Modules/main.c

/* Python interpreter main program */

#include "Python.h"
#include "osdefs.h"
#include "internal/import.h"
#include "internal/pystate.h"

#include <locale.h>

#if defined(MS_WINDOWS) || defined(__CYGWIN__)
#include <windows.h>
#ifdef HAVE_IO_H
#include <io.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#endif

#ifdef _MSC_VER
#include <crtdbg.h>
#endif

#if defined(MS_WINDOWS)
#define PYTHONHOMEHELP "<prefix>\\python{major}{minor}"
#else
#define PYTHONHOMEHELP "<prefix>/lib/pythonX.X"
#endif

#include "pygetopt.h"

#define COPYRIGHT \
    "Type \"help\", \"copyright\", \"credits\" or \"license\" " \
    "for more information."

#ifdef __cplusplus
extern "C" {
#endif

#define DECODE_LOCALE_ERR(NAME, LEN) \
    (((LEN) == -2) \
     ? _Py_INIT_USER_ERR("cannot decode " #NAME) \
     : _Py_INIT_NO_MEMORY())


#define SET_DECODE_ERROR(NAME, LEN) \
    do { \
        if ((LEN) == (size_t)-2) { \
            pymain->err = _Py_INIT_USER_ERR("cannot decode " #NAME); \
        } \
        else { \
            pymain->err = _Py_INIT_NO_MEMORY(); \
        } \
    } while (0)

/* For Py_GetArgcArgv(); set by main() */
static wchar_t **orig_argv;
static int orig_argc;

/* command line options */
#define BASE_OPTS L"bBc:dEhiIJm:OqRsStuvVW:xX:?"

#define PROGRAM_OPTS BASE_OPTS

static const _PyOS_LongOption longoptions[] = {
    {L"check-hash-based-pycs", 1, 0},
    {NULL, 0, 0},
};

/* Short usage message (with %s for argv0) */
static const char usage_line[] =
"usage: %ls [option] ... [-c cmd | -m mod | file | -] [arg] ...\n";

/* Long usage message, split into parts < 512 bytes */
static const char usage_1[] = "\
Options and arguments (and corresponding environment variables):\n\
-b     : issue warnings about str(bytes_instance), str(bytearray_instance)\n\
         and comparing bytes/bytearray with str. (-bb: issue errors)\n\
-B     : don't write .pyc files on import; also PYTHONDONTWRITEBYTECODE=x\n\
-c cmd : program passed in as string (terminates option list)\n\
-d     : debug output from parser; also PYTHONDEBUG=x\n\
-E     : ignore PYTHON* environment variables (such as PYTHONPATH)\n\
-h     : print this help message and exit (also --help)\n\
";
static const char usage_2[] = "\
-i     : inspect interactively after running script; forces a prompt even\n\
         if stdin does not appear to be a terminal; also PYTHONINSPECT=x\n\
-I     : isolate Python from the user's environment (implies -E and -s)\n\
-m mod : run library module as a script (terminates option list)\n\
-O     : optimize generated bytecode slightly; also PYTHONOPTIMIZE=x\n\
-OO    : remove doc-strings in addition to the -O optimizations\n\
-q     : don't print version and copyright messages on interactive startup\n\
-s     : don't add user site directory to sys.path; also PYTHONNOUSERSITE\n\
-S     : don't imply 'import site' on initialization\n\
";
static const char usage_3[] = "\
-u     : force the stdout and stderr streams to be unbuffered;\n\
         this option has no effect on stdin; also PYTHONUNBUFFERED=x\n\
-v     : verbose (trace import statements); also PYTHONVERBOSE=x\n\
         can be supplied multiple times to increase verbosity\n\
-V     : print the Python version number and exit (also --version)\n\
         when given twice, print more information about the build\n\
-W arg : warning control; arg is action:message:category:module:lineno\n\
         also PYTHONWARNINGS=arg\n\
-x     : skip first line of source, allowing use of non-Unix forms of #!cmd\n\
-X opt : set implementation-specific option\n\
--check-hash-based-pycs always|default|never:\n\
    control how Python invalidates hash-based .pyc files\n\
";
static const char usage_4[] = "\
file   : program read from script file\n\
-      : program read from stdin (default; interactive mode if a tty)\n\
arg ...: arguments passed to program in sys.argv[1:]\n\n\
Other environment variables:\n\
PYTHONSTARTUP: file executed on interactive startup (no default)\n\
PYTHONPATH   : '%lc'-separated list of directories prefixed to the\n\
               default module search path.  The result is sys.path.\n\
";
static const char usage_5[] =
"PYTHONHOME   : alternate <prefix> directory (or <prefix>%lc<exec_prefix>).\n"
"               The default module search path uses %s.\n"
"PYTHONCASEOK : ignore case in 'import' statements (Windows).\n"
"PYTHONIOENCODING: Encoding[:errors] used for stdin/stdout/stderr.\n"
"PYTHONFAULTHANDLER: dump the Python traceback on fatal errors.\n";
static const char usage_6[] =
"PYTHONHASHSEED: if this variable is set to 'random', a random value is used\n"
"   to seed the hashes of str, bytes and datetime objects.  It can also be\n"
"   set to an integer in the range [0,4294967295] to get hash values with a\n"
"   predictable seed.\n"
"PYTHONMALLOC: set the Python memory allocators and/or install debug hooks\n"
"   on Python memory allocators. Use PYTHONMALLOC=debug to install debug\n"
"   hooks.\n"
"PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale\n"
"   coercion behavior. Use PYTHONCOERCECLOCALE=warn to request display of\n"
"   locale coercion and locale compatibility warnings on stderr.\n"
"PYTHONDEVMODE: enable the development mode.\n";

static void
pymain_usage(int error, const wchar_t* program)
{
    FILE *f = error ? stderr : stdout;

    fprintf(f, usage_line, program);
    if (error)
        fprintf(f, "Try `python -h' for more information.\n");
    else {
        fputs(usage_1, f);
        fputs(usage_2, f);
        fputs(usage_3, f);
        fprintf(f, usage_4, (wint_t)DELIM);
        fprintf(f, usage_5, (wint_t)DELIM, PYTHONHOMEHELP);
        fputs(usage_6, f);
    }
}


static const char*
pymain_get_env_var(const char *name)
{
    const char *var = Py_GETENV(name);
    if (var && var[0] != '\0') {
        return var;
    }
    else {
        return NULL;
    }
}


static void
pymain_run_startup(PyCompilerFlags *cf)
{
    const char *startup = pymain_get_env_var("PYTHONSTARTUP");
    if (startup == NULL) {
        return;
    }

    FILE *fp = _Py_fopen(startup, "r");
    if (fp == NULL) {
        int save_errno = errno;
        PySys_WriteStderr("Could not open PYTHONSTARTUP\n");
        errno = save_errno;

        PyErr_SetFromErrnoWithFilename(PyExc_OSError,
                        startup);
        PyErr_Print();
        PyErr_Clear();
        return;
    }

