Python/preconfig.c

#include "Python.h"
#include "pycore_coreconfig.h"
#include "pycore_getopt.h"
#include "pycore_pystate.h"   /* _PyRuntime_Initialize() */
#include <locale.h>       /* setlocale() */


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


/* --- File system encoding/errors -------------------------------- */

/* The filesystem encoding is chosen by config_init_fs_encoding(),
   see also initfsencoding(). */
const char *Py_FileSystemDefaultEncoding = NULL;
int Py_HasFileSystemDefaultEncoding = 0;
const char *Py_FileSystemDefaultEncodeErrors = NULL;
int _Py_HasFileSystemDefaultEncodeErrors = 0;

void
_Py_ClearFileSystemEncoding(void)
{
    if (!Py_HasFileSystemDefaultEncoding && Py_FileSystemDefaultEncoding) {
        PyMem_RawFree((char*)Py_FileSystemDefaultEncoding);
        Py_FileSystemDefaultEncoding = NULL;
    }
    if (!_Py_HasFileSystemDefaultEncodeErrors && Py_FileSystemDefaultEncodeErrors) {
        PyMem_RawFree((char*)Py_FileSystemDefaultEncodeErrors);
        Py_FileSystemDefaultEncodeErrors = NULL;
    }
}


/* Set Py_FileSystemDefaultEncoding and Py_FileSystemDefaultEncodeErrors
   global configuration variables. */
int
_Py_SetFileSystemEncoding(const char *encoding, const char *errors)
{
    char *encoding2 = _PyMem_RawStrdup(encoding);
    if (encoding2 == NULL) {
        return -1;
    }

    char *errors2 = _PyMem_RawStrdup(errors);
    if (errors2 == NULL) {
        PyMem_RawFree(encoding2);
        return -1;
    }

    _Py_ClearFileSystemEncoding();

    Py_FileSystemDefaultEncoding = encoding2;
    Py_HasFileSystemDefaultEncoding = 0;

    Py_FileSystemDefaultEncodeErrors = errors2;
    _Py_HasFileSystemDefaultEncodeErrors = 0;
    return 0;
}


/* --- _PyArgv ---------------------------------------------------- */

_PyInitError
_PyArgv_Decode(const _PyArgv *args, wchar_t*** argv_p)
{
    wchar_t** argv;
    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) {
            return _Py_INIT_NO_MEMORY();
        }

        for (int 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);
                return DECODE_LOCALE_ERR("command line arguments",
                                         (Py_ssize_t)len);
            }
            argv[i] = arg;
        }
        argv[args->argc] = NULL;
    }
    else {
        argv = args->wchar_argv;
    }
    *argv_p = argv;
    return _Py_INIT_OK();
}


/* --- _PyPreCmdline ------------------------------------------------- */

typedef struct {
    const _PyArgv *args;
    int argc;
    wchar_t **argv;
    int nxoption;           /* Number of -X options */
    wchar_t **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;
}


/* --- _PyPreConfig ----------------------------------------------- */

void
_PyPreConfig_Clear(_PyPreConfig *config)
{
}


int
_PyPreConfig_Copy(_PyPreConfig *config, const _PyPreConfig *config2)
{
    _PyPreConfig_Clear(config);

#define COPY_ATTR(ATTR) config->ATTR = config2->ATTR

    COPY_ATTR(isolated);
    COPY_ATTR(use_environment);
    COPY_ATTR(coerce_c_locale);
    COPY_ATTR(coerce_c_locale_warn);
#ifdef MS_WINDOWS
    COPY_ATTR(legacy_windows_fs_encoding);
#endif
    COPY_ATTR(utf8_mode);

#undef COPY_ATTR
    return 0;
}


void
_PyPreConfig_GetGlobalConfig(_PyPreConfig *config)
{
#define COPY_FLAG(ATTR, VALUE) \
        if (config->ATTR == -1) { \
            config->ATTR = VALUE; \
        }
#define COPY_NOT_FLAG(ATTR, VALUE) \
        if (config->ATTR == -1) { \
            config->ATTR = !(VALUE); \
        }

