Allow to save downloaded metadata as torrent file

src/base/bittorrent/session.cpp

@@ -3831,13 +3831,18 @@ void Session::handleTorrentMetadataReceived(TorrentHandle *const torrent)
     torrent->saveResumeData();
 
     // Save metadata
-    const QDir resumeDataDir(m_resumeFolderPath);
-    QString torrentFile = resumeDataDir.absoluteFilePath(QString("%1.torrent").arg(torrent->hash()));
-    if (torrent->saveTorrentFile(torrentFile)) {
+    const QDir resumeDataDir {m_resumeFolderPath};
+    const QString torrentFileName {QString {"%1.torrent"}.arg(torrent->hash())};
+    try {
+        torrent->info().saveToFile(resumeDataDir.absoluteFilePath(torrentFileName));
         // Copy the torrent file to the export folder
         if (!torrentExportDirectory().isEmpty())
             exportTorrentFile(torrent);
     }
+    catch (const RuntimeError &err) {
+        LogMsg(tr("Couldn't save torrent metadata file '%1'. Reason: %2")
+               .arg(torrentFileName, err.message()), Log::CRITICAL);
+    }
 
     emit torrentMetadataLoaded(torrent);
 }
@@ -4352,15 +4357,17 @@ void Session::createTorrentHandle(const lt::torrent_handle &nativeHandle)
         // The following is useless for newly added magnet
         if (!fromMagnetUri) {
             // Backup torrent file
-            const QDir resumeDataDir(m_resumeFolderPath);
-            const QString newFile = resumeDataDir.absoluteFilePath(QString("%1.torrent").arg(torrent->hash()));
-            if (torrent->saveTorrentFile(newFile)) {
+            const QDir resumeDataDir {m_resumeFolderPath};
+            const QString torrentFileName {QString {"%1.torrent"}.arg(torrent->hash())};
+            try {
+                torrent->info().saveToFile(resumeDataDir.absoluteFilePath(torrentFileName));
                 // Copy the torrent file to the export folder
                 if (!torrentExportDirectory().isEmpty())
                     exportTorrentFile(torrent);
             }
-            else {
-                LogMsg(tr("Couldn't save '%1.torrent'").arg(torrent->hash()), Log::CRITICAL);
+            catch (const RuntimeError &err) {
+                LogMsg(tr("Couldn't save torrent metadata file '%1'. Reason: %2")
+                       .arg(torrentFileName, err.message()), Log::CRITICAL);
             }
         }
 

src/base/bittorrent/torrenthandle.cpp

@@ -38,15 +38,16 @@
 
 #include <libtorrent/address.hpp>
 #include <libtorrent/alert_types.hpp>
-#include <libtorrent/bencode.hpp>
-#include <libtorrent/create_torrent.hpp>
 #include <libtorrent/entry.hpp>
 #include <libtorrent/magnet_uri.hpp>
 #include <libtorrent/time.hpp>
 #include <libtorrent/version.hpp>
 
 #if (LIBTORRENT_VERSION_NUM >= 10200)
+#include <libtorrent/storage_defs.hpp>
 #include <libtorrent/write_resume_data.hpp>
+#else
+#include <libtorrent/storage.hpp>
 #endif
 
 #include <QBitArray>
@@ -1533,29 +1534,6 @@ void TorrentHandle::renameFile(const int index, const QString &name)
     m_nativeHandle.rename_file(LTFileIndex {index}, Utils::Fs::toNativePath(name).toStdString());
 }
 
-bool TorrentHandle::saveTorrentFile(const QString &path)
-{
-    if (!m_torrentInfo.isValid()) return false;
-#if (LIBTORRENT_VERSION_NUM < 10200)
-    const lt::create_torrent torrentCreator = lt::create_torrent(*(m_torrentInfo.nativeInfo()), true);
-#else
-    const lt::create_torrent torrentCreator = lt::create_torrent(*(m_torrentInfo.nativeInfo()));
-#endif
-    const lt::entry torrentEntry = torrentCreator.generate();
-
-    QByteArray out;
-    out.reserve(1024 * 1024);  // most torrent file sizes are under 1 MB
-    lt::bencode(std::back_inserter(out), torrentEntry);
-    if (out.isEmpty())
-        return false;
-
-    QFile torrentFile(path);
-    if (torrentFile.open(QIODevice::WriteOnly))
-        return (torrentFile.write(out) == out.size());
-
-    return false;
-}
-
 void TorrentHandle::handleStateUpdate(const lt::torrent_status &nativeStatus)
 {
     updateStatus(nativeStatus);

src/base/bittorrent/torrenthandle.h

@@ -319,7 +319,6 @@ namespace BitTorrent
         void forceDHTAnnounce();
         void forceRecheck();
         void renameFile(int index, const QString &name);
-        bool saveTorrentFile(const QString &path);
         void prioritizeFiles(const QVector<DownloadPriority> &priorities);
         void setRatioLimit(qreal limit);
         void setSeedingTimeLimit(int limit);

src/base/bittorrent/torrentinfo.cpp

@@ -32,6 +32,8 @@
 #include <boost/optional.hpp>
 #endif
 
+#include <libtorrent/bencode.hpp>
+#include <libtorrent/create_torrent.hpp>
 #include <libtorrent/error_code.hpp>
 
 #include <QByteArray>
@@ -42,6 +44,7 @@
 #include <QStringList>
 #include <QUrl>
 
+#include "base/exceptions.h"
 #include "base/global.h"
 #include "base/utils/fs.h"
 #include "base/utils/misc.h"
@@ -151,6 +154,27 @@ TorrentInfo TorrentInfo::loadFromFile(const QString &path, QString *error) noexc
     return load(data, error);
 }
 
+void TorrentInfo::saveToFile(const QString &path) const
+{
+    if (!isValid())
+        throw RuntimeError {tr("Invalid metadata.")};
+
+#if (LIBTORRENT_VERSION_NUM < 10200)
+    const lt::create_torrent torrentCreator = lt::create_torrent(*(nativeInfo()), true);
+#else
+    const lt::create_torrent torrentCreator = lt::create_torrent(*(nativeInfo()));
+#endif
+    const lt::entry torrentEntry = torrentCreator.generate();
+
+    QByteArray out;
+    out.reserve(1024 * 1024);  // most torrent file sizes are under 1 MB
+    lt::bencode(std::back_inserter(out), torrentEntry);
+
+    QFile torrentFile{path};
+    if (!torrentFile.open(QIODevice::WriteOnly) || (torrentFile.write(out) != out.size()))
+        throw RuntimeError {torrentFile.errorString()};
+}
+
 bool TorrentInfo::isValid() const
 {
     return (m_nativeInfo && m_nativeInfo->is_valid() && (m_nativeInfo->num_files() > 0));

src/base/bittorrent/torrentinfo.h

@@ -66,6 +66,7 @@ namespace BitTorrent
 
         static TorrentInfo load(const QByteArray &data, QString *error = nullptr) noexcept;
         static TorrentInfo loadFromFile(const QString &path, QString *error = nullptr) noexcept;
+        void saveToFile(const QString &path) const;
 
         TorrentInfo &operator=(const TorrentInfo &other);