summaryrefslogtreecommitdiffstats
path: root/Modules/zlibmodule.c
blob: 725755d10563bec49866ba7e95b69c8906f563d0 (plain)
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
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
/* zlibmodule.c -- gzip-compatible data compression */
/* See http://www.gzip.org/zlib/ */

/* Windows users:  read Python's PCbuild\readme.txt */


#include "Python.h"
#include "zlib.h"

#ifdef WITH_THREAD
#include "pythread.h"

/* #defs ripped off from _tkinter.c, even though the situation here is much
   simpler, because we don't have to worry about waiting for Tcl
   events!  And, since zlib itself is threadsafe, we don't need to worry
   about re-entering zlib functions.

   N.B.

   Since ENTER_ZLIB and LEAVE_ZLIB only need to be called on functions
   that modify the components of preexisting de/compress objects, it
   could prove to be a performance gain on multiprocessor machines if
   there was an de/compress object-specific lock.  However, for the
   moment the ENTER_ZLIB and LEAVE_ZLIB calls are global for ALL
   de/compress objects.
 */

static PyThread_type_lock zlib_lock = NULL; /* initialized on module load */

#define ENTER_ZLIB \
	Py_BEGIN_ALLOW_THREADS \
	PyThread_acquire_lock(zlib_lock, 1); \
	Py_END_ALLOW_THREADS

#define LEAVE_ZLIB \
	PyThread_release_lock(zlib_lock);

#else

#define ENTER_ZLIB
#define LEAVE_ZLIB

#endif

/* The following parameters are copied from zutil.h, version 0.95 */
#define DEFLATED   8
#if MAX_MEM_LEVEL >= 8
#  define DEF_MEM_LEVEL 8
#else
#  define DEF_MEM_LEVEL  MAX_MEM_LEVEL
#endif
#define DEF_WBITS MAX_WBITS

/* The output buffer will be increased in chunks of DEFAULTALLOC bytes. */
#define DEFAULTALLOC (16*1024)
#define PyInit_zlib initzlib

static PyTypeObject Comptype;
static PyTypeObject Decomptype;

static PyObject *ZlibError;

typedef struct
{
    PyObject_HEAD
    z_stream zst;
    PyObject *unused_data;
    PyObject *unconsumed_tail;
    int is_initialised;
} compobject;

static void
zlib_error(z_stream zst, int err, char *msg)
{
    if (zst.msg == Z_NULL)
	PyErr_Format(ZlibError, "Error %d %s", err, msg);
    else
	PyErr_Format(ZlibError, "Error %d %s: %.200s", err, msg, zst.msg);
}

PyDoc_STRVAR(compressobj__doc__,
"compressobj([level]) -- Return a compressor object.\n"
"\n"
"Optional arg level is the compression level, in 1-9.");

PyDoc_STRVAR(decompressobj__doc__,
"decompressobj([wbits]) -- Return a decompressor object.\n"
"\n"
"Optional arg wbits is the window buffer size.");

static compobject *
newcompobject(PyTypeObject *type)
{
    compobject *self;
    self = PyObject_New(compobject, type);
    if (self == NULL)
	return NULL;
    self->is_initialised = 0;
    self->unused_data = PyString_FromString("");
    if (self->unused_data == NULL) {
	Py_DECREF(self);
	return NULL;
    }
    self->unconsumed_tail = PyString_FromString("");
    if (self->unconsumed_tail == NULL) {
	Py_DECREF(self);
	return NULL;
    }
    return self;
}

PyDoc_STRVAR(compress__doc__,
"compress(string[, level]) -- Returned compressed string.\n"
"\n"
"Optional arg level is the compression level, in 1-9.");

static PyObject *
PyZlib_compress(PyObject *self, PyObject *args)
{
    PyObject *ReturnVal = NULL;
    Byte *input, *output;
    int length, level=Z_DEFAULT_COMPRESSION, err;
    z_stream zst;

    /* require Python string object, optional 'level' arg */
    if (!PyArg_ParseTuple(args, "s#|i:compress", &input, &length, &level))
	return NULL;

    zst.avail_out = length + length/1000 + 12 + 1;

    output = (Byte*)malloc(zst.avail_out);
    if (output == NULL) {
	PyErr_SetString(PyExc_MemoryError,
			"Can't allocate memory to compress data");
	return NULL;
    }

