Repository navigation
Expand file tree
/
Copy pathstgdict.c
More file actions
909 lines (834 loc) · 31.6 KB
/
Copy pathstgdict.c
File metadata and controls
909 lines (834 loc) · 31.6 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
#ifndef Py_BUILD_CORE_BUILTIN
# define Py_BUILD_CORE_MODULE 1
#endif
#define NEEDS_PY_IDENTIFIER
#include "Python.h"
// windows.h must be included before pycore internal headers
#ifdef MS_WIN32
# include <windows.h>
#endif
#include "pycore_call.h" // _PyObject_CallNoArgs()
#include <ffi.h>
#ifdef MS_WIN32
# include <malloc.h>
#endif
#include "ctypes.h"
/******************************************************************/
/*
StdDict - a dictionary subclass, containing additional C accessible fields
XXX blabla more
*/
/* Seems we need this, otherwise we get problems when calling
* PyDict_SetItem() (ma_lookup is NULL)
*/
static int
PyCStgDict_init(StgDictObject *self, PyObject *args, PyObject *kwds)
{
if (PyDict_Type.tp_init((PyObject *)self, args, kwds) < 0)
return -1;
self->format = NULL;
self->ndim = 0;
self->shape = NULL;
return 0;
}
static int
PyCStgDict_clear(StgDictObject *self)
{
Py_CLEAR(self->proto);
Py_CLEAR(self->argtypes);
Py_CLEAR(self->converters);
Py_CLEAR(self->restype);
Py_CLEAR(self->checker);
return 0;
}
static void
PyCStgDict_dealloc(StgDictObject *self)
{
PyCStgDict_clear(self);
PyMem_Free(self->format);
PyMem_Free(self->shape);
PyMem_Free(self->ffi_type_pointer.elements);
PyDict_Type.tp_dealloc((PyObject *)self);
}
static PyObject *
PyCStgDict_sizeof(StgDictObject *self, void *unused)
{
Py_ssize_t res;
res = _PyDict_SizeOf((PyDictObject *)self);
res += sizeof(StgDictObject) - sizeof(PyDictObject);
if (self->format)
res += strlen(self->format) + 1;
res += self->ndim * sizeof(Py_ssize_t);
if (self->ffi_type_pointer.elements)
res += (self->length + 1) * sizeof(ffi_type *);
return PyLong_FromSsize_t(res);
}
int
PyCStgDict_clone(StgDictObject *dst, StgDictObject *src)
{
char *d, *s;
Py_ssize_t size;
PyCStgDict_clear(dst);
PyMem_Free(dst->ffi_type_pointer.elements);
PyMem_Free(dst->format);
dst->format = NULL;
PyMem_Free(dst->shape);
dst->shape = NULL;
dst->ffi_type_pointer.elements = NULL;
d = (char *)dst;
s = (char *)src;
memcpy(d + sizeof(PyDictObject),
s + sizeof(PyDictObject),
sizeof(StgDictObject) - sizeof(PyDictObject));
Py_XINCREF(dst->proto);
Py_XINCREF(dst->argtypes);
Py_XINCREF(dst->converters);
Py_XINCREF(dst->restype);
Py_XINCREF(dst->checker);
if (src->format) {
dst->format = PyMem_Malloc(strlen(src->format) + 1);
if (dst->format == NULL) {
PyErr_NoMemory();
return -1;
}
strcpy(dst->format, src->format);
}
if (src->shape) {
dst->shape = PyMem_Malloc(sizeof(Py_ssize_t) * src->ndim);
if (dst->shape == NULL) {
PyErr_NoMemory();
return -1;
}
memcpy(dst->shape, src->shape,
sizeof(Py_ssize_t) * src->ndim);
}
if (src->ffi_type_pointer.elements == NULL)
return 0;
size = sizeof(ffi_type *) * (src->length + 1);
dst->ffi_type_pointer.elements = PyMem_Malloc(size);
if (dst->ffi_type_pointer.elements == NULL) {
PyErr_NoMemory();
return -1;
}
memcpy(dst->ffi_type_pointer.elements,
src->ffi_type_pointer.elements,
size);
return 0;
}
static struct PyMethodDef PyCStgDict_methods[] = {
{"__sizeof__", (PyCFunction)PyCStgDict_sizeof, METH_NOARGS},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyCStgDict_Type = {
PyVarObject_HEAD_INIT(NULL, 0)
"StgDict",
sizeof(StgDictObject),
0,
(destructor)PyCStgDict_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 */
0, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
PyCStgDict_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
(initproc)PyCStgDict_init, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
0, /* tp_free */
};
/* May return NULL, but does not set an exception! */
StgDictObject *
PyType_stgdict(PyObject *obj)
{
PyTypeObject *type;
if (!PyType_Check(obj))
return NULL;
type = (PyTypeObject *)obj;
if (!type->tp_dict || !PyCStgDict_CheckExact(type->tp_dict))
return NULL;
return (StgDictObject *)type->tp_dict;
}
/* May return NULL, but does not set an exception! */
/*
This function should be as fast as possible, so we don't call PyType_stgdict
above but inline the code, and avoid the PyType_Check().
