bpo-42260: Compute the path config in the main init (GH-23211)

The path configuration is now computed in the "main" initialization. The core initialization no longer computes it. * Add _PyConfig_Read() function to read the configuration without computing the path configuration. * pyinit_core() no longer computes the path configuration: it is now computed by init_interp_main(). * The path configuration output members of PyConfig are now optional: * executable * base_executable * prefix * base_prefix * exec_prefix * base_exec_prefix * _PySys_UpdateConfig() now skips NULL strings in PyConfig. * _testembed: Rename test_set_config() to test_init_set_config() for consistency with other tests.

Author: vstinner

Include/internal/pycore_initconfig.h

@@ -152,6 +152,7 @@ extern PyStatus _PyConfig_Copy(
  PyConfig *config,
  const PyConfig *config2);
 extern PyStatus _PyConfig_InitPathConfig(PyConfig *config);
+extern PyStatus _PyConfig_Read(PyConfig *config, int compute_path_config);
 extern PyStatus _PyConfig_Write(const PyConfig *config,
  struct pyruntimestate *runtime);
 extern PyStatus _PyConfig_SetPyArgv(

Lib/test/_test_embed_set_config.py

@@ -100,19 +100,19 @@ def test_set_invalid(self):
  'check_hash_pycs_mode',
  'program_name',
  'platlibdir',
- 'executable',
- 'base_executable',
- 'prefix',
- 'base_prefix',
- 'exec_prefix',
- 'base_exec_prefix',
  # optional wstr:
  # 'pythonpath_env'
- # 'home',
+ # 'home'
  # 'pycache_prefix'
  # 'run_command'
  # 'run_module'
  # 'run_filename'
+ # 'executable'
+ # 'prefix'
+ # 'exec_prefix'
+ # 'base_executable'
+ # 'base_prefix'
+ # 'base_exec_prefix'
  ):
  value_tests.append((key, invalid_wstr))
  type_tests.append((key, b'bytes'))
@@ -217,6 +217,18 @@ def test_pathconfig(self):
  self.set_config(base_executable="base_executable")
  self.assertEqual(sys._base_executable, "base_executable")
 
+ # When base_xxx is NULL, value is copied from xxxx
+ self.set_config(
+ executable='executable',
+ prefix="prefix",
+ exec_prefix="exec_prefix",
+ base_executable=None,
+ base_prefix=None,
+ base_exec_prefix=None)
+ self.assertEqual(sys._base_executable, "executable")
+ self.assertEqual(sys.base_prefix, "prefix")
+ self.assertEqual(sys.base_exec_prefix, "exec_prefix")
+
  def test_path(self):
  self.set_config(module_search_paths_set=1,
  module_search_paths=['a', 'b', 'c'])

Programs/_testembed.c

@@ -1547,7 +1547,7 @@ static int tune_config(void)
 }
 
 
-static int test_set_config(void)
+static int test_init_set_config(void)
 {
  // Initialize core
  PyConfig config;
@@ -1742,7 +1742,7 @@ static struct TestCase TestCases[] = {
  {"test_init_setpath_config", test_init_setpath_config},
  {"test_init_setpythonhome", test_init_setpythonhome},
  {"test_init_warnoptions", test_init_warnoptions},
- {"test_init_set_config", test_set_config},
+ {"test_init_set_config", test_init_set_config},
  {"test_run_main", test_run_main},
  {"test_get_argc_argv", test_get_argc_argv},
 

Python/initconfig.c

@@ -619,15 +619,6 @@ config_check_consistency(const PyConfig *config)
  assert(_PyWideStringList_CheckConsistency(&config->warnoptions));
  assert(_PyWideStringList_CheckConsistency(&config->module_search_paths));
  assert(config->module_search_paths_set >= 0);
- if (config->_install_importlib) {
- /* don't check config->module_search_paths */
- assert(config->executable != NULL);
- assert(config->base_executable != NULL);
- assert(config->prefix != NULL);
- assert(config->base_prefix != NULL);
- assert(config->exec_prefix != NULL);
- assert(config->base_exec_prefix != NULL);
- }
  assert(config->platlibdir != NULL);
  assert(config->filesystem_encoding != NULL);
  assert(config->filesystem_errors != NULL);
@@ -1297,24 +1288,15 @@ _PyConfig_FromDict(PyConfig *config, PyObject *dict)
  GET_WSTR_OPT(home);
  GET_WSTR(platlibdir);
 
