tdf#147008 sw_fieldmarkhide: fix invalid NonTextFieldmark positions

Commit ab6176e88f78d0b3aa2490fbc7858304c2d4a437 introduced a crash
in ModelToViewHelper when the positions of a NonTextFieldmark are invalid.

The NonTextFieldmark must always contain 1 CH_TXT_ATR_FORMELEMENT
but after SplitNode() the position is
(rr) p *pFieldMark->m_pPos1
$2 = SwPosition (node 10, offset 1)
(rr) p *pFieldMark->m_pPos2
$3 = SwPosition (node 9, offset 0)

This is because in ContentIdxStoreImpl::SaveBkmks() there is an
asymmetry where the m_pPos2 is recorded to be wrongly corrected to node
9, but if the positions were swapped so that m_pPos1 is the start
position, then it will not be recorded and remain in node 10.

So fix this by changing the NonTextFieldmark to insert its
CH_TXT_ATR_FORMELEMENT differently.

There is some very subtle code in SwTextNode::Update() that is again
asymmetric and (non-obviously) prefers to move m_pPos2 and leave m_pPos1
alone (by moving it to aTmpIdxReg) in case the positions are equal.

But then the fieldmark code increments "rEnd" (which is really the
m_pPos1 i.e. the start after InsertString() returns), and then
decrements m_pPos2.

So avoid the problem by removing these 2 pointless adjustments.

Then it turns a bunch of tests fail because other code assumes that
m_pPos1 is the end of the NonTextFieldmark, so fix
MarkManager::changeFormFieldmarkType(), ModelToViewHelper and
SwHistoryNoTextFieldmark to use GetMarkStart().

Change-Id: I7c82f9a67661121662c95727e0f8f15e06d85a3a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/129289
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit ea06852ee87531794f07710de496734a647a9062)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/129265
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

5 files changed, 28 insertions, 17 deletions

diff --git a/sw/qa/extras/uiwriter/uiwriter2.cxx b/sw/qa/extras/uiwriter/uiwriter2.cxx
index 79aa517c66f4..65142dbd64e1 100644
--- a/sw/qa/extras/uiwriter/uiwriter2.cxx
+++ b/sw/qa/extras/uiwriter/uiwriter2.cxx
@@ -3600,6 +3600,14 @@ CPPUNIT_TEST_FIXTURE(SwUiWriterTest2, testCheckboxFormFieldInsertion)
     pFieldmark = dynamic_cast<::sw::mark::IFieldmark*>(*aIter);
     CPPUNIT_ASSERT(pFieldmark);
     CPPUNIT_ASSERT_EQUAL(OUString(ODF_FORMCHECKBOX), pFieldmark->GetFieldname());
+
+    // tdf#147008 this would crash
+    SwWrtShell* pWrtShell = pDoc->GetDocShell()->GetWrtShell();
+    pWrtShell->StartOfSection(false);
+    pWrtShell->SplitNode();
+    CPPUNIT_ASSERT_EQUAL(pFieldmark->GetMarkPos().nNode, pFieldmark->GetOtherMarkPos().nNode);
+    CPPUNIT_ASSERT_EQUAL(sal_Int32(pFieldmark->GetMarkPos().nContent.GetIndex() + 1),
+                         pFieldmark->GetOtherMarkPos().nContent.GetIndex());
 }
 
 CPPUNIT_TEST_FIXTURE(SwUiWriterTest2, testDropDownFormFieldInsertion)
diff --git a/sw/source/core/crsr/bookmark.cxx b/sw/source/core/crsr/bookmark.cxx
index 2945b018bb8b..417558aad130 100644
--- a/sw/source/core/crsr/bookmark.cxx
+++ b/sw/source/core/crsr/bookmark.cxx
@@ -154,6 +154,10 @@ namespace
             SwPosition const sepPos(sw::mark::FindFieldSep(rField));
             assert(sepPos.nNode.GetNode().GetTextNode()->GetText()[sepPos.nContent.GetIndex()] == CH_TXT_ATR_FIELDSEP); (void) sepPos;
         }
+        else
+        {   // must be m_pPos1 < m_pPos2 because of asymmetric SplitNode update
+            assert(rField.GetMarkPos().nContent.GetIndex() + 1 == rField.GetOtherMarkPos().nContent.GetIndex());
+        }
         SwPosition const& rEnd(rField.GetMarkEnd());
         assert(rEnd.nNode.GetNode().GetTextNode()->GetText()[rEnd.nContent.GetIndex() - 1] == aEndMark); (void) rEnd;
     }
@@ -207,7 +211,14 @@ namespace
         {
             SwPaM aEndPaM(rEnd);
             io_rDoc.getIDocumentContentOperations().InsertString(aEndPaM, OUString(aEndMark));
-            ++rEnd.nContent;
+            if (aEndMark != CH_TXT_ATR_FORMELEMENT)
+            {
+                ++rEnd.nContent; // InsertString didn't move non-empty mark
+            }
+            else
+            {   // InsertString moved the mark's end, not its start
+                assert(rField.GetMarkPos().nContent.GetIndex() + 1 == rField.GetOtherMarkPos().nContent.GetIndex());
+            }
         }
         lcl_AssertFieldMarksSet(rField, aStartMark, aEndMark);
 
