Merge branch 't/recycling'

diff --combined dss.c
index b4ad2d28960a3c89e9b489d365f45ffed1376e8e,223f80e086e66b6ae3367e84292de91c62a9195a..3508d38d798c1af448398c2de1d0b438a61bb4e4
--- 1/dss.c
--- 2/dss.c
+++ b/dss.c
@@@ -1,5 -1,5 +1,5 @@@
  /*
 - * Copyright (C) 2008-2009 Andre Noll <maan@systemlinux.org>
 + * Copyright (C) 2008-2010 Andre Noll <maan@systemlinux.org>
   *
   * Licensed under the GPL v2. For licencing details see COPYING.
   */
@@@ -964,7 -964,7 +964,7 @@@ static int parse_config_file(int overri
                        conf.logfile_given = 1;
                }
        }
 -      if (conf.logfile_given) {
 +      if (conf.logfile_given && conf.run_given && conf.daemon_given) {
                logfile = open_log(conf.logfile_arg);
                log_welcome(conf.loglevel_arg);
        }
@@@ -1043,22 -1043,48 +1043,48 @@@ static int use_rsync_locally(char *logn
  static int rename_resume_snap(int64_t creation_time)
  {
        struct snapshot_list sl = {.num_snapshots = 0};
-       struct snapshot *s;
+       struct snapshot *s = NULL;
        char *new_name = incomplete_name(creation_time);
        int ret;
+       const char *why;
  
        ret = 0;
        if (conf.no_resume_given)
                goto out;
        dss_get_snapshot_list(&sl);
+       /*
+        * Snapshot recycling: We first look at the newest snapshot. If this
+        * snapshot happens to be incomplete, the last rsync process was
+        * aborted and we reuse this one. Otherwise we look at snapshots which
+        * could be removed (outdated and redundant snapshots) as candidates
+        * for recycling. If no outdated/redundant snapshot exists, we check if
+        * there is an orphaned snapshot, which likely is useless anyway.
+        *
+        * Only if no existing snapshot is suitable for recycling, we bite the
+        * bullet and create a new one.
+        */
        s = get_newest_snapshot(&sl);
-       if (!s)
+       if (!s) /* no snapshots at all */
                goto out;
-       if ((s->flags & SS_COMPLETE) != 0) /* complete */
+       /* re-use last snapshot if it is incomplete */
+       why = "aborted";
+       if ((s->flags & SS_COMPLETE) == 0)
                goto out;
-       DSS_INFO_LOG("resuming: reusing %s as destination dir\n", s->name);
-       ret = dss_rename(s->name, new_name);
+       why = "outdated";
+       s = find_outdated_snapshot(&sl);
+       if (s)
+               goto out;
+       why = "redundant";
+       s = find_redundant_snapshot(&sl);
+       if (s)
+               goto out;
+       why = "orphaned";
+       s = find_orphaned_snapshot(&sl);
  out:
+       if (s) {
+               DSS_INFO_LOG("reusing %s snapshot %s\n", why, s->name);
+               ret = dss_rename(s->name, new_name);
+       }
        if (ret >= 0)
                DSS_NOTICE_LOG("creating new snapshot %s\n", new_name);
        free(new_name);