Issue #18343: faulthandler.register() now keeps the previous signal handler

when the function is called twice, so faulthandler.unregister() restores
correctly the original signal handler.

2 files changed, 6 insertions, 1 deletions

diff --git a/Misc/NEWS b/Misc/NEWS
index dd6d8d1..c887f35 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -41,6 +41,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #18343: faulthandler.register() now keeps the previous signal handler
+  when the function is called twice, so faulthandler.unregister() restores
+  correctly the original signal handler.
+
 - Issue #17097: Make multiprocessing ignore EINTR.
 
 - Issue #18339: Negative ints keys in unpickler.memo dict no longer cause a
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index 7e363f0..c86a27f 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -742,6 +742,8 @@ faulthandler_register_py(PyObject *self,
             PyErr_SetFromErrno(PyExc_OSError);
             return NULL;
         }
+
+        user->previous = previous;
     }
 
     Py_XDECREF(user->file);
@@ -750,7 +752,6 @@ faulthandler_register_py(PyObject *self,
     user->fd = fd;
     user->all_threads = all_threads;
     user->chain = chain;
-    user->previous = previous;
     user->interp = tstate->interp;
     user->enabled = 1;