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 <[email protected]>

1 files changed, 19 insertions, 8 deletions

diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c
index c5ca063f7..1a537127c 100644
--- a/scd/app-openpgp.c
+++ b/scd/app-openpgp.c
@@ -1889,7 +1889,8 @@ do_learn_status (app_t app, ctrl_t ctrl, unsigned int flags)
    buffer. On error PK and PKLEN are not changed and an error code is
    returned.  */
 static gpg_error_t
-do_readkey (app_t app, const char *keyid, unsigned char **pk, size_t *pklen)
+do_readkey (app_t app, ctrl_t ctrl, const char *keyid, unsigned int flags,
+            unsigned char **pk, size_t *pklen)
 {
   gpg_error_t err;
   int keyno;
@@ -1912,15 +1913,25 @@ do_readkey (app_t app, const char *keyid, unsigned char **pk, size_t *pklen)
   if (!buf)
     return gpg_error (GPG_ERR_NO_PUBKEY);
 
-  *pklen = app->app_local->pk[keyno].keylen;
-  *pk = xtrymalloc (*pklen);
-  if (!*pk)
+  if ((flags & APP_READKEY_FLAG_INFO))
     {
-      err = gpg_error_from_syserror ();
-      *pklen = 0;
-      return err;
+      err = send_keypair_info (app, ctrl, keyno+1);
+      if (err)
+        return err;
+    }
+
+  if (pk && pklen)
+    {
+      *pklen = app->app_local->pk[keyno].keylen;
+      *pk = xtrymalloc (*pklen);
+      if (!*pk)
+        {
+          err = gpg_error_from_syserror ();
+          *pklen = 0;
+          return err;
+        }
+      memcpy (*pk, buf, *pklen);
     }
-  memcpy (*pk, buf, *pklen);
 
   return 0;
 }