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4862 lines (4216 loc) · 143 KB
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/* Module definition and import implementation */
#include "Python.h"
#include "pycore_audit.h" // _PySys_Audit()
#include "pycore_ceval.h"
#include "pycore_hashtable.h" // _Py_hashtable_new_full()
#include "pycore_import.h" // _PyImport_BootstrapImp()
#include "pycore_initconfig.h" // _PyStatus_OK()
#include "pycore_interp.h" // struct _import_runtime_state
#include "pycore_magic_number.h" // PYC_MAGIC_NUMBER_TOKEN
#include "pycore_namespace.h" // _PyNamespace_Type
#include "pycore_object.h" // _Py_SetImmortal()
#include "pycore_pyerrors.h" // _PyErr_SetString()
#include "pycore_pyhash.h" // _Py_KeyedHash()
#include "pycore_pylifecycle.h"
#include "pycore_pymem.h" // _PyMem_SetDefaultAllocator()
#include "pycore_pystate.h" // _PyInterpreterState_GET()
#include "pycore_sysmodule.h" // _PySys_ClearAttrString()
#include "pycore_time.h" // _PyTime_AsMicroseconds()
#include "pycore_weakref.h" // _PyWeakref_GET_REF()
#include "marshal.h" // PyMarshal_ReadObjectFromString()
#include "pycore_importdl.h" // _PyImport_DynLoadFiletab
#include "pydtrace.h" // PyDTrace_IMPORT_FIND_LOAD_START_ENABLED()
#include <stdbool.h> // bool
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
/*[clinic input]
module _imp
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=9c332475d8686284]*/
#include "clinic/import.c.h"
#ifndef NDEBUG
static bool
is_interpreter_isolated(PyInterpreterState *interp)
{
return !_Py_IsMainInterpreter(interp)
&& !(interp->feature_flags & Py_RTFLAGS_USE_MAIN_OBMALLOC)
&& interp->ceval.own_gil;
}
#endif
/*******************************/
/* process-global import state */
/*******************************/
/* This table is defined in config.c: */
extern struct _inittab _PyImport_Inittab[];
// This is not used after Py_Initialize() is called.
// (See _PyRuntimeState.imports.inittab.)
struct _inittab *PyImport_Inittab = _PyImport_Inittab;
// When we dynamically allocate a larger table for PyImport_ExtendInittab(),
// we track the pointer here so we can deallocate it during finalization.
static struct _inittab *inittab_copy = NULL;
/*******************************/
/* runtime-global import state */
/*******************************/
#define INITTAB _PyRuntime.imports.inittab
#define LAST_MODULE_INDEX _PyRuntime.imports.last_module_index
#define EXTENSIONS _PyRuntime.imports.extensions
#define PKGCONTEXT (_PyRuntime.imports.pkgcontext)
/*******************************/
/* interpreter import state */
/*******************************/
#define MODULES(interp) \
(interp)->imports.modules
#define MODULES_BY_INDEX(interp) \
(interp)->imports.modules_by_index
#define IMPORTLIB(interp) \
(interp)->imports.importlib
#define OVERRIDE_MULTI_INTERP_EXTENSIONS_CHECK(interp) \
(interp)->imports.override_multi_interp_extensions_check
#define OVERRIDE_FROZEN_MODULES(interp) \
(interp)->imports.override_frozen_modules
#ifdef HAVE_DLOPEN
# define DLOPENFLAGS(interp) \
(interp)->imports.dlopenflags
#endif
#define IMPORT_FUNC(interp) \
(interp)->imports.import_func
#define IMPORT_LOCK(interp) \
(interp)->imports.lock
#define FIND_AND_LOAD(interp) \
(interp)->imports.find_and_load
/*******************/
/* the import lock */
/*******************/
/* Locking primitives to prevent parallel imports of the same module
in different threads to return with a partially loaded module.
