Workaround - read but not create long file names
Posted Mar 2, 2009 22:11 UTC (Mon) by tridge
Parent article: Third time is the charm?
I agree that we should try the approach of working around the patent. For
embedded use such as in a device like the TomTom, I think it is most important
for the device to be able to read long filenames on VFAT filesystems, but I don't
see any need to be able to create files with
long file names. On my TomTom, I don't know of any way that a user could create a file with a long file name anyway, except when the device is docked, in which case the manipulation of the VFAT filesystem is done by the host computer, not the device (it just exports a USB storage device).
So this suggests a simple solution:
- add a new kernel option for VFAT, "read only long file names (patent avoidance)"
- embedded vendors such as TomTom could enable this option, and be fully compatible with existing memory cards.
When this option is enabled, the kernel code that creates long file names in VFAT would be disabled. The code that understands long file names would still work.
This argument relies on the fact that all of the claims of the VFAT patent talk about "storing" the directory entries. If you don't ever store a directory entry in the VFAT format then you can't infringe this patent.
This doesn't solve the problem for all users, but it is much less drastic than dropping support for VFAT, as existing filesystems will still work. I think it would also work as a complete solution for many embedded Linux vendors.
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