Multiple readers with scdaemon
gniibe at fsij.org
Thu Sep 19 01:49:49 CEST 2019
Laurent Bigonville <bigon at bigon.be> wrote:
> I'm coming back to this question after almost a year, but this is still
> an issue for me as without pcscd support, I cannot use other smartcard
> if scdaemon is running.
It is not ignored. Sorry, it has been in low priority state.
Well, the multiple readers support with PC/SC is tracked here:
The feature is now in the master branch (this week). I tested the
feature in my environment of Windows under qemu VM, too. It works for
this environment of mine.
So far, it is only lightly tested. I think that there are some
complicated use cases like: using two readers for OpenPGP cards, and
another for different card for different application. Those cases are
not tested at all. Your testing will be appreciated.
Still, in my opinion, I prefer access to USB device directly by libusb
(not through PC/SC service), when it is possible.
In the development of the support of multiple readers with PC/SC, I
tried to use the API of SCardGetStatusChange and SCardCancel within a
single context, so that scdaemon don't need to poll periodically. I
realized that the API is not good enough (there are fundamental race
conditions). So, for this time, I don't pursue to remove scdaemon's
periodical check with SCardGetStatus. I know that this is not a perfect
situation and some users of laptop complain about possible more use of
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