changeset:   101812:84c91d7d4667
parent:      101810:09ec7f7322b5
parent:      101811:4af64ab34eef
user:        Barry Warsaw <barry@python.org>
date:        Wed Jun 08 17:54:43 2016 -0400
files:       Lib/test/test_io.py Misc/NEWS Modules/_io/fileio.c
description:
Issue #27066: Fixed SystemError if a custom opener (for open()) returns a
negative number without setting an exception.


diff -r 09ec7f7322b5 -r 84c91d7d4667 Lib/test/test_io.py
--- a/Lib/test/test_io.py	Wed Jun 08 14:37:05 2016 -0400
+++ b/Lib/test/test_io.py	Wed Jun 08 17:54:43 2016 -0400
@@ -809,6 +809,22 @@
         with self.open("non-existent", "r", opener=opener) as f:
             self.assertEqual(f.read(), "egg\n")
 
+    def test_bad_opener_negative_1(self):
+        # Issue #27066.
+        def badopener(fname, flags):
+            return -1
+        with self.assertRaises(ValueError) as cm:
+            open('non-existent', 'r', opener=badopener)
+        self.assertEqual(str(cm.exception), 'opener returned -1')
+
+    def test_bad_opener_other_negative(self):
+        # Issue #27066.
+        def badopener(fname, flags):
+            return -2
+        with self.assertRaises(ValueError) as cm:
+            open('non-existent', 'r', opener=badopener)
+        self.assertEqual(str(cm.exception), 'opener returned -2')
+
     def test_fileio_closefd(self):
         # Issue #4841
         with self.open(__file__, 'rb') as f1, \
diff -r 09ec7f7322b5 -r 84c91d7d4667 Misc/NEWS
--- a/Misc/NEWS	Wed Jun 08 14:37:05 2016 -0400
+++ b/Misc/NEWS	Wed Jun 08 17:54:43 2016 -0400
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #27066: Fixed SystemError if a custom opener (for open()) returns a
+  negative number without setting an exception.
+
 - Issue #26983: float() now always return an instance of exact float.
   The deprecation warning is emitted if __float__ returns an instance of
   a strict subclass of float.  In a future versions of Python this can
diff -r 09ec7f7322b5 -r 84c91d7d4667 Modules/_io/fileio.c
--- a/Modules/_io/fileio.c	Wed Jun 08 14:37:05 2016 -0400
+++ b/Modules/_io/fileio.c	Wed Jun 08 17:54:43 2016 -0400
@@ -420,7 +420,13 @@
 
             self->fd = _PyLong_AsInt(fdobj);
             Py_DECREF(fdobj);
-            if (self->fd == -1) {
+            if (self->fd < 0) {
+                if (!PyErr_Occurred()) {
+                    /* The opener returned a negative but didn't set an
+                       exception.  See issue #27066 */
+                    PyErr_Format(PyExc_ValueError,
+                                 "opener returned %d", self->fd);
+                }
                 goto error;
             }
         }