monitor: fix crash on mutating workspace vec

fixes #11236

3 files changed, 15 insertions, 4 deletions

diff --git a/src/Compositor.cpp b/src/Compositor.cpp
index 14f9ee63..e00c8c36 100644
--- a/src/Compositor.cpp
+++ b/src/Compositor.cpp
@@ -2692,6 +2692,16 @@ void CCompositor::registerWorkspace(PHLWORKSPACE w) {
     w->m_events.destroy.listenStatic([this, weak = PHLWORKSPACEREF{w}] { std::erase(m_workspaces, weak); });
 }
 
+std::vector<PHLWORKSPACE> CCompositor::getWorkspacesCopy() {
+    std::vector<PHLWORKSPACE> wsp;
+    auto                      range = getWorkspaces();
+    wsp.reserve(std::ranges::distance(range));
+    for (auto& r : range) {
+        wsp.emplace_back(r.lock());
+    }
+    return wsp;
+}
+
 void CCompositor::performUserChecks() {
     static auto PNOCHECKXDG     = CConfigValue<Hyprlang::INT>("misc:disable_xdg_env_checks");
     static auto PNOCHECKQTUTILS = CConfigValue<Hyprlang::INT>("misc:disable_hyprland_qtutils_check");
diff --git a/src/Compositor.hpp b/src/Compositor.hpp
index c76a73b2..d18b5a93 100644
--- a/src/Compositor.hpp
+++ b/src/Compositor.hpp
@@ -79,7 +79,8 @@ class CCompositor {
     auto getWorkspaces() {
         return std::views::filter(m_workspaces, [](const auto& e) { return e; });
     }
-    void registerWorkspace(PHLWORKSPACE w);
+    std::vector<PHLWORKSPACE> getWorkspacesCopy();
+    void                      registerWorkspace(PHLWORKSPACE w);
 
     //
 
diff --git a/src/helpers/Monitor.cpp b/src/helpers/Monitor.cpp
index 63f1d147..87990009 100644
--- a/src/helpers/Monitor.cpp
+++ b/src/helpers/Monitor.cpp
@@ -216,12 +216,12 @@ void CMonitor::onConnect(bool noRule) {
 
     setupDefaultWS(monitorRule);
 
-    for (auto const& ws : g_pCompositor->getWorkspaces()) {
-        if (!valid(ws.lock()))
+    for (auto const& ws : g_pCompositor->getWorkspacesCopy()) {
+        if (!valid(ws))
             continue;
 
         if (ws->m_lastMonitor == m_name || g_pCompositor->m_monitors.size() == 1 /* avoid lost workspaces on recover */) {
-            g_pCompositor->moveWorkspaceToMonitor(ws.lock(), m_self.lock());
+            g_pCompositor->moveWorkspaceToMonitor(ws, m_self.lock());
             ws->startAnim(true, true, true);
             ws->m_lastMonitor = "";
         }