On Fri, 16 Mar 2018 16:23:09 -0300
Marcelo Ricardo Leitner <marcelo.leit...@gmail.com> wrote:
> This patch introduces support for reading more than one message from
> extack's and to adjust their level (warning/error) accordingly.
>
> Yes, there is a FIXME tag in the callback call for now.
>
> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
Make sense, can hold off until kernel supports warnings.
> ---
> lib/libnetlink.c | 55 ++++++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 40 insertions(+), 15 deletions(-)
>
> diff --git a/lib/libnetlink.c b/lib/libnetlink.c
> index
> 928de1dd16d84b7802c06d0a659f5d73e1bbcb4b..7c4c81e11e02ea857888190eb5e7a9e99d159bb3
> 100644
> --- a/lib/libnetlink.c
> +++ b/lib/libnetlink.c
> @@ -43,9 +43,16 @@ static const enum mnl_attr_data_type
> extack_policy[NLMSGERR_ATTR_MAX + 1] = {
> [NLMSGERR_ATTR_OFFS] = MNL_TYPE_U32,
> };
>
> +#define NETLINK_MAX_EXTACK_MSGS 8
Would rather not have fixed maximums
> +struct extack_args {
> + const struct nlattr *msg[NETLINK_MAX_EXTACK_MSGS];
> + const struct nlattr *offs;
> + int msg_count;
> +};
If you put msg[] last in structure, it could be variable length.
> static int err_attr_cb(const struct nlattr *attr, void *data)
> {
> - const struct nlattr **tb = data;
> + struct extack_args *tb = data;
> uint16_t type;
>
> if (mnl_attr_type_valid(attr, NLMSGERR_ATTR_MAX) < 0) {
> @@ -60,19 +67,23 @@ static int err_attr_cb(const struct nlattr *attr, void
> *data)
> return MNL_CB_ERROR;
> }
>
> - tb[type] = attr;
> + if (type == NLMSGERR_ATTR_OFFS)
> + tb->offs = attr;
> + else if (tb->msg_count < NETLINK_MAX_EXTACK_MSGS)
> + tb->msg[tb->msg_count++] = attr;
> return MNL_CB_OK;
> }
>
> /* dump netlink extended ack error message */
> int nl_dump_ext_ack(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
> {
> - struct nlattr *tb[NLMSGERR_ATTR_MAX + 1] = {};
> + struct extack_args tb = {};
> const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
> const struct nlmsghdr *err_nlh = NULL;
> unsigned int hlen = sizeof(*err);
> - const char *msg = NULL;
> + const char *msg[NETLINK_MAX_EXTACK_MSGS] = {};
> uint32_t off = 0;
> + int ret, i;
>
> /* no TLVs, nothing to do here */
> if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
> @@ -82,14 +93,14 @@ int nl_dump_ext_ack(const struct nlmsghdr *nlh,
> nl_ext_ack_fn_t errfn)
> if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
> hlen += mnl_nlmsg_get_payload_len(&err->msg);
>
> - if (mnl_attr_parse(nlh, hlen, err_attr_cb, tb) != MNL_CB_OK)
> + if (mnl_attr_parse(nlh, hlen, err_attr_cb, &tb) != MNL_CB_OK)
> return 0;
>
> - if (tb[NLMSGERR_ATTR_MSG])
> - msg = mnl_attr_get_str(tb[NLMSGERR_ATTR_MSG]);
> + for (i = 0; i < NETLINK_MAX_EXTACK_MSGS && tb.msg[i]; i++)
> + msg[i] = mnl_attr_get_str(tb.msg[i]);
>
> - if (tb[NLMSGERR_ATTR_OFFS]) {
> - off = mnl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS]);
> + if (tb.offs) {
> + off = mnl_attr_get_u32(tb.offs);
>
> if (off > nlh->nlmsg_len) {
> fprintf(stderr,
> @@ -100,21 +111,35 @@ int nl_dump_ext_ack(const struct nlmsghdr *nlh,
> nl_ext_ack_fn_t errfn)
> }
>
> if (errfn)
> - return errfn(msg, off, err_nlh);
> + return errfn(*msg, off, err_nlh); /* FIXME */
>
> - if (msg && *msg != '\0') {
> + ret = 0;
> + for (i = 0; i < NETLINK_MAX_EXTACK_MSGS && msg[i]; i++) {
> bool is_err = !!err->error;
> + const char *_msg = msg[i];
> +
> + /* Message tagging has precedence.
> + * KERN_WARNING = ASCII Start Of Header ('\001') + '4'
> + */
> + if (!strncmp(_msg, "\0014", 2)) {
> + is_err = false;
> + _msg += 2;
> + }
If you are going to have an API that has levels, it must be the same
as existing syslog kernel log format and maybe even get some code reuse.
> + /* But we can't have Error if it didn't fail. */
> + if (is_err && !err->error)
> + is_err = 0;
>
> fprintf(stderr, "%s: %s",
> - is_err ? "Error" : "Warning", msg);
> - if (msg[strlen(msg) - 1] != '.')
> + is_err ? "Error" : "Warning", _msg);
> + if (_msg[strlen(_msg) - 1] != '.')
> fprintf(stderr, ".");
> fprintf(stderr, "\n");
>
> - return is_err ? 1 : 0;
> + if (is_err)
> + ret = 1;
> }
>
> - return 0;
> + return ret;
> }
> #else
> #warning "libmnl required for error support"