*/
StgDictObject *
PyObject_stgdict(PyObject *self)
{
PyTypeObject *type = Py_TYPE(self);
if (!type->tp_dict || !PyCStgDict_CheckExact(type->tp_dict))
return NULL;
return (StgDictObject *)type->tp_dict;
}
/* descr is the descriptor for a field marked as anonymous. Get all the
_fields_ descriptors from descr->proto, create new descriptors with offset
and index adjusted, and stuff them into type.
*/
static int
MakeFields(PyObject *type, CFieldObject *descr,
Py_ssize_t index, Py_ssize_t offset)
{
Py_ssize_t i;
PyObject *fields;
PyObject *fieldlist;
fields = PyObject_GetAttrString(descr->proto, "_fields_");
if (fields == NULL)
return -1;
fieldlist = PySequence_Fast(fields, "_fields_ must be a sequence");
Py_DECREF(fields);
if (fieldlist == NULL)
return -1;
for (i = 0; i < PySequence_Fast_GET_SIZE(fieldlist); ++i) {
PyObject *pair = PySequence_Fast_GET_ITEM(fieldlist, i); /* borrowed */
PyObject *fname, *ftype, *bits;
CFieldObject *fdescr;
CFieldObject *new_descr;
/* Convert to PyArg_UnpackTuple... */
if (!PyArg_ParseTuple(pair, "OO|O", &fname, &ftype, &bits)) {
Py_DECREF(fieldlist);
return -1;
}
fdescr = (CFieldObject *)PyObject_GetAttr(descr->proto, fname);
if (fdescr == NULL) {
Py_DECREF(fieldlist);
return -1;
}
if (!Py_IS_TYPE(fdescr, &PyCField_Type)) {
PyErr_SetString(PyExc_TypeError, "unexpected type");
Py_DECREF(fdescr);
Py_DECREF(fieldlist);
return -1;
}
if (fdescr->anonymous) {
int rc = MakeFields(type, fdescr,
index + fdescr->index,
offset + fdescr->offset);
Py_DECREF(fdescr);
if (rc == -1) {
Py_DECREF(fieldlist);
return -1;
}
continue;
}
new_descr = (CFieldObject *)PyCField_Type.tp_alloc((PyTypeObject *)&PyCField_Type, 0);
if (new_descr == NULL) {
Py_DECREF(fdescr);
Py_DECREF(fieldlist);
return -1;
}
assert(Py_IS_TYPE(new_descr, &PyCField_Type));
new_descr->size = fdescr->size;
new_descr->offset = fdescr->offset + offset;
new_descr->index = fdescr->index + index;
new_descr->proto = fdescr->proto;
Py_XINCREF(new_descr->proto);
new_descr->getfunc = fdescr->getfunc;
new_descr->setfunc = fdescr->setfunc;
Py_DECREF(fdescr);
if (-1 == PyObject_SetAttr(type, fname, (PyObject *)new_descr)) {
Py_DECREF(fieldlist);
Py_DECREF(new_descr);
return -1;
}
Py_DECREF(new_descr);
}
Py_DECREF(fieldlist);
return 0;
}
/* Iterate over the names in the type's _anonymous_ attribute, if present,
*/
static int
MakeAnonFields(PyObject *type)
{
_Py_IDENTIFIER(_anonymous_);
PyObject *anon;
PyObject *anon_names;
Py_ssize_t i;
if (_PyObject_LookupAttrId(type, &PyId__anonymous_, &anon) < 0) {
return -1;
}
if (anon == NULL) {
return 0;
}
anon_names = PySequence_Fast(anon, "_anonymous_ must be a sequence");
Py_DECREF(anon);
if (anon_names == NULL)
return -1;
for (i = 0; i < PySequence_Fast_GET_SIZE(anon_names); ++i) {
PyObject *fname = PySequence_Fast_GET_ITEM(anon_names, i); /* borrowed */
CFieldObject *descr = (CFieldObject *)PyObject_GetAttr(type, fname);
