xref: /openbmc/qemu/chardev/char-pty.c (revision 10df8ff1) 
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 "qapi/error.h"
26 #include "qemu-common.h"
27 #include "chardev/char.h"
28 #include "io/channel-file.h"
29 #include "qemu/sockets.h"
30 #include "qemu/error-report.h"
31 
32 #include "chardev/char-io.h"
33 
34 typedef struct {
35     Chardev parent;
36     QIOChannel *ioc;
37     int read_bytes;
38 
39     /* Protected by the Chardev chr_write_lock.  */
40     int connected;
41     GSource *timer_src;
42     GSource *open_source;
43 } PtyChardev;
44 
45 #define PTY_CHARDEV(obj) OBJECT_CHECK(PtyChardev, (obj), TYPE_CHARDEV_PTY)
46 
47 static void pty_chr_update_read_handler_locked(Chardev *chr);
48 static void pty_chr_state(Chardev *chr, int connected);
49 
50 static void pty_chr_timer_cancel(PtyChardev *s)
51 {
52     if (s->timer_src) {
53         g_source_destroy(s->timer_src);
54         g_source_unref(s->timer_src);
55         s->timer_src = NULL;
56     }
57 }
58 
59 static void pty_chr_open_src_cancel(PtyChardev *s)
60 {
61     if (s->open_source) {
62         g_source_destroy(s->open_source);
63         g_source_unref(s->open_source);
64         s->open_source = NULL;
65     }
66 }
67 
68 static gboolean pty_chr_timer(gpointer opaque)
69 {
70     struct Chardev *chr = CHARDEV(opaque);
71     PtyChardev *s = PTY_CHARDEV(opaque);
72 
73     qemu_mutex_lock(&chr->chr_write_lock);
74     pty_chr_timer_cancel(s);
75     pty_chr_open_src_cancel(s);
76     if (!s->connected) {
77         /* Next poll ... */
78         pty_chr_update_read_handler_locked(chr);
79     }
80     qemu_mutex_unlock(&chr->chr_write_lock);
81     return FALSE;
82 }
83 
84 /* Called with chr_write_lock held.  */
85 static void pty_chr_rearm_timer(Chardev *chr, int ms)
86 {
87     PtyChardev *s = PTY_CHARDEV(chr);
88     char *name;
89 
90     pty_chr_timer_cancel(s);
91     name = g_strdup_printf("pty-timer-%s", chr->label);
92     s->timer_src = qemu_chr_timeout_add_ms(chr, ms, pty_chr_timer, chr);
93     g_source_set_name(s->timer_src, name);
94     g_free(name);
95 }
96 
97 /* Called with chr_write_lock held.  */
98 static void pty_chr_update_read_handler_locked(Chardev *chr)
99 {
100     PtyChardev *s = PTY_CHARDEV(chr);
101     GPollFD pfd;
102     int rc;
103     QIOChannelFile *fioc = QIO_CHANNEL_FILE(s->ioc);
104 
105     pfd.fd = fioc->fd;
106     pfd.events = G_IO_OUT;
107     pfd.revents = 0;
108     do {
109         rc = g_poll(&pfd, 1, 0);
110     } while (rc == -1 && errno == EINTR);
111     assert(rc >= 0);
112 
113     if (pfd.revents & G_IO_HUP) {
114         pty_chr_state(chr, 0);
115     } else {
116         pty_chr_state(chr, 1);
117     }
118 }
119 
120 static void pty_chr_update_read_handler(Chardev *chr)
121 {
122     qemu_mutex_lock(&chr->chr_write_lock);
123     pty_chr_update_read_handler_locked(chr);
124     qemu_mutex_unlock(&chr->chr_write_lock);
125 }
126 
127 /* Called with chr_write_lock held.  */
128 static int char_pty_chr_write(Chardev *chr, const uint8_t *buf, int len)
129 {
130     PtyChardev *s = PTY_CHARDEV(chr);
131 
132     if (!s->connected) {
133         /* guest sends data, check for (re-)connect */
134         pty_chr_update_read_handler_locked(chr);
135         if (!s->connected) {
136             return len;
137         }
138     }
139     return io_channel_send(s->ioc, buf, len);
140 }
141 
142 static GSource *pty_chr_add_watch(Chardev *chr, GIOCondition cond)
143 {
144     PtyChardev *s = PTY_CHARDEV(chr);
145     if (!s->connected) {
146         return NULL;
147     }
148     return qio_channel_create_watch(s->ioc, cond);
149 }
150 
151 static int pty_chr_read_poll(void *opaque)
152 {
153     Chardev *chr = CHARDEV(opaque);
154     PtyChardev *s = PTY_CHARDEV(opaque);
155 
156     s->read_bytes = qemu_chr_be_can_write(chr);
157     return s->read_bytes;
158 }
159 
160 static gboolean pty_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
161 {
162     Chardev *chr = CHARDEV(opaque);
163     PtyChardev *s = PTY_CHARDEV(opaque);
164     gsize len;
165     uint8_t buf[CHR_READ_BUF_LEN];
166     ssize_t ret;
167 
168     len = sizeof(buf);
169     if (len > s->read_bytes) {