    (void) PyRun_SimpleFileExFlags(fp, startup, 0, cf);
    PyErr_Clear();
    fclose(fp);
}

static void
pymain_run_interactive_hook(void)
{
    PyObject *sys, *hook, *result;
    sys = PyImport_ImportModule("sys");
    if (sys == NULL) {
        goto error;
    }

    hook = PyObject_GetAttrString(sys, "__interactivehook__");
    Py_DECREF(sys);
    if (hook == NULL) {
        PyErr_Clear();
        return;
    }

    result = _PyObject_CallNoArg(hook);
    Py_DECREF(hook);
    if (result == NULL) {
        goto error;
    }
    Py_DECREF(result);

    return;

error:
    PySys_WriteStderr("Failed calling sys.__interactivehook__\n");
    PyErr_Print();
    PyErr_Clear();
}


static int
pymain_run_module(wchar_t *modname, int set_argv0)
{
    PyObject *module, *runpy, *runmodule, *runargs, *result;
    runpy = PyImport_ImportModule("runpy");
    if (runpy == NULL) {
        fprintf(stderr, "Could not import runpy module\n");
        PyErr_Print();
        return -1;
    }
    runmodule = PyObject_GetAttrString(runpy, "_run_module_as_main");
    if (runmodule == NULL) {
        fprintf(stderr, "Could not access runpy._run_module_as_main\n");
        PyErr_Print();
        Py_DECREF(runpy);
        return -1;
    }
    module = PyUnicode_FromWideChar(modname, wcslen(modname));
    if (module == NULL) {
        fprintf(stderr, "Could not convert module name to unicode\n");
        PyErr_Print();
        Py_DECREF(runpy);
        Py_DECREF(runmodule);
        return -1;
    }
    runargs = Py_BuildValue("(Oi)", module, set_argv0);
    if (runargs == NULL) {
        fprintf(stderr,
            "Could not create arguments for runpy._run_module_as_main\n");
        PyErr_Print();
        Py_DECREF(runpy);
        Py_DECREF(runmodule);
        Py_DECREF(module);
        return -1;
    }
    result = PyObject_Call(runmodule, runargs, NULL);
    if (result == NULL) {
        PyErr_Print();
    }
    Py_DECREF(runpy);
    Py_DECREF(runmodule);
    Py_DECREF(module);
    Py_DECREF(runargs);
    if (result == NULL) {
        return -1;
    }
    Py_DECREF(result);
    return 0;
}

static PyObject *
pymain_get_importer(wchar_t *filename)
{
    PyObject *sys_path0 = NULL, *importer;

    sys_path0 = PyUnicode_FromWideChar(filename, wcslen(filename));
    if (sys_path0 == NULL) {
        goto error;
    }

    importer = PyImport_GetImporter(sys_path0);
    if (importer == NULL) {
        goto error;
    }

    if (importer == Py_None) {
        Py_DECREF(sys_path0);
        Py_DECREF(importer);
        return NULL;
    }

    Py_DECREF(importer);
    return sys_path0;

error:
    Py_XDECREF(sys_path0);
    PySys_WriteStderr("Failed checking if argv[0] is an import path entry\n");
    PyErr_Print();
    PyErr_Clear();
    return NULL;
}


static int
pymain_run_command(wchar_t *command, PyCompilerFlags *cf)
{
    PyObject *unicode, *bytes;
    int ret;

    unicode = PyUnicode_FromWideChar(command, -1);
    if (unicode == NULL) {
        goto error;
    }

    bytes = PyUnicode_AsUTF8String(unicode);
    Py_DECREF(unicode);
    if (bytes == NULL) {
        goto error;
    }

    ret = PyRun_SimpleStringFlags(PyBytes_AsString(bytes), cf);
    Py_DECREF(bytes);
    return (ret != 0);

error:
    PySys_WriteStderr("Unable to decode the command from the command line:\n");
    PyErr_Print();
    return 1;
}


static int
pymain_run_file(FILE *fp, const wchar_t *filename, PyCompilerFlags *p_cf)
{
    PyObject *unicode, *bytes = NULL;
    const char *filename_str;
    int run;

    /* call pending calls like signal handlers (SIGINT) */
    if (Py_MakePendingCalls() == -1) {
        PyErr_Print();
        return 1;
    }

    if (filename) {
        unicode = PyUnicode_FromWideChar(filename, wcslen(filename));
        if (unicode != NULL) {
            bytes = PyUnicode_EncodeFSDefault(unicode);
            Py_DECREF(unicode);
        }
        if (bytes != NULL) {
            filename_str = PyBytes_AsString(bytes);
        }
        else {
            PyErr_Clear();
            filename_str = "<encoding error>";
        }
    }
    else {
        filename_str = "<stdin>";
    }

    run = PyRun_AnyFileExFlags(fp, filename_str, filename != NULL, p_cf);
    Py_XDECREF(bytes);
    return run != 0;
}


/* Main program */

typedef struct {
    size_t len;
    wchar_t **options;
} _Py_OptList;

typedef struct {
    wchar_t *filename;           /* Trailing arg without -c or -m */
    wchar_t *command;            /* -c argument */
    wchar_t *module;             /* -m argument */
    _Py_OptList warning_options; /* -W options */
    int print_help;              /* -h, -? options */
    int print_version;           /* -V option */
    int bytes_warning;           /* Py_BytesWarningFlag, -b */
    int debug;                   /* Py_DebugFlag, -b, PYTHONDEBUG */
    int inspect;                 /* Py_InspectFlag, -i, PYTHONINSPECT */
    int interactive;             /* Py_InteractiveFlag, -i */
    int isolated;                /* Py_IsolatedFlag, -I */
    int optimization_level;      /* Py_OptimizeFlag, -O, PYTHONOPTIMIZE */
    int dont_write_bytecode;     /* Py_DontWriteBytecodeFlag, -B, PYTHONDONTWRITEBYTECODE */
    int no_user_site_directory;  /* Py_NoUserSiteDirectory, -I, -s, PYTHONNOUSERSITE */
    int no_site_import;          /* Py_NoSiteFlag, -S */
    int use_unbuffered_io;       /* Py_UnbufferedStdioFlag, -u, PYTHONUNBUFFERED */
    int verbosity;               /* Py_VerboseFlag, -v, PYTHONVERBOSE */
    int quiet_flag;              /* Py_QuietFlag, -q */
    int skip_first_line;         /* -x option */
    _Py_OptList xoptions;        /* -X options */
    const char *check_hash_pycs_mode; /* --check-hash-based-pycs */
#ifdef MS_WINDOWS
    int legacy_windows_fs_encoding;  /* Py_LegacyWindowsFSEncodingFlag,
                                        PYTHONLEGACYWINDOWSFSENCODING */
    int legacy_windows_stdio;        /* Py_LegacyWindowsStdioFlag,
                                        PYTHONLEGACYWINDOWSSTDIO */
#endif
} _Py_CommandLineDetails;

/* Structure used by Py_Main() to pass data to subfunctions */
typedef struct {
    /* Exit status ("exit code") */
    int status;
    PyCompilerFlags cf;
    /* non-zero is stdin is a TTY or if -i option is used */
    int stdin_is_interactive;
    _PyCoreConfig core_config;
    _PyMainInterpreterConfig config;
    _Py_CommandLineDetails cmdline;
    PyObject *main_importer_path;
    /* non-zero if filename, command (-c) or module (-m) is set
       on the command line */
    int run_code;
    /* Error message if a function failed */
    _PyInitError err;
    /* PYTHONWARNINGS env var */
    _Py_OptList env_warning_options;
    int argc;
    wchar_t **argv;

    int sys_argc;
    wchar_t **sys_argv;
} _PyMain;

/* .cmdline is initialized to zeros */
#define _PyMain_INIT \
    {.core_config = _PyCoreConfig_INIT, \
     .config = _PyMainInterpreterConfig_INIT, \
     .run_code = -1, \
     .err = _Py_INIT_OK()}
/* Note: _PyMain_INIT sets other fields to 0/NULL */


static void
pymain_optlist_clear(_Py_OptList *list)
{
    for (size_t i=0; i < list->len; i++) {
        PyMem_RawFree(list->options[i]);
    }
    PyMem_RawFree(list->options);
    list->len = 0;
    list->options = NULL;
}


/* Free global variables which cannot be freed in Py_Finalize():
   configuration options set before Py_Initialize() which should
   remain valid after Py_Finalize(), since Py_Initialize()/Py_Finalize() can
   be called multiple times.

