From c713837e91f39dc18740c74729cb7cebcf54fe6e Mon Sep 17 00:00:00 2001
From: Antoine Pitrou <pitrou@free.fr>
Date: Fri, 3 Nov 2017 20:36:39 +0100
Subject: [2.7] bpo-30057: Fix potential missed signal in signal.signal().
 (GH-4258) (#4263)

Bug report and patch by Jeroen Demeyer..
(cherry picked from commit f6f90ff079a22b79a58d47b6117cc8a8c7d366f3)
---
 Modules/signalmodule.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'Modules/signalmodule.c')

diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index c7bf1f0853..ef70d10bb1 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -317,12 +317,15 @@ signal_signal(PyObject *self, PyObject *args)
     }
     else
         func = signal_handler;
+    /* Check for pending signals before changing signal handler */
+    if (PyErr_CheckSignals()) {
+        return NULL;
+    }
     if (PyOS_setsig(sig_num, func) == SIG_ERR) {
         PyErr_SetFromErrno(PyExc_RuntimeError);
         return NULL;
     }
     old_handler = Handlers[sig_num].func;
-    Handlers[sig_num].tripped = 0;
     Py_INCREF(obj);
     Handlers[sig_num].func = obj;
     if (old_handler != NULL)
-- 
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