zzexe: autodetect header size in decomp

zzexe

@@ -1,12 +1,12 @@
 #!/bin/sh
 set -e # exit on failure
 IFS=$(printf '\n\t') # smarter ifs
-[ "$1" = "-d" ] && tail -n+10 "$2" | zstd -cd | ifne sponge "$2" && exit
+[ "$1" = "-d" ] && awk 'f;/^exit/{f=1}' "$2" | head -c-1 | zstd -cd | ifne sponge "$2" && exit
 [ "$1" = "-p" ] && p="$2" && shift 2 # save prefix if present
 { cat << 'EOF'; zstdmt -c19 "$@"; } | sed "2s/$/${1##*[./]})/;7s/^/$p /" | sponge "$1"
 #!/bin/sh
 dir=$(dirname "$0") out=$(mktemp -t .zzXXXX.
-tail -n+10 "$0" | zstd -cd > "$out"
+awk 'f;/^exit/{f=1}' "$0" | head -c-1 | zstd -cd > "$out"
 chmod +x "$out"
 ln -s "$out" "$dir"
 trap "res=$?" 0 1 2 3 5 10 13 15