These calls are serialized by the global interpreter lock. */
void
_PyImport_AcquireLock(PyInterpreterState *interp)
{
_PyRecursiveMutex_Lock(&IMPORT_LOCK(interp));
}
void
_PyImport_ReleaseLock(PyInterpreterState *interp)
{
_PyRecursiveMutex_Unlock(&IMPORT_LOCK(interp));
}
void
_PyImport_ReInitLock(PyInterpreterState *interp)
{
// gh-126688: Thread id may change after fork() on some operating systems.
IMPORT_LOCK(interp).thread = PyThread_get_thread_ident_ex();
}
/***************/
/* sys.modules */
/***************/
PyObject *
_PyImport_InitModules(PyInterpreterState *interp)
{
assert(MODULES(interp) == NULL);
MODULES(interp) = PyDict_New();
if (MODULES(interp) == NULL) {
return NULL;
}
return MODULES(interp);
}
PyObject *
_PyImport_GetModules(PyInterpreterState *interp)
{
return MODULES(interp);
}
void
_PyImport_ClearModules(PyInterpreterState *interp)
{
Py_SETREF(MODULES(interp), NULL);
}
static inline PyObject *
get_modules_dict(PyThreadState *tstate, bool fatal)
{
/* Technically, it would make sense to incref the dict,
* since sys.modules could be swapped out and decref'ed to 0
* before the caller is done using it. However, that is highly
* unlikely, especially since we can rely on a global lock
* (i.e. the GIL) for thread-safety. */
PyObject *modules = MODULES(tstate->interp);
if (modules == NULL) {
if (fatal) {
Py_FatalError("interpreter has no modules dictionary");
}
_PyErr_SetString(tstate, PyExc_RuntimeError,
"unable to get sys.modules");
return NULL;
}
return modules;
}
PyObject *
PyImport_GetModuleDict(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return get_modules_dict(tstate, true);
}
int
_PyImport_SetModule(PyObject *name, PyObject *m)
{
PyThreadState *tstate = _PyThreadState_GET();
PyObject *modules = get_modules_dict(tstate, true);
return PyObject_SetItem(modules, name, m);
}
int
_PyImport_SetModuleString(const char *name, PyObject *m)
{
PyThreadState *tstate = _PyThreadState_GET();
PyObject *modules = get_modules_dict(tstate, true);
return PyMapping_SetItemString(modules, name, m);
}
static PyObject *
import_get_module(PyThreadState *tstate, PyObject *name)
{
PyObject *modules = get_modules_dict(tstate, false);
if (modules == NULL) {
return NULL;
}
PyObject *m;
Py_INCREF(modules);
(void)PyMapping_GetOptionalItem(modules, name, &m);
Py_DECREF(modules);
return m;
}
static int
import_ensure_initialized(PyInterpreterState *interp, PyObject *mod, PyObject *name)
{
PyObject *spec;
/* Optimization: only call _bootstrap._lock_unlock_module() if
__spec__._initializing is true.
NOTE: because of this, initializing must be set *before*
stuffing the new module in sys.modules.
*/
int rc = PyObject_GetOptionalAttr(mod, &_Py_ID(__spec__), &spec);
if (rc > 0) {
rc = _PyModuleSpec_IsInitializing(spec);
Py_DECREF(spec);
}
if (rc <= 0) {
return rc;
}
/* Wait until module is done importing. */
PyObject *value = PyObject_CallMethodOneArg(
IMPORTLIB(interp), &_Py_ID(_lock_unlock_module), name);
if (value == NULL) {
return -1;
}
Py_DECREF(value);
return 0;
}
static void remove_importlib_frames(PyThreadState *tstate);
PyObject *
PyImport_GetModule(PyObject *name)
{
PyThreadState *tstate = _PyThreadState_GET();
PyObject *mod;
mod = import_get_module(tstate, name);
if (mod != NULL && mod != Py_None) {
if (import_ensure_initialized(tstate->interp, mod, name) < 0) {
Py_DECREF(mod);
remove_importlib_frames(tstate);
return NULL;
}
}
return mod;
}
/* Get the module object corresponding to a module name.
