resolved fdo#48501 enable line size >64k in SvStream::Read*Line()

CSV and other text formats may come with line sizes >64k that so far were
truncated due to limitations in ByteString/UniString/String, even if one line
consists of several fields that each are <64k.

Introduced additional SvStream methods that read into rtl::OString and
rtl::OUString and let SvStream::ReadUniOrByteStringLine() fill solely an
rtl::OUString.

Made Calc CSV import use those.

16 files changed, 267 insertions, 119 deletions

diff --git a/sc/source/filter/dif/difimp.cxx b/sc/source/filter/dif/difimp.cxx
index 19189a19e807..1ffae6a1cb40 100644
--- a/sc/source/filter/dif/difimp.cxx
+++ b/sc/source/filter/dif/difimp.cxx
@@ -312,7 +312,7 @@ TOPIC DifParser::GetNextTopic( void )
     };
 
     STATE                   eS = S_START;
-    String                  aLine;
+    rtl::OUString           aLine;
 
     nVector = 0;
     nVal = 0;
@@ -360,7 +360,7 @@ TOPIC DifParser::GetNextTopic( void )
                 break;
             case S_VectorVal:
             {
-                const sal_Unicode*      pCur = aLine.GetBuffer();
+                const sal_Unicode*      pCur = aLine.getStr();
 
                 pCur = ScanIntVal( pCur, nVector );
 
@@ -375,10 +375,11 @@ TOPIC DifParser::GetNextTopic( void )
             }
                 break;
             case S_Data:
-                OSL_ENSURE( aLine.Len() >= 2,
+                OSL_ENSURE( aLine.getLength() >= 2,
                     "+GetNextTopic(): <String> ist zu kurz!" );
-                if( aLine.Len() > 2 )
-                    aData = aLine.Copy( 1, aLine.Len() - 2 );
+                OSL_ENSURE( aLine.getLength() - 2 <= STRING_MAXLEN, "GetNextTopic(): line doesn't fit into data");
+                if( aLine.getLength() > 2 )
+                    aData = aLine.copy( 1, aLine.getLength() - 2 );
                 else
                     aData.Erase();
                 eS = S_END;
@@ -448,16 +449,16 @@ DATASET DifParser::GetNumberDataset( const sal_Unicode* pPossibleNumericData )
     return eRet;
 }
 
-bool DifParser::ReadNextLine( String& rStr )
+bool DifParser::ReadNextLine( rtl::OUString& rStr )
 {
-    if( aLookAheadLine.Len() == 0 )
+    if( aLookAheadLine.isEmpty() )
     {
         return rIn.ReadUniOrByteStringLine( rStr, rIn.GetStreamCharSet() );
     }
     else
     {
         rStr = aLookAheadLine;
-        aLookAheadLine.Erase();
+        aLookAheadLine = rtl::OUString();
         return true;
     }
 }
@@ -469,10 +470,10 @@ bool DifParser::LookAhead()
     const sal_Unicode* pAktBuffer;
     bool bValidStructure = false;
 
-    OSL_ENSURE( aLookAheadLine.Len() == 0, "*DifParser::LookAhead(): LookAhead called twice in a row" );
+    OSL_ENSURE( aLookAheadLine.isEmpty(), "*DifParser::LookAhead(): LookAhead called twice in a row" );
     rIn.ReadUniOrByteStringLine( aLookAheadLine, rIn.GetStreamCharSet() );
 
-    pAktBuffer = aLookAheadLine.GetBuffer();
+    pAktBuffer = aLookAheadLine.getStr();
 
     switch( *pAktBuffer )
     {
@@ -493,7 +494,7 @@ bool DifParser::LookAhead()
             }
             break;
         case '1':                   // String Data
-            if( Is1_0( aLookAheadLine.GetBuffer() ) )
+            if( Is1_0( aLookAheadLine.getStr() ) )
             {
                 bValidStructure = true;
             }
@@ -505,12 +506,12 @@ bool DifParser::LookAhead()
 DATASET DifParser::GetNextDataset( void )
 {
     DATASET             eRet = D_UNKNOWN;
-    String              aLine;
+    rtl::OUString       aLine;
     const sal_Unicode*      pAktBuffer;
 
     ReadNextLine( aLine );
 
-    pAktBuffer = aLine.GetBuffer();
+    pAktBuffer = aLine.getStr();
 
     switch( *pAktBuffer )
     {
@@ -520,9 +521,9 @@ DATASET DifParser::GetNextDataset( void )
             if( Is1_0( pAktBuffer ) )
             {
                 ReadNextLine( aLine );
-                if( IsBOT( aLine.GetBuffer() ) )
+                if( IsBOT( aLine.getStr() ) )
                     eRet = D_BOT;
-                else if( IsEOD( aLine.GetBuffer() ) )
+                else if( IsEOD( aLine.getStr() ) )
                     eRet = D_EOD;
             }
             break;
@@ -532,25 +533,32 @@ DATASET DifParser::GetNextDataset( void )
             {
                 pAktBuffer++;
                 eRet = GetNumberDataset(pAktBuffer);
-                ReadNextLine( aData );
+                rtl::OUString aTmpLine;
+                ReadNextLine( aTmpLine );
                 if ( eRet == D_SYNT_ERROR )
                 {   // for broken records write "#ERR: data" to cell
                     String aTmp( RTL_CONSTASCII_USTRINGPARAM( "#ERR: " ));
                     aTmp += pAktBuffer;
                     aTmp.AppendAscii( " (" );
-                    aTmp += aData;
+                    OSL_ENSURE( aTmpLine.getLength() <= STRING_MAXLEN - aTmp.Len() - 1, "GetNextDataset(): line doesn't fit into data");
+                    aTmp += aTmpLine;
                     aTmp += sal_Unicode(')');
                     aData = aTmp;
                     eRet = D_STRING;
                 }
+                else
+                {
+                    OSL_ENSURE( aTmpLine.getLength() <= STRING_MAXLEN, "GetNextDataset(): line doesn't fit into data");
+                    aData = aTmpLine;
+                }
             }
             break;
         case '1':                   // String Data
-            if( Is1_0( aLine.GetBuffer() ) )
+            if( Is1_0( aLine.getStr() ) )
             {
                 ReadNextLine( aLine );
-                xub_StrLen nLineLength = aLine.Len();
-                const sal_Unicode* pLine = aLine.GetBuffer();
+                sal_Int32 nLineLength = aLine.getLength();
+                const sal_Unicode* pLine = aLine.getStr();
 
