text: /**
   * \file pcm/pcm_shm.c
   * \ingroup PCM_Plugins
   * \brief PCM Shared Memory Plugin Interface
   * \author Abramo Bagnara <abramo@alsa-project.org>
   * \date 2000-2001
   */
  /*
   *  PCM - Shared Memory Client
   *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
   *
   *
   *   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 <stdlib.h>
  #include <stddef.h>
  #include <limits.h>
  #include <unistd.h>
  #include <string.h>
  #include <fcntl.h>
  #include <sys/ioctl.h>
  #include <sys/shm.h>
  #include <sys/socket.h>
  #include <sys/poll.h>
  #include <sys/un.h>
  #include <sys/mman.h>
  #include <netinet/in.h>
  #include <arpa/inet.h>
  #include <net/if.h>
  #include <netdb.h>
  #include "aserver.h"
  
  #ifndef PIC
  /* entry for static linking */
  const char *_snd_module_pcm_shm = "";
  #endif
  
  #ifndef DOC_HIDDEN
  typedef struct {
  	int socket;
  	volatile snd_pcm_shm_ctrl_t *ctrl;
  } snd_pcm_shm_t;
  #endif
  
  static long snd_pcm_shm_action_fd0(snd_pcm_t *pcm, int *fd)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	int err;
  	char buf[1];
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  
  	err = write(shm->socket, buf, 1);
  	if (err != 1)
  		return -EBADFD;
  	err = snd_receive_fd(shm->socket, buf, 1, fd);
  	if (err != 1)
  		return -EBADFD;
  	if (ctrl->cmd) {
  		SNDERR("Server has not done the cmd");
  		return -EBADFD;
  	}
  	return ctrl->result;
  }
  
  static int snd_pcm_shm_new_rbptr(snd_pcm_t *pcm, snd_pcm_shm_t *shm,
  				 snd_pcm_rbptr_t *rbptr, volatile snd_pcm_shm_rbptr_t *shm_rbptr)
  {
  	if (!shm_rbptr->use_mmap) {
  		if (&pcm->hw == rbptr)
  			snd_pcm_set_hw_ptr(pcm, &shm_rbptr->ptr, -1, 0);
  		else
  			snd_pcm_set_appl_ptr(pcm, &shm_rbptr->ptr, -1, 0);
  	} else {
  		void *ptr;
  		size_t mmap_size, mmap_offset, offset;
  		int fd;
  		long result;
  		
  		shm->ctrl->cmd = &pcm->hw == rbptr ? SND_PCM_IOCTL_HW_PTR_FD : SND_PCM_IOCTL_APPL_PTR_FD;
  		result = snd_pcm_shm_action_fd0(pcm, &fd);
  		if (result < 0)
  			return result;
  		mmap_size = page_ptr(shm_rbptr->offset, sizeof(snd_pcm_uframes_t), &offset, &mmap_offset);
  		ptr = mmap(NULL, mmap_size, PROT_READ|PROT_WRITE, MAP_FILE|MAP_SHARED, fd, mmap_offset);
  		if (ptr == MAP_FAILED || ptr == NULL) {
  			SYSERR("shm rbptr mmap failed");
  			return -errno;
  		}
  		if (&pcm->hw == rbptr)
  			snd_pcm_set_hw_ptr(pcm, (snd_pcm_uframes_t *)((char *)ptr + offset), fd, shm_rbptr->offset);
  		else
  			snd_pcm_set_appl_ptr(pcm, (snd_pcm_uframes_t *)((char *)ptr + offset), fd, shm_rbptr->offset);
  	}
  	return 0;
  }
  
