Block unique-subfolder migration when target files exist

Refuse conversion when any destination file path already exists (libtorrent
may not overwrite). Empty unique directories and unrelated files are fine.
Partial retries map under the unique root without double-wrapping. Drop
setName on success and remove unreleased append_hash resume compatibility.

Author: gl00ten

src/base/bittorrent/bencoderesumedatastorage.cpp

@@ -285,10 +285,6 @@ BitTorrent::LoadResumeDataResult BitTorrent::BencodeResumeDataStorage::loadTorre
     //                fromLTString(root.dict_find_string_value("qBt-contentLayout")), TorrentContentLayout::Default);
     // === END REPLACEMENT CODE === //
 
-    // Legacy flag from intermediate builds; content_layout is source of truth now.
-    if (resumeDataRoot.dict_find_int_value("qBt-appendHashToPayloadName"))
-        torrentParams.contentLayout = TorrentContentLayout::UniqueSubfolder;
-
     torrentParams.stopCondition = Utils::String::toEnum(
             fromLTString(resumeDataRoot.dict_find_string_value("qBt-stopCondition")), Torrent::StopCondition::None);
     torrentParams.sslParameters =

src/base/bittorrent/dbresumedatastorage.cpp

@@ -72,7 +72,7 @@ namespace
 {
     const QString DB_CONNECTION_NAME = u"ResumeDataStorage"_s;
 
-    const int DB_VERSION = 11;
+    const int DB_VERSION = 10;
 
     const QString DB_TABLE_META = u"meta"_s;
     const QString DB_TABLE_TORRENTS = u"torrents"_s;
@@ -147,7 +147,6 @@ namespace
     const Column DB_COLUMN_SHARE_LIMIT_ACTION = makeColumn(u"share_limit_action"_s);
     const Column DB_COLUMN_HAS_OUTER_PIECES_PRIORITY = makeColumn(u"has_outer_pieces_priority"_s);
     const Column DB_COLUMN_HAS_SEED_STATUS = makeColumn(u"has_seed_status"_s);
-    const Column DB_COLUMN_APPEND_HASH_TO_PAYLOAD_NAME = makeColumn(u"append_hash_to_payload_name"_s);
     const Column DB_COLUMN_OPERATING_MODE = makeColumn(u"operating_mode"_s);
     const Column DB_COLUMN_STOPPED = makeColumn(u"stopped"_s);
     const Column DB_COLUMN_STOP_CONDITION = makeColumn(u"stop_condition"_s);
@@ -480,7 +479,6 @@ void BitTorrent::DBResumeDataStorage::createDB() const
             makeColumnDefinition(DB_COLUMN_SHARE_LIMIT_ACTION, u"TEXT NOT NULL DEFAULT `Default`"_s),
             makeColumnDefinition(DB_COLUMN_HAS_OUTER_PIECES_PRIORITY, u"INTEGER NOT NULL"_s),
             makeColumnDefinition(DB_COLUMN_HAS_SEED_STATUS, u"INTEGER NOT NULL"_s),
-            makeColumnDefinition(DB_COLUMN_APPEND_HASH_TO_PAYLOAD_NAME, u"INTEGER NOT NULL DEFAULT 0"_s),
             makeColumnDefinition(DB_COLUMN_OPERATING_MODE, u"TEXT NOT NULL"_s),
             makeColumnDefinition(DB_COLUMN_STOPPED, u"INTEGER NOT NULL"_s),
             makeColumnDefinition(DB_COLUMN_STOP_CONDITION, u"TEXT NOT NULL DEFAULT `None`"_s),
@@ -595,9 +593,6 @@ void BitTorrent::DBResumeDataStorage::updateDB(const int fromVersion) const
         if (fromVersion <= 9)
             addColumn(DB_TABLE_TORRENTS, DB_COLUMN_SHARE_LIMITS_MODE, u"TEXT NOT NULL DEFAULT `Default`"_s);
 
