LibC: implement and call __cxa_finalize() on exit()

This allows global destructors to be actually called

libc/icxxabi.cpp

@@ -1,35 +1,37 @@
+#include <icxxabi.h>
+
 #define ATEXIT_MAX_FUNCS 128
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-typedef unsigned uarch_t;
-
 struct atexit_func_entry_t
 {
-	/*
-	* Each member is at least 4 bytes large. Such that each entry is 12bytes.
-	* 128 * 12 = 1.5KB exact.
-	**/
-	void (*destructor_func)(void *);
-	void *obj_ptr;
+	void (*destructor)(void*);
+	void* data;
 	void* dso_handle;
 };
 
-atexit_func_entry_t __atexit_funcs[ATEXIT_MAX_FUNCS];
-uarch_t __atexit_func_count = 0;
+static atexit_func_entry_t __atexit_funcs[ATEXIT_MAX_FUNCS];
+static int __atexit_func_count = 0;
 
-int __cxa_atexit(void (*f)(void *), void *objptr, void *dso)
+int __cxa_atexit(void (*func)(void*), void* data, void* dso_handle)
 {
-	if (__atexit_func_count >= ATEXIT_MAX_FUNCS) {return -1;};
-	__atexit_funcs[__atexit_func_count].destructor_func = f;
-	__atexit_funcs[__atexit_func_count].obj_ptr = objptr;
-	__atexit_funcs[__atexit_func_count].dso_handle = dso;
+	if (__atexit_func_count >= ATEXIT_MAX_FUNCS)
+		return -1;;
+	__atexit_funcs[__atexit_func_count].destructor = func;
+	__atexit_funcs[__atexit_func_count].data = data;
+	__atexit_funcs[__atexit_func_count].dso_handle = dso_handle;
 	__atexit_func_count++;
-	return 0; /*I would prefer if functions returned 1 on success, but the ABI says...*/
+	return 0;
 };
 
-#ifdef __cplusplus
-};
-#endif
+void __cxa_finalize(void* func)
+{
+	for (int i = __atexit_func_count - 1; i >= 0; i--)
+	{
+		if (func && func != __atexit_funcs[i].destructor)
+			continue;
+		if (__atexit_funcs[i].destructor == nullptr)
+			continue;
+		__atexit_funcs[i].destructor(__atexit_funcs[i].data);
+		__atexit_funcs[i].destructor = nullptr;
+	}
+}

libc/include/icxxabi.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+int __cxa_atexit(void (*func)(void*), void* data, void* dso_handle);
+void __cxa_finalize(void* func);
+
+__END_DECLS

libc/stdlib.cpp

@@ -7,6 +7,8 @@
 #include <sys/syscall.h>
 #include <unistd.h>
 
+#include <icxxabi.h>
+
 extern "C" char** environ;
 
 extern "C" void _fini();
@@ -21,6 +23,7 @@ void abort(void)
 void exit(int status)
 {
 	fflush(nullptr);
+	__cxa_finalize(nullptr);
 	_fini();
 	_exit(status);
 	ASSERT_NOT_REACHED();