xref: /openbmc/qemu/chardev/char-io.c (revision 1c15dd63)
1  /*
2   * QEMU System Emulator
3   *
4   * Copyright (c) 2003-2008 Fabrice Bellard
5   *
6   * Permission is hereby granted, free of charge, to any person obtaining a copy
7   * of this software and associated documentation files (the "Software"), to deal
8   * in the Software without restriction, including without limitation the rights
9   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10   * copies of the Software, and to permit persons to whom the Software is
11   * furnished to do so, subject to the following conditions:
12   *
13   * The above copyright notice and this permission notice shall be included in
14   * all copies or substantial portions of the Software.
15   *
16   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22   * THE SOFTWARE.
23   */
24  #include "qemu/osdep.h"
25  #include "chardev/char-io.h"
26  
27  typedef struct IOWatchPoll {
28      GSource parent;
29  
30      QIOChannel *ioc;
31      GSource *src;
32  
33      IOCanReadHandler *fd_can_read;
34      GSourceFunc fd_read;
35      void *opaque;
36      GMainContext *context;
37  } IOWatchPoll;
38  
39  static IOWatchPoll *io_watch_poll_from_source(GSource *source)
40  {
41      return container_of(source, IOWatchPoll, parent);
42  }
43  
44  static gboolean io_watch_poll_prepare(GSource *source,
45                                        gint *timeout)
46  {
47      IOWatchPoll *iwp = io_watch_poll_from_source(source);
48      bool now_active = iwp->fd_can_read(iwp->opaque) > 0;
49      bool was_active = iwp->src != NULL;
50      if (was_active == now_active) {
51          return FALSE;
52      }
53  
54      /*
55       * We do not register the QIOChannel watch as a child GSource.
56       * The 'prepare' function on the parent GSource will be
57       * skipped if a child GSource's 'prepare' function indicates
58       * readiness. We need this prepare function be guaranteed
59       * to run on *every* iteration of the main loop, because
60       * it is critical to ensure we remove the QIOChannel watch
61       * if 'fd_can_read' indicates the frontend cannot receive
62       * more data.
63       */
64      if (now_active) {
65          iwp->src = qio_channel_create_watch(
66              iwp->ioc, G_IO_IN | G_IO_ERR | G_IO_HUP | G_IO_NVAL);
67          g_source_set_callback(iwp->src, iwp->fd_read, iwp->opaque, NULL);
68          g_source_attach(iwp->src, iwp->context);
69      } else {
70          g_source_destroy(iwp->src);
71          g_source_unref(iwp->src);
72          iwp->src = NULL;
73      }
74      return FALSE;
75  }
76  
77  static gboolean io_watch_poll_check(GSource *source)
78  {
79      return FALSE;
80  }
81  
82  static gboolean io_watch_poll_dispatch(GSource *source, GSourceFunc callback,
83                                         gpointer user_data)
84  {
85      abort();
86  }
87  
88  static void io_watch_poll_finalize(GSource *source)
89  {
90      IOWatchPoll *iwp = io_watch_poll_from_source(source);
91      if (iwp->src) {
92          g_source_destroy(iwp->src);
93          g_source_unref(iwp->src);
94          iwp->src = NULL;
95      }
96  }
97  
98  static GSourceFuncs io_watch_poll_funcs = {
99      .prepare = io_watch_poll_prepare,
100      .check = io_watch_poll_check,
101      .dispatch = io_watch_poll_dispatch,
102      .finalize = io_watch_poll_finalize,
103  };
104  
105  GSource *io_add_watch_poll(Chardev *chr,
106                          QIOChannel *ioc,
107                          IOCanReadHandler *fd_can_read,
108                          QIOChannelFunc fd_read,
109                          gpointer user_data,
110                          GMainContext *context)
111  {
112      IOWatchPoll *iwp;
113      char *name;
114  
115      iwp = (IOWatchPoll *) g_source_new(&io_watch_poll_funcs,
116                                         sizeof(IOWatchPoll));
117      iwp->fd_can_read = fd_can_read;
118      iwp->opaque = user_data;
119      iwp->ioc = ioc;
120      iwp->fd_read = (GSourceFunc) fd_read;
121      iwp->src = NULL;
122      iwp->context = context;
123  
124      name = g_strdup_printf("chardev-iowatch-%s", chr->label);
125      g_source_set_name((GSource *)iwp, name);
126      g_free(name);
127  
128      g_source_attach(&iwp->parent, context);
129      g_source_unref(&iwp->parent);
130      return (GSource *)iwp;
131  }
132  
133  static void io_remove_watch_poll(GSource *source)
134  {
135      IOWatchPoll *iwp;
136  
137      iwp = io_watch_poll_from_source(source);
138      g_source_destroy(&iwp->parent);
139  }
140  
141  void remove_fd_in_watch(Chardev *chr)
142  {
143      if (chr->gsource) {
144          io_remove_watch_poll(chr->gsource);
145          chr->gsource = NULL;
146      }
147  }
148  
149  int io_channel_send_full(QIOChannel *ioc,
150                           const void *buf, size_t len,
151                           int *fds, size_t nfds)
152  {
153      size_t offset = 0;
154  
155      while (offset < len) {
156          ssize_t ret = 0;
157          struct iovec iov = { .iov_base = (char *)buf + offset,
158                               .iov_len = len - offset };
159  
160          ret = qio_channel_writev_full(
161              ioc, &iov, 1,
162              fds, nfds, 0, NULL);
163          if (ret == QIO_CHANNEL_ERR_BLOCK) {
164              if (offset) {
165                  return offset;
166              }
167  
168              errno = EAGAIN;
169              return -1;
170          } else if (ret < 0) {
171              errno = EINVAL;
172              return -1;
173          }
174  
175          offset += ret;
176      }
177  
178      return offset;
179  }
180  
181  int io_channel_send(QIOChannel *ioc, const void *buf, size_t len)
182  {
183      return io_channel_send_full(ioc, buf, len, NULL, 0);
184  }
185