-        if (fromVersion <= 10)
-            addColumn(DB_TABLE_TORRENTS, DB_COLUMN_APPEND_HASH_TO_PAYLOAD_NAME, u"INTEGER NOT NULL DEFAULT 0"_s);
-
         const QString updateMetaVersionQuery = makeUpdateStatement(DB_TABLE_META, {DB_COLUMN_NAME, DB_COLUMN_VALUE});
         if (!query.prepare(updateMetaVersionQuery))
             throw RuntimeError(query.lastError().text());
@@ -657,9 +652,6 @@ LoadResumeDataResult DBResumeDataStorage::parseQueryResultRow(const QSqlQuery &q
     };
     resumeData.contentLayout = Utils::String::toEnum<TorrentContentLayout>(
             query.value(DB_COLUMN_CONTENT_LAYOUT.name).toString(), TorrentContentLayout::Original);
-    // Legacy column (pre-UniqueSubfolder layout enum); content_layout is source of truth now.
-    if (query.value(DB_COLUMN_APPEND_HASH_TO_PAYLOAD_NAME.name).toBool())
-        resumeData.contentLayout = TorrentContentLayout::UniqueSubfolder;
     resumeData.operatingMode = Utils::String::toEnum<TorrentOperatingMode>(
         query.value(DB_COLUMN_OPERATING_MODE.name).toString(), TorrentOperatingMode::AutoManaged);
     resumeData.stopped = query.value(DB_COLUMN_STOPPED.name).toBool();
@@ -881,7 +873,6 @@ StoreJob::StoreJob(const TorrentID &torrentID, LoadTorrentParams resumeData)
             DB_COLUMN_SHARE_LIMIT_ACTION,
             DB_COLUMN_HAS_OUTER_PIECES_PRIORITY,
             DB_COLUMN_HAS_SEED_STATUS,
-            DB_COLUMN_APPEND_HASH_TO_PAYLOAD_NAME,
             DB_COLUMN_OPERATING_MODE,
             DB_COLUMN_STOPPED,
             DB_COLUMN_STOP_CONDITION,
@@ -947,8 +938,6 @@ StoreJob::StoreJob(const TorrentID &torrentID, LoadTorrentParams resumeData)
             query.bindValue(DB_COLUMN_SHARE_LIMIT_ACTION.placeholder, Utils::String::fromEnum(m_resumeData.shareLimits.action));
             query.bindValue(DB_COLUMN_HAS_OUTER_PIECES_PRIORITY.placeholder, m_resumeData.firstLastPiecePriority);
             query.bindValue(DB_COLUMN_HAS_SEED_STATUS.placeholder, m_resumeData.hasFinishedStatus);
-            // Column kept for schema compatibility; always 0. Layout is in content_layout.
-            query.bindValue(DB_COLUMN_APPEND_HASH_TO_PAYLOAD_NAME.placeholder, false);
             query.bindValue(DB_COLUMN_OPERATING_MODE.placeholder, Utils::String::fromEnum(m_resumeData.operatingMode));
             query.bindValue(DB_COLUMN_STOPPED.placeholder, m_resumeData.stopped);
             query.bindValue(DB_COLUMN_STOP_CONDITION.placeholder, Utils::String::fromEnum(m_resumeData.stopCondition));

src/base/bittorrent/toplevelpayload.cpp

@@ -111,6 +111,31 @@ namespace
 
         return base;
     }
+
+    // Path without its first component (or the path itself when single-component).
+    Path payloadRelativePath(const Path &path)
+    {
+        const QString s = path.data();
+        const qsizetype slash = s.indexOf(u'/');
+        if (slash < 0)
+            return path;
+        return Path(s.sliced(slash + 1));
+    }
+
+    // Map each path under uniqueRoot without double-wrapping paths already there.
+    PathList mapUnderUniqueRoot(const PathList &filePaths, const Path &uniqueRoot)
+    {
+        PathList out;
+        out.reserve(filePaths.size());
+        for (const Path &path : filePaths)
+        {
+            if ((path == uniqueRoot) || path.hasAncestor(uniqueRoot))
+                out.append(path);
+            else
+                out.append(uniqueRoot / payloadRelativePath(path));
+        }
+        return out;
+    }
 }
 