First check the modules dictionary if there's one there,
if not, create a new one and insert it in the modules dictionary. */
static PyObject *
import_add_module(PyThreadState *tstate, PyObject *name)
{
PyObject *modules = get_modules_dict(tstate, false);
if (modules == NULL) {
return NULL;
}
PyObject *m;
if (PyMapping_GetOptionalItem(modules, name, &m) < 0) {
return NULL;
}
if (m != NULL && PyModule_Check(m)) {
return m;
}
Py_XDECREF(m);
m = PyModule_NewObject(name);
if (m == NULL)
return NULL;
if (PyObject_SetItem(modules, name, m) != 0) {
Py_DECREF(m);
return NULL;
}
return m;
}
PyObject *
PyImport_AddModuleRef(const char *name)
{
PyObject *name_obj = PyUnicode_FromString(name);
if (name_obj == NULL) {
return NULL;
}
PyThreadState *tstate = _PyThreadState_GET();
PyObject *module = import_add_module(tstate, name_obj);
Py_DECREF(name_obj);
return module;
}
PyObject *
PyImport_AddModuleObject(PyObject *name)
{
PyThreadState *tstate = _PyThreadState_GET();
PyObject *mod = import_add_module(tstate, name);
if (!mod) {
return NULL;
}
// gh-86160: PyImport_AddModuleObject() returns a borrowed reference.
// Create a weak reference to produce a borrowed reference, since it can
// become NULL. sys.modules type can be different than dict and it is not
// guaranteed that it keeps a strong reference to the module. It can be a
// custom mapping with __getitem__() which returns a new object or removes
// returned object, or __setitem__ which does nothing. There is so much
// unknown. With weakref we can be sure that we get either a reference to
// live object or NULL.
//
// Use PyImport_AddModuleRef() to avoid these issues.
PyObject *ref = PyWeakref_NewRef(mod, NULL);
Py_DECREF(mod);
if (ref == NULL) {
return NULL;
}
mod = _PyWeakref_GET_REF(ref);
Py_DECREF(ref);
Py_XDECREF(mod);
if (mod == NULL && !PyErr_Occurred()) {
PyErr_SetString(PyExc_RuntimeError,
"sys.modules does not hold a strong reference "
"to the module");
}
return mod; /* borrowed reference */
}
PyObject *
PyImport_AddModule(const char *name)
{
PyObject *nameobj = PyUnicode_FromString(name);
if (nameobj == NULL) {
return NULL;
}
PyObject *module = PyImport_AddModuleObject(nameobj);
Py_DECREF(nameobj);
return module;
}
/* Remove name from sys.modules, if it's there.
* Can be called with an exception raised.
* If fail to remove name a new exception will be chained with the old
* exception, otherwise the old exception is preserved.
*/
static void
remove_module(PyThreadState *tstate, PyObject *name)
{
PyObject *exc = _PyErr_GetRaisedException(tstate);
PyObject *modules = get_modules_dict(tstate, true);
if (PyDict_CheckExact(modules)) {
// Error is reported to the caller
(void)PyDict_Pop(modules, name, NULL);
}
else if (PyMapping_DelItem(modules, name) < 0) {
if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
_PyErr_Clear(tstate);
}
}
_PyErr_ChainExceptions1(exc);
}
/************************************/
/* per-interpreter modules-by-index */
/************************************/
Py_ssize_t
_PyImport_GetNextModuleIndex(void)
{
return _Py_atomic_add_ssize(&LAST_MODULE_INDEX, 1) + 1;
}
#ifndef NDEBUG
struct extensions_cache_value;
static struct extensions_cache_value * _find_cached_def(PyModuleDef *);
static Py_ssize_t _get_cached_module_index(struct extensions_cache_value *);
#endif
static Py_ssize_t
_get_module_index_from_def(PyModuleDef *def)
{
Py_ssize_t index = def->m_base.m_index;
#ifndef NDEBUG
struct extensions_cache_value *cached = _find_cached_def(def);
assert(cached == NULL || index == _get_cached_module_index(cached));
#endif
return index;
}
static void
_set_module_index(PyModuleDef *def, Py_ssize_t index)
{
assert(index > 0);
if (index == def->m_base.m_index) {
/* There's nothing to do. */
}
else if (def->m_base.m_index == 0) {
/* It should have been initialized by PyModuleDef_Init().
