From RedHat's patch shadow-4.1.2-sysAccountDownhill.patch

Thanks to Peter Vrabec.
	* NEWS, libmisc/find_new_gid.c, libmisc/find_new_uid.c: Build an
	index of used IDs to avoid a database request for each id in the
	allowed range (when the highest allowed ID is already used).
	This speedups the addition of users or groups when the highest
	allowed ID is already used. The additional memory usage of the
	tools should be acceptable when UID_MAX/SYS_UID_MAX are set to a
	reasonable number.

ChangeLog

@@ -1,3 +1,15 @@
+2008-09-07  Nicolas François  <nicolas.francois@centraliens.net>
+
+	From RedHat's patch shadow-4.1.2-sysAccountDownhill.patch
+	Thanks to Peter Vrabec.
+	* NEWS, libmisc/find_new_gid.c, libmisc/find_new_uid.c: Build an
+	index of used IDs to avoid a database request for each id in the
+	allowed range (when the highest allowed ID is already used).
+	This speedups the addition of users or groups when the highest
+	allowed ID is already used. The additional memory usage of the
+	tools should be acceptable when UID_MAX/SYS_UID_MAX are set to a
+	reasonable number.
+
 2008-09-07  Nicolas François  <nicolas.francois@centraliens.net>
 
 	* configure.in: Fix the dependency of ACCT_TOOLS_SETUID on

NEWS

@@ -12,6 +12,10 @@ shadow-4.1.2.1 -> shadow-4.1.3						UNRELEASED
     groupadd, groupdel, groupmod, newusers, useradd, userdel, and usermod.
     This authentication is not necessary when these tools are not
     installed setuid root.
+- addition of users or groups
+  * Speed improvement in case UID_MAX/SYS_UID_MAX/GID_MAX/SYS_GID_MAX is
+    used for an user/group. This should be noticeable in case of LDAP
+    configured systems. This should impact useradd, groupadd, and newusers
 
 - gpasswd
   * Added support for long options --add (-a), --delete (-d),
@@ -19,6 +23,7 @@ shadow-4.1.2.1 -> shadow-4.1.3						UNRELEASED
     --members (-M).
 - groupadd
   * audit logging improvements.
+  * Speedup (see "addition of users or groups" above).
 - groupdel
   * audit logging improvements.
 - groupmems
@@ -35,12 +40,14 @@ shadow-4.1.2.1 -> shadow-4.1.3						UNRELEASED
     --list (-l), --group (-g).
 - newusers
   * Implement the -r, --system option.
+  * Speedup (see "addition of users or groups" above).
 - passwd
   * For compatibility with other passwd version, the --lock an --unlock
     options do not lock or unlock the user account anymore.  They only
     lock or unlock the user's password.
 - useradd
   * audit logging improvements.
+  * Speedup (see "addition of users or groups" above).
 - userdel
   * audit logging improvements.
 - usermod

libmisc/find_new_gid.c

@@ -51,6 +51,7 @@ int find_new_gid (bool sys_group, gid_t *gid, gid_t const *preferred_gid)
 {
 	const struct group *grp;
 	gid_t gid_min, gid_max, group_id;
+	char *used_gids;
 
 	assert (gid != NULL);
 
@@ -62,6 +63,8 @@ int find_new_gid (bool sys_group, gid_t *gid, gid_t const *preferred_gid)
 		gid_max = getdef_ulong ("GID_MIN", 1000L) - 1;
 		gid_max = getdef_ulong ("SYS_GID_MAX", (unsigned long) gid_max);
 	}
+	used_gids = alloca (sizeof (char) * gid_max +1);
+	memset (used_gids, 0, sizeof (char) * gid_max + 1);
 
 	if (   (NULL != preferred_gid)
 	    && (*preferred_gid >= gid_min)
@@ -81,8 +84,8 @@ int find_new_gid (bool sys_group, gid_t *gid, gid_t const *preferred_gid)
 	 * Search the entire group file,
 	 * looking for the largest unused value.
 	 *
-	 * We check the list of users according to NSS (setpwent/getpwent),
+	 * We check the list of groups according to NSS (setgrent/getgrent),
-	 * but we also check the local database (pw_rewind/pw_next) in case
+	 * but we also check the local database (gr_rewind/gr_next) in case
 	 * some groups were created but the changes were not committed yet.
 	 */
 	setgrent ();
@@ -92,20 +95,21 @@ int find_new_gid (bool sys_group, gid_t *gid, gid_t const *preferred_gid)
 		if ((grp->gr_gid >= group_id) && (grp->gr_gid <= gid_max)) {
 			group_id = grp->gr_gid + 1;
 		}
+		/* create index of used GIDs */
+		if (grp->gr_gid <= gid_max) {
+			used_gids[grp->gr_gid] = 1;
+		}
 	}
 	endgrent ();
 
 	/*
 	 * If a group with GID equal to GID_MAX exists, the above algorithm
 	 * will give us GID_MAX+1 even if not unique. Search for the first
-	 * free GID starting with GID_MIN (it's O(n*n) but can be avoided
+	 * free GID starting with GID_MIN.
-	 * by not having users with GID equal to GID_MAX).  --marekm
 	 */
 	if (group_id == gid_max + 1) {
 		for (group_id = gid_min; group_id < gid_max; group_id++) {
-			/* local, no need for xgetgrgid */
+			if (0 == used_gids[grp->gr_gid]) {
-			if (   (getgrgid (group_id) == NULL)
-			    && (gr_locate_gid (group_id) == NULL)) {
 				break;
 			}
 		}

libmisc/find_new_uid.c

@@ -51,6 +51,7 @@ int find_new_uid (bool sys_user, uid_t *uid, uid_t const *preferred_uid)
 {
 	const struct passwd *pwd;
 	uid_t uid_min, uid_max, user_id;
+	char *used_uids;
 
 	assert (uid != NULL);
 
@@ -62,6 +63,8 @@ int find_new_uid (bool sys_user, uid_t *uid, uid_t const *preferred_uid)
 		uid_max = getdef_ulong ("UID_MIN", 1000L) - 1;
 		uid_max = getdef_ulong ("SYS_UID_MAX", (unsigned long) uid_max);
 	}
+	used_uids = alloca (sizeof (char) * uid_max +1);
+	memset (used_uids, 0, sizeof (char) * uid_max + 1);
 
 	if (   (NULL != preferred_uid)
 	    && (*preferred_uid >= uid_min)
@@ -93,20 +96,21 @@ int find_new_uid (bool sys_user, uid_t *uid, uid_t const *preferred_uid)
 		if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) {
 			user_id = pwd->pw_uid + 1;
 		}
+		/* create index of used UIDs */
+		if (pwd->pw_uid <= uid_max) {
+			used_uids[pwd->pw_uid] = 1;
+		}
 	}
 	endpwent ();
 
 	/*
 	 * If a user with UID equal to UID_MAX exists, the above algorithm
 	 * will give us UID_MAX+1 even if not unique. Search for the first
-	 * free UID starting with UID_MIN (it's O(n*n) but can be avoided
+	 * free UID starting with UID_MIN.
-	 * by not having users with UID equal to UID_MAX).  --marekm
 	 */
 	if (user_id == uid_max + 1) {
 		for (user_id = uid_min; user_id < uid_max; user_id++) {
-			/* local, no need for xgetpwuid */
+			if (0 == used_uids[pwd->pw_uid]) {
-			if (   (getpwuid (user_id) == NULL)
-			    && (pw_locate_uid (user_id) == NULL)) {
 				break;
 			}
 		}