[PATCH] debug: Fix clang mq_open fortify wrapper (BZ 31917)

[Khem Raj]

This works ok here with clang/main and failing cases are working fine.

Acked-by: Khem Raj <raj.khem@gmail.com>

On Fri, Jun 21, 2024 at 7:08 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> The mqueue.h fortify wrapper for clang added by c23107effbfe5300
> is not fully correct, where correct 4 argument usage are not
> being correctly handled.  For instance, while building socat 1.8
> with a yocto clang based system shows:
>
>   ./socat-1.8.0.0/xio-posixmq.c:119:8: error: 'mq_open' is unavailable: mq_open can be called either with 2 or 4 arguments
>     119 |         mqd = mq_open(name, oflag, opt_mode, NULL);
>         |               ^
>   [...] /usr/include/bits/mqueue2.h:66:8: note: 'mq_open' has been explicitly marked unavailable here
>      66 | __NTH (mq_open (const char *__name, int __oflag, mode_t mode,
>         |        ^
>   1 error generated.
>
> The correct way to define the wrapper is to set invalid usage
> with __fortify_clang_unavailable (for the case with 5 or more
> arguments), followed by the expected ones.  This fix make mq_open
> similar to current open wrappers.
>
> [1] http://www.dest-unreach.org/socat/
>
> Reported-by: Khem Raj <raj.khem@gmail.com>
> ---
>  rt/bits/mqueue2.h | 20 ++++++++------------
>  1 file changed, 8 insertions(+), 12 deletions(-)
>
> diff --git a/rt/bits/mqueue2.h b/rt/bits/mqueue2.h
> index d6d2d9012d..386404c0c8 100644
> --- a/rt/bits/mqueue2.h
> +++ b/rt/bits/mqueue2.h
> @@ -59,13 +59,16 @@ __NTH (mq_open (const char *__name, int __oflag, ...))
>  }
>  #elif __fortify_use_clang
>  __fortify_function_error_function __attribute_overloadable__ mqd_t
> -__NTH (mq_open (const char *__name, int __oflag, mode_t mode))
> +__NTH (mq_open (__fortify_clang_overload_arg (const char *, , __name),
> +               int __oflag, mode_t __mode, ...))
>       __fortify_clang_unavailable ("mq_open can be called either with 2 or 4 arguments");
>
> -__fortify_function_error_function __attribute_overloadable__ mqd_t
> -__NTH (mq_open (const char *__name, int __oflag, mode_t mode,
> -               struct mq_attr *attr, ...))
> -     __fortify_clang_unavailable ("mq_open can be called either with 2 or 4 arguments");
> +__fortify_function __attribute_overloadable__ mqd_t
> +__NTH (mq_open (__fortify_clang_overload_arg (const char *, ,__name),
> +               int __oflag, mode_t __mode, struct mq_attr *__attr))
> +{
> +  return __mq_open_alias (__name, __oflag, __mode, __attr);
> +}
>
>  __fortify_function __attribute_overloadable__ mqd_t
>  __NTH (mq_open (__fortify_clang_overload_arg (const char *, ,__name),
> @@ -76,11 +79,4 @@ __NTH (mq_open (__fortify_clang_overload_arg (const char *, ,__name),
>  {
>    return __mq_open_alias (__name, __oflag);
>  }
> -
> -__fortify_function __attribute_overloadable__ mqd_t
> -__NTH (mq_open (__fortify_clang_overload_arg (const char *, ,__name),
> -               int __oflag, int __mode, struct mq_attr *__attr))
> -{
> -  return __mq_open_alias (__name, __oflag, __mode, __attr);
> -}
>  #endif
> --
> 2.43.0
>