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/* Copyright (C) 2009 Canonical Ltd
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _IMPORT_C_API_H_
#define _IMPORT_C_API_H_
/**
* Helper functions to eliminate some of the boilerplate when importing a C API
* from a CPython extension module.
*
* For more information see _export_c_api.h
*/
static const char *_C_API_NAME = "_C_API";
/**
* Import a function from the _C_API_NAME dict that is part of module.
*
* @param module The Python module we are importing from
* the attribute _C_API_NAME will be used as a dictionary
* containing the function pointer we are looking for.
* @param funcname Name of the function we want to import
* @param func A pointer to the function handle where we will store the
* function.
* @param signature The C signature of the function. This is validated
* against the signature stored in the C api, to make sure
* there is no versioning skew.
*/
static int _import_function(PyObject *module, const char *funcname,
void **func, const char *signature)
{
PyObject *d = NULL;
PyObject *c_obj = NULL;
const char *desc = NULL;
d = PyObject_GetAttrString(module, _C_API_NAME);
if (!d) {
// PyObject_GetAttrString sets an appropriate exception
goto bad;
}
c_obj = PyDict_GetItemString(d, funcname);
if (!c_obj) {
// PyDict_GetItemString does not set an exception
PyErr_Format(PyExc_AttributeError,
"Module %s did not export a function named %s\n",
PyModule_GetName(module), funcname);
goto bad;
}
desc = (char *)PyCObject_GetDesc(c_obj);
if (!desc || strcmp(desc, signature) != 0) {
if (desc == NULL) {
desc = "<null>";
}
PyErr_Format(PyExc_TypeError,
"C function %s.%s has wrong signature (expected %s, got %s)",
PyModule_GetName(module), funcname, signature, desc);
goto bad;
}
*func = PyCObject_AsVoidPtr(c_obj);
Py_DECREF(d);
return 0;
bad:
Py_XDECREF(d);
return -1;
}
/**
* Get a pointer to an exported PyTypeObject.
*
* @param module The Python module we are importing from
* @param class_name Attribute of the module that should reference the
* Type object. Note that a PyTypeObject is the python
* description of the type, not the raw C structure.
* @return A Pointer to the requested type object. On error NULL will be
* returned and an exception will be set.
*/
static PyTypeObject *
_import_type(PyObject *module, const char *class_name)
{
PyObject *type = NULL;
type = PyObject_GetAttrString(module, class_name);
if (!type) {
goto bad;
}
if (!PyType_Check(type)) {
PyErr_Format(PyExc_TypeError,
"%s.%s is not a type object",
PyModule_GetName(module), class_name);
goto bad;
}
return (PyTypeObject *)type;
bad:
Py_XDECREF(type);
return NULL;
}
struct function_description
{
const char *name;
void **pointer;
const char *signature;
};
struct type_description
{
const char *name;
PyTypeObject **pointer;
};
/**
* Helper for importing several functions and types in a data-driven manner.
*
* @param module The name of the module we will be importing
* @param functions A list of function_description objects, describing the
* functions being imported.
* The list should be terminated with {NULL} to indicate
* there are no more functions to import.
* @param types A list of type_description objects describing type
* objects that we want to import. The list should be
* terminated with {NULL} to indicate there are no more
* types to import.
* @return 0 on success, -1 on error and an exception should be set.
*/
static int
_import_extension_module(const char *module_name,
struct function_description *functions,
struct type_description *types)
{
PyObject *module = NULL;
struct function_description *cur_func;
struct type_description *cur_type;
int ret_code;
module = PyImport_ImportModule(module_name);
if (!module)
goto bad;
if (functions != NULL) {
cur_func = functions;
while (cur_func->name != NULL) {
ret_code = _import_function(module, cur_func->name,
cur_func->pointer,
cur_func->signature);
if (ret_code < 0)
goto bad;
cur_func++;
}
}
if (types != NULL) {
PyTypeObject *type_p = NULL;
cur_type = types;
while (cur_type->name != NULL) {
type_p = _import_type(module, cur_type->name);
if (type_p == NULL)
goto bad;
*(cur_type->pointer) = type_p;
cur_type++;
}
}
Py_XDECREF(module);
return 0;
bad:
Py_XDECREF(module);
return -1;
}
#endif // _IMPORT_C_API_H_
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