#!/bin/sh -ex

w=$1
[ -n "$w" ]
[ -d rc/$w.cfg ]
redo $w
mkdir -p updates
[ -s updates/$w.old ] || {
    echo This is first run
    mv $w updates/$w.old
    exit
}
bsdiff updates/$w.old $w updates/$w.bsdiff
mv updates/$w.old updates/$w.older
mv $w updates/$w.old
cat > updates/$w-update.sh <<EOF
#!/bin/sh -ex
w=\$1
[ -n "\$w" ]
their_hash=\`sha512 < \$w\`
our_hash=`sha512 < updates/$w.older`
[ "\$their_hash" = "\$our_hash" ]
b64decode -o \$w.bsdiff < \$0
bspatch \$w \$w.new \$w.bsdiff
their_hash=\`sha512 < \$w.new\`
our_hash=`sha512 < updates/$w.old`
[ "\$their_hash" = "\$our_hash" ]
chown \`stat -f %u:%g \$w\` \$w.new
chmod \`stat -f %Mp%Lp \$w\` \$w.new
rm \$w.bsdiff
mv -f \$w.new \$w
exit
EOF
b64encode updates/$w.bsdiff < updates/$w.bsdiff >> updates/$w-update.sh
chmod +x updates/$w-update.sh