gpgsm: Extend --learn-card by an optional s/n argument.

* agent/command.c (cmd_learn): Allow for s/n argument.
* agent/learncard.c (agent_handle_learn): Ditto.
* agent/call-scd.c (agent_card_learn): Ditto.  Pass it on to scd.

* scd/command.c (cmd_switchcard): Factor most code out to ...
(switchcard_core): new.
(cmd_learn): Add option --demand to specify a s/n.

* sm/gpgsm.c (main): Allow a s/n argument for --learn-card.
--

This help Kleopatra to get a stable certificate listing.
GnuPG-bug-id: 7379

agent/agent.h

@@ -731,7 +731,7 @@ int agent_tpm2d_pkdecrypt (ctrl_t ctrl, const unsigned char *cipher,
 			   char **r_buf, size_t *r_len);
 
 /*-- call-scd.c --*/
-int agent_card_learn (ctrl_t ctrl,
+int agent_card_learn (ctrl_t ctrl, const char *demand_sn,
                       void (*kpinfo_cb)(void*, const char *),
                       void *kpinfo_cb_arg,
                       void (*certinfo_cb)(void*, const char *),
@@ -780,7 +780,8 @@ gpg_error_t agent_card_keyinfo (ctrl_t ctrl, const char *keygrip,
                                 int cap, struct card_key_info_s **result);
 
 /*-- learncard.c --*/
-int agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context, int force);
+int agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context,
+                        int force, const char *demand_sn);
 
 
 /*-- cvt-openpgp.c --*/

agent/call-scd.c

@@ -260,10 +260,14 @@ learn_status_cb (void *opaque, const char *line)
   return err;
 }
 
+
 /* Perform the LEARN command and return a list of all private keys
-   stored on the card. */
+ * stored on the card.  If DEMAND_SN is given the info is returned for
+ * the card with that S/N instead of the current card.  This may then
+ * switch the current card.  */
 int
 agent_card_learn (ctrl_t ctrl,
+                  const char *demand_sn,
                   void (*kpinfo_cb)(void*, const char *),
                   void *kpinfo_cb_arg,
                   void (*certinfo_cb)(void*, const char *),
@@ -273,6 +277,7 @@ agent_card_learn (ctrl_t ctrl,
 {
   int rc;
   struct learn_parm_s parm;
+  char line[ASSUAN_LINELENGTH];
 
   rc = start_scd (ctrl);
   if (rc)
@@ -285,7 +290,13 @@ agent_card_learn (ctrl_t ctrl,
   parm.certinfo_cb_arg = certinfo_cb_arg;
   parm.sinfo_cb = sinfo_cb;
   parm.sinfo_cb_arg = sinfo_cb_arg;
-  rc = assuan_transact (daemon_ctx (ctrl), "LEARN --force",
+
+  if (demand_sn && *demand_sn)
+    snprintf (line, sizeof line, "LEARN --demand=%s --force", demand_sn);
+  else
+    snprintf (line, sizeof line, "LEARN --force");
+
+  rc = assuan_transact (daemon_ctx (ctrl), line,
                         NULL, NULL, NULL, NULL,
                         learn_status_cb, &parm);
   if (rc)

agent/command.c

@@ -2376,27 +2376,31 @@ cmd_get_confirmation (assuan_context_t ctx, char *line)
 
 
 static const char hlp_learn[] =
-  "LEARN [--send] [--sendinfo] [--force]\n"
+  "LEARN [--send] [--sendinfo] [--force] [SERIALNO]\n"
   "\n"
   "Learn something about the currently inserted smartcard.  With\n"
   "--sendinfo information about the card is returned; with --send\n"
   "the available certificates are returned as D lines; with --force\n"
-  "private key storage will be updated by the result.";
+  "private key storage will be updated by the result. With SERIALNO\n"
+  "given the current card is first switched to the specified one.";
 static gpg_error_t
 cmd_learn (assuan_context_t ctx, char *line)
 {
   ctrl_t ctrl = assuan_get_pointer (ctx);
   gpg_error_t err;
   int send, sendinfo, force;
+  const char *demand_sn;
 
   send = has_option (line, "--send");
   sendinfo = send? 1 : has_option (line, "--sendinfo");
   force = has_option (line, "--force");
+  line = skip_options (line);
+  demand_sn = *line? line : NULL;
 
   if (ctrl->restricted)
     return leave_cmd (ctx, gpg_error (GPG_ERR_FORBIDDEN));
 
-  err = agent_handle_learn (ctrl, send, sendinfo? ctx : NULL, force);
+  err = agent_handle_learn (ctrl, send, sendinfo? ctx : NULL, force, demand_sn);
   return leave_cmd (ctx, err);
 }
 

agent/learncard.c

@@ -295,10 +295,14 @@ send_cert_back (ctrl_t ctrl, const char *id, void *assuan_context)
   return 0;
 }
 
+
 /* Perform the learn operation.  If ASSUAN_CONTEXT is not NULL and
-   SEND is true all new certificates are send back via Assuan.  */
+ * SEND is true all new certificates are send back via Assuan.  If
+ * DEMAND_SN is not NULL it has a string with the serial number of the
+ * card requested. */
 int
-agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context, int force)
+agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context, int force,
+                    const char *demand_sn)
 {
   int rc;
   struct kpinfo_cb_parm_s parm;
@@ -328,7 +332,7 @@ agent_handle_learn (ctrl_t ctrl, int send, void *assuan_context, int force)
   cparm.ctrl = ctrl;
 
   /* Now gather all the available info. */
-  rc = agent_card_learn (ctrl, kpinfo_cb, &parm, certinfo_cb, &cparm,
+  rc = agent_card_learn (ctrl, demand_sn, kpinfo_cb, &parm, certinfo_cb, &cparm,
                          sinfo_cb, &sparm);
   if (!rc && (parm.error || cparm.error || sparm.error))
     rc = parm.error? parm.error : cparm.error? cparm.error : sparm.error;