Disk space check

Hello,
I was wondering if there's a way to check if there's enough diskspace in the $INSTDIR directory for program installation.
If there isn't enough space the user would be prompted. I can use an IF comparison, however I don't know now to get the numbers for current space available and the space required by the installer. Are there special variables that store these values?

thanks.

-JC

The directory page already does that. You can add required size using AddSize or dynmically using SectionSetSize. For a manual check, you can use the following: