bpo-28856: Let %b format for bytes support objects that follow the buffer protocol (GH-664)
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 801711f..30c1a7e 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -528,6 +528,8 @@
return 0;
}
+static PyObject *_PyBytes_FromBuffer(PyObject *x);
+
static PyObject *
format_obj(PyObject *v, const char **pbuf, Py_ssize_t *plen)
{
@@ -564,8 +566,19 @@
*plen = PyBytes_GET_SIZE(result);
return result;
}
+ /* does it support buffer protocol? */
+ if (PyObject_CheckBuffer(v)) {
+ /* maybe we can avoid making a copy of the buffer object here? */
+ result = _PyBytes_FromBuffer(v);
+ if (result == NULL)
+ return NULL;
+ *pbuf = PyBytes_AS_STRING(result);
+ *plen = PyBytes_GET_SIZE(result);
+ return result;
+ }
PyErr_Format(PyExc_TypeError,
- "%%b requires bytes, or an object that implements __bytes__, not '%.100s'",
+ "%%b requires a bytes-like object, "
+ "or an object that implements __bytes__, not '%.100s'",
Py_TYPE(v)->tp_name);
return NULL;
}