On 27/07/2021 22.57, Kees Cook wrote:

In order to have a regular programmatic way to describe a struct
region that can be used for references and sizing, can be examined for
bounds checking, avoids forcing the use of intermediate identifiers,
and avoids polluting the global namespace, introduce the struct_group()
macro. This macro wraps the member declarations to create an anonymous
union of an anonymous struct (no intermediate name) and a named struct
(for references and sizing):

	struct foo {
		int one;
		struct_group(thing,
			int two,
			int three,
		);
		int four;
	};

That example won't compile, the commas after two and three should be
semicolons.

And your implementation relies on MEMBERS not containing any comma
tokens, but as

  int a, b, c, d;

is a valid way to declare multiple members, consider making MEMBERS
variadic

#define struct_group(NAME, MEMBERS...)

to have it slurp up every subsequent argument and make that work.

Co-developed-by: Keith Packard <redacted>
Signed-off-by: Keith Packard <redacted>
Signed-off-by: Kees Cook <redacted>
---
 include/linux/stddef.h | 34 ++++++++++++++++++++++++++++++++++

Bikeshedding a bit, but do we need to add 34 lines that need to be
preprocessed to virtually each and every translation unit [as opposed to
adding a struct_group.h header]? Oh well, you need it for struct
skbuff.h, so it would be pulled in by a lot regardless :(

Rasmus