* We assert here to catch this in dev, but keep going otherwise. */
assert(def->m_base.m_index != 0);
def->m_base.m_index = index;
}
else {
/* It was already set for a different module.
* We replace the old value. */
assert(def->m_base.m_index > 0);
def->m_base.m_index = index;
}
}
static const char *
_modules_by_index_check(PyInterpreterState *interp, Py_ssize_t index)
{
if (index <= 0) {
return "invalid module index";
}
if (MODULES_BY_INDEX(interp) == NULL) {
return "Interpreters module-list not accessible.";
}
if (index >= PyList_GET_SIZE(MODULES_BY_INDEX(interp))) {
return "Module index out of bounds.";
}
return NULL;
}
static PyObject *
_modules_by_index_get(PyInterpreterState *interp, Py_ssize_t index)
{
if (_modules_by_index_check(interp, index) != NULL) {
return NULL;
}
PyObject *res = PyList_GET_ITEM(MODULES_BY_INDEX(interp), index);
return res==Py_None ? NULL : res;
}
static int
_modules_by_index_set(PyInterpreterState *interp,
Py_ssize_t index, PyObject *module)
{
assert(index > 0);
if (MODULES_BY_INDEX(interp) == NULL) {
MODULES_BY_INDEX(interp) = PyList_New(0);
if (MODULES_BY_INDEX(interp) == NULL) {
return -1;
}
}
while (PyList_GET_SIZE(MODULES_BY_INDEX(interp)) <= index) {
if (PyList_Append(MODULES_BY_INDEX(interp), Py_None) < 0) {
return -1;
}
}
return PyList_SetItem(MODULES_BY_INDEX(interp), index, Py_NewRef(module));
}
static int
_modules_by_index_clear_one(PyInterpreterState *interp, Py_ssize_t index)
{
const char *err = _modules_by_index_check(interp, index);
if (err != NULL) {
Py_FatalError(err);
return -1;
}
return PyList_SetItem(MODULES_BY_INDEX(interp), index, Py_NewRef(Py_None));
}
PyObject*
PyState_FindModule(PyModuleDef* module)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
if (module->m_slots) {
return NULL;
}
Py_ssize_t index = _get_module_index_from_def(module);
return _modules_by_index_get(interp, index);
}
/* _PyState_AddModule() has been completely removed from the C-API
(and was removed from the limited API in 3.6). However, we're
playing it safe and keeping it around for any stable ABI extensions
built against 3.2-3.5. */
int
_PyState_AddModule(PyThreadState *tstate, PyObject* module, PyModuleDef* def)
{
if (!def) {
assert(_PyErr_Occurred(tstate));
return -1;
}
if (def->m_slots) {
_PyErr_SetString(tstate,
PyExc_SystemError,
"PyState_AddModule called on module with slots");
return -1;
}
assert(def->m_slots == NULL);
Py_ssize_t index = _get_module_index_from_def(def);
return _modules_by_index_set(tstate->interp, index, module);
}
int
PyState_AddModule(PyObject* module, PyModuleDef* def)
{
if (!def) {
Py_FatalError("module definition is NULL");
return -1;
}
PyThreadState *tstate = _PyThreadState_GET();
if (def->m_slots) {
_PyErr_SetString(tstate,
PyExc_SystemError,
"PyState_AddModule called on module with slots");
return -1;
}
PyInterpreterState *interp = tstate->interp;
