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, 38 insertions, 0 deletions

diff --git a/src/androidfns.c b/src/androidfns.c
index 772a4f51e78..785587d9282 100644
--- a/src/androidfns.c
+++ b/src/androidfns.c
@@ -3096,6 +3096,42 @@ within the directory `/content/storage'.  */)
 
 
 
+/* Functions concerning storage permissions.  */
+
+DEFUN ("android-external-storage-available-p",
+       Fandroid_external_storage_available_p,
+       Sandroid_external_storage_available_p, 0, 0, 0,
+       doc: /* Return whether Emacs is entitled to access external storage.
+Return nil if the requisite permissions for external storage access
+have not been granted to Emacs, t otherwise.  Such permissions can be
+requested by means of the `android-request-storage-access'
+command.
+
+External storage on Android encompasses the `/sdcard' and
+`/storage/emulated' directories, access to which is denied to programs
+absent these permissions.  */)
+  (void)
+{
+  return android_external_storage_available_p () ? Qt : Qnil;
+}
+
+DEFUN ("android-request-storage-access", Fandroid_request_storage_access,
+       Sandroid_request_storage_access, 0, 0, "",
+       doc: /* Request rights to access external storage.
+
+Return nil whether access is accorded or not, immediately subsequent
+to displaying the permissions request dialog.
+
+`android-external-storage-available-p' (which see) ascertains if Emacs
+has received such rights.  */)
+  (void)
+{
+  android_request_storage_access ();
+  return Qnil;
+}
+
+
+
 /* Miscellaneous input method related stuff.  */
 
 /* Report X, Y, by the phys cursor width and height as the cursor
@@ -3302,6 +3338,8 @@ bell being rung.  */);
 #ifndef ANDROID_STUBIFY
   defsubr (&Sandroid_query_battery);
   defsubr (&Sandroid_request_directory_access);
+  defsubr (&Sandroid_external_storage_available_p);
+  defsubr (&Sandroid_request_storage_access);
 
   tip_timer = Qnil;
   staticpro (&tip_timer);