WIP: Add a zipl bootloader backend

zipl is a bit special in that it parses the BLS config files
directly *but* we need to run the command to update the "boot block".

Hence, we're not generating a separate config file like the other
backends.  Instead, extend the bootloader interface with a `post_bls_sync`
method that is run in the same place we swap the `boot/loader` symlink.

We write a "stamp file" in `/boot` that says we need to run this command.
This opens the door to making things eventually-consistent/reconcilable
by later adding a systemd unit to run `zipl` if we're interrupted via
a systemd unit - I think we should eventually take this approach
everywhere rather than requiring `/boot/loader` to be a symlink.

Makefile-libostree.am

@@ -117,6 +117,8 @@ libostree_1_la_SOURCES = \
 	src/libostree/ostree-bootloader.c \
 	src/libostree/ostree-bootloader-grub2.h \
 	src/libostree/ostree-bootloader-grub2.c \
+	src/libostree/ostree-bootloader-zipl.h \
+	src/libostree/ostree-bootloader-zipl.c \
 	src/libostree/ostree-bootloader-syslinux.h \
 	src/libostree/ostree-bootloader-syslinux.c \
 	src/libostree/ostree-bootloader-uboot.h \

src/libostree/ostree-bootloader-zipl.c

@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2019 Colin Walters <[email protected]>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2 of the licence or (at
+ * your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include "ostree-sysroot-private.h"
+#include "ostree-bootloader-zipl.h"
+#include "otutil.h"
+
+#include <string.h>
+
+/* This is specific to zipl today, but in the future we could also
+ * use it for the grub2-mkconfig case.
+ */
+static const char zipl_requires_execute_path[] = "boot/ostree-bootloader-update.stamp";
+
+struct _OstreeBootloaderZipl
+{
+  GObject       parent_instance;
+
+  OstreeSysroot  *sysroot;
+};
+
+typedef GObjectClass OstreeBootloaderZiplClass;
+
+static void _ostree_bootloader_zipl_bootloader_iface_init (OstreeBootloaderInterface *iface);
+G_DEFINE_TYPE_WITH_CODE (OstreeBootloaderZipl, _ostree_bootloader_zipl, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (OSTREE_TYPE_BOOTLOADER, _ostree_bootloader_zipl_bootloader_iface_init));
+
+static gboolean
+_ostree_bootloader_zipl_query (OstreeBootloader *bootloader,
+                                   gboolean         *out_is_active,
+                                   GCancellable     *cancellable,
+                                   GError          **error)
+{
+  /* We don't auto-detect this one; should be explicitly chosen right now.
+   * see also https://github.com/coreos/coreos-assembler/pull/849
+   */
+  *out_is_active = FALSE;
+  return TRUE;
+}
+
+static const char *
+_ostree_bootloader_zipl_get_name (OstreeBootloader *bootloader)
+{
+  return "zipl";
+}
+
+static gboolean
+_ostree_bootloader_zipl_write_config (OstreeBootloader  *bootloader,
+                                          int                bootversion,
+                                          GPtrArray         *new_deployments,
+                                          GCancellable      *cancellable,
+                                          GError           **error)
+{
+  OstreeBootloaderZipl *self = OSTREE_BOOTLOADER_ZIPL (bootloader);
+
+  /* Write our stamp file */
+  if (!glnx_file_replace_contents_at (self->sysroot->sysroot_fd, zipl_requires_execute_path,
+                                      (guint8*)"", 0, GLNX_FILE_REPLACE_NODATASYNC,
+                                      cancellable, error))
+    return FALSE;
+
+  return TRUE;
+}
+
+static gboolean
+_ostree_bootloader_zipl_post_bls_sync (OstreeBootloader  *bootloader,
+                                       GCancellable  *cancellable,
+                                       GError       **error)
+{
+  OstreeBootloaderZipl *self = OSTREE_BOOTLOADER_ZIPL (bootloader);
+
+  /* Note that unlike the grub2-mkconfig backend, we make no attempt to
+   * chroot().
+   */
+  g_assert (self->sysroot->booted_deployment);
+
+  const char *const zipl_argv[] = {"zipl", NULL};
+  int estatus;
+  if (!g_spawn_sync (NULL, (char**)zipl_argv, NULL, G_SPAWN_SEARCH_PATH,
+                     NULL, NULL, NULL, NULL, &estatus, error))
+    return FALSE;
+  if (!g_spawn_check_exit_status (estatus, error))
+    return FALSE;
+  if (!glnx_unlinkat (self->sysroot->sysroot_fd, zipl_requires_execute_path, 0, error))
+    return FALSE;
+  return TRUE;
+}
+
+static void
+_ostree_bootloader_zipl_finalize (GObject *object)
+{
+  OstreeBootloaderZipl *self = OSTREE_BOOTLOADER_ZIPL (object);
+
+  g_clear_object (&self->sysroot);
+
+  G_OBJECT_CLASS (_ostree_bootloader_zipl_parent_class)->finalize (object);
+}
+
+void
+_ostree_bootloader_zipl_init (OstreeBootloaderZipl *self)
+{
+}
+
+static void
+_ostree_bootloader_zipl_bootloader_iface_init (OstreeBootloaderInterface *iface)
+{
+  iface->query = _ostree_bootloader_zipl_query;
+  iface->get_name = _ostree_bootloader_zipl_get_name;
+  iface->write_config = _ostree_bootloader_zipl_write_config;
+  iface->post_bls_sync = _ostree_bootloader_zipl_post_bls_sync;
+}
+
+void
+_ostree_bootloader_zipl_class_init (OstreeBootloaderZiplClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->finalize = _ostree_bootloader_zipl_finalize;
+}
+
+OstreeBootloaderZipl *
+_ostree_bootloader_zipl_new (OstreeSysroot *sysroot)
+{
+  OstreeBootloaderZipl *self = g_object_new (OSTREE_TYPE_BOOTLOADER_ZIPL, NULL);
+  self->sysroot = g_object_ref (sysroot);
+  return self;
+}

