[glib] gtestdbus: Don’t close stdout for dbus-dae mon

[Philip Withnall <pwithnall src gnome org>]

commit d80adeaa960ddfa13837900d0391f9bd9c239f78
Author: Philip Withnall <philip tecnocode co uk>
Date:   Sat Jun 21 23:01:08 2014 +0100

    gtestdbus: Don’t close stdout for dbus-daemon
    
    The stdout FD passed to dbus-daemon is propagated to all its child
    processes, such as service activated processes. If we close the FD after
    reading the bus address from the daemon, any child process which
    subsequently writes to stdout (e.g. for logging) will get a SIGPIPE and
    explode.
    
    Instead of closing the stdout FD immediately after dbus-daemon has
    spawned, keep it open until the daemon is killed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732019

 gio/gtestdbus.c |   17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)
---
diff --git a/gio/gtestdbus.c b/gio/gtestdbus.c
index 4b51d29..4af270b 100644
--- a/gio/gtestdbus.c
+++ b/gio/gtestdbus.c
@@ -418,6 +418,7 @@ struct _GTestDBusPrivate
   GTestDBusFlags flags;
   GPtrArray *service_dirs;
   GPid bus_pid;
+  gint bus_stdout_fd;
   gchar *bus_address;
   gboolean up;
 };
@@ -581,8 +582,8 @@ start_daemon (GTestDBus *self)
   const gchar *argv[] = {"dbus-daemon", "--print-address", "--config-file=foo", NULL};
   gchar *config_path;
   gchar *config_arg;
-  gint stdout_fd;
   GIOChannel *channel;
+  gint stdout_fd2;
   gsize termpos;
   GError *error = NULL;
 
@@ -607,15 +608,21 @@ start_daemon (GTestDBus *self)
                             NULL,
                             &self->priv->bus_pid,
                             NULL,
-                            &stdout_fd,
+                            &self->priv->bus_stdout_fd,
                             NULL,
                             &error);
   g_assert_no_error (error);
 
   _g_test_watcher_add_pid (self->priv->bus_pid);
 
-  /* Read bus address from daemon' stdout */
-  channel = g_io_channel_unix_new (stdout_fd);
+  /* Read bus address from daemon' stdout. We have to be careful to avoid
+   * closing the FD, as it is passed to any D-Bus service activated processes,
+   * and if we close it, they will get a SIGPIPE and die when they try to write
+   * to their stdout. */
+  stdout_fd2 = dup (self->priv->bus_stdout_fd);
+  g_assert_cmpint (stdout_fd2, >=, 0);
+  channel = g_io_channel_unix_new (stdout_fd2);
+
   g_io_channel_read_line (channel, &self->priv->bus_address, NULL,
       &termpos, &error);
   g_assert_no_error (error);
@@ -659,6 +666,8 @@ stop_daemon (GTestDBus *self)
   _g_test_watcher_remove_pid (self->priv->bus_pid);
   g_spawn_close_pid (self->priv->bus_pid);
   self->priv->bus_pid = 0;
+  close (self->priv->bus_stdout_fd);
+  self->priv->bus_stdout_fd = -1;
 
   g_free (self->priv->bus_address);
   self->priv->bus_address = NULL;