From: Victor Stinner <victor.stinner@haypocalc.com>
Date: Fri, 8 Apr 2011 10:48:15 +0000 (+0200)
Subject: faulthandler: fix unregister() if it is called before register()
X-Git-Tag: v3.3.0a1~2644
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=cfa7123ef108452dd402e3cdcec772be28872e2f;p=python

faulthandler: fix unregister() if it is called before register()

Fix a crash: don't read from NULL.
---

diff --git a/Doc/library/faulthandler.rst b/Doc/library/faulthandler.rst
index 106da45b4c..c0b662502f 100644
--- a/Doc/library/faulthandler.rst
+++ b/Doc/library/faulthandler.rst
@@ -97,7 +97,8 @@ Dump the traceback on a user signal
 .. function:: unregister(signum)
 
    Unregister a user signal: uninstall the handler of the *signum* signal
-   installed by :func:`register`.
+   installed by :func:`register`. Return ``True`` if the signal was registered,
+   ``False`` otherwise.
 
    Not available on Windows.
 
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index 76cadf382c..113203692c 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -694,6 +694,9 @@ faulthandler_unregister_py(PyObject *self, PyObject *args)
     if (!check_signum(signum))
         return NULL;
 
+    if (user_signals == NULL)
+        Py_RETURN_FALSE;
+
     user = &user_signals[signum];
     change = faulthandler_unregister(user, signum);
     return PyBool_FromLong(change);