[PATCH iproute2-next 2/3] mnl: add fallback implementation for mnl_attr_get_uint()

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@nvidia.com>

libmnl introduced mnl_attr_get_uint() to handle NLA_UINT
variable-width attributes. Add a configure check to detect it
and provide a fallback implementation for older libmnl versions.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
 configure           | 22 ++++++++++++++++++++++
 include/mnl_utils.h |  4 ++++
 lib/mnl_utils.c     | 17 +++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/configure b/configure
index 7437db4f22a8..ebc0d97a6f26 100755
--- a/configure
+++ b/configure
@@ -366,6 +366,24 @@ check_tirpc()
 	fi
 }
 
+have_mnl_attr_get_uint()
+{
+    cat >$TMPDIR/mnl_attr_get_uint_test.c <<EOF
+#include <libmnl/libmnl.h>
+int main(int argc, char **argv)
+{
+	return !!mnl_attr_get_uint(NULL);
+}
+EOF
+
+    $CC -I$INCLUDE $(${PKG_CONFIG} libmnl --cflags --libs 2>/dev/null) \
+	    -o $TMPDIR/mnl_attr_get_uint_test $TMPDIR/mnl_attr_get_uint_test.c >/dev/null 2>&1
+    local ret=$?
+
+    rm -f $TMPDIR/mnl_attr_get_uint_test.c $TMPDIR/mnl_attr_get_uint_test
+    return $ret
+}
+
 check_mnl()
 {
 	if ${PKG_CONFIG} libmnl --exists; then
@@ -374,6 +392,10 @@ check_mnl()
 
 		echo 'CFLAGS += -DHAVE_LIBMNL' "$(${PKG_CONFIG} libmnl --cflags)" >>$CONFIG
 		echo 'LDLIBS +=' "$(${PKG_CONFIG} libmnl --libs)" >> $CONFIG
+
+		if have_mnl_attr_get_uint; then
+			echo "CFLAGS += -DHAVE_MNL_ATTR_GET_UINT" >>$CONFIG
+		fi
 	else
 		echo "no"
 	fi
diff --git a/include/mnl_utils.h b/include/mnl_utils.h
index 0ddf2932db62..4df9e398e591 100644
--- a/include/mnl_utils.h
+++ b/include/mnl_utils.h
@@ -33,4 +33,8 @@ int mnlu_gen_socket_recv_run(struct mnlu_gen_socket *nlg, mnl_cb_t cb,
 			     void *data);
 int mnlu_gen_cmd_dump_policy(struct mnlu_gen_socket *nlg, uint8_t cmd);
 
+#ifndef HAVE_MNL_ATTR_GET_UINT
+uint64_t mnl_attr_get_uint(const struct nlattr *attr);
+#endif
+
 #endif /* __MNL_UTILS_H__ */
diff --git a/lib/mnl_utils.c b/lib/mnl_utils.c
index 5f6671bf94cc..43b4cd1a9e40 100644
--- a/lib/mnl_utils.c
+++ b/lib/mnl_utils.c
@@ -381,3 +381,20 @@ int mnlu_gen_cmd_dump_policy(struct mnlu_gen_socket *nlg, uint8_t cmd)
 
 	return 0;
 }
+
+#ifndef HAVE_MNL_ATTR_GET_UINT
+uint64_t mnl_attr_get_uint(const struct nlattr *attr)
+{
+	switch (mnl_attr_get_payload_len(attr)) {
+	case sizeof(uint8_t):
+		return mnl_attr_get_u8(attr);
+	case sizeof(uint16_t):
+		return mnl_attr_get_u16(attr);
+	case sizeof(uint32_t):
+		return mnl_attr_get_u32(attr);
+	case sizeof(uint64_t):
+		return mnl_attr_get_u64(attr);
+	}
+	return -1ULL;
+}
+#endif
-- 
2.51.1