Re: [PATCH 2/2] tools: Fix use of fcntl(F_SETFD) during socket activation

[Eric Blake <eblake@redhat.com>]

On 4/20/20 12:53 PM, Eric Blake wrote:
> Blindly setting FD_CLOEXEC without a read-modify-write will
> inadvertently clear any other intentionally-set bits, such as a
> proposed new bit for designating a fd that must behave in 32-bit mode.
> However, we cannot use our wrapper qemu_set_cloexec(), because that
> wrapper intentionally abort()s on failure, whereas the probe here
> intentionally tolerates failure to deal with incorrect socket
> activation gracefully.  Instead, fix the code to do the proper
> read-modify-write.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>   util/systemd.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)

As qemu-nbd is impacted, I'll queue 2/2 through my NBD tree if 
qemu-trivial doesn't pick it up first.

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