Hay guys I'm new to Perl and I'm using it for CGI-scripting with mod_perl and I'm having some problems. The command-line Perl compiler has no problem compiling it but when I open the script in my browser I get 500 error a 500 Internal Server Error. I am trying to make a simple file uploader and the page was working before I added it.

use strict;
use CGI qw(:standard);
use Fcntl qw(:DEFAULT :flock :seek);

use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

sub filesize {
    my $size = $_[0];
    my $i = 0;
    my @suf = ("B", "KiB", "MiB", "GiB", "TiB");
    
    for (; $size >= 1024; $i++) {
        $size /= 1024;
    }
    return sprintf("%.1f %s", $size, $suf[$i]);
}

my ($password, $file) = (param("password"), param("file"));

if ($ENV{"REQUEST_METHOD"} eq "POST" && defined $file && defined $pass
+word) {
    use constant UPLOADPUB => "C:\\Program Files\\Apache Group\\Apache
+2\\htdocs\\upload\\";
    use constant UPLOADDIR => "C:\\Documents and Settings\\Onion Knigh
+t\\Desktop\\";
    use constant MAXSIZE => 1048576;
    
    seek($file, 0, SEEK_END);
    my $size = tell($file);
    seek($file, 0, SEEK_SET);
    
    if ($password eq "") {
        if (sysopen(FILE, UPLOADDIR.$file, O_WRONLY | O_CREAT | O_TRUN
+C)) {
            flock(FILE, LOCK_EX);
            binmode FILE;

            my $buffer;
            while (read($file, $buffer, 512)) {
                print FILE $buffer;
            }
            print "                    $file uploaded successfully! ("
+, &filesize($size), ")";
            close(FILE);
        }
        else {
            print "                    Couldn't write file to disk.";
        }
    }
    elsif ($password eq "guest") {
        if ($size < MAXSIZE) {
            if ($file !~ /^\./) {
                unless (-e UPLOADPUB.$file) {
                    if (sysopen(FILE, UPLOADPUB.$file, O_WRONLY | O_CR
+EAT | O_TRUNC)) {
                        flock(FILE, LOCK_EX);
                        binmode FILE;

                        my $buffer;
                        while (read($file, $buffer, 512)) {
                            print FILE $buffer;
                        }
                        print "                    $file uploaded succ
+essfully! (", &filesize($size), ")";
                        close(FILE);
                    }
                    else {
                        print "                    Couldn't write file
+ to disk.";
                    }
                }
                else {
                    print "                    File exists already.";
                }
            }
            else {
                print "                    Filename not allowed.";
            }
        }
        else {
            print "                    Filesize too big!";
        }
    }
    else {
        print "                    Password incorrect.";
    }
}
else {
    print "                    <br />";
}
[download]

I didn't include any of the HTML-dumping prints because those are unnecessary.

Update: Sorry for writing bad code guys, I improved on it a little. As for headers, yes, I have them but like I said I didn't include any of the functions that print huge chunks of HTML. I tested commenting out the "use strict;" and it worked then! I wonder why. Also, the upload script doesn't work. It seems to me that I don't know how to handle uploaded files in the first place, what am I doing wrong? And why does strict prevent the site from generating?

Update 2: It works perfectly now! The file uploader, and I can use strict; without error. Exception being that the filesize is the size on disk rather than the size of the file. But I think that can be fixed.

Edited by Arunbear: Changed title from 'mod_perl mod_perl lol', as per Monastery guidelines