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cpython/Python/importdl.c

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/* Support for dynamic loading of extension modules */
#include "Python.h"
#include "pycore_call.h"
#include "pycore_import.h"
#include "pycore_pyerrors.h" // _PyErr_FormatFromCause()
#include "pycore_pystate.h"
#include "pycore_runtime.h"
/* ./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
#include "pycore_importdl.h"
#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
/***********************************/
/* 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;
}
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;
}
/********************************/
/* 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 */
/********************************************/
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;
}
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;
}
#endif /* HAVE_DYNAMIC_LOADING */
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