Adapt to poppler sign api change

Now poppler offers signing via PDFConverter class. Add some error
handling, and store signature in temp file. Document gets reloaded
after replacing original file.

core/document.cpp

@@ -2704,7 +2704,32 @@ bool Document::canConfigurePrinter() const
 void Document::sign( const Okular::Annotation* pWhichAnnotation )
 {
     if (d->m_generator->canSign())
-        d->m_generator->sign( pWhichAnnotation );
+    {
+        // we technically need to save the document before signing it,
+        // so let's ask before clobbering
+        const int res = KMessageBox::warningContinueCancel(
+            d->m_widget,
+            i18n( "Signing this document will modify the file \"%1\" on disk by embedding a "
+                  "digital signature inside it. Do you wish to proceed?",
+                  currentDocument().fileName() ),
+            i18n( "Sign Document" ),
+            KStandardGuiItem::ok(),
+            KStandardGuiItem::cancel(),
+            QStringLiteral("SignatureAutoClobber") );
+
+        if (res == KMessageBox::Continue)
+        {
+            // Sign it!
+            if (!d->m_generator->sign( pWhichAnnotation, currentDocument().path() ))
+            {
+                KMessageBox::error( nullptr, i18n("Could not sign '%1'. Invalid password or cannot write",
+                                                  currentDocument().fileName() ) );
+            }
+                // no need to - slotAttemptReload() gets called via
+                //dirty handler anyway:
+                //swapBackingFile(currentDocument().path(), currentDocument());
+        }
+    }
 }
 
 DocumentInfo Document::documentInfo() const

core/generator.h

@@ -309,7 +309,7 @@ public:
 
     virtual bool canSign() const { return false; }
 
-    virtual void sign( const Okular::Annotation* /*pWhichAnnotation*/) { return; }
+    virtual bool sign( const Okular::Annotation* /*pWhichAnnotation*/, const QString& /*rFilename*/) { return false; }
 
     /**
      * This method can be called to trigger the generation of

generators/poppler/CMakeLists.txt

@@ -19,7 +19,7 @@ check_cxx_source_compiles("
 #include <poppler-qt5.h>
 int main()
 {
-  auto f = &Poppler::Document::sign;
+  auto f = &Poppler::PDFConverter::sign;
 }
 " HAVE_POPPLER_SIGNING)
 

generators/poppler/generator_pdf.cpp

@@ -1854,16 +1854,35 @@ Okular::AnnotationProxy *PDFGenerator::annotationProxy() const
     return annotProxy;
 }
 
-void PDFGenerator::sign( const Okular::Annotation* pWhichAnnotation )
+bool PDFGenerator::sign( const Okular::Annotation* pWhichAnnotation, const QString& rFilename )
 {
 #ifdef HAVE_POPPLER_SIGNING
     const Okular::WidgetAnnotation* wa = dynamic_cast<const Okular::WidgetAnnotation*>(pWhichAnnotation);
 
     Poppler::Annotation *popplerAnn = qvariant_cast< Poppler::Annotation * >( pWhichAnnotation->nativeId() );
-    pdfdoc->sign( popplerAnn, wa->certificateCN(), wa->password() );
+
+    // save to tmp file - poppler doesn't like overwriting in-place
+    QTemporaryFile tf(QDir::tempPath() + QLatin1String("/okular_XXXXXX.pdf"));
+    tf.setAutoRemove(false);
+    if (!tf.open())
+        return false;
+    std::unique_ptr<Poppler::PDFConverter> converter(
+        pdfdoc->pdfConverter());
+    converter->setOutputFileName(tf.fileName());
+    converter->setPDFOptions(converter->pdfOptions() | Poppler::PDFConverter::WithChanges);
+    if (!converter->sign( popplerAnn, wa->certificateCN(), QString(), wa->password(), QString()))
+        return false;
+
+    // now copy over old file
+    tf.remove(rFilename);
+    if (!tf.rename(rFilename))
+        return false;
 #else
     Q_UNUSED( pWhichAnnotation );
+    Q_UNUSED( rFilename );
 #endif
+
+    return true;
 }
 
 #include "generator_pdf.moc"

generators/poppler/generator_pdf.h

@@ -101,7 +101,7 @@ public:
     Okular::AnnotationProxy *annotationProxy() const override;
 
     bool canSign() const override {return true;}
-    void sign( const Okular::Annotation* pWhichAnnotation ) override;
+    bool sign( const Okular::Annotation* pWhichAnnotation, const QString& rFilename ) override;
 
 protected:
     SwapBackingFileResult swapBackingFile(QString const &newFileName, QVector<Okular::Page *> &newPagesVector) override;