aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/tools/python3/src/Modules/_bz2module.c
blob: 798e9efc628f0567e913223232319efad6b5f7f5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
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
/* _bz2 - Low-level Python interface to libbzip2. */

#define PY_SSIZE_T_CLEAN

#include "Python.h"
#include "structmember.h"         // PyMemberDef

#include <bzlib.h>
#include <stdio.h>

// Blocks output buffer wrappers
#include "pycore_blocks_output_buffer.h"

#if OUTPUT_BUFFER_MAX_BLOCK_SIZE > UINT32_MAX
    #error "The maximum block size accepted by libbzip2 is UINT32_MAX."
#endif

/* On success, return value >= 0
   On failure, return -1 */
static inline Py_ssize_t
OutputBuffer_InitAndGrow(_BlocksOutputBuffer *buffer, Py_ssize_t max_length,
                         char **next_out, uint32_t *avail_out)
{
    Py_ssize_t allocated;

    allocated = _BlocksOutputBuffer_InitAndGrow(
                    buffer, max_length, (void**) next_out);
    *avail_out = (uint32_t) allocated;
    return allocated;
}

/* On success, return value >= 0
   On failure, return -1 */
static inline Py_ssize_t
OutputBuffer_Grow(_BlocksOutputBuffer *buffer,
                  char **next_out, uint32_t *avail_out)
{
    Py_ssize_t allocated;

    allocated = _BlocksOutputBuffer_Grow(
                    buffer, (void**) next_out, (Py_ssize_t) *avail_out);
    *avail_out = (uint32_t) allocated;
    return allocated;
}

static inline Py_ssize_t
OutputBuffer_GetDataSize(_BlocksOutputBuffer *buffer, uint32_t avail_out)
{
    return _BlocksOutputBuffer_GetDataSize(buffer, (Py_ssize_t) avail_out);
}

static inline PyObject *
OutputBuffer_Finish(_BlocksOutputBuffer *buffer, uint32_t avail_out)
{
    return _BlocksOutputBuffer_Finish(buffer, (Py_ssize_t) avail_out);
}

static inline void
OutputBuffer_OnError(_BlocksOutputBuffer *buffer)
{
    _BlocksOutputBuffer_OnError(buffer);
}


#ifndef BZ_CONFIG_ERROR
#define BZ2_bzCompress bzCompress
#define BZ2_bzCompressInit bzCompressInit
#define BZ2_bzCompressEnd bzCompressEnd
#define BZ2_bzDecompress bzDecompress
#define BZ2_bzDecompressInit bzDecompressInit
#define BZ2_bzDecompressEnd bzDecompressEnd
#endif  /* ! BZ_CONFIG_ERROR */


#define ACQUIRE_LOCK(obj) do { \
    if (!PyThread_acquire_lock((obj)->lock, 0)) { \
        Py_BEGIN_ALLOW_THREADS \
        PyThread_acquire_lock((obj)->lock, 1); \
        Py_END_ALLOW_THREADS \
    } } while (0)
#define RELEASE_LOCK(obj) PyThread_release_lock((obj)->lock)


typedef struct {
    PyTypeObject *bz2_compressor_type;
    PyTypeObject *bz2_decompressor_type;
} _bz2_state;

static inline _bz2_state*
get_bz2_state(PyObject *module)
{
    void *state = PyModule_GetState(module);
    assert(state != NULL);
    return (_bz2_state *)state;
}

typedef struct {
    PyObject_HEAD
    bz_stream bzs;
    int flushed;
    PyThread_type_lock lock;
} BZ2Compressor;

typedef struct {
    PyObject_HEAD
    bz_stream bzs;
    char eof;           /* T_BOOL expects a char */
    PyObject *unused_data;
    char needs_input;
    char *input_buffer;
    size_t input_buffer_size;

    /* bzs->avail_in is only 32 bit, so we store the true length
       separately. Conversion and looping is encapsulated in
       decompress_buf() */
    size_t bzs_avail_in_real;
    PyThread_type_lock lock;
} BZ2Decompressor;

