Failing an RPM install programatically in a spec step

Question

I'm making an RPM. This particular RPM has requirements that can't be expressed as RPM prerequisites, lets call them a particular filesystem/disk configuration. Currently the failure happens after install, at runtime, when the requirements aren't met.

I can check for the required prerequisites in the %install, section of my script. However, I can't figure out how to fail the install if certain criteria are met. Is it possible to fail an rpm install at runtime via some trigger in the %install (or some other) section?

An example would look something like so, in a .spec file:

%install
if [ -f /some/file ]
then
    FAIL_RPM_INSTALL ## What is this command?
fi