pythongh-116646: Add limited C API support to AC fildes converter (python#116769)

Add tests on the "fildes" converter to _testclinic_limited.

Author: vstinner

Lib/test/test_clinic.py

@@ -3698,6 +3698,39 @@ def test_my_double_sum(self):
                 with self.assertRaises(TypeError):
                     func(1., "2")
 
+    def test_get_file_descriptor(self):
+        # test 'file descriptor' converter: call PyObject_AsFileDescriptor()
+        get_fd = _testclinic_limited.get_file_descriptor
+
+        class MyInt(int):
+            pass
+
+        class MyFile:
+            def __init__(self, fd):
+                self._fd = fd
+            def fileno(self):
+                return self._fd
+
+        for fd in (0, 1, 2, 5, 123_456):
+            self.assertEqual(get_fd(fd), fd)
+
+            myint = MyInt(fd)
+            self.assertEqual(get_fd(myint), fd)
+
+            myfile = MyFile(fd)
+            self.assertEqual(get_fd(myfile), fd)
+
+        with self.assertRaises(OverflowError):
+            get_fd(2**256)
+        with self.assertWarnsRegex(RuntimeWarning,
+                                   "bool is used as a file descriptor"):
+            get_fd(True)
+        with self.assertRaises(TypeError):
+            get_fd(1.0)
+        with self.assertRaises(TypeError):
+            get_fd("abc")
+        with self.assertRaises(TypeError):
+            get_fd(None)
 
 
 class PermutationTests(unittest.TestCase):

Modules/_testclinic_limited.c

@@ -105,12 +105,30 @@ my_double_sum_impl(PyObject *module, double x, double y)
 }
 
 
+/*[clinic input]
+get_file_descriptor -> int
+
+    file as fd: fildes
+    /
+
+Get a file descriptor.
+[clinic start generated code]*/
+
+static int
+get_file_descriptor_impl(PyObject *module, int fd)
+/*[clinic end generated code: output=80051ebad54db8a8 input=82e2a1418848cd5b]*/
+{
+    return fd;
+}
+
+
 static PyMethodDef tester_methods[] = {
     TEST_EMPTY_FUNCTION_METHODDEF
     MY_INT_FUNC_METHODDEF
     MY_INT_SUM_METHODDEF
     MY_FLOAT_SUM_METHODDEF
     MY_DOUBLE_SUM_METHODDEF
+    GET_FILE_DESCRIPTOR_METHODDEF
     {NULL, NULL}
 };
 

Modules/clinic/_testclinic_limited.c.h

@@ -3800,18 +3800,19 @@ class fildes_converter(CConverter):
     type = 'int'
     converter = '_PyLong_FileDescriptor_Converter'
 
-    def converter_init(self, *, accept: TypeSet = {int, NoneType}) -> None:
-        self.add_include('pycore_fileutils.h',
-                         '_PyLong_FileDescriptor_Converter()')
-
-    def _parse_arg(self, argname: str, displayname: str) -> str | None:
-        return self.format_code("""
-            {paramname} = PyObject_AsFileDescriptor({argname});
-            if ({paramname} == -1) {{{{
-                goto exit;
-            }}}}
-            """,
-            argname=argname)
+    def parse_arg(self, argname: str, displayname: str, *, limited_capi: bool) -> str | None:
+        if limited_capi:
+            return self.format_code("""
+                {paramname} = PyObject_AsFileDescriptor({argname});
+                if ({paramname} < 0) {{{{
+                    goto exit;
+                }}}}
+                """,
+                argname=argname)
+        else:
+            self.add_include('pycore_fileutils.h',
+                             '_PyLong_FileDescriptor_Converter()')
+            return super().parse_arg(argname, displayname, limited_capi=limited_capi)
 
 
 class float_converter(CConverter):