Port h_atexit to FreeBSD

__cxa_atexit varies between FreeBSD and NetBSD, and thus we must use pointers
instead of static fields in the BSS. More extensive discussion is included in
the source code

In collaboration with: kib
Submitted by: pho

1 files changed, 34 insertions, 0 deletions

diff --git a/contrib/netbsd-tests/lib/libc/stdlib/h_atexit.c b/contrib/netbsd-tests/lib/libc/stdlib/h_atexit.c
index b2f91c4..d3e1f11 100644
--- a/contrib/netbsd-tests/lib/libc/stdlib/h_atexit.c
+++ b/contrib/netbsd-tests/lib/libc/stdlib/h_atexit.c
@@ -42,9 +42,33 @@ __RCSID("$NetBSD: h_atexit.c,v 1.1 2011/01/12 19:44:08 pgoyette Exp $");
 extern int __cxa_atexit(void (*func)(void *), void *, void *);
 extern void __cxa_finalize(void *);
 
+#if defined(__FreeBSD__)
+/*
+ * On shared object unload, in __cxa_finalize, call and clear all installed
+ * atexit and __cxa_atexit handlers that are either installed by unloaded
+ * dso, or points to the functions provided by the dso.
+ *
+ * The reason of the change is to ensure that there is no lingering pointers
+ * to the unloaded code after the dlclose(3).  It is known reason for infinite
+ * stream of the crash reports for many programs which use loadable modules
+ * and fail to properly clean on module unload.  Examples are apache, php,
+ * perl etc.
+ *
+ * You pass the &dso_handle_1 and &dso_handle_2, which points inside the
+ * main binary, to the registration function.  The code from r211706,
+ * correctly detects that they are for the main binary, and on the first
+ * call to __cxa_finalize(), which also pass pointer to main binary, all
+ * registered functions from the main binary are executed.
+ */
+
+static void *dso_handle_1 = (void *)1;
+static void *dso_handle_2 = (void *)2;
+static void *dso_handle_3 = (void *)3;
+#else
 static int dso_handle_1;
 static int dso_handle_2;
 static int dso_handle_3;
+#endif
 
 static int arg_1;
 static int arg_2;
@@ -167,6 +191,15 @@ main(int argc, char *argv[])
 
 	ASSERT(0 == atexit(normal_handler_0));
 	ASSERT(0 == atexit(normal_handler_1));
+#if defined(__FreeBSD__)
+	ASSERT(0 == __cxa_atexit(cxa_handler_4, &arg_1, dso_handle_1));
+	ASSERT(0 == __cxa_atexit(cxa_handler_5, &arg_1, dso_handle_1));
+	ASSERT(0 == __cxa_atexit(cxa_handler_3, &arg_2, dso_handle_2));
+	ASSERT(0 == __cxa_atexit(cxa_handler_2, &arg_3, dso_handle_3));
+
+	__cxa_finalize(dso_handle_1);
+	__cxa_finalize(dso_handle_2);
+#else
 	ASSERT(0 == __cxa_atexit(cxa_handler_4, &arg_1, &dso_handle_1));
 	ASSERT(0 == __cxa_atexit(cxa_handler_5, &arg_1, &dso_handle_1));
 	ASSERT(0 == __cxa_atexit(cxa_handler_3, &arg_2, &dso_handle_2));
@@ -174,5 +207,6 @@ main(int argc, char *argv[])
 
 	__cxa_finalize(&dso_handle_1);
 	__cxa_finalize(&dso_handle_2);
+#endif
 	exit(0);
 }