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cpython/Modules/_ctypes/stgdict.c

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#ifndef Py_BUILD_CORE_BUILTIN
# define Py_BUILD_CORE_MODULE 1
#endif
#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 "pycore_dict.h" // _PyDict_SizeOf()
#include <ffi.h>
#ifdef MS_WIN32
# include <malloc.h>
#endif
#include "ctypes.h"
/* This file relates to StgInfo -- type-specific information for ctypes.
* See ctypes.h for details.
*/
int
PyCStgInfo_clone(StgInfo *dst_info, StgInfo *src_info)
{
Py_ssize_t size;
ctype_clear_stginfo(dst_info);
PyMem_Free(dst_info->ffi_type_pointer.elements);
PyMem_Free(dst_info->format);
dst_info->format = NULL;
PyMem_Free(dst_info->shape);
dst_info->shape = NULL;
dst_info->ffi_type_pointer.elements = NULL;
memcpy(dst_info, src_info, sizeof(StgInfo));
Py_XINCREF(dst_info->proto);
Py_XINCREF(dst_info->argtypes);
Py_XINCREF(dst_info->converters);
Py_XINCREF(dst_info->restype);
Py_XINCREF(dst_info->checker);
Py_XINCREF(dst_info->module);
if (src_info->format) {
dst_info->format = PyMem_Malloc(strlen(src_info->format) + 1);
if (dst_info->format == NULL) {
PyErr_NoMemory();
return -1;
}
strcpy(dst_info->format, src_info->format);
}
if (src_info->shape) {
dst_info->shape = PyMem_Malloc(sizeof(Py_ssize_t) * src_info->ndim);
if (dst_info->shape == NULL) {
PyErr_NoMemory();
return -1;
}
memcpy(dst_info->shape, src_info->shape,
sizeof(Py_ssize_t) * src_info->ndim);
}
if (src_info->ffi_type_pointer.elements == NULL)
return 0;
size = sizeof(ffi_type *) * (src_info->length + 1);
dst_info->ffi_type_pointer.elements = PyMem_Malloc(size);
if (dst_info->ffi_type_pointer.elements == NULL) {
PyErr_NoMemory();
return -1;
}
memcpy(dst_info->ffi_type_pointer.elements,
src_info->ffi_type_pointer.elements,
size);
return 0;
}
/* 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;
ctypes_state *st = get_module_state_by_class(Py_TYPE(descr));
PyTypeObject *cfield_tp = st->PyCField_Type;
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, cfield_tp)) {
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 *)cfield_tp->tp_alloc(cfield_tp, 0);
if (new_descr == NULL) {
Py_DECREF(fdescr);
Py_DECREF(fieldlist);
return -1;
}
assert(Py_IS_TYPE(new_descr, cfield_tp));
new_descr->size = fdescr->size;
new_descr->offset = fdescr->offset + offset;
new_descr->index = fdescr->index + index;
new_descr->proto = Py_XNewRef(fdescr->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)
{
PyObject *anon;
PyObject *anon_names;
Py_ssize_t i;
if (PyObject_GetOptionalAttr(type, &_Py_ID(_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;
ctypes_state *st = get_module_state_by_def(Py_TYPE(type));
PyTypeObject *cfield_tp = st->PyCField_Type;
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, cfield_tp)) {
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;
}
/*
Allocate a memory block for a pep3118 format string, copy prefix (if
non-null) into it and append `{padding}x` to the end.
Returns NULL on failure, with the error indicator set.
*/
char *
_ctypes_alloc_format_padding(const char *prefix, Py_ssize_t padding)
{
/* int64 decimal characters + x + null */
char buf[19 + 1 + 1];
assert(padding > 0);
if (padding == 1) {
/* Use x instead of 1x, for brevity */
return _ctypes_alloc_format_string(prefix, "x");
}
int ret = PyOS_snprintf(buf, sizeof(buf), "%zdx", padding); (void)ret;
assert(0 <= ret && ret < (Py_ssize_t)sizeof(buf));
return _ctypes_alloc_format_string(prefix, buf);
}
/*
Retrieve the (optional) _pack_ attribute from a type, the _fields_ attribute,
and initialize StgInfo. Used for Structure and Union subclasses.
