Skip to content
Navigation Menu
{{ message }}
forked from python/cpython
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathmemoryobject.c
More file actions
3736 lines (3167 loc) · 108 KB
/
Copy pathmemoryobject.c
File metadata and controls
3736 lines (3167 loc) · 108 KB
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
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
/*
* Memoryview object implementation
* --------------------------------
*
* This implementation is a complete rewrite contributed by Stefan Krah in
* Python 3.3. Substantial credit goes to Antoine Pitrou (who had already
* fortified and rewritten the previous implementation) and Nick Coghlan
* (who came up with the idea of the ManagedBuffer) for analyzing the complex
* ownership rules.
*
*/
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_memoryobject.h" // _PyManagedBuffer_Type
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include "pycore_strhex.h" // _Py_strhex_with_sep()
#include <stddef.h> // offsetof()
/*[clinic input]
class memoryview "PyMemoryViewObject *" "&PyMemoryView_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=e2e49d2192835219]*/
#include "clinic/memoryobject.c.h"
/****************************************************************************/
/* ManagedBuffer Object */
/****************************************************************************/
/*
ManagedBuffer Object:
---------------------
The purpose of this object is to facilitate the handling of chained
memoryviews that have the same underlying exporting object. PEP-3118
allows the underlying object to change while a view is exported. This
could lead to unexpected results when constructing a new memoryview
from an existing memoryview.
Rather than repeatedly redirecting buffer requests to the original base
object, all chained memoryviews use a single buffer snapshot. This
snapshot is generated by the constructor _PyManagedBuffer_FromObject().
Ownership rules:
----------------
The master buffer inside a managed buffer is filled in by the original
base object. shape, strides, suboffsets and format are read-only for
all consumers.
A memoryview's buffer is a private copy of the exporter's buffer. shape,
strides and suboffsets belong to the memoryview and are thus writable.
If a memoryview itself exports several buffers via memory_getbuf(), all
buffer copies share shape, strides and suboffsets. In this case, the
arrays are NOT writable.
Reference count assumptions:
----------------------------
The 'obj' member of a Py_buffer must either be NULL or refer to the
exporting base object. In the Python codebase, all getbufferprocs
return a new reference to view.obj (example: bytes_buffer_getbuffer()).
PyBuffer_Release() decrements view.obj (if non-NULL), so the
releasebufferprocs must NOT decrement view.obj.
*/
static inline _PyManagedBufferObject *
mbuf_alloc(void)
{
_PyManagedBufferObject *mbuf;
mbuf = (_PyManagedBufferObject *)
PyObject_GC_New(_PyManagedBufferObject, &_PyManagedBuffer_Type);
if (mbuf == NULL)
return NULL;
mbuf->flags = 0;
mbuf->exports = 0;
mbuf->master.obj = NULL;
_PyObject_GC_TRACK(mbuf);
return mbuf;
}
static PyObject *
_PyManagedBuffer_FromObject(PyObject *base, int flags)
{
_PyManagedBufferObject *mbuf;
mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
if (PyObject_GetBuffer(base, &mbuf->master, flags) < 0) {
mbuf->master.obj = NULL;
Py_DECREF(mbuf);
return NULL;
}
return (PyObject *)mbuf;
}
static void
mbuf_release(_PyManagedBufferObject *self)
{
if (self->flags&_Py_MANAGED_BUFFER_RELEASED)
return;
self->flags |= _Py_MANAGED_BUFFER_RELEASED;
/* PyBuffer_Release() decrements master->obj and sets it to NULL. */
_PyObject_GC_UNTRACK(self);
PyBuffer_Release(&self->master);
}
static void
mbuf_dealloc(PyObject *_self)
{
_PyManagedBufferObject *self = (_PyManagedBufferObject *)_self;
assert(self->exports == 0);
mbuf_release(self);
if (self->flags&_Py_MANAGED_BUFFER_FREE_FORMAT)
PyMem_Free(self->master.format);
PyObject_GC_Del(self);
}
static int
