core: Use openat() for reading bare file objects too

...unless we want xattrs, in which case we have to fallback to path
lookup due to lack of llistxattrat().

This looks nicer in strace.

src/libostree/ostree-repo-private.h

@@ -66,10 +66,6 @@ _ostree_repo_ensure_loose_objdir_at (int             dfd,
                                      GCancellable   *cancellable,
                                      GError        **error);
 
-GFile *
-_ostree_repo_get_file_object_path (OstreeRepo   *self,
-                                   const char   *checksum);
-
 gboolean
 _ostree_repo_find_object (OstreeRepo           *self,
                           OstreeObjectType      objtype,

src/libostree/ostree-repo.c

@@ -576,14 +576,6 @@ ostree_repo_get_parent (OstreeRepo  *self)
   return self->parent_repo;
 }
 
-GFile *
-_ostree_repo_get_file_object_path (OstreeRepo   *self,
-                                   const char   *checksum)
-{
-  return _ostree_repo_get_object_path (self, checksum, OSTREE_OBJECT_TYPE_FILE);
-}
-
-
 static gboolean
 append_object_dirs_from (OstreeRepo          *self,
                          GFile               *dir,
@@ -885,6 +877,76 @@ load_metadata_internal (OstreeRepo       *self,
   return ret;
 }
 
+static gboolean
+query_info_for_bare_content_object (OstreeRepo      *self,
+                                    const char      *loose_path_buf,
+                                    GFileInfo      **out_info,
+                                    GCancellable    *cancellable,
+                                    GError         **error)
+{
+  gboolean ret = FALSE;
+  struct stat stbuf;
+  int res;
+  gs_unref_object GFileInfo *ret_info = NULL;
+
+  do
+    res = fstatat (self->objects_dir_fd, loose_path_buf, &stbuf, AT_SYMLINK_NOFOLLOW);
+  while (G_UNLIKELY (res == -1 && errno == EINTR));
+  if (res == -1)
+    {
+      if (errno == ENOENT)
+        {
+          *out_info = NULL;
+          ret = TRUE;
+          goto out;
+        }
+      ot_util_set_error_from_errno (error, errno);
+      goto out;
+    }
+
+  ret_info = g_file_info_new ();
+
+  if (S_ISREG (stbuf.st_mode))
+    {
+      g_file_info_set_file_type (ret_info, G_FILE_TYPE_REGULAR);
+      g_file_info_set_size (ret_info, stbuf.st_size);
+    }
+  else if (S_ISLNK (stbuf.st_mode))
+    {
+      char targetbuf[PATH_MAX+1];
+      ssize_t len;
+
+      g_file_info_set_file_type (ret_info, G_FILE_TYPE_SYMBOLIC_LINK);
+      
+      do
+        len = readlinkat (self->objects_dir_fd, loose_path_buf, targetbuf, sizeof (targetbuf) - 1);
+      while (G_UNLIKELY (len == -1 && errno == EINTR));
+      if (len == -1)
+        {
+          ot_util_set_error_from_errno (error, errno);
+          goto out;
+        }
+      targetbuf[len] = '\0';
+      g_file_info_set_symlink_target (ret_info, targetbuf);
+    }
+  else
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Not a regular file or symlink: %s", loose_path_buf);
+      goto out;
+    }
+
+  g_file_info_set_attribute_boolean (ret_info, "standard::is-symlink", S_ISLNK (stbuf.st_mode));
+  g_file_info_set_attribute_uint32 (ret_info, "unix::uid", stbuf.st_uid);
+  g_file_info_set_attribute_uint32 (ret_info, "unix::gid", stbuf.st_gid);
+  g_file_info_set_attribute_uint32 (ret_info, "unix::mode", stbuf.st_mode);
+
+  ret = TRUE;
+  gs_transfer_out_value (out_info, &ret_info);
+ out:
+  return ret;
+}
+
 /**
  * ostree_repo_load_file:
  * @self: Repo
@@ -949,33 +1011,34 @@ ostree_repo_load_file (OstreeRepo         *self,
     }
   else
     {
-      gs_unref_object GFile *loose_path = NULL;
+      char loose_path_buf[_OSTREE_LOOSE_PATH_MAX];
 
-      loose_path = _ostree_repo_get_object_path (self, checksum, OSTREE_OBJECT_TYPE_FILE);
+      _ostree_loose_path (loose_path_buf, checksum, OSTREE_OBJECT_TYPE_FILE, self->mode);
 
-      if (!ot_gfile_query_info_allow_noent (loose_path, OSTREE_GIO_FAST_QUERYINFO,
+      if (!query_info_for_bare_content_object (self, loose_path_buf,
-                                            G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
+                                               &ret_file_info,
-                                            &ret_file_info,
+                                               cancellable, error))
-                                            cancellable, error))
         goto out;
 
       if (ret_file_info)
         {
           if (out_xattrs)
             {
-              if (!ostree_get_xattrs_for_file (loose_path, &ret_xattrs,
+              gs_unref_object GFile *full_path =
+                    _ostree_repo_get_object_path (self, checksum, OSTREE_OBJECT_TYPE_FILE);
+
+              if (!ostree_get_xattrs_for_file (full_path, &ret_xattrs,
                                                cancellable, error))
                 goto out;
             }
 
           if (out_input && g_file_info_get_file_type (ret_file_info) == G_FILE_TYPE_REGULAR)
             {
-              ret_input = (GInputStream*) gs_file_read_noatime (loose_path, cancellable, error);
+              int fd = -1;
-              if (!ret_input)
+              if (!gs_file_openat_noatime (self->objects_dir_fd, loose_path_buf, &fd,
-                {
+                                           cancellable, error))
-                  g_prefix_error (error, "Error opening loose file object %s: ", gs_file_get_path_cached (loose_path));
+                goto out;
-                  goto out;
+              ret_input = g_unix_input_stream_new (fd, TRUE);
-                }
             }
           
           found = TRUE;