   Called with the current memory allocators. */
static void
pymain_free_globals(_PyMain *pymain)
{
    _PyPathConfig_Clear(&_Py_path_config);
    _PyImport_Fini2();
    _PyCoreConfig_Clear(&pymain->core_config);

#ifdef __INSURE__
    /* Insure++ is a memory analysis tool that aids in discovering
     * memory leaks and other memory problems.  On Python exit, the
     * interned string dictionaries are flagged as being in use at exit
     * (which it is).  Under normal circumstances, this is fine because
     * the memory will be automatically reclaimed by the system.  Under
     * memory debugging, it's a huge source of useless noise, so we
     * trade off slower shutdown for less distraction in the memory
     * reports.  -baw
     */
    _Py_ReleaseInternedUnicodeStrings();
#endif /* __INSURE__ */
}


static void
pymain_free_pymain(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;
    pymain_optlist_clear(&cmdline->warning_options);
    pymain_optlist_clear(&cmdline->xoptions);
    PyMem_RawFree(cmdline->command);

    PyMem_RawFree(pymain->sys_argv);
    pymain_optlist_clear(&pymain->env_warning_options);
}


/* Clear Python ojects */
static void
pymain_free_python(_PyMain *pymain)
{
    Py_CLEAR(pymain->main_importer_path);

    _PyMainInterpreterConfig_Clear(&pymain->config);
}


static void
pymain_free(_PyMain *pymain)
{
    /* Force the allocator used by pymain_parse_cmdline_envvars() */
    PyMemAllocatorEx old_alloc;
    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);

    pymain_free_python(pymain);
    pymain_free_pymain(pymain);
    pymain_free_globals(pymain);

    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
}


static int
pymain_run_main_from_importer(_PyMain *pymain)
{
    /* Assume sys_path0 has already been checked by pymain_get_importer(),
     * so put it in sys.path[0] and import __main__ */
    PyObject *sys_path = PySys_GetObject("path");
    if (sys_path == NULL) {
        PyErr_SetString(PyExc_RuntimeError, "unable to get sys.path");
        goto error;
    }

    if (PyList_Insert(sys_path, 0, pymain->main_importer_path)) {
        goto error;
    }

    int sts = pymain_run_module(L"__main__", 0);
    return (sts != 0);

error:
    Py_CLEAR(pymain->main_importer_path);
    PyErr_Print();
    return 1;
}


static wchar_t*
pymain_wstrdup(_PyMain *pymain, const wchar_t *str)
{
    wchar_t *str2 = _PyMem_RawWcsdup(str);
    if (str2 == NULL) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return NULL;
    }
    return str2;
}


static int
pymain_optlist_append(_PyMain *pymain, _Py_OptList *list, const wchar_t *str)
{
    wchar_t *str2 = pymain_wstrdup(pymain, str);
    if (str2 == NULL) {
        return -1;
    }

    size_t size = (list->len + 1) * sizeof(list[0]);
    wchar_t **options2 = (wchar_t **)PyMem_RawRealloc(list->options, size);
    if (options2 == NULL) {
        PyMem_RawFree(str2);
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }
    options2[list->len] = str2;
    list->options = options2;
    list->len++;
    return 0;
}


/* Parse the command line arguments
   Return 0 on success.
   Return 1 if parsing failed.
   Set pymain->err and return -1 on other errors. */
static int
pymain_parse_cmdline_impl(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    _PyOS_ResetGetOpt();
    do {
        int longindex = -1;
        int c = _PyOS_GetOpt(pymain->argc, pymain->argv, PROGRAM_OPTS,
                             longoptions, &longindex);
        if (c == EOF) {
            break;
        }

        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) {
                pymain->err = _Py_INIT_NO_MEMORY();
                return -1;
            }
            memcpy(command, _PyOS_optarg, len * sizeof(wchar_t));
            command[len - 2] = '\n';
            command[len - 1] = 0;
            cmdline->command = command;
            break;
        }

        if (c == 'm') {
            /* -m is the last option; following arguments
               that look like options are left for the
               module to interpret. */
            cmdline->module = _PyOS_optarg;
            break;
        }

        switch (c) {
        case 0:
            // Handle long option.
            assert(longindex == 0); // Only one long option now.
            if (!wcscmp(_PyOS_optarg, L"always")) {
                cmdline->check_hash_pycs_mode = "always";
            } else if (!wcscmp(_PyOS_optarg, L"never")) {
                cmdline->check_hash_pycs_mode = "never";
            } else if (!wcscmp(_PyOS_optarg, L"default")) {
                cmdline->check_hash_pycs_mode = "default";
            } else {
                fprintf(stderr, "--check-hash-based-pycs must be one of "
                        "'default', 'always', or 'never'\n");
                return 1;
            }
            break;

        case 'b':
            cmdline->bytes_warning++;
            break;

        case 'd':
            cmdline->debug++;
            break;

        case 'i':
            cmdline->inspect++;
            cmdline->interactive++;
            break;

        case 'I':
            pymain->core_config.ignore_environment++;
            cmdline->isolated++;
            cmdline->no_user_site_directory++;
            break;

        /* case 'J': reserved for Jython */

        case 'O':
            cmdline->optimization_level++;
            break;

        case 'B':
            cmdline->dont_write_bytecode++;
            break;

        case 's':
            cmdline->no_user_site_directory++;
            break;

        case 'S':
            cmdline->no_site_import++;
            break;

        case 'E':
            pymain->core_config.ignore_environment++;
            break;

        case 't':
            /* ignored for backwards compatibility */
            break;

        case 'u':
            cmdline->use_unbuffered_io = 1;
            break;

        case 'v':
            cmdline->verbosity++;
            break;

        case 'x':
            cmdline->skip_first_line = 1;
            break;

        case 'h':
        case '?':
            cmdline->print_help++;
            break;

        case 'V':
            cmdline->print_version++;
            break;

        case 'W':
            if (pymain_optlist_append(pymain, &cmdline->warning_options,
                                      _PyOS_optarg) < 0) {
                return -1;
            }
            break;

        case 'X':
            if (pymain_optlist_append(pymain, &cmdline->xoptions,
                                      _PyOS_optarg) < 0) {
                return -1;
            }
            break;

        case 'q':
            cmdline->quiet_flag++;
            break;

        case 'R':
            /* Ignored */
            break;

        /* This space reserved for other options */

        default:
            /* unknown argument: parsing failed */
            return 1;
        }
    } while (1);

    if (cmdline->command == NULL && cmdline->module == NULL
        && _PyOS_optind < pymain->argc
        && wcscmp(pymain->argv[_PyOS_optind], L"-") != 0)
    {
        cmdline->filename = pymain->argv[_PyOS_optind];
    }

