$max_num_files  ||= 1;
$Photo_Dir      ||= $ENV{'DOCUMENT_ROOT'};

undef @bad_extensions if @good_extensions;
for(my $a = 1; $a <= $max_num_files; $a++) {
    my $req = new CGI;
    ...

##</code><code>##

use strict;
use CGI;

my $req = new CGI;

foreach my $type ( qw/P T/ )  # 'P' for Photo, 'T' for Thumbnail
{
    my $indx = 0;
    while ( 1 )  # we'll exit when $indx gets high enough
    {
        my $paramName = sprintf( "%s_FILE%d", $type, ++$indx );

        last unless ( $req->param( $paramName ));

        my $outname = my $inname = $req->param( $paramName );

        $outname =~ s/^.*(\\|\/)//; # remove leading path
        $outname =~ s/ +/\_/g;      # don't want spaces
        $outname =~ s/\"//g;        # don't want quotes
        $outname = "th_$outname" if ( $type eq "T" );

# removed long portion that depended on @good_extensions and/or
# @bad_extensions having contents : no evidence that they ever did

# removed long portion that depended on $auto_rename having a value of
# 1 or 2 and checking whether "$Photo_Dir/$outname" already exists :
# no evidence that $auto_rename is ever non-zero

# ( I think the original posted code forgot to open the input file )

        my $insize = ( -s $inname );
        ( $insize && open( INFILE, $inname )) or next;

        if ( open( OUTFILE, ">$ENV{DOCUMENT_ROOT}/$outname")) {
            my $outsize = 0;
            while ( my $nr = sysread( INFILE, my $buffer, 1024 )) {
                my $nw = syswrite( OUTFILE, $buffer );
                last if ( $nr != $nw );
                $outsize += $nw;
            }
            close OUTFILE;
            if ( $outsize != $insize ) {
                last;  # might want to report this somehow...
            }

# removed long portion that depended on $max_size being non-zero :
# no evidence that it ever was

        }
        close INFILE;
    }
}