tools: ynl-gen: support struct for binary attributes

Support using a struct pointer for binary attrs. Len field is maintained
because the structs may grow with newer kernel versions. Or, which matters
more, be shorter if the binary is built against newer uAPI than kernel
against which it's executed. Since we are storing a pointer to a struct
type - always allocate at least the amount of memory needed by the struct
per current uAPI headers (unused mem is zeroed). Technically users should
check the length field but per modern ASAN checks storing a short object
under a pointer seems like a bad idea.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250509154213.1747885-4-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index 9a5c65966e9d58b68aba1d7ee48e27b1c8a7e3aa..3b064c61a3740449dec80a7543c53c3a3426dc52 100755 (executable)
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -566,6 +566,23 @@ class TypeBinary(Type):
                 f'memcpy({member}, {self.c_name}, {presence});']
 
 
+class TypeBinaryStruct(TypeBinary):
+    def struct_member(self, ri):
+        ri.cw.p(f'struct {c_lower(self.get("struct"))} *{self.c_name};')
+
+    def _attr_get(self, ri, var):
+        struct_sz = 'sizeof(struct ' + c_lower(self.get("struct")) + ')'
+        len_mem = var + '->_' + self.presence_type() + '.' + self.c_name
+        return [f"{len_mem} = len;",
+                f"if (len < {struct_sz})",
+                f"{var}->{self.c_name} = calloc(1, {struct_sz});",
+                "else",
+                f"{var}->{self.c_name} = malloc(len);",
+                f"memcpy({var}->{self.c_name}, ynl_attr_data(attr), len);"], \
+               ['len = ynl_attr_data_len(attr);'], \
+               ['unsigned int len;']
+
+
 class TypeBinaryScalarArray(TypeBinary):
     def arg_member(self, ri):
         return [f'__{self.get("sub-type")} *{self.c_name}', 'size_t count']
@@ -1010,7 +1027,9 @@ class AttrSet(SpecAttrSet):
         elif elem['type'] == 'string':
             t = TypeString(self.family, self, elem, value)
         elif elem['type'] == 'binary':
-            if elem.get('sub-type') in scalars:
+            if 'struct' in elem:
+                t = TypeBinaryStruct(self.family, self, elem, value)
+            elif elem.get('sub-type') in scalars:
                 t = TypeBinaryScalarArray(self.family, self, elem, value)
             else:
                 t = TypeBinary(self.family, self, elem, value)