io/channel-null.c

   1 /*
   2  * QEMU I/O channels null driver
   3  *
   4  * Copyright (c) 2022 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "io/channel-null.h"
  23 #include "io/channel-watch.h"
  24 #include "qapi/error.h"
  25 #include "trace.h"
  26 #include "qemu/iov.h"
  27
  28 typedef struct QIOChannelNullSource QIOChannelNullSource;
  29 struct QIOChannelNullSource {
  30     GSource parent;
  31     QIOChannel *ioc;
  32     GIOCondition condition;
  33 };
  34
  35
  36 QIOChannelNull *
  37 qio_channel_null_new(void)
  38 {
  39     QIOChannelNull *ioc;
  40
  41     ioc = QIO_CHANNEL_NULL(object_new(TYPE_QIO_CHANNEL_NULL));
  42
  43     trace_qio_channel_null_new(ioc);
  44
  45     return ioc;
  46 }
  47
  48
  49 static void
  50 qio_channel_null_init(Object *obj)
  51 {
  52     QIOChannelNull *ioc = QIO_CHANNEL_NULL(obj);
  53     ioc->closed = false;
  54 }
  55
  56
  57 static ssize_t
  58 qio_channel_null_readv(QIOChannel *ioc,
  59                        const struct iovec *iov,
  60                        size_t niov,
  61                        int **fds G_GNUC_UNUSED,
  62                        size_t *nfds G_GNUC_UNUSED,
  63                        Error **errp)
  64 {
  65     QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
  66
  67     if (nioc->closed) {
  68         error_setg_errno(errp, EINVAL,
  69                          "Channel is closed");
  70         return -1;
  71     }
  72
  73     return 0;
  74 }
  75
  76
  77 static ssize_t
  78 qio_channel_null_writev(QIOChannel *ioc,
  79                         const struct iovec *iov,
  80                         size_t niov,
  81                         int *fds G_GNUC_UNUSED,
  82                         size_t nfds G_GNUC_UNUSED,
  83                         int flags G_GNUC_UNUSED,
  84                         Error **errp)
  85 {
  86     QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
  87
  88     if (nioc->closed) {
  89         error_setg_errno(errp, EINVAL,
  90                          "Channel is closed");
  91         return -1;
  92     }
  93
  94     return iov_size(iov, niov);
  95 }
  96
  97
  98 static int
  99 qio_channel_null_set_blocking(QIOChannel *ioc G_GNUC_UNUSED,
 100                               bool enabled G_GNUC_UNUSED,
 101                               Error **errp G_GNUC_UNUSED)
 102 {
 103     return 0;
 104 }
 105
 106
 107 static off_t
 108 qio_channel_null_seek(QIOChannel *ioc G_GNUC_UNUSED,
 109                       off_t offset G_GNUC_UNUSED,
 110                       int whence G_GNUC_UNUSED,
 111                       Error **errp G_GNUC_UNUSED)
 112 {
 113     return 0;
 114 }
 115
 116
 117 static int
 118 qio_channel_null_close(QIOChannel *ioc,
 119                        Error **errp G_GNUC_UNUSED)
 120 {
 121     QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
 122
 123     nioc->closed = true;
 124     return 0;
 125 }
 126
 127
 128 static void
 129 qio_channel_null_set_aio_fd_handler(QIOChannel *ioc G_GNUC_UNUSED,
 130                                     AioContext *ctx G_GNUC_UNUSED,
 131                                     IOHandler *io_read G_GNUC_UNUSED,
 132                                     IOHandler *io_write G_GNUC_UNUSED,
 133                                     void *opaque G_GNUC_UNUSED)
 134 {
 135 }
 136
 137
 138 static gboolean
 139 qio_channel_null_source_prepare(GSource *source G_GNUC_UNUSED,
 140                                 gint *timeout)
 141 {
 142     *timeout = -1;
 143
 144     return TRUE;
 145 }
 146
 147
 148 static gboolean
 149 qio_channel_null_source_check(GSource *source G_GNUC_UNUSED)
 150 {
 151     return TRUE;
 152 }
 153
 154
 155 static gboolean
 156 qio_channel_null_source_dispatch(GSource *source,
 157                                  GSourceFunc callback,
 158                                  gpointer user_data)
 159 {
 160     QIOChannelFunc func = (QIOChannelFunc)callback;
 161     QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
 162
 163     return (*func)(ssource->ioc,
 164                    ssource->condition,
 165                    user_data);
 166 }
 167
 168
 169 static void
 170 qio_channel_null_source_finalize(GSource *source)
 171 {
 172     QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
 173
 174     object_unref(OBJECT(ssource->ioc));
 175 }
 176
 177
 178 GSourceFuncs qio_channel_null_source_funcs = {
 179     qio_channel_null_source_prepare,
 180     qio_channel_null_source_check,
 181     qio_channel_null_source_dispatch,
 182     qio_channel_null_source_finalize
 183 };
 184
 185
 186 static GSource *
 187 qio_channel_null_create_watch(QIOChannel *ioc,
 188                               GIOCondition condition)
 189 {
 190     GSource *source;
 191     QIOChannelNullSource *ssource;
 192
 193     source = g_source_new(&qio_channel_null_source_funcs,
 194                           sizeof(QIOChannelNullSource));
 195     ssource = (QIOChannelNullSource *)source;
 196
 197     ssource->ioc = ioc;
 198     object_ref(OBJECT(ioc));
 199
 200     ssource->condition = condition;
 201
 202     return source;
 203 }
 204
 205
 206 static void
 207 qio_channel_null_class_init(ObjectClass *klass,
 208                             void *class_data G_GNUC_UNUSED)
 209 {
 210     QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
 211
 212     ioc_klass->io_writev = qio_channel_null_writev;
 213     ioc_klass->io_readv = qio_channel_null_readv;
 214     ioc_klass->io_set_blocking = qio_channel_null_set_blocking;
 215     ioc_klass->io_seek = qio_channel_null_seek;
 216     ioc_klass->io_close = qio_channel_null_close;
 217     ioc_klass->io_create_watch = qio_channel_null_create_watch;
 218     ioc_klass->io_set_aio_fd_handler = qio_channel_null_set_aio_fd_handler;
 219 }
 220
 221
 222 static const TypeInfo qio_channel_null_info = {
 223     .parent = TYPE_QIO_CHANNEL,
 224     .name = TYPE_QIO_CHANNEL_NULL,
 225     .instance_size = sizeof(QIOChannelNull),
 226     .instance_init = qio_channel_null_init,
 227     .class_init = qio_channel_null_class_init,
 228 };
 229
 230
 231 static void
 232 qio_channel_null_register_types(void)
 233 {
 234     type_register_static(&qio_channel_null_info);
 235 }
 236
 237 type_init(qio_channel_null_register_types);