Any brave dive computer download testers out there?

Linus Torvalds torvalds at
Mon Apr 23 11:57:29 PDT 2018

On Mon, Apr 23, 2018 at 10:07 AM, Linus Torvalds
<torvalds at> wrote:
> What we *could* do is to do it knowingly wrong, the way dctool does
> it: don't save the fingerprint data with the real dive data at all,
> just have a random "last download" cache indexed by device family and
> serial number.
> That's how the feature is designed to be used, and it would avoid the
> nasty "pollute our logs with meaningless and badly defined crazy data
> that will never be useful in the future".

So here's a patch for people to play with if they want to.

This is literally how the fingerprint thing is meant to be used, and
it works, but it's a bit dangerous.

It's dangerous because the rule is "once we've downloaded the dives on
one machine, we don't want to download them again".

You can see the breakage by:

 (a) applying this patch

 (b) downloading some dives into a new empty xml file, or as a
different user (so that you actually download things)

 (c) *NOT* saving the end result, closing subsurface

 (d) opening subsurface again with the same empt xml file, and trying
to download

At that point, the fingerprint code says "I've already downloaded all
the dives on this machine, so you have nothing new to download".

Which is exactly how the feature is designed, so hey, it's doing what
it meant to do. You don't want to re-download the same dives over and
over again, do you?

And if you *do* want to re-download them, you'd better just check the
"Force download all dives" checkbox.

Note that this patch saves the fingerprint in the downloader. It would
probably be better to at *least* wait until the user has pressed "ok"
with the most recent dive checked. That still doesn't mean "saved",
but it's a lot closer.

This has been very lightly tested, and did the right thing with my Perdix AI.

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