MemStickScreen: Don't blame the folder after the data has moved

If switching failed after the data was moved, the screen said the folder
doesn't work as a memory stick, though the data was already in it.

The switch's checks (the new folder and the one holding memstick_dir.txt
are writable) now run before anything is moved, where that message is
accurate. If the switch still fails after a move, a new message says the
data is in the new folder, and OK only retries the switch.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Core/Util/MemStick.cpp

@@ -172,23 +172,43 @@ MemstickFolderCheck CheckNewMemstickFolder(const Path &newFolder, const Path &cu
 	return MemstickFolderCheck::OK;
 }
 
-bool SwitchMemstickFolderTo(Path newMemstickFolder) {
+static bool CanWriteTo(const Path &folder) {
+	const Path testWriteFile = folder / ".write_verify_file";
+	if (!File::WriteDataToFile(true, "1", 1, testWriteFile)) {
+		return false;
+	}
+	File::Delete(testWriteFile);
+	return true;
+}
+
+bool CanSwitchMemstickFolderTo(const Path &newMemstickFolder) {
 	// Doesn't already exist, create.
 	// Should this ever happen?
 	if (newMemstickFolder.Type() == PathType::NATIVE) {
 		if (!File::Exists(newMemstickFolder)) {
 			File::CreateFullPath(newMemstickFolder);
 		}
-		Path testWriteFile = newMemstickFolder / ".write_verify_file";
-		if (!File::WriteDataToFile(true, "1", 1, testWriteFile)) {
+		if (!CanWriteTo(newMemstickFolder)) {
+			ERROR_LOG(Log::System, "Can't write to '%s'", newMemstickFolder.c_str());
 			return false;
 		}
-		File::Delete(testWriteFile);
 	} else {
 		// TODO: Do the same but with scoped storage? Not really necessary, right? If it came from a browse
 		// for folder, we can assume it exists and is writable, barring wacky race conditions like the user
 		// being connected by USB and deleting it.
 	}
+	// Where memstick_dir.txt goes. Not set on desktops, which only get here through a debug start screen.
+	if (!g_Config.internalDataDirectory.empty() && !CanWriteTo(g_Config.internalDataDirectory)) {
+		ERROR_LOG(Log::System, "Can't write to '%s'", g_Config.internalDataDirectory.c_str());
+		return false;
+	}
+	return true;
+}
+
+bool SwitchMemstickFolderTo(Path newMemstickFolder) {
+	if (!CanSwitchMemstickFolderTo(newMemstickFolder)) {
+		return false;
+	}
 
 	Path memStickDirFile = g_Config.internalDataDirectory / "memstick_dir.txt";
 #if PPSSPP_PLATFORM(UWP)

Core/Util/MemStick.h

@@ -48,5 +48,7 @@ enum class MemstickFolderCheck {
 MemstickFolderCheck CheckNewMemstickFolder(const Path &newFolder, const Path &currentFolder);
 
 bool FolderSeemsToBeUsed(const Path &newMemstickFolder);
+// The checks SwitchMemstickFolderTo() starts with, to run before moving any data.
+bool CanSwitchMemstickFolderTo(const Path &newMemstickFolder);
 bool SwitchMemstickFolderTo(Path newMemstickFolder);
 MoveResult *MoveDirectoryContentsSafe(Path moveSrc, Path moveDest, MoveProgressReporter &progressReporter);

UI/MemStickScreen.cpp

@@ -551,7 +551,7 @@ void ConfirmMemstickMoveScreen::CreateViews() {
 	}
 
 	if (!error_.empty()) {
-		leftColumn->Add(new TextView(error_, ALIGN_LEFT, false));
+		leftColumn->Add(new TextView(error_, ALIGN_LEFT | FLAG_WRAP_TEXT, false));
 	}
 
 	if (!oldMemstickFolder.empty()) {
@@ -566,7 +566,7 @@ void ConfirmMemstickMoveScreen::CreateViews() {
 	}
 
 	if (!moveDataTask_) {
-		if (!initialSetup_ && CanMoveData()) {
+		if (!initialSetup_ && CanMoveData() && !dataMoved_) {
 			leftColumn->Add(new CheckBox(&moveData_, ms->T("Move Data")))->OnClick.Handle(this, &ConfirmMemstickMoveScreen::OnMoveDataClick);
 		}
 
@@ -611,7 +611,9 @@ void ConfirmMemstickMoveScreen::update() {
 			if (result->success) {
 				progressReporter_.SetProgress(T(I18NCat::DIALOG, "Done!"));
 				INFO_LOG(Log::System, "Move data task finished successfully!");
-				// Succeeded!
+				// Succeeded! If the switch below fails, OK only retries the switch.
+				dataMoved_ = true;
+				moveData_ = false;
 				FinishFolderMove();
 			} else {
 				progressReporter_.SetProgress(ms->T("Failed to move some files!"));
@@ -639,7 +641,20 @@ void ConfirmMemstickMoveScreen::OnConfirm(UI::EventParams &params) {
 	// Should probably be done on a background thread so we can show some UI.
 	// So we probably need another screen for this with a progress bar..
 	// If the directory itself is called PSP, don't go below.
-	if (IsBlocked()) {
+	if (IsBlocked() || moveDataTask_) {
+		return;
+	}
+
+	// Only the switch is left to retry, and its own failure message says the data moved.
+	if (dataMoved_) {
+		FinishFolderMove();
+		return;
+	}
+
+	// Find out now if the switch would fail, rather than after moving the data away.
+	if (!CanSwitchMemstickFolderTo(newMemstickFolder_)) {
+		error_ = T(I18NCat::MEMSTICK, "That folder doesn't work as a memstick folder.");
+		RecreateViews();
 		return;
 	}
 
@@ -667,8 +682,11 @@ void ConfirmMemstickMoveScreen::FinishFolderMove() {
 
 	// Successful so far, switch the memstick folder.
 	if (!SwitchMemstickFolderTo(newMemstickFolder_)) {
-		// TODO: More precise errors.
-		error_ = ms->T("That folder doesn't work as a memstick folder.");
+		if (dataMoved_) {
+			error_ = ms->T("DataMovedButNotSwitched", "Your data was moved to the new folder, but PPSSPP couldn't switch to it. Please try again.");
+		} else {
+			error_ = ms->T("That folder doesn't work as a memstick folder.");
+		}
 		RecreateViews();
 		return;
 	}

UI/MemStickScreen.h

@@ -134,6 +134,8 @@ private:
 	bool moveData_ = true;
 #endif
 	bool initialSetup_;
+	// The data is already in the new folder.
+	bool dataMoved_ = false;
 
 	MoveProgressReporter progressReporter_;
 	UI::TextView *progressView_ = nullptr;