ofz#7816 oom due to too many little allocations in short period of time

Change-Id: I5d575ee37926c24f9708710aa344bbf1f6ea8373
Reviewed-on: https://gerrit.libreoffice.org/53982Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

starmath/source/document.cxx

@@ -673,10 +673,14 @@ bool SmDocShell::ConvertFrom(SfxMedium &rMedium)
                 if ( aStorage->IsStream("Equation Native") )
                 {
                     // is this a MathType Storage?
-                    MathType aEquation( maText );
+                    OUStringBuffer aBuffer;
+                    MathType aEquation(aBuffer);
                     bSuccess = aEquation.Parse( aStorage.get() );
                     if ( bSuccess )
+                    {
+                        maText = aBuffer.makeStringAndClear();
                         Parse();
+                    }
                 }
             }
         }
@@ -1284,7 +1288,8 @@ void SmDocShell::SetModified(bool bModified)
 
 bool SmDocShell::WriteAsMathType3( SfxMedium& rMedium )
 {
-    MathType aEquation( maText, mpTree.get() );
+    OUStringBuffer aTextAsBuffer(maText);
+    MathType aEquation(aTextAsBuffer, mpTree.get());
     return aEquation.ConvertFromStarMath( rMedium );
 }
 

starmath/source/mathtype.hxx

@@ -21,6 +21,7 @@
 #define INCLUDED_STARMATH_SOURCE_MATHTYPE_HXX
 
 #include <rtl/ustring.hxx>
+#include <rtl/ustrbuf.hxx>
 
 #include <set>
 #include <vector>
@@ -55,7 +56,7 @@ typedef ::std::set< MathTypeFont, LessMathTypeFont > MathTypeFontSet;
 class MathType
 {
 public:
-    explicit MathType(OUString &rIn)
+    explicit MathType(OUStringBuffer &rIn)
         : nVersion(0)
         , pS(nullptr)
         , rRet(rIn)
@@ -76,7 +77,7 @@ public:
         Init();
     }
 
-    MathType(OUString &rIn,SmNode *pIn)
+    MathType(OUStringBuffer &rIn,SmNode *pIn)
         : nVersion(0)
         , pS(nullptr)
         , rRet(rIn)
@@ -149,7 +150,7 @@ private:
     void HandleAttributes(SmNode *pNode,int nLevel);
     void TypeFaceToString(OUString &rRet,sal_uInt8 nFace);
 
-    OUString &rRet;
+    OUStringBuffer &rRet;
     SmNode *pTree;
 
     sal_uInt8 nHAlign;
@@ -182,7 +183,7 @@ private:
         tmOARC
     };
 public:
-    static bool LookupChar(sal_Unicode nChar,OUString &rRet,
+    static bool LookupChar(sal_Unicode nChar,OUStringBuffer &rRet,
         sal_uInt8 nVersion,sal_uInt8 nTypeFace=0);
 };
 

starmath/source/node.cxx

@@ -2447,13 +2447,11 @@ void SmMathSymbolNode::Arrange(OutputDevice &rDev, const SmFormat &rFormat)
 
 void SmMathSymbolNode::CreateTextFromNode(OUStringBuffer &rText)
 {
-    OUString sStr;
     sal_Unicode cChar = GetToken().cMathChar;
     if (cChar == MS_INT && GetScaleMode() == SmScaleMode::Height)
-        sStr = "intd ";
+        rText.append("intd ");
     else
-        MathType::LookupChar(cChar, sStr, 3);
-    rText.append(sStr);
+        MathType::LookupChar(cChar, rText, 3);
 }
 
 void SmRectangleNode::CreateTextFromNode(OUStringBuffer &rText)

starmath/source/unofilter.cxx

@@ -68,12 +68,12 @@ sal_Bool MathTypeFilter::filter(const uno::Sequence<beans::PropertyValue>& rDesc
                     if (auto pModel = dynamic_cast<SmModel*>(m_xDstDoc.get()))
                     {
                         auto pDocShell = static_cast<SmDocShell*>(pModel->GetObjectShell());
-                        OUString aText = pDocShell->GetText();
+                        OUStringBuffer aText(pDocShell->GetText());
                         MathType aEquation(aText);
                         bSuccess = aEquation.Parse(aStorage.get());
                         if (bSuccess)
                         {
-                            pDocShell->SetText(aText);
+                            pDocShell->SetText(aText.makeStringAndClear());
                             pDocShell->Parse();
                         }
                     }