keyboxd: Restructure client access code.

* kbx/kbx-client-util.c: New.
* kbx/kbx-client-util.h: New.
* kbx/Makefile.am (client_sources): New.
* g10/keydb.c (parse_keyblock_image): Rename to keydb_parse_keyblock
and make global.
* g10/call-keyboxd.c: Include kbx-client-util.h.
(struct keyboxd_local_s): Remove struct datastream.  Add field kcd.
Remove per_session_init_done.
(lock_datastream, unlock_datastream): Remove.
(prepare_data_pipe, datastream_thread): Remove.
(keydb_get_keyblock_do_parse): Remove.
(gpg_keyboxd_deinit_session_data): Release the KCD object.
(open_context): Use of kbx_client_data_new.
(keydb_get_keyblock): Simplify.
(keydb_search): Use kbx_client_data_cmd and _wait.
--

The data specific part of the code has been moved from gpg to a new
module in kbx/ so that it can also be used by gpgsm.  The OpenPGP
parsing while reading the data has been replaced by storing the data
in memory and parse it later.  That makes a nice interface and
abstracts the fd-passing/D-lines handling away.

Signed-off-by: Werner Koch <wk@gnupg.org>

kbx/kbx-client-util.h

@@ -0,0 +1,41 @@
+/* kbx-client-util.c - Defs for utility functions for a keyboxd client
+ * Copyright (C) 2020  g10 Code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#ifndef GNUPG_KBX_CLIENT_UTIL_H
+#define GNUPG_KBX_CLIENT_UTIL_H 1
+
+
+struct kbx_client_data_s;
+typedef struct kbx_client_data_s *kbx_client_data_t;
+
+gpg_error_t kbx_client_data_new (kbx_client_data_t *r_kcd,
+                                 assuan_context_t ctx);
+void kbx_client_data_release (kbx_client_data_t kcd);
+gpg_error_t kbx_client_data_cmd (kbx_client_data_t kcd, const char *command,
+                                 gpg_error_t (*status_cb)(void *opaque,
+                                                          const char *line),
+                                 void *status_cb_value);
+gpg_error_t kbx_client_data_wait (kbx_client_data_t kcd,
+                                  char **r_data, size_t *r_datalen);
+
+
+
+
+#endif /*GNUPG_KBX_CLIENT_UTIL_H*/