@@ -590,12 +601,6 @@ namespace sw::mark
         if (eMode == sw::mark::InsertMode::New)
         {
             lcl_SetFieldMarks(*this, io_rDoc, CH_TXT_ATR_FIELDSTART, CH_TXT_ATR_FORMELEMENT, pSepPos);
-
-            // For some reason the end mark is moved from 1 by the Insert:
-            // we don't want this for checkboxes
-            SwPosition aNewEndPos = GetMarkEnd();
-            aNewEndPos.nContent--;
-            SetMarkEndPos( aNewEndPos );
         }
         else
         {
diff --git a/sw/source/core/doc/docbm.cxx b/sw/source/core/doc/docbm.cxx
index 5ed676719622..c15c1dd3fcea 100644
--- a/sw/source/core/doc/docbm.cxx
+++ b/sw/source/core/doc/docbm.cxx
@@ -1419,8 +1419,7 @@ namespace sw::mark
     void MarkManager::deleteFieldmarkAt(const SwPosition& rPos)
     {
         auto const pFieldmark = dynamic_cast<Fieldmark*>(getFieldmarkAt(rPos));
-        if (!pFieldmark)
-            return;
+        assert(pFieldmark); // currently all callers require it to be there
 
         deleteMark(lcl_FindMark(m_vAllMarks, pFieldmark));
     }
@@ -1455,12 +1454,11 @@ namespace sw::mark
 
         // Store attributes needed to create the new fieldmark
         OUString sName = pFieldmark->GetName();
-        SwPaM aPaM(pFieldmark->GetMarkPos());
+        SwPaM const aPaM(pFieldmark->GetMarkStart());
 
         // Remove the old fieldmark and create a new one with the new type
-        if(aPaM.GetPoint()->nContent > 0 && (rNewType == ODF_FORMDROPDOWN || rNewType == ODF_FORMCHECKBOX))
+        if (rNewType == ODF_FORMDROPDOWN || rNewType == ODF_FORMCHECKBOX)
         {
-            --aPaM.GetPoint()->nContent;
             SwPosition aNewPos (aPaM.GetPoint()->nNode, aPaM.GetPoint()->nContent);
             deleteFieldmarkAt(aNewPos);
             return makeNoTextFieldBookmark(aPaM, sName, rNewType);
diff --git a/sw/source/core/txtnode/modeltoviewhelper.cxx b/sw/source/core/txtnode/modeltoviewhelper.cxx
index 846e4d1a51b1..1f35cd1ee614 100644
--- a/sw/source/core/txtnode/modeltoviewhelper.cxx
+++ b/sw/source/core/txtnode/modeltoviewhelper.cxx
@@ -286,7 +286,7 @@ ModelToViewHelper::ModelToViewHelper(const SwTextNode &rNode,
 
             for (sw::mark::IFieldmark *const pMark : aNoTextFieldmarks)
             {
-                const sal_Int32 nDummyCharPos = pMark->GetMarkPos().nContent.GetIndex()-1;
+                const sal_Int32 nDummyCharPos = pMark->GetMarkStart().nContent.GetIndex();
                 if (aHiddenMulti.IsSelected(nDummyCharPos))
                     continue;
                 std::vector<block>::iterator aFind = std::find_if(aBlocks.begin(), aBlocks.end(),
diff --git a/sw/source/core/undo/rolbck.cxx b/sw/source/core/undo/rolbck.cxx
index 85f92be47670..49c4d9b1d946 100644
--- a/sw/source/core/undo/rolbck.cxx
+++ b/sw/source/core/undo/rolbck.cxx
@@ -729,8 +729,8 @@ bool SwHistoryBookmark::IsEqualBookmark(const ::sw::mark::IMark& rBkmk)
 SwHistoryNoTextFieldmark::SwHistoryNoTextFieldmark(const ::sw::mark::IFieldmark& rFieldMark)
     : SwHistoryHint(HSTRY_NOTEXTFIELDMARK)
     , m_sType(rFieldMark.GetFieldname())
-    , m_nNode(rFieldMark.GetMarkPos().nNode.GetIndex())
-    , m_nContent(rFieldMark.GetMarkPos().nContent.GetIndex())
+    , m_nNode(rFieldMark.GetMarkStart().nNode.GetIndex())
+    , m_nContent(rFieldMark.GetMarkStart().nContent.GetIndex())
 {
 }
 
@@ -760,8 +760,8 @@ void SwHistoryNoTextFieldmark::ResetInDoc(SwDoc& rDoc)
     std::optional<SwPaM> pPam;
 
     const SwContentNode* pContentNd = rNds[m_nNode]->GetContentNode();
-    if(pContentNd)
-        pPam.emplace(*pContentNd, m_nContent-1);
+    assert(pContentNd);
+    pPam.emplace(*pContentNd, m_nContent);
 
     if (pPam)
     {