krb5 commit [krb5-1.16]: Don't include all MEMORY ccaches in collection

https://github.com/krb5/krb5/commit/4fb4a9c23cc33939deab2855449019bcca1003ab
commit 4fb4a9c23cc33939deab2855449019bcca1003ab
Author: Greg Hudson <[email protected]>
Date:   Wed Aug 1 15:53:12 2018 -0400

    Don't include all MEMORY ccaches in collection
    
    In the MEMORY ccache implementation, only yield a cache in the
    per-type cursor if it is the context default cache, matching the
    behavior of FILE after commit 45360c9688ca963f75a2480f2cf818424fc3dc7b
    (ticket 6955).
    
    (cherry picked from commit 49bb627fed70c5258c151c5135ac3d95ed1ee55d)
    
    ticket: 8720
    version_fixed: 1.16.3

 src/lib/krb5/ccache/cc_memory.c |   23 +++++++++--------------
 src/lib/krb5/ccache/t_cccol.py  |    7 ++++---
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/src/lib/krb5/ccache/cc_memory.c b/src/lib/krb5/ccache/cc_memory.c
index 8cdaff7..cfd5c63 100644
--- a/src/lib/krb5/ccache/cc_memory.c
+++ b/src/lib/krb5/ccache/cc_memory.c
@@ -132,7 +132,7 @@ struct mcc_cursor {
 
 /* Iterator over memory caches.  */
 struct krb5_mcc_ptcursor_data {
-    struct krb5_mcc_list_node *cur;
+    krb5_boolean first;
 };
 
 k5_cc_mutex krb5int_mcc_mutex = K5_CC_MUTEX_PARTIAL_INITIALIZER;
@@ -693,9 +693,7 @@ krb5_mcc_ptcursor_new(
         return ENOMEM;
     }
     n->data = cdata;
-    k5_cc_mutex_lock(context, &krb5int_mcc_mutex);
-    cdata->cur = mcc_head;
-    k5_cc_mutex_unlock(context, &krb5int_mcc_mutex);
+    cdata->first = TRUE;
     *cursor = n;
     return 0;
 }
@@ -707,22 +705,19 @@ krb5_mcc_ptcursor_next(
     krb5_ccache *ccache)
 {
     struct krb5_mcc_ptcursor_data *cdata = NULL;
+    const char *defname;
 
     *ccache = NULL;
     cdata = cursor->data;
-    if (cdata->cur == NULL)
+    if (!cdata->first)
         return 0;
+    cdata->first = FALSE;
 
-    *ccache = malloc(sizeof(**ccache));
-    if (*ccache == NULL)
-        return ENOMEM;
+    defname = krb5_cc_default_name(context);
+    if (defname == NULL || strncmp(defname, "MEMORY:", 7) != 0)
+        return 0;
 
-    (*ccache)->ops = &krb5_mcc_ops;
-    (*ccache)->data = cdata->cur->cache;
-    k5_cc_mutex_lock(context, &krb5int_mcc_mutex);
-    cdata->cur = cdata->cur->next;
-    k5_cc_mutex_unlock(context, &krb5int_mcc_mutex);
-    return 0;
+    return krb5_cc_resolve(context, defname, ccache);
 }
 
 static krb5_error_code KRB5_CALLCONV
diff --git a/src/lib/krb5/ccache/t_cccol.py b/src/lib/krb5/ccache/t_cccol.py
index f7f1785..c6d5f51 100755
--- a/src/lib/krb5/ccache/t_cccol.py
+++ b/src/lib/krb5/ccache/t_cccol.py
@@ -97,10 +97,11 @@ if test_keyring:
 
 mfoo = 'MEMORY:foo'
 mbar = 'MEMORY:bar'
-cursor_test('filemem', [fccname, mfoo, mbar], [fccname, mfoo, mbar])
-cursor_test('dirmem', [dccname, mfoo], [duser, dalice, dbob, mfoo])
+cursor_test('filemem', [fccname, mfoo], [fccname])
+cursor_test('dirmem', [dccname, mfoo], [duser, dalice, dbob])
+cursor_test('mem', [mfoo, mbar], [mfoo])
 if test_keyring:
-    cursor_test('keyringmem', [krccname, mfoo], [kruser, kralice, krbob, mfoo])
+    cursor_test('keyringmem', [krccname, mfoo], [kruser, kralice, krbob])
 
 # Test krb5_cccol_have_content.
 realm.run(['./t_cccursor', dccname, 'CONTENT'])