diff options
| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2025-09-17 15:28:07 +0200 |
|---|---|---|
| committer | Kees Cook <kees@kernel.org> | 2025-09-17 09:29:43 -0700 |
| commit | 2bbdcf02c3f3df6c85abd0a2fee0d7f0f4113e96 (patch) | |
| tree | a44f0ae5f25d3e263ae30540ea71e72ac289e8d3 /include | |
| parent | stddef: Remove token-pasting in TRAILING_OVERLAP() (diff) | |
| download | linux-2bbdcf02c3f3df6c85abd0a2fee0d7f0f4113e96.tar.gz linux-2bbdcf02c3f3df6c85abd0a2fee0d7f0f4113e96.zip | |
stddef: Introduce __TRAILING_OVERLAP()
Introduce underlying __TRAILING_OVERLAP() macro to let callers apply
atributes to trailing overlapping members.
For instance, the code below:
| struct flex {
| size_t count;
| int data[];
| };
| struct {
| struct flex f;
| struct foo a;
| struct boo b;
| } __packed instance;
can now be changed to the following, and preserve the __packed
attribute:
| __TRAILING_OVERLAP(struct flex, f, data, __packed,
| struct foo a;
| struct boo b;
| ) instance;
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/f80c529b239ce11f0a51f714fe00ddf839e05f5e.1758115257.git.gustavoars@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/stddef.h | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/include/linux/stddef.h b/include/linux/stddef.h index 701099c67c24..80b6bfb944f0 100644 --- a/include/linux/stddef.h +++ b/include/linux/stddef.h @@ -94,7 +94,8 @@ enum { __DECLARE_FLEX_ARRAY(TYPE, NAME) /** - * TRAILING_OVERLAP() - Overlap a flexible-array member with trailing members. + * __TRAILING_OVERLAP() - Overlap a flexible-array member with trailing + * members. * * Creates a union between a flexible-array member (FAM) in a struct and a set * of additional members that would otherwise follow it. @@ -102,15 +103,30 @@ enum { * @TYPE: Flexible structure type name, including "struct" keyword. * @NAME: Name for a variable to define. * @FAM: The flexible-array member within @TYPE + * @ATTRS: Any struct attributes (usually empty) * @MEMBERS: Trailing overlapping members. */ -#define TRAILING_OVERLAP(TYPE, NAME, FAM, MEMBERS) \ +#define __TRAILING_OVERLAP(TYPE, NAME, FAM, ATTRS, MEMBERS) \ union { \ TYPE NAME; \ struct { \ unsigned char __offset_to_FAM[offsetof(TYPE, FAM)]; \ MEMBERS \ - }; \ + } ATTRS; \ } +/** + * TRAILING_OVERLAP() - Overlap a flexible-array member with trailing members. + * + * Creates a union between a flexible-array member (FAM) in a struct and a set + * of additional members that would otherwise follow it. + * + * @TYPE: Flexible structure type name, including "struct" keyword. + * @NAME: Name for a variable to define. + * @FAM: The flexible-array member within @TYPE + * @MEMBERS: Trailing overlapping members. + */ +#define TRAILING_OVERLAP(TYPE, NAME, FAM, MEMBERS) \ + __TRAILING_OVERLAP(TYPE, NAME, FAM, /* no attrs */, MEMBERS) + #endif |