    /* Past the point of no return.  From here on out, we need to make sure
       we clean up mallocs & INCREFs. */

    zst.zalloc = (alloc_func)NULL;
    zst.zfree = (free_func)Z_NULL;
    zst.next_out = (Byte *)output;
    zst.next_in = (Byte *)input;
    zst.avail_in = length;
    err = deflateInit(&zst, level);

    switch(err) {
    case(Z_OK):
	break;
    case(Z_MEM_ERROR):
	PyErr_SetString(PyExc_MemoryError,
			"Out of memory while compressing data");
	goto error;
    case(Z_STREAM_ERROR):
	PyErr_SetString(ZlibError,
			"Bad compression level");
	goto error;
    default:
        deflateEnd(&zst);
	zlib_error(zst, err, "while compressing data");
	goto error;
    }

    Py_BEGIN_ALLOW_THREADS;
    err = deflate(&zst, Z_FINISH);
    Py_END_ALLOW_THREADS;

    if (err != Z_STREAM_END) {
	zlib_error(zst, err, "while compressing data");
	deflateEnd(&zst);
	goto error;
    }

    err=deflateEnd(&zst);
    if (err == Z_OK)
	ReturnVal = PyString_FromStringAndSize((char *)output,
					       zst.total_out);
    else
	zlib_error(zst, err, "while finishing compression");

 error:
    free(output);

    return ReturnVal;
}

PyDoc_STRVAR(decompress__doc__,
"decompress(string[, wbits[, bufsize]]) -- Return decompressed string.\n"
"\n"
"Optional arg wbits is the window buffer size.  Optional arg bufsize is\n"
"the initial output buffer size.");

static PyObject *
PyZlib_decompress(PyObject *self, PyObject *args)
{
    PyObject *result_str;
    Byte *input;
    int length, err;
    int wsize=DEF_WBITS, r_strlen=DEFAULTALLOC;
    z_stream zst;

    if (!PyArg_ParseTuple(args, "s#|ii:decompress",
			  &input, &length, &wsize, &r_strlen))
	return NULL;

    if (r_strlen <= 0)
	r_strlen = 1;

    zst.avail_in = length;
    zst.avail_out = r_strlen;

    if (!(result_str = PyString_FromStringAndSize(NULL, r_strlen)))
	return NULL;

    zst.zalloc = (alloc_func)NULL;
    zst.zfree = (free_func)Z_NULL;
    zst.next_out = (Byte *)PyString_AS_STRING(result_str);
    zst.next_in = (Byte *)input;
    err = inflateInit2(&zst, wsize);

    switch(err) {
    case(Z_OK):
	break;
    case(Z_MEM_ERROR):
	PyErr_SetString(PyExc_MemoryError,
			"Out of memory while decompressing data");
	goto error;
    default:
        inflateEnd(&zst);
	zlib_error(zst, err, "while preparing to decompress data");
	goto error;
    }

    do {
	Py_BEGIN_ALLOW_THREADS
	err=inflate(&zst, Z_FINISH);
	Py_END_ALLOW_THREADS

	switch(err) {
	case(Z_STREAM_END):
	    break;
	case(Z_BUF_ERROR):
	    /*
	     * If there is at least 1 byte of room according to zst.avail_out
	     * and we get this error, assume that it means zlib cannot
	     * process the inflate call() due to an error in the data.
	     */
	    if (zst.avail_out > 0) {
		PyErr_Format(ZlibError, "Error %i while decompressing data",
			     err);
		inflateEnd(&zst);
		goto error;
	    }
	    /* fall through */
	case(Z_OK):
	    /* need more memory */
	    if (_PyString_Resize(&result_str, r_strlen << 1) < 0) {
		inflateEnd(&zst);
		goto error;
	    }
	    zst.next_out = (unsigned char *)PyString_AS_STRING(result_str) \
		+ r_strlen;
	    zst.avail_out = r_strlen;
	    r_strlen = r_strlen << 1;
	    break;
	default:
	    inflateEnd(&zst);
	    zlib_error(zst, err, "while decompressing data");
	    goto error;
	}
    } while (err != Z_STREAM_END);

    err = inflateEnd(&zst);
    if (err != Z_OK) {
	zlib_error(zst, err, "while finishing data decompression");
	goto error;
    }

