Making non-standard OS checks in cmake?

[Raphael Kubo da Costa]

On Friday 01 January 2010 15:51:01 Raphael Kubo da Costa wrote:
> Hey there,
> 
> As you can see on my.cdash.org, both kdeadmin and kdenetwork fail to build
> cleanly on FreeBSD:
> 
>  * kdeadmin/kuser's CMakeLists.txt's check for the need to link against -
> lcrypt is broken on FreeBSD,  since the crypt() function is defined in
> unistd.h, not crypt.h, even though -lcrypt still must be passed to the
> compiler
>  * kdenetwork/kppp has been broken since FreeBSD 8.0 - currently the ports
> system just disable its build, and I'd like to do the same upstream.
> 
> In both cases (the former can actually be solved in a different way, but I
> have felt the need for this in other cases as well), it would be useful to
> know if the current OS is FreeBSD, just like APPLE, WIN32 or UNIX are set.
> Is there an easy way to do that?

I mean, besides checking CMAKE_SYSTEM_NAME (or is it OK to do it that way?)