src/libostree/ostree-bootloader-zipl.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2019 Colin Walters <[email protected]>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2 of the licence or (at
+ * your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#pragma once
+
+#include "ostree-bootloader.h"
+
+G_BEGIN_DECLS
+
+#define OSTREE_TYPE_BOOTLOADER_ZIPL (_ostree_bootloader_zipl_get_type ())
+#define OSTREE_BOOTLOADER_ZIPL(inst) (G_TYPE_CHECK_INSTANCE_CAST ((inst), OSTREE_TYPE_BOOTLOADER_ZIPL, OstreeBootloaderZipl))
+#define OSTREE_IS_BOOTLOADER_ZIPL(inst) (G_TYPE_CHECK_INSTANCE_TYPE ((inst), OSTREE_TYPE_BOOTLOADER_ZIPL))
+
+typedef struct _OstreeBootloaderZipl OstreeBootloaderZipl;
+
+GType _ostree_bootloader_zipl_get_type (void) G_GNUC_CONST;
+
+OstreeBootloaderZipl * _ostree_bootloader_zipl_new (OstreeSysroot *sysroot);
+
+G_END_DECLS

src/libostree/ostree-bootloader.c

@@ -65,6 +65,19 @@ _ostree_bootloader_write_config (OstreeBootloader  *self,
                                                            cancellable, error);
 }
 
+gboolean
+_ostree_bootloader_post_bls_sync (OstreeBootloader  *self,
+                                  GCancellable  *cancellable,
+                                  GError       **error)
+{
+  g_return_val_if_fail (OSTREE_IS_BOOTLOADER (self), FALSE);
+
+  if (OSTREE_BOOTLOADER_GET_IFACE (self)->post_bls_sync)
+    return OSTREE_BOOTLOADER_GET_IFACE (self)->post_bls_sync (self, cancellable, error);
+
+  return TRUE;
+}
+
 gboolean
 _ostree_bootloader_is_atomic (OstreeBootloader  *self)
 {

src/libostree/ostree-bootloader.h

@@ -47,6 +47,9 @@ struct _OstreeBootloaderInterface
                                                    GPtrArray     *new_deployments,
                                                    GCancellable  *cancellable,
                                                    GError       **error);
+  gboolean             (* post_bls_sync)          (OstreeBootloader  *self,
+                                                   GCancellable  *cancellable,
+                                                   GError       **error);
   gboolean             (* is_atomic)              (OstreeBootloader  *self);
 };
 G_DEFINE_AUTOPTR_CLEANUP_FUNC (OstreeBootloader, g_object_unref)
@@ -66,6 +69,10 @@ gboolean _ostree_bootloader_write_config (OstreeBootloader  *self,
                                           GCancellable  *cancellable,
                                           GError       **error);
 
+gboolean _ostree_bootloader_post_bls_sync (OstreeBootloader  *self,
+                                           GCancellable  *cancellable,
+                                           GError       **error);
+
 gboolean _ostree_bootloader_is_atomic (OstreeBootloader  *self);
 
 G_END_DECLS

src/libostree/ostree-sysroot-deploy.c

@@ -1830,6 +1830,7 @@ prepare_new_bootloader_link (OstreeSysroot  *sysroot,
 /* Update the /boot/loader symlink to point to /boot/loader.$new_bootversion */
 static gboolean
 swap_bootloader (OstreeSysroot  *sysroot,
+                 OstreeBootloader *bootloader,
                  int             current_bootversion,
                  int             new_bootversion,
                  GCancellable   *cancellable,
@@ -1863,6 +1864,15 @@ swap_bootloader (OstreeSysroot  *sysroot,
   if (fsync (boot_dfd) != 0)
     return glnx_throw_errno_prefix (error, "fsync(boot)");
 
+  /* TODO: In the future also execute this automatically via a systemd unit
+   * if we detect it's necessary.
+   **/
+  if (bootloader)
+    {
+      if (!_ostree_bootloader_post_bls_sync (bootloader, cancellable, error))
+        return FALSE;
+    }
+
   return TRUE;
 }
 
@@ -2129,7 +2139,7 @@ write_deployments_bootswap (OstreeSysroot     *self,
   if (!full_system_sync (self, out_syncstats, cancellable, error))
     return FALSE;
 
-  if (!swap_bootloader (self, self->bootversion, new_bootversion,
+  if (!swap_bootloader (self, bootloader, self->bootversion, new_bootversion,
                         cancellable, error))
     return FALSE;