Re: [PATCH glibc] Update hurd/intr-msg.c to be more portable

[Samuel Thibault]

Applied, thanks!

Flavio Cruz via Libc-alpha, le jeu. 04 mai 2023 00:08:12 -0400, a ecrit:
> Summary of the changes:
> - Introduce BAD_TYPECHECK from MiG to make it simpler to do type
>   checking.
> - Replace int type with mach_msg_type_t. This assumes that
>   mach_msg_type_t is always the same size as int which is not true for
>   x86_64.
> - Calculate the size and align using PTR_ALIGN_UP, which is a bit
>   cleaner and similar to what we do elsewhere.
> - Define mach_msg_type_t to check using designated initializers.
> ---
>  hurd/intr-msg.c | 34 +++++++++++++++++++++-------------
>  1 file changed, 21 insertions(+), 13 deletions(-)
> 
> diff --git a/hurd/intr-msg.c b/hurd/intr-msg.c
> index 716d87ab6a..a8e4d04041 100644
> --- a/hurd/intr-msg.c
> +++ b/hurd/intr-msg.c
> @@ -28,6 +28,11 @@
>  # define mig_reply_header_t  mig_reply_error_t
>  #endif
>  
> +/* Macro used by MIG to cleanly check the type.  */
> +#define BAD_TYPECHECK(type, check) __glibc_unlikely (({      \
> +  union { mach_msg_type_t t; uint32_t w; } _t, _c;   \
> +  _t.t = *(type); _c.t = *(check);_t.w != _c.w; }))
> +
>  error_t
>  _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
>                        mach_msg_option_t option,
> @@ -61,7 +66,7 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
>  #ifdef NDR_CHAR_ASCII
>        NDR_record_t ndr;
>  #else
> -      int type;
> +      mach_msg_type_t type;
>  #endif
>        int code;
>      } check;
> @@ -222,11 +227,12 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
>  
>             if (ty->msgtl_header.msgt_inline)
>               {
> +               /* Calculate length of data in bytes.  */
> +               const vm_size_t length = ((number * size) + 7) >> 3;
>                 clean_ports ((void *) ty, 0);
> -               /* calculate length of data in bytes, rounding up */
> -               ty = (void *) ty + (((((number * size) + 7) >> 3)
> -                                    + sizeof (mach_msg_type_t) - 1)
> -                                   &~ (sizeof (mach_msg_type_t) - 1));
> +               /* Move to the next argument.  */
> +               ty = (void *) PTR_ALIGN_UP ((char *) ty + length,
> +                   __alignof__ (uintptr_t));
>               }
>             else
>               {
> @@ -354,19 +360,21 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
>        {
>       /* We got a reply.  Was it EINTR?  */
>  #ifdef MACH_MSG_TYPE_BIT
> -     const union
> -     {
> -       mach_msg_type_t t;
> -       int i;
> -     } check =
> -       { t: { MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8,
> -              1, TRUE, FALSE, FALSE, 0 } };
> +     static const mach_msg_type_t type_check = {
> +       .msgt_name = MACH_MSG_TYPE_INTEGER_T,
> +       .msgt_size = sizeof (integer_t) * 8,
> +       .msgt_number = 1,
> +       .msgt_inline = TRUE,
> +       .msgt_longform = FALSE,
> +       .msgt_deallocate = FALSE,
> +       .msgt_unused = 0
> +     };
>  #endif
>  
>          if (m->reply.RetCode == EINTR
>           && m->header.msgh_size == sizeof m->reply
>  #ifdef MACH_MSG_TYPE_BIT
> -         && m->check.type == check.i
> +         && !BAD_TYPECHECK(&m->check.type, &type_check)
>  #endif
>           && !(m->header.msgh_bits & MACH_MSGH_BITS_COMPLEX))
>         {
> -- 
> 2.39.2
> 

-- 
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.