From ae62f015240c9162773341a9922794e6b960779d Mon Sep 17 00:00:00 2001
From: Zackery Spytz <zspytz@gmail.com>
Date: Sat, 6 Oct 2018 00:44:25 -0600
Subject: [PATCH] bpo-34910: Ensure that PyObject_Print() always returns -1 on
 error. (GH-9733)

---
 .../next/C API/2018-10-05-17-06-49.bpo-34910.tSFrls.rst      | 2 ++
 Objects/object.c                                             | 5 +++--
 2 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/C API/2018-10-05-17-06-49.bpo-34910.tSFrls.rst

diff --git a/Misc/NEWS.d/next/C API/2018-10-05-17-06-49.bpo-34910.tSFrls.rst b/Misc/NEWS.d/next/C API/2018-10-05-17-06-49.bpo-34910.tSFrls.rst
new file mode 100644
index 00000000000..eff4755d8d5
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2018-10-05-17-06-49.bpo-34910.tSFrls.rst	
@@ -0,0 +1,2 @@
+Ensure that :c:func:`PyObject_Print` always returns ``-1`` on error.  Patch
+by Zackery Spytz.
diff --git a/Objects/object.c b/Objects/object.c
index 607f047d147..ab1baa70d43 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -375,8 +375,9 @@ PyObject_Print(PyObject *op, FILE *fp, int flags)
             else if (PyUnicode_Check(s)) {
                 PyObject *t;
                 t = PyUnicode_AsEncodedString(s, "utf-8", "backslashreplace");
-                if (t == NULL)
-                    ret = 0;
+                if (t == NULL) {
+                    ret = -1;
+                }
                 else {
                     fwrite(PyBytes_AS_STRING(t), 1,
                            PyBytes_GET_SIZE(t), fp);