Followup of #4705: we can't skip the binary buffering layer for stdin because FileIO doesn't have a read1() method
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 6819be5..65c6f5f 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -739,7 +739,12 @@
PyObject *line_buffering;
int buffering, isatty;
- if (Py_UnbufferedStdioFlag)
+ /* stdin is always opened in buffered mode, first because it shouldn't
+ make a difference in common use cases, second because TextIOWrapper
+ depends on the presence of a read1() method which only exists on
+ buffered streams.
+ */
+ if (Py_UnbufferedStdioFlag && write_mode)
buffering = 0;
else
buffering = -1;
@@ -753,7 +758,7 @@
if (buf == NULL)
goto error;
- if (!Py_UnbufferedStdioFlag) {
+ if (buffering) {
raw = PyObject_GetAttrString(buf, "raw");
if (raw == NULL)
goto error;