Compare files in two folders

#!/usr/bin/perl


# Compares all the files in two folders. Comparison is done using md5 signature.
#
# AUTHOR: Diego Pino García <dpino@igalia.com>

use strict;

open ERROR, ">.compare_errors" || die("Couldn't create .compare_errors");
open LOG, ">.log" || die("Couldn't create .log");

my $dir1 = $ARGV[0] || ".";
my $dir2 = $ARGV[1] || ".";

debug("$dir1, $dir2");

my @files = @{readfiles($dir1)};
debug("total files: ".scalar(@files));
compare($dir1, $dir2, @files);

close ERROR;
close LOG;

sub md5
{
    my $filedir = shift;
    my $str = `md5sum $filedir | cut -d " " -f 1`;
    $str =~ s/\n//g;
    return $str;
}

sub debug
{
    my $str = shift;

    print LOG $str."\n";
}

sub compare
{
    my($dir1, $dir2, @files) = @_;

    foreach my $file (@files) {
        debug($file);
        if ( (-f "$dir1/$file") && (-f "$dir2/$file") ) {
            my $file1MD5 = md5("$dir1/$file");
            my $file2MD5 = md5("$dir2/$file");
            debug("$file1MD5 == $file2MD5");
            if ($file1MD5 != $file2MD5) {
                print ERROR "$dir1/$file and $dir2/$file are different!\n";
            }
        } else {
            if (!(-f "$dir1/$file")) {
                print ERROR "Missing $dir1/$file\n";
            }
            if (!(-f "$dir2/$file")) {
                print ERROR "Missing $dir2/$file\n";
            }
        }
    }
}

sub readfiles
{
    my $dir = shift;
    my $files = [];

    opendir DIR, $dir || die("Couln't open dir: $dir\n");
    debug("Open dir: $dir");
    while (my $file = readdir(DIR)) {
        if (-f "$dir/$file") {
            push $files, $file;
        }
    }
    closedir DIR;

    return $files;
}