lib/tevent/tevent_immediate.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    common events code for immediate events
   5
   6    Copyright (C) Stefan Metzmacher 2009
   7
   8      ** NOTE! The following LGPL license applies to the tevent
   9      ** library. This does NOT imply that all of Samba is released
  10      ** under the LGPL
  11
  12    This library is free software; you can redistribute it and/or
  13    modify it under the terms of the GNU Lesser General Public
  14    License as published by the Free Software Foundation; either
  15    version 3 of the License, or (at your option) any later version.
  16
  17    This library is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20    Lesser General Public License for more details.
  21
  22    You should have received a copy of the GNU Lesser General Public
  23    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  24 */
  25
  26 #include "replace.h"
  27 #include "tevent.h"
  28 #include "tevent_internal.h"
  29 #include "tevent_util.h"
  30
  31 static void tevent_common_immediate_cancel(struct tevent_immediate *im)
  32 {
  33         const char *create_location = im->create_location;
  34         bool busy = im->busy;
  35
  36         if (im->destroyed) {
  37                 tevent_abort(im->event_ctx, "tevent_immediate use after free");
  38                 return;
  39         }
  40
  41         if (!im->event_ctx) {
  42                 return;
  43         }
  44
  45         if (im->handler_name != NULL) {
  46                 tevent_debug(im->event_ctx, TEVENT_DEBUG_TRACE,
  47                              "Cancel immediate event %p \"%s\"\n",
  48                              im, im->handler_name);
  49         }
  50
  51         /* let the backend free im->additional_data */
  52         if (im->cancel_fn) {
  53                 im->cancel_fn(im);
  54         }
  55
  56         DLIST_REMOVE(im->event_ctx->immediate_events, im);
  57
  58         *im = (struct tevent_immediate) {
  59                 .create_location        = create_location,
  60                 .busy                   = busy,
  61         };
  62
  63         if (!busy) {
  64                 talloc_set_destructor(im, NULL);
  65         }
  66 }
  67
  68 /*
  69   destroy an immediate event
  70 */
  71 static int tevent_common_immediate_destructor(struct tevent_immediate *im)
  72 {
  73         if (im->destroyed) {
  74                 tevent_common_check_double_free(im,
  75                                                 "tevent_immediate double free");
  76                 goto done;
  77         }
  78
  79         tevent_common_immediate_cancel(im);
  80
  81         im->destroyed = true;
  82
  83 done:
  84         if (im->busy) {
  85                 return -1;
  86         }
  87
  88         return 0;
  89 }
  90
  91 /*
  92  * schedule an immediate event on
  93  */
  94 void tevent_common_schedule_immediate(struct tevent_immediate *im,
  95                                       struct tevent_context *ev,
  96                                       tevent_immediate_handler_t handler,
  97                                       void *private_data,
  98                                       const char *handler_name,
  99                                       const char *location)
 100 {
 101         const char *create_location = im->create_location;
 102         bool busy = im->busy;
 103         struct tevent_wrapper_glue *glue = im->wrapper;
 104
 105         tevent_common_immediate_cancel(im);
 106
 107         if (!handler) {
 108                 return;
 109         }
 110
 111         *im = (struct tevent_immediate) {
 112                 .event_ctx              = ev,
 113                 .wrapper                = glue,
 114                 .handler                = handler,
 115                 .private_data           = private_data,
 116                 .handler_name           = handler_name,
 117                 .create_location        = create_location,
 118                 .schedule_location      = location,
 119                 .busy                   = busy,
 120         };
 121
 122         DLIST_ADD_END(ev->immediate_events, im);
 123         talloc_set_destructor(im, tevent_common_immediate_destructor);
 124
 125         tevent_debug(ev, TEVENT_DEBUG_TRACE,
 126                      "Schedule immediate event \"%s\": %p\n",
 127                      handler_name, im);
 128 }
 129
 130 int tevent_common_invoke_immediate_handler(struct tevent_immediate *im,
 131                                            bool *removed)
 132 {
 133         struct tevent_context *handler_ev = im->event_ctx;
 134         struct tevent_context *ev = im->event_ctx;
 135         struct tevent_immediate cur = *im;
 136
 137         if (removed != NULL) {
 138                 *removed = false;
 139         }
 140
 141         tevent_debug(ev, TEVENT_DEBUG_TRACE,
 142                      "Run immediate event \"%s\": %p\n",
 143                      im->handler_name, im);
 144
 145         /*
 146          * remember the handler and then clear the event
 147          * the handler might reschedule the event
 148          */
 149
 150         im->busy = true;
 151         im->handler_name = NULL;
 152         tevent_common_immediate_cancel(im);
 153         if (cur.wrapper != NULL) {
 154                 handler_ev = cur.wrapper->wrap_ev;
 155
 156                 tevent_wrapper_push_use_internal(handler_ev, cur.wrapper);
 157                 cur.wrapper->ops->before_immediate_handler(
 158                                         cur.wrapper->wrap_ev,
 159                                         cur.wrapper->private_state,
 160                                         cur.wrapper->main_ev,
 161                                         im,
 162                                         cur.handler_name,
 163                                         cur.schedule_location);
 164         }
 165         cur.handler(handler_ev, im, cur.private_data);
 166         if (cur.wrapper != NULL) {
 167                 cur.wrapper->ops->after_immediate_handler(
 168                                         cur.wrapper->wrap_ev,
 169                                         cur.wrapper->private_state,
 170                                         cur.wrapper->main_ev,
 171                                         im,
 172                                         cur.handler_name,
 173                                         cur.schedule_location);
 174                 tevent_wrapper_pop_use_internal(handler_ev, cur.wrapper);
 175         }
 176         im->busy = false;
 177
 178         if (im->destroyed) {
 179                 talloc_set_destructor(im, NULL);
 180                 TALLOC_FREE(im);
 181                 if (removed != NULL) {
 182                         *removed = true;
 183                 }
 184         }
 185
 186         return 0;
 187 }
 188
 189 /*
 190   trigger the first immediate event and return true
 191   if no event was triggered return false
 192 */
 193 bool tevent_common_loop_immediate(struct tevent_context *ev)
 194 {
 195         struct tevent_immediate *im = ev->immediate_events;
 196         int ret;
 197
 198         if (!im) {
 199                 return false;
 200         }
 201
 202         ret = tevent_common_invoke_immediate_handler(im, NULL);
 203         if (ret != 0) {
 204                 tevent_abort(ev, "tevent_common_invoke_immediate_handler() failed");
 205         }
 206
 207         return true;
 208 }
 209