From 89719e1daf8b15810145baf56d984ecbc1bab7ef Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Wed, 30 Sep 2015 15:01:34 +0200
Subject: [PATCH] Issue #25182: Fix compilation on Windows

Restore also errno value before calling PyErr_SetFromErrno().
---
 Objects/fileobject.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 403d718dfe5..1a93a6dd6b2 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -376,7 +376,7 @@ stdprinter_write(PyStdPrinter_Object *self, PyObject *args)
     PyObject *bytes = NULL;
     char *str;
     Py_ssize_t n;
-    int _errno;
+    int err;
 
     if (self->fd < 0) {
         /* fd might be invalid on Windows
@@ -411,13 +411,16 @@ stdprinter_write(PyStdPrinter_Object *self, PyObject *args)
 #else
     n = write(self->fd, str, n);
 #endif
-    _errno = errno;
+    /* save errno, it can be modified indirectly by Py_XDECREF() */
+    err = errno;
     Py_END_ALLOW_THREADS
+
     Py_XDECREF(bytes);
 
     if (n < 0) {
-        if (_errno == EAGAIN)
+        if (err == EAGAIN)
             Py_RETURN_NONE;
+        errno = err;
         PyErr_SetFromErrno(PyExc_IOError);
         return NULL;
     }