Bug 20198: quick_exit should not call destructors.

In C++11 18.5.12 says "Objects shall not be destroyed as a
result of calling quick_exit." In C11 quick_exit is silent
about thread object destruction. Therefore to make glibc
C++ compliant we do not call any thread local destructors.
A new regression test verifies the fix.

I will note that C++11 18.5.3 makes it clear that C++
defines additional requirements for _Exit() to prevent it
from executing destructors.

Given that the point of _Exit() is to terminate the process
immediately it makes sense the C and C++ should line up
and avoid calling destructors.

No failures. New regtest passes.

stdlib/quick_exit.c

@@ -19,11 +19,30 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sysdep.h>
+#include <signal.h>
+#include <errno.h>
+#include <shlib-compat.h>
 #include "exit.h"
 
-
 void
-quick_exit (int status)
+__new_quick_exit (int status)
 {
-  __run_exit_handlers (status, &__quick_exit_funcs, false);
+  /* The new quick_exit, following C++11 18.5.12, does not run object
+     destructors.   While C11 says nothing about object destructors,
+     since it has none, the intent is to run the registered
+     at_quick_exit handlers and then run _Exit immediately without
+     disturbing the state of the process and threads.  */
+  __run_exit_handlers (status, &__quick_exit_funcs, false, false);
 }
+versioned_symbol (libc, __new_quick_exit, quick_exit, GLIBC_2_24);
+
+#if SHLIB_COMPAT(libc, GLIBC_2_10, GLIBC_2_24)
+void
+attribute_compat_text_section
+__old_quick_exit (int status)
+{
+  /* The old quick_exit runs thread_local destructors.  */
+  __run_exit_handlers (status, &__quick_exit_funcs, false, true);
+}
+compat_symbol (libc, __old_quick_exit, quick_exit, GLIBC_2_10);
+#endif