*/
int
PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct)
{
Py_ssize_t len, offset, size, align, i;
Py_ssize_t union_size, total_align, aligned_size;
Py_ssize_t field_size = 0;
Py_ssize_t bitofs = 0;
PyObject *tmp;
int pack;
int forced_alignment = 1;
Py_ssize_t ffi_ofs;
int big_endian;
int arrays_seen = 0;
if (fields == NULL)
return 0;
int rc = PyObject_HasAttrWithError(type, &_Py_ID(_swappedbytes_));
if (rc < 0) {
return -1;
}
if (rc) {
big_endian = !PY_BIG_ENDIAN;
}
else {
big_endian = PY_BIG_ENDIAN;
}
if (PyObject_GetOptionalAttr(type, &_Py_ID(_pack_), &tmp) < 0) {
return -1;
}
if (tmp) {
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 {
/* Setting `_pack_ = 0` amounts to using the default alignment */
pack = 0;
}
#ifdef MS_WIN32
LayoutMode layout_mode = LAYOUT_MODE_MS;
#else
LayoutMode layout_mode = (pack > 0) ? LAYOUT_MODE_MS : LAYOUT_MODE_GCC_SYSV;
#endif
if (PyObject_GetOptionalAttr(type, &_Py_ID(_layout_), &tmp) < 0) {
return -1;
}
if (tmp) {
if (!PyUnicode_Check(tmp)) {
PyErr_SetString(PyExc_TypeError,
"_layout_ must be a string");
return -1;
}
if (PyUnicode_CompareWithASCIIString(tmp, "ms") == 0) {
layout_mode = LAYOUT_MODE_MS;
}
else if (PyUnicode_CompareWithASCIIString(tmp, "gcc-sysv") == 0) {
layout_mode = LAYOUT_MODE_GCC_SYSV;
if (pack > 0) {
PyErr_SetString(PyExc_ValueError,
"_pack_ is not compatible with _layout_=\"gcc-sysv\"");
return -1;
}
}
else {
PyErr_Format(PyExc_ValueError,
"unknown _layout_ %R", tmp);
return -1;
}
}
if (PyObject_GetOptionalAttr(type, &_Py_ID(_align_), &tmp) < 0) {
return -1;
}
if (tmp) {
forced_alignment = PyLong_AsInt(tmp);
Py_DECREF(tmp);
if (forced_alignment < 0) {
if (!PyErr_Occurred() ||
PyErr_ExceptionMatches(PyExc_TypeError) ||
PyErr_ExceptionMatches(PyExc_OverflowError))
{
PyErr_SetString(PyExc_ValueError,
"_align_ must be a non-negative integer");
}
return -1;
}
}
else {
/* Setting `_align_ = 0` amounts to using the default alignment */
forced_alignment = 1;
}
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;
}
ctypes_state *st = get_module_state_by_def(Py_TYPE(type));
StgInfo *stginfo;
if (PyStgInfo_FromType(st, type, &stginfo) < 0) {
return -1;
}
if (!stginfo) {
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 (stginfo->flags & DICTFLAG_FINAL) {/* is final ? */
PyErr_SetString(PyExc_AttributeError,
"_fields_ is final");
return -1;
}
if (stginfo->format) {
PyMem_Free(stginfo->format);
stginfo->format = NULL;
}
if (stginfo->ffi_type_pointer.elements)
PyMem_Free(stginfo->ffi_type_pointer.elements);
StgInfo *baseinfo;
if (PyStgInfo_FromType(st, (PyObject *)((PyTypeObject *)type)->tp_base,
&baseinfo) < 0) {
return -1;
}
if (baseinfo) {
stginfo->flags |= (baseinfo->flags &
(TYPEFLAG_HASUNION | TYPEFLAG_HASBITFIELD));
}
if (!isStruct) {
stginfo->flags |= TYPEFLAG_HASUNION;
}
if (baseinfo) {
size = offset = baseinfo->size;
align = baseinfo->align;
union_size = 0;
total_align = align ? align : 1;
total_align = max(total_align, forced_alignment);
stginfo->ffi_type_pointer.type = FFI_TYPE_STRUCT;
stginfo->ffi_type_pointer.elements = PyMem_New(ffi_type *, baseinfo->length + len + 1);
if (stginfo->ffi_type_pointer.elements == NULL) {
PyErr_NoMemory();
return -1;
}
memset(stginfo->ffi_type_pointer.elements, 0,
sizeof(ffi_type *) * (baseinfo->length + len + 1));
if (baseinfo->length > 0) {
memcpy(stginfo->ffi_type_pointer.elements,
baseinfo->ffi_type_pointer.elements,
sizeof(ffi_type *) * (baseinfo->length));
}
ffi_ofs = baseinfo->length;
} else {
offset = 0;
size = 0;
align = 0;
union_size = 0;
total_align = forced_alignment;
stginfo->ffi_type_pointer.type = FFI_TYPE_STRUCT;
stginfo->ffi_type_pointer.elements = PyMem_New(ffi_type *, len + 1);
if (stginfo->ffi_type_pointer.elements == NULL) {
