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

1 files changed, 30 insertions, 39 deletions

diff --git a/Python/preconfig.c b/Python/preconfig.c
index 50d66b1249..a86ece57cf 100644
--- a/Python/preconfig.c
+++ b/Python/preconfig.c
@@ -64,33 +64,38 @@ _Py_SetFileSystemEncoding(const char *encoding, const char *errors)
 /* --- _PyArgv ---------------------------------------------------- */
 
 _PyInitError
-_PyArgv_Decode(const _PyArgv *args, wchar_t*** argv_p)
+_PyArgv_AsWstrList(const _PyArgv *args, _PyWstrList *list)
 {
-    wchar_t** argv;
+    _PyWstrList wargv = _PyWstrList_INIT;
     if (args->use_bytes_argv) {
-        /* +1 for a the NULL terminator */
-        size_t size = sizeof(wchar_t*) * (args->argc + 1);
-        argv = (wchar_t **)PyMem_RawMalloc(size);
-        if (argv == NULL) {
+        size_t size = sizeof(wchar_t*) * args->argc;
+        wargv.items = (wchar_t **)PyMem_RawMalloc(size);
+        if (wargv.items == NULL) {
             return _Py_INIT_NO_MEMORY();
         }
 
-        for (int i = 0; i < args->argc; i++) {
+        for (Py_ssize_t i = 0; i < args->argc; i++) {
             size_t len;
             wchar_t *arg = Py_DecodeLocale(args->bytes_argv[i], &len);
             if (arg == NULL) {
-                _Py_wstrlist_clear(i, argv);
+                _PyWstrList_Clear(&wargv);
                 return DECODE_LOCALE_ERR("command line arguments",
                                          (Py_ssize_t)len);
             }
-            argv[i] = arg;
+            wargv.items[i] = arg;
+            wargv.length++;
         }
-        argv[args->argc] = NULL;
+
+        _PyWstrList_Clear(list);
+        *list = wargv;
     }
     else {
-        argv = args->wchar_argv;
+        wargv.length = args->argc;
+        wargv.items = args->wchar_argv;
+        if (_PyWstrList_Copy(list, &wargv) < 0) {
+            return _Py_INIT_NO_MEMORY();
+        }
     }
-    *argv_p = argv;
     return _Py_INIT_OK();
 }
 
@@ -98,25 +103,16 @@ _PyArgv_Decode(const _PyArgv *args, wchar_t*** argv_p)
 /* --- _PyPreCmdline ------------------------------------------------- */
 
 typedef struct {
-    const _PyArgv *args;
-    int argc;
-    wchar_t **argv;
-    int nxoption;           /* Number of -X options */
-    wchar_t **xoptions;     /* -X options */
+    _PyWstrList argv;
+    _PyWstrList xoptions;     /* -X options */
 } _PyPreCmdline;
 
 
 static void
 precmdline_clear(_PyPreCmdline *cmdline)
 {
-    if (cmdline->args->use_bytes_argv && cmdline->argv != NULL) {
-        _Py_wstrlist_clear(cmdline->args->argc, cmdline->argv);
-    }
-    cmdline->argv = NULL;
-
-    _Py_wstrlist_clear(cmdline->nxoption, cmdline->xoptions);
-    cmdline->nxoption = 0;
-    cmdline->xoptions = NULL;
+    _PyWstrList_Clear(&cmdline->argv);
+    _PyWstrList_Clear(&cmdline->xoptions);
 }
 
 
@@ -267,10 +263,10 @@ _Py_get_env_flag(_PyPreConfig *config, int *flag, const char *name)
 
 
 const wchar_t*
-_Py_get_xoption(int nxoption, wchar_t * const *xoptions, const wchar_t *name)
+_Py_get_xoption(const _PyWstrList *xoptions, const wchar_t *name)
 {
-    for (int i=0; i < nxoption; i++) {
-        const wchar_t *option = xoptions[i];
+    for (Py_ssize_t i=0; i < xoptions->length; i++) {
+        const wchar_t *option = xoptions->items[i];
         size_t len;
         wchar_t *sep = wcschr(option, L'=');
         if (sep != NULL) {
@@ -292,7 +288,7 @@ preconfig_init_utf8_mode(_PyPreConfig *config, const _PyPreCmdline *cmdline)
 {
     const wchar_t *xopt;
     if (cmdline) {
-        xopt = _Py_get_xoption(cmdline->nxoption, cmdline->xoptions, L"utf8");
+        xopt = _Py_get_xoption(&cmdline->xoptions, L"utf8");
     }
     else {
         xopt = NULL;
@@ -435,7 +431,7 @@ preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
     }
 
     /* dev_mode */
-    if ((cmdline && _Py_get_xoption(cmdline->nxoption, cmdline->xoptions, L"dev"))
+    if ((cmdline && _Py_get_xoption(&cmdline->xoptions, L"dev"))
         || _PyPreConfig_GetEnv(config, "PYTHONDEVMODE"))
     {
         config->dev_mode = 1;
@@ -579,7 +575,7 @@ preconfig_parse_cmdline(_PyPreConfig *config, _PyPreCmdline *cmdline)
     _PyOS_opterr = 0;
     do {
         int longindex = -1;
-        int c = _PyOS_GetOpt(cmdline->args->argc, cmdline->argv, &longindex);
+        int c = _PyOS_GetOpt(cmdline->argv.length, cmdline->argv.items, &longindex);
 
         if (c == EOF || c == 'c' || c == 'm') {
             break;
@@ -596,12 +592,8 @@ preconfig_parse_cmdline(_PyPreConfig *config, _PyPreCmdline *cmdline)
 
         case 'X':
         {
-            _PyInitError err;
-            err = _Py_wstrlist_append(&cmdline->nxoption,
-                                      &cmdline->xoptions,
-                                      _PyOS_optarg);
-            if (_Py_INIT_FAILED(err)) {
-                return err;
+            if (_PyWstrList_Append(&cmdline->xoptions, _PyOS_optarg) < 0) {
+                return _Py_INIT_NO_MEMORY();
             }
             break;
         }
@@ -624,9 +616,8 @@ preconfig_from_argv(_PyPreConfig *config, const _PyArgv *args)
 
     _PyPreCmdline cmdline;
     memset(&cmdline, 0, sizeof(cmdline));
-    cmdline.args = args;
 
-    err = _PyArgv_Decode(cmdline.args, &cmdline.argv);
+    err = _PyArgv_AsWstrList(args, &cmdline.argv);
     if (_Py_INIT_FAILED(err)) {
         goto done;
     }