nlattr: factor out AF_SPEC-typed netlink attribute decoding

decode_ifstats_af and decode_ifla_af do about the same thing, except
the latter employs AF-indexed array and the former uses a list.  This
is going to change with the addition of AF_MCTP protocol IFLA_AF_SPEC
decoding support, as its address family number (45) necessitates
the switch from AF-indexed array to a list as well, so these two
decoders are going to have exactly the same logic, and that is a reason
for factoring it out in a separate function.

* src/nlattr.h (struct af_spec_decoder_desc): New type definition.
(decode_nla_af_spec): New declaration.
* src/nlattr.c (decode_nla_af_spec): New function.
* src/rtnl_link.c (ifla_af_spec_protos): Move inside decode_ifla_af,
rename to protos, change type to struct af_spec_decoder_desc[],
initialise af fields of each item.
(decode_ifla_af): Call decode_nla_af_spec.
(decode_ifstats_af): Change type of the protos local variable
to struct af_spec_decoder_desc[], replace the body with a call
to decode_nla_af_spec.

1 files changed, 27 insertions, 0 deletions

diff --git a/src/nlattr.c b/src/nlattr.c
index 295d29105..9b4879a84 100644
--- a/src/nlattr.c
+++ b/src/nlattr.c
@@ -427,6 +427,33 @@ decode_nla_flags(struct tcb *const tcp,
 	return true;
 }
 
+void
+decode_nla_af_spec(struct tcb *const tcp,
+		   const kernel_ulong_t addr,
+		   const unsigned int len,
+		   uint8_t af,
+		   const struct af_spec_decoder_desc *descs,
+		   size_t desc_cnt)
+{
+	const struct af_spec_decoder_desc *const descs_end = descs + desc_cnt;
+	const struct af_spec_decoder_desc *desc = descs;
+
+	for (; desc < descs_end; desc++) {
+		if (desc->af == af)
+			break;
+	}
+
+	if (desc >= descs_end) {
+		printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
+
+	} else {
+		decode_nlattr(tcp, addr, len,
+			      desc->xlat, desc->dflt, desc->table, desc->size,
+			      NULL);
+	}
+}
+
+
 bool
 decode_nla_be16(struct tcb *const tcp,
 		const kernel_ulong_t addr,