[ostree] deploy: Swap current symlink only after updating the kernel

[Colin Walters <walters src gnome org>]

commit 8c694622b1db25e04316b61df9f427a7a225884c
Author: Colin Walters <walters verbum org>
Date:   Fri Apr 26 18:15:51 2013 -0400

    deploy: Swap current symlink only after updating the kernel
    
    While this still isn't fully atomic (that depends on the bootloader),
    this better ensures that the deployed kernel is booted with the
    intended tree.  For example, if we get ENOSPC when writing out the
    kernel, we won't have swapped the symlink.

 src/ostree/ot-admin-builtin-deploy.c |  131 +++++++++++++++++++--------------
 1 files changed, 75 insertions(+), 56 deletions(-)
---
diff --git a/src/ostree/ot-admin-builtin-deploy.c b/src/ostree/ot-admin-builtin-deploy.c
index c2e3fe9..4569761 100644
--- a/src/ostree/ot-admin-builtin-deploy.c
+++ b/src/ostree/ot-admin-builtin-deploy.c
@@ -34,6 +34,15 @@ typedef struct {
   GFile *ostree_dir;
   char  *osname;
   GFile *osname_dir;
+
+  char        *current_deployment_ref;
+  char        *previous_deployment_ref;
+  char        *resolved_commit;
+  char        *resolved_previous_commit;
+  
+  char        *previous_deployment_revision;
+  GFile       *deploy_target_path;
+  GFile       *previous_deployment;
 } OtAdminDeploy;
 
 static gboolean opt_no_kernel;
@@ -379,23 +388,17 @@ static gboolean
 deploy_tree (OtAdminDeploy     *self,
              const char        *deploy_target,
              const char        *revision,
-             GFile            **out_deploy_dir,           
              GCancellable      *cancellable,
              GError           **error)
 {
   gboolean ret = FALSE;
-  gs_free char *current_deployment_ref = NULL;
-  gs_free char *previous_deployment_ref = NULL;
   ot_lfree char *deploy_target_fullname = NULL;
   ot_lfree char *deploy_target_fullname_tmp = NULL;
-  ot_lobj GFile *deploy_target_path = NULL;
   ot_lobj GFile *deploy_target_path_tmp = NULL;
   ot_lfree char *deploy_target_etc_name = NULL;
   ot_lobj GFile *deploy_target_etc_path = NULL;
   ot_lobj GFile *deploy_target_default_etc_path = NULL;
   ot_lobj GFile *deploy_parent = NULL;
-  ot_lobj GFile *previous_deployment = NULL;
-  ot_lfree char *previous_deployment_revision = NULL;
   ot_lobj GFile *previous_deployment_etc = NULL;
   ot_lobj GFile *previous_deployment_etc_default = NULL;
   ot_lobj OstreeRepoFile *root = NULL;
@@ -403,17 +406,12 @@ deploy_tree (OtAdminDeploy     *self,
   ot_lobj GFileInfo *existing_checkout_info = NULL;
   ot_lfree char *checkout_target_name = NULL;
   ot_lfree char *checkout_target_tmp_name = NULL;
-  ot_lfree char *resolved_commit = NULL;
-  gs_free char *resolved_previous_commit = NULL;
   GError *temp_error = NULL;
   gboolean skip_checkout;
 
   if (!revision)
     revision = deploy_target;
 
-  current_deployment_ref = g_strdup_printf ("deployment/%s/current", self->osname);
-  previous_deployment_ref = g_strdup_printf ("deployment/%s/previous", self->osname);
-
   if (!g_file_query_exists (self->osname_dir, cancellable))
     {
       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
@@ -422,12 +420,12 @@ deploy_tree (OtAdminDeploy     *self,
       goto out;
     }
 
-  if (!ostree_repo_resolve_rev (self->repo, revision, FALSE, &resolved_commit, error))
+  if (!ostree_repo_resolve_rev (self->repo, revision, FALSE, &self->resolved_commit, error))
     goto out;
-  if (!ostree_repo_resolve_rev (self->repo, revision, TRUE, &resolved_previous_commit, error))
+  if (!ostree_repo_resolve_rev (self->repo, revision, TRUE, &self->resolved_previous_commit, error))
     goto out;
 
-  root = (OstreeRepoFile*)ostree_repo_file_new_root (self->repo, resolved_commit);
+  root = (OstreeRepoFile*)ostree_repo_file_new_root (self->repo, self->resolved_commit);
   if (!ostree_repo_file_ensure_resolved (root, error))
     goto out;
 
@@ -437,31 +435,31 @@ deploy_tree (OtAdminDeploy     *self,
   if (!file_info)
     goto out;
 
