The branch main has been updated by olce:
URL:
https://cgit.FreeBSD.org/src/commit/?id=0abeb8d8d8df1842b0c2d2276c958b0150579a1c
commit 0abeb8d8d8df1842b0c2d2276c958b0150579a1c
Author: Olivier Certner <o...@freebsd.org>
AuthorDate: 2025-08-27 14:33:24 +0000
Commit: Olivier Certner <o...@freebsd.org>
CommitDate: 2025-09-17 12:16:02 +0000
cred: 'struct ucred': Rework comment on 'cr_gid'/cr_groups[]
Make it more straightforward for consumers. Also, recommend using
cr_sgroups[] for supplementary groups, as this can generally alleviate
index problems and will help us spot and change consumers if/when
'struct ucred' is evolved incompatibly (and cr_sgroups[] suppressed).
MFC after: 5 days
MFC to: stable/15
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52269
---
sys/sys/ucred.h | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h
index 9c1d8545af34..254f58841993 100644
--- a/sys/sys/ucred.h
+++ b/sys/sys/ucred.h
@@ -112,15 +112,21 @@ struct xucred {
short cr_ngroups; /* number of groups (incl. cr_gid). */
union {
/*
- * Special little hack to avoid needing a cr_gid macro, which
- * would cause problems if one were to use it with struct ucred
- * which also has a cr_groups member.
+ * The effective GID has been the first element of cr_groups[]
+ * for historical reasons. It should be accessed using the
+ * 'cr_gid' identifier. Supplementary groups should be accessed
+ * using cr_sgroups[]. Note that 'cr_ngroups' currently
+ * includes the effective GID.
+ *
+ * XXXOC: On the next API change (requires versioning), please
+ * replace this union with a true unaliased field 'cr_gid' and
+ * make sure that cr_groups[]/'cr_ngroups' only account for
+ * supplementary groups.
*/
struct {
gid_t cr_gid; /* effective group id */
gid_t cr_sgroups[XU_NGROUPS - 1];
};
-
gid_t cr_groups[XU_NGROUPS]; /* groups */
};
union {
