cpython/Python/import.c at 61c7249759ce88465ea655d5c19d17d03ff3f74b · python/cpython · GitHub

History

3890 lines (3341 loc) · 108 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

714

715

716

717

718

719

720

721

722

723

724

725

726

727

728

729

730

731

732

733

734

735

736

737

738

739

740

741

742

743

744

745

746

747

748

749

750

751

752

753

754

755

756

757

758

759

760

761

762

763

764

765

766

767

768

769

770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

813

814

815

816

817

818

819

820

821

822

823

824

825

826

827

828

829

830

831

832

833

834

835

836

837

838

839

840

841

842

843

844

845

846

847

848

849

850

851

852

853

854

855

856

857

858

859

860

861

862

863

864

865

866

867

868

869

870

871

872

873

874

875

876

877

878

879

880

881

882

883

884

885

886

887

888

889

890

891

892

893

894

895

896

897

898

899

900

901

902

903

904

905

906

907

908

909

910

911

912

913

914

915

916

917

918

919

920

921

922

923

924

925

926

927

928

929

930

931

932

933

934

935

936

937

938

939

940

941

942

943

944

945

946

947

948

949

950

951

952

953

954

955

956

957

958

959

960

961

962

963

964

965

966

967

968

969

970

971

972

973

974

975

976

977

978

979

980

981

982

983

984

985

986

987

988

989

990

991

992

993

994

995

996

997

998

999

1000

/* Module definition and import implementation */

#include "Python.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_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_Audit()

#include "pycore_weakref.h" // _PyWeakref_GET_REF()

#include "marshal.h" // PyMarshal_ReadObjectFromString()

#include "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

#ifdef __cplusplus

extern "C" {

#endif

/*[clinic input]

module _imp

[clinic start generated code]*/

/*[clinic end generated code: output=da39a3ee5e6b4b0d input=9c332475d8686284]*/

#include "clinic/import.c.h"

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

/* 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.mutex

#define IMPORT_LOCK_THREAD(interp) \

(interp)->imports.lock.thread

#define IMPORT_LOCK_LEVEL(interp) \

(interp)->imports.lock.level

#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)

{

unsigned long me = PyThread_get_thread_ident();

if (me == PYTHREAD_INVALID_THREAD_ID)

return; /* Too bad */

if (IMPORT_LOCK(interp) == NULL) {

IMPORT_LOCK(interp) = PyThread_allocate_lock();

if (IMPORT_LOCK(interp) == NULL)

return; /* Nothing much we can do. */

}

if (IMPORT_LOCK_THREAD(interp) == me) {

IMPORT_LOCK_LEVEL(interp)++;

return;

}

if (IMPORT_LOCK_THREAD(interp) != PYTHREAD_INVALID_THREAD_ID ||

!PyThread_acquire_lock(IMPORT_LOCK(interp), 0))

{

PyThreadState *tstate = PyEval_SaveThread();

PyThread_acquire_lock(IMPORT_LOCK(interp), WAIT_LOCK);

PyEval_RestoreThread(tstate);

}

assert(IMPORT_LOCK_LEVEL(interp) == 0);

IMPORT_LOCK_THREAD(interp) = me;

IMPORT_LOCK_LEVEL(interp) = 1;

}

int

_PyImport_ReleaseLock(PyInterpreterState *interp)

{

unsigned long me = PyThread_get_thread_ident();

if (me == PYTHREAD_INVALID_THREAD_ID || IMPORT_LOCK(interp) == NULL)

return 0; /* Too bad */

if (IMPORT_LOCK_THREAD(interp) != me)

return -1;

IMPORT_LOCK_LEVEL(interp)--;

assert(IMPORT_LOCK_LEVEL(interp) >= 0);

if (IMPORT_LOCK_LEVEL(interp) == 0) {

IMPORT_LOCK_THREAD(interp) = PYTHREAD_INVALID_THREAD_ID;

PyThread_release_lock(IMPORT_LOCK(interp));

}

return 1;

}

#ifdef HAVE_FORK

/* This function is called from PyOS_AfterFork_Child() to ensure that newly

created child processes do not share locks with the parent.

We now acquire the import lock around fork() calls but on some platforms

(Solaris 9 and earlier? see isue7242) that still left us with problems. */

PyStatus

_PyImport_ReInitLock(PyInterpreterState *interp)

{

if (IMPORT_LOCK(interp) != NULL) {

if (_PyThread_at_fork_reinit(&IMPORT_LOCK(interp)) < 0) {

return _PyStatus_ERR("failed to create a new lock");

}

if (IMPORT_LOCK_LEVEL(interp) > 1) {

/* Forked as a side effect of import */

unsigned long me = PyThread_get_thread_ident();

PyThread_acquire_lock(IMPORT_LOCK(interp), WAIT_LOCK);

IMPORT_LOCK_THREAD(interp) = me;

IMPORT_LOCK_LEVEL(interp)--;

} else {

IMPORT_LOCK_THREAD(interp) = PYTHREAD_INVALID_THREAD_ID;

IMPORT_LOCK_LEVEL(interp) = 0;

