how to figure out beforehand how much disk space will be needed when applying a static-delta

[Davis Roman <davis roman84 gmail com>]

Hi,

I work on embedded devices which don't have much onboard eMMC space so I'm trying to figure out

if there is a deterministic way to figure out how much disk space is needed when performing

an 'ostree static-delta apply-offline && ostree admin deploy'

Of course, I can always just attempt the above commands and if it fails then I'll know I don't have enough space however

my plan is to implement something a bit smarter where I check ahead of time if I have X MBs available otherwise don't bother 

with the above commands. My issue at the moment is how to figure out how many X MBs are needed.

Initially, I was thinking that the size of a static delta file correlates to how much disk space will be required however 

this turns out not to be the case.

I ran a test today for a 241MB static delta file which turned out to require 672MB of actual disk space.

Is there something, perhaps via the command line, that can tell me that given a 241MB static delta, I'll need 672MB available?

Thank you,

Davis