Merge lp:~mterry/lightdm/initialize-more into lp:lightdm

[Michael Terry]

Be more careful about closing uninitialized memory.

Be more careful about closing uninitialized memory.

It caused problems for Josh and me:
- lightdm calls close(0) because of unintialized/zero-initialized memory used as an argument to close()
- pipe() and similar methods are happy to give back fd=0 now
- lightdm may provide USC with --from-dm-fd=0 because it got back 0 from pipe
- USC can't actually write to fd=0 because that's its stdin and isn't inherited like other fds
- USC aborts because it can't open from-dm-fd for writing

Thanks to Josh for finding this fix with me.

[Robert Ancell (robert-ancell)]

Thanks guys!

review: Approve

[Robert Ancell (robert-ancell)]

I've merged the second half of this patch into the 1.18, 1.16 and 1.10 branches.

=== modified file 'src/greeter-session.c'
--- src/greeter-session.c	2016-05-19 02:01:57 +0000
+++ src/greeter-session.c	2016-06-08 18:12:45 +0000
@@ -20,10 +20,6 @@
 {
     /* Greeter running inside this session */
     Greeter *greeter;
-
-    /* Communication channels to communicate with */
-    int to_greeter_input;
-    int from_greeter_output;
 };
 
 G_DEFINE_TYPE (GreeterSession, greeter_session, SESSION_TYPE);
@@ -88,8 +84,6 @@
     GreeterSession *self = GREETER_SESSION (object);
 
     g_clear_object (&self->priv->greeter);
-    close (self->priv->to_greeter_input);
-    close (self->priv->from_greeter_output);
 
     G_OBJECT_CLASS (greeter_session_parent_class)->finalize (object);
 }

=== modified file 'src/unity-system-compositor.c'
--- src/unity-system-compositor.c	2016-05-26 00:36:33 +0000
+++ src/unity-system-compositor.c	2016-06-08 18:12:45 +0000
@@ -435,9 +435,9 @@
 
     /* Close compostor ends of the pipes */
     close (compositor->priv->to_compositor_pipe[0]);
-    compositor->priv->to_compositor_pipe[0] = 0;
+    compositor->priv->to_compositor_pipe[0] = -1;
     close (compositor->priv->from_compositor_pipe[1]);
-    compositor->priv->from_compositor_pipe[1] = 0;
+    compositor->priv->from_compositor_pipe[1] = -1;
 
     if (!result)
         return FALSE;
@@ -466,6 +466,10 @@
     compositor->priv->command = g_strdup ("unity-system-compositor");
     compositor->priv->socket = g_strdup ("/run/mir_socket");
     compositor->priv->timeout = -1;
+    compositor->priv->to_compositor_pipe[0] = -1;
+    compositor->priv->to_compositor_pipe[1] = -1;
+    compositor->priv->from_compositor_pipe[0] = -1;
+    compositor->priv->from_compositor_pipe[1] = -1;
 }
 
 static void