working on adding check

src/dl-man.cpp

@@ -0,0 +1,116 @@
+
+// From Qt5 Examples/Docs
+
+#include"dl-man.h"
+
+DownloadManager::DownloadManager()
+{
+    connect(&manager, SIGNAL(finished(QNetworkReply*)),
+            SLOT(downloadFinished(QNetworkReply*)));
+}
+
+void DownloadManager::doDownload(const QUrl &url)
+{
+    QNetworkRequest request(url);
+    QNetworkReply *reply = manager.get(request);
+    
+#if QT_CONFIG(ssl)
+    connect(reply, SIGNAL(sslErrors(QList<QSslError>)),
+            SLOT(sslErrors(QList<QSslError>)));
+#endif
+    
+    currentDownloads.append(reply);
+}
+
+QString DownloadManager::saveFileName(const QUrl &url)
+{
+    QString path = url.path();
+    QString basename = QFileInfo(path).fileName();
+    
+    if (basename.isEmpty())
+        basename = "download";
+    
+    if (QFile::exists(basename)) {
+        // already exists, don't overwrite
+        int i = 0;
+        basename += '.';
+        while (QFile::exists(basename + QString::number(i)))
+            ++i;
+        
+        basename += QString::number(i);
+    }
+    
+    return basename;
+}
+
+bool DownloadManager::saveToDisk(const QString &filename, QIODevice *data)
+{
+    QFile file(filename);
+    if (!file.open(QIODevice::WriteOnly)) {
+        fprintf(stderr, "Could not open %s for writing: %s\n",
+                qPrintable(filename),
+                qPrintable(file.errorString()));
+        return false;
+    }
+    
+    file.write(data->readAll());
+    file.close();
+    
+    return true;
+}
+
+bool DownloadManager::isHttpRedirect(QNetworkReply *reply)
+{
+    int statusCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
+    return statusCode == 301 || statusCode == 302 || statusCode == 303
+    || statusCode == 305 || statusCode == 307 || statusCode == 308;
+}
+
+void DownloadManager::execute()
+{
+    QStringList args = QCoreApplication::instance()->arguments();
+    args.takeFirst();           // skip the first argument, which is the program's name
+    if (args.isEmpty()) {
+        QCoreApplication::instance()->quit();
+        return;
+    }
+    
+    for (const QString &arg : qAsConst(args)) {
+        QUrl url = QUrl::fromEncoded(arg.toLocal8Bit());
+        doDownload(url);
+    }
+}
+
+void DownloadManager::sslErrors(const QList<QSslError> &sslErrors)
+{
+#if QT_CONFIG(ssl)
+    for (const QSslError &error : sslErrors)
+        fprintf(stderr, "SSL error: %s\n", qPrintable(error.errorString()));
+#else
+    Q_UNUSED(sslErrors);
+#endif
+}
+
+void DownloadManager::downloadFinished(QNetworkReply *reply)
+{
+    QUrl url = reply->url();
+    if (reply->error()) {
+        fprintf(stderr, "Download of %s failed: %s\n",
+                url.toEncoded().constData(),
+                qPrintable(reply->errorString()));
+    } else {
+        if (isHttpRedirect(reply)) {
+            fputs("Request was redirected.\n", stderr);
+        } else {
+            QString filename = saveFileName(url);
+            if (saveToDisk(filename, reply)) {
+                printf("Download of %s succeeded (saved to %s)\n",
+                       url.toEncoded().constData(), qPrintable(filename));
+            }
+        }
+    }
+    
+    currentDownloads.removeAll(reply);
+    reply->deleteLater();
+}
+