android: skip SAF directory picker if unsupported

updates tailscale/corp#30254

This adds an upfront isAndroidTV check before we set the
SAF directory picker activity.  We'll check both that we can
actually launch the activity and that this isn't and AndroidTV
device where the directory picker activity isn't supported or
has a tendency to throw ActivityNotFound exceptions.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>

android/src/main/java/com/tailscale/ipn/MainActivity.kt

@@ -53,7 +53,7 @@ import com.tailscale.ipn.mdm.ShowHide
 import com.tailscale.ipn.ui.model.Ipn
 import com.tailscale.ipn.ui.notifier.Notifier
 import com.tailscale.ipn.ui.theme.AppTheme
-import com.tailscale.ipn.ui.util.AndroidTVUtil
+import com.tailscale.ipn.ui.util.AndroidTVUtil.isAndroidTV
 import com.tailscale.ipn.ui.util.set
 import com.tailscale.ipn.ui.util.universalFit
 import com.tailscale.ipn.ui.view.AboutView
@@ -177,7 +177,9 @@ class MainActivity : ComponentActivity() {
         }
     viewModel.setVpnPermissionLauncher(vpnPermissionLauncher)
 
-    val directoryPickerLauncher =
+    var directoryPickerLauncher: ActivityResultLauncher<Uri?>? = null
+    if (canOpenDocumentTree()) {
+      directoryPickerLauncher =
           registerForActivityResult(ActivityResultContracts.OpenDocumentTree()) { uri: Uri? ->
             if (uri != null) {
               try {
@@ -213,13 +215,15 @@ class MainActivity : ComponentActivity() {
               }
             } else {
               TSLog.d(
-                "MainActivity", "Taildrop directory not saved. Will fall back to internal storage.")
+                  "MainActivity",
+                  "Taildrop directory not saved. Will fall back to internal storage.")
 
               // Fall back to internal storage.
             }
           }
 
       viewModel.setDirectoryPickerLauncher(directoryPickerLauncher)
+    }
 
     setContent {
       navController = rememberNavController()
@@ -354,9 +358,11 @@ class MainActivity : ComponentActivity() {
                         { navController.navigate("taildropDir") },
                         { navController.navigate("notifications") })
                   }
+                  directoryPickerLauncher?.let {
+                    val launcher = it
                     composable("taildropDir") {
-                    TaildropDirView(
+                      TaildropDirView(backTo("permissions"), launcher, permissionsViewModel)
-                        backTo("permissions"), directoryPickerLauncher, permissionsViewModel)
+                    }
                   }
                   composable("notifications") {
                     NotificationsView(backTo("permissions"), ::openApplicationSettings)
@@ -406,6 +412,16 @@ class MainActivity : ComponentActivity() {
     lifecycleScope.launch { Notifier.loginFinished.collect { _ -> loginQRCode.set(null) } }
   }
 
+  // Most AndroidTV's don't support this and the UX is completely broken regardless.   We have
+  // reports of some old devices throwing ActivityNotFound exceptions on TV as well, so we
+  // carefully guard against the attempt.
+  private fun Context.canOpenDocumentTree(): Boolean {
+    return !isAndroidTV() &&
+        Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)
+            .addCategory(Intent.CATEGORY_DEFAULT)
+            .resolveActivity(packageManager) != null
+  }
+
   private fun showOtherVPNConflictDialog() {
     AlertDialog.Builder(this)
         .setTitle(R.string.vpn_permission_denied)
@@ -437,7 +453,7 @@ class MainActivity : ComponentActivity() {
   // Returns true if we should render a QR code instead of launching a browser
   // for login requests
   private fun useQRCodeLogin(): Boolean {
-    return AndroidTVUtil.isAndroidTV()
+    return isAndroidTV()
   }
 
   override fun onNewIntent(intent: Intent) {

android/src/main/java/com/tailscale/ipn/ui/viewModel/MainViewModel.kt

@@ -221,8 +221,10 @@ class MainViewModel(private val vpnViewModel: VpnViewModel) : IpnViewModel() {
   }
 
   fun showDirectoryPickerLauncher() {
+    directoryPickerLauncher?.let {
       _showDirectoryPickerInterstitial.set(false)
-    directoryPickerLauncher?.launch(null)
+      it.launch(null)
+    }
   }
 
   fun checkIfTaildropDirectorySelected() {
@@ -233,17 +235,23 @@ class MainViewModel(private val vpnViewModel: VpnViewModel) : IpnViewModel() {
     val app = App.get()
     val storedUri = app.getStoredDirectoryUri()
     if (storedUri == null) {
+      if (directoryPickerLauncher != null) {
         // No stored URI, so launch the directory picker.
         _showDirectoryPickerInterstitial.set(true)
+      }
       return
     }
 
     val documentFile = DocumentFile.fromTreeUri(app, storedUri)
     if (documentFile == null || !documentFile.exists() || !documentFile.canWrite()) {
+      if (directoryPickerLauncher != null) {
         TSLog.d(
             "MainViewModel",
             "Stored directory URI is invalid or inaccessible; launching directory picker.")
         _showDirectoryPickerInterstitial.set(true)
+      } else {
+        TSLog.d("MainViewModel", "Directory picker activity not available")
+      }
     } else {
       TSLog.d("MainViewModel", "Using stored directory URI: $storedUri")
     }