  static long snd_pcm_shm_action(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	int err, result;
  	char buf[1];
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  
  	if (ctrl->hw.changed || ctrl->appl.changed)
  		return -EBADFD;
  	err = write(shm->socket, buf, 1);
  	if (err != 1)
  		return -EBADFD;
  	err = read(shm->socket, buf, 1);
  	if (err != 1)
  		return -EBADFD;
  	if (ctrl->cmd) {
  		SNDERR("Server has not done the cmd");
  		return -EBADFD;
  	}
  	result = ctrl->result;
  	if (ctrl->hw.changed) {
  		err = snd_pcm_shm_new_rbptr(pcm, shm, &pcm->hw, &ctrl->hw);
  		if (err < 0)
  			return err;
  		ctrl->hw.changed = 0;
  	}
  	if (ctrl->appl.changed) {
  		err = snd_pcm_shm_new_rbptr(pcm, shm, &pcm->appl, &ctrl->appl);
  		if (err < 0)
  			return err;
  		ctrl->appl.changed = 0;
  	}
  	return result;
  }
  
  static long snd_pcm_shm_action_fd(snd_pcm_t *pcm, int *fd)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	int err;
  	char buf[1];
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  
  	if (ctrl->hw.changed || ctrl->appl.changed)
  		return -EBADFD;
  	err = write(shm->socket, buf, 1);
  	if (err != 1)
  		return -EBADFD;
  	err = snd_receive_fd(shm->socket, buf, 1, fd);
  	if (err != 1)
  		return -EBADFD;
  	if (ctrl->cmd) {
  		SNDERR("Server has not done the cmd");
  		return -EBADFD;
  	}
  	if (ctrl->hw.changed) {
  		err = snd_pcm_shm_new_rbptr(pcm, shm, &pcm->hw, &ctrl->hw);
  		if (err < 0)
  			return err;
  		ctrl->hw.changed = 0;
  	}
  	if (ctrl->appl.changed) {
  		err = snd_pcm_shm_new_rbptr(pcm, shm, &pcm->appl, &ctrl->appl);
  		if (err < 0)
  			return err;
  		ctrl->appl.changed = 0;
  	}
  	return ctrl->result;
  }
  
  static int snd_pcm_shm_nonblock(snd_pcm_t *pcm ATTRIBUTE_UNUSED, int nonblock ATTRIBUTE_UNUSED)
  {
  	return 0;
  }
  
  static int snd_pcm_shm_async(snd_pcm_t *pcm, int sig, pid_t pid)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SND_PCM_IOCTL_ASYNC;
  	ctrl->u.async.sig = sig;
  	ctrl->u.async.pid = pid;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_info(snd_pcm_t *pcm, snd_pcm_info_t * info)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  //	ctrl->u.info = *info;
  	ctrl->cmd = SNDRV_PCM_IOCTL_INFO;
  	err = snd_pcm_shm_action(pcm);
  	if (err < 0)
  		return err;
  	*info = ctrl->u.info;
  	return err;
  }
  
  static int snd_pcm_shm_hw_refine_cprepare(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params ATTRIBUTE_UNUSED)
  {
  	return 0;
  }
  
  static int snd_pcm_shm_hw_refine_sprepare(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *sparams)
  {
  	snd_pcm_access_mask_t saccess_mask = { SND_PCM_ACCBIT_MMAP };
  	_snd_pcm_hw_params_any(sparams);
  	_snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS,
  				   &saccess_mask);
  	return 0;
  }
  
  static int snd_pcm_shm_hw_refine_schange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params,
  					  snd_pcm_hw_params_t *sparams)
  {
  	int err;
  	unsigned int links = ~SND_PCM_HW_PARBIT_ACCESS;
  	const snd_pcm_access_mask_t *access_mask = snd_pcm_hw_param_get_mask(params, SND_PCM_HW_PARAM_ACCESS);
  	if (!snd_pcm_access_mask_test(access_mask, SND_PCM_ACCESS_RW_INTERLEAVED) &&
  	    !snd_pcm_access_mask_test(access_mask, SND_PCM_ACCESS_RW_NONINTERLEAVED)) {
  		err = _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS,
  					     access_mask);
  		if (err < 0)
  			return err;
  	}
  	err = _snd_pcm_hw_params_refine(sparams, links, params);
  	if (err < 0)
  		return err;
  	return 0;
  }
  	
