[LEDE-DEV] [PATCH] umdns: Replace unnecessary memset calls with {}.

[Jo-Philipp Wich]

Hi,

comments inline.

> ---
>  interface.c | 22 ++++++++--------------
>  1 file changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/interface.c b/interface.c
> index 7f814d2..18dee52 100644
> --- a/interface.c
> +++ b/interface.c
> @@ -44,7 +44,7 @@
>  static int
>  interface_send_packet4(struct interface *iface, struct sockaddr_in *to, struct iovec *iov, int iov_len)
>  {
> -	static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
> +	static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1] = {};
>  	static struct sockaddr_in a;
>  	static struct msghdr m = {
>  		.msg_name = (struct sockaddr *) &a,
> @@ -61,7 +61,6 @@ interface_send_packet4(struct interface *iface, struct sockaddr_in *to, struct i
>  	m.msg_iov = iov;
>  	m.msg_iovlen = iov_len;
>  
> -	memset(cmsg_data, 0, sizeof(cmsg_data));

The cmsg_data buffer is static, wouldn't that mean that it is never
zeroed again after the first function call?

>  	cmsg = CMSG_FIRSTHDR(&m);
>  	cmsg->cmsg_len = m.msg_controllen;
>  	cmsg->cmsg_level = IPPROTO_IP;
> @@ -84,7 +83,7 @@ interface_send_packet4(struct interface *iface, struct sockaddr_in *to, struct i
>  static int
>  interface_send_packet6(struct interface *iface, struct sockaddr_in6 *to, struct iovec *iov, int iov_len)
>  {
> -	static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in6_pktinfo)) / sizeof(size_t)) + 1];
> +	static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in6_pktinfo)) / sizeof(size_t)) + 1] = {};
>  	static struct sockaddr_in6 a;
>  	static struct msghdr m = {
>  		.msg_name = (struct sockaddr *) &a,
> @@ -101,7 +100,6 @@ interface_send_packet6(struct interface *iface, struct sockaddr_in6 *to, struct
>  	m.msg_iov = iov;
>  	m.msg_iovlen = iov_len;
>  
> -	memset(cmsg_data, 0, sizeof(cmsg_data));

Same here, I think the buffer needs to be zeroed on each invocation.

>  	cmsg = CMSG_FIRSTHDR(&m);
>  	cmsg->cmsg_len = m.msg_controllen;
>  	cmsg->cmsg_level = IPPROTO_IPV6;
> @@ -186,7 +184,7 @@ read_socket4(struct uloop_fd *u, unsigned int events)
>  	struct iovec iov[1];
>  	char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo)) + CMSG_SPACE(sizeof(int)) + 1];
>  	struct cmsghdr *cmsgptr;
> -	struct msghdr msg;
> +	struct msghdr msg = {};
>  	socklen_t len;

[snip]

~ Jo