Automatically migrate client mod storage (#11960)

src/client/client.cpp

@@ -50,6 +50,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "clientmap.h"
 #include "clientmedia.h"
 #include "version.h"
+#include "database/database-files.h"
 #include "database/database-sqlite3.h"
 #include "serialization.h"
 #include "guiscalingfilter.h"
@@ -140,6 +141,33 @@ Client::Client(
 	m_cache_save_interval = g_settings->getU16("server_map_save_interval");
 }
 
+void Client::migrateModStorage()
+{
+	std::string mod_storage_dir = porting::path_user + DIR_DELIM + "client";
+	std::string old_mod_storage = mod_storage_dir + DIR_DELIM + "mod_storage";
+	if (fs::IsDir(old_mod_storage)) {
+		infostream << "Migrating client mod storage to SQLite3 database" << std::endl;
+		{
+			ModMetadataDatabaseFiles files_db(mod_storage_dir);
+			std::vector<std::string> mod_list;
+			files_db.listMods(&mod_list);
+			for (const std::string &modname : mod_list) {
+				infostream << "Migrating client mod storage for mod " << modname << std::endl;
+				StringMap meta;
+				files_db.getModEntries(modname, &meta);
+				for (const auto &pair : meta) {
+					m_mod_storage_database->setModEntry(modname, pair.first, pair.second);
+				}
+			}
+		}
+		if (!fs::Rename(old_mod_storage, old_mod_storage + ".bak")) {
+			// Execution cannot move forward if the migration does not complete.
+			throw BaseException("Could not finish migrating client mod storage");
+		}
+		infostream << "Finished migration of client mod storage" << std::endl;
+	}
+}
+
 void Client::loadMods()
 {
 	// Don't load mods twice.

src/client/client.h

@@ -385,6 +385,9 @@ public:
 	bool registerModStorage(ModMetadata *meta) override;
 	void unregisterModStorage(const std::string &name) override;
 
+	// Migrates away old files-based mod storage if necessary
+	void migrateModStorage();
+
 	// The following set of functions is used by ClientMediaDownloader
 	// Insert a media file appropriately into the appropriate manager
 	bool loadMedia(const std::string &data, const std::string &filename,

src/client/game.cpp

@@ -1466,11 +1466,18 @@ bool Game::connectToServer(const GameStartData &start_data,
 		return false;
 	}
 
-	client = new Client(start_data.name.c_str(),
-			start_data.password, start_data.address,
-			*draw_control, texture_src, shader_src,
-			itemdef_manager, nodedef_manager, sound, eventmgr,
-			m_rendering_engine, connect_address.isIPv6(), m_game_ui.get());
+	try {
+		client = new Client(start_data.name.c_str(),
+				start_data.password, start_data.address,
+				*draw_control, texture_src, shader_src,
+				itemdef_manager, nodedef_manager, sound, eventmgr,
+				m_rendering_engine, connect_address.isIPv6(), m_game_ui.get());
+		client->migrateModStorage();
+	} catch (const BaseException &e) {
+		*error_message = fmtgettext("Error creating client: %s", e.what());
+		errorstream << *error_message << std::endl;
+		return false;
+	}
 
 	client->m_simple_singleplayer_mode = simple_singleplayer_mode;