                 if( nLineLength >= 1 && *pLine == '"' )
                 {
@@ -562,7 +570,8 @@ DATASET DifParser::GetNextDataset( void )
                         // Single line string
                         if( nLineLength >= 2 && pLine[nLineLength - 1] == '"' )
                         {
-                            aData = aLine.Copy( 1, nLineLength - 2 );
+                            OSL_ENSURE( aLine.getLength() - 2 <= STRING_MAXLEN, "GetNextDataset(): line doesn't fit into data");
+                            aData = aLine.copy( 1, nLineLength - 2 );
                             lcl_DeEscapeQuotesDif( aData );
                             eRet = D_STRING;
                         }
@@ -570,7 +579,8 @@ DATASET DifParser::GetNextDataset( void )
                     else
                     {
                         // Multiline string
-                        aData = aLine.Copy( 1 );
+                        OSL_ENSURE( aLine.getLength() - 1 <= STRING_MAXLEN, "GetNextDataset(): line doesn't fit into data");
+                        aData = aLine.copy( 1 );
                         bool bContinue = true;
                         while ( bContinue )
                         {
@@ -578,17 +588,19 @@ DATASET DifParser::GetNextDataset( void )
                             bContinue = !rIn.IsEof() && ReadNextLine( aLine );
                             if( bContinue )
                             {
-                                nLineLength = aLine.Len();
+                                nLineLength = aLine.getLength();
                                 if( nLineLength >= 1 )
                                 {
-                                    pLine = aLine.GetBuffer();
+                                    pLine = aLine.getStr();
                                     bContinue = !LookAhead();
                                     if( bContinue )
                                     {
+                                        OSL_ENSURE( aLine.getLength() <= STRING_MAXLEN - aData.Len(), "GetNextDataset(): line doesn't fit into data");
                                         aData.Append( aLine );
                                     }
                                     else if( pLine[nLineLength - 1] == '"' )
                                     {
+                                        OSL_ENSURE( nLineLength - 1 <= STRING_MAXLEN - aData.Len(), "GetNextDataset(): line doesn't fit into data");
                                         aData.Append( pLine, nLineLength - 1 );
                                         lcl_DeEscapeQuotesDif( aData );
                                         eRet = D_STRING;
diff --git a/sc/source/filter/inc/dif.hxx b/sc/source/filter/inc/dif.hxx
index 374ea301b976..2e1ca38ba672 100644
--- a/sc/source/filter/inc/dif.hxx
+++ b/sc/source/filter/inc/dif.hxx
@@ -32,6 +32,7 @@
 #include <boost/ptr_container/ptr_vector.hpp>
 
 #include <tools/string.hxx>
+#include <rtl/ustring.hxx>
 
 #include "address.hxx"
 #include "global.hxx"
@@ -80,9 +81,9 @@ private:
     SvNumberFormatter*  pNumFormatter;
     SvStream&           rIn;
     sal_Bool                bPlain;
-    String              aLookAheadLine;
+    rtl::OUString       aLookAheadLine;
 
-    bool                ReadNextLine( String& rStr );
+    bool                ReadNextLine( rtl::OUString& rStr );
     bool                LookAhead();
     DATASET             GetNumberDataset( const sal_Unicode* pPossibleNumericData );
     static inline sal_Bool  IsBOT( const sal_Unicode* pRef );
diff --git a/sc/source/ui/dbgui/asciiopt.cxx b/sc/source/ui/dbgui/asciiopt.cxx
index 60e0db4c185a..0b6ce50e4527 100644
--- a/sc/source/ui/dbgui/asciiopt.cxx
+++ b/sc/source/ui/dbgui/asciiopt.cxx
@@ -81,7 +81,7 @@ ScAsciiOptions::ScAsciiOptions(const ScAsciiOptions& rOpt) :
 {
     if (nInfoCount)
     {
-        pColStart = new xub_StrLen[nInfoCount];
+        pColStart = new sal_Int32[nInfoCount];
         pColFormat = new sal_uInt8[nInfoCount];
         for (sal_uInt16 i=0; i<nInfoCount; i++)
         {
@@ -104,7 +104,7 @@ ScAsciiOptions::~ScAsciiOptions()
 }
 
 
-void ScAsciiOptions::SetColInfo( sal_uInt16 nCount, const xub_StrLen* pStart, const sal_uInt8* pFormat )
+void ScAsciiOptions::SetColInfo( sal_uInt16 nCount, const sal_Int32* pStart, const sal_uInt8* pFormat )
 {
     delete[] pColStart;
     delete[] pColFormat;
@@ -113,7 +113,7 @@ void ScAsciiOptions::SetColInfo( sal_uInt16 nCount, const xub_StrLen* pStart, co
 
     if (nInfoCount)
     {
-        pColStart = new xub_StrLen[nInfoCount];
+        pColStart = new sal_Int32[nInfoCount];
         pColFormat = new sal_uInt8[nInfoCount];
         for (sal_uInt16 i=0; i<nInfoCount; i++)
         {
@@ -139,7 +139,7 @@ void ScAsciiOptions::SetColumnInfo( const ScCsvExpDataVec& rDataVec )
     nInfoCount = static_cast< sal_uInt16 >( rDataVec.size() );
     if( nInfoCount )
     {
-        pColStart = new xub_StrLen[ nInfoCount ];
+        pColStart = new sal_Int32[ nInfoCount ];
         pColFormat = new sal_uInt8[ nInfoCount ];
         for( sal_uInt16 nIx = 0; nIx < nInfoCount; ++nIx )
         {
@@ -276,11 +276,11 @@ void ScAsciiOptions::ReadFromString( const String& rString )
         nInfoCount = nSub / 2;
         if (nInfoCount)
         {
-            pColStart = new xub_StrLen[nInfoCount];
+            pColStart = new sal_Int32[nInfoCount];
             pColFormat = new sal_uInt8[nInfoCount];
             for (sal_uInt16 nInfo=0; nInfo<nInfoCount; nInfo++)
             {
-                pColStart[nInfo]  = (xub_StrLen) aToken.GetToken( 2*nInfo, '/' ).ToInt32();
+                pColStart[nInfo]  = (sal_Int32) aToken.GetToken( 2*nInfo, '/' ).ToInt32();
                 pColFormat[nInfo] = (sal_uInt8) aToken.GetToken( 2*nInfo+1, '/' ).ToInt32();
             }
         }
diff --git a/sc/source/ui/dbgui/csvgrid.cxx b/sc/source/ui/dbgui/csvgrid.cxx
index 83cbad623b6d..09d3651e6fde 100644
--- a/sc/source/ui/dbgui/csvgrid.cxx
+++ b/sc/source/ui/dbgui/csvgrid.cxx
@@ -537,7 +537,7 @@ void ScCsvGrid::FillColumnDataSep( ScAsciiOptions& rOptions ) const
         if( GetColumnType( nColIx ) != CSV_TYPE_DEFAULT )
             // 1-based column index
             aDataVec.push_back( ScCsvExpData(
-                static_cast< xub_StrLen >( nColIx + 1 ),
+                static_cast< sal_Int32 >( nColIx + 1 ),
                 lcl_GetExtColumnType( GetColumnType( nColIx ) ) ) );
     }
     rOptions.SetColumnInfo( aDataVec );
@@ -551,11 +551,10 @@ void ScCsvGrid::FillColumnDataFix( ScAsciiOptions& rOptions ) const
     for( sal_uInt32 nColIx = 0; nColIx < nCount; ++nColIx )
     {
         ScCsvExpData& rData = aDataVec[ nColIx ];
-        rData.mnIndex = static_cast< xub_StrLen >(
-            Min( static_cast< sal_Int32 >( STRING_MAXLEN ), GetColumnPos( nColIx ) ) );
+        rData.mnIndex = static_cast< sal_Int32 >( GetColumnPos( nColIx ) );
         rData.mnType = lcl_GetExtColumnType( GetColumnType( nColIx ) );
     }
-    aDataVec[ nCount ].mnIndex = STRING_MAXLEN;
+    aDataVec[ nCount ].mnIndex = SAL_MAX_INT32;
     aDataVec[ nCount ].mnType = SC_COL_SKIP;
     rOptions.SetColumnInfo( aDataVec );
 }
@@ -730,7 +729,7 @@ void ScCsvGrid::DoSelectAction( sal_uInt32 nColIndex, sal_uInt16 nModifier )
 // cell contents --------------------------------------------------------------
 
