Cryfs should check memory is enough

[alexgarel]

Expected Behavior

Until #349 is fixed,

cryfs should check available memory and warn if it's too low for it to operate (with a prompt, are you sure ?).

Actual Behavior

I'm hit by #349 but in a weird way:

I installed cryfs on my personal server (4Gb of RAM). It runs ok, I put a lot of stuff in my encrypted directory… and no it refuses to mount it again because of OutOfMemory !

I have two phases: a first peak while it's deriving the key, which pass (near to the limit), and then a second peak an it fails with fuse: fork() failed: Cannot allocate memory.

You can imagine my deception :-( if it had failed from start, ok… but after I put something inside… (it's ok because I have this data on another drive, at home,…).

Specifications

• CryFS Version: cryfs 0.10.2
• Operating System (incl. Version): Debian 11 (4.19-ovh-xxxx-std-ipv6-64)
• memory: 4Gb (2.7 Gb free at the time of running)