From fe4a2cf7d803eee36a2108c04e3ab7b097a8f8ea Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Sun, 11 Oct 2026 21:05:51 +0000
Subject: [PATCH] fix(libc): run atexit handlers in one order with __cxa_atexit
 destructors

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ha6Tsy62AFUyp9a5Mf7vjA
---
 core/libs/prx/libc/src/Process.cpp | 20 +++++---------------
 core/libs/tests/GuestExitOrder.cpp | 17 ++++++++++++-----
 2 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/core/libs/prx/libc/src/Process.cpp b/core/libs/prx/libc/src/Process.cpp
index 0e2341b02..fd810843e 100644
--- a/core/libs/prx/libc/src/Process.cpp
+++ b/core/libs/prx/libc/src/Process.cpp
@@ -18,6 +18,8 @@
 #include "prx/libc/include/General.hpp"
 #include "SceTypes.hpp"
 
+extern "C" int APS5_VABI __cxa_atexit_nid_postfix(void (APS5_VABI *func)(void*), void* arg, void* dsoHandle);
+
 namespace {
 
 std::mutex shutdownMutex;
@@ -31,17 +33,9 @@ std::stop_source shutdownSource;
 std::atomic<bool> exitRequested{false};
 std::atomic<bool> exitStarted{false};
 using GuestExitCallback = void (APS5_VABI*)();
-std::mutex exitCallbackMutex;
-std::vector<GuestExitCallback> exitCallbacks;
 
-void runGuestExitCallback() {
-    GuestExitCallback callback;
-    {
-        std::lock_guard lock(exitCallbackMutex);
-        callback = exitCallbacks.back();
-        exitCallbacks.pop_back();
-    }
-    callback();
+void APS5_VABI RunGuestExitCallback(void* callback) {
+    reinterpret_cast<GuestExitCallback>(callback)();
 }
 
 }
@@ -166,11 +160,7 @@ int* APS5_VABI __error_nid_postfix() {
 int APS5_VABI atexit_nid_postfix(GuestExitCallback func) {
     if (func == nullptr)
         return 0;
-    std::lock_guard lock(exitCallbackMutex);
-    exitCallbacks.push_back(func);
-    const int result = std::atexit(runGuestExitCallback);
-    if (result != 0) exitCallbacks.pop_back();
-    return result;
+    return __cxa_atexit_nid_postfix(RunGuestExitCallback, reinterpret_cast<void*>(func), nullptr);
 }
 
 namespace {
diff --git a/core/libs/tests/GuestExitOrder.cpp b/core/libs/tests/GuestExitOrder.cpp
index 067bea90f..889e6f0f2 100644
--- a/core/libs/tests/GuestExitOrder.cpp
+++ b/core/libs/tests/GuestExitOrder.cpp
@@ -6,6 +6,7 @@
 #include <unistd.h>
 
 extern "C" int APS5_VABI __cxa_atexit_nid_postfix(void (APS5_VABI *func)(void*), void* arg, void* dsoHandle);
+extern "C" int APS5_VABI atexit_nid_postfix(void (APS5_VABI *func)());
 
 namespace {
 
@@ -19,14 +20,16 @@ void APS5_VABI GuestHandler(void*) { Record('G'); }
 
 void HostHandler() { Record('H'); }
 
-bool GuestHandlersRunFirst() {
+void APS5_VABI AtexitHandler() { Record('A'); }
+
+template <typename Setup>
+bool ExitOrder(Setup setup, const char* expected) {
     if (pipe(events) != 0) return false;
     const pid_t child = fork();
     if (child < 0) return false;
     if (child == 0) {
         close(events[0]);
-        __cxa_atexit_nid_postfix(GuestHandler, nullptr, nullptr);
-        std::atexit(HostHandler);
+        setup();
         LibcExit_nid_no_patch(0);
     }
     close(events[1]);
@@ -39,15 +42,19 @@ bool GuestHandlersRunFirst() {
     }
     close(events[0]);
     int status = 0;
-    return waitpid(child, &status, 0) == child && WIFEXITED(status) && WEXITSTATUS(status) == 0 && length == 2 && order[0] == 'G' && order[1] == 'H';
+    return waitpid(child, &status, 0) == child && WIFEXITED(status) && WEXITSTATUS(status) == 0 && length == 2 && order[0] == expected[0] && order[1] == expected[1];
 }
 
 }
 
 int main() {
-    if (!GuestHandlersRunFirst()) {
+    if (!ExitOrder([] { __cxa_atexit_nid_postfix(GuestHandler, nullptr, nullptr); std::atexit(HostHandler); }, "GH")) {
         std::fputs("guest exit handlers must run before the host exit handlers\n", stderr);
         return 1;
     }
+    if (!ExitOrder([] { __cxa_atexit_nid_postfix(GuestHandler, nullptr, nullptr); atexit_nid_postfix(AtexitHandler); }, "AG")) {
+        std::fputs("atexit and __cxa_atexit handlers must run in reverse order of registration\n", stderr);
+        return 1;
+    }
     return 0;
 }