/* Support for dynamic loading of extension modules */

#include "Python.h"

#include "pycore_call.h"          // _PyObject_CallMethod()

#include "pycore_import.h"        // _PyImport_SwapPackageContext()

#include "pycore_importdl.h"

#include "pycore_moduleobject.h"  // _PyModule_GetDef()

#include "pycore_pyerrors.h"      // _PyErr_FormatFromCause()

#include "pycore_runtime.h"       // _Py_ID()

/* ./configure sets HAVE_DYNAMIC_LOADING if dynamic loading of modules is

   supported on this platform. configure will then compile and link in one

   of the dynload_*.c files, as appropriate. We will call a function in

   those modules to get a function pointer to the module's init function.

*/

#ifdef HAVE_DYNAMIC_LOADING

#ifdef MS_WINDOWS

extern dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,

                                                     const char *shortname,

                                                     PyObject *pathname,

                                                     FILE *fp);

#else

extern dl_funcptr _PyImport_FindSharedFuncptr(const char *prefix,

                                              const char *shortname,

                                              const char *pathname, FILE *fp);

#endif

#endif /* HAVE_DYNAMIC_LOADING */

/***********************************/

/* module info to use when loading */

/***********************************/

static const char * const ascii_only_prefix = "PyInit";

static const char * const nonascii_prefix = "PyInitU";

/* Get the variable part of a module's export symbol name.

 * Returns a bytes instance. For non-ASCII-named modules, the name is

 * encoded as per PEP 489.

 * The hook_prefix pointer is set to either ascii_only_prefix or

 * nonascii_prefix, as appropriate.

 */

static PyObject *

get_encoded_name(PyObject *name, const char **hook_prefix) {

    PyObject *tmp;

    PyObject *encoded = NULL;

    PyObject *modname = NULL;

    Py_ssize_t name_len, lastdot;

    /* Get the short name (substring after last dot) */

    name_len = PyUnicode_GetLength(name);

    if (name_len < 0) {

        return NULL;

    }

    lastdot = PyUnicode_FindChar(name, '.', 0, name_len, -1);

    if (lastdot < -1) {

        return NULL;

    } else if (lastdot >= 0) {

        tmp = PyUnicode_Substring(name, lastdot + 1, name_len);

        if (tmp == NULL)

            return NULL;

        name = tmp;

        /* "name" now holds a new reference to the substring */

    } else {

        Py_INCREF(name);

    }

    /* Encode to ASCII or Punycode, as needed */

    encoded = PyUnicode_AsEncodedString(name, "ascii", NULL);

    if (encoded != NULL) {

        *hook_prefix = ascii_only_prefix;

    } else {

        if (PyErr_ExceptionMatches(PyExc_UnicodeEncodeError)) {

            PyErr_Clear();

            encoded = PyUnicode_AsEncodedString(name, "punycode", NULL);

            if (encoded == NULL) {

                goto error;

            }

            *hook_prefix = nonascii_prefix;

        } else {

            goto error;

        }

    }

    /* Replace '-' by '_' */

    modname = _PyObject_CallMethod(encoded, &_Py_ID(replace), "cc", '-', '_');

    if (modname == NULL)

        goto error;

    Py_DECREF(name);

    Py_DECREF(encoded);

    return modname;

error:

    Py_DECREF(name);

    Py_XDECREF(encoded);

    return NULL;

}

void

_Py_ext_module_loader_info_clear(struct _Py_ext_module_loader_info *info)

{

    Py_CLEAR(info->filename);

#ifndef MS_WINDOWS

    Py_CLEAR(info->filename_encoded);

#endif

    Py_CLEAR(info->name);

    Py_CLEAR(info->name_encoded);

}

int

_Py_ext_module_loader_info_init(struct _Py_ext_module_loader_info *p_info,

                                PyObject *name, PyObject *filename,

                                _Py_ext_module_origin origin)

{

    struct _Py_ext_module_loader_info info = {

        .origin=origin,

    };

    assert(name != NULL);

    if (!PyUnicode_Check(name)) {

        PyErr_SetString(PyExc_TypeError,

                        "module name must be a string");

        _Py_ext_module_loader_info_clear(&info);

        return -1;

