bpo-36301: Add _PyWstrList structure (GH-12343)

Replace messy _Py_wstrlist_xxx() functions with a new clean
_PyWstrList structure and new _PyWstrList_xxx() functions.

Changes:

* Add _PyCoreConfig.use_module_search_paths to decide if
  _PyCoreConfig.module_search_paths should be computed or not, to
  support empty search path list.
* _PyWstrList_Clear() sets length to 0 and items to NULL, whereas
  _Py_wstrlist_clear() only freed memory.
* _PyWstrList_Append() returns an int, whereas _Py_wstrlist_append()
  returned _PyInitError.
* _PyWstrList uses Py_ssize_t for the length, instead of int.
* Replace (int, wchar_t**) with _PyWstrList in:

  * _PyPreConfig
  * _PyCoreConfig
  * _PyPreCmdline
  * _PyCmdline

* Replace "int orig_argv; wchar_t **orig_argv;"
  with "_PyWstrList orig_argv".
* _PyCmdline and _PyPreCmdline now also copy wchar_argv.
* Rename _PyArgv_Decode() to _PyArgv_AsWstrList().
* PySys_SetArgvEx() now pass the fixed (argc, argv) to
  _PyPathConfig_ComputeArgv0() (don't pass negative argc or NULL
  argv).
* _PyOS_GetOpt() uses Py_ssize_t

Author: vstinner

Include/cpython/coreconfig.h

@@ -46,6 +46,18 @@ typedef struct {
 #define _Py_INIT_FAILED(err) \
     (err.msg != NULL || err.exitcode != -1)
 
+/* --- _PyWstrList ------------------------------------------------ */
+
+typedef struct {
+    /* If length is greater than zero, items must be non-NULL
+       and all items strings must be non-NULL */
+    Py_ssize_t length;
+    wchar_t **items;
+} _PyWstrList;
+
+#define _PyWstrList_INIT (_PyWstrList){.length = 0, .items = NULL}
+
+
 /* --- _PyPreConfig ----------------------------------------------- */
 
 typedef struct {
@@ -162,29 +174,24 @@ typedef struct {
     char *filesystem_encoding;
     char *filesystem_errors;
 
-    wchar_t *pycache_prefix; /* PYTHONPYCACHEPREFIX, -X pycache_prefix=PATH */
-
-    wchar_t *program_name;  /* Program name, see also Py_GetProgramName() */
-    int argc;               /* Number of command line arguments,
-                               -1 means unset */
-    wchar_t **argv;         /* Command line arguments */
-    wchar_t *program;       /* argv[0] or "" */
-
-    int nxoption;           /* Number of -X options */
-    wchar_t **xoptions;     /* -X options */
-
-    int nwarnoption;        /* Number of warnings options */
-    wchar_t **warnoptions;  /* Warnings options */
+    wchar_t *pycache_prefix;  /* PYTHONPYCACHEPREFIX, -X pycache_prefix=PATH */
+    wchar_t *program_name;    /* Program name, see also Py_GetProgramName() */
+    _PyWstrList argv;         /* Command line arguments */
+    wchar_t *program;         /* argv[0] or "" */
+    _PyWstrList xoptions;     /* Command line -X options */
+    _PyWstrList warnoptions;  /* Warnings options */
 
     /* Path configuration inputs */
     wchar_t *module_search_path_env; /* PYTHONPATH environment variable */
     wchar_t *home;          /* PYTHONHOME environment variable,
                                see also Py_SetPythonHome(). */
 
     /* Path configuration outputs */
-    int nmodule_search_path;        /* Number of sys.path paths,
-                                       -1 means unset */
-    wchar_t **module_search_paths;  /* sys.path paths */
+    int use_module_search_paths;  /* If non-zero, use module_search_paths */
+    _PyWstrList module_search_paths;  /* sys.path paths. Computed if
+                                       use_module_search_paths is equal
+                                       to zero. */
+
     wchar_t *executable;    /* sys.executable */
     wchar_t *prefix;        /* sys.prefix */
     wchar_t *base_prefix;   /* sys.base_prefix */
@@ -366,8 +373,7 @@ typedef struct {
         .use_hash_seed = -1, \
         .faulthandler = -1, \
         .tracemalloc = -1, \
-        .argc = -1, \
-        .nmodule_search_path = -1, \
+        .use_module_search_paths = 0, \
         .site_import = -1, \
         .bytes_warning = -1, \
         .inspect = -1, \