PyErr_NoMemory();
return -1;
}
memset(stginfo->ffi_type_pointer.elements, 0,
sizeof(ffi_type *) * (len + 1));
ffi_ofs = 0;
}
assert(stginfo->format == NULL);
if (isStruct) {
stginfo->format = _ctypes_alloc_format_string(NULL, "T{");
} else {
/* PEP3118 doesn't support union. Use 'B' for bytes. */
stginfo->format = _ctypes_alloc_format_string(NULL, "B");
}
if (stginfo->format == NULL)
return -1;
for (i = 0; i < len; ++i) {
PyObject *name = NULL, *desc = NULL;
PyObject *pair = PySequence_GetItem(fields, i);
PyObject *prop;
Py_ssize_t bitsize = 0;
if (!pair || !PyArg_ParseTuple(pair, "UO|n", &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(st, desc)) {
arrays_seen = 1;
}
StgInfo *info;
if (PyStgInfo_FromType(st, desc, &info) < 0) {
Py_DECREF(pair);
return -1;
}
if (info == NULL) {
Py_DECREF(pair);
PyErr_Format(PyExc_TypeError,
"second item in _fields_ tuple (index %zd) must be a C type",
i);
return -1;
}
stginfo->ffi_type_pointer.elements[ffi_ofs + i] = &info->ffi_type_pointer;
if (info->flags & (TYPEFLAG_ISPOINTER | TYPEFLAG_HASPOINTER))
stginfo->flags |= TYPEFLAG_HASPOINTER;
stginfo->flags |= info->flags & (TYPEFLAG_HASUNION | TYPEFLAG_HASBITFIELD);
info->flags |= DICTFLAG_FINAL; /* mark field type final */
if (PyTuple_Size(pair) == 3) { /* bits specified */
stginfo->flags |= TYPEFLAG_HASBITFIELD;
switch(info->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 (info->getfunc != _ctypes_get_fielddesc("c")->getfunc
&& info->getfunc != _ctypes_get_fielddesc("u")->getfunc)
{
break;
}
_Py_FALLTHROUGH; /* 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 > info->size * 8) {
PyErr_Format(PyExc_ValueError,
"number of bits invalid for bit field %R",
name);
Py_DECREF(pair);
return -1;
}
} else
bitsize = 0;
if (isStruct) {
const char *fieldfmt = info->format ? info->format : "B";
const char *fieldname = PyUnicode_AsUTF8(name);
char *ptr;
Py_ssize_t len;
char *buf;
Py_ssize_t last_size = size;
Py_ssize_t padding;
if (fieldname == NULL)
{
Py_DECREF(pair);
return -1;
}
/* construct the field now, as `prop->offset` is `offset` with
corrected alignment */
prop = PyCField_FromDesc(st, desc, i,
&field_size, bitsize, &bitofs,
&size, &offset, &align,
pack, big_endian, layout_mode);
if (prop == NULL) {
Py_DECREF(pair);
return -1;
}
/* number of bytes between the end of the last field and the start
of this one */
padding = ((CFieldObject *)prop)->offset - last_size;
if (padding > 0) {
ptr = stginfo->format;
stginfo->format = _ctypes_alloc_format_padding(ptr, padding);
PyMem_Free(ptr);
if (stginfo->format == NULL) {
Py_DECREF(pair);
Py_DECREF(prop);
return -1;
}
}
len = strlen(fieldname) + strlen(fieldfmt);
buf = PyMem_Malloc(len + 2 + 1);
if (buf == NULL) {
Py_DECREF(pair);
Py_DECREF(prop);
PyErr_NoMemory();
return -1;
}
sprintf(buf, "%s:%s:", fieldfmt, fieldname);
ptr = stginfo->format;
if (info->shape != NULL) {
stginfo->format = _ctypes_alloc_format_string_with_shape(
info->ndim, info->shape, stginfo->format, buf);
} else {
stginfo->format = _ctypes_alloc_format_string(stginfo->format, buf);
}
PyMem_Free(ptr);
PyMem_Free(buf);
if (stginfo->format == NULL) {
Py_DECREF(pair);
Py_DECREF(prop);
return -1;
}
} else /* union */ {
field_size = 0;
size = 0;
bitofs = 0;
offset = 0;
align = 0;
prop = PyCField_FromDesc(st, desc, i,
&field_size, bitsize, &bitofs,
&size, &offset, &align,
pack, big_endian, layout_mode);
if (prop == NULL) {
Py_DECREF(pair);
return -1;
}
union_size = max(size, union_size);
}
total_align = max(align, total_align);
if (-1 == PyObject_SetAttr(type, name, prop)) {
Py_DECREF(prop);
Py_DECREF(pair);
return -1;
}
Py_DECREF(pair);
Py_DECREF(prop);
}
if (!isStruct) {
size = union_size;
}
/* Adjust the size according to the alignment requirements */
