diff --git a/libglnx/.gitignore b/libglnx/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..55b946e76272aee1d57c71f3b78c9a5f5d22d3d8
--- /dev/null
+++ b/libglnx/.gitignore
@@ -0,0 +1,16 @@
+# A path ostree writes to work around automake bug with
+# subdir-objects
+Makefile-libglnx.am.inc
+
+# Some standard bits
+.deps
+.libs
+.dirstamp
+*.typelib
+*.la
+*.lo
+*.o
+*.pyc
+*.stamp
+*~
+
diff --git a/libglnx/COPYING b/libglnx/COPYING
new file mode 100644
index 0000000000000000000000000000000000000000..4362b49151d7b34ef83b3067a8f9c9f877d72a0e
--- /dev/null
+++ b/libglnx/COPYING
@@ -0,0 +1,502 @@
+                  GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
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+That's all there is to it!
diff --git a/libglnx/Makefile-libglnx.am b/libglnx/Makefile-libglnx.am
new file mode 100644
index 0000000000000000000000000000000000000000..158063c7beee4b71100b5f85e4d2cbd43ffab4d7
--- /dev/null
+++ b/libglnx/Makefile-libglnx.am
@@ -0,0 +1,78 @@
+# Copyright (C) 2015 Colin Walters <walters@verbum.org>
+#
+# This library 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 License, 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.
+
+EXTRA_DIST += \
+	$(libglnx_srcpath)/README.md \
+	$(libglnx_srcpath)/COPYING \
+	$(libglnx_srcpath)/libglnx.m4 \
+	$(NULL)
+
+libglnx_la_SOURCES = \
+	$(libglnx_srcpath)/glnx-macros.h \
+	$(libglnx_srcpath)/glnx-backport-autocleanups.h \
+	$(libglnx_srcpath)/glnx-backport-autoptr.h \
+	$(libglnx_srcpath)/glnx-backports.h \
+	$(libglnx_srcpath)/glnx-backports.c \
+	$(libglnx_srcpath)/glnx-local-alloc.h \
+	$(libglnx_srcpath)/glnx-local-alloc.c \
+	$(libglnx_srcpath)/glnx-errors.h \
+	$(libglnx_srcpath)/glnx-errors.c \
+	$(libglnx_srcpath)/glnx-console.h \
+	$(libglnx_srcpath)/glnx-console.c \
+	$(libglnx_srcpath)/glnx-dirfd.h \
+	$(libglnx_srcpath)/glnx-dirfd.c \
+	$(libglnx_srcpath)/glnx-fdio.h \
+	$(libglnx_srcpath)/glnx-fdio.c \
+	$(libglnx_srcpath)/glnx-lockfile.h \
+	$(libglnx_srcpath)/glnx-lockfile.c \
+	$(libglnx_srcpath)/glnx-missing-syscall.h \
+	$(libglnx_srcpath)/glnx-missing.h \
+	$(libglnx_srcpath)/glnx-xattrs.h \
+	$(libglnx_srcpath)/glnx-xattrs.c \
+	$(libglnx_srcpath)/glnx-shutil.h \
+	$(libglnx_srcpath)/glnx-shutil.c \
+	$(libglnx_srcpath)/libglnx.h \
+	$(libglnx_srcpath)/tests/libglnx-testlib.h \
+	$(NULL)
+
+libglnx_la_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)
+libglnx_la_LDFLAGS = -avoid-version -Bsymbolic-functions -export-symbols-regex "^glnx_" -no-undefined -export-dynamic 
+libglnx_la_LIBADD = $(libglnx_libs)
+
+libglnx_tests = test-libglnx-xattrs test-libglnx-fdio test-libglnx-errors test-libglnx-macros test-libglnx-shutil
+TESTS += $(libglnx_tests)
+
+check_PROGRAMS += $(libglnx_tests)
+test_libglnx_xattrs_SOURCES = $(libglnx_srcpath)/tests/test-libglnx-xattrs.c
+test_libglnx_xattrs_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)
+test_libglnx_xattrs_LDADD = $(libglnx_libs) libglnx.la
+
+test_libglnx_fdio_SOURCES = $(libglnx_srcpath)/tests/test-libglnx-fdio.c
+test_libglnx_fdio_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)
+test_libglnx_fdio_LDADD = $(libglnx_libs) libglnx.la
+
+test_libglnx_errors_SOURCES = $(libglnx_srcpath)/tests/test-libglnx-errors.c
+test_libglnx_errors_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)
+test_libglnx_errors_LDADD = $(libglnx_libs) libglnx.la
+
+test_libglnx_macros_SOURCES = $(libglnx_srcpath)/tests/test-libglnx-macros.c
+test_libglnx_macros_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)
+test_libglnx_macros_LDADD = $(libglnx_libs) libglnx.la
+
+test_libglnx_shutil_SOURCES = $(libglnx_srcpath)/tests/test-libglnx-shutil.c
+test_libglnx_shutil_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)
+test_libglnx_shutil_LDADD = $(libglnx_libs) libglnx.la
diff --git a/libglnx/README.md b/libglnx/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..6589d29be3fdede809a965631a1581fedab8b2c9
--- /dev/null
+++ b/libglnx/README.md
@@ -0,0 +1,50 @@
+libglnx is the successor to libgsystem: https://git.gnome.org/browse/libgsystem
+
+It is for modules which depend on both GLib and Linux, intended to be
+used as a git submodule.
+
+Features:
+
+ - File APIs which use `openat()` like APIs, but also take a `GCancellable`
+   to support dynamic cancellation
+ - APIs also have a `GError` parameter
+ - High level "shutil", somewhat inspired by Python's
+ - A "console" API for tty output
+ - A backport of the GLib cleanup macros for projects which can't yet take
+   a dependency on 2.40.
+
+Why?
+----
+
+There are multiple projects which have a hard dependency on Linux and
+GLib, such as NetworkManager, ostree, flatpak, etc.  It makes sense
+for them to be able to share Linux-specific APIs.
+
+This module also contains some code taken from systemd, which has very
+high quality LGPLv2+ shared library code, but most of the internal
+shared library is private, and not namespaced.
+
+One could also compare this project to gnulib; the salient differences
+there are that at least some of this module is eventually destined for
+inclusion in GLib.
+
+Porting from libgsystem
+-----------------------
+
+For all of the filesystem access code, libglnx exposes only
+fd-relative API, not `GFile*`.  It does use `GCancellable` where
+applicable.
+
+For local allocation macros, you should start using the `g_auto`
+macros from GLib.  A backport is included in libglnx.  There are a few
+APIs not defined in GLib yet, such as `glnx_autofd`.
+
+`gs_transfer_out_value` is replaced by `g_steal_pointer`.
+
+Contributing
+------------
+
+Development happens in GNOME Gitlab: https://gitlab.gnome.org/GNOME/libglnx
+
+(If you're seeing this on the Github mirror, we used to do development
+ on Github but that was before GNOME deployed Gitlab.)
diff --git a/libglnx/glnx-backport-autocleanups.h b/libglnx/glnx-backport-autocleanups.h
new file mode 100644
index 0000000000000000000000000000000000000000..b5f3475d9010d86eff4034638ab9b164dd2ed6c4
--- /dev/null
+++ b/libglnx/glnx-backport-autocleanups.h
@@ -0,0 +1,127 @@
+/*
+ * Copyright © 2015 Canonical Limited
+ *
+ * This library 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Ryan Lortie <desrt@desrt.ca>
+ */
+
+#pragma once
+
+#include <glnx-backport-autoptr.h>
+
+#if !GLIB_CHECK_VERSION(2, 43, 4)
+
+static inline void
+g_autoptr_cleanup_generic_gfree (void *p)
+{ 
+  void **pp = (void**)p;
+  if (*pp)
+    g_free (*pp);
+}
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GAsyncQueue, g_async_queue_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GBookmarkFile, g_bookmark_file_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GBytes, g_bytes_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GChecksum, g_checksum_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GDateTime, g_date_time_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GDir, g_dir_close)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GError, g_error_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GHashTable, g_hash_table_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GHmac, g_hmac_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GIOChannel, g_io_channel_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GKeyFile, g_key_file_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GList, g_list_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GArray, g_array_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GPtrArray, g_ptr_array_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMainContext, g_main_context_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMainLoop, g_main_loop_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSource, g_source_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMappedFile, g_mapped_file_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMarkupParseContext, g_markup_parse_context_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(gchar, g_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GNode, g_node_destroy)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GOptionContext, g_option_context_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GOptionGroup, g_option_group_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GPatternSpec, g_pattern_spec_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GQueue, g_queue_free)
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GQueue, g_queue_clear)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GRand, g_rand_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GRegex, g_regex_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMatchInfo, g_match_info_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GScanner, g_scanner_destroy)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSequence, g_sequence_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSList, g_slist_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GStringChunk, g_string_chunk_free)
+G_DEFINE_AUTO_CLEANUP_FREE_FUNC(GStrv, g_strfreev, NULL)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GThread, g_thread_unref)
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GMutex, g_mutex_clear)
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GCond, g_cond_clear)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTimer, g_timer_destroy)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTimeZone, g_time_zone_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTree, g_tree_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GVariant, g_variant_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GVariantBuilder, g_variant_builder_unref)
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GVariantBuilder, g_variant_builder_clear)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GVariantIter, g_variant_iter_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GVariantDict, g_variant_dict_unref)
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GVariantDict, g_variant_dict_clear)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GVariantType, g_variant_type_free)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSubprocess, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSubprocessLauncher, g_object_unref)
+
+/* Add GObject-based types as needed. */
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GAsyncResult, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GCancellable, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GConverter, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GConverterOutputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GDataInputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFile, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFileEnumerator, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFileIOStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFileInfo, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFileInputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFileMonitor, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GFileOutputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GInputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMemoryInputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMemoryOutputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GMount, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GOutputStream, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSocket, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GSocketAddress, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTask, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTlsCertificate, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTlsDatabase, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GTlsInteraction, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GDBusConnection, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GDBusMessage, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GVolumeMonitor, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GZlibCompressor, g_object_unref)
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GZlibDecompressor, g_object_unref)
+
+#endif
+
+#if !GLIB_CHECK_VERSION(2, 45, 8)
+
+static inline void
+g_autoptr_cleanup_gstring_free (GString *string)
+{
+  if (string)
+    g_string_free (string, TRUE);
+}
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GString, g_autoptr_cleanup_gstring_free)
+
+#endif
diff --git a/libglnx/glnx-backport-autoptr.h b/libglnx/glnx-backport-autoptr.h
new file mode 100644
index 0000000000000000000000000000000000000000..b36919dcb52b6cb638107f93dd2e37c4257bc999
--- /dev/null
+++ b/libglnx/glnx-backport-autoptr.h
@@ -0,0 +1,133 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2015 Colin Walters <walters@verbum.org>
+ * 
+ * GLIB - Library of useful routines for C programming
+ * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ * This library 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 License, 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 <gio/gio.h>
+
+G_BEGIN_DECLS
+
+#if !GLIB_CHECK_VERSION(2, 43, 4)
+
+#define _GLIB_AUTOPTR_FUNC_NAME(TypeName) glib_autoptr_cleanup_##TypeName
+#define _GLIB_AUTOPTR_TYPENAME(TypeName)  TypeName##_autoptr
+#define _GLIB_AUTO_FUNC_NAME(TypeName)    glib_auto_cleanup_##TypeName
+#define _GLIB_CLEANUP(func)               __attribute__((cleanup(func)))
+#define _GLIB_DEFINE_AUTOPTR_CHAINUP(ModuleObjName, ParentName) \
+  typedef ModuleObjName *_GLIB_AUTOPTR_TYPENAME(ModuleObjName);                                          \
+  static inline void _GLIB_AUTOPTR_FUNC_NAME(ModuleObjName) (ModuleObjName **_ptr) {                     \
+    _GLIB_AUTOPTR_FUNC_NAME(ParentName) ((ParentName **) _ptr); }                                        \
+
+
+/* these macros are API */
+#define G_DEFINE_AUTOPTR_CLEANUP_FUNC(TypeName, func) \
+  typedef TypeName *_GLIB_AUTOPTR_TYPENAME(TypeName);                                                           \
+  G_GNUC_BEGIN_IGNORE_DEPRECATIONS                                                                              \
+  static inline void _GLIB_AUTOPTR_FUNC_NAME(TypeName) (TypeName **_ptr) { if (*_ptr) (func) (*_ptr); }         \
+  G_GNUC_END_IGNORE_DEPRECATIONS
+#define G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(TypeName, func) \
+  G_GNUC_BEGIN_IGNORE_DEPRECATIONS                                                                              \
+  static inline void _GLIB_AUTO_FUNC_NAME(TypeName) (TypeName *_ptr) { (func) (_ptr); }                         \
+  G_GNUC_END_IGNORE_DEPRECATIONS
+#define G_DEFINE_AUTO_CLEANUP_FREE_FUNC(TypeName, func, none) \
+  G_GNUC_BEGIN_IGNORE_DEPRECATIONS                                                                              \
+  static inline void _GLIB_AUTO_FUNC_NAME(TypeName) (TypeName *_ptr) { if (*_ptr != none) (func) (*_ptr); }     \
+  G_GNUC_END_IGNORE_DEPRECATIONS
+#define g_autoptr(TypeName) _GLIB_CLEANUP(_GLIB_AUTOPTR_FUNC_NAME(TypeName)) _GLIB_AUTOPTR_TYPENAME(TypeName)
+#define g_auto(TypeName) _GLIB_CLEANUP(_GLIB_AUTO_FUNC_NAME(TypeName)) TypeName
+#define g_autofree _GLIB_CLEANUP(g_autoptr_cleanup_generic_gfree)
+
+/**
+ * g_steal_pointer:
+ * @pp: a pointer to a pointer
+ *
+ * Sets @pp to %NULL, returning the value that was there before.
+ *
+ * Conceptually, this transfers the ownership of the pointer from the
+ * referenced variable to the "caller" of the macro (ie: "steals" the
+ * reference).
+ *
+ * The return value will be properly typed, according to the type of
+ * @pp.
+ *
+ * This can be very useful when combined with g_autoptr() to prevent the
+ * return value of a function from being automatically freed.  Consider
+ * the following example (which only works on GCC and clang):
+ *
+ * |[
+ * GObject *
+ * create_object (void)
+ * {
+ *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
+ *
+ *   if (early_error_case)
+ *     return NULL;
+ *
+ *   return g_steal_pointer (&obj);
+ * }
+ * ]|
+ *
+ * It can also be used in similar ways for 'out' parameters and is
+ * particularly useful for dealing with optional out parameters:
+ *
+ * |[
+ * gboolean
+ * get_object (GObject **obj_out)
+ * {
+ *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
+ *
+ *   if (early_error_case)
+ *     return FALSE;
+ *
+ *   if (obj_out)
+ *     *obj_out = g_steal_pointer (&obj);
+ *
+ *   return TRUE;
+ * }
+ * ]|
+ *
+ * In the above example, the object will be automatically freed in the
+ * early error case and also in the case that %NULL was given for
+ * @obj_out.
+ *
+ * Since: 2.44
+ */
+static inline gpointer
+(g_steal_pointer) (gpointer pp)
+{
+  gpointer *ptr = (gpointer *) pp;
+  gpointer ref;
+
+  ref = *ptr;
+  *ptr = NULL;
+
+  return ref;
+}
+
+/* type safety */
+#define g_steal_pointer(pp) \
+  (0 ? (*(pp)) : (g_steal_pointer) (pp))
+
+#endif /* !GLIB_CHECK_VERSION(2, 43, 3) */
+
+G_END_DECLS
diff --git a/libglnx/glnx-backports.c b/libglnx/glnx-backports.c
new file mode 100644
index 0000000000000000000000000000000000000000..c7bb600f413cdeb85da06a228893a11f60e032c2
--- /dev/null
+++ b/libglnx/glnx-backports.c
@@ -0,0 +1,61 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2015 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 "glnx-backports.h"
+
+#if !GLIB_CHECK_VERSION(2, 44, 0)
+gboolean
+glnx_strv_contains (const gchar * const *strv,
+                    const gchar         *str)
+{
+  g_return_val_if_fail (strv != NULL, FALSE);
+  g_return_val_if_fail (str != NULL, FALSE);
+
+  for (; *strv != NULL; strv++)
+    {
+      if (g_str_equal (str, *strv))
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
+gboolean
+glnx_set_object (GObject **object_ptr,
+                 GObject  *new_object)
+{
+  GObject *old_object = *object_ptr;
+
+  if (old_object == new_object)
+    return FALSE;
+
+  if (new_object != NULL)
+    g_object_ref (new_object);
+
+  *object_ptr = new_object;
+
+  if (old_object != NULL)
+    g_object_unref (old_object);
+
+  return TRUE;
+}
+#endif
diff --git a/libglnx/glnx-backports.h b/libglnx/glnx-backports.h
new file mode 100644
index 0000000000000000000000000000000000000000..cd853cca250af80f01e601c636f78eddc0f4df18
--- /dev/null
+++ b/libglnx/glnx-backports.h
@@ -0,0 +1,46 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2015 Colin Walters <walters@verbum.org>
+ * 
+ * GLIB - Library of useful routines for C programming
+ * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ * This library 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 License, 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 <gio/gio.h>
+
+G_BEGIN_DECLS
+
+#if !GLIB_CHECK_VERSION(2, 44, 0)
+
+#define g_strv_contains glnx_strv_contains
+gboolean              glnx_strv_contains  (const gchar * const *strv,
+                                           const gchar         *str);
+
+#define g_set_object(object_ptr, new_object) \
+ (/* Check types match. */ \
+  0 ? *(object_ptr) = (new_object), FALSE : \
+  glnx_set_object ((GObject **) (object_ptr), (GObject *) (new_object)) \
+ )
+gboolean              glnx_set_object  (GObject **object_ptr,
+                                        GObject  *new_object);
+
+#endif /* !GLIB_CHECK_VERSION(2, 44, 0) */
+
+G_END_DECLS
diff --git a/libglnx/glnx-console.c b/libglnx/glnx-console.c
new file mode 100644
index 0000000000000000000000000000000000000000..c2fe29db0584b1e0780a2d655af9d320737e6f3b
--- /dev/null
+++ b/libglnx/glnx-console.c
@@ -0,0 +1,359 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2013,2014,2015 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 "glnx-console.h"
+
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+
+/* For people with widescreen monitors and maximized terminals, it looks pretty
+ * bad to have an enormous progress bar. For much the same reason as web pages
+ * tend to have a maximum width;
+ * https://ux.stackexchange.com/questions/48982/suggest-good-max-width-for-fluid-width-design
+ */
+#define MAX_PROGRESSBAR_COLUMNS 20
+
+/* Max updates output per second.  On a tty there's no point to rendering
+ * extremely fast; and for a non-tty we're probably in a Jenkins job
+ * or whatever and having percentages spam multiple lines there is annoying.
+ */
+#define MAX_TTY_UPDATE_HZ (5)
+#define MAX_NONTTY_UPDATE_HZ (1)
+
+static gboolean locked;
+static guint64 last_update_ms; /* monotonic time in millis we last updated */
+
+gboolean
+glnx_stdout_is_tty (void)
+{
+  static gsize initialized = 0;
+  static gboolean stdout_is_tty_v;
+
+  if (g_once_init_enter (&initialized))
+    {
+      stdout_is_tty_v = isatty (1);
+      g_once_init_leave (&initialized, 1);
+    }
+
+  return stdout_is_tty_v;
+}
+
+static volatile guint cached_columns = 0;
+static volatile guint cached_lines = 0;
+
+static int
+fd_columns (int fd)
+{
+  struct winsize ws = {};
+
+  if (ioctl (fd, TIOCGWINSZ, &ws) < 0)
+    return -errno;
+
+  if (ws.ws_col <= 0)
+    return -EIO;
+
+  return ws.ws_col;
+}
+
+/**
+ * glnx_console_columns:
+ * 
+ * Returns: The number of columns for terminal output
+ */
+guint
+glnx_console_columns (void)
+{
+  if (G_UNLIKELY (cached_columns == 0))
+    {
+      int c;
+
+      c = fd_columns (STDOUT_FILENO);
+
+      if (c <= 0)
+        c = 80;
+
+      if (c > 256)
+        c = 256;
+
+      cached_columns = c;
+    }
+
+  return cached_columns;
+}
+
+static int
+fd_lines (int fd)
+{
+  struct winsize ws = {};
+
+  if (ioctl (fd, TIOCGWINSZ, &ws) < 0)
+    return -errno;
+
+  if (ws.ws_row <= 0)
+    return -EIO;
+
+  return ws.ws_row;
+}
+
+/**
+ * glnx_console_lines:
+ * 
+ * Returns: The number of lines for terminal output
+ */
+guint
+glnx_console_lines (void)
+{
+  if (G_UNLIKELY (cached_lines == 0))
+    {
+      int l;
+
+      l = fd_lines (STDOUT_FILENO);
+
+      if (l <= 0)
+        l = 24;
+
+      cached_lines = l;
+    }
+
+  return cached_lines;
+}
+
+static void
+on_sigwinch (int signum)
+{
+  cached_columns = 0;
+  cached_lines = 0;
+}
+
+void
+glnx_console_lock (GLnxConsoleRef *console)
+{
+  static gsize sigwinch_initialized = 0;
+
+  g_return_if_fail (!locked);
+  g_return_if_fail (!console->locked);
+
+  console->is_tty = glnx_stdout_is_tty ();
+
+  locked = console->locked = TRUE;
+
+  if (console->is_tty)
+    {
+      if (g_once_init_enter (&sigwinch_initialized))
+        {
+          signal (SIGWINCH, on_sigwinch);
+          g_once_init_leave (&sigwinch_initialized, 1);
+        }
+      
+      { static const char initbuf[] = { 0x1B, 0x37 };
+        (void) fwrite (initbuf, 1, sizeof (initbuf), stdout);
+      }
+    }
+}
+
+static void
+printpad (const char *padbuf,
+          guint       padbuf_len,
+          guint       n)
+{
+  const guint d = n / padbuf_len;
+  const guint r = n % padbuf_len;
+  guint i;
+
+  for (i = 0; i < d; i++)
+    fwrite (padbuf, 1, padbuf_len, stdout);
+  fwrite (padbuf, 1, r, stdout);
+}
+
+static void
+text_percent_internal (const char *text,
+                       int percentage)
+{
+  /* Check whether we're trying to render too fast; unless percentage is 100, in
+   * which case we assume this is the last call, so we always render it.