    COPY_FLAG(isolated, Py_IsolatedFlag);
    COPY_NOT_FLAG(use_environment, Py_IgnoreEnvironmentFlag);
#ifdef MS_WINDOWS
    COPY_FLAG(legacy_windows_fs_encoding, Py_LegacyWindowsFSEncodingFlag);
#endif
    COPY_FLAG(utf8_mode, Py_UTF8Mode);

#undef COPY_FLAG
#undef COPY_NOT_FLAG
}


void
_PyPreConfig_SetGlobalConfig(const _PyPreConfig *config)
{
#define COPY_FLAG(ATTR, VAR) \
        if (config->ATTR != -1) { \
            VAR = config->ATTR; \
        }
#define COPY_NOT_FLAG(ATTR, VAR) \
        if (config->ATTR != -1) { \
            VAR = !config->ATTR; \
        }

    COPY_FLAG(isolated, Py_IsolatedFlag);
    COPY_NOT_FLAG(use_environment, Py_IgnoreEnvironmentFlag);
#ifdef MS_WINDOWS
    COPY_FLAG(legacy_windows_fs_encoding, Py_LegacyWindowsFSEncodingFlag);
#endif
    COPY_FLAG(utf8_mode, Py_UTF8Mode);

#undef COPY_FLAG
#undef COPY_NOT_FLAG
}


const char*
_PyPreConfig_GetEnv(const _PyPreConfig *config, const char *name)
{
    assert(config->use_environment >= 0);

    if (!config->use_environment) {
        return NULL;
    }

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


int
_Py_str_to_int(const char *str, int *result)
{
    const char *endptr = str;
    errno = 0;
    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;
}


void
_Py_get_env_flag(_PyPreConfig *config, int *flag, const char *name)
{
    const char *var = _PyPreConfig_GetEnv(config, name);
    if (!var) {
        return;
    }
    int value;
    if (_Py_str_to_int(var, &value) < 0 || value < 0) {
        /* PYTHONDEBUG=text and PYTHONDEBUG=-2 behave as PYTHONDEBUG=1 */
        value = 1;
    }
    if (*flag < value) {
        *flag = value;
    }
}


const wchar_t*
_Py_get_xoption(int nxoption, wchar_t * const *xoptions, const wchar_t *name)
{
    for (int i=0; i < nxoption; i++) {
        const wchar_t *option = xoptions[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 _PyInitError
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");
    }
    else {
        xopt = NULL;
    }
    if (xopt) {
        wchar_t *sep = wcschr(xopt, L'=');
        if (sep) {
            xopt = sep + 1;
            if (wcscmp(xopt, L"1") == 0) {
                config->utf8_mode = 1;
            }
            else if (wcscmp(xopt, L"0") == 0) {
                config->utf8_mode = 0;
            }
            else {
                return _Py_INIT_USER_ERR("invalid -X utf8 option value");
            }
        }
        else {
            config->utf8_mode = 1;
        }
        return _Py_INIT_OK();
    }

    const char *opt = _PyPreConfig_GetEnv(config, "PYTHONUTF8");
    if (opt) {
        if (strcmp(opt, "1") == 0) {
            config->utf8_mode = 1;
        }
        else if (strcmp(opt, "0") == 0) {
            config->utf8_mode = 0;
        }
        else {
            return _Py_INIT_USER_ERR("invalid PYTHONUTF8 environment "
                                     "variable value");
        }
        return _Py_INIT_OK();
    }

    return _Py_INIT_OK();
}


static void
preconfig_init_locale(_PyPreConfig *config)
{
    /* Test also if coerce_c_locale equals 1: PYTHONCOERCECLOCALE=1 doesn't
       imply that the C locale is always coerced. It is only coerced if
       if the LC_CTYPE locale is "C". */
    if (config->coerce_c_locale != 0) {
        /* The C locale enables the C locale coercion (PEP 538) */
        if (_Py_LegacyLocaleDetected()) {
            config->coerce_c_locale = 1;
        }
        else {
            config->coerce_c_locale = 0;
        }
    }
}


static _PyInitError
preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
{
    _PyPreConfig_GetGlobalConfig(config);