if (descr == NULL) {
Py_DECREF(anon_names);
return -1;
}
if (!Py_IS_TYPE(descr, &PyCField_Type)) {
PyErr_Format(PyExc_AttributeError,
"'%U' is specified in _anonymous_ but not in "
"_fields_",
fname);
Py_DECREF(anon_names);
Py_DECREF(descr);
return -1;
}
descr->anonymous = 1;
/* descr is in the field descriptor. */
if (-1 == MakeFields(type, (CFieldObject *)descr,
((CFieldObject *)descr)->index,
((CFieldObject *)descr)->offset)) {
Py_DECREF(descr);
Py_DECREF(anon_names);
return -1;
}
Py_DECREF(descr);
}
Py_DECREF(anon_names);
return 0;
}
/*
Retrieve the (optional) _pack_ attribute from a type, the _fields_ attribute,
and create an StgDictObject. Used for Structure and Union subclasses.
*/
int
PyCStructUnionType_update_stgdict(PyObject *type, PyObject *fields, int isStruct)
{
_Py_IDENTIFIER(_swappedbytes_);
_Py_IDENTIFIER(_use_broken_old_ctypes_structure_semantics_);
_Py_IDENTIFIER(_pack_);
StgDictObject *stgdict, *basedict;
Py_ssize_t len, offset, size, align, i;
Py_ssize_t union_size, total_align;
Py_ssize_t field_size = 0;
int bitofs;
PyObject *tmp;
int isPacked;
int pack;
Py_ssize_t ffi_ofs;
int big_endian;
int arrays_seen = 0;
/* HACK Alert: I cannot be bothered to fix ctypes.com, so there has to
be a way to use the old, broken semantics: _fields_ are not extended
but replaced in subclasses.
XXX Remove this in ctypes 1.0!
*/
int use_broken_old_ctypes_semantics;
if (fields == NULL)
return 0;
if (_PyObject_LookupAttrId(type, &PyId__swappedbytes_, &tmp) < 0) {
return -1;
}
if (tmp) {
Py_DECREF(tmp);
big_endian = !PY_BIG_ENDIAN;
}
else {
big_endian = PY_BIG_ENDIAN;
}
if (_PyObject_LookupAttrId(type,
&PyId__use_broken_old_ctypes_structure_semantics_, &tmp) < 0)
{
return -1;
}
if (tmp) {
Py_DECREF(tmp);
use_broken_old_ctypes_semantics = 1;
}
else {
use_broken_old_ctypes_semantics = 0;
}
if (_PyObject_LookupAttrId(type, &PyId__pack_, &tmp) < 0) {
return -1;
}
if (tmp) {
isPacked = 1;
pack = _PyLong_AsInt(tmp);
Py_DECREF(tmp);
if (pack < 0) {
if (!PyErr_Occurred() ||
PyErr_ExceptionMatches(PyExc_TypeError) ||
PyErr_ExceptionMatches(PyExc_OverflowError))
{
PyErr_SetString(PyExc_ValueError,
"_pack_ must be a non-negative integer");
}
return -1;
}
}
else {
isPacked = 0;
pack = 0;
}
len = PySequence_Size(fields);
if (len == -1) {
if (PyErr_ExceptionMatches(PyExc_TypeError)) {
PyErr_SetString(PyExc_TypeError,
"'_fields_' must be a sequence of pairs");
}
return -1;
}
stgdict = PyType_stgdict(type);
if (!stgdict) {
PyErr_SetString(PyExc_TypeError,
"ctypes state is not initialized");
return -1;
}
/* If this structure/union is already marked final we cannot assign
_fields_ anymore. */
if (stgdict->flags & DICTFLAG_FINAL) {/* is final ? */
PyErr_SetString(PyExc_AttributeError,
"_fields_ is final");
return -1;
}
if (stgdict->format) {
PyMem_Free(stgdict->format);
stgdict->format = NULL;
}
