Re: [PATCH for-9.1 v2 01/11] libvhost-user: set msg.msg_control to NULL when it is empty

[David Hildenbrand]

On 26.03.24 14:39, Stefano Garzarella wrote:

On some OS (e.g. macOS) sendmsg() returns -1 (errno EINVAL) if
the `struct msghdr` has the field `msg_controllen` set to 0, but
`msg_control` is not NULL.

Signed-off-by: Stefano Garzarella 
---
  subprojects/libvhost-user/libvhost-user.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/subprojects/libvhost-user/libvhost-user.c 
b/subprojects/libvhost-user/libvhost-user.c
index a879149fef..22bea0c775 100644
--- a/subprojects/libvhost-user/libvhost-user.c
+++ b/subprojects/libvhost-user/libvhost-user.c
@@ -632,6 +632,7 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg 
*vmsg)
  memcpy(CMSG_DATA(cmsg), vmsg->fds, fdsize);
  } else {
  msg.msg_controllen = 0;
+msg.msg_control = NULL;
  }
  
  do {


Reviewed-by: David Hildenbrand 

--
Cheers,

David / dhildenb

Re: [PATCH for-9.1 v2 01/11] libvhost-user: set msg.msg_control to NULL when it is empty

[Eric Blake]

On Tue, Mar 26, 2024 at 02:39:26PM +0100, Stefano Garzarella wrote:
> On some OS (e.g. macOS) sendmsg() returns -1 (errno EINVAL) if
> the `struct msghdr` has the field `msg_controllen` set to 0, but
> `msg_control` is not NULL.
> 
> Signed-off-by: Stefano Garzarella 
> ---
>  subprojects/libvhost-user/libvhost-user.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Eric Blake 

> 
> diff --git a/subprojects/libvhost-user/libvhost-user.c 
> b/subprojects/libvhost-user/libvhost-user.c
> index a879149fef..22bea0c775 100644
> --- a/subprojects/libvhost-user/libvhost-user.c
> +++ b/subprojects/libvhost-user/libvhost-user.c
> @@ -632,6 +632,7 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg 
> *vmsg)
>  memcpy(CMSG_DATA(cmsg), vmsg->fds, fdsize);
>  } else {
>  msg.msg_controllen = 0;
> +msg.msg_control = NULL;
>  }
>  
>  do {
> -- 
> 2.44.0
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization:  qemu.org | libguestfs.org