xref: /openbmc/qemu/io/channel-buffer.c (revision 84a3a53c) 
1 /*
2  * QEMU I/O channels memory buffer driver
3  *
4  * Copyright (c) 2015 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 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 "io/channel-buffer.h"
22 #include "io/channel-watch.h"
23 #include "qemu/sockets.h"
24 #include "trace.h"
25 
26 QIOChannelBuffer *
27 qio_channel_buffer_new(size_t capacity)
28 {
29     QIOChannelBuffer *ioc;
30 
31     ioc = QIO_CHANNEL_BUFFER(object_new(TYPE_QIO_CHANNEL_BUFFER));
32 
33     if (capacity) {
34         ioc->data = g_new0(char, capacity);
35         ioc->capacity = capacity;
36     }
37 
38     return ioc;
39 }
40 
41 
42 static void qio_channel_buffer_finalize(Object *obj)
43 {
44     QIOChannelBuffer *ioc = QIO_CHANNEL_BUFFER(obj);
45     g_free(ioc->data);
46     ioc->capacity = ioc->usage = ioc->offset = 0;
47 }
48 
49 
50 static ssize_t qio_channel_buffer_readv(QIOChannel *ioc,
51                                         const struct iovec *iov,
52                                         size_t niov,
53                                         int **fds,
54                                         size_t *nfds,
55                                         Error **errp)
56 {
57     QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
58     ssize_t ret = 0;
59     size_t i;
60 
61     for (i = 0; i < niov; i++) {
62         size_t want = iov[i].iov_len;
63         if (bioc->offset >= bioc->usage) {
64             break;
65         }
66         if ((bioc->offset + want) > bioc->usage)  {
67             want = bioc->usage - bioc->offset;
68         }
69         memcpy(iov[i].iov_base, bioc->data + bioc->offset, want);
70         ret += want;
71         bioc->offset += want;
72     }
73 
74     return ret;
75 }
76 
77 static ssize_t qio_channel_buffer_writev(QIOChannel *ioc,
78                                          const struct iovec *iov,
79                                          size_t niov,
80                                          int *fds,
81                                          size_t nfds,
82                                          Error **errp)
83 {
84     QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
85     ssize_t ret = 0;
86     size_t i;
87     size_t towrite = 0;
88 
89     for (i = 0; i < niov; i++) {
90         towrite += iov[i].iov_len;
91     }
92 
93     if ((bioc->offset + towrite) > bioc->capacity) {
94         bioc->capacity = bioc->offset + towrite;
95         bioc->data = g_realloc(bioc->data, bioc->capacity);
96     }
97 
98     if (bioc->offset > bioc->usage) {
99         memset(bioc->data, 0, bioc->offset - bioc->usage);
100         bioc->usage = bioc->offset;
101     }
102 
103     for (i = 0; i < niov; i++) {
104         memcpy(bioc->data + bioc->usage,
105                iov[i].iov_base,
106                iov[i].iov_len);
107         bioc->usage += iov[i].iov_len;
108         bioc->offset += iov[i].iov_len;
109         ret += iov[i].iov_len;
110     }
111 
112     return ret;
113 }
114 
115 static int qio_channel_buffer_set_blocking(QIOChannel *ioc G_GNUC_UNUSED,
116                                            bool enabled G_GNUC_UNUSED,
117                                            Error **errp G_GNUC_UNUSED)
118 {
119     return 0;
120 }
121 
122 
123 static off_t qio_channel_buffer_seek(QIOChannel *ioc,
124                                      off_t offset,
125                                      int whence,
126                                      Error **errp)
127 {
128     QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
129 
130     bioc->offset = offset;
131 
132     return offset;
133 }
134 
135 
136 static int qio_channel_buffer_close(QIOChannel *ioc,
137                                     Error **errp)
138 {
139     QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
140 
141     g_free(bioc->data);
142     bioc->capacity = bioc->usage = bioc->offset = 0;
143 
144     return 0;
145 }
146 
147 
148 typedef struct QIOChannelBufferSource QIOChannelBufferSource;
149 struct QIOChannelBufferSource {
150     GSource parent;
151     QIOChannelBuffer *bioc;
152     GIOCondition condition;
153 };
154 
155 static gboolean
156 qio_channel_buffer_source_prepare(GSource *source,
157                                   gint *timeout)
158 {
159     QIOChannelBufferSource *bsource = (QIOChannelBufferSource *)source;
160 
161     *timeout = -1;
162 
163     return (G_IO_IN | G_IO_OUT) & bsource->condition;
164 }
165 
166 static gboolean
167 qio_channel_buffer_source_check(GSource *source)
168 {
169     QIOChannelBufferSource *bsource = (QIOChannelBufferSource *)source;
170 
171     return (G_IO_IN | G_IO_OUT) & bsource->condition;
172 }
173 
174 static gboolean
175 qio_channel_buffer_source_dispatch(GSource *source,
176                                    GSourceFunc callback,
177                                    gpointer user_data)
178 {
179     QIOChannelFunc func = (QIOChannelFunc)callback;
180     QIOChannelBufferSource *bsource = (QIOChannelBufferSource *)source;
181 
182     return (*func)(QIO_CHANNEL(bsource->bioc),
183                    ((G_IO_IN | G_IO_OUT) & bsource->condition),
184                    user_data);
185 }
186 
187 static void
188 qio_channel_buffer_source_finalize(GSource *source)
189 {
190     QIOChannelBufferSource *ssource = (QIOChannelBufferSource *)source;
191 
192     object_unref(OBJECT(ssource->bioc));
193 }
194 
195 GSourceFuncs qio_channel_buffer_source_funcs = {
196     qio_channel_buffer_source_prepare,
197     qio_channel_buffer_source_check,
198     qio_channel_buffer_source_dispatch,
199     qio_channel_buffer_source_finalize
200 };
201 
202 static GSource *qio_channel_buffer_create_watch(QIOChannel *ioc,
203                                                 GIOCondition condition)
204 {
205     QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
206     QIOChannelBufferSource *ssource;
207     GSource *source;
208 
209     source = g_source_new(&qio_channel_buffer_source_funcs,
210                           sizeof(QIOChannelBufferSource));
211     ssource = (QIOChannelBufferSource *)source;
212 
213     ssource->bioc = bioc;
214     object_ref(OBJECT(bioc));
215 
216     ssource->condition = condition;
217 
218     return source;
219 }
220 
221 
222 static void qio_channel_buffer_class_init(ObjectClass *klass,
223                                           void *class_data G_GNUC_UNUSED)
224 {
225     QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
226 
227     ioc_klass->io_writev = qio_channel_buffer_writev;
228     ioc_klass->io_readv = qio_channel_buffer_readv;
229     ioc_klass->io_set_blocking = qio_channel_buffer_set_blocking;
230     ioc_klass->io_seek = qio_channel_buffer_seek;
231     ioc_klass->io_close = qio_channel_buffer_close;
232     ioc_klass->io_create_watch = qio_channel_buffer_create_watch;
233 }
234 
235 static const TypeInfo qio_channel_buffer_info = {
236     .parent = TYPE_QIO_CHANNEL,
237     .name = TYPE_QIO_CHANNEL_BUFFER,
238     .instance_size = sizeof(QIOChannelBuffer),
239     .instance_finalize = qio_channel_buffer_finalize,
240     .class_init = qio_channel_buffer_class_init,
241 };
242 
243 static void qio_channel_buffer_register_types(void)
244 {
245     type_register_static(&qio_channel_buffer_info);
246 }
247 
248 type_init(qio_channel_buffer_register_types);
249