if (stgdict->ffi_type_pointer.elements)
PyMem_Free(stgdict->ffi_type_pointer.elements);
basedict = PyType_stgdict((PyObject *)((PyTypeObject *)type)->tp_base);
if (basedict) {
stgdict->flags |= (basedict->flags &
(TYPEFLAG_HASUNION | TYPEFLAG_HASBITFIELD));
}
if (!isStruct) {
stgdict->flags |= TYPEFLAG_HASUNION;
}
if (basedict && !use_broken_old_ctypes_semantics) {
size = offset = basedict->size;
align = basedict->align;
union_size = 0;
total_align = align ? align : 1;
stgdict->ffi_type_pointer.type = FFI_TYPE_STRUCT;
stgdict->ffi_type_pointer.elements = PyMem_New(ffi_type *, basedict->length + len + 1);
if (stgdict->ffi_type_pointer.elements == NULL) {
PyErr_NoMemory();
return -1;
}
memset(stgdict->ffi_type_pointer.elements, 0,
sizeof(ffi_type *) * (basedict->length + len + 1));
if (basedict->length > 0) {
memcpy(stgdict->ffi_type_pointer.elements,
basedict->ffi_type_pointer.elements,
sizeof(ffi_type *) * (basedict->length));
}
ffi_ofs = basedict->length;
} else {
offset = 0;
size = 0;
align = 0;
union_size = 0;
total_align = 1;
stgdict->ffi_type_pointer.type = FFI_TYPE_STRUCT;
stgdict->ffi_type_pointer.elements = PyMem_New(ffi_type *, len + 1);
if (stgdict->ffi_type_pointer.elements == NULL) {
PyErr_NoMemory();
return -1;
}
memset(stgdict->ffi_type_pointer.elements, 0,
sizeof(ffi_type *) * (len + 1));
ffi_ofs = 0;
}
assert(stgdict->format == NULL);
if (isStruct && !isPacked) {
stgdict->format = _ctypes_alloc_format_string(NULL, "T{");
} else {
/* PEP3118 doesn't support union, or packed structures (well,
only standard packing, but we don't support the pep for
that). Use 'B' for bytes. */
stgdict->format = _ctypes_alloc_format_string(NULL, "B");
}
if (stgdict->format == NULL)
return -1;
for (i = 0; i < len; ++i) {
PyObject *name = NULL, *desc = NULL;
PyObject *pair = PySequence_GetItem(fields, i);
PyObject *prop;
StgDictObject *dict;
int bitsize = 0;
if (!pair || !PyArg_ParseTuple(pair, "UO|i", &name, &desc, &bitsize)) {
PyErr_SetString(PyExc_TypeError,
"'_fields_' must be a sequence of (name, C type) pairs");
Py_XDECREF(pair);
return -1;
}
if (PyCArrayTypeObject_Check(desc))
arrays_seen = 1;
dict = PyType_stgdict(desc);
if (dict == NULL) {
Py_DECREF(pair);
PyErr_Format(PyExc_TypeError,
"second item in _fields_ tuple (index %zd) must be a C type",
i);
return -1;
}
stgdict->ffi_type_pointer.elements[ffi_ofs + i] = &dict->ffi_type_pointer;
if (dict->flags & (TYPEFLAG_ISPOINTER | TYPEFLAG_HASPOINTER))
stgdict->flags |= TYPEFLAG_HASPOINTER;
stgdict->flags |= dict->flags & (TYPEFLAG_HASUNION | TYPEFLAG_HASBITFIELD);
dict->flags |= DICTFLAG_FINAL; /* mark field type final */
if (PyTuple_Size(pair) == 3) { /* bits specified */
stgdict->flags |= TYPEFLAG_HASBITFIELD;
switch(dict->ffi_type_pointer.type) {
case FFI_TYPE_UINT8:
case FFI_TYPE_UINT16:
case FFI_TYPE_UINT32:
case FFI_TYPE_SINT64:
case FFI_TYPE_UINT64:
break;
