From c342d5ca44ec4ecbd39b595d458ea58214b5d871 Mon Sep 17 00:00:00 2001
From: Vaxry <vaxry@vaxry.net>
Date: Mon, 8 Jul 2024 23:06:28 +0200
Subject: [PATCH] memory: do not release pointers after emitting a signal

A signal called is allowed to free ourselves, in which case we're not allowed to use this anymore. Only perform the housekeeping of removing stale events before emit, and in registerListener.
---
 src/signal/Signal.cpp | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/src/signal/Signal.cpp b/src/signal/Signal.cpp
index 698d16a..3442fe7 100644
--- a/src/signal/Signal.cpp
+++ b/src/signal/Signal.cpp
@@ -9,14 +9,10 @@ using namespace Hyprutils::Memory;
 #define WP CWeakPointer
 
 void Hyprutils::Signal::CSignal::emit(std::any data) {
-    bool                             dirty = false;
-
     std::vector<SP<CSignalListener>> listeners;
     for (auto& l : m_vListeners) {
-        if (l.expired()) {
-            dirty = true;
+        if (l.expired())
             continue;
-        }
 
         listeners.emplace_back(l.lock());
     }
@@ -29,10 +25,9 @@ void Hyprutils::Signal::CSignal::emit(std::any data) {
     for (auto& l : listeners) {
         // if there is only one lock, it means the event is only held by the listeners
         // vector and was removed during our iteration
-        if (l.strongRef() == 1) {
-            dirty = true;
+        if (l.strongRef() == 1)
             continue;
-        }
+        
         l->emit(data);
     }
 
@@ -43,13 +38,17 @@ void Hyprutils::Signal::CSignal::emit(std::any data) {
     // release SPs
     listeners.clear();
 
-    if (dirty)
-        std::erase_if(m_vListeners, [](const auto& other) { return other.expired(); });
+    // we cannot release any expired refs here as one of the listeners could've removed this object and 
+    // as such we'd be doing a UAF
 }
 
 CHyprSignalListener Hyprutils::Signal::CSignal::registerListener(std::function<void(std::any)> handler) {
     CHyprSignalListener listener = makeShared<CSignalListener>(handler);
     m_vListeners.emplace_back(listener);
+
+    // housekeeping: remove any stale listeners
+    std::erase_if(m_vListeners, [](const auto& other) { return other.expired(); });
+    
     return listener;
 }