gi/pygi-signal-closure.c

   1 /* -*- mode: C; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
   2 /*
   3  * Copyright (c) 2011  Laszlo Pandy <lpandy@src.gnome.org>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "pygi-signal-closure.h"
  20 #include "pygi-value.h"
  21 #include "pygi-argument.h"
  22 #include "pygi-boxed.h"
  23
  24 static GISignalInfo *
  25 _pygi_lookup_signal_from_g_type (GType g_type,
  26                                  const gchar *signal_name)
  27 {
  28     GIRepository *repository;
  29     GIBaseInfo *info;
  30     GISignalInfo *signal_info = NULL;
  31
  32     repository = g_irepository_get_default();
  33     info = g_irepository_find_by_gtype (repository, g_type);
  34     if (info == NULL)
  35         return NULL;
  36
  37     if (GI_IS_OBJECT_INFO (info))
  38         signal_info = g_object_info_find_signal ((GIObjectInfo *) info,
  39                                                  signal_name);
  40     else if (GI_IS_INTERFACE_INFO (info))
  41         signal_info = g_interface_info_find_signal ((GIInterfaceInfo *) info,
  42                                                     signal_name);
  43
  44     g_base_info_unref (info);
  45     return signal_info;
  46 }
  47
  48 static void
  49 pygi_signal_closure_invalidate(gpointer data,
  50                                GClosure *closure)
  51 {
  52     PyGClosure *pc = (PyGClosure *)closure;
  53     PyGILState_STATE state;
  54
  55     state = PyGILState_Ensure();
  56     Py_XDECREF(pc->callback);
  57     Py_XDECREF(pc->extra_args);
  58     Py_XDECREF(pc->swap_data);
  59     PyGILState_Release(state);
  60
  61     pc->callback = NULL;
  62     pc->extra_args = NULL;
  63     pc->swap_data = NULL;
  64
  65     g_base_info_unref (((PyGISignalClosure *) pc)->signal_info);
  66     ((PyGISignalClosure *) pc)->signal_info = NULL;
  67 }
  68
  69 static void
  70 pygi_signal_closure_marshal(GClosure *closure,
  71                             GValue *return_value,
  72                             guint n_param_values,
  73                             const GValue *param_values,
  74                             gpointer invocation_hint,
  75                             gpointer marshal_data)
  76 {
  77     PyGILState_STATE state;
  78     PyGClosure *pc = (PyGClosure *)closure;
  79     PyObject *params, *ret = NULL;
  80     guint i;
  81     GISignalInfo *signal_info;
  82     gint n_sig_info_args;
  83     gint sig_info_highest_arg;
  84     GSList *list_item = NULL;
  85     GSList *pass_by_ref_structs = NULL;
  86
  87     state = PyGILState_Ensure();
  88
  89     signal_info = ((PyGISignalClosure *)closure)->signal_info;
  90     n_sig_info_args = g_callable_info_get_n_args(signal_info);
  91     /* the first argument to a signal callback is instance,
  92        but instance is not counted in the introspection data */
  93     sig_info_highest_arg = n_sig_info_args + 1;
  94     g_assert_cmpint(sig_info_highest_arg, ==, n_param_values);
  95
  96     /* construct Python tuple for the parameter values */
  97     params = PyTuple_New(n_param_values);
  98     for (i = 0; i < n_param_values; i++) {
  99         /* swap in a different initial data for connect_object() */
 100         if (i == 0 && G_CCLOSURE_SWAP_DATA(closure)) {
 101             g_return_if_fail(pc->swap_data != NULL);
 102             Py_INCREF(pc->swap_data);
 103             PyTuple_SetItem(params, 0, pc->swap_data);
 104
 105         } else if (i == 0) {
 106             PyObject *item = pyg_value_as_pyobject(&param_values[i], FALSE);
 107
 108             if (!item) {
 109                 goto out;
 110             }
 111             PyTuple_SetItem(params, i, item);
 112
 113         } else if (i < sig_info_highest_arg) {
 114             GIArgInfo arg_info;
 115             GITypeInfo type_info;
 116             GITypeTag type_tag;
 117             GIArgument arg = { 0, };
 118             PyObject *item = NULL;
 119             gboolean free_array = FALSE;
 120             gboolean pass_struct_by_ref = FALSE;
 121
 122             g_callable_info_load_arg(signal_info, i - 1, &arg_info);
 123             g_arg_info_load_type(&arg_info, &type_info);
 124
 125             arg = _pygi_argument_from_g_value(&param_values[i], &type_info);
 126
 127             type_tag = g_type_info_get_tag (&type_info);
 128             if (type_tag == GI_TYPE_TAG_ARRAY) {
 129                 /* Skip the self argument of param_values */
 130                 arg.v_pointer = _pygi_argument_to_array (&arg,
 131                                                          _pygi_argument_array_length_marshal,
 132                                                          (void *)(param_values + 1),
 133                                                          signal_info,
 134                                                          &type_info,
 135                                                          &free_array);
 136             }
 137
 138             /* Hack to ensure struct arguments are passed-by-reference allowing
 139              * callback implementors to modify the struct values. This is needed
 140              * for keeping backwards compatibility and should be removed in future
 141              * versions which support signal output arguments as return values.
 142              * See: https://bugzilla.gnome.org/show_bug.cgi?id=735486
 143              *
 144              * Note the logic here must match the logic path taken in _pygi_argument_to_object.
