Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 04/05/2022 13:48, Florian Weimer wrote:
> diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
> new file mode 100644
> index 0000000000..a5de941759
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/startup.h
> @@ -0,0 +1,38 @@
> +/* Linux definitions of functions used by static libc main startup.
> +   Copyright (C) 2017-2022 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifdef SHARED
> +# include_next <startup.h>
> +#else
> +# include <sysdep.h>
> +
> +/* Avoid a run-time invocation of strlen.  */
> +#define _startup_fatal(message)                                         \
> +  do                                                                    \
> +    {                                                                   \
> +      size_t message_length = __builtin_strlen (message);               \

Shoudn't we use double underscore name to avoid clash with local variables?

> +      if (! __builtin_constant_p (message_length))                      \
> +        {                                                               \
> +          extern void _startup_fatal_not_constant (void);               \
> +          _startup_fatal_not_constant ();                               \
> +        }                                                               \
> +      INTERNAL_SYSCALL_CALL (write, STDERR_FILENO, message, message_length); \
> +      INTERNAL_SYSCALL_CALL (exit_group, 127);                          \
> +    }                                                                   \
> +  while (0)
> +#endif  /* !SHARED */