scd: New options --info and --info-only for READKEY.
* scd/command.c (cmd_readkey): New options --info and --info-only. * scd/app.c (app_readkey): New arg 'flags'. * scd/app-common.h (APP_READKEY_FLAG_INFO): New. (struct app_ctx_s): New args 'ctrl' and 'flags' for member readkey. Change all implementers. * scd/app-nks.c (do_readkey): Stub implementation of APP_READKEY_FLAG_INFO. * scd/app-openpgp.c (do_readkey): Implement APP_READKEY_FLAG_INFO. * scd/app-piv.c (do_readkey): Ditto.
This feature allows to quickly get the keygrip and in most cases also
the usage flags for one specific keyref. Example:
<- readkey --info-only PIV.9D
-> S KEYPAIRINFO FC6061FB457224370B85C6F34DD56CD29E669620 PIV.9D e
-> OK
- Signed-off-by: Werner Koch <wk@gnupg.org>