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Date: Sun, 17 Feb 2013 11:33:58 +1100 (EST)
From: Bruce Evans <brde@optusnet.com.au>
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Subject: cleaning files beyond EOF
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I have a (possibly damaged) ffs data block with nonzero data beyond
EOF.  Is anything responsible for clearing this data when the file
is mmapped()?

At least old versions of gcc mmap() the file and have a bug checking
for EOF.  They read the garbage beyond the end and get confused.

Bruce