+   */
+  const guint64 current_ms = g_get_monotonic_time () / 1000;
+  if (percentage != 100)
+    {
+      const guint64 diff_ms = current_ms - last_update_ms;
+      if (glnx_stdout_is_tty ())
+        {
+          if (diff_ms < (1000/MAX_TTY_UPDATE_HZ))
+            return;
+        }
+      else
+        {
+          if (diff_ms < (1000/MAX_NONTTY_UPDATE_HZ))
+            return;
+        }
+    }
+  last_update_ms = current_ms;
+
+  static const char equals[] = "====================";
+  const guint n_equals = sizeof (equals) - 1;
+  static const char spaces[] = "                    ";
+  const guint n_spaces = sizeof (spaces) - 1;
+  const guint ncolumns = glnx_console_columns ();
+  const guint bar_min = 10;
+
+  if (text && !*text)
+    text = NULL;
+
+  const guint input_textlen = text ? strlen (text) : 0;
+
+  if (!glnx_stdout_is_tty ())
+    {
+      if (text)
+        fprintf (stdout, "%s", text);
+      if (percentage != -1)
+        {
+          if (text)
+            fputc (' ', stdout);
+          fprintf (stdout, "%u%%", percentage);
+        }
+      fputc ('\n', stdout);
+      fflush (stdout);
+      return;
+    }
+
+  if (ncolumns < bar_min)
+    return; /* TODO: spinner */
+
+  /* Restore cursor */
+  { const char beginbuf[2] = { 0x1B, 0x38 };
+    (void) fwrite (beginbuf, 1, sizeof (beginbuf), stdout);
+  }
+
+  if (percentage == -1)
+    {
+      if (text != NULL)
+        fwrite (text, 1, input_textlen, stdout);
+
+      /* Overwrite remaining space, if any */
+      if (ncolumns > input_textlen)
+        printpad (spaces, n_spaces, ncolumns - input_textlen);
+    }
+  else
+    {
+      const guint textlen = MIN (input_textlen, ncolumns - bar_min);
+      const guint barlen = MIN (MAX_PROGRESSBAR_COLUMNS, ncolumns - (textlen + 1));
+
+      if (textlen > 0)
+        {
+          fwrite (text, 1, textlen, stdout);
+          fputc (' ', stdout);
+        }
+
+      {
+        const guint nbraces = 2;
+        const guint textpercent_len = 5;
+        const guint bar_internal_len = barlen - nbraces - textpercent_len;
+        const guint eqlen = bar_internal_len * (percentage / 100.0);
+        const guint spacelen = bar_internal_len - eqlen;
+
+        fputc ('[', stdout);
+        printpad (equals, n_equals, eqlen);
+        printpad (spaces, n_spaces, spacelen);
+        fputc (']', stdout);
+        fprintf (stdout, " %3d%%", percentage);
+      }
+    }
+
+  fflush (stdout);
+}
+
+/**
+ * glnx_console_progress_text_percent:
+ * @text: Show this text before the progress bar
+ * @percentage: An integer in the range of 0 to 100
+ *
+ * On a tty, print to the console @text followed by an ASCII art
+ * progress bar whose percentage is @percentage.  If stdout is not a
+ * tty, a more basic line by line change will be printed.
+ *
+ * You must have called glnx_console_lock() before invoking this
+ * function.
+ *
+ */
+void
+glnx_console_progress_text_percent (const char *text,
+                                    guint percentage)
+{
+  g_return_if_fail (percentage <= 100);
+
+  text_percent_internal (text, percentage);
+}
+
+/**
+ * glnx_console_progress_n_items:
+ * @text: Show this text before the progress bar
+ * @current: An integer for how many items have been processed
+ * @total: An integer for how many items there are total
+ *
+ * On a tty, print to the console @text followed by [@current/@total],
+ * then an ASCII art progress bar, like glnx_console_progress_text_percent().
+ *
+ * You must have called glnx_console_lock() before invoking this
+ * function.
+ */
+void
+glnx_console_progress_n_items (const char     *text,
+                               guint           current,
+                               guint           total)
+{
+  g_return_if_fail (current <= total);
+  g_return_if_fail (total > 0);
+
+  g_autofree char *newtext = g_strdup_printf ("%s (%u/%u)", text, current, total);
+  /* Special case current == total to ensure we end at 100% */
+  int percentage = (current == total) ? 100 : (((double)current) / total * 100);
+  glnx_console_progress_text_percent (newtext, percentage);
+}
+
+void
+glnx_console_text (const char *text)
+{
+  text_percent_internal (text, -1);
+}
+
+/**
+ * glnx_console_unlock:
+ *
+ * Print a newline, and reset all cached console progress state.
+ *
+ * This function does nothing if stdout is not a tty.
+ */
+void
+glnx_console_unlock (GLnxConsoleRef *console)
+{
+  g_return_if_fail (locked);
+  g_return_if_fail (console->locked);
+
+  if (console->is_tty)
+    fputc ('\n', stdout);
+      
+  locked = console->locked = FALSE;
+}
diff --git a/libglnx/glnx-console.h b/libglnx/glnx-console.h
new file mode 100644
index 0000000000000000000000000000000000000000..d853a80c69121b4ad7e600d7f591f539b1b94c03
--- /dev/null
+++ b/libglnx/glnx-console.h
@@ -0,0 +1,61 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2013,2014,2015 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.
+ */
+
+#pragma once
+
+#include <glnx-backport-autocleanups.h>
+
+G_BEGIN_DECLS
+
+struct GLnxConsoleRef {
+  gboolean locked;
+  gboolean is_tty;
+};
+
+typedef struct GLnxConsoleRef GLnxConsoleRef;
+
+gboolean glnx_stdout_is_tty (void);
+
+void	 glnx_console_lock (GLnxConsoleRef *ref);
+
+void	 glnx_console_text (const char     *text);
+
+void	 glnx_console_progress_text_percent (const char     *text,
+                                           guint           percentage);
+
+void	 glnx_console_progress_n_items (const char     *text,
+                                      guint           current,
+                                      guint           total);
+
+void	 glnx_console_unlock (GLnxConsoleRef *ref);
+
+guint    glnx_console_lines (void);
+
+guint    glnx_console_columns (void);
+
+static inline void
+glnx_console_ref_cleanup (GLnxConsoleRef *p)
+{
+  if (p->locked)
+    glnx_console_unlock (p);
+}
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GLnxConsoleRef, glnx_console_ref_cleanup)
+
+G_END_DECLS
diff --git a/libglnx/glnx-dirfd.c b/libglnx/glnx-dirfd.c
new file mode 100644
index 0000000000000000000000000000000000000000..6d1e2d216f0f7bbadbdef778432572813898ba50
--- /dev/null
+++ b/libglnx/glnx-dirfd.c
@@ -0,0 +1,425 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-dirfd.h>
+#include <glnx-fdio.h>
+#include <glnx-errors.h>
+#include <glnx-local-alloc.h>
+#include <glnx-shutil.h>
+
+/**
+ * glnx_opendirat_with_errno:
+ * @dfd: File descriptor for origin directory
+ * @name: Pathname, relative to @dfd
+ * @follow: Whether or not to follow symbolic links
+ *
+ * Use openat() to open a directory, using a standard set of flags.
+ * This function sets errno.
+ */
+int
+glnx_opendirat_with_errno (int           dfd,
+                           const char   *path,
+                           gboolean      follow)
+{
+  int flags = O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOCTTY;
+  if (!follow)
+    flags |= O_NOFOLLOW;
+
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  return openat (dfd, path, flags);
+}
+
+/**
+ * glnx_opendirat:
+ * @dfd: File descriptor for origin directory
+ * @path: Pathname, relative to @dfd
+ * @follow: Whether or not to follow symbolic links
+ * @error: Error
+ *
+ * Use openat() to open a directory, using a standard set of flags.
+ */
+gboolean
+glnx_opendirat (int             dfd,
+                const char     *path,
+                gboolean        follow,
+                int            *out_fd,
+                GError        **error)
+{
+  int ret = glnx_opendirat_with_errno (dfd, path, follow);
+  if (ret == -1)
+    return glnx_throw_errno_prefix (error, "opendir(%s)", path);
+  *out_fd = ret;
+  return TRUE;
+}
+
+struct GLnxRealDirfdIterator
+{
+  gboolean initialized;
+  int fd;
+  DIR *d;
+};
+typedef struct GLnxRealDirfdIterator GLnxRealDirfdIterator;
+
+/**
+ * glnx_dirfd_iterator_init_at:
+ * @dfd: File descriptor, may be AT_FDCWD or -1
+ * @path: Path, may be relative to @dfd
+ * @follow: If %TRUE and the last component of @path is a symlink, follow it
+ * @out_dfd_iter: (out caller-allocates): A directory iterator, will be initialized
+ * @error: Error
+ *
+ * Initialize @out_dfd_iter from @dfd and @path.
+ */
+gboolean
+glnx_dirfd_iterator_init_at (int                     dfd,
+                             const char             *path,
+                             gboolean                follow,
+                             GLnxDirFdIterator      *out_dfd_iter,
+                             GError                **error)
+{
+  glnx_autofd int fd = -1;
+  if (!glnx_opendirat (dfd, path, follow, &fd, error))
+    return FALSE;
+
+  if (!glnx_dirfd_iterator_init_take_fd (&fd, out_dfd_iter, error))
+    return FALSE;
+
+  return TRUE;
+}
+
+/**
+ * glnx_dirfd_iterator_init_take_fd:
+ * @dfd: File descriptor - ownership is taken, and the value is set to -1
+ * @dfd_iter: A directory iterator
+ * @error: Error
+ *
+ * Steal ownership of @dfd, using it to initialize @dfd_iter for
+ * iteration.
+ */
+gboolean
+glnx_dirfd_iterator_init_take_fd (int               *dfd,
+                                  GLnxDirFdIterator *dfd_iter,
+                                  GError           **error)
+{
+  GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter;
+  DIR *d = fdopendir (*dfd);
+  if (!d)
+    return glnx_throw_errno_prefix (error, "fdopendir");
+
+  real_dfd_iter->fd = glnx_steal_fd (dfd);
+  real_dfd_iter->d = d;
+  real_dfd_iter->initialized = TRUE;
+
+  return TRUE;
+}
+
+/**
+ * glnx_dirfd_iterator_next_dent:
+ * @dfd_iter: A directory iterator
+ * @out_dent: (out) (transfer none): Pointer to dirent; do not free
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Read the next value from @dfd_iter, causing @out_dent to be
+ * updated.  If end of stream is reached, @out_dent will be set
+ * to %NULL, and %TRUE will be returned.
+ */
+gboolean
+glnx_dirfd_iterator_next_dent (GLnxDirFdIterator  *dfd_iter,
+                               struct dirent     **out_dent,
+                               GCancellable       *cancellable,
+                               GError             **error)
+{
+  GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter;
+
+  g_return_val_if_fail (out_dent, FALSE);
+  g_return_val_if_fail (dfd_iter->initialized, FALSE);
+
+  if (g_cancellable_set_error_if_cancelled (cancellable, error))
+    return FALSE;
+
+  do
+    {
+      errno = 0;
+      *out_dent = readdir (real_dfd_iter->d);
+      if (*out_dent == NULL && errno != 0)
+        return glnx_throw_errno_prefix (error, "readdir");
+    } while (*out_dent &&
+             (strcmp ((*out_dent)->d_name, ".") == 0 ||
+              strcmp ((*out_dent)->d_name, "..") == 0));
+
+  return TRUE;
+}
+
+/**
+ * glnx_dirfd_iterator_next_dent_ensure_dtype:
+ * @dfd_iter: A directory iterator
+ * @out_dent: (out) (transfer none): Pointer to dirent; do not free
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * A variant of @glnx_dirfd_iterator_next_dent, which will ensure the
+ * `dent->d_type` member is filled in by calling `fstatat`
+ * automatically if the underlying filesystem type sets `DT_UNKNOWN`.
+ */
+gboolean
+glnx_dirfd_iterator_next_dent_ensure_dtype (GLnxDirFdIterator  *dfd_iter,
+                                            struct dirent     **out_dent,
+                                            GCancellable       *cancellable,
+                                            GError            **error)
+{
+  g_return_val_if_fail (out_dent, FALSE);
+
+  if (!glnx_dirfd_iterator_next_dent (dfd_iter, out_dent, cancellable, error))
+    return FALSE;
+
+  struct dirent *ret_dent = *out_dent;
+  if (ret_dent)
+    {
+
+      if (ret_dent->d_type == DT_UNKNOWN)
+        {
+          struct stat stbuf;
+          if (!glnx_fstatat (dfd_iter->fd, ret_dent->d_name, &stbuf, AT_SYMLINK_NOFOLLOW, error))
+            return FALSE;
+          ret_dent->d_type = IFTODT (stbuf.st_mode);
+        }
+    }
+
+  return TRUE;
+}
+
+/**
+ * glnx_dirfd_iterator_clear:
+ * @dfd_iter: Iterator, will be de-initialized
+ *
+ * Unset @dfd_iter, freeing any resources.  If @dfd_iter is not
+ * initialized, do nothing.
+ */
+void
+glnx_dirfd_iterator_clear (GLnxDirFdIterator *dfd_iter)
+{
+  GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter;
+  /* fd is owned by dfd_iter */
+  if (!real_dfd_iter->initialized)
+    return;
+  (void) closedir (real_dfd_iter->d);
+  real_dfd_iter->initialized = FALSE;
+}
+
+/**
+ * glnx_fdrel_abspath:
+ * @dfd: Directory fd
+ * @path: Path
+ *
+ * Turn a fd-relative pair into something that can be used for legacy
+ * APIs expecting absolute paths.
+ *
+ * This is Linux specific, and only valid inside this process (unless
+ * you set up the child process to have the exact same fd number, but
+ * don't try that).
+ */
+char *
+glnx_fdrel_abspath (int         dfd,
+                    const char *path)
+{
+  dfd = glnx_dirfd_canonicalize (dfd);
+  if (dfd == AT_FDCWD)
+    return g_strdup (path);
+  return g_strdup_printf ("/proc/self/fd/%d/%s", dfd, path);
+}
+
+/**
+ * glnx_gen_temp_name:
+ * @tmpl: (type filename): template directory name, the last 6 characters will be replaced
+ *
+ * Replace the last 6 characters of @tmpl with random ASCII.  You must
+ * use this in combination with a mechanism to ensure race-free file
+ * creation such as `O_EXCL`.
+ */
+void
+glnx_gen_temp_name (gchar *tmpl)
+{
+  g_return_if_fail (tmpl != NULL);
+  const size_t len = strlen (tmpl);
+  g_return_if_fail (len >= 6);
+
+  static const char letters[] =
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
+  static const int NLETTERS = sizeof (letters) - 1;
+
+  char *XXXXXX = tmpl + (len - 6);
+  for (int i = 0; i < 6; i++)
+    XXXXXX[i] = letters[g_random_int_range(0, NLETTERS)];
+}
+
+/**
+ * glnx_mkdtempat:
+ * @dfd: Directory fd
+ * @tmpl: (type filename): Initial template directory name, last 6 characters will be replaced
+ * @mode: permissions with which to create the temporary directory
+ * @out_tmpdir: (out caller-allocates): Initialized tempdir structure
+ * @error: Error
+ *
+ * Somewhat similar to g_mkdtemp_full(), but fd-relative, and returns a
+ * structure that uses autocleanups.  Note that the supplied @dfd lifetime
+ * must match or exceed that of @out_tmpdir in order to remove the directory.
+ */
+gboolean
+glnx_mkdtempat (int dfd, const char *tmpl, int mode,
+                GLnxTmpDir *out_tmpdir, GError **error)
+{
+  g_return_val_if_fail (tmpl != NULL, FALSE);
+  g_return_val_if_fail (out_tmpdir != NULL, FALSE);
+  g_return_val_if_fail (!out_tmpdir->initialized, FALSE);
+
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  g_autofree char *path = g_strdup (tmpl);
+  for (int count = 0; count < 100; count++)
+    {
+      glnx_gen_temp_name (path);
+
+      /* Ideally we could use openat(O_DIRECTORY | O_CREAT | O_EXCL) here
+       * to create and open the directory atomically, but that’s not supported by
+       * current kernel versions: http://www.openwall.com/lists/oss-security/2014/11/26/14
+       * (Tested on kernel 4.10.10-200.fc25.x86_64). For the moment, accept a
+       * TOCTTOU race here. */
+      if (mkdirat (dfd, path, mode) == -1)
+        {
+          if (errno == EEXIST)
+            continue;
+
+          /* Any other error will apply also to other names we might
+           *  try, and there are 2^32 or so of them, so give up now.
+           */
+          return glnx_throw_errno_prefix (error, "mkdirat");
+        }
+
+      /* And open it */
+      glnx_autofd int ret_dfd = -1;
+      if (!glnx_opendirat (dfd, path, FALSE, &ret_dfd, error))
+        {
+          /* If we fail to open, let's try to clean up */
+          (void)unlinkat (dfd, path, AT_REMOVEDIR);
+          return FALSE;
+        }
+
+      /* Return the initialized directory struct */
+      out_tmpdir->initialized = TRUE;
+      out_tmpdir->src_dfd = dfd; /* referenced; see above docs */
+      out_tmpdir->fd = glnx_steal_fd (&ret_dfd);
+      out_tmpdir->path = g_steal_pointer (&path);
+      return TRUE;
+    }
+
+  /* Failure */
+  g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS,
+               "glnx_mkdtempat ran out of combinations to try");
+  return FALSE;
+}
+
+/**
+ * glnx_mkdtemp:
+ * @tmpl: (type filename): Source template directory name, last 6 characters will be replaced
+ * @mode: permissions to create the temporary directory with
+ * @out_tmpdir: (out caller-allocates): Return location for tmpdir data
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Similar to glnx_mkdtempat(), but will use g_get_tmp_dir() as the parent
+ * directory to @tmpl.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ * Since: UNRELEASED
+ */
+gboolean
+glnx_mkdtemp (const gchar   *tmpl,
+              int      mode,
+              GLnxTmpDir *out_tmpdir,
+              GError **error)
+{
+  g_autofree char *path = g_build_filename (g_get_tmp_dir (), tmpl, NULL);
+  return glnx_mkdtempat (AT_FDCWD, path, mode,
+                         out_tmpdir, error);
+}
+
+static gboolean
+_glnx_tmpdir_free (GLnxTmpDir *tmpd,
+                   gboolean    delete_dir,
+                   GCancellable *cancellable,
+                   GError    **error)
+{
+  /* Support being passed NULL so we work nicely in a GPtrArray */
+  if (!(tmpd && tmpd->initialized))
+    return TRUE;
+  g_assert_cmpint (tmpd->fd, !=, -1);
+  glnx_close_fd (&tmpd->fd);
+  g_assert (tmpd->path);
+  g_assert_cmpint (tmpd->src_dfd, !=, -1);
+  g_autofree char *path = tmpd->path; /* Take ownership */
+  tmpd->initialized = FALSE;
+  if (delete_dir)
+    {
+      if (!glnx_shutil_rm_rf_at (tmpd->src_dfd, path, cancellable, error))
+        return FALSE;
+    }
+  return TRUE;
+}
+
+/**
+ * glnx_tmpdir_delete:
+ * @tmpf: Temporary dir
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Deallocate a tmpdir, closing the fd and recursively deleting the path. This
+ * is normally called indirectly via glnx_tmpdir_cleanup() by the autocleanup
+ * attribute, but you can also invoke this directly.
+ *
+ * If an error occurs while deleting the filesystem path, @tmpf will still have
+ * been deallocated and should not be reused.
+ *
+ * See also `glnx_tmpdir_unset` to avoid deleting the path.
+ */
+gboolean
+glnx_tmpdir_delete (GLnxTmpDir *tmpf, GCancellable *cancellable, GError **error)
+{
+  return _glnx_tmpdir_free (tmpf, TRUE, cancellable, error);
+}
+
+/**
+ * glnx_tmpdir_unset:
+ * @tmpf: Temporary dir
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Deallocate a tmpdir, but do not delete the filesystem path.  See also
+ * `glnx_tmpdir_delete()`.
+ */
+void
+glnx_tmpdir_unset (GLnxTmpDir *tmpf)
+{
+  (void) _glnx_tmpdir_free (tmpf, FALSE, NULL, NULL);
+}
diff --git a/libglnx/glnx-dirfd.h b/libglnx/glnx-dirfd.h
new file mode 100644
index 0000000000000000000000000000000000000000..0046ac8eb651ebe9b753d604d1150a2ab2334478
--- /dev/null
+++ b/libglnx/glnx-dirfd.h
@@ -0,0 +1,137 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-backport-autocleanups.h>
+#include <glnx-macros.h>
+#include <glnx-errors.h>
+#include <limits.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+G_BEGIN_DECLS
+ 
+/**
+ * glnx_dirfd_canonicalize:
+ * @fd: A directory file descriptor
+ *
+ * It's often convenient in programs to use `-1` for "unassigned fd",
+ * and also because gobject-introspection doesn't support `AT_FDCWD`,
+ * libglnx honors `-1` to mean `AT_FDCWD`.  This small inline function
+ * canonicalizes `-1 -> AT_FDCWD`.
+ */
+static inline int
+glnx_dirfd_canonicalize (int fd)
+{
+  if (fd == -1)
+    return AT_FDCWD;
+  return fd;
+}
+
+struct GLnxDirFdIterator {
+  gboolean initialized;
+  int fd;
+  gpointer padding_data[4];
+};
+
+typedef struct GLnxDirFdIterator GLnxDirFdIterator;
+gboolean glnx_dirfd_iterator_init_at (int dfd, const char *path,
+                                    gboolean follow,
+                                    GLnxDirFdIterator *dfd_iter, GError **error);
+gboolean glnx_dirfd_iterator_init_take_fd (int *dfd, GLnxDirFdIterator *dfd_iter, GError **error);
+gboolean glnx_dirfd_iterator_next_dent (GLnxDirFdIterator  *dfd_iter,
+                                        struct dirent     **out_dent,
+                                        GCancellable       *cancellable,
+                                        GError            **error);
+gboolean glnx_dirfd_iterator_next_dent_ensure_dtype (GLnxDirFdIterator  *dfd_iter,
+                                                     struct dirent     **out_dent,
+                                                     GCancellable       *cancellable,
+                                                     GError            **error);
+void glnx_dirfd_iterator_clear (GLnxDirFdIterator *dfd_iter);
+
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GLnxDirFdIterator, glnx_dirfd_iterator_clear)
+
+int glnx_opendirat_with_errno (int           dfd,
+                               const char   *path,
+                               gboolean      follow);
+
+gboolean glnx_opendirat (int             dfd,
+                         const char     *path,
+                         gboolean        follow,
+                         int            *out_fd,
+                         GError        **error);
+
+char *glnx_fdrel_abspath (int         dfd,
+                          const char *path);
+
+void glnx_gen_temp_name (gchar *tmpl);
+
+/**
+ * glnx_ensure_dir:
+ * @dfd: directory fd
+ * @path: Directory path
+ * @mode: Mode
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Wrapper around mkdirat() which adds #GError support, ensures that
+ * it retries on %EINTR, and also ignores `EEXIST`.
+ *
+ * See also `glnx_shutil_mkdir_p_at()` for recursive handling.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ */
+static inline gboolean
+glnx_ensure_dir (int           dfd,
+                 const char   *path,
+                 mode_t        mode,
+                 GError      **error)
+{
+  if (TEMP_FAILURE_RETRY (mkdirat (dfd, path, mode)) != 0)
+    {
+      if (G_UNLIKELY (errno != EEXIST))
+        return glnx_throw_errno_prefix (error, "mkdirat(%s)", path);
+    }
+  return TRUE;
+}
+
+typedef struct {
+  gboolean initialized;
+  int src_dfd;
+  int fd;
+  char *path;
+} GLnxTmpDir;
+gboolean glnx_tmpdir_delete (GLnxTmpDir *tmpf, GCancellable *cancellable, GError **error);
+void glnx_tmpdir_unset (GLnxTmpDir *tmpf);
+static inline void
+glnx_tmpdir_cleanup (GLnxTmpDir *tmpf)
+{
+  (void)glnx_tmpdir_delete (tmpf, NULL, NULL);
+}
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GLnxTmpDir, glnx_tmpdir_cleanup)
+
+gboolean glnx_mkdtempat (int dfd, const char *tmpl, int mode,
+                         GLnxTmpDir *out_tmpdir, GError **error);
+
+gboolean glnx_mkdtemp (const char *tmpl, int      mode,
+                       GLnxTmpDir *out_tmpdir, GError **error);
+
+G_END_DECLS
diff --git a/libglnx/glnx-errors.c b/libglnx/glnx-errors.c
new file mode 100644
index 0000000000000000000000000000000000000000..f350f3059d6ef7f5c444eae010e48aab43208148
--- /dev/null
+++ b/libglnx/glnx-errors.c
@@ -0,0 +1,131 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-backport-autocleanups.h>
+#include <glnx-errors.h>
+
+/* Set @error with G_IO_ERROR/G_IO_ERROR_FAILED.
