cpp: Add interactor to add existing subkeys to other keys

* lang/cpp/src/gpgaddexistingsubkeyeditinteractor.cpp,
lang/cpp/src/gpgaddexistingsubkeyeditinteractor.h: New.
* lang/cpp/src/Makefile.am: Add new files.
--

GnuPG-bug-id: 5770

NEWS

@@ -12,6 +12,8 @@ Noteworthy changes in version 1.16.1 (unreleased)
  * cpp,qt: Add support for export of secret keys and secret subkeys.
    [#5757]
 
+ * cpp: Support for adding existing subkeys to other keys.  [#5770]
+
  * qt: Extend ChangeExpiryJob to change expiration of primary key
    and of subkeys at the same time. [#4717]
 
@@ -25,6 +27,7 @@ Noteworthy changes in version 1.16.1 (unreleased)
  cpp: Context::startKeyExport               NEW.
  cpp: Context::exportSecretKeys             NEW.
  cpp: Context::startSecretKeyExport         NEW.
+ cpp: GpgAddExistingSubkeyEditInteractor    NEW.
  GPGME_EXPORT_MODE_SECRET_SUBKEY            NEW.
  gpgme_set_ctx_flag                    EXTENDED: New flag 'key-origin'.
  gpgme_set_ctx_flag                    EXTENDED: New flag 'import-filter'.

lang/cpp/src/Makefile.am

@@ -33,6 +33,7 @@ main_sources = \
     engineinfo.cpp gpgsetexpirytimeeditinteractor.cpp \
     gpgsetownertrusteditinteractor.cpp gpgsignkeyeditinteractor.cpp \
     gpgadduserideditinteractor.cpp gpggencardkeyinteractor.cpp \
+    gpgaddexistingsubkeyeditinteractor.cpp \
     defaultassuantransaction.cpp \
     scdgetinfoassuantransaction.cpp gpgagentgetinfoassuantransaction.cpp \
     statusconsumerassuantransaction.cpp \
@@ -46,6 +47,7 @@ gpgmepp_headers = \
     gpgmefw.h gpgsetexpirytimeeditinteractor.h \
     gpgsetownertrusteditinteractor.h gpgsignkeyeditinteractor.h \
     gpggencardkeyinteractor.h \
+    gpgaddexistingsubkeyeditinteractor.h \
     importresult.h keygenerationresult.h key.h keylistresult.h \
     notation.h result.h scdgetinfoassuantransaction.h signingresult.h \
     statusconsumerassuantransaction.h \

