scripting: Add script (backportable) to undo a GUID index

This script allows the DB to be read, and re-indexed, by an earlier Samba version,
most likely 4.7 with some backported patches.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Sat Sep 23 09:16:31 CEST 2017 on sn-devel-144

source4/scripting/bin/sambaundoguididx

@@ -0,0 +1,84 @@
+#!/usr/bin/env python
+import optparse
+import sys
+
+# Find right directory when running from source tree
+sys.path.insert(0, "bin/python")
+
+
+import samba
+import ldb
+import urllib
+import os
+from samba import getopt as options
+from samba.samdb import SamDB
+from samba.dbchecker import dbcheck
+from samba.credentials import Credentials
+parser = optparse.OptionParser("sambaundoguididx")
+sambaopts = options.SambaOptions(parser)
+parser.add_option_group(options.VersionOptions(parser))
+parser.add_option("-H", "--URL", help="LDB URL for database",
+                  type=str, metavar="URL", dest="H")
+opts, args = parser.parse_args()
+
+if len(args) != 0:
+    parser.print_usage()
+    sys.exit(1)
+
+lp_ctx = sambaopts.get_loadparm()
+lp_ctx.set("dsdb:guid index", "false")
+
+if opts.H is None:
+    url = lp_ctx.samdb_url()
+else:
+    url = opts.H
+
+samdb = ldb.Ldb(url=url, options=["modules:"])
+
+partitions = samdb.search(base="@PARTITION",
+			  scope=ldb.SCOPE_BASE,
+                          attrs=["partition"])
+
+modmsg = ldb.Message()
+modmsg.dn = ldb.Dn(samdb, '@INDEXLIST')
+modmsg.add(ldb.MessageElement(
+    elements=[],
+    flags=ldb.FLAG_MOD_REPLACE,
+    name='@IDXGUID'))
+modmsg.add(ldb.MessageElement(
+    elements=[],
+    flags=ldb.FLAG_MOD_REPLACE,
+    name='@IDX_DN_GUID'))
+
+samdb.transaction_start()
+samdb.modify(modmsg)
+
+privatedir = os.path.dirname(url)
+
+dbs = []
+for part in partitions[0]['partition']:
+    file_quoted = part.split(":")[1]
+    tdbname = urllib.unquote(file_quoted)
+    tdbpath = os.path.join(privatedir, tdbname)
+
+    db = ldb.Ldb(url=tdbpath, options=["modules:"])
+    db.transaction_start()
+    db.modify(modmsg)
+    dbs.append(db)
+
+for db in dbs:
+    db.transaction_commit()
+
+samdb.transaction_commit()
+
+print "Re-opening with the full DB stack"
+samdb = SamDB(url=url,
+                          lp=lp_ctx)
+print "Re-triggering another re-index"
+chk = dbcheck(samdb)
+
+chk.reindex_database()
+
+print "Your database has been downgraded to DN-based index values."
+
+print "NOTE: Any use of a Samba 4.8 tool including ldbsearch will auto-upgrade back to GUID index mode"