    _PyString_Resize(&result_str, zst.total_out);
    return result_str;

 error:
    Py_XDECREF(result_str);
    return NULL;
}

static PyObject *
PyZlib_compressobj(PyObject *selfptr, PyObject *args)
{
    compobject *self;
    int level=Z_DEFAULT_COMPRESSION, method=DEFLATED;
    int wbits=MAX_WBITS, memLevel=DEF_MEM_LEVEL, strategy=0, err;

    if (!PyArg_ParseTuple(args, "|iiiii:compressobj", &level, &method, &wbits,
			  &memLevel, &strategy))
	return NULL;

    self = newcompobject(&Comptype);
    if (self==NULL)
	return(NULL);
    self->zst.zalloc = (alloc_func)NULL;
    self->zst.zfree = (free_func)Z_NULL;
    self->zst.next_in = NULL;
    self->zst.avail_in = 0;
    err = deflateInit2(&self->zst, level, method, wbits, memLevel, strategy);
    switch(err) {
    case (Z_OK):
	self->is_initialised = 1;
	return (PyObject*)self;
    case (Z_MEM_ERROR):
	Py_DECREF(self);
	PyErr_SetString(PyExc_MemoryError,
			"Can't allocate memory for compression object");
	return NULL;
    case(Z_STREAM_ERROR):
	Py_DECREF(self);
	PyErr_SetString(PyExc_ValueError, "Invalid initialization option");
	return NULL;
    default:
	zlib_error(self->zst, err, "while creating compression object");
        Py_DECREF(self);
	return NULL;
    }
}

static PyObject *
PyZlib_decompressobj(PyObject *selfptr, PyObject *args)
{
    int wbits=DEF_WBITS, err;
    compobject *self;
    if (!PyArg_ParseTuple(args, "|i:decompressobj", &wbits))
	return NULL;

    self = newcompobject(&Decomptype);
    if (self == NULL)
	return(NULL);
    self->zst.zalloc = (alloc_func)NULL;
    self->zst.zfree = (free_func)Z_NULL;
    self->zst.next_in = NULL;
    self->zst.avail_in = 0;
    err = inflateInit2(&self->zst, wbits);
    switch(err) {
    case (Z_OK):
	self->is_initialised = 1;
	return (PyObject*)self;
    case(Z_STREAM_ERROR):
	Py_DECREF(self);
	PyErr_SetString(PyExc_ValueError, "Invalid initialization option");
	return NULL;
    case (Z_MEM_ERROR):
	Py_DECREF(self);
	PyErr_SetString(PyExc_MemoryError,
			"Can't allocate memory for decompression object");
	return NULL;
    default:
	zlib_error(self->zst, err, "while creating decompression object");
        Py_DECREF(self);
	return NULL;
    }
}

static void
Comp_dealloc(compobject *self)
{
    if (self->is_initialised)
	deflateEnd(&self->zst);
    Py_XDECREF(self->unused_data);
    Py_XDECREF(self->unconsumed_tail);
    PyObject_Del(self);
}

static void
Decomp_dealloc(compobject *self)
{
    if (self->is_initialised)
	inflateEnd(&self->zst);
    Py_XDECREF(self->unused_data);
    Py_XDECREF(self->unconsumed_tail);
    PyObject_Del(self);
}

PyDoc_STRVAR(comp_compress__doc__,
"compress(data) -- Return a string containing data compressed.\n"
"\n"
"After calling this function, some of the input data may still\n"
"be stored in internal buffers for later processing.\n"
"Call the flush() method to clear these buffers.");


static PyObject *
PyZlib_objcompress(compobject *self, PyObject *args)
{
    int err, inplen, length = DEFAULTALLOC;
    PyObject *RetVal;
    Byte *input;
    unsigned long start_total_out;

    if (!PyArg_ParseTuple(args, "s#:compress", &input, &inplen))
	return NULL;

    if (!(RetVal = PyString_FromStringAndSize(NULL, length)))
	return NULL;

    ENTER_ZLIB

    start_total_out = self->zst.total_out;
    self->zst.avail_in = inplen;
    self->zst.next_in = input;
    self->zst.avail_out = length;
    self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal);

    Py_BEGIN_ALLOW_THREADS
    err = deflate(&(self->zst), Z_NO_FLUSH);
    Py_END_ALLOW_THREADS

    /* while Z_OK and the output buffer is full, there might be more output,
       so extend the output buffer and try again */
    while (err == Z_OK && self->zst.avail_out == 0) {
	if (_PyString_Resize(&RetVal, length << 1) < 0)
	    goto error;
	self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal) \
	    + length;
	self->zst.avail_out = length;
	length = length << 1;