  static int snd_pcm_shm_hw_refine_cchange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params,
  					  snd_pcm_hw_params_t *sparams)
  {
  	int err;
  	unsigned int links = ~SND_PCM_HW_PARBIT_ACCESS;
  	snd_pcm_access_mask_t access_mask;
  	snd_mask_copy(&access_mask, snd_pcm_hw_param_get_mask(sparams, SND_PCM_HW_PARAM_ACCESS));
  	snd_pcm_access_mask_set(&access_mask, SND_PCM_ACCESS_RW_INTERLEAVED);
  	snd_pcm_access_mask_set(&access_mask, SND_PCM_ACCESS_RW_NONINTERLEAVED);
  	err = _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS,
  					 &access_mask);
  	if (err < 0)
  		return err;
  	err = _snd_pcm_hw_params_refine(params, links, sparams);
  	if (err < 0)
  		return err;
  	return 0;
  }
  
  static int snd_pcm_shm_hw_refine_slave(snd_pcm_t *pcm,
  				       snd_pcm_hw_params_t *params)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	ctrl->u.hw_refine = *params;
  	ctrl->cmd = SNDRV_PCM_IOCTL_HW_REFINE;
  	err = snd_pcm_shm_action(pcm);
  	*params = ctrl->u.hw_refine;
  	return err;
  }
  
  static int snd_pcm_shm_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
  {
  	return snd_pcm_hw_refine_slave(pcm, params,
  				       snd_pcm_shm_hw_refine_cprepare,
  				       snd_pcm_shm_hw_refine_cchange,
  				       snd_pcm_shm_hw_refine_sprepare,
  				       snd_pcm_shm_hw_refine_schange,
  				       snd_pcm_shm_hw_refine_slave);
  }
  
  static int snd_pcm_shm_hw_params_slave(snd_pcm_t *pcm, 
  				       snd_pcm_hw_params_t *params)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	params->flags |= SND_PCM_HW_PARAMS_EXPORT_BUFFER;
  	ctrl->cmd = SNDRV_PCM_IOCTL_HW_PARAMS;
  	ctrl->u.hw_params = *params;
  	err = snd_pcm_shm_action(pcm);
  	*params = ctrl->u.hw_params;
  	return err;
  }
  
  static int snd_pcm_shm_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
  {
  	return snd_pcm_hw_params_slave(pcm, params,
  				       snd_pcm_shm_hw_refine_cchange,
  				       snd_pcm_shm_hw_refine_sprepare,
  				       snd_pcm_shm_hw_refine_schange,
  				       snd_pcm_shm_hw_params_slave);
  }
  
  static int snd_pcm_shm_hw_free(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_HW_FREE;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t * params)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	ctrl->cmd = SNDRV_PCM_IOCTL_SW_PARAMS;
  	ctrl->u.sw_params = *params;
  	err = snd_pcm_shm_action(pcm);
  	*params = ctrl->u.sw_params;
  	if (err < 0)
  		return err;
  	return err;
  }
  
  static int snd_pcm_shm_mmap(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
  {
  	return 0;
  }
  
  static int snd_pcm_shm_munmap(snd_pcm_t *pcm)
  {
  	unsigned int c;
  	for (c = 0; c < pcm->channels; ++c) {
  		snd_pcm_channel_info_t *i = &pcm->mmap_channels[c];
  		unsigned int c1;
  		int err;
  		if (i->type != SND_PCM_AREA_MMAP)
  			continue;
  		if (i->u.mmap.fd < 0)
  			continue;
  		for (c1 = c + 1; c1 < pcm->channels; ++c1) {
  			snd_pcm_channel_info_t *i1 = &pcm->mmap_channels[c1];
  			if (i1->type != SND_PCM_AREA_MMAP)
  				continue;
  			if (i1->u.mmap.fd != i->u.mmap.fd)
  				continue;
  			i1->u.mmap.fd = -1;
  		}
  		err = close(i->u.mmap.fd);
  		if (err < 0) {
  			SYSERR("close failed");
  			return -errno;
  		}
  	}
  	return 0;
  }
  
