IOS7: Save state to a separate file when closing ScummVM

The state information was saved using ConfMan in the scummvm ini file,
but this could cause corruption of that ini file if the application
was killed while ConfMan was flushed (see bug #14623). To reduce the
risk of losing the config file, we now save the state to a separate
file.

backends/platform/ios7/ios7_osys_main.cpp

@@ -24,6 +24,7 @@
 
 #include <unistd.h>
 #include <string.h>
+#include <stdio.h>
 
 #include <sys/time.h>
 #include <QuartzCore/QuartzCore.h>
@@ -36,6 +37,7 @@
 #include "common/fs.h"
 #include "common/config-manager.h"
 #include "common/translation.h"
+#include "common/formats/ini-file.h"
 
 #include "base/main.h"
 
@@ -280,49 +282,64 @@ void OSystem_iOS7::saveState() {
 	if (g_engine && g_engine->hasFeature(Engine::kSupportsSavingDuringRuntime) && g_engine->canSaveAutosaveCurrently()) {
 		Common::String targetName(ConfMan.getActiveDomainName());
 		int saveSlot = g_engine->getAutosaveSlot();
+		if (saveSlot == -1)
+			return;
 		// Make sure we do not overwrite a user save
 		SaveStateDescriptor desc = g_engine->getMetaEngine()->querySaveMetaInfos(targetName.c_str(), saveSlot);
 		if (desc.getSaveSlot() != -1 && !desc.isAutosave())
 			return;
 
-		// Do the auto-save, and if successful store this it in the config
+		// Do the auto-save, and if successful store this it in the uset settings
 		if (g_engine->saveGameState(saveSlot, _("Autosave"), true).getCode() == Common::kNoError) {
-			ConfMan.set("restore_target", targetName, Common::ConfigManager::kApplicationDomain);
-			ConfMan.setInt("restore_slot", saveSlot, Common::ConfigManager::kApplicationDomain);
-			ConfMan.flushToDisk();
+			Common::INIFile stateFile;
+			stateFile.addSection("state");
+			stateFile.setKey("restore_target", "state", targetName);
+			stateFile.setKey("restore_slot", "state", Common::String::format("%d", saveSlot));
+			stateFile.saveToFile("/scummvm.state");
 		}
 	}
 }
 
 void OSystem_iOS7::restoreState() {
-	Common::String target;
-	int slot = -1;
-	if (ConfMan.hasKey("restore_target", Common::ConfigManager::kApplicationDomain) &&
-		ConfMan.hasKey("restore_slot", Common::ConfigManager::kApplicationDomain)) {
-		target = ConfMan.get("restore_target", Common::ConfigManager::kApplicationDomain);
-		slot = ConfMan.getInt("restore_slot", Common::ConfigManager::kApplicationDomain);
+	// If the g_engine is still running (i.e. the application was not terminated) we don't need to do anything other than clear the saved state.
+	if (g_engine) {
 		clearState();
+		return;
 	}
 
-	// If the g_engine is still running (i.e. the application was not terminated) we don't need to do anything.
-	if (g_engine)
+	// Read the state
+	Common::FSNode node("/scummvm.state");
+	Common::File stateFile;
+	if (!stateFile.open(node))
 		return;
 
-	if (!target.empty() && slot != -1) {
-		ConfMan.setInt("save_slot", slot, Common::ConfigManager::kTransientDomain);
-		ConfMan.setActiveDomain(target);
+	Common::String targetName, slotString;
+	int saveSlot = -1;
+	Common::INIFile stateIniFile;
+	if (stateIniFile.loadFromStream(stateFile) &&
+		stateIniFile.getKey("restore_target", "state", targetName) &&
+		stateIniFile.getKey("restore_slot", "state", slotString) &&
+		!slotString.empty()) {
+		char *errpos;
+		saveSlot = (int)strtol(slotString.c_str(), &errpos, 10);
+		if (slotString.c_str() == errpos)
+			saveSlot = -1;
+	}
+
+	clearState();
+
+	// Reload the state
+	if (!targetName.empty() && saveSlot != -1) {
+		ConfMan.setInt("save_slot", saveSlot, Common::ConfigManager::kTransientDomain);
+		ConfMan.setActiveDomain(targetName);
 		if (GUI::GuiManager::hasInstance())
 			g_gui.exitLoop();
 	}
 }
 
 void OSystem_iOS7::clearState() {
-	if (ConfMan.hasKey("restore_target", Common::ConfigManager::kApplicationDomain) &&
-	ConfMan.hasKey("restore_slot", Common::ConfigManager::kApplicationDomain)) {
-		ConfMan.removeKey("restore_target", Common::ConfigManager::kApplicationDomain);
-		ConfMan.removeKey("restore_slot", Common::ConfigManager::kApplicationDomain);
-		ConfMan.flushToDisk();
-	}
+	Common::String statePath = _chrootBasePath + "/scummvm.state";
+	remove(statePath.c_str());
 }
 
 uint32 OSystem_iOS7::getMillis(bool skipRecord) {