    /* -c and -m options are exclusive */
    assert(!(cmdline->command != NULL && cmdline->module != NULL));

    return 0;
}


static int
pymain_add_xoptions(_PyMain *pymain)
{
    _Py_OptList *options = &pymain->cmdline.xoptions;
    for (size_t i=0; i < options->len; i++) {
        wchar_t *option = options->options[i];
        if (_PySys_AddXOptionWithError(option) < 0) {
            pymain->err = _Py_INIT_NO_MEMORY();
            return -1;
        }
    }
    return 0;
}


static int
pymain_add_warnings_optlist(_Py_OptList *warnings)
{
    for (size_t i = 0; i < warnings->len; i++) {
        PyObject *option = PyUnicode_FromWideChar(warnings->options[i], -1);
        if (option == NULL) {
            return -1;
        }
        if (_PySys_AddWarnOptionWithError(option)) {
            Py_DECREF(option);
            return -1;
        }
        Py_DECREF(option);
    }
    return 0;
}


static int
pymain_add_warning_dev_mode(_PyCoreConfig *core_config)
{
    if (core_config->dev_mode) {
        PyObject *option = PyUnicode_FromString("default");
        if (option == NULL) {
            return -1;
        }
        if (_PySys_AddWarnOptionWithError(option)) {
            Py_DECREF(option);
            return -1;
        }
        Py_DECREF(option);
    }
    return 0;
}


static int
pymain_add_warning_bytes_flag(int bytes_warning_flag)
{
    /* If the bytes_warning_flag isn't set, bytesobject.c and bytearrayobject.c
     * don't even try to emit a warning, so we skip setting the filter in that
     * case.
     */
    if (bytes_warning_flag) {
        const char *filter = (bytes_warning_flag > 1) ? "error::BytesWarning":
                                                        "default::BytesWarning";
        PyObject *option = PyUnicode_FromString(filter);
        if (option == NULL) {
            return -1;
        }
        if (_PySys_AddWarnOptionWithError(option)) {
            Py_DECREF(option);
            return -1;
        }
        Py_DECREF(option);
    }
    return 0;
}


static int
pymain_add_warnings_options(_PyMain *pymain)
{
    PySys_ResetWarnOptions();

    /* The priority order for warnings configuration is (highest precedence
     * first):
     *
     * - the BytesWarning filter, if needed ('-b', '-bb')
     * - any '-W' command line options; then
     * - the 'PYTHONWARNINGS' environment variable; then
     * - the dev mode filter ('-X dev', 'PYTHONDEVMODE'); then
     * - any implicit filters added by _warnings.c/warnings.py
     *
     * All settings except the last are passed to the warnings module via
     * the `sys.warnoptions` list. Since the warnings module works on the basis
     * of "the most recently added filter will be checked first", we add
     * the lowest precedence entries first so that later entries override them.
     */

    if (pymain_add_warning_dev_mode(&pymain->core_config) < 0) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }
    if (pymain_add_warnings_optlist(&pymain->env_warning_options) < 0) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }
    if (pymain_add_warnings_optlist(&pymain->cmdline.warning_options) < 0) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }
    if (pymain_add_warning_bytes_flag(pymain->cmdline.bytes_warning) < 0) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }
    return 0;
}


/* Get warning options from PYTHONWARNINGS environment variable.
   Return 0 on success.
   Set pymain->err and return -1 on error. */
static int
pymain_warnings_envvar(_PyMain *pymain)
{
    if (Py_IgnoreEnvironmentFlag) {
        return 0;
    }

#ifdef MS_WINDOWS
    const wchar_t *wp;

    if ((wp = _wgetenv(L"PYTHONWARNINGS")) && *wp != L'\0') {
        wchar_t *warning, *context = NULL;

        wchar_t *buf = pymain_wstrdup(pymain, wp);
        if (buf == NULL) {
            return -1;
        }
        for (warning = wcstok_s(buf, L",", &context);
             warning != NULL;
             warning = wcstok_s(NULL, L",", &context)) {

            if (pymain_optlist_append(pymain, &pymain->env_warning_options,
                                      warning) < 0) {
                PyMem_RawFree(buf);
                return -1;
            }
        }
        PyMem_RawFree(buf);
    }
#else
    const char *p = pymain_get_env_var("PYTHONWARNINGS");
    if (p != NULL) {
        char *buf, *oldloc;

        /* settle for strtok here as there's no one standard
           C89 wcstok */
        buf = (char *)PyMem_RawMalloc(strlen(p) + 1);
        if (buf == NULL) {
            pymain->err = _Py_INIT_NO_MEMORY();
            return -1;
        }
        strcpy(buf, p);
        oldloc = _PyMem_RawStrdup(setlocale(LC_ALL, NULL));
        setlocale(LC_ALL, "");
        for (p = strtok(buf, ","); p != NULL; p = strtok(NULL, ",")) {
            size_t len;
            wchar_t *warning = Py_DecodeLocale(p, &len);
            if (warning == NULL) {
                SET_DECODE_ERROR("PYTHONWARNINGS environment variable", len);
                return -1;
            }
            if (pymain_optlist_append(pymain, &pymain->env_warning_options,
                                      warning) < 0) {
                PyMem_RawFree(warning);
                return -1;
            }
            PyMem_RawFree(warning);
        }
        setlocale(LC_ALL, oldloc);
        PyMem_RawFree(oldloc);
        PyMem_RawFree(buf);
    }
#endif
    return 0;
}


static void
pymain_init_stdio(_PyMain *pymain)
{
    pymain->stdin_is_interactive = (isatty(fileno(stdin))
                                    || Py_InteractiveFlag);

#if defined(MS_WINDOWS) || defined(__CYGWIN__)
    /* don't translate newlines (\r\n <=> \n) */
    _setmode(fileno(stdin), O_BINARY);
    _setmode(fileno(stdout), O_BINARY);
    _setmode(fileno(stderr), O_BINARY);
#endif

    if (Py_UnbufferedStdioFlag) {
#ifdef HAVE_SETVBUF
        setvbuf(stdin,  (char *)NULL, _IONBF, BUFSIZ);
        setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ);
        setvbuf(stderr, (char *)NULL, _IONBF, BUFSIZ);
#else /* !HAVE_SETVBUF */
        setbuf(stdin,  (char *)NULL);
        setbuf(stdout, (char *)NULL);
        setbuf(stderr, (char *)NULL);
#endif /* !HAVE_SETVBUF */
    }
    else if (Py_InteractiveFlag) {
#ifdef MS_WINDOWS
        /* Doesn't have to have line-buffered -- use unbuffered */
        /* Any set[v]buf(stdin, ...) screws up Tkinter :-( */
        setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ);
#else /* !MS_WINDOWS */
#ifdef HAVE_SETVBUF
        setvbuf(stdin,  (char *)NULL, _IOLBF, BUFSIZ);
        setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ);
#endif /* HAVE_SETVBUF */
#endif /* !MS_WINDOWS */
        /* Leave stderr alone - it should be unbuffered anyway. */
    }
}


/* Get the program name: use PYTHONEXECUTABLE and __PYVENV_LAUNCHER__
   environment variables on macOS if available. */
static _PyInitError
config_get_program_name(_PyCoreConfig *config)
{
    assert(config->program_name == NULL);

    /* If Py_SetProgramName() was called, use its value */
    const wchar_t *program_name = _Py_path_config.program_name;
    if (program_name != NULL) {
        config->program_name = _PyMem_RawWcsdup(program_name);
        if (config->program_name == NULL) {
            return _Py_INIT_NO_MEMORY();
        }
    }