+ *
+ * This function returns %FALSE so it can be used conveniently in a single
+ * statement:
+ *
+ * ```
+ *   if (strcmp (foo, "somevalue") != 0)
+ *     return glnx_throw (error, "key must be somevalue, not '%s'", foo);
+ * ```
+ */
+gboolean
+glnx_throw (GError    **error,
+            const char *fmt,
+            ...)
+{
+  if (error == NULL)
+    return FALSE;
+
+  va_list args;
+  va_start (args, fmt);
+  GError *new = g_error_new_valist (G_IO_ERROR, G_IO_ERROR_FAILED, fmt, args);
+  va_end (args);
+  g_propagate_error (error, g_steal_pointer (&new));
+  return FALSE;
+}
+
+void
+glnx_real_set_prefix_error_va (GError     *error,
+                               const char *format,
+                               va_list     args)
+{
+  if (error == NULL)
+    return;
+
+  g_autofree char *old_msg = g_steal_pointer (&error->message);
+  g_autoptr(GString) buf = g_string_new ("");
+  g_string_append_vprintf (buf, format, args);
+  g_string_append (buf, ": ");
+  g_string_append (buf, old_msg);
+  error->message = g_string_free (g_steal_pointer (&buf), FALSE);
+}
+
+/* Prepend to @error's message by `$prefix: ` where `$prefix` is computed via
+ * printf @fmt. Returns %FALSE so it can be used conveniently in a single
+ * statement:
+ *
+ * ```
+ *   if (!function_that_fails (s, error))
+ *     return glnx_throw_prefix (error, "while handling '%s'", s);
+ * ```
+ * */
+gboolean
+glnx_prefix_error (GError    **error,
+                   const char *fmt,
+                   ...)
+{
+  if (error == NULL)
+    return FALSE;
+
+  va_list args;
+  va_start (args, fmt);
+  glnx_real_set_prefix_error_va (*error, fmt, args);
+  va_end (args);
+  return FALSE;
+}
+
+void
+glnx_real_set_prefix_error_from_errno_va (GError     **error,
+                                          gint         errsv,
+                                          const char  *format,
+                                          va_list      args)
+{
+  if (!error)
+    return;
+
+  g_set_error_literal (error,
+                       G_IO_ERROR,
+                       g_io_error_from_errno (errsv),
+                       g_strerror (errsv));
+  glnx_real_set_prefix_error_va (*error, format, args);
+}
+
+/* Set @error using the value of `$prefix: g_strerror (errno)` where `$prefix`
+ * is computed via printf @fmt.
+ *
+ * This function returns %FALSE so it can be used conveniently in a single
+ * statement:
+ *
+ * ```
+ *   return glnx_throw_errno_prefix (error, "unlinking %s", pathname);
+ * ```
+ */
+gboolean
+glnx_throw_errno_prefix (GError    **error,
+                         const char *fmt,
+                         ...)
+{
+  int errsv = errno;
+  va_list args;
+  va_start (args, fmt);
+  glnx_real_set_prefix_error_from_errno_va (error, errsv, fmt, args);
+  va_end (args);
+  /* See comment in glnx_throw_errno() about preserving errno */
+  errno = errsv;
+  return FALSE;
+}
diff --git a/libglnx/glnx-errors.h b/libglnx/glnx-errors.h
new file mode 100644
index 0000000000000000000000000000000000000000..cbe74a6063bf7afbc7b4bd0e0d479b444326cf63
--- /dev/null
+++ b/libglnx/glnx-errors.h
@@ -0,0 +1,134 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-backport-autocleanups.h>
+#include <errno.h>
+
+G_BEGIN_DECLS
+
+gboolean glnx_throw (GError **error, const char *fmt, ...) G_GNUC_PRINTF (2,3);
+
+/* Like `glnx_throw ()`, but returns %NULL. */
+#define glnx_null_throw(error, args...) \
+  ({glnx_throw (error, args); NULL;})
+
+/* Implementation detail of glnx_throw_prefix() */
+void glnx_real_set_prefix_error_va (GError     *error,
+                                    const char *format,
+                                    va_list     args) G_GNUC_PRINTF (2,0);
+
+gboolean glnx_prefix_error (GError **error, const char *fmt, ...) G_GNUC_PRINTF (2,3);
+
+/* Like `glnx_prefix_error ()`, but returns %NULL. */
+#define glnx_prefix_error_null(error, args...) \
+  ({glnx_prefix_error (error, args); NULL;})
+
+/**
+ * GLNX_AUTO_PREFIX_ERROR:
+ *
+ * An autocleanup-based macro to automatically call `g_prefix_error()` (also with a colon+space `: `)
+ * when it goes out of scope.  This is useful when one wants error strings built up by the callee
+ * function, not all callers.
+ *
+ * ```
+ * gboolean start_http_request (..., GError **error)
+ * {
+ *   GLNX_AUTO_PREFIX_ERROR ("HTTP request", error)
+ *
+ *   if (!libhttp_request_start (..., error))
+ *     return FALSE;
+ *   ...
+ *   return TRUE;
+ * ```
+ */
+typedef struct {
+  const char *prefix;
+  GError **error;
+} GLnxAutoErrorPrefix;
+static inline void
+glnx_cleanup_auto_prefix_error (GLnxAutoErrorPrefix *prefix)
+{
+  if (prefix->error && *(prefix->error))
+    g_prefix_error (prefix->error, "%s: ", prefix->prefix);
+}
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GLnxAutoErrorPrefix, glnx_cleanup_auto_prefix_error)
+#define GLNX_AUTO_PREFIX_ERROR(text, error) \
+  G_GNUC_UNUSED g_auto(GLnxAutoErrorPrefix) _GLNX_MAKE_ANONYMOUS(_glnxautoprefixerror_) = { text, error }
+
+/* Set @error using the value of `g_strerror (errno)`.
+ *
+ * This function returns %FALSE so it can be used conveniently in a single
+ * statement:
+ *
+ * ```
+ *   if (unlinkat (fd, somepathname) < 0)
+ *     return glnx_throw_errno (error);
+ * ```
+ */
+static inline gboolean
+glnx_throw_errno (GError **error)
+{
+  /* Save the value of errno, in case one of the
+   * intermediate function calls happens to set it.
+   */
+  int errsv = errno;
+  g_set_error_literal (error, G_IO_ERROR,
+                       g_io_error_from_errno (errsv),
+                       g_strerror (errsv));
+  /* We also restore the value of errno, since that's
+   * what was done in a long-ago libgsystem commit
+   * https://git.gnome.org/browse/libgsystem/commit/?id=ed106741f7a0596dc8b960b31fdae671d31d666d
+   * but I certainly can't remember now why I did that.
+   */
+  errno = errsv;
+  return FALSE;
+}
+
+/* Like glnx_throw_errno(), but yields a NULL pointer. */
+#define glnx_null_throw_errno(error) \
+  ({glnx_throw_errno (error); NULL;})
+
+/* Implementation detail of glnx_throw_errno_prefix() */
+void glnx_real_set_prefix_error_from_errno_va (GError     **error,
+                                               gint         errsv,
+                                               const char  *format,
+                                               va_list      args) G_GNUC_PRINTF (3,0);
+
+gboolean glnx_throw_errno_prefix (GError **error, const char *fmt, ...) G_GNUC_PRINTF (2,3);
+
+/* Like glnx_throw_errno_prefix(), but yields a NULL pointer. */
+#define glnx_null_throw_errno_prefix(error, args...) \
+  ({glnx_throw_errno_prefix (error, args); NULL;})
+
+/* BEGIN LEGACY APIS */
+
+#define glnx_set_error_from_errno(error)                \
+  do {                                                  \
+    glnx_throw_errno (error);                           \
+  } while (0);
+
+#define glnx_set_prefix_error_from_errno(error, format, args...)  \
+  do {                                                            \
+    glnx_throw_errno_prefix (error, format, args);                \
+  } while (0);
+
+G_END_DECLS
diff --git a/libglnx/glnx-fdio.c b/libglnx/glnx-fdio.c
new file mode 100644
index 0000000000000000000000000000000000000000..7b734ff6f1e6e85f72937bd3916de631a1ce6bb8
--- /dev/null
+++ b/libglnx/glnx-fdio.c
@@ -0,0 +1,1105 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * Portions derived from systemd:
+ *  Copyright 2010 Lennart Poettering
+ *
+ * This library 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 License, 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 <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/ioctl.h>
+#include <sys/sendfile.h>
+#include <errno.h>
+
+#include <glnx-fdio.h>
+#include <glnx-dirfd.h>
+#include <glnx-errors.h>
+#include <glnx-xattrs.h>
+#include <glnx-backport-autoptr.h>
+#include <glnx-local-alloc.h>
+#include <glnx-missing.h>
+
+/* The standardized version of BTRFS_IOC_CLONE */
+#ifndef FICLONE
+#define FICLONE _IOW(0x94, 9, int)
+#endif
+
+/* Returns the number of chars needed to format variables of the
+ * specified type as a decimal string. Adds in extra space for a
+ * negative '-' prefix (hence works correctly on signed
+ * types). Includes space for the trailing NUL. */
+#define DECIMAL_STR_MAX(type)                                           \
+        (2+(sizeof(type) <= 1 ? 3 :                                     \
+            sizeof(type) <= 2 ? 5 :                                     \
+            sizeof(type) <= 4 ? 10 :                                    \
+            sizeof(type) <= 8 ? 20 : sizeof(int[-2*(sizeof(type) > 8)])))
+
+gboolean
+glnx_stdio_file_flush (FILE *f, GError **error)
+{
+  if (fflush (f) != 0)
+    return glnx_throw_errno_prefix (error, "fflush");
+  if (ferror (f) != 0)
+    return glnx_throw_errno_prefix (error, "ferror");
+  return TRUE;
+}
+
+/* An implementation of renameat2(..., RENAME_NOREPLACE)
+ * with fallback to a non-atomic version.
+ */
+int
+glnx_renameat2_noreplace (int olddirfd, const char *oldpath,
+                          int newdirfd, const char *newpath)
+{
+#ifndef ENABLE_WRPSEUDO_COMPAT
+  if (renameat2 (olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE) < 0)
+    {
+      if (G_IN_SET(errno, EINVAL, ENOSYS))
+        {
+          /* Fall through */
+        }
+      else
+        {
+          return -1;
+        }
+    }
+  else
+    return TRUE;
+#endif
+
+  if (linkat (olddirfd, oldpath, newdirfd, newpath, 0) < 0)
+    return -1;
+
+  if (unlinkat (olddirfd, oldpath, 0) < 0)
+    return -1;
+
+  return 0;
+}
+
+static gboolean
+rename_file_noreplace_at (int olddirfd, const char *oldpath,
+                          int newdirfd, const char *newpath,
+                          gboolean ignore_eexist,
+                          GError **error)
+{
+  if (glnx_renameat2_noreplace (olddirfd, oldpath,
+                                newdirfd, newpath) < 0)
+    {
+      if (errno == EEXIST && ignore_eexist)
+        {
+          (void) unlinkat (olddirfd, oldpath, 0);
+          return TRUE;
+        }
+      else
+        return glnx_throw_errno_prefix (error, "renameat");
+    }
+  return TRUE;
+}
+
+/* An implementation of renameat2(..., RENAME_EXCHANGE)
+ * with fallback to a non-atomic version.
+ */
+int
+glnx_renameat2_exchange (int olddirfd, const char *oldpath,
+                         int newdirfd, const char *newpath)
+{
+#ifndef ENABLE_WRPSEUDO_COMPAT
+  if (renameat2 (olddirfd, oldpath, newdirfd, newpath, RENAME_EXCHANGE) == 0)
+    return 0;
+  else
+    {
+      if (G_IN_SET(errno, ENOSYS, EINVAL))
+        {
+          /* Fall through */
+        }
+      else
+        {
+          return -1;
+        }
+    }
+#endif
+
+  /* Fallback */
+  { char *old_tmp_name_buf = glnx_strjoina (oldpath, ".XXXXXX");
+    /* This obviously isn't race-free, but doing better gets tricky, since if
+     * we're here the kernel isn't likely to support RENAME_NOREPLACE either.
+     * Anyways, upgrade the kernel. Failing that, avoid use of this function in
+     * shared subdirectories like /tmp.
+     */
+    glnx_gen_temp_name (old_tmp_name_buf);
+    const char *old_tmp_name = old_tmp_name_buf;
+
+    /* Move old out of the way */
+    if (renameat (olddirfd, oldpath, olddirfd, old_tmp_name) < 0)
+      return -1;
+    /* Now move new into its place */
+    if (renameat (newdirfd, newpath, olddirfd, oldpath) < 0)
+      return -1;
+    /* And finally old(tmp) into new */
+    if (renameat (olddirfd, old_tmp_name, newdirfd, newpath) < 0)
+      return -1;
+  }
+  return 0;
+}
+
+/* Deallocate a tmpfile, closing the fd and deleting the path, if any. This is
+ * normally called by default by the autocleanup attribute, but you can also
+ * invoke this directly.
+ */
+void
+glnx_tmpfile_clear (GLnxTmpfile *tmpf)
+{
+  /* Support being passed NULL so we work nicely in a GPtrArray */
+  if (!tmpf)
+    return;
+  if (!tmpf->initialized)
+    return;
+  glnx_close_fd (&tmpf->fd);
+  /* If ->path is set, we're likely aborting due to an error. Clean it up */
+  if (tmpf->path)
+    {
+      (void) unlinkat (tmpf->src_dfd, tmpf->path, 0);
+      g_free (tmpf->path);
+    }
+  tmpf->initialized = FALSE;
+}
+
+static gboolean
+open_tmpfile_core (int dfd, const char *subpath,
+                   int flags,
+                   GLnxTmpfile *out_tmpf,
+                   GError **error)
+{
+  /* Picked this to match mkstemp() */
+  const guint mode = 0600;
+
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  /* Creates a temporary file, that shall be renamed to "target"
+   * later. If possible, this uses O_TMPFILE – in which case
+   * "ret_path" will be returned as NULL. If not possible a the
+   * tempoary path name used is returned in "ret_path". Use
+   * link_tmpfile() below to rename the result after writing the file
+   * in full. */
+#if defined(O_TMPFILE) && !defined(DISABLE_OTMPFILE) && !defined(ENABLE_WRPSEUDO_COMPAT)
+  {
+    glnx_autofd int fd = openat (dfd, subpath, O_TMPFILE|flags, mode);
+    if (fd == -1 && !(G_IN_SET(errno, ENOSYS, EISDIR, EOPNOTSUPP)))
+      return glnx_throw_errno_prefix (error, "open(O_TMPFILE)");
+    if (fd != -1)
+      {
+        /* Workaround for https://sourceware.org/bugzilla/show_bug.cgi?id=17523
+         * See also https://github.com/ostreedev/ostree/issues/991
+         */
+        if (fchmod (fd, mode) < 0)
+          return glnx_throw_errno_prefix (error, "fchmod");
+        out_tmpf->initialized = TRUE;
+        out_tmpf->src_dfd = dfd; /* Copied; caller must keep open */
+        out_tmpf->fd = glnx_steal_fd (&fd);
+        out_tmpf->path = NULL;
+        return TRUE;
+      }
+  }
+  /* Fallthrough */
+#endif
+
+  const guint count_max = 100;
+  { g_autofree char *tmp = g_strconcat (subpath, "/tmp.XXXXXX", NULL);
+
+    for (int count = 0; count < count_max; count++)
+      {
+        glnx_gen_temp_name (tmp);
+
+        glnx_autofd int fd = openat (dfd, tmp, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|flags, mode);
+        if (fd < 0)
+          {
+            if (errno == EEXIST)
+              continue;
+            else
+              return glnx_throw_errno_prefix (error, "Creating temp file");
+          }
+        else
+          {
+            out_tmpf->initialized = TRUE;
+            out_tmpf->src_dfd = dfd;  /* Copied; caller must keep open */
+            out_tmpf->fd = glnx_steal_fd (&fd);
+            out_tmpf->path = g_steal_pointer (&tmp);
+            return TRUE;
+          }
+      }
+  }
+  g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS,
+               "Exhausted %u attempts to create temporary file", count_max);
+  return FALSE;
+}
+
+/* Allocate a temporary file, using Linux O_TMPFILE if available. The file mode
+ * will be 0600.
+ *
+ * The result will be stored in @out_tmpf, which is caller allocated
+ * so you can store it on the stack in common scenarios.
+ *
+ * The directory fd @dfd must live at least as long as the output @out_tmpf.
+ */
+gboolean
+glnx_open_tmpfile_linkable_at (int dfd,
+                               const char *subpath,
+                               int flags,
+                               GLnxTmpfile *out_tmpf,
+                               GError **error)
+{
+  /* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE;
+   * it's used for glnx_open_anonymous_tmpfile().
+   */
+  g_return_val_if_fail ((flags & O_EXCL) == 0, FALSE);
+
+  return open_tmpfile_core (dfd, subpath, flags, out_tmpf, error);
+}
+
+/* A variant of `glnx_open_tmpfile_linkable_at()` which doesn't support linking.
+ * Useful for true temporary storage. The fd will be allocated in /var/tmp to
+ * ensure maximum storage space.
+ */
+gboolean
+glnx_open_anonymous_tmpfile (int          flags,
+                             GLnxTmpfile *out_tmpf,
+                             GError     **error)
+{
+  /* Add in O_EXCL */
+  if (!open_tmpfile_core (AT_FDCWD, "/var/tmp", flags | O_EXCL, out_tmpf, error))
+    return FALSE;
+  if (out_tmpf->path)
+    {
+      (void) unlinkat (out_tmpf->src_dfd, out_tmpf->path, 0);
+      g_clear_pointer (&out_tmpf->path, g_free);
+    }
+  out_tmpf->anonymous = TRUE;
+  out_tmpf->src_dfd = -1;
+  return TRUE;
+}
+
+/* Use this after calling glnx_open_tmpfile_linkable_at() to give
+ * the file its final name (link into place).
+ */
+gboolean
+glnx_link_tmpfile_at (GLnxTmpfile *tmpf,
+                      GLnxLinkTmpfileReplaceMode mode,
+                      int target_dfd,
+                      const char *target,
+                      GError **error)
+{
+  const gboolean replace = (mode == GLNX_LINK_TMPFILE_REPLACE);
+  const gboolean ignore_eexist = (mode == GLNX_LINK_TMPFILE_NOREPLACE_IGNORE_EXIST);
+
+  g_return_val_if_fail (!tmpf->anonymous, FALSE);
+  g_return_val_if_fail (tmpf->fd >= 0, FALSE);
+  g_return_val_if_fail (tmpf->src_dfd == AT_FDCWD || tmpf->src_dfd >= 0, FALSE);
+
+  /* Unlike the original systemd code, this function also supports
+   * replacing existing files.
+   */
+
+  /* We have `tmpfile_path` for old systems without O_TMPFILE. */
+  if (tmpf->path)
+    {
+      if (replace)
+        {
+          /* We have a regular tempfile, we're overwriting - this is a
+           * simple renameat().
+           */
+          if (renameat (tmpf->src_dfd, tmpf->path, target_dfd, target) < 0)
+            return glnx_throw_errno_prefix (error, "renameat");
+        }
+      else
+        {
+          /* We need to use renameat2(..., NOREPLACE) or emulate it */
+          if (!rename_file_noreplace_at (tmpf->src_dfd, tmpf->path, target_dfd, target,
+                                         ignore_eexist,
+                                         error))
+            return FALSE;
+        }
+      /* Now, clear the pointer so we don't try to unlink it */
+      g_clear_pointer (&tmpf->path, g_free);
+    }
+  else
+    {
+      /* This case we have O_TMPFILE, so our reference to it is via /proc/self/fd */
+      char proc_fd_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(tmpf->fd) + 1];
+
+      sprintf (proc_fd_path, "/proc/self/fd/%i", tmpf->fd);
+
+      if (replace)
+        {
+          /* In this case, we had our temp file atomically hidden, but now
+           * we need to make it visible in the FS so we can do a rename.
+           * Ideally, linkat() would gain AT_REPLACE or so.
+           */
+          /* TODO - avoid double alloca, we can just alloca a copy of
+           * the pathname plus space for tmp.XXXXX */
+          char *dnbuf = strdupa (target);
+          const char *dn = dirname (dnbuf);
+          char *tmpname_buf = glnx_strjoina (dn, "/tmp.XXXXXX");
+
+          const guint count_max = 100;
+          guint count;
+          for (count = 0; count < count_max; count++)
+            {
+              glnx_gen_temp_name (tmpname_buf);
+
+              if (linkat (AT_FDCWD, proc_fd_path, target_dfd, tmpname_buf, AT_SYMLINK_FOLLOW) < 0)
+                {
+                  if (errno == EEXIST)
+                    continue;
+                  else
+                    return glnx_throw_errno_prefix (error, "linkat");
+                }
+              else
+                break;
+            }
+          if (count == count_max)
+            {
+              g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS,
+               "Exhausted %u attempts to create temporary file", count);
+              return FALSE;
+            }
+          if (!glnx_renameat (target_dfd, tmpname_buf, target_dfd, target, error))
+            {
+              /* This is currently the only case where we need to have
+               * a cleanup unlinkat() still with O_TMPFILE.
+               */
+              (void) unlinkat (target_dfd, tmpname_buf, 0);
+              return FALSE;
+            }
+        }
+      else
+        {
+          if (linkat (AT_FDCWD, proc_fd_path, target_dfd, target, AT_SYMLINK_FOLLOW) < 0)
+            {
+              if (errno == EEXIST && mode == GLNX_LINK_TMPFILE_NOREPLACE_IGNORE_EXIST)
+                ;
+              else
+                return glnx_throw_errno_prefix (error, "linkat");
+            }
+        }
+
+    }
+  return TRUE;
+}
+
+/**
+ * glnx_openat_rdonly:
+ * @dfd: File descriptor for origin directory
+ * @path: Pathname, relative to @dfd
+ * @follow: Whether or not to follow symbolic links in the final component
+ * @out_fd: (out): File descriptor
+ * @error: Error
+ *
+ * Use openat() to open a file, with flags `O_RDONLY | O_CLOEXEC | O_NOCTTY`.
+ * Like the other libglnx wrappers, will use `TEMP_FAILURE_RETRY` and
+ * also includes @path in @error in case of failure.
+ */
+gboolean
+glnx_openat_rdonly (int             dfd,
+                    const char     *path,
+                    gboolean        follow,
+                    int            *out_fd,
+                    GError        **error)
+{
+  int flags = O_RDONLY | O_CLOEXEC | O_NOCTTY;
+  if (!follow)
+    flags |= O_NOFOLLOW;
+  int fd = TEMP_FAILURE_RETRY (openat (dfd, path, flags));
+  if (fd == -1)
+    return glnx_throw_errno_prefix (error, "openat(%s)", path);
+  *out_fd = fd;
+  return TRUE;
+}
+
+static guint8*
+glnx_fd_readall_malloc (int               fd,
+                        gsize            *out_len,
+                        gboolean          nul_terminate,
+                        GCancellable     *cancellable,
+                        GError          **error)
+{
+  const guint maxreadlen = 4096;
+
+  struct stat stbuf;
+  if (!glnx_fstat (fd, &stbuf, error))
+    return FALSE;
+
+  gsize buf_allocated;
+  if (S_ISREG (stbuf.st_mode) && stbuf.st_size > 0)
+    buf_allocated = stbuf.st_size;
+  else
+    buf_allocated = 16;
+
+  g_autofree guint8* buf = g_malloc (buf_allocated);
+
+  gsize buf_size = 0;
+  while (TRUE)
+    {
+      gsize readlen = MIN (buf_allocated - buf_size, maxreadlen);
+
+      if (g_cancellable_set_error_if_cancelled (cancellable, error))
+        return FALSE;
+
+      gssize bytes_read;
+      do
+        bytes_read = read (fd, buf + buf_size, readlen);
+      while (G_UNLIKELY (bytes_read == -1 && errno == EINTR));
+      if (G_UNLIKELY (bytes_read == -1))
+        return glnx_null_throw_errno (error);
+      if (bytes_read == 0)
+        break;
+
+      buf_size += bytes_read;
+      if (buf_allocated - buf_size < maxreadlen)
+        buf = g_realloc (buf, buf_allocated *= 2);
+    }
+
+  if (nul_terminate)
+    {
+      if (buf_allocated - buf_size == 0)
+        buf = g_realloc (buf, buf_allocated + 1);
+      buf[buf_size] = '\0';
+    }
+
+  *out_len = buf_size;
+  return g_steal_pointer (&buf);
+}
+
+/**
+ * glnx_fd_readall_bytes:
+ * @fd: A file descriptor
+ * @cancellable: Cancellable:
+ * @error: Error
+ *
+ * Read all data from file descriptor @fd into a #GBytes.  It's
+ * recommended to only use this for small files.
