SettingsActivity: allow for installing command line tools

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/SettingsActivity.java

@@ -2,9 +2,14 @@ package com.wireguard.android;
 
 import android.app.Activity;
 import android.app.FragmentTransaction;
+import android.content.Context;
+import android.os.AsyncTask;
 import android.os.Bundle;
+import android.preference.Preference;
 import android.preference.PreferenceFragment;
 
+import com.wireguard.android.backends.RootShell;
+
 public class SettingsActivity extends Activity {
     @Override
     protected void onCreate(final Bundle savedInstanceState) {
@@ -22,6 +27,77 @@ public class SettingsActivity extends Activity {
             addPreferencesFromResource(R.xml.preferences);
             if (getArguments() != null && getArguments().getBoolean("showQuickTile"))
                 ((ConfigListPreference) findPreference("primary_config")).show();
+
+            final Preference installTools = findPreference("install_cmd_line_tools");
+            installTools.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
+                public boolean onPreferenceClick(Preference preference) {
+                    new ToolsInstaller(installTools).execute();
+                    return true;
+                }
+            });
+        }
+    }
+
+    private static class ToolsInstaller extends AsyncTask<Void, Void, Integer> {
+        Preference installTools;
+
+        public ToolsInstaller(Preference installTools) {
+            this.installTools = installTools;
+            installTools.setEnabled(false);
+            installTools.setSummary(installTools.getContext().getString(R.string.install_cmd_line_tools_progress));
+        }
+
+        private static final String[][] libraryNamedExecutables = {
+                { "libwg.so", "wg" },
+                { "libwg-quick.so", "wg-quick" }
+        };
+
+        @Override
+        protected Integer doInBackground(final Void... voids) {
+            final Context context = installTools.getContext();
+            final String libDir = context.getApplicationInfo().nativeLibraryDir;
+            final StringBuilder cmd = new StringBuilder();
+
+            cmd.append("set -ex;");
+
+            for (final String[] libraryNamedExecutable : libraryNamedExecutables) {
+                final String arg1 = "'" + libDir + "/" + libraryNamedExecutable[0] + "'";
+                final String arg2 = "'/system/xbin/" + libraryNamedExecutable[1] + "'";
+
+                cmd.append(String.format("diff %s %s && ", arg1, arg2));
+            }
+            cmd.append("exit 114;");
+
+            cmd.append("trap 'mount -o remount,ro /system' EXIT;");
+            cmd.append("mount -o remount,rw /system;");
+
+            for (final String[] libraryNamedExecutable : libraryNamedExecutables) {
+                final String arg1 = "'" + libDir + "/" + libraryNamedExecutable[0] + "'";
+                final String arg2 = "'/system/xbin/" + libraryNamedExecutable[1] + "'";
+                cmd.append(String.format("cp %s %s; chmod 755 %s;", arg1, arg2, arg2));
+            }
+
+            return new RootShell(context).run(null, cmd.toString());
+        }
+
+        @Override
+        protected void onPostExecute(final Integer ret) {
+            final Context context = installTools.getContext();
+            String status;
+
+            switch (ret) {
+                case 0:
+                    status = context.getString(R.string.install_cmd_line_tools_success);
+                    break;
+                case 114 /* OsConstants.EALREADY */:
+                    status = context.getString(R.string.install_cmd_line_tools_already);
+                    break;
+                default:
+                    status = context.getString(R.string.install_cmd_line_tools_failure);
+                    break;
+            }
+            installTools.setSummary(status);
+            installTools.setEnabled(true);
         }
     }
 }

app/src/main/java/com/wireguard/android/backends/RootShell.java

@@ -18,7 +18,7 @@ import java.util.regex.Matcher;
  * Helper class for running commands as root.
  */
 
-class RootShell {
+public class RootShell {
     /**
      * Setup commands that are run at the beginning of each root shell. The trap command ensures
      * access to the return value of the last command, since su itself always exits with 0.
@@ -33,23 +33,23 @@ class RootShell {
 
     private final String preamble;
 