mbuf_traverse(PyObject *_self, visitproc visit, void *arg)
{
_PyManagedBufferObject *self = (_PyManagedBufferObject *)_self;
Py_VISIT(self->master.obj);
return 0;
}
static int
mbuf_clear(PyObject *_self)
{
_PyManagedBufferObject *self = (_PyManagedBufferObject *)_self;
assert(self->exports >= 0);
mbuf_release(self);
return 0;
}
PyTypeObject _PyManagedBuffer_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"managedbuffer",
sizeof(_PyManagedBufferObject),
0,
mbuf_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
0, /* tp_doc */
mbuf_traverse, /* tp_traverse */
mbuf_clear /* tp_clear */
};
/****************************************************************************/
/* MemoryView Object */
/****************************************************************************/
/* In the process of breaking reference cycles mbuf_release() can be
called before memory_release(). */
#define BASE_INACCESSIBLE(mv) \
(((PyMemoryViewObject *)mv)->flags&_Py_MEMORYVIEW_RELEASED || \
((PyMemoryViewObject *)mv)->mbuf->flags&_Py_MANAGED_BUFFER_RELEASED)
#define CHECK_RELEASED(mv) \
if (BASE_INACCESSIBLE(mv)) { \
PyErr_SetString(PyExc_ValueError, \
"operation forbidden on released memoryview object"); \
return NULL; \
}
#define CHECK_RELEASED_INT(mv) \
if (BASE_INACCESSIBLE(mv)) { \
PyErr_SetString(PyExc_ValueError, \
"operation forbidden on released memoryview object"); \
return -1; \
}
#define CHECK_RESTRICTED(mv) \
if (((PyMemoryViewObject *)(mv))->flags & _Py_MEMORYVIEW_RESTRICTED) { \
PyErr_SetString(PyExc_ValueError, \
"cannot create new view on restricted memoryview"); \
return NULL; \
}
#define CHECK_RESTRICTED_INT(mv) \
if (((PyMemoryViewObject *)(mv))->flags & _Py_MEMORYVIEW_RESTRICTED) { \
PyErr_SetString(PyExc_ValueError, \
"cannot create new view on restricted memoryview"); \
return -1; \
}
/* See gh-92888. These macros signal that we need to check the memoryview
again due to possible read after frees. */
#define CHECK_RELEASED_AGAIN(mv) CHECK_RELEASED(mv)
#define CHECK_RELEASED_INT_AGAIN(mv) CHECK_RELEASED_INT(mv)
#define CHECK_LIST_OR_TUPLE(v) \
if (!PyList_Check(v) && !PyTuple_Check(v)) { \
PyErr_SetString(PyExc_TypeError, \
#v " must be a list or a tuple"); \
return NULL; \
}
#define VIEW_ADDR(mv) (&((PyMemoryViewObject *)mv)->view)
/* Check for the presence of suboffsets in the first dimension. */
#define HAVE_PTR(suboffsets, dim) (suboffsets && suboffsets[dim] >= 0)
/* Adjust ptr if suboffsets are present. */
#define ADJUST_PTR(ptr, suboffsets, dim) \
(HAVE_PTR(suboffsets, dim) ? *((char**)ptr) + suboffsets[dim] : ptr)
/* Memoryview buffer properties */
#define MV_C_CONTIGUOUS(flags) (flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C))
#define MV_F_CONTIGUOUS(flags) \
(flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_FORTRAN))
#define MV_ANY_CONTIGUOUS(flags) \
(flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN))
/* Fast contiguity test. Caller must ensure suboffsets==NULL and ndim==1. */
#define MV_CONTIGUOUS_NDIM1(view) \
((view)->shape[0] == 1 || (view)->strides[0] == (view)->itemsize)
/* getbuffer() requests */
#define REQ_INDIRECT(flags) ((flags&PyBUF_INDIRECT) == PyBUF_INDIRECT)
#define REQ_C_CONTIGUOUS(flags) ((flags&PyBUF_C_CONTIGUOUS) == PyBUF_C_CONTIGUOUS)
#define REQ_F_CONTIGUOUS(flags) ((flags&PyBUF_F_CONTIGUOUS) == PyBUF_F_CONTIGUOUS)
#define REQ_ANY_CONTIGUOUS(flags) ((flags&PyBUF_ANY_CONTIGUOUS) == PyBUF_ANY_CONTIGUOUS)
#define REQ_STRIDES(flags) ((flags&PyBUF_STRIDES) == PyBUF_STRIDES)
#define REQ_SHAPE(flags) ((flags&PyBUF_ND) == PyBUF_ND)
#define REQ_WRITABLE(flags) (flags&PyBUF_WRITABLE)
#define REQ_FORMAT(flags) (flags&PyBUF_FORMAT)
/**************************************************************************/
/* Copy memoryview buffers */
/**************************************************************************/
/* The functions in this section take a source and a destination buffer
with the same logical structure: format, itemsize, ndim and shape
are identical, with ndim > 0.