-  deploy_target_fullname = g_strconcat (deploy_target, "-", resolved_commit, NULL);
-  deploy_target_path = g_file_resolve_relative_path (self->osname_dir, deploy_target_fullname);
+  deploy_target_fullname = g_strconcat (deploy_target, "-", self->resolved_commit, NULL);
+  self->deploy_target_path = g_file_resolve_relative_path (self->osname_dir, deploy_target_fullname);
 
   deploy_target_fullname_tmp = g_strconcat (deploy_target_fullname, ".tmp", NULL);
   deploy_target_path_tmp = g_file_resolve_relative_path (self->osname_dir, deploy_target_fullname_tmp);
 
-  deploy_parent = g_file_get_parent (deploy_target_path);
+  deploy_parent = g_file_get_parent (self->deploy_target_path);
   if (!gs_file_ensure_directory (deploy_parent, TRUE, cancellable, error))
     goto out;
 
-  deploy_target_etc_name = g_strconcat (deploy_target, "-", resolved_commit, "-etc", NULL);
+  deploy_target_etc_name = g_strconcat (deploy_target, "-", self->resolved_commit, "-etc", NULL);
   deploy_target_etc_path = g_file_resolve_relative_path (self->osname_dir, deploy_target_etc_name);
 
   /* Delete any previous temporary data */
   if (!gs_shutil_rm_rf (deploy_target_path_tmp, cancellable, error))
     goto out;
 
-  existing_checkout_info = g_file_query_info (deploy_target_path, OSTREE_GIO_FAST_QUERYINFO,
+  existing_checkout_info = g_file_query_info (self->deploy_target_path, OSTREE_GIO_FAST_QUERYINFO,
                                               G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
                                               cancellable, &temp_error);
   if (existing_checkout_info)
     {
       if (opt_force)
         {
-          if (!gs_shutil_rm_rf (deploy_target_path, cancellable, error))
+          if (!gs_shutil_rm_rf (self->deploy_target_path, cancellable, error))
             goto out;
           if (!gs_shutil_rm_rf (deploy_target_etc_path, cancellable, error))
             goto out;
@@ -482,27 +480,27 @@ deploy_tree (OtAdminDeploy     *self,
       goto out;
     }
 
-  if (!ot_admin_get_current_deployment (self->ostree_dir, self->osname, &previous_deployment,
+  if (!ot_admin_get_current_deployment (self->ostree_dir, self->osname, &self->previous_deployment,
                                         cancellable, error))
     goto out;
-  if (previous_deployment)
+  if (self->previous_deployment)
     {
       ot_lfree char *etc_name;
       ot_lobj GFile *parent;
 
-      etc_name = g_strconcat (gs_file_get_basename_cached (previous_deployment), "-etc", NULL);
-      parent = g_file_get_parent (previous_deployment);
+      etc_name = g_strconcat (gs_file_get_basename_cached (self->previous_deployment), "-etc", NULL);
+      parent = g_file_get_parent (self->previous_deployment);
 
       previous_deployment_etc = g_file_get_child (parent, etc_name);
 
       if (!g_file_query_exists (previous_deployment_etc, cancellable)
-          || g_file_equal (previous_deployment, deploy_target_path))
+          || g_file_equal (self->previous_deployment, self->deploy_target_path))
         g_clear_object (&previous_deployment_etc);
       else
-        previous_deployment_etc_default = g_file_get_child (previous_deployment, "etc");
+        previous_deployment_etc_default = g_file_get_child (self->previous_deployment, "etc");
 
-      if (!ostree_repo_resolve_rev (self->repo, current_deployment_ref, TRUE,
-                                    &previous_deployment_revision, error))
+      if (!ostree_repo_resolve_rev (self->repo, self->current_deployment_ref, TRUE,
+                                    &self->previous_deployment_revision, error))
         goto out;
     }
 
@@ -513,7 +511,7 @@ deploy_tree (OtAdminDeploy     *self,
       ot_lobj GFile *triggers_run_path = NULL;
 
       g_print ("ostadmin: Creating deployment %s\n",
-               gs_file_get_path_cached (deploy_target_path));
+               gs_file_get_path_cached (self->deploy_target_path));
 
       memset (&checkout_data, 0, sizeof (checkout_data));
       checkout_data.loop = g_main_loop_new (NULL, TRUE);
@@ -559,33 +557,12 @@ deploy_tree (OtAdminDeploy     *self,
       else
         g_print ("ostadmin: No previous deployment; therefore, no configuration changes to merge\n");
 