	Py_BEGIN_ALLOW_THREADS
	err = deflate(&(self->zst), Z_NO_FLUSH);
	Py_END_ALLOW_THREADS
    }
    /* We will only get Z_BUF_ERROR if the output buffer was full but
       there wasn't more output when we tried again, so it is not an error
       condition.
    */

    if (err != Z_OK && err != Z_BUF_ERROR) {
	zlib_error(self->zst, err, "while compressing");
	Py_DECREF(RetVal);
	RetVal = NULL;
	goto error;
    }
    _PyString_Resize(&RetVal, self->zst.total_out - start_total_out);

 error:
    LEAVE_ZLIB
    return RetVal;
}

PyDoc_STRVAR(decomp_decompress__doc__,
"decompress(data, max_length) -- Return a string containing the decompressed\n"
"version of the data.\n"
"\n"
"After calling this function, some of the input data may still be stored in\n"
"internal buffers for later processing.\n"
"Call the flush() method to clear these buffers.\n"
"If the max_length parameter is specified then the return value will be\n"
"no longer than max_length.  Unconsumed input data will be stored in\n"
"the unconsumed_tail attribute.");

static PyObject *
PyZlib_objdecompress(compobject *self, PyObject *args)
{
    int err, inplen, old_length, length = DEFAULTALLOC;
    int max_length = 0;
    PyObject *RetVal;
    Byte *input;
    unsigned long start_total_out;

    if (!PyArg_ParseTuple(args, "s#|i:decompress", &input,
			  &inplen, &max_length))
	return NULL;
    if (max_length < 0) {
	PyErr_SetString(PyExc_ValueError,
			"max_length must be greater than zero");
	return NULL;
    }

    /* limit amount of data allocated to max_length */
    if (max_length && length > max_length)
	length = max_length;
    if (!(RetVal = PyString_FromStringAndSize(NULL, length)))
	return NULL;

    ENTER_ZLIB

    start_total_out = self->zst.total_out;
    self->zst.avail_in = inplen;
    self->zst.next_in = input;
    self->zst.avail_out = length;
    self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal);

    Py_BEGIN_ALLOW_THREADS
    err = inflate(&(self->zst), Z_SYNC_FLUSH);
    Py_END_ALLOW_THREADS

    /* While Z_OK and the output buffer is full, there might be more output.
       So extend the output buffer and try again.
    */
    while (err == Z_OK && self->zst.avail_out == 0) {
	/* If max_length set, don't continue decompressing if we've already
	   reached the limit.
	*/
	if (max_length && length >= max_length)
	    break;

	/* otherwise, ... */
	old_length = length;
	length = length << 1;
	if (max_length && length > max_length)
	    length = max_length;

	if (_PyString_Resize(&RetVal, length) < 0)
	    goto error;
	self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal) \
	    + old_length;
	self->zst.avail_out = length - old_length;

	Py_BEGIN_ALLOW_THREADS
	err = inflate(&(self->zst), Z_SYNC_FLUSH);
	Py_END_ALLOW_THREADS
    }

    /* Not all of the compressed data could be accommodated in the output buffer
       of specified size. Return the unconsumed tail in an attribute.*/
    if(max_length) {
	Py_DECREF(self->unconsumed_tail);
	self->unconsumed_tail = PyString_FromStringAndSize((char *)self->zst.next_in,
							   self->zst.avail_in);
	if(!self->unconsumed_tail) {
	    Py_DECREF(RetVal);
	    RetVal = NULL;
	    goto error;
	}
    }

    /* The end of the compressed data has been reached, so set the
       unused_data attribute to a string containing the remainder of the
       data in the string.  Note that this is also a logical place to call
       inflateEnd, but the old behaviour of only calling it on flush() is
       preserved.
    */
    if (err == Z_STREAM_END) {
	Py_XDECREF(self->unused_data);  /* Free original empty string */
	self->unused_data = PyString_FromStringAndSize(
	    (char *)self->zst.next_in, self->zst.avail_in);
	if (self->unused_data == NULL) {
	    Py_DECREF(RetVal);
	    goto error;
	}
	/* We will only get Z_BUF_ERROR if the output buffer was full
	   but there wasn't more output when we tried again, so it is
	   not an error condition.
	*/
    } else if (err != Z_OK && err != Z_BUF_ERROR) {
	zlib_error(self->zst, err, "while decompressing");
	Py_DECREF(RetVal);
	RetVal = NULL;
	goto error;
    }

