diff options
| -rw-r--r-- | numpy/core/_dtype_ctypes.py | 68 | ||||
| -rw-r--r-- | numpy/core/src/multiarray/descriptor.c | 124 | ||||
| -rw-r--r-- | numpy/core/src/multiarray/descriptor.h | 2 | ||||
| -rw-r--r-- | numpy/core/src/multiarray/scalarapi.c | 2 | ||||
| -rw-r--r-- | numpy/core/tests/test_dtype.py | 30 |
5 files changed, 157 insertions, 69 deletions
diff --git a/numpy/core/_dtype_ctypes.py b/numpy/core/_dtype_ctypes.py new file mode 100644 index 000000000..f10b4e99f --- /dev/null +++ b/numpy/core/_dtype_ctypes.py @@ -0,0 +1,68 @@ +""" +Conversion from ctypes to dtype. + +In an ideal world, we could acheive this through the PEP3118 buffer protocol, +something like:: + + def dtype_from_ctypes_type(t): + # needed to ensure that the shape of `t` is within memoryview.format + class DummyStruct(ctypes.Structure): + _fields_ = [('a', t)] + + # empty to avoid memory allocation + ctype_0 = (DummyStruct * 0)() + mv = memoryview(ctype_0) + + # convert the struct, and slice back out the field + return _dtype_from_pep3118(mv.format)['a'] + +Unfortunately, this fails because: + +* ctypes cannot handle length-0 arrays with PEP3118 (bpo-32782) +* PEP3118 cannot represent unions, but both numpy and ctypes can +* ctypes cannot handle big-endian structs with PEP3118 (bpo-32780) +""" +import _ctypes +import ctypes + +import numpy as np + + +def _from_ctypes_array(t): + return np.dtype((dtype_from_ctypes_type(t._type_), (t._length_,))) + + +def _from_ctypes_structure(t): + # TODO: gh-10533, gh-10532 + fields = [] + for item in t._fields_: + if len(item) > 2: + raise TypeError( + "ctypes bitfields have no dtype equivalent") + fname, ftyp = item + fields.append((fname, dtype_from_ctypes_type(ftyp))) + + # by default, ctypes structs are aligned + return np.dtype(fields, align=True) + + +def dtype_from_ctypes_type(t): + """ + Construct a dtype object from a ctypes type + """ + if issubclass(t, _ctypes.Array): + return _from_ctypes_array(t) + elif issubclass(t, _ctypes._Pointer): + raise TypeError("ctypes pointers have no dtype equivalent") + elif issubclass(t, _ctypes.Structure): + return _from_ctypes_structure(t) + elif issubclass(t, _ctypes.Union): + # TODO + raise NotImplementedError( + "conversion from ctypes.Union types like {} to dtype" + .format(t.__name__)) + elif isinstance(t._type_, str): + return np.dtype(t._type_) + else: + raise NotImplementedError( + "Unknown ctypes type {}".format(t.__name__)) diff --git a/numpy/core/src/multiarray/descriptor.c b/numpy/core/src/multiarray/descriptor.c index 439980877..7acac8059 100644 --- a/numpy/core/src/multiarray/descriptor.c +++ b/numpy/core/src/multiarray/descriptor.c @@ -10,7 +10,7 @@ #include "numpy/arrayscalars.h" #include "npy_config.h" - +#include "npy_ctypes.h" #include "npy_pycompat.h" #include "_datetime.h" @@ -54,79 +54,46 @@ Borrowed_PyMapping_GetItemString(PyObject *o, char *key) return ret; } -/* - * Creates a dtype object from ctypes inputs. - * - * Returns a new reference to a dtype object, or NULL - * if this is not possible. When it returns NULL, it does - * not set a Python exception. - */ static PyArray_Descr * -_arraydescr_fromctypes(PyObject *obj) +_arraydescr_from_ctypes_type(PyTypeObject *type) { - PyObject *dtypedescr; - PyArray_Descr *newdescr; - int ret; + PyObject *_numpy_dtype_ctypes; + PyObject *res; - /* Understand basic ctypes */ - dtypedescr = PyObject_GetAttrString(obj, "_type_"); - PyErr_Clear(); - if (dtypedescr) { - ret = PyArray_DescrConverter(dtypedescr, &newdescr); - Py_DECREF(dtypedescr); - if (ret == NPY_SUCCEED) { - PyObject *length; - /* Check for ctypes arrays */ - length = PyObject_GetAttrString(obj, "_length_"); - PyErr_Clear(); - if (length) { - /* derived type */ - PyObject *newtup; - PyArray_Descr *derived; - newtup = Py_BuildValue("N(N)", newdescr, length); - ret = PyArray_DescrConverter(newtup, &derived); - Py_DECREF(newtup); - if (ret == NPY_SUCCEED) { - return derived; - } - PyErr_Clear(); - return NULL; - } - return newdescr; - } - PyErr_Clear(); + /* Call the python function of the same name. */ + _numpy_dtype_ctypes = PyImport_ImportModule("numpy.core._dtype_ctypes"); + if (_numpy_dtype_ctypes == NULL) { return NULL; } - /* Understand ctypes structures -- - bit-fields are not supported - automatically aligns */ - dtypedescr = PyObject_GetAttrString(obj, "_fields_"); - PyErr_Clear(); - if (dtypedescr) { - ret = PyArray_DescrAlignConverter(dtypedescr, &newdescr); - Py_DECREF(dtypedescr); - if (ret == NPY_SUCCEED) { - return newdescr; - } - PyErr_Clear(); + res = PyObject_CallMethod(_numpy_dtype_ctypes, "dtype_from_ctypes_type", "O", (PyObject *)type); + Py_DECREF(_numpy_dtype_ctypes); + if (res == NULL) { + return NULL; } - return NULL; + /* + * sanity check that dtype_from_ctypes_type returned the right type, + * since getting it wrong would give segfaults. + */ + if (!PyObject_TypeCheck(res, &PyArrayDescr_Type)) { + Py_DECREF(res); + PyErr_BadInternalCall(); + return NULL; + } + + return (PyArray_Descr *)res; } /* - * This function creates a dtype object when: - * - The object has a "dtype" attribute, and it can be converted - * to a dtype object. - * - The object is a ctypes type object, including array - * and structure types. + * This function creates a dtype object when the object has a "dtype" attribute, + * and it can be converted to a dtype object. * * Returns a new reference to a dtype object, or NULL * if this is not possible. When it returns NULL, it does * not set a Python exception. */ NPY_NO_EXPORT PyArray_Descr * -_arraydescr_fromobj(PyObject *obj) +_arraydescr_from_dtype_attr(PyObject *obj) { PyObject *dtypedescr; PyArray_Descr *newdescr = NULL; @@ -135,15 +102,18 @@ _arraydescr_fromobj(PyObject *obj) /* For arbitrary objects that have a "dtype" attribute */ dtypedescr = PyObject_GetAttrString(obj, "dtype"); PyErr_Clear(); - if (dtypedescr != NULL) { - ret = PyArray_DescrConverter(dtypedescr, &newdescr); - Py_DECREF(dtypedescr); - if (ret == NPY_SUCCEED) { - return newdescr; - } + if (dtypedescr == NULL) { + return NULL; + } + + ret = PyArray_DescrConverter(dtypedescr, &newdescr); + Py_DECREF(dtypedescr); + if (ret != NPY_SUCCEED) { PyErr_Clear(); + return NULL; } - return _arraydescr_fromctypes(obj); + + return newdescr; } /* @@ -1423,10 +1393,20 @@ PyArray_DescrConverter(PyObject *obj, PyArray_Descr **at) check_num = NPY_VOID; } else { - *at = _arraydescr_fromobj(obj); + *at = _arraydescr_from_dtype_attr(obj); if (*at) { return NPY_SUCCEED; } + + /* + * Note: this comes after _arraydescr_from_dtype_attr because the ctypes + * type might override the dtype if numpy does not otherwise + * support it. + */ + if (npy_ctypes_check((PyTypeObject *)obj)) { + *at = _arraydescr_from_ctypes_type((PyTypeObject *)obj); + return *at ? NPY_SUCCEED : NPY_FAIL; + } } goto finish; } @@ -1596,13 +1576,23 @@ PyArray_DescrConverter(PyObject *obj, PyArray_Descr **at) goto fail; } else { - *at = _arraydescr_fromobj(obj); + *at = _arraydescr_from_dtype_attr(obj); if (*at) { return NPY_SUCCEED; } if (PyErr_Occurred()) { return NPY_FAIL; } + + /* + * Note: this comes after _arraydescr_from_dtype_attr because the ctypes + * type might override the dtype if numpy does not otherwise + * support it. + */ + if (npy_ctypes_check(Py_TYPE(obj))) { + *at = _arraydescr_from_ctypes_type(Py_TYPE(obj)); + return *at ? NPY_SUCCEED : NPY_FAIL; + } goto fail; } if (PyErr_Occurred()) { diff --git a/numpy/core/src/multiarray/descriptor.h b/numpy/core/src/multiarray/descriptor.h index 5a3e4b15f..a5f3b8cdf 100644 --- a/numpy/core/src/multiarray/descriptor.h +++ b/numpy/core/src/multiarray/descriptor.h @@ -8,7 +8,7 @@ NPY_NO_EXPORT PyObject * array_set_typeDict(PyObject *NPY_UNUSED(ignored), PyObject *args); NPY_NO_EXPORT PyArray_Descr * -_arraydescr_fromobj(PyObject *obj); +_arraydescr_from_dtype_attr(PyObject *obj); NPY_NO_EXPORT int diff --git a/numpy/core/src/multiarray/scalarapi.c b/numpy/core/src/multiarray/scalarapi.c index 5ef6c0bbf..bc435d1ca 100644 --- a/numpy/core/src/multiarray/scalarapi.c +++ b/numpy/core/src/multiarray/scalarapi.c @@ -471,7 +471,7 @@ PyArray_DescrFromTypeObject(PyObject *type) /* Do special thing for VOID sub-types */ if (PyType_IsSubtype((PyTypeObject *)type, &PyVoidArrType_Type)) { new = PyArray_DescrNewFromType(NPY_VOID); - conv = _arraydescr_fromobj(type); + conv = _arraydescr_from_dtype_attr(type); if (conv) { new->fields = conv->fields; Py_INCREF(new->fields); diff --git a/numpy/core/tests/test_dtype.py b/numpy/core/tests/test_dtype.py index dbed07466..ecb51f72d 100644 --- a/numpy/core/tests/test_dtype.py +++ b/numpy/core/tests/test_dtype.py @@ -794,6 +794,36 @@ class TestFromCTypes(object): ], align=True) self.check(PaddedStruct, expected) + def test_bit_fields(self): + class BitfieldStruct(ctypes.Structure): + _fields_ = [ + ('a', ctypes.c_uint8, 7), + ('b', ctypes.c_uint8, 1) + ] + assert_raises(TypeError, np.dtype, BitfieldStruct) + assert_raises(TypeError, np.dtype, BitfieldStruct()) + + def test_pointer(self): + p_uint8 = ctypes.POINTER(ctypes.c_uint8) + assert_raises(TypeError, np.dtype, p_uint8) + + @pytest.mark.xfail( + reason="Unions are not implemented", + raises=NotImplementedError) + def test_union(self): + class Union(ctypes.Union): + _fields_ = [ + ('a', ctypes.c_uint8), + ('b', ctypes.c_uint16), + ] + expected = np.dtype(dict( + names=['a', 'b'], + formats=[np.uint8, np.uint16], + offsets=[0, 0], + itemsize=2 + )) + self.check(Union, expected) + @pytest.mark.xfail(reason="_pack_ is ignored - see gh-11651") def test_packed_structure(self): class PackedStructure(ctypes.Structure): |