sysprep: add IPA offline unenrollment (RHBZ#1789592)

This new operation unenrolls the guest from a IPA server offline, by
removing the configuration files and certificates.

Thanks to Christian Heimes and François Cami for the hints.

sysprep/Makefile.am

@@ -43,6 +43,7 @@ operations = \
 	flag_reconfiguration \
 	firewall_rules \
 	fs_uuids \
+	ipa_client \
 	kerberos_data \
 	lvm_uuids \
 	logfiles \

sysprep/sysprep_operation_ipa_client.ml

@@ -0,0 +1,66 @@
+(* virt-sysprep
+ * Copyright (C) 2020 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *)
+
+open Sysprep_operation
+open Common_gettext.Gettext
+
+module G = Guestfs
+
+let ipa_client_perform (g : Guestfs.guestfs) root side_effects =
+  let typ = g#inspect_get_type root in
+  if typ = "linux" then (
+    (* Simple paths with no side effects. *)
+    let paths = [ "/etc/ipa/ca.crt";
+                  "/etc/ipa/default.conf";
+                  "/var/lib/ipa-client/sysrestore/*";
+                  "/var/lib/ipa-client/pki/*" ] in
+    let paths = List.concat (List.map Array.to_list (List.map g#glob_expand paths)) in
+    List.iter (
+      fun filename ->
+        try g#rm filename with G.Error _ -> ()
+    ) paths;
+
+    (* Certificates in the system CA store. *)
+    let certs = [ "/etc/pki/ca-trust/source/anchors/ipa-ca.crt";
+                  "/usr/local/share/ca-certificates/ipa-ca.crt";
+                  "/etc/pki/ca-trust/source/ipa.p11-kit" ] in
+    List.iter (
+      fun filename ->
+        try
+          g#rm filename;
+          side_effects#update_system_ca_store ()
+        with
+          G.Error _ -> ()
+    ) certs
+  )
+
+let op = {
+  defaults with
+    name = "ipa-client";
+    enabled_by_default = true;
+    heading = s_"Remove the IPA files";
+    pod_description = Some (s_"\
+Remove all the files related to an IPA (Identity, Policy, Audit) system.
+This effectively unenrolls the guest from an IPA server without interacting
+with it.
+
+This operation does not run C<ipa-client>.");
+    perform_on_filesystems = Some ipa_client_perform;
+}
+
+let () = register_operation op