chardev/char-pty.c

   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);