lang/cpp/src/gpgaddexistingsubkeyeditinteractor.cpp

@@ -0,0 +1,209 @@
+/*
+  gpgaddexistingsubkeyeditinteractor.cpp - Edit Interactor to add an existing subkey to an OpenPGP key
+  Copyright (c) 2022 g10 Code GmbH
+  Software engineering by Ingo Klöcker <dev@ingo-kloecker.de>
+
+  This file is part of GPGME++.
+
+  GPGME++ is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Library General Public
+  License as published by the Free Software Foundation; either
+  version 2 of the License, or (at your option) any later version.
+
+  GPGME++ 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 Library General Public License for more details.
+
+  You should have received a copy of the GNU Library General Public License
+  along with GPGME++; see the file COPYING.LIB.  If not, write to the
+  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+  Boston, MA 02110-1301, USA.
+*/
+
+#ifdef HAVE_CONFIG_H
+ #include "config.h"
+#endif
+
+#include "gpgaddexistingsubkeyeditinteractor.h"
+
+#include "error.h"
+
+#include <gpgme.h>
+
+// avoid conflict (msvc)
+#ifdef ERROR
+# undef ERROR
+#endif
+
+using namespace GpgME;
+
+class GpgAddExistingSubkeyEditInteractor::Private
+{
+    enum {
+        START = EditInteractor::StartState,
+        COMMAND,
+        ADD_EXISTING_KEY,
+        KEYGRIP,
+        FLAGS,
+        VALID,
+        KEY_CREATED,
+        QUIT,
+        SAVE,
+
+        ERROR = EditInteractor::ErrorState
+    };
+
+    GpgAddExistingSubkeyEditInteractor *const q = nullptr;
+
+public:
+    Private(GpgAddExistingSubkeyEditInteractor *q, const std::string &keygrip)
+        : q{q}
+        , keygrip{keygrip}
+    {
+    }
+
+    const char *action(Error &err) const;
+    unsigned int nextState(unsigned int statusCode, const char *args, Error &err) const;
+
+    std::string keygrip;
+    std::string expiry;
+};
+
+const char *GpgAddExistingSubkeyEditInteractor::Private::action(Error &err) const
+{
+    switch (q->state()) {
+    case COMMAND:
+        return "addkey";
+    case ADD_EXISTING_KEY:
+        return "keygrip";
+    case KEYGRIP:
+        return keygrip.c_str();
+    case FLAGS:
+        return "Q"; // do not toggle any usage flags
+    case VALID:
+        return expiry.empty() ? "0" : expiry.c_str();
+    case QUIT:
+        return "quit";
+    case SAVE:
+        return "Y";
+    case START:
+    case KEY_CREATED:
+    case ERROR:
+        return nullptr;
+    default:
+        err = Error::fromCode(GPG_ERR_GENERAL);
+        return nullptr;
+    }
+}
+
+unsigned int GpgAddExistingSubkeyEditInteractor::Private::nextState(unsigned int status, const char *args, Error &err) const
+{
+    using std::strcmp;
+
+    static const Error GENERAL_ERROR  = Error::fromCode(GPG_ERR_GENERAL);
+    static const Error NO_KEY_ERROR = Error::fromCode(GPG_ERR_NO_KEY);
+    static const Error INV_TIME_ERROR = Error::fromCode(GPG_ERR_INV_TIME);
+
+    if (q->needsNoResponse(status)) {
+        return q->state();
+    }
+
+    switch (q->state()) {
+    case START:
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keyedit.prompt") == 0) {
+            return COMMAND;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case COMMAND:
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keygen.algo") == 0) {
+            return ADD_EXISTING_KEY;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case ADD_EXISTING_KEY:
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keygen.keygrip") == 0) {
+            return KEYGRIP;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case KEYGRIP:
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keygen.flags") == 0) {
+            return FLAGS;
+        } else if (status == GPGME_STATUS_GET_LINE &&
+                   strcmp(args, "keygen.keygrip")) {
+            err = NO_KEY_ERROR;
+            return ERROR;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case FLAGS:
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keygen.valid") == 0) {
+            return VALID;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case VALID:
+        if (status == GPGME_STATUS_KEY_CREATED) {
+            return KEY_CREATED;
+        }
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keyedit.prompt") == 0) {
+            return QUIT;
+        } else if (status == GPGME_STATUS_GET_LINE &&
+                   strcmp(args, "keygen.valid")) {
+            err = INV_TIME_ERROR;
+            return ERROR;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case KEY_CREATED:
+        return QUIT;
+    case QUIT:
+        if (status == GPGME_STATUS_GET_BOOL &&
+                strcmp(args, "keyedit.save.okay") == 0) {
+            return SAVE;
+        }
+        err = GENERAL_ERROR;
+        return ERROR;
+    case ERROR:
+        if (status == GPGME_STATUS_GET_LINE &&
+                strcmp(args, "keyedit.prompt") == 0) {
+            return QUIT;
+        }
+        err = q->lastError();
+        return ERROR;
+    default:
+        err = GENERAL_ERROR;
+        return ERROR;
+    }
+}
+
+GpgAddExistingSubkeyEditInteractor::GpgAddExistingSubkeyEditInteractor(const std::string &keygrip)
+    : EditInteractor{}
+    , d{new Private{this, keygrip}}
+{
+}
+
+GpgAddExistingSubkeyEditInteractor::~GpgAddExistingSubkeyEditInteractor() = default;
+
+void GpgAddExistingSubkeyEditInteractor::setExpiry(const std::string &timeString)
+{
+    d->expiry = timeString;
+}
+
+const char *GpgAddExistingSubkeyEditInteractor::action(Error &err) const
+{
+    return d->action(err);
+}
+
+unsigned int GpgAddExistingSubkeyEditInteractor::nextState(unsigned int status, const char *args, Error &err) const
+{
+    return d->nextState(status, args, err);
+}

lang/cpp/src/gpgaddexistingsubkeyeditinteractor.h

@@ -0,0 +1,59 @@
+/*
+  gpgaddexistingsubkeyeditinteractor.h - Edit Interactor to add an existing subkey to an OpenPGP key
+  Copyright (c) 2022 g10 Code GmbH
+  Software engineering by Ingo Klöcker <dev@ingo-kloecker.de>
+
+  This file is part of GPGME++.
+
+  GPGME++ is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Library General Public
+  License as published by the Free Software Foundation; either
+  version 2 of the License, or (at your option) any later version.
+
+  GPGME++ 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 Library General Public License for more details.
+
+  You should have received a copy of the GNU Library General Public License
+  along with GPGME++; see the file COPYING.LIB.  If not, write to the
+  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+  Boston, MA 02110-1301, USA.
+*/
+
+#ifndef __GPGMEPP_GPGADDEXISTINGSUBKEYEDITINTERACTOR_H__
+#define __GPGMEPP_GPGADDEXISTINGSUBKEYEDITINTERACTOR_H__
+
+#include "editinteractor.h"
+
+#include <memory>
+
+namespace GpgME
+{
+
+class GPGMEPP_EXPORT GpgAddExistingSubkeyEditInteractor : public EditInteractor
+{
+public:
+    /** Edit interactor to add the existing subkey with keygrip \a keygrip
+     *  to the key a key edit operation is working on.
+     **/
+    explicit GpgAddExistingSubkeyEditInteractor(const std::string &keygrip);
+    ~GpgAddExistingSubkeyEditInteractor() override;
+
+    /** Sets the validity period of the added subkey. Use "0" for no expiration
+     *  or a simplified ISO date string ("yyyymmddThhmmss") for setting an
+     *  expiration date. */
+    void setExpiry(const std::string &timeString);
+
+private:
+    const char *action(Error &err) const override;
+    unsigned int nextState(unsigned int statusCode, const char *args, Error &err) const override;
+
+private:
+    class Private;
+    const std::unique_ptr<Private> d;
+};
+
+} // namespace GpgME
+
+#endif // __GPGMEPP_GPGADDEXISTINGSUBKEYEDITINTERACTOR_H__