+ *
+ * Returns: (transfer full): A newly allocated #GBytes
+ */
+GBytes *
+glnx_fd_readall_bytes (int               fd,
+                       GCancellable     *cancellable,
+                       GError          **error)
+{
+  gsize len;
+  guint8 *buf = glnx_fd_readall_malloc (fd, &len, FALSE, cancellable, error);
+  if (!buf)
+    return NULL;
+  return g_bytes_new_take (buf, len);
+}
+
+/**
+ * glnx_fd_readall_utf8:
+ * @fd: A file descriptor
+ * @out_len: (out): Returned length
+ * @cancellable: Cancellable:
+ * @error: Error
+ *
+ * Read all data from file descriptor @fd, validating
+ * the result as UTF-8.
+ *
+ * Returns: (transfer full): A string validated as UTF-8, or %NULL on error.
+ */
+char *
+glnx_fd_readall_utf8 (int               fd,
+                      gsize            *out_len,
+                      GCancellable     *cancellable,
+                      GError          **error)
+{
+  gsize len;
+  g_autofree guint8 *buf = glnx_fd_readall_malloc (fd, &len, TRUE, cancellable, error);
+  if (!buf)
+    return FALSE;
+
+  if (!g_utf8_validate ((char*)buf, len, NULL))
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   G_IO_ERROR_INVALID_DATA,
+                   "Invalid UTF-8");
+      return FALSE;
+    }
+
+  if (out_len)
+    *out_len = len;
+  return (char*)g_steal_pointer (&buf);
+}
+
+/**
+ * glnx_file_get_contents_utf8_at:
+ * @dfd: Directory file descriptor
+ * @subpath: Path relative to @dfd
+ * @out_len: (out) (allow-none): Optional length
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Read the entire contents of the file referred
+ * to by @dfd and @subpath, validate the result as UTF-8.
+ * The length is optionally stored in @out_len.
+ *
+ * Returns: (transfer full): UTF-8 validated text, or %NULL on error
+ */
+char *
+glnx_file_get_contents_utf8_at (int                   dfd,
+                                const char           *subpath,
+                                gsize                *out_len,
+                                GCancellable         *cancellable,
+                                GError              **error)
+{
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  glnx_autofd int fd = -1;
+  if (!glnx_openat_rdonly (dfd, subpath, TRUE, &fd, error))
+    return NULL;
+
+  gsize len;
+  g_autofree char *buf = glnx_fd_readall_utf8 (fd, &len, cancellable, error);
+  if (G_UNLIKELY(!buf))
+    return FALSE;
+
+  if (out_len)
+    *out_len = len;
+  return g_steal_pointer (&buf);
+}
+
+/**
+ * glnx_readlinkat_malloc:
+ * @dfd: Directory file descriptor
+ * @subpath: Subpath
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Read the value of a symlink into a dynamically
+ * allocated buffer.
+ */
+char *
+glnx_readlinkat_malloc (int            dfd,
+                        const char    *subpath,
+                        GCancellable  *cancellable,
+                        GError       **error)
+{
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  size_t l = 100;
+  for (;;)
+    {
+      g_autofree char *c = g_malloc (l);
+      ssize_t n = TEMP_FAILURE_RETRY (readlinkat (dfd, subpath, c, l-1));
+      if (n < 0)
+        return glnx_null_throw_errno_prefix (error, "readlinkat");
+
+      if ((size_t) n < l-1)
+        {
+          c[n] = 0;
+          return g_steal_pointer (&c);
+        }
+
+      l *= 2;
+    }
+
+  g_assert_not_reached ();
+}
+
+static gboolean
+copy_symlink_at (int                   src_dfd,
+                 const char           *src_subpath,
+                 const struct stat    *src_stbuf,
+                 int                   dest_dfd,
+                 const char           *dest_subpath,
+                 GLnxFileCopyFlags     copyflags,
+                 GCancellable         *cancellable,
+                 GError              **error)
+{
+  g_autofree char *buf = glnx_readlinkat_malloc (src_dfd, src_subpath, cancellable, error);
+  if (!buf)
+    return FALSE;
+
+  if (TEMP_FAILURE_RETRY (symlinkat (buf, dest_dfd, dest_subpath)) != 0)
+    return glnx_throw_errno_prefix (error, "symlinkat");
+
+  if (!(copyflags & GLNX_FILE_COPY_NOXATTRS))
+    {
+      g_autoptr(GVariant) xattrs = NULL;
+
+      if (!glnx_dfd_name_get_all_xattrs (src_dfd, src_subpath, &xattrs,
+                                         cancellable, error))
+        return FALSE;
+
+      if (!glnx_dfd_name_set_all_xattrs (dest_dfd, dest_subpath, xattrs,
+                                         cancellable, error))
+        return FALSE;
+    }
+
+  if (TEMP_FAILURE_RETRY (fchownat (dest_dfd, dest_subpath,
+                                    src_stbuf->st_uid, src_stbuf->st_gid,
+                                    AT_SYMLINK_NOFOLLOW)) != 0)
+    return glnx_throw_errno_prefix (error, "fchownat");
+
+  return TRUE;
+}
+
+#define COPY_BUFFER_SIZE (16*1024)
+
+/* Most of the code below is from systemd, but has been reindented to GNU style,
+ * and changed to use POSIX error conventions (return -1, set errno) to more
+ * conveniently fit in with the rest of libglnx.
+ */
+
+/* Like write(), but loop until @nbytes are written, or an error
+ * occurs.
+ *
+ * On error, -1 is returned an @errno is set.  NOTE: This is an
+ * API change from previous versions of this function.
+ */
+int
+glnx_loop_write(int fd, const void *buf, size_t nbytes)
+{
+  g_return_val_if_fail (fd >= 0, -1);
+  g_return_val_if_fail (buf, -1);
+
+  errno = 0;
+
+  const uint8_t *p = buf;
+  while (nbytes > 0)
+    {
+      ssize_t k = write(fd, p, nbytes);
+      if (k < 0)
+        {
+          if (errno == EINTR)
+            continue;
+
+          return -1;
+        }
+
+      if (k == 0) /* Can't really happen */
+        {
+          errno = EIO;
+          return -1;
+        }
+
+      p += k;
+      nbytes -= k;
+    }
+
+  return 0;
+}
+
+/* Read from @fdf until EOF, writing to @fdt. If max_bytes is -1, a full-file
+ * clone will be attempted. Otherwise Linux copy_file_range(), sendfile()
+ * syscall will be attempted.  If none of those work, this function will do a
+ * plain read()/write() loop.
+ *
+ * The file descriptor @fdf must refer to a regular file.
+ *
+ * If provided, @max_bytes specifies the maximum number of bytes to read from @fdf.
+ * On error, this function returns `-1` and @errno will be set.
+ */
+int
+glnx_regfile_copy_bytes (int fdf, int fdt, off_t max_bytes)
+{
+  /* Last updates from systemd as of commit 6bda23dd6aaba50cf8e3e6024248cf736cc443ca */
+  static int have_cfr = -1; /* -1 means unknown */
+  bool try_cfr = have_cfr != 0;
+  static int have_sendfile = -1; /* -1 means unknown */
+  bool try_sendfile = have_sendfile != 0;
+
+  g_return_val_if_fail (fdf >= 0, -1);
+  g_return_val_if_fail (fdt >= 0, -1);
+  g_return_val_if_fail (max_bytes >= -1, -1);
+
+  /* If we've requested to copy the whole range, try a full-file clone first.
+   */
+  if (max_bytes == (off_t) -1)
+    {
+      if (ioctl (fdt, FICLONE, fdf) == 0)
+        return 0;
+      /* Fall through */
+      struct stat stbuf;
+
+      /* Gather the size so we can provide the whole thing at once to
+       * copy_file_range() or sendfile().
+       */
+      if (fstat (fdf, &stbuf) < 0)
+        return -1;
+      max_bytes = stbuf.st_size;
+    }
+
+  while (TRUE)
+    {
+      ssize_t n;
+
+      /* First, try copy_file_range(). Note this is an inlined version of
+       * try_copy_file_range() from systemd upstream, which works better since
+       * we use POSIX errno style.
+       */
+      if (try_cfr)
+        {
+          n = copy_file_range (fdf, NULL, fdt, NULL, max_bytes, 0u);
+          if (n < 0)
+            {
+              if (errno == ENOSYS)
+                {
+                  /* No cfr in kernel, mark as permanently unavailable
+                   * and fall through to sendfile().
+                   */
+                  have_cfr = 0;
+                  try_cfr = false;
+                }
+              else if (errno == EXDEV)
+                /* We won't try cfr again for this run, but let's be
+                 * conservative and not mark it as available/unavailable until
+                 * we know for sure.
+                 */
+                try_cfr = false;
+              else
+                return -1;
+            }
+          else
+            {
+              /* cfr worked, mark it as available */
+              if (have_cfr == -1)
+                have_cfr = 1;
+
+              if (n == 0) /* EOF */
+                break;
+              else
+                /* Success! */
+                goto next;
+            }
+        }
+
+      /* Next try sendfile(); this version is also changed from systemd upstream
+       * to match the same logic we have for copy_file_range().
+       */
+      if (try_sendfile)
+        {
+          n = sendfile (fdt, fdf, NULL, max_bytes);
+          if (n < 0)
+            {
+              if (G_IN_SET (errno, EINVAL, ENOSYS))
+                {
+                  /* No sendfile(), or it doesn't work on regular files.
+                   * Mark it as permanently unavailable, and fall through
+                   * to plain read()/write().
+                   */
+                  have_sendfile = 0;
+                  try_sendfile = false;
+                }
+              else
+                return -1;
+            }
+          else
+            {
+              /* sendfile() worked, mark it as available */
+              if (have_sendfile == -1)
+                have_sendfile = 1;
+
+              if (n == 0) /* EOF */
+                break;
+              else if (n > 0)
+                /* Succcess! */
+                goto next;
+            }
+        }
+
+      /* As a fallback just copy bits by hand */
+      { size_t m = COPY_BUFFER_SIZE;
+        if (max_bytes != (off_t) -1)
+          {
+            if ((off_t) m > max_bytes)
+              m = (size_t) max_bytes;
+          }
+        char buf[m];
+
+        n = TEMP_FAILURE_RETRY (read (fdf, buf, m));
+        if (n < 0)
+          return -1;
+        if (n == 0) /* EOF */
+          break;
+
+        if (glnx_loop_write (fdt, buf, (size_t) n) < 0)
+          return -1;
+      }
+
+    next:
+      if (max_bytes != (off_t) -1)
+        {
+          g_assert_cmpint (max_bytes, >=, n);
+          max_bytes -= n;
+          if (max_bytes == 0)
+            break;
+        }
+    }
+
+  return 0;
+}
+
+/**
+ * glnx_file_copy_at:
+ * @src_dfd: Source directory fd
+ * @src_subpath: Subpath relative to @src_dfd
+ * @src_stbuf: (allow-none): Optional stat buffer for source; if a stat() has already been done
+ * @dest_dfd: Target directory fd
+ * @dest_subpath: Destination name
+ * @copyflags: Flags
+ * @cancellable: cancellable
+ * @error: Error
+ *
+ * Perform a full copy of the regular file or symbolic link from @src_subpath to
+ * @dest_subpath; if @src_subpath is anything other than a regular file or
+ * symbolic link, an error will be returned.
+ *
+ * If the source is a regular file and the destination exists as a symbolic
+ * link, the symbolic link will not be followed; rather the link itself will be
+ * replaced. Related to this: for regular files, when `GLNX_FILE_COPY_OVERWRITE`
+ * is specified, this function always uses `O_TMPFILE` (if available) and does a
+ * rename-into-place rather than `open(O_TRUNC)`.
+ */
+gboolean
+glnx_file_copy_at (int                   src_dfd,
+                   const char           *src_subpath,
+                   struct stat          *src_stbuf,
+                   int                   dest_dfd,
+                   const char           *dest_subpath,
+                   GLnxFileCopyFlags     copyflags,
+                   GCancellable         *cancellable,
+                   GError              **error)
+{
+  /* Canonicalize dfds */
+  src_dfd = glnx_dirfd_canonicalize (src_dfd);
+  dest_dfd = glnx_dirfd_canonicalize (dest_dfd);
+
+  if (g_cancellable_set_error_if_cancelled (cancellable, error))
+    return FALSE;
+
+  /* Automatically do stat() if no stat buffer was supplied */
+  struct stat local_stbuf;
+  if (!src_stbuf)
+    {
+      if (!glnx_fstatat (src_dfd, src_subpath, &local_stbuf, AT_SYMLINK_NOFOLLOW, error))
+        return FALSE;
+      src_stbuf = &local_stbuf;
+    }
+
+  /* For symlinks, defer entirely to copy_symlink_at() */
+  if (S_ISLNK (src_stbuf->st_mode))
+    {
+      return copy_symlink_at (src_dfd, src_subpath, src_stbuf,
+                              dest_dfd, dest_subpath,
+                              copyflags,
+                              cancellable, error);
+    }
+  else if (!S_ISREG (src_stbuf->st_mode))
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                   "Cannot copy non-regular/non-symlink file: %s", src_subpath);
+      return FALSE;
+    }
+
+  /* Regular file path below here */
+
+  glnx_autofd int src_fd = -1;
+  if (!glnx_openat_rdonly (src_dfd, src_subpath, FALSE, &src_fd, error))
+    return FALSE;
+
+  /* Open a tmpfile for dest. Particularly for AT_FDCWD calls, we really want to
+   * open in the target directory, otherwise we may not be able to link.
+   */
+  g_auto(GLnxTmpfile) tmp_dest = { 0, };
+  { char *dnbuf = strdupa (dest_subpath);
+    const char *dn = dirname (dnbuf);
+    if (!glnx_open_tmpfile_linkable_at (dest_dfd, dn, O_WRONLY | O_CLOEXEC,
+                                        &tmp_dest, error))
+      return FALSE;
+  }
+
+  if (glnx_regfile_copy_bytes (src_fd, tmp_dest.fd, (off_t) -1) < 0)
+    return glnx_throw_errno_prefix (error, "regfile copy");
+
+  if (fchown (tmp_dest.fd, src_stbuf->st_uid, src_stbuf->st_gid) != 0)
+    return glnx_throw_errno_prefix (error, "fchown");
+
+  if (!(copyflags & GLNX_FILE_COPY_NOXATTRS))
+    {
+      g_autoptr(GVariant) xattrs = NULL;
+
+      if (!glnx_fd_get_all_xattrs (src_fd, &xattrs,
+                                   cancellable, error))
+        return FALSE;
+
+      if (!glnx_fd_set_all_xattrs (tmp_dest.fd, xattrs,
+                                   cancellable, error))
+        return FALSE;
+    }
+
+  /* Always chmod after setting xattrs, in case the file has mode 0400 or less,
+   * like /etc/shadow.  Linux currently allows write() on non-writable open files
+   * but not fsetxattr().
+   */
+  if (fchmod (tmp_dest.fd, src_stbuf->st_mode & 07777) != 0)
+    return glnx_throw_errno_prefix (error, "fchmod");
+
+  struct timespec ts[2];
+  ts[0] = src_stbuf->st_atim;
+  ts[1] = src_stbuf->st_mtim;
+  (void) futimens (tmp_dest.fd, ts);
+
+  if (copyflags & GLNX_FILE_COPY_DATASYNC)
+    {
+      if (fdatasync (tmp_dest.fd) < 0)
+        return glnx_throw_errno_prefix (error, "fdatasync");
+    }
+
+  const GLnxLinkTmpfileReplaceMode replacemode =
+    (copyflags & GLNX_FILE_COPY_OVERWRITE) ?
+    GLNX_LINK_TMPFILE_REPLACE :
+    GLNX_LINK_TMPFILE_NOREPLACE;
+
+  if (!glnx_link_tmpfile_at (&tmp_dest, replacemode, dest_dfd, dest_subpath, error))
+    return FALSE;
+
+  return TRUE;
+}
+
+/**
+ * glnx_file_replace_contents_at:
+ * @dfd: Directory fd
+ * @subpath: Subpath
+ * @buf: (array len=len) (element-type guint8): File contents
+ * @len: Length (if `-1`, assume @buf is `NUL` terminated)
+ * @flags: Flags
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Create a new file, atomically replacing the contents of @subpath
+ * (relative to @dfd) with @buf.  By default, if the file already
+ * existed, fdatasync() will be used before rename() to ensure stable
+ * contents.  This and other behavior can be controlled via @flags.
+ *
+ * Note that no metadata from the existing file is preserved, such as
+ * uid/gid or extended attributes.  The default mode will be `0644`.
+ */ 
+gboolean
+glnx_file_replace_contents_at (int                   dfd,
+                               const char           *subpath,
+                               const guint8         *buf,
+                               gsize                 len,
+                               GLnxFileReplaceFlags  flags,
+                               GCancellable         *cancellable,
+                               GError              **error)
+{
+  return glnx_file_replace_contents_with_perms_at (dfd, subpath, buf, len,
+                                                   (mode_t) -1, (uid_t) -1, (gid_t) -1,
+                                                   flags, cancellable, error);
+}
+
+/**
+ * glnx_file_replace_contents_with_perms_at:
+ * @dfd: Directory fd
+ * @subpath: Subpath
+ * @buf: (array len=len) (element-type guint8): File contents
+ * @len: Length (if `-1`, assume @buf is `NUL` terminated)
+ * @mode: File mode; if `-1`, use `0644`
+ * @flags: Flags
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Like glnx_file_replace_contents_at(), but also supports
+ * setting mode, and uid/gid.
+ */ 
+gboolean
+glnx_file_replace_contents_with_perms_at (int                   dfd,
+                                          const char           *subpath,
+                                          const guint8         *buf,
+                                          gsize                 len,
+                                          mode_t                mode,
+                                          uid_t                 uid,
+                                          gid_t                 gid,
+                                          GLnxFileReplaceFlags  flags,
+                                          GCancellable         *cancellable,
+                                          GError              **error)
+{
+  char *dnbuf = strdupa (subpath);
+  const char *dn = dirname (dnbuf);
+
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  /* With O_TMPFILE we can't use umask, and we can't sanely query the
+   * umask...let's assume something relatively standard.
+   */
+  if (mode == (mode_t) -1)
+    mode = 0644;
+
+  g_auto(GLnxTmpfile) tmpf = { 0, };
+  if (!glnx_open_tmpfile_linkable_at (dfd, dn, O_WRONLY | O_CLOEXEC,
+                                      &tmpf, error))
+    return FALSE;
+
+  if (len == -1)
+    len = strlen ((char*)buf);
+
+  if (!glnx_try_fallocate (tmpf.fd, 0, len, error))
+    return FALSE;
+
+  if (glnx_loop_write (tmpf.fd, buf, len) < 0)
+    return glnx_throw_errno_prefix (error, "write");
+
+  if (!(flags & GLNX_FILE_REPLACE_NODATASYNC))
+    {
+      struct stat stbuf;
+      gboolean do_sync;
+
+      if (!glnx_fstatat_allow_noent (dfd, subpath, &stbuf, AT_SYMLINK_NOFOLLOW, error))
+        return FALSE;
+      if (errno == ENOENT)
+        do_sync = (flags & GLNX_FILE_REPLACE_DATASYNC_NEW) > 0;
+      else
+        do_sync = TRUE;
+
+      if (do_sync)
+        {
+          if (fdatasync (tmpf.fd) != 0)
+            return glnx_throw_errno_prefix (error, "fdatasync");
+        }
+    }
+
+  if (uid != (uid_t) -1)
+    {
+      if (fchown (tmpf.fd, uid, gid) != 0)
+        return glnx_throw_errno_prefix (error, "fchown");
+    }
+
+  if (fchmod (tmpf.fd, mode) != 0)
+    return glnx_throw_errno_prefix (error, "fchmod");
+
+  if (!glnx_link_tmpfile_at (&tmpf, GLNX_LINK_TMPFILE_REPLACE,
+                             dfd, subpath, error))
+    return FALSE;
+
+  return TRUE;
+}
diff --git a/libglnx/glnx-fdio.h b/libglnx/glnx-fdio.h
new file mode 100644
index 0000000000000000000000000000000000000000..c0a7cc1de847e0bc9ca2f1c3306eb413055701d7
--- /dev/null
+++ b/libglnx/glnx-fdio.h
@@ -0,0 +1,369 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-backport-autocleanups.h>
+#include <gio/gfiledescriptorbased.h>
+#include <limits.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdio.h>
+#include <sys/xattr.h>
+// For dirname(), and previously basename()
+#include <libgen.h>
+
+#include <glnx-macros.h>
+#include <glnx-errors.h>
+
+G_BEGIN_DECLS
+
+/* Irritatingly, g_basename() which is what we want
+ * is deprecated.
+ */
+static inline
+const char *glnx_basename (const char *path)
+{
+  gchar *base = strrchr (path, G_DIR_SEPARATOR);
+
+  if (base)
+    return base + 1;
+
+  return path;
+}
+
+/* Utilities for standard FILE* */
+static inline void
+glnx_stdio_file_cleanup (void *filep)
+{
+  FILE *f = filep;
+  if (f)
+    fclose (f);
+}
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(FILE, glnx_stdio_file_cleanup)
+
+/**
+ * glnx_stdio_file_flush:
+ * Call fflush() and check ferror().
+ */
+gboolean
+glnx_stdio_file_flush (FILE *f, GError **error);
+
+typedef struct {
+  gboolean initialized;
+  gboolean anonymous;
+  int src_dfd;
+  int fd;
+  char *path;
+} GLnxTmpfile;
+void glnx_tmpfile_clear (GLnxTmpfile *tmpf);
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GLnxTmpfile, glnx_tmpfile_clear)
+
+gboolean
+glnx_open_anonymous_tmpfile (int flags,
+                             GLnxTmpfile *out_tmpf,
+                             GError **error);
+
+gboolean
+glnx_open_tmpfile_linkable_at (int dfd,
+                               const char *subpath,
+                               int flags,
+                               GLnxTmpfile *out_tmpf,
+                               GError **error);
+
+typedef enum {
+  GLNX_LINK_TMPFILE_REPLACE,
+  GLNX_LINK_TMPFILE_NOREPLACE,
+  GLNX_LINK_TMPFILE_NOREPLACE_IGNORE_EXIST
+} GLnxLinkTmpfileReplaceMode;
+
+gboolean
+glnx_link_tmpfile_at (GLnxTmpfile *tmpf,
+                      GLnxLinkTmpfileReplaceMode flags,
+                      int target_dfd,
+                      const char *target,
+                      GError **error);
+
+gboolean
+glnx_openat_rdonly (int             dfd,
+                    const char     *path,
+                    gboolean        follow,
+                    int            *out_fd,
+                    GError        **error);
+
+GBytes *
+glnx_fd_readall_bytes (int               fd,
+                       GCancellable     *cancellable,
+                       GError          **error);
+
+char *
+glnx_fd_readall_utf8 (int               fd,
+                      gsize            *out_len,
+                      GCancellable     *cancellable,
+                      GError          **error);
+
+char *
+glnx_file_get_contents_utf8_at (int                   dfd,
+                                const char           *subpath,
+                                gsize                *out_len,
+                                GCancellable         *cancellable,
+                                GError              **error);
+
+/**
+ * GLnxFileReplaceFlags:
+ * @GLNX_FILE_REPLACE_DATASYNC_NEW: Call fdatasync() even if the file did not exist
+ * @GLNX_FILE_REPLACE_NODATASYNC: Never call fdatasync()
+ *
+ * Flags controlling file replacement.
