Line data    Source code

       1             : /*
       2             :  * Unix SMB/CIFS implementation.
       3             :  * Utils around server_id_db with more dependencies
       4             :  * Copyright (C) Volker Lendecke 2014
       5             :  *
       6             :  * This program is free software; you can redistribute it and/or modify
       7             :  * it under the terms of the GNU General Public License as published by
       8             :  * the Free Software Foundation; either version 3 of the License, or
       9             :  * (at your option) any later version.
      10             :  *
      11             :  * This program is distributed in the hope that it will be useful,
      12             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             :  * GNU General Public License for more details.
      15             :  *
      16             :  * You should have received a copy of the GNU General Public License
      17             :  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
      18             :  */
      19             : 
      20             : #include "replace.h"
      21             : #include "server_id_db_util.h"
      22             : #include "lib/util/server_id.h"
      23             : #include "serverid.h"
      24             : #include "lib/util/samba_util.h"
      25             : 
      26             : static int server_id_db_check_exclusive(
      27             :         struct server_id_db *db, const char *name,
      28             :         unsigned num_servers, struct server_id *servers);
      29             : 
      30           0 : int server_id_db_set_exclusive(struct server_id_db *db, const char *name)
      31             : {
      32             :         int ret;
      33             :         unsigned num_servers;
      34             :         struct server_id *servers;
      35             : 
      36           0 :         ret = server_id_db_add(db, name);
      37           0 :         if (ret != 0) {
      38           0 :                 return ret;
      39             :         }
      40             : 
      41           0 :         ret = server_id_db_lookup(db, name, talloc_tos(),
      42             :                                   &num_servers, &servers);
      43           0 :         if (ret != 0) {
      44           0 :                 goto done;
      45             :         }
      46             : 
      47             :         /*
      48             :          * Remove entries from the server_id_db for processes that have died
      49             :          * and could not clean up. This is racy, as two processes could
      50             :          * simultaneously try to register a name. Both would succeed in the
      51             :          * server_id_db_add call, and both would see their peer active during
      52             :          * the check_exclusive call. Both would get an EEXIST, and nobody
      53             :          * would be able to register itself. But this is okay, as this is
      54             :          * meant to be a cleanup routine, and normally only one daemon should
      55             :          * start up at a time anyway. Getting this "right" would mean we would
      56             :          * have to add locking to server_id_db, or add a dependency on
      57             :          * serverids_exist to server_id_db. Both are too heavy-weight for my
      58             :          * taste.
      59             :          */
      60             : 
      61           0 :         ret = server_id_db_check_exclusive(db, name, num_servers, servers);
      62           0 :         TALLOC_FREE(servers);
      63             : 
      64           0 : done:
      65           0 :         if (ret != 0) {
      66           0 :                 server_id_db_remove(db, name);
      67             :         }
      68           0 :         return ret;
      69             : }
      70             : 
      71           0 : static int server_id_db_check_exclusive(
      72             :         struct server_id_db *db, const char *name,
      73             :         unsigned num_servers, struct server_id *servers)
      74             : {
      75           0 :         struct server_id me = server_id_db_pid(db);
      76             :         unsigned i;
      77             : 
      78           0 :         for (i=0; i<num_servers; i++) {
      79             :                 int ret;
      80             : 
      81           0 :                 if (server_id_same_process(&me, &servers[i])) {
      82             :                         /*
      83             :                          * I am always around ... :-)
      84             :                          */
      85           0 :                         continue;
      86             :                 }
      87             : 
      88           0 :                 if (serverid_exists(&servers[i])) {
      89           0 :                         return EEXIST;
      90             :                 }
      91             : 
      92           0 :                 ret = server_id_db_prune_name(db, name, servers[i]);
      93           0 :                 if (ret != 0) {
      94           0 :                         return ret;
      95             :                 }
      96             :         }
      97             : 
      98           0 :         return 0;
      99             : }