#ifdef __APPLE__
    /* On MacOS X, when the Python interpreter is embedded in an
       application bundle, it gets executed by a bootstrapping script
       that does os.execve() with an argv[0] that's different from the
       actual Python executable. This is needed to keep the Finder happy,
       or rather, to work around Apple's overly strict requirements of
       the process name. However, we still need a usable sys.executable,
       so the actual executable path is passed in an environment variable.
       See Lib/plat-mac/bundlebuiler.py for details about the bootstrap
       script. */
    const char *p = pymain_get_env_var("PYTHONEXECUTABLE");
    if (p != NULL) {
        size_t len;
        wchar_t* program_name = Py_DecodeLocale(p, &len);
        if (program_name == NULL) {
            return DECODE_LOCALE_ERR("PYTHONEXECUTABLE environment "
                                     "variable", (Py_ssize_t)len);
        }
        config->program_name = program_name;
    }
#ifdef WITH_NEXT_FRAMEWORK
    else {
        const char* pyvenv_launcher = getenv("__PYVENV_LAUNCHER__");
        if (pyvenv_launcher && *pyvenv_launcher) {
            /* Used by Mac/Tools/pythonw.c to forward
             * the argv0 of the stub executable
             */
            size_t len;
            wchar_t* program_name = Py_DecodeLocale(pyvenv_launcher, &len);
            if (program_name == NULL) {
                return DECODE_LOCALE_ERR("__PYVENV_LAUNCHER__ environment "
                                         "variable", (Py_ssize_t)len);
            }
            config->program_name = program_name;
        }
    }
#endif   /* WITH_NEXT_FRAMEWORK */
#endif   /* __APPLE__ */

    return _Py_INIT_OK();
}


/* If config_get_program_name() found no program name: use argv[0] by default.
   Return 0 on success. Set pymain->err and return -1 on error. */
static int
pymain_get_program_name(_PyMain *pymain)
{
    if (pymain->core_config.program_name == NULL) {
        /* Use argv[0] by default */
        pymain->core_config.program_name = pymain_wstrdup(pymain, pymain->argv[0]);
        if (pymain->core_config.program_name == NULL) {
            return -1;
        }
    }
    return 0;
}


/* Initialize the main interpreter.
 *
 * Replaces previous call to Py_Initialize()
 *
 * Return 0 on success.
 * Set pymain->err and return -1 on error.
 */
static int
pymain_init_main_interpreter(_PyMain *pymain)
{
    _PyInitError err;

    err = _Py_InitializeMainInterpreter(&pymain->config);
    if (_Py_INIT_FAILED(err)) {
        pymain->err = err;
        return -1;
    }
    return 0;
}


static void
pymain_header(_PyMain *pymain)
{
    /* TODO: Move this to _PyRun_PrepareMain */
    if (Py_QuietFlag) {
        return;
    }

    if (!Py_VerboseFlag && (pymain->run_code || !pymain->stdin_is_interactive)) {
        return;
    }

    fprintf(stderr, "Python %s on %s\n", Py_GetVersion(), Py_GetPlatform());
    if (!Py_NoSiteFlag) {
        fprintf(stderr, "%s\n", COPYRIGHT);
    }
}


static int
pymain_create_argv_list(_PyMain *pymain)
{
    int argc = pymain->sys_argc;
    wchar_t** argv = pymain->sys_argv;

    if (argc <= 0 || pymain->sys_argv == NULL) {
        /* Ensure at least one (empty) argument is seen */
        static wchar_t *empty_argv[1] = {L""};
        argv = empty_argv;
        argc = 1;
    }

    PyObject *list = PyList_New(argc);
    if (list == NULL) {
        return -1;
    }

    for (int i = 0; i < argc; i++) {
        PyObject *v = PyUnicode_FromWideChar(argv[i], -1);
        if (v == NULL) {
            Py_DECREF(list);
            return -1;
        }
        PyList_SET_ITEM(list, i, v);
    }

    pymain->config.argv = list;
    return 0;
}


static int
pymain_init_sys_argv(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    if (cmdline->command != NULL || cmdline->module != NULL) {
        /* Backup _PyOS_optind */
        _PyOS_optind--;
    }

    /* Copy argv to be able to modify it (to force -c/-m) */
    pymain->sys_argc = pymain->argc - _PyOS_optind;
    size_t size = pymain->sys_argc * sizeof(pymain->argv[0]);
    pymain->sys_argv = PyMem_RawMalloc(size);
    if (pymain->sys_argv == NULL) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }
    memcpy(pymain->sys_argv, &pymain->argv[_PyOS_optind], size);

    if (cmdline->command != NULL) {
        /* Force sys.argv[0] = '-c' */
        pymain->sys_argv[0] = L"-c";
    }
    else if (cmdline->module != NULL) {
        /* Force sys.argv[0] = '-m'*/
        pymain->sys_argv[0] = L"-m";
    }
    return 0;
}


static int
pymain_update_sys_path(_PyMain *pymain)
{
    if (pymain->main_importer_path != NULL) {
        /* Let pymain_run_main_from_importer() adjust sys.path[0] later */
        return 0;
    }

    if (Py_IsolatedFlag) {
        return 0;
    }

    /* Prepend argv[0] to sys.path.
       If argv[0] is a symlink, use the real path. */
    PyObject *sys_path = PySys_GetObject("path");
    if (sys_path == NULL) {
        pymain->err = _Py_INIT_ERR("can't get sys.path");
        return -1;
    }

    PyObject *path0 = _PyPathConfig_ComputeArgv0(pymain->sys_argc, pymain->sys_argv);
    if (path0 == NULL) {
        pymain->err = _Py_INIT_NO_MEMORY();
        return -1;
    }

    /* Prepend path0 to sys.path */
    if (PyList_Insert(sys_path, 0, path0) < 0) {
        Py_DECREF(path0);
        pymain->err = _Py_INIT_ERR("sys.path.insert(0, path0) failed");
        return -1;
    }
    Py_DECREF(path0);

    return 0;
}


/* Get Py_xxx global configuration variables */
static void
pymain_get_global_config(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    cmdline->bytes_warning = Py_BytesWarningFlag;
    cmdline->debug = Py_DebugFlag;
    cmdline->inspect = Py_InspectFlag;
    cmdline->interactive = Py_InteractiveFlag;
    cmdline->isolated = Py_IsolatedFlag;
    cmdline->optimization_level = Py_OptimizeFlag;
    cmdline->dont_write_bytecode = Py_DontWriteBytecodeFlag;
    cmdline->no_user_site_directory = Py_NoUserSiteDirectory;
    cmdline->no_site_import = Py_NoSiteFlag;
    cmdline->use_unbuffered_io = Py_UnbufferedStdioFlag;
    cmdline->verbosity = Py_VerboseFlag;
    cmdline->quiet_flag = Py_QuietFlag;
#ifdef MS_WINDOWS
    cmdline->legacy_windows_fs_encoding = Py_LegacyWindowsFSEncodingFlag;
    cmdline->legacy_windows_stdio = Py_LegacyWindowsStdioFlag;
#endif
    cmdline->check_hash_pycs_mode = _Py_CheckHashBasedPycsMode ;

    pymain->core_config.ignore_environment = Py_IgnoreEnvironmentFlag;
    pymain->core_config.utf8_mode = Py_UTF8Mode;
}


/* Set Py_XXX global configuration variables */
static void
pymain_set_global_config(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    Py_BytesWarningFlag = cmdline->bytes_warning;
    Py_DebugFlag = cmdline->debug;
    Py_InspectFlag = cmdline->inspect;
    Py_InteractiveFlag = cmdline->interactive;
    Py_IsolatedFlag = cmdline->isolated;
    Py_OptimizeFlag = cmdline->optimization_level;
    Py_DontWriteBytecodeFlag = cmdline->dont_write_bytecode;
    Py_NoUserSiteDirectory = cmdline->no_user_site_directory;
    Py_NoSiteFlag = cmdline->no_site_import;
    Py_UnbufferedStdioFlag = cmdline->use_unbuffered_io;
    Py_VerboseFlag = cmdline->verbosity;
    Py_QuietFlag = cmdline->quiet_flag;
    _Py_CheckHashBasedPycsMode = cmdline->check_hash_pycs_mode;
#ifdef MS_WINDOWS
    Py_LegacyWindowsFSEncodingFlag = cmdline->legacy_windows_fs_encoding;
    Py_LegacyWindowsStdioFlag = cmdline->legacy_windows_stdio;
#endif

