[PATCH net-next v4 3/7] tools: ynl: Add struct attr decoding to ynl

[Donald Hunter <donald.hunter@gmail.com>]

Add support for decoding attributes that contain C structs.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
---
 Documentation/netlink/genetlink-legacy.yaml |  5 +++++
 tools/net/ynl/lib/ynl.py                    | 15 ++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/genetlink-legacy.yaml b/Documentation/netlink/genetlink-legacy.yaml
index 5dc6f1c07a97..d50c78b9f42d 100644
--- a/Documentation/netlink/genetlink-legacy.yaml
+++ b/Documentation/netlink/genetlink-legacy.yaml
@@ -218,6 +218,11 @@ properties:
                     description: Max length for a string or a binary attribute.
                     $ref: '#/$defs/len-or-define'
               sub-type: *attr-type
+              # Start genetlink-legacy
+              struct:
+                description: Name of the struct type used for the attribute.
+                type: string
+              # End genetlink-legacy
 
       # Make sure name-prefix does not appear in subsets (subsets inherit naming)
       dependencies:
diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index b635d147175c..af1d6d380035 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -102,6 +102,16 @@ class NlAttr:
         format, _ = self.type_formats[type]
         return list({ x[0] for x in struct.iter_unpack(format, self.raw) })
 
+    def as_struct(self, members):
+        value = dict()
+        offset = 0
+        for m in members:
+            format, size = self.type_formats[m.type]
+            decoded = struct.unpack_from(format, self.raw, offset)
+            offset += size
+            value[m.name] = decoded[0]
+        return value
+
     def __repr__(self):
         return f"[type:{self.type} len:{self._len}] {self.raw}"
 
@@ -373,8 +383,11 @@ class YnlFamily(SpecFamily):
         rsp[attr_spec['name']] = value
 
     def _decode_binary(self, attr, attr_spec):
+        struct_name = attr_spec.get('struct')
         sub_type = attr_spec.get('sub-type')
-        if sub_type:
+        if struct_name:
+            decoded = attr.as_struct(self.consts[struct_name])
+        elif sub_type:
             decoded = attr.as_c_array(sub_type)
         else:
             decoded = attr.as_bin()
-- 
2.39.0