Fix for trackfd=False. Raise ValueError instead of OSError.

Author: serhiy-storchaka

Lib/test/test_mmap.py

@@ -282,9 +282,8 @@ def test_trackfd_parameter(self):
                         if close_original_fd:
                             f.close()
                         self.assertEqual(len(m), size)
-                        with self.assertRaises(OSError) as err_cm:
+                        with self.assertRaises(ValueError):
                             m.size()
-                        self.assertEqual(err_cm.exception.errno, errno.EBADF)
                         with self.assertRaises(ValueError):
                             m.resize(size * 2)
                         with self.assertRaises(ValueError):
@@ -309,7 +308,7 @@ def test_trackfd_parameter(self):
     def test_trackfd_neg1(self):
         size = 64
         with mmap.mmap(-1, size, trackfd=False) as m:
-            with self.assertRaises(OSError):
+            with self.assertRaises(ValueError):
                 m.size()
             with self.assertRaises(ValueError):
                 m.resize(size // 2)

Misc/NEWS.d/next/Library/2021-03-07-16-31-36.bpo-43429.Koa0mf.rst

@@ -2,3 +2,4 @@ The :meth:`~mmap.mmap.size` method of the :class:`mmap.mmap` class now
 returns the size of an anonymous mapping on both Unix and Windows.
 Previously, the size would be returned on Windows and an :exc:`OSError`
 would be raised on Unix.
+Raise :exc:`ValueError` instead of :exc:`OSError` with ``trackfd=False``.

Modules/mmapmodule.c

@@ -740,10 +740,7 @@ mmap_size_method(PyObject *op, PyObject *Py_UNUSED(ignored))
 #endif /* MS_WINDOWS */
 
 #ifdef UNIX
-    {
-        if (self->fd == -1) {
-            return PyLong_FromSsize_t(self->size);
-        }
+    if (self->fd != -1) {
         struct _Py_stat_struct status;
         if (_Py_fstat(self->fd, &status) == -1)
             return NULL;
@@ -753,6 +750,14 @@ mmap_size_method(PyObject *op, PyObject *Py_UNUSED(ignored))
         return PyLong_FromLong(status.st_size);
 #endif
     }
+    else if (self->trackfd) {
+        return PyLong_FromSsize_t(self->size);
+    }
+    else {
+        PyErr_SetString(PyExc_ValueError,
+            "can't get size with trackfd=False");
+        return NULL;
+    }
 #endif /* UNIX */
 }