Offer to grant storage permissions if absent

* java/org/gnu/emacs/EmacsService.java (externalStorageAvailable)
(requestStorageAccess23, requestStorageAccess30)
(requestStorageAccess): New functions.

* lisp/startup.el (fancy-startup-tail, normal-splash-screen):
Call android-win functions for inserting the new storage
permission notice.

* lisp/term/android-win.el
(android-display-storage-permission-popup)
(android-after-splash-screen): New functions.

* src/android.c (android_init_emacs_service): Link to new Java
functions.
(android_external_storage_available_p)
(android_request_storage_access): New functions.

* src/android.h: Update prototypes.

* src/androidfns.c (Fandroid_external_storage_available_p)
(Fandroid_request_storage_access): New functions.
(syms_of_androidfns): Register new subrs.

1 files changed, 122 insertions, 0 deletions

diff --git a/java/org/gnu/emacs/EmacsService.java b/java/org/gnu/emacs/EmacsService.java
index 5bd1dcc5a88..3cc37dd992d 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -63,6 +63,7 @@ import android.net.Uri;
 
 import android.os.BatteryManager;
 import android.os.Build;
+import android.os.Environment;
 import android.os.Looper;
 import android.os.IBinder;
 import android.os.Handler;
@@ -73,6 +74,7 @@ import android.os.VibrationEffect;
 
 import android.provider.DocumentsContract;
 import android.provider.DocumentsContract.Document;
+import android.provider.Settings;
 
 import android.util.Log;
 import android.util.DisplayMetrics;
@@ -1909,4 +1911,124 @@ public final class EmacsService extends Service
 
     return false;
   }
+
+
+
+  /* Functions for detecting and requesting storage permissions.  */
+
+  public boolean
+  externalStorageAvailable ()
+  {
+    final String readPermission;
+
+    readPermission = "android.permission.READ_EXTERNAL_STORAGE";
+
+    return (Build.VERSION.SDK_INT < Build.VERSION_CODES.R
+	    ? (checkSelfPermission (readPermission)
+	       == PackageManager.PERMISSION_GRANTED)
+	    : Environment.isExternalStorageManager ());
+  }
+
+  private void
+  requestStorageAccess23 ()
+  {
+    Runnable runnable;
+
+    runnable = new Runnable () {
+	@Override
+	public void
+	run ()
+	{
+	  EmacsActivity activity;
+	  String permission, permission1;
+
+	  permission = "android.permission.READ_EXTERNAL_STORAGE";
+	  permission1 = "android.permission.WRITE_EXTERNAL_STORAGE";
+
+	  /* Find an activity that is entitled to display a permission
+	     request dialog.  */
+
+	  if (EmacsActivity.focusedActivities.isEmpty ())
+	    {
+	      /* If focusedActivities is empty then this dialog may
+		 have been displayed immediately after another popup
+		 dialog was dismissed.  Try the EmacsActivity to be
+		 focused.  */
+
+	      activity = EmacsActivity.lastFocusedActivity;
+
+	      if (activity == null)
+		{
+		  /* Still no luck.  Return failure.  */
+		  return;
+		}
+	    }
+	  else
+	    activity = EmacsActivity.focusedActivities.get (0);
+
+	  /* Now request these permissions.  */
+	  activity.requestPermissions (new String[] { permission,
+						      permission1, },
+	    0);
+	}
+      };
+
+    runOnUiThread (runnable);
+  }
+
+  private void
+  requestStorageAccess30 ()
+  {
+    Runnable runnable;
+    final Intent intent;
+
+    intent
+      = new Intent (Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION,
+		    Uri.parse ("package:org.gnu.emacs"));
+
+    runnable = new Runnable () {
+	@Override
+	public void
+	run ()
+	{
+	  EmacsActivity activity;
+
+	  /* Find an activity that is entitled to display a permission
+	     request dialog.  */
+
+	  if (EmacsActivity.focusedActivities.isEmpty ())
+	    {
+	      /* If focusedActivities is empty then this dialog may
+		 have been displayed immediately after another popup
+		 dialog was dismissed.  Try the EmacsActivity to be
+		 focused.  */
+
+	      activity = EmacsActivity.lastFocusedActivity;
+
+	      if (activity == null)
+		{
+		  /* Still no luck.  Return failure.  */
+		  return;
+		}
+	    }
+	  else
+	    activity = EmacsActivity.focusedActivities.get (0);
+
+	  /* Now request these permissions.  */
+
+	  activity.startActivity (intent);
+	}
+      };
+
+    runOnUiThread (runnable);
+  }
+
+  public void
+  requestStorageAccess ()
+  {
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.R)
+      requestStorageAccess23 ();
+    else
+      requestStorageAccess30 ();
+  }
 };