Spawn: prune non-{C:,Z:} drive letters from prefix at launch

Wine canonicalises paths against the dosdevices map and prefers the most
specific (longest-prefix) drive letter.  An external symlink such as
dosdevices/x: -> /home/<user> turns every Z:\home\<user>\... binary path
into X:\..., which confuses tools and obscures launch logs.

PrefixSetupRunner::stepDriveCleanup already enforces the {C:, Z:} policy
but only runs as part of the explicit prefix-setup pipeline; drives
added later (Faugus, manual edits, modlist installers) survive forever.
Mirror that cleanup at launch in spawn.cpp's pruneExtraDrives() so every
Proton launch sees a known-good dosdevices layout.

1 files changed, 42 insertions, 0 deletions

diff --git a/src/src/spawn.cpp b/src/src/spawn.cpp
index 8e97ed0..9d4d8f2 100644
--- a/src/src/spawn.cpp
+++ b/src/src/spawn.cpp
@@ -27,7 +27,10 @@ along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
 #include "settingsdialogworkarounds.h"

 #include "shared/appconfig.h"

 #include <QApplication>

+#include <QDir>

+#include <QFile>

 #include <QMessageBox>

+#include <QSet>

 #include <QSettings>

 #include <QtDebug>

 #include <uibase/errorcodes.h>

@@ -517,6 +520,44 @@ QString firstExistingSetting(const QSettings &settings,
   return {};

 }

 

+// Remove dosdevices/<letter>: symlinks for any drive other than C: and Z:.

+// External tooling (Faugus, manual edits, modlist installers) can re-add

+// drives like X: that map subtrees of the host filesystem; Wine then prefers

+// the more specific drive when canonicalising paths, which mangles binary

+// paths we passed in as Z:\... into X:\...  Keeping this list minimal means

+// MO2 can rely on Z: being the only host-mapped drive.

+void pruneExtraDrives(const QString &prefixPath) {

+  static const QSet<QString> kept = {QStringLiteral("c:"), QStringLiteral("z:")};

+

+  const QString dosdevices = QDir(prefixPath).filePath("dosdevices");

+  QDir dir(dosdevices);

+  if (!dir.exists()) {

+    return;

+  }

+

+  QStringList removed;

+  for (const QString &entry :

+       dir.entryList(QDir::NoDotAndDotDot | QDir::AllEntries)) {

+    const QString lower = entry.toLower();

+    if (lower.length() != 2 || !lower.endsWith(':') ||

+        !lower.at(0).isLetter()) {

+      continue;

+    }

+    if (kept.contains(lower)) {

+      continue;

+    }

+    if (QFile::remove(dir.filePath(entry))) {

+      removed << entry.toUpper();

+    }

+  }

+

+  if (!removed.isEmpty()) {

+    MOBase::log::info(

+        "Pruned stale drive letters from prefix '{}': {}", prefixPath,

+        removed.join(QStringLiteral(", ")).toStdString());

+  }

+}

+

 QString resolvePrefixPath() {

   // The Fluorine config is authoritative: it's the prefix the user

   // explicitly created through Settings > Proton and that Fluorine itself

@@ -702,6 +743,7 @@ int spawn(const SpawnParameters &sp, pid_t &processId) {
       return ENOENT;

     } else {

       MOBase::log::info("Using Wine prefix: {}", prefixPath);

+      pruneExtraDrives(prefixPath);

       launcher.setPrefix(prefixPath);

     }