+ */
+typedef enum {
+  GLNX_FILE_REPLACE_DATASYNC_NEW = (1 << 0),
+  GLNX_FILE_REPLACE_NODATASYNC = (1 << 1),
+} GLnxFileReplaceFlags;
+
+gboolean
+glnx_file_replace_contents_at (int                   dfd,
+                               const char           *subpath,
+                               const guint8         *buf,
+                               gsize                 len,
+                               GLnxFileReplaceFlags  flags,
+                               GCancellable         *cancellable,
+                               GError              **error);
+
+gboolean
+glnx_file_replace_contents_with_perms_at (int                   dfd,
+                                          const char           *subpath,
+                                          const guint8         *buf,
+                                          gsize                 len,
+                                          mode_t                mode,
+                                          uid_t                 uid,
+                                          gid_t                 gid,
+                                          GLnxFileReplaceFlags  flags,
+                                          GCancellable         *cancellable,
+                                          GError              **error);
+
+char *
+glnx_readlinkat_malloc (int            dfd,
+                        const char    *subpath,
+                        GCancellable  *cancellable,
+                        GError       **error);
+
+int
+glnx_loop_write (int fd, const void *buf, size_t nbytes);
+
+int
+glnx_regfile_copy_bytes (int fdf, int fdt, off_t max_bytes);
+
+typedef enum {
+  GLNX_FILE_COPY_OVERWRITE = (1 << 0),
+  GLNX_FILE_COPY_NOXATTRS = (1 << 1),
+  GLNX_FILE_COPY_DATASYNC = (1 << 2)
+} GLnxFileCopyFlags;
+
+gboolean
+glnx_file_copy_at (int                   src_dfd,
+                   const char           *src_subpath,
+                   struct stat          *src_stbuf,
+                   int                   dest_dfd,
+                   const char           *dest_subpath,
+                   GLnxFileCopyFlags     copyflags,
+                   GCancellable         *cancellable,
+                   GError              **error);
+
+int glnx_renameat2_noreplace (int olddirfd, const char *oldpath,
+                              int newdirfd, const char *newpath);
+int glnx_renameat2_exchange (int olddirfd, const char *oldpath,
+                             int newdirfd, const char *newpath);
+
+/**
+ * glnx_try_fallocate:
+ * @fd: File descriptor
+ * @size: Size
+ * @error: Error
+ *
+ * Wrapper for Linux fallocate().  Explicitly ignores a @size of zero.
+ * Also, will silently do nothing if the underlying filesystem doesn't
+ * support it.  Use this instead of posix_fallocate(), since the glibc fallback
+ * is bad: https://sourceware.org/bugzilla/show_bug.cgi?id=18515
+ */
+static inline gboolean
+glnx_try_fallocate (int      fd,
+                    off_t    offset,
+                    off_t    size,
+                    GError **error)
+{
+  /* This is just nicer than throwing an error */
+  if (size == 0)
+    return TRUE;
+
+  if (fallocate (fd, 0, offset, size) < 0)
+    {
+      if (G_IN_SET(errno, ENOSYS, EOPNOTSUPP))
+        ; /* Ignore */
+      else
+        return glnx_throw_errno_prefix (error, "fallocate");
+    }
+
+  return TRUE;
+}
+
+/**
+ * glnx_fstat:
+ * @fd: FD to stat
+ * @buf: (out caller-allocates): Return location for stat details
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Wrapper around fstat() which adds #GError support and ensures that it retries
+ * on %EINTR.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ * Since: UNRELEASED
+ */
+static inline gboolean
+glnx_fstat (int           fd,
+            struct stat  *buf,
+            GError      **error)
+{
+  if (TEMP_FAILURE_RETRY (fstat (fd, buf)) != 0)
+    return glnx_throw_errno_prefix (error, "fstat");
+  return TRUE;
+}
+
+/**
+ * glnx_fchmod:
+ * @fd: FD
+ * @mode: Mode
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Wrapper around fchmod() which adds #GError support and ensures that it
+ * retries on %EINTR.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ * Since: UNRELEASED
+ */
+static inline gboolean
+glnx_fchmod (int           fd,
+             mode_t        mode,
+             GError      **error)
+{
+  if (TEMP_FAILURE_RETRY (fchmod (fd, mode)) != 0)
+    return glnx_throw_errno_prefix (error, "fchmod");
+  return TRUE;
+}
+
+/**
+ * glnx_fstatat:
+ * @dfd: Directory FD to stat beneath
+ * @path: Path to stat beneath @dfd
+ * @buf: (out caller-allocates): Return location for stat details
+ * @flags: Flags to pass to fstatat()
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Wrapper around fstatat() which adds #GError support and ensures that it
+ * retries on %EINTR.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ * Since: UNRELEASED
+ */
+static inline gboolean
+glnx_fstatat (int           dfd,
+              const gchar  *path,
+              struct stat  *buf,
+              int           flags,
+              GError      **error)
+{
+  if (TEMP_FAILURE_RETRY (fstatat (dfd, path, buf, flags)) != 0)
+    return glnx_throw_errno_prefix (error, "fstatat(%s)", path);
+  return TRUE;
+}
+
+/**
+ * glnx_fstatat_allow_noent:
+ * @dfd: Directory FD to stat beneath
+ * @path: Path to stat beneath @dfd
+ * @buf: (out caller-allocates) (allow-none): Return location for stat details
+ * @flags: Flags to pass to fstatat()
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Like glnx_fstatat(), but handles `ENOENT` in a non-error way.  Instead,
+ * on success `errno` will be zero, otherwise it will be preserved.  Hence
+ * you can test `if (errno == 0)` to conditionalize on the file existing,
+ * or `if (errno == ENOENT)` for non-existence.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise (errno is preserved)
+ * Since: UNRELEASED
+ */
+static inline gboolean
+glnx_fstatat_allow_noent (int               dfd,
+                          const char       *path,
+                          struct stat      *out_buf,
+                          int               flags,
+                          GError          **error)
+{
+  G_GNUC_UNUSED struct stat unused_stbuf;
+  if (TEMP_FAILURE_RETRY (fstatat (dfd, path, out_buf ? out_buf : &unused_stbuf, flags)) != 0)
+    {
+      if (errno != ENOENT)
+        return glnx_throw_errno_prefix (error, "fstatat(%s)", path);
+      /* Note we preserve errno as ENOENT */
+    }
+  else
+    errno = 0;
+  return TRUE;
+}
+
+/**
+ * glnx_renameat:
+ *
+ * Wrapper around renameat() which adds #GError support and ensures that it
+ * retries on %EINTR.
+ */
+static inline gboolean
+glnx_renameat (int           src_dfd,
+               const gchar  *src_path,
+               int           dest_dfd,
+               const gchar  *dest_path,
+               GError      **error)
+{
+  if (TEMP_FAILURE_RETRY (renameat (src_dfd, src_path, dest_dfd, dest_path)) != 0)
+    return glnx_throw_errno_prefix (error, "renameat(%s, %s)", src_path, dest_path);
+  return TRUE;
+}
+
+/**
+ * glnx_unlinkat:
+ *
+ * Wrapper around unlinkat() which adds #GError support and ensures that it
+ * retries on %EINTR.
+ */
+static inline gboolean
+glnx_unlinkat (int           dfd,
+               const gchar  *path,
+               int           flags,
+               GError      **error)
+{
+  if (TEMP_FAILURE_RETRY (unlinkat (dfd, path, flags)) != 0)
+    return glnx_throw_errno_prefix (error, "unlinkat(%s)", path);
+  return TRUE;
+}
+
+G_END_DECLS
diff --git a/libglnx/glnx-local-alloc.c b/libglnx/glnx-local-alloc.c
new file mode 100644
index 0000000000000000000000000000000000000000..692f0de2b9fcbcac8ea669fdc43a0b0991f438ce
--- /dev/null
+++ b/libglnx/glnx-local-alloc.c
@@ -0,0 +1,72 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2012,2015 Colin Walters <walters@verbum.org>
+ *
+ * This library 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 License, 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 "glnx-local-alloc.h"
+
+/**
+ * SECTION:glnxlocalalloc
+ * @title: GLnx local allocation
+ * @short_description: Release local variables automatically when they go out of scope
+ *
+ * These macros leverage the GCC extension __attribute__ ((cleanup))
+ * to allow calling a cleanup function such as g_free() when a
+ * variable goes out of scope.  See <ulink
+ * url="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html">
+ * for more information on the attribute.
+ *
+ * The provided macros make it easy to use the cleanup attribute for
+ * types that come with GLib.  The primary two are #glnx_free and
+ * #glnx_unref_object, which correspond to g_free() and
+ * g_object_unref(), respectively.
+ *
+ * The rationale behind this is that particularly when handling error
+ * paths, it can be very tricky to ensure the right variables are
+ * freed.  With this, one simply applies glnx_unref_object to a
+ * locally-allocated #GFile for example, and it will be automatically
+ * unreferenced when it goes out of scope.
+ *
+ * Note - you should only use these macros for <emphasis>stack
+ * allocated</emphasis> variables.  They don't provide garbage
+ * collection or let you avoid freeing things.  They're simply a
+ * compiler assisted deterministic mechanism for calling a cleanup
+ * function when a stack frame ends.
+ *
+ * <example id="gs-lfree"><title>Calling g_free automatically</title>
+ * <programlisting>
+ *
+ * GFile *
+ * create_file (GError **error)
+ * {
+ *   glnx_free char *random_id = NULL;
+ *
+ *   if (!prepare_file (error))
+ *     return NULL;
+ *
+ *   random_id = alloc_random_id ();
+ *
+ *   return create_file_real (error);
+ *   // Note that random_id is freed here automatically
+ * }
+ * </programlisting>
+ * </example>
+ *
+ */
diff --git a/libglnx/glnx-local-alloc.h b/libglnx/glnx-local-alloc.h
new file mode 100644
index 0000000000000000000000000000000000000000..3be1fa43b02b4a7a383c39c3770fdd8803d012a3
--- /dev/null
+++ b/libglnx/glnx-local-alloc.h
@@ -0,0 +1,91 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2012,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <gio/gio.h>
+#include <errno.h>
+
+G_BEGIN_DECLS
+
+/**
+ * glnx_unref_object:
+ *
+ * Call g_object_unref() on a variable location when it goes out of
+ * scope.  Note that unlike g_object_unref(), the variable may be
+ * %NULL.
+ */
+#define glnx_unref_object __attribute__ ((cleanup(glnx_local_obj_unref)))
+static inline void
+glnx_local_obj_unref (void *v)
+{
+  GObject *o = *(GObject **)v;
+  if (o)
+    g_object_unref (o);
+}
+#define glnx_unref_object __attribute__ ((cleanup(glnx_local_obj_unref)))
+
+static inline int
+glnx_steal_fd (int *fdp)
+{
+  int fd = *fdp;
+  *fdp = -1;
+  return fd;
+}
+
+/**
+ * glnx_close_fd:
+ * @fdp: Pointer to fd
+ *
+ * Effectively `close (glnx_steal_fd (&fd))`.  Also
+ * asserts that `close()` did not raise `EBADF` - encountering
+ * that error is usually a critical bug in the program.
+ */
+static inline void
+glnx_close_fd (int *fdp)
+{
+  int errsv;
+
+  g_assert (fdp);
+
+  int fd = glnx_steal_fd (fdp);
+  if (fd >= 0)
+    {
+      errsv = errno;
+      if (close (fd) < 0)
+        g_assert (errno != EBADF);
+      errno = errsv;
+    }
+}
+
+/**
+ * glnx_fd_close:
+ *
+ * Deprecated in favor of `glnx_autofd`.
+ */
+#define glnx_fd_close __attribute__((cleanup(glnx_close_fd)))
+/**
+ * glnx_autofd:
+ *
+ * Call close() on a variable location when it goes out of scope.
+ */
+#define glnx_autofd __attribute__((cleanup(glnx_close_fd)))
+
+G_END_DECLS
diff --git a/libglnx/glnx-lockfile.c b/libglnx/glnx-lockfile.c
new file mode 100644
index 0000000000000000000000000000000000000000..f1d52dee30ff2ebb2e0fb50d0036a446329c2cc1
--- /dev/null
+++ b/libglnx/glnx-lockfile.c
@@ -0,0 +1,179 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+  Now copied into libglnx:
+    - Use GError
+
+  Copyright 2010 Lennart Poettering
+  Copyright 2015 Colin Walters <walters@verbum.org>
+
+  systemd 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 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "glnx-lockfile.h"
+#include "glnx-errors.h"
+#include "glnx-fdio.h"
+#include "glnx-backport-autocleanups.h"
+#include "glnx-local-alloc.h"
+
+#define newa(t, n) ((t*) alloca(sizeof(t)*(n)))
+
+/**
+ * glnx_make_lock_file:
+ * @dfd: Directory file descriptor (if not `AT_FDCWD`, must have lifetime `>=` @out_lock)
+ * @p: Path
+ * @operation: one of `LOCK_SH`, `LOCK_EX`, `LOCK_UN`, as passed to flock()
+ * @out_lock: (out) (caller allocates): Return location for lock
+ * @error: Error
+ *
+ * Block until a lock file named @p (relative to @dfd) can be created,
+ * using the flags in @operation, returning the lock data in the
+ * caller-allocated location @out_lock.
+ *
+ * This API wraps new-style process locking if available, otherwise
+ * falls back to BSD locks.
+ */
+gboolean
+glnx_make_lock_file(int dfd, const char *p, int operation, GLnxLockFile *out_lock, GError **error) {
+        glnx_autofd int fd = -1;
+        g_autofree char *t = NULL;
+        int r;
+
+        /*
+         * We use UNPOSIX locks if they are available. They have nice
+         * semantics, and are mostly compatible with NFS. However,
+         * they are only available on new kernels. When we detect we
+         * are running on an older kernel, then we fall back to good
+         * old BSD locks. They also have nice semantics, but are
+         * slightly problematic on NFS, where they are upgraded to
+         * POSIX locks, even though locally they are orthogonal to
+         * POSIX locks.
+         */
+
+        t = g_strdup(p);
+
+        for (;;) {
+#ifdef F_OFD_SETLK
+                struct flock fl = {
+                        .l_type = (operation & ~LOCK_NB) == LOCK_EX ? F_WRLCK : F_RDLCK,
+                        .l_whence = SEEK_SET,
+                };
+#endif
+                struct stat st;
+
+                fd = openat(dfd, p, O_CREAT|O_RDWR|O_NOFOLLOW|O_CLOEXEC|O_NOCTTY, 0600);
+                if (fd < 0)
+                        return glnx_throw_errno(error);
+
+                /* Unfortunately, new locks are not in RHEL 7.1 glibc */
+#ifdef F_OFD_SETLK
+                r = fcntl(fd, (operation & LOCK_NB) ? F_OFD_SETLK : F_OFD_SETLKW, &fl);
+#else
+                r = -1;
+                errno = EINVAL;
+#endif
+                if (r < 0) {
+
+                        /* If the kernel is too old, use good old BSD locks */
+                        if (errno == EINVAL)
+                                r = flock(fd, operation);
+
+                        if (r < 0)
+                                return glnx_throw_errno_prefix (error, "flock");
+                }
+
+                /* If we acquired the lock, let's check if the file
+                 * still exists in the file system. If not, then the
+                 * previous exclusive owner removed it and then closed
+                 * it. In such a case our acquired lock is worthless,
+                 * hence try again. */
+
+                if (!glnx_fstat (fd, &st, error))
+                        return FALSE;
+                if (st.st_nlink > 0)
+                        break;
+
+                glnx_close_fd (&fd);
+        }
+
+        /* Note that if this is not AT_FDCWD, the caller takes responsibility
+         * for the fd's lifetime being >= that of the lock.
+         */
+        out_lock->initialized = TRUE;
+        out_lock->dfd = dfd;
+        out_lock->path = g_steal_pointer (&t);
+        out_lock->fd = glnx_steal_fd (&fd);
+        out_lock->operation = operation;
+        return TRUE;
+}
+
+void glnx_release_lock_file(GLnxLockFile *f) {
+        int r;
+
+        if (!(f && f->initialized))
+                return;
+
+        if (f->path) {
+
+                /* If we are the exclusive owner we can safely delete
+                 * the lock file itself. If we are not the exclusive
+                 * owner, we can try becoming it. */
+
+                if (f->fd >= 0 &&
+                    (f->operation & ~LOCK_NB) == LOCK_SH) {
+#ifdef F_OFD_SETLK
+                        static const struct flock fl = {
+                                .l_type = F_WRLCK,
+                                .l_whence = SEEK_SET,
+                        };
+
+                        r = fcntl(f->fd, F_OFD_SETLK, &fl);
+#else
+                        r = -1;
+                        errno = EINVAL;
+#endif
+                        if (r < 0 && errno == EINVAL)
+                                r = flock(f->fd, LOCK_EX|LOCK_NB);
+
+                        if (r >= 0)
+                                f->operation = LOCK_EX|LOCK_NB;
+                }
+
+                if ((f->operation & ~LOCK_NB) == LOCK_EX) {
+                        (void) unlinkat(f->dfd, f->path, 0);
+                }
+
+                g_free(f->path);
+                f->path = NULL;
+        }
+
+        glnx_close_fd (&f->fd);
+        f->operation = 0;
+        f->initialized = FALSE;
+}
diff --git a/libglnx/glnx-lockfile.h b/libglnx/glnx-lockfile.h
new file mode 100644
index 0000000000000000000000000000000000000000..b346508942c829fc3f5d61a30d82c9dbc266bf6d
--- /dev/null
+++ b/libglnx/glnx-lockfile.h
@@ -0,0 +1,40 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2011 Lennart Poettering
+  Copyright 2015 Colin Walters <walters@verbum.org>
+
+  systemd 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 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "config.h"
+
+#include "glnx-backport-autoptr.h"
+
+typedef struct GLnxLockFile {
+        gboolean initialized;
+        int dfd;
+        char *path;
+        int fd;
+        int operation;
+} GLnxLockFile;
+
+gboolean glnx_make_lock_file(int dfd, const char *p, int operation, GLnxLockFile *ret, GError **error);
+void glnx_release_lock_file(GLnxLockFile *f);
+
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(GLnxLockFile, glnx_release_lock_file)
diff --git a/libglnx/glnx-macros.h b/libglnx/glnx-macros.h
new file mode 100644
index 0000000000000000000000000000000000000000..6d8aca93f8a36b49e378c59bc374e169e0991c71
--- /dev/null
+++ b/libglnx/glnx-macros.h
@@ -0,0 +1,189 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2017 Colin Walters <walters@verbum.org>
+ * With original source from systemd:
+ * Copyright 2010 Lennart Poettering
+ *
+ * This library 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 License, 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 <stdlib.h>
+#include <string.h>
+#include <gio/gio.h>
+
+G_BEGIN_DECLS
+
+/* All of these are for C only. */
+#ifndef __GI_SCANNER__
+
+/* Taken from https://github.com/systemd/systemd/src/basic/string-util.h
+ * at revision v228-666-gcf6c8c4
+ */
+#define glnx_strjoina(a, ...)                                           \
+        ({                                                              \
+                const char *_appendees_[] = { a, __VA_ARGS__ };         \
+                char *_d_, *_p_;                                        \
+                size_t _len_ = 0;                                       \
+                unsigned _i_;                                           \
+                for (_i_ = 0; _i_ < G_N_ELEMENTS(_appendees_) && _appendees_[_i_]; _i_++) \
+                        _len_ += strlen(_appendees_[_i_]);              \
+                _p_ = _d_ = alloca(_len_ + 1);                          \
+                for (_i_ = 0; _i_ < G_N_ELEMENTS(_appendees_) && _appendees_[_i_]; _i_++) \
+                        _p_ = stpcpy(_p_, _appendees_[_i_]);            \
+                *_p_ = 0;                                               \
+                _d_;                                                    \
+        })
+
+#ifndef G_IN_SET
+
+/* Infrastructure for `G_IN_SET`; this code is copied from
+ * systemd's macro.h - please treat that version as canonical
+ * and submit patches first to systemd.
+ */
+#define _G_INSET_CASE_F(X) case X:
+#define _G_INSET_CASE_F_1(CASE, X) _G_INSET_CASE_F(X)
+#define _G_INSET_CASE_F_2(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_1(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_3(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_2(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_4(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_3(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_5(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_4(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_6(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_5(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_7(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_6(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_8(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_7(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_9(CASE, X, ...)  CASE(X) _G_INSET_CASE_F_8(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_10(CASE, X, ...) CASE(X) _G_INSET_CASE_F_9(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_11(CASE, X, ...) CASE(X) _G_INSET_CASE_F_10(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_12(CASE, X, ...) CASE(X) _G_INSET_CASE_F_11(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_13(CASE, X, ...) CASE(X) _G_INSET_CASE_F_12(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_14(CASE, X, ...) CASE(X) _G_INSET_CASE_F_13(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_15(CASE, X, ...) CASE(X) _G_INSET_CASE_F_14(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_16(CASE, X, ...) CASE(X) _G_INSET_CASE_F_15(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_17(CASE, X, ...) CASE(X) _G_INSET_CASE_F_16(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_18(CASE, X, ...) CASE(X) _G_INSET_CASE_F_17(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_19(CASE, X, ...) CASE(X) _G_INSET_CASE_F_18(CASE, __VA_ARGS__)
+#define _G_INSET_CASE_F_20(CASE, X, ...) CASE(X) _G_INSET_CASE_F_19(CASE, __VA_ARGS__)
+
+#define _G_INSET_GET_CASE_F(_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,_11,_12,_13,_14,_15,_16,_17,_18,_19,_20,NAME,...) NAME
+#define _G_INSET_FOR_EACH_MAKE_CASE(...) \
+  _G_INSET_GET_CASE_F(__VA_ARGS__,_G_INSET_CASE_F_20,_G_INSET_CASE_F_19,_G_INSET_CASE_F_18,_G_INSET_CASE_F_17,_G_INSET_CASE_F_16,_G_INSET_CASE_F_15,_G_INSET_CASE_F_14,_G_INSET_CASE_F_13,_G_INSET_CASE_F_12,_G_INSET_CASE_F_11, \
+                               _G_INSET_CASE_F_10,_G_INSET_CASE_F_9,_G_INSET_CASE_F_8,_G_INSET_CASE_F_7,_G_INSET_CASE_F_6,_G_INSET_CASE_F_5,_G_INSET_CASE_F_4,_G_INSET_CASE_F_3,_G_INSET_CASE_F_2,_G_INSET_CASE_F_1) \
+                   (_G_INSET_CASE_F,__VA_ARGS__)
+
+/* Note: claiming the name here even though it isn't upstream yet
+ * https://bugzilla.gnome.org/show_bug.cgi?id=783751
+ */
+/**
+ * G_IN_SET:
+ * @x: Integer (or smaller) sized value
+ * @...: Elements to compare
+ *
+ * It's quite common to test whether or not `char` values or Unix @errno (among) others
+ * are members of a small set.  Normally one has to choose to either use `if (x == val || x == otherval ...)`
+ * or a `switch` statement.  This macro is useful to reduce duplication in the first case,
+ * where one can write simply `if (G_IN_SET (x, val, otherval))`, and avoid the verbosity
+ * that the `switch` statement requires.