aligned_size = ((size + total_align - 1) / total_align) * total_align;
if (isStruct) {
char *ptr;
Py_ssize_t padding;
/* Pad up to the full size of the struct */
padding = aligned_size - size;
if (padding > 0) {
ptr = stginfo->format;
stginfo->format = _ctypes_alloc_format_padding(ptr, padding);
PyMem_Free(ptr);
if (stginfo->format == NULL) {
return -1;
}
}
ptr = stginfo->format;
stginfo->format = _ctypes_alloc_format_string(stginfo->format, "}");
PyMem_Free(ptr);
if (stginfo->format == NULL)
return -1;
}
stginfo->ffi_type_pointer.alignment = Py_SAFE_DOWNCAST(total_align,
Py_ssize_t,
unsigned short);
stginfo->ffi_type_pointer.size = aligned_size;
stginfo->size = aligned_size;
stginfo->align = total_align;
stginfo->length = ffi_ofs + len;
/*
* The value of MAX_STRUCT_SIZE depends on the platform Python is running on.
*/
#if defined(__aarch64__) || defined(__arm__) || defined(_M_ARM64)
# define MAX_STRUCT_SIZE 32
#elif defined(__powerpc64__)
# define MAX_STRUCT_SIZE 64
#else
# define MAX_STRUCT_SIZE 16
#endif
if (arrays_seen && (size <= MAX_STRUCT_SIZE)) {
/*
* See bpo-22273 and gh-110190. 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.
* 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.
*
* Small structures have different sizes depending on the platform
* where Python is running on:
*
* * x86-64: 16 bytes or less
* * Arm platforms (both 32 and 64 bit): 32 bytes or less
* * PowerPC 64 Little Endian: 64 bytes or less
*
* In that case, there can't be more than 16, 32 or 64 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 the above
* platforms, 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;
* }
*
* The same principle applies for a struct 32 or 64 bytes in size.
*
* 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);
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;
}
StgInfo *info;
if (PyStgInfo_FromType(st, desc, &info) < 0) {
Py_DECREF(pair);
return -1;
}
if (info == 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(st, desc)) {
/* Not an array. Just need an ffi_type pointer. */
num_ffi_type_pointers++;
}
else {
/* It's an array. */
Py_ssize_t length = info->length;
StgInfo *einfo;
if (PyStgInfo_FromType(st, info->proto, &einfo) < 0) {
Py_DECREF(pair);
return -1;
}
if (einfo == 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 && (baseinfo != NULL)) {
memcpy(element_types,
baseinfo->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);
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;
}
StgInfo *info;
if (PyStgInfo_FromType(st, desc, &info) < 0) {
Py_DECREF(pair);
PyMem_Free(type_block);
return -1;
}
/* Possibly this check could be avoided, but see above comment. */
if (info == 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(st, desc)) {
/* Not an array. Just copy over the element ffi_type. */
element_types[element_index++] = &info->ffi_type_pointer;
}
else {
Py_ssize_t length = info->length;
StgInfo *einfo;
if (PyStgInfo_FromType(st, info->proto, &einfo) < 0) {
Py_DECREF(pair);
PyMem_Free(type_block);
return -1;
}
if (einfo == 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 * einfo->ffi_type_pointer.size;
structs[struct_index].alignment = einfo->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++] = &einfo->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(stginfo->ffi_type_pointer.elements);
PyMem_Free(stginfo->ffi_type_pointer.elements);
stginfo->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 (stginfo->flags & DICTFLAG_FINAL) {
PyErr_SetString(PyExc_AttributeError,
"Structure or union cannot contain itself");
return -1;
}
stginfo->flags |= DICTFLAG_FINAL;
return MakeAnonFields(type);
}
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