sub openFile {

    my ($file, $accessMode) = @_;
    my $err;

    if (! defined($accessMode)) {   # by default, open the file for reading
        $accessMode = $MODE_READ;
    }

    if (exists($ACCESS_MODES{$accessMode})) {
        if (! open(FILE, "$ACCESS_MODES{$accessMode}$file")) {
            $err = $!;
            if (defined($returnOnError)) {
                return $FALSE;
            }
            &throwGenError("Can't open $file: $err");   # throw exception
        }
    } else {
        &throwGenError("In openFile: Wrong access mode $accessMode");
    }
    return FILE;
}

##</code><code>##

sub func1 {

  my (@fileContent,@temp, @comment);
  my $contentFh = &openFile($file1);

  while (my $line = <$contentFh >) {
    ...
    push(@fileContent,&func2($line));
    ...    
    }
  }
  close($contentFh);
  return \@fileContent;
}

sub func2 {

  my ($user) = @_;
  my @groupsFile;
  my $groupsFh = &openFile($file2);

  @groupsFile = <$groupsFh>;
  close($groupsFh);
  ...
  return @groupsFile;
}

##</code><code>##

readline() on closed filehandle FILE at /var/www/cgi-bin/lib/myfile.pl line 25.