[PATCH] features: version-gate _DYNAMIC_STACK_SIZE_SOURCE

[H.J. Lu]

On Fri, Jan 28, 2022 at 6:38 PM Andrew Kelley <andrew@ziglang.org> wrote:
>
> Without this patch, software compiled against glibc 2.34 headers but
> then executed on a system with an older glibc version will attempt to
> invoke `sysconf(_SC_SIGSTKSZ)` when MINSIGSTKSZ or SIGSTKSZ are used. On
> glibcs older than 2.34, this will return -1 (with an errno of EINVAL),
> effectively causing MINSIGSTKSZ and SIGSTKSZ to have the value of -1.
>
> This patch version-gates the _DYNAMIC_STACK_SIZE_SOURCE preprocessor
> definition so that this problem cannot occur.
>
> Downstream patch:
> https://github.com/ziglang/zig/commit/39083c31a550ed80f369f60d35791e98904b8096
> ---
>  include/features.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/features.h b/include/features.h
> index ab2b2caac4..77a8f8cc32 100644
> --- a/include/features.h
> +++ b/include/features.h
> @@ -220,8 +220,10 @@
>  # define _DEFAULT_SOURCE       1
>  # undef  _ATFILE_SOURCE
>  # define _ATFILE_SOURCE        1
> -# undef  _DYNAMIC_STACK_SIZE_SOURCE
> -# define _DYNAMIC_STACK_SIZE_SOURCE 1
> +# if __GNUC_PREREQ (2,34)
> +#  undef  _DYNAMIC_STACK_SIZE_SOURCE
> +#  define _DYNAMIC_STACK_SIZE_SOURCE 1

You are changing a glibc 2.35 header file.   Isn't __GNUC_PREREQ (2,34)
always true? Am I missing something?

> +# endif
>  #endif
>
>  /* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined,
> --
> 2.33.1
>


-- 
H.J.