qemu/io/channel-null.c
Daniel P. Berrangé 87e4276449 io: add a QIOChannelNull equivalent to /dev/null
This is for code which needs a portable equivalent to a QIOChannelFile
connected to /dev/null.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-06-22 18:11:21 +01:00

238 lines
5.8 KiB
C

/*
* QEMU I/O channels null driver
*
* Copyright (c) 2022 Red Hat, Inc.
*
* 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 library 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, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "io/channel-null.h"
#include "io/channel-watch.h"
#include "qapi/error.h"
#include "trace.h"
#include "qemu/iov.h"
typedef struct QIOChannelNullSource QIOChannelNullSource;
struct QIOChannelNullSource {
GSource parent;
QIOChannel *ioc;
GIOCondition condition;
};
QIOChannelNull *
qio_channel_null_new(void)
{
QIOChannelNull *ioc;
ioc = QIO_CHANNEL_NULL(object_new(TYPE_QIO_CHANNEL_NULL));
trace_qio_channel_null_new(ioc);
return ioc;
}
static void
qio_channel_null_init(Object *obj)
{
QIOChannelNull *ioc = QIO_CHANNEL_NULL(obj);
ioc->closed = false;
}
static ssize_t
qio_channel_null_readv(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int **fds G_GNUC_UNUSED,
size_t *nfds G_GNUC_UNUSED,
Error **errp)
{
QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
if (nioc->closed) {
error_setg_errno(errp, EINVAL,
"Channel is closed");
return -1;
}
return 0;
}
static ssize_t
qio_channel_null_writev(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int *fds G_GNUC_UNUSED,
size_t nfds G_GNUC_UNUSED,
int flags G_GNUC_UNUSED,
Error **errp)
{
QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
if (nioc->closed) {
error_setg_errno(errp, EINVAL,
"Channel is closed");
return -1;
}
return iov_size(iov, niov);
}
static int
qio_channel_null_set_blocking(QIOChannel *ioc G_GNUC_UNUSED,
bool enabled G_GNUC_UNUSED,
Error **errp G_GNUC_UNUSED)
{
return 0;
}
static off_t
qio_channel_null_seek(QIOChannel *ioc G_GNUC_UNUSED,
off_t offset G_GNUC_UNUSED,
int whence G_GNUC_UNUSED,
Error **errp G_GNUC_UNUSED)
{
return 0;
}
static int
qio_channel_null_close(QIOChannel *ioc,
Error **errp G_GNUC_UNUSED)
{
QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
nioc->closed = true;
return 0;
}
static void
qio_channel_null_set_aio_fd_handler(QIOChannel *ioc G_GNUC_UNUSED,
AioContext *ctx G_GNUC_UNUSED,
IOHandler *io_read G_GNUC_UNUSED,
IOHandler *io_write G_GNUC_UNUSED,
void *opaque G_GNUC_UNUSED)
{
}
static gboolean
qio_channel_null_source_prepare(GSource *source G_GNUC_UNUSED,
gint *timeout)
{
*timeout = -1;
return TRUE;
}
static gboolean
qio_channel_null_source_check(GSource *source G_GNUC_UNUSED)
{
return TRUE;
}
static gboolean
qio_channel_null_source_dispatch(GSource *source,
GSourceFunc callback,
gpointer user_data)
{
QIOChannelFunc func = (QIOChannelFunc)callback;
QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
return (*func)(ssource->ioc,
ssource->condition,
user_data);
}
static void
qio_channel_null_source_finalize(GSource *source)
{
QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
object_unref(OBJECT(ssource->ioc));
}
GSourceFuncs qio_channel_null_source_funcs = {
qio_channel_null_source_prepare,
qio_channel_null_source_check,
qio_channel_null_source_dispatch,
qio_channel_null_source_finalize
};
static GSource *
qio_channel_null_create_watch(QIOChannel *ioc,
GIOCondition condition)
{
GSource *source;
QIOChannelNullSource *ssource;
source = g_source_new(&qio_channel_null_source_funcs,
sizeof(QIOChannelNullSource));
ssource = (QIOChannelNullSource *)source;
ssource->ioc = ioc;
object_ref(OBJECT(ioc));
ssource->condition = condition;
return source;
}
static void
qio_channel_null_class_init(ObjectClass *klass,
void *class_data G_GNUC_UNUSED)
{
QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
ioc_klass->io_writev = qio_channel_null_writev;
ioc_klass->io_readv = qio_channel_null_readv;
ioc_klass->io_set_blocking = qio_channel_null_set_blocking;
ioc_klass->io_seek = qio_channel_null_seek;
ioc_klass->io_close = qio_channel_null_close;
ioc_klass->io_create_watch = qio_channel_null_create_watch;
ioc_klass->io_set_aio_fd_handler = qio_channel_null_set_aio_fd_handler;
}
static const TypeInfo qio_channel_null_info = {
.parent = TYPE_QIO_CHANNEL,
.name = TYPE_QIO_CHANNEL_NULL,
.instance_size = sizeof(QIOChannelNull),
.instance_init = qio_channel_null_init,
.class_init = qio_channel_null_class_init,
};
static void
qio_channel_null_register_types(void)
{
type_register_static(&qio_channel_null_info);
}
type_init(qio_channel_null_register_types);