-      if (!gs_file_rename (deploy_target_path_tmp, deploy_target_path,
+      if (!gs_file_rename (deploy_target_path_tmp, self->deploy_target_path,
                            cancellable, error))
         goto out;
     }
 
-  /* Write out a ref so that any "ostree prune" on the raw repo
-   * doesn't GC the currently deployed tree.
-   */
-  if (!ostree_repo_write_ref (self->repo, NULL, current_deployment_ref,
-                              resolved_commit, error))
-    goto out;
-  /* Only overwrite previous if it's different from what we're deploying now.
-   */
-  if (resolved_previous_commit != NULL
-      && strcmp (resolved_previous_commit, resolved_commit) != 0)
-    {
-      if (!ostree_repo_write_ref (self->repo, NULL, previous_deployment_ref,
-                                  previous_deployment_revision, error))
-        goto out;
-    }
-
-  if (!update_current (self, previous_deployment, deploy_target_path,
-                       cancellable, error))
-    goto out;
-
   ret = TRUE;
-  ot_transfer_out_value (out_deploy_dir, &deploy_target_path);
  out:
   return ret;
 }
@@ -597,7 +574,6 @@ deploy_tree (OtAdminDeploy     *self,
  */
 static gboolean
 do_update_kernel (OtAdminDeploy     *self,
-                  GFile             *deploy_path,
                   GCancellable      *cancellable,
                   GError           **error)
 {
@@ -611,7 +587,7 @@ do_update_kernel (OtAdminDeploy     *self,
                         "--boot-dir", gs_file_get_path_cached (self->admin_opts->boot_dir),
                         "update-kernel",
                         self->osname,
-                        gs_file_get_path_cached (deploy_path), NULL);
+                        gs_file_get_path_cached (self->deploy_target_path), NULL);
   g_ptr_array_add (args, NULL);
 
   proc = gs_subprocess_new_simple_argv ((char**)args->pdata,
@@ -628,6 +604,38 @@ do_update_kernel (OtAdminDeploy     *self,
   return ret;
 }
 
+static gboolean
+complete_deployment (OtAdminDeploy     *self,
+                     GCancellable      *cancellable,
+                     GError           **error)
+{
+  gboolean ret = FALSE;
+
+  /* Write out a ref so that any "ostree prune" on the raw repo
+   * doesn't GC the currently deployed tree.
+   */
+  if (!ostree_repo_write_ref (self->repo, NULL, self->current_deployment_ref,
+                              self->resolved_commit, error))
+    goto out;
+  /* Only overwrite previous if it's different from what we're deploying now.
+   */
+  if (self->resolved_previous_commit != NULL
+      && strcmp (self->resolved_previous_commit, self->resolved_commit) != 0)
+    {
+      if (!ostree_repo_write_ref (self->repo, NULL, self->previous_deployment_ref,
+                                  self->previous_deployment_revision, error))
+        goto out;
+    }
+
+  if (!update_current (self, self->previous_deployment, self->deploy_target_path,
+                       cancellable, error))
+    goto out;
+
+  ret = TRUE;
+ out:
+  return ret;
+}
+
 gboolean
 ot_admin_builtin_deploy (int argc, char **argv, OtAdminBuiltinOpts *admin_opts, GError **error)
 {
@@ -675,20 +683,31 @@ ot_admin_builtin_deploy (int argc, char **argv, OtAdminBuiltinOpts *admin_opts,
 
   self->osname = g_strdup (osname);
   self->osname_dir = ot_gfile_get_child_build_path (self->ostree_dir, "deploy", osname, NULL);
-  if (!deploy_tree (self, deploy_target, revision, &deploy_path,
-                    cancellable, error))
+  self->current_deployment_ref = g_strdup_printf ("deployment/%s/current", self->osname);
+  self->previous_deployment_ref = g_strdup_printf ("deployment/%s/previous", self->osname);
+
+  if (!deploy_tree (self, deploy_target, revision, cancellable, error))
     goto out;
 
   if (!opt_no_kernel)
     {
-      if (!do_update_kernel (self, deploy_path, cancellable, error))
+      if (!do_update_kernel (self, cancellable, error))
         goto out;
     }
 
+  if (!complete_deployment (self, cancellable, error))
+    goto out;
+
   ret = TRUE;
  out:
   g_clear_object (&self->repo);
   g_free (self->osname);
+  g_free (self->current_deployment_ref);
+  g_free (self->previous_deployment_ref);
+  g_free (self->resolved_commit);
+  g_free (self->resolved_previous_commit);
+  g_free (self->previous_deployment_revision);
+  g_clear_object (&self->previous_deployment);
   g_clear_object (&self->ostree_dir);
   g_clear_object (&self->osname_dir);
   if (context)