[libcxx-commits] [libcxx] WIP [libc++][hardening] Overhaul the termination mechanism for hardening (PR #77823)

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,23 @@
+// -*- C++ -*-
----------------
ldionne wrote:

Per our live review just now, we explored the following alternatives (using chrome as an example since we know they override verbose abort right now):

```
Option #1
=======================
$ cmake ... -DLIBCXX_VERBOSE_TRAP_OVERRIDE="void __chromium_trap(char const*);\n#define _LIBCPP_VERBOSE_TRAP(message) __chromium_trap(message)"

// __verbose_trap.in
#ifndef _LIBCPP___VERBOSE_TRAP
#define _LIBCPP___VERBOSE_TRAP

#include <__availability>
#include <__config>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

#if @LIBCXX_VERBOSE_TRAP_OVERRIDE@
    @LIBCXX_VERBOSE_TRAP_OVERRIDE@
#elif HARDENING_MODE == DEBUG
#   define _LIBCPP_VERBOSE_TRAP(message) ::verbose_abort(...)
#else
#   define _LIBCPP_VERBOSE_TRAP(message) ((void)message, __builtin_trap())
#endif

#endif // _LIBCPP___VERBOSE_TRAP



Option #2
=======================
$ cmake ... -DLIBCXX_VERBOSE_TRAP_OVERRIDE=libcxx/vendor/chrome/verbose_trap.in

// __verbose_trap.in
#ifndef _LIBCPP___VERBOSE_TRAP
#define _LIBCPP___VERBOSE_TRAP

#include <__availability>
#include <__config>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

#if @LIBCXX_VERBOSE_TRAP_OVERRIDE@
    copy-paste the contents of @LIBCXX_VERBOSE_TRAP_OVERRIDE@ at CMake configuration time
#elif HARDENING_MODE == DEBUG
#   define _LIBCPP_VERBOSE_TRAP(message) ::verbose_abort(...)
#else
#   define _LIBCPP_VERBOSE_TRAP(message) ((void)message, __builtin_trap())
#endif

#endif // _LIBCPP___VERBOSE_TRAP


// in libcxx/vendor/chrome/verbose_trap.in
#define _LIBCPP_VERBOSE_TRAP(message) ::whatever()
```

https://github.com/llvm/llvm-project/pull/77823