+ */
+#define G_IN_SET(x, ...)                          \
+        ({                                      \
+                gboolean _g_inset_found = FALSE;            \
+                /* If the build breaks in the line below, you need to extend the case macros */ \
+                static G_GNUC_UNUSED char _static_assert__macros_need_to_be_extended[20 - sizeof((int[]){__VA_ARGS__})/sizeof(int)]; \
+                switch(x) {                     \
+                _G_INSET_FOR_EACH_MAKE_CASE(__VA_ARGS__) \
+                        _g_inset_found = TRUE;          \
+                        break;                  \
+                default:                        \
+                        break;                  \
+                }                               \
+                _g_inset_found;                 \
+        })
+
+#endif /* ifndef G_IN_SET */
+
+#define _GLNX_CONCAT(a, b)  a##b
+#define _GLNX_CONCAT_INDIRECT(a, b) _GLNX_CONCAT(a, b)
+#define _GLNX_MAKE_ANONYMOUS(a) _GLNX_CONCAT_INDIRECT(a, __COUNTER__)
+
+#define _GLNX_HASH_TABLE_FOREACH_IMPL_KV(guard, ht, it, kt, k, vt, v)          \
+    gboolean guard = TRUE;                                                     \
+    G_STATIC_ASSERT (sizeof (kt) == sizeof (void*));                           \
+    G_STATIC_ASSERT (sizeof (vt) == sizeof (void*));                           \
+    for (GHashTableIter it;                                                    \
+         guard && ({ g_hash_table_iter_init (&it, ht), TRUE; });               \
+         guard = FALSE)                                                        \
+            for (kt k; guard; guard = FALSE)                                   \
+                for (vt v; g_hash_table_iter_next (&it, (gpointer)&k, (gpointer)&v);)
+
+
+/* Cleaner method to iterate over a GHashTable. I.e. rather than
+ *
+ *   gpointer k, v;
+ *   GHashTableIter it;
+ *   g_hash_table_iter_init (&it, table);
+ *   while (g_hash_table_iter_next (&it, &k, &v))
+ *     {
+ *       const char *str = k;
+ *       GPtrArray *arr = v;
+ *       ...
+ *     }
+ *
+ * you can simply do
+ *
+ *   GLNX_HASH_TABLE_FOREACH_IT (table, it, const char*, str, GPtrArray*, arr)
+ *     {
+ *       ...
+ *     }
+ *
+ * All variables are scoped within the loop. You may use the `it` variable as
+ * usual, e.g. to remove an element using g_hash_table_iter_remove(&it). There
+ * are shorter variants for the more common cases where you do not need access
+ * to the iterator or to keys/values:
+ *
+ *   GLNX_HASH_TABLE_FOREACH (table, const char*, str) { ... }
+ *   GLNX_HASH_TABLE_FOREACH_V (table, MyData*, data) { ... }
+ *   GLNX_HASH_TABLE_FOREACH_KV (table, const char*, str, MyData*, data) { ... }
+ *
+ */
+#define GLNX_HASH_TABLE_FOREACH_IT(ht, it, kt, k, vt, v) \
+    _GLNX_HASH_TABLE_FOREACH_IMPL_KV( \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_guard_), ht, it, kt, k, vt, v)
+
+/* Variant of GLNX_HASH_TABLE_FOREACH without having to specify an iterator. An
+ * anonymous iterator will be created. */
+#define GLNX_HASH_TABLE_FOREACH_KV(ht, kt, k, vt, v) \
+    _GLNX_HASH_TABLE_FOREACH_IMPL_KV( \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_guard_), ht, \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_it_), kt, k, vt, v)
+
+/* Variant of GLNX_HASH_TABLE_FOREACH_KV which omits unpacking keys. */
+#define GLNX_HASH_TABLE_FOREACH_V(ht, vt, v) \
+    _GLNX_HASH_TABLE_FOREACH_IMPL_KV( \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_guard_), ht, \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_it_), \
+         gpointer, _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_v_), \
+         vt, v)
+
+/* Variant of GLNX_HASH_TABLE_FOREACH_KV which omits unpacking vals. */
+#define GLNX_HASH_TABLE_FOREACH(ht, kt, k) \
+    _GLNX_HASH_TABLE_FOREACH_IMPL_KV( \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_guard_), ht, \
+         _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_it_), kt, k, \
+         gpointer, _GLNX_MAKE_ANONYMOUS(_glnx_ht_iter_v_))
+
+#endif /* GI_SCANNER */
+
+G_END_DECLS
diff --git a/libglnx/glnx-missing-syscall.h b/libglnx/glnx-missing-syscall.h
new file mode 100644
index 0000000000000000000000000000000000000000..4876ca3967102855fe24e12fc177c37dc743c3c7
--- /dev/null
+++ b/libglnx/glnx-missing-syscall.h
@@ -0,0 +1,156 @@
+/***
+  This file was originally part of systemd.
+
+  Copyright 2010 Lennart Poettering
+  Copyright 2016 Zbigniew Jędrzejewski-Szmek
+
+  systemd 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 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+/* Missing glibc definitions to access certain kernel APIs.
+   This file is last updated from systemd git:
+
+   commit 71e5200f94b22589922704aa4abdf95d4fe2e528
+   Author:     Daniel Mack <daniel@zonque.org>
+   AuthorDate: Tue Oct 18 17:57:10 2016 +0200
+   Commit:     Lennart Poettering <lennart@poettering.net>
+   CommitDate: Fri Sep 22 15:24:54 2017 +0200
+
+   Add abstraction model for BPF programs
+*/
+
+#include "config.h"
+
+#if !HAVE_DECL_RENAMEAT2
+#  ifndef __NR_renameat2
+#    if defined __x86_64__
+#      define __NR_renameat2 316
+#    elif defined __arm__
+#      define __NR_renameat2 382
+#    elif defined __aarch64__
+#      define __NR_renameat2 276
+#    elif defined _MIPS_SIM
+#      if _MIPS_SIM == _MIPS_SIM_ABI32
+#        define __NR_renameat2 4351
+#      endif
+#      if _MIPS_SIM == _MIPS_SIM_NABI32
+#        define __NR_renameat2 6315
+#      endif
+#      if _MIPS_SIM == _MIPS_SIM_ABI64
+#        define __NR_renameat2 5311
+#      endif
+#    elif defined __i386__
+#      define __NR_renameat2 353
+#    elif defined __powerpc64__
+#      define __NR_renameat2 357
+#    elif defined __s390__ || defined __s390x__
+#      define __NR_renameat2 347
+#    elif defined __arc__
+#      define __NR_renameat2 276
+#    else
+#      warning "__NR_renameat2 unknown for your architecture"
+#    endif
+#  endif
+
+static inline int renameat2(int oldfd, const char *oldname, int newfd, const char *newname, unsigned flags) {
+#  ifdef __NR_renameat2
+        return syscall(__NR_renameat2, oldfd, oldname, newfd, newname, flags);
+#  else
+        errno = ENOSYS;
+        return -1;
+#  endif
+}
+#endif
+
+#if !HAVE_DECL_MEMFD_CREATE
+#  ifndef __NR_memfd_create
+#    if defined __x86_64__
+#      define __NR_memfd_create 319
+#    elif defined __arm__
+#      define __NR_memfd_create 385
+#    elif defined __aarch64__
+#      define __NR_memfd_create 279
+#    elif defined __s390__
+#      define __NR_memfd_create 350
+#    elif defined _MIPS_SIM
+#      if _MIPS_SIM == _MIPS_SIM_ABI32
+#        define __NR_memfd_create 4354
+#      endif
+#      if _MIPS_SIM == _MIPS_SIM_NABI32
+#        define __NR_memfd_create 6318
+#      endif
+#      if _MIPS_SIM == _MIPS_SIM_ABI64
+#        define __NR_memfd_create 5314
+#      endif
+#    elif defined __i386__
+#      define __NR_memfd_create 356
+#    elif defined __arc__
+#      define __NR_memfd_create 279
+#    else
+#      warning "__NR_memfd_create unknown for your architecture"
+#    endif
+#  endif
+
+static inline int memfd_create(const char *name, unsigned int flags) {
+#  ifdef __NR_memfd_create
+        return syscall(__NR_memfd_create, name, flags);
+#  else
+        errno = ENOSYS;
+        return -1;
+#  endif
+}
+#endif
+
+/* Copied from systemd git:
+   commit 6bda23dd6aaba50cf8e3e6024248cf736cc443ca
+   Author:     Yu Watanabe <watanabe.yu+github@gmail.com>
+   AuthorDate: Thu Jul 27 20:22:54 2017 +0900
+   Commit:     Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
+   CommitDate: Thu Jul 27 07:22:54 2017 -0400
+*/
+#if !HAVE_DECL_COPY_FILE_RANGE
+#  ifndef __NR_copy_file_range
+#    if defined(__x86_64__)
+#      define __NR_copy_file_range 326
+#    elif defined(__i386__)
+#      define __NR_copy_file_range 377
+#    elif defined __s390__
+#      define __NR_copy_file_range 375
+#    elif defined __arm__
+#      define __NR_copy_file_range 391
+#    elif defined __aarch64__
+#      define __NR_copy_file_range 285
+#    elif defined __powerpc__
+#      define __NR_copy_file_range 379
+#    elif defined __arc__
+#      define __NR_copy_file_range 285
+#    else
+#      warning "__NR_copy_file_range not defined for your architecture"
+#    endif
+#  endif
+
+static inline ssize_t missing_copy_file_range(int fd_in, loff_t *off_in,
+                                              int fd_out, loff_t *off_out,
+                                              size_t len,
+                                              unsigned int flags) {
+#  ifdef __NR_copy_file_range
+        return syscall(__NR_copy_file_range, fd_in, off_in, fd_out, off_out, len, flags);
+#  else
+        errno = ENOSYS;
+        return -1;
+#  endif
+}
+
+#  define copy_file_range missing_copy_file_range
+#endif
diff --git a/libglnx/glnx-missing.h b/libglnx/glnx-missing.h
new file mode 100644
index 0000000000000000000000000000000000000000..0eba07bfd1a2d588d11c9e54d2590aca96cd85ba
--- /dev/null
+++ b/libglnx/glnx-missing.h
@@ -0,0 +1,95 @@
+#pragma once
+
+/***
+  This file was originally part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd 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 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+/* Missing glibc definitions to access certain kernel APIs.
+   This file is last updated from systemd git:
+
+   commit 71e5200f94b22589922704aa4abdf95d4fe2e528
+   Author:     Daniel Mack <daniel@zonque.org>
+   AuthorDate: Tue Oct 18 17:57:10 2016 +0200
+   Commit:     Lennart Poettering <lennart@poettering.net>
+   CommitDate: Fri Sep 22 15:24:54 2017 +0200
+
+   Add abstraction model for BPF programs
+*/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <uchar.h>
+#include <unistd.h>
+
+/* The precise definition of __O_TMPFILE is arch specific; use the
+ * values defined by the kernel (note: some are hexa, some are octal,
+ * duplicated as-is from the kernel definitions):
+ * - alpha, parisc, sparc: each has a specific value;
+ * - others: they use the "generic" value.
+ */
+
+#ifndef __O_TMPFILE
+#if defined(__alpha__)
+#define __O_TMPFILE     0100000000
+#elif defined(__parisc__) || defined(__hppa__)
+#define __O_TMPFILE     0400000000
+#elif defined(__sparc__) || defined(__sparc64__)
+#define __O_TMPFILE     0x2000000
+#else
+#define __O_TMPFILE     020000000
+#endif
+#endif
+
+/* a horrid kludge trying to make sure that this will fail on old kernels */
+#ifndef O_TMPFILE
+#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
+#endif
+
+#ifndef RENAME_NOREPLACE
+#define RENAME_NOREPLACE (1 << 0)
+#endif
+#ifndef RENAME_EXCHANGE
+#define RENAME_EXCHANGE (1 << 1)
+#endif
+
+#ifndef F_LINUX_SPECIFIC_BASE
+#define F_LINUX_SPECIFIC_BASE 1024
+#endif
+
+#ifndef F_ADD_SEALS
+#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
+#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
+
+#define F_SEAL_SEAL     0x0001  /* prevent further seals from being set */
+#define F_SEAL_SHRINK   0x0002  /* prevent file from shrinking */
+#define F_SEAL_GROW     0x0004  /* prevent file from growing */
+#define F_SEAL_WRITE    0x0008  /* prevent writes */
+#endif
+
+#ifndef MFD_ALLOW_SEALING
+#define MFD_ALLOW_SEALING 0x0002U
+#endif
+
+#ifndef MFD_CLOEXEC
+#define MFD_CLOEXEC 0x0001U
+#endif
+
+#include "glnx-missing-syscall.h"
diff --git a/libglnx/glnx-shutil.c b/libglnx/glnx-shutil.c
new file mode 100644
index 0000000000000000000000000000000000000000..78042fe0ed0d5e1f0037720bed57fc6a1ac9e606
--- /dev/null
+++ b/libglnx/glnx-shutil.c
@@ -0,0 +1,268 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-shutil.h>
+#include <glnx-errors.h>
+#include <glnx-fdio.h>
+#include <glnx-local-alloc.h>
+
+static gboolean
+unlinkat_allow_noent (int dfd,
+                      const char *path,
+                      int flags,
+                      GError **error)
+{
+  if (unlinkat (dfd, path, flags) == -1)
+    {
+      if (errno != ENOENT)
+        return glnx_throw_errno_prefix (error, "unlinkat(%s)", path);
+    }
+  return TRUE;
+}
+
+static gboolean
+glnx_shutil_rm_rf_children (GLnxDirFdIterator    *dfd_iter,
+                            GCancellable       *cancellable,
+                            GError            **error)
+{
+  struct dirent *dent;
+
+  while (TRUE)
+    {
+      if (!glnx_dirfd_iterator_next_dent_ensure_dtype (dfd_iter, &dent, cancellable, error))
+        return FALSE;
+      if (dent == NULL)
+        break;
+
+      if (dent->d_type == DT_DIR)
+        {
+          g_auto(GLnxDirFdIterator) child_dfd_iter = { 0, };
+
+          if (!glnx_dirfd_iterator_init_at (dfd_iter->fd, dent->d_name, FALSE,
+                                            &child_dfd_iter, error))
+            return FALSE;
+
+          if (!glnx_shutil_rm_rf_children (&child_dfd_iter, cancellable, error))
+            return FALSE;
+
+          if (!glnx_unlinkat (dfd_iter->fd, dent->d_name, AT_REMOVEDIR, error))
+            return FALSE;
+        }
+      else
+        {
+          if (!unlinkat_allow_noent (dfd_iter->fd, dent->d_name, 0, error))
+            return FALSE;
+        }
+    }
+
+  return TRUE;
+}
+
+/**
+ * glnx_shutil_rm_rf_at:
+ * @dfd: A directory file descriptor, or `AT_FDCWD` or `-1` for current
+ * @path: Path
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Recursively delete the filename referenced by the combination of
+ * the directory fd @dfd and @path; it may be a file or directory.  No
+ * error is thrown if @path does not exist.
+ */
+gboolean
+glnx_shutil_rm_rf_at (int                   dfd,
+                      const char           *path,
+                      GCancellable         *cancellable,
+                      GError              **error)
+{
+  dfd = glnx_dirfd_canonicalize (dfd);
+
+  /* With O_NOFOLLOW first */
+  glnx_autofd int target_dfd =
+    openat (dfd, path, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW);
+
+  if (target_dfd == -1)
+    {
+      int errsv = errno;
+      if (errsv == ENOENT)
+        {
+          ;
+        }
+      else if (errsv == ENOTDIR || errsv == ELOOP)
+        {
+          if (!glnx_unlinkat (dfd, path, 0, error))
+            return FALSE;
+        }
+      else
+        return glnx_throw_errno_prefix (error, "open(%s)", path);
+    }
+  else
+    {
+      g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
+      if (!glnx_dirfd_iterator_init_take_fd (&target_dfd, &dfd_iter, error))
+        return FALSE;
+
+      if (!glnx_shutil_rm_rf_children (&dfd_iter, cancellable, error))
+        return glnx_prefix_error (error, "Removing %s", path);
+
+      if (!unlinkat_allow_noent (dfd, path, AT_REMOVEDIR, error))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+mkdir_p_at_internal (int              dfd,
+                     char            *path,
+                     int              mode,
+                     GCancellable    *cancellable,
+                     GError         **error)
+{
+  gboolean did_recurse = FALSE;
+
+  if (g_cancellable_set_error_if_cancelled (cancellable, error))
+    return FALSE;
+
+ again:
+  if (mkdirat (dfd, path, mode) == -1)
+    {
+      if (errno == ENOENT)
+        {
+          char *lastslash;
+
+          g_assert (!did_recurse);
+
+          lastslash = strrchr (path, '/');
+          if (lastslash == NULL)
+            {
+              /* This can happen if @dfd was deleted between being opened and
+               * passed to mkdir_p_at_internal(). */
+              return glnx_throw_errno_prefix (error, "mkdir(%s)", path);
+            }
+
+          /* Note we can mutate the buffer as we dup'd it */
+          *lastslash = '\0';
+
+          if (!glnx_shutil_mkdir_p_at (dfd, path, mode,
+                                       cancellable, error))
+            return FALSE;
+
+          /* Now restore it for another mkdir attempt */
+          *lastslash = '/';
+
+          did_recurse = TRUE;
+          goto again;
+        }
+      else if (errno == EEXIST)
+        {
+          /* Fall through; it may not have been a directory,
+           * but we'll find that out on the next call up.
+           */
+        }
+      else
+        return glnx_throw_errno_prefix (error, "mkdir(%s)", path);
+    }
+
+  return TRUE;
+}
+
+/**
+ * glnx_shutil_mkdir_p_at:
+ * @dfd: Directory fd
+ * @path: Directory path to be created
+ * @mode: Mode for newly created directories
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Similar to g_mkdir_with_parents(), except operates relative to the
+ * directory fd @dfd.
+ *
+ * See also glnx_ensure_dir() for a non-recursive version.
+ *
+ * This will return %G_IO_ERROR_NOT_FOUND if @dfd has been deleted since being
+ * opened. It may return other errors from mkdirat() in other situations.
+ */
+gboolean
+glnx_shutil_mkdir_p_at (int                   dfd,
+                        const char           *path,
+                        int                   mode,
+                        GCancellable         *cancellable,
+                        GError              **error)
+{
+  struct stat stbuf;
+  char *buf;
+
+  /* Fast path stat to see whether it already exists */
+  if (fstatat (dfd, path, &stbuf, AT_SYMLINK_NOFOLLOW) == 0)
+    {
+      /* Note early return */
+      if (S_ISDIR (stbuf.st_mode))
+        return TRUE;
+    }
+
+  buf = strdupa (path);
+
+  if (!mkdir_p_at_internal (dfd, buf, mode, cancellable, error))
+    return FALSE;
+
+  return TRUE;
+}
+
+/**
+ * glnx_shutil_mkdir_p_at_open:
+ * @dfd: Directory fd
+ * @path: Directory path to be created
+ * @mode: Mode for newly created directories
+ * @out_dfd: (out caller-allocates): Return location for an FD to @dfd/@path,
+ *    or `-1` on error
+ * @cancellable: (nullable): Cancellable, or %NULL
+ * @error: Return location for a #GError, or %NULL
+ *
+ * Similar to glnx_shutil_mkdir_p_at(), except it opens the resulting directory
+ * and returns a directory FD to it. Currently, this is not guaranteed to be
+ * race-free.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ * Since: UNRELEASED
+ */
+gboolean
+glnx_shutil_mkdir_p_at_open (int            dfd,
+                             const char    *path,
+                             int            mode,
+                             int           *out_dfd,
+                             GCancellable  *cancellable,
+                             GError       **error)
+{
+  /* FIXME: It’s not possible to eliminate the race here until
+   * openat(O_DIRECTORY | O_CREAT) works (and returns a directory rather than a
+   * file). It appears to be not supported in current kernels. (Tested with
+   * 4.10.10-200.fc25.x86_64.) */
+  *out_dfd = -1;
+
+  if (!glnx_shutil_mkdir_p_at (dfd, path, mode, cancellable, error))
+    return FALSE;
+
+  return glnx_opendirat (dfd, path, TRUE, out_dfd, error);
+}
diff --git a/libglnx/glnx-shutil.h b/libglnx/glnx-shutil.h
new file mode 100644
index 0000000000000000000000000000000000000000..56a99fa2c4873fd2ddcc225c520344a527a6b921
--- /dev/null
+++ b/libglnx/glnx-shutil.h
@@ -0,0 +1,48 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-dirfd.h>
+
+G_BEGIN_DECLS
+
+gboolean
+glnx_shutil_rm_rf_at (int                   dfd,
+                      const char           *path,
+                      GCancellable         *cancellable,
+                      GError              **error);
+
+gboolean
+glnx_shutil_mkdir_p_at (int                   dfd,
+                        const char           *path,
+                        int                   mode,
+                        GCancellable         *cancellable,
+                        GError              **error);
+
+gboolean
+glnx_shutil_mkdir_p_at_open (int            dfd,
+                             const char    *path,
+                             int            mode,
+                             int           *out_dfd,
+                             GCancellable  *cancellable,
+                             GError       **error);
+
+G_END_DECLS
diff --git a/libglnx/glnx-xattrs.c b/libglnx/glnx-xattrs.c
new file mode 100644
index 0000000000000000000000000000000000000000..79a14cd372e29b79644abc773baf8234711d1b62
--- /dev/null
+++ b/libglnx/glnx-xattrs.c
@@ -0,0 +1,444 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <stdio.h>
+
+#include <glnx-macros.h>
+#include <glnx-xattrs.h>
+#include <glnx-errors.h>
+#include <glnx-local-alloc.h>
+
+static GVariant *
+variant_new_ay_bytes (GBytes *bytes)
+{
+  gsize size;
+  gconstpointer data;
+  data = g_bytes_get_data (bytes, &size);
+  g_bytes_ref (bytes);
+  return g_variant_new_from_data (G_VARIANT_TYPE ("ay"), data, size,
+                                  TRUE, (GDestroyNotify)g_bytes_unref, bytes);
+}
+
+static char *
+canonicalize_xattrs (char    *xattr_string,
+                     size_t   len)
+{
+  char *p;
+  GSList *xattrs = NULL;
+  GSList *iter;
+  GString *result;
+
+  result = g_string_new (0);
+
+  p = xattr_string;
+  while (p < xattr_string+len)
+    {
+      xattrs = g_slist_prepend (xattrs, p);
+      p += strlen (p) + 1;
+    }
+
+  xattrs = g_slist_sort (xattrs, (GCompareFunc) strcmp);
+  for (iter = xattrs; iter; iter = iter->next) {
+    g_string_append (result, iter->data);
+    g_string_append_c (result, '\0');
+  }
+
+  g_slist_free (xattrs);
+  return g_string_free (result, FALSE);
+}
+
+static gboolean
+read_xattr_name_array (const char *path,
+                       int         fd,
+                       const char *xattrs,
+                       size_t      len,
+                       GVariantBuilder *builder,
+                       GError  **error)
+{
+  gboolean ret = FALSE;
+  const char *p;
+  int r;
+  const char *funcstr;
+
+  g_assert (path != NULL || fd != -1);
+
+  funcstr = fd != -1 ? "fgetxattr" : "lgetxattr";
+
+  for (p = xattrs; p < xattrs+len; p = p + strlen (p) + 1)
+    {
+      ssize_t bytes_read;
+      g_autofree char *buf = NULL;
+      g_autoptr(GBytes) bytes = NULL;
+
+    again:
+      if (fd != -1)
+        bytes_read = fgetxattr (fd, p, NULL, 0);
+      else
+        bytes_read = lgetxattr (path, p, NULL, 0);
+      if (bytes_read < 0)
+        {
+          if (errno == ENODATA)
+            continue;
+
+          glnx_set_prefix_error_from_errno (error, "%s", funcstr);
+          goto out;
+        }
+      if (bytes_read == 0)
+        continue;
+
+      buf = g_malloc (bytes_read);
+      if (fd != -1)
+        r = fgetxattr (fd, p, buf, bytes_read);
+      else
+        r = lgetxattr (path, p, buf, bytes_read);
+      if (r < 0)
+        {
+          if (errno == ERANGE)
+            {
+              g_free (g_steal_pointer (&buf));
+              goto again;
+            }
+          else if (errno == ENODATA)
+            continue;
+
+          glnx_set_prefix_error_from_errno (error, "%s", funcstr);
+          goto out;
+        }
+
+      bytes = g_bytes_new_take (g_steal_pointer (&buf), bytes_read);
+      g_variant_builder_add (builder, "(@ay@ay)",
+                             g_variant_new_bytestring (p),
+                             variant_new_ay_bytes (bytes));
+    }
+
+  ret = TRUE;
+ out:
+  return ret;
+}
+
+static gboolean
+get_xattrs_impl (const char      *path,
+                 int              fd,
+                 GVariant       **out_xattrs,
+                 GCancellable    *cancellable,
+                 GError         **error)
+{
+  gboolean ret = FALSE;
+  ssize_t bytes_read, real_size;
+  g_autofree char *xattr_names = NULL;
+  g_autofree char *xattr_names_canonical = NULL;
+  GVariantBuilder builder;
+  gboolean builder_initialized = FALSE;
+  g_autoptr(GVariant) ret_xattrs = NULL;
+
+  g_assert (path != NULL || fd != -1);
+
+  g_variant_builder_init (&builder, G_VARIANT_TYPE ("a(ayay)"));
+  builder_initialized = TRUE;
+
+ again:
+  if (path)
+    bytes_read = llistxattr (path, NULL, 0);
+  else
+    bytes_read = flistxattr (fd, NULL, 0);
+
+  if (bytes_read < 0)
+    {
+      if (errno != ENOTSUP)
+        {
+          glnx_set_prefix_error_from_errno (error, "%s", "llistxattr");
+          goto out;
+        }
+    }
+  else if (bytes_read > 0)
+    {
+      xattr_names = g_malloc (bytes_read);
+      if (path)
+        real_size = llistxattr (path, xattr_names, bytes_read);
+      else
+        real_size = flistxattr (fd, xattr_names, bytes_read);
+      if (real_size < 0)
+        {
+          if (errno == ERANGE)
+            {
+              g_free (xattr_names);
+              goto again;
+            }
+          glnx_set_prefix_error_from_errno (error, "%s", "llistxattr");
+          goto out;
+        }
+      else if (real_size > 0)
+        {
+          xattr_names_canonical = canonicalize_xattrs (xattr_names, real_size);
+
+          if (!read_xattr_name_array (path, fd, xattr_names_canonical, real_size, &builder, error))
+            goto out;
+        }
+    }
+
+  ret_xattrs = g_variant_builder_end (&builder);
+  builder_initialized = FALSE;
+  g_variant_ref_sink (ret_xattrs);
+  
+  ret = TRUE;
+  if (out_xattrs)
+    *out_xattrs = g_steal_pointer (&ret_xattrs);
+ out:
+  if (!builder_initialized)
+    g_variant_builder_clear (&builder);
+  return ret;
+}
+
+/**
+ * glnx_fd_get_all_xattrs:
+ * @fd: a file descriptor
+ * @out_xattrs: (out): A new #GVariant containing the extended attributes
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Read all extended attributes from @fd in a canonical sorted order, and
+ * set @out_xattrs with the result.