case FFI_TYPE_SINT8:
case FFI_TYPE_SINT16:
case FFI_TYPE_SINT32:
if (dict->getfunc != _ctypes_get_fielddesc("c")->getfunc
&& dict->getfunc != _ctypes_get_fielddesc("u")->getfunc
)
break;
/* else fall through */
default:
PyErr_Format(PyExc_TypeError,
"bit fields not allowed for type %s",
((PyTypeObject *)desc)->tp_name);
Py_DECREF(pair);
return -1;
}
if (bitsize <= 0 || bitsize > dict->size * 8) {
PyErr_SetString(PyExc_ValueError,
"number of bits invalid for bit field");
Py_DECREF(pair);
return -1;
}
} else
bitsize = 0;
if (isStruct && !isPacked) {
const char *fieldfmt = dict->format ? dict->format : "B";
const char *fieldname = PyUnicode_AsUTF8(name);
char *ptr;
Py_ssize_t len;
char *buf;
if (fieldname == NULL)
{
Py_DECREF(pair);
return -1;
}
len = strlen(fieldname) + strlen(fieldfmt);
buf = PyMem_Malloc(len + 2 + 1);
if (buf == NULL) {
Py_DECREF(pair);
PyErr_NoMemory();
return -1;
}
sprintf(buf, "%s:%s:", fieldfmt, fieldname);
ptr = stgdict->format;
if (dict->shape != NULL) {
stgdict->format = _ctypes_alloc_format_string_with_shape(
dict->ndim, dict->shape, stgdict->format, buf);
} else {
stgdict->format = _ctypes_alloc_format_string(stgdict->format, buf);
}
PyMem_Free(ptr);
PyMem_Free(buf);
if (stgdict->format == NULL) {
Py_DECREF(pair);
return -1;
}
}
if (isStruct) {
prop = PyCField_FromDesc(desc, i,
&field_size, bitsize, &bitofs,
&size, &offset, &align,
pack, big_endian);
} else /* union */ {
size = 0;
offset = 0;
align = 0;
prop = PyCField_FromDesc(desc, i,
&field_size, bitsize, &bitofs,
&size, &offset, &align,
pack, big_endian);
union_size = max(size, union_size);
}
total_align = max(align, total_align);
if (!prop) {
Py_DECREF(pair);
return -1;
}
if (-1 == PyObject_SetAttr(type, name, prop)) {
Py_DECREF(prop);
Py_DECREF(pair);
return -1;
}
Py_DECREF(pair);
Py_DECREF(prop);
}
if (isStruct && !isPacked) {
char *ptr = stgdict->format;
stgdict->format = _ctypes_alloc_format_string(stgdict->format, "}");
PyMem_Free(ptr);
if (stgdict->format == NULL)
return -1;
}
if (!isStruct)
size = union_size;
/* Adjust the size according to the alignment requirements */
size = ((size + total_align - 1) / total_align) * total_align;
stgdict->ffi_type_pointer.alignment = Py_SAFE_DOWNCAST(total_align,
Py_ssize_t,
unsigned short);
stgdict->ffi_type_pointer.size = size;
stgdict->size = size;
stgdict->align = total_align;
stgdict->length = len; /* ADD ffi_ofs? */
#define MAX_STRUCT_SIZE 16
if (arrays_seen && (size <= MAX_STRUCT_SIZE)) {
/*
* See bpo-22273. Arrays are normally treated as pointers, which is
* fine when an array name is being passed as parameter, but not when
* passing structures by value that contain arrays. On 64-bit Linux,
* small structures passed by value are passed in registers, and in
* order to do this, libffi needs to know the true type of the array
* members of structs. Treating them as pointers breaks things.
