Fix check for unsafe watch descriptor

* src/lisp.h (make_pointer_integer_unsafe): New function.
(make_pointer_integer): Use it.
* src/gfilenotify.c (dir_monitor_callback): Omit redundant eassert.
(Fgfile_add_watch): Signal an error instead of failing an
assertion if the pointer does not work.

2 files changed, 10 insertions, 5 deletions

diff --git a/src/gfilenotify.c b/src/gfilenotify.c
index 7eea2cfac1c..798f308b315 100644
--- a/src/gfilenotify.c
+++ b/src/gfilenotify.c
@@ -77,7 +77,6 @@ dir_monitor_callback (GFileMonitor *monitor,
 
   /* Determine callback function.  */
   monitor_object = make_pointer_integer (monitor);
-  eassert (FIXNUMP (monitor_object));
   watch_object = assq_no_quit (monitor_object, watch_list);
 
   if (CONSP (watch_object))
@@ -203,10 +202,10 @@ will be reported only in case of the `moved' event.  */)
   if (! monitor)
     xsignal2 (Qfile_notify_error, build_string ("Cannot watch file"), file);
 
-  Lisp_Object watch_descriptor = make_pointer_integer (monitor);
+  Lisp_Object watch_descriptor = make_pointer_integer_unsafe (monitor);
 
-  /* Check the dicey assumption that make_pointer_integer is safe.  */
-  if (! FIXNUMP (watch_descriptor))
+  if (! (FIXNUMP (watch_descriptor)
+         && XFIXNUMPTR (watch_descriptor) == monitor))
     {
       g_object_unref (monitor);
       xsignal2 (Qfile_notify_error, build_string ("Unsupported file watcher"),
diff --git a/src/lisp.h b/src/lisp.h
index b7ef8dc63a0..18d53537cca 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1189,9 +1189,15 @@ XFIXNUMPTR (Lisp_Object a)
 }
 
 INLINE Lisp_Object
+make_pointer_integer_unsafe (void *p)
+{
+  return TAG_PTR (Lisp_Int0, p);
+}
+
+INLINE Lisp_Object
 make_pointer_integer (void *p)
 {
-  Lisp_Object a = TAG_PTR (Lisp_Int0, p);
+  Lisp_Object a = make_pointer_integer_unsafe (p);
   eassert (FIXNUMP (a) && XFIXNUMPTR (a) == p);
   return a;
 }