[PATCH net-next v4 2/7] tools: ynl: Add C array attribute decoding to ynl

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

Add support for decoding C arrays from binay blobs in genetlink-legacy
messages.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
---
 tools/net/ynl/lib/ynl.py | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index 98ecfdb44a83..b635d147175c 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -68,6 +68,11 @@ class Netlink:
 
 
 class NlAttr:
+    type_formats = { 'u8' : ('B', 1), 's8' : ('b', 1),
+                     'u16': ('H', 2), 's16': ('h', 2),
+                     'u32': ('I', 4), 's32': ('i', 4),
+                     'u64': ('Q', 8), 's64': ('q', 8) }
+
     def __init__(self, raw, offset):
         self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
         self.type = self._type & ~Netlink.NLA_TYPE_MASK
@@ -93,6 +98,10 @@ class NlAttr:
     def as_bin(self):
         return self.raw
 
+    def as_c_array(self, type):
+        format, _ = self.type_formats[type]
+        return list({ x[0] for x in struct.iter_unpack(format, self.raw) })
+
     def __repr__(self):
         return f"[type:{self.type} len:{self._len}] {self.raw}"
 
@@ -363,6 +372,14 @@ class YnlFamily(SpecFamily):
             value = enum.entries_by_val[raw - i].name
         rsp[attr_spec['name']] = value
 
+    def _decode_binary(self, attr, attr_spec):
+        sub_type = attr_spec.get('sub-type')
+        if sub_type:
+            decoded = attr.as_c_array(sub_type)
+        else:
+            decoded = attr.as_bin()
+        return decoded
+
     def _decode(self, attrs, space):
         attr_space = self.attr_sets[space]
         rsp = dict()
@@ -380,7 +397,7 @@ class YnlFamily(SpecFamily):
             elif attr_spec["type"] == 'string':
                 decoded = attr.as_strz()
             elif attr_spec["type"] == 'binary':
-                decoded = attr.as_bin()
+                decoded = self._decode_binary(attr, attr_spec)
             elif attr_spec["type"] == 'flag':
                 decoded = True
             else:
-- 
2.39.0