 void ScCsvGrid::ImplSetTextLineSep(
-        sal_Int32 nLine, const String& rTextLine,
+        sal_Int32 nLine, const rtl::OUString& rTextLine,
         const String& rSepChars, sal_Unicode cTextSep, bool bMergeSep )
 {
     if( nLine < GetFirstVisLine() ) return;
@@ -744,7 +743,7 @@ void ScCsvGrid::ImplSetTextLineSep(
     // scan for separators
     String aCellText;
     const sal_Unicode* pSepChars = rSepChars.GetBuffer();
-    const sal_Unicode* pChar = rTextLine.GetBuffer();
+    const sal_Unicode* pChar = rTextLine.getStr();
     sal_uInt32 nColIx = 0;
 
     while( *pChar && (nColIx < sal::static_int_cast<sal_uInt32>(CSV_MAXCOLCOUNT)) )
@@ -787,11 +786,11 @@ void ScCsvGrid::ImplSetTextLineSep(
     InvalidateGfx();
 }
 
-void ScCsvGrid::ImplSetTextLineFix( sal_Int32 nLine, const String& rTextLine )
+void ScCsvGrid::ImplSetTextLineFix( sal_Int32 nLine, const rtl::OUString& rTextLine )
 {
     if( nLine < GetFirstVisLine() ) return;
 
-    sal_Int32 nChars = rTextLine.Len();
+    sal_Int32 nChars = rTextLine.getLength();
     if( nChars > GetPosCount() )
         Execute( CSVCMD_SETPOSCOUNT, nChars );
 
@@ -802,13 +801,13 @@ void ScCsvGrid::ImplSetTextLineFix( sal_Int32 nLine, const String& rTextLine )
     StringVec& rStrVec = maTexts[ nLineIx ];
     rStrVec.clear();
     sal_uInt32 nColCount = GetColumnCount();
-    xub_StrLen nStrLen = rTextLine.Len();
-    xub_StrLen nStrIx = 0;
+    sal_Int32 nStrLen = rTextLine.getLength();
+    sal_Int32 nStrIx = 0;
     for( sal_uInt32 nColIx = 0; (nColIx < nColCount) && (nStrIx < nStrLen); ++nColIx )
     {
-        xub_StrLen nColWidth = static_cast< xub_StrLen >( GetColumnWidth( nColIx ) );
-        rStrVec.push_back( rTextLine.Copy( nStrIx, Max( nColWidth, CSV_MAXSTRLEN ) ) );
-        nStrIx = sal::static_int_cast<xub_StrLen>( nStrIx + nColWidth );
+        sal_Int32 nColWidth = GetColumnWidth( nColIx );
+        rStrVec.push_back( rTextLine.copy( nStrIx, Max( nColWidth, static_cast<sal_Int32>(CSV_MAXSTRLEN) ) ) );
+        nStrIx = nStrIx + nColWidth;
     }
     InvalidateGfx();
 }
diff --git a/sc/source/ui/dbgui/csvtablebox.cxx b/sc/source/ui/dbgui/csvtablebox.cxx
index 74777a09021a..bb55aec394ec 100644
--- a/sc/source/ui/dbgui/csvtablebox.cxx
+++ b/sc/source/ui/dbgui/csvtablebox.cxx
@@ -191,14 +191,14 @@ void ScCsvTableBox::MakePosVisible( sal_Int32 nPos )
 // cell contents --------------------------------------------------------------
 
 void ScCsvTableBox::SetUniStrings(
-        const String* pTextLines, const String& rSepChars,
+        const rtl::OUString* pTextLines, const String& rSepChars,
         sal_Unicode cTextSep, bool bMergeSep )
 {
     // assuming that pTextLines is a string array with size CSV_PREVIEW_LINES
     // -> will be dynamic sometime
     DisableRepaint();
     sal_Int32 nEndLine = GetFirstVisLine() + CSV_PREVIEW_LINES;
-    const String* pString = pTextLines;
+    const rtl::OUString* pString = pTextLines;
     for( sal_Int32 nLine = GetFirstVisLine(); nLine < nEndLine; ++nLine, ++pString )
     {
         if( mbFixedMode )
diff --git a/sc/source/ui/dbgui/scuiasciiopt.cxx b/sc/source/ui/dbgui/scuiasciiopt.cxx
index fefb2557677e..11b2bb3533d8 100644
--- a/sc/source/ui/dbgui/scuiasciiopt.cxx
+++ b/sc/source/ui/dbgui/scuiasciiopt.cxx
@@ -441,7 +441,7 @@ ScImportAsciiDlg::~ScImportAsciiDlg()
 