}

return _PyStatus_OK();

}

#endif

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

/* 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);

}

PyObject *

PyImport_GetModuleDict(void)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

if (MODULES(interp) == NULL) {

Py_FatalError("interpreter has no modules dictionary");

}

return MODULES(interp);

}

int

_PyImport_SetModule(PyObject *name, PyObject *m)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

PyObject *modules = MODULES(interp);

return PyObject_SetItem(modules, name, m);

}

int

_PyImport_SetModuleString(const char *name, PyObject *m)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

PyObject *modules = MODULES(interp);

return PyMapping_SetItemString(modules, name, m);

}

static PyObject *

import_get_module(PyThreadState *tstate, PyObject *name)

{

PyObject *modules = MODULES(tstate->interp);

if (modules == NULL) {

_PyErr_SetString(tstate, PyExc_RuntimeError,

"unable to get sys.modules");

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.

spec = PyObject_GetAttr(mod, &_Py_ID(__spec__));

int busy = _PyModuleSpec_IsInitializing(spec);

Py_XDECREF(spec);

if (busy) {

/* 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 = MODULES(tstate->interp);

if (modules == NULL) {

_PyErr_SetString(tstate, PyExc_RuntimeError,

"no import module dictionary");

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 = MODULES(tstate->interp);

if (PyDict_CheckExact(modules)) {

PyObject *mod = _PyDict_Pop(modules, name, Py_None);

Py_XDECREF(mod);

}

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)

{

PyThread_acquire_lock(EXTENSIONS.mutex, WAIT_LOCK);

LAST_MODULE_INDEX++;

Py_ssize_t index = LAST_MODULE_INDEX;

PyThread_release_lock(EXTENSIONS.mutex);

return 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, PyModuleDef *def)

{

Py_ssize_t index = def->m_base.m_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,

PyModuleDef *def, PyObject *module)

{

assert(def != NULL);

assert(def->m_slots == NULL);

assert(def->m_base.m_index > 0);

if (MODULES_BY_INDEX(interp) == NULL) {

MODULES_BY_INDEX(interp) = PyList_New(0);

if (MODULES_BY_INDEX(interp) == NULL) {

return -1;

}

Py_ssize_t index = def->m_base.m_index;

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, PyModuleDef *def)

{

Py_ssize_t index = def->m_base.m_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;

}

return _modules_by_index_get(interp, module);

}

/* _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;

}

return _modules_by_index_set(tstate->interp, def, 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 = def->m_base.m_index;

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;

}

return _modules_by_index_set(interp, def, 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;

}

return _modules_by_index_clear_one(tstate->interp, def);

}

// 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) {

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_WriteUnraisable(MODULES_BY_INDEX(interp));

}

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

/* 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):

1. _imp_create_dynamic_impl() -> import_find_extension()

2. _imp_create_dynamic_impl() -> _PyImport_LoadDynamicModuleWithSpec()

3. _PyImport_LoadDynamicModuleWithSpec(): load <module init func>

4. _PyImport_LoadDynamicModuleWithSpec(): call <module init func>

5. <module init func> -> PyModule_Create() -> PyModule_Create2() -> PyModule_CreateInitialized()

6. PyModule_CreateInitialized() -> PyModule_New()

7. PyModule_CreateInitialized(): allocate mod->md_state

8. PyModule_CreateInitialized() -> PyModule_AddFunctions()

9. PyModule_CreateInitialized() -> PyModule_SetDocString()

10. PyModule_CreateInitialized(): set mod->md_def

11. <module init func>: initialize the module

12. _PyImport_LoadDynamicModuleWithSpec() -> _PyImport_CheckSubinterpIncompatibleExtensionAllowed()

13. _PyImport_LoadDynamicModuleWithSpec(): set def->m_base.m_init

14. _PyImport_LoadDynamicModuleWithSpec(): set __file__

15. _PyImport_LoadDynamicModuleWithSpec() -> _PyImport_FixupExtensionObject()

16. _PyImport_FixupExtensionObject(): add it to interp->imports.modules_by_index

17. _PyImport_FixupExtensionObject(): copy __dict__ into def->m_base.m_copy

18. _PyImport_FixupExtensionObject(): add it to _PyRuntime.imports.extensions

(6). subsequent times (found in _PyRuntime.imports.extensions):

1. _imp_create_dynamic_impl() -> import_find_extension()

2. import_find_extension() -> import_add_module()

3. if name in sys.modules: use that module

4. else:

1. import_add_module() -> PyModule_NewObject()

2. import_add_module(): set it on sys.modules

5. import_find_extension(): copy the "m_copy" dict into __dict__

6. _imp_create_dynamic_impl() -> _PyImport_CheckSubinterpIncompatibleExtensionAllowed()

(10). (every time):

1. 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):

1-16. (same as for m_size == -1)

(6). main interpreter - first time (not found in _PyRuntime.imports.extensions):

1-16. (same as for m_size == -1)

17. _PyImport_FixupExtensionObject(): add it to _PyRuntime.imports.extensions

(6). previously loaded in main interpreter (found in _PyRuntime.imports.extensions):