/* Helper functions. */

static int
catch_bz2_error(int bzerror)
{
    switch(bzerror) {
        case BZ_OK:
        case BZ_RUN_OK:
        case BZ_FLUSH_OK:
        case BZ_FINISH_OK:
        case BZ_STREAM_END:
            return 0;

#ifdef BZ_CONFIG_ERROR
        case BZ_CONFIG_ERROR:
            PyErr_SetString(PyExc_SystemError,
                            "libbzip2 was not compiled correctly");
            return 1;
#endif
        case BZ_PARAM_ERROR:
            PyErr_SetString(PyExc_ValueError,
                            "Internal error - "
                            "invalid parameters passed to libbzip2");
            return 1;
        case BZ_MEM_ERROR:
            PyErr_NoMemory();
            return 1;
        case BZ_DATA_ERROR:
        case BZ_DATA_ERROR_MAGIC:
            PyErr_SetString(PyExc_OSError, "Invalid data stream");
            return 1;
        case BZ_IO_ERROR:
            PyErr_SetString(PyExc_OSError, "Unknown I/O error");
            return 1;
        case BZ_UNEXPECTED_EOF:
            PyErr_SetString(PyExc_EOFError,
                            "Compressed file ended before the logical "
                            "end-of-stream was detected");
            return 1;
        case BZ_SEQUENCE_ERROR:
            PyErr_SetString(PyExc_RuntimeError,
                            "Internal error - "
                            "Invalid sequence of commands sent to libbzip2");
            return 1;
        default:
            PyErr_Format(PyExc_OSError,
                         "Unrecognized error from libbzip2: %d", bzerror);
            return 1;
    }
}


/* BZ2Compressor class. */

static PyObject *
compress(BZ2Compressor *c, char *data, size_t len, int action)
{
    PyObject *result;
    _BlocksOutputBuffer buffer = {.list = NULL};

    if (OutputBuffer_InitAndGrow(&buffer, -1, &c->bzs.next_out, &c->bzs.avail_out) < 0) {
        goto error;
    }
    c->bzs.next_in = data;
    c->bzs.avail_in = 0;

    for (;;) {
        int bzerror;

        /* On a 64-bit system, len might not fit in avail_in (an unsigned int).
           Do compression in chunks of no more than UINT_MAX bytes each. */
        if (c->bzs.avail_in == 0 && len > 0) {
            c->bzs.avail_in = (unsigned int)Py_MIN(len, UINT_MAX);
            len -= c->bzs.avail_in;
        }

        /* In regular compression mode, stop when input data is exhausted. */
        if (action == BZ_RUN && c->bzs.avail_in == 0)
            break;

        if (c->bzs.avail_out == 0) {
            if (OutputBuffer_Grow(&buffer, &c->bzs.next_out, &c->bzs.avail_out) < 0) {
                goto error;
            }
        }

        Py_BEGIN_ALLOW_THREADS
        bzerror = BZ2_bzCompress(&c->bzs, action);
        Py_END_ALLOW_THREADS

        if (catch_bz2_error(bzerror))
            goto error;

        /* In flushing mode, stop when all buffered data has been flushed. */
        if (action == BZ_FINISH && bzerror == BZ_STREAM_END)
            break;
    }

    result = OutputBuffer_Finish(&buffer, c->bzs.avail_out);
    if (result != NULL) {
        return result;
    }

error:
    OutputBuffer_OnError(&buffer);
    return NULL;
}

/*[clinic input]
module _bz2
class _bz2.BZ2Compressor "BZ2Compressor *" "&BZ2Compressor_Type"
class _bz2.BZ2Decompressor "BZ2Decompressor *" "&BZ2Decompressor_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=dc7d7992a79f9cb7]*/

#include "clinic/_bz2module.c.h"

/*[clinic input]
_bz2.BZ2Compressor.compress

    data: Py_buffer
    /

Provide data to the compressor object.