 // ----------------------------------------------------------------------------
 
-bool ScImportAsciiDlg::GetLine( sal_uLong nLine, String &rText )
+bool ScImportAsciiDlg::GetLine( sal_uLong nLine, rtl::OUString &rText )
 {
     if (nLine >= ASCIIDLG_MAXROWS || !mpDatStream)
         return false;
@@ -704,7 +704,7 @@ IMPL_LINK_NOARG(ScImportAsciiDlg, UpdateTextHdl)
             break;
     }
     for (; i < CSV_PREVIEW_LINES; i++)
-        maPreviewLine[i].Erase();
+        maPreviewLine[i] = rtl::OUString();
 
     maTableBox.Execute( CSVCMD_SETLINECOUNT, mnRowPosCount);
     bool bMergeSep = (aCkbAsOnce.IsChecked() == sal_True);
diff --git a/sc/source/ui/docshell/impex.cxx b/sc/source/ui/docshell/impex.cxx
index eecae51acbfd..418eda7ac728 100644
--- a/sc/source/ui/docshell/impex.cxx
+++ b/sc/source/ui/docshell/impex.cxx
@@ -87,6 +87,13 @@ class StarBASIC;
 
 //========================================================================
 
+// We don't want to end up with 2GB read in one line just because of malformed
+// multiline fields, so chop it _somewhere_, which is twice supported columns
+// times maximum cell content length, 2*1024*64K=128M, and because it's
+// sal_Unicode that's 256MB. If it's 2GB of data without LF we're out of luck
+// anyway.
+static const sal_Int32 nArbitraryLineLengthLimit = 2 * MAXCOLCOUNT * STRING_MAXLEN;
+
 namespace
 {
     const char SYLK_LF[]  = "\x1b :";
@@ -562,6 +569,30 @@ void ScImportExport::WriteUnicodeOrByteEndl( SvStream& rStrm )
 }
 
 
+/** Append characters of [p1,p2) to rField.
+
+    @returns TRUE if ok; FALSE if data overflow, truncated
+ */
+static bool lcl_appendLineData( String& rField, const sal_Unicode* p1, const sal_Unicode* p2 )
+{
+    OSL_ENSURE( rField.Len() + (p2 - p1) <= STRING_MAXLEN, "lcl_appendLineData: data overflow");
+    if (rField.Len() + (p2 - p1) <= STRING_MAXLEN)
+    {
+        rField.Append( p1, sal::static_int_cast<xub_StrLen>( p2 - p1 ) );
+        return true;
+    }
+    else
+    {
+        // If STRING_MAXLEN is passed as length, then String attempts to
+        // determine the length of the string and comes up with an overflow
+        // casted to xub_StrLen again ... so pass max-1, data will be truncated
+        // anyway.
+        rField.Append( p1, (rField.Len() ? STRING_MAXLEN - rField.Len() : STRING_MAXLEN - 1) );
+        return false;
+    }
+}
+
+
 enum DoubledQuoteMode
 {
     DQM_KEEP,       // both are taken
@@ -613,7 +644,12 @@ static const sal_Unicode* lcl_ScanString( const sal_Unicode* p, String& rString,
                 p++;
         }
         if ( p0 < p )
-            rString.Append( p0, sal::static_int_cast<xub_StrLen>( ((*p || *(p-1) == cStr) ? p-1 : p) - p0 ) );
+        {
+            if (!lcl_appendLineData( rString, p0, ((*p || *(p-1) == cStr) ? p-1 : p)))
+            {
+                /* TODO: warning at UI, data truncated */
+            }
+        }
     } while ( bCont );
     return p;
 }
@@ -785,16 +821,17 @@ sal_Bool ScImportExport::Text2Doc( SvStream& rStrm )
 
     while( bOk )
     {
-        String aLine, aCell;
+        rtl::OUString aLine;
+        String aCell;
         SCROW nRow = nStartRow;
         rStrm.Seek( nOldPos );
         for( ;; )
         {
-            rStrm.ReadUniOrByteStringLine( aLine, rStrm.GetStreamCharSet() );
+            rStrm.ReadUniOrByteStringLine( aLine, rStrm.GetStreamCharSet(), nArbitraryLineLengthLimit );
             if( rStrm.IsEof() )
                 break;
             SCCOL nCol = nStartCol;
-            const sal_Unicode* p = aLine.GetBuffer();
+            const sal_Unicode* p = aLine.getStr();
             while( *p )
             {
                 aCell.Erase();
@@ -811,7 +848,10 @@ sal_Bool ScImportExport::Text2Doc( SvStream& rStrm )
                     const sal_Unicode* q = p;
                     while( *p && *p != cSep )
                         p++;
-                    aCell.Assign( q, sal::static_int_cast<xub_StrLen>( p - q ) );
+                    if (!lcl_appendLineData( aCell, q, p))
+                    {
+                        /* TODO: warning at UI, data truncated */
+                    }
                     if( *p )
                         p++;
                 }
@@ -1104,25 +1144,31 @@ static bool lcl_PutString(
 }
 
 
-String lcl_GetFixed( const String& rLine, xub_StrLen nStart, xub_StrLen nNext, bool& rbIsQuoted )
+String lcl_GetFixed( const rtl::OUString& rLine, sal_Int32 nStart, sal_Int32 nNext, bool& rbIsQuoted )
 {
-    xub_StrLen nLen = rLine.Len();
+    sal_Int32 nLen = rLine.getLength();
     if (nNext > nLen)
         nNext = nLen;
     if ( nNext <= nStart )
         return EMPTY_STRING;
 
-    const sal_Unicode* pStr = rLine.GetBuffer();
+    const sal_Unicode* pStr = rLine.getStr();
 
-    xub_StrLen nSpace = nNext;
+    sal_Int32 nSpace = nNext;
     while ( nSpace > nStart && pStr[nSpace-1] == ' ' )
         --nSpace;
 
     rbIsQuoted = (pStr[nStart] == sal_Unicode('"') && pStr[nSpace-1] == sal_Unicode('"'));
     if (rbIsQuoted)
-        return rLine.Copy(nStart+1, nSpace-nStart-2);
+    {
+        OSL_ENSURE( nSpace - nStart - 3 <= STRING_MAXLEN, "lcl_GetFixed: line doesn't fit into data");
+        return rLine.copy(nStart+1, nSpace-nStart-2);
+    }
     else
-        return rLine.Copy(nStart, nSpace-nStart);
+    {
+        OSL_ENSURE( nSpace - nStart <= STRING_MAXLEN, "lcl_GetFixed: line doesn't fit into data");
+        return rLine.copy(nStart, nSpace-nStart);
+    }
 }
 
 sal_Bool ScImportExport::ExtText2Doc( SvStream& rStrm )
@@ -1144,12 +1190,12 @@ sal_Bool ScImportExport::ExtText2Doc( SvStream& rStrm )
     SCROW nStartRow = aRange.aStart.Row();
     SCTAB nTab = aRange.aStart.Tab();
 
