Index: b/usr/src/head/grp.h
===================================================================
--- a/usr/src/head/grp.h
+++ b/usr/src/head/grp.h
@@ -52,6 +52,10 @@ struct	group {	/* see getgrent(3C) */
 	char	**gr_mem;
 };
 
+#if defined(__EXTENSIONS__) || defined(_BSD_SOURCE)
+int getgrouplist(const char *, gid_t, gid_t *, int *);
+#endif
+
 extern struct group *getgrgid(gid_t);		/* MT-unsafe */
 extern struct group *getgrnam(const char *);	/* MT-unsafe */
 
Index: b/usr/src/lib/libc/amd64/Makefile
===================================================================
--- a/usr/src/lib/libc/amd64/Makefile
+++ b/usr/src/lib/libc/amd64/Makefile
@@ -203,6 +203,7 @@ COMSYSOBJS=			\
 	getegid.o		\
 	geteuid.o		\
 	getgid.o		\
+	getgrouplist.o		\
 	getgroups.o		\
 	gethrtime.o		\
 	getitimer.o		\
Index: b/usr/src/lib/libc/i386/Makefile.com
===================================================================
--- a/usr/src/lib/libc/i386/Makefile.com
+++ b/usr/src/lib/libc/i386/Makefile.com
@@ -437,6 +437,7 @@ PORTGEN=			\
 	getexecname.o		\
 	getgrnam.o		\
 	getgrnam_r.o		\
+	getgrouplist.o		\
 	gethostid.o		\
 	gethostname.o		\
 	gethz.o			\
Index: b/usr/src/lib/libc/port/gen/getgrouplist.c
===================================================================
--- /dev/null
+++ b/usr/src/lib/libc/port/gen/getgrouplist.c
@@ -0,0 +1,89 @@
+/*  $OpenBSD: getgrouplist.c,v 1.12 2005/08/08 08:05:34 espie Exp $ */
+/*
+ * Copyright (c) 1991, 1993
+ *  The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* OPENBSD ORIGINAL: lib/libc/gen/getgrouplist.c */
+
+/*
+ * get credential
+ */
+#include <sys/types.h>
+#include <string.h>
+#include <unistd.h>
+#include <grp.h>
+
+int
+getgrouplist(const char *uname, gid_t agroup, gid_t *groups, int *grpcnt)
+{
+    struct group *grp;
+    int i, ngroups;
+    int ret, maxgroups;
+    int bail;
+
+    ret = 0;
+    ngroups = 0;
+    maxgroups = *grpcnt;
+
+    /*
+     * install primary group
+     */
+    if (ngroups >= maxgroups) {
+        *grpcnt = ngroups;
+        return (-1);
+    }
+    groups[ngroups++] = agroup;
+
+    /*
+     * Scan the group file to find additional groups.
+     */
+    setgrent();
+    while ((grp = getgrent())) {
+        if (grp->gr_gid == agroup)
+            continue;
+        for (bail = 0, i = 0; bail == 0 && i < ngroups; i++)
+            if (groups[i] == grp->gr_gid)
+                bail = 1;
+        if (bail)
+            continue;
+        for (i = 0; grp->gr_mem[i]; i++) {
+            if (!strcmp(grp->gr_mem[i], uname)) {
+                if (ngroups >= maxgroups) {
+                    ret = -1;
+                    goto out;
+                }
+                groups[ngroups++] = grp->gr_gid;
+                break;
+            }
+        }
+    }
+out:
+    endgrent();
+    *grpcnt = ngroups;
+    return (ret);
+}
Index: b/usr/src/lib/libc/port/mapfile-vers
===================================================================
--- a/usr/src/lib/libc/port/mapfile-vers
+++ b/usr/src/lib/libc/port/mapfile-vers
@@ -280,6 +280,7 @@ SYMBOL_VERSION DYSON_1 {
         fts_open;
         fts_read;
         fts_set;
+        getgrouplist;
         gnu_strerror_r;
         mempcpy;
         memrchr;