Returns a chunk of compressed data if possible, or b'' otherwise.

When you have finished providing data to the compressor, call the
flush() method to finish the compression process.
[clinic start generated code]*/

static PyObject *
_bz2_BZ2Compressor_compress_impl(BZ2Compressor *self, Py_buffer *data)
/*[clinic end generated code: output=59365426e941fbcc input=85c963218070fc4c]*/
{
    PyObject *result = NULL;

    ACQUIRE_LOCK(self);
    if (self->flushed)
        PyErr_SetString(PyExc_ValueError, "Compressor has been flushed");
    else
        result = compress(self, data->buf, data->len, BZ_RUN);
    RELEASE_LOCK(self);
    return result;
}

/*[clinic input]
_bz2.BZ2Compressor.flush

Finish the compression process.

Returns the compressed data left in internal buffers.

The compressor object may not be used after this method is called.
[clinic start generated code]*/

static PyObject *
_bz2_BZ2Compressor_flush_impl(BZ2Compressor *self)
/*[clinic end generated code: output=3ef03fc1b092a701 input=d64405d3c6f76691]*/
{
    PyObject *result = NULL;

    ACQUIRE_LOCK(self);
    if (self->flushed)
        PyErr_SetString(PyExc_ValueError, "Repeated call to flush()");
    else {
        self->flushed = 1;
        result = compress(self, NULL, 0, BZ_FINISH);
    }
    RELEASE_LOCK(self);
    return result;
}

static void*
BZ2_Malloc(void* ctx, int items, int size)
{
    if (items < 0 || size < 0)
        return NULL;
    if (size != 0 && (size_t)items > (size_t)PY_SSIZE_T_MAX / (size_t)size)
        return NULL;
    /* PyMem_Malloc() cannot be used: compress() and decompress()
       release the GIL */
    return PyMem_RawMalloc((size_t)items * (size_t)size);
}

static void
BZ2_Free(void* ctx, void *ptr)
{
    PyMem_RawFree(ptr);
}


/* Argument Clinic is not used since the Argument Clinic always want to
   check the type which would be wrong here */
static int
_bz2_BZ2Compressor___init___impl(BZ2Compressor *self, int compresslevel)
{
    int bzerror;

    if (!(1 <= compresslevel && compresslevel <= 9)) {
        PyErr_SetString(PyExc_ValueError,
                        "compresslevel must be between 1 and 9");
        return -1;
    }

    self->lock = PyThread_allocate_lock();
    if (self->lock == NULL) {
        PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
        return -1;
    }

    self->bzs.opaque = NULL;
    self->bzs.bzalloc = BZ2_Malloc;
    self->bzs.bzfree = BZ2_Free;
    bzerror = BZ2_bzCompressInit(&self->bzs, compresslevel, 0, 0);
    if (catch_bz2_error(bzerror))
        goto error;

    return 0;

error:
    PyThread_free_lock(self->lock);
    self->lock = NULL;
    return -1;
}

PyDoc_STRVAR(_bz2_BZ2Compressor___init____doc__,
"BZ2Compressor(compresslevel=9, /)\n"
"--\n"
"\n"
"Create a compressor object for compressing data incrementally.\n"
"\n"
"  compresslevel\n"
"    Compression level, as a number between 1 and 9.\n"
"\n"
"For one-shot compression, use the compress() function instead.");

static int
_bz2_BZ2Compressor___init__(PyObject *self, PyObject *args, PyObject *kwargs)
{
    int return_value = -1;
    int compresslevel = 9;

    if (!_PyArg_NoKeywords("BZ2Compressor", kwargs)) {
        goto exit;
    }
    if (!_PyArg_CheckPositional("BZ2Compressor", PyTuple_GET_SIZE(args), 0, 1)) {
        goto exit;
    }
    if (PyTuple_GET_SIZE(args) < 1) {
        goto skip_optional;
    }
    compresslevel = _PyLong_AsInt(PyTuple_GET_ITEM(args, 0));
    if (compresslevel == -1 && PyErr_Occurred()) {
        goto exit;
    }
skip_optional:
    return_value = _bz2_BZ2Compressor___init___impl((BZ2Compressor *)self, compresslevel);

