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     g_assert_cmpint (n_sig_info_args, >=, 0);
  92     /* the first argument to a signal callback is instance,
  93        but instance is not counted in the introspection data */
  94     sig_info_highest_arg = n_sig_info_args + 1;
  95     g_assert_cmpint(sig_info_highest_arg, ==, n_param_values);
  96
  97     /* construct Python tuple for the parameter values */
  98     params = PyTuple_New(n_param_values);
  99     for (i = 0; i < n_param_values; i++) {
 100         /* swap in a different initial data for connect_object() */
 101         if (i == 0 && G_CCLOSURE_SWAP_DATA(closure)) {
 102             g_return_if_fail(pc->swap_data != NULL);
 103             Py_INCREF(pc->swap_data);
 104             PyTuple_SetItem(params, 0, pc->swap_data);
 105
 106         } else if (i == 0) {
 107             PyObject *item = pyg_value_as_pyobject(&param_values[i], FALSE);
 108
 109             if (!item) {
 110                 goto out;
 111             }
 112             PyTuple_SetItem(params, i, item);
 113
 114         } else if (i < (guint)sig_info_highest_arg) {
 115             GIArgInfo arg_info;
 116             GITypeInfo type_info;
 117             GITypeTag type_tag;
 118             GIArgument arg = { 0, };
 119             PyObject *item = NULL;
 120             gboolean free_array = FALSE;
 121             gboolean pass_struct_by_ref = FALSE;
 122
 123             g_callable_info_load_arg(signal_info, i - 1, &arg_info);
 124             g_arg_info_load_type(&arg_info, &type_info);
 125
 126             arg = _pygi_argument_from_g_value(&param_values[i], &type_info);
 127
 128             type_tag = g_type_info_get_tag (&type_info);
 129             if (type_tag == GI_TYPE_TAG_ARRAY) {
 130                 /* Skip the self argument of param_values */
 131                 arg.v_pointer = _pygi_argument_to_array (&arg,
 132                                                          _pygi_argument_array_length_marshal,
 133                                                          (void *)(param_values + 1),
 134                                                          signal_info,
 135                                                          &type_info,
 136                                                          &free_array);
 137             }
 138
 139             /* Hack to ensure struct arguments are passed-by-reference allowing
 140              * callback implementors to modify the struct values. This is needed
 141              * for keeping backwards compatibility and should be removed in future
 142              * versions which support signal output arguments as return values.
 143              * See: https://bugzilla.gnome.org/show_bug.cgi?id=735486
 144              *
 145              * Note the logic here must match the logic path taken in _pygi_argument_to_object.
 146              */
 147             if (type_tag == GI_TYPE_TAG_INTERFACE) {
 148                 GIBaseInfo *info = g_type_info_get_interface (&type_info);
 149                 GIInfoType info_type = g_base_info_get_type (info);
 150
 151                 if (info_type == GI_INFO_TYPE_STRUCT ||
 152                         info_type == GI_INFO_TYPE_BOXED ||
 153                         info_type == GI_INFO_TYPE_UNION) {
 154
 155                     GType gtype = g_registered_type_info_get_g_type ((GIRegisteredTypeInfo *) info);
 156                     gboolean is_foreign = (info_type == GI_INFO_TYPE_STRUCT) &&
 157                                           (g_struct_info_is_foreign ((GIStructInfo *) info));
 158
 159                     if (!is_foreign && !g_type_is_a (gtype, G_TYPE_VALUE) &&
 160                             g_type_is_a (gtype, G_TYPE_BOXED)) {
 161                         pass_struct_by_ref = TRUE;
 162                     }
 163                 }
 164
 165                 g_base_info_unref (info);
 166             }
 167
 168             if (pass_struct_by_ref) {
 169                 /* transfer everything will ensure the struct is not copied when wrapped. */
 170                 item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_EVERYTHING);
 171                 if (item && PyObject_IsInstance (item, (PyObject *) &PyGIBoxed_Type)) {