Py_ssize_t index = _get_module_index_from_def(def);
if (MODULES_BY_INDEX(interp) &&
index < PyList_GET_SIZE(MODULES_BY_INDEX(interp)) &&
module == PyList_GET_ITEM(MODULES_BY_INDEX(interp), index))
{
_Py_FatalErrorFormat(__func__, "module %p already added", module);
return -1;
}
assert(def->m_slots == NULL);
return _modules_by_index_set(interp, index, module);
}
int
PyState_RemoveModule(PyModuleDef* def)
{
PyThreadState *tstate = _PyThreadState_GET();
if (def->m_slots) {
_PyErr_SetString(tstate,
PyExc_SystemError,
"PyState_RemoveModule called on module with slots");
return -1;
}
Py_ssize_t index = _get_module_index_from_def(def);
return _modules_by_index_clear_one(tstate->interp, index);
}
// Used by finalize_modules()
void
_PyImport_ClearModulesByIndex(PyInterpreterState *interp)
{
if (!MODULES_BY_INDEX(interp)) {
return;
}
Py_ssize_t i;
for (i = 0; i < PyList_GET_SIZE(MODULES_BY_INDEX(interp)); i++) {
PyObject *m = PyList_GET_ITEM(MODULES_BY_INDEX(interp), i);
if (PyModule_Check(m)) {
/* cleanup the saved copy of module dicts */
PyModuleDef *md = PyModule_GetDef(m);
if (md) {
// XXX Do this more carefully. The dict might be owned
// by another interpreter.
Py_CLEAR(md->m_base.m_copy);
}
}
}
/* Setting modules_by_index to NULL could be dangerous, so we
clear the list instead. */
if (PyList_SetSlice(MODULES_BY_INDEX(interp),
0, PyList_GET_SIZE(MODULES_BY_INDEX(interp)),
NULL)) {
PyErr_FormatUnraisable("Exception ignored on clearing interpreters module list");
}
}
/*********************/
/* extension modules */
/*********************/
/*
It may help to have a big picture view of what happens
when an extension is loaded. This includes when it is imported
for the first time.
Here's a summary, using importlib._bootstrap._load() as a starting point.
1. importlib._bootstrap._load()
2. _load(): acquire import lock
3. _load() -> importlib._bootstrap._load_unlocked()
4. _load_unlocked() -> importlib._bootstrap.module_from_spec()
5. module_from_spec() -> ExtensionFileLoader.create_module()
6. create_module() -> _imp.create_dynamic()
(see below)
7. module_from_spec() -> importlib._bootstrap._init_module_attrs()
8. _load_unlocked(): sys.modules[name] = module
9. _load_unlocked() -> ExtensionFileLoader.exec_module()
10. exec_module() -> _imp.exec_dynamic()
(see below)
11. _load(): release import lock
...for single-phase init modules, where m_size == -1:
(6). first time (not found in _PyRuntime.imports.extensions):
A. _imp_create_dynamic_impl() -> import_find_extension()
B. _imp_create_dynamic_impl() -> _PyImport_GetModInitFunc()
C. _PyImport_GetModInitFunc(): load <module init func>
D. _imp_create_dynamic_impl() -> import_run_extension()
E. import_run_extension() -> _PyImport_RunModInitFunc()
F. _PyImport_RunModInitFunc(): call <module init func>
G. <module init func> -> PyModule_Create() -> PyModule_Create2()
-> PyModule_CreateInitialized()
