Actually, this is better.  Ditch the 1st diff and consider
this one instead.

I will take more care with future efforts.

* Log the valid preauth methods
* Use NULL instead of '0' per calloc/malloc man page
* Log a not enough memory message if needed, since this
   function does not return krb5_error_code
* Set length to 0, not NULL, fixed gcc warning

--- ../../PRISTINE-DONT-MOD-krb5-1.8/src/kdc/kdc_preauth.c	2010-02-12 
15:28:39.000000000 -0500
+++ kdc/kdc_preauth.c	2010-04-23 12:36:15.000000000 -0400
@@ -562,6 +562,10 @@
      free(kdc_realm_names);
      n_preauth_systems = k;
      /* Add the end-of-list marker. */
+    for (i = 0; i < k; i++) {
+        krb5_klog_syslog (LOG_INFO, "preauth method %s valid",
+                         preauth_systems[i].name);
+    }
      preauth_systems[k].name = "[end]";
      preauth_systems[k].type = -1;
      return 0;
@@ -1006,8 +1010,11 @@
      hw_only = isflagset(client->attributes, KRB5_KDB_REQUIRES_HW_AUTH);
      /* Allocate two extra entries for the cookie and the terminator. */
      pa_data = calloc(n_preauth_systems + 2, sizeof(krb5_pa_data *));
-    if (pa_data == 0)
+    if (pa_data == NULL) {
+        krb5_klog_syslog (LOG_INFO,
+                          "Not enough memory in get_preauth_hint_list");
          return;
+    }
      pa = pa_data;
       for (ap = preauth_systems; ap->type != -1; ap++) {
@@ -1328,7 +1335,7 @@
      }
      key_modified = FALSE;
      null_item.contents = NULL;
-    null_item.length = NULL;
+    null_item.length = 0;
      send_pa = send_pa_list;
      *send_pa = 0;