAlpha) {
+                continue;
+            }
+            if (i > 0 && c >= '0' && c <= '9') {
+                continue;
+            }
+            return false;
+        }
+        return true;
+    }
+
     /**
      * Look for running processes and return an array
      * containing the PIDs of found instances.