autochan.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2009, Digium, Inc.
 *
 * Mark Michelson <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \file
 * \brief "smart" channels
 *
 * \author Mark Michelson <[email protected]>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/autochan.h"
#include "asterisk/utils.h"
#include "asterisk/linkedlists.h"
#include "asterisk/options.h"
#include "asterisk/channel.h"

struct ast_autochan *ast_autochan_setup(struct ast_channel *chan)
{
   struct ast_autochan *autochan;

   if (!chan) {
      return NULL;
   }

   if (!(autochan = ast_calloc(1, sizeof(*autochan)))) {
      return NULL;
   }
   ast_mutex_init(&autochan->lock);

   autochan->chan = ast_channel_ref(chan);

   ast_debug(1, "Created autochan %p to hold channel %s (%p)\n",
      autochan, ast_channel_name(chan), chan);

   /* autochan is still private, no need for ast_autochan_channel_lock() */
   ast_channel_lock(autochan->chan);
   AST_LIST_INSERT_TAIL(ast_channel_autochans(autochan->chan), autochan, list);
   ast_channel_unlock(autochan->chan);

   return autochan;
}

void ast_autochan_destroy(struct ast_autochan *autochan)
{
   struct ast_autochan *autochan_iter;

   ast_autochan_channel_lock(autochan);
   AST_LIST_TRAVERSE_SAFE_BEGIN(ast_channel_autochans(autochan->chan), autochan_iter, list) {
      if (autochan_iter == autochan) {
         AST_LIST_REMOVE_CURRENT(list);
         ast_debug(1, "Removed autochan %p from the list, about to free it\n", autochan);
         break;
      }
   }
   AST_LIST_TRAVERSE_SAFE_END;
   ast_autochan_channel_unlock(autochan);

   autochan->chan = ast_channel_unref(autochan->chan);

   ast_mutex_destroy(&autochan->lock);

   ast_free(autochan);
}

void ast_autochan_new_channel(struct ast_channel *old_chan, struct ast_channel *new_chan)
{
   struct ast_autochan *autochan;

   AST_LIST_APPEND_LIST(ast_channel_autochans(new_chan), ast_channel_autochans(old_chan), list);

   /* Deadlock avoidance is not needed since the channels are already locked. */
   AST_LIST_TRAVERSE(ast_channel_autochans(new_chan), autochan, list) {
      ast_mutex_lock(&autochan->lock);
      if (autochan->chan == old_chan) {
         autochan->chan = ast_channel_ref(new_chan);
         ast_channel_unref(old_chan);

         ast_debug(1, "Autochan %p used to hold channel %s (%p) but now holds channel %s (%p)\n",
               autochan, ast_channel_name(old_chan), old_chan, ast_channel_name(new_chan), new_chan);
      }
      ast_mutex_unlock(&autochan->lock);
   }
}