NOTE: All buffers are assumed to have PyBUF_FULL information, which
is the case for memoryviews! */
/* Assumptions: ndim >= 1. The macro tests for a corner case that should
perhaps be explicitly forbidden in the PEP. */
#define HAVE_SUBOFFSETS_IN_LAST_DIM(view) \
(view->suboffsets && view->suboffsets[view->ndim-1] >= 0)
static inline int
last_dim_is_contiguous(const Py_buffer *dest, const Py_buffer *src)
{
assert(dest->ndim > 0 && src->ndim > 0);
return (!HAVE_SUBOFFSETS_IN_LAST_DIM(dest) &&
!HAVE_SUBOFFSETS_IN_LAST_DIM(src) &&
dest->strides[dest->ndim-1] == dest->itemsize &&
src->strides[src->ndim-1] == src->itemsize);
}
/* This is not a general function for determining format equivalence.
It is used in copy_single() and copy_buffer() to weed out non-matching
formats. Skipping the '@' character is specifically used in slice
assignments, where the lvalue is already known to have a
format. This is a performance hack that could be rewritten (if properly
benchmarked). */
static inline int
equiv_format(const Py_buffer *dest, const Py_buffer *src)
{
const char *dfmt, *sfmt;
assert(dest->format && src->format);
dfmt = dest->format[0] == '@' ? dest->format+1 : dest->format;
sfmt = src->format[0] == '@' ? src->format+1 : src->format;
if (strcmp(dfmt, sfmt) != 0 ||
dest->itemsize != src->itemsize) {
return 0;
}
return 1;
}
/* Two shapes are equivalent if they are either equal or identical up
to a zero element at the same position. For example, in NumPy arrays
the shapes [1, 0, 5] and [1, 0, 7] are equivalent. */
static inline int
equiv_shape(const Py_buffer *dest, const Py_buffer *src)
{
int i;
if (dest->ndim != src->ndim)
return 0;
for (i = 0; i < dest->ndim; i++) {
if (dest->shape[i] != src->shape[i])
return 0;
if (dest->shape[i] == 0)
break;
}
return 1;
}
/* Check that the logical structure of the destination and source buffers
is identical. */
static int
equiv_structure(const Py_buffer *dest, const Py_buffer *src)
{
if (!equiv_format(dest, src) ||
!equiv_shape(dest, src)) {
PyErr_SetString(PyExc_ValueError,
"memoryview assignment: lvalue and rvalue have different "
"structures");
return 0;
}
return 1;
}
/* Base case for recursive multi-dimensional copying. Contiguous arrays are
copied with very little overhead. Assumptions: ndim == 1, mem == NULL or
sizeof(mem) == shape[0] * itemsize. */
static void
copy_base(const Py_ssize_t *shape, Py_ssize_t itemsize,
char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
char *mem)
{
if (mem == NULL) { /* contiguous */
Py_ssize_t size = shape[0] * itemsize;
if (dptr + size < sptr || sptr + size < dptr)
memcpy(dptr, sptr, size); /* no overlapping */
else
memmove(dptr, sptr, size);
}
else {
char *p;
Py_ssize_t i;
for (i=0, p=mem; i < shape[0]; p+=itemsize, sptr+=sstrides[0], i++) {
char *xsptr = ADJUST_PTR(sptr, ssuboffsets, 0);
memcpy(p, xsptr, itemsize);
}
for (i=0, p=mem; i < shape[0]; p+=itemsize, dptr+=dstrides[0], i++) {
char *xdptr = ADJUST_PTR(dptr, dsuboffsets, 0);
memcpy(xdptr, p, itemsize);
}
}
}
/* Recursively copy a source buffer to a destination buffer. The two buffers
have the same ndim, shape and itemsize. */
static void
copy_rec(const Py_ssize_t *shape, Py_ssize_t ndim, Py_ssize_t itemsize,
char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
char *mem)
{
Py_ssize_t i;
assert(ndim >= 1);
if (ndim == 1) {
copy_base(shape, itemsize,
dptr, dstrides, dsuboffsets,
sptr, sstrides, ssuboffsets,
mem);
return;
}
for (i = 0; i < shape[0]; dptr+=dstrides[0], sptr+=sstrides[0], i++) {
