core/imagedownloader.cpp: remove recursion

If loading from hash failed in the saveImage() slot(!) it would
recurse into loadFromUrl(), which would generate a new network
reply. Very scary and a (small) wonder that it worked.

Let's try to make this all more explicit.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

2 files changed, 21 insertions, 18 deletions

diff --git a/core/imagedownloader.cpp b/core/imagedownloader.cpp
index 82ca53026..c3024764c 100644
--- a/core/imagedownloader.cpp
+++ b/core/imagedownloader.cpp
@@ -17,7 +17,6 @@ static QUrl cloudImageURL(const char *hash)
 ImageDownloader::ImageDownloader(struct picture *pic)
 {
 	picture = pic;
-	loadFromHash = false;
 }
 
 ImageDownloader::~ImageDownloader()
@@ -25,18 +24,24 @@ ImageDownloader::~ImageDownloader()
 	picture_free(picture);
 }
 
-void ImageDownloader::load(bool fromHash){
-	QUrl url;
-	loadFromHash = fromHash;
-	if(fromHash)
-		url = cloudImageURL(picture->hash);
-	else
-		url = QUrl::fromUserInput(QString(picture->filename));
+void ImageDownloader::load(bool fromHash)
+{
+	if (fromHash && loadFromUrl(cloudImageURL(picture->hash)))
+		return;
+
+	// If loading from hash failed, try to load from filename
+	loadFromUrl(QUrl::fromUserInput(QString(picture->filename)));
+}
+
+bool ImageDownloader::loadFromUrl(const QUrl &url)
+{
+	bool success = false;
 	if (url.isValid()) {
 		QEventLoop loop;
 		QNetworkAccessManager manager;
 		QNetworkRequest request(url);
-		connect(&manager, SIGNAL(finished(QNetworkReply *)), this, SLOT(saveImage(QNetworkReply *)));
+		connect(&manager, &QNetworkAccessManager::finished, this,
+			[this,&success] (QNetworkReply *reply) { saveImage(reply, success); });
 		QNetworkReply *reply = manager.get(request);
 		while (reply->isRunning()) {
 			loop.processEvents();
@@ -44,18 +49,18 @@ void ImageDownloader::load(bool fromHash){
 		}
 		delete reply;
 	}
+	return success;
 }
 
-void ImageDownloader::saveImage(QNetworkReply *reply)
+void ImageDownloader::saveImage(QNetworkReply *reply, bool &success)
 {
+	success = false;
 	QByteArray imageData = reply->readAll();
 	QImage image = QImage();
 	image.loadFromData(imageData);
-	if (image.isNull()) {
-		if (loadFromHash)
-			load(false);
+	if (image.isNull())
 		return;
-	}
+	success = true;
 	QCryptographicHash hash(QCryptographicHash::Sha1);
 	hash.addData(imageData);
 	QString path = QStandardPaths::standardLocations(QStandardPaths::CacheLocation).first();
diff --git a/core/imagedownloader.h b/core/imagedownloader.h
index 295b664f4..be196aaef 100644
--- a/core/imagedownloader.h
+++ b/core/imagedownloader.h
@@ -14,11 +14,9 @@ public:
 	void load(bool fromHash);
 
 private:
+	bool loadFromUrl(const QUrl &);	// return true on success
+	void saveImage(QNetworkReply *reply, bool &success);
 	struct picture *picture;
-	bool loadFromHash;
-
-private slots:
-	void saveImage(QNetworkReply *reply);
 };
 
 class SHashedImage : public QImage {