backports: Add g_steal_fd, from GLib >= 2.70

This is essentially the same as glnx_steal_fd, so make glnx_steal_fd an
alias for it.

The unit test is taken from GLib, slightly modified to avoid g_close()
and also test the old name glnx_steal_fd().

Signed-off-by: Simon McVittie <smcv@collabora.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/test-libglnx-backports.c b/tests/test-libglnx-backports.c
index c475cd4..0fa374e 100644
--- a/tests/test-libglnx-backports.c
+++ b/tests/test-libglnx-backports.c
@@ -2,12 +2,15 @@
  *
  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
  * Copyright 2019 Emmanuel Fleury
+ * Copyright 2021 Collabora Ltd.
  * SPDX-License-Identifier: LGPL-2.1-or-later AND LicenseRef-old-glib-tests
  */
 
 #include "libglnx-config.h"
 #include "libglnx.h"
 
+#include <glib/gstdio.h>
+
 /* Testing g_memdup2() function with various positive and negative cases */
 static void
 test_memdup2 (void)
@@ -28,9 +31,45 @@ test_memdup2 (void)
   g_free (str_dup);
 }
 
+static void
+test_steal_fd (void)
+{
+  GError *error = NULL;
+  gchar *tmpfile = NULL;
+  int fd = -42;
+  int borrowed;
+  int stolen;
+
+  g_assert_cmpint (g_steal_fd (&fd), ==, -42);
+  g_assert_cmpint (fd, ==, -1);
+  g_assert_cmpint (g_steal_fd (&fd), ==, -1);
+  g_assert_cmpint (fd, ==, -1);
+
+  fd = g_file_open_tmp (NULL, &tmpfile, &error);
+  g_assert_cmpint (fd, >=, 0);
+  g_assert_no_error (error);
+  borrowed = fd;
+  stolen = g_steal_fd (&fd);
+  g_assert_cmpint (fd, ==, -1);
+  g_assert_cmpint (borrowed, ==, stolen);
+
+  g_assert_no_errno (close (g_steal_fd (&stolen)));
+  g_assert_cmpint (stolen, ==, -1);
+
+  g_assert_no_errno (remove (tmpfile));
+  g_free (tmpfile);
+
+  /* Backwards compatibility with older libglnx: glnx_steal_fd is the same
+   * as g_steal_fd */
+  fd = -23;
+  g_assert_cmpint (glnx_steal_fd (&fd), ==, -23);
+  g_assert_cmpint (fd, ==, -1);
+}
+
 int main (int argc, char **argv)
 {
   g_test_init (&argc, &argv, NULL);
+  g_test_add_func ("/mainloop/steal-fd", test_steal_fd);
   g_test_add_func ("/strfuncs/memdup2", test_memdup2);
   return g_test_run();
 }