char *xdptr = ADJUST_PTR(dptr, dsuboffsets, 0);
char *xsptr = ADJUST_PTR(sptr, ssuboffsets, 0);
copy_rec(shape+1, ndim-1, itemsize,
xdptr, dstrides+1, dsuboffsets ? dsuboffsets+1 : NULL,
xsptr, sstrides+1, ssuboffsets ? ssuboffsets+1 : NULL,
mem);
}
}
/* Faster copying of one-dimensional arrays. */
static int
copy_single(PyMemoryViewObject *self, const Py_buffer *dest, const Py_buffer *src)
{
CHECK_RELEASED_INT_AGAIN(self);
char *mem = NULL;
assert(dest->ndim == 1);
if (!equiv_structure(dest, src))
return -1;
if (!last_dim_is_contiguous(dest, src)) {
mem = PyMem_Malloc(dest->shape[0] * dest->itemsize);
if (mem == NULL) {
PyErr_NoMemory();
return -1;
}
}
copy_base(dest->shape, dest->itemsize,
dest->buf, dest->strides, dest->suboffsets,
src->buf, src->strides, src->suboffsets,
mem);
if (mem)
PyMem_Free(mem);
return 0;
}
/* Recursively copy src to dest. Both buffers must have the same basic
structure. Copying is atomic, the function never fails with a partial
copy. */
static int
copy_buffer(const Py_buffer *dest, const Py_buffer *src)
{
char *mem = NULL;
assert(dest->ndim > 0);
if (!equiv_structure(dest, src))
return -1;
if (!last_dim_is_contiguous(dest, src)) {
mem = PyMem_Malloc(dest->shape[dest->ndim-1] * dest->itemsize);
if (mem == NULL) {
PyErr_NoMemory();
return -1;
}
}
copy_rec(dest->shape, dest->ndim, dest->itemsize,
dest->buf, dest->strides, dest->suboffsets,
src->buf, src->strides, src->suboffsets,
mem);
if (mem)
PyMem_Free(mem);
return 0;
}
/* Initialize strides for a C-contiguous array. */
static inline void
init_strides_from_shape(Py_buffer *view)
{
Py_ssize_t i;
assert(view->ndim > 0);
view->strides[view->ndim-1] = view->itemsize;
for (i = view->ndim-2; i >= 0; i--)
view->strides[i] = view->strides[i+1] * view->shape[i+1];
}
/* Initialize strides for a Fortran-contiguous array. */
static inline void
init_fortran_strides_from_shape(Py_buffer *view)
{
Py_ssize_t i;
assert(view->ndim > 0);
view->strides[0] = view->itemsize;
for (i = 1; i < view->ndim; i++)
view->strides[i] = view->strides[i-1] * view->shape[i-1];
}
/* Copy src to a contiguous representation. order is one of 'C', 'F' (Fortran)
or 'A' (Any). Assumptions: src has PyBUF_FULL information, src->ndim >= 1,
len(mem) == src->len. */
static int
buffer_to_contiguous(char *mem, const Py_buffer *src, char order)
{
Py_buffer dest;
Py_ssize_t *strides;
int ret;
assert(src->ndim >= 1);
assert(src->shape != NULL);
assert(src->strides != NULL);
strides = PyMem_Malloc(src->ndim * (sizeof *src->strides));
if (strides == NULL) {
PyErr_NoMemory();
return -1;
}
/* initialize dest */
dest = *src;
dest.buf = mem;
/* shape is constant and shared: the logical representation of the
array is unaltered. */
/* The physical representation determined by strides (and possibly
suboffsets) may change. */
dest.strides = strides;
if (order == 'C' || order == 'A') {
init_strides_from_shape(&dest);
}
else {
init_fortran_strides_from_shape(&dest);
}
dest.suboffsets = NULL;
ret = copy_buffer(&dest, src);
PyMem_Free(strides);
return ret;
}
/****************************************************************************/
/* Constructors */
/****************************************************************************/
/* Initialize values that are shared with the managed buffer. */
static inline void
init_shared_values(Py_buffer *dest, const Py_buffer *src)
{
dest->obj = src->obj;
dest->buf = src->buf;
dest->len = src->len;
dest->itemsize = src->itemsize;
dest->readonly = src->readonly;