170         len = s->read_bytes;
171     }
172     if (len == 0) {
173         return TRUE;
174     }
175     ret = qio_channel_read(s->ioc, (char *)buf, len, NULL);
176     if (ret <= 0) {
177         pty_chr_state(chr, 0);
178         return FALSE;
179     } else {
180         pty_chr_state(chr, 1);
181         qemu_chr_be_write(chr, buf, ret);
182     }
183     return TRUE;
184 }
185 
186 static gboolean qemu_chr_be_generic_open_func(gpointer opaque)
187 {
188     Chardev *chr = CHARDEV(opaque);
189     PtyChardev *s = PTY_CHARDEV(opaque);
190 
191     s->open_source = NULL;
192     qemu_chr_be_event(chr, CHR_EVENT_OPENED);
193     return FALSE;
194 }
195 
196 /* Called with chr_write_lock held.  */
197 static void pty_chr_state(Chardev *chr, int connected)
198 {
199     PtyChardev *s = PTY_CHARDEV(chr);
200 
201     if (!connected) {
202         pty_chr_open_src_cancel(s);
203         remove_fd_in_watch(chr);
204         s->connected = 0;
205         /* (re-)connect poll interval for idle guests: once per second.
206          * We check more frequently in case the guests sends data to
207          * the virtual device linked to our pty. */
208         pty_chr_rearm_timer(chr, 1000);
209     } else {
210         pty_chr_timer_cancel(s);
211         if (!s->connected) {
212             g_assert(s->open_source == NULL);
213             s->open_source = g_idle_source_new();
214             s->connected = 1;
215             g_source_set_callback(s->open_source,
216                                   qemu_chr_be_generic_open_func,
217                                   chr, NULL);
218             g_source_attach(s->open_source, chr->gcontext);
219         }
220         if (!chr->gsource) {
221             chr->gsource = io_add_watch_poll(chr, s->ioc,
222                                                pty_chr_read_poll,
223                                                pty_chr_read,
224                                                chr, chr->gcontext);
225         }
226     }
227 }
228 
229 static void char_pty_finalize(Object *obj)
230 {
231     Chardev *chr = CHARDEV(obj);
232     PtyChardev *s = PTY_CHARDEV(obj);
233 
234     qemu_mutex_lock(&chr->chr_write_lock);
235     pty_chr_state(chr, 0);
236     object_unref(OBJECT(s->ioc));
237     pty_chr_timer_cancel(s);
238     qemu_mutex_unlock(&chr->chr_write_lock);
239     qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
240 }
241 
242 static void char_pty_open(Chardev *chr,
243                           ChardevBackend *backend,
244                           bool *be_opened,
245                           Error **errp)
246 {
247     PtyChardev *s;
248     int master_fd, slave_fd;
249     char pty_name[PATH_MAX];
250     char *name;
251 
252     master_fd = qemu_openpty_raw(&slave_fd, pty_name);
253     if (master_fd < 0) {
254         error_setg_errno(errp, errno, "Failed to create PTY");
255         return;
256     }
257 
258     close(slave_fd);
259     qemu_set_nonblock(master_fd);
260 
261     chr->filename = g_strdup_printf("pty:%s", pty_name);
262     error_printf("char device redirected to %s (label %s)\n",
263                  pty_name, chr->label);
264 
265     s = PTY_CHARDEV(chr);
266     s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd));
267     name = g_strdup_printf("chardev-pty-%s", chr->label);
268     qio_channel_set_name(QIO_CHANNEL(s->ioc), name);
269     g_free(name);
270     s->timer_src = NULL;
271     *be_opened = false;
272 }
273 
274 static void char_pty_class_init(ObjectClass *oc, void *data)
275 {
276     ChardevClass *cc = CHARDEV_CLASS(oc);
277 
278     cc->open = char_pty_open;
279     cc->chr_write = char_pty_chr_write;
280     cc->chr_update_read_handler = pty_chr_update_read_handler;
281     cc->chr_add_watch = pty_chr_add_watch;
282 }
283 
284 static const TypeInfo char_pty_type_info = {
285     .name = TYPE_CHARDEV_PTY,
286     .parent = TYPE_CHARDEV,
287     .instance_size = sizeof(PtyChardev),
288     .instance_finalize = char_pty_finalize,
289     .class_init = char_pty_class_init,
290 };
291 
292 static void register_types(void)
293 {
294     type_register_static(&char_pty_type_info);
295 }
296 
297 type_init(register_types);
298