 172                     ((PyGBoxed *)item)->free_on_dealloc = FALSE;
 173                     pass_by_ref_structs = g_slist_prepend (pass_by_ref_structs, item);
 174                 }
 175
 176             } else {
 177                 item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_NOTHING);
 178             }
 179
 180             if (free_array) {
 181                 g_array_free (arg.v_pointer, FALSE);
 182             }
 183
 184             if (item == NULL) {
 185                 PyErr_Print ();
 186                 goto out;
 187             }
 188             PyTuple_SetItem(params, i, item);
 189         }
 190     }
 191     /* params passed to function may have extra arguments */
 192     if (pc->extra_args) {
 193         PyObject *tuple = params;
 194         params = PySequence_Concat(tuple, pc->extra_args);
 195         Py_DECREF(tuple);
 196     }
 197     ret = PyObject_CallObject(pc->callback, params);
 198     if (ret == NULL) {
 199         if (pc->exception_handler)
 200             pc->exception_handler(return_value, n_param_values, param_values);
 201         else
 202             PyErr_Print();
 203         goto out;
 204     }
 205
 206     if (G_IS_VALUE(return_value) && pyg_value_from_pyobject(return_value, ret) != 0) {
 207         PyErr_SetString(PyExc_TypeError,
 208                         "can't convert return value to desired type");
 209
 210         if (pc->exception_handler)
 211             pc->exception_handler(return_value, n_param_values, param_values);
 212         else
 213             PyErr_Print();
 214     }
 215     Py_DECREF(ret);
 216
 217     /* Run through the list of structs which have been passed by reference and
 218      * check if they are being held longer than the duration of the callback
 219      * execution. This is determined if the ref count is greater than 1.
 220      * A single ref is held by the argument list and any more would mean the callback
 221      * stored a ref somewhere else. In this case we make an internal copy of
 222      * the boxed struct so Python can own the memory to it.
 223      */
 224     list_item = pass_by_ref_structs;
 225     while (list_item) {
 226         PyObject *item = list_item->data;
 227         if (Py_REFCNT (item) > 1) {
 228             pygi_boxed_copy_in_place ((PyGIBoxed *)item);
 229         }
 230         list_item = g_slist_next (list_item);
 231     }
 232
 233  out:
 234     g_slist_free (pass_by_ref_structs);
 235     Py_DECREF(params);
 236     PyGILState_Release(state);
 237 }
 238
 239 GClosure *
 240 pygi_signal_closure_new (PyGObject *instance,
 241                          GType g_type,
 242                          const gchar *signal_name,
 243                          PyObject *callback,
 244                          PyObject *extra_args,
 245                          PyObject *swap_data)
 246 {
 247     GClosure *closure = NULL;
 248     PyGISignalClosure *pygi_closure = NULL;
 249     GISignalInfo *signal_info = NULL;
 250
 251     g_return_val_if_fail(callback != NULL, NULL);
 252
 253     signal_info = _pygi_lookup_signal_from_g_type (g_type, signal_name);
 254     if (signal_info == NULL)
 255         return NULL;
 256
 257     closure = g_closure_new_simple(sizeof(PyGISignalClosure), NULL);
 258     g_closure_add_invalidate_notifier(closure, NULL, pygi_signal_closure_invalidate);
 259     g_closure_set_marshal(closure, pygi_signal_closure_marshal);
 260
 261     pygi_closure = (PyGISignalClosure *)closure;
 262
 263     pygi_closure->signal_info = signal_info;
 264     Py_INCREF(callback);
 265     pygi_closure->pyg_closure.callback = callback;
 266
 267     if (extra_args != NULL && extra_args != Py_None) {
 268         Py_INCREF(extra_args);
 269         if (!PyTuple_Check(extra_args)) {
 270             PyObject *tmp = PyTuple_New(1);
 271             PyTuple_SetItem(tmp, 0, extra_args);
 272             extra_args = tmp;
 273         }
 274         pygi_closure->pyg_closure.extra_args = extra_args;
 275     }
 276     if (swap_data) {
 277         Py_INCREF(swap_data);
 278         pygi_closure->pyg_closure.swap_data = swap_data;
 279         closure->derivative_flag = TRUE;
 280     }
 281
 282     return closure;
 283 }