gio: compile GUnixConnection on all platforms

On !UNIX, return an error for send_fd() & receive_fd().
(the unixfdmessage unit is not compiled on !UNIX)

The header is installed under the common GIO include directory.

Ensure G_TYPE_UNIX_CONNECTION is registered on all platforms.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

docs/reference/gio/meson.build

@@ -108,7 +108,6 @@ if get_option('gtk_doc')
   if host_system == 'windows'
     ignore_headers += [
       'gfiledescriptorbased.h',
-      'gunixconnection.h',
       'gunixmounts.h',
       'gunixfdlist.h',
       'gunixfdmessage.h',

gio/gsocketconnection.c

@@ -615,9 +615,7 @@ g_socket_connection_factory_register_type (GType         g_type,
 static void
 init_builtin_types (void)
 {
-#ifndef G_OS_WIN32
   g_type_ensure (G_TYPE_UNIX_CONNECTION);
-#endif
   g_type_ensure (G_TYPE_TCP_CONNECTION);
 }
 

gio/gunixconnection.c

@@ -24,7 +24,9 @@
 
 #include <errno.h>
 #include <string.h>
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
+#endif
 
 /**
  * SECTION:gunixconnection
@@ -39,9 +41,12 @@
  * It contains functions to do some of the UNIX socket specific
  * functionality like passing file descriptors.
  *
- * Note that `<gio/gunixconnection.h>` belongs to the UNIX-specific
- * GIO interfaces, thus you have to use the `gio-unix-2.0.pc`
- * pkg-config file when using it.
+ * Since GLib 2.72, #GUnixConnection is available on all platforms. It requires
+ * underlying system support (such as Windows 10 with `AF_UNIX`) at run time.
+ *
+ * Before GLib 2.72, `<gio/gunixconnection.h>` belonged to the UNIX-specific GIO
+ * interfaces, thus you had to use the `gio-unix-2.0.pc` pkg-config file when
+ * using it. This is no longer necessary since GLib 2.72.
  *
  * Since: 2.22
  */
@@ -86,6 +91,7 @@ g_unix_connection_send_fd (GUnixConnection  *connection,
                            GCancellable     *cancellable,
                            GError          **error)
 {
+#ifdef G_OS_UNIX
   GSocketControlMessage *scm;
   GSocket *socket;
 
@@ -114,6 +120,11 @@ g_unix_connection_send_fd (GUnixConnection  *connection,
   g_object_unref (scm);
 
   return TRUE;
+#else
+  g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                       _("Sending FD is not supported"));
+  return FALSE;
+#endif
 }
 
 /**
@@ -139,6 +150,7 @@ g_unix_connection_receive_fd (GUnixConnection  *connection,
                               GCancellable     *cancellable,
                               GError          **error)
 {
+#ifdef G_OS_UNIX
   GSocketControlMessage **scms;
   gint *fds, nfd, fd, nscm;
   GUnixFDMessage *fdmsg;
@@ -221,6 +233,11 @@ g_unix_connection_receive_fd (GUnixConnection  *connection,
     }
 
   return fd;
+#else
+  g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                       _("Receiving FD is not supported"));
+  return -1;
+#endif
 }
 
 static void

gio/meson.build

@@ -346,7 +346,6 @@ if host_system != 'windows'
   unix_sources = files(
     'gfiledescriptorbased.c',
     'giounix-private.c',
-    'gunixconnection.c',
     'gunixfdlist.c',
     'gunixfdmessage.c',
     'gunixmount.c',
@@ -374,7 +373,6 @@ if host_system != 'windows'
 
   gio_unix_include_headers = files(
     'gfiledescriptorbased.h',
-    'gunixconnection.h',
     'gunixmounts.h',
     'gunixfdlist.h',
     'gunixfdmessage.h',
@@ -565,6 +563,7 @@ gio_sources = files(
   'gdtlsclientconnection.c',
   'gdtlsserverconnection.c',
   'gunionvolumemonitor.c',
+  'gunixconnection.c',
   'gunixcredentialsmessage.c',
   'gunixsocketaddress.c',
   'gvfs.c',
@@ -702,6 +701,7 @@ gio_headers = files(
   'gdtlsconnection.h',
   'gdtlsclientconnection.h',
   'gdtlsserverconnection.h',
+  'gunixconnection.h',
   'gunixcredentialsmessage.h',
   'gunixsocketaddress.h',
   'gvfs.h',