exit:
    return return_value;
}

static void
BZ2Compressor_dealloc(BZ2Compressor *self)
{
    BZ2_bzCompressEnd(&self->bzs);
    if (self->lock != NULL) {
        PyThread_free_lock(self->lock);
    }
    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free((PyObject *)self);
    Py_DECREF(tp);
}

static int
BZ2Compressor_traverse(BZ2Compressor *self, visitproc visit, void *arg)
{
    Py_VISIT(Py_TYPE(self));
    return 0;
}

static PyMethodDef BZ2Compressor_methods[] = {
    _BZ2_BZ2COMPRESSOR_COMPRESS_METHODDEF
    _BZ2_BZ2COMPRESSOR_FLUSH_METHODDEF
    {NULL}
};

static PyType_Slot bz2_compressor_type_slots[] = {
    {Py_tp_dealloc, BZ2Compressor_dealloc},
    {Py_tp_methods, BZ2Compressor_methods},
    {Py_tp_init, _bz2_BZ2Compressor___init__},
    {Py_tp_new, PyType_GenericNew},
    {Py_tp_doc, (char *)_bz2_BZ2Compressor___init____doc__},
    {Py_tp_traverse, BZ2Compressor_traverse},
    {0, 0}
};

static PyType_Spec bz2_compressor_type_spec = {
    .name = "_bz2.BZ2Compressor",
    .basicsize = sizeof(BZ2Compressor),
    // Calling PyType_GetModuleState() on a subclass is not safe.
    // bz2_compressor_type_spec does not have Py_TPFLAGS_BASETYPE flag
    // which prevents to create a subclass.
    // So calling PyType_GetModuleState() in this file is always safe.
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE),
    .slots = bz2_compressor_type_slots,
};

/* BZ2Decompressor class. */

/* Decompress data of length d->bzs_avail_in_real in d->bzs.next_in.  The output
   buffer is allocated dynamically and returned.  At most max_length bytes are
   returned, so some of the input may not be consumed. d->bzs.next_in and
   d->bzs_avail_in_real are updated to reflect the consumed input. */
static PyObject*
decompress_buf(BZ2Decompressor *d, Py_ssize_t max_length)
{
    /* data_size is strictly positive, but because we repeatedly have to
       compare against max_length and PyBytes_GET_SIZE we declare it as
       signed */
    PyObject *result;
    _BlocksOutputBuffer buffer = {.list = NULL};
    bz_stream *bzs = &d->bzs;

    if (OutputBuffer_InitAndGrow(&buffer, max_length, &bzs->next_out, &bzs->avail_out) < 0) {
        goto error;
    }

    for (;;) {
        int bzret;
        /* On a 64-bit system, buffer length might not fit in avail_out, so we
           do decompression in chunks of no more than UINT_MAX bytes
           each. Note that the expression for `avail` is guaranteed to be
           positive, so the cast is safe. */
        bzs->avail_in = (unsigned int)Py_MIN(d->bzs_avail_in_real, UINT_MAX);
        d->bzs_avail_in_real -= bzs->avail_in;

        Py_BEGIN_ALLOW_THREADS
        bzret = BZ2_bzDecompress(bzs);
        Py_END_ALLOW_THREADS

        d->bzs_avail_in_real += bzs->avail_in;

        if (catch_bz2_error(bzret))
            goto error;
        if (bzret == BZ_STREAM_END) {
            d->eof = 1;
            break;
        } else if (d->bzs_avail_in_real == 0) {
            break;
        } else if (bzs->avail_out == 0) {
            if (OutputBuffer_GetDataSize(&buffer, bzs->avail_out) == max_length) {
                break;
            }
            if (OutputBuffer_Grow(&buffer, &bzs->next_out, &bzs->avail_out) < 0) {
                goto error;
            }
        }
    }

    result = OutputBuffer_Finish(&buffer, bzs->avail_out);
    if (result != NULL) {
        return result;
    }

error:
    OutputBuffer_OnError(&buffer);
    return NULL;
}


static PyObject *
decompress(BZ2Decompressor *d, char *data, size_t len, Py_ssize_t max_length)
{
    char input_buffer_in_use;
    PyObject *result;
    bz_stream *bzs = &d->bzs;