  static int snd_pcm_shm_channel_info(snd_pcm_t *pcm, snd_pcm_channel_info_t * info)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	int fd;
  	ctrl->cmd = SNDRV_PCM_IOCTL_CHANNEL_INFO;
  	ctrl->u.channel_info = *info;
  	err = snd_pcm_shm_action_fd(pcm, &fd);
  	if (err < 0)
  		return err;
  	*info = ctrl->u.channel_info;
  	info->addr = 0;
  	switch (info->type) {
  	case SND_PCM_AREA_MMAP:
  		info->u.mmap.fd = fd;
  		break;
  	case SND_PCM_AREA_SHM:
  		break;
  	default:
  		assert(0);
  		break;
  	}
  	return err;
  }
  
  static int snd_pcm_shm_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	ctrl->cmd = SNDRV_PCM_IOCTL_STATUS;
  	// ctrl->u.status = *status;
  	err = snd_pcm_shm_action(pcm);
  	if (err < 0)
  		return err;
  	*status = ctrl->u.status;
  	return err;
  }
  
  static snd_pcm_state_t snd_pcm_shm_state(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SND_PCM_IOCTL_STATE;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_hwsync(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SND_PCM_IOCTL_HWSYNC;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	ctrl->cmd = SNDRV_PCM_IOCTL_DELAY;
  	err = snd_pcm_shm_action(pcm);
  	if (err < 0)
  		return err;
  	*delayp = ctrl->u.delay.frames;
  	return err;
  }
  
  static snd_pcm_sframes_t snd_pcm_shm_avail_update(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	ctrl->cmd = SND_PCM_IOCTL_AVAIL_UPDATE;
  	err = snd_pcm_shm_action(pcm);
  	if (err < 0)
  		return err;
  	return err;
  }
  
  static int snd_pcm_shm_htimestamp(snd_pcm_t *pcm ATTRIBUTE_UNUSED,
  				  snd_pcm_uframes_t *avail ATTRIBUTE_UNUSED,
  				  snd_htimestamp_t *tstamp ATTRIBUTE_UNUSED)
  {
  	return -EIO;	/* not implemented yet */
  }
  
  static int snd_pcm_shm_prepare(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_PREPARE;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_reset(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_RESET;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_start(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_START;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_drop(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_DROP;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_drain(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int err;
  	do {
  		ctrl->cmd = SNDRV_PCM_IOCTL_DRAIN;
  		err = snd_pcm_shm_action(pcm);
  		if (err != -EAGAIN)
  			break;
  		usleep(10000);
  	} while (1);
  	if (err < 0)
  		return err;
  	if (!(pcm->mode & SND_PCM_NONBLOCK))
  		snd_pcm_wait(pcm, -1);
  	return err;
  }
  
  static int snd_pcm_shm_pause(snd_pcm_t *pcm, int enable)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_PAUSE;
  	ctrl->u.pause.enable = enable;
  	return snd_pcm_shm_action(pcm);
  }
  
  static snd_pcm_sframes_t snd_pcm_shm_rewindable(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
  {
  	return 0;	/* FIX ME */
  }
  
  static snd_pcm_sframes_t snd_pcm_shm_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_REWIND;
  	ctrl->u.rewind.frames = frames;
  	return snd_pcm_shm_action(pcm);
  }
  
  static snd_pcm_sframes_t snd_pcm_shm_forwardable(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
  {
  	return 0;	/* FIX ME */
  }
  
  static snd_pcm_sframes_t snd_pcm_shm_forward(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SND_PCM_IOCTL_FORWARD;
  	ctrl->u.forward.frames = frames;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_resume(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SNDRV_PCM_IOCTL_RESUME;
  	return snd_pcm_shm_action(pcm);
  }
  
  static snd_pcm_sframes_t snd_pcm_shm_mmap_commit(snd_pcm_t *pcm,
  						 snd_pcm_uframes_t offset ATTRIBUTE_UNUSED,
  						 snd_pcm_uframes_t size)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	ctrl->cmd = SND_PCM_IOCTL_MMAP_COMMIT;
  	ctrl->u.mmap_commit.offset = offset;
  	ctrl->u.mmap_commit.frames = size;
  	return snd_pcm_shm_action(pcm);
  }
  
