libostree: Add initial GRUB2 supportwip/grub2

In this approach, we drop a /etc/grub.d/15_ostree file which is a
hybrid of shell/C that picks up bits from the GRUB2 library (e.g. the
block device script generation), and then calls into libostree's
GRUB2 code which knows about the BLS entries.

This is admittedly ugly.  There exists another approach for GRUB2 to
learn the BLS specification.  However, the spec has a few issues:

https://www.redhat.com/archives/anaconda-devel-list/2014-July/msg00002.html

This approach also gives a bit more control to the admin via the
naming of the 15_ostree symlink; they can easily disable it:

Or reorder the ostree entries ahead of 10_linux:

Also, this approach doesn't require patches for grub2, which is an
issue with the pressure to backport (rpm-)OSTree to EL7.

1 files changed, 84 insertions, 0 deletions

diff --git a/src/ostree/ot-admin-instutil-builtin-grub2-generate.c b/src/ostree/ot-admin-instutil-builtin-grub2-generate.c
new file mode 100644
index 00000000..0b00cf97
--- /dev/null
+++ b/src/ostree/ot-admin-instutil-builtin-grub2-generate.c
@@ -0,0 +1,84 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014 Colin Walters <walters@verbum.org>
+ *
+ * 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 <string.h>
+#include <glib-unix.h>
+
+#include "ot-admin-instutil-builtins.h"
+#include "ostree-cmdprivate.h"
+
+#include "otutil.h"
+
+static GOptionEntry options[] = {
+  { NULL }
+};
+
+gboolean
+ot_admin_instutil_builtin_grub2_generate (int argc, char **argv, OstreeSysroot *sysroot, GCancellable *cancellable, GError **error)
+{
+  gboolean ret = FALSE;
+  guint bootversion;
+  gs_unref_object GFile *subpath = NULL;
+  gs_unref_object OstreeSePolicy *sepolicy = NULL;
+  gs_unref_ptrarray GPtrArray *deployments = NULL;
+  GOptionContext *context = NULL;
+  gs_unref_object GFile *deployment_path = NULL;
+
+  context = g_option_context_new ("BOOTVERSION - generate GRUB2 configuration from given BLS entries");
+
+  g_option_context_add_main_entries (context, options, NULL);
+
+  if (!g_option_context_parse (context, &argc, &argv, error))
+    goto out;
+
+  if (argc >= 2)
+    {
+      bootversion = (guint) g_ascii_strtoull (argv[1], NULL, 10);
+      if (!(bootversion == 0 || bootversion == 1))
+        {
+          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                       "Invalid bootversion: %u", bootversion);
+      goto out;
+        }
+    }
+  else 
+    {
+      const char *bootversion_env = g_getenv ("_OSTREE_GRUB2_BOOTVERSION");
+      if (bootversion_env)
+        bootversion = g_ascii_strtoull (bootversion_env, NULL, 10);
+      else
+        bootversion = ostree_sysroot_get_bootversion (sysroot);
+      g_assert (bootversion == 0 || bootversion == 1);
+    }
+
+  if (!ostree_sysroot_load (sysroot, cancellable, error))
+    goto out;
+
+  if (!ostree_cmd__private__()->ostree_generate_grub2_config (sysroot, bootversion, 1, cancellable, error))
+    goto out;
+
+  ret = TRUE;
+ out:
+  if (context)
+    g_option_context_free (context);
+  return ret;
+}