    /* Prepend unconsumed input if necessary */
    if (bzs->next_in != NULL) {
        size_t avail_now, avail_total;

        /* Number of bytes we can append to input buffer */
        avail_now = (d->input_buffer + d->input_buffer_size)
            - (bzs->next_in + d->bzs_avail_in_real);

        /* Number of bytes we can append if we move existing
           contents to beginning of buffer (overwriting
           consumed input) */
        avail_total = d->input_buffer_size - d->bzs_avail_in_real;

        if (avail_total < len) {
            size_t offset = bzs->next_in - d->input_buffer;
            char *tmp;
            size_t new_size = d->input_buffer_size + len - avail_now;

            /* Assign to temporary variable first, so we don't
               lose address of allocated buffer if realloc fails */
            tmp = PyMem_Realloc(d->input_buffer, new_size);
            if (tmp == NULL) {
                PyErr_SetNone(PyExc_MemoryError);
                return NULL;
            }
            d->input_buffer = tmp;
            d->input_buffer_size = new_size;

            bzs->next_in = d->input_buffer + offset;
        }
        else if (avail_now < len) {
            memmove(d->input_buffer, bzs->next_in,
                    d->bzs_avail_in_real);
            bzs->next_in = d->input_buffer;
        }
        memcpy((void*)(bzs->next_in + d->bzs_avail_in_real), data, len);
        d->bzs_avail_in_real += len;
        input_buffer_in_use = 1;
    }
    else {
        bzs->next_in = data;
        d->bzs_avail_in_real = len;
        input_buffer_in_use = 0;
    }

    result = decompress_buf(d, max_length);
    if(result == NULL) {
        bzs->next_in = NULL;
        return NULL;
    }

    if (d->eof) {
        d->needs_input = 0;
        if (d->bzs_avail_in_real > 0) {
            Py_XSETREF(d->unused_data,
                      PyBytes_FromStringAndSize(bzs->next_in, d->bzs_avail_in_real));
            if (d->unused_data == NULL)
                goto error;
        }
    }
    else if (d->bzs_avail_in_real == 0) {
        bzs->next_in = NULL;
        d->needs_input = 1;
    }
    else {
        d->needs_input = 0;

        /* If we did not use the input buffer, we now have
           to copy the tail from the caller's buffer into the
           input buffer */
        if (!input_buffer_in_use) {

            /* Discard buffer if it's too small
               (resizing it may needlessly copy the current contents) */
            if (d->input_buffer != NULL &&
                d->input_buffer_size < d->bzs_avail_in_real) {
                PyMem_Free(d->input_buffer);
                d->input_buffer = NULL;
            }

            /* Allocate if necessary */
            if (d->input_buffer == NULL) {
                d->input_buffer = PyMem_Malloc(d->bzs_avail_in_real);
                if (d->input_buffer == NULL) {
                    PyErr_SetNone(PyExc_MemoryError);
                    goto error;
                }
                d->input_buffer_size = d->bzs_avail_in_real;
            }

            /* Copy tail */
            memcpy(d->input_buffer, bzs->next_in, d->bzs_avail_in_real);
            bzs->next_in = d->input_buffer;
        }
    }

    return result;

error:
    Py_XDECREF(result);
    return NULL;
}

/*[clinic input]
_bz2.BZ2Decompressor.decompress

    data: Py_buffer
    max_length: Py_ssize_t=-1

Decompress *data*, returning uncompressed data as bytes.

