Pythonの初期化

pymain_main(_PyArgv *args)
{
    pymain_init(args);
    return Py_RunMain();
}

/* --- pymain_init() ---------------------------------------------- */

static PyStatus
pymain_init(const _PyArgv *args)
{
    PyStatus status;
    status = _PyRuntime_Initialize();

    PyPreConfig preconfig;
    PyPreConfig_InitPythonConfig(&preconfig);

    status = _Py_PreInitializeFromPyArgv(&preconfig, args);

    PyConfig config;
    PyConfig_InitPythonConfig(&config);

    /* pass NULL as the config: config is read from command line arguments,
       environment variables, configuration files */
    if (args->use_bytes_argv) {
        status = PyConfig_SetBytesArgv(&config, args->argc, args->bytes_argv);
    }
    else {
        status = PyConfig_SetArgv(&config, args->argc, args->wchar_argv);
    }

    status = Py_InitializeFromConfig(&config);
    status = _PyStatus_OK();

done:
    PyConfig_Clear(&config);
    return status;
}

PyStatus
_PyRuntime_Initialize(void)
{
    /* XXX We only initialize once in the process, which aligns with
       the static initialization of the former globals now found in
       _PyRuntime.  However, _PyRuntime *should* be initialized with
       every Py_Initialize() call, but doing so breaks the runtime.
       This is because the runtime state is not properly finalized
       currently. */
    if (runtime_initialized) {
        return _PyStatus_OK();
    }
    runtime_initialized = 1;

    return _PyRuntimeState_Init(&_PyRuntime);
}

PyStatus
_PyRuntimeState_Init(_PyRuntimeState *runtime)
{
    /* Force default allocator, since _PyRuntimeState_Fini() must
       use the same allocator than this function. */
    PyMemAllocatorEx old_alloc;
    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);

    PyStatus status = _PyRuntimeState_Init_impl(runtime);

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

static PyStatus
_PyRuntimeState_Init_impl(_PyRuntimeState *runtime)
{
    /* We preserve the hook across init, because there is
       currently no public API to set it between runtime
       initialization and interpreter initialization. */
    void *open_code_hook = runtime->open_code_hook;
    void *open_code_userdata = runtime->open_code_userdata;
    _Py_AuditHookEntry *audit_hook_head = runtime->audit_hook_head;
    // bpo-42882: Preserve next_index value if Py_Initialize()/Py_Finalize()
    // is called multiple times.
    Py_ssize_t unicode_next_index = runtime->unicode_ids.next_index;

    memset(runtime, 0, sizeof(*runtime));

    runtime->open_code_hook = open_code_hook;
    runtime->open_code_userdata = open_code_userdata;
    runtime->audit_hook_head = audit_hook_head;

    _PyEval_InitRuntimeState(&runtime->ceval);

    PyPreConfig_InitPythonConfig(&runtime->preconfig);

    runtime->gilstate.check_enabled = 1;

    /* A TSS key must be initialized with Py_tss_NEEDS_INIT
       in accordance with the specification. */
    Py_tss_t initial = Py_tss_NEEDS_INIT;
    runtime->gilstate.autoTSSkey = initial;

    runtime->interpreters.mutex = PyThread_allocate_lock();
    if (runtime->interpreters.mutex == NULL) {
        return _PyStatus_NO_MEMORY();
    }
    runtime->interpreters.next_id = -1;

    runtime->xidregistry.mutex = PyThread_allocate_lock();
    if (runtime->xidregistry.mutex == NULL) {
        return _PyStatus_NO_MEMORY();
    }

    // Set it to the ID of the main thread of the main interpreter.
    runtime->main_thread = PyThread_get_thread_ident();

    runtime->unicode_ids.lock = PyThread_allocate_lock();
    if (runtime->unicode_ids.lock == NULL) {
        return _PyStatus_NO_MEMORY();
    }
    runtime->unicode_ids.next_index = unicode_next_index;

    return _PyStatus_OK();
}

void
_PyEval_InitRuntimeState(struct _ceval_runtime_state *ceval)
{
#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
    _gil_initialize(&ceval->gil);
#endif
}

void
PyPreConfig_InitPythonConfig(PyPreConfig *config)
{
    _PyPreConfig_InitCompatConfig(config);

