Replace stat.ST_xxx usage with os.stat().st_xxx (#116501)

Modernize code to use the new API which avoids the usage of the stat
module just to read os.stat() members.

* Sort logging.handlers imports.
* Rework reopenIfNeeded() code to make it easier to follow.
* Replace "not self.stream" with "self.stream is None".

Author: vstinner

Lib/logging/handlers.py

@@ -23,11 +23,17 @@
 To use, simply 'import logging.handlers' and log away!
 """
 
-import io, logging, socket, os, pickle, struct, time, re
-from stat import ST_DEV, ST_INO, ST_MTIME
+import copy
+import io
+import logging
+import os
+import pickle
 import queue
+import re
+import socket
+import struct
 import threading
-import copy
+import time
 
 #
 # Some constants...
@@ -269,7 +275,7 @@ def __init__(self, filename, when='h', interval=1, backupCount=0,
         # path object (see Issue #27493), but self.baseFilename will be a string
         filename = self.baseFilename
         if os.path.exists(filename):
-            t = os.stat(filename)[ST_MTIME]
+            t = int(os.stat(filename).st_mtime)
         else:
             t = int(time.time())
         self.rolloverAt = self.computeRollover(t)
@@ -459,8 +465,7 @@ class WatchedFileHandler(logging.FileHandler):
     This handler is not appropriate for use under Windows, because
     under Windows open files cannot be moved or renamed - logging
     opens the files with exclusive locks - and so there is no need
-    for such a handler. Furthermore, ST_INO is not supported under
-    Windows; stat always returns zero for this value.
+    for such a handler.
 
     This handler is based on a suggestion and patch by Chad J.
     Schroeder.
@@ -476,9 +481,11 @@ def __init__(self, filename, mode='a', encoding=None, delay=False,
         self._statstream()
 
     def _statstream(self):
-        if self.stream:
-            sres = os.fstat(self.stream.fileno())
-            self.dev, self.ino = sres[ST_DEV], sres[ST_INO]
+        if self.stream is None:
+            return
+        sres = os.fstat(self.stream.fileno())
+        self.dev = sres.st_dev
+        self.ino = sres.st_ino
 
     def reopenIfNeeded(self):
         """
@@ -488,25 +495,33 @@ def reopenIfNeeded(self):
         has, close the old stream and reopen the file to get the
         current stream.
         """
+        if self.stream is None:
+            return
+
         # Reduce the chance of race conditions by stat'ing by path only
         # once and then fstat'ing our new fd if we opened a new log stream.
         # See issue #14632: Thanks to John Mulligan for the problem report
         # and patch.
         try:
             # stat the file by path, checking for existence
             sres = os.stat(self.baseFilename)
+
+            # compare file system stat with that of our stream file handle
+            reopen = (sres.st_dev != self.dev or sres.st_ino != self.ino)
         except FileNotFoundError:
-            sres = None
-        # compare file system stat with that of our stream file handle
-        if not sres or sres[ST_DEV] != self.dev or sres[ST_INO] != self.ino:
-            if self.stream is not None:
-                # we have an open file handle, clean it up
-                self.stream.flush()
-                self.stream.close()
-                self.stream = None  # See Issue #21742: _open () might fail.
-                # open a new file handle and get new stat info from that fd
-                self.stream = self._open()
-                self._statstream()
+            reopen = True
+
+        if not reopen:
+            return
+
+        # we have an open file handle, clean it up
+        self.stream.flush()
+        self.stream.close()
+        self.stream = None  # See Issue #21742: _open () might fail.
+
+        # open a new file handle and get new stat info from that fd
+        self.stream = self._open()
+        self._statstream()
 
     def emit(self, record):
         """

Lib/test/test_largefile.py

@@ -2,7 +2,6 @@
 """
 
 import os
-import stat
 import sys
 import unittest
 import socket
@@ -29,7 +28,7 @@ def setUp(self):
             mode = 'w+b'
 
         with self.open(TESTFN, mode) as f:
-            current_size = os.fstat(f.fileno())[stat.ST_SIZE]
+            current_size = os.fstat(f.fileno()).st_size
             if current_size == size+1:
                 return
 
@@ -40,13 +39,13 @@ def setUp(self):
             f.seek(size)
             f.write(b'a')
             f.flush()
-            self.assertEqual(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
+            self.assertEqual(os.fstat(f.fileno()).st_size, size+1)
 
     @classmethod
     def tearDownClass(cls):
         with cls.open(TESTFN, 'wb'):
             pass
-        if not os.stat(TESTFN)[stat.ST_SIZE] == 0:
+        if not os.stat(TESTFN).st_size == 0:
             raise cls.failureException('File was not truncated by opening '
                                        'with mode "wb"')
         unlink(TESTFN2)
@@ -67,7 +66,7 @@ def test_large_read(self, _size):
             self.assertEqual(f.tell(), size + 1)
 
     def test_osstat(self):
-        self.assertEqual(os.stat(TESTFN)[stat.ST_SIZE], size+1)
+        self.assertEqual(os.stat(TESTFN).st_size, size+1)
 
     def test_seek_read(self):
         with self.open(TESTFN, 'rb') as f:

Lib/test/test_mailbox.py

@@ -702,8 +702,7 @@ def _check_basics(self, factory=None):
         self.assertEqual(self._box._factory, factory)
         for subdir in '', 'tmp', 'new', 'cur':
             path = os.path.join(self._path, subdir)
-            mode = os.stat(path)[stat.ST_MODE]
-            self.assertTrue(stat.S_ISDIR(mode), "Not a directory: '%s'" % path)
+            self.assertTrue(os.path.isdir(path), f"Not a directory: {path!r}")
 
     def test_list_folders(self):
         # List folders