If *max_length* is nonnegative, returns at most *max_length* bytes of
decompressed data. If this limit is reached and further output can be
produced, *self.needs_input* will be set to ``False``. In this case, the next
call to *decompress()* may provide *data* as b'' to obtain more of the output.

If all of the input data was decompressed and returned (either because this
was less than *max_length* bytes, or because *max_length* was negative),
*self.needs_input* will be set to True.

Attempting to decompress data after the end of stream is reached raises an
EOFError.  Any data found after the end of the stream is ignored and saved in
the unused_data attribute.
[clinic start generated code]*/

static PyObject *
_bz2_BZ2Decompressor_decompress_impl(BZ2Decompressor *self, Py_buffer *data,
                                     Py_ssize_t max_length)
/*[clinic end generated code: output=23e41045deb240a3 input=52e1ffc66a8ea624]*/
{
    PyObject *result = NULL;

    ACQUIRE_LOCK(self);
    if (self->eof)
        PyErr_SetString(PyExc_EOFError, "End of stream already reached");
    else
        result = decompress(self, data->buf, data->len, max_length);
    RELEASE_LOCK(self);
    return result;
}

/* Argument Clinic is not used since the Argument Clinic always want to
   check the type which would be wrong here */
static int
_bz2_BZ2Decompressor___init___impl(BZ2Decompressor *self)
{
    int bzerror;

    PyThread_type_lock lock = PyThread_allocate_lock();
    if (lock == NULL) {
        PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
        return -1;
    }
    if (self->lock != NULL) {
        PyThread_free_lock(self->lock);
    }
    self->lock = lock;

    self->needs_input = 1;
    self->bzs_avail_in_real = 0;
    self->input_buffer = NULL;
    self->input_buffer_size = 0;
    Py_XSETREF(self->unused_data, PyBytes_FromStringAndSize(NULL, 0));
    if (self->unused_data == NULL)
        goto error;

    bzerror = BZ2_bzDecompressInit(&self->bzs, 0, 0);
    if (catch_bz2_error(bzerror))
        goto error;

    return 0;

error:
    Py_CLEAR(self->unused_data);
    PyThread_free_lock(self->lock);
    self->lock = NULL;
    return -1;
}

static int
_bz2_BZ2Decompressor___init__(PyObject *self, PyObject *args, PyObject *kwargs)
{
    int return_value = -1;

    if (!_PyArg_NoPositional("BZ2Decompressor", args)) {
        goto exit;
    }
    if (!_PyArg_NoKeywords("BZ2Decompressor", kwargs)) {
        goto exit;
    }
    return_value = _bz2_BZ2Decompressor___init___impl((BZ2Decompressor *)self);

exit:
    return return_value;
}

PyDoc_STRVAR(_bz2_BZ2Decompressor___init____doc__,
"BZ2Decompressor()\n"
"--\n"
"\n"
"Create a decompressor object for decompressing data incrementally.\n"
"\n"
"For one-shot decompression, use the decompress() function instead.");

static void
BZ2Decompressor_dealloc(BZ2Decompressor *self)
{
    if(self->input_buffer != NULL) {
        PyMem_Free(self->input_buffer);
    }
    BZ2_bzDecompressEnd(&self->bzs);
    Py_CLEAR(self->unused_data);
    if (self->lock != NULL) {
        PyThread_free_lock(self->lock);
    }

    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free((PyObject *)self);
    Py_DECREF(tp);
}

static int
BZ2Decompressor_traverse(BZ2Decompressor *self, visitproc visit, void *arg)
{
    Py_VISIT(Py_TYPE(self));
    return 0;
}

static PyMethodDef BZ2Decompressor_methods[] = {
    _BZ2_BZ2DECOMPRESSOR_DECOMPRESS_METHODDEF
    {NULL}
};

PyDoc_STRVAR(BZ2Decompressor_eof__doc__,
"True if the end-of-stream marker has been reached.");

