git: c55330ce4d1a - stable/13 - groupmember(): Extract the supplementary group search in a separate function

The branch stable/13 has been updated by olce:

URL: https://cgit.FreeBSD.org/src/commit/?id=c55330ce4d1a8cfa214299872f243d1dffc90376

commit c55330ce4d1a8cfa214299872f243d1dffc90376
Author:     Olivier Certner <olce.freebsd@certner.fr>
AuthorDate: 2023-08-17 23:54:44 +0000
Commit:     Olivier Certner <olce@FreeBSD.org>
CommitDate: 2023-12-21 13:37:45 +0000

    groupmember(): Extract the supplementary group search in a separate function
    
    This is in preparation for the introduction of the new realgroupmember()
    function, which does the same search into supplementary groups as
    groupmember().
    
    Reviewed by:            mhorne
    Sponsored by:           Kumacom SAS
    Differential Revision:  https://reviews.freebsd.org/D40640
    
    (cherry picked from commit b725f232f3b09b4bcbc426854fe1545234c66965)
    
    Approved by:    markj (mentor)
---
 sys/kern/kern_prot.c | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c
index 7f196a446315..682754dd7687 100644
--- a/sys/kern/kern_prot.c
+++ b/sys/kern/kern_prot.c
@@ -1275,36 +1275,43 @@ sys___setugid(struct thread *td, struct __setugid_args *uap)
 }
 
 /*
- * Check if gid is a member of the group set.
+ * Returns whether gid designates a supplementary group in cred.
  */
-int
-groupmember(gid_t gid, struct ucred *cred)
+static int
+supplementary_group_member(gid_t gid, struct ucred *cred)
 {
-	int l;
-	int h;
-	int m;
-
-	if (cred->cr_groups[0] == gid)
-		return(1);
+	int l, h, m;
 
 	/*
-	 * If gid was not our primary group, perform a binary search
-	 * of the supplemental groups.  This is possible because we
-	 * sort the groups in crsetgroups().
+	 * Perform a binary search of the supplemental groups.  This is possible
+	 * because we sort the groups in crsetgroups().
 	 */
 	l = 1;
 	h = cred->cr_ngroups;
+
 	while (l < h) {
-		m = l + ((h - l) / 2);
+		m = l + (h - l) / 2;
 		if (cred->cr_groups[m] < gid)
-			l = m + 1; 
+			l = m + 1;
 		else
-			h = m; 
+			h = m;
 	}
-	if ((l < cred->cr_ngroups) && (cred->cr_groups[l] == gid))
+
+	return (l < cred->cr_ngroups && cred->cr_groups[l] == gid);
+}
+
+/*
+ * Check if gid is a member of the (effective) group set (i.e., effective and
+ * supplementary groups).
+ */
+int
+groupmember(gid_t gid, struct ucred *cred)
+{
+
+	if (cred->cr_groups[0] == gid)
 		return (1);
 
-	return (0);
+	return (supplementary_group_member(gid, cred));
 }
 
 /*