Fix Python 3 using example at http://wiki.python.org/moin/PortingExtensionModulesToPy3k

diff --git a/python/py_magic.c b/python/py_magic.c
index 65fc758d3a3a9e7eb4eb715971e3bfe59c344691..ff0a1faf63f7f846d04c465867049bd7358d872a 100644 (file)
--- a/python/py_magic.c
+++ b/python/py_magic.c
@@ -27,6 +27,10 @@
    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    SUCH DAMAGE.
 */
+
+/* The initialisation code was rewritten for Python 2 & 3 compatibility, based on that at
+   http://wiki.python.org/moin/PortingExtensionModulesToPy3k */
+
 #include <Python.h>
 #include <magic.h>
 
@@ -107,8 +111,27 @@ static PyMethodDef magic_cookie_hnd_methods[] = {
 
 /* module level methods */
 
+struct module_state {
+       PyObject *error;
+};
+
+#if PY_MAJOR_VERSION >= 3
+#define GETSTATE(m) ((struct module_state*)PyModule_GetState(m))
+#else
+#define GETSTATE(m) (&_state)
+static struct module_state _state;
+#endif
+
+static PyObject *
+error_out(PyObject *m) {
+       struct module_state *st = GETSTATE(m);
+       PyErr_SetString(st->error, "something bad happened");
+       return NULL;
+}
+
 static PyMethodDef magic_methods[] = {
        { "open",     py_magic_open,     METH_VARARGS, _magic_open__doc__     },
+       { "error_out", error_out,        METH_NOARGS,  NULL                   },
        { NULL,       NULL,              0,            NULL                   }
 };
 
@@ -392,35 +415,63 @@ const_init(PyObject *dict)
  * Module initialization
  */
 
-#ifndef PyMODINIT_FUNC
-#define PyMODINIT_FUNC void
-#endif
-
-PyMODINIT_FUNC
 #if PY_MAJOR_VERSION >= 3
+
+static int magic_traverse(PyObject *m, visitproc visit, void *arg) {
+       Py_VISIT(GETSTATE(m)->error);
+       return 0;
+}
+
+static int magic_clear(PyObject *m) {
+       Py_CLEAR(GETSTATE(m)->error);
+       return 0;
+}
+
+static struct PyModuleDef moduledef = {
+       PyModuleDef_HEAD_INIT,
+       "magic",
+       NULL,
+       sizeof(struct module_state),
+       magic_methods,
+       NULL,
+       magic_traverse,
+       magic_clear,
+       NULL
+};
+
+#define INITERROR return NULL
+
+PyObject *
 PyInit_magic(void)
+
 #else
+#define INITERROR return
+
+void
 initmagic(void)
 #endif
 {
+       PyObject *dict;
 #if PY_MAJOR_VERSION >= 3
-       PyModuleDef modDef = {
-               PyModuleDef_HEAD_INIT,
-               "magic",                /* name */
-               "File magic module",    /* module doc */
-               -1,                     /* size of per-interpreter state of mod
-                                        * or -1 if the module keeps stat in
-                                        * global vars
-                                        */
-               magic_methods
-       };
-
-       PyObject *module = PyModule_Create(&modDef);
+       PyObject *module = PyModule_Create(&moduledef);
+#else
+       PyObject *module = Py_InitModule4("magic", magic_methods,
+                                         "File magic module", (PyObject*)0, PYTHON_API_VERSION);
+#endif
+
        if (module == NULL)
-           Py_FatalError("module error");
-       PyObject *dict = PyModule_GetDict(module);
+               INITERROR;
+       struct module_state *st = GETSTATE(module);
+
+       dict = PyModule_GetDict(module);
        if (dict == NULL)
-           Py_FatalError("dict error");
+               Py_FatalError("dict error");
+
+       st->error = PyErr_NewException("magic.Error", NULL, NULL);
+       if (st->error == NULL) {
+               Py_DECREF(module);
+               INITERROR;
+       }
 
        magic_error_obj = PyErr_NewException("magic.error", 0, 0);
        PyDict_SetItemString(dict, "error", magic_error_obj);
@@ -432,20 +483,7 @@ initmagic(void)
        if (PyErr_Occurred())
                Py_FatalError("can't initialize module magic");
 
+#if PY_MAJOR_VERSION >= 3
        return module;
-#else
-       PyObject *module = Py_InitModule4("magic", magic_methods,
-           "File magic module", (PyObject*)0, PYTHON_API_VERSION);
-       PyObject *dict = PyModule_GetDict(module);
-
-       magic_error_obj = PyErr_NewException("magic.error", 0, 0);
-       PyDict_SetItemString(dict, "error", magic_error_obj);
-
-       /* Initialize constants */
-
-       const_init(dict);
-
-       if (PyErr_Occurred())
-               Py_FatalError("can't initialize module magic");
 #endif
 }