From c5b4cbf34e21ac77124a2ca421c1fdd179329783 Mon Sep 17 00:00:00 2001
From: Andrew Bartlett <abartlet@samba.org>
Date: Fri, 16 Jun 2017 15:49:45 +1200
Subject: [PATCH] dsdb: Add test showing a search can't start while a
 transaction is already repared in a backend partition

Pair-programmed-with: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
---
 python/samba/tests/dsdb.py       | 54 ++++++++++++++++++++++++++++++++
 selftest/knownfail.d/ldb-locking |  1 +
 2 files changed, 55 insertions(+)
 create mode 100644 selftest/knownfail.d/ldb-locking

diff --git a/python/samba/tests/dsdb.py b/python/samba/tests/dsdb.py
index bafd040d865..f38393e71a0 100644
--- a/python/samba/tests/dsdb.py
+++ b/python/samba/tests/dsdb.py
@@ -201,3 +201,57 @@ class DsdbTests(TestCase):
         self.assertEqual(got_pid, pid)
         self.assertTrue(os.WIFEXITED(status))
         self.assertEqual(os.WEXITSTATUS(status), 0)
+
+
+    def test_full_db_lock(self):
+        basedn = self.samdb.get_default_basedn()
+        backend_filename = "%s.ldb" % basedn.get_casefold()
+        backend_subpath = os.path.join("sam.ldb.d",
+                                       backend_filename)
+        backend_path = self.lp.private_path(backend_subpath)
+        (r1, w1) = os.pipe()
+
+        pid = os.fork()
+        if pid == 0:
+            # In the child, close the main DB, re-open just one DB
+            del(self.samdb)
+            gc.collect()
+
+            backenddb = ldb.Ldb(backend_path)
+
+
+            backenddb.transaction_start()
+
+            backenddb.add({"dn":"@DSDB_LOCK_TEST"})
+            backenddb.delete("@DSDB_LOCK_TEST")
+
+            # Obtain a write lock
+            backenddb.transaction_prepare_commit()
+            os.write(w1, b"added")
+            time.sleep(2)
+
+            # Drop the write lock
+            backenddb.transaction_cancel()
+            os._exit(0)
+
+        self.assertEqual(os.read(r1, 5), b"added")
+
+        start = time.time()
+
+        # We need to hold this iterator open to hold the all-record lock.
+        res = self.samdb.search_iterator()
+
+        # This should take at least 2 seconds because the transaction
+        # has a write lock on one backend db open
+
+        end = time.time()
+        self.assertGreater(end - start, 1.9)
+
+        # Release the locks
+        for l in res:
+            pass
+
+        (got_pid, status) = os.waitpid(pid, 0)
+        self.assertEqual(got_pid, pid)
+        self.assertTrue(os.WIFEXITED(status))
+        self.assertEqual(os.WEXITSTATUS(status), 0)
diff --git a/selftest/knownfail.d/ldb-locking b/selftest/knownfail.d/ldb-locking
new file mode 100644
index 00000000000..5b569d26e86
--- /dev/null
+++ b/selftest/knownfail.d/ldb-locking
@@ -0,0 +1 @@
+samba.tests.dsdb.samba.tests.dsdb.DsdbTests.test_full_db_lock\(ad_dc_ntvfs:local\)