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>
This commit is contained in:
Daniel P. Berrangé
committed by
Dr. David Alan Gilbert
Dr. David Alan Gilbert
parent
1abaec9a1b
commit
87e4276449
@@ -0,0 +1,237 @@
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/*
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* QEMU I/O channels null driver
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*
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* Copyright (c) 2022 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* 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, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "io/channel-null.h"
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#include "io/channel-watch.h"
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#include "qapi/error.h"
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#include "trace.h"
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#include "qemu/iov.h"
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typedef struct QIOChannelNullSource QIOChannelNullSource;
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struct QIOChannelNullSource {
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GSource parent;
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QIOChannel *ioc;
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GIOCondition condition;
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};
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QIOChannelNull *
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qio_channel_null_new(void)
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{
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QIOChannelNull *ioc;
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ioc = QIO_CHANNEL_NULL(object_new(TYPE_QIO_CHANNEL_NULL));
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trace_qio_channel_null_new(ioc);
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return ioc;
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}
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static void
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qio_channel_null_init(Object *obj)
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{
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QIOChannelNull *ioc = QIO_CHANNEL_NULL(obj);
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ioc->closed = false;
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}
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static ssize_t
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qio_channel_null_readv(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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int **fds G_GNUC_UNUSED,
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size_t *nfds G_GNUC_UNUSED,
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Error **errp)
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{
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QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
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if (nioc->closed) {
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error_setg_errno(errp, EINVAL,
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"Channel is closed");
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return -1;
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}
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return 0;
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}
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static ssize_t
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qio_channel_null_writev(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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int *fds G_GNUC_UNUSED,
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size_t nfds G_GNUC_UNUSED,
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int flags G_GNUC_UNUSED,
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Error **errp)
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{
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QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
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if (nioc->closed) {
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error_setg_errno(errp, EINVAL,
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"Channel is closed");
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return -1;
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}
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return iov_size(iov, niov);
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}
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static int
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qio_channel_null_set_blocking(QIOChannel *ioc G_GNUC_UNUSED,
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bool enabled G_GNUC_UNUSED,
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Error **errp G_GNUC_UNUSED)
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{
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return 0;
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}
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static off_t
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qio_channel_null_seek(QIOChannel *ioc G_GNUC_UNUSED,
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off_t offset G_GNUC_UNUSED,
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int whence G_GNUC_UNUSED,
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Error **errp G_GNUC_UNUSED)
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{
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return 0;
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}
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static int
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qio_channel_null_close(QIOChannel *ioc,
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Error **errp G_GNUC_UNUSED)
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{
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QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
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nioc->closed = true;
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return 0;
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}
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static void
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qio_channel_null_set_aio_fd_handler(QIOChannel *ioc G_GNUC_UNUSED,
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AioContext *ctx G_GNUC_UNUSED,
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IOHandler *io_read G_GNUC_UNUSED,
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IOHandler *io_write G_GNUC_UNUSED,
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void *opaque G_GNUC_UNUSED)
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{
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}
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static gboolean
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qio_channel_null_source_prepare(GSource *source G_GNUC_UNUSED,
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gint *timeout)
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{
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*timeout = -1;
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return TRUE;
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}
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static gboolean
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qio_channel_null_source_check(GSource *source G_GNUC_UNUSED)
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{
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return TRUE;
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}
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static gboolean
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qio_channel_null_source_dispatch(GSource *source,
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GSourceFunc callback,
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gpointer user_data)
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{
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QIOChannelFunc func = (QIOChannelFunc)callback;
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QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
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return (*func)(ssource->ioc,
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ssource->condition,
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user_data);
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}
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static void
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qio_channel_null_source_finalize(GSource *source)
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{
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QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
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object_unref(OBJECT(ssource->ioc));
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}
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GSourceFuncs qio_channel_null_source_funcs = {
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qio_channel_null_source_prepare,
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qio_channel_null_source_check,
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qio_channel_null_source_dispatch,
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qio_channel_null_source_finalize
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};
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static GSource *
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qio_channel_null_create_watch(QIOChannel *ioc,
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GIOCondition condition)
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{
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GSource *source;
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QIOChannelNullSource *ssource;
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source = g_source_new(&qio_channel_null_source_funcs,
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sizeof(QIOChannelNullSource));
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ssource = (QIOChannelNullSource *)source;
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ssource->ioc = ioc;
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object_ref(OBJECT(ioc));
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ssource->condition = condition;
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return source;
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}
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static void
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qio_channel_null_class_init(ObjectClass *klass,
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void *class_data G_GNUC_UNUSED)
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{
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QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
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ioc_klass->io_writev = qio_channel_null_writev;
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ioc_klass->io_readv = qio_channel_null_readv;
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ioc_klass->io_set_blocking = qio_channel_null_set_blocking;
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ioc_klass->io_seek = qio_channel_null_seek;
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ioc_klass->io_close = qio_channel_null_close;
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ioc_klass->io_create_watch = qio_channel_null_create_watch;
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ioc_klass->io_set_aio_fd_handler = qio_channel_null_set_aio_fd_handler;
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}
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static const TypeInfo qio_channel_null_info = {
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.parent = TYPE_QIO_CHANNEL,
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.name = TYPE_QIO_CHANNEL_NULL,
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.instance_size = sizeof(QIOChannelNull),
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.instance_init = qio_channel_null_init,
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.class_init = qio_channel_null_class_init,
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};
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static void
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qio_channel_null_register_types(void)
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{
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type_register_static(&qio_channel_null_info);
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}
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type_init(qio_channel_null_register_types);
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@@ -3,6 +3,7 @@ io_ss.add(files(
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'channel-buffer.c',
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'channel-command.c',
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'channel-file.c',
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'channel-null.c',
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'channel-socket.c',
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'channel-tls.c',
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'channel-util.c',
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@@ -10,6 +10,9 @@ qio_task_thread_result(void *task) "Task thread result task=%p"
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qio_task_thread_source_attach(void *task, void *source) "Task thread source attach task=%p source=%p"
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qio_task_thread_source_cancel(void *task, void *source) "Task thread source cancel task=%p source=%p"
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# channel-null.c
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qio_channel_null_new(void *ioc) "Null new ioc=%p"
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# channel-socket.c
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qio_channel_socket_new(void *ioc) "Socket new ioc=%p"
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qio_channel_socket_new_fd(void *ioc, int fd) "Socket new ioc=%p fd=%d"
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