s3: use getgrset() when it is available

When getgrouplist() is not defined, use getgrset() if it is defined
instead of using the initgroups() + getgroups() combo

Major contributions from Yannick Bergeron <yaberger@ca.ibm.com>

Autobuild-User: Volker Lendecke <vlendec@samba.org>
Autobuild-Date: Sat Mar 19 10:09:38 CET 2011 on sn-devel-104

3 files changed, 59 insertions, 3 deletions

diff --git a/source3/configure.in b/source3/configure.in
index 74df9d4836..6033b0b13b 100644
--- a/source3/configure.in
+++ b/source3/configure.in
@@ -1070,6 +1070,7 @@ AC_CHECK_FUNCS(fdatasync,,[AC_CHECK_LIB_EXT(rt, LIBS, fdatasync)])
 AC_CHECK_FUNCS(setsid glob strpbrk crypt16 getauthuid)
 AC_CHECK_FUNCS(sigprocmask sigblock sigaction sigset innetgr setnetgrent getnetgrent endnetgrent)
 AC_CHECK_FUNCS(initgroups select rdchk getgrnam getgrent pathconf)
+AC_CHECK_FUNCS(getgrset)
 AC_CHECK_FUNCS(setpriv setgidx setuidx setgroups sysconf stat64 fstat64)
 AC_CHECK_FUNCS(lstat64 fopen64 atexit grantpt lseek64 ftruncate64 posix_fallocate posix_fallocate64)
 AC_CHECK_FUNCS(fallocate fallocate64)
diff --git a/source3/lib/system_smbd.c b/source3/lib/system_smbd.c
index 3bb2c4240b..12538c4434 100644
--- a/source3/lib/system_smbd.c
+++ b/source3/lib/system_smbd.c
@@ -28,6 +28,56 @@
 
 #ifndef HAVE_GETGROUPLIST
 
+#ifdef HAVE_GETGRSET
+static int getgrouplist_getgrset(const char *user, gid_t gid, gid_t *groups,
+				 int *grpcnt)
+{
+	char *grplist;
+	char *grp;
+	gid_t temp_gid;
+	int num_gids = 1;
+	int ret = 0;
+	long l;
+
+	grplist = getgrset(user);
+
+	DEBUG(10, ("getgrset returned %s\n", grplist));
+
+	if (grplist == NULL) {
+		return -1;
+	}
+
+	if (*grpcnt > 0) {
+		groups[0] = gid;
+	}
+
+	while ((grp = strsep(&grplist, ",")) != NULL) {
+		l = strtol(grp, NULL, 10);
+		temp_gid = (gid_t) l;
+		if (temp_gid == gid) {
+			continue;
+		}
+
+		if (num_gids + 1 > *grpcnt) {
+			num_gids++;
+			continue;
+		}
+		groups[num_gids++] = temp_gid;
+	}
+	free(grplist);
+
+	if (num_gids > *grpcnt) {
+		ret = -1;
+	}
+	*grpcnt = num_gids;
+
+	DEBUG(10, ("Found %d groups for user %s\n", *grpcnt, user));
+
+	return ret;
+}
+
+#else /* HAVE_GETGRSET */
+
 /*
   This is a *much* faster way of getting the list of groups for a user
   without changing the current supplementary group list. The old
@@ -113,7 +163,8 @@ static int getgrouplist_internals(const char *user, gid_t gid, gid_t *groups,
 	free(gids_saved);
 	return ret;
 }
-#endif
+#endif /* HAVE_GETGRSET */
+#endif /* HAVE_GETGROUPLIST */
 
 static int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
 {
@@ -131,10 +182,14 @@ static int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grp
 #ifdef HAVE_GETGROUPLIST
 	retval = getgrouplist(user, gid, groups, grpcnt);
 #else
+#ifdef HAVE_GETGRSET
+	retval = getgrouplist_getgrset(user, gid, groups, grpcnt);
+#else
 	become_root();
 	retval = getgrouplist_internals(user, gid, groups, grpcnt);
 	unbecome_root();
-#endif
+#endif /* HAVE_GETGRSET */
+#endif /* HAVE_GETGROUPLIST */
 
 	/* allow winbindd lookups, but only if they were not already disabled */
 	if (!winbind_env) {
diff --git a/source3/wscript b/source3/wscript
index 9fcf173065..e8bd62598b 100644
--- a/source3/wscript
+++ b/source3/wscript
@@ -269,7 +269,7 @@ _fork __fork fremoveea fremovexattr fseek64 fseeko64 fsetea
 fsetproplist fsetxattr _fstat __fstat fstat64 _fstat64 __fstat64 fsync
 ftell64 ftello64 ftruncate64 futimens futimes __fxstat getauthuid
 getcwd _getcwd __getcwd getdents __getdents getdents64 getdirentries
-getgrent getgrnam getgrouplist getmntent getpagesize
+getgrent getgrnam getgrouplist getgrset getmntent getpagesize
 getproplist get_proplist_entry getpwanam getpwent_r getrlimit gettext
 glob grantpt hstrerror initgroups innetgr
 inotify_init lgetea lgetxattr listea listxattr llistea llistxattr