    config->_config_init = (int)_PyConfig_INIT_PYTHON;
    config->isolated = 0;
    config->parse_argv = 1;
    config->use_environment = 1;
    /* Set to -1 to enable C locale coercion (PEP 538) and UTF-8 Mode (PEP 540)
       depending on the LC_CTYPE locale, PYTHONUTF8 and PYTHONCOERCECLOCALE
       environment variables. */
    config->coerce_c_locale = -1;
    config->coerce_c_locale_warn = -1;
    config->utf8_mode = -1;
#ifdef MS_WINDOWS
    config->legacy_windows_fs_encoding = 0;
#endif
}

    PyPreConfig preconfig;
    PyPreConfig_InitPythonConfig(&preconfig);

void
PyPreConfig_InitPythonConfig(PyPreConfig *config)
{
    _PyPreConfig_InitCompatConfig(config);

    config->_config_init = (int)_PyConfig_INIT_PYTHON;
    config->isolated = 0;
    config->parse_argv = 1;
    config->use_environment = 1;
    /* Set to -1 to enable C locale coercion (PEP 538) and UTF-8 Mode (PEP 540)
       depending on the LC_CTYPE locale, PYTHONUTF8 and PYTHONCOERCECLOCALE
       environment variables. */
    config->coerce_c_locale = -1;
    config->coerce_c_locale_warn = -1;
    config->utf8_mode = -1;
#ifdef MS_WINDOWS
    config->legacy_windows_fs_encoding = 0;
#endif
}

void
_PyPreConfig_InitCompatConfig(PyPreConfig *config)
{
    memset(config, 0, sizeof(*config));

    config->_config_init = (int)_PyConfig_INIT_COMPAT;
    config->parse_argv = 0;
    config->isolated = -1;
    config->use_environment = -1;
    config->configure_locale = 1;

    /* bpo-36443: C locale coercion (PEP 538) and UTF-8 Mode (PEP 540)
       are disabled by default using the Compat configuration.

       Py_UTF8Mode=1 enables the UTF-8 mode. PYTHONUTF8 environment variable
       is ignored (even if use_environment=1). */
    config->utf8_mode = 0;
    config->coerce_c_locale = 0;
    config->coerce_c_locale_warn = 0;

    config->dev_mode = -1;
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
    /* bpo-40512: pymalloc is not compatible with subinterpreters,
       force usage of libc malloc() which is thread-safe. */
#ifdef Py_DEBUG
    config->allocator = PYMEM_ALLOCATOR_MALLOC_DEBUG;
#else
    config->allocator = PYMEM_ALLOCATOR_MALLOC;
#endif
#else
    config->allocator = PYMEM_ALLOCATOR_NOT_SET;
#endif
#ifdef MS_WINDOWS
    config->legacy_windows_fs_encoding = -1;
#endif
}

    status = _Py_PreInitializeFromPyArgv(&preconfig, args);

PyStatus
_Py_PreInitializeFromPyArgv(const PyPreConfig *src_config, const _PyArgv *args)
{
    PyStatus status;
    _PyRuntimeState *runtime = &_PyRuntime;

    if (runtime->preinitialized) {
        /* If it's already configured: ignored the new configuration */
        return _PyStatus_OK();
    }
    runtime->preinitializing = 1;

    PyPreConfig config;
    status = _PyPreConfig_InitFromPreConfig(&config, src_config);
    status = _PyPreConfig_Read(&config, args);
    status = _PyPreConfig_Write(&config);

    runtime->preinitializing = 0;
    runtime->preinitialized = 1;
    return _PyStatus_OK();
}

PyStatus
_PyPreConfig_InitFromPreConfig(PyPreConfig *config,
                               const PyPreConfig *config2)
{
    PyPreConfig_InitPythonConfig(config);
    preconfig_copy(config, config2);
    return _PyStatus_OK();
}

/* Read the configuration from:

   - command line arguments
   - environment variables
   - Py_xxx global configuration variables
   - the LC_CTYPE locale */
PyStatus
_PyPreConfig_Read(PyPreConfig *config, const _PyArgv *args)
{
    PyStatus status;

    status = _PyRuntime_Initialize();
    if (_PyStatus_EXCEPTION(status)) {
        return status;
    }

    preconfig_get_global_vars(config);