  static int snd_pcm_shm_poll_descriptor(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int fd, err;
  	ctrl->cmd = SND_PCM_IOCTL_POLL_DESCRIPTOR;
  	err = snd_pcm_shm_action_fd(pcm, &fd);
  	if (err < 0)
  		return err;
  	return fd;
  }
  
  static int snd_pcm_shm_close(snd_pcm_t *pcm)
  {
  	snd_pcm_shm_t *shm = pcm->private_data;
  	volatile snd_pcm_shm_ctrl_t *ctrl = shm->ctrl;
  	int result;
  	ctrl->cmd = SND_PCM_IOCTL_CLOSE;
  	result = snd_pcm_shm_action(pcm);
  	shmdt((void *)ctrl);
  	close(shm->socket);
  	close(pcm->poll_fd);
  	free(shm);
  	return result;
  }
  
  static void snd_pcm_shm_dump(snd_pcm_t *pcm, snd_output_t *out)
  {
  	snd_output_printf(out, "Shm PCM\n");
  	if (pcm->setup) {
  		snd_output_printf(out, "Its setup is:\n");
  		snd_pcm_dump_setup(pcm, out);
  	}
  }
  
  static const snd_pcm_ops_t snd_pcm_shm_ops = {
  	.close = snd_pcm_shm_close,
  	.info = snd_pcm_shm_info,
  	.hw_refine = snd_pcm_shm_hw_refine,
  	.hw_params = snd_pcm_shm_hw_params,
  	.hw_free = snd_pcm_shm_hw_free,
  	.sw_params = snd_pcm_shm_sw_params,
  	.channel_info = snd_pcm_shm_channel_info,
  	.dump = snd_pcm_shm_dump,
  	.nonblock = snd_pcm_shm_nonblock,
  	.async = snd_pcm_shm_async,
  	.mmap = snd_pcm_shm_mmap,
  	.munmap = snd_pcm_shm_munmap,
  };
  
  static const snd_pcm_fast_ops_t snd_pcm_shm_fast_ops = {
  	.status = snd_pcm_shm_status,
  	.state = snd_pcm_shm_state,
  	.hwsync = snd_pcm_shm_hwsync,
  	.delay = snd_pcm_shm_delay,
  	.prepare = snd_pcm_shm_prepare,
  	.reset = snd_pcm_shm_reset,
  	.start = snd_pcm_shm_start,
  	.drop = snd_pcm_shm_drop,
  	.drain = snd_pcm_shm_drain,
  	.pause = snd_pcm_shm_pause,
  	.rewindable = snd_pcm_shm_rewindable,
  	.rewind = snd_pcm_shm_rewind,
  	.forwardable = snd_pcm_shm_forwardable,
  	.forward = snd_pcm_shm_forward,
  	.resume = snd_pcm_shm_resume,
  	.writei = snd_pcm_mmap_writei,
  	.writen = snd_pcm_mmap_writen,
  	.readi = snd_pcm_mmap_readi,
  	.readn = snd_pcm_mmap_readn,
  	.avail_update = snd_pcm_shm_avail_update,
  	.mmap_commit = snd_pcm_shm_mmap_commit,
  	.htimestamp = snd_pcm_shm_htimestamp,
  };
  
  static int make_local_socket(const char *filename)
  {
  	size_t l = strlen(filename);
  	size_t size = offsetof(struct sockaddr_un, sun_path) + l;
  	struct sockaddr_un *addr = alloca(size);
  	int sock;
  
  	sock = socket(PF_LOCAL, SOCK_STREAM, 0);
  	if (sock < 0) {
  		SYSERR("socket failed");
  		return -errno;
  	}
  	
  	addr->sun_family = AF_LOCAL;
  	memcpy(addr->sun_path, filename, l);
  
  	if (connect(sock, (struct sockaddr *) addr, size) < 0) {
  		SYSERR("connect failed");
  		return -errno;
  	}
  	return sock;
  }
  