    _PyString_Resize(&RetVal, self->zst.total_out - start_total_out);

 error:
    LEAVE_ZLIB

    return RetVal;
}

PyDoc_STRVAR(comp_flush__doc__,
"flush( [mode] ) -- Return a string containing any remaining compressed data.\n"
"\n"
"mode can be one of the constants Z_SYNC_FLUSH, Z_FULL_FLUSH, Z_FINISH; the\n"
"default value used when mode is not specified is Z_FINISH.\n"
"If mode == Z_FINISH, the compressor object can no longer be used after\n"
"calling the flush() method.  Otherwise, more data can still be compressed.");

static PyObject *
PyZlib_flush(compobject *self, PyObject *args)
{
    int err, length = DEFAULTALLOC;
    PyObject *RetVal;
    int flushmode = Z_FINISH;
    unsigned long start_total_out;

    if (!PyArg_ParseTuple(args, "|i:flush", &flushmode))
	return NULL;

    /* Flushing with Z_NO_FLUSH is a no-op, so there's no point in
       doing any work at all; just return an empty string. */
    if (flushmode == Z_NO_FLUSH) {
	return PyString_FromStringAndSize(NULL, 0);
    }

    if (!(RetVal = PyString_FromStringAndSize(NULL, length)))
	return NULL;

    ENTER_ZLIB

    start_total_out = self->zst.total_out;
    self->zst.avail_in = 0;
    self->zst.avail_out = length;
    self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal);

    Py_BEGIN_ALLOW_THREADS
    err = deflate(&(self->zst), flushmode);
    Py_END_ALLOW_THREADS

    /* while Z_OK and the output buffer is full, there might be more output,
       so extend the output buffer and try again */
    while (err == Z_OK && self->zst.avail_out == 0) {
	if (_PyString_Resize(&RetVal, length << 1) < 0)
	    goto error;
	self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal) \
	    + length;
	self->zst.avail_out = length;
	length = length << 1;

	Py_BEGIN_ALLOW_THREADS
	err = deflate(&(self->zst), flushmode);
	Py_END_ALLOW_THREADS
    }

    /* If flushmode is Z_FINISH, we also have to call deflateEnd() to free
       various data structures. Note we should only get Z_STREAM_END when
       flushmode is Z_FINISH, but checking both for safety*/
    if (err == Z_STREAM_END && flushmode == Z_FINISH) {
	err = deflateEnd(&(self->zst));
	if (err != Z_OK) {
	    zlib_error(self->zst, err, "from deflateEnd()");
	    Py_DECREF(RetVal);
	    RetVal = NULL;
	    goto error;
	}
	else
	    self->is_initialised = 0;

	/* We will only get Z_BUF_ERROR if the output buffer was full
	   but there wasn't more output when we tried again, so it is
	   not an error condition.
	*/
    } else if (err!=Z_OK && err!=Z_BUF_ERROR) {
	zlib_error(self->zst, err, "while flushing");
	Py_DECREF(RetVal);
	RetVal = NULL;
	goto error;
    }

    _PyString_Resize(&RetVal, self->zst.total_out - start_total_out);

 error:
    LEAVE_ZLIB

    return RetVal;
}

PyDoc_STRVAR(decomp_flush__doc__,
"flush() -- Return a string containing any remaining decompressed data.\n"
"\n"
"The decompressor object can no longer be used after this call.");

static PyObject *
PyZlib_unflush(compobject *self, PyObject *args)
{
    int err, length = DEFAULTALLOC;
    PyObject * retval = NULL;
    unsigned long start_total_out;

    if (!PyArg_ParseTuple(args, "|i:flush", &length))
	return NULL;
    if (!(retval = PyString_FromStringAndSize(NULL, length)))
	return NULL;


    ENTER_ZLIB

    start_total_out = self->zst.total_out;
    self->zst.avail_out = length;
    self->zst.next_out = (Byte *)PyString_AS_STRING(retval);

    Py_BEGIN_ALLOW_THREADS
    err = inflate(&(self->zst), Z_FINISH);
    Py_END_ALLOW_THREADS

    /* while Z_OK and the output buffer is full, there might be more output,
       so extend the output buffer and try again */
    while ((err == Z_OK || err == Z_BUF_ERROR) && self->zst.avail_out == 0) {
	if (_PyString_Resize(&retval, length << 1) < 0)
	    goto error;
	self->zst.next_out = (Byte *)PyString_AS_STRING(retval) + length;
	self->zst.avail_out = length;
	length = length << 1;

