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/* Channel broadcaster.
Copyright (C) 2007 Free Software Foundation, Inc.
Written by Carl Fredrik Hammar <hammy.lite@gmail.com>
This file is part of the GNU Hurd.
The GNU Hurd is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
The GNU Hurd 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
#include "channel.h"
#include <string.h>
struct broadcast_hook
{
struct channel *channel; /* Channel to broadcast. */
size_t num_channels; /* Number of open channels. */
size_t amount; /* Amount to read. */
/* Broadcasted when read has been made. */
struct condition read_cond;
size_t wait_count; /* Number of channels waiting to read. */
size_t pending_count; /* Number of channels waiting to recieve. */
/* Result of read. */
error_t err;
void *buf;
size_t len;
};
static error_t
broadcast_read (struct channel *channel, size_t amount,
void **buf, size_t *len)
{
struct channel_hub *hub = channel->hub;
struct broadcast_hook *hook = hub->hook;
pthread_mutex_lock (&hub->lock);
hook->wait_count++;
if (hook->amount == 0 || amount < hook->amount)
hook->amount = amount;
if (hook->wait_count == hook->num_channels)
{
hook->err = channel_read (hook->channel, hook->amount,
&hook->buf, &hook->len);
hook->pending_count = hook->wait_count;
hook->wait_count = 0;
condition_broadcast (&hook->read_cond);
}
else
condition_wait (&hook->read_cond, &hub->lock);
hook->pending_count--;
if (hook->err)
return hook->err;
if (hook->pending_count == 0)
*buf = hook->buf;
else
memcpy (*buf, hook->buf, hook->amount);
*len = hook->len;
pthread_mutex_unlock (&hub->lock);
return 0;
}
static error_t
broadcast_write (struct channel *channel, void *buf, size_t len,
size_t *amount)
{
return EOPNOTSUPP;
}
static error_t
broadcast_open (struct channel *channel, int flags)
{
struct broadcast_hook *hook = channel->hub->hook;
error_t err = 0;
if (hook->num_channels == 0)
err = channel_open (channel->hub->children[0], flags, &hook->channel);
if (! err)
hook->num_channels++;
return err;
}
static void
broadcast_close (struct channel *channel)
{
struct broadcast_hook *hook = channel->hub->hook;
pthread_mutex_lock (&channel->hub->lock);
hook->num_channels--;
if (hook->num_channels == 0)
channel_close (hook->channel);
pthread_mutex_unlock (&channel->hub->lock);
}
static void
broadcast_clear_hub (struct channel_hub *hub)
{
struct broadcast_hook *hook = hub->hook;
/* Might be null because `channel_free_hub' is called from
`channel_create_broadcast_hub'. */
if (hook)
{
condition_clear (&hook->read_cond);
free (hook);
}
}
const struct channel_class
channel_broadcast_class = {
name: "broadcast",
read: broadcast_read,
write: broadcast_write,
open: broadcast_open,
close: broadcast_close,
create_hub: channel_create_broadcast_hub,
clear_hub: broadcast_clear_hub
};
CHANNEL_STD_CLASS (broadcast);
error_t
channel_create_broadcast_hub (const char *name, int flags,
const struct channel_class *const *classes,
struct channel_hub **hub)
{
struct channel_hub *new = 0, *child = 0;
struct broadcast_hook *hook = 0;
error_t err;
flags |= CHANNEL_HARD_READONLY | CHANNEL_ENFORCED;
err = channel_alloc_hub (&channel_broadcast_class, name, flags, &new);
if (err)
return err;
err = channel_create_typed_hub (name, flags, classes, &child);
if (err)
{
channel_free_hub (new);
return err;
}
channel_set_children (new, &child, 1);
if (err)
{
channel_free_hub (new);
channel_free_hub (child);
return err;
}
hook = new->hook = calloc (1, sizeof (struct broadcast_hook));
if (!hook)
{
channel_free_hub (new);
return ENOMEM;
}
condition_init (&hook->read_cond);
*hub = new;
return 0;
}
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