1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
/* 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;
/* (char *) because Python2.4 defines this as (char *) rather than
* (const char *)
*/
d = PyObject_GetAttrString(module, (char *)_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, (char *)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((char *)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_
|
