The corruption of rsbep-protected data with GCC versions later than 4.3 has now been fixed.
I reviewed the code with valgrind, and it turned out that the code I "inherited" from the original rsbep package performed out of bounds read accesses in the "distribute" function... This was not in the "core" Reed-solomon code, only in the interleaving function. I re-wrote it - check rsbep.c, line 68 in the latest tarball. I also did a clean-up of useless code that was never called. The results work perfectly under all GCC versions I tried, under Debian/32, Arch/32 and FreeBSD/64. Give it a try: http://users.softlab.ntua.gr/~ttsiod/rsbep-0.1.0-ttsiodras.tar.bz2 So, to summarize, my response points on the original thread: - The errors reported by David Mathog on the list had to do with erroneous usage of the tools - either the "freeze"/"melt" scripts must be used, or "chopping" of the output has to be done via your own custom code. - The memory read access errors were fixed, so the tool works fine with all GCC versions under all OSes. - David's "pockmark" app is not representative of what happens in storage media - they don't fail on byte-boundaries - they fail on sector boundaries. My small contributions (freeze/melt scripts) on rsbep make sure that even if we lose 127 contiguous 512-byte sectors, we can still recover the data, at the exact original size. - If you want bullet-proof checks, you can easily add the MD5 or SHA sum of the input data, to the "to-be-shielded-stream", so that the "melting" can be 100% certain of successful in detecting successful restoration or data. This, however, is not necessary if you use an algorithm that can detect errors in the decoded stream (gzip, bzip2, etc) - One final comment about PAR, which was suggested by others: since it was designed for newsgroups, its recovery capabilities had other (non-storage related) scope - for an "executive summary" read the last of the comments I received when my rsbep became Slashdotted, here: http://hardware.slashdot.org/hardware/08/08/03/197254.shtml -- What I gave, I have; what I spent, I had; what I kept, I lost. -Old Epitaph _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
