qt: Add API to get the context for a Job

* lang/qt/src/job.cpp,
lang/qt/src/job.h (Job::context): New.
* lang/qt/src/threadedjobmixin.cpp
(ThreadedJobMixin::~ThreadedJobMixin): New. Unregister context.
(ThreadedJobMixin::lateInitialization): Register context.
* NEWS: Update for cpp and qt.

--
The global map hack is necessary because the job class does
not know about the context which is held in threadedjobmixin.
Adding a virtual function in Job would be an ABI break which
I'd like to avoid at this point. Although QGpgME's API will
need a big ABI break to make it ABI maintainable. The virtual
jobs -> implementation classes are nearly unmaintainable ABI wise.

The context is exposed to provide more flexibility to users, e.g.
to add a passphrase callback or to set the sender in a context.

NEWS

@@ -14,9 +14,12 @@ Noteworthy changes in version 1.7.2 (unreleased)
  gpgme_query_swdb_result_t       NEW.
  qt: DN                          NEW.
  qt: DN::Attribute               NEW.
+ qt: Job::context(Job*)          NEW.
  cpp: EngineInfo::Version::Version(const char*) NEW.
  cpp: EngineInfo::Version::Version()            NEW.
  cpp: SwdbResult                                NEW.
+ cpp: Context::setSender(const char*)           NEW.
+ cpp: Context::getSender()                      NEW.
 
 
 Noteworthy changes in version 1.7.1 (2016-10-18)

lang/qt/src/job.cpp

@@ -62,6 +62,7 @@
 #include "keyformailboxjob.h"
 #include "wkspublishjob.h"
 #include "tofupolicyjob.h"
+#include "threadedjobmixin.h"
 
 #include <QCoreApplication>
 #include <QDebug>
@@ -78,7 +79,6 @@ QGpgME::Job::Job(QObject *parent)
 
 QGpgME::Job::~Job()
 {
-
 }
 
 QString QGpgME::Job::auditLogAsHtml() const
@@ -98,6 +98,14 @@ bool QGpgME::Job::isAuditLogSupported() const
     return auditLogError().code() != GPG_ERR_NOT_IMPLEMENTED;
 }
 
+QMap <QGpgME::Job *, GpgME::Context *> QGpgME::g_context_map;
+
+/* static */
+GpgME::Context *QGpgME::Job::context(QGpgME::Job *job)
+{
+    return QGpgME::g_context_map.value (job, nullptr);
+}
+
 #define make_job_subclass_ext(x,y)                \
     QGpgME::x::x( QObject * parent ) : y( parent ) {} \
     QGpgME::x::~x() {}

lang/qt/src/job.h

@@ -38,6 +38,7 @@
 
 #include <QObject>
 #include <QString>
+#include <QMap>
 
 #ifdef BUILDING_QGPGME
 # include "error.h"
@@ -79,6 +80,20 @@ public:
     virtual GpgME::Error auditLogError() const;
     bool isAuditLogSupported() const;
 
+    /** Get the underlying context to set some additional options for a job.
+     *
+     * This is intended to provide more flexibility on configuring jobs before
+     * they are started.
+     * The context is still owned by the thread, do not delete it.
+     *
+     * This is a static method that takes the job as argument.
+     *
+     * This function may not be called for running jobs.
+     *
+     * @returns the context used by the job job or null.
+     */
+    static GpgME::Context *context(Job *job);
+
 public Q_SLOTS:
     virtual void slotCancel() = 0;
 
@@ -87,6 +102,7 @@ Q_SIGNALS:
     void done();
 };
 
+extern QMap <Job *, GpgME::Context *> g_context_map;
 }
 
 #endif // __KLEO_JOB_H__

lang/qt/src/threadedjobmixin.h

@@ -48,6 +48,7 @@
 # include <gpgme++/interfaces/progressprovider.h>
 #endif
 
+#include "job.h"
 
 #include <cassert>
 
@@ -147,7 +148,6 @@ protected:
     explicit ThreadedJobMixin(GpgME::Context *ctx)
         : T_base(0), m_ctx(ctx), m_thread(), m_auditLog(), m_auditLogError()
     {
-
     }
 
     void lateInitialization()
@@ -155,6 +155,12 @@ protected:
         assert(m_ctx);
         QObject::connect(&m_thread, SIGNAL(finished()), this, SLOT(slotFinished()));
         m_ctx->setProgressProvider(this);
+        QGpgME::g_context_map.insert(this, m_ctx.get());
+    }
+
+    ~ThreadedJobMixin()
+    {
+        QGpgME::g_context_map.remove(this);
     }
 
     template <typename T_binder>

lang/qt/tests/t-tofuinfo.cpp

@@ -152,6 +152,10 @@ private Q_SLOTS:
         const QByteArray data1(testMsg1);
         QByteArray plaintext;
 
+        auto ctx = Job::context(job);
+        Q_ASSERT(ctx);
+        ctx->setSender("alfa@example.net");
+
         auto result = job->exec(data1, plaintext);
         delete job;