    /* Copy LC_CTYPE locale, since it's modified later */
    const char *loc = setlocale(LC_CTYPE, NULL);
    if (loc == NULL) {
        return _PyStatus_ERR("failed to LC_CTYPE locale");
    }
    char *init_ctype_locale = _PyMem_RawStrdup(loc);
    if (init_ctype_locale == NULL) {
        return _PyStatus_NO_MEMORY();
    }

    /* Save the config to be able to restore it if encodings change */
    PyPreConfig save_config;

    status = _PyPreConfig_InitFromPreConfig(&save_config, config);
    if (_PyStatus_EXCEPTION(status)) {
        return status;
    }

    /* Set LC_CTYPE to the user preferred locale */
    if (config->configure_locale) {
        _Py_SetLocaleFromEnv(LC_CTYPE);
    }

    _PyPreCmdline cmdline = _PyPreCmdline_INIT;
    int init_utf8_mode = Py_UTF8Mode;
#ifdef MS_WINDOWS
    int init_legacy_encoding = Py_LegacyWindowsFSEncodingFlag;
#endif

    int locale_coerced = 0;
    int loops = 0;

    while (1) {
        int utf8_mode = config->utf8_mode;

        /* Watchdog to prevent an infinite loop */
        loops++;
        if (loops == 3) {
            status = _PyStatus_ERR("Encoding changed twice while "
                                   "reading the configuration");
            goto done;
        }

        /* bpo-34207: Py_DecodeLocale() and Py_EncodeLocale() depend
           on Py_UTF8Mode and Py_LegacyWindowsFSEncodingFlag. */
        Py_UTF8Mode = config->utf8_mode;
#ifdef MS_WINDOWS
        Py_LegacyWindowsFSEncodingFlag = config->legacy_windows_fs_encoding;
#endif

        if (args) {
            // Set command line arguments at each iteration. If they are bytes
            // strings, they are decoded from the new encoding.
            status = _PyPreCmdline_SetArgv(&cmdline, args);
            if (_PyStatus_EXCEPTION(status)) {
                goto done;
            }
        }

        status = preconfig_read(config, &cmdline);
        if (_PyStatus_EXCEPTION(status)) {
            goto done;
        }

        /* The legacy C locale assumes ASCII as the default text encoding, which
         * causes problems not only for the CPython runtime, but also other
         * components like GNU readline.
         *
         * Accordingly, when the CLI detects it, it attempts to coerce it to a
         * more capable UTF-8 based alternative.
         *
         * See the documentation of the PYTHONCOERCECLOCALE setting for more
         * details.
         */
        int encoding_changed = 0;
        if (config->coerce_c_locale && !locale_coerced) {
            locale_coerced = 1;
            _Py_CoerceLegacyLocale(0);
            encoding_changed = 1;
        }

        if (utf8_mode == -1) {
            if (config->utf8_mode == 1) {
                /* UTF-8 Mode enabled */
                encoding_changed = 1;
            }
        }
        else {
            if (config->utf8_mode != utf8_mode) {
                encoding_changed = 1;
            }
        }

        if (!encoding_changed) {
            break;
        }

        /* Reset the configuration before reading again the configuration,
           just keep UTF-8 Mode and coerce C locale value. */
        int new_utf8_mode = config->utf8_mode;
        int new_coerce_c_locale = config->coerce_c_locale;
        preconfig_copy(config, &save_config);
        config->utf8_mode = new_utf8_mode;
        config->coerce_c_locale = new_coerce_c_locale;

        /* The encoding changed: read again the configuration
           with the new encoding */
    }
    status = _PyStatus_OK();

done:
    if (init_ctype_locale != NULL) {
        setlocale(LC_CTYPE, init_ctype_locale);
        PyMem_RawFree(init_ctype_locale);
    }
    Py_UTF8Mode = init_utf8_mode ;
#ifdef MS_WINDOWS
    Py_LegacyWindowsFSEncodingFlag = init_legacy_encoding;
#endif
    _PyPreCmdline_Clear(&cmdline);
    return status;
}