    }

    assert(PyUnicode_GetLength(name) > 0);

    info.name = Py_NewRef(name);

    info.name_encoded = get_encoded_name(info.name, &info.hook_prefix);

    if (info.name_encoded == NULL) {

        _Py_ext_module_loader_info_clear(&info);

        return -1;

    }

    info.newcontext = PyUnicode_AsUTF8(info.name);

    if (info.newcontext == NULL) {

        _Py_ext_module_loader_info_clear(&info);

        return -1;

    }

    if (filename != NULL) {

        if (!PyUnicode_Check(filename)) {

            PyErr_SetString(PyExc_TypeError,

                            "module filename must be a string");

            _Py_ext_module_loader_info_clear(&info);

            return -1;

        }

        info.filename = Py_NewRef(filename);

#ifndef MS_WINDOWS

        info.filename_encoded = PyUnicode_EncodeFSDefault(info.filename);

        if (info.filename_encoded == NULL) {

            _Py_ext_module_loader_info_clear(&info);

            return -1;

        }

#endif

        info.path = info.filename;

    }

    else {

        info.path = info.name;

    }

    *p_info = info;

    return 0;

}

int

_Py_ext_module_loader_info_init_for_builtin(

                            struct _Py_ext_module_loader_info *info,

                            PyObject *name)

{

    assert(PyUnicode_Check(name));

    assert(PyUnicode_FindChar(name, '.', 0, PyUnicode_GetLength(name), -1) == -1);

    assert(PyUnicode_GetLength(name) > 0);

    PyObject *name_encoded = PyUnicode_AsEncodedString(name, "ascii", NULL);

    if (name_encoded == NULL) {

        return -1;

    }

    *info = (struct _Py_ext_module_loader_info){

        .name=Py_NewRef(name),

        .name_encoded=name_encoded,

        /* We won't need filename. */

        .path=name,

        .origin=_Py_ext_module_origin_BUILTIN,

        .hook_prefix=ascii_only_prefix,

        .newcontext=NULL,

    };

    return 0;

}

int

_Py_ext_module_loader_info_init_for_core(

                            struct _Py_ext_module_loader_info *info,

                            PyObject *name)

{

    if (_Py_ext_module_loader_info_init_for_builtin(info, name) < 0) {

        return -1;

    }

    info->origin = _Py_ext_module_origin_CORE;

    return 0;

}

#ifdef HAVE_DYNAMIC_LOADING

int

_Py_ext_module_loader_info_init_from_spec(

                            struct _Py_ext_module_loader_info *p_info,

                            PyObject *spec)

{

    PyObject *name = PyObject_GetAttrString(spec, "name");

    if (name == NULL) {

        return -1;

    }

    PyObject *filename = PyObject_GetAttrString(spec, "origin");

    if (filename == NULL) {

        Py_DECREF(name);

        return -1;

    }

    /* We could also accommodate builtin modules here without much trouble. */

    _Py_ext_module_origin origin = _Py_ext_module_origin_DYNAMIC;

    int err = _Py_ext_module_loader_info_init(p_info, name, filename, origin);

    Py_DECREF(name);

    Py_DECREF(filename);

    return err;

}

#endif /* HAVE_DYNAMIC_LOADING */

/********************************/

/* module init function results */

/********************************/

void

_Py_ext_module_loader_result_clear(struct _Py_ext_module_loader_result *res)

{

    /* Instead, the caller should have called

     * _Py_ext_module_loader_result_apply_error(). */

    assert(res->err == NULL);

    *res = (struct _Py_ext_module_loader_result){0};

}

static void

_Py_ext_module_loader_result_set_error(

                            struct _Py_ext_module_loader_result *res,

                            enum _Py_ext_module_loader_result_error_kind kind)

{

#ifndef NDEBUG

    switch (kind) {

    case _Py_ext_module_loader_result_EXCEPTION: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_UNREPORTED_EXC:

        assert(PyErr_Occurred());

        break;

    case _Py_ext_module_loader_result_ERR_MISSING: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_UNINITIALIZED: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_NONASCII_NOT_MULTIPHASE: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_NOT_MODULE: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_MISSING_DEF:

        assert(!PyErr_Occurred());

        break;

    default:

        /* We added a new error kind but forgot to add it to this switch. */

        assert(0);

    }

#endif

    assert(res->err == NULL && res->_err.exc == NULL);

    res->err = &res->_err;

    *res->err = (struct _Py_ext_module_loader_result_error){

        .kind=kind,

        .exc=PyErr_GetRaisedException(),

    };