dest->format = src->format ? src->format : "B";
dest->internal = src->internal;
}
/* Copy shape and strides. Reconstruct missing values. */
static void
init_shape_strides(Py_buffer *dest, const Py_buffer *src)
{
Py_ssize_t i;
if (src->ndim == 0) {
dest->shape = NULL;
dest->strides = NULL;
return;
}
if (src->ndim == 1) {
dest->shape[0] = src->shape ? src->shape[0] : src->len / src->itemsize;
dest->strides[0] = src->strides ? src->strides[0] : src->itemsize;
return;
}
for (i = 0; i < src->ndim; i++)
dest->shape[i] = src->shape[i];
if (src->strides) {
for (i = 0; i < src->ndim; i++)
dest->strides[i] = src->strides[i];
}
else {
init_strides_from_shape(dest);
}
}
static inline void
init_suboffsets(Py_buffer *dest, const Py_buffer *src)
{
Py_ssize_t i;
if (src->suboffsets == NULL) {
dest->suboffsets = NULL;
return;
}
for (i = 0; i < src->ndim; i++)
dest->suboffsets[i] = src->suboffsets[i];
}
/* len = product(shape) * itemsize */
static inline void
init_len(Py_buffer *view)
{
Py_ssize_t i, len;
len = 1;
for (i = 0; i < view->ndim; i++)
len *= view->shape[i];
len *= view->itemsize;
view->len = len;
}
/* Initialize memoryview buffer properties. */
static void
init_flags(PyMemoryViewObject *mv)
{
const Py_buffer *view = &mv->view;
int flags = 0;
switch (view->ndim) {
case 0:
flags |= (_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C|
_Py_MEMORYVIEW_FORTRAN);
break;
case 1:
if (MV_CONTIGUOUS_NDIM1(view))
flags |= (_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN);
break;
default:
if (PyBuffer_IsContiguous(view, 'C'))
flags |= _Py_MEMORYVIEW_C;
if (PyBuffer_IsContiguous(view, 'F'))
flags |= _Py_MEMORYVIEW_FORTRAN;
break;
}
if (view->suboffsets) {
flags |= _Py_MEMORYVIEW_PIL;
flags &= ~(_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN);
}
mv->flags = flags;
}
/* Allocate a new memoryview and perform basic initialization. New memoryviews
are exclusively created through the mbuf_add functions. */
static inline PyMemoryViewObject *
memory_alloc(int ndim)
{
PyMemoryViewObject *mv;
mv = (PyMemoryViewObject *)
PyObject_GC_NewVar(PyMemoryViewObject, &PyMemoryView_Type, 3*ndim);
if (mv == NULL)
return NULL;
mv->mbuf = NULL;
mv->hash = -1;
mv->flags = 0;
mv->exports = 0;
mv->view.ndim = ndim;
mv->view.shape = mv->ob_array;
mv->view.strides = mv->ob_array + ndim;
mv->view.suboffsets = mv->ob_array + 2 * ndim;
mv->weakreflist = NULL;
_PyObject_GC_TRACK(mv);
return mv;
}
/*
Return a new memoryview that is registered with mbuf. If src is NULL,
use mbuf->master as the underlying buffer. Otherwise, use src.
The new memoryview has full buffer information: shape and strides
are always present, suboffsets as needed. Arrays are copied to
the memoryview's ob_array field.
*/
static PyObject *
mbuf_add_view(_PyManagedBufferObject *mbuf, const Py_buffer *src)
{
PyMemoryViewObject *mv;
Py_buffer *dest;
if (src == NULL)
src = &mbuf->master;
if (src->ndim > PyBUF_MAX_NDIM) {
PyErr_SetString(PyExc_ValueError,
"memoryview: number of dimensions must not exceed "
Py_STRINGIFY(PyBUF_MAX_NDIM));
return NULL;
}
mv = memory_alloc(src->ndim);
if (mv == NULL)
return NULL;
dest = &mv->view;
init_shared_values(dest, src);
init_shape_strides(dest, src);
init_suboffsets(dest, src);
init_flags(mv);
mv->mbuf = (_PyManagedBufferObject*)Py_NewRef(mbuf);
mbuf->exports++;
return (PyObject *)mv;
}
/* Register an incomplete view: shape, strides, suboffsets and flags still
need to be initialized. Use 'ndim' instead of src->ndim to determine the
size of the memoryview's ob_array.