    if (config->isolated > 0) {
        config->use_environment = 0;
    }

    /* Default values */
    if (config->use_environment < 0) {
        config->use_environment = 0;
    }

    if (config->use_environment) {
#ifdef MS_WINDOWS
        _Py_get_env_flag(config, &config->legacy_windows_fs_encoding,
                "PYTHONLEGACYWINDOWSFSENCODING");
#endif

        const char *env = _PyPreConfig_GetEnv(config, "PYTHONCOERCECLOCALE");
        if (env) {
            if (strcmp(env, "0") == 0) {
                if (config->coerce_c_locale < 0) {
                    config->coerce_c_locale = 0;
                }
            }
            else if (strcmp(env, "warn") == 0) {
                config->coerce_c_locale_warn = 1;
            }
            else {
                if (config->coerce_c_locale < 0) {
                    config->coerce_c_locale = 1;
                }
            }
        }
    }

#ifdef MS_WINDOWS
    if (config->legacy_windows_fs_encoding) {
        config->utf8_mode = 0;
    }
#endif

    if (config->utf8_mode < 0) {
        _PyInitError err = preconfig_init_utf8_mode(config, cmdline);
        if (_Py_INIT_FAILED(err)) {
            return err;
        }
    }

    if (config->coerce_c_locale != 0) {
        preconfig_init_locale(config);
    }

#ifndef MS_WINDOWS
    if (config->utf8_mode < 0) {
        /* The C locale and the POSIX locale enable the UTF-8 Mode (PEP 540) */
        const char *ctype_loc = setlocale(LC_CTYPE, NULL);
        if (ctype_loc != NULL
           && (strcmp(ctype_loc, "C") == 0
               || strcmp(ctype_loc, "POSIX") == 0))
        {
            config->utf8_mode = 1;
        }
    }
#endif

    if (config->coerce_c_locale < 0) {
        config->coerce_c_locale = 0;
    }
    if (config->utf8_mode < 0) {
        config->utf8_mode = 0;
    }

    assert(config->coerce_c_locale >= 0);
    assert(config->utf8_mode >= 0);
    assert(config->isolated >= 0);
    assert(config->use_environment >= 0);

    return _Py_INIT_OK();
}


_PyInitError
_PyPreConfig_Read(_PyPreConfig *config)
{
    return preconfig_read(config, NULL);
}


int
_PyPreConfig_AsDict(const _PyPreConfig *config, PyObject *dict)
{
#define SET_ITEM(KEY, EXPR) \
        do { \
            PyObject *obj = (EXPR); \
            if (obj == NULL) { \
                goto fail; \
            } \
            int res = PyDict_SetItemString(dict, (KEY), obj); \
            Py_DECREF(obj); \
            if (res < 0) { \
                goto fail; \
            } \
        } while (0)
#define SET_ITEM_INT(ATTR) \
    SET_ITEM(#ATTR, PyLong_FromLong(config->ATTR))

    SET_ITEM_INT(isolated);
    SET_ITEM_INT(use_environment);
    SET_ITEM_INT(coerce_c_locale);
    SET_ITEM_INT(coerce_c_locale_warn);
    SET_ITEM_INT(utf8_mode);
#ifdef MS_WINDOWS
    SET_ITEM_INT(legacy_windows_fs_encoding);
#endif
    return 0;

fail:
    return -1;

#undef SET_ITEM
#undef SET_ITEM_INT
}


/* Parse the command line arguments */
static _PyInitError
preconfig_parse_cmdline(_PyPreConfig *config, _PyPreCmdline *cmdline)
{
    _PyOS_ResetGetOpt();
    /* Don't log parsing errors into stderr here: _PyCoreConfig_ReadFromArgv()
       is responsible for that */
    _PyOS_opterr = 0;
    do {
        int longindex = -1;
        int c = _PyOS_GetOpt(cmdline->args->argc, cmdline->argv, &longindex);

        if (c == EOF || c == 'c' || c == 'm') {
            break;
        }

        switch (c) {
        case 'E':
            config->use_environment = 0;
            break;