+ // Path configuration output
  GET_UINT(module_search_paths_set);
  GET_WSTRLIST(module_search_paths);
- if (config->_install_importlib) {
- GET_WSTR(executable);
- GET_WSTR(base_executable);
- GET_WSTR(prefix);
- GET_WSTR(base_prefix);
- GET_WSTR(exec_prefix);
- GET_WSTR(base_exec_prefix);
- }
- else {
- GET_WSTR_OPT(executable);
- GET_WSTR_OPT(base_executable);
- GET_WSTR_OPT(prefix);
- GET_WSTR_OPT(base_prefix);
- GET_WSTR_OPT(exec_prefix);
- GET_WSTR_OPT(base_exec_prefix);
- }
+ GET_WSTR_OPT(executable);
+ GET_WSTR_OPT(base_executable);
+ GET_WSTR_OPT(prefix);
+ GET_WSTR_OPT(base_prefix);
+ GET_WSTR_OPT(exec_prefix);
+ GET_WSTR_OPT(base_exec_prefix);
 
  GET_UINT(skip_source_first_line);
  GET_WSTR_OPT(run_command);
@@ -2043,7 +2025,7 @@ config_init_fs_encoding(PyConfig *config, const PyPreConfig *preconfig)
 
 
 static PyStatus
-config_read(PyConfig *config)
+config_read(PyConfig *config, int compute_path_config)
 {
  PyStatus status;
  const PyPreConfig *preconfig = &_PyRuntime.preconfig;
@@ -2087,7 +2069,7 @@ config_read(PyConfig *config)
  }
  }
 
- if (config->_install_importlib) {
+ if (compute_path_config && config->_install_importlib) {
  status = _PyConfig_InitPathConfig(config);
  if (_PyStatus_EXCEPTION(status)) {
  return status;
@@ -2834,7 +2816,7 @@ PyConfig_SetWideStringList(PyConfig *config, PyWideStringList *list,
 
  The only side effects are to modify config and to call _Py_SetArgcArgv(). */
 PyStatus
-PyConfig_Read(PyConfig *config)
+_PyConfig_Read(PyConfig *config, int compute_path_config)
 {
  PyStatus status;
 
@@ -2877,7 +2859,7 @@ PyConfig_Read(PyConfig *config)
  goto done;
  }
 
- status = config_read(config);
+ status = config_read(config, compute_path_config);
  if (_PyStatus_EXCEPTION(status)) {
  goto done;
  }
@@ -2892,6 +2874,13 @@ PyConfig_Read(PyConfig *config)
 }
 
 
+PyStatus
+PyConfig_Read(PyConfig *config)
+{
+ return _PyConfig_Read(config, 1);
+}
+
+
 PyObject*
 _Py_GetConfigsAsDict(void)
 {

Python/pylifecycle.c

@@ -429,25 +429,20 @@ _Py_SetLocaleFromEnv(int category)
 
 
 static int
-interpreter_set_config(const PyConfig *config)
+interpreter_update_config(PyThreadState *tstate, int only_update_path_config)
 {
- PyThreadState *tstate = PyThreadState_Get();
+ const PyConfig *config = &tstate->interp->config;
 
- PyStatus status = _PyConfig_Write(config, tstate->interp->runtime);
- if (_PyStatus_EXCEPTION(status)) {
- _PyErr_SetFromPyStatus(status);
- return -1;
- }
-
- status = _PyConfig_Copy(&tstate->interp->config, config);
- if (_PyStatus_EXCEPTION(status)) {
- _PyErr_SetFromPyStatus(status);
- return -1;
+ if (!only_update_path_config) {
+ PyStatus status = _PyConfig_Write(config, tstate->interp->runtime);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ return -1;
+ }
  }
- config = &tstate->interp->config;
 
- if (config->_install_importlib && _Py_IsMainInterpreter(tstate)) {
- status = _PyConfig_WritePathConfig(config);
+ if (_Py_IsMainInterpreter(tstate)) {
+ PyStatus status = _PyConfig_WritePathConfig(config);
  if (_PyStatus_EXCEPTION(status)) {
  _PyErr_SetFromPyStatus(status);
  return -1;
@@ -465,6 +460,7 @@ interpreter_set_config(const PyConfig *config)
 int
 _PyInterpreterState_SetConfig(const PyConfig *src_config)
 {
+ PyThreadState *tstate = PyThreadState_Get();
  int res = -1;
 
  PyConfig config;
@@ -481,7 +477,13 @@ _PyInterpreterState_SetConfig(const PyConfig *src_config)
  goto done;
  }
 