*
* By small structures, we mean ones that are 16 bytes or less. In that
* case, there can't be more than 16 elements after unrolling arrays,
* as we (will) disallow bitfields. So we can collect the true ffi_type
* values in a fixed-size local array on the stack and, if any arrays
* were seen, replace the ffi_type_pointer.elements with a more
* accurate set, to allow libffi to marshal them into registers
* correctly. It means one more loop over the fields, but if we got
* here, the structure is small, so there aren't too many of those.
*
* Although the passing in registers is specific to 64-bit Linux, the
* array-in-struct vs. pointer problem is general. But we restrict the
* type transformation to small structs nonetheless.
*
* Note that although a union may be small in terms of memory usage, it
* could contain many overlapping declarations of arrays, e.g.
*
* union {
* unsigned int_8 foo [16];
* unsigned uint_8 bar [16];
* unsigned int_16 baz[8];
* unsigned uint_16 bozz[8];
* unsigned int_32 fizz[4];
* unsigned uint_32 buzz[4];
* }
*
* which is still only 16 bytes in size. We need to convert this into
* the following equivalent for libffi:
*
* union {
* struct { int_8 e1; int_8 e2; ... int_8 e_16; } f1;
* struct { uint_8 e1; uint_8 e2; ... uint_8 e_16; } f2;
* struct { int_16 e1; int_16 e2; ... int_16 e_8; } f3;
* struct { uint_16 e1; uint_16 e2; ... uint_16 e_8; } f4;
* struct { int_32 e1; int_32 e2; ... int_32 e_4; } f5;
* struct { uint_32 e1; uint_32 e2; ... uint_32 e_4; } f6;
* }
*
* So the struct/union needs setting up as follows: all non-array
* elements copied across as is, and all array elements replaced with
* an equivalent struct which has as many fields as the array has
* elements, plus one NULL pointer.
*/
Py_ssize_t num_ffi_type_pointers = 0; /* for the dummy fields */
Py_ssize_t num_ffi_types = 0; /* for the dummy structures */
size_t alloc_size; /* total bytes to allocate */
void *type_block; /* to hold all the type information needed */
ffi_type **element_types; /* of this struct/union */
ffi_type **dummy_types; /* of the dummy struct elements */
ffi_type *structs; /* point to struct aliases of arrays */
Py_ssize_t element_index; /* index into element_types for this */
Py_ssize_t dummy_index = 0; /* index into dummy field pointers */
Py_ssize_t struct_index = 0; /* index into dummy structs */
/* first pass to see how much memory to allocate */
for (i = 0; i < len; ++i) {
PyObject *name, *desc;
PyObject *pair = PySequence_GetItem(fields, i);
StgDictObject *dict;
int bitsize = 0;
if (pair == NULL) {
return -1;
}
if (!PyArg_ParseTuple(pair, "UO|i", &name, &desc, &bitsize)) {
PyErr_SetString(PyExc_TypeError,
"'_fields_' must be a sequence of (name, C type) pairs");
Py_DECREF(pair);
return -1;
}
dict = PyType_stgdict(desc);
if (dict == NULL) {
Py_DECREF(pair);
PyErr_Format(PyExc_TypeError,
"second item in _fields_ tuple (index %zd) must be a C type",
i);
return -1;
}
if (!PyCArrayTypeObject_Check(desc)) {
/* Not an array. Just need an ffi_type pointer. */
num_ffi_type_pointers++;
}
else {
/* It's an array. */
Py_ssize_t length = dict->length;
StgDictObject *edict;
edict = PyType_stgdict(dict->proto);
if (edict == NULL) {
Py_DECREF(pair);
PyErr_Format(PyExc_TypeError,
"second item in _fields_ tuple (index %zd) must be a C type",
i);
return -1;
}
/*
* We need one extra ffi_type to hold the struct, and one
* ffi_type pointer per array element + one for a NULL to
* mark the end.
*/
num_ffi_types++;
num_ffi_type_pointers += length + 1;
}
Py_DECREF(pair);
}
/*
* At this point, we know we need storage for some ffi_types and some
* ffi_type pointers. We'll allocate these in one block.
* There are three sub-blocks of information: the ffi_type pointers to
* this structure/union's elements, the ffi_type_pointers to the
* dummy fields standing in for array elements, and the
* ffi_types representing the dummy structures.