	Py_BEGIN_ALLOW_THREADS
	err = inflate(&(self->zst), Z_FINISH);
	Py_END_ALLOW_THREADS
    }

    /* If flushmode is Z_FINISH, we also have to call deflateEnd() to free
       various data structures. Note we should only get Z_STREAM_END when
       flushmode is Z_FINISH */
    if (err == Z_STREAM_END) {
	err = inflateEnd(&(self->zst));
        self->is_initialised = 0;
	if (err != Z_OK) {
	    zlib_error(self->zst, err, "from inflateEnd()");
	    Py_DECREF(retval);
	    retval = NULL;
	    goto error;
	}
    }
    _PyString_Resize(&retval, self->zst.total_out - start_total_out);

error:

    LEAVE_ZLIB

    return retval;
}

static PyMethodDef comp_methods[] =
{
    {"compress", (binaryfunc)PyZlib_objcompress, METH_VARARGS,
                 comp_compress__doc__},
    {"flush", (binaryfunc)PyZlib_flush, METH_VARARGS,
              comp_flush__doc__},
    {NULL, NULL}
};

static PyMethodDef Decomp_methods[] =
{
    {"decompress", (binaryfunc)PyZlib_objdecompress, METH_VARARGS,
                   decomp_decompress__doc__},
    {"flush", (binaryfunc)PyZlib_unflush, METH_VARARGS,
              decomp_flush__doc__},
    {NULL, NULL}
};

static PyObject *
Comp_getattr(compobject *self, char *name)
{
  /* No ENTER/LEAVE_ZLIB is necessary because this fn doesn't touch
     internal data. */

  return Py_FindMethod(comp_methods, (PyObject *)self, name);
}

static PyObject *
Decomp_getattr(compobject *self, char *name)
{
    PyObject * retval;

    ENTER_ZLIB

    if (strcmp(name, "unused_data") == 0) {
	Py_INCREF(self->unused_data);
	retval = self->unused_data;
    } else if (strcmp(name, "unconsumed_tail") == 0) {
	Py_INCREF(self->unconsumed_tail);
	retval = self->unconsumed_tail;
    } else
	retval = Py_FindMethod(Decomp_methods, (PyObject *)self, name);

    LEAVE_ZLIB

    return retval;
}

PyDoc_STRVAR(adler32__doc__,
"adler32(string[, start]) -- Compute an Adler-32 checksum of string.\n"
"\n"
"An optional starting value can be specified.  The returned checksum is\n"
"an integer.");

static PyObject *
PyZlib_adler32(PyObject *self, PyObject *args)
{
    uLong adler32val = adler32(0L, Z_NULL, 0);
    Byte *buf;
    int len;

    if (!PyArg_ParseTuple(args, "s#|k:adler32", &buf, &len, &adler32val))
	return NULL;
    adler32val = adler32(adler32val, buf, len);
    return PyInt_FromLong(adler32val);
}

PyDoc_STRVAR(crc32__doc__,
"crc32(string[, start]) -- Compute a CRC-32 checksum of string.\n"
"\n"
"An optional starting value can be specified.  The returned checksum is\n"
"an integer.");

static PyObject *
PyZlib_crc32(PyObject *self, PyObject *args)
{
    uLong crc32val = crc32(0L, Z_NULL, 0);
    Byte *buf;
    int len;
    if (!PyArg_ParseTuple(args, "s#|k:crc32", &buf, &len, &crc32val))
	return NULL;
    crc32val = crc32(crc32val, buf, len);
    return PyInt_FromLong(crc32val);
}


static PyMethodDef zlib_methods[] =
{
    {"adler32", (PyCFunction)PyZlib_adler32, METH_VARARGS,
                adler32__doc__},
    {"compress", (PyCFunction)PyZlib_compress,  METH_VARARGS,
                 compress__doc__},
    {"compressobj", (PyCFunction)PyZlib_compressobj, METH_VARARGS,
                    compressobj__doc__},
    {"crc32", (PyCFunction)PyZlib_crc32, METH_VARARGS,
              crc32__doc__},
    {"decompress", (PyCFunction)PyZlib_decompress, METH_VARARGS,
                   decompress__doc__},
    {"decompressobj", (PyCFunction)PyZlib_decompressobj, METH_VARARGS,
                   decompressobj__doc__},
    {NULL, NULL}
};

