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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_free_stginfo_members(dst_info);

memcpy(dst_info, src_info, sizeof(StgInfo));

#ifdef Py_GIL_DISABLED

dst_info->mutex = (PyMutex){0};

#endif

dst_info->dict_final = 0;

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);

dst_info->pointer_type = NULL; // the cache cannot be shared

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->byte_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->byte_size = fdescr->byte_size;

new_descr->byte_offset = fdescr->byte_offset + offset;

new_descr->bitfield_size = fdescr->bitfield_size;

new_descr->bit_offset = fdescr->bit_offset;

new_descr->index = fdescr->index + index;

new_descr->proto = Py_XNewRef(fdescr->proto);

new_descr->getfunc = fdescr->getfunc;

new_descr->setfunc = fdescr->setfunc;

new_descr->name = Py_NewRef(fdescr->name);

new_descr->anonymous = fdescr->anonymous;

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)->byte_offset)) {

Py_DECREF(descr);

Py_DECREF(anon_names);

return -1;

}

Py_DECREF(descr);

}

Py_DECREF(anon_names);

return 0;

}

int

_replace_array_elements(ctypes_state *st, PyObject *layout_fields,

Py_ssize_t ffi_ofs, StgInfo *baseinfo, StgInfo *stginfo);

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 ffi_ofs;

int arrays_seen = 0;

int retval = -1;

// The following are NULL or hold strong references.

// They're cleared on error.

PyObject *layout_func = NULL;

PyObject *kwnames = NULL;

PyObject *align_obj = NULL;

PyObject *size_obj = NULL;

PyObject *layout_fields_obj = NULL;

PyObject *layout_fields = NULL;

PyObject *layout = NULL;

PyObject *format_spec_obj = NULL;

if (fields == NULL) {

return 0;

}

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;

}

PyObject *base = (PyObject *)((PyTypeObject *)type)->tp_base;

StgInfo *baseinfo;

if (PyStgInfo_FromType(st, base, &baseinfo) < 0) {

return -1;

}

STGINFO_LOCK(stginfo);

/* If this structure/union is already marked final we cannot assign

_fields_ anymore. */

if (stginfo_get_dict_final(stginfo) == 1) {/* is final ? */

PyErr_SetString(PyExc_AttributeError,

"_fields_ is final");

goto error;

}

layout_func = PyImport_ImportModuleAttrString("ctypes._layout", "get_layout");

if (!layout_func) {

goto error;

}

kwnames = PyTuple_Pack(

&_Py_ID(is_struct),

&_Py_ID(base));

if (!kwnames) {

goto error;

}

layout = PyObject_Vectorcall(

layout_func,

1 + (PyObject*[]){

NULL,

/* positional args */

type,

fields,

/* keyword args */

isStruct ? Py_True : Py_False,

baseinfo ? base : Py_None},

2 | PY_VECTORCALL_ARGUMENTS_OFFSET,

kwnames);

Py_CLEAR(kwnames);

Py_CLEAR(layout_func);

fields = NULL; // a borrowed reference we won't be using again

if (!layout) {

goto error;

}

align_obj = PyObject_GetAttr(layout, &_Py_ID(align));

if (!align_obj) {

goto error;

}

Py_ssize_t total_align = PyLong_AsSsize_t(align_obj);

Py_CLEAR(align_obj);

if (total_align < 0) {

if (!PyErr_Occurred()) {

PyErr_SetString(PyExc_ValueError,

"align must be a non-negative integer");

}

goto error;

}

size_obj = PyObject_GetAttr(layout, &_Py_ID(size));

if (!size_obj) {

goto error;

}

Py_ssize_t total_size = PyLong_AsSsize_t(size_obj);

Py_CLEAR(size_obj);

if (total_size < 0) {

if (!PyErr_Occurred()) {

PyErr_SetString(PyExc_ValueError,

"size must be a non-negative integer");

}

goto error;

}

format_spec_obj = PyObject_GetAttr(layout, &_Py_ID(format_spec));

if (!format_spec_obj) {

goto error;

}

Py_ssize_t format_spec_size;

const char *format_spec = PyUnicode_AsUTF8AndSize(format_spec_obj,

&format_spec_size);

if (!format_spec) {

goto error;

}

if (stginfo->format) {

PyMem_Free(stginfo->format);

stginfo->format = NULL;

}

stginfo->format = PyMem_Malloc(format_spec_size + 1);

if (!stginfo->format) {

PyErr_NoMemory();

goto error;

}

memcpy(stginfo->format, format_spec, format_spec_size + 1);

layout_fields_obj = PyObject_GetAttr(layout, &_Py_ID(fields));

if (!layout_fields_obj) {

goto error;

}

layout_fields = PySequence_Tuple(layout_fields_obj);

if (!layout_fields) {

goto error;

}

Py_CLEAR(layout_fields_obj);

Py_CLEAR(layout);

Py_ssize_t len = PyTuple_GET_SIZE(layout_fields);

if (stginfo->ffi_type_pointer.elements) {

PyMem_Free(stginfo->ffi_type_pointer.elements);

stginfo->ffi_type_pointer.elements = NULL;

}

if (baseinfo) {

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();

goto error;

}

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 {

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();

goto error;

