Re: [PATCH 1/4] hurd: Don't pass fd flags in CMSG_DATA

[Samuel Thibault]

Sergey Bugaev, le lun. 17 avril 2023 16:38:59 +0300, a ecrit:
> The only valid flag defined here is FD_CLOEXEC. It is of no concern to
> the receiving process whether or not the sender process wants to close
> its copy of sent file descriptor upon exec,

Ok, but couldn't there be some flags that we could want to transfer, in
the future? I'd better keep the infrastructure, even if it is not
actually useful for now. So that people who end up needing something see
that passing it is already supported.

Samuel

> and it should not influence
> whether or not the received file descriptor gets the FD_CLOEXEC flag
> set in the receiving process.
> 
> The latter should in fact be dependent on the MSG_CMSG_CLOEXEC flag
> being passed to the recvmsg () call, which is going to be implemented
> in the following commit.
> 
> Fixes 344e755248ce02c0f8d095d11cc49e340703d926
> "hurd: Support sending file descriptors over Unix sockets"
> 
> Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
> ---
>  sysdeps/mach/hurd/recvmsg.c | 3 +--
>  sysdeps/mach/hurd/sendmsg.c | 4 ++--
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/sysdeps/mach/hurd/recvmsg.c b/sysdeps/mach/hurd/recvmsg.c
> index 39de86f6..5e8b18c6 100644
> --- a/sysdeps/mach/hurd/recvmsg.c
> +++ b/sysdeps/mach/hurd/recvmsg.c
> @@ -189,7 +189,6 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
>      if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
>        {
>       /* SCM_RIGHTS support.  */
> -     /* The fd's flags are passed in the control data.  */
>       int *fds = (int *) CMSG_DATA (cmsg);
>       nfds = (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr)))
>              / sizeof (int);
> @@ -200,7 +199,7 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
>           if (err)
>             goto cleanup;
>           fds[j] = opened_fds[newfds] = _hurd_intern_fd (newports[newfds],
> -                                                        fds[j], 0);
> +                                                        0, 0);
>           if (fds[j] == -1)
>             {
>               err = errno;
> diff --git a/sysdeps/mach/hurd/sendmsg.c b/sysdeps/mach/hurd/sendmsg.c
> index 5871d1d8..77a720fb 100644
> --- a/sysdeps/mach/hurd/sendmsg.c
> +++ b/sysdeps/mach/hurd/sendmsg.c
> @@ -138,8 +138,8 @@ __libc_sendmsg (int fd, const struct msghdr *message, int 
> flags)
>                                            0, 0, 0, 0);
>                  if (! err)
>                    nports++;
> -                /* We pass the flags in the control data.  */
> -                fds[i] = descriptor->flags;
> +                /* We just pass 0 in the control data.  */
> +                fds[i] = 0;
>                  err;
>                }));
>  
> -- 
> 2.39.2
> 

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