xref: /openbmc/qemu/chardev/char-fd.c (revision 3973e7ae)
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 
25 #include "qemu/osdep.h"
26 #include "qemu-common.h"
27 #include "qemu/module.h"
28 #include "qemu/sockets.h"
29 #include "qapi/error.h"
30 #include "chardev/char.h"
31 #include "chardev/char-fe.h"
32 #include "io/channel-file.h"
33 
34 #include "chardev/char-fd.h"
35 #include "chardev/char-io.h"
36 
37 /* Called with chr_write_lock held.  */
38 static int fd_chr_write(Chardev *chr, const uint8_t *buf, int len)
39 {
40     FDChardev *s = FD_CHARDEV(chr);
41 
42     if (!s->ioc_out) {
43         return -1;
44     }
45 
46     return io_channel_send(s->ioc_out, buf, len);
47 }
48 
49 static gboolean fd_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
50 {
51     Chardev *chr = CHARDEV(opaque);
52     FDChardev *s = FD_CHARDEV(opaque);
53     int len;
54     uint8_t buf[CHR_READ_BUF_LEN];
55     ssize_t ret;
56 
57     len = sizeof(buf);
58     if (len > s->max_size) {
59         len = s->max_size;
60     }
61     if (len == 0) {
62         return TRUE;
63     }
64 
65     ret = qio_channel_read(
66         chan, (gchar *)buf, len, NULL);
67     if (ret == 0) {
68         remove_fd_in_watch(chr);
69         qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
70         return FALSE;
71     }
72     if (ret > 0) {
73         qemu_chr_be_write(chr, buf, ret);
74     }
75 
76     return TRUE;
77 }
78 
79 static int fd_chr_read_poll(void *opaque)
80 {
81     Chardev *chr = CHARDEV(opaque);
82     FDChardev *s = FD_CHARDEV(opaque);
83 
84     s->max_size = qemu_chr_be_can_write(chr);
85     return s->max_size;
86 }
87 
88 typedef struct FDSource {
89     GSource parent;
90 
91     GIOCondition cond;
92 } FDSource;
93 
94 static gboolean
95 fd_source_prepare(GSource *source,
96                   gint *timeout_)
97 {
98     FDSource *src = (FDSource *)source;
99 
100     return src->cond != 0;
101 }
102 
103 static gboolean
104 fd_source_check(GSource *source)
105 {
106     FDSource *src = (FDSource *)source;
107 
108     return src->cond != 0;
109 }
110 
111 static gboolean
112 fd_source_dispatch(GSource *source, GSourceFunc callback,
113                    gpointer user_data)
114 {
115     FDSource *src = (FDSource *)source;
116     FEWatchFunc func = (FEWatchFunc)callback;
117     gboolean ret = G_SOURCE_CONTINUE;
118 
119     if (src->cond) {
120         ret = func(NULL, src->cond, user_data);
121         src->cond = 0;
122     }
123 
124     return ret;
125 }
126 
127 static GSourceFuncs fd_source_funcs = {
128   fd_source_prepare,
129   fd_source_check,
130   fd_source_dispatch,
131   NULL, NULL, NULL
132 };
133 
134 static GSource *fd_source_new(FDChardev *chr)
135 {
136     return g_source_new(&fd_source_funcs, sizeof(FDSource));
137 }
138 
139 static gboolean child_func(GIOChannel *source,
140                            GIOCondition condition,
141                            gpointer data)
142 {
143     FDSource *parent = data;
144 
145     parent->cond |= condition;
146 
147     return G_SOURCE_CONTINUE;
148 }
149 
150 static GSource *fd_chr_add_watch(Chardev *chr, GIOCondition cond)
151 {
152     FDChardev *s = FD_CHARDEV(chr);
153     g_autoptr(GSource) source = fd_source_new(s);
154 
155     if (s->ioc_out) {
156         g_autoptr(GSource) child = qio_channel_create_watch(s->ioc_out, cond & ~G_IO_IN);
