Libguestfs - Aug 2019 - Re: [nbdkit PATCH 4/8] Revert "RHEL 5: Define O_CLOEXEC and SOCK_CLOEXEC."

On Wed, Jul 31, 2019 at 04:31:32PM -0500, Eric Blake
wrote:
> This reverts commit 25206df20275aeff346d9b86adf5e9be99cc9e43.
> 
> An upcoming patch wants to ensure no leaked fds from the server to a
> child process.  POSIX has required O_CLOEXEC since 2008, and although
> current POSIX doesn't yet specify full atomic interfaces everywhere
> such as SOCK_CLOEXEC, it does have an open bug since 2014 [1]
> recommending the full set of interfaces that will be mandatory in the
> next revision of POSIX.  Most modern OS have caught up to that (RHEL 6
> and FreeBSD 10 support SOCK_CLOEXEC, for example), and we're doing
> ourselves a disservice by using silent fallback instead of actively
> detecting with compile failure on systems that are still behind.
> 
> [1] http://austingroupbugs.net/view.php?id=411
> 
> Conflicts:
>  filters/xz/xzfile.c - The fallback moved from plugins/xz/xzfile.c (and
> in fact has been dead code since commit c879d310 made it a filter)
>  plugins/file/file.c - context changes in the meantime
>  src/internal.h - Moved to server/internal.h
> ---
>  server/internal.h             | 8 --------
>  filters/xz/xzfile.c           | 4 ----
>  plugins/example2/example2.c   | 4 ----
>  plugins/file/file.c           | 4 ----
>  plugins/streaming/streaming.c | 4 ----
>  5 files changed, 24 deletions(-)
> 
> diff --git a/server/internal.h b/server/internal.h
> index 80ab879c..6207f0cf 100644
> --- a/server/internal.h
> +++ b/server/internal.h
> @@ -50,14 +50,6 @@
>  #define UNIX_PATH_MAX 108
>  #endif
> 
> -#ifndef O_CLOEXEC
> -#define O_CLOEXEC 0
> -#endif
> -
> -#ifndef SOCK_CLOEXEC
> -#define SOCK_CLOEXEC 0
> -#endif
As far as I can see Haiku (hrev52698) has O_CLOEXEC but NOT
SOCK_CLOEXEC.  As this version is a little old I'll do an update and
see if newer versions support it.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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On Thu, Aug 01, 2019 at 10:06:01AM +0100, Richard W.M. Jones
wrote:
> As far as I can see Haiku (hrev52698) has O_CLOEXEC but NOT
> SOCK_CLOEXEC.  As this version is a little old I'll do an update and
> see if newer versions support it.
I'm on hrev53313+1 which also doesn't appear to have SOCK_CLOEXEC (nor
does it have accept4).

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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On 8/1/19 4:15 AM, Richard W.M. Jones wrote:
> On Thu, Aug 01, 2019 at 10:06:01AM +0100, Richard W.M. Jones wrote:
>> As far as I can see Haiku (hrev52698) has O_CLOEXEC but NOT
>> SOCK_CLOEXEC.  As this version is a little old I'll do an update
and
>> see if newer versions support it.
> 
> I'm on hrev53313+1 which also doesn't appear to have SOCK_CLOEXEC
(nor
> does it have accept4).
Ouch. Then I'm seriously thinking of a followup patch which either
forces SERIALIZE_ALL_REQUESTS on all plugins when SOCK_CLOEXEC is
missing, or which adds a bool to the plugin interface that the plugin
sets to true if it does not fork (default to false), and where we force
SERIALIZE_ALL_REQUESTS plugins which have not set it to true (most of
our in-tree plugins can set the bool to true).

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org