xref: /openbmc/qemu/io/channel-null.c (revision 919a0423)
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                         int flags,
64                         Error **errp)
65  {
66      QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
67  
68      if (nioc->closed) {
69          error_setg_errno(errp, EINVAL,
70                           "Channel is closed");
71          return -1;
72      }
73  
74      return 0;
75  }
76  
77  
78  static ssize_t
79  qio_channel_null_writev(QIOChannel *ioc,
80                          const struct iovec *iov,
81                          size_t niov,
82                          int *fds G_GNUC_UNUSED,
83                          size_t nfds G_GNUC_UNUSED,
84                          int flags G_GNUC_UNUSED,
85                          Error **errp)
86  {
87      QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
88  
89      if (nioc->closed) {
90          error_setg_errno(errp, EINVAL,
91                           "Channel is closed");
92          return -1;
93      }
94  
95      return iov_size(iov, niov);
96  }
97  
98  
99  static int
100  qio_channel_null_set_blocking(QIOChannel *ioc G_GNUC_UNUSED,
101                                bool enabled G_GNUC_UNUSED,
102                                Error **errp G_GNUC_UNUSED)
103  {
104      return 0;
105  }
106  
107  
108  static off_t
109  qio_channel_null_seek(QIOChannel *ioc G_GNUC_UNUSED,
110                        off_t offset G_GNUC_UNUSED,
111                        int whence G_GNUC_UNUSED,
112                        Error **errp G_GNUC_UNUSED)
113  {
114      return 0;
115  }
116  
117  
118  static int
119  qio_channel_null_close(QIOChannel *ioc,
120                         Error **errp G_GNUC_UNUSED)
121  {
122      QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
123  
124      nioc->closed = true;
125      return 0;
126  }
127  
128  
129  static void
130  qio_channel_null_set_aio_fd_handler(QIOChannel *ioc G_GNUC_UNUSED,
131                                      AioContext *ctx G_GNUC_UNUSED,
132                                      IOHandler *io_read G_GNUC_UNUSED,
133                                      IOHandler *io_write G_GNUC_UNUSED,
134                                      void *opaque G_GNUC_UNUSED)
135  {
136  }
137  
138  
139  static gboolean
140  qio_channel_null_source_prepare(GSource *source G_GNUC_UNUSED,
141                                  gint *timeout)
142  {
143      *timeout = -1;
144  
145      return TRUE;
146  }
147  
148  
149  static gboolean
150  qio_channel_null_source_check(GSource *source G_GNUC_UNUSED)
151  {
152      return TRUE;
153  }
154  
155  
156  static gboolean
157  qio_channel_null_source_dispatch(GSource *source,
158                                   GSourceFunc callback,
159                                   gpointer user_data)
160  {
161      QIOChannelFunc func = (QIOChannelFunc)callback;
162      QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
163  
164      return (*func)(ssource->ioc,
165                     ssource->condition,
166                     user_data);
167  }
168  
169  
170  static void
171  qio_channel_null_source_finalize(GSource *source)
172  {
173      QIOChannelNullSource *ssource = (QIOChannelNullSource *)source;
174  
175      object_unref(OBJECT(ssource->ioc));
176  }
177  
178  
179  GSourceFuncs qio_channel_null_source_funcs = {
180      qio_channel_null_source_prepare,
181      qio_channel_null_source_check,
182      qio_channel_null_source_dispatch,
183      qio_channel_null_source_finalize
184  };
185  
186  
187  static GSource *
188  qio_channel_null_create_watch(QIOChannel *ioc,
189                                GIOCondition condition)
190  {
191      GSource *source;
192      QIOChannelNullSource *ssource;
193  
194      source = g_source_new(&qio_channel_null_source_funcs,
195                            sizeof(QIOChannelNullSource));
196      ssource = (QIOChannelNullSource *)source;
197  
198      ssource->ioc = ioc;
199      object_ref(OBJECT(ioc));
200  
201      ssource->condition = condition;
202  
203      return source;
204  }
205  
206  
207  static void
208  qio_channel_null_class_init(ObjectClass *klass,
209                              void *class_data G_GNUC_UNUSED)
210  {
211      QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
212  
213      ioc_klass->io_writev = qio_channel_null_writev;
214      ioc_klass->io_readv = qio_channel_null_readv;
215      ioc_klass->io_set_blocking = qio_channel_null_set_blocking;
216      ioc_klass->io_seek = qio_channel_null_seek;
217      ioc_klass->io_close = qio_channel_null_close;
218      ioc_klass->io_create_watch = qio_channel_null_create_watch;
219      ioc_klass->io_set_aio_fd_handler = qio_channel_null_set_aio_fd_handler;
220  }
221  
222  
223  static const TypeInfo qio_channel_null_info = {
224      .parent = TYPE_QIO_CHANNEL,
225      .name = TYPE_QIO_CHANNEL_NULL,
226      .instance_size = sizeof(QIOChannelNull),
227      .instance_init = qio_channel_null_init,
228      .class_init = qio_channel_null_class_init,
229  };
230  
231  
232  static void
233  qio_channel_null_register_types(void)
234  {
235      type_register_static(&qio_channel_null_info);
236  }
237  
238  type_init(qio_channel_null_register_types);
239