+ *
+ * If the filesystem does not support extended attributes, @out_xattrs
+ * will have 0 elements, and this function will return successfully.
+ */
+gboolean
+glnx_fd_get_all_xattrs (int            fd,
+                        GVariant     **out_xattrs,
+                        GCancellable  *cancellable,
+                        GError       **error)
+{
+  return get_xattrs_impl (NULL, fd, out_xattrs,
+                          cancellable, error);
+}
+
+/**
+ * glnx_dfd_name_get_all_xattrs:
+ * @dfd: Parent directory file descriptor
+ * @name: File name
+ * @out_xattrs: (out): Extended attribute set
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Load all extended attributes for the file named @name residing in
+ * directory @dfd.
+ */
+gboolean
+glnx_dfd_name_get_all_xattrs (int            dfd,
+                              const char    *name,
+                              GVariant     **out_xattrs,
+                              GCancellable  *cancellable,
+                              GError       **error)
+{
+  if (G_IN_SET(dfd, AT_FDCWD, -1))
+    {
+      return get_xattrs_impl (name, -1, out_xattrs, cancellable, error);
+    }
+  else
+    {
+      char buf[PATH_MAX];
+      /* A workaround for the lack of lgetxattrat(), thanks to Florian Weimer:
+       * https://mail.gnome.org/archives/ostree-list/2014-February/msg00017.html
+       */
+      snprintf (buf, sizeof (buf), "/proc/self/fd/%d/%s", dfd, name);
+      return get_xattrs_impl (buf, -1, out_xattrs, cancellable, error);
+    }
+}
+
+static gboolean
+set_all_xattrs_for_path (const char    *path,
+                         GVariant      *xattrs,
+                         GCancellable  *cancellable,
+                         GError       **error)
+{
+  const guint n = g_variant_n_children (xattrs);
+  for (guint i = 0; i < n; i++)
+    {
+      const guint8* name;
+      g_autoptr(GVariant) value = NULL;
+      g_variant_get_child (xattrs, i, "(^&ay@ay)",
+                           &name, &value);
+
+      gsize value_len;
+      const guint8* value_data = g_variant_get_fixed_array (value, &value_len, 1);
+
+      if (lsetxattr (path, (char*)name, (char*)value_data, value_len, 0) < 0)
+        return glnx_throw_errno_prefix (error, "lsetxattr");
+    }
+
+  return TRUE;
+}
+
+/**
+ * glnx_dfd_name_set_all_xattrs:
+ * @dfd: Parent directory file descriptor
+ * @name: File name
+ * @xattrs: Extended attribute set
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Set all extended attributes for the file named @name residing in
+ * directory @dfd.
+ */
+gboolean
+glnx_dfd_name_set_all_xattrs (int            dfd,
+                              const char    *name,
+                              GVariant      *xattrs,
+                              GCancellable  *cancellable,
+                              GError       **error)
+{
+  if (G_IN_SET(dfd, AT_FDCWD, -1))
+    {
+      return set_all_xattrs_for_path (name, xattrs, cancellable, error);
+    }
+  else
+    {
+      char buf[PATH_MAX];
+      /* A workaround for the lack of lsetxattrat(), thanks to Florian Weimer:
+       * https://mail.gnome.org/archives/ostree-list/2014-February/msg00017.html
+       */
+      snprintf (buf, sizeof (buf), "/proc/self/fd/%d/%s", dfd, name);
+      return set_all_xattrs_for_path (buf, xattrs, cancellable, error);
+    }
+}
+
+/**
+ * glnx_fd_set_all_xattrs:
+ * @fd: File descriptor
+ * @xattrs: Extended attributes
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * For each attribute in @xattrs, set its value on the file or
+ * directory referred to by @fd.  This function does not remove any
+ * attributes not in @xattrs.
+ */
+gboolean
+glnx_fd_set_all_xattrs (int            fd,
+                        GVariant      *xattrs,
+                        GCancellable  *cancellable,
+                        GError       **error)
+{
+  const guint n = g_variant_n_children (xattrs);
+  for (guint i = 0; i < n; i++)
+    {
+      const guint8* name;
+      g_autoptr(GVariant) value = NULL;
+      g_variant_get_child (xattrs, i, "(^&ay@ay)",
+                           &name, &value);
+
+      gsize value_len;
+      const guint8* value_data = g_variant_get_fixed_array (value, &value_len, 1);
+
+      if (TEMP_FAILURE_RETRY (fsetxattr (fd, (char*)name, (char*)value_data, value_len, 0)) < 0)
+        return glnx_throw_errno_prefix (error, "fsetxattr");
+    }
+
+  return TRUE;
+}
+
+/**
+ * glnx_lgetxattrat:
+ * @dfd: Directory file descriptor
+ * @subpath: Subpath
+ * @attribute: Extended attribute to retrieve
+ * @error: Error
+ *
+ * Retrieve an extended attribute value, relative to a directory file
+ * descriptor.
+ */
+GBytes *
+glnx_lgetxattrat (int            dfd,
+                  const char    *subpath,
+                  const char    *attribute,
+                  GError       **error)
+{
+  char pathbuf[PATH_MAX];
+  snprintf (pathbuf, sizeof (pathbuf), "/proc/self/fd/%d/%s", dfd, subpath);
+
+  ssize_t bytes_read, real_size;
+  if (TEMP_FAILURE_RETRY (bytes_read = lgetxattr (pathbuf, attribute, NULL, 0)) < 0)
+    return glnx_null_throw_errno_prefix (error, "lgetxattr");
+
+  g_autofree guint8 *buf = g_malloc (bytes_read);
+  if (TEMP_FAILURE_RETRY (real_size = lgetxattr (pathbuf, attribute, buf, bytes_read)) < 0)
+    return glnx_null_throw_errno_prefix (error, "lgetxattr");
+
+  return g_bytes_new_take (g_steal_pointer (&buf), real_size);
+}
+
+/**
+ * glnx_fgetxattr_bytes:
+ * @fd: Directory file descriptor
+ * @attribute: Extended attribute to retrieve
+ * @error: Error
+ *
+ * Returns: (transfer full): An extended attribute value, or %NULL on error
+ */
+GBytes *
+glnx_fgetxattr_bytes (int            fd,
+                      const char    *attribute,
+                      GError       **error)
+{
+  ssize_t bytes_read, real_size;
+
+  if (TEMP_FAILURE_RETRY (bytes_read = fgetxattr (fd, attribute, NULL, 0)) < 0)
+    return glnx_null_throw_errno_prefix (error, "fgetxattr");
+
+  g_autofree guint8 *buf = g_malloc (bytes_read);
+  if (TEMP_FAILURE_RETRY (real_size = fgetxattr (fd, attribute, buf, bytes_read)) < 0)
+    return glnx_null_throw_errno_prefix (error, "fgetxattr");
+
+  return g_bytes_new_take (g_steal_pointer (&buf), real_size);
+}
+
+/**
+ * glnx_lsetxattrat:
+ * @dfd: Directory file descriptor
+ * @subpath: Path
+ * @attribute: An attribute name
+ * @value: (array length=len) (element-type guint8): Attribute value
+ * @len: Length of @value
+ * @flags: Flags, containing either XATTR_CREATE or XATTR_REPLACE
+ * @error: Error
+ *
+ * Set an extended attribute, relative to a directory file descriptor.
+ */
+gboolean
+glnx_lsetxattrat (int            dfd,
+                  const char    *subpath,
+                  const char    *attribute,
+                  const guint8  *value,
+                  gsize          len,
+                  int            flags,
+                  GError       **error)
+{
+  char pathbuf[PATH_MAX];
+  snprintf (pathbuf, sizeof (pathbuf), "/proc/self/fd/%d/%s", dfd, subpath);
+
+  if (TEMP_FAILURE_RETRY (lsetxattr (subpath, attribute, value, len, flags)) < 0)
+    return glnx_throw_errno_prefix (error, "lsetxattr");
+
+  return TRUE;
+}
+
diff --git a/libglnx/glnx-xattrs.h b/libglnx/glnx-xattrs.h
new file mode 100644
index 0000000000000000000000000000000000000000..a566a2249051d1856a1f7b84ed4b6ae699fe8e91
--- /dev/null
+++ b/libglnx/glnx-xattrs.h
@@ -0,0 +1,78 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <glnx-backport-autocleanups.h>
+#include <limits.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/xattr.h>
+
+G_BEGIN_DECLS
+
+gboolean
+glnx_dfd_name_get_all_xattrs (int                    dfd,
+                              const char            *name,
+                              GVariant             **out_xattrs,
+                              GCancellable          *cancellable,
+                              GError               **error);
+
+gboolean
+glnx_fd_get_all_xattrs (int                    fd,
+                        GVariant             **out_xattrs,
+                        GCancellable          *cancellable,
+                        GError               **error);
+
+gboolean
+glnx_dfd_name_set_all_xattrs (int            dfd,
+                              const char    *name,
+                              GVariant      *xattrs,
+                              GCancellable  *cancellable,
+                              GError       **error);
+
+gboolean
+glnx_fd_set_all_xattrs (int            fd,
+                        GVariant      *xattrs,
+                        GCancellable  *cancellable,
+                        GError       **error);
+
+GBytes *
+glnx_lgetxattrat (int            dfd,
+                  const char    *subpath,
+                  const char    *attribute,
+                  GError       **error);
+
+GBytes *
+glnx_fgetxattr_bytes (int            fd,
+                      const char    *attribute,
+                      GError       **error);
+
+gboolean
+glnx_lsetxattrat (int            dfd,
+                  const char    *subpath,
+                  const char    *attribute,
+                  const guint8  *value,
+                  gsize          len,
+                  int            flags,
+                  GError       **error);
+
+G_END_DECLS
diff --git a/libglnx/libglnx.doap b/libglnx/libglnx.doap
new file mode 100644
index 0000000000000000000000000000000000000000..2b38074e1d84c5b5398e093ea40050e9c0fe9da3
--- /dev/null
+++ b/libglnx/libglnx.doap
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Project xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+         xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
+         xmlns:foaf="http://xmlns.com/foaf/0.1/"
+         xmlns:gnome="http://api.gnome.org/doap-extensions#"
+         xmlns="http://usefulinc.com/ns/doap#">
+
+  <name>libglnx</name>
+  <shortname>libglnx</shortname>
+
+  <shortdesc xml:lang="en">"Copylib" for system service modules using GLib with Linux</shortdesc>
+
+  <description xml:lang="en">This module is intended for use by
+  infrastructure code using GLib that is also Linux specific, such as
+  ostree, NetworkManager, and others.
+  </description>
+
+  <license rdf:resource="http://usefulinc.com/doap/licenses/lgpl" />
+  <mailing-list rdf:resource="mailto:desktop-devel-list@gnome.org" />
+
+  <programming-language>C</programming-language>
+
+  <maintainer>
+    <foaf:Person>
+      <foaf:name>Colin Walters</foaf:name>
+      <foaf:mbox rdf:resource="mailto:walters@verbum.org"/>
+      <gnome:userid>walters</gnome:userid>
+    </foaf:Person>
+  </maintainer>
+
+</Project>
diff --git a/libglnx/libglnx.h b/libglnx/libglnx.h
new file mode 100644
index 0000000000000000000000000000000000000000..411d4fa0008d0dc20a9b42421d3e4a5879990f8b
--- /dev/null
+++ b/libglnx/libglnx.h
@@ -0,0 +1,40 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2012,2013,2015 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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 License, 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 <gio/gio.h>
+
+G_BEGIN_DECLS
+
+#include <glnx-macros.h>
+#include <glnx-missing.h>
+#include <glnx-local-alloc.h>
+#include <glnx-backport-autocleanups.h>
+#include <glnx-backports.h>
+#include <glnx-lockfile.h>
+#include <glnx-errors.h>
+#include <glnx-dirfd.h>
+#include <glnx-shutil.h>
+#include <glnx-xattrs.h>
+#include <glnx-console.h>
+#include <glnx-fdio.h>
+
+G_END_DECLS
diff --git a/libglnx/libglnx.m4 b/libglnx/libglnx.m4
new file mode 100644
index 0000000000000000000000000000000000000000..5922805bc7a014812d3da44c8d5b9f3b76a5eb59
--- /dev/null
+++ b/libglnx/libglnx.m4
@@ -0,0 +1,34 @@
+AC_DEFUN([LIBGLNX_CONFIGURE],
+[
+AC_CHECK_DECLS([
+        renameat2,
+        memfd_create,
+        copy_file_range],
+        [], [], [[
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <sys/mount.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <linux/loop.h>
+#include <linux/random.h>
+#include <sys/mman.h>
+]])
+
+AC_ARG_ENABLE(otmpfile,
+              [AS_HELP_STRING([--disable-otmpfile],
+                              [Disable use of O_TMPFILE [default=no]])],,
+              [enable_otmpfile=yes])
+AS_IF([test $enable_otmpfile = yes], [], [
+  AC_DEFINE([DISABLE_OTMPFILE], 1, [Define if we should avoid using O_TMPFILE])])
+
+AC_ARG_ENABLE(wrpseudo-compat,
+              [AS_HELP_STRING([--enable-wrpseudo-compat],
+                              [Disable use syscall() and filesystem calls to for compatibility with wrpseudo [default=no]])],,
+              [enable_wrpseudo_compat=no])
+AS_IF([test $enable_wrpseudo_compat = no], [], [
+  AC_DEFINE([ENABLE_WRPSEUDO_COMPAT], 1, [Define if we should be compatible with wrpseudo])])
+
+dnl end LIBGLNX_CONFIGURE
+])
diff --git a/libglnx/tests/libglnx-testlib.h b/libglnx/tests/libglnx-testlib.h
new file mode 100644
index 0000000000000000000000000000000000000000..ee750e499c0d08eddbe4f189d58a527f98d5ae97
--- /dev/null
+++ b/libglnx/tests/libglnx-testlib.h
@@ -0,0 +1,34 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This library 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 License, 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
+
+typedef GError _GLnxTestAutoError;
+static inline void
+_glnx_test_auto_error_cleanup (_GLnxTestAutoError *autoerror)
+{
+  g_assert_no_error (autoerror);
+  /* We could add a clear call here, but no point...we'll have aborted */
+}
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(_GLnxTestAutoError, _glnx_test_auto_error_cleanup);
+
+#define _GLNX_TEST_DECLARE_ERROR(local_error, error)      \
+  g_autoptr(_GLnxTestAutoError) local_error = NULL; \
+  GError **error = &local_error
diff --git a/libglnx/tests/test-libglnx-errors.c b/libglnx/tests/test-libglnx-errors.c
new file mode 100644
index 0000000000000000000000000000000000000000..4e91e02c6e225ca8e95aaa068076de22185f4962
--- /dev/null
+++ b/libglnx/tests/test-libglnx-errors.c
@@ -0,0 +1,183 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This library 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 License, 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 "libglnx.h"
+#include <glib.h>
+#include <stdlib.h>
+#include <gio/gio.h>
+#include <string.h>
+
+static void
+test_error_throw (void)
+{
+  g_autoptr(GError) error = NULL;
+
+  g_assert (!glnx_throw (&error, "foo: %s %d", "hello", 42));
+  g_assert_error (error, G_IO_ERROR, G_IO_ERROR_FAILED);
+  g_assert_cmpstr (error->message, ==, "foo: hello 42");
+  g_clear_error (&error);
+
+  gpointer dummy = glnx_null_throw (&error, "literal foo");
+  g_assert (dummy == NULL);
+  g_assert_error (error, G_IO_ERROR, G_IO_ERROR_FAILED);
+  g_assert_cmpstr (error->message, ==, "literal foo");
+  g_clear_error (&error);
+
+  gpointer dummy2 = glnx_null_throw (&error, "foo: %s %d", "hola", 24);
+  g_assert (dummy2 == NULL);
+  g_assert_error (error, G_IO_ERROR, G_IO_ERROR_FAILED);
+  g_assert_cmpstr (error->message, ==, "foo: hola 24");
+  g_clear_error (&error);
+}
+
+static void
+test_error_errno (void)
+{
+  g_autoptr(GError) error = NULL;
+  const char noent_path[] = "/enoent-this-should-not-exist";
+  int fd;
+
+  fd = open (noent_path, O_RDONLY);
+  if (fd < 0)
+    {
+      g_assert (!glnx_throw_errno (&error));
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (!glnx_prefix_error (&error, "myprefix"));
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (g_str_has_prefix (error->message, "myprefix: "));
+      g_clear_error (&error);
+    }
+  else
+    g_assert_cmpint (fd, ==, -1);
+
+  fd = open (noent_path, O_RDONLY);
+  if (fd < 0)
+    {
+      gpointer dummy = glnx_null_throw_errno (&error);
+      g_assert (dummy == NULL);
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      dummy = glnx_prefix_error_null (&error, "myprefix");
+      g_assert (dummy == NULL);
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (g_str_has_prefix (error->message, "myprefix: "));
+      g_clear_error (&error);
+    }
+  else
+    g_assert_cmpint (fd, ==, -1);
+
+  fd = open (noent_path, O_RDONLY);
+  if (fd < 0)
+    {
+      g_autofree char *expected_prefix = g_strdup_printf ("Failed to open %s", noent_path);
+      g_assert (!glnx_throw_errno_prefix (&error, "Failed to open %s", noent_path));
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (g_str_has_prefix (error->message, expected_prefix));
+      g_clear_error (&error);
+      /* And test the legacy wrapper */
+      glnx_set_prefix_error_from_errno (&error, "Failed to open %s", noent_path);
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (g_str_has_prefix (error->message, expected_prefix));
+      g_clear_error (&error);
+    }
+  else
+    g_assert_cmpint (fd, ==, -1);
+
+  fd = open (noent_path, O_RDONLY);
+  if (fd < 0)
+    {
+      gpointer dummy = glnx_null_throw_errno_prefix (&error, "Failed to open file");
+      g_assert (dummy == NULL);
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (g_str_has_prefix (error->message, "Failed to open file"));
+      g_clear_error (&error);
+    }
+  else
+    g_assert_cmpint (fd, ==, -1);
+
+  fd = open (noent_path, O_RDONLY);
+  if (fd < 0)
+    {
+      gpointer dummy = glnx_null_throw_errno_prefix (&error, "Failed to open %s", noent_path);
+      g_assert (dummy == NULL);
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+      g_assert (g_str_has_prefix (error->message, glnx_strjoina ("Failed to open ", noent_path)));
+      g_clear_error (&error);
+    }
+  else
+    g_assert_cmpint (fd, ==, -1);
+}
+
+static void
+test_error_auto_nothrow (GError **error)
+{
+  GLNX_AUTO_PREFIX_ERROR("foo", error);
+  /* Side effect to avoid otherwise empty function */
+  g_assert_no_error (*error);
+}
+
+static void
+test_error_auto_throw (GError **error)
+{
+  GLNX_AUTO_PREFIX_ERROR("foo", error);
+  (void) glnx_throw (error, "oops");
+}
+
+static void
+test_error_auto_throw_recurse (GError **error)
+{
+  GLNX_AUTO_PREFIX_ERROR("foo", error);
+
+  if (TRUE)
+    {
+      GLNX_AUTO_PREFIX_ERROR("bar", error);
+      (void) glnx_throw (error, "oops");
+    }
+}
+
+static void
+test_error_auto (void)
+{
+  g_autoptr(GError) error = NULL;
+  test_error_auto_nothrow (&error);
+  g_assert_no_error (error);
+  test_error_auto_throw (&error);
+  g_assert_nonnull (error);
+  g_assert_cmpstr (error->message, ==, "foo: oops");
+  g_clear_error (&error);
+  test_error_auto_throw_recurse (&error);
+  g_assert_nonnull (error);
+  g_assert_cmpstr (error->message, ==, "foo: bar: oops");
+}
+
+int main (int argc, char **argv)
+{
+  int ret;
+
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/error-throw", test_error_throw);
+  g_test_add_func ("/error-errno", test_error_errno);
+  g_test_add_func ("/error-auto", test_error_auto);
+
+  ret = g_test_run();
+
+  return ret;
+}
diff --git a/libglnx/tests/test-libglnx-fdio.c b/libglnx/tests/test-libglnx-fdio.c
new file mode 100644
index 0000000000000000000000000000000000000000..81636e59cb74ee91056eb15a3c41c99ff54c624b
--- /dev/null
+++ b/libglnx/tests/test-libglnx-fdio.c
@@ -0,0 +1,254 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This library 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 License, 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 "libglnx.h"
+#include <glib.h>
