Never pass an invalid X connection descriptor to an input reading loop

Fixes: debbugs:19147

* xterm.c (x_delete_terminal): Call emacs_close for X connection
descriptor if called from x_connection_closed and always delete
this descriptor from keyboard waiting set (Bug#19147).

2 files changed, 21 insertions, 10 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 2a6e2373fcd..27c08580cb8 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-11  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        * xterm.c (x_delete_terminal): Call emacs_close for X connection
+        descriptor if called from x_connection_closed and always delete
+        this descriptor from keyboard waiting set (Bug#19147).
+
 2014-12-10  Eli Zaretskii  <eliz@gnu.org>
 
         * bidi.c (BIDI_CACHE_MAX_ELTS_PER_SLOT): New macro.
diff --git a/src/xterm.c b/src/xterm.c
index 98f2a27c1ce..1ccc38ca313 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -11318,8 +11318,7 @@ x_delete_terminal (struct terminal *terminal)
     xim_close_dpy (dpyinfo);
 #endif
 
-  /* If called from x_connection_closed, the display may already be closed
-     and dpyinfo->display was set to 0 to indicate that.  */
+  /* Normally, the display is available...  */
   if (dpyinfo->display)
     {
       x_destroy_all_bitmaps (dpyinfo);
@@ -11360,17 +11359,23 @@ x_delete_terminal (struct terminal *terminal)
       XCloseDisplay (dpyinfo->display);
 #endif
 #endif /* ! USE_GTK */
-
-      /* No more input on this descriptor.  Do not close it because
-         it's already closed by X(t)CloseDisplay (Bug#18403).  */
-      eassert (0 <= dpyinfo->connection);
-      delete_keyboard_wait_descriptor (dpyinfo->connection);
-
-      /* Mark as dead. */
+      /* Do not close the connection here because it's already closed
+         by X(t)CloseDisplay (Bug#18403).  */
       dpyinfo->display = NULL;
-      dpyinfo->connection = -1;
     }
 
+  /* ...but if called from x_connection_closed, the display may already
+     be closed and dpyinfo->display was set to 0 to indicate that.  Since
+     X server is most likely gone, explicit close is the only reliable
+     way to continue and avoid Bug#19147.  */
+  else if (dpyinfo->connection >= 0)
+    emacs_close (dpyinfo->connection);
+
+  /* No more input on this descriptor.  */
+  delete_keyboard_wait_descriptor (dpyinfo->connection);
+  /* Mark as dead. */
+  dpyinfo->connection = -1;
+
   x_delete_display (dpyinfo);
   unblock_input ();
 }