-    RootShell(final Context context) {
+    public RootShell(final Context context) {
         final String binDir = context.getCacheDir().getPath() + "/bin";
         final String tmpDir = context.getCacheDir().getPath() + "/tmp";
+        final String libDir = context.getApplicationInfo().nativeLibraryDir;
 
         new File(binDir).mkdirs();
         new File(tmpDir).mkdirs();
 
-        preamble = String.format("export PATH=\"%s:$PATH\" TMPDIR=\"%s\";", binDir, tmpDir);
+        StringBuilder builder = new StringBuilder();
-
-        final String libDir = context.getApplicationInfo().nativeLibraryDir;
-        String symlinkCommand = "set -ex;";
         for (final String[] libraryNamedExecutable : libraryNamedExecutables) {
-            final String args = "'" + libDir + "/" + libraryNamedExecutable[0] + "' '" + binDir + "/" + libraryNamedExecutable[1] + "'";
+            final String arg1 = "'" + libDir + "/" + libraryNamedExecutable[0] + "'";
-            symlinkCommand += "ln -f " + args + " || ln -sf " + args + ";";
+            final String arg2 = "'" + binDir + "/" + libraryNamedExecutable[1] + "'";
+            builder.append(String.format("[ %s -ef %s ] || ln -sf %s %s || exit 31;", arg1, arg2, arg1, arg2));
         }
-        if (run(null, symlinkCommand) != 0)
+        builder.append(String.format("export PATH=\"%s:$PATH\" TMPDIR=\"%s\";", binDir, tmpDir));
-            Log.e(TAG, "Unable to establish symlinks for important executables.");
+
+        preamble = builder.toString();
     }
 
     /**
@@ -60,7 +60,7 @@ class RootShell {
      * @param command  Command to run as root.
      * @return The exit value of the last command run, or -1 if there was an internal error.
      */
-    int run(final List<String> output, final String command) {
+    public int run(final List<String> output, final String command) {
         int exitValue = -1;
         try {
             final ProcessBuilder builder = new ProcessBuilder();

app/src/main/java/com/wireguard/android/backends/VpnService.java

@@ -14,7 +14,6 @@ import android.os.IBinder;
 import android.preference.PreferenceManager;
 import android.provider.OpenableColumns;
 import android.service.quicksettings.TileService;
-import android.system.ErrnoException;
 import android.system.OsConstants;
 import android.util.Log;
 import android.widget.Toast;

app/src/main/res/values/strings.xml

@@ -60,6 +60,12 @@
     <string name="public_key_description">WireGuard public key</string>
     <string name="restore_on_boot">Restore on boot</string>
     <string name="restore_on_boot_summary">Restore previously enabled configurations on boot</string>
+    <string name="install_cmd_line_tools">Install command line tools</string>
+    <string name="install_cmd_line_tools_summary">Install optional tools for scripting into /system/xbin</string>
+    <string name="install_cmd_line_tools_success">wg and wg-quick installed into /system/xbin</string>
+    <string name="install_cmd_line_tools_progress">Installing wg and wg-quick into /system/xbin</string>
+    <string name="install_cmd_line_tools_already">wg and wg-quick are already installed</string>
+    <string name="install_cmd_line_tools_failure">Command line tools could not be installed</string>
     <string name="save">Save</string>
     <string name="settings">Settings</string>
     <string name="status">Status</string>

app/src/main/res/xml/preferences.xml

@@ -9,4 +9,8 @@
         android:key="restore_on_boot"
         android:summary="@string/restore_on_boot_summary"
         android:title="@string/restore_on_boot" />
+    <Preference
+        android:key="install_cmd_line_tools"
+        android:summary="@string/install_cmd_line_tools_summary"
+        android:title="@string/install_cmd_line_tools" />
 </PreferenceScreen>