fdio: Expose wrappers for renameat2() EXCHANGE and NOREPLACE

I want the `RENAME_EXCHANGE` version for rpm-ostree, to atomically
swap `/usr/share/rpm` (a directory) with a new verison.  While
we're here we might as well expose `RENAME_NOREPLACE` in case
something else wants it.

These both have fallbacks to the non-atomic version.

Closes: https://github.com/GNOME/libglnx/pull/36

1 files changed, 155 insertions, 0 deletions

diff --git a/tests/test-libglnx-fdio.c b/tests/test-libglnx-fdio.c
new file mode 100644
index 0000000..9830c10
--- /dev/null
+++ b/tests/test-libglnx-fdio.c
@@ -0,0 +1,155 @@
+/* -*- 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>
+
+static gboolean
+renameat_test_setup (int *out_srcfd, int *out_destfd,
+                     GError **error)
+{
+  glnx_fd_close int srcfd = -1;
+  glnx_fd_close 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)
+{
+  g_autoptr(GError) local_error = NULL;
+  GError **error = &local_error;
+  glnx_fd_close int srcfd = -1;
+  glnx_fd_close int destfd = -1;
+  struct stat stbuf;
+
+  if (!renameat_test_setup (&srcfd, &destfd, error))
+    goto out;
+
+  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)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+  if (fstatat (destfd, "bar", &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+
+  if (fstatat (srcfd, "foo", &stbuf, AT_SYMLINK_NOFOLLOW) == 0)
+    g_assert_not_reached ();
+  else
+    g_assert_cmpint (errno, ==, ENOENT);
+
+ out:
+  g_assert_no_error (local_error);
+}
+
+static void
+test_renameat2_exchange (void)
+{
+  g_autoptr(GError) local_error = NULL;
+  GError **error = &local_error;
+  glnx_fd_close int srcfd = -1;
+  glnx_fd_close int destfd = -1;
+  struct stat stbuf;
+
+  if (!renameat_test_setup (&srcfd, &destfd, error))
+    goto out;
+
+  if (glnx_renameat2_exchange (AT_FDCWD, "srcdir", AT_FDCWD, "destdir") < 0)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+
+  /* Ensure the dir fds are the same */
+  if (fstatat (srcfd, "foo", &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+  if (fstatat (destfd, "bar", &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+  /* But the dirs should be swapped */
+  if (fstatat (AT_FDCWD, "destdir/foo", &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+  if (fstatat (AT_FDCWD, "srcdir/bar", &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+    {
+      glnx_set_error_from_errno (error);
+      goto out;
+    }
+
+ 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 ("/renameat2-noreplace", test_renameat2_noreplace);
+  g_test_add_func ("/renameat2-exchange", test_renameat2_exchange);
+
+  ret = g_test_run();
+
+  return ret;
+}