/*****************************************************************************
 * sched/group_find.c
 *
 *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 *****************************************************************************/

/*****************************************************************************
 * Included Files
 *****************************************************************************/

#include <nuttx/config.h>

#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/kmalloc.h>

#include "group_internal.h"
#include "env_internal.h"

#ifdef HAVE_TASK_GROUP

/*****************************************************************************
 * Pre-processor Definitions
 *****************************************************************************/

/*****************************************************************************
 * Private Types
 *****************************************************************************/

/*****************************************************************************
 * Private Data
 *****************************************************************************/

/*****************************************************************************
 * Public Data
 *****************************************************************************/

/*****************************************************************************
 * Private Functions
 *****************************************************************************/

/*****************************************************************************
 * Public Functions
 *****************************************************************************/

/*****************************************************************************
 * Name: group_findbygid
 *
 * Description:
 *   Given a group ID, find the group task structure with that ID.  IDs are
 *   used instead of pointers to group structures.  This is done because a 
 *   group can disappear at any time leaving a stale pointer; an ID is cleaner
 *   because if the group disappears, this function will fail gracefully.
 *
 * Parameters:
 *   gid - The group ID to find.
 *
 * Return Value:
 *   On success, a pointer to the group task structure is returned.  This
 *   function can fail only if there is no group that corresponds to the
 *   group ID.
 *
 * Assumptions:
 *   Called during when signally tasks in a safe context.  No special
 *   precautions should be required here.  However, extra care is taken when
 *   accessing the global g_grouphead list.
 *
 *****************************************************************************/

#ifdef HAVE_GROUP_MEMBERS
FAR struct task_group_s *group_findbygid(gid_t gid)
{
  FAR struct task_group_s *group;
  irqstate_t flags;

  /* Find the status structure with the matching GID  */

  flags = irqsave();
  for (group = g_grouphead; group; group = group->flink)
    {
      if (group->tg_gid == gid)
        {
          irqrestore(flags);
          return group;
        }
    }

  irqrestore(flags);
  return NULL;
}
#endif

/*****************************************************************************
 * Name: group_findbygid
 *
 * Description:
 *   Given a task ID, find the group task structure with was started by that
 *   task ID.  That task's ID is retained in the group as tg_task and will
 *   be remember even if the main task thread leaves the group.
 *
 * Parameters:
 *   pid - The task ID of the main task thread.
 *
 * Return Value:
 *   On success, a pointer to the group task structure is returned.  This
 *   function can fail only if there is no group that corresponds to the
 *   task ID.
 *
 * Assumptions:
 *   Called during when signally tasks in a safe context.  No special
 *   precautions should be required here.  However, extra care is taken when
 *   accessing the global g_grouphead list.
 *
 *****************************************************************************/

#ifdef HAVE_GROUP_MEMBERS
FAR struct task_group_s *group_findbypid(pid_t pid)
{
  FAR struct task_group_s *group;
  irqstate_t flags;

  /* Find the status structure with the matching PID  */

  flags = irqsave();
  for (group = g_grouphead; group; group = group->flink)
    {
      if (group->tg_task == pid)
        {
          irqrestore(flags);
          return group;
        }
    }

  irqrestore(flags);
  return NULL;
}
#endif

#endif /* HAVE_TASK_GROUP */