Re: [PATCH v2 2/4] Consolidate stdio-lock.h

[Florian Weimer <fweimer@redhat.com>]

* Adhemerval Zanella:

> You are right.  The change now uses __libc_cleanup_region_start from
> libc-lock.h instead of the cleanup version.  I am not sure about
> hardening, but afaiu __libc_cleanup_push_defer should handle C++
> unwinding for fopencookie.

No, C++ unwinding will right go through these frames.  We only
interleave in the other direction (pthread_cancel unwinding running C++
destructors).

> It seems that the Hurd version is indeed to the best option, so I think for
> generic it would be better to just use:
>
> diff --git a/sysdeps/generic/stdio-lock.h b/sysdeps/generic/stdio-lock.h
> index 14cf458bdd..a42131f5a5 100644
> --- a/sysdeps/generic/stdio-lock.h
> +++ b/sysdeps/generic/stdio-lock.h
> @@ -45,20 +45,12 @@ __libc_lock_define_recursive (typedef, _IO_lock_t)
>  #define _IO_cleanup_region_end(_doit) \
>    __libc_cleanup_region_end (_doit)
>
> -#if defined _LIBC && IS_IN (libc)
> -
> -# ifdef __EXCEPTIONS
> -# define _IO_acquire_lock(_fp) \
> +#define _IO_acquire_lock(_fp) \
>    do {                                                                       \
>      FILE *_IO_acquire_lock_file                                                      \
>         __attribute__((cleanup (_IO_acquire_lock_fct)))                       \
>         = (_fp);                                                              \
>      _IO_flockfile (_IO_acquire_lock_file);
> -# else
> -#  define _IO_acquire_lock(_fp) _IO_acquire_lock_needs_exceptions_enabled
> -# endif
> -# define _IO_release_lock(_fp) ; } while (0)
> -
> -#endif
> +#define _IO_release_lock(_fp) ; } while (0)
>
>  #endif /* stdio-lock.h */

I suppose so.

Thanks,
Florian