################################################################################
sub checksum_lock {
         
        my $file_name = checksum_file_name (@_);
         
        open  (CHECKSUM_FILE, "$file_name.lock") || die "can't open $file_name.lock: $!";
        flock (CHECKSUM_FILE, LOCK_EX);
}
################################################################################
sub checksum_unlock {
        flock (CHECKSUM_FILE, LOCK_UN);
        close (CHECKSUM_FILE);
         
}
################################################################################
sub checksum_file_name {
        my ($kind) = @_;
         
        return "$preconf->{_}->{docroot}dbm/$kind.txt";
}
################################################################################
sub checksum_init {
        my ($kind) = @_;
        my $filename = checksum_file_name ($kind);
        print STDERR "   $filename... ";
         
        open (LOCK, ">$filename.lock") or die "Can't write to $filename.lock: $!\n";
        print LOCK 1;
        close (LOCK);
        chmod 0777, "$filename.lock";
        open (F, ">$filename") or die "Can't write to $filename: $!\n";
        print F '';
        close (F);
        chmod 0777, $filename;
        my %h;
        tie (%h, 'Eludia::Tie::Txt_hash', $filename) or die "Couldn't tie Txt_hash file $filename: $!\n";
        $preconf -> {_} -> {checksums} -> {$kind} = \%h;
                 
        print STDERR "ok.\n";
}
################################################################################
BEGIN {
        if ($preconf -> {_} -> {docroot}) {
         
                $preconf -> {_} -> {checksums} = {};
                 
                print STDERR "Txt, ok.\n";
         
        }
}
################################################################################
package Eludia::Tie::Txt_hash;
sub TIEHASH  {
        my ($package, $filename) = @_;
        -f $filename or die "File doesn't exist: $filename\n";
         
        my $options = {
         
                filename => $filename,
         
        };
        bless $options, $package;
}
sub FETCH {
        my ($options, $key) = @_;
         
        my $value;
        open  (F, $options -> {filename}) or die "Can't open $options->{filename}: $!\n";
         
        while (<F>) {
         
                /^$key\t/ or next;
                 
                $value = $';
                 
                chomp $value;
                 
                last;
         
        }
         
        close (F);
         
        return $value;
}
sub STORE {
        my ($options, $key, $value) = @_;
                 
        my %h = ();
        open  (F, $options -> {filename}) or die "Can't open $options->{filename}: $!\n";
                 
        while (<F>) {
         
                my ($k, $v) = split /[\t\n\r]+/;
                $h {$k} = $v;
         
        }
         
        close (F);
        $h {$key} = $value;
        open  (F, ">$options->{filename}") or die "Can't write to $options->{filename}: $!\n";
         
        while (my ($k, $v) = each %h) {
         
                print F "$k\t$v\n";
         
        }
         
        close (F);
}