    /* For some kinds, we also set/check res->kind. */

    switch (kind) {

    case _Py_ext_module_loader_result_ERR_UNINITIALIZED:

        assert(res->kind == _Py_ext_module_kind_UNKNOWN);

        res->kind = _Py_ext_module_kind_INVALID;

        break;

    /* None of the rest affect the result kind. */

    case _Py_ext_module_loader_result_EXCEPTION: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_MISSING: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_UNREPORTED_EXC: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_NONASCII_NOT_MULTIPHASE: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_NOT_MODULE: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_MISSING_DEF:

        break;

    default:

        /* We added a new error kind but forgot to add it to this switch. */

        assert(0);

    }

}

void

_Py_ext_module_loader_result_apply_error(

                            struct _Py_ext_module_loader_result *res,

                            const char *name)

{

    assert(!PyErr_Occurred());

    assert(res->err != NULL && res->err == &res->_err);

    struct _Py_ext_module_loader_result_error err = *res->err;

    res->err = NULL;

    /* We're otherwise done with the result at this point. */

    _Py_ext_module_loader_result_clear(res);

#ifndef NDEBUG

    switch (err.kind) {

    case _Py_ext_module_loader_result_EXCEPTION: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_UNREPORTED_EXC:

        assert(err.exc != NULL);

        break;

    case _Py_ext_module_loader_result_ERR_MISSING: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_UNINITIALIZED: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_NONASCII_NOT_MULTIPHASE: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_NOT_MODULE: _Py_FALLTHROUGH;

    case _Py_ext_module_loader_result_ERR_MISSING_DEF:

        assert(err.exc == NULL);

        break;

    default:

        /* We added a new error kind but forgot to add it to this switch. */

        assert(0);

    }

#endif

    const char *msg = NULL;

    switch (err.kind) {

    case _Py_ext_module_loader_result_EXCEPTION:

        break;

    case _Py_ext_module_loader_result_ERR_MISSING:

        msg = "initialization of %s failed without raising an exception";

        break;

    case _Py_ext_module_loader_result_ERR_UNREPORTED_EXC:

        msg = "initialization of %s raised unreported exception";

        break;

    case _Py_ext_module_loader_result_ERR_UNINITIALIZED:

        msg = "init function of %s returned uninitialized object";

        break;

    case _Py_ext_module_loader_result_ERR_NONASCII_NOT_MULTIPHASE:

        msg = "initialization of %s did not return PyModuleDef";

        break;

    case _Py_ext_module_loader_result_ERR_NOT_MODULE:

        msg = "initialization of %s did not return an extension module";

        break;

    case _Py_ext_module_loader_result_ERR_MISSING_DEF:

        msg = "initialization of %s did not return a valid extension module";

        break;

    default:

        /* We added a new error kind but forgot to add it to this switch. */

        assert(0);

        PyErr_Format(PyExc_SystemError,

                     "loading %s failed due to init function", name);

        return;

    }

    if (err.exc != NULL) {

        PyErr_SetRaisedException(err.exc);

        err.exc = NULL;  /* PyErr_SetRaisedException() stole our reference. */

        if (msg != NULL) {

            _PyErr_FormatFromCause(PyExc_SystemError, msg, name);

        }

    }

    else {

        assert(msg != NULL);

        PyErr_Format(PyExc_SystemError, msg, name);

    }

}

/********************************************/

/* getting/running the module init function */

/********************************************/

#ifdef HAVE_DYNAMIC_LOADING

PyModInitFunction

_PyImport_GetModInitFunc(struct _Py_ext_module_loader_info *info,

                         FILE *fp)

{

    const char *name_buf = PyBytes_AS_STRING(info->name_encoded);

    dl_funcptr exportfunc;

#ifdef MS_WINDOWS

    exportfunc = _PyImport_FindSharedFuncptrWindows(

            info->hook_prefix, name_buf, info->filename, fp);

#else

    {

        const char *path_buf = PyBytes_AS_STRING(info->filename_encoded);

        exportfunc = _PyImport_FindSharedFuncptr(

                        info->hook_prefix, name_buf, path_buf, fp);

    }

#endif

    if (exportfunc == NULL) {

        if (!PyErr_Occurred()) {

            PyObject *msg;

            msg = PyUnicode_FromFormat(

                "dynamic module does not define "

