> From: Tyler Retzlaff [mailto:roret...@linux.microsoft.com]
> Sent: Thursday, 4 April 2024 19.15
>
> RFC sample illustrating conversion of VLA to alloca() where
> sizeof(array) was in use.
>
> Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
> ---
> lib/vhost/socket.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
> index 96b3ab5..cedcfb2 100644
> --- a/lib/vhost/socket.c
> +++ b/lib/vhost/socket.c
> @@ -110,7 +110,8 @@ struct vhost_user {
> {
> struct iovec iov;
> struct msghdr msgh;
> - char control[CMSG_SPACE(max_fds * sizeof(int))];
> + const size_t control_sz = sizeof(char) * CMSG_SPACE(max_fds *
> sizeof(int));
I get the point, but think multiplying with sizeof(char) is overkill.
It's a matter of personal taste; maybe it's just me.
If it was an array of a different type, e.g. int, multiplying with sizeof(int)
would be required, like in the latencystats example.
Anyway, I agree with the approach here.
> + char *control = alloca(control_sz);
> struct cmsghdr *cmsg;
> int got_fds = 0;
> int ret;
> @@ -124,7 +125,7 @@ struct vhost_user {
> msgh.msg_iov = &iov;
> msgh.msg_iovlen = 1;
> msgh.msg_control = control;
> - msgh.msg_controllen = sizeof(control);
> + msgh.msg_controllen = control_sz;
>
> ret = recvmsg(sockfd, &msgh, 0);
> if (ret <= 0) {
> --
> 1.8.3.1