  /**
   * \brief Creates a new shared memory PCM
   * \param pcmp Returns created PCM handle
   * \param name Name of PCM
   * \param sockname Unix socket name
   * \param sname Server name
   * \param stream PCM Stream
   * \param mode PCM Mode
   * \retval zero on success otherwise a negative error code
   * \warning Using of this function might be dangerous in the sense
   *          of compatibility reasons. The prototype might be freely
   *          changed in future.
   */
  int snd_pcm_shm_open(snd_pcm_t **pcmp, const char *name,
  		     const char *sockname, const char *sname,
  		     snd_pcm_stream_t stream, int mode)
  {
  	snd_pcm_t *pcm;
  	snd_pcm_shm_t *shm = NULL;
  	snd_client_open_request_t *req;
  	snd_client_open_answer_t ans;
  	size_t snamelen, reqlen;
  	int err;
  	int result;
  	snd_pcm_shm_ctrl_t *ctrl = NULL;
  	int sock = -1;
  	snamelen = strlen(sname);
  	if (snamelen > 255)
  		return -EINVAL;
  
  	result = make_local_socket(sockname);
  	if (result < 0) {
  		SNDERR("server for socket %s is not running", sockname);
  		goto _err;
  	}
  	sock = result;
  
  	reqlen = sizeof(*req) + snamelen;
  	req = alloca(reqlen);
  	memcpy(req->name, sname, snamelen);
  	req->dev_type = SND_DEV_TYPE_PCM;
  	req->transport_type = SND_TRANSPORT_TYPE_SHM;
  	req->stream = stream;
  	req->mode = mode;
  	req->namelen = snamelen;
  	err = write(sock, req, reqlen);
  	if (err < 0) {
  		SYSERR("write error");
  		result = -errno;
  		goto _err;
  	}
  	if ((size_t) err != reqlen) {
  		SNDERR("write size error");
  		result = -EINVAL;
  		goto _err;
  	}
  	err = read(sock, &ans, sizeof(ans));
  	if (err < 0) {
  		SYSERR("read error");
  		result = -errno;
  		goto _err;
  	}
  	if (err != sizeof(ans)) {
  		SNDERR("read size error");
  		result = -EINVAL;
  		goto _err;
  	}
  	result = ans.result;
  	if (result < 0)
  		goto _err;
  
  	ctrl = shmat(ans.cookie, 0, 0);
  	if (!ctrl) {
  		SYSERR("shmat error");
  		result = -errno;
  		goto _err;
  	}
  		
  	shm = calloc(1, sizeof(snd_pcm_shm_t));
  	if (!shm) {
  		result = -ENOMEM;
  		goto _err;
  	}
  
  	shm->socket = sock;
  	shm->ctrl = ctrl;
  
  	err = snd_pcm_new(&pcm, SND_PCM_TYPE_SHM, name, stream, mode);
  	if (err < 0) {
  		result = err;
  		goto _err;
  	}
  	pcm->mmap_rw = 1;
  	pcm->ops = &snd_pcm_shm_ops;
  	pcm->fast_ops = &snd_pcm_shm_fast_ops;
  	pcm->private_data = shm;
  	err = snd_pcm_shm_poll_descriptor(pcm);
  	if (err < 0) {
  		snd_pcm_close(pcm);
  		return err;
  	}
  	pcm->poll_fd = err;
  	pcm->poll_events = stream == SND_PCM_STREAM_PLAYBACK ? POLLOUT : POLLIN;
  	snd_pcm_set_hw_ptr(pcm, &ctrl->hw.ptr, -1, 0);
  	snd_pcm_set_appl_ptr(pcm, &ctrl->appl.ptr, -1, 0);
  	*pcmp = pcm;
  	return 0;
  
   _err:
  	close(sock);
  	if (ctrl)
  		shmdt(ctrl);
  	free(shm);
  	return result;
  }
  
  /*! \page pcm_plugins
  
  \section pcm_plugins_shm Plugin: shm
  
  This plugin communicates with aserver via shared memory. It is a raw
  communication without any conversions, but it can be expected worse
  performance.
  
