So I thought that for now we only support the "anonymous" mode, and if
in the future we have a use case where the user wants to specify the
name, we can add it later.
Okay, so for now you really only want an anonymous fd that behaves like
a memfd, got it.
Likely we should somehow fail if the "POSIX shared memory object"
already exists. Hmm.
`O_CREAT | O_EXCL` should provide just this behavior.
From shm_open(3) manpage:
O_EXCL If O_CREAT was also specified, and a shared memory object
with the given name already exists, return an error. The
check for the existence of the object, and its creation if
it does not exist, are performed atomically.
That said, if you think it's already useful from the beginning, I can
add the name as an optional parameter.
I'm also not quite sure if "host_memory_backend_get_name()" should be
used for the purpose here.
What problem do you see? As an alternative I thought of a static
counter.
If it's really just an "internal UUID", as we'll remove the file using
shm_unlink(), then the name in fact shouldn't matter and this would be
fine. Correct?
Right. It's a name that will only "appear" in the system for a very
short time since we call shm_unlink() right after shm_open(). So I just
need the unique name to prevent several QEMUs launched at the same time
from colliding with the name.
So I assume if we ever want to have non-anonymous fds here, we'd pass
in a new property "name", and change the logic how we open/unlink.
Makes sense.
Exactly! I can clarify this in the commit description as well.
Thanks for the helpful comments!
If there is anything I need to change for v3, please tell me ;-)