gh-87901: os.popen: Fix new encoding argument.

Doc/library/os.rst

@@ -3916,13 +3916,13 @@ written in Python, such as a mail server's external command delivery program.
    .. availability:: Unix.
 
 
-.. function:: popen(cmd, mode='r', buffering=-1, encoding=None)
+.. function:: popen(cmd, mode='r', buffering=-1, *, encoding=None, errors=None)
 
    Open a pipe to or from command *cmd*.
    The return value is an open file object
    connected to the pipe, which can be read or written depending on whether *mode*
    is ``'r'`` (default) or ``'w'``.
-   The *buffering* and *encoding* arguments have the same meaning as
+   The *buffering*, *encoding*, and *errors* arguments have the same meaning as
    the corresponding argument to the built-in :func:`open` function. The
    returned file object reads or writes text strings rather than bytes.
 
@@ -3946,7 +3946,7 @@ written in Python, such as a mail server's external command delivery program.
    subprocesses.
 
    .. versionchanged:: 3.11
-      Added the *encoding* parameter.
+      Added the *encoding* and *errors* parameters.
 
 
 .. function:: posix_spawn(path, argv, env, *, file_actions=None, \

Lib/os.py

@@ -974,7 +974,7 @@ def spawnlpe(mode, file, *args):
 # command in a shell can't be supported.
 if sys.platform != 'vxworks':
     # Supply os.popen()
-    def popen(cmd, mode="r", buffering=-1, encoding=None):
+    def popen(cmd, mode="r", buffering=-1, *, encoding=None, errors=None):
         if not isinstance(cmd, str):
             raise TypeError("invalid cmd type (%s, expected string)" % type(cmd))
         if mode not in ("r", "w"):
@@ -985,13 +985,13 @@ def popen(cmd, mode="r", buffering=-1, encoding=None):
         encoding = io.text_encoding(encoding)
         if mode == "r":
             proc = subprocess.Popen(cmd,
-                                    shell=True, text=True,
+                                    shell=True, encoding=encoding, errors=errors,
                                     stdout=subprocess.PIPE,
                                     bufsize=buffering)
             return _wrap_close(proc.stdout, proc)
         else:
             proc = subprocess.Popen(cmd,
-                                    shell=True, text=True,
+                                    shell=True, encoding=encoding, errors=errors,
                                     stdin=subprocess.PIPE,
                                     bufsize=buffering)
             return _wrap_close(proc.stdin, proc)

Lib/test/test_os.py

@@ -167,6 +167,13 @@ def test_getcwdb(self):
         self.assertIsInstance(cwd, bytes)
         self.assertEqual(os.fsdecode(cwd), os.getcwd())
 
+    @unittest.skipUnless(hasattr(os, 'popen'), "needs os.popen()")
+    @support.requires_subprocess()
+    def test_popen_encoding(self):
+        cmd = f"""{sys.executable} -c "import sys; sys.stdout.buffer.write(b'\\xc0')" """
+        with os.popen(cmd, encoding="latin1") as p:
+            self.assertEqual(p.read(), "\xc0")
+
 
 # Tests creating TESTFN
 class FileTests(unittest.TestCase):

Misc/NEWS.d/next/Library/2022-05-13-05-27-07.gh-issue-87901.gct4iY.rst

@@ -0,0 +1,2 @@
+Fix ``encoding`` argument of :func:`os.popen` and added ``errors`` argument
+too.