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@benjaminp @ZackerySpytz @jdemeyer @mdickinson @abalkin
324 lines (254 sloc) 7.27 KB
/* Wrap void * pointers to be passed between C modules */
#include "Python.h"
/* Internal structure of PyCapsule */
typedef struct {
PyObject_HEAD
void *pointer;
const char *name;
void *context;
PyCapsule_Destructor destructor;
} PyCapsule;
static int
_is_legal_capsule(PyCapsule *capsule, const char *invalid_capsule)
{
if (!capsule || !PyCapsule_CheckExact(capsule) || capsule->pointer == NULL) {
PyErr_SetString(PyExc_ValueError, invalid_capsule);
return 0;
}
return 1;
}
#define is_legal_capsule(capsule, name) \
(_is_legal_capsule(capsule, \
name " called with invalid PyCapsule object"))
static int
name_matches(const char *name1, const char *name2) {
/* if either is NULL, */
if (!name1 || !name2) {
/* they're only the same if they're both NULL. */
return name1 == name2;
}
return !strcmp(name1, name2);
}
PyObject *
PyCapsule_New(void *pointer, const char *name, PyCapsule_Destructor destructor)
{
PyCapsule *capsule;
if (!pointer) {
PyErr_SetString(PyExc_ValueError, "PyCapsule_New called with null pointer");
return NULL;
}
capsule = PyObject_NEW(PyCapsule, &PyCapsule_Type);
if (capsule == NULL) {
return NULL;
}
capsule->pointer = pointer;
capsule->name = name;
capsule->context = NULL;
capsule->destructor = destructor;
return (PyObject *)capsule;
}
int
PyCapsule_IsValid(PyObject *o, const char *name)
{
PyCapsule *capsule = (PyCapsule *)o;
return (capsule != NULL &&
PyCapsule_CheckExact(capsule) &&
capsule->pointer != NULL &&
name_matches(capsule->name, name));
}
void *
PyCapsule_GetPointer(PyObject *o, const char *name)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_GetPointer")) {
return NULL;
}
if (!name_matches(name, capsule->name)) {
PyErr_SetString(PyExc_ValueError, "PyCapsule_GetPointer called with incorrect name");
return NULL;
}
return capsule->pointer;
}
const char *
PyCapsule_GetName(PyObject *o)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_GetName")) {
return NULL;
}
return capsule->name;
}
PyCapsule_Destructor
PyCapsule_GetDestructor(PyObject *o)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_GetDestructor")) {
return NULL;
}
return capsule->destructor;
}
void *
PyCapsule_GetContext(PyObject *o)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_GetContext")) {
return NULL;
}
return capsule->context;
}
int
PyCapsule_SetPointer(PyObject *o, void *pointer)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!pointer) {
PyErr_SetString(PyExc_ValueError, "PyCapsule_SetPointer called with null pointer");
return -1;
}
if (!is_legal_capsule(capsule, "PyCapsule_SetPointer")) {
return -1;
}
capsule->pointer = pointer;
return 0;
}
int
PyCapsule_SetName(PyObject *o, const char *name)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_SetName")) {
return -1;
}
capsule->name = name;
return 0;
}
int
PyCapsule_SetDestructor(PyObject *o, PyCapsule_Destructor destructor)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_SetDestructor")) {
return -1;
}
capsule->destructor = destructor;
return 0;
}
int
PyCapsule_SetContext(PyObject *o, void *context)
{
PyCapsule *capsule = (PyCapsule *)o;
if (!is_legal_capsule(capsule, "PyCapsule_SetContext")) {
return -1;
}
capsule->context = context;
return 0;
}
void *
PyCapsule_Import(const char *name, int no_block)
{
PyObject *object = NULL;
void *return_value = NULL;
char *trace;
size_t name_length = (strlen(name) + 1) * sizeof(char);
char *name_dup = (char *)PyMem_MALLOC(name_length);
if (!name_dup) {
return PyErr_NoMemory();
}
memcpy(name_dup, name, name_length);
trace = name_dup;
while (trace) {
char *dot = strchr(trace, '.');
if (dot) {
*dot++ = '\0';
}
if (object == NULL) {
if (no_block) {
object = PyImport_ImportModuleNoBlock(trace);
} else {
object = PyImport_ImportModule(trace);
if (!object) {
PyErr_Format(PyExc_ImportError, "PyCapsule_Import could not import module \"%s\"", trace);
}
}
} else {
PyObject *object2 = PyObject_GetAttrString(object, trace);
Py_DECREF(object);
object = object2;
}
if (!object) {
goto EXIT;
}
trace = dot;
}
/* compare attribute name to module.name by hand */
if (PyCapsule_IsValid(object, name)) {
PyCapsule *capsule = (PyCapsule *)object;
return_value = capsule->pointer;
} else {
PyErr_Format(PyExc_AttributeError,
"PyCapsule_Import \"%s\" is not valid",
name);
}
EXIT:
Py_XDECREF(object);
if (name_dup) {
PyMem_FREE(name_dup);
}
return return_value;
}
static void
capsule_dealloc(PyObject *o)
{
PyCapsule *capsule = (PyCapsule *)o;
if (capsule->destructor) {
capsule->destructor(o);
}
PyObject_DEL(o);
}
static PyObject *
capsule_repr(PyObject *o)
{
PyCapsule *capsule = (PyCapsule *)o;
const char *name;
const char *quote;
if (capsule->name) {
quote = "\"";
name = capsule->name;
} else {
quote = "";
name = "NULL";
}
return PyUnicode_FromFormat("<capsule object %s%s%s at %p>",
quote, name, quote, capsule);
}
PyDoc_STRVAR(PyCapsule_Type__doc__,
"Capsule objects let you wrap a C \"void *\" pointer in a Python\n\
object. They're a way of passing data through the Python interpreter\n\
without creating your own custom type.\n\
\n\
Capsules are used for communication between extension modules.\n\
They provide a way for an extension module to export a C interface\n\
to other extension modules, so that extension modules can use the\n\
Python import mechanism to link to one another.\n\
");
PyTypeObject PyCapsule_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"PyCapsule", /*tp_name*/
sizeof(PyCapsule), /*tp_basicsize*/
0, /*tp_itemsize*/
/* methods */
capsule_dealloc, /*tp_dealloc*/
0, /*tp_vectorcall_offset*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_as_async*/
capsule_repr, /*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*/
0, /*tp_flags*/
PyCapsule_Type__doc__ /*tp_doc*/
};
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