        case 'I':
            config->isolated++;
            break;

        case 'X':
        {
            _PyInitError err;
            err = _Py_wstrlist_append(&cmdline->nxoption,
                                      &cmdline->xoptions,
                                      _PyOS_optarg);
            if (_Py_INIT_FAILED(err)) {
                return err;
            }
            break;
        }

        default:
            /* ignore other argument:
               handled by _PyCoreConfig_ReadFromArgv() */
            break;
        }
    } while (1);

    return _Py_INIT_OK();
}


static _PyInitError
preconfig_from_argv(_PyPreConfig *config, const _PyArgv *args)
{
    _PyInitError err;

    _PyPreCmdline cmdline;
    memset(&cmdline, 0, sizeof(cmdline));
    cmdline.args = args;

    err = _PyArgv_Decode(cmdline.args, &cmdline.argv);
    if (_Py_INIT_FAILED(err)) {
        goto done;
    }

    err = preconfig_parse_cmdline(config, &cmdline);
    if (_Py_INIT_FAILED(err)) {
        goto done;
    }

    err = preconfig_read(config, &cmdline);
    if (_Py_INIT_FAILED(err)) {
        goto done;
    }
    err = _Py_INIT_OK();

done:
    precmdline_clear(&cmdline);
    return err;
}


/* Read the preconfiguration. */
_PyInitError
_PyPreConfig_ReadFromArgv(_PyPreConfig *config, const _PyArgv *args)
{
    _PyInitError err;

    err = _PyRuntime_Initialize();
    if (_Py_INIT_FAILED(err)) {
        return err;
    }

    char *init_ctype_locale = NULL;
    int init_utf8_mode = Py_UTF8Mode;
#ifdef MS_WINDOWS
    int init_legacy_encoding = Py_LegacyWindowsFSEncodingFlag;
#endif
    _PyPreConfig save_config = _PyPreConfig_INIT;
    int locale_coerced = 0;
    int loops = 0;

    /* copy LC_CTYPE locale */
    const char *loc = setlocale(LC_CTYPE, NULL);
    if (loc == NULL) {
        err = _Py_INIT_ERR("failed to LC_CTYPE locale");
        goto done;
    }
    init_ctype_locale = _PyMem_RawStrdup(loc);
    if (init_ctype_locale == NULL) {
        err = _Py_INIT_NO_MEMORY();
        goto done;
    }

    if (_PyPreConfig_Copy(&save_config, config) < 0) {
        err = _Py_INIT_NO_MEMORY();
        goto done;
    }

    /* Set LC_CTYPE to the user preferred locale */
    _Py_SetLocaleFromEnv(LC_CTYPE);

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

        /* Watchdog to prevent an infinite loop */
        loops++;
        if (loops == 3) {
            err = _Py_INIT_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

        err = preconfig_from_argv(config, args);
        if (_Py_INIT_FAILED(err)) {
            goto done;
        }

        if (locale_coerced) {
            config->coerce_c_locale = 1;
        }

        /* 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 value. */
        int new_utf8_mode = config->utf8_mode;
        int new_coerce_c_locale = config->coerce_c_locale;
        if (_PyPreConfig_Copy(config, &save_config) < 0) {
            err = _Py_INIT_NO_MEMORY();
            goto done;
        }
        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 */
    }
    err = _Py_INIT_OK();

done:
    if (init_ctype_locale != NULL) {
        setlocale(LC_CTYPE, init_ctype_locale);
    }
    _PyPreConfig_Clear(&save_config);
    Py_UTF8Mode = init_utf8_mode ;
#ifdef MS_WINDOWS
    Py_LegacyWindowsFSEncodingFlag = init_legacy_encoding;
#endif
    return err;
}


void
_PyPreConfig_Write(const _PyPreConfig *config)
{
    _PyPreConfig_SetGlobalConfig(config);

    if (config->coerce_c_locale) {
        _Py_CoerceLegacyLocale(config->coerce_c_locale_warn);
    }

    /* Set LC_CTYPE to the user preferred locale */
    _Py_SetLocaleFromEnv(LC_CTYPE);
}