Include/internal/pycore_coreconfig.h

@@ -8,39 +8,38 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE or Py_BUILD_CORE_BUILTIN defined"
 #endif
 
-/* --- _Py_wstrlist ----------------------------------------------- */
-
-PyAPI_FUNC(void) _Py_wstrlist_clear(
-    int len,
-    wchar_t **list);
-PyAPI_FUNC(wchar_t**) _Py_wstrlist_copy(
-    int len,
-    wchar_t * const *list);
-PyAPI_FUNC(_PyInitError) _Py_wstrlist_append(
-    int *len,
-    wchar_t ***list,
-    const wchar_t *str);
-PyAPI_FUNC(PyObject*) _Py_wstrlist_as_pylist(
-    int len,
-    wchar_t **list);
+
+/* --- _PyWstrList ------------------------------------------------ */
+
+#ifndef NDEBUG
+PyAPI_FUNC(int) _PyWstrList_CheckConsistency(const _PyWstrList *list);
+#endif
+PyAPI_FUNC(void) _PyWstrList_Clear(_PyWstrList *list);
+PyAPI_FUNC(int) _PyWstrList_Copy(_PyWstrList *list,
+    const _PyWstrList *list2);
+PyAPI_FUNC(int) _PyWstrList_Append(_PyWstrList *list,
+    const wchar_t *item);
+PyAPI_FUNC(PyObject*) _PyWstrList_AsList(const _PyWstrList *list);
+
 
 /* --- _PyArgv ---------------------------------------------------- */
 
-PyAPI_FUNC(_PyInitError) _PyArgv_Decode(const _PyArgv *args,
-    wchar_t*** argv_p);
+PyAPI_FUNC(_PyInitError) _PyArgv_AsWstrList(const _PyArgv *args,
+    _PyWstrList *list);
+
 
 /* --- Py_GetArgcArgv() helpers ----------------------------------- */
 
 PyAPI_FUNC(void) _Py_ClearArgcArgv(void);
 
+
 /* --- _PyPreConfig ----------------------------------------------- */
 
 PyAPI_FUNC(int) _Py_str_to_int(
     const char *str,
     int *result);
 PyAPI_FUNC(const wchar_t*) _Py_get_xoption(
-    int nxoption,
-    wchar_t * const *xoptions,
+    const _PyWstrList *xoptions,
     const wchar_t *name);
 
 PyAPI_FUNC(void) _PyPreConfig_Clear(_PyPreConfig *config);

Include/internal/pycore_getopt.h

@@ -6,8 +6,8 @@
 #endif
 
 extern int _PyOS_opterr;
-extern int _PyOS_optind;
-extern wchar_t *_PyOS_optarg;
+extern Py_ssize_t _PyOS_optind;
+extern const wchar_t *_PyOS_optarg;
 
 extern void _PyOS_ResetGetOpt(void);
 
@@ -17,6 +17,6 @@ typedef struct {
     int val;
 } _PyOS_LongOption;
 
-extern int _PyOS_GetOpt(int argc, wchar_t **argv, int *longindex);
+extern int _PyOS_GetOpt(Py_ssize_t argc, wchar_t **argv, int *longindex);
 
 #endif /* !Py_INTERNAL_PYGETOPT_H */

Include/internal/pycore_pathconfig.h

@@ -44,7 +44,7 @@ PyAPI_FUNC(_PyInitError) _PyPathConfig_SetGlobal(
 PyAPI_FUNC(_PyInitError) _PyPathConfig_Calculate_impl(
     _PyPathConfig *config,
     const _PyCoreConfig *core_config);
-PyAPI_FUNC(PyObject*) _PyPathConfig_ComputeArgv0(int argc, wchar_t **argv);
+PyAPI_FUNC(PyObject*) _PyPathConfig_ComputeArgv0(const _PyWstrList *argv);
 PyAPI_FUNC(int) _Py_FindEnvConfigValue(
     FILE *env_file,
     const wchar_t *key,