 QString BitTorrent::uniqueSubfolderTag(const TorrentID &id)
@@ -130,18 +155,20 @@ PathList BitTorrent::applyUniqueSubfolderLayout(PathList filePaths, const Torren
 
     const QString tag = uniqueSubfolderTag(id);
     const QString folderName = uniqueSubfolderName(id, originalNameForUniqueDir(filePaths, torrentName, tag));
+    const Path uniqueRoot {folderName};
 
+    // Uniform layout: common root rename, or wrap rootless/single-file.
+    // Mixed (partial migration) is handled by mapUnderUniqueRoot so paths already
+    // under uniqueRoot are left alone.
     const Path rootFolder = Path::findRootFolder(filePaths);
     if (!rootFolder.isEmpty())
     {
-        if (rootFolder.toString() == folderName)
+        if (rootFolder == uniqueRoot)
             return filePaths;
         return renameRootFolder(std::move(filePaths), rootFolder.toString(), folderName);
     }
 
-    // Single file or rootless multi-file: wrap under the unique folder.
-    Path::addRootFolder(filePaths, Path(folderName));
-    return filePaths;
+    return mapUnderUniqueRoot(filePaths, uniqueRoot);
 }
 
 BitTorrent::UniqueSubfolderMigrationPlan BitTorrent::makeUniqueSubfolderMigrationPlan(
@@ -152,37 +179,45 @@ BitTorrent::UniqueSubfolderMigrationPlan BitTorrent::makeUniqueSubfolderMigratio
     if (currentPaths.isEmpty())
         return plan;
 
-    const PathList targetPaths = applyUniqueSubfolderLayout(currentPaths, id, torrentName);
-    if (targetPaths == currentPaths)
-        return plan;
-
     if (storageRoot.isEmpty())
     {
         plan.blocked = true;
         plan.blockReason = QCoreApplication::translate("BitTorrent", "Storage location is unknown.");
         return plan;
     }
 
-    const Path uniqueDir = Path::findRootFolder(targetPaths);
-    if (uniqueDir.isEmpty())
+    // Always derive the unique folder from the torrent name (stable across partial states).
+    const QString tag = uniqueSubfolderTag(id);
+    const Path uniqueRoot {uniqueSubfolderName(id, originalNameForUniqueDir(currentPaths, torrentName, tag))};
+    if (uniqueRoot.isEmpty())
     {
         plan.blocked = true;
         plan.blockReason = QCoreApplication::translate("BitTorrent", "Target unique subfolder is invalid.");
         return plan;
     }
 
+    const PathList targetPaths = mapUnderUniqueRoot(currentPaths, uniqueRoot);
+
     for (int i = 0; i < targetPaths.size(); ++i)
     {
-        if (targetPaths.at(i) != currentPaths.at(i))
-            plan.renames.append({.fileIndex = i, .to = targetPaths.at(i)});
-    }
-    if (plan.renames.isEmpty())
-        return plan;
+        if (targetPaths.at(i) == currentPaths.at(i))
+            continue;
 
-    // Existing destination: do not block. UI may confirm a merge (overwrite matching paths only).
-    const Path destAbs = storageRoot / uniqueDir;
-    if (destAbs.exists())
-        plan.existingUniqueFolder = destAbs;
+        // Refuse if the destination *file* already exists. Existing directories are fine.
+        // Unrelated files under the unique folder that are not rename targets are left alone.
+        const Path targetAbs = storageRoot / targetPaths.at(i);
+        if (targetAbs.exists() && !Utils::Fs::isDir(targetAbs))
+        {
+            plan.blocked = true;
+            plan.blockReason = QCoreApplication::translate("BitTorrent"
+                    , "Migration cannot continue: destination file already exists: \"%1\".")
+                    .arg(targetPaths.at(i).toString());
+            plan.renames.clear();
+            return plan;
+        }
+
+        plan.renames.append({.fileIndex = i, .to = targetPaths.at(i)});
+    }
 
     return plan;
 }

src/base/bittorrent/toplevelpayload.h

@@ -47,26 +47,17 @@ namespace BitTorrent
     };
 
