bpo-40286: Add randbytes() method to random.Random (GH-19527)

Add random.randbytes() function and random.Random.randbytes()
method to generate random bytes.

Modify secrets.token_bytes() to use SystemRandom.randbytes()
rather than calling directly os.urandom().

Rename also genrand_int32() to genrand_uint32(), since it returns an
unsigned 32-bit integer, not a signed integer.

The _random module is now built with Py_BUILD_CORE_MODULE defined.

1 files changed, 42 insertions, 1 deletions

diff --git a/Modules/clinic/_randommodule.c.h b/Modules/clinic/_randommodule.c.h
index a467811..dda78f6 100644
--- a/Modules/clinic/_randommodule.c.h
+++ b/Modules/clinic/_randommodule.c.h
@@ -114,4 +114,45 @@ _random_Random_getrandbits(RandomObject *self, PyObject *arg)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=a7feb0c9c8d1b627 input=a9049054013a1b77]*/
+
+PyDoc_STRVAR(_random_Random_randbytes__doc__,
+"randbytes($self, n, /)\n"
+"--\n"
+"\n"
+"Generate n random bytes.");
+
+#define _RANDOM_RANDOM_RANDBYTES_METHODDEF    \
+    {"randbytes", (PyCFunction)_random_Random_randbytes, METH_O, _random_Random_randbytes__doc__},
+
+static PyObject *
+_random_Random_randbytes_impl(RandomObject *self, Py_ssize_t n);
+
+static PyObject *
+_random_Random_randbytes(RandomObject *self, PyObject *arg)
+{
+    PyObject *return_value = NULL;
+    Py_ssize_t n;
+
+    if (PyFloat_Check(arg)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    {
+        Py_ssize_t ival = -1;
+        PyObject *iobj = PyNumber_Index(arg);
+        if (iobj != NULL) {
+            ival = PyLong_AsSsize_t(iobj);
+            Py_DECREF(iobj);
+        }
+        if (ival == -1 && PyErr_Occurred()) {
+            goto exit;
+        }
+        n = ival;
+    }
+    return_value = _random_Random_randbytes_impl(self, n);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=e515c651860c4001 input=a9049054013a1b77]*/