    Py_IgnoreEnvironmentFlag = pymain->core_config.ignore_environment;
    Py_UTF8Mode = pymain->core_config.utf8_mode;
}


static void
pymain_import_readline(_PyMain *pymain)
{
    if (Py_IsolatedFlag) {
        return;
    }
    if (!Py_InspectFlag && pymain->run_code) {
        return;
    }
    if (!isatty(fileno(stdin))) {
        return;
    }

    PyObject *mod = PyImport_ImportModule("readline");
    if (mod == NULL) {
        PyErr_Clear();
    }
    else {
        Py_DECREF(mod);
    }
}


static FILE*
pymain_open_filename(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;
    FILE* fp;

    fp = _Py_wfopen(cmdline->filename, L"r");
    if (fp == NULL) {
        char *cfilename_buffer;
        const char *cfilename;
        int err = errno;
        cfilename_buffer = Py_EncodeLocale(cmdline->filename, NULL);
        if (cfilename_buffer != NULL)
            cfilename = cfilename_buffer;
        else
            cfilename = "<unprintable file name>";
        fprintf(stderr, "%ls: can't open file '%s': [Errno %d] %s\n",
                pymain->argv[0], cfilename, err, strerror(err));
        PyMem_Free(cfilename_buffer);
        pymain->status = 2;
        return NULL;
    }

    if (cmdline->skip_first_line) {
        int ch;
        /* Push back first newline so line numbers
           remain the same */
        while ((ch = getc(fp)) != EOF) {
            if (ch == '\n') {
                (void)ungetc(ch, fp);
                break;
            }
        }
    }

    struct _Py_stat_struct sb;
    if (_Py_fstat_noraise(fileno(fp), &sb) == 0 &&
            S_ISDIR(sb.st_mode)) {
        fprintf(stderr,
                "%ls: '%ls' is a directory, cannot continue\n",
                pymain->argv[0], cmdline->filename);
        fclose(fp);
        pymain->status = 1;
        return NULL;
    }

    return fp;
}


static void
pymain_run_filename(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    if (cmdline->filename == NULL && pymain->stdin_is_interactive) {
        Py_InspectFlag = 0; /* do exit on SystemExit */
        pymain_run_startup(&pymain->cf);
        pymain_run_interactive_hook();
    }

    if (pymain->main_importer_path != NULL) {
        pymain->status = pymain_run_main_from_importer(pymain);
        return;
    }

    FILE *fp;
    if (cmdline->filename != NULL) {
        fp = pymain_open_filename(pymain);
        if (fp == NULL) {
            return;
        }
    }
    else {
        fp = stdin;
    }

    pymain->status = pymain_run_file(fp, cmdline->filename, &pymain->cf);
}


static void
pymain_repl(_PyMain *pymain)
{
    /* Check this environment variable at the end, to give programs the
       opportunity to set it from Python. */
    if (!Py_InspectFlag && pymain_get_env_var("PYTHONINSPECT")) {
        Py_InspectFlag = 1;
    }

    if (!(Py_InspectFlag && pymain->stdin_is_interactive
          && pymain->run_code)) {
        return;
    }

    Py_InspectFlag = 0;
    pymain_run_interactive_hook();

    int res = PyRun_AnyFileFlags(stdin, "<stdin>", &pymain->cf);
    pymain->status = (res != 0);
}


/* Parse the command line.
   Handle --version and --help options directly.

   Return 1 if Python must exit.
   Return 0 on success.
   Set pymain->err and return -1 on failure. */
static int
pymain_parse_cmdline(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    int res = pymain_parse_cmdline_impl(pymain);
    if (res < 0) {
        return -1;
    }
    if (res) {
        pymain_usage(1, pymain->argv[0]);
        pymain->status = 2;
        return 1;
    }

    if (cmdline->print_help) {
        pymain_usage(0, pymain->argv[0]);
        pymain->status = 0;
        return 1;
    }

    if (cmdline->print_version) {
        printf("Python %s\n",
               (cmdline->print_version >= 2) ? Py_GetVersion() : PY_VERSION);
        return 1;
    }

    pymain->run_code = (cmdline->command != NULL || cmdline->filename != NULL
                        || cmdline->module != NULL);

    return 0;
}


static const wchar_t*
pymain_get_xoption(_PyMain *pymain, wchar_t *name)
{
    _Py_OptList *list = &pymain->cmdline.xoptions;
    for (size_t i=0; i < list->len; i++) {
        wchar_t *option = list->options[i];
        size_t len;
        wchar_t *sep = wcschr(option, L'=');
        if (sep != NULL) {
            len = (sep - option);
        }
        else {
            len = wcslen(option);
        }
        if (wcsncmp(option, name, len) == 0 && name[len] == L'\0') {
            return option;
        }
    }
    return NULL;
}


static int
pymain_str_to_int(const char *str, int *result)
{
    errno = 0;
    const char *endptr = str;
    long value = strtol(str, (char **)&endptr, 10);
    if (*endptr != '\0' || errno == ERANGE) {
        return -1;
    }
    if (value < INT_MIN || value > INT_MAX) {
        return -1;
    }

    *result = (int)value;
    return 0;
}


static int
pymain_wstr_to_int(const wchar_t *wstr, int *result)
{
    errno = 0;
    const wchar_t *endptr = wstr;
    long value = wcstol(wstr, (wchar_t **)&endptr, 10);
    if (*endptr != '\0' || errno == ERANGE) {
        return -1;
    }
    if (value < INT_MIN || value > INT_MAX) {
        return -1;
    }

    *result = (int)value;
    return 0;
}


static int
pymain_init_tracemalloc(_PyMain *pymain)
{
    int nframe;
    int valid;

    const char *env = pymain_get_env_var("PYTHONTRACEMALLOC");
    if (env) {
        if (!pymain_str_to_int(env, &nframe)) {
            valid = (nframe >= 1);
        }
        else {
            valid = 0;
        }
        if (!valid) {
            pymain->err = _Py_INIT_USER_ERR("PYTHONTRACEMALLOC: invalid "
                                            "number of frames");
            return -1;
        }
        pymain->core_config.tracemalloc = nframe;
    }

    const wchar_t *xoption = pymain_get_xoption(pymain, L"tracemalloc");
    if (xoption) {
        const wchar_t *sep = wcschr(xoption, L'=');
        if (sep) {
            if (!pymain_wstr_to_int(sep + 1, &nframe)) {
                valid = (nframe >= 1);
            }
            else {
                valid = 0;
            }
            if (!valid) {
                pymain->err = _Py_INIT_USER_ERR("-X tracemalloc=NFRAME: "
                                                "invalid number of frames");
                return -1;
            }
        }
        else {
            /* -X tracemalloc behaves as -X tracemalloc=1 */
            nframe = 1;
        }
        pymain->core_config.tracemalloc = nframe;
    }
    return 0;
}


