[Python-checkins] bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data. (GH-5754)

[Miss Islington (bot)]

https://github.com/python/cpython/commit/e49bf0f353a968cddc4d8e6ea668b9d2d116e2ac
commit: e49bf0f353a968cddc4d8e6ea668b9d2d116e2ac
branch: 3.7
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2018-02-24T09:39:18-08:00
summary:

bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data. (GH-5754)

(cherry picked from commit 42c35d9c0c8175332f50fbe034a001fe52f057b9)

Co-authored-by: Serhiy Storchaka <storchaka at gmail.com>

files:
A Misc/NEWS.d/next/Windows/2018-02-19-13-54-42.bpo-31966._Q3HPb.rst
M Lib/test/test_winconsoleio.py
M Modules/_io/winconsoleio.c

diff --git a/Lib/test/test_winconsoleio.py b/Lib/test/test_winconsoleio.py
index 656483cf1621..a78fa4d7d919 100644
--- a/Lib/test/test_winconsoleio.py
+++ b/Lib/test/test_winconsoleio.py
@@ -121,6 +121,10 @@ def test_conout_path(self):
             else:
                 self.assertNotIsInstance(f, ConIO)
 
+    def test_write_empty_data(self):
+        with ConIO('CONOUT$', 'w') as f:
+            self.assertEqual(f.write(b''), 0)
+
     def assertStdinRoundTrip(self, text):
         stdin = open('CONIN$', 'r')
         old_stdin = sys.stdin
diff --git a/Misc/NEWS.d/next/Windows/2018-02-19-13-54-42.bpo-31966._Q3HPb.rst b/Misc/NEWS.d/next/Windows/2018-02-19-13-54-42.bpo-31966._Q3HPb.rst
new file mode 100644
index 000000000000..042a4d835abf
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2018-02-19-13-54-42.bpo-31966._Q3HPb.rst
@@ -0,0 +1 @@
+Fixed WindowsConsoleIO.write() for writing empty data.
diff --git a/Modules/_io/winconsoleio.c b/Modules/_io/winconsoleio.c
index 30d1c767afcf..b85c11b3405a 100644
--- a/Modules/_io/winconsoleio.c
+++ b/Modules/_io/winconsoleio.c
@@ -964,6 +964,9 @@ _io__WindowsConsoleIO_write_impl(winconsoleio *self, Py_buffer *b)
     if (!self->writable)
         return err_mode("writing");
 
+    if (!b->len) {
+        return PyLong_FromLong(0);
+    }
     if (b->len > BUFMAX)
         len = BUFMAX;
     else