Wine implements StgOpenStorageEx (http://msdn.microsoft.com/en-us/library/aa380342%28v=vs.85%29.aspx) and other related API functions for accessing compound binary files. However, to use Wine for this, you must use winelib, and this is probably impractical. I would guess that extracting the storage code and removing the Windows API dependencies is also impractical. The format of structured storage files is publicly documented and fairly simple (http://msdn.microsoft.com/en-us/library/dd942138%28v=prot.13%29.aspx), so rolling your own solution is possible, though not ideal. I was hoping there'd be some open source library for this, but all I can find is OpenMCDF (http://sourceforge.net/projects/openmcdf/) which relies on .NET.