static void
pymain_set_flag_from_env(int *flag, const char *name)
{
    const char *var = pymain_get_env_var(name);
    if (!var) {
        return;
    }
    int value;
    if (pymain_str_to_int(var, &value) < 0 || value < 0) {
        /* PYTHONDEBUG=text and PYTHONDEBUG=-2 behave as PYTHONDEBUG=1 */
        value = 1;
    }
    if (*flag < value) {
        *flag = value;
    }
}


static void
pymain_set_flags_from_env(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;
    pymain_set_flag_from_env(&cmdline->debug,
                             "PYTHONDEBUG");
    pymain_set_flag_from_env(&cmdline->verbosity,
                             "PYTHONVERBOSE");
    pymain_set_flag_from_env(&cmdline->optimization_level,
                             "PYTHONOPTIMIZE");
    pymain_set_flag_from_env(&cmdline->inspect,
                             "PYTHONINSPECT");
    pymain_set_flag_from_env(&cmdline->dont_write_bytecode,
                             "PYTHONDONTWRITEBYTECODE");
    pymain_set_flag_from_env(&cmdline->no_user_site_directory,
                             "PYTHONNOUSERSITE");
    pymain_set_flag_from_env(&cmdline->use_unbuffered_io,
                             "PYTHONUNBUFFERED");
#ifdef MS_WINDOWS
    pymain_set_flag_from_env(&cmdline->legacy_windows_fs_encoding,
                             "PYTHONLEGACYWINDOWSFSENCODING");
    pymain_set_flag_from_env(&cmdline->legacy_windows_stdio,
                             "PYTHONLEGACYWINDOWSSTDIO");
#endif
}


static int
config_get_env_var_dup(wchar_t **dest, wchar_t *wname, char *name)
{
    if (Py_IgnoreEnvironmentFlag) {
        *dest = NULL;
        return 0;
    }

#ifdef MS_WINDOWS
    const wchar_t *var = _wgetenv(wname);
    if (!var || var[0] == '\0') {
        *dest = NULL;
        return 0;
    }

    wchar_t *copy = _PyMem_RawWcsdup(var);
    if (copy == NULL) {
        return -1;
    }

    *dest = copy;
#else
    const char *var = getenv(name);
    if (!var || var[0] == '\0') {
        *dest = NULL;
        return 0;
    }

    size_t len;
    wchar_t *wvar = Py_DecodeLocale(var, &len);
    if (!wvar) {
        if (len == (size_t)-2) {
            return -2;
        }
        else {
            return -1;
        }
    }
    *dest = wvar;
#endif
    return 0;
}


static _PyInitError
config_init_pythonpath(_PyCoreConfig *config)
{
    wchar_t *path;
    int res = config_get_env_var_dup(&path, L"PYTHONPATH", "PYTHONPATH");
    if (res < 0) {
        return DECODE_LOCALE_ERR("PYTHONHOME", res);
    }
    config->module_search_path_env = path;
    return _Py_INIT_OK();
}


static _PyInitError
config_init_home(_PyCoreConfig *config)
{
    wchar_t *home;

    /* If Py_SetPythonHome() was called, use its value */
    home = _Py_path_config.home;
    if (home) {
        config->home = _PyMem_RawWcsdup(home);
        if (config->home == NULL) {
            return _Py_INIT_NO_MEMORY();
        }
        return _Py_INIT_OK();
    }

    int res = config_get_env_var_dup(&home, L"PYTHONHOME", "PYTHONHOME");
    if (res < 0) {
        return DECODE_LOCALE_ERR("PYTHONHOME", res);
    }
    config->home = home;
    return _Py_INIT_OK();
}


_PyInitError
_PyCoreConfig_ReadEnv(_PyCoreConfig *config)
{
    _PyInitError err = config_init_home(config);
    if (_Py_INIT_FAILED(err)) {
        return err;
    }

    err = config_init_pythonpath(config);
    if (_Py_INIT_FAILED(err)) {
        return err;
    }

    err = config_get_program_name(config);
    if (_Py_INIT_FAILED(err)) {
        return err;
    }

    return _Py_INIT_OK();
}


static int
pymain_init_utf8_mode(_PyMain *pymain)
{
    _PyCoreConfig *core_config = &pymain->core_config;

#ifdef MS_WINDOWS
    if (pymain->cmdline.legacy_windows_fs_encoding) {
        core_config->utf8_mode = 0;
        return 0;
    }
#endif

    const wchar_t *xopt = pymain_get_xoption(pymain, L"utf8");
    if (xopt) {
        wchar_t *sep = wcschr(xopt, L'=');
        if (sep) {
            xopt = sep + 1;
            if (wcscmp(xopt, L"1") == 0) {
                core_config->utf8_mode = 1;
            }
            else if (wcscmp(xopt, L"0") == 0) {
                core_config->utf8_mode = 0;
            }
            else {
                pymain->err = _Py_INIT_USER_ERR("invalid -X utf8 option value");
                return -1;
            }
        }
        else {
            core_config->utf8_mode = 1;
        }
        return 0;
    }

    const char *opt = pymain_get_env_var("PYTHONUTF8");
    if (opt) {
        if (strcmp(opt, "1") == 0) {
            core_config->utf8_mode = 1;
        }
        else if (strcmp(opt, "0") == 0) {
            core_config->utf8_mode = 0;
        }
        else {
            pymain->err = _Py_INIT_USER_ERR("invalid PYTHONUTF8 environment "
                                             "variable value");
            return -1;
        }
        return 0;
    }
    return 0;
}


static int
pymain_parse_envvars(_PyMain *pymain)
{
    _PyCoreConfig *core_config = &pymain->core_config;

    /* Get environment variables */
    pymain_set_flags_from_env(pymain);

    /* The variable is only tested for existence here;
       _Py_HashRandomization_Init will check its value further. */
    if (pymain_get_env_var("PYTHONHASHSEED")) {
        Py_HashRandomizationFlag = 1;
    }

    if (pymain_warnings_envvar(pymain) < 0) {
        return -1;
    }

    _PyInitError err = _PyCoreConfig_ReadEnv(&pymain->core_config);
    if (_Py_INIT_FAILED(pymain->err)) {
        pymain->err = err;
        return -1;
    }
    if (pymain_get_program_name(pymain) < 0) {
        return -1;
    }

    core_config->allocator = pymain_get_env_var("PYTHONMALLOC");

    /* -X options */
    if (pymain_get_xoption(pymain, L"showrefcount")) {
        core_config->show_ref_count = 1;
    }
    if (pymain_get_xoption(pymain, L"showalloccount")) {
        core_config->show_alloc_count = 1;
    }

    /* More complex options: env var and/or -X option */
    if (pymain_get_env_var("PYTHONFAULTHANDLER")
       || pymain_get_xoption(pymain, L"faulthandler")) {
        core_config->faulthandler = 1;
    }
    if (pymain_get_env_var("PYTHONPROFILEIMPORTTIME")
       || pymain_get_xoption(pymain, L"importtime")) {
        core_config->import_time = 1;
    }
    if (pymain_init_tracemalloc(pymain) < 0) {
        return -1;
    }
    if (pymain_get_xoption(pymain, L"dev" ) ||
        pymain_get_env_var("PYTHONDEVMODE"))
    {
        core_config->dev_mode = 1;
        core_config->faulthandler = 1;
        core_config->allocator = "debug";
    }
    if (pymain_get_env_var("PYTHONDUMPREFS")) {
        pymain->core_config.dump_refs = 1;
    }
    if (pymain_get_env_var("PYTHONMALLOCSTATS")) {
        pymain->core_config.malloc_stats = 1;
    }

    if (pymain_init_utf8_mode(pymain) < 0) {
        return -1;
    }

    return 0;
}


/* Parse command line options and environment variables.
   This code must not use Python runtime apart PyMem_Raw memory allocator.

