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/*
* IPC SHM area manager
* Copyright (c) 2003 by Jaroslav Kysela <perex@perex.cz>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <errno.h>
#include <sys/poll.h>
#include <sys/mman.h>
#include <sys/shm.h>
#include "list.h"
#ifndef DOC_HIDDEN
struct snd_shm_area {
struct list_head list;
int shmid;
void *ptr;
int share;
};
#endif
static LIST_HEAD(shm_areas);
/**
* \brief Create a shm area record
* \param shmid IPC SHM ID
* \param ptr the shared area pointer
* \return The allocated shm area record, NULL if fail
*
* Allocates a shared area record with the given SHM ID and pointer.
* The record has a reference counter, which is initialized to 1 by this function.
*/
struct snd_shm_area *snd_shm_area_create(int shmid, void *ptr)
{
struct snd_shm_area *area = malloc(sizeof(*area));
if (area) {
area->shmid = shmid;
area->ptr = ptr;
area->share = 1;
list_add_tail(&area->list, &shm_areas);
}
return area;
}
/**
* \brief Increase the reference counter of shm area record
* \param area shm area record
* \return the shm area record (identical with the argument)
*
* Increases the reference counter of the given shared area record.
*/
struct snd_shm_area *snd_shm_area_share(struct snd_shm_area *area)
{
if (area == NULL)
return NULL;
area->share++;
return area;
}
/**
* \brief Release the shared area record
* \param area the shared are record
* \return 0 if successful, or a negative error code
*
* Decreases the reference counter of the given shared area record, and
* releases the resources automaticall if it reaches to 0.
*/
int snd_shm_area_destroy(struct snd_shm_area *area)
{
if (area == NULL)
return -ENOENT;
if (--area->share)
return 0;
list_del(&area->list);
shmdt(area->ptr);
free(area);
return 0;
}
void snd_shm_area_destructor(void) __attribute__ ((destructor));
void snd_shm_area_destructor(void)
{
struct list_head *pos;
struct snd_shm_area *area;
list_for_each(pos, &shm_areas) {
area = list_entry(pos, struct snd_shm_area, list);
shmdt(area->ptr);
}
}
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