Modules/main.c

@@ -84,15 +84,15 @@ mainconfig_add_xoption(PyObject *opts, const wchar_t *s)
 static PyObject*
 mainconfig_create_xoptions_dict(const _PyCoreConfig *config)
 {
-    int nxoption = config->nxoption;
-    wchar_t **xoptions = config->xoptions;
+    Py_ssize_t nxoption = config->xoptions.length;
+    wchar_t * const * xoptions = config->xoptions.items;
     PyObject *dict = PyDict_New();
     if (dict == NULL) {
         return NULL;
     }
 
-    for (int i=0; i < nxoption; i++) {
-        wchar_t *option = xoptions[i];
+    for (Py_ssize_t i=0; i < nxoption; i++) {
+        const wchar_t *option = xoptions[i];
         if (mainconfig_add_xoption(dict, option) < 0) {
             Py_DECREF(dict);
             return NULL;
@@ -243,22 +243,18 @@ _PyMainInterpreterConfig_Read(_PyMainInterpreterConfig *main_config,
             } \
         } \
     } while (0)
-#define COPY_WSTRLIST(ATTR, LEN, LIST) \
+#define COPY_WSTRLIST(ATTR, LIST) \
     do { \
         if (ATTR == NULL) { \
-            ATTR = _Py_wstrlist_as_pylist(LEN, LIST); \
+            ATTR = _PyWstrList_AsList(LIST); \
             if (ATTR == NULL) { \
                 return _Py_INIT_NO_MEMORY(); \
             } \
         } \
     } while (0)
 
-    COPY_WSTRLIST(main_config->warnoptions,
-                  config->nwarnoption, config->warnoptions);
-    if (config->argc >= 0) {
-        COPY_WSTRLIST(main_config->argv,
-                      config->argc, config->argv);
-    }
+    COPY_WSTRLIST(main_config->warnoptions, &config->warnoptions);
+    COPY_WSTRLIST(main_config->argv, &config->argv);
 
     if (config->_install_importlib) {
         COPY_WSTR(executable);
@@ -268,7 +264,7 @@ _PyMainInterpreterConfig_Read(_PyMainInterpreterConfig *main_config,
         COPY_WSTR(base_exec_prefix);
 
         COPY_WSTRLIST(main_config->module_search_path,
-                      config->nmodule_search_path, config->module_search_paths);
+                      &config->module_search_paths);
 
         if (config->pycache_prefix != NULL) {
             COPY_WSTR(pycache_prefix);
@@ -784,8 +780,7 @@ pymain_run_python(PyInterpreterState *interp, int *exitcode)
         }
     }
     else if (!config->preconfig.isolated) {
-        PyObject *path0 = _PyPathConfig_ComputeArgv0(config->argc,
-                                                     config->argv);
+        PyObject *path0 = _PyPathConfig_ComputeArgv0(&config->argv);
         if (path0 == NULL) {
             err = _Py_INIT_NO_MEMORY();
             goto done;

Programs/_testembed.c

@@ -479,8 +479,8 @@ static int test_init_from_config(void)
         L"-c",
         L"pass",
     };
-    config.argc = Py_ARRAY_LENGTH(argv);
-    config.argv = argv;
+    config.argv.length = Py_ARRAY_LENGTH(argv);
+    config.argv.items = argv;
 
     config.program = L"conf_program";
 
@@ -489,15 +489,15 @@ static int test_init_from_config(void)
         L"core_xoption2=",
         L"core_xoption3",
     };
-    config.nxoption = Py_ARRAY_LENGTH(xoptions);
-    config.xoptions = xoptions;
+    config.xoptions.length = Py_ARRAY_LENGTH(xoptions);
+    config.xoptions.items = xoptions;
 
     static wchar_t* warnoptions[2] = {
         L"default",
         L"error::ResourceWarning",
     };
-    config.nwarnoption = Py_ARRAY_LENGTH(warnoptions);
-    config.warnoptions = warnoptions;
+    config.warnoptions.length = Py_ARRAY_LENGTH(warnoptions);
+    config.warnoptions.items = warnoptions;
 
     /* FIXME: test module_search_path_env */
     /* FIXME: test home */