+ ($size) = ($size =~ /^(\d+)$/) or die "size '$size' not an integer\n"; # untaint
+ ($used) = ($used =~ /^(\d+)$/) or die "used '$used' not an integer\n"; # untaint
+ ($format) = ($format =~ /^(\S+)$/) or die "format '$format' includes whitespace\n"; # untaint
+ if (defined($parent)) {
+ ($parent) = ($parent =~ /^(\S+)$/) or die "parent '$parent' includes whitespace\n"; # untaint
+ }