[libvirt] [PATCH 2/4] util: add virNetlinkDumpCommand()

[Laine Stump]

On 03/03/2017 10:00 AM, Cédric Bosdonnat wrote:
> virNetlinkCommand() processes only one response message, while some
> netlink commands like routes dumping need to process several ones.
> Add virNetlinkDumpCommand() as a virNetlinkCommand() sister.
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virnetlink.c    | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
>  src/util/virnetlink.h    |  9 ++++++++
>  3 files changed, 65 insertions(+)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index bce0487ab..71143851c 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2117,6 +2117,7 @@ virNetDevVPortProfileOpTypeToString;
>  # util/virnetlink.h
>  virNetlinkCommand;
>  virNetlinkDelLink;
> +virNetlinkDumpCommand;
>  virNetlinkDumpLink;
>  virNetlinkEventAddClient;
>  virNetlinkEventRemoveClient;
> diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c
> index 5fb49251c..4747ba5a4 100644
> --- a/src/util/virnetlink.c
> +++ b/src/util/virnetlink.c
> @@ -335,6 +335,49 @@ int virNetlinkCommand(struct nl_msg *nl_msg,
>      return ret;
>  }
>  
> +int
> +virNetlinkDumpCommand(struct nl_msg *nl_msg,
> +                      virNetlinkDumpCallback callback,
> +                      uint32_t src_pid, uint32_t dst_pid,
> +                      unsigned int protocol, unsigned int groups,
> +                      void *opaque)
> +{
> +    int ret = -1;
> +    bool end = false;
> +    int len = 0;
> +    struct nlmsghdr *resp = NULL;
> +    struct nlmsghdr *msg = NULL;
> +
> +    struct sockaddr_nl nladdr = {
> +            .nl_family = AF_NETLINK,
> +            .nl_pid    = dst_pid,
> +            .nl_groups = 0,
> +    };
> +    virNetlinkHandle *nlhandle = NULL;
> +
> +    if (!(nlhandle = virNetlinkDoCommand(nl_msg, src_pid, nladdr,
> +                                         protocol, groups)))
> +        goto cleanup;
> +
> +    while (!end) {
> +        len = nl_recv(nlhandle, &nladdr, (unsigned char **)&resp, NULL);
> +
> +        for (msg = resp; NLMSG_OK(msg, len); msg = NLMSG_NEXT(msg, len)) {
> +            if (msg->nlmsg_type == NLMSG_DONE)
> +                end = true;
> +
> +            if (callback(msg, opaque) < 0)
> +                goto cleanup;

This is relying on the callback function to throw an error in order to get us out of the loop (assuming we never get an NLMSG_DONE). I don't see the callback that's written in patch 4 doing anything along the lines of virNetlinkGetErrorCode() though. Maybe you should call that function from here prior to the callback - that would eliminate the need to separately do that level of error checking in all the future consumers of this new function.

Otherwise I think it looks okay (I can't claim to have great knowledge of multipart netlink messages though, so...)