better error if sys.stderr is None

Issue #21497: faulthandler functions now raise a better error if
sys.stderr is None: RuntimeError("sys.stderr is None") instead of
AttributeError("'NoneType' object has no attribute 'fileno'").

Set also version to 2.4.

doc/index.rst

@@ -210,6 +210,13 @@ faulthandler.__version__ is the module version as a string (e.g. "2.0").
 Changelog
 =========
 
+Version 2.4
+-----------
+
+* Python issue #21497: faulthandler functions now raise a better error if
+  ``sys.stderr`` is ``None``: RuntimeError("sys.stderr is None") instead of
+  AttributeError("'NoneType' object has no attribute 'fileno'").
+
 Version 2.3 (2013-12-17)
 ------------------------
 

faulthandler.c

@@ -8,7 +8,7 @@
 #include "pythread.h"
 #include <signal.h>
 
-#define VERSION 0x203
+#define VERSION 0x204
 
 /* Allocate at maximum 100 MB of the stack to raise the stack overflow */
 #define STACK_OVERFLOW_MAX_SIZE (100*1024*1024)
@@ -157,6 +157,10 @@ faulthandler_get_fileno(PyObject *file, int *p_fd)
             PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr");
             return NULL;
         }
+        if (file == Py_None) {
+            PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");
+            return NULL;
+        }
     }
 
     result = PyObject_CallMethod(file, "fileno", "");
@@ -316,7 +320,7 @@ faulthandler_fatal_error(int signum)
         return;
     }
 #endif
-    /* call the previous signal handler: it is called immediatly if we use
+    /* call the previous signal handler: it is called immediately if we use
        sigaction() thanks to SA_NODEFER flag, otherwise it is deferred */
     raise(signum);
 }

setup.py

@@ -41,7 +41,7 @@
     print("ERROR: faulthandler is a builtin module since Python 3.3")
     sys.exit(1)
 
-VERSION = "2.3"
+VERSION = "2.4"
 
 FILES = ['faulthandler.c', 'traceback.c']