GChildWatchSource: Allow passing -1 for pidwip/child-catchall

With the goal of modifying gnome-session to use the new Linux
PR_SET_CHILD_SUBREAPER, it needs to be able to reap arbitary children
that may be reparented to it.

But if gnome-session is going to continue to work with GLib and GIO,
even if we converted all child watches in gnome-session to use this
new API, we'd still have to contend with the possibility of it having
a process spawned indirectly (stuff like the GDBus dbus-launch
invocation).  Thus, we don't give the -1 child watch *every* waitpid,
only the ones which don't have a specific watcher.

Also, fix up g_spawn_sync() to hold the unix signal lock when forking.
This way we ensure that GLib itself gets the waitpid() result for the
synchronously spawned child, instead of racing with the worker thread.

https://bugzilla.gnome.org/show_bug.cgi?id=687061

1 files changed, 100 insertions, 0 deletions

diff --git a/glib/tests/unix.c b/glib/tests/unix.c
index 329e19aa8..ffcc6a11f 100644
--- a/glib/tests/unix.c
+++ b/glib/tests/unix.c
@@ -147,6 +147,105 @@ test_sighup_add_remove (void)
 
 }
 
+typedef struct {
+  GPid regular_pid;
+  GPid catchall_pid;
+  GMainLoop *loop;
+  gboolean regular_exited;
+  gboolean catchall_exited;
+} CatchAllData;
+
+static void
+on_catchall_child (GPid   pid,
+                   gint   estatus,
+                   gpointer user_data)
+{
+  CatchAllData *data = user_data;
+  GError *local_error = NULL;
+  GError **error = &local_error;
+
+  g_assert (pid == data->catchall_pid);
+
+  g_spawn_check_exit_status (estatus, error);
+  g_assert_no_error (local_error);
+
+  data->catchall_exited = TRUE;
+  if (data->regular_exited)
+    g_main_loop_quit (data->loop);
+}
+
+static void
+on_regular_child (GPid  pid,
+                  gint  estatus,
+                  gpointer user_data)
+{
+  CatchAllData *data = user_data;
+  GError *local_error = NULL;
+  GError **error = &local_error;
+
+  g_assert (pid == data->regular_pid);
+
+  g_spawn_check_exit_status (estatus, error);
+  g_assert_no_error (local_error);
+
+  data->regular_exited = TRUE;
+  if (data->catchall_exited)
+    g_main_loop_quit (data->loop);
+}
+
+static void
+spawn_with_raw_fork (gchar  **child_argv,
+                     pid_t   *out_pid)
+{
+  pid_t pid;
+
+  pid = fork ();
+  g_assert (pid >= 0);
+  if (pid == 0)
+    {
+      execv (child_argv[0], child_argv+1);
+      g_assert_not_reached ();
+    }
+  else
+    *out_pid = pid;
+}
+
+static void
+test_catchall (void)
+{
+  GMainLoop *mainloop;
+  CatchAllData data;
+  GSource *source;
+  GPid pid;
+  GError *local_error = NULL;
+  GError **error = &local_error;
+  char *child_args[] = { "/bin/true", "/bin/true", NULL };
+
+  memset (&data, 0, sizeof (data));
+  mainloop = g_main_loop_new (NULL, FALSE);
+  data.loop = mainloop;
+
+  source = g_child_watch_source_new (-1);
+  g_source_set_callback (source, (GSourceFunc)on_catchall_child, &data, NULL);
+  g_source_attach (source, NULL);
+  g_source_unref (source);
+
+  g_spawn_async (NULL, (char**)child_args, NULL, G_SPAWN_DO_NOT_REAP_CHILD,
+                 NULL, NULL, &pid, error);
+  g_child_watch_add (pid, on_regular_child, &data);
+  data.regular_pid = pid;
+
+  spawn_with_raw_fork ((char**)child_args, &pid);
+  data.catchall_pid = pid;
+
+  g_main_loop_run (mainloop);
+
+  g_source_destroy (source);
+  g_main_loop_unref (mainloop);
+
+  g_assert (data.regular_exited && data.catchall_exited);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -159,6 +258,7 @@ main (int   argc,
   g_test_add_func ("/glib-unix/sigterm", test_sigterm);
   g_test_add_func ("/glib-unix/sighup_again", test_sighup);
   g_test_add_func ("/glib-unix/sighup_add_remove", test_sighup_add_remove);
+  g_test_add_func ("/glib-unix/catchall", test_catchall);
 
   return g_test_run();
 }