tdf#108821 - fix for overflow of variables on opening huge files

This should fix the issue, as well as restrict available
to return only non-negative values.

Change-Id: I198e226e945b9bd79dec32b1686c20e2a8dfaf3e
Reviewed-on: https://gerrit.libreoffice.org/39665Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Jenkins <ci@libreoffice.org>

package/source/zipapi/XBufferedThreadedStream.cxx

@@ -145,7 +145,7 @@ sal_Int32 SAL_CALL XBufferedThreadedStream::readBytes( Sequence< sal_Int8 >& rDa
     if( !hasBytes() )
         return 0;
 
-    const sal_Int32 nAvailableSize = std::min<sal_Int32>( nBytesToRead, remainingSize() );
+    const sal_Int32 nAvailableSize = static_cast< sal_Int32 > ( std::min< sal_Int64 >( nBytesToRead, remainingSize() ) );
     rData.realloc( nAvailableSize );
     sal_Int32 i = 0, nPendingBytes = nAvailableSize;
 
@@ -188,7 +188,7 @@ sal_Int32 SAL_CALL XBufferedThreadedStream::available()
     if( !hasBytes() )
         return 0;
 
-    return remainingSize();
+    return static_cast< sal_Int32 > ( std::min< sal_Int64 >( SAL_MAX_INT32, remainingSize() ) );
 }
 
 void SAL_CALL XBufferedThreadedStream::closeInput()

package/source/zipapi/XBufferedThreadedStream.hxx

@@ -44,7 +44,7 @@ private:
     static const size_t nBufferSize = 32 * 1024;
 
     const Buffer& getNextBlock();
-    size_t remainingSize() const { return mnStreamSize - mnPos; }
+    sal_Int64 remainingSize() const { return mnStreamSize - mnPos; }
     bool hasBytes() const { return mnPos < mnStreamSize; }
 
     bool canProduce() const

package/source/zipapi/XUnbufferedStream.cxx

@@ -310,7 +310,7 @@ void SAL_CALL XUnbufferedStream::skipBytes( sal_Int32 nBytesToSkip )
 sal_Int32 SAL_CALL XUnbufferedStream::available(  )
 {
     //available size must include the prepended header in case of wrapped raw stream
-    return static_cast < sal_Int32 > ( mnZipSize + mnHeaderToRead - mnMyCurrent );
+    return static_cast< sal_Int32 > ( std::min< sal_Int64 >( SAL_MAX_INT32, (mnZipSize + mnHeaderToRead - mnMyCurrent) ) );
 }
 
 void SAL_CALL XUnbufferedStream::closeInput(  )