   Return 0 on success.
   Return 1 if Python is done and must exit.
   Set pymain->err and return -1 on error. */
static int
pymain_parse_cmdline_envvars_impl(_PyMain *pymain)
{
    int res = pymain_parse_cmdline(pymain);
    if (res < 0) {
        return -1;
    }
    if (res > 0) {
        return 1;
    }

    /* Set Py_IgnoreEnvironmentFlag needed by Py_GETENV() */
    pymain_set_global_config(pymain);

    if (pymain_parse_envvars(pymain) < 0) {
        return -1;
    }
    /* FIXME: if utf8_mode value changed, parse again cmdline */

    if (pymain_init_sys_argv(pymain) < 0) {
        return -1;
    }

    _PyInitError err = _PyCoreConfig_Read(&pymain->core_config);
    if (_Py_INIT_FAILED(err)) {
        pymain->err = err;
        return -1;
    }
    return 0;
}


static int
pymain_parse_cmdline_envvars(_PyMain *pymain)
{
    /* Force default allocator, since pymain_free() must use the same allocator
       than this function. */
    PyMemAllocatorEx old_alloc;
    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);

    int res = pymain_parse_cmdline_envvars_impl(pymain);

    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
    return res;
}


static PyObject *
config_create_path_list(const wchar_t *path, wchar_t delim)
{
    int i, n;
    const wchar_t *p;
    PyObject *v;

    n = 1;
    p = path;
    while ((p = wcschr(p, delim)) != NULL) {
        n++;
        p++;
    }
    v = PyList_New(n);
    if (v == NULL) {
        return NULL;
    }
    for (i = 0; ; i++) {
        p = wcschr(path, delim);
        if (p == NULL) {
            p = path + wcslen(path); /* End of string */
        }
        PyObject *w = PyUnicode_FromWideChar(path, (Py_ssize_t)(p - path));
        if (w == NULL) {
            Py_DECREF(v);
            return NULL;
        }
        PyList_SET_ITEM(v, i, w);
        if (*p == '\0') {
            break;
        }
        path = p+1;
    }
    return v;
}


static _PyInitError
config_init_module_search_path(_PyMainInterpreterConfig *config, _PyCoreConfig *core_config)
{
    _PyInitError err = _PyPathConfig_Init(core_config);
    if (_Py_INIT_FAILED(err)) {
        return err;
    }
    wchar_t *sys_path = Py_GetPath();

    config->module_search_path = config_create_path_list(sys_path, DELIM);
    if (config->module_search_path == NULL) {
        return _Py_INIT_NO_MEMORY();
    }
    return _Py_INIT_OK();
}


_PyInitError
_PyMainInterpreterConfig_Read(_PyMainInterpreterConfig *config, _PyCoreConfig *core_config)
{
    /* Signal handlers are installed by default */
    if (config->install_signal_handlers < 0) {
        config->install_signal_handlers = 1;
    }

    if (config->module_search_path == NULL &&
        !core_config->_disable_importlib)
    {
        _PyInitError err = config_init_module_search_path(config, core_config);
        if (_Py_INIT_FAILED(err)) {
            return err;
        }
    }

    return _Py_INIT_OK();
}


static int
pymain_init_python_core(_PyMain *pymain)
{
    pymain_set_global_config(pymain);

    pymain_init_stdio(pymain);

    pymain->err = _Py_InitializeCore(&pymain->core_config);
    if (_Py_INIT_FAILED(pymain->err)) {
        return -1;
    }
    return 0;
}


static int
pymain_init_python_main(_PyMain *pymain)
{
    if (pymain_add_xoptions(pymain)) {
        return -1;
    }
    if (pymain_add_warnings_options(pymain)) {
        return -1;
    }

    /* Create sys.argv list */
    if (pymain_create_argv_list(pymain) < 0) {
        pymain->err = _Py_INIT_ERR("failed to create sys.argv");
        return -1;
    }

    _PyInitError err = _PyMainInterpreterConfig_Read(&pymain->config,
                                                     &pymain->core_config);
    if (_Py_INIT_FAILED(err)) {
        pymain->err = err;
        return -1;
    }

    if (pymain_init_main_interpreter(pymain)) {
        return -1;
    }

    if (pymain->cmdline.filename != NULL) {
        /* If filename is a package (ex: directory or ZIP file) which contains
           __main__.py, main_importer_path is set to filename and will be
           prepended to sys.path by pymain_run_main_from_importer(). Otherwise,
           main_importer_path is set to NULL. */
        pymain->main_importer_path = pymain_get_importer(pymain->cmdline.filename);
    }

    if (pymain_update_sys_path(pymain) < 0) {
        return -1;
    }
    return 0;
}


static void
pymain_run_python(_PyMain *pymain)
{
    _Py_CommandLineDetails *cmdline = &pymain->cmdline;

    pymain_header(pymain);
    pymain_import_readline(pymain);

    if (cmdline->command) {
        pymain->status = pymain_run_command(cmdline->command, &pymain->cf);
    }
    else if (cmdline->module) {
        pymain->status = (pymain_run_module(cmdline->module, 1) != 0);
    }
    else {
        pymain_run_filename(pymain);
    }
    pymain_repl(pymain);
}


static int
pymain_init(_PyMain *pymain)
{
    pymain->err = _PyRuntime_Initialize();
    if (_Py_INIT_FAILED(pymain->err)) {
        return -1;
    }

    pymain->core_config.utf8_mode = Py_UTF8Mode;
    pymain->core_config._disable_importlib = 0;
    pymain->config.install_signal_handlers = 1;

    orig_argc = pymain->argc;           /* For Py_GetArgcArgv() */
    orig_argv = pymain->argv;
    return 0;
}


static int
pymain_impl(_PyMain *pymain)
{
    int res = pymain_init(pymain);
    if (res < 0) {
        return -1;
    }

    pymain_get_global_config(pymain);

    res = pymain_parse_cmdline_envvars(pymain);
    if (res < 0) {
        return -1;
    }
    if (res > 0) {
        /* --help or --version command: we are done */
        return 0;
    }

    res = pymain_init_python_core(pymain);
    if (res < 0) {
        return -1;
    }

    res = pymain_init_python_main(pymain);
    if (res < 0) {
        return -1;
    }

    pymain_run_python(pymain);

    pymain_free_python(pymain);

    if (Py_FinalizeEx() < 0) {
        /* Value unlikely to be confused with a non-error exit status or
           other special meaning */
        pymain->status = 120;
    }
    return 0;
}


int
Py_Main(int argc, wchar_t **argv)
{
    _PyMain pymain = _PyMain_INIT;
    memset(&pymain.cmdline, 0, sizeof(pymain.cmdline));
    pymain.argc = argc;
    pymain.argv = argv;

    if (pymain_impl(&pymain) < 0) {
        _Py_FatalInitError(pymain.err);
    }
    pymain_free(&pymain);

    return pymain.status;
}

/* this is gonna seem *real weird*, but if you put some other code between
   Py_Main() and Py_GetArgcArgv() you will need to adjust the test in the
   while statement in Misc/gdbinit:ppystack */

/* Make the *original* argc/argv available to other modules.
   This is rare, but it is needed by the secureware extension. */

void
Py_GetArgcArgv(int *argc, wchar_t ***argv)
{
    *argc = orig_argc;
    *argv = orig_argv;
}

#ifdef __cplusplus
}
#endif