Assumption: ndim <= PyBUF_MAX_NDIM. */
static PyObject *
mbuf_add_incomplete_view(_PyManagedBufferObject *mbuf, const Py_buffer *src,
int ndim)
{
PyMemoryViewObject *mv;
Py_buffer *dest;
if (src == NULL)
src = &mbuf->master;
assert(ndim <= PyBUF_MAX_NDIM);
mv = memory_alloc(ndim);
if (mv == NULL)
return NULL;
dest = &mv->view;
init_shared_values(dest, src);
mv->mbuf = (_PyManagedBufferObject*)Py_NewRef(mbuf);
mbuf->exports++;
return (PyObject *)mv;
}
/* Expose a raw memory area as a view of contiguous bytes. flags can be
PyBUF_READ or PyBUF_WRITE. view->format is set to "B" (unsigned bytes).
The memoryview has complete buffer information. */
PyObject *
PyMemoryView_FromMemory(char *mem, Py_ssize_t size, int flags)
{
_PyManagedBufferObject *mbuf;
PyObject *mv;
int readonly;
assert(mem != NULL);
assert(flags == PyBUF_READ || flags == PyBUF_WRITE);
mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
readonly = (flags == PyBUF_WRITE) ? 0 : 1;
(void)PyBuffer_FillInfo(&mbuf->master, NULL, mem, size, readonly,
PyBUF_FULL_RO);
mv = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return mv;
}
/* Create a memoryview from a given Py_buffer. For simple byte views,
PyMemoryView_FromMemory() should be used instead.
This function is the only entry point that can create a master buffer
without full information. Because of this fact init_shape_strides()
must be able to reconstruct missing values. */
PyObject *
PyMemoryView_FromBuffer(const Py_buffer *info)
{
_PyManagedBufferObject *mbuf;
PyObject *mv;
if (info->buf == NULL) {
PyErr_SetString(PyExc_ValueError,
"PyMemoryView_FromBuffer(): info->buf must not be NULL");
return NULL;
}
mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
/* info->obj is either NULL or a borrowed reference. This reference
should not be decremented in PyBuffer_Release(). */
mbuf->master = *info;
mbuf->master.obj = NULL;
mv = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return mv;
}
/* Create a memoryview from an object that implements the buffer protocol,
using the given flags.
If the object is a memoryview, the new memoryview must be registered
with the same managed buffer. Otherwise, a new managed buffer is created. */
static PyObject *
PyMemoryView_FromObjectAndFlags(PyObject *v, int flags)
{
_PyManagedBufferObject *mbuf;
if (PyMemoryView_Check(v)) {
PyMemoryViewObject *mv = (PyMemoryViewObject *)v;
CHECK_RELEASED(mv);
CHECK_RESTRICTED(mv);
return mbuf_add_view(mv->mbuf, &mv->view);
}
else if (PyObject_CheckBuffer(v)) {
PyObject *ret;
mbuf = (_PyManagedBufferObject *)_PyManagedBuffer_FromObject(v, flags);
if (mbuf == NULL)
return NULL;
ret = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return ret;
}
PyErr_Format(PyExc_TypeError,
"memoryview: a bytes-like object is required, not '%.200s'",
Py_TYPE(v)->tp_name);
return NULL;
}
/* Create a memoryview from an object that implements the buffer protocol,
using the given flags.
If the object is a memoryview, the new memoryview must be registered
with the same managed buffer. Otherwise, a new managed buffer is created. */
PyObject *
_PyMemoryView_FromBufferProc(PyObject *v, int flags, getbufferproc bufferproc)
{
_PyManagedBufferObject *mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
int res = bufferproc(v, &mbuf->master, flags);
if (res < 0) {
mbuf->master.obj = NULL;
Py_DECREF(mbuf);
return NULL;
}
PyObject *ret = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return ret;
}
/* Create a memoryview from an object that implements the buffer protocol.