*/
alloc_size = (ffi_ofs + 1 + len + num_ffi_type_pointers) * sizeof(ffi_type *) +
num_ffi_types * sizeof(ffi_type);
type_block = PyMem_Malloc(alloc_size);
if (type_block == NULL) {
PyErr_NoMemory();
return -1;
}
/*
* the first block takes up ffi_ofs + len + 1 which is the pointers *
* for this struct/union. The second block takes up
* num_ffi_type_pointers, so the sum of these is ffi_ofs + len + 1 +
* num_ffi_type_pointers as allocated above. The last bit is the
* num_ffi_types structs.
*/
element_types = (ffi_type **) type_block;
dummy_types = &element_types[ffi_ofs + len + 1];
structs = (ffi_type *) &dummy_types[num_ffi_type_pointers];
if (num_ffi_types > 0) {
memset(structs, 0, num_ffi_types * sizeof(ffi_type));
}
if (ffi_ofs && (basedict != NULL)) {
memcpy(element_types,
basedict->ffi_type_pointer.elements,
ffi_ofs * sizeof(ffi_type *));
}
element_index = ffi_ofs;
/* second pass to actually set the type pointers */
for (i = 0; i < len; ++i) {
PyObject *name, *desc;
PyObject *pair = PySequence_GetItem(fields, i);
StgDictObject *dict;
int bitsize = 0;
if (pair == NULL) {
PyMem_Free(type_block);
return -1;
}
/* In theory, we made this call in the first pass, so it *shouldn't*
* fail. However, you never know, and the code above might change
* later - keeping the check in here is a tad defensive but it
* will affect program size only slightly and performance hardly at
* all.
*/
if (!PyArg_ParseTuple(pair, "UO|i", &name, &desc, &bitsize)) {
PyErr_SetString(PyExc_TypeError,
"'_fields_' must be a sequence of (name, C type) pairs");
Py_DECREF(pair);
PyMem_Free(type_block);
return -1;
}
dict = PyType_stgdict(desc);
/* Possibly this check could be avoided, but see above comment. */
if (dict == NULL) {
Py_DECREF(pair);
PyMem_Free(type_block);
PyErr_Format(PyExc_TypeError,
"second item in _fields_ tuple (index %zd) must be a C type",
i);
return -1;
}
assert(element_index < (ffi_ofs + len)); /* will be used below */
if (!PyCArrayTypeObject_Check(desc)) {
/* Not an array. Just copy over the element ffi_type. */
element_types[element_index++] = &dict->ffi_type_pointer;
}
else {
Py_ssize_t length = dict->length;
StgDictObject *edict;
edict = PyType_stgdict(dict->proto);
if (edict == NULL) {
Py_DECREF(pair);
PyMem_Free(type_block);
PyErr_Format(PyExc_TypeError,
"second item in _fields_ tuple (index %zd) must be a C type",
i);
return -1;
}
element_types[element_index++] = &structs[struct_index];
structs[struct_index].size = length * edict->ffi_type_pointer.size;
structs[struct_index].alignment = edict->ffi_type_pointer.alignment;
structs[struct_index].type = FFI_TYPE_STRUCT;
structs[struct_index].elements = &dummy_types[dummy_index];
++struct_index;
/* Copy over the element's type, length times. */
while (length > 0) {
assert(dummy_index < (num_ffi_type_pointers));
dummy_types[dummy_index++] = &edict->ffi_type_pointer;
length--;
}
assert(dummy_index < (num_ffi_type_pointers));
dummy_types[dummy_index++] = NULL;
}
Py_DECREF(pair);
}
element_types[element_index] = NULL;
/*
* Replace the old elements with the new, taking into account
* base class elements where necessary.
*/
assert(stgdict->ffi_type_pointer.elements);
PyMem_Free(stgdict->ffi_type_pointer.elements);
stgdict->ffi_type_pointer.elements = element_types;
}
/* We did check that this flag was NOT set above, it must not
have been set until now. */
if (stgdict->flags & DICTFLAG_FINAL) {
PyErr_SetString(PyExc_AttributeError,
"Structure or union cannot contain itself");
return -1;
}
stgdict->flags |= DICTFLAG_FINAL;
return MakeAnonFields(type);
}