Disk Cost Issue with ReserveCost!

 

This was an interestingly annoying issue I came across with Windows Installer, when you use the ReserveCost Element to specify the disk space by populating the disk cost for your components in the ReserveCost Table.

Here is the scenario:

1) You have a ReserveCost Element for your component which specifies the amount of disk space needed for the component.

2) You have conditions around the components which decide if the component is installed on the target machine.

 

So something like this….

<Component Id="MyCustomComponent" Guid="A2DCFC09-0651-4E2C-04A4-B18F759F9F41">
  <Condition>
    <![CDATA[MYCONDITION = "1"]]>
  </Condition>
  <File Id="MYCAB.CAB" Name="MYCAB.CAB" Source="$(var.CustomPath)MYCAB.CAB"  Compressed="no" 

  KeyPath="yes" DiskId="1" />
  <ReserveCost Directory="CABDIR" RunLocal="300000" RunFromSource="0" Id="CABID" />
</Component>

3) And then you have checks as follows in the “Next” or “Install” button
to prevent the installation from continuing if the target machine does not have
sufficient space

 

<Publish Event="SpawnDialog" Value="OutOfDiskDlg"><![CDATA[(OutOfDiskSpace = 1 AND 

OutOfNoRbDiskSpace = 1) OR (OutOfDiskSpace = 1 AND PROMPTROLLBACKCOST="F")]]></Publish>

You would expect to see the assigned space of 300000, in this case in the Space requirements information section by subscribing to the “SelectionSize” event

<Subscribe Event="SelectionSize" Attribute="Text" />

And also expect that the installer will not proceed with the installation on the target machine with insufficient space and will trigger the “OutOfDiskDlg” dialog which you just wired up.

 

But unfortunately even though your ReserveCost table was populated correctly, Windows Installer decides to go the safe route of not including the size (ReserveCost size) of any components which have a condition around them and the total space needed for the component(and Product) is not correct anymore (even if the conditions which they are dependant on have already being determined to be true and the component will be installed).

 

The fix for this would be to include a dummy component with the ReserveCost element with no conditions under the same feature (and ofcourse with no File attribute).