bpo-36356: Fix _PyCoreConfig_Read() (GH-12454)

Don't override parameters which are already set by the user.

Author: vstinner

Python/coreconfig.c

@@ -961,13 +961,15 @@ config_read_env_vars(_PyCoreConfig *config)
  config->malloc_stats = 1;
  }
 
- wchar_t *path;
- int res = _PyCoreConfig_GetEnvDup(config, &path,
- L"PYTHONPATH", "PYTHONPATH");
- if (res < 0) {
- return DECODE_LOCALE_ERR("PYTHONPATH", res);
+ if (config->module_search_path_env == NULL) {
+ wchar_t *path;
+ int res = _PyCoreConfig_GetEnvDup(config, &path,
+ L"PYTHONPATH", "PYTHONPATH");
+ if (res < 0) {
+ return DECODE_LOCALE_ERR("PYTHONPATH", res);
+ }
+ config->module_search_path_env = path;
  }
- config->module_search_path_env = path;
 
  if (config->use_hash_seed < 0) {
  _PyInitError err = config_init_hash_seed(config);
@@ -1689,28 +1691,32 @@ config_parse_cmdline(_PyCoreConfig *config, _PyCmdline *cmdline,
  }
 
  if (c == 'c') {
- /* -c is the last option; following arguments
- that look like options are left for the
- command to interpret. */
- size_t len = wcslen(_PyOS_optarg) + 1 + 1;
- wchar_t *command = PyMem_RawMalloc(sizeof(wchar_t) * len);
- if (command == NULL) {
- return _Py_INIT_NO_MEMORY();
+ if (config->run_command == NULL) {
+ /* -c is the last option; following arguments
+ that look like options are left for the
+ command to interpret. */
+ size_t len = wcslen(_PyOS_optarg) + 1 + 1;
+ wchar_t *command = PyMem_RawMalloc(sizeof(wchar_t) * len);
+ if (command == NULL) {
+ return _Py_INIT_NO_MEMORY();
+ }
+ memcpy(command, _PyOS_optarg, (len - 2) * sizeof(wchar_t));
+ command[len - 2] = '\n';
+ command[len - 1] = 0;
+ config->run_command = command;
  }
- memcpy(command, _PyOS_optarg, (len - 2) * sizeof(wchar_t));
- command[len - 2] = '\n';
- command[len - 1] = 0;
- config->run_command = command;
  break;
  }
 
  if (c == 'm') {
  /* -m is the last option; following arguments
  that look like options are left for the
  module to interpret. */
- config->run_module = _PyMem_RawWcsdup(_PyOS_optarg);
  if (config->run_module == NULL) {
- return _Py_INIT_NO_MEMORY();
+ config->run_module = _PyMem_RawWcsdup(_PyOS_optarg);
+ if (config->run_module == NULL) {
+ return _Py_INIT_NO_MEMORY();
+ }
  }
  break;
  }
@@ -1825,7 +1831,8 @@ config_parse_cmdline(_PyCoreConfig *config, _PyCmdline *cmdline,
 
  if (config->run_command == NULL && config->run_module == NULL
  && _PyOS_optind < cmdline->argv.length
- && wcscmp(cmdline->argv.items[_PyOS_optind], L"-") != 0)
+ && wcscmp(cmdline->argv.items[_PyOS_optind], L"-") != 0
+ && config->run_filename == NULL)
  {
  config->run_filename = _PyMem_RawWcsdup(cmdline->argv.items[_PyOS_optind]);
  if (config->run_filename == NULL) {
@@ -2032,9 +2039,11 @@ config_from_cmdline(_PyCoreConfig *config, _PyCmdline *cmdline,
 
  _PyCoreConfig_GetGlobalConfig(config);
 
- err = config_init_program(config, cmdline);
- if (_Py_INIT_FAILED(err)) {
- return err;
+ if (config->program == NULL) {
+ err = config_init_program(config, cmdline);
+ if (_Py_INIT_FAILED(err)) {
+ return err;
+ }
  }
 
  err = config_parse_cmdline(config, cmdline, &need_usage);