     // Preflight only — no disk changes.
-    // When existingUniqueFolder is set, the UI should confirm a merge before start.
+    // If any absolute target *file* already exists, blocked is set (directories are OK).
     struct UniqueSubfolderMigrationPlan
     {
         QList<UniqueSubfolderRename> renames;
-
-        // Absolute path of an existing unique destination (empty if none).
-        Path existingUniqueFolder;
-
         bool blocked = false;
         QString blockReason;
 
         bool isEmpty() const
         {
             return renames.isEmpty() && !blocked;
         }
-
-        bool needsConfirmation() const
-        {
-            return !existingUniqueFolder.isEmpty();
-        }
     };
 
     // Pure preflight used by TorrentImpl and unit tests.

src/base/bittorrent/torrentimpl.cpp

@@ -2949,12 +2949,7 @@ void TorrentImpl::finishUniqueSubfolderMigration()
 
     const bool success = job.failedFileIndexes.isEmpty();
     if (success)
-    {
         m_contentLayout = TorrentContentLayout::UniqueSubfolder;
-        const Path uniqueRoot = Path::findRootFolder(filePaths());
-        if (!uniqueRoot.isEmpty())
-            setName(uniqueRoot.toString());
-    }
 
     deferredRequestResumeData();
 

src/gui/optionsdialog.cpp

@@ -588,7 +588,7 @@ void OptionsDialog::loadDownloadsTabOptions()
             + tr("Put content in a unique folder with a short hash suffix (e.g. Show a19f83c275d1). "
                  "Avoids name collisions; breaks path-based cross-seeding. "
                  "Existing torrents stay as-is until converted via right-click "
-                 "(if the folder already exists, you can confirm a merge that replaces matching files).")
+                 "(migration stops if matching destination files already exist).")
             + u"</p><p><b>" + tr("Don't create subfolder") + u"</b> - "
             + tr("Put files directly in the save path.")
             + u"</p></body></html>");

src/gui/transferlistwidget.cpp

@@ -982,24 +982,6 @@ void TransferListWidget::createUniqueSubfolderForSelectedTorrents()
         if (plan.isEmpty())
             return;
 
-        // Merge if the unique folder already exists (overwrite matching paths only).
-        if (plan.needsConfirmation())
-        {
-            const QString text = tr(
-                    "Torrent: \"%1\"\n\n"
-                    "The unique subfolder already exists. Continuing will merge the torrent into it "
-                    "and replace files with matching paths. Other files will not be removed.")
-                    .arg(torrent->name());
-
-            const QMessageBox::StandardButton answer = QMessageBox::warning(this
-                    , tr("Create unique subfolder")
-                    , text
-                    , (QMessageBox::Ok | QMessageBox::Cancel)
-                    , QMessageBox::Cancel);
-            if (answer != QMessageBox::Ok)
-                return;
-        }
-
         connect(torrent, &BitTorrent::Torrent::uniqueSubfolderMigrationFinished, this
                 , [this](const bool success, const QString &message)
         {
@@ -1095,7 +1077,7 @@ void TransferListWidget::displayListMenu()
             , tr("Create &unique subfolder"), listMenu);
     actionCreateUniqueSubfolder->setToolTip(tr(
             "Move selected torrents into a unique folder (e.g. Show a19f83c275d1). "
-            "If that folder already exists, matching files may be overwritten after confirmation."));
+            "If matching destination files already exist, migration cannot continue."));
     connect(actionCreateUniqueSubfolder, &QAction::triggered, this, &TransferListWidget::createUniqueSubfolderForSelectedTorrents);
     auto *actionSequentialDownload = new TriStateAction(tr("Download in sequential order"), listMenu);
     connect(actionSequentialDownload, &QAction::triggered, this, &TransferListWidget::setSelectedTorrentsSequentialDownload);