  \code
  pcm.name {
          type shm                # Shared memory PCM
  	server STR		# Server name
  	pcm STR			# PCM name
  }
  \endcode
  
  \subsection pcm_plugins_shm_funcref Function reference
  
  <UL>
    <LI>snd_pcm_shm_open()
    <LI>_snd_pcm_shm_open()
  </UL>
  
  */
  
  /**
   * \brief Creates a new shm PCM
   * \param pcmp Returns created PCM handle
   * \param name Name of PCM
   * \param root Root configuration node
   * \param conf Configuration node with hw PCM description
   * \param stream PCM Stream
   * \param mode PCM Mode
   * \warning Using of this function might be dangerous in the sense
   *          of compatibility reasons. The prototype might be freely
   *          changed in future.
   */
  int _snd_pcm_shm_open(snd_pcm_t **pcmp, const char *name,
  		      snd_config_t *root, snd_config_t *conf,
  		      snd_pcm_stream_t stream, int mode)
  {
  	snd_config_iterator_t i, next;
  	const char *server = NULL;
  	const char *pcm_name = NULL;
  	snd_config_t *sconfig;
  	const char *sockname = NULL;
  	long port = -1;
  	int err;
  
  	snd_config_for_each(i, next, conf) {
  		snd_config_t *n = snd_config_iterator_entry(i);
  		const char *id;
  		if (snd_config_get_id(n, &id) < 0)
  			continue;
  		if (snd_pcm_conf_generic_id(id))
  			continue;
  		if (strcmp(id, "server") == 0) {
  			err = snd_config_get_string(n, &server);
  			if (err < 0) {
  				SNDERR("Invalid type for %s", id);
  				return -EINVAL;
  			}
  			continue;
  		}
  		if (strcmp(id, "pcm") == 0) {
  			err = snd_config_get_string(n, &pcm_name);
  			if (err < 0) {
  				SNDERR("Invalid type for %s", id);
  				return -EINVAL;
  			}
  			continue;
  		}
  		SNDERR("Unknown field %s", id);
  		return -EINVAL;
  	}
  	if (!pcm_name) {
  		SNDERR("pcm is not defined");
  		return -EINVAL;
  	}
  	if (!server) {
  		SNDERR("server is not defined");
  		return -EINVAL;
  	}
  	err = snd_config_search_definition(root, "server", server, &sconfig);
  	if (err < 0) {
  		SNDERR("Unknown server %s", server);
  		return -EINVAL;
  	}
  	if (snd_config_get_type(sconfig) != SND_CONFIG_TYPE_COMPOUND) {
  		SNDERR("Invalid type for server %s definition", server);
  		goto _err;
  	}
  	snd_config_for_each(i, next, sconfig) {
  		snd_config_t *n = snd_config_iterator_entry(i);
  		const char *id;
  		if (snd_config_get_id(n, &id) < 0)
  			continue;
  		if (strcmp(id, "comment") == 0)
  			continue;
  		if (strcmp(id, "host") == 0)
  			continue;
  		if (strcmp(id, "socket") == 0) {
  			err = snd_config_get_string(n, &sockname);
  			if (err < 0) {
  				SNDERR("Invalid type for %s", id);
  				goto _err;
  			}
  			continue;
  		}
  		if (strcmp(id, "port") == 0) {
  			err = snd_config_get_integer(n, &port);
  			if (err < 0) {
  				SNDERR("Invalid type for %s", id);
  				goto _err;
  			}
  			continue;
  		}
  		SNDERR("Unknown field %s", id);
  	       _err:
  		err = -EINVAL;
  		goto __error;
  	}
  
  	if (!sockname) {
  		SNDERR("socket is not defined");
  		goto _err;
  	}
  	err = snd_pcm_shm_open(pcmp, name, sockname, pcm_name, stream, mode);
        __error:
  	snd_config_delete(sconfig);
  	return err;
  }
  #ifndef DOC_HIDDEN
  SND_DLSYM_BUILD_VERSION(_snd_pcm_shm_open, SND_PCM_DLSYM_VERSION);
  #endif
  