-    sal_Bool    bFixed          = pExtOptions->IsFixedLen();
-    const String& rSeps     = pExtOptions->GetFieldSeps();
-    const sal_Unicode* pSeps = rSeps.GetBuffer();
-    sal_Bool    bMerge          = pExtOptions->IsMergeSeps();
-    sal_uInt16  nInfoCount      = pExtOptions->GetInfoCount();
-    const xub_StrLen* pColStart = pExtOptions->GetColStart();
+    sal_Bool    bFixed           = pExtOptions->IsFixedLen();
+    const String& rSeps          = pExtOptions->GetFieldSeps();
+    const sal_Unicode* pSeps     = rSeps.GetBuffer();
+    sal_Bool    bMerge           = pExtOptions->IsMergeSeps();
+    sal_uInt16  nInfoCount       = pExtOptions->GetInfoCount();
+    const sal_Int32* pColStart   = pExtOptions->GetColStart();
     const sal_uInt8* pColFormat  = pExtOptions->GetColFormat();
     long nSkipLines = pExtOptions->GetStartRow();
 
@@ -1176,7 +1222,8 @@ sal_Bool ScImportExport::ExtText2Doc( SvStream& rStrm )
             MsLangId::convertLanguageToLocale( LANGUAGE_ENGLISH_US ) );
     }
 
-    String aLine, aCell;
+    rtl::OUString aLine;
+    String aCell;
     sal_uInt16 i;
     SCROW nRow = nStartRow;
 
@@ -1209,7 +1256,7 @@ sal_Bool ScImportExport::ExtText2Doc( SvStream& rStrm )
             if ( rStrm.IsEof() )
                 break;
 
-            xub_StrLen nLineLen = aLine.Len();
+            sal_Int32 nLineLen = aLine.getLength();
             SCCOL nCol = nStartCol;
             bool bMultiLine = false;
             if ( bFixed )               //  Feste Satzlaenge
@@ -1227,8 +1274,8 @@ sal_Bool ScImportExport::ExtText2Doc( SvStream& rStrm )
                             bOverflow = sal_True;       // display warning on import
                         else if (!bDetermineRange)
                         {
-                            xub_StrLen nStart = pColStart[i];
-                            xub_StrLen nNext = ( i+1 < nInfoCount ) ? pColStart[i+1] : nLineLen;
+                            sal_Int32 nStart = pColStart[i];
+                            sal_Int32 nNext = ( i+1 < nInfoCount ) ? pColStart[i+1] : nLineLen;
                             bool bIsQuoted = false;
                             aCell = lcl_GetFixed( aLine, nStart, nNext, bIsQuoted );
                             if (bIsQuoted && bQuotedAsText)
@@ -1247,7 +1294,7 @@ sal_Bool ScImportExport::ExtText2Doc( SvStream& rStrm )
             {
                 SCCOL nSourceCol = 0;
                 sal_uInt16 nInfoStart = 0;
-                const sal_Unicode* p = aLine.GetBuffer();
+                const sal_Unicode* p = aLine.getStr();
                 // Yes, the check is nCol<=MAXCOL+1, +1 because it is only an
                 // overflow if there is really data following to be put behind
                 // the last column, which doesn't happen if info is
@@ -1378,7 +1425,12 @@ const sal_Unicode* ScImportExport::ScanNextFieldFromString( const sal_Unicode* p
         // Append remaining unquoted and undelimited data (dirty, dirty) to
         // this field.
         if (p > p1)
-            rField.Append( p1, sal::static_int_cast<xub_StrLen>( p - p1 ) );
+        {
+            if (!lcl_appendLineData( rField, p1, p))
+            {
+                /* TODO: warning at UI, data truncated */
+            }
+        }
         if( *p )
             p++;
     }
@@ -1387,7 +1439,10 @@ const sal_Unicode* ScImportExport::ScanNextFieldFromString( const sal_Unicode* p
         const sal_Unicode* p0 = p;
         while ( *p && !ScGlobal::UnicodeStrChr( pSeps, *p ) )
             p++;
-        rField.Append( p0, sal::static_int_cast<xub_StrLen>( p - p0 ) );
+        if (!lcl_appendLineData( rField, p0, p))
+        {
+            /* TODO: warning at UI, data truncated */
+        }
         if( *p )
             p++;
     }
@@ -2135,12 +2190,12 @@ inline const sal_Unicode* lcl_UnicodeStrChr( const sal_Unicode* pStr,
     return 0;
 }
 
-String ReadCsvLine(SvStream &rStream, sal_Bool bEmbeddedLineBreak,
+rtl::OUString ReadCsvLine(SvStream &rStream, sal_Bool bEmbeddedLineBreak,
         const String& rFieldSeparators, sal_Unicode cFieldQuote,
         sal_Bool bAllowBackslashEscape)
 {
-    String aStr;
-    rStream.ReadUniOrByteStringLine(aStr, rStream.GetStreamCharSet());
+    rtl::OUString aStr;
+    rStream.ReadUniOrByteStringLine(aStr, rStream.GetStreamCharSet(), nArbitraryLineLengthLimit);
 
     if (bEmbeddedLineBreak)
     {
@@ -2149,13 +2204,13 @@ String ReadCsvLine(SvStream &rStream, sal_Bool bEmbeddedLineBreak,
         // See if the separator(s) include tab.
         bool bTabSep = lcl_UnicodeStrChr(pSeps, '\t') != NULL;
 
-        xub_StrLen nLastOffset = 0;
-        xub_StrLen nQuotes = 0;
-        while (!rStream.IsEof() && aStr.Len() < STRING_MAXLEN)
+        sal_Int32 nLastOffset = 0;
+        sal_Int32 nQuotes = 0;
+        while (!rStream.IsEof() && aStr.getLength() < nArbitraryLineLengthLimit)
         {
             bool bBackslashEscaped = false;
             const sal_Unicode *p, *pStart;
-            p = pStart = aStr.GetBuffer();
+            p = pStart = aStr.getStr();
             p += nLastOffset;
             while (*p)
             {
@@ -2193,10 +2248,10 @@ String ReadCsvLine(SvStream &rStream, sal_Bool bEmbeddedLineBreak,
                 break;
             else
             {
-                nLastOffset = aStr.Len();
-                String aNext;
-                rStream.ReadUniOrByteStringLine(aNext, rStream.GetStreamCharSet());
-                aStr += sal_Unicode(_LF);
+                nLastOffset = aStr.getLength();
+                rtl::OUString aNext;
+                rStream.ReadUniOrByteStringLine(aNext, rStream.GetStreamCharSet(), nArbitraryLineLengthLimit);
+                aStr += rtl::OUString( sal_Unicode(_LF));
                 aStr += aNext;
             }
         }
diff --git a/sc/source/ui/inc/asciiopt.hxx b/sc/source/ui/inc/asciiopt.hxx
index 7fb3c937538d..53a22dd6dec5 100644
--- a/sc/source/ui/inc/asciiopt.hxx
+++ b/sc/source/ui/inc/asciiopt.hxx
@@ -59,7 +59,7 @@ private:
     sal_Bool        bCharSetSystem;
     long        nStartRow;
     sal_uInt16      nInfoCount;
-    xub_StrLen* pColStart;  //! TODO replace with vector
+    sal_Int32* pColStart;  //! TODO replace with vector
     sal_uInt8*       pColFormat; //! TODO replace with vector
 
