Lock around more ulog operations

Always lock the ulog when accessing it.  We can currently get away
with some laxness on iprop slaves because they are mostly synchronous,
but hierarchical iprop will allow master and slave operations to take
place concurrently, requiring more strict locking.

Add new functions ulog_get_last and ulog_set_last, which access the
ulog header with locking, and use them in kdb5_util and kpropd.  Add
locking to ulog_replay and ulog_init_header.

ulog_lock and ulog_sync_header are no longer used outside of kdb_log.c
after these changes, so make them static functions and remove the
ulog_ prefix.  Add an unlock_ulog function for clarity.

2 files changed, 13 insertions, 9 deletions

diff --git a/src/slave/kpropd.c b/src/slave/kpropd.c
index afeb53fa3b..65fb3e84fc 100644
--- a/src/slave/kpropd.c
+++ b/src/slave/kpropd.c
@@ -147,7 +147,7 @@ static int db_args_size = 0;
 static void parse_args(char **argv);
 static void do_standalone(void);
 static void doit(int fd);
-static krb5_error_code do_iprop(kdb_log_context *log_ctx);
+static krb5_error_code do_iprop(void);
 static void kerberos_authenticate(krb5_context context, int fd,
                                   krb5_principal *clientp, krb5_enctype *etype,
                                   struct sockaddr_storage *my_sin);
@@ -321,7 +321,7 @@ main(int argc, char **argv)
         /* NOTREACHED */
         break;
     default:
-        retval = do_iprop(log_ctx);
+        retval = do_iprop();
         /* do_iprop() can return due to failures and runonce. */
         kill(fullprop_child, SIGHUP);
         wait(NULL);
@@ -606,7 +606,7 @@ full_resync(CLIENT *clnt)
  * Returns non-zero on failure due to errors.
  */
 krb5_error_code
-do_iprop(kdb_log_context *log_ctx)
+do_iprop()
 {
     kadm5_ret_t retval;
     krb5_principal iprop_svc_principal;
@@ -621,13 +621,10 @@ do_iprop(kdb_log_context *log_ctx)
     kdb_last_t mylast;
     kdb_fullresync_result_t *full_ret;
     kadm5_iprop_handle_t handle;
-    kdb_hlog_t *ulog;
 
     if (debug)
         fprintf(stderr, _("Incremental propagation enabled\n"));
 
-    ulog = log_ctx->ulog;
-
     pollin = params.iprop_poll_time;
     if (pollin == 0)
         pollin = 10;
@@ -771,8 +768,11 @@ reinit:
          * Get the most recent ulog entry sno + ts, which
          * we package in the request to the master KDC
          */
-        mylast.last_sno = ulog->kdb_last_sno;
-        mylast.last_time = ulog->kdb_last_time;
+        retval = ulog_get_last(kpropd_context, &mylast);
+        if (retval) {
+            com_err(progname, retval, _("reading update log header"));
+            goto done;
+        }
 
         /*
          * Loop continuously on an iprop_get_updates_1(),
diff --git a/src/slave/kproplog.c b/src/slave/kproplog.c
index b051279513..853aa0633f 100644
--- a/src/slave/kproplog.c
+++ b/src/slave/kproplog.c
@@ -480,7 +480,11 @@ main(int argc, char **argv)
     }
 
     if (reset) {
-        ulog_init_header(context);
+        if (ulog_init_header(context) != 0) {
+            fprintf(stderr, _("Couldn't reinitialize ulog file %s\n\n"),
+                    params.iprop_logfile);
+            exit(1);
+        }
         printf(_("Reinitialized the ulog.\n"));
         exit(0);
     }