static PyTypeObject Comptype = {
    PyObject_HEAD_INIT(0)
    0,
    "zlib.Compress",
    sizeof(compobject),
    0,
    (destructor)Comp_dealloc,       /*tp_dealloc*/
    0,                              /*tp_print*/
    (getattrfunc)Comp_getattr,      /*tp_getattr*/
    0,                              /*tp_setattr*/
    0,                              /*tp_compare*/
    0,                              /*tp_repr*/
    0,                              /*tp_as_number*/
    0,                              /*tp_as_sequence*/
    0,                              /*tp_as_mapping*/
};

static PyTypeObject Decomptype = {
    PyObject_HEAD_INIT(0)
    0,
    "zlib.Decompress",
    sizeof(compobject),
    0,
    (destructor)Decomp_dealloc,     /*tp_dealloc*/
    0,                              /*tp_print*/
    (getattrfunc)Decomp_getattr,    /*tp_getattr*/
    0,                              /*tp_setattr*/
    0,                              /*tp_compare*/
    0,                              /*tp_repr*/
    0,                              /*tp_as_number*/
    0,                              /*tp_as_sequence*/
    0,                              /*tp_as_mapping*/
};

PyDoc_STRVAR(zlib_module_documentation,
"The functions in this module allow compression and decompression using the\n"
"zlib library, which is based on GNU zip.\n"
"\n"
"adler32(string[, start]) -- Compute an Adler-32 checksum.\n"
"compress(string[, level]) -- Compress string, with compression level in 1-9.\n"
"compressobj([level]) -- Return a compressor object.\n"
"crc32(string[, start]) -- Compute a CRC-32 checksum.\n"
"decompress(string,[wbits],[bufsize]) -- Decompresses a compressed string.\n"
"decompressobj([wbits]) -- Return a decompressor object.\n"
"\n"
"'wbits' is window buffer size.\n"
"Compressor objects support compress() and flush() methods; decompressor\n"
"objects support decompress() and flush().");

PyMODINIT_FUNC
PyInit_zlib(void)
{
    PyObject *m, *ver;
    Comptype.ob_type = &PyType_Type;
    Decomptype.ob_type = &PyType_Type;
    m = Py_InitModule4("zlib", zlib_methods,
		       zlib_module_documentation,
		       (PyObject*)NULL,PYTHON_API_VERSION);
    if (m == NULL)
	return;

    ZlibError = PyErr_NewException("zlib.error", NULL, NULL);
    if (ZlibError != NULL) {
        Py_INCREF(ZlibError);
	PyModule_AddObject(m, "error", ZlibError);
    }
    PyModule_AddIntConstant(m, "MAX_WBITS", MAX_WBITS);
    PyModule_AddIntConstant(m, "DEFLATED", DEFLATED);
    PyModule_AddIntConstant(m, "DEF_MEM_LEVEL", DEF_MEM_LEVEL);
    PyModule_AddIntConstant(m, "Z_BEST_SPEED", Z_BEST_SPEED);
    PyModule_AddIntConstant(m, "Z_BEST_COMPRESSION", Z_BEST_COMPRESSION);
    PyModule_AddIntConstant(m, "Z_DEFAULT_COMPRESSION", Z_DEFAULT_COMPRESSION);
    PyModule_AddIntConstant(m, "Z_FILTERED", Z_FILTERED);
    PyModule_AddIntConstant(m, "Z_HUFFMAN_ONLY", Z_HUFFMAN_ONLY);
    PyModule_AddIntConstant(m, "Z_DEFAULT_STRATEGY", Z_DEFAULT_STRATEGY);

    PyModule_AddIntConstant(m, "Z_FINISH", Z_FINISH);
    PyModule_AddIntConstant(m, "Z_NO_FLUSH", Z_NO_FLUSH);
    PyModule_AddIntConstant(m, "Z_SYNC_FLUSH", Z_SYNC_FLUSH);
    PyModule_AddIntConstant(m, "Z_FULL_FLUSH", Z_FULL_FLUSH);

    ver = PyString_FromString(ZLIB_VERSION);
    if (ver != NULL)
	PyModule_AddObject(m, "ZLIB_VERSION", ver);

    PyModule_AddStringConstant(m, "__version__", "1.0");

#ifdef WITH_THREAD
    zlib_lock = PyThread_allocate_lock();
#endif /* WITH_THREAD */
}