+#include <stdlib.h>
+#include <gio/gio.h>
+#include <err.h>
+#include <string.h>
+
+#include "libglnx-testlib.h"
+
+static gboolean
+renameat_test_setup (int *out_srcfd, int *out_destfd,
+                     GError **error)
+{
+  glnx_autofd int srcfd = -1;
+  glnx_autofd int destfd = -1;
+
+  (void) glnx_shutil_rm_rf_at (AT_FDCWD, "srcdir", NULL, NULL);
+  if (mkdir ("srcdir", 0755) < 0)
+    err (1, "mkdir");
+  if (!glnx_opendirat (AT_FDCWD, "srcdir", TRUE, &srcfd, error))
+    return FALSE;
+  (void) glnx_shutil_rm_rf_at (AT_FDCWD, "destdir", NULL, NULL);
+  if (mkdir ("destdir", 0755) < 0)
+    err (1, "mkdir");
+  if (!glnx_opendirat (AT_FDCWD, "destdir", TRUE, &destfd, error))
+    return FALSE;
+
+  if (!glnx_file_replace_contents_at (srcfd, "foo", (guint8*)"foo contents", strlen ("foo contents"),
+                                      GLNX_FILE_REPLACE_NODATASYNC, NULL, error))
+    return FALSE;
+  if (!glnx_file_replace_contents_at (destfd, "bar", (guint8*)"bar contents", strlen ("bar contents"),
+                                      GLNX_FILE_REPLACE_NODATASYNC, NULL, error))
+    return FALSE;
+
+  *out_srcfd = srcfd; srcfd = -1;
+  *out_destfd = destfd; destfd = -1;
+  return TRUE;
+}
+
+static void
+test_renameat2_noreplace (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+  glnx_autofd int srcfd = -1;
+  glnx_autofd int destfd = -1;
+  struct stat stbuf;
+
+  if (!renameat_test_setup (&srcfd, &destfd, error))
+    return;
+
+  if (glnx_renameat2_noreplace (srcfd, "foo", destfd, "bar") == 0)
+    g_assert_not_reached ();
+  else
+    {
+      g_assert_cmpint (errno, ==, EEXIST);
+    }
+
+  if (glnx_renameat2_noreplace (srcfd, "foo", destfd, "baz") < 0)
+    return (void)glnx_throw_errno_prefix (error, "renameat");
+  if (!glnx_fstatat (destfd, "bar", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+
+  if (fstatat (srcfd, "foo", &stbuf, AT_SYMLINK_NOFOLLOW) == 0)
+    g_assert_not_reached ();
+  else
+    g_assert_cmpint (errno, ==, ENOENT);
+}
+
+static void
+test_renameat2_exchange (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+
+  glnx_autofd int srcfd = -1;
+  glnx_autofd int destfd = -1;
+  if (!renameat_test_setup (&srcfd, &destfd, error))
+    return;
+
+  if (glnx_renameat2_exchange (AT_FDCWD, "srcdir", AT_FDCWD, "destdir") < 0)
+    return (void)glnx_throw_errno_prefix (error, "renameat");
+
+  /* Ensure the dir fds are the same */
+  struct stat stbuf;
+  if (!glnx_fstatat (srcfd, "foo", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+  if (!glnx_fstatat (destfd, "bar", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+  /* But the dirs should be swapped */
+  if (!glnx_fstatat (AT_FDCWD, "destdir/foo", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+  if (!glnx_fstatat (AT_FDCWD, "srcdir/bar", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+}
+
+static void
+test_tmpfile (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+
+  g_auto(GLnxTmpfile) tmpf = { 0, };
+  if (!glnx_open_tmpfile_linkable_at (AT_FDCWD, ".", O_WRONLY|O_CLOEXEC, &tmpf, error))
+    return;
+  if (glnx_loop_write (tmpf.fd, "foo", strlen ("foo")) < 0)
+    return (void)glnx_throw_errno_prefix (error, "write");
+  if (glnx_link_tmpfile_at (&tmpf, GLNX_LINK_TMPFILE_NOREPLACE, AT_FDCWD, "foo", error))
+    return;
+}
+
+static void
+test_stdio_file (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+  g_auto(GLnxTmpfile) tmpf = { 0, };
+  g_autoptr(FILE) f = NULL;
+
+  if (!glnx_open_anonymous_tmpfile (O_RDWR|O_CLOEXEC, &tmpf, error))
+    return;
+  f = fdopen (tmpf.fd, "w");
+  tmpf.fd = -1; /* Ownership was transferred via fdopen() */
+  if (!f)
+    return (void)glnx_throw_errno_prefix (error, "fdopen");
+  if (fwrite ("hello", 1, strlen ("hello"), f) != strlen ("hello"))
+    return (void)glnx_throw_errno_prefix (error, "fwrite");
+  if (!glnx_stdio_file_flush (f, error))
+    return;
+}
+
+static void
+test_fstatat (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+  struct stat stbuf = { 0, };
+
+  if (!glnx_fstatat_allow_noent (AT_FDCWD, ".", &stbuf, 0, error))
+    return;
+  g_assert_cmpint (errno, ==, 0);
+  g_assert_no_error (local_error);
+  g_assert (S_ISDIR (stbuf.st_mode));
+  if (!glnx_fstatat_allow_noent (AT_FDCWD, "nosuchfile", &stbuf, 0, error))
+    return;
+  g_assert_cmpint (errno, ==, ENOENT);
+  g_assert_no_error (local_error);
+
+  /* test NULL parameter for stat */
+  if (!glnx_fstatat_allow_noent (AT_FDCWD, ".", NULL, 0, error))
+    return;
+  g_assert_cmpint (errno, ==, 0);
+  g_assert_no_error (local_error);
+  if (!glnx_fstatat_allow_noent (AT_FDCWD, "nosuchfile", NULL, 0, error))
+    return;
+  g_assert_cmpint (errno, ==, ENOENT);
+  g_assert_no_error (local_error);
+}
+
+static void
+test_filecopy (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+  const char foo[] = "foo";
+  struct stat stbuf;
+
+  if (!glnx_ensure_dir (AT_FDCWD, "subdir", 0755, error))
+    return;
+
+  if (!glnx_file_replace_contents_at (AT_FDCWD, foo, (guint8*)foo, sizeof (foo),
+                                      GLNX_FILE_REPLACE_NODATASYNC, NULL, error))
+    return;
+
+  /* Copy it into both the same dir and a subdir */
+  if (!glnx_file_copy_at (AT_FDCWD, foo, NULL, AT_FDCWD, "bar",
+                          GLNX_FILE_COPY_NOXATTRS, NULL, error))
+    return;
+  if (!glnx_file_copy_at (AT_FDCWD, foo, NULL, AT_FDCWD, "subdir/bar",
+                          GLNX_FILE_COPY_NOXATTRS, NULL, error))
+    return;
+  if (!glnx_fstatat (AT_FDCWD, "subdir/bar", &stbuf, 0, error))
+    return;
+
+  if (glnx_file_copy_at (AT_FDCWD, foo, NULL, AT_FDCWD, "bar",
+                         GLNX_FILE_COPY_NOXATTRS, NULL, error))
+    g_assert_not_reached ();
+  g_assert_error (local_error, G_IO_ERROR, G_IO_ERROR_EXISTS);
+  g_clear_error (&local_error);
+
+  if (!glnx_file_copy_at (AT_FDCWD, foo, NULL, AT_FDCWD, "bar",
+                          GLNX_FILE_COPY_NOXATTRS | GLNX_FILE_COPY_OVERWRITE,
+                          NULL, error))
+    return;
+
+  if (symlinkat ("nosuchtarget", AT_FDCWD, "link") < 0)
+    return (void) glnx_throw_errno_prefix (error, "symlinkat");
+
+  /* Shouldn't be able to overwrite a symlink without GLNX_FILE_COPY_OVERWRITE */
+  if (glnx_file_copy_at (AT_FDCWD, foo, NULL, AT_FDCWD, "link",
+                         GLNX_FILE_COPY_NOXATTRS,
+                         NULL, error))
+    g_assert_not_reached ();
+  g_assert_error (local_error, G_IO_ERROR, G_IO_ERROR_EXISTS);
+  g_clear_error (&local_error);
+
+  /* Test overwriting symlink */
+  if (!glnx_file_copy_at (AT_FDCWD, foo, NULL, AT_FDCWD, "link",
+                          GLNX_FILE_COPY_NOXATTRS | GLNX_FILE_COPY_OVERWRITE,
+                          NULL, error))
+    return;
+
+  if (!glnx_fstatat_allow_noent (AT_FDCWD, "nosuchtarget", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+  g_assert_cmpint (errno, ==, ENOENT);
+  g_assert_no_error (local_error);
+
+  if (!glnx_fstatat (AT_FDCWD, "link", &stbuf, AT_SYMLINK_NOFOLLOW, error))
+    return;
+  g_assert (S_ISREG (stbuf.st_mode));
+}
+
+int main (int argc, char **argv)
+{
+  int ret;
+
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/tmpfile", test_tmpfile);
+  g_test_add_func ("/stdio-file", test_stdio_file);
+  g_test_add_func ("/filecopy", test_filecopy);
+  g_test_add_func ("/renameat2-noreplace", test_renameat2_noreplace);
+  g_test_add_func ("/renameat2-exchange", test_renameat2_exchange);
+  g_test_add_func ("/fstat", test_fstatat);
+
+  ret = g_test_run();
+
+  return ret;
+}
diff --git a/libglnx/tests/test-libglnx-macros.c b/libglnx/tests/test-libglnx-macros.c
new file mode 100644
index 0000000000000000000000000000000000000000..ffde8fae202ff3d80589c08b9d17ee18e06beaa3
--- /dev/null
+++ b/libglnx/tests/test-libglnx-macros.c
@@ -0,0 +1,109 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This library 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 License, 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 "libglnx.h"
+#include <glib.h>
+#include <stdlib.h>
+#include <gio/gio.h>
+#include <string.h>
+
+static void
+test_inset (void)
+{
+  g_assert (G_IN_SET (7, 7));
+  g_assert (G_IN_SET (7, 42, 7));
+  g_assert (G_IN_SET (7, 7,42,3,9));
+  g_assert (G_IN_SET (42, 7,42,3,9));
+  g_assert (G_IN_SET (3, 7,42,3,9));
+  g_assert (G_IN_SET (9, 7,42,3,9));
+  g_assert (!G_IN_SET (8, 7,42,3,9));
+  g_assert (!G_IN_SET (-1, 7,42,3,9));
+  g_assert (G_IN_SET ('x', 'a', 'x', 'c'));
+  g_assert (!G_IN_SET ('y', 'a', 'x', 'c'));
+}
+
+static void
+test_hash_table_foreach (void)
+{
+  /* use var names all different from the macro metavars to ensure proper
+   * substitution */
+  g_autoptr(GHashTable) table = g_hash_table_new (g_str_hash, g_str_equal);
+  const char *keys[] = {"key1", "key2"};
+  const char *vals[] = {"val1", "val2"};
+  g_hash_table_insert (table, (gpointer)keys[0], (gpointer)vals[0]);
+  g_hash_table_insert (table, (gpointer)keys[1], (gpointer)vals[1]);
+
+  guint i = 0;
+  GLNX_HASH_TABLE_FOREACH_IT (table, it, const char*, key, const char*, val)
+    {
+      g_assert_cmpstr (key, ==, keys[i]);
+      g_assert_cmpstr (val, ==, vals[i]);
+      i++;
+    }
+  g_assert_cmpuint (i, ==, 2);
+
+  i = 0;
+  GLNX_HASH_TABLE_FOREACH_IT (table, it, const char*, key, const char*, val)
+    {
+      g_hash_table_iter_remove (&it);
+      break;
+    }
+  g_assert_cmpuint (g_hash_table_size (table), ==, 1);
+
+  g_hash_table_insert (table, (gpointer)keys[1], (gpointer)vals[1]);
+  g_assert_cmpuint (g_hash_table_size (table), ==, 1);
+
+  g_hash_table_insert (table, (gpointer)keys[0], (gpointer)vals[0]);
+  g_assert_cmpuint (g_hash_table_size (table), ==, 2);
+
+  i = 0;
+  GLNX_HASH_TABLE_FOREACH_KV (table, const char*, key, const char*, val)
+    {
+      g_assert_cmpstr (key, ==, keys[i]);
+      g_assert_cmpstr (val, ==, vals[i]);
+      i++;
+    }
+  g_assert_cmpuint (i, ==, 2);
+
+  i = 0;
+  GLNX_HASH_TABLE_FOREACH (table, const char*, key)
+    {
+      g_assert_cmpstr (key, ==, keys[i]);
+      i++;
+    }
+  g_assert_cmpuint (i, ==, 2);
+
+  i = 0;
+  GLNX_HASH_TABLE_FOREACH_V (table, const char*, val)
+    {
+      g_assert_cmpstr (val, ==, vals[i]);
+      i++;
+    }
+  g_assert_cmpuint (i, ==, 2);
+}
+
+int main (int argc, char **argv)
+{
+  g_test_init (&argc, &argv, NULL);
+  g_test_add_func ("/inset", test_inset);
+  g_test_add_func ("/hash_table_foreach", test_hash_table_foreach);
+  return g_test_run();
+}
diff --git a/libglnx/tests/test-libglnx-shutil.c b/libglnx/tests/test-libglnx-shutil.c
new file mode 100644
index 0000000000000000000000000000000000000000..6917b89096879b296f8ea70c293cc202b2190048
--- /dev/null
+++ b/libglnx/tests/test-libglnx-shutil.c
@@ -0,0 +1,63 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright © 2017 Endless Mobile, Inc.
+ *
+ * This library 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 License, 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 "libglnx.h"
+#include <glib.h>
+#include <stdlib.h>
+#include <gio/gio.h>
+#include <err.h>
+#include <string.h>
+
+#include "libglnx-testlib.h"
+
+static void
+test_mkdir_p_enoent (void)
+{
+  _GLNX_TEST_DECLARE_ERROR(local_error, error);
+  glnx_autofd int dfd = -1;
+
+  if (!glnx_ensure_dir (AT_FDCWD, "test", 0755, error))
+    return;
+  if (!glnx_opendirat (AT_FDCWD, "test", FALSE, &dfd, error))
+    return;
+  if (rmdir ("test") < 0)
+    return (void) glnx_throw_errno_prefix (error, "rmdir(%s)", "test");
+
+  /* This should fail with ENOENT. */
+  glnx_shutil_mkdir_p_at (dfd, "blah/baz", 0755, NULL, error);
+  g_assert_error (local_error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND);
+  g_clear_error (&local_error);
+}
+
+int
+main (int    argc,
+      char **argv)
+{
+  int ret;
+
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/mkdir-p/enoent", test_mkdir_p_enoent);
+
+  ret = g_test_run();
+
+  return ret;
+}
diff --git a/libglnx/tests/test-libglnx-xattrs.c b/libglnx/tests/test-libglnx-xattrs.c
new file mode 100644
index 0000000000000000000000000000000000000000..63e12314a332ddd94e7b5b3c17fbec7c761e1350
--- /dev/null
+++ b/libglnx/tests/test-libglnx-xattrs.c
@@ -0,0 +1,283 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This library 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 License, 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 "libglnx.h"
+#include <glib.h>
+#include <stdlib.h>
+#include <gio/gio.h>
+#include <string.h>
+
+#define XATTR_THREAD_RUN_TIME_USECS (5 * G_USEC_PER_SEC)
+
+struct XattrWorker {
+  int dfd;
+  gboolean is_writer;
+  guint n_attrs_read;
+};
+
+typedef enum {
+  WRITE_RUN_MUTATE,
+  WRITE_RUN_CREATE,
+} WriteType;
+
+static gboolean
+set_random_xattr_value (int fd, const char *name, GError **error)
+{
+  const guint8 randxattrbyte = g_random_int_range (0, 256);
+  const guint32 randxattrvalue_len = (g_random_int () % 256) + 1; /* Picked to be not too small or large */
+  g_autofree char *randxattrvalue = g_malloc (randxattrvalue_len);
+
+  memset (randxattrvalue, randxattrbyte, randxattrvalue_len);
+
+  if (fsetxattr (fd, name, randxattrvalue, randxattrvalue_len, 0) < 0)
+    {
+      glnx_set_error_from_errno (error);
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+add_random_xattrs (int fd, GError **error)
+{
+  const guint nattrs = MIN (2, g_random_int () % 16);
+
+  for (guint i = 0; i < nattrs; i++)
+    {
+      guint32 randxattrname_v = g_random_int ();
+      g_autofree char *randxattrname = g_strdup_printf ("user.test%u", randxattrname_v);
+
+      if (!set_random_xattr_value (fd, randxattrname, error))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+do_write_run (GLnxDirFdIterator *dfd_iter, GError **error)
+{
+  WriteType wtype = g_random_int () % 2;
+
+  if (wtype == WRITE_RUN_CREATE)
+    {
+      guint32 randname_v = g_random_int ();
+      g_autofree char *randname = g_strdup_printf ("file%u", randname_v);
+      glnx_autofd int fd = -1;
+
+    again:
+      fd = openat (dfd_iter->fd, randname, O_CREAT | O_EXCL, 0644);
+      if (fd < 0)
+        {
+          if (errno == EEXIST)
+            {
+              g_printerr ("Congratulations!  I suggest purchasing a lottery ticket today!\n");
+              goto again;
+            }
+          else
+            {
+              glnx_set_error_from_errno (error);
+              return FALSE;
+            }
+        }
+
+      if (!add_random_xattrs (fd, error))
+        return FALSE;
+      }
+  else if (wtype == WRITE_RUN_MUTATE)
+    {
+      while (TRUE)
+        {
+          struct dirent *dent;
+          if (!glnx_dirfd_iterator_next_dent (dfd_iter, &dent, NULL, error))
+            return FALSE;
+          if (!dent)
+            break;
+
+          glnx_autofd int fd = -1;
+          if (!glnx_openat_rdonly (dfd_iter->fd, dent->d_name, FALSE, &fd, error))
+            return FALSE;
+
+          g_autoptr(GVariant) current_xattrs = NULL;
+          if (!glnx_fd_get_all_xattrs (fd, &current_xattrs, NULL, error))
+            return FALSE;
+
+          for (int i = 0; i < g_variant_n_children (current_xattrs); i++)
+            {
+              const char *name, *value;
+              g_variant_get_child (current_xattrs, i, "(^&ay^&ay)", &name, &value);
+
+              /* We don't want to potentially test/change xattrs like security.selinux
+               * that were injected by the system.
+               */
+              if (!g_str_has_prefix (name, "user.test"))
+                continue;
+
+              if (!set_random_xattr_value (fd, name, error))
+                return FALSE;
+            }
+        }
+    }
+  else
+    g_assert_not_reached ();
+
+  return TRUE;
+}
+
+static gboolean
+do_read_run (GLnxDirFdIterator *dfd_iter,
+             guint *out_n_read,
+             GError **error)
+{
+  guint nattrs = 0;
+  while (TRUE)
+    {
+      struct dirent *dent;
+      if (!glnx_dirfd_iterator_next_dent (dfd_iter, &dent, NULL, error))
+        return FALSE;
+      if (!dent)
+        break;
+
+      glnx_autofd int fd = -1;
+      if (!glnx_openat_rdonly (dfd_iter->fd, dent->d_name, FALSE, &fd, error))
+        return FALSE;
+
+      g_autoptr(GVariant) current_xattrs = NULL;
+      if (!glnx_fd_get_all_xattrs (fd, &current_xattrs, NULL, error))
+        return FALSE;
+
+      /* We don't actually care about the values, just use the variable
+       * to avoid compiler warnings.
+       */
+      nattrs += g_variant_n_children (current_xattrs);
+    }
+
+  *out_n_read = nattrs;
+  return TRUE;
+}
+
+static gpointer
+xattr_thread (gpointer data)
+{
+  g_autoptr(GError) local_error = NULL;
+  GError **error = &local_error;
+  struct XattrWorker *worker = data;
+  guint64 end_time = g_get_monotonic_time () + XATTR_THREAD_RUN_TIME_USECS;
+  guint n_read = 0;
+
+  while (g_get_monotonic_time () < end_time)
+    {
+      g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
+
+      if (!glnx_dirfd_iterator_init_at (worker->dfd, ".", TRUE, &dfd_iter, error))
+        goto out;
+
+      if (worker->is_writer)
+        {
+          if (!do_write_run (&dfd_iter, error))
+            goto out;
+        }
+      else
+        {
+          if (!do_read_run (&dfd_iter, &n_read, error))
+            goto out;
+        }
+    }
+
+ out:
+  g_assert_no_error (local_error);
+
+  return GINT_TO_POINTER (n_read);
+}
+
+static void
+test_xattr_races (void)
+{
+  /* If for some reason we're built in a VM which only has one vcpu, let's still
+   * at least make the test do something.
+   */
+  /* FIXME - this deadlocks for me on 4.9.4-201.fc25.x86_64, whether
+   * using overlayfs or xfs as source/dest.
+   */
+  const guint nprocs = MAX (4, g_get_num_processors ());
+  struct XattrWorker wdata[nprocs];
+  GThread *threads[nprocs];
+  g_autoptr(GError) local_error = NULL;
+  GError **error = &local_error;
+  g_auto(GLnxTmpDir) tmpdir = { 0, };
+  g_autofree char *tmpdir_path = g_strdup_printf ("%s/libglnx-xattrs-XXXXXX",
+                                                  getenv ("TMPDIR") ?: "/var/tmp");
+  guint nread = 0;
+
+  if (!glnx_mkdtempat (AT_FDCWD, tmpdir_path, 0700,
+                       &tmpdir, error))
+    goto out;
+
+  /* Support people building/testing on tmpfs https://github.com/flatpak/flatpak/issues/686 */
+  if (fsetxattr (tmpdir.fd, "user.test", "novalue", strlen ("novalue"), 0) < 0)
+    {
+      if (errno == EOPNOTSUPP)
+        {
+          g_test_skip ("no xattr support");
+          return;
+        }
+      else
+        {
+          glnx_set_error_from_errno (error);
+          goto out;
+        }
+    }
+
+  for (guint i = 0; i < nprocs; i++)
+    {
+      struct XattrWorker *worker = &wdata[i];
+      worker->dfd = tmpdir.fd;
+      worker->is_writer = i % 2 == 0;
+      threads[i] = g_thread_new (NULL, xattr_thread, worker);
+    }
+
+  for (guint i = 0; i < nprocs; i++)
+    {
+      if (wdata[i].is_writer)
+        (void) g_thread_join (threads[i]);
+      else
+        nread += GPOINTER_TO_UINT (g_thread_join (threads[i]));
+    }
+
+  g_print ("Read %u xattrs race free!\n", nread);
+
+ out:
+  g_assert_no_error (local_error);
+}
+
+int main (int argc, char **argv)
+{
+  int ret;
+
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/xattr-races", test_xattr_races);
+
+  ret = g_test_run();
+
+  return ret;
+}