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115 lines
2.9 KiB
C
115 lines
2.9 KiB
C
/*
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* IPC SHM area manager
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* Copyright (c) 2003 by Jaroslav Kysela <perex@perex.cz>
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#include "config.h"
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/* These funcs are only used by pcm_mmap when sys/shm.h is available. */
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#ifdef HAVE_SYS_SHM_H
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#include <stdio.h>
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#include <malloc.h>
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#include <string.h>
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#include <errno.h>
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#include <poll.h>
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#include <sys/mman.h>
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#include <sys/shm.h>
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#include "list.h"
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#ifndef DOC_HIDDEN
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struct snd_shm_area {
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struct list_head list;
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int shmid;
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void *ptr;
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int share;
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};
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#endif
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static LIST_HEAD(shm_areas);
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/**
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* \brief Create a shm area record
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* \param shmid IPC SHM ID
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* \param ptr the shared area pointer
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* \return The allocated shm area record, NULL if fail
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*
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* Allocates a shared area record with the given SHM ID and pointer.
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* The record has a reference counter, which is initialized to 1 by this function.
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*/
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struct snd_shm_area *snd_shm_area_create(int shmid, void *ptr)
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{
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struct snd_shm_area *area = malloc(sizeof(*area));
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if (area) {
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area->shmid = shmid;
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area->ptr = ptr;
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area->share = 1;
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list_add_tail(&area->list, &shm_areas);
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}
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return area;
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}
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/**
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* \brief Increase the reference counter of shm area record
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* \param area shm area record
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* \return the shm area record (identical with the argument)
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*
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* Increases the reference counter of the given shared area record.
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*/
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struct snd_shm_area *snd_shm_area_share(struct snd_shm_area *area)
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{
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if (area == NULL)
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return NULL;
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area->share++;
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return area;
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}
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/**
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* \brief Release the shared area record
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* \param area the shared are record
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* \return 0 if successful, or a negative error code
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*
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* Decreases the reference counter of the given shared area record, and
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* releases the resources automaticall if it reaches to 0.
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*/
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int snd_shm_area_destroy(struct snd_shm_area *area)
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{
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if (area == NULL)
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return -ENOENT;
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if (--area->share)
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return 0;
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list_del(&area->list);
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shmdt(area->ptr);
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free(area);
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return 0;
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}
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void snd_shm_area_destructor(void) __attribute__ ((destructor));
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void snd_shm_area_destructor(void)
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{
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struct list_head *pos;
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struct snd_shm_area *area;
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list_for_each(pos, &shm_areas) {
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area = list_entry(pos, struct snd_shm_area, list);
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shmdt(area->ptr);
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}
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}
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#endif
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