 public:
@@ -87,7 +87,7 @@ public:
     sal_Unicode         GetTextSep() const      { return cTextSep; }
     sal_Bool                IsFixedLen() const      { return bFixedLen; }
     sal_uInt16              GetInfoCount() const    { return nInfoCount; }
-    const xub_StrLen*   GetColStart() const     { return pColStart; }
+    const sal_Int32*   GetColStart() const     { return pColStart; }
     const sal_uInt8*            GetColFormat() const    { return pColFormat; }
     long                GetStartRow() const     { return nStartRow; }
     LanguageType        GetLanguage() const     { return eLang; }
@@ -103,7 +103,7 @@ public:
     void    SetStartRow( long nRow)             { nStartRow= nRow; }
     void    SetLanguage(LanguageType e)         { eLang = e; }
 
-    void    SetColInfo( sal_uInt16 nCount, const xub_StrLen* pStart, const sal_uInt8* pFormat );
+    void    SetColInfo( sal_uInt16 nCount, const sal_Int32* pStart, const sal_uInt8* pFormat );
     void    SetColumnInfo( const ScCsvExpDataVec& rDataVec );
 };
 
diff --git a/sc/source/ui/inc/csvcontrol.hxx b/sc/source/ui/inc/csvcontrol.hxx
index 68a97150e8e4..6a47b677ba14 100644
--- a/sc/source/ui/inc/csvcontrol.hxx
+++ b/sc/source/ui/inc/csvcontrol.hxx
@@ -83,7 +83,7 @@ const sal_uInt8 SC_COL_ENGLISH          = 10;
 /** Exported data of a column (data used in the dialog). */
 struct ScCsvExpData
 {
-    xub_StrLen                  mnIndex;        /// Index of a column.
+    sal_Int32                   mnIndex;        /// Index of a column.
     sal_uInt8                   mnType;         /// External type of the column.
 
     inline                      ScCsvExpData() : mnIndex( 0 ), mnType( SC_COL_STANDARD ) {}
diff --git a/sc/source/ui/inc/csvgrid.hxx b/sc/source/ui/inc/csvgrid.hxx
index acb21731528e..8056943a1ce0 100644
--- a/sc/source/ui/inc/csvgrid.hxx
+++ b/sc/source/ui/inc/csvgrid.hxx
@@ -277,10 +277,10 @@ private:
 public:
     /** Fills all cells of a line with the passed text (separators mode). */
     void                        ImplSetTextLineSep(
-                                    sal_Int32 nLine, const String& rTextLine,
+                                    sal_Int32 nLine, const rtl::OUString& rTextLine,
                                     const String& rSepChars, sal_Unicode cTextSep, bool bMergeSep );
     /** Fills all cells of a line with the passed text (fixed width mode). */
-    void                        ImplSetTextLineFix( sal_Int32 nLine, const String& rTextLine );
+    void                        ImplSetTextLineFix( sal_Int32 nLine, const rtl::OUString& rTextLine );
 
     /** Returns the text of the specified cell. */
     const String&               GetCellText( sal_uInt32 nColIndex, sal_Int32 nLine ) const;
diff --git a/sc/source/ui/inc/csvtablebox.hxx b/sc/source/ui/inc/csvtablebox.hxx
index 22bb380e38c2..68f7e7efe7c2 100644
--- a/sc/source/ui/inc/csvtablebox.hxx
+++ b/sc/source/ui/inc/csvtablebox.hxx
@@ -108,7 +108,7 @@ private:
 public:
     /** Fills all cells of all lines with the passed texts (Unicode strings). */
     void                        SetUniStrings(
-                                    const String* pTextLines, const String& rSepChars,
+                                    const rtl::OUString* pTextLines, const String& rSepChars,
                                     sal_Unicode cTextSep, bool bMergeSep );
 
     // column settings --------------------------------------------------------
diff --git a/sc/source/ui/inc/impex.hxx b/sc/source/ui/inc/impex.hxx
index 51bd610aaa1c..aaaebac17853 100644
--- a/sc/source/ui/inc/impex.hxx
+++ b/sc/source/ui/inc/impex.hxx
@@ -225,8 +225,8 @@ public:
 
     @ATTENTION
     Note that the string returned may be truncated even inside
-    a quoted field if STRING_MAXLEN was reached. There
-    currently is no way to exactly determine the conditions,
+    a quoted field if some (arbritary) maximum length was reached.
+    There currently is no way to exactly determine the conditions,
     whether this was at a line end, or whether open quotes
     would have closed the field before the line end, as even a
     ReadUniOrByteStringLine() may return prematurely but the
@@ -235,11 +235,12 @@ public:
     length and bytes read don't necessarily match, and
     resyncing to a previous position matching the string's
     length isn't always possible. As a result, a logical line
-    with embedded line breaks and more than STRING_MAXLEN
+    with embedded line breaks and more than the maximum length
     characters will be spoiled, and a subsequent ReadCsvLine()
     may start under false preconditions.
+
   */
-SC_DLLPUBLIC String ReadCsvLine(SvStream &rStream, sal_Bool bEmbeddedLineBreak,
+SC_DLLPUBLIC rtl::OUString ReadCsvLine(SvStream &rStream, sal_Bool bEmbeddedLineBreak,
         const String& rFieldSeparators, sal_Unicode cFieldQuote,
         sal_Bool bAllowBackslashEscape = sal_False);
 
diff --git a/sc/source/ui/inc/scuiasciiopt.hxx b/sc/source/ui/inc/scuiasciiopt.hxx
index c07f6f4f10c8..c45b9acd1d08 100644
--- a/sc/source/ui/inc/scuiasciiopt.hxx
+++ b/sc/source/ui/inc/scuiasciiopt.hxx
@@ -44,7 +44,7 @@ class ScImportAsciiDlg : public ModalDialog
     sal_uLong*                      mpRowPosArray;
     sal_uLong                       mnRowPosCount;
 
-    String                      maPreviewLine[ CSV_PREVIEW_LINES ];
+    rtl::OUString               maPreviewLine[ CSV_PREVIEW_LINES ];
 
