pythongh-120057: Add os.get_user_default_environ()

Doc/library/os.rst

@@ -197,6 +197,10 @@ process and user.
    changes to the environment made by :func:`os.putenv`, by
    :func:`os.unsetenv`, or made outside Python in the same process.
 
+   On Windows, :func:`get_user_default_environ` can be used to update
+   :data:`os.environ` to the latest system environment variables, such as the
+   ``PATH`` variable.
+
    This mapping may be used to modify the environment as well as query the
    environment.  :func:`putenv` will be called automatically when the mapping
    is modified.
@@ -326,6 +330,8 @@ process and user.
    and ``'surrogateescape'`` error handler. Use :func:`os.getenvb` if you
    would like to use a different encoding.
 
+   See also the :data:`os.environ.refresh() <os.environ>` method.
+
    .. availability:: Unix, Windows.
 
 
@@ -357,6 +363,22 @@ process and user.
    .. versionadded:: 3.2
 
 
+.. function:: get_user_default_environ()
+
+   Get the default environment of the current process user as a dictionary.
+
+   It can be used to update :data:`os.environ` to the latest system environment
+   variables, such as the ``PATH`` variable. Example::
+
+       os.environ.update(os.get_user_default_environ())
+
+   See also the :data:`os.environ.refresh() <os.environ>` method.
+
+   .. availability:: Windows.
+
+   .. versionadded:: 3.14
+
+
 .. function:: getegid()
 
    Return the effective group id of the current process.  This corresponds to the

Doc/whatsnew/3.14.rst

@@ -100,6 +100,11 @@ os
   by :func:`os.unsetenv`, or made outside Python in the same process.
   (Contributed by Victor Stinner in :gh:`120057`.)
 
+* Added the :func:`os.get_user_default_environ` function to get the user
+  default environment. It can be used to update :data:`os.environ` to the
+  latest system environment variables, such as the ``PATH`` variable.
+  (Contributed by Victor Stinner in :gh:`120057`.)
+
 symtable
 --------
 

Lib/os.py

@@ -96,6 +96,10 @@ def _get_exports_list(module):
         from nt import _create_environ
     except ImportError:
         pass
+    try:
+        from nt import _get_user_default_environ
+    except ImportError:
+        pass
 
 else:
     raise ImportError('no os specific module found')
@@ -826,6 +830,20 @@ def decode(value):
 del _create_environ_mapping
 
 
+if _exists("_get_user_default_environ"):
+    def get_user_default_environ():
+        env = {}
+        env_str = _get_user_default_environ()
+        for entry in env_str.split('\0'):
+            parts = entry.split('=', 1)
+            if len(parts) != 2:
+                # Skip names that begin with '='
+                continue
+            name, value = parts
+            env[name] = value
+        return env
+
+
 def getenv(key, default=None):
     """Get an environment variable, return None if it doesn't exist.
     The optional second argument can specify an alternate default.

Lib/test/test_os.py

@@ -1345,6 +1345,17 @@ def test_refresh(self):
             self.assertNotIn(b'test_env', os.environb)
             self.assertNotIn('test_env', os.environ)
 
+    @unittest.skipUnless(hasattr(os, 'get_user_default_environ'),
+                         'need os.get_user_default_environ()')
+    def test_get_user_default_environ(self):
+        env = os.get_user_default_environ()
+        self.assertIsInstance(env, dict)
+        for name, value in env.items():
+            self.assertIsInstance(name, str)
+            self.assertIsInstance(value, str)
+            self.assertTrue(bool(name), name)  # must be not empty
+
+
 class WalkTests(unittest.TestCase):
     """Tests for os.walk()."""
     is_fwalk = False

Misc/NEWS.d/next/Library/2024-06-14-13-28-09.gh-issue-120057.GN0-d0.rst

@@ -0,0 +1,4 @@
+Added the :func:`os.get_user_default_environ` function to get the user
+default environment. It can be used to update :data:`os.environ` to the
+latest system environment variables, such as the ``PATH`` variable. Patch by
+Victor Stinner.

Modules/posixmodule.c

@@ -16823,6 +16823,70 @@ os__create_environ_impl(PyObject *module)
 }
 
 
+#ifdef MS_WINDOWS
+/*[clinic input]
+os._get_user_default_environ
+
+Get user default environment string.
+[clinic start generated code]*/
+
+static PyObject *
+os__get_user_default_environ_impl(PyObject *module)
+/*[clinic end generated code: output=6cce8c186a556ef0 input=e15b3d87fce12734]*/
+{
+    HINSTANCE hUserEnv = LoadLibraryW(L"USERENV");
+    if (!hUserEnv) {
+        goto error;
+    }
+
+    HINSTANCE (CALLBACK *pCreateEnvironmentBlock) (LPVOID, HANDLE, BOOL);
+    HINSTANCE (CALLBACK *pDestroyEnvironmentBlock) (LPVOID);
+
+    *(FARPROC*)&pCreateEnvironmentBlock = GetProcAddress(hUserEnv,
+                                                "CreateEnvironmentBlock");
+    if (!pCreateEnvironmentBlock) {
+        goto error;
+    }
+
+    *(FARPROC*)&pDestroyEnvironmentBlock = GetProcAddress(hUserEnv,
+                                                 "DestroyEnvironmentBlock");
+    if (!pDestroyEnvironmentBlock) {
+        goto error;
+    }
+
+    HANDLE htoken;
+    if (!OpenProcessToken(GetCurrentProcess(),
+                          TOKEN_DUPLICATE|TOKEN_QUERY,
+                          &htoken)) {
+        goto error;
+    }
+
+    PWCHAR env_str;
+    if (!pCreateEnvironmentBlock(&env_str, htoken, 0)) {
+        CloseHandle(htoken);
+        goto error;
+    }
+    CloseHandle(htoken);
+
+    Py_ssize_t len = wcslen(env_str);
+    while (!env_str[len+1] != 0) {
+        len++;
+        len += wcslen(env_str + len);
+    }
+
+    PyObject *str = PyUnicode_FromWideChar(env_str, len);
+    if (!pDestroyEnvironmentBlock(env_str)) {
+        Py_XDECREF(str);
+        goto error;
+    }
+    return str;
+
+error:
+    return PyErr_SetFromWindowsErr(0);
+}
+#endif  // MS_WINDOWS
+
+
 static PyMethodDef posix_methods[] = {
 
     OS_STAT_METHODDEF
@@ -17038,6 +17102,7 @@ static PyMethodDef posix_methods[] = {
     OS__INPUTHOOK_METHODDEF
     OS__IS_INPUTHOOK_INSTALLED_METHODDEF
     OS__CREATE_ENVIRON_METHODDEF
+    OS__GET_USER_DEFAULT_ENVIRON_METHODDEF
     {NULL,              NULL}            /* Sentinel */
 };