これで一旦完成。

#!/usr/local/bin/perl
use CGI":all";sub U{unescape CGI@_}chomp(($d,$c,$s,$q,$_,@w)=<DATA>);chdir$d;$_
=$&if path_info=~m|[^/]+|;tr/\x00- \x7F/ /s;$_=escape CGI$_;-d&¨$/='';open
F,($w=param w)?">$_":$_;eval{flock F,2};print F$w||=<F>;opendir D,'.';charset$c
;put header,start_html(-title=>U($_),style=>$s,lang,ja,encoding,$c),ul(map{li""
.localtime((stat)[9]),a{href,url."/$_"},U$_}sort grep!/^\./,readdir D),h1(U$_),
startform(0,url."/$_"),p(textarea(w,$w,@w),submit$q),'</form>',end_html

__DATA__
data_dir
EUC-JP
http://example.com/path/to/your.css
save
Default Page Title
20
70