 145              */
 146             if (type_tag == GI_TYPE_TAG_INTERFACE) {
 147                 GIBaseInfo *info = g_type_info_get_interface (&type_info);
 148                 GIInfoType info_type = g_base_info_get_type (info);
 149
 150                 if (info_type == GI_INFO_TYPE_STRUCT ||
 151                         info_type == GI_INFO_TYPE_BOXED ||
 152                         info_type == GI_INFO_TYPE_UNION) {
 153
 154                     GType gtype = g_registered_type_info_get_g_type ((GIRegisteredTypeInfo *) info);
 155                     gboolean is_foreign = (info_type == GI_INFO_TYPE_STRUCT) &&
 156                                           (g_struct_info_is_foreign ((GIStructInfo *) info));
 157
 158                     if (!is_foreign && !g_type_is_a (gtype, G_TYPE_VALUE) &&
 159                             g_type_is_a (gtype, G_TYPE_BOXED)) {
 160                         pass_struct_by_ref = TRUE;
 161                     }
 162                 }
 163
 164                 g_base_info_unref (info);
 165             }
 166
 167             if (pass_struct_by_ref) {
 168                 /* transfer everything will ensure the struct is not copied when wrapped. */
 169                 item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_EVERYTHING);
 170                 if (item && PyObject_IsInstance (item, (PyObject *) &PyGIBoxed_Type)) {
 171                     ((PyGBoxed *)item)->free_on_dealloc = FALSE;
 172                     pass_by_ref_structs = g_slist_prepend (pass_by_ref_structs, item);
 173                 }
 174
 175             } else {
 176                 item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_NOTHING);
 177             }
 178
 179             if (free_array) {
 180                 g_array_free (arg.v_pointer, FALSE);
 181             }
 182
 183             if (item == NULL) {
 184                 PyErr_Print ();
 185                 goto out;
 186             }
 187             PyTuple_SetItem(params, i, item);
 188         }
 189     }
 190     /* params passed to function may have extra arguments */
 191     if (pc->extra_args) {
 192         PyObject *tuple = params;
 193         params = PySequence_Concat(tuple, pc->extra_args);
 194         Py_DECREF(tuple);
 195     }
 196     ret = PyObject_CallObject(pc->callback, params);
 197     if (ret == NULL) {
 198         if (pc->exception_handler)
 199             pc->exception_handler(return_value, n_param_values, param_values);
 200         else
 201             PyErr_Print();
 202         goto out;
 203     }
 204
 205     if (G_IS_VALUE(return_value) && pyg_value_from_pyobject(return_value, ret) != 0) {
 206         PyErr_SetString(PyExc_TypeError,
 207                         "can't convert return value to desired type");
 208
 209         if (pc->exception_handler)
 210             pc->exception_handler(return_value, n_param_values, param_values);
 211         else
 212             PyErr_Print();
 213     }
 214     Py_DECREF(ret);
 215
 216     /* Run through the list of structs which have been passed by reference and
 217      * check if they are being held longer than the duration of the callback
 218      * execution. This is determined if the ref count is greater than 1.
 219      * A single ref is held by the argument list and any more would mean the callback
 220      * stored a ref somewhere else. In this case we make an internal copy of
 221      * the boxed struct so Python can own the memory to it.
 222      */
 223     list_item = pass_by_ref_structs;
 224     while (list_item) {
 225         PyObject *item = list_item->data;
 226         if (item->ob_refcnt > 1) {
 227             _pygi_boxed_copy_in_place ((PyGIBoxed *)item);
 228         }
 229         list_item = g_slist_next (list_item);
 230     }
 231
 232  out:
 233     g_slist_free (pass_by_ref_structs);
 234     Py_DECREF(params);
 235     PyGILState_Release(state);
 236 }
 237
 238 GClosure *
 239 pygi_signal_closure_new (PyGObject *instance,
 240                          GType g_type,
 241                          const gchar *signal_name,
 242                          PyObject *callback,
 243                          PyObject *extra_args,
 244                          PyObject *swap_data)
 245 {
 246     GClosure *closure = NULL;
 247     PyGISignalClosure *pygi_closure = NULL;
 248     GISignalInfo *signal_info = NULL;
 249
 250     g_return_val_if_fail(callback != NULL, NULL);
 251
 252     signal_info = _pygi_lookup_signal_from_g_type (g_type, signal_name);
 253     if (signal_info == NULL)
 254         return NULL;
 255
 256     closure = g_closure_new_simple(sizeof(PyGISignalClosure), NULL);
 257     g_closure_add_invalidate_notifier(closure, NULL, pygi_signal_closure_invalidate);
 258     g_closure_set_marshal(closure, pygi_signal_closure_marshal);
 259
 260     pygi_closure = (PyGISignalClosure *)closure;
 261
 262     pygi_closure->signal_info = signal_info;
 263     Py_INCREF(callback);
 264     pygi_closure->pyg_closure.callback = callback;
 265
 266     if (extra_args != NULL && extra_args != Py_None) {
 267         Py_INCREF(extra_args);
 268         if (!PyTuple_Check(extra_args)) {
 269             PyObject *tmp = PyTuple_New(1);
 270             PyTuple_SetItem(tmp, 0, extra_args);
 271             extra_args = tmp;
 272         }
 273         pygi_closure->pyg_closure.extra_args = extra_args;
 274     }
 275     if (swap_data) {
 276         Py_INCREF(swap_data);
 277         pygi_closure->pyg_closure.swap_data = swap_data;
 278         closure->derivative_flag = TRUE;
 279     }
 280
 281     return closure;
 282 }