     FixedLine                   aFlFieldOpt;
     FixedText                   aFtCharSet;
@@ -116,7 +116,7 @@ private:
     void                        SetupSeparatorCtrls();
 
 
-    bool                        GetLine( sal_uLong nLine, String &rText );
+    bool                        GetLine( sal_uLong nLine, rtl::OUString &rText );
     void                        UpdateVertical();
     inline bool                 Seek( sal_uLong nPos ); // synced to and from mnStreamPos
 
diff --git a/sc/source/ui/vba/vbarange.cxx b/sc/source/ui/vba/vbarange.cxx
index 27de1e8bf5da..def7b63bc360 100644
--- a/sc/source/ui/vba/vbarange.cxx
+++ b/sc/source/ui/vba/vbarange.cxx
@@ -4996,12 +4996,12 @@ ScVbaRange::TextToColumns( const css::uno::Any& Destination, const css::uno::Any
 
     // Parse the value of parameter FieldInfo.
     sal_uInt16 nRealCount = 0;
-    xub_StrLen* pColumns = NULL;
+    sal_Int32* pColumns = NULL;
     sal_uInt8* pFormats = NULL;
     if ( sFieldInfo.getLength() > 0 )
     {
         sal_uInt16 nCount = sFieldInfo.getLength();
-        pColumns = new xub_StrLen[nCount];
+        pColumns = new sal_Int32[nCount];
         pFormats = new sal_uInt8[nCount];
         sal_uInt16 nFormat = 1;
         uno::Reference< script::XTypeConverter > xConverter = getTypeConverter( mxContext );
@@ -5012,7 +5012,7 @@ ScVbaRange::TextToColumns( const css::uno::Any& Destination, const css::uno::Any
                 nFormat = 1;
                 try
                 {
-                    uno::Any aConverted = xConverter->convertTo( sFieldInfo[nIndex][0], getCppuType((xub_StrLen*)0) );
+                    uno::Any aConverted = xConverter->convertTo( sFieldInfo[nIndex][0], getCppuType((sal_Int32*)0) );
                     aConverted >>= pColumns[nRealCount];
                     aConverted = xConverter->convertTo( sFieldInfo[nIndex][1], getCppuType((sal_uInt16*)0) );
                     aConverted >>= nFormat;
diff --git a/tools/inc/tools/stream.hxx b/tools/inc/tools/stream.hxx
index 5b5c443ac354..dc4505a06a35 100644
--- a/tools/inc/tools/stream.hxx
+++ b/tools/inc/tools/stream.hxx
@@ -380,9 +380,37 @@ public:
     // next Tell() <= nSize
     sal_Bool        SetStreamSize( sal_Size nSize );
 
-    sal_Bool        ReadLine( rtl::OString& rStr );
+                /** Read a line of bytes.
+
+                    @param nMaxBytesToRead
+                        Maximum of bytes to read, if line is longer it will be
+                        truncated.
+
+                        NOTE that the default is one character less than
+                        STRING_MAXLEN to prevent problems after conversion to
+                        String that may be lurking in various places doing
+                        something like
+                        for (sal_uInt16 i=0; i < aString.Len(); ++i)
+                        causing endless loops ...
+                 */
+    sal_Bool        ReadLine( rtl::OString& rStr, sal_Int32 nMaxBytesToRead = 0xFFFE );
     sal_Bool        WriteLine( const rtl::OString& rStr );
 
+                /** Read a line of bytes.
+
+                    @param nMaxBytesToRead
+                        Maximum of bytes to read, if line is longer it will be
+                        truncated.
+
+                        NOTE that the default is one character less than
+                        STRING_MAXLEN to prevent problems after conversion to
+                        String that may be lurking in various places doing
+                        something like
+                        for (sal_uInt16 i=0; i < aString.Len(); ++i)
+                        causing endless loops ...
+                 */
+    sal_Bool        ReadByteStringLine( rtl::OUString& rStr, rtl_TextEncoding eSrcCharSet,
+                                        sal_Int32 nMaxBytesToRead = 0xFFFE );
     sal_Bool        ReadByteStringLine( String& rStr, rtl_TextEncoding eSrcCharSet );
     sal_Bool        WriteByteStringLine( const String& rStr, rtl_TextEncoding eDestCharSet );
 
@@ -403,17 +431,44 @@ public:
                  */
     sal_Bool        StartReadingUnicodeText( rtl_TextEncoding eReadBomCharSet );
 
-                /// Read a line of Unicode
-    sal_Bool        ReadUniStringLine( String& rStr );
+                /** Read a line of Unicode.
+
+                    @param nMaxCodepointsToRead
+                        Maximum of codepoints (UCS-2 or UTF-16 pairs, not
+                        bytes) to read, if line is longer it will be truncated.
+
+                        NOTE that the default is one character less than
+                        STRING_MAXLEN to prevent problems after conversion to
+                        String that may be lurking in various places doing
+                        something like
+                        for (sal_uInt16 i=0; i < aString.Len(); ++i)
+                        causing endless loops ...
+                 */
+    sal_Bool        ReadUniStringLine( rtl::OUString& rStr, sal_Int32 nMaxCodepointsToRead = 0xFFFE );
                 /// Read a 32bit length prefixed sequence of utf-16 if eSrcCharSet==RTL_TEXTENCODING_UNICODE,
                 /// otherwise read a 16bit length prefixed sequence of bytes and convert from eSrcCharSet
     rtl::OUString   ReadUniOrByteString(rtl_TextEncoding eSrcCharSet);
                 /// Write a 32bit length prefixed sequence of utf-16 if eSrcCharSet==RTL_TEXTENCODING_UNICODE,
                 /// otherwise convert to eSrcCharSet and write a 16bit length prefixed sequence of bytes
     SvStream&       WriteUniOrByteString( const rtl::OUString& rStr, rtl_TextEncoding eDestCharSet );
-                /// Read a line of Unicode if eSrcCharSet==RTL_TEXTENCODING_UNICODE,
-                /// otherwise read a line of Bytecode and convert from eSrcCharSet
-    sal_Bool        ReadUniOrByteStringLine( String& rStr, rtl_TextEncoding eSrcCharSet );
+
+                /** Read a line of Unicode if eSrcCharSet==RTL_TEXTENCODING_UNICODE,
+                    otherwise read a line of Bytecode and convert from eSrcCharSet
+
+                    @param nMaxCodepointsToRead
+                        Maximum of codepoints (2 bytes if Unicode, bytes if not
+                        Unicode) to read, if line is longer it will be
+                        truncated.
+
+                        NOTE that the default is one character less than
+                        STRING_MAXLEN to prevent problems after conversion to
+                        String that may be lurking in various places doing
+                        something like
+                        for (sal_uInt16 i=0; i < aString.Len(); ++i)
+                        causing endless loops ...
+                 */
+    sal_Bool        ReadUniOrByteStringLine( rtl::OUString& rStr, rtl_TextEncoding eSrcCharSet,
+                                             sal_Int32 nMaxCodepointsToRead = 0xFFFE );
                 /// Write a sequence of Unicode characters if eDestCharSet==RTL_TEXTENCODING_UNICODE,
                 /// otherwise write a sequence of Bytecodes converted to eDestCharSet
     sal_Bool        WriteUnicodeOrByteText( const String& rStr, rtl_TextEncoding eDestCharSet );
diff --git a/tools/source/stream/stream.cxx b/tools/source/stream/stream.cxx
index 1da4096a92c7..96cabc266c34 100644
--- a/tools/source/stream/stream.cxx
+++ b/tools/source/stream/stream.cxx
@@ -647,6 +647,15 @@ void SvStream::ResetError()
 |*
 *************************************************************************/
 
