bpo-20443: _PyConfig_Read() gets the absolute path of run_filename (GH-14053)

Python now gets the absolute path of the script filename specified on
the command line (ex: "python3 script.py"): the __file__ attribute of
the __main__ module, sys.argv[0] and sys.path[0] become an absolute
path, rather than a relative path.

* Add _Py_isabs() and _Py_abspath() functions.
* _PyConfig_Read() now tries to get the absolute path of
  run_filename, but keeps the relative path if _Py_abspath() fails.
* Reimplement os._getfullpathname() using _Py_abspath().
* Use _Py_isabs() in getpath.c.

1 files changed, 9 insertions, 10 deletions

diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index 86c2f22..be848b2 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -926,27 +926,26 @@ class PyWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
             return stderr
 
         # tracemalloc disabled
+        filename = os.path.abspath(support.TESTFN)
         stderr = run('-Wd', support.TESTFN)
-        expected = textwrap.dedent('''
-            {fname}:5: ResourceWarning: unclosed file <...>
+        expected = textwrap.dedent(f'''
+            {filename}:5: ResourceWarning: unclosed file <...>
               f = None
             ResourceWarning: Enable tracemalloc to get the object allocation traceback
-        ''')
-        expected = expected.format(fname=support.TESTFN).strip()
+        ''').strip()
         self.assertEqual(stderr, expected)
 
         # tracemalloc enabled
         stderr = run('-Wd', '-X', 'tracemalloc=2', support.TESTFN)
-        expected = textwrap.dedent('''
-            {fname}:5: ResourceWarning: unclosed file <...>
+        expected = textwrap.dedent(f'''
+            {filename}:5: ResourceWarning: unclosed file <...>
               f = None
             Object allocated at (most recent call last):
-              File "{fname}", lineno 7
+              File "{filename}", lineno 7
                 func()
-              File "{fname}", lineno 3
+              File "{filename}", lineno 3
                 f = open(__file__)
-        ''')
-        expected = expected.format(fname=support.TESTFN).strip()
+        ''').strip()
         self.assertEqual(stderr, expected)