}

memset(stginfo->ffi_type_pointer.elements, 0,

sizeof(ffi_type *) * (len + 1));

ffi_ofs = 0;

}

for (Py_ssize_t i = 0; i < len; ++i) {

PyObject *prop_obj = PyTuple_GET_ITEM(layout_fields, i);

assert(prop_obj);

if (!PyType_IsSubtype(Py_TYPE(prop_obj), st->PyCField_Type)) {

PyErr_Format(PyExc_TypeError,

"fields must be of type CField, got %T", prop_obj);

goto error;

}

CFieldObject *prop = (CFieldObject *)prop_obj; // borrow from prop_obj

if (prop->index != i) {

PyErr_Format(PyExc_ValueError,

"field %R index mismatch (expected %zd, got %zd)",

prop->name, i, prop->index);

goto error;

}

if (PyCArrayTypeObject_Check(st, prop->proto)) {

arrays_seen = 1;

}

StgInfo *info;

if (PyStgInfo_FromType(st, prop->proto, &info) < 0) {

goto error;

}

assert(info);

STGINFO_LOCK(info);

stginfo->ffi_type_pointer.elements[ffi_ofs + i] = &info->ffi_type_pointer;

if (info->flags & (TYPEFLAG_ISPOINTER | TYPEFLAG_HASPOINTER))

stginfo->flags |= TYPEFLAG_HASPOINTER;

stginfo_set_dict_final_lock_held(info); /* mark field type final */

STGINFO_UNLOCK();

if (-1 == PyObject_SetAttr(type, prop->name, prop_obj)) {

goto error;

}

stginfo->ffi_type_pointer.alignment = Py_SAFE_DOWNCAST(total_align,

Py_ssize_t,

unsigned short);

stginfo->ffi_type_pointer.size = total_size;

stginfo->size = total_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) || defined(__sparc__)

# define MAX_STRUCT_SIZE 32

#elif defined(__powerpc64__)

# define MAX_STRUCT_SIZE 64

#else

# define MAX_STRUCT_SIZE 16

#endif

if (arrays_seen && (total_size <= MAX_STRUCT_SIZE)) {

if (_replace_array_elements(st, layout_fields, ffi_ofs, baseinfo, stginfo) < 0) {

goto error;

}

/* We did check that this flag was NOT set above, it must not

have been set until now. */

if (stginfo_get_dict_final(stginfo) == 1) {

PyErr_SetString(PyExc_AttributeError,

"Structure or union cannot contain itself");

goto error;

}

stginfo_set_dict_final_lock_held(stginfo);

retval = MakeAnonFields(type);

error:;

Py_XDECREF(layout_func);

Py_XDECREF(kwnames);

Py_XDECREF(align_obj);

Py_XDECREF(size_obj);

Py_XDECREF(layout_fields_obj);

Py_XDECREF(layout_fields);

Py_XDECREF(layout);

Py_XDECREF(format_spec_obj);

STGINFO_UNLOCK();

return retval;

}

Replace array elements at stginfo->ffi_type_pointer.elements.

Return -1 if error occurred.

int

_replace_array_elements(ctypes_state *st, PyObject *layout_fields,

Py_ssize_t ffi_ofs, StgInfo *baseinfo, StgInfo *stginfo)

{

* 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 = NULL; /* 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 */

Py_ssize_t len = PyTuple_GET_SIZE(layout_fields);

/* first pass to see how much memory to allocate */

for (Py_ssize_t i = 0; i < len; ++i) {

PyObject *prop_obj = PyTuple_GET_ITEM(layout_fields, i); // borrowed

assert(prop_obj);

assert(PyType_IsSubtype(Py_TYPE(prop_obj), st->PyCField_Type));

CFieldObject *prop = (CFieldObject *)prop_obj; // borrowed

StgInfo *info;

if (PyStgInfo_FromType(st, prop->proto, &info) < 0) {

goto error;

}

assert(info);

if (!PyCArrayTypeObject_Check(st, prop->proto)) {

/* 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) {

goto error;

}

if (einfo == NULL) {

PyErr_Format(PyExc_TypeError,

"second item in _fields_ tuple (index %zd) must be a C type",

i);

goto error;

}

* 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;

}

* 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();

goto error;

}

* 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 (Py_ssize_t i = 0; i < len; ++i) {

PyObject *prop_obj = PyTuple_GET_ITEM(layout_fields, i); // borrowed

assert(prop_obj);

assert(PyType_IsSubtype(Py_TYPE(prop_obj), st->PyCField_Type));

CFieldObject *prop = (CFieldObject *)prop_obj; // borrowed

StgInfo *info;

if (PyStgInfo_FromType(st, prop->proto, &info) < 0) {

goto error;

}

assert(info);

assert(element_index < (ffi_ofs + len)); /* will be used below */

if (!PyCArrayTypeObject_Check(st, prop->proto)) {

/* 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) {

goto error;

}

if (einfo == NULL) {

PyErr_Format(PyExc_TypeError,

"second item in _fields_ tuple (index %zd) must be a C type",

i);

goto error;

}

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;

}

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;

return 0;

error:

PyMem_Free(type_block);

return -1;

}

cpython/Modules/_ctypes/stgdict.c at main · python/cpython · GitHub

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