- res = interpreter_set_config(&config);
+ status = _PyConfig_Copy(&tstate->interp->config, &config);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ goto done;
+ }
+
+ res = interpreter_update_config(tstate, 0);
 
 done:
  PyConfig_Clear(&config);
@@ -763,13 +765,6 @@ pycore_init_import_warnings(PyThreadState *tstate, PyObject *sysmod)
 
  const PyConfig *config = _PyInterpreterState_GetConfig(tstate->interp);
  if (config->_install_importlib) {
- if (_Py_IsMainInterpreter(tstate)) {
- status = _PyConfig_WritePathConfig(config);
- if (_PyStatus_EXCEPTION(status)) {
- return status;
- }
- }
-
  /* This call sets up builtin and frozen import support */
  status = init_importlib(tstate, sysmod);
  if (_PyStatus_EXCEPTION(status)) {
@@ -985,7 +980,9 @@ pyinit_core(_PyRuntimeState *runtime,
  goto done;
  }
 
- status = PyConfig_Read(&config);
+ // Read the configuration, but don't compute the path configuration
+ // (it is computed in the main init).
+ status = _PyConfig_Read(&config, 0);
  if (_PyStatus_EXCEPTION(status)) {
  goto done;
  }
@@ -1012,8 +1009,8 @@ pyinit_core(_PyRuntimeState *runtime,
 static PyStatus
 pyinit_main_reconfigure(PyThreadState *tstate)
 {
- if (_PySys_UpdateConfig(tstate) < 0) {
- return _PyStatus_ERR("fail to update sys for the new conf");
+ if (interpreter_update_config(tstate, 0) < 0) {
+ return _PyStatus_ERR("fail to reconfigure Python");
  }
  return _PyStatus_OK();
 }
@@ -1041,14 +1038,20 @@ init_interp_main(PyThreadState *tstate)
  return _PyStatus_OK();
  }
 
+ // Compute the path configuration
+ status = _PyConfig_InitPathConfig(&interp->config);
+ if (_PyStatus_EXCEPTION(status)) {
+ return status;
+ }
+
  if (is_main_interp) {
  if (_PyTime_Init() < 0) {
  return _PyStatus_ERR("can't initialize time");
  }
  }
 
- if (_PySys_UpdateConfig(tstate) < 0) {
- return _PyStatus_ERR("can't finish initializing sys");
+ if (interpreter_update_config(tstate, 1) < 0) {
+ return _PyStatus_ERR("failed to update the Python config");
  }
 
  status = init_importlib_external(tstate);

Python/sysmodule.c

@@ -2922,17 +2922,22 @@ _PySys_UpdateConfig(PyThreadState *tstate)
 #define SET_SYS_FROM_WSTR(KEY, VALUE) \
  SET_SYS(KEY, PyUnicode_FromWideChar(VALUE, -1));
 
+#define COPY_WSTR(SYS_ATTR, WSTR) \
+ if (WSTR != NULL) { \
+ SET_SYS_FROM_WSTR(SYS_ATTR, WSTR); \
+ }
+
  if (config->module_search_paths_set) {
  COPY_LIST("path", config->module_search_paths);
  }
 
- SET_SYS_FROM_WSTR("executable", config->executable);
- SET_SYS_FROM_WSTR("_base_executable", config->base_executable);
- SET_SYS_FROM_WSTR("prefix", config->prefix);
- SET_SYS_FROM_WSTR("base_prefix", config->base_prefix);
- SET_SYS_FROM_WSTR("exec_prefix", config->exec_prefix);
- SET_SYS_FROM_WSTR("base_exec_prefix", config->base_exec_prefix);
- SET_SYS_FROM_WSTR("platlibdir", config->platlibdir);
+ COPY_WSTR("executable", config->executable);
+ COPY_WSTR("_base_executable", config->base_executable);
+ COPY_WSTR("prefix", config->prefix);
+ COPY_WSTR("base_prefix", config->base_prefix);
+ COPY_WSTR("exec_prefix", config->exec_prefix);
+ COPY_WSTR("base_exec_prefix", config->base_exec_prefix);
+ COPY_WSTR("platlibdir", config->platlibdir);
 
  if (config->pycache_prefix != NULL) {
  SET_SYS_FROM_WSTR("pycache_prefix", config->pycache_prefix);
@@ -2946,8 +2951,9 @@ _PySys_UpdateConfig(PyThreadState *tstate)
 
  SET_SYS("_xoptions", sys_create_xoptions_dict(config));
 
-#undef COPY_LIST
 #undef SET_SYS_FROM_WSTR
+#undef COPY_LIST
+#undef COPY_WSTR
 
  // sys.flags
  PyObject *flags = _PySys_GetObject(tstate, "flags"); // borrowed ref