1. _imp_create_dynamic_impl() -> import_find_extension()

2. import_find_extension(): call def->m_base.m_init

3. import_find_extension(): add the module to sys.modules

(10). every time:

1. noop

...for multi-phase init modules:

(6). every time:

1. _imp_create_dynamic_impl() -> import_find_extension() (not found)

2. _imp_create_dynamic_impl() -> _PyImport_LoadDynamicModuleWithSpec()

3. _PyImport_LoadDynamicModuleWithSpec(): load module init func

4. _PyImport_LoadDynamicModuleWithSpec(): call module init func

5. _PyImport_LoadDynamicModuleWithSpec() -> PyModule_FromDefAndSpec()

6. PyModule_FromDefAndSpec(): gather/check moduledef slots

7. if there's a Py_mod_create slot:

1. PyModule_FromDefAndSpec(): call its function

8. else:

1. PyModule_FromDefAndSpec() -> PyModule_NewObject()

9: PyModule_FromDefAndSpec(): set mod->md_def

10. PyModule_FromDefAndSpec() -> _add_methods_to_object()

11. PyModule_FromDefAndSpec() -> PyModule_SetDocString()

(10). every time:

1. _imp_exec_dynamic_impl() -> exec_builtin_or_dynamic()

2. 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

PyThread_acquire_lock(EXTENSIONS.mutex, WAIT_LOCK);

#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

PyThread_release_lock(EXTENSIONS.mutex);

#endif

return name;

}

const char *

_PyImport_SwapPackageContext(const char *newcontext)

{

#ifndef HAVE_THREAD_LOCAL

PyThread_acquire_lock(EXTENSIONS.mutex, WAIT_LOCK);

#endif

const char *oldcontext = PKGCONTEXT;

PKGCONTEXT = newcontext;

#ifndef HAVE_THREAD_LOCAL

PyThread_release_lock(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().)

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)

{

PyThread_acquire_lock(_PyRuntime.imports.extensions.mutex, WAIT_LOCK);

}

static inline void

extensions_lock_release(void)

{

PyThread_release_lock(_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

_PyImport_FixupExtensionObject() 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.

static void *

hashtable_key_from_2_strings(PyObject *str1, PyObject *str2, const char sep)

{

Py_ssize_t str1_len, str2_len;

const char *str1_data = PyUnicode_AsUTF8AndSize(str1, &str1_len);

const char *str2_data = PyUnicode_AsUTF8AndSize(str2, &str2_len);

if (str1_data == NULL || str2_data == NULL) {

return NULL;

}

/* Make sure sep and the NULL byte won't cause an overflow. */

assert(SIZE_MAX - str1_len - str2_len > 2);

size_t size = str1_len + 1 + str2_len + 1;

char *key = PyMem_RawMalloc(size);

if (key == NULL) {

PyErr_NoMemory();

return NULL;

}

strncpy(key, str1_data, str1_len);

key[str1_len] = sep;

strncpy(key + str1_len + 1, str2_data, str2_len + 1);

assert(strlen(key) == size - 1);

return key;

}

static Py_uhash_t

hashtable_hash_str(const void *key)

{

return _Py_HashBytes(key, strlen((const char *)key));

}

static int

hashtable_compare_str(const void *key1, const void *key2)

{

return strcmp((const char *)key1, (const char *)key2) == 0;

}

static void

hashtable_destroy_str(void *ptr)

{

PyMem_RawFree(ptr);

}

#define HTSEP ':'

static PyModuleDef *

_extensions_cache_get(PyObject *filename, PyObject *name)

{

PyModuleDef *def = NULL;

void *key = NULL;

extensions_lock_acquire();

if (EXTENSIONS.hashtable == NULL) {

goto finally;

}

key = hashtable_key_from_2_strings(filename, name, HTSEP);

if (key == NULL) {

goto finally;

}

_Py_hashtable_entry_t *entry = _Py_hashtable_get_entry(

EXTENSIONS.hashtable, key);

if (entry == NULL) {

goto finally;

}

def = (PyModuleDef *)entry->value;

finally:

extensions_lock_release();

if (key != NULL) {

PyMem_RawFree(key);

}

return def;

}

static int

_extensions_cache_set(PyObject *filename, PyObject *name, PyModuleDef *def)

{

int res = -1;

extensions_lock_acquire();

if (EXTENSIONS.hashtable == NULL) {

_Py_hashtable_allocator_t alloc = {PyMem_RawMalloc, PyMem_RawFree};

EXTENSIONS.hashtable = _Py_hashtable_new_full(

hashtable_hash_str,

hashtable_compare_str,

hashtable_destroy_str, // key

/* There's no need to decref the def since it's immortal. */

NULL, // value

&alloc

View remainder of file in raw view

cpython/Python/import.c at 61c7249759ce88465ea655d5c19d17d03ff3f74b · python/cpython · GitHub

Uh oh!

Expand file tree

Breadcrumbs

import.c

Latest commit

History

Breadcrumbs

import.c

File metadata and controls