If you use a 3rd party command line zip tool like 7-zip
, you might find a function to get the size (although maybe not directly).
For example, 7zip does not have anthing that just returns the size, but if you issue this command:
7za l archive.zip > c:\temp\list.txt
you'll get the contents of the archive "archive.zip" to the file "C:\temp\list.txt") in which the the 2nd to the last line contains the total size (in bytes) of the zip archive. Once you have that, you could write a function that would open the file and read the info out of it. (Check the plugins page for some functions to help you.)
Other zip utilities might offer something similiar.
Or, if you are the one packing the zip file in the first place, just unzip the archive on your own to figure out its size and then add the size your installation as JasonFriday13 suggested.