From b46d79c8792cd5de9aded0c83956cd5ac76f8697 Mon Sep 17 00:00:00 2001
From: =?utf8?q?=C3=81lvaro=20Fern=C3=A1ndez=20Rojas?= <noltari@gmail.com>
Date: Thu, 13 Nov 2025 11:46:51 +0100
Subject: [PATCH] odhcp6c: properly guard attributes
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Properly guard odhcp6c.h attributes with `#ifndef` to avoid redefining them
when including external headers.
Also convert the remaining __attribute__ usages to the custom declarations.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Link: https://github.com/openwrt/odhcp6c/pull/120
---
 src/odhcp6c.h | 14 +++++++++++---
 src/ra.c      |  4 ++--
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/odhcp6c.h b/src/odhcp6c.h
index 6c669c0..02578cc 100644
--- a/src/odhcp6c.h
+++ b/src/odhcp6c.h
@@ -20,9 +20,17 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#define _o_unused __attribute__((unused))
-#define _o_packed __attribute__((packed))
+#ifndef _o_aligned
 #define _o_aligned(n) __attribute__((aligned(n)))
+#endif /* _o_aligned */
+
+#ifndef _o_packed
+#define _o_packed __attribute__((packed))
+#endif /* _o_packed */
+
+#ifndef _o_unused
+#define _o_unused __attribute__((unused))
+#endif /* _o_unused */
 
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
 
@@ -278,7 +286,7 @@ struct dhcpv6_retx {
 struct dhcpv6_header {
 	uint8_t msg_type;
 	uint8_t tr_id[3];
-} __attribute__((packed));
+} _o_packed;
 
 struct dhcpv6_ia_hdr {
 	uint16_t type;
diff --git a/src/ra.c b/src/ra.c
index ffff0aa..dcc5fd6 100644
--- a/src/ra.c
+++ b/src/ra.c
@@ -71,7 +71,7 @@ struct {
 	.lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
 };
 
-static void ra_send_rs(int signal __attribute__((unused)));
+static void ra_send_rs(_o_unused int signal);
 
 int ra_init(const char *ifname, const struct in6_addr *ifid,
 		unsigned int options, unsigned int holdoff_interval)
@@ -189,7 +189,7 @@ failure:
 	return -1;
 }
 
-static void ra_send_rs(int signal __attribute__((unused)))
+static void ra_send_rs(_o_unused int signal)
 {
 	const struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, if_index};
 	const struct icmpv6_opt llnull = {ND_OPT_SOURCE_LINKADDR, 1, {0}};
-- 
2.30.2