qt: Add mechanism for missing d-pointer in Job

* lang/qt/src/job_p.h: New.
* lang/qt/src/job.cpp (typedef JobPrivateHash, d_func, setJobPrivate,
getJobPrivate): New.
--

Because of ABI compatibility requirements we cannot add a d-pointer
to Job. Therefore we store the d-pointers in a global static. This
mechanism will allow Job subclasses to store additional data without
breaking the ABI.

GnuPG-bug-id: 4717

lang/qt/src/job.cpp

@@ -5,6 +5,8 @@
     Copyright (c) 2004,2005 Klarälvdalens Datakonsult AB
     Copyright (c) 2016 by Bundesamt für Sicherheit in der Informationstechnik
     Software engineering by Intevation GmbH
+    Copyright (c) 2021 g10 Code GmbH
+    Software engineering by Ingo Klöcker <dev@ingo-kloecker.de>
 
     QGpgME is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License as
@@ -37,6 +39,7 @@
 #endif
 
 #include "job.h"
+#include "job_p.h"
 
 #include "keylistjob.h"
 #include "listallkeysjob.h"
@@ -72,6 +75,25 @@
 
 #include <gpg-error.h>
 
+#include <unordered_map>
+
+namespace
+{
+typedef std::unordered_map<const QGpgME::Job*, std::unique_ptr<QGpgME::JobPrivate>> JobPrivateHash;
+Q_GLOBAL_STATIC(JobPrivateHash, d_func)
+}
+
+void QGpgME::setJobPrivate(const Job *job, std::unique_ptr<JobPrivate> d)
+{
+    auto &ref = d_func()->operator[](job);
+    ref = std::move(d);
+}
+
+QGpgME::JobPrivate *QGpgME::getJobPrivate(const Job *job)
+{
+    return d_func()->operator[](job).get();
+}
+
 QGpgME::Job::Job(QObject *parent)
     : QObject(parent)
 {

lang/qt/src/job_p.h

@@ -0,0 +1,70 @@
+/*
+    job_p.h
+
+    This file is part of qgpgme, the Qt API binding for gpgme
+    Copyright (c) 2021 g10 Code GmbH
+    Software engineering by Ingo Klöcker <dev@ingo-kloecker.de>
+
+    QGpgME 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 2 of the
+    License, or (at your option) any later version.
+
+    QGpgME 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, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of this program with any edition of
+    the Qt library by Trolltech AS, Norway (or with modified versions
+    of Qt that use the same license as Qt), and distribute linked
+    combinations including the two.  You must obey the GNU General
+    Public License in all respects for all of the code used other than
+    Qt.  If you modify this file, you may extend this exception to
+    your version of the file, but you are not obligated to do so.  If
+    you do not wish to do so, delete this exception statement from
+    your version.
+*/
+
+#ifndef __QGPGME_JOB_P_H__
+#define __QGPGME_JOB_P_H__
+
+#include "job.h"
+
+#include <memory>
+
+namespace QGpgME
+{
+
+// Base class for pimpl classes for Job subclasses
+class JobPrivate
+{
+public:
+    virtual ~JobPrivate() {}
+};
+
+// Setter and getters for the externally stored pimpl instances of jobs
+// BCI: Add a real d-pointer to Job
+void setJobPrivate(const Job *job, std::unique_ptr<JobPrivate> d);
+
+JobPrivate *getJobPrivate(const Job *job);
+
+template <typename T>
+static T *jobPrivate(const Job *job) {
+    auto d = getJobPrivate(job);
+    if (!d) {
+        std::unique_ptr<T> ref{new T};
+        d = ref.get();
+        setJobPrivate(job, std::move(ref));
+    }
+    return dynamic_cast<T *>(d);
+}
+
+}
+
+#endif // __QGPGME_JOB_P_H__