PyDoc_STRVAR(BZ2Decompressor_unused_data__doc__,
"Data found after the end of the compressed stream.");

PyDoc_STRVAR(BZ2Decompressor_needs_input_doc,
"True if more input is needed before more decompressed data can be produced.");

static PyMemberDef BZ2Decompressor_members[] = {
    {"eof", T_BOOL, offsetof(BZ2Decompressor, eof),
     READONLY, BZ2Decompressor_eof__doc__},
    {"unused_data", T_OBJECT_EX, offsetof(BZ2Decompressor, unused_data),
     READONLY, BZ2Decompressor_unused_data__doc__},
    {"needs_input", T_BOOL, offsetof(BZ2Decompressor, needs_input), READONLY,
     BZ2Decompressor_needs_input_doc},
    {NULL}
};

static PyType_Slot bz2_decompressor_type_slots[] = {
    {Py_tp_dealloc, BZ2Decompressor_dealloc},
    {Py_tp_methods, BZ2Decompressor_methods},
    {Py_tp_init, _bz2_BZ2Decompressor___init__},
    {Py_tp_doc, (char *)_bz2_BZ2Decompressor___init____doc__},
    {Py_tp_members, BZ2Decompressor_members},
    {Py_tp_new, PyType_GenericNew},
    {Py_tp_traverse, BZ2Decompressor_traverse},
    {0, 0}
};

static PyType_Spec bz2_decompressor_type_spec = {
    .name = "_bz2.BZ2Decompressor",
    .basicsize = sizeof(BZ2Decompressor),
    // Calling PyType_GetModuleState() on a subclass is not safe.
    // bz2_decompressor_type_spec does not have Py_TPFLAGS_BASETYPE flag
    // which prevents to create a subclass.
    // So calling PyType_GetModuleState() in this file is always safe.
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE),
    .slots = bz2_decompressor_type_slots,
};

/* Module initialization. */

static int
_bz2_exec(PyObject *module)
{
    _bz2_state *state = get_bz2_state(module);
    state->bz2_compressor_type = (PyTypeObject *)PyType_FromModuleAndSpec(module,
                                                            &bz2_compressor_type_spec, NULL);
    if (state->bz2_compressor_type == NULL) {
        return -1;
    }

    if (PyModule_AddType(module, state->bz2_compressor_type) < 0) {
        return -1;
    }

    state->bz2_decompressor_type = (PyTypeObject *)PyType_FromModuleAndSpec(module,
                                                         &bz2_decompressor_type_spec, NULL);
    if (state->bz2_decompressor_type == NULL) {
        return -1;
    }

    if (PyModule_AddType(module, state->bz2_decompressor_type) < 0) {
        return -1;
    }

    return 0;
}

static int
_bz2_traverse(PyObject *module, visitproc visit, void *arg)
{
    _bz2_state *state = get_bz2_state(module);
    Py_VISIT(state->bz2_compressor_type);
    Py_VISIT(state->bz2_decompressor_type);
    return 0;
}

static int
_bz2_clear(PyObject *module)
{
    _bz2_state *state = get_bz2_state(module);
    Py_CLEAR(state->bz2_compressor_type);
    Py_CLEAR(state->bz2_decompressor_type);
    return 0;
}

static void
_bz2_free(void *module)
{
    _bz2_clear((PyObject *)module);
}

static struct PyModuleDef_Slot _bz2_slots[] = {
    {Py_mod_exec, _bz2_exec},
    {0, NULL}
};

static struct PyModuleDef _bz2module = {
    PyModuleDef_HEAD_INIT,
    .m_name = "_bz2",
    .m_size = sizeof(_bz2_state),
    .m_slots = _bz2_slots,
    .m_traverse = _bz2_traverse,
    .m_clear = _bz2_clear,
    .m_free = _bz2_free,
};

PyMODINIT_FUNC
PyInit__bz2(void)
{
    return PyModuleDef_Init(&_bz2module);
}