H. PyModule_CreateInitialized() -> PyModule_New()
I. PyModule_CreateInitialized(): allocate mod->md_state
J. PyModule_CreateInitialized() -> PyModule_AddFunctions()
K. PyModule_CreateInitialized() -> PyModule_SetDocString()
L. PyModule_CreateInitialized(): set mod->md_def
M. <module init func>: initialize the module, etc.
N. import_run_extension()
-> _PyImport_CheckSubinterpIncompatibleExtensionAllowed()
O. import_run_extension(): set __file__
P. import_run_extension() -> update_global_state_for_extension()
Q. update_global_state_for_extension():
copy __dict__ into def->m_base.m_copy
R. update_global_state_for_extension():
add it to _PyRuntime.imports.extensions
S. import_run_extension() -> finish_singlephase_extension()
T. finish_singlephase_extension():
add it to interp->imports.modules_by_index
U. finish_singlephase_extension(): add it to sys.modules
Step (Q) is skipped for core modules (sys/builtins).
(6). subsequent times (found in _PyRuntime.imports.extensions):
A. _imp_create_dynamic_impl() -> import_find_extension()
B. import_find_extension() -> reload_singlephase_extension()
C. reload_singlephase_extension()
-> _PyImport_CheckSubinterpIncompatibleExtensionAllowed()
D. reload_singlephase_extension() -> import_add_module()
E. if name in sys.modules: use that module
F. else:
1. import_add_module() -> PyModule_NewObject()
2. import_add_module(): set it on sys.modules
G. reload_singlephase_extension(): copy the "m_copy" dict into __dict__
H. reload_singlephase_extension(): add to modules_by_index
(10). (every time):
A. noop
...for single-phase init modules, where m_size >= 0:
(6). not main interpreter and never loaded there - every time (not found in _PyRuntime.imports.extensions):
A-P. (same as for m_size == -1)
Q. _PyImport_RunModInitFunc(): set def->m_base.m_init
R. (skipped)
S-U. (same as for m_size == -1)
(6). main interpreter - first time (not found in _PyRuntime.imports.extensions):
A-P. (same as for m_size == -1)
Q. _PyImport_RunModInitFunc(): set def->m_base.m_init
R-U. (same as for m_size == -1)
(6). subsequent times (found in _PyRuntime.imports.extensions):
A. _imp_create_dynamic_impl() -> import_find_extension()
B. import_find_extension() -> reload_singlephase_extension()
C. reload_singlephase_extension()
-> _PyImport_CheckSubinterpIncompatibleExtensionAllowed()
D. reload_singlephase_extension(): call def->m_base.m_init (see above)
E. reload_singlephase_extension(): add the module to sys.modules
F. reload_singlephase_extension(): add to modules_by_index
(10). every time:
A. noop
...for multi-phase init modules:
(6). every time:
A. _imp_create_dynamic_impl() -> import_find_extension() (not found)
B. _imp_create_dynamic_impl() -> _PyImport_GetModInitFunc()
C. _PyImport_GetModInitFunc(): load <module init func>
D. _imp_create_dynamic_impl() -> import_run_extension()
E. import_run_extension() -> _PyImport_RunModInitFunc()
F. _PyImport_RunModInitFunc(): call <module init func>
G. import_run_extension() -> PyModule_FromDefAndSpec()
H. PyModule_FromDefAndSpec(): gather/check moduledef slots
I. if there's a Py_mod_create slot:
1. PyModule_FromDefAndSpec(): call its function
J. else:
1. PyModule_FromDefAndSpec() -> PyModule_NewObject()
K: PyModule_FromDefAndSpec(): set mod->md_def
L. PyModule_FromDefAndSpec() -> _add_methods_to_object()
M. PyModule_FromDefAndSpec() -> PyModule_SetDocString()
(10). every time:
A. _imp_exec_dynamic_impl() -> exec_builtin_or_dynamic()
B. if mod->md_state == NULL (including if m_size == 0):
1. exec_builtin_or_dynamic() -> PyModule_ExecDef()
2. PyModule_ExecDef(): allocate mod->md_state
3. if there's a Py_mod_exec slot:
1. PyModule_ExecDef(): call its function
*/
/* Make sure name is fully qualified.
