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/* Generic channel functions.
Copyright (C) 1995, 1996, 1997, 1998, 1999, 2001, 2002, 2003, 2007
Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.org>
Reworked for libchannel 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 <malloc.h>
#include "channel.h"
/* Allocate a new channel of hub HUB, with FLAGS set, then return it in
CHANNEL. Return ENOMEM if memory for the hub couldn't be allocated. */
error_t
channel_alloc (struct channel_hub *hub, int flags,
struct channel **channel)
{
struct channel *new = malloc (sizeof (struct channel));
if (!new)
return ENOMEM;
new->flags = flags;
new->hub = hub;
new->class_hook = 0;
new->user_hook = 0;
*channel = new;
return 0;
}
/* Free CHANNEL and any generic resources allocated for it. */
void
channel_free (struct channel *channel)
{
free (channel);
}
/* Allocate a new channel, open it, and return it in CHANNEL. Uses
HUB's open method and passes FLAGS to it, unless it's null. */
error_t
channel_open (struct channel_hub *hub, int flags,
struct channel **channel)
{
error_t err;
flags |= hub->flags & (CHANNEL_READONLY | CHANNEL_WRITEONLY);
err = channel_alloc (hub, flags, channel);
if (err)
return err;
if (hub->class->open)
err = (*hub->class->open) (*channel, flags);
return err;
}
/* Call CHANNEL's close method, unless it's null, then free it
(regardless.) */
void
channel_close (struct channel *channel)
{
if (channel->hub->class->close)
(*channel->hub->class->close) (channel);
channel_free (channel);
}
/* Set the flags FLAGS in CHANNEL. Remove any already set flags in FLAGS,
if FLAGS contain any backend flags call set_flags method or if
set_flags is null return EINVAL. Lastly generic flags get set. */
error_t
channel_set_flags (struct channel *channel, int flags)
{
error_t err = 0;
int orig = channel->flags, new = flags & ~orig;
if (new & CHANNEL_BACKEND_FLAGS)
{
if (channel->hub->class->set_flags)
err = (*channel->hub->class->set_flags) (channel, new);
else
err = EINVAL;
}
if (! err)
channel->flags |= (new & ~CHANNEL_BACKEND_FLAGS);
return err;
}
/* Clear the flags FLAGS in CHANNEL. Remove any already cleared flags in
FLAGS, if FLAGS contain any backend flags call clear_flags method or if
clear_flags is null return EINVAL. Lastly generic flags get
cleared. */
error_t
channel_clear_flags (struct channel *channel, int flags)
{
error_t err = 0;
int orig = channel->flags, kill = flags & orig;
if (kill & CHANNEL_BACKEND_FLAGS)
{
if (channel->hub->class->clear_flags)
err = (*channel->hub->class->clear_flags) (channel, kill);
else
err = EINVAL;
}
if (! err)
channel->flags &= ~(kill & ~CHANNEL_BACKEND_FLAGS);
return err;
}
/* Reads at most AMOUNT bytes from CHANNEL into BUF and LEN with the usual
return buf semantics. Block until data is available and return 0 bytes
on EOF. If channel is write-only return EPERM, otherwise forward call
to CHANNEL's read method. */
error_t
channel_read (struct channel *channel, size_t amount,
void **buf, size_t *len)
{
if (channel->flags & CHANNEL_WRITEONLY)
return EPERM;
return (*channel->hub->class->read) (channel, amount, buf, len);
}
/* Write LEN bytes of BUF to CHANNEL, AMOUNT is set to the amount actually
witten. Block until data can be written. If channel is read-only
return EPERM, otherwise forward call to CHANNEL's write method. */
error_t
channel_write (struct channel *channel, void *buf, size_t len,
size_t *amount)
{
if (channel->flags & CHANNEL_READONLY)
return EPERM;
return (*channel->hub->class->write) (channel, buf, len, amount);
}
/* Write out any pending data held by CHANNEL in buffers, by forwarding
call to flush method, unless it's null. */
error_t
channel_flush (struct channel *channel)
{
if (channel->hub->class->flush)
return (*channel->hub->class->flush) (channel);
else
return 0;
}
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