From 52ee1dab95436128b44c37cc495022ff90108b2e Mon Sep 17 00:00:00 2001

From: Nikolaus Rath <Nikolaus@rath.org>

Date: Mon, 9 May 2022 10:04:30 +0100

Subject: [PATCH] Add nbdkit.parse_size() Python function.

This enables Python plugins to parse sizes the same way as C plugins.

I'm not sure about the best way to test this - input is appreciated.

I'm not too happy with the way this code is tested. It workes, but putting the tests into

test-python-plugin.py feels misplaced: this file is intended to support the unit tests in

test_python.py, not run its own unit tests.

(cherry picked from commit 1b7d72542be68e254c1ef86ecb1a82b05c78ff63)

---

 plugins/python/modfunctions.c           | 21 +++++++++++++++++++++

 plugins/python/nbdkit-python-plugin.pod |  5 +++++

 tests/test-python-plugin.py             | 19 +++++++++++++++++++

 3 files changed, 45 insertions(+)

diff --git a/plugins/python/modfunctions.c b/plugins/python/modfunctions.c

index fffbaab2..46b0c904 100644

--- a/plugins/python/modfunctions.c

+++ b/plugins/python/modfunctions.c

@@ -93,11 +93,32 @@ do_shutdown (PyObject *self, PyObject *args)

   Py_RETURN_NONE;

 }

+/* nbdkit.parse_size */

+static PyObject *

+parse_size (PyObject *self, PyObject *args)

+{

+  const char *s;

+  if (!PyArg_ParseTuple (args, "s", &s)) {

+    PyErr_SetString (PyExc_TypeError, "Expected string, got something else");

+    return NULL;

+  }

+

+  int64_t size = nbdkit_parse_size(s);

+  if (size == -1) {

+    PyErr_SetString (PyExc_ValueError, "Unable to parse string as size");

+    return NULL;

+  }

+

+  return PyLong_FromSize_t((size_t)size);

+}

+

 static PyMethodDef NbdkitMethods[] = {

   { "debug", debug, METH_VARARGS,

     "Print a debug message" },

   { "export_name", export_name, METH_VARARGS,

     "Return the optional export name negotiated with the client" },

+  { "parse_size", parse_size, METH_VARARGS,

+    "Parse human-readable size strings into bytes" },

   { "set_error", set_error, METH_VARARGS,

     "Store an errno value prior to throwing an exception" },

   { "shutdown", do_shutdown, METH_VARARGS,

diff --git a/plugins/python/nbdkit-python-plugin.pod b/plugins/python/nbdkit-python-plugin.pod

index 051b0237..ccc9406f 100644

--- a/plugins/python/nbdkit-python-plugin.pod

+++ b/plugins/python/nbdkit-python-plugin.pod

@@ -131,6 +131,11 @@ Record C<err> as the reason you are about to throw an exception. C<err>

 should correspond to usual errno values, where it may help to

 C<import errno>.

+=head3 C<nbdkit.parse_size(str)>

+

+Parse a string (such as "100M") into a size in bytes. Wraps the

+C<nbdkit_parse_size()> C function.

+

 =head3 C<nbdkit.shutdown()>

 Request asynchronous server shutdown.

diff --git a/tests/test-python-plugin.py b/tests/test-python-plugin.py

index 0b34d532..d4f379fc 100644

--- a/tests/test-python-plugin.py

+++ b/tests/test-python-plugin.py

@@ -34,12 +34,31 @@

 import nbdkit

 import pickle

 import base64

+import unittest

 API_VERSION = 2

 cfg = {}

+# Not nice, but there doesn't seem to be a better way of putting this

+class TestAPI(unittest.TestCase):

+

+    def test_parse_size(self):

+        self.assertEqual(nbdkit.parse_size('511'), 511)

+        self.assertEqual(nbdkit.parse_size('7k'), 7*1024)

+        self.assertEqual(nbdkit.parse_size('17M'), 17*1024*1024)

+

+        with self.assertRaises(TypeError):

+            nbdkit.parse_size(17)

+

+        with self.assertRaises(ValueError):

+            nbdkit.parse_size('foo')

+

+

+TestAPI().test_parse_size()

+

+

 def config(k, v):

     global cfg

     if k == "cfg":

-- 

2.31.1