                "module export function (%s_%s)",

                info->hook_prefix, name_buf);

            if (msg != NULL) {

                PyErr_SetImportError(msg, info->name, info->filename);

                Py_DECREF(msg);

            }

        }

        return NULL;

    }

    return (PyModInitFunction)exportfunc;

}

#endif /* HAVE_DYNAMIC_LOADING */

int

_PyImport_RunModInitFunc(PyModInitFunction p0,

                         struct _Py_ext_module_loader_info *info,

                         struct _Py_ext_module_loader_result *p_res)

{

    struct _Py_ext_module_loader_result res = {

        .kind=_Py_ext_module_kind_UNKNOWN,

    };

    /* Call the module init function. */

    /* Package context is needed for single-phase init */

    const char *oldcontext = _PyImport_SwapPackageContext(info->newcontext);

    PyObject *m = p0();

    _PyImport_SwapPackageContext(oldcontext);

    /* Validate the result (and populate "res". */

    if (m == NULL) {

        /* The init func for multi-phase init modules is expected

         * to return a PyModuleDef after calling PyModuleDef_Init().

         * That function never raises an exception nor returns NULL,

         * so at this point it must be a single-phase init modules. */

        res.kind = _Py_ext_module_kind_SINGLEPHASE;

        if (PyErr_Occurred()) {

            _Py_ext_module_loader_result_set_error(

                        &res, _Py_ext_module_loader_result_EXCEPTION);

        }

        else {

            _Py_ext_module_loader_result_set_error(

                        &res, _Py_ext_module_loader_result_ERR_MISSING);

        }

        goto error;

    } else if (PyErr_Occurred()) {

        /* Likewise, we infer that this is a single-phase init module. */

        res.kind = _Py_ext_module_kind_SINGLEPHASE;

        _Py_ext_module_loader_result_set_error(

                &res, _Py_ext_module_loader_result_ERR_UNREPORTED_EXC);

        /* We would probably be correct to decref m here,

         * but we weren't doing so before,

         * so we stick with doing nothing. */

        m = NULL;

        goto error;

    }

    if (Py_IS_TYPE(m, NULL)) {

        /* This can happen when a PyModuleDef is returned without calling

         * PyModuleDef_Init on it

         */

        _Py_ext_module_loader_result_set_error(

                &res, _Py_ext_module_loader_result_ERR_UNINITIALIZED);

        /* Likewise, decref'ing here makes sense.  However, the original

         * code has a note about "prevent segfault in DECREF",

         * so we play it safe and leave it alone. */

        m = NULL; /* prevent segfault in DECREF */

        goto error;

    }

    if (PyObject_TypeCheck(m, &PyModuleDef_Type)) {

        /* multi-phase init */

        res.kind = _Py_ext_module_kind_MULTIPHASE;

        res.def = (PyModuleDef *)m;

        /* Run PyModule_FromDefAndSpec() to finish loading the module. */

    }

    else if (info->hook_prefix == nonascii_prefix) {

        /* Non-ASCII is only supported for multi-phase init. */

        res.kind = _Py_ext_module_kind_MULTIPHASE;

        /* Don't allow legacy init for non-ASCII module names. */

        _Py_ext_module_loader_result_set_error(

                &res, _Py_ext_module_loader_result_ERR_NONASCII_NOT_MULTIPHASE);

        goto error;

    }

    else {

        /* single-phase init (legacy) */

        res.kind = _Py_ext_module_kind_SINGLEPHASE;

        res.module = m;

        if (!PyModule_Check(m)) {

            _Py_ext_module_loader_result_set_error(

                    &res, _Py_ext_module_loader_result_ERR_NOT_MODULE);

            goto error;

        }

        res.def = _PyModule_GetDef(m);

        if (res.def == NULL) {

            PyErr_Clear();

            _Py_ext_module_loader_result_set_error(

                    &res, _Py_ext_module_loader_result_ERR_MISSING_DEF);

            goto error;

        }

    }

    assert(!PyErr_Occurred());

    assert(res.err == NULL);

    *p_res = res;

    return 0;

error:

    assert(!PyErr_Occurred());

    assert(res.err != NULL);

    Py_CLEAR(res.module);

    res.def = NULL;

    *p_res = res;

    p_res->err = &p_res->_err;

    return -1;

}