There probably exists a bindiff program like this, but I felt like making one. It took me a while wading through the Bash manpage till I found out the magic incantations to fetch the last two positional parameters. There's probably a far more elegant way but this is working:
#!/bin/sh
# compare two binary files
if [ "$#" -lt 2 ]; then
echo Usage: $0 [DIFFOPTIONS] FILE1 FILE2 >&2
exit 1
fi
switches=${@:1:$(($#-2))}
file1=${@:$(($#-1)):1}; file2=${@:$(($#)):1}
binfile1=$(mktemp); binfile2=$(mktemp)
if [ -f $file1 -a -r $file1 -a -f $file2 -a -r $file2 ]; then
xxd $file1 $binfile1; xxd $file2 $binfile2
diff $switches $binfile1 $binfile2
else
echo Both files must exist and be readable >&2
exit 1
fi
Using it, I found that the trashed USB key had overwritten almost perfectly; only the first block had been hopelessly ruined, and the trailing zeros in the last block had been overwritten by 0xcc. At this point I could try to figure out where it got the bogus data, or I could just keep working on debugging the code. Mañana.
last updated 2012-01-11 20:41:16. served from tektonic.jcomeau.com