If the object is a memoryview, the new memoryview must be registered
with the same managed buffer. Otherwise, a new managed buffer is created. */
PyObject *
PyMemoryView_FromObject(PyObject *v)
{
return PyMemoryView_FromObjectAndFlags(v, PyBUF_FULL_RO);
}
/* Copy the format string from a base object that might vanish. */
static int
mbuf_copy_format(_PyManagedBufferObject *mbuf, const char *fmt)
{
if (fmt != NULL) {
char *cp = PyMem_Malloc(strlen(fmt)+1);
if (cp == NULL) {
PyErr_NoMemory();
return -1;
}
mbuf->master.format = strcpy(cp, fmt);
mbuf->flags |= _Py_MANAGED_BUFFER_FREE_FORMAT;
}
return 0;
}
/*
Return a memoryview that is based on a contiguous copy of src.
Assumptions: src has PyBUF_FULL_RO information, src->ndim > 0.
Ownership rules:
1) As usual, the returned memoryview has a private copy
of src->shape, src->strides and src->suboffsets.
2) src->format is copied to the master buffer and released
in mbuf_dealloc(). The releasebufferproc of the bytes
object is NULL, so it does not matter that mbuf_release()
passes the altered format pointer to PyBuffer_Release().
*/
static PyObject *
memory_from_contiguous_copy(const Py_buffer *src, char order)
{
_PyManagedBufferObject *mbuf;
PyMemoryViewObject *mv;
PyObject *bytes;
Py_buffer *dest;
int i;
assert(src->ndim > 0);
assert(src->shape != NULL);
bytes = PyBytes_FromStringAndSize(NULL, src->len);
if (bytes == NULL)
return NULL;
mbuf = (_PyManagedBufferObject *)_PyManagedBuffer_FromObject(bytes, PyBUF_FULL_RO);
Py_DECREF(bytes);
if (mbuf == NULL)
return NULL;
if (mbuf_copy_format(mbuf, src->format) < 0) {
Py_DECREF(mbuf);
return NULL;
}
mv = (PyMemoryViewObject *)mbuf_add_incomplete_view(mbuf, NULL, src->ndim);
Py_DECREF(mbuf);
if (mv == NULL)
return NULL;
dest = &mv->view;
/* shared values are initialized correctly except for itemsize */
dest->itemsize = src->itemsize;
/* shape and strides */
for (i = 0; i < src->ndim; i++) {
dest->shape[i] = src->shape[i];
}
if (order == 'C' || order == 'A') {
init_strides_from_shape(dest);
}
else {
init_fortran_strides_from_shape(dest);
}
/* suboffsets */
dest->suboffsets = NULL;
/* flags */
init_flags(mv);
if (copy_buffer(dest, src) < 0) {
Py_DECREF(mv);
return NULL;
}
return (PyObject *)mv;
}
/*
Return a new memoryview object based on a contiguous exporter with
buffertype={PyBUF_READ, PyBUF_WRITE} and order={'C', 'F'ortran, or 'A'ny}.
The logical structure of the input and output buffers is the same
(i.e. tolist(input) == tolist(output)), but the physical layout in
memory can be explicitly chosen.
As usual, if buffertype=PyBUF_WRITE, the exporter's buffer must be writable,
otherwise it may be writable or read-only.
If the exporter is already contiguous with the desired target order,
the memoryview will be directly based on the exporter.
Otherwise, if the buffertype is PyBUF_READ, the memoryview will be
based on a new bytes object. If order={'C', 'A'ny}, use 'C' order,
'F'ortran order otherwise.
*/
PyObject *
PyMemoryView_GetContiguous(PyObject *obj, int buffertype, char order)
{
PyMemoryViewObject *mv;
PyObject *ret;
Py_buffer *view;
assert(buffertype == PyBUF_READ || buffertype == PyBUF_WRITE);
assert(order == 'C' || order == 'F' || order == 'A');
mv = (PyMemoryViewObject *)PyMemoryView_FromObject(obj);
if (mv == NULL)
return NULL;
view = &mv->view;
if (buffertype == PyBUF_WRITE && view->readonly) {
PyErr_SetString(PyExc_BufferError,
"underlying buffer is not writable");
Py_DECREF(mv);
return NULL;
}
if (PyBuffer_IsContiguous(view, order))
return (PyObject *)mv;
if (buffertype == PyBUF_WRITE) {
PyErr_SetString(PyExc_BufferError,
"writable contiguous buffer requested "
"for a non-contiguous object.");
Py_DECREF(mv);
return NULL;
}
ret = memory_from_contiguous_copy(view, order);
Py_DECREF(mv);
return ret;
You can’t perform that action at this time.