This is a bit of a hack: when the shared library is loaded,
the module name is "package.module", but the module calls
PyModule_Create*() with just "module" for the name. The shared
library loader squirrels away the true name of the module in
_PyRuntime.imports.pkgcontext, and PyModule_Create*() will
substitute this (if the name actually matches).
*/
#ifdef HAVE_THREAD_LOCAL
_Py_thread_local const char *pkgcontext = NULL;
# undef PKGCONTEXT
# define PKGCONTEXT pkgcontext
#endif
const char *
_PyImport_ResolveNameWithPackageContext(const char *name)
{
#ifndef HAVE_THREAD_LOCAL
PyMutex_Lock(&EXTENSIONS.mutex);
#endif
if (PKGCONTEXT != NULL) {
const char *p = strrchr(PKGCONTEXT, '.');
if (p != NULL && strcmp(name, p+1) == 0) {
name = PKGCONTEXT;
PKGCONTEXT = NULL;
}
}
#ifndef HAVE_THREAD_LOCAL
PyMutex_Unlock(&EXTENSIONS.mutex);
#endif
return name;
}
const char *
_PyImport_SwapPackageContext(const char *newcontext)
{
#ifndef HAVE_THREAD_LOCAL
PyMutex_Lock(&EXTENSIONS.mutex);
#endif
const char *oldcontext = PKGCONTEXT;
PKGCONTEXT = newcontext;
#ifndef HAVE_THREAD_LOCAL
PyMutex_Unlock(&EXTENSIONS.mutex);
#endif
return oldcontext;
}
#ifdef HAVE_DLOPEN
int
_PyImport_GetDLOpenFlags(PyInterpreterState *interp)
{
return DLOPENFLAGS(interp);
}
void
_PyImport_SetDLOpenFlags(PyInterpreterState *interp, int new_val)
{
DLOPENFLAGS(interp) = new_val;
}
#endif // HAVE_DLOPEN
/* Common implementation for _imp.exec_dynamic and _imp.exec_builtin */
static int
exec_builtin_or_dynamic(PyObject *mod) {
PyModuleDef *def;
void *state;
if (!PyModule_Check(mod)) {
return 0;
}
def = PyModule_GetDef(mod);
if (def == NULL) {
return 0;
}
state = PyModule_GetState(mod);
if (state) {
/* Already initialized; skip reload */
return 0;
}
return PyModule_ExecDef(mod, def);
}
static int clear_singlephase_extension(PyInterpreterState *interp,
PyObject *name, PyObject *filename);
// Currently, this is only used for testing.
// (See _testinternalcapi.clear_extension().)
// If adding another use, be careful about modules that import themselves
// recursively (see gh-123880).
int
_PyImport_ClearExtension(PyObject *name, PyObject *filename)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
/* Clearing a module's C globals is up to the module. */
if (clear_singlephase_extension(interp, name, filename) < 0) {
return -1;
}
// In the future we'll probably also make sure the extension's
// file handle (and DL handle) is closed (requires saving it).
