Optional mandatory locking

Posted Dec 16, 2015 23:28 UTC (Wed) by neilbrown (subscriber, #359)
In reply to: Optional mandatory locking by nix
Parent article: Optional mandatory locking

> One problem, of course, is that moving to that intermediate trust-but-verify scheme should really require something that is in some sense intermediate between that used by advisory locking and no-write-permission, so you could shift between them easily.

Nope. There is an enormous difference between co-operating processes and adversarial processes. Advisory locking is for friends that work together on a common goal and don't want to tread on each other's toes. IPC is for strangers with a contractual arrangement. They really are different scenarios and pretending you can drift smoothly from one to the other is a mistake.

I can agree that it would be nice if IPC were as easy as writing to a file, but I don't agree that you should be able to achieve IPC with minor modifications to code which is written to just write to a file.

Optional mandatory locking

Posted Dec 20, 2015 1:08 UTC (Sun) by nix (subscriber, #2304) [Link]

Hm, good point -- only, of course, the whole point of 'everything is an fd' and That Hideous Name was that you *should* be able to make major changes like that with as little churn as possible. I would be ever so happy if the VFS was general enough that it *was* the only IPC mechanism we needed. But that's not what we've got :(