[PATCH v2 2/4] hurd: Implement MSG_CMSG_CLOEXEC

[Samuel Thibault]

Applied, thanks!

Sergey Bugaev, le dim. 23 avril 2023 19:05:46 +0300, a ecrit:
> This is a new flag that can be passed to recvmsg () to make it
> atomically set the CLOEXEC flag on all the file descriptors received
> using the SCM_RIGHTS mechanism. This is useful for all the same reasons
> that the other XXX_CLOEXEC flags are useful: namely, it provides
> atomicity with respect to another thread of the same process calling
> (fork and then) exec at the same time.
> 
> This flag is already supported on Linux and FreeBSD. The flag's value,
> 0x40000, is choosen to match FreeBSD's.
> 
> Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
> ---
>  sysdeps/mach/hurd/bits/socket.h | 5 ++++-
>  sysdeps/mach/hurd/recvmsg.c     | 3 ++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/sysdeps/mach/hurd/bits/socket.h b/sysdeps/mach/hurd/bits/socket.h
> index 2d78a916..c2392bed 100644
> --- a/sysdeps/mach/hurd/bits/socket.h
> +++ b/sysdeps/mach/hurd/bits/socket.h
> @@ -197,8 +197,11 @@ enum
>  #define MSG_WAITALL MSG_WAITALL
>      MSG_DONTWAIT	= 0x80,	/* This message should be nonblocking.  */
>  #define MSG_DONTWAIT MSG_DONTWAIT
> -    MSG_NOSIGNAL	= 0x0400	/* Do not generate SIGPIPE on EPIPE.  */
> +    MSG_NOSIGNAL	= 0x0400,	/* Do not generate SIGPIPE on EPIPE.  */
>  #define MSG_NOSIGNAL MSG_NOSIGNAL
> +    MSG_CMSG_CLOEXEC	= 0x40000	/* Atomically set close-on-exec flag
> +					   for file descriptors in SCM_RIGHTS.  */
> +#define MSG_CMSG_CLOEXEC MSG_CMSG_CLOEXEC
>    };
>  
>  
> diff --git a/sysdeps/mach/hurd/recvmsg.c b/sysdeps/mach/hurd/recvmsg.c
> index c08eb499..9a37a053 100644
> --- a/sysdeps/mach/hurd/recvmsg.c
> +++ b/sysdeps/mach/hurd/recvmsg.c
> @@ -197,11 +197,12 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
>  
>  	for (j = 0; j < nfds; j++)
>  	  {
> +	    int fd_flags = (flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
>  	    err = reauthenticate (ports[i], &newports[newfds]);
>  	    if (err)
>  	      goto cleanup;
>  	    fds[j] = opened_fds[newfds] = _hurd_intern_fd (newports[newfds],
> -							   0, 0);
> +							   fd_flags, 0);
>  	    if (fds[j] == -1)
>  	      {
>  		err = errno;
> -- 
> 2.40.0
> 

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