(merge) Issue #11395: io.FileIO().write() clamps the data length to 32,767
bytes on Windows if the file is a TTY to workaround a Windows bug. The Windows
console returns an error (12: not enough space error) on writing into stdout if
stdout mode is binary and the length is greater than 66,000 bytes (or less,
depending on heap usage).
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index e40f763..35aa7fa 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -97,6 +97,25 @@
self.assertEqual(fobj.read().splitlines(),
[b"bacon", b"eggs", b"spam"])
+ def write_windows_console(self, *args):
+ retcode = subprocess.call(args,
+ # use a new console to not flood the test output
+ creationflags=subprocess.CREATE_NEW_CONSOLE,
+ # use a shell to hide the console window (SW_HIDE)
+ shell=True)
+ self.assertEqual(retcode, 0)
+
+ @unittest.skipUnless(sys.platform == 'win32',
+ 'test specific to the Windows console')
+ def test_write_windows_console(self):
+ # Issue #11395: the Windows console returns an error (12: not enough
+ # space error) on writing into stdout if stdout mode is binary and the
+ # length is greater than 66,000 bytes (or less, depending on heap
+ # usage).
+ code = "print('x' * 100000)"
+ self.write_windows_console(sys.executable, "-c", code)
+ self.write_windows_console(sys.executable, "-u", "-c", code)
+
class TemporaryFileTests(unittest.TestCase):
def setUp(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index 3101327..d55c888 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,12 @@
Core and Builtins
-----------------
+- Issue #11395: io.FileIO().write() clamps the data length to 32,767 bytes on
+ Windows if the file is a TTY to workaround a Windows bug. The Windows console
+ returns an error (12: not enough space error) on writing into stdout if
+ stdout mode is binary and the length is greater than 66,000 bytes (or less,
+ depending on heap usage).
+
- Issue #11320: fix bogus memory management in Modules/getpath.c, leading to
a possible crash when calling Py_SetPath().
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index f96f2e2..1aa5ee9 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -712,7 +712,14 @@
errno = 0;
len = pbuf.len;
#if defined(MS_WIN64) || defined(MS_WINDOWS)
- if (len > INT_MAX)
+ if (len > 32767 && isatty(self->fd)) {
+ /* Issue #11395: the Windows console returns an error (12: not
+ enough space error) on writing into stdout if stdout mode is
+ binary and the length is greater than 66,000 bytes (or less,
+ depending on heap usage). */
+ len = 32767;
+ }
+ else if (len > INT_MAX)
len = INT_MAX;
n = write(self->fd, pbuf.buf, (int)len);
#else