From b0b8815fffcd1d3862a4784fe93bb7c9d66b7d1c Mon Sep 17 00:00:00 2001
From: Patrick Luby <patrick.luby@collabora.com>
Date: Fri, 10 Mar 2023 12:11:25 -0500
Subject: [PATCH] Handle pasting disallowed clipboard contents on iOS

When another app owns the current clipboard contents, pasting
will display a "allow or disallow" dialog. If the disallow
option is selected, the data from the UIPasteboard will be
garbage and GetLOKNotifier() will return a nullptr. Since calling
SetLOKNotifier() with a nullptr aborts in an assert(), fix the
crash by failing gracefully.

Also, throw an exception if the -[UIPasteboard dataForPasteboardType:]
returns nil. By throwing an exception,  the "allow or disallow"
dialog will display again the next time the user tries to paste.

Change-Id: I05d689b679a7643a8478e3ce0f416205fdf8ec23
Reference-to: https://github.com/CollaboraOnline/online/issues/5908
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/148655
Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoffice@gmail.com>
Reviewed-by: Andras Timar <andras.timar@collabora.com>
(cherry picked from commit 1dd68786a927a23e5465589025abd90b8c9f4e7b)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/148627
Tested-by: Jenkins
Reviewed-by: Patrick Luby <plubius@neooffice.org>
---
 vcl/ios/iOSTransferable.cxx  | 10 ++++++++++
 vcl/source/window/dialog.cxx | 13 +++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/vcl/ios/iOSTransferable.cxx b/vcl/ios/iOSTransferable.cxx
index ece771e7f60b..bfbc8a9afa82 100644
--- a/vcl/ios/iOSTransferable.cxx
+++ b/vcl/ios/iOSTransferable.cxx
@@ -109,6 +109,16 @@ Any SAL_CALL iOSTransferable::getTransferData(const DataFlavor& aFlavor)
     DataProviderPtr_t dp;
 
     NSData* sysData = [[UIPasteboard generalPasteboard] dataForPasteboardType:sysFormat];
+    if (!sysData)
+    {
+        // Related: gh#5908 throw an exception if the data flavor is nil
+        // If nil is returned, it can mean that the user has selected the
+        // "disallow" option and so we can't access the current clipboard
+        // contents. Also, by throwing an exception, the "allow or disallow"
+        // dialog will display again the next time the user tries to paste.
+        throw UnsupportedFlavorException("Data flavor is nil", static_cast<XTransferable*>(this));
+    }
+
     dp = DataFlavorMapper::getDataProvider(sysFormat, sysData);
 
     if (dp.get() == nullptr)
diff --git a/vcl/source/window/dialog.cxx b/vcl/source/window/dialog.cxx
index a255ed4b9a47..3327e371e6c1 100644
--- a/vcl/source/window/dialog.cxx
+++ b/vcl/source/window/dialog.cxx
@@ -926,7 +926,20 @@ bool Dialog::ImplStartExecute()
     if (bModal)
     {
         if (bKitActive && !GetLOKNotifier())
+        {
+#ifdef IOS
+            // gh#5908 handle pasting disallowed clipboard contents on iOS
+            // When another app owns the current clipboard contents, pasting
+            // will display a "allow or disallow" dialog. If the disallow
+            // option is selected, the data from the UIPasteboard will be
+            // garbage and we will find ourselves here. Since calling
+            // SetLOKNotifier() with a nullptr aborts in an assert(), fix
+            // the crash by failing gracefully.
+            return false;
+#else
             SetLOKNotifier(mpDialogImpl->m_aInstallLOKNotifierHdl.Call(nullptr));
+#endif
+        }
 
         switch ( Application::GetDialogCancelMode() )
         {