+sal_Bool SvStream::ReadByteStringLine( rtl::OUString& rStr, rtl_TextEncoding eSrcCharSet,
+                                       sal_Int32 nMaxBytesToRead )
+{
+    rtl::OString aStr;
+    sal_Bool bRet = ReadLine( aStr, nMaxBytesToRead);
+    rStr = rtl::OStringToOUString(aStr, eSrcCharSet);
+    return bRet;
+}
+
 sal_Bool SvStream::ReadByteStringLine( String& rStr, rtl_TextEncoding eSrcCharSet )
 {
     rtl::OString aStr;
@@ -655,7 +664,7 @@ sal_Bool SvStream::ReadByteStringLine( String& rStr, rtl_TextEncoding eSrcCharSe
     return bRet;
 }
 
-sal_Bool SvStream::ReadLine(rtl::OString& rStr)
+sal_Bool SvStream::ReadLine( rtl::OString& rStr, sal_Int32 nMaxBytesToRead )
 {
     sal_Char    buf[256+1];
     sal_Bool        bEnd        = sal_False;
@@ -663,7 +672,7 @@ sal_Bool SvStream::ReadLine(rtl::OString& rStr)
     sal_Char    c           = 0;
     sal_Size       nTotalLen   = 0;
 
-    rtl::OStringBuffer aBuf;
+    rtl::OStringBuffer aBuf(4096);
     while( !bEnd && !GetError() )   // !!! nicht auf EOF testen,
                                     // !!! weil wir blockweise
                                     // !!! lesen
@@ -695,8 +704,15 @@ sal_Bool SvStream::ReadLine(rtl::OString& rStr)
                 buf[n] = c;
             ++n;
         }
-        aBuf.append(buf, n);
         nTotalLen += j;
+        if (nTotalLen > static_cast<sal_Size>(nMaxBytesToRead))
+        {
+            n -= nTotalLen - nMaxBytesToRead;
+            nTotalLen = nMaxBytesToRead;
+            bEnd = sal_True;
+        }
+        if ( n )
+            aBuf.append(buf, n);
     }
 
     if ( !bEnd && !GetError() && aBuf.getLength() )
@@ -723,7 +739,7 @@ sal_Bool SvStream::ReadLine(rtl::OString& rStr)
     return bEnd;
 }
 
-sal_Bool SvStream::ReadUniStringLine( String& rStr )
+sal_Bool SvStream::ReadUniStringLine( rtl::OUString& rStr, sal_Int32 nMaxCodepointsToRead )
 {
     sal_Unicode buf[256+1];
     sal_Bool        bEnd        = sal_False;
@@ -733,7 +749,7 @@ sal_Bool SvStream::ReadUniStringLine( String& rStr )
 
     DBG_ASSERT( sizeof(sal_Unicode) == sizeof(sal_uInt16), "ReadUniStringLine: swapping sizeof(sal_Unicode) not implemented" );
 
-    rStr.Erase();
+    rtl::OUStringBuffer aBuf(4096);
     while( !bEnd && !GetError() )   // !!! nicht auf EOF testen,
                                     // !!! weil wir blockweise
                                     // !!! lesen
@@ -742,10 +758,11 @@ sal_Bool SvStream::ReadUniStringLine( String& rStr )
         nLen /= sizeof(sal_Unicode);
         if ( !nLen )
         {
-            if ( rStr.Len() == 0 )
+            if ( aBuf.getLength() == 0 )
             {
                 // der allererste Blockread hat fehlgeschlagen -> Abflug
                 bIsEof = sal_True;
+                rStr = rtl::OUString();
                 return sal_False;
             }
             else
@@ -774,12 +791,18 @@ sal_Bool SvStream::ReadUniStringLine( String& rStr )
                 ++n;
             }
         }
-        if ( n )
-            rStr.Append( buf, n );
         nTotalLen += j;
+        if (nTotalLen > static_cast<sal_Size>(nMaxCodepointsToRead))
+        {
+            n -= nTotalLen - nMaxCodepointsToRead;
+            nTotalLen = nMaxCodepointsToRead;
+            bEnd = sal_True;
+        }
+        if ( n )
+            aBuf.append( buf, n );
     }
 
-    if ( !bEnd && !GetError() && rStr.Len() )
+    if ( !bEnd && !GetError() && aBuf.getLength() )
         bEnd = sal_True;
 
     nOldFilePos += nTotalLen * sizeof(sal_Unicode);
@@ -799,20 +822,22 @@ sal_Bool SvStream::ReadUniStringLine( String& rStr )
 
     if ( bEnd )
         bIsEof = sal_False;
+    rStr = aBuf.makeStringAndClear();
     return bEnd;
 }
 
-sal_Bool SvStream::ReadUniOrByteStringLine( String& rStr, rtl_TextEncoding eSrcCharSet )
+sal_Bool SvStream::ReadUniOrByteStringLine( rtl::OUString& rStr, rtl_TextEncoding eSrcCharSet,
+                                            sal_Int32 nMaxCodepointsToRead )
 {
     if ( eSrcCharSet == RTL_TEXTENCODING_UNICODE )
-        return ReadUniStringLine( rStr );
+        return ReadUniStringLine( rStr, nMaxCodepointsToRead );
     else
-        return ReadByteStringLine( rStr, eSrcCharSet );
+        return ReadByteStringLine( rStr, eSrcCharSet, nMaxCodepointsToRead );
 }
 
 rtl::OString read_zeroTerminated_uInt8s_ToOString(SvStream& rStream)
 {
-    rtl::OStringBuffer aOutput;
+    rtl::OStringBuffer aOutput(256);
 
     sal_Char buf[ 256 + 1 ];
     sal_Bool bEnd = sal_False;