Resume pending APK install

README.md

@@ -174,6 +174,9 @@ In the app:
   SHA-256, and open Android's installer.
 - If the same version APK was already downloaded and its SHA-256 still matches,
   the app reuses that file instead of downloading it again.
+- If Android sends you to the unknown-app install permission screen, return to
+  the app after allowing it; the app continues installing the already downloaded
+  APK without another update check or download.
 - Open `More` -> `Open APK download` to download the current public APK in a
   browser.
 - Open the `Update` page or `More` -> `Permissions / update status` to see the

app/src/main/java/com/neatstudio/tmuxandroid/MainActivity.java

@@ -2019,6 +2019,14 @@ public final class MainActivity extends Activity {
         super.onBackPressed();
     }
 
+    @Override
+    protected void onResume() {
+        super.onResume();
+        if (updateManager != null) {
+            updateManager.resumePendingInstall();
+        }
+    }
+
     @Override
     protected void onDestroy() {
         closeTerminalSocket();

app/src/main/java/com/neatstudio/tmuxandroid/UpdateManager.java

@@ -25,6 +25,8 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
 final class UpdateManager {
+    private static final String PREF_PENDING_INSTALL_APK = "pending_install_apk";
+
     interface Callback {
         void onChecking(boolean checking);
         void onMessage(String message);
@@ -34,8 +36,9 @@ final class UpdateManager {
     private final SharedPreferences prefs;
     private final Callback callback;
     private final ExecutorService executor = Executors.newSingleThreadExecutor();
-    private boolean checkInProgress;
-    private boolean downloadInProgress;
+    private volatile boolean checkInProgress;
+    private volatile boolean downloadInProgress;
+    private File pendingInstallApk;
 
     UpdateManager(Activity activity, SharedPreferences prefs, Callback callback) {
         this.activity = activity;
@@ -226,15 +229,19 @@ final class UpdateManager {
     private void installApk(File apk) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
                 && !activity.getPackageManager().canRequestPackageInstalls()) {
+            pendingInstallApk = apk;
+            prefs.edit().putString(PREF_PENDING_INSTALL_APK, apk.getAbsolutePath()).apply();
             Intent settingsIntent = new Intent(
                     Settings.ACTION_MANAGE_UNKNOWN_APP_SOURCES,
                     Uri.parse("package:" + activity.getPackageName())
             );
             activity.startActivity(settingsIntent);
-            Toast.makeText(activity, "Allow installs, then run update again", Toast.LENGTH_LONG).show();
+            Toast.makeText(activity, "Allow installs, then return to continue", Toast.LENGTH_LONG).show();
             postMessage("Install permission required");
             return;
         }
+        pendingInstallApk = null;
+        prefs.edit().remove(PREF_PENDING_INSTALL_APK).apply();
 
         Uri apkUri = UpdateFileProvider.getUriForFile(
                 activity,
@@ -253,6 +260,32 @@ final class UpdateManager {
         }
     }
 
+    void resumePendingInstall() {
+        File apk = pendingInstallApk;
+        if (apk == null) {
+            String path = prefs.getString(PREF_PENDING_INSTALL_APK, "");
+            if (path != null && !path.isEmpty()) {
+                apk = new File(path);
+                pendingInstallApk = apk;
+            }
+        }
+        if (apk == null) {
+            return;
+        }
+        if (!apk.exists() || apk.length() <= 0) {
+            pendingInstallApk = null;
+            prefs.edit().remove(PREF_PENDING_INSTALL_APK).apply();
+            postMessage("Downloaded APK is no longer available");
+            return;
+        }
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
+                && !activity.getPackageManager().canRequestPackageInstalls()) {
+            return;
+        }
+        postMessage("Continuing APK install...");
+        installApk(apk);
+    }
+
     private static byte[] readAllBytes(InputStream input) throws Exception {
         java.io.ByteArrayOutputStream output = new java.io.ByteArrayOutputStream();
         byte[] buffer = new byte[16 * 1024];

docs/android-client-notes.md

@@ -106,7 +106,9 @@ provider checks.
 Downloaded APKs are cached by `versionCode`. If a cached APK exists and its
 SHA-256 matches the manifest, the app reuses it instead of downloading the same
 version again. This matters when Android redirects the user to unknown-app
-install settings before the installer can run.
+install settings before the installer can run. After the user grants that
+permission and returns to the app, the app resumes installation of the pending
+APK instead of asking the user to run update again.
 
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