ostree checkout: Support --composefs to create a composefs image

src/ostree/ot-builtin-checkout.c

@@ -33,6 +33,7 @@ static gboolean opt_user_mode;
 static gboolean opt_allow_noent;
 static gboolean opt_disable_cache;
 static char *opt_subpath;
+static gboolean opt_composefs;
 static gboolean opt_union;
 static gboolean opt_union_add;
 static gboolean opt_union_identical;
@@ -88,6 +89,7 @@ static GOptionEntry options[] = {
   { "skip-list", 0, 0, G_OPTION_ARG_FILENAME, &opt_skiplist_file, "File containing list of files to skip", "FILE" },
   { "selinux-policy", 0, 0, G_OPTION_ARG_FILENAME, &opt_selinux_policy, "Set SELinux labels based on policy in root filesystem PATH (may be /); implies --force-copy", "PATH" },
   { "selinux-prefix", 0, 0, G_OPTION_ARG_STRING, &opt_selinux_prefix, "When setting SELinux labels, prefix all paths by PREFIX", "PREFIX" },
+  { "composefs", 0, 0, G_OPTION_ARG_NONE, &opt_composefs, "Check out into a composfs image", NULL },
   { NULL }
 };
 
@@ -114,19 +116,60 @@ checkout_filter (OstreeRepo         *self,
 }
 
 static gboolean
-process_one_checkout (OstreeRepo           *repo,
-                      const char           *resolved_commit,
-                      const char           *subpath,
-                      const char           *destination,
-                      GCancellable         *cancellable,
-                      GError              **error)
+process_one_checkout (OstreeRepo              *repo,
+                      const char              *resolved_commit,
+                      const char              *subpath,
+                      const char              *destination,
+                      OstreeComposefsTarget   *composefs_target,
+                      GCancellable            *cancellable,
+                      GError                 **error)
 {
+  if (opt_composefs)
+    {
+      OstreeRepoCheckoutComposefsOptions checkout_options = { 0 };
+      g_autoptr(OstreeComposefsTarget) default_target = NULL;
+
+      if (composefs_target == NULL)
+        composefs_target = default_target = ostree_composefs_target_new ();
+
+      if (opt_union && opt_union_add)
+        return glnx_throw (error, "Cannot specify both --union and --union-add");
+      if (opt_union && opt_union_identical)
+        return glnx_throw (error, "Cannot specify both --union and --union-identical");
+      if (opt_union_add && opt_union_identical)
+        return glnx_throw (error, "Cannot specify both --union-add and --union-identical");
+      if (opt_union)
+        checkout_options.overwrite_mode = OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES;
+      else if (opt_union_add)
+        checkout_options.overwrite_mode = OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES;
+      else if (opt_union_identical)
+        checkout_options.overwrite_mode = OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_IDENTICAL;
+
+      if (opt_whiteouts)
+        checkout_options.process_whiteouts = TRUE;
+      if (subpath)
+        checkout_options.subpath = subpath;
+
+      /* Todo: Apply options */
+
+      if (!ostree_repo_checkout_composefs (repo, &checkout_options, composefs_target,
+                                           resolved_commit, cancellable, error))
+        return FALSE;
+
+      if (default_target)
+        {
+          if (!ostree_composefs_target_write_at (default_target,
+                                                 AT_FDCWD, destination,
+                                                 cancellable, error))
+            return FALSE;
+        }
+    }
   /* This strange code structure is to preserve testing
    * coverage of both `ostree_repo_checkout_tree` and
    * `ostree_repo_checkout_at` until such time as we have a more
    * convenient infrastructure for testing C APIs with data.
    */
-  if (opt_disable_cache || opt_whiteouts || opt_require_hardlinks ||
+  else if (opt_disable_cache || opt_whiteouts || opt_require_hardlinks ||
       opt_union_add || opt_force_copy || opt_force_copy_zerosized ||
       opt_bareuseronly_dirs || opt_union_identical ||
       opt_skiplist_file || opt_selinux_policy || opt_selinux_prefix)
@@ -260,6 +303,10 @@ process_many_checkouts (OstreeRepo         *repo,
   g_autofree char *revision = NULL;
   g_autofree char *subpath = NULL;
   g_autofree char *resolved_commit = NULL;
+  g_autoptr(OstreeComposefsTarget) composefs = NULL;
+
+  if (opt_composefs)
+    composefs = ostree_composefs_target_new ();
 
   if (opt_from_stdin)
     {
@@ -300,7 +347,7 @@ process_many_checkouts (OstreeRepo         *repo,
         goto out;
 
       if (!process_one_checkout (repo, resolved_commit, subpath, target,
-                                 cancellable, error))
+                                 composefs, cancellable, error))
         {
           g_prefix_error (error, "Processing tree %s: ", resolved_commit);
           goto out;
@@ -314,6 +361,14 @@ process_many_checkouts (OstreeRepo         *repo,
       goto out;
     }
 
+  if (composefs)
+    {
+      if (!ostree_composefs_target_write_at (composefs,
+                                             AT_FDCWD, target,
+                                             cancellable, error))
+        goto out;
+    }
+
   ret = TRUE;
  out:
   return ret;
@@ -358,7 +413,7 @@ ostree_builtin_checkout (int argc, char **argv, OstreeCommandInvocation *invocat
         return FALSE;
 
       if (!process_one_checkout (repo, resolved_commit, opt_subpath,
-                                 destination,
+                                 destination, NULL,
                                  cancellable, error))
         return FALSE;
     }