tdf#138605 sw change tracking: fix crash with Undo

Regression from commit 469f472fb31c4ef1a57f8ec54ba750c1332feec2
(tdf#138479 tdf#137769 sw ChangesInMargin: fix Undo in paragraphs)

Change-Id: I7826b7920e51733da98c00bfdcb8636d42655afc
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/107637
Tested-by: Jenkins
Reviewed-by: László Németh <nemeth@numbertext.org>

2 files changed, 33 insertions, 3 deletions

diff --git a/sw/qa/extras/uiwriter/uiwriter2.cxx b/sw/qa/extras/uiwriter/uiwriter2.cxx
index 4bbaeee20341..cb33dc0ac5b3 100644
--- a/sw/qa/extras/uiwriter/uiwriter2.cxx
+++ b/sw/qa/extras/uiwriter/uiwriter2.cxx
@@ -1957,6 +1957,36 @@ CPPUNIT_TEST_FIXTURE(SwUiWriterTest2, testTdf137503)
     CPPUNIT_ASSERT(!pWrtShell->GetViewOptions()->IsShowChangesInMargin());
 }
 
+CPPUNIT_TEST_FIXTURE(SwUiWriterTest2, testTdf138605)
+{
+    SwDoc* const pDoc(createDoc());
+    SwWrtShell* const pWrtShell = pDoc->GetDocShell()->GetWrtShell();
+    SwXTextDocument* pTextDoc = dynamic_cast<SwXTextDocument*>(mxComponent.get());
+    CPPUNIT_ASSERT(pTextDoc);
+
+    // turn on red-lining and show changes
+    pDoc->getIDocumentRedlineAccess().SetRedlineFlags(RedlineFlags::On | RedlineFlags::ShowInsert
+                                                      | RedlineFlags::ShowDelete);
+    CPPUNIT_ASSERT_MESSAGE("redlining should be on",
+                           pDoc->getIDocumentRedlineAccess().IsRedlineOn());
+    CPPUNIT_ASSERT_MESSAGE(
+        "redlines should be visible",
+        IDocumentRedlineAccess::IsShowChanges(pDoc->getIDocumentRedlineAccess().GetRedlineFlags()));
+
+    // insert a word, delete it with change tracking and try to undo it
+    pWrtShell->Insert("word");
+    dispatchCommand(mxComponent, ".uno:SelectAll", {});
+    dispatchCommand(mxComponent, ".uno:Delete", {});
+    // this crashed due to bad access to the empty redline table
+    dispatchCommand(mxComponent, ".uno:Undo", {});
+
+    // more Undo
+    CPPUNIT_ASSERT(getParagraph(1)->getString().startsWith("word"));
+    dispatchCommand(mxComponent, ".uno:Undo", {});
+    CPPUNIT_ASSERT(getParagraph(1)->getString().startsWith(""));
+    dispatchCommand(mxComponent, ".uno:Undo", {});
+}
+
 CPPUNIT_TEST_FIXTURE(SwUiWriterTest2, testTdf138135)
 {
     load(DATA_DIRECTORY, "tdf132160.odt");
diff --git a/sw/source/core/undo/unredln.cxx b/sw/source/core/undo/unredln.cxx
index 6865beba6cd6..a737863c3835 100644
--- a/sw/source/core/undo/unredln.cxx
+++ b/sw/source/core/undo/unredln.cxx
@@ -93,15 +93,15 @@ void SwUndoRedline::UndoImpl(::sw::UndoRedoContext & rContext)
 
     // fix PaM for deletions shown in margin
     bool bIsDeletion = dynamic_cast<SwUndoRedlineDelete*>(this);
+    const SwRedlineTable& rTable = rDoc.getIDocumentRedlineAccess().GetRedlineTable();
     sal_uInt32 nMaxId = SAL_MAX_UINT32;
-    if ( bIsDeletion )
+    if ( bIsDeletion && rTable.size() > 0 )
     {
         // Nodes of the deletion range are in the newest invisible redlines.
         // Set all redlines visible and recover the original deletion range.
-        for (sal_uInt32 nNodes = 0; nNodes <  m_nEndNode - m_nSttNode + 1; ++ nNodes)
+        for (sal_uInt32 nNodes = 0; nNodes <  m_nEndNode - m_nSttNode + 1; ++nNodes)
         {
             SwRedlineTable::size_type nCurRedlinePos = 0;
-            const SwRedlineTable& rTable = rDoc.getIDocumentRedlineAccess().GetRedlineTable();
             SwRangeRedline * pRedline(rTable[nCurRedlinePos]);
 
             // search last but nNodes redline by its nth biggest id