new file mode 100644
@@ -0,0 +1,55 @@
+/*
+ * 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/>.
+ *
+ */
+
+#ifndef QIO_CHANNEL_FILE_H
+#define QIO_CHANNEL_FILE_H
+
+#include "io/channel.h"
+#include "qom/object.h"
+
+#define TYPE_QIO_CHANNEL_NULL "qio-channel-null"
+OBJECT_DECLARE_SIMPLE_TYPE(QIOChannelNull, QIO_CHANNEL_NULL)
+
+
+/**
+ * QIOChannelNull:
+ *
+ * The QIOChannelNull object provides a channel implementation
+ * that discards all writes and returns EOF for all reads.
+ */
+
+struct QIOChannelNull {
+ QIOChannel parent;
+ bool closed;
+};
+
+
+/**
+ * qio_channel_null_new:
+ *
+ * Create a new IO channel object that discards all writes
+ * and returns EOF for all reads.
+ *
+ * Returns: the new channel object
+ */
+QIOChannelNull *
+qio_channel_null_new(void);
+
+#endif /* QIO_CHANNEL_NULL_H */
new file mode 100644
@@ -0,0 +1,237 @@
+/*
+ * 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);
@@ -3,6 +3,7 @@ io_ss.add(files(
'channel-buffer.c',
'channel-command.c',
'channel-file.c',
+ 'channel-null.c',
'channel-socket.c',
'channel-tls.c',
'channel-util.c',
@@ -10,6 +10,9 @@ qio_task_thread_result(void *task) "Task thread result task=%p"
qio_task_thread_source_attach(void *task, void *source) "Task thread source attach task=%p source=%p"
qio_task_thread_source_cancel(void *task, void *source) "Task thread source cancel task=%p source=%p"
+# channel-null.c
+qio_channel_null_new(void *ioc) "Null new ioc=%p"
+
# channel-socket.c
qio_channel_socket_new(void *ioc) "Socket new ioc=%p"
qio_channel_socket_new_fd(void *ioc, int fd) "Socket new ioc=%p fd=%d"
@@ -88,6 +88,7 @@ if have_block
'test-io-channel-file': ['io-channel-helpers.c', io],
'test-io-channel-command': ['io-channel-helpers.c', io],
'test-io-channel-buffer': ['io-channel-helpers.c', io],
+ 'test-io-channel-null': [io],
'test-crypto-ivgen': [io],
'test-crypto-afsplit': [io],
'test-crypto-block': [io],
new file mode 100644
@@ -0,0 +1,95 @@
+/*
+ * QEMU I/O channel null test
+ *
+ * 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 "qapi/error.h"
+
+static gboolean test_io_channel_watch(QIOChannel *ioc,
+ GIOCondition condition,
+ gpointer opaque)
+{
+ GIOCondition *gotcond = opaque;
+ *gotcond = condition;
+ return G_SOURCE_REMOVE;
+}
+
+static void test_io_channel_null_io(void)
+{
+ g_autoptr(QIOChannelNull) null = qio_channel_null_new();
+ char buf[1024];
+ GIOCondition gotcond = 0;
+ Error *local_err = NULL;
+
+ g_assert(qio_channel_write(QIO_CHANNEL(null),
+ "Hello World", 11,
+ &error_abort) == 11);
+
+ g_assert(qio_channel_read(QIO_CHANNEL(null),
+ buf, sizeof(buf),
+ &error_abort) == 0);
+
+ qio_channel_add_watch(QIO_CHANNEL(null),
+ G_IO_IN,
+ test_io_channel_watch,
+ &gotcond,
+ NULL);
+
+ g_main_context_iteration(NULL, false);
+
+ g_assert(gotcond == G_IO_IN);
+
+ qio_channel_add_watch(QIO_CHANNEL(null),
+ G_IO_IN | G_IO_OUT,
+ test_io_channel_watch,
+ &gotcond,
+ NULL);
+
+ g_main_context_iteration(NULL, false);
+
+ g_assert(gotcond == (G_IO_IN | G_IO_OUT));
+
+ qio_channel_close(QIO_CHANNEL(null), &error_abort);
+
+ g_assert(qio_channel_write(QIO_CHANNEL(null),
+ "Hello World", 11,
+ &local_err) == -1);
+ g_assert_nonnull(local_err);
+
+ g_clear_pointer(&local_err, error_free);
+
+ g_assert(qio_channel_read(QIO_CHANNEL(null),
+ buf, sizeof(buf),
+ &local_err) == -1);
+ g_assert_nonnull(local_err);
+
+ g_clear_pointer(&local_err, error_free);
+}
+
+int main(int argc, char **argv)
+{
+ module_call_init(MODULE_INIT_QOM);
+
+ g_test_init(&argc, &argv, NULL);
+
+ g_test_add_func("/io/channel/null/io", test_io_channel_null_io);
+
+ return g_test_run();
+}
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> --- include/io/channel-null.h | 55 +++++++ io/channel-null.c | 237 ++++++++++++++++++++++++++++++ io/meson.build | 1 + io/trace-events | 3 + tests/unit/meson.build | 1 + tests/unit/test-io-channel-null.c | 95 ++++++++++++ 6 files changed, 392 insertions(+) create mode 100644 include/io/channel-null.h create mode 100644 io/channel-null.c create mode 100644 tests/unit/test-io-channel-null.c