return 0;
}
/*****************************/
/* single-phase init modules */
/*****************************/
/*
We support a number of kinds of single-phase init builtin/extension modules:
* "basic"
* no module state (PyModuleDef.m_size == -1)
* does not support repeated init (we use PyModuleDef.m_base.m_copy)
* may have process-global state
* the module's def is cached in _PyRuntime.imports.extensions,
by (name, filename)
* "reinit"
* no module state (PyModuleDef.m_size == 0)
* supports repeated init (m_copy is never used)
* should not have any process-global state
* its def is never cached in _PyRuntime.imports.extensions
(except, currently, under the main interpreter, for some reason)
* "with state" (almost the same as reinit)
* has module state (PyModuleDef.m_size > 0)
* supports repeated init (m_copy is never used)
* should not have any process-global state
* its def is never cached in _PyRuntime.imports.extensions
(except, currently, under the main interpreter, for some reason)
There are also variants within those classes:
* two or more modules share a PyModuleDef
* a module's init func uses another module's PyModuleDef
* a module's init func calls another's module's init func
* a module's init "func" is actually a variable statically initialized
to another module's init func
* two or modules share "methods"
* a module's init func copies another module's PyModuleDef
(with a different name)
* (basic-only) two or modules share process-global state
In the first case, where modules share a PyModuleDef, the following
notable weirdness happens:
* the module's __name__ matches the def, not the requested name
* the last module (with the same def) to be imported for the first time wins
* returned by PyState_Find_Module() (via interp->modules_by_index)
* (non-basic-only) its init func is used when re-loading any of them
(via the def's m_init)
* (basic-only) the copy of its __dict__ is used when re-loading any of them
(via the def's m_copy)
However, the following happens as expected:
* a new module object (with its own __dict__) is created for each request
* the module's __spec__ has the requested name
* the loaded module is cached in sys.modules under the requested name
* the m_index field of the shared def is not changed,
so at least PyState_FindModule() will always look in the same place
For "basic" modules there are other quirks:
* (whether sharing a def or not) when loaded the first time,
m_copy is set before _init_module_attrs() is called
in importlib._bootstrap.module_from_spec(),
so when the module is re-loaded, the previous value
for __wpec__ (and others) is reset, possibly unexpectedly.
Generally, when multiple interpreters are involved, some of the above
gets even messier.
*/
static inline void
extensions_lock_acquire(void)
{
PyMutex_Lock(&_PyRuntime.imports.extensions.mutex);
}
static inline void
extensions_lock_release(void)
{
PyMutex_Unlock(&_PyRuntime.imports.extensions.mutex);
}
/* Magic for extension modules (built-in as well as dynamically
loaded). To prevent initializing an extension module more than
once, we keep a static dictionary 'extensions' keyed by the tuple
(module name, module name) (for built-in modules) or by
(filename, module name) (for dynamically loaded modules), containing these
modules. A copy of the module's dictionary is stored by calling
fix_up_extension() immediately after the module initialization
function succeeds. A copy can be retrieved from there by calling
import_find_extension().
Modules which do support multiple initialization set their m_size
field to a non-negative number (indicating the size of the
module-specific state). They are still recorded in the extensions
dictionary, to avoid loading shared libraries twice.
*/
typedef struct cached_m_dict {
/* A shallow copy of the original module's __dict__. */
PyObject *copied;
/* The interpreter that owns the copy. */
int64_t interpid;
} *cached_m_dict_t;
struct extensions_cache_value {
PyModuleDef *def;
/* The function used to re-initialize the module.
This is only set for legacy (single-phase init) extension modules
and only used for those that support multiple initializations
(m_size >= 0).
It is set by update_global_state_for_extension(). */
PyModInitFunction m_init;
/* The module's index into its interpreter's modules_by_index cache.
This is set for all extension modules but only used for legacy ones.
(See PyInterpreterState.modules_by_index for more info.) */
Py_ssize_t m_index;
/* A copy of the module's __dict__ after the first time it was loaded.
This is only set/used for legacy modules that do not support
multiple initializations.
It is set exclusively by fixup_cached_def(). */
cached_m_dict_t m_dict;
struct cached_m_dict _m_dict;
_Py_ext_module_origin origin;
#ifdef Py_GIL_DISABLED
/* The module's md_gil slot, for legacy modules that are reinitialized from
m_dict rather than calling their initialization function again. */
void *md_gil;
#endif
};
static struct extensions_cache_value *
alloc_extensions_cache_value(void)
{
struct extensions_cache_value *value
= PyMem_RawMalloc(sizeof(struct extensions_cache_value));
if (value == NULL) {
PyErr_NoMemory();
return NULL;
}
*value = (struct extensions_cache_value){0};
return value;
}
static void
free_extensions_cache_value(struct extensions_cache_value *value)
{
PyMem_RawFree(value);
}
static Py_ssize_t
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