GetFileSizeEx is needed for 64bit files. I may have to make two releases to 
solve
this. I'll investigate.

I think the 64-bit-filesize problem is definitely not relevant when working 
with 
files on the local file system on Win9x since the FAT32 file system only 
supports 
files up to 4 GB in size.
I wonder whether Win9x supports larger file sizes when working with network 
files...

Under WinXP I could get GetFileSize() to return the correct 64-bit filesize of 
a 6 
GB file by using the following code:
__int64 size;
DWORD sizeHigh, sizeLow;
sizeLow = ::GetFileSize( hFile, &sizeHigh );
size = ( __int64( sizeHigh ) << 32 ) | __int64(sizeLow);

Let me know if this installer solves the problem for you:

http://code.google.com/p/xdelta/downloads/detail?name=xdelta30q.msi

Statically linked:
http://code.google.com/p/xdelta/downloads/detail?name=xdelta3q.1.msi

Still missing the following DLL-Imports under Win98: GetFileSizeEx, 
SetFilePointerEx.
GetFileSizeEx could be replaced by GetFileSize and SetFilePointerEx by 
SetFilePointer - but only GetFileSize supports 64-bit file sizes (for network 
files). So I think there is no way to process 64-bit files under Win9x.
I wonder whether there really is a need for xdelta to support large files under 
these old systems.

OK -- leaving this issue open.  I want to avoid using different function 
signatures
in different builds, we'll see if that's possible.

Maybe my last comment was a bit unclear. Both GetFileSize() and 
SetFilePointer() are 
documented to work with 64-bit file sizes and are available for all Win32 OS.
The only exception is that the Win9x family (Windows Me/98/95) does not support 
64-
bit offsets for SetFilePointer(). 

I see, so we can't do a 64bit seek on Windows98.

In fact the encoder does not seek so it can be fixed, but the decoder may be 
forced
to seek if it is configured w/ less memory than the encoder was.

I would like to fix this so that < 2GB (4GB?) files work on Windows98, at least.

Fixed in SVN 221.  I've had an accident w/ my windows laptop and won't be able 
to
make a new release very soon.  But, it should build from source.

Fixed.  See issue 56.