157         g_source_set_callback(child, (GSourceFunc)child_func, source, NULL);
158         g_source_add_child_source(source, child);
159     }
160     if (s->ioc_in) {
161         g_autoptr(GSource) child = qio_channel_create_watch(s->ioc_in, cond & ~G_IO_OUT);
162         g_source_set_callback(child, (GSourceFunc)child_func, source, NULL);
163         g_source_add_child_source(source, child);
164     }
165 
166     return g_steal_pointer(&source);
167 }
168 
169 static void fd_chr_update_read_handler(Chardev *chr)
170 {
171     FDChardev *s = FD_CHARDEV(chr);
172 
173     remove_fd_in_watch(chr);
174     if (s->ioc_in) {
175         chr->gsource = io_add_watch_poll(chr, s->ioc_in,
176                                            fd_chr_read_poll,
177                                            fd_chr_read, chr,
178                                            chr->gcontext);
179     }
180 }
181 
182 static void char_fd_finalize(Object *obj)
183 {
184     Chardev *chr = CHARDEV(obj);
185     FDChardev *s = FD_CHARDEV(obj);
186 
187     remove_fd_in_watch(chr);
188     if (s->ioc_in) {
189         object_unref(OBJECT(s->ioc_in));
190     }
191     if (s->ioc_out) {
192         object_unref(OBJECT(s->ioc_out));
193     }
194 
195     qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
196 }
197 
198 int qmp_chardev_open_file_source(char *src, int flags, Error **errp)
199 {
200     int fd = -1;
201 
202     TFR(fd = qemu_open_old(src, flags, 0666));
203     if (fd == -1) {
204         error_setg_file_open(errp, errno, src);
205     }
206     return fd;
207 }
208 
209 /* open a character device to a unix fd */
210 void qemu_chr_open_fd(Chardev *chr,
211                       int fd_in, int fd_out)
212 {
213     FDChardev *s = FD_CHARDEV(chr);
214     g_autofree char *name = NULL;
215 
216     if (fd_out >= 0) {
217         qemu_set_nonblock(fd_out);
218     }
219 
220     if (fd_out == fd_in && fd_in >= 0) {
221         s->ioc_in = QIO_CHANNEL(qio_channel_file_new_fd(fd_in));
222         name = g_strdup_printf("chardev-file-%s", chr->label);
223         qio_channel_set_name(QIO_CHANNEL(s->ioc_in), name);
224         s->ioc_out = QIO_CHANNEL(object_ref(s->ioc_in));
225         return;
226     }
227 
228     if (fd_in >= 0) {
229         s->ioc_in = QIO_CHANNEL(qio_channel_file_new_fd(fd_in));
230         name = g_strdup_printf("chardev-file-in-%s", chr->label);
231         qio_channel_set_name(QIO_CHANNEL(s->ioc_in), name);
232     }
233 
234     if (fd_out >= 0) {
235         s->ioc_out = QIO_CHANNEL(qio_channel_file_new_fd(fd_out));
236         g_free(name);
237         name = g_strdup_printf("chardev-file-out-%s", chr->label);
238         qio_channel_set_name(QIO_CHANNEL(s->ioc_out), name);
239     }
240 }
241 
242 static void char_fd_class_init(ObjectClass *oc, void *data)
243 {
244     ChardevClass *cc = CHARDEV_CLASS(oc);
245 
246     cc->chr_add_watch = fd_chr_add_watch;
247     cc->chr_write = fd_chr_write;
248     cc->chr_update_read_handler = fd_chr_update_read_handler;
249 }
250 
251 static const TypeInfo char_fd_type_info = {
252     .name = TYPE_CHARDEV_FD,
253     .parent = TYPE_CHARDEV,
254     .instance_size = sizeof(FDChardev),
255     .instance_finalize = char_fd_finalize,
256     .class_init = char_fd_class_init,
257     .abstract = true,
258 };
259 
260 static void register_types(void)
261 {
262     type_register_static(&char_fd_type_info);
263 }
264 
265 type_init(register_types);
266